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    • 专利摘要:
    AUTOSTEREOSCOPIC SCREEN AND PORTABLE DEVICE. The invention relates to an auto-stereoscopic screen comprising a pixelated display panel comprising a single color pixel array or a sub-pixel array of different colors, and a visualization arrangement comprising a lens element array. The pixels form a hexagonal grid, and the lenses are also repeated in a hexagonal grid. A vector p is defined, which refers to a mapping between the pixel grid and the lens grid. The regions in the two-dimensional space for this vector p are identified, which provide satisfactory or unsatisfactory tonal banding performance, and the best tonal banding performance regions are selected.
    公开号:BR112017013418B1
    申请号:R112017013418-7
    申请日:2015-12-21
    公开日:2021-03-02
    发明作者:Olexandr Valentynovych Vdovin；Bart Kroon；Mark Thomas Johnson；Eibert Gerjan Van Putten
    申请人:Koninklijke Philips N.V；
    IPC主号:
    专利说明:

    FIELD OF THE INVENTION
    [001] This invention relates to a self-stereoscopic display device and a drive method for such a display device. BACKGROUND OF THE INVENTION
    [002] A well-known self-stereoscopic display device comprises a two-dimensional liquid crystal display panel that has a row and column array of screen pixels (where a "pixel" typically comprises a set of "subpixels", and a "subpixel" ”Is the smallest individually addressable single-color image element) that acts as an image-forming medium to produce a screen. An array of elongated lenses extending parallel to each other overlaps the array of screen pixels and acts as a means of forming visualization. They are known as "lenticular lenses". The outputs of the display pixels are projected through these lenticular lenses, whose function is to modify the directions of the outputs.
    [003] The pixel comprises the smallest set of subpixels that can be addressed to produce all possible colors. For the purposes of this description, a “unit cell” is also defined. The unit cell is defined as the smallest set of sub-pixels that is repeated to form the total sub-pixel pattern. The unit cell can have the same sub-pixel arrangement as a pixel. However, the unit cell can include more subpixels than one pixel. This is the case if there are pixels with orientations other than subpixels, for example. The general sub-pixel pattern is then repeated with a larger base unit (the unit cell) than a pixel.
    [004] Lenticular lenses are provided as a blade of lens elements, each comprising a partially cylindrical (e.g., semi-cylindrical) lens element. The lenticular lenses extend towards the column of the display panel, with each lenticular lens overlapping a respective group of two or more adjacent columns of screen subpixels.
    [005] Each lenticular lens can be associated with two columns of screen subpixels to enable a user to observe a single stereoscopic image. Instead, each lenticular lens can be associated with a group of three or more adjacent screen subpixels in the row direction. The corresponding columns of screen subpixels in each group are properly arranged to provide a vertical slice from a respective two-dimensional subimage. When moving the head from left to right, the user observes a series of different and successive stereoscopic images that create, for example, an impression of “immersion in an environment”.
    [006] Figure 1 is a schematic perspective view of a known self-stereoscopic direct view device 1. The known device 1 comprises a liquid crystal display panel 3, of the "active matrix" type, which acts as a spatial light modulator to produce the display.
    [007] The display panel 3 has an orthogonal array of rows and columns of screen 5 subpixels. For the sake of clarity, only a small number of screen 5 subpixels is shown in the figure. In practice, display panel 3 can comprise about a thousand rows and several thousand columns of screen 5 sub-pixels. In a black-and-white display panel, a sub-pixel is in fact a full pixel. On a color screen, a subpixel is a color component of a full color pixel. The full color pixel, according to general terminology, comprises all the sub pixels necessary to create all the colors of a smaller part of the displayed image. Thus, for example, a full color pixel may have subpixels in the colors red (R - red), green (G - green) and blue (B - blue) possibly enlarged with a white subpixel or with one or more other colored subpixels elementary. The structure of the liquid crystal display panel 3 is completely conventional. In particular, panel 3 comprises a pair of transparent glassy substrates spaced from each other, between which an aligned twisted nematic material or other liquid crystal material is provided. The substrates carry patterns of indium tin oxide electrodes (ITO - indium tin oxide) transparent on their surfaces facing each other. The polarizing layers are also presented on the external surfaces of the substrates.
    [008] Each screen subpixel 5 comprises opposite electrodes on the substrates, the liquid crystal material being interposed between them. The format and layout of screen 5 subpixels are determined by the shape and layout of the electrodes. Screen 5 subpixels are evenly spaced from each other by gaps.
    [009] Each screen subpixel 5 is associated with a switching element, such as a thin film transistor (TFT - thin film transistor) or thin film diode (TFD - thin film diode). Screen pixels are operated to produce the display by providing addressing signals to the switching elements, and suitable addressing schemes are known to those skilled in the art.
    [0010] The display panel 3 is illuminated by a light source 7 comprising, in this case, a flat backlight that extends over the area of the screen pixel matrix. The light from the light source 7 is directed through the display panel 3, with the individual screen sub-pixels 5 being activated to modulate the light and produce the display.
    [0011] The display device 1 also comprises a lenticular blade 9, arranged on the display side of the display panel 3, which performs a function of directing light and, therefore, an image-forming function. The lenticular blade 9 comprises a row of lenticular elements 11 which extend parallel to each other, of which only one is shown with exaggerated dimensions, for the sake of clarity.
    [0012] The lenticular elements 11 are in the form of convex cylindrical lenses, each of which has an elongated axis 12 that extends perpendicular to the cylindrical curvature of the element, and each element acts as a means of directing light output to provide different images, or views, from the display panel 3 in the eyes of a user positioned in front of the display device 1.
    [0013] The display device has a controller 13 that controls the backlight and the display panel.
    [0014] The self-stereoscopic display device 1 shown in Figure 1 is capable of providing several different perspective views in different directions, that is, it is capable of directing the pixel output to different spatial positions in the viewing field of the display device . In particular, each lenticular element 11 overlaps with a small group of screen subpixels 5 in each row, and in the current example, a row extends perpendicular to the elongated axis of the lenticular element 11. Lenticular element 11 projects the output of each screen subpixel 5 of a group in a different direction, in order to form the various different visualizations. As the user moves his head from left to right, his eyes will receive different views among the various views, one after the other.
    [0015] The person skilled in the art should understand that a means of polarizing light needs to be used in conjunction with the matrix described above, since the liquid crystal material is birefringent, and the change in the refractive index applies only in the light of a specific polarization. The light polarization medium can be provided as part of the display panel or the device's visualization arrangement.
    [0016] Figure 2 shows the principle of operation of a lenticular visualization arrangement, as described above, and shows the light source 7, the display panel 3 and the lenticular blade 9. The arrangement provides three images , each projected in different directions. Each subpixel of the display panel 3 is triggered with information for a specific visualization.
    [0017] In the designs above, the backlight generates a static output, and all viewing directions are performed by the lenticular arrangement, which provides a spatial multiplexing approach. A similar approach is achieved with the use of a parallax barrier.
    [0018] The lenticular arrangement only provides an auto-stereoscopic effect with a specific orientation of the screen. However, many portable devices rotate between portrait and landscape view modes. Therefore, a fixed lenticular arrangement does not allow an auto-stereoscopic visualization effect in different visualization modes. Future 3D screens, specifically for tablet computers, mobile phones and other portable devices, will thus have the possibility to observe 3D images from many directions and for different screen orientations. Modern LCD and OLED display panels with existing pixel designs are not suitable for this application. This problem has been recognized, and there are several solutions.
    [0019] A dynamic solution involves providing a switchable lens arrangement, which can be switched between different modes to activate the visualization effect in different orientations. There can be essentially two lenticular arrangements, one acting in the crossing mode and the other acting in the lens forming mode. The mode for each lenticular arrangement can be controlled by switching the lenticular arrangement itself (for example, using a matrix of switchable LC lenses) or by controlling a polarization of the light incident on the lenticular arrangement.
    [0020] A static solution involves designing a lens array that works in different orientations. A simple example can combine a rectangular grid of square subpixels on the screen with a rectangular grid of microlenses (where the directions of the lens grid are oblique or not oblique in relation to the pixel grid directions) to create multiple views in both orientations of screen. Sub-pixel formats should preferably be close to an aspect ratio of 1: 1, as this will make it possible to avoid a problem of different angular width for individual views in portrait / landscape orientations.
    [0021] An alternative grid design can be based on checkered hexagons, and this invention refers specifically to these designs. A hexagonal grid for the display panel pixels and the arrangement of formation of visualizations (lenses) can generate additional symmetry and compact packaging.
    [0022] A possible disadvantage of this approach is an effect of tonal banding, in which the black matrix areas between the subpixels are projected to the observer as a regular pattern. This can be partially solved by tilting the lens array. Specifically, in order to reduce the tonal banding effect due to the projection of a periodic black pixel matrix, a visualization arrangement needs to be chosen in relation to the pixel usage direction (rows / columns). SUMMARY OF THE INVENTION
    [0023] The invention is defined by the claims.
    [0024] According to the invention, an auto-stereoscopic screen is provided, comprising:
    [0025] a pixelated display panel comprising an array of pixels of a single color or an array of sub-pixels of different colors with respective groups of sub-pixels that together define full-color pixels; and
    [0026] a visualization arrangement that comprises an array of lens elements, positioned on the display panel, to direct the light of different pixels or subpixels to different spatial locations, thus allowing different views of a three-dimensional scene is shown in different spatial locations,
    [0027] where the pixels of the display panel form a hexagonal grid, with a maximum internal angle deviation from 120 degrees of 20 degrees or less, and the hexagonal grid is repeated with basic translation vectors a and b, and the lengths of the basic translation vectors a and b have an aspect ratio from the shortest to the longest between 0.66 and 1,
    [0028] being that the arrangement of formation of visualizations comprises a two-dimensional array of lenses that is repeated in a hexagonal grid with basic translation vectors p 'and q';
    [0029] where a vector without dimension p is defined as (pa, pb), which satisfies: P '= PaU + Pbb,
    [0030] and defining circular regions in the component space pb and pa for integer n as:

    [0031] where rn = ron-Y defines the radius of each circle, rn defines the centers of a circle, and N comprises a vector function for two coordinate vectors defined as:

    [0032] the basic translation vectors a, b, p 'and q are selected with values so that p falls into the vector space that excludes the sets E1, E3 or E4 with r0 = 0.1 and Y = 0, 75.
    [0033] In words, the main equation above is read as follows:
    [0034] (Line 1) Ené equal to the set of values of p so that the function N applied to the difference vector of a vector v to the foot vector smaller than rn2 for all values of vector v in the set rn. The N function is subsequently defined. This defines the circles centered on the set of rn values.
    [0035] (Line 2) rn is the set of vector values i + j / n with i and j as vectors in the two-dimensional vector space of integer values (that is, positive and negative integers and zero) and for which the function N applied to vector j generates response n.
    [0036] The vector p defines the spatial relationship between the pixel grid (or subpixel) and the lens grid. Therefore, this defines a mapping between the pixels (or subpixels) and the lens. In particular, the components of the vector put the terms of the matrix transformation of the pixel grid vector space (defined by a and b) and the lens grid vector space (defined in at least by p '). The components of the p vector define, in turn, how different pixels (or subpixels) contribute to different lens phases and how the black mask area is imaged by the lens grid. Therefore, the vector p can be considered a more fundamental way to define the relationship between the lens and the pixels.
    [0037] The term "basic translation vector" means a vector translation from a point within a pixel or lens area to a corresponding point in an adjacent pixel or lens area. The lens and pixel areas are two-dimensional, so there are two translation vectors, one for each grid direction. For a regular hexagonal grid, the basic translation vectors are in the row and column directions at 120 degrees from each other. For an oblique grid, the basic translation vectors can deviate from this 120 degree angle, but follow the grid's row and column directions. Therefore, the hexagonal grid of the lenses and / or pixels can be regular hexagonal, or they can have a non-regular hexagonal shape, for example, an oblique version of a regular hexagonal grid.
    [0038] Circular regions define sets of possible values for the components of the vector p and thus define regions of related characteristics.
    [0039] Excluding the regions close to the centers of E1, E3 and E4, the problems of tonal band formation are avoided. In particular, routine panel designs, for example, with an array of sub-pixel integers under each lens, as well as fractional designs, correspond to p values that fall in the center of the E1, E3 or E4 regions.
    [0040] In this way, the invention provides design parameters for display panel layouts that solve the problems of tonal band formation mentioned above and enable 3D multi-visualized auto-stereoscopic screens with satisfactory performance.
    [0041] The basic translation vectors a, b, p 'and q' can have values so that p is not in the set Eicom ro = 0.25 and Y = 0.75-
    [0042] The basic translation vectors a, b, p 'and q' can have values so that p is not in the E3 set with ro = 0.25 and Y = 0.75-
    [0043] The basic translation vectors a, b, p 'and q' can have values so that p is not in the set E4 with ro = 0.25 and Y = 0.75-
    [0044] These different regions represent progressively better tonal banding performance, so that by progressively excluding more areas in the design space for the p vector, the remaining design options generate progressively better tonal banding performance.
    [0045] The basic translation vectors a, b, p 'and q' can have values so that p is not in the set or sets as defined above with r0 = 0.35.
    [0046] There are also preferential regions in the vector space for the p vector. In one example, the basic translation vectors a, b, p ’and q’ have values so that p is in the set E7 with ro = 0.35 and Y = 0.75-
    [0047] In another example, the basic translation vectors a, b, p 'and q' have values so that p is in the set E9 with ro = 0.35 and Y = 0.75-
    [0048] The display device can be used on a portable device, where the portable device is configurable to operate in a portrait view and a landscape view. It can be a mobile phone or tablet computer. BRIEF DESCRIPTION OF THE FIGURES
    [0049] The modalities of the invention will now be described, by way of example only, with reference to the attached drawings, in which:
    [0050] Figure 1 is a schematic perspective view of a known auto-stereoscopic display device;
    [0051] Figure 2 is a schematic cross-sectional view of the display device shown in Figure 1;
    [0052] Figures 3a to 3e show several possible pixel grids based on square or almost square pixel or lens grids;
    [0053] Figure 4 shows a lens grid superimposed on a square pixel matrix, with a step vector p defining the relationship between them, for the purposes of explaining the analysis used;
    [0054] Figure 5 is a graphical explanation for parameters used to characterize the pixel matrix and the lens grid;
    [0055] Figure 6 shows a graph with the use of moiré equations and a visibility function to estimate the amount of visible tonal bands for a given step vector p;
    [0056] Figure 7 shows a first possible characterization of the regions of the graph of Figure 6;
    [0057] Figure 8 shows a second possible characterization of the regions of the graph in Figure 6;
    [0058] Figures 9a to 9d show simulations of ray trace rendering of the 3D pixel structure for the 2D pixel layout of Figure 3 (c) for different lens designs;
    [0059] Figures 10a to 10d are a graph of luminosity (L *) as a function of the lens phases in two dimensions, for the same examples as in Figures 9a to 9d;
    [0060] Figures 11a to 11d show a graph of the color deviation for the same examples as in Figures 9a to 9d;
    [0061] Figures 12a to 12d show several possible pixel grids based on the hexagonal pixel and the lens grids;
    [0062] Figure 13 shows a pixel grid based on hexagonal subpixels, but which, in reality, form a rectangular grid;
    [0063] Figure 14 shows a hexagonal lens grid superimposed on a hexagonal pixel matrix, with a step vector p defining the relationship between them;
    [0064] Figure 15 is a first graphic explanation for parameters used to characterize the pixel matrix and the lens grid;
    [0065] Figure 16 is a second graphic explanation for parameters used to characterize the pixel matrix and the lens grid that corresponds to the representation in Figure 5;
    [0066] Figure 17 shows a graph with the use of moiré equations and a visibility function to estimate the amount of visible tonal bands for a given step vector p.
    [0067] Figure 18 shows a first possible characterization of the regions of the graph in Figure 17; and
    [0068] Figure 19 shows a second possible characterization of the regions of the graph in Figure 17.
    [0069] Note that Figures 3a to 3e and 4 are intended to show square lens and pixel grids, Figures 12a to 14 are intended to show regular hexagonal lens and pixel grids, and Figures 5 to 8 and 15 to 19 are meant to show circular regions. Any distortions of square, regular hexagonal and circular representations are the result of inaccurate image reproduction. DETAILED DESCRIPTION OF THE MODALITIES
    [0070] The present invention provides an auto-stereoscopic screen comprising a pixelated display panel comprising a single color pixel array or a sub-pixel array of different colors and a visualization array comprising an array of lens elements. The pixels form a hexagonal grid, and the lenses are also repeated in a hexagonal grid. A defined foot vector, which refers to a mapping between the pixel grid and the lens grid. The regions in the two-dimensional space for this vector are identified, which provide satisfactory or unsatisfactory tonal banding performance, and the best tonal banding performance regions are selected.
    [0071] The invention is based on an analysis of the effect of the relationship between the pixel grid and the lens grid on the tonal banding performance. The analysis of tonal banding can be applied to different pixel and lens designs. Note that the term “pixel grid” is used to indicate the pixel grid (if each pixel has only one addressable element) or the sub-pixel grid (if each pixel has multiple independently usable sub-pixels).
    [0072] To illustrate the analytical approach, a first example will be presented based on square (or almost square) pixel grids and lens grids. This invention relates specifically to hexagonal lens and pixel grids, for which an analysis is provided as a second example.
    [0073] For the first example of a pixel grid and a square lens grid, the display panel designs are discussed with pixels in a regular square 4-fold symmetrical grid, in addition to a light modulator that also has elements in a regular 4-fold symmetrical grid. For the purpose of explanation, some definitions are needed. In particular, a panel coordinate system (that is, of the pixel grid) needs to be defined, and a coordinate system of the visualization layout needs to be defined in terms of geometric (physical) coordinates and logical coordinates that are related to the panel coordinate system.
    [0074] Figure 3 shows several possible pixel grids. Each example shows the smallest unit cell 30 (i.e., the smallest set of subpixels 31 that is repeated to form the subpixel pattern, as defined above) and a pixel 32 using the definition employed in that description. A 32 pixel is the smallest square arrangement of all primary colors so that the pixel size and shape are the same in the two orthogonal orientations.
    [0075] Subpixels are shown as squares. However, the actual sub-pixel format may be different. For example, the actual pixel aperture will typically be irregularly shaped as it may, for example, depend on the size and position of the pixel circuit elements, such as the switching transistor in the case of a display panel. active matrix. It is the shape of the pixel grid that is important rather than the precise shape of the individual pixels or subpixels. The same reasoning applies to the hexagonal pixel grid discussed further below.
    [0076] The pixel pitch vectors x and y are also shown. There are translation vectors between the adjacent pixel centers in the row direction and in the column direction, respectively. The letters in the smallest unit cell 30 indicate the primary colors: R = red, G = green, B = blue, W = white.
    [0077] Figure 3 (a) shows an RGGB unit cell and an RGGB pixel, Figure 3 (b) shows an RGBGBGRG unit cell and an RGBG pixel, Figure 3 (c) shows an RGBW unit cell and an RGBW pixel, Figure 3 (d) shows an RGBWBWRG unit cell and an RGBW pixel, and Figure 3 (d) shows a W unit cell and a W pixel.
    [0078] A pixel grid is defined based on the two vectors x and y, later called pixel pitch vectors. The vectors form a lattice matrix X = [x y] with units of length (for example, meters). There are multiple possible definitions of a pixel including the smallest unit cell; however, for this description, the pixel is approximately square. Therefore, X should be chosen to form an approximately square region of subpixels. As shown in Figures 3 (a) to 3 (d), for color screens, the pixel definition results more simply in a region with 2x2 subpixels. When the unit cell is larger, as in Figures 3 (b) and 3 (d), the pixel group appears rotated or mirrored to form the larger unit cell, but also in these cases, X remains a 2x2 region. For monochrome screens, the pixel is the region of a single sub-pixel.
    [0079] Pixels don't have to be perfectly square. They can be approximately square, which means that rotation at any angle, limited shear or limited elongation are covered in scope. The aspect ratio is defined as:

    [0080] and the grid angle is:

    [0081] The shear is then expressed as | θ - 90 ° |. Therefore, for an approximately square grid, it means that «1 e | θ- 90 ° | «0 °.
    [0082] For example, a is preferably between 0.9 and 1.1, and θ is between 80 and 100 degrees (obviously, if one pair of corner angles is at 80 degrees, then the other pair will be in 100 degrees).
    [0083] To define the lens grid, the lens pitch vectors can be defined.
    [0084] Figure 4 shows a lens grid 42 superimposed on a square pixel matrix 40 with subpixels of 2x2 31 per pixel 32 (as in Figures 3 (a) and 3 (c)). One pixel among each pixel group of four subpixels 31 is highlighted (ie, shown white). The x and y vectors are the pixel pitch vectors of that grid, as explained above. The lens grid 42 comprises a microlens array with spherical lenses 44 arranged in a square grid. The vectors p ’and q’ are the step vectors of that grid. They are formed by a linear combination of the pixel pitch vectors.
    [0085] Instead of physical lens step vectors in units of meters, logical and dimensionless lens step vectors can be defined as: P = (Px.Py) and <7 = (“Py.Px)
    [0086] for the chosen px and py.
    [0087] The geometric (physical) p 'eq' step vectors (for example, in meters) are defined in terms of the logical lens step vectors as: p '= xp = pxx + pyy, qf = Xq = -pyx + pxy.
    [0088] Deformations in the pixel grid should be reflected in equal deformations of the lens grid. Note that (p, q) = 0, but not necessarily (p ', q ’) = 0 since it is not required (x, y) = 0. Similarly, | p | = | q |, but not necessarily | p '| = | q ’|.
    [0089] For the purposes of this description, regions are defined as Pn, m for integer values n and m. These regions consist of multiple circles, the same being organized in a grid of circles.
    [0090] This region is defined by:

    [0091] The term p-vespecifies the length of the vector from v to p and thus the inequality defines a set of centralized circles with a center defined by v. v being, in itself, a set of vectors defined by the set of terms L. This has an isolated number of members as a result of the conditions placed on the integer values that make up the two-dimensional vectors i and j.
    [0092] Here, r n, m = ron-Y is the radius of each circle. This radius thus decreases with the increasing n. Ln, m is the set of centers, and (i, i) denotes the internal product, so that when i = [i j)] T, then (i, i) = i2 + j2. An abbreviation Pn = Pn, right used in this description. Note that there are integers k for which there are no possible combinations of integers i and j, for which (j, j) = k is true. As a consequence, the sets P3, P6 and P7 are empty.
    [0093] As an example, the set P5 can be explored starting with L5,5.
    [0094] With i G Z2, all i = [ij] T is indicated where i and i are whole numbers (negative, zero or positive). The set of solutions for j G Z2 A (j, j) = 5 is:

    [0095] There is a graphic explanation of j and j / n as Gaussian integers and their reciprocal lattice shown in Figure 5.
    [0096] Each point in Figure 5 (a) is marked with the coordinate of the Gaussian integer g = a + ib, where i2 = -1 and the norm N (g) = a2 + b2. Figure 5 (b) consists of the same points, but the coordinates of the points are divided by their norm, thus corresponding to j / n instead of j.
    [0097] Any combination
    of the set of solutions for j shown above is at L5.5. Two examples are
    The P 5 region then consists of circular regions with those centers and a radius r 5 = r 05-Y. Note that there are eight circles P5 around each circle P1 due to the fact that there are eight solutions for j G Z2 A <j, j> = 5.
    [0098] In order to minimize the problems of tonal band formation for rotating screens with pixels in a roughly square grid, a screen design is presented, in which an array of view formation arrangements (typically, a microlens array) forms a square grid that can be described by the direction p in terms of pixel coordinates in which foot chosen outside the Pn regions that originate the formation of tonal bands.
    [0099] To analyze the problems of tonal range formation, two models were used. The first model is based on an analysis of spatial frequencies in both the pixel structure and the lens structure, and the second model is based on ray tracing.
    [00100] The first model uses moiré equations and a visibility function to estimate the amount of visible tonal bands for a given step vector p.
    [00101] This model results in a map like Figure 6, in which the lighter areas indicate more tonal band formation (on a logarithmic scale). Figure 6 graphically represents py versus px. It must be understood that the current map depends on parameters such as the visual angle of the microlenses and the pixel structure. The map in Figure 6 is generated for the case of a pixel with a single emission area with an aperture of 1/8 of the total pixel surface, a point spread function (PSF) of a Gaussian lens that scale with the lens aperture, and a constant visual angle of 97 μrad (20 arcsec).
    [00102] As a consequence of the PSF scale change, more tonal banding components are visible for | p | smaller (in the upper left part of Figure 6) due to the more precise focus. It has been observed that the intensity of several tonal band “bubbles” depends on the actual pixel structure (see Figure 3), but the position of the bubbles is always the same.
    [00103] The analysis being partly in the recognition that most of the structure in this tonal band formation map can be explained with the use of the Pn areas, in which Pn with a higher n corresponds to smaller areas. Most areas with significant tonal bands are explained by P1 ... P 8.
    [00104] Adapting a radius r 0 = 0.35 and y = 0.75 to this map, the result is the image shown in Figure 7. In other situations, there may be less tonal band formation, and as a consequence, r0 = 0.25 is sufficiently accurate. Figure 8 shows the results of adapting a radius r0 = 0.25 to the map in Figure 5.
    [00105] In Figures 7 and 8, the preferred regions are also represented graphically for the examples of square grid, namely, P9,18 and P14,26. These regions are best described by r0 = 0.35.
    [00106] The approach of this invention is based on avoiding the zones that originate the formation of tonal bands, namely, avoiding certain ranges of values of the vector p = (px, py).
    [00107] The first zones to avoid are the P1 regions (ie, P1.1) that originate the largest tonal band formations. In Figure 8, with smaller radius values, the excluded zone is smaller. Therefore, a first zone to be excluded is based on r0 = 0.25.
    [00108] The zones to be excluded when designing the relationship between the pixel grid and the lens grid for this square example are: 1. p £ Pi, with radius r0 = 0.25 and Y = 0.75.2. As directly above and also p g P2,3. As directly above and also p g P4,4. As directly above and also p g P5.5. As directly above and also p g P8.6 Any of the above, but with a radius of 0 = 0.35.
    [00109] Within the space that is left excluding regions, there are some regions that are of particular interest due to the fact that the formation of tonal ranges is specifically low for a wide range of parameters. These regions are: 1. p E P9.18 with radius r0 = 0.35.2. p E P 14.26 with radius ro = 0.35.
    [00110] Preferably, for the square grid example, the subpixels are in a perfectly square grid, but small variations are possible. The aspect ratio is preferably limited
    , or more preferably,
    The grid shear from a square / rectangle to a diamond / parallelogram is preferably up to | θ - 90 ° | <20 °, or even up to | θ - 90 ° | <5 °.
    [00111] An alternative to moiré equations to illustrate the approach is to trace rays from a model of a screen with a lens that displays a completely white image.
    [00112] Figure 9 shows this rendering for the 2D pixel layout like the one in Figure 3 (c). Any rendering of a tonal stripe-free design would appear to be medium white, whereas for a tonal stripe design, the intensity and / or color depends on the position of the observer (ie, the lens phase).
    [00113] Figure 9 (a) shows renderings for a lens design in a P1 region for a lens phase. Although not shown in the presentation in Figure 9 (a), white and most of the primary blue are missing. Figure 9 (b) shows renderings for a lens design in a P2 region for a lens phase in which more than an average amount of black matrix is visible. Figure 9 (c) shows renderings for a lens design in a P4 region for a lens phase in which almost no black matrix is visible. Figure 9 (d) shows renderings for a lens design in a P14.26 center with (virtually) equal distribution of primers within this correction for this and all other phases.
    [00114] A correction as shown in Figure 9 can be rendered for several lens phases, since different lens phases (this means that the lens position that is responsible for generating the view for a specific view location) gives rise to different distributions of subpixels. It is more effective to calculate the CIE 1931 XYZ color value for each correction. From this average, the color value of CIE L * a * b * can be calculated, which generates quantitative means of comparing the effects of the formation of tonal bands of perception.
    [00115] In this perception color space, the L2 distance between two color values (denoted as ΔE below) is indicative of the perceived difference between those colors.
    [00116] The target is white, corresponding to (L *, a *, b *) = (100, 0, 0).
    [00117] In Figure 10, the brightness (L *) is plotted as a function of the lens phases in two dimensions, corresponding to different views projected by the lens for different observer positions, for the same examples as in Figure 9. The variable dimensionless lens phase has values in the range of (0.1). Due to the periodicity of the pixel grid and the lens grid, the lens phases 0 and 1 correspond to the same generated views. Due to the fact that the screen uses a 2D microlens matrix, the lens phase itself is also 2D.
    [00118] In Figure 11, the color error (ΔE) is represented again for the same examples.
    [00119] Depending on the situation, ΔE «1 is only visible. The free example of tonal banding in Figures 10 (d) and 11 (d) appears as uniform L * = 100 and ΔE = 0, respectively, while the other examples clearly have tonal banding as the color varies. with the observer's position (ie lens phase).
    [00120] Due to the fact that the screen uses a 2D microlens matrix, the lens phase itself is also 2D.
    [00121] The graphs can be summarized by obtaining the mean square root (RMS) value of ΔE over the entire phase space.
    [00122] In the table below, this was done for a list of points that correspond to regions that, according to the tonal range formation model explained above, should be excluded or included.


    [00123] From this table, it is clear that the two models are quite consistent in terms of forecasting the formation of tonal bands. The positive areas have low ΔERMS values, and the largest negative areas (with lower ordinals) have the highest ΔERMS values.
    [00124] The first model above provides an overview of the tonal banding effect, while the second model provides more details and visualization.
    [00125] An analogous analysis will now be presented for the example of a hexagonal pixel grid.
    [00126] This invention refers specifically to panels with pixels (or subpixels) in a hexagonal grid (which is, preferably, a regular hexagonal grid, although it can deviate from a regular grid), there is a formation arrangement on it of views that also have elements in a hexagonal grid.
    [00127] As in the example above, the panel coordinate system is defined, so the coordinate system of the visualization layout is defined in terms of geometric (physical) coordinates and logical coordinates that are related to the panel coordinate system . The parametric regions in the parameter space are defined again, which can be selected to achieve the desired performance, for example, in relation to the formation of tonal bands.
    [00128] The pixel pitch vectors are defined again, and for this example, the vectors a and b are defined, analogous to the vectors x and y in the example above.
    [00129] The vectors a and b, are the pixel step vectors that form a lattice matrix X = [a b] with units of length (for example, meters). There are multiple possible definitions of a pixel that include the smallest unit cell; however, for this invention, the pixel grid is hexagonal, for example, hexagonal at least approximately regular. Therefore, X should be chosen to form a hexagonal region of subpixels.
    [00130] The examples are shown in Figure 12.
    [00131] For color screens, the pixel area 32 is probably a triangular region with 3 or maybe 4 subpixels 31. Sometimes this group appears rotated or mirrored to form a possibly larger unit cell, but also in this In this case, X is a region with 3 or 4 subpixels 31. For monochrome screens, the unit cell 30 is the region of a single pixel 32. The grid of pixels 32 is more important than the format or grid of subpixels 31.
    [00132] Figure 12 (a) shows a hexagonal grid in which each pixel 32 is formed as a triangle of three RGB 31 sub-pixels. The unit cell 30 is the same.
    [00133] Figure 12 (b) shows a hexagonal grid in which each pixel 32 is formed as the group of four subpixels 31 RGBW, forming a shape that is essentially a rhombus (but without straight sides). Unit cell 30 is the same.
    [00134] Figure 12 (c) shows a hexagonal grid in which each pixel 32 is formed from seven subpixels 31 (one in the center and six around the outside). However, external subpixels are shared with adjacent pixels, so that on average there are 4 subpixels (RGBW) per pixel. Unit cell 30 (the smallest element that can be translated to form the overall overall sub-pixel pattern) is larger, due to the fact that there are two types of pixels.
    [00135] Figure 12 (d) shows a hexagonal grid of pixels of a single color. Unit cell 30 is a single pixel 32.
    [00136] The layout of Figure 13 is a counterexample due to the fact that although the subpixels are hexagons and are arranged in a hexagonal grid, the pixel grid is, in fact, rectangular. The pixel grid is defined by vectors that translate from one pixel to the same location within the adjacent pixels.
    [00137] As in the example above, the invention does not require perfectly hexagonal grids, and the angular orientation is also not relevant. Rotation around any angle, limited shear or limited elongation are also possible.
    [00138] The aspect ratio for the hexagonal pixel grid is defined as

    [00139] and the grid angle is:

    [00140] An interior angle of 120 corresponds to a regular hexagonal grid. A shear amount can therefore be expressed as | θ - 120 ° |. Therefore, for an approximately regular hexagonal grid, it is true that β ~ 1 and | θ - 120 ° | ~ 0 °.
    [00141] As in the example above, the lens pitch vectors are also defined. The definition of the physical and dimensionless lens step vectors is p = (pa, pb) for chosen pa and pb.
    [00142] The vectors relevant to the hexagonal case are shown in Figure 14, which, like Figure 4, shows lens grid 42 over pixel matrix 40. This is based on the three sub-pixel of Figure 12 (a). The lens grid is formed by the real p ’and q’ vectors.
    [00143] The vectors p 'and q have the same length, and the angle between p' and q 'is 120 °. The geometric (physical) pitch vectors p 'eq' (for example, in meters) are defined in terms of the logical lens pitch vectors, where deformations (for example, rotation, shear, scale change) in the grid pixels should be reflected in equal deformations of the lens grid. This can be understood by considering a flexible auto-stereoscopic screen being extended.
    [00144] The step vector p without dimension again defines a mapping between the pixel grid and the lens grid, and in this case, it is defined by: P '= Pα «+ Pbb,
    [00145] For this example, the regions are defined for integers n that consist of multiple circles, themselves organized in a grid of circles. These regions are defined by:

    [00146] Again, rn = r 0 n -Y is the radius of each circle, r is the set of centers, and N (j) is the norm similar to Eisenstein's integer norm defined as:

    [00147] This defines a hexagonal grid of centers. As in the example above, the term p-v specifies the vector from v to p and therefore the inequality, which is essentially based on the norm of space (distance to the square); this, which defines a set of circles with a center defined by v. v, is itself a set of vectors defined by the set of terms r n. It has an isolated number of members as a result of the conditions placed on the integer values that make up the two-dimensional vectors i and j.
    [00148] As an example, exploring E4 is considered, starting with r4. The set of solutions for j E Z2 AN (j) = 4 is:

    [00149] Any combination of
    is in Γ4Two examples are
    The E4 region then consists of circular regions with those centers and the radius r4 = ro4-Y. There is a graphical explanation of jej / n as Eisenstein integers (which form a hexagonal lattice in the complex plane) and its reciprocal lattice, respectively, as shown in Figure 15.
    [00150] Each point in the left sub-figure is marked with the coordinate of Eisenstein's integer c = a + ab, and the norm N ([a b)] T). The right sub-figure consists of the same points, but divided by its norm, therefore, corresponding to j / n instead of j.
    [00151] Again, there are integers k for which there are no j, for which N (j) = k is true. As a consequence, the sets E2, E5 and E6 are empty.
    [00152] In the example used above based on square grids, a Cartesian standard is used, namely, {j, j) = jTj, and, in a graphical explanation, Gaussian integers are used, which form a square grid in the complex plane, rather than Eisenstein's whole numbers. Figure 16 shows this approach for comparison with Figure 5.
    [00153] The approach explained above is used to analyze the effect of forming tonal bands of different designs. The resulting map, again based on moiré equations and a visibility function to estimate the amount of visible tonal bands for a given vector of step p, is shown in Figure 17. This is a graph of pb versus pa, and again , the lighter areas indicate more tonal ranges.
    [00154] It must be understood that the current map depends on parameters such as the visual angle of the microlenses and the pixel structure. The map in Figure 17 is generated for the case of a pixel with a single emission area with an aperture of 1/6 of the total pixel surface, a point spread function (PSF) of a Gaussian lens that scale with the lens aperture, and a constant visual angle of 97 μrad (20 arcsec). As a consequence of the PSF scale change, more tonal banding components are visible for | p | smaller due to the more precise focus.
    [00155] Most of the structure in this tonal band formation map can be explained with the use of the En areas, where En with upper n corresponds to smaller areas. Most areas with significant tonal range formation are explained by E1 ... E4.
    [00156] As in the examples above, r 0 = 0.35 and y = 0.75 are used to generate the image in Figure 18. In other situations, there may be less tonal band formation, and as a consequence, r0 = 0.25 it is accurate enough. Figure 19 shows the results of adapting a radius r0 = 0.25 to the map in Figure 17.
    [00157] Note that in Figures 18 and 19, the regions are labeled Px for simple comparison with Figures 7 and 8. These regions are, however, the Ex regions, as defined by the equations above.
    [00158] In Figures 18 and 19, the preferred regions are represented, namely, E7 and E9 (shown as P7 and P9). These regions are best described by r0 = 0.35.
    [00159] The invention is based on avoiding the zones that originate the formation of tonal bands, namely, the value of the vector p = (pa, pb).
    [00160] The first areas to avoid are the E1 regions that originate the largest tonal band formations. In Figure 19, with smaller radius values, the excluded zone is smaller. Therefore, a first zone to be excluded is based on r0 = 0.25.
    [00161] The zones to be excluded when projecting the relationship between the pixel grid and the lens grid are: 1. p i Ei with radius r0 = 0.25 and y = 0.75.2. As directly above and also p i E3,3. As directly above and also p i E4,4. Any of the above, but with a radius of 0 = 0.35.
    [00162] Within the space that is left excluding regions, there are some regions that are of particular interest due to the fact that the formation of tonal ranges is specifically low for a wide range of parameters. These regions are: 1. p E E7 with radius r0 = 0.35.2. p E E9 with radius r0 = 0.35.
    [00163] Preferably, the subpixels are in regular hexagonal weight, but small variations are included in the scope of the invention: The aspect ratio is, 2preference, limited
    or more preferably, the
    . The shear of the grid in the opposite direction to that of a regular hexagon is preferably limited to | θ - 120 ° | <20 °, or even at | θ- 120 ° | <5 °.
    [00164] The invention is applicable to the field of auto-stereoscopic 3D screens, more specifically, to auto-stereoscopic screens of rotating full parallax multiviews.
    [00165] The invention relates to the relationship between the pixel grid and the lens grid. It can be applied to any screen technology.
    [00166] Other variations to the disclosed modalities can be understood and realized by those skilled in the art in the practice of the claimed invention, from a study of the drawings, the disclosure and the attached claims. In the claims, the expression “that comprises” does not exclude other elements or other stages, and the indefinite article “one” or “one” does not exclude a plurality. The mere fact that certain measures are mentioned in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. No reference sign in the claims should be construed as limiting the scope of the invention.
    权利要求:
    Claims (11)
    [0001]
    1. AUTOESTEREOSCOPIC SCREEN, characterized by comprising: a pixelated display panel (3) comprising a matrix of pixels of a single color or a matrix of subpixels of different colors with respective groups of subpixels that together define full color pixels; a view-forming arrangement (42) comprising an array of lens elements (44), positioned on the display panel, to direct light from different pixels or subpixels to different spatial locations, thus enabling different views of a three-dimensional scene are displayed in different spatial locations, with the pixels of the display panel forming a hexagonal grid, with a maximum internal angle deviation from 120 degrees of 20 degrees or less, and in which the hexagonal grid is repeated with basic translation vectors a and b, and the lengths of the basic translation vectors a and b have an aspect ratio from the shortest to the longest between 0.66 and 1; in which the visualization arrangement comprises a two-dimensional array of lenses (44 ) that is repeated in a hexagonal grid with basic translation vectors p 'and q'; in which a vector without dimension p is defined as (pa, pb), which satisfies: P '= Paa + Pbb, and is defined and circular regions in the component space pb and pa for integer n as:
    [0002]
    2. SCREEN according to claim 1, characterized by the basic translation vectors a, b, p 'and q' having values such that p falls into the vector space that excludes the set Ei with ro = 0.25 and Y = 0.75.
    [0003]
    3. SCREEN according to claim 1 or 2, characterized by the basic translation vectors a, b, p 'and q' having values such that p falls in the vector space that excludes the set E3 with ro = 0, 25 and y = 0.75.
    [0004]
    4. SCREEN according to any one of claims 1 to 3, characterized by the basic translation vectors a, b, p 'and q' having values such that p falls into the vector space that excludes the set E4 with ro = 0.25 and y = 0.75.
    [0005]
    5. SCREEN according to any one of claims 1 to 4, characterized by the basic translation vectors a, b, p 'and q' having values such that p is not in the set or sets defined with ro = 0.35 .
    [0006]
    6. SCREEN according to any one of claims 1 to 7, characterized by the basic translation vectors a, b, p 'and q' having such modulus values p is in the set E7 with r0 = 0.35 and Y = 0.75 .
    [0007]
    7. SCREEN according to any one of claims 1 to 6, characterized in that the basic translation vectors a, b, p 'and q' have such modulus values p is in the set E9 with r0 = 0.35 and Y = 0.75 .
    [0008]
    SCREEN according to any one of claims 1 to 7, characterized in that the basic hexagonal pixel grid translation vectors a and b have an aspect ratio of the shortest to the longest vector lengths between 0.83 and 1.
    [0009]
    SCREEN according to any one of claims 1 to 8, characterized in that the hexagonal pixel grid has a maximum internal angle deviation from 120 degrees of 5 degrees or less.
    [0010]
    10. PORTABLE DEVICE, characterized by comprising a screen, as defined in any one of claims 1 to 9, the portable device being configurable to operate in a portrait view and a landscape view.
    [0011]
    11. PORTABLE DEVICE, according to claim 10, characterized by comprising a mobile phone or tablet type computer.
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    法律状态:
    2020-05-05| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2020-12-08| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-03-02| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 21/12/2015, OBSERVADAS AS CONDICOES LEGAIS. |
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    EP14200331.8|2014-12-24|
    PCT/EP2015/080839|WO2016102495A1|2014-12-24|2015-12-21|Autostereoscopic display device|
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