optical chain for switchable directional screen

专利摘要:
A privacy screen comprising a space light modulator and a switchable compensated liquid crystal retarder arranged between the first and second polarizers arranged in series with the space light modulator. In a private mode of operation, the light within the geometric axis of the spatial light modulator is directed without loss, while the light outside the geometric axis has reduced luminance. The visibility of the screen for onlookers outside the geometric axis is reduced by reducing the luminance over a wide polar field. In a wide-angle operating mode, the switchable liquid crystal delay is adjusted so that the luminance outside the geometric axis is substantially unchanged.
公开号:BR112020005126A2
申请号:R112020005126-8
申请日:2018-09-14
公开日:2020-09-15
发明作者:Michael G. Robinson；Graham J. Woodgate；Robert A. Ramsey；Jonathan Harrold
申请人:Reald Spark, Llc；
IPC主号:

专利说明:

[0001] [0001] This disclosure refers generally to lighting from light modulating devices, and more specifically it refers to switchable optical chains to provide lighting control for use on a screen including a privacy screen (filter or film). BACKGROUND
[0002] [0002] Privacy screens provide image visibility to a primary user who is typically in a position within the geometry axis and reduced visibility of image content to a curious person who is typically in a position outside the geometry axis. A privacy function can be provided by optical films with microdeflectors that transmit some light from a screen in a direction within the geometry axis with low luminance in positions outside the geometry axis. However, such films have high losses of frontal illumination and microdeflectors can cause Moiré artifacts due to the pattern of interference with the pixels of the spatial light modulator. It may be necessary to select the microdeflector pitch for panel resolution, increasing inventory and cost.
[0003] [0003] Switchable privacy screens can be provided by controlling the optical output outside the geometric axis.
[0004] [0004] Control can be provided by reducing luminance, for example by switchable backlighting for a liquid crystal display (LCD, liquid crystal display) light modulator. The screen backlights, in general, employ waveguides and edge emission sources. Certain directional imaging backlights have the added ability to direct illumination through a display panel into viewing windows. An image formation system can be formed between the multiple sources and the respective images in the window. An example of directional imaging backlighting is an optical valve that can employ a folded optical system and therefore can also be an example of a folded directional imaging backlight. The light can propagate substantially without loss in one direction through the optical valve, while the counter-propagation light can be extracted by reflection of inclined facets, as described in US Patent No. 9,519,153, which is incorporated herein by reference in its entirety.
[0005] [0005] Privacy control outside the geometric axis can be additionally provided by reducing the contrast, for example by adjusting the slope of the liquid crystal on an LCD with switching in the plane. BRIEF SUMMARY
[0006] [0006] In accordance with a first aspect of the present disclosure, a display device is provided which comprises: a spatial light modulator; a screen polarizer arranged on one side of the space light modulator; an additional polarizer arranged on the same side of the space light modulator as the screen polarizer; and multiple retarders arranged between the additional polarizer and the screen polarizer; the multiple retarders comprising: a switchable liquid crystal retarder comprising a layer of liquid crystal material disposed between the screen polarizer and the additional polarizer; and at least one passive compensation retarder.
[0007] [0007] The multiple retarders can be arranged so as not to affect the luminance of the light that passes through the screen polarizer, the additional polarizer and the multiple retarders along a geometric axis along the normal to the plane of the retarders, and / or reduce the luminance of the light that passes through the screen polarizer, the additional polarizer and the multiple retarders along an inclined geometric axis relative to the normal plane of the retarders.
[0008] [0008] The at least one passive compensation retarder can be arranged to not introduce any phase shift in the polarization components of the light that passed through one of the screen polarizer and the additional polarizer on the input side of the multiple retarders along a geometric axis along normal to the plane of at least one passive compensation retarder, and / or to introduce a phase shift in the polarization components of the light that passed through one of the screen polarizer and the additional polarizer on the input side of multiple retarders along an inclined geometric axis relative to the normal plane of at least one passive compensating retarder.
[0009] [0009] The switchable liquid crystal retarder can be arranged not to introduce any phase shift in the polarization components of the light that has passed through one of the screen polarizer and the additional polarizer on the input side of the multiple retarders along an axis geometric along the normal to the plane of the switchable liquid crystal retarder, and / or to introduce a phase shift in the polarization components of the light that passed through one of the screen polarizer and the additional polarizer on the input side of the multiple retarders to the along an inclined geometric axis relative to normal to the plane of the switchable liquid-retardant in a switchable state of the liquid-retardant.
[0010] [0010] Advantageously, a switchable privacy screen can be provided that can be switched between a wide-angle operational state and a private operational state. The field of view for operation in private mode can be extended in comparison to known arrangements, and lower luminance levels outside the geometric axis can be obtained by increasing the degree of privacy observed by a curious outside the geometric axis. In addition, luminance outside the geometric axis can be maintained in both wide and private angle operating states for primary users within the geometric axis.
[0011] [0011] The screen polarizer and the additional polarizer can have electrical vector transmission directions that are parallel.
[0012] [0012] In an alternative, the switchable liquid crystal retarder may comprise two layers of surface alignment disposed adjacent to the layer of liquid crystal material and on opposite sides thereof, and each arranged to provide homeotropic alignment in the material of adjacent liquid crystal. The liquid crystal material layer of the switchable liquid crystal retarder may comprise a liquid crystal material with a negative dielectric anisotropy. The layer of liquid crystal material may have a light delay of a wavelength of 550 nm in a range from 500 nm to 1000 nm, preferably in a range of 600 nm to 900 nm, and most preferably in a range 700 nm to 850 nm range.
[0013] [0013] Where two layers of surface alignment providing homeotropic alignment are provided, the at least one passive compensation retarder may comprise a retarder that has its optical axis perpendicular to the plane of the retarder, the at least one passive retarder having a delay for light of a wavelength of 550 nm in the range of -300 nm to -900 nm, preferably in the range of -450 nm to -800 nm, and most preferably in the range of -500 nm to -725 nm .
[0014] [0014] Alternatively, where two layers of surface alignment providing homeotropic alignment are provided, the at least one passive compensating retarder may comprise a pair of retarders that have optical axes in the plane of the retarders that are crossed, with each retarder in the pair of retarders has a light delay of a wavelength of 550 nm in a range of 300 nm to 800 nm, preferably in a range of 500 nm to 700 nm, and most preferably in a range of 550 nm to 675 nm. Advantageously, in this case, an increased field of view in the wide angle operating mode can be provided. In addition, a zero voltage operation in the wide angle operating mode can be provided, reducing energy consumption.
[0015] [0015] In another alternative, the switchable liquid crystal retarder may comprise two layers of surface alignment disposed adjacent to the layer of liquid crystal material and on opposite sides thereof, and each arranged to provide homogeneous alignment in the material of adjacent liquid crystal. Advantageously, compared to homeotropic alignment on opposite sides of the liquid crystal, increased resilience to the visibility of the flow of liquid crystal material during the applied pressure can be achieved.
[0016] [0016] The liquid crystal material layer of the switchable liquid crystal retarder may comprise a liquid crystal material with a positive dielectric anisotropy. The layer of liquid crystal material may have a light delay of a wavelength of 550 nm in a range from 500 nm to 900 nm, preferably in a range of 600 nm to 850 nm, and most preferably in a range range from 700 nm to 800 nm.
[0017] [0017] Where two layers of surface alignment providing homogeneous alignment are provided, the at least one passive compensation retarder may comprise a retarder that has its optical axis perpendicular to the plane of the retarder, the at least one passive retarder having a delay for light of a wavelength of 550 nm in a range of -300 nm to -700 nm, preferably in a range of -350 nm to -600 nm, and most preferably in a range of -400 nm to -500 nm .
[0018] [0018] Alternatively, where the two layers of surface alignment providing homogeneous alignment are provided, the at least one passive compensation retarder may comprise a pair of retarders that have optical axes in the plane of the retarders that are crossed, each retardant being pair of retarders has a light delay of a wavelength of 550 nm in a range of 300 nm to 800 nm, preferably in a range of 350 nm to 650 nm, and most preferably in a range of 450 nm to 550 nm. Advantageously, in this case, increased resilience to the visibility of the flow of liquid crystal material during the applied pressure can be achieved.
[0019] [0019] In another alternative, the switchable liquid crystal retarder may comprise two layers of surface alignment disposed adjacent to the layer of liquid crystal material and on opposite sides thereof, one of the layers of surface alignment being arranged to provide homeotropic alignment in the adjacent liquid crystal material and the other surface alignment layer arranged to provide homogeneous alignment in the adjacent liquid crystal material.
[0020] [0020] When the surface alignment layer arranged to provide homogeneous alignment is between the layer of liquid crystal material and the compensation retardant, the layer of liquid crystal material may have a light delay of a wavelength of 550 nm in a range from 700 nm to 2000 nm, preferably in a range from 1000 nm to 1500 nm, and most preferably from 1200 nm to 1500 nm.
[0021] [0021] When the surface alignment layer arranged to provide homogeneous alignment is located between the layer of liquid crystal material and the compensation retarder, the at least one passive compensation retarder may comprise a retarder that has its optical axis perpendicular at the plane of the retarder, the at least one passive retarder having a light delay of a wavelength of 550 nm in the range of -400 nm to -1800 nm, preferably in the range of -700 nm to -1500 nm, and most preferably in the range of -900 nm to -1300 nm.
[0022] [0022] When the surface alignment layer arranged to provide homogeneous alignment lies between the layer of liquid crystal material and the compensating retarder, the at least one passive compensating retarder may comprise a pair of retarders having optical axes in the plane of the intersecting retarders, each retarder of the pair of retarders having a light delay of a wavelength of 550 nm in a range from 400 nm to 1800 nm, preferably in a range of 700 nm to 1500 nm, and with maximum preference in a range from 900 nm to 1300 nm.
[0023] [0023] When the surface alignment layer arranged to provide homeotropic alignment is between the liquid crystal material layer and the compensation retardant, the liquid crystal material layer may have a light delay of a wavelength of 550 nm in a range from 500 nm to 1800 nm, preferably in a range from 700 nm to 1500 nm, and most preferably from 900 nm to 1350 nm.
[0024] [0024] When the surface alignment layer arranged to provide homeotropic alignment lies between the layer of liquid crystal material and the compensation retardant, the at least one passive compensation retarder may comprise a retarder that has its optical axis perpendicular in the plane of the retarder, the at least one passive retarder having a light delay of a wavelength of 550 nm in the range of -300 nm to -1600 nm, preferably in the range of -500 nm to -1300 nm, and most preferably in the range of -700 nm to -1150 nm.
[0025] [0025] When the surface alignment layer arranged to provide homeotropic alignment is located between the layer of liquid crystal material and the compensation retarder, the at least one passive compensation retarder may comprise a pair of retarders that have optical axes in the plane of the intersecting retarders, each retarder in the pair of retarders having a light delay of a wavelength of 550 nm in a range from 400 nm to 1600 nm, preferably in a range of 600 nm to 1400 nm, and with maximum preference in a range of 800 nm to 1300 nm. Advantageously, in this case, increased resilience to the visibility of the flow of liquid crystal material during the applied pressure can be achieved.
[0026] [0026] Each alignment layer can have a pre-slope that has a pre-slope direction with a component in the plane of the liquid crystal layer that is parallel or antiparallel or orthogonal to the direction of the vector transmission of the screen polarizer. Advantageously, a screen can be provided with a narrow viewing angle in a lateral direction and ample viewing freedom for rotation of the screen around a horizontal geometric axis. Such a screen can be comfortable to see for a user in front of the screen and difficult to see for a user outside the geometric axis of the screen.
[0027] [0027] The at least one passive retarder may comprise at least two passive retarders with at least two different orientations of optical axes that may have optical axes in the plane of the intersecting retarders. The field of view for homogeneously aligned liquid crystal retarders is increased while providing resilience to the visibility of liquid crystal material flow during applied pressure.
[0028] [0028] The pair of passive retarders may have optical axes that extend at 45 ° and 135 °, respectively, in relation to an electric vector transmission direction that is parallel to the screen polarizer electric vector transmission. Passive retarders can be supplied using stretched films to advantageously achieve low cost and high uniformity.
[0029] [0029] The switchable liquid crystal retarder can be provided between the pair of passive retarders. Advantageously, the thickness and complexity of the multiple retarders can be reduced.
[0030] [0030] A transparent electrode and a liquid crystal alignment layer can be formed on one side of each of the pair of passive retarders adjacent to the switchable liquid crystal retarder; and may additionally comprise a first and a second substrate between which the switchable liquid crystal retarder is provided, the first and second substrates each comprising one of the pair of passive retarders, with each of the pair passive retarders have a light delay of a wavelength of 550 nm in a range of 150 nm to 800 nm, preferably in a range of 200 nm to 700 nm, and most preferably in a range of 250 nm to 600 nm.
[0031] [0031] In an alternative, the at least one passive compensation retarder may comprise a retarder that has an optical axis perpendicular to the plane of the retarder. Advantageously, the thickness and complexity of the chain of passive retarders can be reduced.
[0032] [0032] The at least one passive compensation retarder may comprise two passive retarders that have an optical axis perpendicular to the plane of the passive retarders, and the switchable liquid crystal retarder is provided between the two passive retarders. Advantageously, the thickness and complexity of the multiple retarders can be reduced. High frontal efficiency can be achieved in both wide and private modes, a wide field of view for wide-angle mode and onlookers may be unable to perceive image data from a wide range of off-axis observation locations geometric.
[0033] [0033] A transparent electrode and a liquid crystal alignment layer can be formed on one side of each of the two passive retarders adjacent to the switchable liquid crystal retarder. A first and a second substrate between which the switchable liquid crystal retarder can be provided, the first and second substrates each comprising one of the two passive retarders. The two passive retarders can have a total delay
[0034] [0034] for light with a wavelength of 550 nm in the range of -300 nm to -700 nm, preferably in the range of -350 nm to -600 nm, and most preferably in the range of -400 nm to -500 nm.
[0035] [0035] In another alternative, the at least one passive compensation retarder may comprise a retarder that has an optical axis with a component perpendicular to the plane of the retarder and with a component in the plane of the retarder. Advantageously, the fields of view in wide-angle mode can be enlarged and curious people may be unable to perceive image data from a wide range of observation locations outside the geometric axis.
[0036] [0036] The component in the passive retarder plane can extend to 0 °, in relation to an electric vector transmission direction that is parallel or perpendicular to the electric vector transmission of the screen polarizer. The at least one passive retarder may additionally comprise a passive retarder that has an optical axis perpendicular to the plane of the passive retarder or a pair of passive retarders that have optical axes in the plane of the intersecting passive retarders.
[0037] [0037] The delay of at least one passive compensation retarder can be equal and opposite to the delay of the switchable liquid crystal retarder.
[0038] [0038] The switchable liquid crystal retarder can comprise a first and a second pre-slope; and the at least one passive compensation retarder may comprise a compensation retarder with a first and a second pre-slope, the first pre-slope of the compensation retarder being equal to the first pre-slope of the liquid crystal retarder, and the second pre-slope of the compensation retarder being the same as the second pre-slope of the liquid crystal
[0039] [0039] The switchable liquid crystal retarder may additionally comprise electrodes arranged to apply a voltage to control the layer of liquid crystal material. The electrodes can be on opposite sides of the liquid crystal material layer. The screen can be switched by controlling the liquid crystal layer, advantageously achieving a switchable privacy screen, or another screen with reduced diffused light outside the geometric axis. The screen may further comprise a control system arranged to control the voltage applied to the electrodes of at least one switchable liquid crystal retarder.
[0040] [0040] The electrodes can be standardized to provide at least two standard regions. Advantageously, the increased privacy performance can be provided by hiding the image data. The screen can be switched between a wide angle mode with no visibility of the camouflage structure and a private mode with additional camouflage to provide reduced visibility to a curious off-axis without substantial visibility of the camouflage pattern to a frontal user.
[0041] [0041] The control system can additionally comprise a means to determine the location of a curious in relation to the screen and the control system is arranged to adjust the voltage applied to the electrodes of at least one switchable liquid crystal retardant in response to the location of the curious. Advantageously, the visibility of an image to a detected onlooker can be minimized to a range of locations of the onlooker.
[0042] [0042] The display device may additionally comprise at least one additional retarder and one additional polarizer, the at least one additional retarder being disposed between the first mentioned additional polarizer and the other additional polarizer. Advantageously, the luminance outside the geometric axis can be reduced even further, reducing the visibility of the image to a curious outside the geometric axis.
[0043] [0043] In an alternative to the display device, the spatial light modulator is a transmissive spatial light modulator willing to receive the light emitted from a backlight. Advantageously, the backlight can provide reduced luminance outside the geometric axis in comparison to emissive screens.
[0044] [0044] The backlight can provide, at polar angles with normal to the spatial light modulator greater than 45 degrees, a luminance that is at most 33% of the luminance over normal to the spatial light modulator, preferably at most 20% from luminance along the normal to the spatial light modulator, and with maximum preference at most 10% of the luminance along the normal to the spatial light modulator. Advantageously, the luminance can be reduced for onlookers outside the geometric axis.
[0045] [0045] The backlight can comprise: an array of light sources; a directional waveguide comprising: an entrance end that extends in a lateral direction along one side of the directional waveguide, the light sources being arranged along the entrance end and arranged to insert light from entry in the waveguide; and an opposing first and second guide surfaces extending through the directional waveguide from the inlet end to guide the entry of light into the inlet end along the waveguide, the waveguide being arranged to deflect the entry light guided through the directional waveguide to exit through the first guide surface. Advantageously, wide and uniform area lighting can be provided with high efficiency.
[0046] [0046] The backlight can additionally comprise a reflective film and the directional waveguide is a collimation waveguide. The collimation waveguide can comprise (i) a plurality of elongated lenticular elements; and (ii) a plurality of inclined light extraction resources, the plurality of elongated lenticular elements and the plurality of inclined light extraction resources are oriented to deflect the incoming light guided through the directional waveguide to exit through the first guide surface. Advantageously, a narrow angled outlet can be provided by the backlight.
[0047] [0047] The directional waveguide can be an imaging waveguide arranged to imagine the light sources in the lateral direction so that the light emitted from the light sources is directed to the respective optical windows in directions of exit that are distributed based on the input positions of the light sources. The imaging waveguide may comprise a reflective end to reflect the incoming light back along the imaging waveguide, the second guide surface being arranged to deflect the reflected input light through the first guide surface. like the output light, the second guide surface comprises light extraction features and intermediate regions between the light extraction features, and the light extraction features are oriented to deflect the incoming light reflected through the first light surface. guide as an exit light and the intermediate regions are arranged to direct the light through the waveguide without extracting it; and the reflective end may have a positive optical power in the lateral direction extending between the sides of the waveguide extending between the first and the second guide surfaces.
[0048] [0048] Advantageously, switchable directional lighting can be provided that can be switched between narrow-angle and wide-angle lighting.
[0049] [0049] In an alternative where the space light modulator is a transmissive space light modulator, the screen polarizer can be an input screen polarizer arranged on the input side of the space light modulator between the backlight and the light modulator space, and the additional polarizer is arranged between the input screen polarizer and the backlight. Advantageously, the efficiency of the screen is increased. The additional polarizer can be a reflective polarizer.
[0050] [0050] In this case, the display device may additionally comprise an output polarizer arranged on the output side of the space light modulator.
[0051] [0051] In an alternative where the space light modulator is a transmissive space light modulator, the screen polarizer can be an output polarizer arranged on the output side of the space light modulator. Advantageously, the efficiency of the screen is increased.
[0052] [0052] The display device may additionally comprise an input polarizer arranged on the input side of the space light modulator.
[0053] [0053] The display device may additionally comprise another additional polarizer disposed on the input side of the space light modulator and at least one additional retarder disposed between the at least one additional polarizer and the input polarizer. Advantageously, the luminance can be reduced for onlookers outside the geometric axis.
[0054] [0054] In an alternative to the display device, the spatial light modulator may comprise an emissive spatial light modulator arranged to emit light. In this case, the screen polarizer can be an output screen polarizer arranged on the output side of the emissive spatial light modulator. Advantageously, the screen thickness can be reduced compared to backlit screens, and flexible and foldable screens can be conveniently supplied.
[0055] [0055] The display device may comprise at least one additional retarder and another additional polarizer, the at least one additional retarder being disposed between the first mentioned additional polarizer and the other additional polarizer. Advantageously, the luminance can be reduced for onlookers outside the geometric axis.
[0056] [0056] The various optional and alternative features set out above in relation to the first aspect of the present invention can be applied together in any combination.
[0057] [0057] In accordance with a second aspect of the present disclosure, an optical element of viewing angle control is provided for application to a display device, which comprises a spatial light modulator and a screen polarizer arranged on one side of the modulator. spatial light, the viewing angle control optical element comprising a control polarizer and multiple retarders for arrangement between the additional polarizer and the screen polarizer when applying the viewing angle control optical element to the display device, the multiple retarders comprising: a switchable liquid crystal retarder comprising a layer of liquid crystal material; and at least one passive compensation retarder.
[0058] [0058] Advantageously, the viewing angle control optical element can be distributed as an after-sales element and can be attached to display devices by screen users. The element does not require complex alignment. The Moiré interference pattern between the element and the screen pixels is not present and the selection of the component in relation to the distance between pixels is not necessary. Inventory costs are reduced.
[0059] [0059] Alternatively, the optical viewing angle control element can be conveniently installed by the factory on display devices.
[0060] [0060] The various resources and alternatives set out above in relation to the first aspect of the present disclosure can also be applied to the second aspect of the present disclosure.
[0061] [0061] The modalities of the present disclosure can be used in a variety of optical systems. The modalities may include or work with a variety of projectors, projection systems, optical components, screens, microtels, computer systems, processors, self-contained projection systems, visual and / or audiovisual systems, and optical and / or electrical devices. Aspects of the present disclosure can be used with virtually any device related to optical and electrical devices, optical systems, presentation systems, or any device that may contain any type of optical system. Consequently, the modalities of the present disclosure can be used in optical systems, devices used in visual and / or optical presentations, visual peripherals, etc., and in countless computing environments.
[0062] [0062] Before considering in detail the modalities presented, it must be understood that the revelation is not limited to its application or creation to the details of specific provisions shown, because the revelation is capable of other modalities. In addition, aspects of disclosure can be defined in different combinations and arrangements to define unique modalities by themselves. In addition, the terminology used in the present invention is for the purpose of description and not limitation.
[0063] [0063] These and other advantages and characteristics of the present disclosure will be evident to those skilled in the art by reading this disclosure in its entirety. BRIEF DESCRIPTION OF THE DRAWINGS
[0064] [0064] The modalities are illustrated by way of example in the attached figures, in which similar reference numbers indicate similar parts, and in which:
[0065] [0065] Figure 1A is a schematic diagram illustrating a side perspective view of an optical chain of a directional display device comprising a switchable front retarder;
[0066] [0066] Figure 1B is a schematic diagram illustrating a front view of the alignment of the optical layers in the optical chain of Figure 1A;
[0067] [0067] Figure 1C is a schematic diagram illustrating a side perspective view of an optical chain of a directional display device comprising an emissive space light modulator and a switchable compensated retarder arranged on the output side of the space light modulator emissive;
[0068] [0068] Figure 1D is a schematic diagram illustrating a side perspective view of an optical angle-of-view control element comprising a passive compensation retarder, a switchable liquid crystal retarder and a control polarizer;
[0069] [0069] Figure 2A is a schematic diagram illustrating a side perspective view of an optical chain of a directional display device comprising a backlight, a rear switchable compensated retarder and a transmissive spatial light modulator, the additional polarizer being comprises a reflective polarizer;
[0070] [0070] Figure 2B is a schematic diagram illustrating a front view of the alignment of the optical layers in the optical chain of Figure 2A;
[0071] [0071] Figure 2C is a schematic diagram illustrating a side perspective view of an optical chain of a directional display device comprising a backlight, a rear switchable compensated retarder, and a transmissive spatial light modulator, the polarizer being additional comprises a dichroic polarizer;
[0072] [0072] Figure 3 is a schematic diagram illustrating a side view of an arrangement of a switchable compensated liquid crystal retarder;
[0073] [0073] Figure 4A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder comprising a negative plate C in a wide angle operating mode;
[0074] [0074] Figure 4B is a schematic diagram that illustrates a graph of the steering angle against fractional location of the liquid crystal through the switchable liquid crystal retarding cell;
[0075] [0075] Figure 4C is a schematic diagram illustrating a side view of the propagation of the output light from a spatial light modulator through the optical chain of Figure 4A in a wide angle operation mode;
[0076] [0076] Figure 4D is a schematic graph that illustrates the variation of the output transmission with polar directions for the light rays transmitted in Figure 4C;
[0077] [0077] Figure 5A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder comprising a negative plate C in a private mode of operation;
[0078] [0078] Figure 4C is a schematic diagram illustrating a side view of the propagation of output light from a spatial light modulator through the optical chain of Figure 5A in a private mode of operation;
[0079] [0079] Figure 5C is a schematic graph that illustrates the variation of the output transmission with polar directions for the light rays transmitted in Figure 5B;
[0080] [0080] Figure 6A is a schematic diagram illustrating a front perspective view of the output light transmitted to a screen operating in private mode;
[0081] [0081] Figure 6B is a schematic diagram that illustrates frontal perspective views of the appearance of the screen of Figures 1A to 1C operating in private mode;
[0082] [0082] Figure 6C is a schematic diagram illustrating a side view of an automotive vehicle with a switchable directional screen arranged inside the vehicle's cabin for entertainment and sharing modes of operation;
[0083] [0083] Figure 6D is a schematic diagram illustrating a top view of an automotive vehicle with a switchable directional screen arranged inside the vehicle cabin in an entertainment operating mode;
[0084] [0084] Figure 6E is a schematic diagram illustrating a top view of an automotive vehicle with a switchable directional screen arranged inside the vehicle's cab in a sharing operation mode;
[0085] [0085] Figure 6F is a schematic diagram illustrating a top view of an automotive vehicle with a switchable directional screen arranged inside the vehicle's cabin for night and day operating modes;
[0086] [0086] Figure 6G is a schematic diagram illustrating a side view of an automotive vehicle with a switchable directional screen arranged inside the vehicle's cab in a night mode of operation;
[0087] [0087] Figure 6H is a schematic diagram illustrating a side view of an automotive vehicle with a switchable directional screen arranged inside the vehicle's cabin in a daytime mode of operation;
[0088] [0088] Figure 7A, Figure 7B, Figure 7C and Figure 7D are schematic diagrams that illustrate the variation of the output transmission with polar directions for different drive voltages;
[0089] [0089] Figure 8 is a flow chart illustrating the control of a privacy screen;
[0090] [0090] Figure 9A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a wide-angle operating mode comprising passive crossover A-plate compensating retarders and a switchable liquid crystal retarder homeotropically aligned;
[0091] [0091] Figure 9B is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a private mode of operation comprising passive crossover A-plate compensating retarders and a homeotropically aligned switchable liquid retardant ;
[0092] [0092] Figure 9C is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 9A in a wide angle operation mode;
[0093] [0093] Figure 9D is a schematic graph illustrating the variation of the output transmission with polar directions for light rays transmitted in Figure 9B in a private mode of operation;
[0094] [0094] Figure 10A and Figure 10B are schematic diagrams illustrating a side perspective view of an arrangement of a compensated retarder switchable in a wide angle mode and a private operating mode, respectively, comprising a liquid crystal retarder homogeneously aligned switchable and a passive negative plate C retarder;
[0095] [0095] Figure 10C is a schematic diagram illustrating a graph of the steering angle against fractional location of the liquid crystal through the switchable liquid crystal retardant cell of Figure 10A for different applied voltages;
[0096] [0096] Figure 11A, Figure 11B and Figure 11C are schematic graphs illustrating the variation of the output transmission with polar directions for light rays transmitted from the switchable compensated retarder comprising a homogeneously aligned liquid crystal cell and a C plate negative in a private mode, and for two different addressing drive voltages in wide angle mode, respectively;
[0097] [0097] Figure 12A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a private mode of operation comprising passive compensating retarders of crossed A plates and a switchable homogeneously aligned liquid crystal retarder ;
[0098] [0098] Figure 12B, Figure 12C and Figure 12D are schematic graphs that illustrate the variation of the output transmission with polar directions for light rays transmitted from the switchable compensated retarder comprising a homogeneously aligned liquid crystal cell and crossed A plates in a private mode and wide angle modes for different drive voltages;
[0099] [0099] Figure 13A and Figure 13B are schematic diagrams illustrating partial side views of a screen comprising a switchable compensated retarder and optical bonding layers;
[0100] [0100] Figure 14 is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a private mode of operation comprising passive compensating retarders of crossed A plates and a switchable homogeneously aligned liquid crystal retarder , further comprising a passive rotation retarder;
[0101] [0101] Figure 15A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a private mode of operation comprising a homeotropically aligned liquid crystal retarder disposed between the first and second compensation retarders. plate C liabilities;
[0102] [0102] Figure 15B and Figure 15C are schematic graphs illustrating the variation of output transmission with polar directions for light rays transmitted in the optical chain of Figure 15A in a wide angle mode and a private operating mode, respectively;
[0103] [0103] Figure 16A is a schematic diagram illustrating a side perspective view of a screen comprising a switchable liquid crystal retarder disposed between the first and second substrates, each comprising passive plate C compensation retarders;
[0104] [0104] Figure 16B is a schematic diagram illustrating a partial side view of a screen comprising a switchable liquid crystal retarder disposed between the first and second substrates, each comprising passive plate C compensation retarders;
[0105] [0105] Figure 17A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a wide angle operating mode comprising a homogeneously aligned liquid crystal retarder disposed between the first and the second retarders liabilities for crossed A plates;
[0106] [0106] Figure 17B and Figure 17C are schematic graphs that illustrate the variation of output transmission with polar directions for light rays transmitted to the arrangement of Figure 17A in wide and private angle modes, respectively;
[0107] [0107] Figure 18A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a private mode of operation comprising a homotropically aligned switchable liquid crystal retarder and a passive C plate retarder. negative;
[0108] [0108] Figure 18D is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 18A in a private mode of operation;
[0109] [0109] Figure 18C is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 18A in a wide angle operating mode;
[0110] [0110] Figure 19A is a schematic diagram showing a side perspective view of an evenly aligned switchable liquid crystal retarder arrangement;
[0111] [0111] Figure 19B is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 19A for a first applied voltage;
[0112] [0112] Figure 19C is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 19A for a second applied voltage that is greater than the first applied voltage;
[0113] [0113] Figure 19D is a schematic diagram showing a side perspective view of a plate C disposed between parallel polarizers;
[0114] [0114] Figure 19E is a schematic graph that illustrates the variation of the output transmission with polar directions for rays of light transmitted in Figure 19D;
[0115] [0115] Figure 20A is a schematic diagram illustrating a side perspective view of an arrangement of a homogeneously aligned switchable liquid crystal retarder arranged between parallel polarizers arranged in series with a plate C arranged between the parallel polarizers;
[0116] [0116] Figure 20B is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 20A for a first applied voltage;
[0117] [0117] Figure 20C is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 20A for a second applied voltage that is greater than the first applied voltage;
[0118] [0118] Figure 21A is a schematic diagram illustrating a side perspective view of an arrangement of a homogeneously aligned switchable liquid crystal retarder arranged in series with a C plate compensation retardant, with switchable liquid crystal retardants aligned. homogeneously and plate C compensation are arranged between a single pair of parallel polarizers;
[0119] [0119] Figure 21B is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 21A for a first applied voltage;
[0120] [0120] Figure 21C is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 21A for a second applied voltage that is greater than the first applied voltage;
[0121] [0121] Figure 22A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a private mode of operation comprising a passive negative plate C compensation retardant and an aligned switchable liquid crystal retarder homeotropically arranged between the output polarizer and the additional polarizer; and a passive negative plate C compensation retardant and a homeotropically aligned switchable liquid crystal retarder arranged between the first mentioned additional polarizer and the other additional polarizer in a private mode of operation;
[0122] [0122] Figure 22B is a schematic diagram illustrating a side perspective view of an arrangement of the first switchable compensated retarder at the entrance of a liquid crystal display and a second switchable compensated retarder arranged at the exit of a liquid crystal display;
[0123] [0123] Figure 22C is a schematic diagram illustrating a side perspective view of an optical angle of view control element comprising a first passive compensation retarder, a first switchable liquid crystal retarder, a first control polarizer, a second passive compensation retarder, a second switchable liquid crystal retarder and a second control polarizer;
[0124] [0124] Figure 22D is a schematic diagram illustrating a top view of an automotive vehicle with a switchable directional screen arranged inside the vehicle's cab for daytime and / or sharing modes;
[0125] [0125] Figure 22E is a schematic diagram that illustrates a side view of an automotive vehicle with a switchable directional screen arranged inside the vehicle cabin for daytime and / or sharing modes;
[0126] [0126] Figure 22F is a schematic diagram illustrating a top view of an automotive vehicle with a switchable directional screen arranged inside the vehicle's cabin for night and / or entertainment modes of operation;
[0127] [0127] Figure 22G is a schematic diagram illustrating a side view of an automotive vehicle with a switchable directional screen arranged inside the vehicle cabin for night and / or entertainment modes of operation;
[0128] [0128] Figure 23A is a schematic diagram illustrating a side perspective view of an arrangement of an additional reflective polarizer and a passive retarder arranged at the entrance of a liquid crystal display, and a switchable compensated retarder and an additional polarizer arranged on the output from a liquid crystal display;
[0129] [0129] Figure 23B is a schematic diagram illustrating a side perspective view of an optical viewing angle control element comprising a passive retarder, a first control polarizer, a passive compensation retarder, a liquid crystal retarder switchable and a second control polarizer;
[0130] [0130] Figure 24A is a schematic diagram illustrating a side perspective view of an optical chain of a passive retarder comprising a negative plate O slanted in a plane orthogonal to the direction of electrical transmission of the screen polarizer and a plate C negative, and willing to provide modification of the field of view of a display device;
[0131] [0131] Figure 24B is a schematic graph that illustrates the variation of the output transmission with polar directions for the light rays transmitted in Figure 24A;
[0132] [0132] Figure 24C is a schematic diagram illustrating a side perspective view of an optical chain of a passive retarder comprising crossed A plates and a positive O plate;
[0133] [0133] Figure 24D is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in the passive retarder of Figure 24C;
[0134] [0134] Figure 24E is a schematic diagram showing a side perspective view of an optical chain of a passive retarder comprising two pairs of crossed A plates;
[0135] [0135] Figure 24F is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in the passive retarder of Figure 24E;
[0136] [0136] Figure 25A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a private mode of operation comprising a passive negative plate C compensation retardant, and a switchable liquid crystal retarder homeotropically aligned which additionally comprises an electrode layer provided with a pattern;
[0137] [0137] Figure 25B is a schematic diagram that illustrates a frontal perspective view of the lighting of a primary observer and a curious one next to a private screen with camouflaged controlled luminance;
[0138] [0138] Figure 25C is a schematic diagram that illustrates a side perspective view of the lighting of a curious person next to a private screen with camouflaged controlled luminance;
[0139] [0139] Figure 26A is a schematic diagram that illustrates a front perspective view of a directional backlight;
[0140] [0140] Figure 26B is a schematic diagram that illustrates a front perspective view of a non-directional backlight;
[0141] [0141] Figure 26C is a schematic graph that illustrates a variation of luminance in side view angles of screens with different fields of view;
[0142] [0142] Figure 27A is a schematic diagram illustrating a side view of a switchable directional display apparatus comprising an imaging waveguide and a switchable liquid crystal retarder;
[0143] [0143] Figure 27B is a schematic diagram illustrating a rear perspective view of the operation of an imaging waveguide in a narrow angle operation mode;
[0144] [0144] Figure 27C is a schematic graph illustrating a luminance plot of the field of view of the Figure 27B output when used on a display device with no switchable liquid crystal retarder;
[0145] [0145] Figure 28A is a schematic diagram illustrating a side view of a switchable directional display apparatus comprising a switchable collimation waveguide and a switchable liquid crystal retarder operating in a private mode of operation;
[0146] [0146] Figure 28B is a schematic diagram illustrating a top view of the output of a collimation waveguide;
[0147] [0147] Figure 28C is a schematic graph that illustrates a polar plot of the iso-luminance field of view for the display apparatus of Figure 28A;
[0148] [0148] Figure 29A is a schematic diagram illustrating a perspective view of the illumination of a light-retardant layer outside the geometric axis;
[0149] [0149] Figure 29B is a schematic diagram illustrating a perspective view of the illumination of a light-retardant layer outside the axis of a first linear 0 degree polarization state;
[0150] [0150] Figure 29C is a schematic diagram illustrating a perspective view of the illumination of a light-retardant layer outside the geometric axis of a first 90 degree linear polarization state;
[0151] [0151] Figure 29D is a schematic diagram illustrating a perspective view of the illumination of a light-retardant layer outside the geometric axis of a first 45 degree linear polarization state;
[0152] [0152] Figure 30A is a schematic diagram showing a perspective view of the illumination of a plate C retarder by polarized light outside the geometric axis with a positive elevation;
[0153] [0153] Figure 30B is a schematic diagram illustrating a perspective view of the illumination of a plate C retarder by polarized light outside the geometric axis with a negative side angle;
[0154] [0154] Figure 30C is a schematic diagram illustrating a perspective view of the illumination of a plate C retarder by polarized light outside the geometric axis with a positive elevation and a negative side angle;
[0155] [0155] Figure 30D is a schematic diagram illustrating a perspective view of the illumination of a plate C retarder by polarized light outside the geometric axis with a positive elevation and a positive lateral angle;
[0156] [0156] Figure 30E is a schematic graph that illustrates the variation of the output transmission with polar directions for rays of light transmitted in Figures 30A to 30D;
[0157] [0157] Figure 31A is a schematic diagram illustrating a perspective view of the illumination of the layers of a plate retarder A crossed by polarized light outside the geometric axis with a positive elevation;
[0158] [0158] Figure 31B is a schematic diagram illustrating a perspective view of the illumination of the layers of a plate retarder A crossed by polarized light outside the geometric axis with a negative side angle;
[0159] [0159] Figure 31C is a schematic diagram illustrating a perspective view of the illumination of layers of a plate retarder A crossed by polarized light outside the geometric axis with a positive elevation and a negative side angle;
[0160] [0160] Figure 31D is a schematic diagram illustrating a perspective view of the illumination of the layers of a plate retarder A crossed by polarized light outside the geometric axis with a positive elevation and a positive lateral angle; and
[0161] [0161] Figure 31E is a schematic graph that illustrates the variation of the output transmission with polar directions for rays of light transmitted in Figures 31A to 31D. DETAILED DESCRIPTION
[0162] [0162] The terms related to optical retarders for the purposes of the present disclosure will now be described.
[0163] [0163] In a layer comprising uniaxial birefringent material, there is a direction that governs optical anisotropy, while all directions perpendicular to said layer (or at a given angle to it) have equivalent birefringence.
[0164] [0164] Optical axes refer to the direction of propagation of a ray of light in uniaxial birefringent material in which no birefringence is experienced for light that propagates in a direction orthogonal to the optical axis; the optical axis is the slow geometric axis when linearly polarized light with an electric vector direction parallel to the slow geometric axis moves at the slowest speed. The direction of the slow geometric axis is the direction with the highest refractive index in the design wavelength. Similarly, the direction of the fast geometric axis is the direction with the lowest refractive index in the design wavelength.
[0165] [0165] For uniaxial birefringent materials with positive dielectric anisotropy, the direction of the slow geometric axis is the extraordinary geometric axis of the birefringent material. For uniaxial birefringent materials with negative dielectric anisotropy, the direction of the fast geometric axis is the extraordinary geometric axis of the birefringent material.
[0166] [0166] The terms "half-wavelength" and "quarter-wavelength" refer to the operation of a retarder for a wavelength λ0 of the design that can typically be between 500 nm and 570 nm. In the present illustrative embodiments, exemplary delay values are provided for a wavelength of 550 nm, unless otherwise specified.
[0167] [0167] The retarder provides a phase shift between two polarization components perpendicular to the light wave incident on the retarder and is characterized by the amount of relative phase, Γ, which it gives to the two polarization components; which is related to Δn birefringence and retarder thickness d by the ratio
[0168] [0168] In equation 1, Δn is defined as the difference between the extraordinary and ordinary refractive indices, ie
[0169] [0169] For a half wave retarder, the relationship between d, Δn and λ 0 is chosen so that the phase shift between the polarization components is Γ = π. For a quarter-wave retarder, the relationship between d, Δn and λ0 is chosen so that the phase shift between the polarization components is Γ = π / 2.
[0170] [0170] The term "half-wave retardant" in the present invention typically refers to light that propagates in the direction normal to the retarder and normal to the spatial light modulator.
[0171] [0171] In the present disclosure, a 'plate A' refers to an optical retarder that uses a layer of birefringent material with its optical axis parallel to the plane (x-y) of the layer.
[0172] [0172] A 'positive A plate' refers to positively birefringent A plates, that is, A plates with a positive Δn.
[0173] [0173] In the present disclosure, a 'plate C' refers to an optical retarder that uses a layer of birefringent material with its optical axis perpendicular to the plane of the layer. A 'positive C plate' refers to a positively birefringent C plate, that is, a C plate with a positive Δn. A 'negative C plate' refers to a negatively birefringent C plate, that is, a C plate with a negative Δn.
[0174] [0174] An 'O plate' refers to an optical retarder that uses a layer of birefringent material with its optical axis having a component parallel to the plane of the layer and a component perpendicular to the plane of the layer. A 'positive O plate' refers to positively birefringent O plates, that is, O plates with a positive Δn.
[0175] [0175] Achromatic retarders can be supplied, with the retarder material having a Δn delay. d which varies with the wavelength λ according to the relation where κ is substantially a constant.
[0176] [0176] Examples of suitable materials include modified polycarbonates available from Teijin Films. Achromatic retarders can be provided in the present modalities to advantageously minimize color changes between polar angular observation directions that have low luminance reduction and polar angular observation directions that have increased luminance reductions as described below.
[0177] [0177] Several other terms used in the present disclosure related to retardants and liquid crystals will now be described.
[0178] [0178] A liquid crystal cell has a delay given by Δn. d where An is the birefringence of the liquid crystal material in the liquid crystal cell and d is the thickness of the liquid crystal cell, regardless of the alignment of the liquid crystal material in the liquid crystal cell.
[0179] [0179] Homogeneous alignment refers to the alignment of liquid crystals in switchable liquid crystal screens where the molecules align substantially in parallel to a substrate. Homogeneous alignment is sometimes called flat alignment. The homogeneous alignment can typically be provided with a small pre-slope such as 2 degrees, so that the molecules on the surfaces of the alignment layers of the liquid crystal cell are slightly inclined, as will be described below. The pre-inclination is arranged to minimize degeneration in the switching of cells.
[0180] [0180] In the present disclosure, homeotropic alignment is the state in which rod-shaped liquid crystal molecules align substantially perpendicular to the substrate. In discotic liquid crystals, homeotropic alignment is defined as the state in which a geometric axis of the column structure, which is formed by disc-like liquid crystal molecules, aligns perpendicularly to a surface. In homeotropic alignment, the pre-slope is the angle of inclination of the molecules that are close to the alignment layer and are typically close to 90 degrees and, for example, can be 88 degrees.
[0181] [0181] Liquid crystal molecules with positive dielectric anisotropy are switched from homogeneous alignment (as an orientation of plate A retarder) to a homeotropic alignment (as an orientation of plate C or plate retarder) by applying a field electric.
[0182] [0182] Liquid crystal molecules with negative dielectric anisotropy are switched from a homeotropic alignment (as an orientation of the plate C or plate O retarder) to a homogeneous alignment (as an orientation of the plate retarder A) by applying a field electric.
[0183] [0183] Rod-shaped molecules have a positive birefringence so that ne> n0, as described in equation 2. Discotic molecules have negative birefringence so that ne <n0.
[0184] [0184] Positive retarders such as A-plates, O-positive plates and C-positive plates can typically be supplied by stretched films or rod-shaped liquid crystal molecules. Negative retarders like those of negative C plates can be supplied by stretched films or disk-shaped liquid crystal molecules.
[0185] [0185] The parallel alignment of liquid crystal cells refers to the direction of alignment of the homogeneous alignment layers being parallel or more typically antiparallel. In the case of pre-inclined homeotropic alignment, the alignment layers may have components that are substantially parallel or antiparallel. Hybrid-aligned liquid crystal cells can have a homogeneous alignment layer and a homeotropic alignment layer. Twisted liquid crystal cells can be provided by alignment layers that do not have parallel alignment, for example oriented 90 degrees from each other.
[0186] [0186] Transmissive space light modulators may additionally comprise retarders between the input screen polarizer and the output screen polarizer, for example as disclosed in US Patent No. 8,237,876, which is incorporated herein by reference in its entirety. Such retarders (not shown) are located in different locations than the passive retarders of the present modalities. Such retarders compensate for contrast degradation for observation sites outside the geometric axis, which is a different effect than the reduction of luminance for observation positions outside the geometric axis of the present modalities.
[0187] [0187] The optical isolation retarders provided between the screen polarizer and an emission layer of the OLED screen are further described in US Patent No. 7,067,985. The optical isolation retarders are located in different locations than the passive retarders of the present modalities. The insulation retardant reduces the frontal reflections of the emission layer of the OLED screen, which is a different effect than the reduction of luminance for observation positions outside the geometric axis of the present modalities.
[0188] [0188] The structure and operation of several switchable display devices will now be described. In this description, similar elements have similar reference numbers. It should be noted that the disclosure related to any element applies to each device on which the same element or a corresponding element is provided. Consequently, for the sake of brevity, such a description will not be repeated.
[0189] [0189] Figure 1A is a schematic diagram illustrating a side perspective view of an optical chain from a display device.
[0190] [0190] The display device 100 comprises a spatial light modulator 48 comprising at least one screen polarizer which is the output polarizer 218. The backlight 20 is arranged to emit light, and the spatial light modulator 48 comprises a modulator transmissive spatial light 48 arranged to receive light emitted from the backlight 20. Display device 100 is arranged to emit output light 400 with angular luminance properties, as will be described in the present disclosure.
[0191] [0191] In the present disclosure, the spatial light modulator 48 may comprise a liquid crystal screen comprising substrates 212, 216, and the liquid crystal layer 214 has red, green and blue pixels 220, 222, 224. The modulator of Spatial light 48 has an input screen polarizer 210 and an output screen polarizer 218 on opposite sides of the modulator. The output screen polarizer 218 is arranged to provide a high extinction ratio for the light coming from pixels 220, 222, 224 of the space light modulator 48. Typical polarizers 210, 218 can be absorbent polarizers like dichroic polarizers.
[0192] [0192] Optionally, a reflective polarizer 208 can be provided between the dichroic input screen polarizer 210 and the backlight 210 to provide recirculated light and increase screen efficiency. Advantageously, efficiency can be increased.
[0193] [0193] The backlight 20 may comprise incoming light sources 15, a waveguide 1, a rear reflector 3 and an optical chain 5 comprising diffusers, reflective films and other known optical backlight structures. Asymmetric diffusers, which can comprise relief elements with an asymmetric surface, for example, can be provided in the optical chain 5 with the increase of diffusion in the direction of elevation compared to the lateral direction. Advantageously, the uniformity of the image can be increased.
[0194] [0194] In the present embodiments, the backlight 20 can be arranged to provide an angular light distribution that has reduced luminance for observation positions outside the geometric axis compared to the frontal luminance, as will be described with reference to Figures 26A to 28C below . The backlight 20 may additionally comprise a switchable backlight arranged to switch the output angular luminance profile in order to provide reduced luminance outside the geometry axis in a private operating mode and higher luminance outside the geometry axis in an angle operating mode broad. Such backlight switching 20 can cooperate with the switchable compensated retarder 300 of the present embodiments.
[0195] [0195] An additional polarizer 318 is arranged on the same output side of the space light modulator 48 as the output screen polarizer 218, which can be a dichroic absorption polarizer.
[0196] [0196] Screen polarizer 218 and additional polarizer 318 have electrical vector transmission directions 219, 319 that are parallel. As will be described below, such parallel alignment provides high transmission to central observation sites.
[0197] [0197] The multiple retarders, which together are called switchable compensated retardant 300 in the present invention, are arranged between the additional polarizer 318 and the screen polarizer 218 and comprise: (i) a switchable liquid crystal retarder 301 comprising a layer 314 of liquid crystal material disposed between the screen polarizer 218 and the additional polarizer 318; and (ii) a passive compensation retarder 330.
[0198] [0198] Figure 1B is a schematic diagram that illustrates a front view of the alignment of the optical layers in the optical chain of Figure 1A. The input vector electric transmission direction 211 on the input screen polarizer 210 of the space light modulator 48 provides an input polarization component that can be transformed by the liquid crystal layer 214 to provide an output polarization component determined by the electric vector transmission direction 219 at output screen polarizer 218.
[0199] [0199] The passive compensation retarder 330 may comprise a delay layer with a discreet birefringent material 430, while the switchable liquid crystal retarder 301 may comprise a liquid crystal material.
[0200] [0200] The switchable compensated retardant 300 thus comprises a switchable liquid crystal retardant 301 comprising a switchable liquid crystal retardant 301, substrates 312, 316 and a passive compensation retardant 330 disposed between an additional polarizer 318 and a polarizer screen 218.
[0201] [0201] Substrates 312, 316 can be glass substrates or polymer substrates such as polyimide substrates. Flexible substrates can be conveniently supplied with transparent electrodes. Advantageously, curved, folded and foldable screens can be provided.
[0202] [0202] The display device 100 further comprises a control system 352 arranged to control the voltage applied by the voltage driver 350 to the electrodes of the switchable liquid crystal retarder 301.
[0203] [0203] It may be desirable to provide reduced stray light or privacy control for an emissive screen.
[0204] [0204] Figure 1C is a schematic diagram illustrating a side perspective view of an optical chain of a directional display device comprising an emissive spatial light modulator 48 and a switchable compensated retarder 300 arranged on the output side of the modulator. emissive space light 48.
[0205] [0205] The spatial light modulator 48 can alternatively be supplied by other types of screens that provide 400 output light per emission, such as organic LED screens (OLED), with an output screen polarizer 218, substrates 512, 516 and a light-emitting layer 514. Output polarizer 218 can provide luminance reduction for reflected light from the OLED pixel plane through one or more retarders 518 inserted between the output screen polarizer 218 and the pixel plane OLED. The one or more retarders 518 can be a quarter wave plate (blade) and are different from the compensation retarder 330 of the present disclosure.
[0206] [0206] In the embodiment of Figure 1C, the spatial light modulator 48 thus comprises an emissive spatial light modulator, and the screen polarizer is the output screen polarizer 218.
[0207] [0207] Otherwise, the directional display device in Figure 1C is the same as in Figure 1A, as described above.
[0208] [0208] An optical viewing angle control element 260 for application to a display device will be described below. Optical viewing angle control elements 260 can be added to spatial light modulators comprising a screen polarizer 210, 218 to achieve switchable field of view characteristics.
[0209] [0209] Figure 1D is a schematic diagram illustrating a side perspective view of an optical viewing angle control element 260 for application to a display device comprising a passive compensation retarder 330, a switchable liquid crystal retarder 301 and a control polarizer 250.
[0210] [0210] In use, the viewing angle control optical element 260 can be fixed by a user or can be fixed by the factory to a 48 polarized output space light modulator. The viewing angle control optical element 260 can be supplied as a flexible film for curved and folded screens. Alternatively, the viewing angle control optical element 260 may be provided on a rigid substrate such as a glassy substrate.
[0211] [0211] Advantageously, an after-sales privacy control element and / or diffused light control element can be provided that does not require matching the panel's pixel resolution to avoid Moiré artifacts. The optical element for viewing angle control 260 can be additionally supplied for attachment by the factory to the space light modulator 48.
[0212] [0212] By attaching the optical viewing angle control element 260 of Figure 1D to an existing display device, it is possible to form a display device as shown in any of Figures 1A to 1C.
[0213] [0213] The modalities of Figures 1A to 1D provide polar luminance control for light 400 that is emitted from the space light modulator
[0214] [0214] In addition, the provision of passive compensation retardant 330, in addition to the switchable liquid crystal retarder 301, optimizes performance, as will be described in more detail with reference to some specific display devices, and compared to some examples comparatives described with reference to Figures 19A to 19E.
[0215] [0215] It may be desirable to reduce the number of optical layers between a space light modulator 48 and an observer. An arrangement will be described below in which the multiple retarders 300 are arranged on the input side of the space light modulator 48.
[0216] [0216] Figure 2A is a schematic diagram illustrating a side perspective view of an optical chain of a directional display device comprising a backlight 20, a rear switchable rear retarder 300, a transmissive spatial light modulator 48, where the additional polarizer 318 comprises a reflective polarizer; and Figure 2B is a schematic diagram showing a front view of the alignment of the optical layers in the optical chain of Figure 2A.
[0217] [0217] The display device 100 comprises a spatial light modulator 48; a screen polarizer 210 arranged on the input side of the space light modulator 48. An additional polarizer 318 is arranged on the same side of the space light modulator 48 as the screen polarizer 210. The additional polarizer 318 is a reflective polarizer that operates in cooperation with the backlight 20 to achieve greater efficiency.
[0218] [0218] The multiple retarders 300 are arranged between the additional reflective retarder 318 and the screen polarizer 210. With reference to Figure 1A, the multiple retarders 300 comprise: a switchable liquid crystal retarder 301 comprising a layer 314 of crystal material liquid disposed between the screen polarizer 210 and the additional reflective polarizer 318; and a passive compensation retarder 330. In this way, the additional reflective polarizer 318 is arranged on the input side of the input screen polarizer 210 between the input screen polarizer 210 and the backlight 20, and the multiple retarders 300 are arranged between the additional reflective polarizer 318 and the input screen polarizer 210.
[0219] [0219] The electric vector transmission direction 319 of the additional reflective polarizer 318 is parallel to the electric vector transmission direction 211 of the input polarizer 210 to achieve switchable directional properties, as will be described later in this document.
[0220] [0220] In alternative embodiments, the additional polarizer 318 may comprise either a reflective polarizer or a dichroic absorption polarizer, or it may comprise only a dichroic polarizer.
[0221] [0221] The additional reflective polarizer 318 can, for example, be a multilayer film like DBEF ™ available from 3M Corporation, or it can be a wire grid polarizer. Advantageously, the display efficiency can be improved due to the recycling of light from the polarized reflection of polarizer 372. Additional costs and thickness can be reduced compared to the use of a dichroic absorption polarizer and a reflective polarizer as the additional polarizer 318.
[0222] [0222] Compared to the arrangement of Figure 1A, Figure 2A can provide enhanced contrast of the image in front of the screen due to the reduced number of layers between pixels 220, 222, 224 and an observer.
[0223] [0223] Figure 2C is a schematic diagram illustrating a side perspective view of an optical chain of a directional display device comprising a backlight 20, a rear switchable compensated retarder 300 and a transmissive spatial light modulator 48, of which the additional polarizer 318 comprises a dichroic polarizer. In comparison to the additional reflective polarizer 318 of Figure 2A, the additional dichroic polarizer 318 does not recycle the high angle light for the backlight and thus can reduce the luminance outside the geometric axis compared to the arrangement of Figure 2A. Advantageously, privacy performance is improved.
[0224] [0224] The arrangement and operation of the switchable compensated retarders 300 and the additional polarizer 318 of Figures 1A to 1C and Figures 2A and 2B will now be described.
[0225] [0225] Figure 3 is a schematic diagram illustrating a side view of an illustrative arrangement of a switchable liquid crystal retarder 301 comprising a layer 314 of liquid crystal material 414 with a negative dielectric anisotropy. The substrates 312, 316 can have transparent electrodes 413, 415 disposed on them and homeotropic surface alignment layers 409, 411 arranged on opposite sides of the switchable liquid crystal retarder 301. The homeotropic alignment layers 409, 411 can provide homeotropic alignment in the adjacent liquid crystal material 414 with a pre-slope angle 407.
[0226] [0226] The orientation of liquid crystal material 414 in the xy plane is determined by the direction of the pre-slope of the alignment layers, so that each alignment layer has a pre-slope, with the pre-slope of each layer of alignment. The alignment has a pre-tilt direction with a component 417a, 417b in the plane of the switchable liquid crystal retarder 301 which is parallel or antiparallel or orthogonal to the electrical vector transmission direction 303 of the output screen polarizer 218.
[0227] [0227] The pre-slope 407a, 407b can be, for example, 88 degrees, so that component 417 is small enough to achieve defect reduction ("declines") in the relaxed (zero stress) state of alignment of layer 314 of liquid crystal material 414. In this way, layer 314 is provided substantially by a positive plate C in the zero stress arrangement. In practice, the liquid crystal layer has additionally small O-plate characteristics provided by pre-tilting the angled homeotropic alignment layer 407a and a residual component 417.
[0228] [0228] The switchable liquid crystal retarder 301 comprises electrodes 413, 415 disposed adjacent to the switchable liquid crystal retardant 301 and on opposite sides of the switchable liquid crystal retardant
[0229] [0229] In the non-actuated state, the liquid crystal material 414 is aligned with a component 418 perpendicular to the plane of the retarder 301 and a component 417 in the plane of the retarder.
[0230] [0230] The retarder 330 is illustrated as comprising a passive negative plate O comprising 430 discotic birefringent material. The delay of the passive compensation retarder 330 may be equal to and opposite to the delay of the switchable switchable liquid crystal retarder 301. The crystal retardant switchable liquid 301 can comprise a first and a second pre-slope 407a, 407b; and the passive compensation retardant 330 comprises a compensation retarder with the first and second pre-slopes 405a, 405b, the first pre-slope 405a of the compensation retarder 330 being the same as the first pre-slope 407a of the liquid crystal retarder 301 , and the second pre-slope 405b of the compensation retarder 330 being the same as the second pre-slope 307b of the liquid crystal retarder 301.
[0231] [0231] Passive O plates may comprise, for example, layers of cured mesogen which may be layers of reactive discotic mesogens. The pre-slope of the compensation retarder can be achieved by curing reactive mesogen materials after alignment with an appropriate alignment layer. The O plates can also comprise double extended polymeric films such as polycarbonate.
[0232] [0232] In operation, the switchable liquid crystal retarder 301 is switchable between two orientation states. The first state can allow multiple observers to observe the screen. The second state can be provided with a narrow angle mode for operation in private mode, or reduced diffused light, for example in night operation. As will be further described below, such elements can provide high transmission for a wide range of polar angles in wide angle operating mode, and a polar field of view with restricted luminance in a private operating mode.
[0233] [0233] The operation of the screen in Figure 1A in wide angle mode representing a first state will now be described.
[0234] [0234] Figure 4A is a schematic diagram illustrating a side perspective view of an arrangement of the switchable compensated retarder 300 in a wide angle operating mode. A zero volt voltage is applied to the switchable liquid crystal retarder 301. In Figure 4A and other schematic diagrams below, some layers of the optical chain are omitted for clarity. For example, switchable liquid crystal retarder 301 is shown by omitting substrates 312, 316.
[0235] [0235] The switchable liquid crystal retarder 301 comprises two layers of surface alignment disposed adjacent to the layer of liquid crystal material 414 on opposite sides thereof and arranged to provide homeotropic alignment in the adjacent liquid crystal material 414. As described above, liquid crystal material 414 can be provided with a pre-slope, for example, of 88 degrees to the horizontal to remove degeneration in the alignment of liquid crystal material 414.
[0236] [0236] The passive compensation retarder 330 comprises a negative plate C which has an optical axis which is a fast geometric axis perpendicular to the plane of the retarder. Thus, the material 430 of the plate retarder C may have a negative dielectric anisotropy. The C plates can comprise transparent birefringent materials such as: polycarbonates or reactive mesogens that are molded on a substrate that provides homeotropic alignment for example; Cyclic Olefin Polymer (COP, from "Cyclo Olefin Polymer") Zeonex ™; discotic polymers; and Nitto Denko ™ double extended polycarbonates.
[0237] [0237] Figure 4B is a schematic diagram showing a graph of the steering angle 407 against the fractionated liquid crystal location 440 through the switchable liquid crystal retarding cell, where the fractionated location 440 varies between 0, for a location on the surface alignment 409, and 1 for a location on the surface alignment layer 411.
[0238] [0238] For a vertically aligned mode with no voltage applied, as shown in Figure 4A, the liquid crystal drivers are at a 407 degree slope of 88 degrees through the cell thickness as indicated by the tilt profile 442. The tilt profile for the layer 314 can be the same as the profile 442. The compensation retarder 330 can provide correction for the pre-tilt direction of the switchable liquid crystal retarder 301. The compensation retarder 330 can alternatively have a uniform tilt angle of 90 degrees, such a difference in the pre-inclination of the liquid crystal layer provides only a small difference in the observation properties outside the geometric axis.
[0239] [0239] Thus, the off-axis delay of the compensation retarder 330 is substantially the same and opposite to the off-axis delay of the switchable liquid crystal retarder 301 when no voltage is applied.
[0240] [0240] Figure 4C is a schematic diagram illustrating a side view of the propagation of output light from a spatial light modulator 48 through the optical chain of Figure 1A in a wide-angle operation mode; and Figure 4D is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 4C in a wide angle operating mode.
[0241] [0241] An ideal switchable compensated retardant 300 comprises a compensating retardant 330 in combination with a variable switchable liquid crystal retardant 301 in which the dielectric constants, anisotropy and anisotropy dispersion of the compensating retardant 330 have dielectric constants, anisotropy and anisotropy dispersion equal to and opposite to that of layer 314. The delay of the passive compensation retardant 330 is the same and opposite to the delay of the switchable switchable liquid crystal retarder 301.
[0242] [0242] Such an ideal switchable compensated retarder achieves compensation for light transmitted in a first wide-angle state of layer 314 of liquid crystal material 414 for all polar angles; and a narrow field of view in a lateral direction in a second private state of the switchable liquid crystal retarder 301.
[0243] [0243] Additionally, the optical axis of the compensation retarder 330 has the same direction as the optical axis of the liquid crystal retarder 301 in its wide-angle state. Such a compensation retarder 330 overrides the delay of the liquid crystal retardant for all viewing angles, and provides an ideal wide-angle observation state with no loss of luminance for all observation directions.
[0244] [0244] The polar transmission profile of wide angle for non-ideal material selections will now be described.
[0245] [0245] The illustrative embodiments of the present disclosure illustrate compensation retardants 330 which may not exactly compensate for the delay of the switchable liquid crystal retardant 301 due to small differences in material properties that are typical for the 330, 301. retarders. However, advantageously , such deviations are small and high-performance wide and narrow angle states can be obtained with such deviations that may be close to optimal performance.
[0246] [0246] Thus, when the switchable liquid crystal retardant 301 is in a first state of said two states, the compensated retardant 300 does not provide general transformation of the polarization component 360, 361 to emit rays of light 400 that pass through it perpendicularly to the plane of the switchable retarder or at an acute angle to the perpendicular to the plane of the switchable retarder, like light rays 402.
[0247] [0247] Polarization component 362 is substantially the same as polarization component 360, and polarization component 364 is substantially equal to polarization component 361. In this way, the angular transmission profile of Figure 4D is transmitted substantially uniformly across of a wide polar region.
[0248] [0248] In other words, when the liquid crystal material layer 414 is in the first orientation state of said two orientation states, the multiple retarders 330, 301 do not provide any general retardation of the light that passes through them perpendicular to the plane of the retarders or at an acute angle to the perpendicular to the plane of the retarders 330, 301.
[0249] [0249] Advantageously, the variation of the screen's luminance with the viewing angle in the first state is substantially unchanged. Multiple users can conveniently view the screen from a wide range of viewing angles.
[0250] [0250] The operation of compensated retarder 300 and additional polarizer 318 in a narrow angle mode, for example for use in a private operating mode, will be described below.
[0251] [0251] Figure 5A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder 300 in a private mode of operation comprising a passive negative plate C compensation retardant 330, and a crystal retardant switchable liquid aligned homeotropically 301 in a private mode of operation.
[0252] [0252] Liquid crystal retarder 301 additionally comprises transparent electrodes 413, 415 as ITO electrodes (indium and tin oxide) arranged along the switchable liquid crystal retarder 301. Electrodes 413, 415 control the switchable liquid crystal retarder 301 by adjusting the voltage being applied to electrodes 413, 415.
[0253] [0253] The control system 352 is arranged to control the voltage applied by the voltage trigger 350 to electrodes 413, 415 of the switchable liquid crystal retarder 301.
[0254] [0254] Again with reference to Figure 4B, when a voltage is applied, the slant profile 444 is supplied to the switchable liquid crystal retarder 301 so that the retardation of layer 314 of liquid crystal material 414 is modified.
[0255] [0255] The direction of optimal privacy performance can be adjusted in response to the observer's position by controlling the drive voltage. In another mode of use or to provide controlled luminance to observers outside the geometric axis, for example in an automotive environment when a passenger or driver may want some visibility of the displayed image, without complete obscuration, through intermediate voltage levels.
[0256] [0256] Figure 5B is a schematic diagram illustrating a side view of the propagation of the light output from the space light modulator 48 through the optical chain of Figure 1A in a private operating mode in which the switchable liquid crystal retarder 301 is guided by the application of a tension.
[0257] [0257] In the present embodiments, the switchable liquid crystal retarder 330 compensated can be configured, in combination with the screen polarizer 210, 218, 316 and the additional polarizer 318, to have the effect that the luminance of the light emitted from the device display at an acute angle to the optical axis (outside the geometric axis) is reduced, that is, in comparison with the retarder not being present. The switchable compensated liquid crystal retarder 330 can also be configured, in combination with the screen polarizer 210, 218, 316 and the additional polarizer 318, to have the effect that the luminance of the light emitted from the display device along the axis optical (outside the geometric axis) is not reduced, that is, in comparison with the retarder not being present.
[0258] [0258] The polarization component 360 of the output screen polarizer 218 is transmitted by the output screen polarizer 218 and falls on the switchable compensated retarder 300. The light on the geometric axis has a polarization component 362 that is not modified from of the 360 component, while the light outside the geometric axis has a polarizing component 364 which is transformed by the switchable compensated retarder 300 retarders. At a minimum, the polarizing component 361 is transformed into a linear polarizing component 364 and absorbed by the additional polarizer 318. More generally, polarization component 361 is transformed into an elliptical polarization component, which is partially absorbed by the additional polarizer 318.
[0259] [0259] Thus, when the switchable liquid crystal retardant retardant 301 is in the second orientation of said two orientation states, the multiple retarders 301, 330 do not provide any general retardation of light passing through them along a geometric axis perpendicular to the plane of the retarders, but provide an overall non-zero delay for the light passing through them to some polar angles 363 which are at an acute angle to the perpendicular to the plane of the retarders 301, 330.
[0260] [0260] In other words, when the switchable liquid crystal retardant 301 is in a second state of said two states, the switchable compensated retardant 330 does not provide general transformation of the polarization component 360 to emit 400 light rays passing through it at along a geometric axis perpendicular to the plane of the switchable retarder 301, but provides a general transformation of the polarization component 361 to light rays 402 that pass through it to some polar angles that are at an acute angle to the perpendicular to the plane of the 301 retarders , 330.
[0261] [0261] An illustrative material system will be described for operation at a narrow angle.
[0262] [0262] Figure 5C is a schematic graph that illustrates the variation of the output transmission with polar directions for the light rays transmitted in Figure 5B, with the parameters described in Table 1.
[0263] [0263] In the present modalities, desirable ranges for delays and stresses were established by means of simulation of retarder chains and experiments with optical chains of screens.
[0264] [0264] Switchable liquid crystal retardant 300 comprises a first surface alignment layer 409 disposed on a first side of the liquid crystal material layer 414, and a second surface alignment layer 411 disposed on the second side of the material layer liquid crystal 414 opposite the first side; the first surface alignment layer 409 being a homeotropic alignment layer, and the second surface alignment layer 411 being a homeotropic alignment layer, the liquid crystal material layer having a light delay of a length 550 nm wavelength between 500 nm and 1000 nm, preferably between 600 nm and 900 nm, and most preferably between 700 nm and 850 nm.
[0265] [0265] When the passive compensation retarder 330 comprises a retarder that has an optical axis perpendicular to the plane of the retarder, the passive retarder has a light-delay of 550 nm between -300 nm and -900 nm, preferably between -450 nm and -800 nm, and most preferably between -500 nm and -725 nm.
[0266] [0266] The polar distribution of the light transmission illustrated in Figure 5C modifies the polar distribution of the luminance output of the underlying space light modulator 48 and where applicable to the backlight 20.
[0267] [0267] Advantageously, a private screen is provided that has low luminance for a curious person outside the geometric axis, while maintaining high luminance for an observer on the geometric axis. A large polar region is provided over which the luminance of the screen for a curious outside the geometric axis is reduced. In addition, the luminance on the geometric axis is substantially unchanged for the primary user of the screen in the private operating mode.
[0268] [0268] The voltage applied to the electrodes is zero for the first orientation state and different from zero for the second orientation state. Advantageously, the wide operating mode may have no additional power consumption, and the failure mode for driving the switchable liquid crystal retarder 301 is designed for the wide angle mode.
[0269] [0269] The private mode operation of the screen in Figure 1A will now be described in detail.
[0270] [0270] Figure 6A is a schematic diagram that illustrates a front perspective view of the output light transmitted to a screen operating in private mode. The display device 100 can be supplied with white regions 603 and black regions 601. A curious person can observe an image on the screen if the difference in luminance between the observed regions 601, 603 can be perceived. In operation, the primary user 45 observes an image with full luminance through 400 rays to observation sites 26 that can be optical windows of a directional display device. Curious 47 observes reduced luminance beams 402 at observation sites 27 that can be optical windows of a directional display device. Regions 26, 27 additionally represent regions within the geometric axis and outside the geometric axis of Figure 5C.
[0271] [0271] Figure 6B is a schematic diagram that illustrates frontal perspective views of the appearance of the screen in Figure 1A operating in private mode 1 with variations in luminance as illustrated in Figure 5C. In this way, upper observation quadrants 530, 532, lower observation quadrants 534, 536 and lateral observation positions 526, 528 provide reduced luminance, while upper / lower central observation regions 522, 520 and frontal observation provide a lower luminance. much higher luminance.
[0272] [0272] It may be desirable to provide controllable screen lighting in an automotive vehicle.
[0273] [0273] Figure 6C is a schematic diagram illustrating a side view of an automotive vehicle with a switchable directional screen 100 disposed within the cabin of vehicle 602 of a motor vehicle 600 for both entertainment and sharing operating modes. A light cone 610 (for example, representing the light cone within which the luminance is greater than 50% of the peak luminance) can be provided by the luminance distribution of the screen 100 in the direction of elevation and is not switchable.
[0274] [0274] Figure 6D is a schematic diagram illustrating a top view of an automotive vehicle with a switchable directional screen 100 arranged inside the cabin of vehicle 602 in an entertainment operating mode and operates in a similar manner to that of a screen private. The light cone 612 is provided with a narrow angled band so that passenger 606 can see screen 100 and driver 604 cannot see an image on screen 100. Advantageously, entertainment images can be displayed to passenger 606 without distraction for the conductor 604.
[0275] [0275] Figure 6E is a schematic diagram illustrating a top view of an automotive vehicle with a switchable directional screen 100 arranged inside the cabin of vehicle 602 in a sharing operation mode. The light cone 614 is provided with a wide angular range so that all occupants can perceive an image on the screen 100, for example when the screen is not moving or when images that divert attention are not provided.
[0276] [0276] Figure 6F is a schematic diagram illustrating a top view of an automotive vehicle with a switchable directional screen 100 arranged inside the cabin of vehicle 602 for both night and day operating modes. In comparison with the modalities of Figures 6C to 6E, the optical output is rotated so that the direction of elevation of the screen is located along a geometric axis between the locations of the driver 604 and the passenger 606. The light cone 620 illuminates both driver 604 and passenger 606.
[0277] [0277] Figure 6G is a schematic diagram illustrating a side view of an automotive vehicle with a switchable directional screen 100 disposed within the cabin of vehicle 602 in a night mode of operation. In this way, the screen can provide a narrow angled light cone
[0278] [0278] Figure 6H is a schematic diagram illustrating a side view of an automotive vehicle with a switchable directional screen 100 disposed within the cabin of vehicle 602 in a daytime mode of operation. In this way, the screen can provide a narrow angled 624 light cone. Advantageously, the screen can be conveniently observed by all occupants of booth 602.
[0279] [0279] The screens 100 of Figures 6C to 6H can be arranged in other places in the vehicle cabin, such as on the driver's instrument panel, on the center console screen and on screens on the seat back.
[0280] [0280] Figures 7A to 7D are schematic diagrams illustrating the variation of the output transmission with polar directions for four different drive voltages from 2.05 V to 2.35 V in 0.1 V increments. Thus, the voltage applied can provide control of the minimum luminance in locations of the field of view in the private operating mode. In addition, the minimum luminance can be controlled between an elevation that is zero or less to elevations that are in the upper quadrants of the polar profile.
[0281] [0281] Figure 8 is a flow chart that illustrates the control of a private screen implemented by a control system. The control can be applied to each of the devices described here.
[0282] [0282] In a first step 870, a user can enable a private mode of operation.
[0283] [0283] If a first switchable compensated liquid crystal retarder and an additional switchable compensated liquid crystal retarder 300B are provided (as, for example, in the device of Figure 22A described below), the control system is arranged in the second state guidance for controlling the voltage applied to electrodes 413, 415 of the first switchable liquid crystal retardant 314a mentioned and to control the voltage applied to the electrodes of the additional switchable liquid crystal retarder 314B; the total delay of light passing through the first mentioned switchable liquid crystal retardant 314A mentioned and the first passive compensation retardant 330A mentioned at some polar angles at an acute angle with the perpendicular to the plane of retarders 314A, 330A is different from the delay total light passing through the additional switchable liquid crystal retarder 314B and the additional passive compensation retarder 330B at the same polar angles.
[0284] [0284] Such a privately defined definition can be provided by manual configuration (for example, a keyboard operation), or by automatic detection through the use of a sensor to locate the presence of a curious person, as described, for example, in the order US Patent No. 2017-0236494, which is incorporated herein by reference in its entirety. Optionally, the orientation of the screen in relation to the curious can be additionally detected through a detector 873.
[0285] [0285] In a second step 872, the place of the curious can be detected, for example, through a camera or by a keyboard configuration, or another method. In an illustrative example, an office environment can be envisaged in which it may be desirable to optimize privacy performance for onlookers who are moving around a shared office environment and thus optimize performance for observation quadrants in the direction to low. By way of comparison, in a flight environment it may be desirable to provide privacy level optimization for onlookers sitting, with a better level of privacy at lower altitudes than those desirable for an office environment.
[0286] [0286] In a third step 876, the voltage applied to the switchable liquid crystal retarder 301 can be adjusted and in a fourth step 878 an LED profile can be adjusted with the control system.
[0287] [0287] In this way, the control system can additionally comprise a means 872 for determining the location of a curious 47 in relation to the display device 100, and the control system is arranged to adjust the voltage applied by the drive 350 to the electrodes 413 .415 of switchable liquid crystal retarder 314 in response to the measured location of curious 47.
[0288] [0288] Advantageously, the privacy operation of the screen can be controlled to optimize the geometry of observation of the curious.
[0289] [0289] Back to the discussion of the present modalities, additional provisions of the switchable compensated retarders 300 will be described below.
[0290] [0290] Figure 9A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable retarder in a private mode of operation comprising passive crossover plate A 308A, 308B compensation retarders and a switchable liquid crystal retarder homeotropically aligned 301; and Figure 9B is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a private mode of operation comprising passive crossover A plate compensating retarders and a homeotropically aligned switchable liquid retardant.
[0291] [0291] Compared to the arrangement of Figure 4A and Figure 5A, the compensation retarder 330 may alternatively comprise a pair of retarders 308A, 308B having optical axes in the plane of the intersecting retarders. The compensation retarder 330 thus comprises a pair of retarders 308A, 308B, each of which comprises a single plate A.
[0292] [0292] The pair of retarders 308A, 308B each comprise multiple plates A having respective optical axes 309A, 309B aligned at different angles to each other. The pair of retarders has optical axes 309A, 309B that each extend at 45 ° with respect to an electric vector transmission direction that is parallel to the electric vector transmission direction 211 of the input screen polarizer 210, in the case in that the additional polarizer 318 is disposed on the input side of the input screen polarizer or is parallel to the electrical vector transmission direction 219 of the output screen polarizer 218 in the event that the additional polarizer 318 is disposed on the output side of the input screen polarizer 218.
[0293] [0293] Figure 9C is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 9A in a wide angle operation mode; and Figure 9D is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 9B in a private mode of operation provided by the illustrative modality of Table 2.
[0294] [0294] When the passive compensation retarder 330 comprises a pair of retarders that have optical axes in the plane of the intersecting retarders, each retarder in the pair of retarders has a light delay of a 550 nm wavelength between 300 nm and 800 nm, preferably between 500 nm and 700 nm, and most preferably between 550 nm and 675 nm.
[0295] [0295] Advantageously, plates A can be manufactured more conveniently at a lower cost than plate retardant C of Figure 4A and Figure 5A. In addition, a zero voltage state can be provided for the wide angle operating mode, minimizing energy consumption during wide angle operation.
[0296] [0296] In the present modalities, the term 'crossed', as well as its flexions, refers to an angle of substantially 90 ° between the optical axes of the two retarders in the plane of the retarders. To reduce the cost of retarder materials, it is desirable to supply materials with some variation in retarder orientation due to stretching errors during film making, for example. Variations in the orientation of the retarder in the opposite direction to the preferred directions can reduce the frontal luminance and increase the minimum transmission. Preferably, the angle of 310A is at least 35 ° and at most 55 °, more preferably at least 40 ° and at most 50 °, and most preferably at least 42.5 ° and at most 47, 5th. Preferably, the angle 310B is at least 125 ° and at most 145 °, more preferably at least 130 ° and at most 135 °, and most preferably at least 132.5 ° and at most 137.5 °.
[0297] [0297] During mechanical distortion, such as when touching the screen, homeotropically aligned liquid crystal retardants 301 of Figures 9A and 9B can have undesirably long recovery times, creating visible misalignment artifacts. It would be desirable to provide fast recovery times after mechanical distortion.
[0298] [0298] Figures 10A and 10B are schematic diagrams illustrating a side perspective view of an arrangement of a switchable retarder in a wide and private angle operating mode, respectively, comprising a homogeneously aligned switchable liquid crystal retarder comprising liquid crystal material 414 with a positive dielectric anisotropy and a passive negative plate C retardant 330 for the first and second drive voltages, respectively.
[0299] [0299] The switchable liquid crystal retarder additionally comprises surface alignment layers 431, 433 disposed adjacent to the layer of liquid crystal material 414, and each arranged to provide homogeneous alignment in the adjacent liquid crystal material. In other words, the switchable liquid crystal retarder comprises two layers of surface alignment 431, 433 disposed adjacent to the layer of liquid crystal material 414 and on opposite sides thereof, and each arranged to provide homogeneous alignment in the material of adjacent liquid crystal 414.
[0300] [0300] Figure 10C is a schematic diagram illustrating a graph of the steering angle 407 against fractional location 440 of the liquid crystal through the switchable liquid crystal retarding cell 301 of Figure 10A for several different applied voltages. Figure 10C differs from Figure 4B in that the pre-tilt angle is small and increases with the applied stress. Profile 441 illustrates the tilt angle of liquid crystal material 414 to 0 V applied voltage, tilt profile 443 illustrates direction guidance for 2.5 V and tilt profile 445 illustrates direction guidance for 5 V. In this way, the liquid crystal layers are typically inclined in desirable switched states, and compensated by the compensation retarders 330. Increasing the voltage above 2.5 V to 10 V progressively reduces the thickness of the 301 retarder on the screen in which it is present, and advantageously increases the polar field of view over which transmission is maximized.
[0301] [0301] The resolved component 419a, 419b of the liquid crystal slope compared to the direction perpendicular to the plane of the retarder is substantially larger than the components 417a, 417b of Figure 5A.
[0302] [0302] The larger amplitude of the resolved component 419a, 419b can provide greater restoring force after mechanical distortion compared to the arrangement of Figure 9A, for example. The sensitivity to mechanical distortions such as during a touch on the screen can be advantageously reduced.
[0303] [0303] The operating voltage can be reduced below 10 V for an acceptable wide-angle field of view, reducing energy consumption; and reducing the costs and complexity of the electric drive.
[0304] [0304] Figures 11A to 11C are schematic graphs illustrating the variation of the output transmission with polar directions for light rays transmitted from the switchable compensated retarder comprising a homogeneously aligned liquid crystal retarder 301 and a passive C plate compensation retarder negative 330, similarly to the display device of Figures 10A and 10B, in a private mode and two different wide-angle modes for different drive voltages comprising the modalities illustrated in Table 3.
[0305] [0305] Desirable optical delay ranges for the active LC retarder 301 comprising homogeneous alignment layers 431, 433 on both substrates and a passive negative plate C compensation delay 330 are further described in Table 4.
[0306] [0306] Thus, the switchable liquid crystal retardant 300 comprises a first surface alignment layer 431 disposed on a first side of the liquid crystal material layer 414, and a second surface alignment layer 433 disposed on the second side of the layer of liquid crystal material 414 opposite the first side; the first surface alignment layer 409 being a homogeneous alignment layer and the second surface alignment layer being a homogeneous alignment layer; the layer of liquid crystal material may have a light delay of a wavelength of 550 nm in a range from 500 nm to 1000 nm, preferably in a range of 600 nm to 850 nm, and most preferably in a range from 700 nm to 800 nm. Thus, when the first and second alignment layers are each homogeneous alignment layers and when the passive compensation retarder 330 comprises a retarder that has an optical axis perpendicular to the plane of the retarder, the passive retarder has a delay for light of a wavelength of 550 nm in a range from -300 nm to -700 nm, preferably in a range from -350 nm to -600 nm, and most preferably from -400 nm to - 500 nm.
[0307] [0307] Advantageously, privacy outside the geometrical axis can be provided by reducing the luminance and increasing the level of privacy over wide polar regions. The additional resistance to visual artifacts arising from the flow of liquid crystal material in layer 314 can be improved compared to homeotropic alignment.
[0308] [0308] Various other configurations of the optical structure and drive of Figure 10A will now be described.
[0309] [0309] 5 V operation provides lower power consumption and low cost electronic circuits, while at the same time an acceptable reduction in luminance in wide angle mode. The field of view in wide angle mode can be further extended with 10 V operation.
[0310] [0310] Figure 12A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a private mode of operation comprising passive compensating retarders of crossed plates A 308A, 308B and a liquid crystal retarder homogeneously aligned switchable 301; and Figures 12B to 12D are schematic graphs illustrating the variation of the output transmission with polar directions for light rays transmitted from the switchable compensated retarder 301 comprising a homogeneously aligned liquid crystal material 414 and passive cross-plate retarders 308A, 308B in a private mode and a wide angle mode for different drive voltages that comprise the respective modalities illustrated in Table 5.
[0311] [0311] Desirable optical delay ranges for the active LC retarder 301 comprising homogeneous alignment layers 409, 411 on both substrates and A positive plates retarders 308A, 308B are further described in Table 6.
[0312] [0312] Thus, when: the first and second alignment layers are each homogeneous alignment layers; the layer of liquid crystal material may have a light delay of a wavelength of 550 nm in a range from 500 nm to 1000 nm, preferably in a range of 600 nm to 850 nm, and most preferably in a 700 nm to 800 nm range; and the passive compensation retarder 330 comprises a pair of retarders that have optical axes in the plane of the intersecting retarders, so each retarder of the pair of retarders has a light delay of a 550 nm wavelength between 300 nm and 800 nm , preferably between 350 nm and 650 nm, and most preferably between 450 nm and 550 nm.
[0313] [0313] Additionally, the crossed A plates can be conveniently supplied from low cost materials.
[0314] [0314] As an illustration, several other exemplary modalities of the optical structure and drive of Figure 12A will now be described. Figure 12C and Figure 12D further illustrate that, by adjusting the control voltage and the delays, advantageously different wide-angle fields of view can be achieved.
[0315] [0315] Optical chain structure arrangements will be described below.
[0316] [0316] Figure 13A and Figure 13B are schematic diagrams illustrating partial side views of a screen comprising a switchable compensated retarder and optical bonding layers 380. Optical bonding layers 380 can be provided to laminate films and substrates, resulting for greater efficiency and reduced luminance at high viewing angles in private mode. In addition, an air gap 384 can be provided between the space light modulator 48 and the switchable compensated retarder
[0317] [0317] Passive compensation retarder 330 can be provided between the switchable liquid crystal layer 301 and the space light modulator 48, as shown in Figure 13A, or it can be supplied between the additional polarizer 318 and the switchable liquid crystal retarder 301, as shown in Figure 13B. Substantially, the same optical performance is provided on both systems.
[0318] [0318] Figure 13A illustrates that the optical layers are attached to the outer sides of the substrates 312, 316. Advantageously, the flexion of the substrates 312, 316 from the layers fixed due to the stresses stored during lamination can be reduced and the leveling of the screen maintained.
[0319] [0319] Similarly, the switchable compensated retarder 300 can be arranged so that the output polarizer 218 is the screen polarizer. The dispersion that can be provided by the spatial light modulator 48, as from the phase structures in pixels 220, 222, 224, does not degrade the output luminance profile compared to arrangements in which the switchable compensated retarder 301 is disposed behind of the space light modulator 48.
[0320] [0320] It may be desirable to provide the additional polarizer with an electrical vector transmission direction other than the electrical vector transmission direction of the screen polarizer.
[0321] [0321] Figure 14A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a private mode of operation comprising passive compensating retarders of crossed plates A 308A, 308B and a liquid crystal retarder homogeneously aligned switchable 301 as described above but additionally comprising a passive rotation retarder 460.
[0322] [0322] The screen polarizer 218 can be provided with an electric vector transmission direction 219, which can be, for example, at a 45 degree angle 317 in the case of a twisted nematic LCD screen. The additional polarizer 318 may be arranged to provide vertically polarized light to a user who may be wearing polarizing sunglasses that typically transmit vertically polarized light.
[0323] [0323] The passive rotation retarder 460 is different from the compensation retarder 330 of the present modalities and its operation will now be described.
[0324] [0324] The passive rotation retarder 460 may comprise a birefringent material 462 and be a half-wave plate, with a delay at a 550 nm wavelength of 275 nm, for example.
[0325] [0325] The passive rotation retarder 460 has a fast geometric axis orientation 464 that is tilted at an angle 466 that can be 22.5 degrees from the direction of electric vector transmission 319 of the additional polarizer
[0326] [0326] The passive rotation retarder 460 modifies the polarization state within the geometric axis, providing an angular rotation of the polarization component of the screen polarizer 218. In comparison, the compensation retarders 308A, 308B together do not modify the polarization state within the geometric axis.
[0327] [0327] Additionally, the passive rotation retarder 460 provides a polarization rotation that can be substantially independent of the viewing angle. In comparison, the 308A, 308B compensation retarders provide substantial changes in output luminance with the viewing angle.
[0328] [0328] Advantageously, a screen can be provided with an output polarization direction 319 which is different from the polarization direction of screen polarizer 219, for example, to provide an observation with polarizing sunglasses.
[0329] [0329] In an alternative embodiment the separate retarder 460 can be omitted and the delay 308B of Figure 11A increased to provide an additional half wave rotation compared to the delay of the retarder 308A. Still in the illustrative embodiment, the delay of the retarder 308B at a wavelength of 550 nm can be 275 nm greater than the delay of the retarder 308A. Advantageously, the number of layers, complexity and cost can be reduced.
[0330] [0330] It would be desirable to provide a reduced thickness and a reduced total number of optical components.
[0331] [0331] Figure 15A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder in a private mode of operation comprising a homogeneously aligned liquid crystal retarder 301 disposed between the first and the second retarders. passive compensation for C 330A, 330B plates, illustrated in more detail in Table 7.
[0332] [0332] Figure 15B and Figure 15C are schematic graphs that illustrate the variation of output transmission with polar directions for light rays transmitted in the optical chain of Figure 15A in a wide angle mode and a private operating mode, respectively.
[0333] [0333] The passive compensation retarder 330 comprises a first and a second plate C 330A, 330B; and the switchable liquid crystal layer 301 is provided between the first and second plates C 330A, 330B.
[0334] [0334] The passive compensation retarder 330A, 330B comprises two passive retarders that have an optical axis perpendicular to the plane of the passive retarders, and the switchable liquid crystal retarder 301 is provided between the two passive retarders. Thus, the first and second substrates 312, 316 of Figure 1A each comprise one of the two passive retarders 330A, 330B.
[0335] [0335] In combination the two passive retarders 330A, 330B have a total delay for light of a wavelength of 550 nm in a range of -300 nm to -800 nm, preferably in a range of -350 nm to -700 nm, and with the most preference in a range of -400 nm to -600 nm.
[0336] [0336] Figure 16A is a schematic diagram illustrating a side perspective view of a screen comprising a switchable liquid crystal retarder 301 disposed between the first and second substrates, each comprising passive compensating retarders for C 330A plates, 330B; and Figure 16B is a schematic diagram illustrating a partial side view of a screen comprising a switchable liquid crystal retarder 301 disposed between the first and the second substrates, each comprising passive compensating retarders for plates C 330A, 330B.
[0337] [0337] The first C 330A plate has a transparent electrode layer 415 and a liquid crystal alignment layer 411 formed on one side, and the second C plate 330b has a transparent electrode layer 413 and a liquid crystal alignment layer 409 formed on one side.
[0338] [0338] The layer 314 of liquid crystal material is provided between the first and second substrates 312, 316, and the first and second substrates 312, 316 each comprise one of the first and second plates C 330A, 330B. The C plates can be supplied in double extended COP films that are coated with ITO to provide electrodes 413, 415 and have liquid crystal alignment layers 409, 411 formed on them.
[0339] [0339] Advantageously, the number of layers can be reduced compared to the layout in Figure 1, reducing thickness, cost and complexity. Additionally, the C 330A, 330B boards can be flexible substrates, and can provide a flexible privacy screen.
[0340] [0340] It would be desirable to provide a layer 314 of liquid crystal material between a first and a second A plate substrate.
[0341] [0341] Figure 17A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable compensated retarder 300 in a wide angle operating mode comprising a homogeneously aligned liquid crystal retarder 301 disposed between the first and the second passive compensating retarders of crossed plates A, 330A, 330B, as described above; and Figure 17B and Figure 17C are schematic graphs that illustrate the variation of the output transmission with polar directions for light rays transmitted to the structure of Figure 17A when activated in wide and private angle operating modes, respectively, comprising the modalities additional illustrations shown in Table 7.
[0342] [0342] Compared to the arrangement in Figure 15A, plates A can advantageously be manufactured at a reduced cost compared to plates C.
[0343] [0343] Aligned hybrid structures comprising homogeneous and homogeneous alignment layers will be described below.
[0344] [0344] Figure 18A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable retarder in a private mode of operation comprising a switchable homogeneously and homeotropically aligned liquid crystal retarder 301 comprising a liquid crystal material 423 and a passive negative plate C retardant 330.
[0345] [0345] Figures 18B and 18C are schematic graphs that illustrate the variation of the output transmission with polar directions for light rays transmitted in Figure 18A in a wide and private angle operation mode, respectively, and provided by the provision in Table 8 .
[0346] [0346] The 301 hybrid switchable liquid crystal retardant has a variable inclination such that, for a given choice of material and cell thickness, an effective reduced birefringence is provided. Therefore, the design of the retarder must be adjusted to compensate, in comparison to the arrangements in which the alignment layers are the same. The switchable liquid crystal retarder 330 comprises a first surface alignment layer 441 disposed on a first side of the liquid crystal material layer 423, and a second surface alignment layer 443 disposed on the second side of the liquid crystal material layer 423 opposite the first side. The first surface alignment layer 441 is a homeotropic alignment layer arranged to provide homeotropic alignment of the adjacent liquid crystal material 423, and the second surface alignment layer 443 is a homogeneous alignment layer arranged to provide homogeneous alignment in the material of adjacent liquid crystal 423.
[0347] [0347] Additionally, the ideal retarder designs are related to the relative location of the passive compensation retarder 330 in relation to the homogeneous and homogeneous alignment layers.
[0348] [0348] When the surface alignment layer 443 arranged to provide homeotropic alignment is between the liquid crystal material layer 423 and the compensation retardant 330, the liquid crystal material layer 423 may have a light delay of a length 550 nm wave in a range from 500 nm to 1800 nm, preferably in a range from 700 nm to 1500 nm, and most preferably from 900 nm to 1350 nm. When the surface alignment layer 443 arranged to provide homogeneous alignment lies between the layer of liquid crystal material 423 and the compensating retardant 330, the passive compensating retarder may comprise a retarder 330 having its optical axis perpendicular to the plane of the retarder, as shown in Figure 18A, the passive retarder 330 having a light delay of a wavelength of 550 nm in the range of -300 nm to -1600 nm, preferably in the range of -500 nm to - 1300 nm, and most preferably in the range of -700 nm to -1150 nm; or, alternatively, the passive compensating retarder may comprise a pair of retarders (not shown) that have optical axes in the plane of the retarders that are crossed, each retarder of the pair of retarders having a light delay of a wavelength of 550 nm in a range from 400 nm to 1600 nm, preferably in a range from 600 nm to 1400 nm, and most preferably in a range from 800 nm to 1300 nm.
[0349] [0349] When the surface alignment layer 441 arranged to provide homeotropic alignment is between the layer of liquid crystal material 423 and the compensation retardant 330, the layer of liquid crystal material 423 may have a light delay of a length 550 nm wave in a range from 700 nm to 2000 nm, preferably in a range from 1000 nm to 1700 nm, and most preferably from 1200 nm to 1500 nm. When the surface alignment layer 441 arranged to provide homeotropic alignment lies between the layer of liquid crystal material 423 and the compensating retardant 330, the passive compensating retarder may comprise a retarder 330 having its optical axis perpendicular to the plane of the retarder, as shown in Figure 18 A, the passive retarder having a light delay of a wavelength of 550 nm in the range of -400 nm to -1800 nm, preferably in the range of -700 nm to -1500 nm, and most preferably in the range from -900 nm to -1300 nm; or, alternatively, the passive compensating retarder may comprise a pair of retarders (not shown) that have optical axes in the plane of the retarders that are crossed, each retarder of the pair of retarders having a light delay of a wavelength of 550 nm in a range from 400 nm to 1800 nm, preferably in a range from 700 nm to 1500 nm, and most preferably in a range from 900 nm to 1300 nm.
[0350] [0350] Compared to the arrangement of Figure 5A, the private mode of operation can advantageously achieve an increased resilience to the appearance of the material flow when the liquid crystal retarder is pressed.
[0351] [0351] As a comparison with the present modalities, the performance of retarders between parallel polarizers when arranged in series will be described below. First, the field of view of a homogeneously aligned liquid crystal retarder 301 will now be described for two different drive voltages.
[0352] [0352] Figure 19A is a schematic diagram showing a side perspective view of an array of a homogeneously aligned switchable liquid crystal retarder 390; Figure 19B is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 19A for a first applied voltage; and Figure 19C is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 19A for a second applied voltage that is greater than the first applied voltage, comprising the structure shown in Table 9. O homogeneously aligned switchable liquid crystal retarder 390 corresponds to switchable liquid crystal retardant 330 described above and can be applied as the switchable liquid crystal retardant in any of the devices disclosed herein.
[0353] [0353] Figure 19D is a schematic diagram illustrating a side perspective view of a passive C 392 plate retarder disposed between parallel polarizers; and Figure 19E is a schematic graph that illustrates the variation of the output transmission with polar directions for the light rays transmitted in Figure 19D, which comprises the structure illustrated in Table 9. The passive retarder of plate C 392 corresponds to the compensation retarder passive 330 and can be applied as at least one passive compensation retarder to any of the devices disclosed herein.
[0354] [0354] Figure 20A is a schematic diagram illustrating a side perspective view of an array of a homogeneously aligned switchable liquid crystal retarder 390 arranged between parallel polarizers 394, 396 in series with a passive retarder with field of view control that comprises a C 392 plate retarder disposed between parallel polarizers 396, 398; Figure 20B is a schematic graph showing the variation of the output transmission with polar directions for light rays transmitted in Figure 20A for a first applied voltage; Figure 20C is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figure 20A for a second applied voltage that is greater than the first applied voltage, comprising the structure shown in Table 9.
[0355] [0355] Figure 21A is a schematic diagram illustrating a side perspective view of an arrangement of a homogeneously aligned switchable liquid crystal retarder 301 arranged in series with a C 330 plate compensation retardant, the liquid crystal material being homogeneously aligned switchable 712 and the C 330 plate compensation retarder are arranged between a single pair of parallel polarizers; The
[0356] [0356] Unexpectedly, the ideal conditions for a maximum field of view operation are provided by network delay equal to or opposite to that of the switchable compensation retarder 330 compared to the switchable liquid crystal retarder 301 in its non-actuated state. An ideal compensation retarder 330 and a switchable liquid crystal retardant 301 can achieve (i) no change in the performance of the wide angle mode from the input light and (ii) optimal reduction of the side viewing angle for off-axis positions geometric for all elevations when arranged to provide a narrow angle state. This teaching can be applied to all display devices disclosed here.
[0357] [0357] It may be desirable to increase the luminance reduction for observation positions outside the geometric axis. In particular, it would be desirable to provide greater privacy reduction on a liquid crystal display with a wide-angle backlight.
[0358] [0358] Figure 22A is a schematic diagram illustrating a side perspective view (and looking at the inverted view in which the z axis, together with the output light, is directed downwards) of an arrangement of a switchable retarder in a private mode of operation, comprising: a first switchable compensated retarder 300A (in this case, a passive compensating retarder of plate C negative 330A and a switchable liquid crystal homeotropically aligned 301A, but this is just an example and can be replaced by any of the other multiple retarder arrangements disclosed herein) disposed between the output screen polarizer 218 and an additional polarizer 318A; and an additional switchable compensated retarder 300B (in this case, a passive negative compensation plate C
[0359] [0359] As an alternative, the first additional polarizer mentioned 318A can be disposed on the input side of the input screen polarizer 210, in which case the other additional polarizer 318B can be disposed on the input side of the input screen polarizer 210 between the first mentioned additional polarizer 318A and the backlight 20, and the additional switchable compensated retarder 300B can be arranged between the other additional polarizer 318B and the first mentioned additional polarizer 318A.
[0360] [0360] In both of these alternatives, each of the first multiple retarders 300 and the additional multiple retarders 300B is arranged between a respective pair of polarizers, thus producing an effect similar to that of the corresponding structure in the devices described above.
[0361] [0361] The pre-tilt directions 307A, 309AA of the alignment layers of the additional switchable liquid crystal retarder 301A may have a component in the plane of the liquid crystal layer that is aligned parallel or antiparallel or orthogonal to the directions of pre- slope of the alignment layers 307B, 309AB of the first switchable liquid crystal retarder 301B. In a wide-angle operating mode, both switchable liquid crystal retarders 301A, 301B are triggered to provide a wide viewing angle. In a private mode of operation, the switchable liquid crystal retardants 301B, 301A can cooperate to advantageously achieve an increased luminance reduction and thus form better privacy on a single geometric axis.
[0362] [0362] The delays provided by the first switchable liquid crystal retarder 301B and the additional liquid crystal retardants 301A may be different. The switchable liquid crystal retarder 301B and the additional switchable liquid crystal retardant 301A can be driven by a common electrical voltage and the liquid crystal material 408B in the first switchable liquid crystal retardant 301B may be different from the liquid crystal material 408A in the retarder switchable liquid crystal display 301A. The chromatic variation of the polar luminance profiles illustrated elsewhere in the present invention can be reduced, so that advantageously the appearance of colors outside the geometric axis is improved.
[0363] [0363] Alternatively, switchable liquid crystal retardants 301B, 301A can have orthogonal alignments so that low luminance is achieved in both horizontal and vertical directions, to advantageously provide a landscape and portrait privacy operation.
[0364] [0364] Alternatively, layers 301A, 301B can be provided with different drive voltages. Advantageously, greater control of the reduction of the luminance profile can be achieved or a switch between privacy and landscape operations can be provided.
[0365] [0365] The delay control layer 330B can comprise a passive compensation retarder 330A disposed between the first additional polarizer 318A and the other additional polarizer 318B. More generally, the switchable liquid crystal retarder 301A can be omitted and a fixed luminance reduction can be provided by the passive compensation retarders 330A. For example, the luminance reduction in observation quadrants can only be provided through the 330A layer. Advantageously, an increased area of the polar region can be obtained for luminance reduction. In addition, backlights can be provided that have a wider lighting output angle than collimated backlights, increasing the visibility of the screen in wide angle operation mode.
[0366] [0366] Figure 22B is a schematic diagram illustrating a side perspective view of an arrangement of the first switchable compensated retarder at the entrance of a liquid crystal display and a second switchable compensated retarder arranged at the exit of a liquid crystal display.
[0367] [0367] The first additional polarizer mentioned 318A is disposed on the input side of the input screen polarizer 210 between the input screen polarizer 210 and the backlight 20, and the display device further comprises: another additional polarizer 318B disposed on the output side of the output screen polarizer 218; and additional retarders 301B, 330B disposed between the other additional polarizer 318B and the output screen polarizer 218. The additional retarders comprise a switchable liquid crystal retarder 301B comprising a layer of liquid crystal material 414B and electrodes 413B, 415B on sides opposed to the liquid crystal material layer 414B, the liquid crystal material layer 414B being switchable between two orientation states through a voltage being applied to electrodes 413B, 415B.
[0368] [0368] Figure 22C is a schematic diagram illustrating a side perspective view of an optical angle of view control element comprising a first passive compensation retarder, a first switchable liquid crystal retarder, a first 250 control polarizer , a second passive compensation retarder, a second switchable liquid crystal retarder and a second control polarizer 250. Such an element can achieve performance similar to that of Figure 22B when provided for a display device 100 comprising a space light modulator 48.
[0369] [0369] It may be desirable to provide both entertainment and night operating modes in a motor vehicle.
[0370] [0370] Figure 22D is a schematic diagram that illustrates a top view of an automotive vehicle with a switchable directional screen like the one illustrated in Figure 22B arranged inside the vehicle cabin 602 for daytime and / or sharing modes of operation; and Figure 22E is a schematic diagram illustrating a side view of an automotive vehicle with a switchable directional screen disposed within the vehicle cabin 602 for daytime and / or sharing modes. The light cone 630, 632 has a wide angular field of view and thus the screen is advantageously visible to multiple occupants.
[0371] [0371] Figure 22F is a schematic diagram illustrating a top view of an automotive vehicle with a switchable directional screen like the one illustrated in Figure 22B arranged inside the cabin of vehicle 602 for night and / or entertainment modes of operation; Figure 22G is a schematic diagram illustrating a side view of an automotive vehicle with a switchable directional screen disposed within the cabin of vehicle 602 for night and / or entertainment modes of operation. The light cone 634, 636 has a narrow angled field of view and thus the screen is advantageously visible only by a single occupant. Advantageously, the diffused light for night operation is reduced, increasing driver safety. In addition, reflections from the screen from window 601 are reduced, minimizing driver distraction 604.
[0372] [0372] It would be desirable to provide a reduction in the field of view for light cones that are created by wide-angle lighting backlights and low-cost, emissive spatial light modulators.
[0373] [0373] Figure 23A is a schematic diagram illustrating a side perspective view of an arrangement of an additional reflective polarizer 318A and a passive retarder 270 arranged at the entrance of a space light modulator 48. At the exit of the space light modulator 48 there are multiple retarders 300 similar to those in the device of Figure 22B. In comparison to the arrangement of Figure 22B, passive retarder 270 is provided in place of the rear switchable compensated liquid crystal retarder 300A. Advantageously, the cost and thickness are reduced, while low illumination outside the geometric axis is achieved in the private operating mode and an acceptable viewing angle in the wide operating mode.
[0374] [0374] Figure 23B is a schematic diagram illustrating a side perspective view of an optical angle of view control element comprising a passive retarder 270, a first control polarizer 250A, a passive compensation retarder 330, a retarder switchable liquid crystal display 301 and a second 250B control polarizer. The optical element is arranged in front of a space light modulator 48 to provide a display device.
[0375] [0375] Several passive retarders 270 will now be described, any of which can be applied to any of the above devices.
[0376] [0376] Figure 24A is a schematic diagram illustrating a side perspective view of an optical chain of a passive retarder 270 comprising a negative plate O retarder 272A inclined in a plane orthogonal to the electric vector transmission direction of the polarizer. screen and a negative C-plate retarder 272B, and arranged to provide modification of the field of view of a display device; and Figure 24B is a schematic graph that illustrates the variation of the output transmission with polar directions for the light rays transmitted in Figure 24A, which comprises the structure illustrated in Table 10.
[0377] [0377] Passive retardant 270 thus comprises a passive retarder 272A which is a negative opiate that has an optical axis with a component in the plane of the passive retarder 272A and a component perpendicular to the plane of the passive retarder 272A. In addition, the component in the passive retarder plane extends 90 ° with respect to an electric vector transmission direction that is parallel to the electric vector transmission 219 of the screen polarizer 218. The passive retarder 272B comprises a passive retarder which it has an optical axis perpendicular to the plane of the passive retarder.
[0378] [0378] Advantageously, the luminance can be reduced for lateral observation directions. A movable screen can be comfortably rotated around a horizontal geometry axis while obtaining privacy for onlookers outside the geometrical axis in a lateral direction.
[0379] [0379] Figure 24C is a schematic diagram illustrating a side perspective view of an optical chain of a passive retarder 270 comprising crossed A plates and a positive O plate; and Figure 24D is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in the passive retarder of Figure 24C, which comprises the structure illustrated in Table 11.
[0380] [0380] The passive retarder 270 thus comprises passive retarders 272A, 272B which are crossed A plates and the retarder 272C which has an optical axis with a component in the plane of the passive retarder 272C and a component perpendicular to the plane of the passive retarder 272C . The component in the plane of the passive retarder extends 90 °, in relation to an electric vector transmission direction that is parallel to the electric vector transmission 219 of the screen polarizer 218. Advantageously, the luminance can be reduced for lateral observation directions . A movable screen can be comfortably rotated around a horizontal geometry axis while obtaining privacy for onlookers outside the geometrical axis in a lateral direction.
[0381] [0381] It may be desirable to provide luminance reduction in both lateral and elevated directions.
[0382] [0382] Figure 24E is a schematic diagram illustrating a side perspective view of an optical chain of passive retarders comprising two pairs of crossed A plates; and Figure 24F is a schematic graph illustrating the variation of the output transmission with polar directions for light rays transmitted in the passive retarder of Figure 24E, which comprises the structure illustrated in Table 12.
[0383] [0383] The retarder 270 thus comprises a pair of passive retarders 272, 272D that have optical axes in the plane of the intersecting retarders. The pair of retarders each comprises multiple plates A which have respective optical axes aligned at different angles to each other. The pair of passive retarders 272B, 272C have optical axes that extend 90 ° and 0 °, respectively, with respect to an electric vector transmission direction which is parallel to the electric vector transmission 211 of the screen polarizer 210.
[0384] [0384] The pair of passive retarders 272A, 272D have optical axes that extend at 45 ° and 135 °, respectively, with respect to an electrical vector transmission direction 211 that is parallel to the electrical vector transmission of the screen polarizer 218 .
[0385] [0385] The screen additionally comprises an additional pair of passive retarders 272B, 272C disposed between the first pair of passive retarders 272A, 272D mentioned and which has optical axes in the plane of the intersecting retarders. The pair of passive retarders 272B, 272C have optical axes that extend at 0 ° and 90 °, respectively, with respect to an electrical vector transmission direction 211, 317 that is parallel to the electrical vector transmission of the screen polarizer 210, 316.
[0386] [0386] The delay of each plate A for light of a wavelength of 550 nm can be in a range of 600 nm to 850 nm, preferably in a range of 650 nm to 730 nm, and most preferably in a range from 670 nm to 710 nm. The color change of the light absorbed from a central observation point to an observation point outside the geometric axis can be advantageously reduced.
[0387] [0387] In additional illustrative embodiments, the angle 273A is preferably at least 40 ° and at most 50 °, more preferably at least 42.5 ° and at most 47.5 °, and most preferably minimum 44 ° and maximum 46 °. Preferably, the angle 273D is at least 130 ° and at most 140 °, more preferably at least 132.5 ° and at most 137.5 °, and most preferably at least 134 ° and at most 136 °.
[0388] [0388] In additional illustrative modalities, the internal pair of retarders 272B, 272C may have more flexible tolerances than the external pair of retarders 272A, 272D. Preferably, the angle 273B is at least -10 ° and at most 10 °, more preferably at least -5 ° and at most 5 °, and most preferably at least -2 ° and at most 2 ° . Preferably, the angle 273C is at least 80 ° and at most 100 °, more preferably at least 85 ° and at most 95 °, and most preferably at least 88 ° and at most 92 °.
[0389] [0389] The present modality provides a transmission profile that has some rotational symmetry. Advantageously, the privacy screen can be equipped with reduced image visibility from a wide field of view to lateral or elevated observation positions of a curious person. In addition, such a provision can be used to achieve an improved privacy operation for landscape and portrait operations on a mobile screen. Such an arrangement can be provided in a vehicle to reduce stray light for passengers outside the geometrical axis, and also to reduce the light falling on windows and other glass surfaces on the vehicle.
[0390] [0390] It would be desirable to provide an improved appearance of the image by adding camouflage to the private image seen by the curious 47 in the private operation mode.
[0391] [0391] Figure 25A is a schematic diagram illustrating a side perspective view of an arrangement of a switchable retarder in a private mode of operation comprising a passive negative plate C compensation retardant, and an inline switchable liquid crystal retarder. homeotropically additionally comprising an electrode layer 415 provided with a pattern. Thus, electrodes 415a, 415b, 415c are provided with a pattern to provide at least two regions with a pattern.
[0392] [0392] At least one of the electrodes 413, 415 can be provided with a standard; in this example, electrode 415 is standardized with regions 415a, 415b, 415c and driven by the respective voltage actuators 350a, 350b, 350c with voltages Va, Vb, and Vc. Spans 417 can be provided between electrode regions 415a, 415b, 415c. The slope of material 414a, 414b, 414c can then be adjusted independently to reveal a camouflage pattern with different levels of luminance for viewing outside the geometric axis.
[0393] [0393] In this way, the switchable liquid crystal retarder disposed between the output screen polarizer 218 and the additional absorption polarizer 318 is controlled via addressing electrodes 415a, 415b, 415c and a uniform electrode 413. The addressing electrodes they can be provided with a pattern to provide at least two regions with a pattern comprising electrode 415a and span 417.
[0394] [0394] Figure 25B is a schematic diagram that illustrates a frontal perspective view of the lighting of a primary observer and a curious one next to a private screen with camouflaged controlled luminance. The display device 100 may have dark image data 601 and white background data 603 which are visible to the primary observer 45 in the observation window 26p. By way of comparison, the curious 47 can see the camouflaged image as shown in Figure 25C which is a schematic diagram illustrating a side perspective view of the lighting of a curious near a camouflaged controlled luminance privacy screen. Thus, in the white background regions 603, a camouflage structure can be provided that has a mixed luminance of the white regions 603. The regions with a pattern of electrodes 415a, 415b, 415c are therefore camouflage patterns. At least one of the regions with a standard is individually addressable and is willing to operate in a private mode of operation.
[0395] [0395] Regions with a pattern can be arranged to provide camouflage for multiple spatial frequencies by controlling which patterns are provided during private mode of operation. In an illustrative example, a presentation with 20 mm high text can be provided. A camouflage pattern with a similar size pattern can be provided with a first control of an electrode pattern. In a second example, a photo with wide area content that is more visible to a curious 47 can be provided. The spatial frequency of the camouflage pattern can be reduced to hide the larger area structures by combining the first and second regions electrode to supply the voltage and achieve a resulting lower spatial frequency pattern.
[0396] [0396] Advantageously, a controllable camouflage structure can be provided by adjusting the voltages Va, Vb, and Vc in layer 892. Substantially, no visibility of the camouflage structure can be seen during frontal operation. Additionally, the camouflaged image can be removed as long as Va, Vb and Vc are the same.
[0397] [0397] It would be desirable to provide curious people with luminance outside the geometric axis with a luminance value, for example, less than 1%. Directional backlights that provide low luminance outside the geometric axis and that can be used together with the switchable compensated liquid crystal retardants of the present modalities will now be described. Directional backlights will be described first.
[0398] [0398] A similar pattern formation can be applied to any of the devices described here.
[0399] [0399] It would be desirable to provide a further reduction in luminance outside the geometrical axis through directional illumination from the space light modulator 48. The directional lighting of the space light modulator 48 by directional backlights 20 will now be described.
[0400] [0400] Figure 26A is a schematic diagram illustrating a front perspective view of a directional backlight 20, and Figure 26B is a schematic diagram illustrating a front perspective view of a non-directional backlight 20, and any of them can be applied to any of the devices described here. In this way, a directional backlight 20 as shown in Figure 26A has a narrow cone 450, while a non-directional backlight 20 as shown in Figure 26B offers a wide angular distribution cone 452 of the outgoing light rays.
[0401] [0401] Figure 26C is a schematic graph that illustrates a variation of luminance with side viewing angle for several different backlight arrangements. The graph in Figure 26C can be a cross section through the polar field of view profiles described here.
[0402] [0402] A Lambertian backlight has an 846 luminance profile that is independent of the viewing angle.
[0403] [0403] A wide-angle backlight has a reduction at greater angles so that the total width at half height 866 of relative luminance can be greater than 40 °, preferably greater than 60 °, and most preferably greater than 80 ° . In addition, the relative luminance 864 ° to +/- 45 °, is preferably greater than 7.5%, more preferably greater than 10%, and the most preferably greater than 20%.
[0404] [0404] As a comparison, a directional backlight 20 has a reduction in greater angles so that the total width at half height 862 of relative luminance can be less than 60 °, preferably less than 40 °, and most preferably less than 20 °. In addition, the backlight 20 can provide, at polar angles with normal to the spatial light modulator 48 greater than 45 degrees, a luminance that is at most 33% of the luminance over normal to the spatial light modulator 48, preferably in the maximum 20%
[0405] [0405] Scattering and diffraction in the space light modulator 48 can degrade the private operating mode when the switchable retarder 300 is disposed between the input screen polarizer 210 and the additional polarizer
[0406] [0406] Advantageously, a lower luminance outside the geometric axis can be obtained for the arrangement of Figure 1A in comparison with Figure 2A for the same backlight 20.
[0407] [0407] In an illustrative embodiment of Figure 1A, the luminance at polar angles with the normal to the spatial light modulator 48 greater than 45 degrees can be a maximum of 18%, while in an illustrative embodiment of Figure 2A the luminance in angles polar with the normal to the space light modulator 48 greater than 45 degrees can be a maximum of 10%. Advantageously, the embodiment of Figure 1A can provide a wider freedom of observation in the wide-angle mode of operation and at the same time achieve freedom of observation similar to that of Figure 2A in the private mode of operation.
[0408] [0408] Such luminance profiles can be provided by the directional backlights 20 described below or they can also be provided by the wide-angle backlights in combination with the other additional polarizer 318B and passive retarders 270, or an additional switchable liquid crystal retardant 300B.
[0409] [0409] Figure 27A is a schematic diagram illustrating a side view of a switchable directional display apparatus 100 comprising a switchable liquid crystal retardant 300 and a backlight 20. The backlight 20 of Figure 27A can be applied to any of devices described herein and comprising an imaging waveguide 1 illuminated by a light source array 15 through an input end 2. Figure 27B is a schematic diagram illustrating a rear perspective view of the operation of the waveguide 1 of Figure 27A in a narrow angle operating mode.
[0410] [0410] Imaging waveguides 1 are of the type described in US Patent No. 9,519,153, which is incorporated herein by reference in its entirety. The waveguide 1 has an inlet end 2 that extends in a lateral direction along the waveguide 1. A matrix of light sources 15 is arranged along the inlet end 2 and inserts light into the waveguide 1 .
[0411] [0411] The waveguide 1 also has a first and a second guide surfaces 6, 8 that extend through the waveguide 1 from the inlet end 2 to a reflective end 4 to guide the light entry into the end of inlet 2 back and forth along the waveguide 1. The second guide surface 8 has a plurality of light extraction features 12 facing the reflective end 4 and arranged to deflect at least part of the light guided back through of the waveguide 1 of the reflective end 4, from different inlet positions across the inlet end 2 in different directions through the first guide surface 6, which depend on the inlet position.
[0412] [0412] In operation, the light rays are directed from the light source matrix 15 through an input end and are guided between the first and second guide surfaces 6, 8 to a reflective end 4, without loss. The reflected rays strike facets 12 and are reflected as rays of light 230 or are transmitted as rays of light 232. The rays of transmitted light 232 are directed back through waveguide 1 by facets 803, 805 of the reflector rear 800. The operation of the rear reflectors is further described in US patent no.
[0413] [0413] As shown in Figure 27B, the optical power of the curved reflective end 4 and the facets 12 provide an optical window 26 that is transmitted through the spatial light modulator 48 and has a geometric axis 197 that is typically aligned with the optical axis 199 of the waveguide 1. A similar optical window 26 is provided by the transmitted rays of light 232 which are reflected by the rear reflector 800.
[0414] [0414] Figure 27C is a schematic graph that illustrates the luminance plot of field of view of the Figure 27B output when used on a display device without any switchable liquid crystal retarder.
[0415] [0415] Thus, observation positions outside the geometric axis for onlookers 47 may have reduced luminance, for example between 1% and 3% of the central peak luminance at an elevation of 0 degrees and a lateral angle of +/- 45 degrees. Additionally, the luminance reduction outside the geometric axis is obtained by the multiple retarders 301, 330 of the present modalities.
[0416] [0416] The following text describes another type of directional backlight with low luminance outside the geometric axis.
[0417] [0417] Figure 28A is a schematic diagram illustrating a side view of a switchable directional display apparatus comprising a backlight 20 that includes a switchable collimation waveguide 901 and a switchable liquid crystal retarder 300, and an additional polarizer 318. The backlight 20 of Figure 28A can be applied to any of the devices described herein and is arranged as described below.
[0418] [0418] The waveguide 901 has an input end 902 that extends in a lateral direction along the waveguide 901. An array of light sources 915 is arranged along the input end 902 and inserts light into the guide waveguide 1. The waveguide 901 also has a first and a second guide surface 906, 908 that extend through the waveguide 1 from the inlet end 2 to a reflective end 4 to guide the light inlet at the end inlet 2 back and forth along the waveguide 1. In operation, the light is guided between the first and second guide surfaces 906, 908.
[0419] [0419] The first guide surface 906 can be provided with a lenticular structure 904 which comprises a plurality of elongated lenticular elements 905, and the second guide surface 908 can be provided with prismatic structures 912 that are inclined and act as extraction features. of light. The plurality of elongated lenticular elements 905 of the lenticular structure 904 and the plurality of inclined light extraction features deflect the incoming light guided through the waveguide 901 to exit through the first guide surface 906.
[0420] [0420] A rear reflector 903, which can be a flat reflector, is provided to direct the light that is transmitted through the surface 908 back through the waveguide 901.
[0421] [0421] The outgoing light rays that fall on the prismatic structures 912 and the lenticular elements 905 of the lenticular structure 904 are emitted at angles close to that of low incidence with the surface 906. A prismatic curved film 926 comprising facets 927 is arranged to redirect the output light rays 234 by total internal reflection through the spatial light modulator 48 and the compensated switchable liquid crystal retardant 300.
[0422] [0422] Figure 28B is a schematic diagram illustrating a top view of the collimation waveguide output 901. The prismatic structures 912 are arranged to provide light at angles of incidence on the lenticular structure 904 which are below the critical angle and in that way, they can escape. In view of the edges of a lenticular surface, the inclination of the surface provides a deflection of light for the escaping rays and provides a collimation effect. The ray of light 234 can be provided by the rays of light 188a-c and the rays of light 189a-c, focusing on locations 185 of the lenticular structure 904 of the collimated waveguide 901.
[0423] [0423] Figure 28C is a schematic graph that illustrates a polar plot of the iso-luminance field of view for the display apparatus of Figure 28A. In this way, a narrow exit light cone can be provided, with its size determined by structures 904, 912 and curved film 926.
[0424] [0424] Advantageously, in regions where onlookers may be located at lateral angles of 45 degrees or more, for example, the luminance of the screen output is small, typically less than 2%. It would be desirable to achieve an additional reduction in the output luminance. Such additional reduction is provided by the switchable compensated liquid crystal retarder 300 and the additional polarizer 318 illustrated in Figure 28A. Advantageously, a high-performance privacy screen with low luminance outside the geometric axis can be provided over a wide field of view.
[0425] [0425] Directional backlights, like the types described with reference to Figures 27A and 28A, together with the multiple retarders 301, 330 of the present modalities, can achieve luminance outside the geometric axis less than 1.5%, preferably less than 0.75%, and with the maximum preference less than 0.5% for typical places of a curious 47. In addition, a high luminance and uniformity in the geometric axis can be provided to the primary user 45. Advantageously, a high privacy screen low luminance performance outside the geometric axis can be provided over a wide field of view, which can be switched to a wide angle mode through control of the switchable retarder 301 via the control system 352 illustrated in Figure 1A.
[0426] [0426] The operation of a retarder layer between parallel polarizers for off-axis lighting will now be described in detail. In the various devices described above, the retarders are arranged between a pair of polarizers (typically the additional polarizer 318 and one between the input polarizer 210 and the output polarizer 218) in several different configurations. In each case, the retarders are configured so as not to affect the luminance of the light that passes through the pair of polarizers and the multiple retarders along a geometric axis along the normal to the plane of the retarders, but they do reduce the luminance of the light that passes through the pair of polarizers and the multiple retarders along an inclined geometric axis relative to the normal plane of the retarders, at least in one of the switchable states of the switchable compensated retarder 300. A description will now be provided in more detail of this effect, whose principles can be applied in general to all the devices described above.
[0427] [0427] Figure 29A is a schematic diagram illustrating a perspective view of the illumination of a light-retardant layer outside the geometric axis. A correction retarder 630 may comprise birefringent material, represented by the refractive index ellipsoid 632 with the optical axis direction 634 at 0 degree of the x axis, and have a thickness 631. Normal light rays 636 propagate so that the path length in the material is equal to thickness 631. The light rays 637 that are in the yz plane have an increased path length; however, the birefringence of the material is substantially the same as that of rays 636. As a comparison, light rays 638 that are in the xz plane have an increase in the length of the birefringent material path and, in addition, birefringence is different from the radius normal 636.
[0428] [0428] The delay of retarder 630 therefore depends on the angle of incidence of the respective radius, and also on the plane of incidence, that is, rays 638 in the xz plane will have a different delay from normal rays 636 and rays 637 in the plane yz.
[0429] [0429] The interaction of polarized light with the 630 retarder will now be described. In order to distinguish between the first and the second polarization components during operation in a directional backlight 101, the following explanation will refer to a third and fourth polarization components.
[0430] [0430] Figure 29B is a schematic diagram illustrating a perspective view of the illumination of a light-retardant layer outside the geometric axis of a third linear polarization state at 90 degrees of the x-axis, and Figure 29C is a diagram schematic illustrating a perspective view of the illumination of a light-retardant layer outside the geometric axis of a fourth state of linear polarization at 0 degrees of the x axis. In such arrangements, the incident linear polarization states are aligned with the optical axes of the birefringent material, represented by the 632 ellipse. Consequently, there is no phase difference between the third and fourth orthogonal polarization components, and there is no resulting change of the polarization state of the linearly polarized input for each radius 636, 637, 638. Thus, the retarder 630 does not introduce a phase shift in the polarizing components of the light that passed through the polarizer on the input side of the retarder 630 along an axis geometric along the normal to the plane of the retarder
[0431] [0431] Figure 29D is a schematic diagram illustrating a perspective view of the illumination of a layer of retarder 630 by light outside the geometric axis of a first 45 degree linear polarization state. The linear polarization state can be separated into a third and fourth polarization components that are, respectively, orthogonal and parallel to the direction of the optical axis 634. The thickness of the retarder 631 and the retardation of the material represented by the refractive index ellipsoid 632 can provide a net effect of relative phase shift of the third and fourth polarizing components incident on it in a normal direction represented by radius 636 for half a wavelength, for a projected wavelength. The projected wavelength can, for example, be in the range of 500 to 550 nm.
[0432] [0432] At the projected wavelength and for light that normally propagates along radius 636, the output bias can be rotated 90 degrees to a state of linear polarization from 640 to -45 degrees. The light that propagates along radius 637 can experience a phase difference that is similar, but not identical, to the phase difference along radius 637 due to the change in thickness, and thus an elliptical polarization state can be transmitted 639 which may have a main axis similar to the linear polarization axis of the output light for radius 636.
[0433] [0433] By contrast, the phase difference for the incident linear polarization state along radius 638 can be significantly different, in particular a lower phase difference can be provided. Such a phase difference can provide an output polarization state 644 that is substantially circular at a given angle of inclination 642. Thus, retarder 630 introduces a phase shift in the polarizing components of the light that has passed through the polarizer on the input side of the retarder 630 along a geometric axis corresponding to radius 638 which is inclined from normal to the plane of retarder 630. Although Figure 29D is related to retarder 630 which is passive, a similar effect is achieved by a switchable liquid crystal retarder , and the multiple retarders described above, in a switchable state of the switchable liquid crystal retarder corresponding to the private mode.
[0434] [0434] To illustrate the off-axis behavior of retarder chains, the angular luminance control of C 308A, 308B plates between an additional polarizer 318 and an output screen polarizer 218 will now be described in various lighting arrangements outside the geometric axis in relation to the operation of a C 560 plate between parallel polarizers 500, 210.
[0435] [0435] Figure 30A is a schematic diagram illustrating a perspective view of the illumination of a layer of plate C by polarized light outside the geometric axis with a positive elevation. The incident linear polarization component 704 focuses on the birefringent material 632 of retarder 560 which is a C plate with an optical axis direction 507 that is perpendicular to the plane of retarder 560. Polarization component 704 sees no difference in liquid phase in the transmission through the liquid crystal molecule and therefore the output bias component is equal to component 704. Thus, a maximum transmission is seen through polarizer 210. In this way, the retarder comprises a retarder 560 that has an optical axis 561 perpendicular to the plane of retarder 560, which is the xy plane. The retarder 560 which has an optical axis perpendicular to the plane of the retarder comprises a plate C.
[0436] [0436] Figure 30B is a schematic diagram illustrating a perspective view of the illumination of a layer of plate C by polarized light outside the geometric axis with a negative side angle. As with the arrangement of Figure 30A, polarization state 704 sees no difference in liquid phase and is transmitted at maximum luminance. Thus, retarder 560 does not introduce a phase shift in the polarizing components of the light that passed through the polarizer on the input side of retarder 560 along a geometric axis along the normal to the plane of retarder 560. Consequently, retarder 560 does not affects the luminance of the light that passes through the 560 retarder and the polarizers (not shown) on each side of the 560 retarder. Although Figures 29A to 29C refer specifically to the 560 retarder which is passive, a similar effect is achieved by a switchable liquid crystal and multiple retarders on the devices described above.
[0437] [0437] Figure 30C is a schematic diagram illustrating a perspective view of the illumination of a layer of plate C by polarized light outside the geometric axis with a positive elevation and a negative side angle. In comparison with the arrangement of Figures 30A and 30B, the polarization state 704 is resolved in the eigenvectors 703, 705 in relation to the birefringent material 632 providing a difference in liquid phase in the transmission through the retarder 560. The resulting elliptical polarization component 656 is transmitted through polarizer 210 with reduced luminance compared to the rays illustrated in Figures 30A and 30B.
[0438] [0438] Figure 30D is a schematic diagram illustrating a perspective view of the illumination of a layer of plate C by polarized light outside the geometric axis with a positive elevation and a positive lateral angle. In a similar way to Figure 30C, the polarization component 704 is solved in eigenvectors 703, 705 that undergo a liquid phase difference, and an elliptical polarization component 660 is provided, which after transmission through the polarizer reduces the luminance of the respective radius outside the geometric axis. In this way, retarder 560 introduces a phase shift in the polarizing components of the light that passed through the polarizer on the input side of retarder 560 along a geometric axis that is inclined from normal to the plane of retarder 560. Although Figure 29D is related to the 560 retardant which is passive, a similar effect is achieved by a switchable liquid crystal retarder,
[0439] [0439] Figure 30E is a schematic graph that illustrates the variation of the output transmission with polar directions for rays of light transmitted in Figures 30A to 30D. Thus, plate C can provide luminance reduction in polar quadrants. In combination with the switchable liquid crystal retardant 301 described elsewhere in this document, (i) the removal of dimming from plate C can be done in a first wide-angle operating state, and (ii) an extended polar region for luminance reduction can be obtained in a second private operating state.
[0440] [0440] To illustrate the off-axis behavior of retarder chains, the angular luminance control of crossed plates A 308a, 308b between an additional polarizer 318 and an output screen polarizer 218 will now be described in various lighting arrangements outside of the geometric axis.
[0441] [0441] Figure 31A is a schematic diagram illustrating a perspective view of the illumination of the layers of a plate retarder A crossed by polarized light outside the geometric axis with a positive elevation. A linear polarizer 218 with an electric vector transmission direction 219 is used to provide a linear polarization state 704 that is parallel to the lateral direction on the first A 308A plate among the crossed A 308A, 308B plates. The optical axis direction 309A is tilted at +45 degrees in the lateral direction. The retardation of the retarder 308A to the angle outside the geometric axis θ 1 in the positive elevation direction provides a resulting polarization component 650 that is generally elliptical at the output. The polarization component 650 focuses on the second plate A 308B among the crossed plates A 308A, 308B which has an optical axis direction 309B which is orthogonal to the optical axis direction 309A of the first plate A 308A. In the plane of incidence of Figure 31A, the delay of the second plate A 308B to the angle outside the geometric axis θ1 is equal and opposite to the delay of the first plate A 308A. In this way, a zero loss delay is provided for the incident polarization component 704 and the output polarization component is the same as the input polarization component 704.
[0442] [0442] The output bias component is aligned with the electrical vector transmission direction of the additional polarizer 318, and is thus transmitted efficiently. Advantageously, no substantial loss is experienced by light rays that have an angular component of zero lateral angle, so that full transmission efficiency is achieved.
[0443] [0443] Figure 31B is a schematic diagram illustrating a perspective view of the illumination of layers of a plate retarder A crossed by polarized light outside the geometric axis with a negative side angle. In this way, the input bias component is converted by the first plate A 308A into an intermediate bias component 652 which is generally an elliptical bias state. The second plate A 308B again provides a delay equal to and opposite to that of the first plate A so that the output bias component is equal to the input bias component 704 and the light is efficiently transmitted through polarizer 318.
[0444] [0444] Thus, the retarder comprises a pair of retarders 308, 308B that have optical axes in the plane of the intersecting retarders 308A, 308B, which is the x-y plane in the present modalities. The pair of retarders 308A, 308B have optical axes 309A, 309B that extend at 45 ° with respect to an electric vector transmission direction that is parallel to the electric vector transmission of polarizer 318.
[0445] [0445] Advantageously, no substantial loss is experienced by light rays that have an angular component of zero lateral elevation, so that full transmission efficiency is achieved.
[0446] [0446] Figure 31C is a schematic diagram illustrating a perspective view of the illumination of the layers of a plate retarder A crossed by polarized light outside the geometric axis with a positive elevation and a negative side angle. Polarization component 704 is converted to an elliptical polarization component 654 by the first plate A 308A. A resulting elliptical component 656 is transmitted from the second plate
[0447] [0447] Figure 31D is a schematic diagram illustrating a perspective view of the illumination of layers of a plate retarder A crossed by polarized light outside the geometric axis with a positive elevation and a positive side angle. Polarizing components 658 and 660 are provided by the first and second plates A 308A, 308B, since the net delay of the first and second retarders does not provide compensation.
[0448] [0448] In this way, luminance is reduced for light rays that have a non-zero side angle and non-zero elevation components. Advantageously, the privacy of the screen can be increased for onlookers who are arranged in observation quadrants, while the luminous efficiency for the main users of the screen is not substantially reduced.
[0449] [0449] Figure 31E is a schematic graph that illustrates the variation of the output transmission with polar directions for light rays transmitted in Figures 30A to 30D. In comparison to the arrangement in Figure 30E, the luminance reduction area is increased for observation outside the geometric axis. However, the switchable liquid crystal retarder 301 can provide reduced uniformity compared to the plate C arrangements for off-axis observation in the first wide operating state.
[0450] [0450] As used here, the terms "substantially" and "approximately" provide an industry-accepted tolerance for their corresponding term and / or relativity between items. Such tolerance accepted in the industry ranges from zero percent to ten percent, and corresponds to, but is not limited to, component values, angles, etc. Such relativity between items varies between approximately zero percent and ten percent.
[0451] [0451] Although several modalities have been described above according to the principles disclosed here, it should be understood that they were presented only as an example, and not as a limitation. Accordingly, the extent and scope of this disclosure should not be limited by any of the exemplary modalities described above, but should be defined only in accordance with any claims and their equivalents arising from this disclosure. In addition, the advantages and resources presented above are provided in the modalities described, but should not limit the application of such claims granted to processes and structures that provide any or all of the above advantages.
[0452] [0452] Additionally, the section headings in this document are provided for consistency with the suggestions under 37 CFR 1.77, or to otherwise provide organizational cues. These headings should not limit or characterize the modality (s) defined in any of the claims that may derive from this disclosure. Specifically and by way of example, although the headings refer to a "Technical Field", claims should not be limited by the language chosen under that heading to describe the so-called field. In addition, a description of a technology in the "Background" section should not be interpreted as an admission that a particular technology is prior art to any modality in this disclosure. Likewise, the "Summary" section should not be considered as a characterization of the modality (s) presented in the claims granted. Furthermore, any reference in this revelation to the "invention" used in the singular way should not be used as an argument that there is only a single point of innovation in this revelation. Multiple modalities can be presented according to the limitations of the multiple claims arising from this disclosure, and such claims consequently define the modalities, and their equivalents, that are thus protected. In all instances, the scope of such claims should be considered by itself in the light of this disclosure, but should not be constrained by the headings described herein.

权利要求:
Claims (59)
[1]
1. Display device, characterized by comprising: a spatial light modulator; a screen polarizer arranged on one side of the space light modulator; an additional polarizer arranged on the same side of the space light modulator as the screen polarizer; and multiple retarders arranged between the additional polarizer and the screen polarizer; the multiple retarders comprising: a switchable liquid crystal retarder comprising a layer of liquid crystal material; and at least one passive compensation retarder.
[2]
2. Display device according to claim 1, characterized in that the screen polarizer and the additional polarizer have electrical vector transmission directions that are parallel.
[3]
Display device according to claim 1 or claim 2, characterized in that the switchable liquid crystal retarder comprises two layers of surface alignment disposed adjacent to the layer of liquid crystal material and on opposite sides thereof, and each arranged to provide homeotropic alignment in the adjacent liquid crystal material.
[4]
Display device according to claim 3, characterized in that the liquid crystal material layer of the switchable liquid crystal retarder comprises a liquid crystal material with a negative dielectric anisotropy.
[5]
Display device according to claim 3 or claim 4, characterized in that the layer of liquid crystal material has a light delay of a wavelength of 550 nm in a range from 500 nm to 1000 nm, from preferably in a range from 600 nm to 900 nm, and most preferably in a range from 700 nm to 850 nm.
[6]
Display device according to any of claims 3 to 5, characterized in that: the at least one passive compensation retarder comprises a retarder that has its optical axis perpendicular to the plane of the retarder, the at least one passive retarder has a delay for light with a wavelength of 550 nm in the range of -300 nm to -900 nm, preferably in the range of -450 nm to -800 nm, and most preferably in the range of -500 nm to - 725 nm; or at least one passive compensating retarder comprises a pair of retarders that have optical axes in the plane of the retarders that are crossed, each retarder in the pair of retarders having a light delay of a wavelength of 550 nm over a range of 400 nm to 1800 nm, preferably in a range of 700 nm to 1500 nm, and most preferably in a range of 900 nm to 1300 nm.
[7]
Display device according to claim 1 or claim 2, characterized in that the switchable liquid crystal retarder comprises two layers of surface alignment disposed adjacent to the layer of liquid crystal material and on opposite sides thereof, and each arranged to provide homogeneous alignment in the adjacent liquid crystal material.
[8]
Display device according to claim 7, characterized in that the liquid crystal material layer of the switchable liquid crystal retarder comprises a liquid crystal material with a positive dielectric anisotropy.
[9]
Display device according to claim 7 or claim 8, characterized in that the layer of liquid crystal material has a light delay of a wavelength of 550 nm in a range from 500 nm to 1000 nm, from preferably in a range from 600 nm to 850 nm, and most preferably in a range from 700 nm to 800 nm.
[10]
Display device according to any of claims 7 to 9, characterized by:
the at least one passive compensation retarder comprises a retarder that has its optical axis perpendicular to the plane of the retarder, the at least one passive retarder having a light delay of a wavelength of 550 nm in a range of -300 nm to - 700 nm, preferably in the range of -350 nm to -600 nm, and most preferably in the range of -400 nm to -500 nm; or the at least one passive compensation retarder comprises a pair of retarders that have optical axes in the plane of the retarders that are crossed, with each retarder in the pair of retarders having a light delay of a wavelength of 550 nm in a range from 300 nm to 800 nm, preferably in a range from 350 nm to 650 nm, and most preferably in a range from 450 nm to 550 nm.
[11]
Display device according to claim 1 or claim 2, characterized in that the switchable liquid crystal retarder comprises two layers of surface alignment arranged adjacent to the layer of liquid crystal material and on opposite sides thereof, one of the surface alignment layers arranged to provide homeotropic alignment in the adjacent liquid crystal material and the other surface alignment layer arranged to provide homogeneous alignment in the adjacent liquid crystal material.
[12]
Display device according to claim 11, characterized in that the surface alignment layer arranged to provide homogeneous alignment is between the layer of liquid crystal material and the compensation retarder; the layer of liquid crystal material has a light delay of a wavelength of 550 nm in a range from 700 nm to 2000 nm, preferably in a range of 1000 nm to 1500 nm, and most preferably in a range from 1200 nm to 1500 nm; and the at least one passive compensation retarder comprises a retarder that has its optical axis perpendicular to the plane of the retarder, the at least one passive retarder having a light delay of a wavelength of 550 nm in a range of -400 nm to -1800 nm, preferably in a range of -700 nm to -1500 nm, and most preferably in a range of -900 nm to -1300 nm; or the at least one passive compensation retarder comprises a pair of retarders that have optical axes in the plane of the retarders that are crossed, with each retarder in the pair of retarders having a light delay of a wavelength of 550 nm in a range from 400 nm to 1800 nm, preferably in a range from 700 nm to 1500 nm, and most preferably in a range from 900 nm to 1300 nm.
[13]
Display device according to claim 11, characterized in that the surface alignment layer arranged to provide homeotropic alignment is between the layer of liquid crystal material and the compensation retardant; the layer of liquid crystal material has a light delay of a wavelength of 550 nm in a range from 500 nm to 1800 nm, preferably in a range from 700 nm to 1500 nm, and most preferably in a range from 900 nm to 1350 nm; and the at least one passive compensation retarder comprises a retarder that has its optical axis perpendicular to the plane of the retarder, the at least one passive retarder having a light delay of a wavelength of 550 nm over a range of -300 nm to -1600 nm, preferably in the range of -500 nm to -1300 nm, and most preferably in the range of -700 nm to -1150 nm; or the at least one passive compensation retarder comprises a pair of retarders that have optical axes in the plane of the retarders that are crossed, with each retarder in the pair of retarders having a light delay of a wavelength of 550 nm in a range from 400 nm to 1600 nm, preferably in the range of 600 nm to 1400 nm, and most preferably in the range of 800 nm to 1300 nm.
[14]
Display device according to any of claims 3 to 13, characterized in that each alignment layer has a pre-inclination that has a pre-inclination direction with a component in the plane of the liquid crystal layer that is parallel or antiparallel or orthogonal to the electrical vector transmission direction of the screen polarizer.
[15]
Display device according to any of the preceding claims, characterized in that the at least one passive retarder comprises at least two passive retarders with at least two different optical axis orientations.
[16]
Display device according to any of the preceding claims, characterized in that the at least one passive compensating retarder comprises a pair of passive retarders that have optical axes in the plane of the intersecting retarders.
[17]
17. Display device according to claim 16, characterized in that the pair of passive retarders have optical axes that extend at 45 ° and 135 °, respectively, in relation to an electric vector transmission direction that is parallel to the transmission vector image of screen polarizer.
[18]
Display device according to claim 16 or claim 17, characterized in that the switchable liquid crystal retarder is provided between the pair of passive retarders.
[19]
19. Display device according to claim 18, characterized in that it additionally comprises a transparent electrode and a liquid crystal alignment layer formed on one side of each of the pair of passive retarders adjacent to the switchable liquid crystal retarder.
[20]
Display device according to claim 19, characterized in that it additionally comprises a first and a second substrate between which the switchable liquid crystal retarder is provided, the first and second substrates each comprising one of the pair of passive retarders.
[21]
21. Display device according to claim 20, characterized in that each of the pair of retarders has a light delay of a wavelength of 550 nm in a range from 150 nm to 800 nm, preferably in a range from 200 nm to 700 nm, and with the most preference in a range of 250 nm to 600 nm.
[22]
22. Display device according to any of the preceding claims, characterized in that the at least one passive compensation retarder comprises a retarder that has an optical axis perpendicular to the plane of the retarder.
[23]
Display device according to claim 22, characterized in that the at least one passive compensating retarder comprises two passive retarders that have an optical axis perpendicular to the plane of the passive retarders, and the switchable liquid crystal retarder is provided between the two passive retarders.
[24]
24. Display device according to claim 23, characterized in that it further comprises a transparent electrode and a liquid crystal alignment layer formed on one side of each between the two passive retarders adjacent to the switchable liquid crystal retarder.
[25]
Display device according to claim 23 or claim 24, characterized in that it additionally comprises a first and a second substrate between which the switchable liquid crystal retarder is provided, the first and second substrates each comprising one of the two passive retarders.
[26]
26. Display device according to any of claims 23 to 25, characterized in that the two passive retarders have a total delay for light of a wavelength of 550 nm in a range of -300 nm to -700 nm, preferably in a range from -350 nm to -600 nm, and most preferably in a range from -400 nm to -500 nm.
[27]
27. Display device according to any of the preceding claims, characterized in that the at least one passive compensation retarder comprises a retarder that has an optical axis with a component perpendicular to the plane of the retarder and with a component in the plane of the retarder.
[28]
28. Display device according to claim 27, characterized in that the component in the plane of the passive retarder extends to 0 °, in relation to an electric vector transmission direction that is parallel or perpendicular to the polarizer electric vector transmission of screen.
[29]
29. Display device according to claim 27 or claim 28, characterized in that the at least one passive retarder additionally comprises a passive retarder having an optical axis perpendicular to the plane of the passive retarder or a pair of passive retarders having axes in the plane of the passive intersecting retarders.
[30]
Display device according to any of the preceding claims, characterized in that the delay of the at least one passive compensation retarder is the same and opposite to the delay of the switchable liquid crystal retarder.
[31]
31. Display device according to any of the preceding claims, characterized in that: the adjustable liquid crystal retarder comprises a first and a second pre-slope; and the at least one passive compensation retarder comprises a compensation retarder with a first and a second pre-slope, the first pre-slope of the compensation retarder is equal to the first pre-slope of the liquid crystal retarder and the second pre-slope. inclination of the compensation retarder is equal to the second pre-inclination of the liquid crystal retarder.
[32]
32. Display device according to any of the preceding claims, characterized in that the at least one passive compensation retarder is arranged not to introduce any phase shift in the polarization components of the light that has passed through one of the screen polarizer and the additional polarizer on the input side of the multiple retarders along a geometric axis along the normal to the plane of at least one passive compensation retarder.
[33]
33. Display device according to any of the preceding claims, characterized in that the at least one passive compensation retarder is arranged to introduce a phase shift in the polarization components of the light that has passed through one of the screen polarizer and the polarizer additional on the input side of the multiple retarders along an inclined geometric axis relative to the normal to the plane of at least one passive compensation retarder.
[34]
34. Display device according to any of the preceding claims, characterized in that the switchable liquid crystal retarder is arranged not to introduce any phase shift in the polarization components of the light that has passed through one of the screen polarizer and the additional polarizer on the input side of the multiple retarders along a geometric axis along the normal to the plane of the switchable liquid crystal retarder.
[35]
35. Display device according to any of the preceding claims, characterized in that the switchable liquid crystal retarder is arranged to introduce a phase shift in the polarization components of the light that has passed through one of the screen polarizer and the additional polarizer in the input side of the multiple retarders along an inclined geometric axis relative to the normal to the plane of the switchable liquid-retardant in a switchable state of the switchable liquid-retardant.
[36]
36. Display device according to any of the preceding claims, characterized in that the multiple retarders are arranged so as not to affect the luminance of the light that passes through the screen polarizer, the additional polarizer and the multiple retarders along a geometric axis along from normal to the plane of retarders.
[37]
37. Display device according to any one of the preceding claims, characterized in that the multiple retarders are arranged to reduce the luminance of the light that passes through the screen polarizer, the additional polarizer and the multiple retarders along an inclined geometric axis in relation to normal to the plane of the retarders.
[38]
38. Display device according to any of the preceding claims, characterized in that the switchable liquid crystal retarder additionally comprises electrodes for applying a voltage to control the layer of liquid crystal material.
[39]
39. Display device according to claim 38, characterized in that the electrodes are on opposite sides of the layer of liquid crystal material.
[40]
40. Display device according to claim 38 or claim 40, characterized in that the electrodes are provided with a pattern to provide at least two regions with a pattern.
[41]
41. Display device according to any of claims 38 to 40, characterized in that it additionally comprises a control system arranged to control the voltage applied to the electrodes of at least one switchable liquid crystal retarder.
[42]
42. Display device according to claim 41, characterized in that the control system additionally comprises a means for determining the location of a curious person in relation to the screen and the control system is arranged to adjust the voltage applied to the hair electrodes minus a switchable liquid crystal retardant in response to the location of the curious.
[43]
43. Display device according to any of the preceding claims, characterized in that it additionally comprises at least one additional retarder and one additional polarizer, the at least one additional retarder being disposed between the first mentioned additional polarizer and the other additional polarizer .
[44]
44. Display device according to any of the preceding claims, characterized in that it additionally comprises a backlight arranged to emit light, the spatial light modulator being a transmissive spatial light modulator arranged to receive light from the backlight output.
[45]
45. Display device according to claim 44, characterized in that the backlight provides, at polar angles with the normal to the spatial light modulator greater than 45 degrees, a luminance that is at most 33% of the luminance over normal at spatial light modulator, preferably at most 20% of the luminance over normal to the spatial light modulator, and most preferably at most 10% of the luminance over normal to the spatial light modulator.
[46]
46. Display device according to claim 44 or claim 45, characterized in that the backlight comprises: a set of light sources; a directional waveguide comprising: an entrance end that extends in a lateral direction along one side of the directional waveguide, the light sources being arranged along the entrance end and arranged to insert light from entry in the waveguide; and an opposing first and second guide surfaces extending through the directional waveguide from the inlet end to guide the entry of light into the inlet end along the waveguide, the waveguide being arranged to deflect the entry light guided through the directional waveguide to exit through the first guide surface.
[47]
47. Display device according to claim 46, characterized in that the backlight additionally comprises a curved reflective film and the directional waveguide is a collimation waveguide.
[48]
48. Display device according to claim 47, characterized in that the collimation waveguide comprises: (i) a plurality of elongated lenticular elements; and (ii) a plurality of inclined light extraction resources, the plurality of elongated lenticular elements and the plurality of inclined light extraction resources are oriented to deflect the incoming light guided through the directional waveguide to exit through the first guide surface.
[49]
49. Display device according to claim 46, characterized in that the directional waveguide is an imaging waveguide arranged to imagine the light sources in the lateral direction so that the light output from the light sources is directed for the respective optical windows in exit directions that are distributed based on the input positions of the light sources.
[50]
50. Display device according to claim 49, characterized in that the imaging waveguide comprises a reflective end to reflect the incoming light back along the imaging waveguide, the second guide surface being arranged to deflect the incoming light reflected through the first guide surface as the exit light, the second guide surface comprises light extraction features and intermediate regions between the light extraction features, the light extraction features being they are oriented to deflect the incoming light reflected through the first guide surface as an exit light and the intermediate regions are arranged to direct the light through the waveguide without extracting it; and the reflective end having a positive optical power in the lateral direction extending between the sides of the waveguide extending between the first and the second guide surfaces.
[51]
51. Display device according to any of claims 44 to 50, characterized in that the screen polarizer is an input screen polarizer arranged on the input side of the space light modulator between the backlight and the space light modulator, and the additional polarizer is arranged between the input screen polarizer and the backlight.
[52]
52. Display device according to claim 51, characterized in that the additional polarizer is a reflective polarizer.
[53]
53. Display device according to claim 51 or claim 52, characterized in that the display device further comprises an output polarizer arranged on the output side of the space light modulator.
[54]
54. Display device according to any of claims 1 to 50, characterized in that the screen polarizer is an output polarizer arranged on the output side of the space light modulator.
[55]
55. Display device according to claim 54, characterized in that the display device additionally comprises an input polarizer arranged on the input side of the space light modulator.
[56]
56. Display device according to claim 55, characterized in that it additionally comprises another additional polarizer disposed on the input side of the space light modulator and at least one additional retarder disposed between the at least one additional additional polarizer and the input polarizer. input.
[57]
57. Display device according to any of claims 1 to 43, characterized in that the spatial light modulator comprises an emissive spatial light modulator for emitting light and the screen polarizer is an output screen polarizer arranged on the output side of the emissive space light modulator.
[58]
58. Display device according to claim 57, characterized in that it additionally comprises at least one additional retarder and another additional polarizer, the at least one additional retarder being disposed between the first mentioned additional polarizer and the other additional polarizer.
[59]
59. Optical viewing angle control element for application to a display device comprising a spatial light modulator and a screen polarizer arranged on one side of the spatial light modulator, the optical viewing angle control element being characterized for understanding a control polarizer and multiple retarders for the arrangement between the additional polarizer and the screen polarizer when applying the optical angle of view control element to the display device, with the multiple retarders comprising:
a switchable liquid crystal retarder comprising a layer of liquid crystal material; and at least one passive compensation retarder.

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法律状态:
2021-11-23| B350| Update of information on the portal [chapter 15.35 patent gazette]|

优先权:

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申请号 | 申请日 | 专利标题

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US201762559187P| true| 2017-09-15|2017-09-15|

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US62/559,187|2017-09-15|

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US201762565836P| true| 2017-09-29|2017-09-29|

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US62/565,836|2017-09-29|

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US201762582052P| true| 2017-11-06|2017-11-06|

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US62/582,052|2017-11-06|

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US201762592085P| true| 2017-11-29|2017-11-29|

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US62/592,085|2017-11-29|

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US201862634168P| true| 2018-02-22|2018-02-22|

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US62/634,168|2018-02-22|

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US201862641657P| true| 2018-03-12|2018-03-12|

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US62/641,657|2018-03-12|

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US201862673359P| true| 2018-05-18|2018-05-18|

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US62/673,359|2018-05-18|

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US201862699914P| true| 2018-07-18|2018-07-18|

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US62/699,914|2018-07-18|

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PCT/US2018/051021|WO2019055753A1|2017-09-15|2018-09-14|Optical stack for switchable directional display|

---