Luminous module for a motor-vehicle signalling device

Abstract

The invention relates to a luminous module (1, 10, 100) for a motor-vehicle signalling device, comprising a plurality of selectively controllable light sources (2), characterized in that the set of light sources (2) is mounted on the same common support (3) and in that it comprises a grid (4) overmoulded on a substrate formed by the common support (3) or extending from the common support (3), the grid (4) being formed from an opaque material and extending over the substrate between each pair of light sources (2), forming a wall (41) separating neighbouring light sources (2), such that each light source (2) emits a light beam into a cell (6) of this grid (4).

Description

LIGHT MODULE FOR A SIGNALING DEVICE OF A MOTOR VEHICLE

[0001] The invention relates to the field of automotive lighting and light signaling. More specifically, the invention relates to the field of screens integrated into light modules for lighting or light signaling of motor vehicles.

[0002] In the field of automotive signaling, it is known to integrate screens into light modules of motor vehicles, such as rear lights, which can be produced using matrices comprising a significant number of light sources.

[0003] The plurality of light sources is generally selectively controllable and comprises sufficiently small dimensions to be able to display information on said screens, which may be in the form of a message or even a pictogram, with an acceptable resolution.

[0004] The information provided by the screens makes it possible to improve the signaling of the motor vehicle, by contextualizing or even accompanying a given signaling function with a message.

[0005] In order to obtain a homogeneous screen appearance, and in particular to avoid perceiving pixels clearly separated from each other (dotted effect whereby the shape of the light sources is perceptible or in English "dotty effect"), it is known to reduce the dimension of the light sources and the pitch separating two neighboring light sources (also called "pitch"). Beyond the increase in screen resolution which is thus generated, it is therefore possible to reduce the width of the area separating two neighboring pixels. Although this area appears dark, it becomes imperceptible as its width decreases.

[0006] However, it is not possible to reduce the separation pitch below a certain threshold, except by significantly increasing the cost and complexity of producing the screen.

[0007] In this context, in order to maintain good resolution and a uniform lit appearance of the screen, without a "dotty effect", it is also known to add to the screen an element diffusing the light emitted by each light source to form pixels of dimensions larger than those of the light sources, which then makes it possible to reduce the width of the area separating two neighboring pixels. The diffusion must also be such that the luminance within each pixel is uniform, and that the sharpness and contrast qualities of the screen are respected.

[0008] However, reducing the pitch between neighboring light sources combined with diffusion of the light emitted by the light sources can create parasitic effects between the different light sources, particularly neighboring light sources. Indeed, the light emitted by a light source can, if the pitch separating them is reduced, spill over onto the pixel produced by a neighboring light source.

[0009] This effect, also called "cross-talk," results in a reduced screen resolution. Pixels generated by neighboring light sources partially overlap, making it impossible to manage these pixels independently of each other.

[0010] In order to meet these different constraints, it is known to equip the screen with a grid whose walls define cells each containing a light source. It is thus possible to reduce the pitch between the light sources, to preserve the diffusing element and to avoid cross-talk, the light emitted by a light source remaining confined by the walls of the cell containing this light source so that it does not overflow onto a neighboring pixel.

[0011] However, the question of the design and assembly of the screen arises. Indeed, the reduction in the dimensions of the light sources and the pitch separating two neighboring light sources makes the assembly of the grid with the matrix of light sources complex. Indeed, taking into account the manufacturing tolerances of the grid and this matrix of light sources as well as the phenomena of differential expansion depending on the temperature, it is possible that certain light sources end up at the level of a wall of the grid, or even outside the cells for which they are intended, during the assembly of the matrix and the grid to form the screen.

[0012] Thus, there is also a need to provide a light module for a motor vehicle, intended to form a screen having good resolution, without a "cross-talk" effect, and a homogeneous lit appearance, without a "dotty effect", and which can be assembled without generating a defect despite the reduction in the dimensions of the light sources and the pitch separating two neighboring light sources.

[0013] The present invention is placed in this context and aims to meet this need.

[0014] For these purposes, the invention relates to a light module of a signaling device of a motor vehicle, comprising a plurality of light sources which can be selectively controlled.

[0015] According to the invention, all of the light sources are mounted on the same common support and the light module comprises a grid overmolded on a substrate formed by the common support or extending from the common support, the grid being formed in an opaque material and extending on the substrate between each pair of light sources forming a wall separating the neighboring light sources, so that each light source emits a light beam in a cell of this grid.

[0016] The invention thus proposes to overmold a grid directly onto the support of the light sources or onto a substrate extending from this common support. In accordance with the solutions presented in the preamble, the fact that each light source is arranged in a cell of this grid makes it possible to create an enclosure in which the light emitted by said light sources is contained, or even reflected, in order to reduce the cross-talk phenomenon. It is thus possible to reduce the dimensions of the light sources as well as the spacing separating two neighboring light sources, while using an element to diffuse the light emitted by each light source, in order to avoid a "dotty effect".Furthermore, since the grid is produced by overmolding, it is thus freed from the constraints of positioning the grid in relation to the matrix of light sources during assembly, which could be generated by a variation in the dimensions of the grid due to manufacturing tolerances or a phenomenon of thermal expansion.

[0017] Preferably, in the invention, the common support is a printed circuit board, also called PCB for “Printed Circuit Board”, on which all of the light sources are directly mounted.

[0018] The printed circuit board, or PCB, has a first side and a second side opposite the first side. The light sources are mounted on the first side of the PCB, which faces the outside of the signaling device in which the light module is integrated.

[0019] In a preferred embodiment, the light sources can be arranged on the common support so as to be spaced apart from each other by a distance of less than 5 micrometers, in particular greater than 1 micrometer.

[0020] Here, the term "distance between two light sources" means the distance separating one edge of a light source from the other edge facing it of another light source.

[0021] Preferably, the light module is arranged so that the fill factor of the pixels of the screen, also called in English "fill factor" is greater than 50%, preferably greater than 70%, or even greater than 80%. The term "fill factor" means the ratio between the surface area of ​​the pixel for which the luminance is greater than a given percentage, in particular 10%, of the maximum luminance of the pixel and the total surface area of ​​the pixel.

[0022] In the invention, the light sources may be light-emitting semiconductor chips. The semiconductor may be a gallium nitride, or GaN, capable of emitting, by electroluminescence and in response to an electric current passing through it, rays of blue light. The photoluminescent element may, for example, be in the form of a resin comprising a cerium-doped yttrium aluminum garnet, or CE:YAG, capable of absorbing blue light and, by photoluminescence and in response to the excitation produced by this light, emitting rays of yellow or white light. The photoluminescent element is arranged on the generator so that a portion of the blue light rays excites this element so that it emits, by photoluminescence, rays of yellow or white light. The other portion of the blue light rays passes through this element.Thus, the light source simultaneously emits, when electrically powered, rays of wavelength in the blue and yellow or white spectrum, the light thus formed appearing white to the human eye.

[0023] In a particular embodiment, the substrate is formed by the common support on which all of the light sources are mounted, the grid being overmolded directly onto the common support.

[0024] In a preferred embodiment of the invention, the light module comprises at least one electronic component mounted on the common support, said at least one electronic component being encapsulated in a wall of the grid.

[0025] Thus, encapsulating electronic components arranged on the common support by grid overmolding makes it possible to protect said electronic components in order to reduce their risk of detachment from the common support and to avoid their exposure to chemical attack. In addition, this characteristic makes it possible to clear the area in which these electronic components are usually arranged, so as to be able to use the space thus available for other purposes or to reduce the size of the light module. Finally, this characteristic improves the off appearance of the screen since these electronic components are hidden in the walls.

[0026] In another embodiment, the substrate is formed by a first layer of transparent material encapsulating all of the light sources arranged on the common support, and the light module comprises at least one electronic component encapsulated in the first layer of transparent material.

[0027] Advantageously, the substrate is formed by a first layer of transparent material encapsulating all of the light sources arranged on the common support, so that each wall of the grid has a part immersed in the first layer of transparent material.

[0028] Advantageously, the first layer of transparent material extends above the upper surfaces of the light sources and grooves are formed between each pair of light sources, each wall of the grid being overmolded in one of said grooves to extend above the upper surface of said first layer of transparent material.

[0029] In a preferred embodiment, the first layer of transparent material is a transparent silicone resin, or transparent silicone.

[0030] Preferably, the first layer of transparent material has a thickness of less than 10 millimeters, or even 5 millimeters.

[0031] Advantageously, the first layer of transparent material encapsulating the light sources has, at the level of each light source, a curved light beam exit surface forming an optical component of the light module.

[0032] Thus, the presence at each light source of a curved light beam exit surface improves the sharpness of the light beam emitted by each of the light sources.

[0033] Preferably, the optical component of the light module may be in the form of a lens or a collimator.

[0034] In a particular embodiment of the invention, the first layer of transparent material encapsulating the light sources has, at the level of each light source, a light beam exit surface provided with diffusing optical structures.

[0035] Preferably, the diffusing optical structures may be in the form of particular patterns or even Fresnel structures.

[0036] Advantageously, the light module comprises at least one electronic component mounted on the common support, said at least one electronic component being encapsulated in the first layer of transparent material.

[0037] In one embodiment according to the invention, the walls of the grid are made of white material.

[0038] The white material may be a dielectric material, having a reflection coefficient of between 60 and 99%, in particular substantially equal to 90%. It may, for example, be a silicone resin enriched with titanium dioxide (TiO2). Where appropriate, each wall made of the white material may have a thickness of at most 100 µm.

[0039] Thus, these walls allow on the one hand to intercept light emitted by the light source and which would be likely to reach another light source of the light module. Due to their white color, this light is reflected in the enclosure defined by the first walls and in which the light source is located.

[0040] These walls therefore significantly reduce the effects of interference or cross-talk and increase the efficiency of the light module. It is therefore possible to reduce the dimensions of the light sources without impacting the screen resolution. In addition, the edges, or thicknesses, of these white walls contribute to the visible appearance of the light module when switched off and therefore reduce the influence of the color of the photoluminescent element on this appearance when switched off.

[0041] In a preferred embodiment, the walls of the grid are made of dark colored material.

[0042] Given its opacity and color, it thus makes it possible to further limit the effects of interference or cross-talk which could remain, despite the presence of the white walls, to improve the unlit appearance of the light module.

[0043] Advantageously, the dark-colored material may be black or gray and have a mass transmission coefficient of between 50% and 95% over a thickness of 1 millimeter. It may, for example, be a polymer, in particular an epoxy resin or a silicone, enriched with carbon particles or black pigments.

[0044] For example, it may be possible to consider that the concentration of carbon particles, namely the mass of carbon relative to the mass of the polymer, is less than 0.05%. This characteristic is particularly suitable when the light module is intended to perform a regulatory signaling function. Otherwise, it may be possible to consider that the concentration of carbon particles is greater than 0.05%, in particular in order to improve the contrast and the off-light appearance of the screen.

[0045] Advantageously, the light module comprises a second layer of transparent material arranged between each wall of the grid, extending from the substrate over at least the height of the walls of the grid.

[0046] In a preferred embodiment, the second layer of transparent material forms an exit surface of the light module and has, at each light source, an exit surface for the light beam provided with diffusing optical structures.

[0047] Preferably, the light module comprises an additional diffusing layer mounted extending above the grid. Provision may be made for said additional diffusing layer to be present whether the first layer of transparent material is overmolded on the common support or on a substrate extending on this common support and whether it is supported directly by the grid and / or by the second layer of diffusing material.

[0048] In a particular embodiment, the additional diffusing layer comprises a thickness substantially less than the thickness of the layer of transparent material.

[0049] Preferably, the additional diffusing layer is made of a diffusing material and / or comprising diffusing optical structures, which can be, for example, bonded to the layer of transparent material.

[0050] Thus, in another embodiment, the layer of transparent material comprises, for example, at its upper surface a plurality of diffusing optical structures.

[0051] Advantageously, the light module has a first protective layer arranged between certain pairs of light sources and having a first albedo and has a second protective layer arranged between other pairs of light sources and having a second albedo greater than the first albedo, the second layer defining a logo.

[0052] In a particular embodiment, the first protective layer is formed by molding onto the grid and the second protective layer, on only certain light sources, is formed by molding onto the grid and the first protective layer.

[0053] Thus, the second protective layer is superimposed on the first protective layer by molding, and is in such a way as to form a particular pattern which can form a logo.

[0054] In the invention, albedo means the reflective power of a surface, also called reflectance, expressed in the form of a percentage reflecting the ratio between the luminous flux reflected from an incident luminous flux, and this incident luminous flux. In the remainder of the description, albedo will be understood to mean a diffuse albedo or a diffuse reflectance.

[0055] In the invention, the term logo means any form recognizable by an observer as such, and in particular a form consisting of one of the following elements or a combination of several of the following elements: a geometric figure, an alphanumeric character, a pattern, a pictorial representation of a living being.

[0056] It should be noted that a major part of the visible surface of a light screen is formed not by the light sources but by the substrate of these light sources. This substrate is usually provided with a protective layer, of low albedo, which extends between the light sources, and thus contributes significantly to the black extinguished appearance of the screen. Consequently, a second protective layer is added to a part of this first protective layer, of higher albedo, and therefore capable of diffusing ambient light, an urban lighting beam or a light beam emitted by another vehicle, incident on the light screen to a greater extent than the first layer.

[0057] It is thus understood that it is possible to materialize, using this second layer of protection, a logo on the luminous screen, day and night, without it being necessary to power the screen. It should be noted that it is possible to use particularly simple manufacturing processes to produce this second layer of protection.

[0058] Advantageously, the first protective layer may have a first albedo of a value substantially less than 20%, in particular 15%, while the second protective layer may have a second albedo greater than 50%, in particular 60%. Alternatively, the light device may comprise a protective glass arranged at the level of the light screen and provided, on one of its faces, with an anti-reflective coating. Where appropriate, the first protective layer may have a first albedo of a value substantially less than 15%, in particular 10%, while the second protective layer may have a second albedo greater than 20%, in particular 30%.The use of such protective glass makes it possible to increase the contrast between the first layer and the second layer or to maintain an identical contrast between these two layers, so as to be able to reduce the difference in albedo, which makes it possible, among other things, to reduce the cost of producing the lighting device.

[0059] In a preferred embodiment, each of the light sources comprises at least one light-emitting semiconductor chip having dimensions between 100 micrometers and 400 micrometers.

[0060] Such a chip is known as a mini-LED. If necessary, the light sources can be arranged on the same common support so that the distance between the centers of two neighboring sources is less than 1 millimeter.

[0061] In a particular embodiment, each of the light sources comprises at least one light-emitting semiconductor chip whose dimensions are between 5 micrometers and 150 micrometers.

[0062] Such a chip is known as a microLED. If necessary, the light sources can be arranged on the same common support so that the distance between the centers of two neighboring sources is between 200 and 400 µm, or even less than or equal to 300 µm.

[0063] Preferably, the light module comprises a connector for receiving a control instruction from said plurality of light sources and at least one controller capable of selectively controlling light sources, wherein the plurality of light sources forms a passive matrix and wherein the controller is arranged to control said passive matrix as a function of the control instruction received by the connector.

[0064] Advantageously, the light module comprises a connector for receiving a control instruction from said plurality of light sources and at least one controller capable of selectively controlling light sources. Where appropriate, the plurality of light sources forms a passive matrix and the controller is arranged to control said passive matrix as a function of the control instruction received by the connector. For example, the light module may comprise a plurality of devices for controlling the electrical power supplied to the light sources, each control device being mounted on a first face of the printed circuit board, in line with a light source, to control the electrical power supplied to the light source, in particular as a function of an instruction received from the controller intended for it.

[0065] Advantageously, the light module comprises at least 500 light sources, in particular distributed in a matrix manner, the controller being arranged to selectively control each of these light sources.

[0066] Advantageously, the light module comprises an interconnection system connected to the controller and arranged to interconnect the controller to the plurality of light sources. The interconnection system may be integrated into the printed circuit board or be an independent element mounted on this printed circuit board. The interconnection system may comprise a matrix of connectors, such as a ball grid array (BGA) or a pad matrix (LGA).

[0067] The plurality of light sources forms a passive matrix where each row and each column of light sources is associated with a control device mounted on the PCB at the right of this row or this column to control the electrical power supplied to the light sources of this row or this column. The controller is thus arranged to control each of the sources of said passive matrix according to the control instruction received by the connector, by successively scanning the rows then the columns of the matrix to control the electrical power supplied to each of the light sources.

[0068] In a particular embodiment, the walls of the grid are arranged so that each cell has the shape of a cone section.

[0069] The walls of the grid then have a specific, slanted shape, making it easier to demould said walls of the grid, always with a view to facilitating the production of such a light module according to the invention. In particular, the walls of the grid are arranged so as to have a rectangular shape in section through a plane perpendicular to the common support.

[0070] The invention also relates to a signaling device for a motor vehicle, characterized in that it comprises a light module according to the invention, said plurality of light sources forming a light screen of said signaling device.

[0071] The invention also relates to a method of manufacturing a light module according to the invention, the method comprising the following steps:

[0072] Assembly of a plurality of light sources on the same common support;

[0073] Overmolding an opaque material onto the common support to form the grid, said grid being arranged between each pair of light sources.

[0074] In another embodiment, the manufacturing method comprises the following steps:

[0075] Assembly of a plurality of light sources on the same common support;

[0076] Depositing a first layer of transparent material on the common support to encapsulate said plurality of light sources;

[0077] Cutting said layer of transparent material to form a plurality of grooves, each groove extending between a pair of neighboring light sources;

[0078] Overmolding in each groove of an opaque material to form the grid in the grooves.

[0079] Preferably, the manufacturing method also comprises a step of molding the second layer of transparent material between each wall of the grid.

[0080] In a particular embodiment, a step of depositing an additional diffusing layer above the grid.

[0081] In a preferred embodiment, the additional diffusing layer is a diffusing film bonded to the upper surfaces of the walls of the grid and / or the second layer of transparent material.

[0082] The present invention is now described using examples which are purely illustrative and in no way limitative of the scope of the invention, and from the appended drawings, drawings in which the various figures represent:

[0083] represents, schematically and partially, a front view of a light module according to one embodiment of the invention;

[0084] represents, schematically and partially, a sectional view of the light module of the;

[0085] represents, schematically and partially, a side view of a light module according to another embodiment;

[0086] represents, schematically and partially, a side view of a light module according to yet another embodiment.

[0087] In the following description, elements which are identical, by structure or by function, appearing in different figures retain, unless otherwise specified, the same references.

[0088] A front view of a light module 1 according to an embodiment of the invention and a sectional view of the light module 1 have been described. In the example described, this light module 1 is intended to be integrated into a front or rear light of a motor vehicle, the light module 1 forming a screen.

[0089] The light module 1 comprises a plurality of light sources 2 mounted on the same common support 3, formed in the example described by a printed circuit board.

[0090] In the example described, the light module 1 comprises more than 20,000 light sources 2, arranged so as to create a passive matrix, on 256 columns and 80 rows. The light sources 2 are mini-LEDs, the dimensions of which are between 100 µm and 400 µm. The light sources 2 are separated from each other by a center-to-center distance less than or equal to 1 millimeter. It should be noted that other dimensions of the light sources 2, other distances between the light sources 2, other numbers of light sources 2 or even other distributions of the light sources 2 could be envisaged, without departing from the scope of the present invention.

[0091] Each light source 2 comprises a light-emitting semiconductor chip 2a, forming an elementary light generator. The semiconductor may for example be a gallium nitride, or GaN, capable of emitting, by electroluminescence and in response to an electric current passing through it, rays of blue light, for example whose spectrum has a peak centered on a wavelength between 410 nm and 480 nm. Each light source 2 also comprises a photoluminescent element 2b encapsulating the chip 2a. This photoluminescent element may for example be in the form of a resin comprising a cerium-doped yttrium aluminum garnet, or CE:YAG, capable of absorbing blue light and, by photoluminescence and in response to the excitation produced by this light, of emitting rays of yellow or white light.

[0092] The printed circuit board, or PCB, 3 has a first face 31 and a second face 32 opposite the first face 31. The light sources 2 are mounted on the first face 31 of the PCB, which faces the outside of the signaling device in which the light module 1 is integrated.

[0093] It should be noted that, in the example described, the printed circuit board is a so-called multi-layer PCB, comprising a stack of layers, between the first and second faces. These layers are in particular intended for the interconnection of the components mounted on the PCB, and may each comprise a plurality of through-vias, blind or buried, arranged in the PCB to be connected to the different interconnection layers. These vias open onto the first face or the second face of the PCB at the level of metal pads to which they are connected.

[0094] As illustrated in, all of the light sources 2 are encapsulated in a layer of transparent material 5. In the example described, the layer of transparent material 5 is formed by a transparent silicone resin, deposited on the PCB 3 to a thickness of less than 10 millimeters. Provision may be made for the layer of transparent material 5 to also encapsulate other electronic components of the light module 1, mounted on the first face 31.

[0095] Furthermore, the layer of transparent material 5 encapsulating the light sources 2 has, at the level of each light source 2, an exit surface 7 of the light beam of curved shape forming an optical component of the light module 1.

[0096] This layer of material 5, taking into account the material used and its structure, in particular the curved shapes 7, thus participates in the diffusion of the light rays emitted by the light sources 2 to form pixels of dimensions significantly larger than those of these light sources 2. Combined with a reduction in the pitch p separating two neighboring light sources 2, this layer makes it possible to increase the fill factor of the pixels formed by the light sources 2. It is thus possible to avoid a dotted appearance, or “dotty effect” of the screen formed by the module 1 when it is lit, the width of the zone separating two neighboring pixels being significantly reduced.

[0097] Alternatively, it could be provided that the first layer of transparent material 5 has, at the level of each light source, an output surface provided with diffusing optical structures, such as Fresnel structures.

[0098] In the embodiment described, the layer of transparent material 5 forms a substrate on which a grid 4 is produced.

[0099] The grid 4 comprises a plurality of walls 41, arranged in a matrix manner to define cells 6 each containing a light source 2. Each wall 41 is overmolded in a groove 51 previously made in an upper surface of the layer of transparent material 5, so that it has a part immersed in this layer of transparent material 5 and extends over a height of approximately 1 mm above this layer 5.

[0100] Furthermore, and in order to facilitate the demolding of the grid 4 on the layer of transparent material 5, the walls 41 of the grid 4 are arranged so that each cell 6 has the shape of a cone section narrowing towards this layer of transparent material 5. It can be observed in particular that the walls 41 of the grid 4 are arranged so as to have a rectangular shape in section in a plane perpendicular to the common support 3.

[0101] Thus, said grid 4 extends from the layer of transparent material between each pair of light sources 2, each light source 2 thus emitting a light beam into a cell 6 of this grid 4.

[0102] The grid is made of an opaque material, dark in color, for example black or gray, with a transmission coefficient of between 50% and 95%, over a thickness of 1 millimeter. It could, for example, be a polymer, in particular a silicone enriched with carbon particles, the concentration of carbon particles being less than 0.05%.

[0103] Each wall 41 of a cell 6 thus makes it possible to intercept light rays emitted by the light source 2 contained in this cell and which would be directed towards an adjacent cell 6 to come and superimpose themselves on the light rays emitted by the light source 2 contained in this adjacent cell. By intercepting these parasitic rays, the walls 41 thus reduce a “cross-talk” effect and thus contribute to improving the resolution, sharpness and contrast of the screen formed by the light module 1.

[0104] In addition, the light module 1 comprises an additional diffusing layer 12 extending above the grid 4. This additional layer makes it possible to further reinforce the homogeneity of the lit appearance of the screen.

[0105] Advantageously, the light module 1 comprises a connector (not shown) for receiving a control instruction from said plurality of light sources 2 and at least one controller (not shown) capable of selectively controlling light sources 2. Where appropriate, the plurality of light sources 2 forms a passive matrix and the controller is arranged to control said passive matrix as a function of the control instruction received by the connector. For example, the light module 1 may comprise a plurality of devices for controlling the electrical power supplied to the light sources 2, each control device being mounted on the first face 31 of the printed circuit board 3, in line with a light source, being encapsulated in the layer 5, to control the electrical power supplied to the light source, in particular as a function of an instruction received from the controller intended for it.

[0106] It could be envisaged that a single controller controls all of the light sources 2 mounted on the PCB or that a plurality of controllers could be provided, each selectively controlling a matrix, for example 64x64, or 4096, light sources 2.

[0107] The instruction may, for example, be an instruction issued by a computer of the motor vehicle or the signaling device for the display of a logo, a message, a pattern or a pictogram.

[0108] As another example, this could be an instruction to display a pictogram intended to inform an outside observer of the opening of a door of the motor vehicle, a pictogram intended to inform a motorist following the motor vehicle of the presence of black ice on the road or information relating to motor traffic.

[0109] The plurality of light sources 2 therefore forms a passive matrix where each row and each column of light sources 2 are associated with a control device (not shown) mounted on the PCB at the right of this row or this column to control the electrical power supplied to the light sources 2 of this row or this column. The controller is thus arranged to control each of the sources of said passive matrix according to the control instruction received by the connector, by successively scanning the rows then the columns of the matrix to control the electrical power supplied to each of the light sources 2.

[0110] An example of a method for manufacturing a light module 1 according to the embodiment of the set will now be described.

[0111] In a first step, a plurality of light sources 2 is assembled on the same PCB 3. A layer of transparent material 5, such as a transparent silicone resin, is deposited on the common support 3 to encapsulate said plurality of light sources 2. Said layer 5 can be molded to form the curved shapes of the surface 7.

[0112] In a second step, grooves 51 are dug by means of a blade in the layer of transparent material 5, each groove extending between a pair of neighboring light sources 2.

[0113] In a third step, walls 41 are overmolded in each of the grooves 51 of the layer of transparent material 5 so as to form a grid 4 defining cells each containing a light source 2.

[0114] The grid 4 being produced by overmolding, it is thus possible to overcome the constraints of positioning the grid 4 relative to the matrix of light sources 2 compared to a method of assembling a pre-designed grid with a matrix of light sources 2, in which positioning defects of certain walls 41 with respect to the sources 2 could be induced by a variation in the dimensions of the grid due to manufacturing tolerances or to a phenomenon of thermal expansion during assembly.

[0115] Finally, in a fourth step, a diffusing film is deposited on the upper surfaces of the walls 41 to form an additional diffusing layer 12.

[0116] In connection with the, we will now describe another embodiment of the invention. The represents a sectional view of the light module 10 according to this other embodiment. In this example, the printed circuit board 3 on which the light sources 2 are mounted forms the substrate on which the grid 4 is directly overmolded. In other words, the light module 10 is devoid of a layer of transparent material directly encapsulating the light sources 2.

[0117] Thus, the grid 4 is directly overmolded onto the first face 31 of the PCB 3. Said grid 4 extends from the PCB 3 between each pair of light sources 2 to form walls 41 separating neighboring light sources 2, so as to define cells 6 each containing a light source 2. Each light source 2 thus emits a light beam into a cell 6 of this grid 4.

[0118] In the example described, the grid is made using a white-colored material with a reflection coefficient of between 60 and 99%, in particular substantially equal to 90%. It could, for example, be a silicone resin enriched with titanium dioxide (TiO2). If necessary, each wall 41 could have a thickness of at most 100 µm. Due to this white color, the light emitted by a light source 2 is reflected in the enclosure 6 defined by the walls 41 and in which this light source 2 is located. These walls therefore significantly reduce the effects of interference or cross-talk and increase the efficiency of the light module 10. It is therefore possible to reduce the dimensions of the light sources without impacting the resolution of the screen.In addition, the edges, or thicknesses, of these white walls contribute to the visible, unlit appearance of the light module and therefore reduce the influence of the color of the photoluminescent element on this unlit appearance.

[0119] On the PCB 3 are also mounted electronic components 8, encapsulated alone or grouped in walls 41 of the grid 4 during overmolding of the grid on the PCB 3, so as to reduce the exposure, wear and the risk of detachment of the electronic components 8, to mask these components 8 and to free the rear face 32 of the PCB on which these components 8 are usually mounted. The components 8 may be active or passive components, connected via the PCB 3 to a power supply and / or a control unit of the light module to participate in the power supply and / or the control of the light sources 2.

[0120] Compared to the manufacturing method of the light module 1 of the first embodiment, the light module 10 can be produced by a reduced number of steps, since the walls 41 of the grid 4 can be directly overmolded onto the PCB 3.

[0121] In connection with the, a third embodiment of the invention will now be described. The represents a sectional view of the light module 100 according to this third embodiment.

[0122] The embodiment of the is substantially identical to that of set, the grid 4 being overmolded in grooves 51 of the layer of transparent material 5.

[0123] On the other hand, the first layer of material 5 is devoid of optical element 7 and a second layer of transparent material 11 is overmolded on the layer of transparent material 5 between each wall 41 of the grid 4. The second layer of transparent material 11 thus extends from the first layer of transparent material 5 to the height of the walls 41 of the grid 4. The material of the second layer 11 may be a material identical to that of the first layer of transparent material 5 or on the contrary be a different material, in particular provided with diffusing properties.

[0124] In the example described, the upper face of the second layer of transparent material 11 forms an exit surface of the light module 1 and has, at the level of each light source 2, diffusing optical structures 11a. Alternatively or cumulatively, provision may be made to deposit a diffusing film on the upper surface of the second layer 11 to form an additional diffusing layer identical to the layer 12 of the embodiment of set.

[0125] The light module 100 can thus be designed by a method substantially identical to the method for manufacturing the light module 1, the step of depositing the diffusing film being preceded or replaced by a step of molding a transparent material on the first layer 5 and between the walls 41 to form the second layer 11 and possibly by a step of modifying, or texturing, the upper surface of this second layer 11 to form the diffusing optical structures 11a.

[0126] The foregoing description clearly explains how the invention makes it possible to achieve the objectives it has set itself, namely to propose a light module capable of forming a screen having good resolution, without a "cross-talk" effect, and a homogeneous lit appearance, without a "dotty effect", and which can be assembled without generating a defect despite the reduction in the dimensions of the light sources and the pitch separating two neighboring light sources.

[0127] It is thus understood that these objectives are achieved in particular by overmolding, directly onto the support of the light sources or onto a substrate extending over this support, an opaque grid defining cells each containing a light source and each allowing the interception of light rays likely to interfere with a pixel formed by a neighboring light source. This grid can thus limit the "cross-talk" effect and therefore makes it possible to reduce the dimensions of the light sources as well as the pitch separating two neighboring light sources, while using an element to diffuse the light emitted by each light source, in order to avoid a "dotty effect".Furthermore, since the grid is produced by overmolding, it is thus freed from the constraints of positioning the grid in relation to the matrix of light sources during assembly, which could be generated by a variation in the dimensions of the grid due to manufacturing tolerances or a phenomenon of thermal expansion.

[0128] In any event, the invention cannot be limited to the embodiments specifically described in this document, and extends in particular to any equivalent means and to any technically effective combination of these means. In particular, it may be possible to replace the printed circuit board with another support, such as a ceramic or glass substrate, rigid or flexible, straight or curved. It may also be possible to provide for the light sources 2 to form an active matrix. It may also be possible to provide other types of light sources 2 than that described, and in particular light sources 2 of smaller dimensions, for example between 5 µm and 150 µm, such as microLEDs.It will also be possible to consider materials other than those described, or to exchange the different materials of the embodiments which have been described, in particular to produce walls of grey, white or black color, or even to produce alternations or variations in the color of the walls in the same embodiment.

Claims

Light module (1, 10, 100) of a signaling device of a motor vehicle, comprising a plurality of light sources (2) which can be selectively controlled, characterized in that all of the light sources (2) are mounted on the same common support (3) and in that it comprises a grid (4) overmolded on a substrate formed by the common support (3) or extending from the common support, the grid (4) being formed in an opaque material and extending on the substrate between each pair of light sources (2) forming a wall (41) separating the neighboring light sources (2), so that each light source (2) emits a light beam in a cell (6) of this grid (4). Light module (10) according to the preceding claim, characterized in that the substrate is formed by the common support (3) on which all of the light sources (2) are mounted, the grid (4) being directly overmolded onto the common support (3). Light module (10) according to the preceding claim, characterized in that it comprises at least one electronic component (8) mounted on the common support (8), said at least one electronic component (8) being encapsulated in a wall (41) of the grid (4). Light module (1, 100) according to claim 1, characterized in that the substrate is formed by a first layer of transparent material (5) encapsulating all of the light sources (2) arranged on the common support (3), so that each wall (41) of the grid (4) has a part immersed in the first layer of transparent material (5). Light module (1) according to the preceding claim, characterized in that the first layer of transparent material (5) encapsulating the light sources (2) has, at the level of each light source (2), an exit surface (7) of the light beam of curved shape forming an optical component of the light module (1). Light module (1) according to one of claims 4 or 5, characterized in that the first layer of transparent material (5) encapsulating the light sources (2) has, at the level of each light source (2), an exit surface (7) of the light beam provided with diffusing optical structures. Light module (100) according to claim 4, characterized in that it comprises a second layer of transparent material (11) arranged between each wall (41) of the grid (4), extending from the substrate (5) over at least the height of the walls (41) of the grid (4). Light module (100) according to the preceding claim, characterized in that the second layer of transparent material (11) forms an exit surface of the light module (100) and has, at the level of each light source (2), an exit surface of the light beam provided with diffusing optical structures (11a). Light module (1, 10, 100) according to one of the preceding claims, characterized in that it comprises an additional diffusing layer (12) extending above the grid (4). Light module (1, 10, 100) according to one of the preceding claims, characterized in that the walls (41) of the grid (4) are arranged so that each cell has the shape of a cone section. Light module (1, 10, 100) according to one of the preceding claims, characterized in that it has a first protective layer arranged between certain pairs of light sources (2) and having a first albedo and has a second protective layer arranged between other pairs of light sources (2) and having a second albedo greater than the first albedo, the second layer defining a logo. Method of manufacturing a light module (10) according to one of claims 1 to 3 and 9 to 11 when they depend on claim 2 or claim 3, characterized in that it comprises the following steps:Assembly of a plurality of light sources (2) on the same common support (3);Overmolding of an opaque material on the common support (3) to form the grid (4), said grid (4) being arranged between each pair of light sources (2). Method for manufacturing a light module (1, 100) according to one of claims 4 to 11, characterized in that it comprises the following steps: Assembling a plurality of light sources (2) on the same common support (3); Depositing a first layer of transparent material (5) on the common support (3) to encapsulate said plurality of light sources (2); Cutting said first layer of transparent material (5) to form a plurality of grooves, each groove extending between a pair of neighboring light sources (2); Overmolding in each groove of an opaque material to form the grid (4) in the grooves. Method according to the preceding claim, characterized in that it comprises a step of molding the second layer of transparent material (11) between each wall (41) of the grid (4). Method according to one of claims 12 to 14, characterized in that it comprises a step of depositing an additional diffusing layer (12) above the grid (4).

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