LED display device

Abstract

A display device (100) comprising: a support; -first and second electrically conductive power supply elements (106, 108), the first electrically conductive element being arranged on the support; -a number of LED modules (104), each LED module comprising at least one LED and two power supply pads, respectively arranged on two opposite faces of the LED module, one of the two opposite faces corresponding to the emitting face of the LED, where the power supply pad of each LED module is connected to a first and a second electrically conductive power supply element, respectively, a connection region of a power supply pad of the LED module for connection to the first electrically conductive power supply element is substantially smaller than a receiving region of the first electrically conductive element, which receiving region corresponds to a region of the first electrically conductive element in a plane parallel to the connection region of the power supply pad of the LED module.

Description

[0001] describe

[0002] This application is a divisional application of the Chinese invention patent application with application number 201880044671.4, application date July 3, 2018, and invention name “LED display device”.

[0003] Technical field and prior art

[0004] The field of the invention relates to display or image projection devices. In particular, the invention relates to the realization of screens comprising LEDs or micro-LEDs (μLEDs), preferably made of GaN.

[0005] Most current screens are made with liquid crystals coupled to a backlight and are known as LCD (Liquid Crystal Display) screens. The liquid crystal matrix of such screens is driven by TFTs (Thin Film Transistors).

[0006] Another technology for producing higher efficiency screens is OLED (Organic Light Emitting Diode) technology. The pixel command principle is similar to that used in the case of LCD screens (ie the command circuit is produced using TFT technology).

[0007] Micro-LEDs (or μLEDs) including, for example, structures based on GaN / InGaN can also be used. These μLEDs make it possible to have reduced power consumption compared to LCD and OLED screens (GaN / InGaN μLEDs have an efficiency greater than 60%). These μLEDs are compatible with high current densities, which makes it possible to have typical current densities of 10 6 cd / m 2 High brightness.

[0008] Document FR 3 044 467 describes a method for manufacturing screens by assembling microchips consisting of μLEDs and their command electronics. With this method, it is possible to manufacture the command electronics using bulk technology instead of TFT technology. However, a drawback of this method is that the microchips (each of which comprises four connections) must be transferred very precisely on the interconnection network, which is very complex to perform given the required precision. The duration necessary to perform this transfer is also very important given the number of μLEDs that must be transferred.

[0009] Description of the Invention

[0010] The object of the present invention is to propose a display device whose architecture allows relaxing the constraints concerning the transfer of the LEDs and their positioning relative to the interconnects to which they are connected.

[0011] To this end, a display device is proposed, which at least includes:

[0012] - support member;

[0013] - a first current supply conducting element and a second current supply conducting element, said at least one first conducting element being arranged on a surface of said support;

[0014] - several LED modules, each LED module comprising at least one LED, each LED comprising at least two layers forming a pn junction, and each LED module comprising two supply pads, the two supply pads being arranged respectively on two opposite faces of the LED module, one of the two opposite faces corresponding to the emission face of the LED module,

[0015] The power supply pad of each LED module is respectively connected to the first power supply conductive element and the second power supply conductive element to supply power to the LED module, and

[0016] In which, the connection surface between the power supply pad of the LED module and the first power supply conductive element is significantly smaller than the main surface of the first conductive element, and the main surface corresponds to the following surface of the first conductive element: the surface is in a plane parallel to the connection surface of the power supply pad of the LED module and can produce electrical contact with the power supply pad of the LED module.

[0017] A display device is also provided, which comprises at least:

[0018] - support member;

[0019] - a first current supply conducting element and a second current supply conducting element, said at least one first conducting element being arranged on a surface of said support;

[0020] - a number of LED modules, each LED module comprising at least one LED, each LED comprising at least two layers forming a pn junction, and each LED module comprising two supply pads, the two supply pads being arranged respectively on two opposite faces of the LED module, one of the two opposite faces corresponding to the emission face of the LED module,

[0021] The power supply pad of each LED module is respectively connected to the first power supply conductive element and the second power supply conductive element for supplying power to the LED module, and

[0022] The size ratio between the main surface of the display pixel area and the connection surface between the power supply pad (110) of one of the LED modules and the first conductive element is greater than or equal to 2, wherein one or more LED modules belonging to the display pixel area are intended to generate a light spot display of the display device, and the main surface is formed by the first conductive element.

[0023] In such an arrangement, given the difference in the important dimensions of the body surface compared to the dimensions of the supply pads, it is not necessary to achieve a precise positioning of the LED module on the body surface of the first conductive element. Therefore, different ways of transferring the LED module to the body surface can be envisaged, such as, for example, achieving a random arrangement of the LED modules on the body surface. There is no need to achieve an alignment of the pixel modules relative to the conductive element electrically connected to the LED modules.

[0024] The LED modules may be positioned or transferred onto the main body surface of the first conductive element in an undefined manner. In this context, undefined positioning or transfer means essentially random. Thus, the undefined transfer may result in a variable and thus non-uniform density of the LED modules on the support. Moreover, the density of the LED modules at a given position cannot generally be predetermined in advance and will be determined, for example, by statistical probability laws of the Poisson's law type.

[0025] The LED module can be positioned or transferred onto the main body surface of the first conductive element in an unconstrained or unconstrained manner. Unconstrained or unconstrained positioning or transfer means that the size of the contact surface of the conductive power supply pad of the LED module is smaller than the size of the contact surface of the conductive main body surface of the support on which the LED module is to be transferred, for example, the ratio is at least equal to 2 or at least equal to 5, so that the accuracy of positioning the LED module by this positioning method can have a loose or even very loose accuracy, and the LED module can be positioned at different positions on the main body surface without having to ensure that the pad of the LED module is centered on the conductive main body surface. In this case, the density of the LED modules can be basically uniform for different conductive main body surfaces, but the positioning of the LED on the main body surface may fluctuate, so the positioning on the conductive main body surface can use the term "pseudo-random positioning".

[0026] Furthermore, the orientation of the modules during their transfer may be random or non-random, depending on whether a technique for pre-orienting the LED modules is used before or during the transfer operation onto the support.

[0027] The term LED is used to refer to either LED or μLED.

[0028] In a plane formed at an interface between a main body surface of the first conductive element and a connection surface of a power supply pad of the LED module, a ratio of a size of the main body surface to a size of the connection surface may be greater than or equal to 2 or greater than or equal to 5.

[0029] The main body surface of the first conductive element corresponds to the entire surface of the conductive material of the first conductive element that can be used to make electrical contact with the power supply pad of the LED module. Conductive material that cannot be used to form an electrical connection with the LED module does not form part of the main body surface.

[0030] The LED modules may be distributed on the main surface of the first conductive element in a random or quasi-random manner, and this arrangement can be realized by implementing the method described below.

[0031] The LED modules may be distributed in a random manner such that the density of the LED modules on the surface of the body is non-uniform.

[0032] A size ratio between a main body surface of the first conductive element and a connection surface of a power supply pad of one of the LED modules is greater than or equal to 2, or greater than or equal to 5.

[0033] Each LED module may also comprise a command circuit for an LED in said LED module, the command circuit being capable of outputting a signal representative of a light signal intended to be emitted by the LED on one of said layers of the pn junction of the LED.

[0034] The command circuit may be able to perform a PWM (Pulse Width Modulation) demodulation of an optical signal intended to be transmitted on the powered conducting element, or a demodulation of a binary signal representative of an optical signal intended to be transmitted on the powered conducting element.

[0035] The demodulation can be of PWM or BCM (Binary Code Modulation) type.

[0036] Each of the first power supply conductive element and the second power supply conductive element may include several conductive tracks extending substantially parallel to each other, the conductive tracks of the first power supply conductive element extending substantially perpendicular to the conductive tracks of the second power supply conductive element. In this case, the area corresponding to the overlapping area of ​​one of the conductive tracks of the first conductive element and one of the conductive tracks of the second conductive element may form a display pixel area, in which the LED modules belonging to the display pixel area are intended to generate a light point display of the device and form, for example, a pixel of the display device.

[0037] Each of the first power supply conducting element and the second power supply conducting element may include a single conductive plane or a single conductive layer.

[0038] Each LED module may include two LEDs arranged end to end with each other.

[0039] The display device may further include:

[0040] - a display plane comprising a number of display pixel areas, each display pixel area comprising at least one of the LED modules, and a control device of at least one of the LED modules in said display pixel area being based on a command signal of said display pixel area intended to be received by said control device;

[0041] - an input / output interface of a display device, capable of receiving image signals intended to be displayed on a display surface and comprising at least one command unit intended to output said command signals for said display pixel areas;

[0042] in:

[0043] - the command unit is connected to at least one first antenna capable of transmitting command signals for the display pixel area by means of RF waves;

[0044] - Each control device includes at least one second antenna coupled to the RF signal processing circuit, and each control device is capable of receiving a command signal of an associated display pixel area, and is capable of commanding at least one of the LED modules (104) in the display pixel area to emit a light signal corresponding to a portion of the image signal associated with the display pixel area based on the received command signal.

[0045] In such a display device forming, for example, a μLED screen, the control device for commanding the LED modules is no longer linked in a wired manner to the command unit processing the image signals received by the display device. Such a configuration makes it possible to transmit the power supply signal independently of the command signal of the LED module, which avoids excessive attenuation caused by the transmission of the command signal in a conductive element which may have significant dimensions.

[0046] Furthermore, this architecture provides greater flexibility in the association between the display elements (LED modules and control means) and the signal processing elements upstream of the display (command unit). It is thus possible to easily modify the association of these different elements with each other.

[0047] Even when the LED module does not include a command circuit, the control device can still drive the LED module according to the signal received on the second antenna.

[0048] Each LED module may include a control device, or each display pixel area may include several LED modules and a common control device electrically connected to the LED modules of the display pixel area.

[0049] The second antenna may be arranged in the same plane as one of the two supply conducting elements.

[0050] Each control device may be arranged between two power supply conducting elements and supplied with power by said power supply conducting elements.

[0051] Therefore, it is possible to implement a method for displaying an image on a display device, the method comprising at least:

[0052] - receiving an image signal intended to be displayed on a display plane of a display device;

[0053] - processing the image signal by at least one command unit of the display device to determine command signals of a plurality of display pixel regions of the display device, so that each display pixel region comprises at least one LED module, and the at least one LED module comprises at least one LED,

[0054] - Sending command signals to the display pixel area via RF waves;

[0055] - receiving each command signal by a control device of each display pixel area;

[0056] - The control device commands the LED module of each display pixel area to emit a light signal corresponding to a portion of the image signal associated with the display pixel area according to the received command signal.

[0057] A method for realizing a display device is also proposed, the method at least comprising:

[0058] - manufacturing several LED modules, each LED module comprising at least one LED and at least two supply pads, said at least two supply pads being arranged on two opposite faces of the LED module, one of said two opposite faces corresponding to the emission face of the LED of said LED module;

[0059] - manufacturing a support, on the surface of which at least one first current supplying conducting element is arranged;

[0060] - transferring the LED modules onto the support such that the first current supply conducting element forms at least one body surface for at least a portion of the LED modules, against which one of the current supply pads of each said LED module is arranged to produce an electrical contact, the connection surface of the current supply pad being significantly smaller than said body surface;

[0061] - manufacturing at least one second supply conducting element on the LED module such that the LED module is arranged between said first supply conducting element and said second supply conducting element and two supply pads are connected to the first supply conducting element and the second supply conducting element, respectively.

[0062] A method for manufacturing a display device is also proposed, the method comprising at least:

[0063] - manufacturing several LED modules, each LED module comprising at least one LED and at least two supply pads, said at least two supply pads being arranged on two opposite faces of the LED module, one of said two opposite faces corresponding to the emission face of the LED of said LED module;

[0064] - manufacturing a support, on the surface of which at least one first current supplying conducting element is arranged;

[0065] - transferring the LED module onto the support so that the first power supply conductive element forms at least one main body surface of a display pixel area for at least a part of the LED module, in which one or more LED modules belonging to the display pixel area are intended to generate a light point display of the display device, one of the power supply pads of each of the LED modules is arranged against the at least one main body surface to generate an electrical contact, and the size ratio between the main body surface and the connection surface between the power supply pad of one of the LED modules and the first conductive element is greater than or equal to 2;

[0066] - manufacturing at least one second supply conducting element on the LED module such that the LED module is arranged between said first supply conducting element and said second supply conducting element and two supply pads are connected to the first supply conducting element and the second supply conducting element, respectively.

[0067] During the step of transferring the LED modules, the positioning of the LED modules may be performed in a random or quasi-random manner on the at least one body surface of the first electrically conductive element.

[0068] The dispersal of the LED modules on the support may be random and may include projecting the LED modules by spraying them, or suspending the LED modules in a solution, depositing the LED modules on the support, and removing the solvent of the solution in which the LED modules have been dispersed.

[0069] In an alternative, the transferred LED modules can be manufactured in a pseudo-random manner using a transfer machine capable of transferring several LED modules simultaneously onto a portion of the support.

[0070] Manufacturing each of the first and second current supply conducting elements may comprise depositing by printing several conductive traces extending substantially parallel to each other, the conductive traces of a first of the two current supply conducting elements extending substantially perpendicularly to the conductive traces of a second of the two current supply conducting elements.

[0071] The method may further include, between transferring the LED module and manufacturing the second power supply conductive element, performing the following steps:

[0072] - depositing a photosensitive resin, the photosensitive resin covering the LED module and a portion of the support member that is located on one side of the LED module and not covered by the LED module;

[0073] - exposing the photosensitive resin through said support, said support being transparent with respect to the wavelength used for said exposure;

[0074] - developing the exposed resin so that the remaining exposed portions of the photosensitive resin remain between the LED modules and form a passivation element between the LED modules.

[0075] The LED modules can be manufactured so that each of them includes at least one micromagnet and / or so that the side surfaces of the LED modules are etched so that during the scattering of these LED modules on the support, the LED modules are arranged so that the emission surface of the LED is arranged on the preferably optically transparent side of the support.

[0076] BRIEF DESCRIPTION OF THE DRAWINGS

[0077] The invention will be better understood by reading the description of exemplary embodiments, which are provided purely for the purpose of illustration and not limiting in any way, with reference to the accompanying drawings, in which:

[0078] - Figure 1 schematically shows a part of a display device (subject of the present invention) according to a first embodiment;

[0079] - Figure 2 Schematically shows an LED module of a display device according to the present invention;

[0080] - FIG. 3A to FIG. 7B The steps of the method for manufacturing a display device according to the present invention are shown;

[0081] - Figure 8 An example of a μLED of a display device according to the present invention is shown;

[0082] - Fig. 9 schematically shows an LED module comprising two LEDs mounted end to end;

[0083] - Fig.10 A method for manufacturing an LED module is shown;

[0084] - Fig.11 Schematically shows the electronic command circuit of the LED module;

[0085] - Fig.12 The steps of a method for manufacturing an LED module having a predetermined orientation are shown;

[0086] - Fig.13A and Fig. 13B Schematically illustrates an LED module with a predetermined orientation;

[0087] - Fig.14 An alternative way of transferring LED modules is shown;

[0088] - Fig.15 and Fig.16 shows a simulation curve of random scattering of LED modules;

[0089] - Fig.17 and Fig.19 A diagram showing an exemplary embodiment of an electronic command circuit for an LED module;

[0090] - Fig.18 shows the signal obtained by the LED module during the display period;

[0091] - Fig. 20 A display device is schematically shown, comprising zones differentiated by colors to be displayed;

[0092] - Fig.21 schematically illustrates a portion of a display device in which LED modules communicate via RF signals;

[0093] - Fig. 22 and Fig.23 schematically illustrates an LED module communicating via RF signals;

[0094] - Fig.24 Schematically illustrates the elements within the display device that perform signal transmission via RF waves;

[0095] - Fig.25 schematically shows a portion of a display device according to another embodiment;

[0096] - Fig.26A and Fig.26B A diagram showing an RF antenna used in a display device;

[0097] - Fig. 27 schematically shows a portion of a display device according to another embodiment;

[0098] - Fig.28 A diagram showing a method for displaying an image according to certain embodiments is shown.

[0099] The same, similar or equivalent parts in the different figures described below have the same reference numbers to facilitate easier connection from one figure to the next.

[0100] In order to make the drawings easier to understand, different parts of the drawings are not necessarily shown to a uniform scale.

[0101] The different possibilities (alternatives and embodiments) are to be understood as not being mutually exclusive and can be combined.

[0102] Detailed description of specific embodiments

[0103] A display device is proposed herein, which is manufactured by transferring LEDs in an indeterminate, random or pseudo-random manner onto a transfer support (e.g., a plate containing a TFT assembly or an unfunctionalized support plate). The transfer support comprises at least one conductive trace, which corresponds, for example, to a future row or column of a future matrix.

[0104] First reference Figure 1 , which schematically shows a display device 100 according to a first embodiment.

[0105] The device 100 forms a matrix of n×m display pixel areas 102. The display pixel area 102 corresponds to an area of ​​the display plane of the device 100, which is intended for displaying a point image that is commanded separately relative to other image points of the display plane. Each display pixel area 102 includes one or more LED modules 104 that ensure light emission of the display pixel area 102 (however, a defective display pixel area may not include an LED module, as described below). All LED modules 104 present in the same display pixel area operate simultaneously to display the corresponding image point. In the first embodiment described herein, each display pixel area 102 corresponds to a pixel of the display plane. Figure 1 In , only a part of the pixel matrix is ​​shown and corresponds to a set of 36 pixels distributed over 6 rows and 6 columns of pixels.

[0106] The LED modules 104 each include an LED 105 and an electronic command circuit 118. The LED 105 is made, for example, of at least one inorganic semiconductor, preferably GaN and / or InGaN and / or AlGaN. Figure 2 As can be seen in FIG, each LED module 104 comprises, on one side, an LED 105 and, on the other side, an electronic command circuit 118. In the case of micro LED modules, the dimensions of each LED module 104 in a plane parallel to the interface between the electronic command circuit 118 and the LED 105 are, for example, comprised between about 1 μm and 100 μm, or between about 5 μm and 100 μm, depending mainly on the volume of the electronic command circuit 118, which depends on the complexity of this electronic command circuit 118, i.e. the number and type of functions implemented by this circuit 118. The thickness of each LED module 104 is, for example, between about 2 μm and 10 μm.

[0107] The LEDs 105 may emit light of variable color, or alternatively monochromatic light. When monochromatic LEDs 105 are used, different LEDs 105 emitting red, green and blue (and optionally white) light are preferably transferred so that there is at least one LED 105 of each of these colors in each pixel (except in defective display pixel areas 102).

[0108] The LED modules 104 are herein distributed in a random manner within the display pixel regions 102 of the device 100. The density at which the LED modules 104 are distributed is such that, statistically, except for a limited number of regions 102, each display pixel region 102 includes at least one LED module 104. However, each region 102 may include several LED modules 104.

[0109] Each LED module 104 includes two power supply pads 110, 112 connected to the power supply conductive elements 106, 108 of the device 100. Figure 2 As can be seen in FIG. 1 , the LED 105 of each LED module 104 and the electronic command circuit 118 of each LED module 104 are connected to one of the conductive elements 108 via the soldering pad 110 and to one of the conductive elements 106 via the soldering pad 112. The conductive element 108 is optically transparent or translucent so as to enable the LED 105 to emit light.

[0110] exist Figure 1 In the embodiment, the conductive element 106 is arranged along a first direction (in Figure 1 The conductive elements 108 are formed in the form of conductive rows extending in a second direction substantially perpendicular to the first direction (in the horizontal direction). Figure 1 The conductive column is formed by extending in the vertical direction (in the middle).

[0111] For example, the name V 供电 A supply potential is intended to be applied to the conductive element 106 and is designated V 接地 A reference potential (eg ground) is intended to be applied to the conductive element 108. Within each zone 102, each of the LED modules 104 is therefore connected to the supply potential and the reference potential.

[0112] Thus, a screen is proposed herein that is manufactured by transfer of LEDs, for example transferred in an indeterminate manner onto a transfer support. As in the case of the first embodiment described above, the transfer support may correspond to a plate on which one of the conductive elements 106, 108 is formed in rows or columns. The transfer support may also correspond to a TFT plate including electronic command elements.

[0113] This particular transfer of the LED modules 104 is possible due to the difference in an important dimension of the body surface or contact surface of the LED modules 104, namely the dimensions of the conductive elements 108 compared to the dimensions of the LED modules and more specifically to the dimensions of the conductive pads present on each LED module and intended to allow the supply of power to the LED modules. In fact, it is not necessary to achieve a precise positioning of the LED modules 104 on these body surfaces, given that the dimensions of these conductive elements are indeed much larger than the dimensions of the LED modules 104, and the same is true of the supply pads 110, 112 relative to the contact surface of the conductive elements 108. These dimensions are such that, in a plane parallel to the contact surface, the ratio of the dimensions of one of the contact surfaces on the support to the dimensions of one of the two opposite faces of one of the LED modules is greater than or equal to 2, or greater than or equal to 5, or even greater than or equal to 10. The contact surface on the support corresponds to a surface that can be used to make electrical contact with one of the LED modules 104, which surface can optionally be partially perforated or consist of different surfaces that are electrically connected and at the same electrical potential.

[0114] Combination FIG. 3A to FIG. 7B The steps of a method for manufacturing the device 100 are described.

[0115] First, the first electrode layer is fabricated ( Figure 3A and Figure 3B ). In the example described herein, they are conductive elements 108 intended to be located on one side of the emitting face of the LED 105. A transparent support 130, for example made of glass, is used. Next, ITO strips are etched at a pitch corresponding to the desired pitch of the display pixel area 102, preferably by laser etching the inter-strip areas from a continuous plane or continuous layer of ITO. These ITO strips form the conductive elements 108.

[0116] Ideally, the LED modules 104 are suspended in the water-IPA mixture and kept suspended by ultrasonic agitation. Advantageously, the apparatus may be of the type used for liquid crystal screens for randomly interspersing the spacers.

[0117] Next, the LED modules 104 are randomly scattered, for example by spraying, to minimize the number of defective areas 102 on the conductive element 108 ( Figure 4A and Figure 4B ). For 1.10 6 The screen with 102 pixels or areas is allocated with 1.10 7 A solution of the order of magnitude of 10 LED modules 104 must be provided, which must ensure a defect level of the order of magnitude of 10. Direct metal-to-metal bonding may be performed to ensure the connection of the LED module 104 to the conductive element 108.

[0118] The negative type insulating resin 132 is preferably distributed over the entire structure achieved by spraying, and its thickness is preferably greater than the thickness of the LED module 104 ( Figure 5 ). Advantageously, the resin is black in order to obtain a good contrast with the LED 105 during light emission, in case the emission of ambient light is not zero, and to have a black display plane when the LED 105 is not emitting light.

[0119] Exposure through the transparent support 130 and the conductive element 108 makes it possible to expose the resin 132 between the LED modules 104 without exposing the resin present on the LED modules 104. Next, development of the resin 132 makes it possible to remove the unexposed resin present on the LED modules 104 ( Figure 6 ). The rest of the resin ensures passivation between the LED modules 104 .

[0120] Finally, the other conductive elements 106 are produced, for example, by printing metal electrodes (perpendicular to the previous electrodes). The resin 132 deposited in the previous step then ensures a smoothing effect, thus facilitating the deposition of the conductive elements 106 by printing.

[0121] In this random scattering process of LED modules 104, the distribution follows Poisson's law. Assume that the number of display pixel regions 102 is 1.10 6 , and using Poisson's law, it is possible to evaluate the number of LED modules 104 that must be allocated based on the number of defects accepted by the device 100. A defect is a display pixel area 102 that has no LED module 104 or no functional LED module 104. Fig.15 In the diagram shown in , considering the case of one million display pixel areas 102, it is necessary to distribute on the support an order of magnitude of 14 million LED modules 104 in order to have only a single defective display pixel area 102 (so that the average number of LED modules 104 per pixel area is 14). By interspersing 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 located in one display pixel area 102, based on the number of defects accepted. Therefore, in Fig.16 By accepting a single defective display pixel region 102 , it is possible to find a display pixel region 102 including 35 LED modules 104 .

[0122] In the method described below, the LED modules 104 are distributed on the support 130 and the conductive element 108 due to the dispersion achieved by spraying. In an alternative, the LED modules 104 can be placed in a liquid to obtain a colloidal suspension of the LED modules 104. This suspension is distributed on the support 130 and the conductive element 108, and then, the LED modules 104 are arranged on the conductive element 108 by depositing and then aspirating the solvent in which the LED modules 104 are located.

[0123] The LED 105 of the LED module 104 is, for example, Figure 8 . The LED 105 comprises an n-doped semiconductor layer 134, which is arranged against a p-doped semiconductor layer 136, this stack forms a pn junction arranged between two conductive layers 138 (transparent to enable light emission of the LED 105) comprising, for example, ITO. The semiconductor layers 134, 136 are, for example, GaN. The layer 138 facilitates contact with the conductive elements 106, 108.

[0124] By distributing the LED modules 104 on the support in a random manner, some of these LED modules 104 are not arranged in a correct manner, i.e., include their emitting face which is not on the right side of the display plane. However, considering the huge number of scattered LED modules 104, a sufficient number of correctly oriented LED modules 104 is statistically obtained. The reversed LED modules 104 do not constitute an electrical problem, because when powered on, these LED modules 104 form reverse biased diodes without interfering with the operation of other correctly oriented LED modules 104. When each LED module 104 includes a command circuit 118 of CMOS type, the CMOS architecture of this circuit 118 is such that reverse biasing does not produce a short circuit.

[0125] In the above described embodiment, the interspersed LED module 104 includes the LED 105 and the command circuit 118. In an alternative, the LED module 105 may not include the command circuit 118, but may include one or more LEDs 105 singly.

[0126] Preferably, each LED module 104 may include two LEDs 105 arranged end to end. Fig. 9 , where on a first side, the first LED 105a includes an n-doped layer 134a, and the second LED 105b includes a p-doped layer 136b, and on a second side opposite to the first side, the first LED 105a includes a p-doped layer 136a, and the second LED 105b includes an n-doped layer 134b. Therefore, no matter which side (the first side or the second side) is in contact with one of the conductive elements 108, one of the LEDs 105 will function.

[0127] Combination Fig.10 An example of a method for manufacturing LED module 104 is described.

[0128] In step a) of the figure, a matrix of electronic command circuits 118 is manufactured in a semiconductor substrate 142 , for example silicon, using CMOS technology.

[0129] In parallel with the manufacture of the matrix of electronic command circuits 118 , the matrix of LEDs 105 is manufactured from another semiconductor substrate 144 , for example by epitaxy (step b)).

[0130] Next, the matrix of electronic command circuits 118 is transferred onto the matrix of LEDs 105. During this assembly, the contact pick-ups between the electronic command circuits 118 and the LEDs 105 are made. Next the semiconductor of the substrate 142 is thinned and then the pads 112 are made on one side of the command circuits 118. The growth substrate 144 is then removed (step c)).

[0131] The LED modules 104 are then etched and singulated (step d)). The LED modules 104 can then be arranged in a solution.

[0132] exist Fig.11 An exemplary embodiment of an electronic command circuit 118 is shown in FIG. 1 . The 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 comprises a portion CMOS 148, which is not described in detail herein and is used to process data signals intended to be received by the LED module 104 and to drive the transistor T to power the LED 105. This portion 148 may correspond to a simple CMOS transistor when the circuit 118 performs no other functions than powering the LED 105. This portion 148 is connected to a second contact 150, for example of ITO, intended to be connected to the conductive element 108 and located on one side of the emission face of the LED 105. The contact 150 is connected to the component 148 by a conductive via 152, which is electrically isolated relative to the semiconductor layers 134 and 136 of the LED 105.

[0133] During the interspersing of the LED modules 104, it is preferred to facilitate the positioning of the LED modules 104 in a suitable direction, i.e. to orient the LED modules 104 so that the emission surfaces of the maximum number of LEDs 105 are turned towards the display surface of the device 100. Therefore, it is necessary to use a technique for pre-orienting the LED modules before / during their transfer to the support.

[0134] A first solution to facilitate this correct orientation may be to incorporate micro-magnets within the LED modules 104. These micro-magnets may be used to subsequently assemble the LED modules 104 on the correct side during random placement of the LED modules 104. For example, by repeating the previously incorporated Fig.10 The method described, at the end of step c), a dielectric 152 such as SiO2 is deposited on the face including the pad 112. The temporary treatment 151 is manufactured integrally with the LED 105, and the bonding of the temporary treatment 151 can be performed before the substrate 142 is thinned. Next, the planarization of the dielectric 152 is achieved, and the micromagnets 154 are then arranged on the planarized dielectric, distributed so that at least one micromagnet distribution 154 is associated with each LED module 104 (see Fig.12 , step a). The micromagnet 154 is covered with a dielectric layer 156, which has, for example, the same properties as the dielectric 152, and then the contact pick-up portion of the pad 112 is manufactured through the dielectric layer 156 and the dielectric 152 through a conductive via 158, which is formed, for example, by a damascene method ( Fig.12 , step b). Next, the stacking is performed by etching to singulate the LED modules 104, and the temporary processing portion 151 is removed ( Fig.12 , step c)). Thus, the inlay method makes it possible to prepare a surface compatible with direct bonding. By thus integrating the micromagnets 154 in the LED modules 104, the positioning of these LED modules 104 is influenced, since the micromagnets 154 are attracted on the side of the conductive element 106, thereby facilitating the correct positioning of the emission surface of the LED 105.

[0135] Other configurations of the LED modules 104 may facilitate the proper orientation of these modules. For example, to avoid positioning the LED modules 104 so that one of the sides is disposed on the side of the conductive element 108, it is possible to position the LED modules 104 in a manner such as to Fig.13A and Fig. 13BThe LED module 104 is etched in the shape shown in , i.e., including a portion etched at the side. The upper surface of the LED module 104 includes a contact 110, around which the etching of the insulator is partially performed so that the contact protrudes. In this way, after being interspersed by the spraying method described previously, only the surface at the bottom of the LED module 104 will have sufficient adhesion (via van der Waals forces) to withstand washing (possibly assisted by a small amount of HP). The LED modules 104 that are not adhered to the conductive element 108 are recovered. In this configuration, it is wise to intersperse a plurality of LED modules 104, the number of which is at least 6 times greater than the number of LED modules 104 predicted by Poisson's law. The individual interspersions of the LED modules 104 are very interesting because the partial uncertainty is increased because these clusters that cannot attach themselves due to the shape of the LED modules 104 will be cleared from the areas that are over-clustered as the clusters of LED modules 104 are formed.

[0136] exist Fig.14 Another way of interspersing or arranging the LED modules 104 on the surface of the body formed by the conductive element is shown in FIG.

[0137] The LED module 104 is transferred to the temporary processing part 160 so that the emitting surface is placed against the processing part 160 ( Fig.14 , step a)). Next, the assembly is turned over ( Fig.14 , step b)), and remove a portion of the LED modules 104 onto the conductive element 108 ( Fig.14 , step c)). Given that the size of the conductive element 108 is larger than the size of the LED module 104, the positioning constraints are relaxed. The temporary treatment portion can also take the form of a flexible substrate that can be stretched before turning over. In this case, the positioning of the LED module on the main body surface of the conductive element 108 will vary from display device to display device, so the positioning of the LED module on the main body surface under consideration is pseudo-random.

[0138] In the examples described above, the interspersion of the LED modules 104 is performed in an indeterminate manner in terms of positioning the LED modules, and when a technique for pre-orienting the LED modules is implemented, it is possible to perform in a non-random manner in terms of orienting the LED modules. However, the fact of having a body surface with dimensions much larger than the dimensions of the transferred LED modules also makes it possible to implement a determined transfer solution, for example via a machine that transfers the LED modules 104 onto the body surface, while relaxing the imposed alignment constraints due to these dimensions. It is therefore possible to work with a larger transfer surface than when the LED modules have to be transferred onto electrical contacts having dimensions similar to those of the pads of the LED modules. For example, it is possible to work with a transfer machine having a transfer element (called a "stamp") having dimensions of 5 cm×5 cm in order to transfer the LED modules 104 with a pitch of 250 μm, i.e., to transfer 50,000 LED modules 104 at the same time. The positioning of the transfer element relative to the surface of the body does not need to be precise (+ / - 10 μm may be sufficient), which makes it possible to increase the transfer speed and thus reduce the costs of the method.

[0139] The transfer efficiency is not 100%. In order to ensure that there is at least one LED module 104 (or even 3 modules if it is desired to have multiple monochrome LED modules 104 with three colors per pixel area), it is necessary to create redundancy in each display pixel area. Assuming a transfer efficiency of 99%, if the number of transfers is doubled, 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 efficiency is independent from one transfer to another. If there are defects locally in the transfer element, there is a dependency from one transfer to another, and in this case, doubling the transfer steps can only reproduce the defects (the same overall efficiency is obtained after the transfer element passes for the second time). In order to offset potential defects locally related to the reference point of the transfer element, the transfer redundancy step can be completed in the following way: Nx, Ny display pixel areas are shifted (Nx represents the number of pixel areas in the row, and Ny represents the number of pixel areas in the column) so that the fixed defects of the transfer element are spatially distributed on the support.

[0140] If further redundancy is needed to obtain better overall efficiency, the transfer element can be shifted for each pass over the same body area. 6 If the transfer efficiency is 96%, then 4 passes are sufficient. In general, the different passes can be shifted by several pixels.

[0141] In the previously described device 100, the LED module 104 comprises its power supply pads 110, 112, which are connected to the power supply conductive elements 106, 108, on which the supply voltage is applied to power the LED module 104. The only contact pads of the LED module 104 are the power supply pads 110, 112, and the data signals enabling the driving and commanding of the LED module 104 must be transmitted to the LED module, rather than through a dedicated wire connection. Thus, in this example, the command signals are transmitted to the LED module 104 through these power supply pads 110, 112 and these conductive elements 106, 108 in the form of a modulated signal that the LED module 104 must interpret.

[0142] Other ways of transmitting the command signals to the LEDs can be envisaged, such as by RF (or even infrared) means.

[0143] Fig.17 A block diagram is shown of the functions implemented in the electronic command circuit 118 of each LED module 104, which are used to implement commands of the LEDs 105 in the module by PWM (Pulse Width Modulation) or BCM (Binary Code Modulation) based on data and synchronization signals transmitted by amplitude modulation of the supply voltage present on the supply conductors 106, 108.

[0144] This block diagram describes an architecture suitable for an LED module 104 with 3 channels (RGB), which makes it possible to perform addressing and writing functions of binary data. Thus, the LED module includes 3 LEDs and their corresponding command switches, similar to Fig.11 The example shown in .

[0145] When powered on, the block PoR (power-on reset) 170 initializes a first decoder 172 named decoder_1, which at a given moment points to one of the three channels (for example, to channel R (red)), and also initializes the RGB data in the three latch-type storage elements Latch_R, Latch_G and Latch_B, for example, with "0".

[0146] The demodulators 174, 176 each receive a supply signal coming from the conductive elements 106, 108, which supply signals include data and synchronization signals obtained by amplitude modulation of the "POWER" and "GROUND" supply voltages, respectively. The data signal is named "POWER+DATA_PULSE" and the synchronization signal is named "GROUND+CLK_PULSE". These demodulators 174, 176 make it possible to extract the variations in the power and ground voltages in order to reconstruct the binary signals (named DATA_PULSE and CLK_PULSE).

[0147] The signal DATA_PULSE is sent to the input of a second decoder 178, which outputs a data signal DATA which ultimately implements the command of the LED 105. The signal DATA is stored in one of three storage elements 180.1, 180.2, 180.3 for the three RGB channels, depending on the signals VALID_R, VALID_G, VALID_B from the decoder 172. The assembly is synchronized by the decoder 172, which changes the channel selected on each pulse of the clock signal CLK_PULSE by sending the signals VALID_R, VALID_G, VALID_B to the storage elements 180.1, 180.2 and 180.3.

[0148] Fig.18 An example of a timing diagram of the signals obtained in this circuit is shown. Sending 2 pulses on CLK_PULSE makes it possible on the one hand to increase the selection of the RGB channels and then to define a time window during which one can wait to see if a DATA_PULSE pulse is received. If so, a 1 is written, for example, in the storage element corresponding to the selected channel (R, V or B), and a 0 is written if not.

[0149] In this example, the value stored in each latch-type storage point (used to store a single binary value) is used to directly control the command switch of LED 105 in an "all or nothing" mode (the LED is in a conductive or non-conductive state, because it is connected or not connected to the supply voltage, respectively).

[0150] The conducting time and the non-conducting time need to be driven in order to be able to control the light intensity of the LED 105. Therefore, the value present in each storage point must be modified during each image frame.

[0151] PWM (Pulse Width Modulation) or BCM addressing makes it possible to modulate the average brightness emitted by the LED 105 by modulating the on time of the LED 105 by writing only 1s and 0s: 1=ON, 0=OFF. If the LED 105 is on for the entire image time, this corresponds to the maximum code, for example on 3 bits: 111. On the other hand, if the LED 105 is off for the entire image time, this corresponds to the minimum code: 000.

[0152] In this example with 3 addressing bits, the ON or OFF duration associated with the most significant bit (the third bit) corresponds to four times the ON or OFF duration associated with the least significant bit (the first bit), and the ON or OFF duration associated with the second bit corresponds to twice the ON or OFF duration associated with the least significant bit. The ON or OFF duration can be encoded by selecting a value between 0 and 7.

[0153] In this context, the brightness emitted by the LED is controlled during the display of each image by the ratio of the duration of the command LED to be turned on to the total display time of the image on the screen. This command of the LED can be obtained using a binary word or information of the BCM type (i.e., a binary code on a certain number of bits that makes it possible to control the display of the image), in which the brightness of each pixel is encoded in the form of a binary signal. Each bit of this binary word drives the LED to turn on or off for a duration proportional to the effective value of the bit. For example, the most significant bit (MSB) drives the LED during half the display duration of the image (e.g., 10ms for a display device running at a frequency of 50 images / second). The next bit (named MSB-1) represents a quarter of this duration, and so on, until the LSB (least significant bit).

[0154] In a matrix display device (such as a combination of Figure 1 In the case of a matrix display device as described above, it can be arranged that each row of pixels is addressed three times during a frame at reduced time intervals. The duration of the first time interval is thus four times longer than the third time interval, and the duration of the second time interval is twice longer than the third time interval. The values ​​stored in the "latch" storage point during the first, second and third time intervals correspond to the first (most significant bit), the second and the third (least significant bit), respectively.

[0155] In the case of a module comprising 3 LEDs, it is necessary to carry out 3 information transfers for the 3 channels each time a row is addressed (the values ​​are stored in the corresponding storage points Latch_R, Latch_G and Latch_B). It is thus possible to envisage the successive addressing of the 3 channels of a pixel module by sending 6 pulses on CLK_PULSE and applying or not applying 3 pulses of DATA_PULSE according to the code to be applied.

[0156] This protocol offers the advantage of having a very compact architecture, which is extremely advantageous since it makes it possible to manufacture LED modules 104 having small dimensions.

[0157] In this protocol, a demodulation error may lead to an error in channel selection or an error in writing data. If the data is wrong, the result will be limited by a one-time shutdown, whereas an error in the detection of CLK_PULSE will lead to an error in the time window and an error in the addressing channel. In this case, reinitialization must be performed by power-on reset.

[0158] In order to improve the robustness of the circuit 118, it is possible to place a binary decoder at the output of the demodulators 174, 176 to ensure that the R, G or B channel is addressed individually, rather than using a tracker (cyclic sequencer) to address it. However, this requires more surface and requires more data to be transmitted (with complex labels making it possible to know which channel is addressed).

[0159] exist Fig.19 The implementation is shown in Fig.17 A block diagram of an exemplary embodiment of the functionality of circuitry 118 is provided.

[0160] Other embodiments of the electronic control circuit present in the LED module can be envisaged. For example, each single-bit storage element (latch) can be replaced by a storage element of the register type with several bits, so as to store in each register a numerical value corresponding to the desired light intensity (for example, to store the numerical value on 3 bits as previously described). In this case, it is not necessary to provide 3 row addressing during the frame, but a single row addressing makes it possible to transmit a value with 3 bits. Thereafter, it will be necessary to add a command circuit between each register and the command switch of the corresponding LED, for converting the binary value into a time command signal for the LED. The advantage of such an alternative embodiment is that it makes it possible to envisage updating the register value only when it is desired to modify the light intensity, thereby making it possible to reduce energy consumption. Moreover, in connection with the device for identifying LED modules as described below, architectures other than matrix architectures can be envisaged.

[0161] After manufacturing the device 100 and before using it, when the LED modules 102 are already randomly distributed on the support, the number of LED modules 104 in each display pixel area 102 is unknown, and a first calibration phase makes it possible to determine the number of LED modules 104 by reading the consumption when the LEDs 105 of the display pixel areas 102 are switched on. Knowing the number, the display code will be adapted in an inversely proportional manner to achieve the initial desired brightness.

[0162] Other methods for calibrating the display device 100 are also possible, such as, for example, current adjustment or voltage adjustment for a display pixel region 102 containing n LED modules 104. Visual inspection to determine the position, color and number of LED modules 104 in each display pixel region 102 is also conceivable.

[0163] Because of this calibration, each display pixel region 102 operates in the same manner regardless of the number of LED modules 102 in each region 102 .

[0164] In an alternative, the calibration may be performed via identification of the LED module 104. The communication process using the identification of the LED module may be accomplished in different ways, by wired or wireless means (eg, RF communication).

[0165] Before using the communication method using module identification, each LED module must receive an identifier. This "personalization" of each LED module can be achieved by operating on hardware components: i.e. by flashing a ROM, by blowing fuses to assign a code to each LED module 104, or can be performed by programming the LED modules 104.

[0166] In the communication process using identification, statistical characteristics can also be used to identify the LED module 104 without having a unique identification code. This makes it possible to reduce the number of identification bits to be stored and greatly reduces the complexity of the LED module 104.

[0167] To this end, "n" LED modules 104 with different identification codes are manufactured and randomly distributed to manufacture the device 100. Each display pixel area 102 has one or more LED modules 104, whose addresses are among "n". During communication with the LED modules 104 in the display pixel area 102, an inventory of these LED modules 104 is performed in the following manner: scan n address codes so that the number of LED modules in the display pixel area 102 is known and the addresses of the LED modules that have been restored to existence are identified. Therefore, it is possible to turn off redundant LED modules 104 and only keep one active LED module 104 for each display pixel area. In this way, no adjustments (voltage / current / binary code) are required to have a uniform display on the entire display, because there is only a single LED module 104 for each display pixel area 102.

[0168] Software can be used to perform this identification. Thus, it is possible to communicate with the display pixel area 102 in a manner where a computer on the Internet sends a request and obtains a unique address on the network. This requires communication protocols, digital electronic components and memory.

[0169] The advantage of the individual addressing of the LED modules 104 is that it is possible to change the way writing is done in the display device 100. In fact, instead of scanning all the rows in sequence while having to refresh the data present on the column buses in order to display an image, if the pixels have a specific address, it is possible to address only those that have changed from one image to the next, which makes it possible to obtain a very low consumption of the device 100.

[0170] The identification by address (individually or not) provides the possibility of disabling certain LED modules 104, which makes it possible to use redundancy. In the case that a certain LED module 104 fails or is too scattered, it is possible to disable the LED module and select another LED module (if there is one LED module) located in the same display pixel area 102.

[0171] In the previously described exemplary embodiment, the command electronics of the LED 105 are integrated in the LED module 104. As an alternative or as a supplement, it is possible that the electronic command circuit is present under a support of the device 100 connected to the LED module 104, for example made using CMOS technology. In this case, it is the bare LED that is transferred.

[0172] The support can be constructed according to different zones, each zone intended to receive an LED module 104 suitable for emitting a single color, namely red, green or blue. This relaxes the constraints on the deposition of the LED modules 104, since it is possible to deposit the LED modules 104 associated with each of these colors by means of a silk screen stencil, and makes it possible to keep the traditional display architecture of the polysilicon type by bonding large-surface MOS-type TFT command electronics on the back side of the support. Fig. 20 Schematically shown is a configuration in which body areas 182 differentiated for different colors are produced for arranging the LED modules 104. The command electronics present on the back are referenced 184.

[0173] As an alternative to TFT technology for manufacturing the command electronics 184 , it is possible to use a glass plate and bond a MOS control module against this plate for addressing the display pixel areas 102 .

[0174] After the RGB modules have been deposited, it is possible to communicate with the desired module or to apply a certain configuration (e.g. by a laser blowing a fuse) to force one of these modules to display only one of the desired colors. This, combined with the structuring of the power supply conductive elements, makes it possible to have a display device 100 that has a large surface and that can be reconfigured on a large TFT type technology surface when only a single type of RGB modules is manufactured / deposited.

[0175] The controller can manage the power supply signals, currents or voltages of several display pixel areas, each of which realizes RGB light emission. The controller can receive its data through wiring or RF link and distribute the information according to the display pixel area. This solution provides the following advantages: having a CMOS controller that is very small compared to the surface occupied by the controlled display pixel area.

[0176] Various embodiments of the display device 100 will now be described in which the LED modules 104 communicate via RF signals.

[0177] First reference Fig.21 , which schematically shows a portion of such a display device 100 .

[0178] The device 100 comprises a display plane on which one or more images are displayed. The display plane is divided into a number of display pixel areas 102 which are controlled independently of each other.

[0179] Each display pixel region 102 includes one or more LED modules 104. Each LED module 104 includes at least one LED 105, which is a μLED in this context. The LEDs 105 each include a pn junction formed by a GaN layer and / or an InGaN layer and / or an AlGaN layer.

[0180] The LED module 104 is inserted between two power supply conductive elements 106, 108 (at Fig.21 1 to 106.6 and 108.1 to 108.8), and each LED module 104 comprises two supply pads 110, 112, which are arranged at two opposite faces 114, 116 of the LED module 104, one of which corresponds to the emission face of the LED 105 of the LED module 104, and the two supply pads 110, 112 are respectively connected to one and the other of the two supply conductive elements 106, 108 on which a supply potential (in this example, the supply potential is applied to the element 106) and a reference potential (in this example, the reference potential is applied to the element 108). Fig. 22 Such a configuration can be seen for one of the LED modules 104 in FIG. 104. In this example, the emission face of the LED 105 corresponds to the face 114 which is located on the side of the conductive element 108.

[0181] As an example, the conductive element 108 disposed against the emitting surface of the LED 105 may include a transparent conductive material such as ITO.

[0182] exist Fig.21 , the power supply conductors 106, 108 are implemented in the form of conductive tracks arranged perpendicular to each other. In the embodiment described herein, each intersection of one of the conductive elements 106 arranged in a row and one of the conductive elements 108 arranged in a column defines a display pixel area. Thus, the layout forms a matrix of display pixel areas 102. Furthermore, by commanding the LED modules 104 so that the LED modules 104 in each area 102 form the same signal, that is, so that they display light signals forming the same image point, each pixel area 102 corresponds to a pixel of the display plane of the device 100.

[0183] Here, each LED module 104 also comprises a command circuit 118. This command circuit 118 comprises electronic components making it possible to command the light emission by the LED 105 of the module 104, while outputting to the LED 105 a signal representative of the light signal to be emitted.

[0184] exist Fig.23An exemplary embodiment of such a command circuit 118 is schematically shown in FIG. This circuit 116 comprises a first transistor T1 for commanding the LED 105 to be turned on or off, a transistor T2 which makes it possible to inject a desired current into the LED 105, and a storage capacitor C which makes it possible to maintain a desired voltage at the gate of the transistor T2. The voltage Vdd coming from the conductive element 106 is applied to the drain of the transistor T2 via a supply pad 112 of the LED module 104 in contact with the conductive element 106. The current output by the transistor T2 is applied to one layer of the pn junction of the LED 105. The other layer of the pn junction of the LED 105 is subjected to the potential transmitted by the conductive element 108 via the supply pad 110.

[0185] The command signal is transmitted from the control means 120 to the command circuit 118. In this embodiment, each LED module 104 comprises a control means 120 intended to control the light signal intended to be emitted by this LED module 104. The control means 120 may comprise electronic circuits such as memories, a decoder for received messages, a unit for sequencing commands to be applied by the command circuit 118, etc. Advantageously, the control means 120 are powered via the connections to the conductive elements 106 and 108.

[0186] Next, the device 100 comprises an input / output interface capable of receiving at input an image signal S intended to be displayed by the device 100. 图像 The input / output interface includes Fig.24 One or more command units 122 shown in FIG. 1 , which are based on the image signal S 图像 Or according to the signal S 图像 The command signal to be sent to different display pixel areas 102 is determined by a part of the display pixel area 102, so that the LED 105 emits a signal together with the image signal S 图像 The corresponding optical signal.

[0187] Unlike conventional screens in which these command signals are transmitted by wired connections from a screen element that receives image signals for display on the screen all the way to the command circuit for each pixel, these command units 122 or each command unit 122 of the device 100 transmit command signals for the display pixel area 102 wirelessly by RF waves via at least one first antenna 124 to the control device 120. These command signals are received by second antennas 126, each of which is coupled to one of the control devices 120. Therefore, in the embodiment described herein, due to the fact that each LED module 104 is provided with its own control device 120, each LED module 104 comprises an antenna 126 which makes it possible to receive command signals which will make it possible to obtain the desired light emission of the LEDs 105 of this LED module 104 after processing by an RF signal processing circuit included in the control device 120 (see Fig.24 ).

[0188] In general, the command signal propagated by the RF device may include different types of information, for example, an identifier of the control device 120 of the accessed address or the desired brightness level of the display pixel area 102 of the accessed address. The command signal may also include a time sequence of the desired brightness level. The information transmitted by the RF device may be optionally encoded. If necessary, the control device 120 of the accessed address may decode the information and then drive the command circuit to obtain the desired brightness level or the desired sequence. Information about the desired brightness level may be stored in the memory of the control device 120, and the information may be uniquely updated, for example, when the desired brightness value needs to be changed.

[0189] Despite Fig.24 1 shows a single antenna 124, but it is possible to have several command units 122, each connected to an antenna 124 and intended to transmit by RF command signals of only a portion of the display pixel area of ​​the device 100. For example, it is possible to have several command units 122, each connected to a different antenna 124, these command units and these antennas 124 being spaced apart by a distance equal to about 300 μm, wherein each of these command units 122 and these antennas 124 can manage the RF transmission of the device 100 in an area forming a square with dimensions of 300 μm x 300 μm.

[0190] In the above-described embodiment, each display pixel region 102 includes an LED module 104, which includes, for example, a single-color LED 105. In an alternative solution, the LED module 104 may include three LEDs of red / green / blue, such as RGB.

[0191] In the alternative, each display pixel region 102 may include several LED modules 104 intended to display the same light signal.

[0192] In an alternative, each display pixel region may include several single-color LED modules 104, and for example at least three LED modules 104 capable of emitting the colors red, green, and blue, respectively. In this case, the light signal emitted by each of the different colored single-color diodes may be defined according to the same command signal (which may require the same current level in all LEDs, or require different current levels in the LEDs) or according to different command signals for each LED color in the display pixel region.

[0193] In the embodiments described above, each of the LED modules 104 includes a control device 120 coupled to an antenna 126 .

[0194] According to another embodiment, each control device 120 and each antenna 126 may be associated with several LED modules 104. Fig.25 In FIG. 1 , a display pixel area 102 of the device 100 is shown. The area includes several LED modules 104, which are coupled in a wired manner (wires indicated by 128) to a control device 120 common to these different modules 104. A command unit 122 associated with the area 102 sends different command signals for these LED modules 104 to the control device 120 via RF transmission, and the control device 120 then transmits the command signals to the modules 104 via a wired connection.

[0195] exist Fig.25 In the example shown in , the control device is arranged between the electrically conductive elements 106 , 108 like the LED module 104 .

[0196] This further embodiment is used, for example, when the density of the LED modules 104 does not allow each LED module 104 to have its own antenna 126 , in particular taking into account the size of these antennas 126 imposed by the characteristics of the transmitted signal.

[0197] Furthermore, the control device 120 may drive the LED module 104 according to the signal received on the second antenna even when the LED module does not include a command circuit.

[0198] In the above described embodiments, the antenna 126 may be arranged in the same plane as one of the two conductive elements 106, 108 (in the previously described exemplary embodiments, in the same plane as the conductive element 106). In this case, the antenna 126 may be in the form of a planar antenna or an open-hole "patch" ( Fig.26A) or in spaced rows (in Fig.26B ) implementation as shown in the example.

[0199] according to Fig. 27 In another embodiment shown in , it is also possible to have the following control devices 120, which are not arranged in the display plane together with the LED modules 104, but are arranged behind the display plane. In this case, they are arranged behind the display plane via a wired link between these control devices 120 and the LED modules 104.

[0200] According to an alternative embodiment, it is possible that the LED module 104 is not powered via the conductive elements 106 , 108 , but is powered remotely using, for example, RFID or NFC type communication.

[0201] In the previously described exemplary embodiments, the conductive elements 106, 108 each correspond to several conductive traces extending in different directions. In an alternative, it is possible that the conductive elements 106, 108 each correspond to a conductive plane common to all LED modules 104 or to a subassembly of LED modules 104 of the device 100.

[0202] The RF communications previously described may invoke an identification code associated with each LED module 104 or with a group of LED modules 104 (eg, those LED modules 104 in the same display pixel region 102).

[0203] Fig.28 , a flow chart of the organizational structure of the display method implemented by the device 100 is shown.

[0204] In step 200, an image signal intended to be displayed on a display plane of the device 100 is received by the device 100 via its input / output interface.

[0205] At step 202 , the received image signal is processed by the command unit 122 , which determines command signals to be sent to different display pixel regions 102 of the device 100 .

[0206] In step 204 , the command signal calculated by the command unit 122 is transmitted to the display pixel area 102 via the antenna 124 by means of RF waves.

[0207] At step 206 , the command signal is received via the antenna 126 by the control device 120 present in each display pixel region 102 addressed by the command unit 122 .

[0208] At step 208 , the control device 120 commands the LED modules 104 to display light signals corresponding to the command signals that have been transmitted to these LED modules.

[0209] Other embodiments of the invention may be envisaged by a person skilled in the art. Among other things, although the previously described embodiments comprise LED modules each arranged between two electrically conductive supply elements, it is entirely possible to envisage a display device in which the two electrically conductive elements are positioned on the same substrate on the same side of the LED module (an exemplary embodiment of such a display device is described in French patent application FR 3044467A1).

Claims

1. A display device (100), comprising at least: - a support member (130); - a first current supply conducting element (108) and a second current supply conducting element (106), the at least one first current supply conducting element (108) being arranged on a surface of the support (130); - a plurality of 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 supply pads (110, 112), the two supply pads being arranged on two opposite faces of the LED module, one of the two opposite faces corresponding to the emission face of the LED of the LED module, The power supply pad of each LED module is respectively connected to the first power supply conductive element and the second power supply conductive element to supply power to the LED module, and wherein a ratio of a size of a main body surface of a display pixel region to a connection surface between a power supply pad (110) of one of the LED modules and the first power supply conductive element is greater than or equal to 2, wherein one or more LED modules belonging to the display pixel region are intended to generate a light point display of the display device, and the main body surface is formed by the first power supply conductive element, Each LED module (104) includes two LEDs which are arranged end to end.

2. The display device (100) according to claim 1, wherein: The LED modules (104) are distributed in a random manner such that the density of the LED modules on the surface of the body is non-uniform.

3. The display device (100) according to claim 1 or 2, wherein: Each LED module (104) further comprises a command circuit (118) for the LED (105) of the LED module (104), the command circuit (118) being capable of outputting a signal on one of the layers of the pn junction of the LED (105), the signal being representative of a light signal intended to be emitted by the LED (105).

4. The display device (100) according to claim 3, wherein: The command circuit (118) is capable of performing a demodulation of a binary signal representative of an optical signal intended to be transmitted on the powered conducting element.

5. The display device (100) according to claim 4, wherein: The demodulation is of PWM or BCM type.

6. The display device (100) according to claim 1 or 2, wherein: Each of the first power supply conducting element (108) and the second power supply conducting element (106) comprises a number of conductive traces extending substantially parallel to each other, the conductive traces of the first power supply conducting element extending substantially perpendicular to the conductive traces of the second power supply conducting element.

7. The display device (100) according to claim 1 or 2, wherein: Each of the first power supply conducting element (108) and the second power supply conducting element (106) includes a single conductive layer.

8. The display device (100) according to claim 1 or 2, further comprising: - a display plane comprising a plurality of display pixel areas (102), each display pixel area (102) comprising at least one LED module (104) of the LED modules (104), and a control device (120) of the at least one LED module (104) of the LED modules (104) in the display pixel area (102) being based on a command signal of the display pixel area (102) intended to be received by the control device (120); - an input / output interface of the display device (100), the input / output interface being capable of receiving image signals intended to be displayed on the display plane and comprising at least one command unit (122) intended to output the command signals of the display pixel area (102); in: - the command unit (122) is connected to at least one first antenna (124), the first antenna (124) being capable of transmitting the command signal of the display pixel area (102) by means of RF waves; - Each control device (120) includes at least one second antenna (126), the second antenna (126) is coupled to the RF signal processing circuit, and each control device (120) is capable of receiving a command signal of the associated display pixel area (102), and is capable of commanding at least one of the LED modules (104) in the display pixel area (102) to emit a light signal corresponding to a portion of the image signal associated with the display pixel area (102) based on the received command signal.

9. A method for manufacturing a display device (100), the method comprising at least: - manufacturing a plurality of LED modules (104), each LED module (104) comprising at least one LED (105) and at least two supply pads (110, 112), the at least two supply pads (110, 112) being arranged on two opposite faces of the LED module, one of the two opposite faces corresponding to the emission face of the LED of the LED module, wherein each LED module (104) comprises two LEDs arranged end to end with each other; - manufacturing a support (130) on the surface of which at least one first current supplying conductive element (108) is arranged; - transferring the LED module onto the support, so that the first power supply conductive element forms at least one main body surface of a display pixel area for at least a part of the LED module, in which one or more LED modules belonging to the display pixel area are intended to generate a light point display of the display device, one of the power supply pads of each of the LED modules is arranged against the at least one main body surface to generate electrical contact, and the ratio of the size between the main body surface and the connection surface between the power supply pad (110) of one of the LED modules and the first power supply conductive element (108) is greater than or equal to 2; - manufacturing at least one second supply conducting element on the LED module such that the LED module is arranged between the first and second supply conducting element and the two supply pads are connected to the first and second supply conducting element, respectively.

10. The method according to claim 9, wherein: During the step of transferring the LED modules, the positioning of the LED modules is performed in a random or quasi-random manner on the at least one body surface of the first current supply conducting element.

11. The method according to claim 10, wherein: The scattering of the LED modules (104) on the main support (130) is random and includes: projecting by spraying the LED modules, or suspending the LED modules in a solution and then depositing the LED modules on the main support, and removing the solvent of the solution in which the LED modules have been scattered.

12. The method according to claim 10, wherein: Transferring the LED modules is accomplished in a pseudo-random manner using a transfer machine that is capable of transferring several LED modules simultaneously onto a portion of the body support.

13. The method according to any one of claims 9 to 12, wherein: Manufacturing each of the first (108) and second (106) current supply conducting elements comprises depositing by printing a number of conductive traces extending substantially parallel to each other, the conductive traces of a first of the two current supply conducting elements extending substantially perpendicularly to the conductive traces of a second of the two current supply conducting elements.

14. The method according to any one of claims 9 to 12, further comprising: Between transferring the LED module (104) and manufacturing the second power supply conductive element (106), the following steps are implemented: - depositing a photosensitive resin (132), the photosensitive resin covering the LED module and a portion of the main support member located on one side of the LED module and not covered by the LED module; - exposing the photosensitive resin through the body support, the body support being transparent with respect to the wavelength used for the exposure; - developing the exposed resin so that the remaining exposed portions of the photosensitive resin remain between the LED modules and form a passivation element between the LED modules.

15. The method according to any one of claims 9 to 12, wherein: The LED modules are manufactured so that each of them includes at least one micromagnet and / or so that the sides of the LED modules are etched so that during the scattering of the LED modules on the main body support, the LED modules are arranged so that the emission surface of the LED is arranged on the preferably optically transparent side of the main body support.

16. The display device (100) according to claim 1, wherein: The LED modules (104) are distributed on the main surface of the first power supply conductive element (108) in a random or quasi-random manner, and the device is realized by implementing the method according to claim 11.

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