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    • 专利摘要:
    Display device (100) comprising: - a support; first and second conductive power supply elements (106, 108), the first conductive element being placed on the support; a plurality of LED modules (104) each comprising at least one LED and two power supply pads respectively disposed on two opposite faces of the LED module, one of which corresponds to an emitting face of the LED, in which the power supply pads each of the LED modules are respectively connected to the first and second conductive power supply elements, and wherein, the connection surface of a power supply pad of an LED module with the first conductive power supply element is significantly lower than a receiving surface of the first conductive element corresponding to the surface of the first conductive element in a plane parallel to the connection surfaces of the power supply pads of the LED modules.
    公开号:FR3068819A1
    申请号:FR1756310
    申请日:2017-07-04
    公开日:2019-01-11
    发明作者:Ivan-Christophe Robin；Bertrand Dupont；Stephane Caplet；Emeric De Foucauld；Umberto Rossini；Alexei Tchelnokov；Francois Templier
    申请人:Commissariat a lEnergie Atomique CEA；Commissariat a lEnergie Atomique et aux Energies Alternatives CEA；
    IPC主号:
    专利说明:

    LED DISPLAY DEVICE
    DESCRIPTION
    TECHNICAL AREA AND PRIOR ART
    The field of the invention relates to image display or projection devices. It relates in particular to the production of a screen comprising LEDs or micro-LEDs (pLEDs) advantageously produced with GaN.
    The vast majority of current screens are made with liquid crystal coupled to a backlight and are called LCD screen (for "Liquid Crystal Display", or liquid crystal screen). A liquid crystal matrix of such a screen is controlled by TFTs (for "Thin Film Transistor", or thin film transistor).
    Another more efficient screen technology is OLEDs, or organic light emitting diodes. The pixel control principle is similar to that used in the case of an LCD screen (control circuit made in TFT technology).
    It is also possible to use micro-LEDs (or pLEDs) comprising for example a structure based on GaN / InGaN. These pLEDs allow a reduced consumption (efficiency of GaN / InGaN pLEDs greater than 60%) compared to LCD and OLED screens. These pLEDs are compatible with high current densities, which makes it possible to have high luminances, typically of 10 6 cd / m 2 .
    Document FR 3 044 467 describes a process for manufacturing a screen by assembling microchips made up of pLEDs and their control electronics. With this process, the control electronics can be produced in bulk technology and not in TFT technology. However, this method has the disadvantage of having to carry out a very precise transfer of the microchips, which each have four connections, on an interconnection network, which is complicated to achieve given the precision required. The time required to carry out this transfer is also very important because of the number of pLEDs which have to be transferred.
    STATEMENT OF THE INVENTION
    An object of the present invention is to provide a display device whose architecture allows relaxation of the constraints relating to the postponement and positioning of the LEDs relative to the interconnections to which the LEDs are connected.
    For this, the present invention provides a display device comprising at least:
    - a support;
    - first and second conductive elements of electrical supply, said at least one first conductive element being placed on one face of said support;
    several LED modules each comprising at least one LED, each LED comprising at least two layers forming a pn junction, and each LED module comprising two electrical supply pads respectively disposed on two opposite faces of the LED module, one of which corresponds to a emissive face of the LED of said LED module, in which the electrical supply pads of each LED module are connected respectively to the first and second conductive elements of electrical supply, for the electrical supply of the LED module, and in which the connection area of an electrical supply pad of an LED module with the first conductive power supply element is significantly smaller than a reception area of the first conductive element corresponding to the surface of the first conductive element in a plane parallel to the connection surfaces of the supply pads of the LED modules and suitable for producing an electrical contact ectrique with an electrical supply pad of an LED module.
    In such a device, given the large dimensions of the reception surface relative to those of the supply pads, it is not necessary to achieve precise positioning of the LED modules on the reception surface of the first conductive element . Different ways of transferring the LED modules to this reception surface is therefore possible, such as for example making a random arrangement of the LED modules on the reception surface. It is not necessary to align the pixel modules with respect to the conductive elements to which the LED modules are electrically connected.
    The LED modules can be positioned or transferred onto the reception surface of the first conductive element in a non-deterministic manner. Non-deterministic positioning or postponement here signifies substantially random. A non - deterministic transfer, can thus lead to a variable, and therefore not uniform, density of the LED modules on a support. In addition, the density of LED modules at a given location can often not be predetermined in advance and will for example be dictated by a statistical probability law of the Poisson law type.
    The LED modules can be positioned or transferred onto the reception surface of the first conductive element in an unconstrained or unconstrained manner. Unconstrained, or unconstrained positioning or transfer means that the supply conductive pads of the LED modules have contact surfaces of dimensions smaller than those of the conductive reception surfaces of the support on which the LED modules are transferred, for example with a ratio at least equal to 5, so that the positioning accuracy of the LED modules by the positioning process can have a relaxed precision, or even very relaxed, the LED module can be positioned at different locations on the surface of reception, without the need to center the studs of the LED module on the conductive reception surfaces. In this case, the density of LED modules could be substantially uniform for the different conductive receiving surfaces, but the positioning of the LEDs on a receiving surface could fluctuate and we could thus speak of pseudo-random positioning on the conductive surfaces d 'Home.
    Furthermore, the orientation of the modules during their transfer may be random or not, depending on whether or not a technique of pre-orientation of the LED modules is used before or during the transfer operation on the support.
    The term LED is used to denote an LED or a pLED.
    A relationship between the dimensions of the reception surface of the first conductive element and those of the connection surface of an electrical supply pad of an LED module, in the plane formed at the interface of the reception surface and the connection surface, can be greater than or equal to 5.
    The receiving surface of the first conductive element corresponds to the entire surface of conductive material of the first conductive element which can be used to make electrical contact with the electrical supply pads of the LED modules. A conductive material which could not be used to form the electrical connection with the LED modules is not part of this reception surface.
    The LED modules can be distributed randomly or almost randomly over the reception surface of the first conductive element, the device being able to result from the implementation of the method described below.
    The LED modules can be distributed randomly, so that the density of LED modules on the receiving surface is not uniform.
    The ratio of dimensions between the reception surface of the first conductive element and the connection surface of a supply pad of one of the LED modules is greater than or equal to 5.
    Each LED module can also comprise a control circuit for the LED of said LED module, the control circuit being capable of delivering, on one of the layers of the pn junction of the LED, a signal representative of the light signal intended to be emitted by the LED.
    The control circuits may be capable of carrying out a PWM demodulation (modulation by pulse width) of the light signal intended to be transmitted on the electrically conductive elements.
    Each of the first and second conductive electrical supply elements may comprise several conductive tracks extending substantially parallel to one another, the conductive tracks of the first electrical supply conductive element extending substantially perpendicular to the conductive tracks of the second conductive element d power supply. In this case, the region corresponding to the superposition of one of the conductive tracks of the first conductive element with one of the conductive tracks of the second conductive element can form a display pixel area in which the LED module or modules belonging to this area of display are intended to display a luminous point of the device, and for example form a pixel of the display device.
    Each of the first and second electrically conductive elements may comprise a single electrically conductive plane.
    Each LED module can have two LEDs arranged head to tail side by side.
    The display device may also include:
    a display plane comprising several display pixel zones, each display pixel zone comprising at least one of the LED modules and a device for controlling said at least one of the LED modules of said display pixel zone as a function of a control signal of said display pixel area intended to be received by the control device;
    - an input / output interface of the display device, capable of receiving an image signal intended to be displayed on the display plane and comprising at least one control unit intended to deliver the control signals of the pixel areas display;
    in which :
    - the control unit is connected to at least a first antenna capable of transmitting by RF waves the control signals of the display pixel zones;
    each control device comprises at least a second antenna coupled to an RF signal processing circuit and is capable of receiving the command signal from the associated display pixel zone and controlling said at least one of the LED modules in the zone display pixel as a function of the control signal received to emit a light signal corresponding to a part of the image signal associated with said display pixel area.
    In such a display device, for example forming a pLED screen, the control devices which control the LED modules are no longer linked by wire to the control unit or units which process the image signal received by the device display. Such a configuration makes it possible to decorrelate the transport of the power supply signals vis-à-vis the control signals of the LED modules, which avoids the transport of the control signals in conductive elements which may have large dimensions and causing excessive attenuations. important.
    In addition, this architecture provides greater flexibility in the association between the display elements (LED modules and control devices) and the signal processing elements upstream of the display (control unit (s)). Thus, it is possible to easily modify the association of these different elements with each other.
    Each of the LED modules can comprise a control device, or each display pixel zone can comprise several LED modules and a common control device electrically connected to the LED modules of said display pixel zone.
    The second antennas can be arranged in the same plane as one of the two electric power supply elements.
    Each control device can be arranged between the two electric power supply conductive elements and supplied by said electric power conductive elements.
    It is thus possible to implement a method of displaying an image on a display device, comprising at least:
    - reception of an image signal intended to be displayed on a display plane of the display device;
    a processing of the image signal by at least one control unit of the display device to determine control signals of several display pixel areas of the display device such that each display pixel area comprises at least one LED module including at least one LED,
    - sending by RF waves of the control signals to the display pixel zones;
    a reception of each control signal by a device for controlling each display pixel area;
    a command of the LED module of each display pixel area by said control device as a function of the control signal received to emit a light signal corresponding to a part of the image signal associated with said display pixel area.
    The invention also relates to a method for producing a display device comprising at least:
    - Production of several LED modules each comprising at least one LED and at least two electrical supply pads arranged at two opposite faces of the LED module, one of which corresponds to an emissive face of the LED of said LED module;
    - Production of a support with at least a first electrically conductive element placed on one face of the support;
    - transfer of the LED modules to the support such that the first conductive element of electrical supply forms, for at least part of the LED modules, at least one reception surface, against which one of the electrical supply pads of each said LED modules is arranged to make an electrical contact, the connection surface of a supply pad being significantly smaller than said reception surface;
    - Realization of at least a second electric power supply element on the LED modules such that the LED modules are arranged between the first and second electric power supply elements and that the two electric power pads are connected respectively to the first and second electrically conductive elements.
    During the step of transferring the LED modules, the positioning of the LED modules can be carried out randomly or almost randomly on said at least one reception surface of the first conductive element.
    The dispersion of the LED modules on the reception support can be random and can include a spray projection of the LED modules, or a suspension of the LED modules in a solution then sedimentation of the LED modules on the reception support and a removal of the medium from the solution in which the LED modules were dispersed.
    As a variant, the transfer of the LED modules can be implemented in a pseudo-random manner using a transfer machine capable of simultaneously transferring several LED modules to a part of the reception support.
    The production of each of the first and second electric power supply elements may include the deposition by printing of several conductive tracks extending substantially parallel to one another, the conductive tracks of a first of the two electric power supply elements s 'extending substantially perpendicular to the conductive tracks of a second of the two electric power supply elements.
    The method may also include, between the postponement of the LED modules and the production of the second electrically conductive element, the implementation of the following steps:
    - deposit of a photosensitive resin covering the LED modules and the parts of the reception support located on the side of the LED modules and not covered by the LED modules;
    - exposure of the sensitive resin through the reception support which is transparent with respect to the wavelength used for this exposure;
    - Development of the exposed resin such that the remaining exposed parts of the photosensitive resin are kept between the LED modules and form passivation elements between the LED modules.
    The LED modules can be produced such that they each comprise at least one micro-magnet and / or such that the lateral faces of the LED modules are engraved such that, when the LED modules are dispersed on the reception support, an arrangement LED modules such that the emissive face of the LED is arranged on the side of the reception support which is optically transparent is favored.
    BRIEF DESCRIPTION OF THE DRAWINGS
    The present invention will be better understood on reading the description of exemplary embodiments given purely by way of indication and in no way limiting, with reference to the appended drawings in which:
    - Figure 1 schematically shows part of a display device, object of the present invention, according to a first embodiment;
    - Figure 2 schematically shows LED modules of a display device according to the invention;
    - Figures 3A to 7B show the steps of a method of producing a display device according to the invention;
    - Figure 8 shows an example of pLED of a display device according to the invention;
    - Figure 9 schematically shows an LED module comprising two LEDs mounted head to tail;
    - Figure 10 shows a method of producing LED modules;
    - Figure 11 schematically shows an electronic control circuit of an LED module;
    - Figure 12 shows the steps of a method for producing pre-orientation LED modules;
    - Figures 13A and 13B schematically show a pre-orientation LED module;
    - Figure 14 shows a variant of LED module transfer;
    - Figures 15 and 16 show simulation curves of random dispersion of the LED modules;
    - Figures 17 and 19 show diagrams of an exemplary embodiment of an electronic control circuit of an LED module;
    - Figure 18 of the signals obtained during a display by a module
    LED;
    - Figure 20 schematically shows a display device comprising the areas differentiated by color to be displayed;
    - Figure 21 shows schematically a part of a display device in which the LED modules communicate by RF signals;
    - Figures 22 and 23 schematically represent an LED module communicating by RF signals;
    - Figure 24 shows schematically the elements performing a transmission of signals by RF waves within the display device;
    - Figure 25 shows schematically a part of the display device according to another embodiment;
    - Figures 26A and 26B show diagrams of RF antennas used in a display device;
    - Figure 27 shows schematically a part of the display device according to another embodiment;
    - Figure 28 shows a diagram of a method of displaying an image according to a particular embodiment.
    Identical, similar or equivalent parts of the different figures described below have the same reference numerals so as to facilitate the passage from one figure to another.
    The different parts shown in the figures are not necessarily shown on a uniform scale, to make the figures more readable.
    The different possibilities (variants and embodiments) must be understood as not being mutually exclusive and can be combined with one another.
    DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS
    A display device produced by carrying LEDs in a non-deterministic, random or pseudo-random manner is proposed here on a transfer support (for example a plate containing TFT components or a non-functionalized support plate). The transfer support comprises at least one conductive track corresponding for example to the future rows or columns of a future matrix.
    First of all, reference is made to FIG. 1 which schematically represents a display device 100 according to a first embodiment.
    The device 100 forms a matrix of nxm display pixel zones 102. A display pixel zone 102 corresponds to a region of a display plane of the device 100 intended for the display of an image point controlled individually with respect to at the other image points of the display plane. Each display pixel zone 102 comprises one or more LED modules 104 ensuring the light emission from this display pixel zone 102 (a defective display pixel zone may however comprise no LED module, as described below). All the LED modules 104 present in the same display pixel area operate jointly to display the corresponding image point. In the first embodiment described here, each display pixel area 102 corresponds to a pixel of the display plane. In FIG. 1, only part of this pixel matrix is represented and corresponds to a set of 36 pixels distributed over 6 rows and 6 columns of pixels.
    The LED modules 104 each comprise an LED 105 and an electronic control circuit 118. The LEDs 105 are produced for example from at least one inorganic semiconductor, advantageously GaN and / or InGaN and / or the AlGaN. As can be seen in FIG. 2, each LED module 104 comprises on one side the LED 105, and on the other the electronic control circuit 118. The dimensions of each LED module 104, in a plane parallel to the interface between the electronic control circuit 118 and the LED 105, are for example included, in the case of microLED modules, between approximately 1 pm and 100 pm, or between approximately 5 pm and 100 pm, depending in particular on the size of the circuit control electronics 118 which will depend on its complexity, that is to say on the number and type of functions implemented by this circuit 118. The thickness of each LED module 104 is for example between approximately 2 μm and 10 pm.
    The LEDs 105 can emit either a light of variable color, or else emit a monochrome light. When monochrome LEDs 105 are used, different LEDS 105 emitting lights of red, green and blue colors (and possibly white) are preferably reported in order to have in each pixel at least one LED 105 of each of these colors (except in display pixel areas 102 defective).
    The LED modules 104 are here randomly distributed, within the display pixel areas 102 of the device 100. The density with which the LED modules 104 are distributed is such that statistically, each display pixel area 102 comprises at least one LED module 104 except for a limited number of zones 102. Each zone 102 can however include several LED modules 104.
    Each LED module 104 has two electrical supply pads 110, 112 connected to electrical supply conductive elements 106, 108 of the device 100. As can be seen in FIG. 2, the LED 105 of each LED module 104 and the circuit control electronics 118 of each LED module 104 are both connected, via the stud 110, to one of the conductive elements 108 and connected, via the stud 112, to one of the conductive elements 106. The conductive elements 108 are optically transparent or semi-transparent to allow the light emission of LEDs 105.
    In FIG. 1, the conductive elements 106 are produced in the form of electrically conductive lines extending in a first direction (horizontally in FIG. 1), and the conductive elements 108 form electrically conductive columns extending in a second direction substantially perpendicular to the first direction (vertically in Figure 1).
    An electrical supply potential, called V a | im , is for example intended to be applied to the conductive elements 106 and a reference electrical potential (for example ground), called V masS e, is intended to be applied to the conductive elements 108. Within each zone 102, each of the LED modules 104 is therefore connected to this supply potential and to the reference potential.
    We therefore propose here a screen produced by the transfer of LEDs transferred for example in a non-deterministic manner on a transfer support. The transfer support can correspond to a plate on which one of the conductive elements 106, 108 is formed in the form of rows or columns as is the case in the first embodiment described above. The transfer support can also correspond to a TFT plate including electronic control elements.
    This particular transfer of the LED modules 104 is possible thanks to the large dimensions of the reception or contact surfaces of the LED modules 104, that is to say to the dimensions of the electrically conductive elements 108, relative to those of the LED modules and more particularly to the dimensions of the conductive pads present on each LED module and intended to allow the supply of the LED module. In fact, given that the dimensions of these electrically conductive elements are much larger than those of the LED modules 104 and therefore also of the electrical supply pads 110, 112 with respect to the contact surfaces of the electrically conductive elements 108, it is not necessary to perform precise positioning of the LED modules 104 on these reception surfaces. These dimensions are such that in a plane parallel to the contact surfaces, a ratio between the dimensions of one of the contact surfaces on the support and those of one of the two opposite faces of one of the LED modules is greater than or equal to 5 , or even greater than or equal to 10. The contact surface on the support corresponds to the surface available for making electrical contact with one of the LED modules 104, this surface possibly being able to be partially perforated or made up of different surfaces electrically connected and to the same potential.
    There are described in connection with FIGS. 3A to 7B steps of a method for producing the device 100.
    A first level of electrode is first of all produced (FIGS. 3A and 3B). In the example described here, these are the conductive elements 108 intended to be located on the side of the emissive faces of the LEDs 105. A transparent support 130 is used, for example made of glass. ITO bands are then etched at the pitch corresponding to the pitch of the desired display pixel areas 102, preferably by laser etching of the interband areas from a continuous ITO plane. These ITO bands form the conductive elements 108.
    The LED 104 modules are ideally suspended in a water-IPA mixture and kept in suspension by ultrasonic agitation. The equipment may advantageously be of the type used for liquid crystal displays, for the random dispersion of the spacers.
    The LED modules 104 are then randomly dispersed, for example by spray so as to minimize the number of defective zones 102, on the conductive elements 108 (FIGS. 4A and 4B). For a screen of 1.10 6 pixels or 102 zones, there is a volume of solutions containing of the order of 1.10 7 LED modules 104, which must ensure a defect rate of the order of 10. Direct metal-to-metal bonding can be realized to ensure the connection of LED modules 104 with conductive elements 108.
    An insulating resin 132 of negative type is distributed over the entire structure produced, preferably by spray and with a thickness preferably greater than the thickness of the LED modules 104 (FIG. 5). This resin is advantageously black in order to obtain a good contrast with the LEDs 105 during a light emission with a non-zero emission of ambient light, as well as to have a black display plane when the LEDs 105 do not emit light.
    Insolation through the transparent support 130 and conductive elements 108 allows the resin 132 to be exposed between the LED modules 104 and not the resin present on the LED modules 104. Development of the resin 132 then makes it possible to remove the non-exposed resin present on LED modules 104 (figure 6). The remaining portions of the resin passivate between the LED modules 104.
    Finally, the other conductive elements 106 are produced for example by printing the metal electrodes (perpendicular to the preceding electrodes. The resin 132 deposited in the previous step then plays a smoothing role promoting the deposition of the conductive elements 106 by printing.
    In this process of random dispersion of the LED modules 104, the distribution follows a Poisson law. By assuming a number of display pixel areas 102 of 1.10 6 and using Poisson's law, it is possible to evaluate the number of LED modules 104 that must be dispensed as a function of the number of faults which is accepted for the device 100. By default is meant a display pixel zone 102 where there is no LED module 104 or no LED module 104 functional. In the graph represented in FIG. 15, considering a million pixel display areas 102, it is necessary to dispense of the order of 14 million LED modules 104 on the reception support in order to have only one area display pixel 102 defective (the average number of LED modules 104 per pixel area then being 14). By dispersing 10 million LED modules, approximately 45 defective display pixel areas 102 are obtained. It is also possible to estimate the maximum number of LED modules 104 that can be found in a display pixel area 102 as a function of the number of faults accepted. Thus, in FIG. 16, by accepting a single defective display pixel area 102, it is possible to find a display pixel area 102 comprising 35 LED modules 104.
    In the process described below, the LED modules 104 are distributed by means of a spray dispersion on the support 130 and the conductive elements 108. As a variant, it is possible to place the LED modules 104 in a liquid to obtain a colloidal suspension LED modules 104. This suspension is distributed over the support 130 and the conductive elements 108 then, by sedimentation and then aspiration of the medium in which the LED modules 104 are located, the LED modules 104 are found disposed on the conductive elements 108.
    The LEDs 105 of the LED modules 104 are for example like that shown in FIG. 8. This LED 105 comprises a layer 134 of n-doped semiconductor placed against a layer 136 of p-doped semiconductor, this stack forming a pn junction being disposed between two conductive layers 138 comprising for example ΓΙΤΟ (transparent to allow the light emission of the LED 105). The semiconductor of the layers 134, 136 is for example GaN. The layers 138 facilitate contact with the conductive elements 106, 108.
    By randomly distributing the LED modules 104 on the support, some of these LED modules 104 are not arranged in the right direction, that is to say have their light face which is not on the right side of the display plane. . However, given the large number of dispersed LED modules 104, a sufficient number of correctly oriented LED modules 104 are statistically obtained. The inverted LED modules 104 do not pose an electrical problem because under voltage, these LED modules 104 form reverse biased diodes which do not disturb the operation of the other correctly oriented LED modules 104. When each LED module 104 includes a CMOS type control circuit 118, the CMOS architecture of this circuit 118 is such that a reverse bias does not create a short circuit.
    In the embodiment described above, the dispersed LED modules 104 comprise an LED 105 and a control circuit 118. As a variant, it is possible that the LED modules 105 do not comprise a control circuit 118, but only one or several LEDs 105.
    Advantageously, it is possible that each LED module 104 has two LEDs 105 arranged head to tail one next to the other. Such a configuration is shown in FIG. 9 in which, at a first face, a first LED 105a comprises the n-doped layer 134a and a second LED 105b comprises the p-doped layer 136b, and at a second face opposite the first, the first LED 105a comprises the p-doped layer 136a and the second LED 105b comprises the n-doped layer 134b. Thus, one of the LEDs 105 will be functional whatever the face (first or second) which finds itself in contact with one of the conductive elements 108.
    An example of a method for producing LED modules 104 is described in connection with FIG. 10.
    In step a) of this figure, a matrix of the electronic control circuits 118 is produced in CMOS technology in a substrate 142 of semiconductor, for example of silicon.
    In parallel with the production of the matrix of electronic control circuits 118, a matrix of LEDs 105 is produced from another semiconductor substrate 144, for example parepitaxy (step b)).
    The matrix of electronic control circuits 118 is then transferred to the matrix of LEDs 105. Contact resumption between the electronic control circuits 118 and the LEDs 105 is carried out during this assembly. The semiconductor of the substrate 142 is then thinned then the pads 112 are then produced on the side of the control circuits 118. The growth substrate 144 is then removed (step c)).
    An engraving and a singularization of the LED modules 104 are then implemented (step d)). These LED modules 104 can then be put into solution.
    An exemplary embodiment of the electronic control circuit 118 is shown in FIG. 11. This circuit comprises a MOS transistor T connected between a contact 146, for example of ITO, intended to be connected to the conductive element 106, and the LED 105. The gate of the transistor T is connected to the contact 146. The circuit 118 also includes a CMOS part 148 not detailed here and intended for the processing of the data signals intended to be received by the LED module 104 and for driving the transistor T supplying electrically LED 105. This part 148 can correspond to a simple CMOS transistor when no function other than the power supply of LED 105 is fulfilled by the circuit 118. This part 148 is connected to a second contact 150, for example ITO, intended to be connected to the conductive element 108 and located on the side of the emissive face of the LED 105. The contact 150 is connected to the part 148 by means of a via co inductor 152 which is electrically insulated from the semiconductor layers 134 and 136 of the LED 105.
    When the LED modules 104 are dispersed, it is advantageous to favor the positioning of the LED modules 104 in the right direction, that is to say to have the LED modules 104 oriented such that the emissive faces of the greatest number of LED 105 are turned towards the display face of the device 100. It will therefore be necessary to plan to use a technique of pre-orientation of the LED modules before / during their transfer to the support.
    A first solution to promote this good orientation can be to incorporate micro-magnets within the LED modules 104. These micro-magnets can be used to subsequently assemble the LED modules 104 on the right side during a random placement of the modules LED 104. For example, using the method described above in connection with FIG. 10, at the end of step c), a dielectric 152 such as SiO 2 is deposited on the face comprising the pads 112. A handle temporary 151 is secured to the LEDs 105, the bonding of this temporary handle 151 can be carried out before the thinning of the substrate 142. A planarization of this dielectric 152 is then implemented, then micro-magnets 154 are placed on this planarized dielectric , distributed such that at least one micro-magnet 154 is associated with each LED module 104 (see FIG. 12, step a). The micro-magnets 154 are covered with a dielectric layer 156, for example of the same kind as the dielectric 152, then a resumption of contact of the pads 112 is carried out through this dielectric layer 156 and the dielectric 152 via vias conductors 158 formed for example by a damascene process (Figure 12, step b)). A singularization of the LED modules 104 by etching of the stack produced is then implemented, the temporary handle 151 being removed (FIG. 12, step c)). Thus, the damascene process makes it possible to prepare a surface compatible with direct bonding. By thus integrating micro-magnets 154 within the LED modules 104, the positioning of these LED modules 104 is influenced because the micro-magnet 154 is attracted to the side of the conductive elements 106, thus promoting the correct positioning of the emissive faces of the LEDs 105 .
    Other configurations of the LED modules 104 can promote the correct orientation of these modules. For example, to avoid positioning an LED module 104 such that one of the side faces is on the side of the conductive elements 108, it is possible to engrave the LED modules 104 in a shape as shown in FIGS. 13A and 13B, that is to say comprising parts engraved at the side faces. The upper face of the LED module 104 includes the contact 110 around which an engraving of the insulation has been made in part to highlight this contact. In this way, after dispersion by the spray method described above, only the bottom face of the LED module 104 will have sufficient adhesion (by Van der Walls forces) to resist rinsing (possibly assisted by a little HP) . The LED modules 104 which do not adhere to the conductive elements 108 are recycled. In this configuration, it is wise to disperse a number of LED modules 104 at least 6 times greater than the number of LED modules 104 than what is provided for by Poisson's law. A single dispersion of LED modules 104 is very interesting because a part of the indeterminacy is lifted because the overcrowded areas with the formation of clusters of LED modules 104 will be cleaned of these clusters which cannot be fixed by the shape of the LED modules 104.
    Another way of dispersing or arranging the LED modules 104 on the reception surfaces formed by the conductive elements is shown in FIG. 14.
    The LED modules 104 are transferred to a temporary handle 160, emissive faces disposed against this handle 160 (FIG. 14, step a)). This assembly is then turned over (FIG. 14, step b)) and a part of the LED modules 104 are detached on the conductive elements 108 (FIG. 14, step c)). The positioning constraints are relaxed due to the dimensions of the conductive elements 108 which are larger than those of the LED modules 104. The temporary handle could also be in the form of a flexible substrate which could be stretched before being turned over. In this case, the positioning of the LED modules on the reception surfaces of the conductive elements 108 will be different from one display device to another, and the positioning of the LED modules on a reception surface considered is thus pseudo-random.
    In the examples described above, the dispersion of the LED modules 104 is carried out in a non-deterministic manner for their positioning and possibly in a non-random manner for their orientation when a technique for pre-orientation of the LED modules is implemented. However, having reception surfaces of dimensions much larger than those of the deferred LED modules also makes it possible to implement deterministic transfer solutions, for example via a machine transferring the LED modules 104 onto the reception surface. , by relaxing the alignment constraints imposed due to these dimensions. Thus, it is possible to work with larger transfer surfaces than when the LED modules must be transferred to electrical contacts of size similar to that of the pads of the LED modules. For example, it is possible to work with a transfer machine, the transfer element (called “stamp”) of dimensions 5 cm x 5 cm to transfer the LED modules 104 in steps of 250 μm, ie 50,000 LED modules 104 simultaneously. The positioning of the transfer element relative to the receiving surface does not need to be precise (+/- 10 pm may be sufficient), which makes it possible to gain in transfer speed and therefore in process cost .
    The transfer yield is not 100%. To be sure to have at least one LED 104 module (or even 3 modules if you want three colors per pixel area with monochrome 104 LED modules), you would have to put redundancy per pixel display area. Assuming a transfer efficiency of 99%, if we double the transfers then it is possible to reach 99.99% of the pixels having at least one LED module 104. This figure of 99.99% corresponds to the case where the transfer yield is independent from one transfer to another. If the transfer element has a defect locally, there is a dependence from one transfer to another and in this case the doubling of the transfer steps can only copy the defect (the same overall yield is obtained after a second pass of the carry-over item). To overcome this possible defect locally linked to the reference of the transfer element, the transfer redundancy step can be done with an offset of Nx, Ny display pixel zones (Nx for the number of online pixel zones, and Ny for the number of pixel zones in column) so that the fixed defects of the transfer element are distributed spatially on the reception support.
    If there is a need to further increase the redundancy in order to achieve better overall performance, each passage of the transfer element over the same reception area can be offset. By targeting a yield of 10 faults / 10 6 pixel display areas, then with a transfer efficiency of 99%, 3 passes of the transfer element on the receiving surface are sufficient. If the transfer efficiency is 96%, 4 passes may suffice. Typically, the different passages can be offset by several pixels.
    In the device 100 described above, the LED modules 104 have their electrical supply pads 110, 112 connected to the electrical supply conductive elements 106, 108 on which the supply voltage is applied to supply the LED modules 104 electrically. the only contact pads of the LED modules 104 are the power pads 110, 112, and the data signals making it possible to drive and control the LED modules 104 must be brought to the LED modules other than by dedicated wired connections. Thus, in this example, the control signals are transmitted to the LED modules 104 via these supply pads 110, 112 and these conductive elements 106, 108 in the form of a modulation signal which the LED modules 104 must interpret.
    Other ways of supplying the LED control signals can be envisaged, for example by RF channel (see below).
    FIG. 17 represents a block diagram of the functions implemented in the electronic control circuit 118 of each LED module 104 in order to carry out the control by PWM modulation (pulse width modulation) of an LED 105 of the module from data and synchronization signals transmitted by amplitude modulation of the supply voltage present on an electrical supply conductor 106,108.
    This block diagram describes an architecture adapted to a 3-channel LED module 104 (RGB) making it possible to perform the function of addressing and writing binary data. The LED module thus includes 3 LEDs with their respective control switches, similar to the example shown in FIG. 11.
    On power-up, a PoR (Power on Reset) block 170 initializes a first decoder 172 called decoder_l which points at one given time to one of the three channels, for example to channel R (red), and initializes, by example at "0", also the RGB data, in three memory type flip-flops (latch in English) Latch_R, Latch_G and Latch-B.
    Demodulators 174, 176 each receive the supply signals from the conductive elements 106, 108 which include the data and synchronization signals by amplitude modulation of the supply voltages "POWER" and ground "GROUND" respectively. The data signal is called "POWER + DATA_PULSE" and the synchronization signal called "GROUND + CLK_PULSE". These demodulators 174, 176 make it possible to extract the variations in supply and ground voltages in order to reconstruct binary signals (called DATA_PULSE and CLK_PULSE).
    The DATA_PULSE signal is sent to the input of a second decoder 178, outputting the DATA data signal allowing in fine the control of the LED 105. The DATA signal is stored in one of the three memory elements 180.1,180.2,
    180.3 used for the 3 RGB channels depending on the signals from the decoder 172, VALID_R, VALID_G, VALID_B. The assembly is synchronized by the decoder 172 which changes the selected channel at each pulse of the clock signal CLK_PULSE via the sending of the signals VALID_R, VALID_G, VALID_B to the memory elements 180.1, 180.2 and 180.3.
    FIG. 18 represents examples of timing diagrams of signals obtained in this circuit. The sending of 2 pulses on CLK_PULSE allows on the one hand to increment the choice of the RGB channel, then allows to define a time window during which we wait to see if we receive or not a pulse of DATA_PULSE. If yes, then for example a 1 is written in the storage element corresponding to the selected channel (R, G or B), otherwise a 0 is written.
    In this example, the value stored in each latch type memory point (memorizing a single binary value) is used to directly control the control switch of an LED 105 in "all or nothing" mode (the LED being conductive or not conductive because respectively connected or not connected to the supply voltage).
    In order to be able to control the light intensity of an LED 105, it is necessary to control the conduction and non-conduction times. Thus, the value present in each memory point must be modified during each image frame.
    Addressing in PWM (“Puise Width Modulation”) allows you to write only 1s and 0s to modulate the average luminance emitted by an LED 105 by modulating its ignition time: 1 = on, 0 = off. If the LED 105 is lit during the entire image time, this corresponds to the maximum code, for example on 3 bits: 111. If on the other hand the LED 105 is off during the entire image time, then this corresponds to the minimum code: 000.
    In this example with 3 addressing bits, the duration of switching on or off associated with the most significant bit (the third) corresponds to four times that associated with the least significant bit (the first), and that associated with the second bit corresponds to twice that associated with the least significant bit. The on or off time can be coded by choosing a value between 0 and 7.
    In the case of a matrix type display device such as that described in connection with FIG. 1, it will thus be possible to provide that each line of pixels is addressed 3 times during a frame, with decreasing time intervals . Thus the first time interval lasts 4 times longer than the third interval, and the second time interval lasts 2 times longer than the third time interval. The values memorized in the “latch” memory points during the first, second and third time intervals correspond respectively to the 1st bit (most significant), 2nd bit and 3 rd bit (least significant).
    In the case where the modules include 3 LEDs, it is necessary during each addressing of a line, to carry out 3 information transmissions for the 3 channels (values memorized in the respective memory points latch_R latch_G and latch_B). It is thus possible to consider successively addressing the 3 channels of the pixel module by sending 6 pulses to CLK_PULSE and applying or not applying 3 pulses of DATA_PULSE depending on the code to be applied.
    Such a protocol offers the advantage of having a very compact architecture, which is extremely advantageous because it allows LED modules 104 to be made with small dimensions.
    In this protocol, a demodulation error can lead to a channel selection error or a written data error. If the data is false, the consequence is limited since it is punctual, on the other hand an error on the detection of CLK_PULSE causes an error on the time window and an error on the channel addressed. In this case a reset by Power On Reset is necessary.
    In order to improve the robustness of the circuit 118, it is possible to put a binary decoder at the output of the demodulators 174, 176 to be certain of addressing the channel R, G, or B individually instead of using a chaser (cycled sequencer ). However, this requires more space and requires the transmission of more data (including a complex tag which makes it possible to know which channel is addressed).
    An exemplary embodiment of the circuit 118 implementing the functions of the block diagram of FIG. 17 is shown in FIG. 19.
    Other embodiments of an electronic control circuit present in the LED module can be envisaged. We could for example replace each unitary storage element (latch) by a storage element of several bits, of the register type in order to store in each register the digital value, for example on 3 bits as above, corresponding to the desired light intensity. . In this case, it is not necessary to provide 3 line addresses during the frame, but a single line addressing which makes it possible to convey the value of the 3 bits. It will therefore be necessary to add a control circuit between each register and the control switch for the corresponding LED to convert the binary value into a time control signal for the LED. An advantage of such an alternative embodiment is that it makes it possible to envisage updating the register values only when it is desired to modify the light intensity, thus allowing a reduction in energy consumption. In addition, associated with an LED module identification device as described below, it is possible to envisage architectures other than matrix.
    After the production of the device 100, and before its use, when the LED modules 102 have been randomly distributed on the reception support, the number of LED modules 104 per display pixel area 102 being unknown, a first calibration phase allows , by reading the consumption when the LEDs 105 of a display pixel area 102 are ON, to determine their number. Knowing this number, the display codes are adapted inversely proportional to arrive at the brightness initially desired.
    Other approaches for calibrating the display device 100 are possible, such as for example adjusting the current or adjusting the voltage of the display pixel zones 102 containing the n LED modules 104. It is also possible to consider visual detection to determine the position, color and number of LED modules 104 per pixel display areas 102.
    Thanks to this calibration, each display pixel zone 102 operates in the same way regardless of the number of LED modules 102 in each of the zones 102.
    As a variant, this calibration can be carried out via an identification of the LED modules 104. The communication process using an identification of the LED modules can be done in different ways, by wire or non-wire (for example RF communication).
    Before using a communication process with module identification, each LED module must receive an identifier. This “customization” of each LED module can be achieved by action on a hardware component: by flashing a rom, by burning fuses to assign a code to each LED module 104, or perhaps by programming an LED module 104 .
    During a communication procedure with identification, it is also possible to use statistical properties to identify the LED modules 104 without having a unique identification code. This makes it possible to reduce the number of identification bits to memorize and greatly reduces the complexity of the LED modules 104.
    For this, “n” LED modules 104 having different identification codes are produced and distributed randomly to produce the device 100. Each display pixel area 102 has one or more LED modules 104 which have an address from “n”. During a communication with the LED modules 104 of a display pixel area 102, a census of the LED modules 104 is carried out by scanning the n address codes in order to know their number and to identify the addresses of the LED modules having replied present. Thus, it is possible to switch off the redundant LED modules 104 and keep only one active LED module 104 per display pixel zone. By this means, there is no longer any adjustment to be made (voltage / current / binary code) in order to have a homogeneous display throughout the display because there is only one LED module 104 per zone. display pixel 102.
    The identification can be carried out in software. Thus, it is possible to communicate with the display pixel areas 102 in the manner of a computer on the internet network by sending requests and obtaining a unique address on the network. This requires a communication protocol, digital electronics and memory.
    An advantage of the individual addressing of the LED modules 104 is that it is possible to change the writing method in the display device 100. Indeed, instead of scanning all the lines in turn in front refresh the data present on the column bus in order to display an image, if the pixels have a proper address, then it is possible to address only the pixels which have changed from one image to the next, which makes it possible to obtain a very low consumption of the device 100.
    Identification by address (individual or not) offers the possibility of deactivating certain LED modules 104, this allows redundancy to be exploited. In the event of failure or excessive dispersion of an LED module 104, it is possible to deactivate it and select another (if there is one) located in the same display pixel area 102.
    In the embodiments described above, the control electronics of the LEDS 105 is integrated into the LED modules 104. As a variant or in addition, it is possible that electronic control circuits are present under the reception support of the device 100 to which the LED modules 104 are connected, for example produced in CMOS technology. In this case, it is bare LEDs that are reported.
    The reception support can be structured according to differentiated zones each intended to receive LED modules 104 adapted to the emission of a single red, green or blue color. This eases the constraint of depositing LED modules 104 because it is possible to use a stencil for depositing LED modules 104 associated with each of these colors and makes it possible to keep a classic display architecture by sticking to the rear face of the support. a large area TFT, Poly-Si type MOS control electronics. FIG. 20 schematically represents such a configuration in which reception areas 182 differentiated for the different colors are produced for the arrangement of the LED modules 104. The control electronics present on the rear face are referenced 184.
    As an alternative to TFT technology for producing the control electronics 184, it is possible to use a glass plate and to stick MOS control modules against this plate to address the display pixel areas 102.
    After the RGB modules have been deposited, it is possible to communicate with the desired module or to impose a configuration (for example by laser which burns fuses) in order to force one of the modules to display only one of the desired colors. This combined with a structuring of the electric power supply elements makes it possible to have a display device 100 of large area and potentially reconfigurable on a large area TFT type techno while manufacturing / depositing only one type of RGB module.
    A controller can manage the supply signals, the currents or the voltages of several pixel display zones each producing an RGB light emission. This controller can receive its data by wire or RF link, and distribute the information by display pixel area. This solution offers the advantage of having a very small CMOS controller compared to the surface occupied by the pixel display areas controlled.
    We will now describe different embodiments of the display device 100 in which the LED modules 104 communicate by RF signals.
    Reference is first made to FIG. 21 which schematically represents a part of such a display device 100.
    This device 100 includes a display plane on which one or more images are intended to be displayed. This display plane is divided into several display pixel zones 102 controlled independently of each other.
    Each display pixel area 102 comprises one or more LED modules 104. Each LED module 104 comprises at least one LED 105, which is here a pLED. The LEDs 105 each have a p-n junction formed by layers of GaN and / or InGaN and / or AIGaN.
    The LED modules 104 are interposed between two conductive elements of electrical supply 106, 108 (referenced 106.1 to 106.6 and 108.1 to 108.8 in FIG. 21), and each LED module 104 comprises two electrical supply studs 110, 112 arranged at two opposite faces 114, 116 of the LED module 104, one of which corresponds to an emissive face of the LED 105 of said LED module 104 and connected respectively to one and the other of the two electrically conductive elements 106, 108 on which a supply potential (on element 106 in this example) and a reference potential (on element 108 in this example) are applied. This configuration of one of the LED modules 104 is visible in FIG. 22. In this example, the emissive face of the LED 105 corresponds to the face 114 which is located on the side of the conductive element 108.
    By way of example, the conductive element 108 which is disposed against the emissive face of the LEDs 105 may include a transparent conductive material such as ΙΊΤΟ.
    In FIG. 21, the electrical supply conductors 106, 108 are produced in the form of conductive tracks arranged perpendicular to one another. In the embodiment described here, each intersection of one of the conductive elements 106 arranged in line with one of the conductive elements 108 arranged in a column defines a display pixel area. This arrangement thus forms a matrix of display pixel zones 102. In addition, by controlling the LED modules 104 such as the LED module or modules 104 of each zone 102 from the same signal, that is to say such that they display a light signal forming the same image point, each pixel area 102 therefore corresponds to one pixel of the display plane of the device 100.
    Here, each LED module 104 also includes a control circuit 118. This control circuit 118 comprises electronic elements making it possible to control the light emission produced by the LED 105 of the module 104 by delivering to the LED 105 a signal representative of the light signal to emit.
    An exemplary embodiment of such a control circuit 118 is shown diagrammatically in FIG. 23. This circuit 116 comprises a first transistor T1 used to control the switching on or off of the LED 105, a transistor T2 making it possible to inject the current desired in the LED 105 and a storage capacity C making it possible to maintain the desired voltage on the gate of the transistor T2. A voltage Vdd from the conductive element 106 is applied to the drain of the transistor T2 from the electrical supply pad 112 of the LED module 104 in contact with the conductive element 106. The current delivered by the transistor T2 is applied to the one of the layers of the pn junction of LED 105. The other layer of the pn junction of LED 105 is subjected to the electrical potential transmitted by the conductive element 108 via the electrical supply pad 110.
    Control signals are transmitted to the control circuit 118 from a control device 120. In this embodiment, each LED module 104 includes a control device 120 intended to control the light signal intended to be emitted by this LED module 104. The control device 120 may include electronic circuits such as a memory, a received message decoder, a command sequencing unit to be applied by the control circuit 118, etc. The control device 120 is advantageously supplied via connections connected to the conductive elements 106 and 108.
    Then, the device 100 includes an input / output interface capable of receiving an image signal Si mage intended to be displayed by the device 100 as input. This input / output interface comprises one or more control units 122, represented in FIG. 24, which, from the image signal S imag e or from a part of this signal S imag e, determines (s) the control signals to be sent to the different display pixel areas 102 so that the LEDs 105 emit light signals corresponding together to the image signal S image .
    Unlike conventional screens in which these control signals are transmitted from the screen element receiving the image signal to be displayed on the screen to the control circuit of each pixel via wired connections, the or each of the control units 122 of the device 100 transmits the control signals of the display pixel areas 102 to the control devices 120 by RF waves, wirelessly, via at least a first antenna 124. These control signals are received by second antennas 126 each coupled to one of the control devices 120. Thus, in the embodiment described here, since each LED module 104 is provided with its own control device 120, each LED module 104 includes an antenna 126 allowing to receive the control signal which will, after processing performed by an RF signal processing circuit included in the control device 120, obtain the light emission desired for LED 105 of this LED module 104 (see diagram in Figure 24).
    In general, the control signals propagated by RF channel can comprise different types of information, for example an identifier of the recipient control device 120 or a desired level of brightness for a recipient display pixel area 102. The control signal can also include a time sequence of desired brightness levels. The information transiting by RF channel can possibly be coded. The recipient control device 120 may, if necessary, decode the information and consequently control the control circuit so as to obtain the desired level of brightness, or the desired sequence. The information on the desired level or levels of brightness can be stored in a memory of the control device 120 and this information can, for example, be updated only when there is a need to change the desired brightness values.
    Although in FIG. 24, a single antenna 124 is shown, it is possible to have several control units 122 each connected to an antenna 124 and intended to transmit by RF the control signals of only part of the pixel areas d display of the device 100. It is for example possible to have several control units 122 each connected to a separate antenna 124, these control units and these antennas 124 being spaced from each other by a distance equal to approximately 300 μm , with each of these control units 122 and of these antennas 124 managing the RF transmissions within the device 100 in a region forming a square of dimensions 300 μm x 300 μm.
    In the embodiment described above, each display pixel area 102 comprises an LED module 104 comprising for example an LED 105 of monochrome type. As a variant, the LED module 104 could include 3 LEDs, for example RGB, for Red / Green / Blue.
    As a variant, each display pixel zone 102 may comprise several LED modules 104 intended to display the same light signal.
    As a variant, each display pixel zone may comprise several monochrome LED modules 104 and for example at least three LED modules 104 capable of emitting red, green and blue colors respectively. In this case, the light signals emitted by each of the monochrome diodes of different colors can be defined from the same control signal (which can request the same current level in all the LEDs or request different current levels in the LEDS) or from different control signals for each of the LED colors in the display pixel area.
    In the embodiment described above, each of the LED modules 104 comprises a control device 120 coupled to an antenna 126.
    According to another embodiment, it is possible that each control device 120, as well as each antenna 126, is associated with several LED modules 104. In FIG. 25, a display pixel area 102 of the device 100 is shown. This zone includes several LED modules 104 coupled by wire (wires referenced 128) with a control device 120 common to these different modules 104. The control unit 122 associated with this zone 102 therefore sends the different control signals of these modules LED 104 by RF transmission to the control device 120 which then transmits them by wire connections to the modules 104.
    In the example shown in FIG. 25, the control device is arranged between the conductive elements 106, 108, like the LED modules 104.
    This other embodiment is for example used when the density of the LED modules 104 does not allow each LED module 104 to have its own antenna 126, due in particular to the dimensions of these antennas 126 imposed by the characteristics of the signals transmitted.
    In the embodiments described above, the antennas 126 can be arranged in the same plane as one of the two conductive elements 106, 108 (in the same plane as the conductive element 106 in the embodiments described above) . In this case, the antennas 126 can be produced in the form of planar, or “patch”, perforated antennas (example shown in FIG. 26A) or in the form of spaced lines (example shown in FIG. 26B).
    According to another embodiment shown in FIG. 27, it is also possible to have the control devices 120 which are not arranged in the display plane with the LED modules 104, but which are arranged behind this plane of display, in this case with wire connections between these control devices 120 and the LED modules 104.
    According to an alternative embodiment, it is possible that the LED modules 104 are not supplied electrically via the conductive elements 106, 108, but are remotely supplied by using for example a communication of the RFID or NFC type.
    In the embodiments described above, the conductive elements 106, 108 each correspond to several conductive tracks extending in different directions. As a variant, it is possible that the conductive elements 106, 108 each correspond to a conductive plane common to all the LED modules 104 or common to a subset of LED modules 104 of the device 100.
    The RF communications described above can use identification codes associated with each LED module 104 or groups of LED modules 104, for example those of the same pixel display area 102.
    A flow diagram of the display method implemented by the device 100 is shown in FIG. 28.
    In a step 200, the image signal intended to be displayed on the display plane of the device 100 is received by the device 100 via its input / output interface.
    In a step 202, the received image signal is processed by the control unit or units 122 which determine the control signals to be sent to the different display pixel areas 102 of the device 100.
    In a step 204, the control signals calculated by the control unit (s) 122 are sent to the display pixel areas 102 by RF waves via the antenna (s) 124.
    In a step 206, the control signals are received, via the antenna (s) 126, by the control device (s) 120 present in each display pixel area 102 addressed by the control unit (s) 122.
    In a step 208, the LED modules 104 are then controlled by the control devices 120 to display the light signals corresponding to the control signals which have been transmitted to them.
    Those skilled in the art will be able to envisage other embodiments of the present invention. Among other things, although the embodiments described above comprise LED modules each disposed between two conductive supply elements 10, it is quite possible to envisage a display device in which the two conductive elements are positioned on a same substrate, on the same side of the LED modules (an embodiment of such a display device is described in French patent application FR 3 044 467 Al.
    权利要求:
    Claims (17)
    [1" id="c-fr-0001]
    1. Display device (100) comprising at least:
    - a support (130);
    - first and second electrically conductive elements (106,108), said at least one first conductive element (108) being placed on one face of said support (130);
    - several LED modules (104) each comprising at least one LED (105), each LED comprising at least two layers (134, 136) forming a pn junction, and each LED module comprising two electrical supply pads (110, 112) disposed respectively on two opposite faces of the LED module, one of which corresponds to an emissive face of the LED of said LED module, in which the electrical supply pads of each LED module are respectively connected to the first and second power supply elements electrical, for the electrical supply of the LED module, and in which, the connection surface of an electrical supply pad of an LED module with the first conductive element of electrical supply is significantly smaller than a surface d reception of the first conductive element corresponding to the surface of the first conductive element in a plane parallel to the connection surfaces of the supply pads of the LED modules and capable of making electrical contact with an electrical supply pad of an LED module.
    [2" id="c-fr-0002]
    2. Display device (100) according to claim 1, in which the LED modules (104) are distributed randomly, so that the density of LED modules on the reception surface is not uniform.
    [3" id="c-fr-0003]
    3. Display device (100) according to one of the preceding claims, in which the ratio of dimensions between the reception surface of the first conductive element (108) and the connection surface of an electrical supply pad ( 110) of one of the LED modules is greater than or equal to 5.
    [4" id="c-fr-0004]
    4. Display device (100) according to one of the preceding claims, in which each LED module (104) further comprises a control circuit (118) of the LED (105) of said LED module (104), the circuit control (118) being capable of delivering, on one of the layers of the pn junction of the LED (105), a signal representative of the light signal intended to be emitted by the LED (105).
    [5" id="c-fr-0005]
    5. Display device (100) according to claim 4, in which the control circuits (118) are capable of carrying out a PWM demodulation of the light signal intended to be transmitted on the electrically conductive elements.
    [6" id="c-fr-0006]
    6. Display device (100) according to one of the preceding claims, in which each of the first and second electric power supply elements (106, 108) comprises several conductive tracks extending substantially parallel to one another, the conductive tracks of the first electrical supply conductive element extending substantially perpendicular to the conductive tracks of the second electrical supply conductive element.
    [7" id="c-fr-0007]
    7. Display device (100) according to one of claims 1 to 5, in which each of the first and second electrically conductive elements (106,108) comprises a single electrically conductive plane.
    [8" id="c-fr-0008]
    8. Display device (100) according to one of the preceding claims, in which each LED module (104) comprises two LEDs arranged head to tail one next to the other.
    [9" id="c-fr-0009]
    9. Display device (100) according to one of the preceding claims, further comprising:
    - a display plane comprising several display pixel zones (102), each display pixel zone (102) comprising at least one of the LED modules (104) and a control device (120) of said at least one of the modules LEDs (104) of said display pixel area (102) in accordance with a control signal from said display pixel area (102) to be received by the control device (120);
    - an input / output interface of the display device (100), capable of receiving an image signal intended to be displayed on the display plane and comprising at least one control unit (122) intended to deliver the display pixel area control signals (102);
    in which :
    - the control unit (122) is connected to at least a first antenna (124) capable of transmitting by RF waves the control signals of the display pixel areas (102);
    each control device (120) comprises at least a second antenna (126) coupled to an RF signal processing circuit and is capable of receiving the command signal from the associated display pixel area (102) and of controlling said command at least one of the LED modules (104) of the display pixel area (102) as a function of the control signal received to emit a light signal corresponding to a part of the image signal associated with said display pixel area (102).
    [10" id="c-fr-0010]
    10. Method for producing a display device (100) comprising at least:
    - production of several LED modules (104) each comprising at least one LED (105) and at least two power supply pads (110, 112) arranged at two opposite faces of the LED module, one of which corresponds to one face emitting the LED of said LED module;
    - Production of a support (130) with at least a first electrically conductive element (108) placed on one face of the support;
    - transfer of the LED modules to the support such that the first conductive element of electrical supply forms, for at least part of the LED modules, at least one reception surface, against which one of the electrical supply pads of each said LED modules is arranged to make an electrical contact, the connection surface of a supply pad being significantly smaller than said reception surface;
    - Realization of at least a second electric power supply element on the LED modules such that the LED modules are arranged between the first and second electric power supply elements and that the two electric power pads are connected respectively to the first and second electrically conductive elements.
    [11" id="c-fr-0011]
    11. The method of claim 10, wherein, during the step of transferring the LED modules, the positioning of the LED modules is carried out randomly or almost randomly on said at least one reception surface of the first conductive element.
    [12" id="c-fr-0012]
    12. The method of claim 11, wherein the dispersion of the LED modules (104) on the reception support (130) is random and comprises a spray projection of the LED modules, or a suspension of the LED modules in a solution then sedimentation of the LED modules on the reception support and removal of the medium from the solution in which the LED modules were dispersed.
    [13" id="c-fr-0013]
    13. The method of claim 11, wherein the transfer of the LED modules (104) is implemented in a pseudo-random manner using a transfer machine capable of simultaneously transferring several LED modules on a part of the reception support.
    [14" id="c-fr-0014]
    14. Method according to one of claims 10 to 13, wherein the production of each of the first and second electric power supply elements (106, 108) comprises the deposition by printing of several conductive tracks extending substantially parallel to each other. others, the conductive tracks of a first of the two electric supply conductive elements extending substantially perpendicular to the conductive tracks of a second of the two electric supply conductive elements.
    [15" id="c-fr-0015]
    15. Method according to one of claims 10 to 14, further comprising, between the transfer of the LED modules (104) and the production of the second electrically conductive element (106), the implementation of the following steps:
    - depositing a photosensitive resin (132) covering the LED modules and the parts of the reception support located on the side of the LED modules and not covered by the LED modules;
    - exposure of the sensitive resin through the reception support which is transparent with respect to the wavelength used for this exposure;
    - Development of the exposed resin such that the remaining exposed parts of the photosensitive resin are kept between the LED modules and form passivation elements between the LED modules.
    [16" id="c-fr-0016]
    16. Method according to one of claims 10 to 15, in which the LED modules are produced such that they each comprise at least one micro-magnet and / or such that the lateral faces of the LED modules are engraved such that, during the dispersion of the LED modules on the reception support, an arrangement of the LED modules such that the emissive face of the LED is arranged on the side of the reception support that is optically transparent is favored.
    [17" id="c-fr-0017]
    17. Display device (100) according to claim 1, in which the LED modules (104) are distributed in a random or quasi-random manner on the reception surface of the first conductive element (108), the device resulting from the implementation of the method according to claim 11.
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    同族专利:
    公开号 | 公开日
    WO2019008262A1|2019-01-10|
    CN110832637A|2020-02-21|
    KR20200026285A|2020-03-10|
    EP3965154A1|2022-03-09|
    EP3649672B1|2022-02-16|
    JP2020525836A|2020-08-27|
    EP3649672A1|2020-05-13|
    FR3068819B1|2019-11-08|
    US20210142716A1|2021-05-13|
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    法律状态:
    2019-01-11| PLSC| Publication of the preliminary search report|Effective date: 20190111 |
    2019-07-31| PLFP| Fee payment|Year of fee payment: 3 |
    2020-07-31| PLFP| Fee payment|Year of fee payment: 4 |
    2021-07-29| PLFP| Fee payment|Year of fee payment: 5 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1756310A|FR3068819B1|2017-07-04|2017-07-04|LED DISPLAY DEVICE|
    FR1756310|2017-07-04|FR1756310A| FR3068819B1|2017-07-04|2017-07-04|LED DISPLAY DEVICE|
    PCT/FR2018/051643| WO2019008262A1|2017-07-04|2018-07-03|Led display device|
    CN201880044671.4A| CN110832637A|2017-07-04|2018-07-03|LED display device|
    JP2019571640A| JP2020525836A|2017-07-04|2018-07-03|LED display device|
    US16/628,223| US20210142716A1|2017-07-04|2018-07-03|Led display device|
    EP21204030.7A| EP3965154A1|2017-07-04|2018-07-03|Display device with leds|
    KR1020207003362A| KR20200026285A|2017-07-04|2018-07-03|LED display device|
    EP18749022.2A| EP3649672B1|2017-07-04|2018-07-03|Led display device|
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