MOTOR VEHICLE LIGHTING MODULE COMPRISING A CERAMIC SUBSTRATE

Abstract

A lighting module of a motor vehicle signaling device includes a ceramic substrate having opposite first and second faces, and a plurality of selectively activatable light sources mounted on the first face of the ceramic substrate. Each of the first and second faces of the ceramic substrate are provided with at least a first and a second respective interconnection layer. The ceramic substrate comprises a plurality of through holes designed to interconnect the first interconnection layer to the second interconnection layer.

Claims

1. A lighting module of a motor vehicle signaling device, comprising a ceramic substrate comprising opposing first and second faces, and a plurality of light sources that can be activated selectively, mounted on the first face of the ceramic substrate, each of the first and second faces of the ceramic substrate being provided with at least one first or second interconnection layer respectively, wherein the ceramic substrate comprises a plurality of through-holes arranged to interconnect the first interconnection layer and the second interconnection layer.

2. The lighting module as claimed in claim 1, wherein the ceramic substrate is a glass substrate.

3. The lighting module as claimed in claim 1, wherein the ceramic substrate is curved.

4. The lighting module as claimed in claim 1, wherein each light source is mounted on said first face of the ceramic substrate level with a through-hole.

5. The lighting module as claimed in claim 1, the module comprising a connector capable of receiving an instruction for controlling said light sources and a control unit arranged to selectively control each of the light sources on the basis of said control instruction received by the connector.

6. The lighting module as claimed in claim 5, wherein the connector comprises an adhesive anisotropic conductive film, the connector being mechanically and electrically connected to one of the first and second interconnection layers by means of said adhesive anisotropic conductive film.

7. The lighting module as claimed in claim 6, wherein the connector comprises a flexible printed circuit board, the control unit being mounted on said flexible printed circuit board.

8. The lighting module as claimed in claim 5, wherein the connector is mounted on the second face of the ceramic substrate.

9. The lighting module as claimed in claim 5, wherein, characterized in that it comprises a plurality of active control elements, each active control element being arranged to control one of the light sources with which it is associated and being mounted on the first interconnection layer level with one of the through-holes so as to be connected to the second interconnection layer, said plurality of active control elements forming an active matrix and the control unit being arranged to control said active matrix on the basis of said control instruction received by the connector.

10. The lighting module as claimed in claim 9, wherein each light source is mounted on and connected to the control element with which it is associated.

11. The lighting module as claimed in claim 5, wherein, characterized in that each light source is mounted directly on the first interconnection layer, the plurality of light sources forming a passive matrix and the control unit being arranged to control said passive matrix on the basis of the control instruction received by the connector.

12. The lighting module as claimed in claim 11, wherein, characterized in that it comprises a support member on which the ceramic substrate is mounted.

13. The lighting module as claimed in claim 1, wherein, characterized in that it comprises an opaque coating applied to the first face of the ceramic substrate.

14. A motor vehicle light signaling device, comprising a lighting module as claimed in claim 1.

15. The lighting module as claimed in claim 2, wherein the ceramic substrate is curved.

16. The lighting module as claimed in claim 2, wherein each light source is mounted on said first face of the ceramic substrate level with a through-hole.

17. The lighting module as claimed in claim 2, the module comprising a connector capable of receiving an instruction for controlling said light sources and a control unit arranged to selectively control each of the light sources on the basis of said control instruction received by the connector.

18. The lighting module as claimed in claim 6, wherein the connector is mounted on the second face of the ceramic substrate.

19. The lighting module as claimed in claim 6, wherein it comprises a plurality of active control elements, each active control element being arranged to control one of the light sources with which it is associated and being mounted on the first interconnection layer level with one of the through-holes so as to be connected to the second interconnection layer, said plurality of active control elements forming an active matrix and the control unit being arranged to control said active matrix on the basis of said control instruction received by the connector.

20. The lighting module as claimed in claim 6, wherein each light source is mounted directly on the first interconnection layer, the plurality of light sources forming a passive matrix and the control unit being arranged to control said passive matrix on the basis of the control instruction received by the connector.

Description

[0029] The present invention will now be described by way of examples that are merely illustrative and that in no way limit the scope of the invention, and with reference to the accompanying illustrations, in which:

[0030] FIG. 1 schematically and partially depicts a cross-sectional view of a lighting module according to a first embodiment of the invention;

[0031] FIG. 2 schematically and partially depicts a cross-sectional view of a lighting module according to a second embodiment of the invention;

[0032] FIG. 3 schematically and partially depicts a cross-sectional view of a lighting module according to a third embodiment of the invention; and

[0033] FIG. 4 schematically and partially depicts a cross-sectional view of a lighting module according to a fourth embodiment of the invention.

[0034] In the following description, elements that are identical, in structure or function, and that appear in several figures, use the same reference signs, unless otherwise indicated.

[0035] [FIG. 1] shows a first embodiment of a lighting module 1 according to the invention. This lighting module 1 forms part of a tail light of a motor vehicle.

[0036] The lighting module 1 comprises a plurality of light sources 2 mounted on a first face 31 of a glass substrate 3. Each of the light sources 2 comprises at least one light-emitting semiconductor chip with dimensions of between 5 μm and 80 μm. The light sources 2 are mounted on the first face 31 in a matrix such that two adjacent light sources 2 are a maximum of 1 mm apart.

[0037] In order to control these light sources 2 selectively, the first face 31 of the glass substrate is provided with a first interconnection layer 41, comprising a network of copper electrical tracks electrically connected to the light sources 2. Symmetrically, the second face 32 of the glass substrate 3, opposite the first face 31, is likewise provided with a second interconnection layer 42, comprising a network of copper electrical tracks of a thickness substantially identical to that of the first layer 41. The glass substrate 3 comprises a plurality of through-holes 33, each of the through-holes being provided with an internal copper coating making it possible to interconnect said first and second interconnection layers 41 and 42.

[0038] In the example described, it will be noted that each light source 2 is mounted on the first interconnection layer 41 by means of a thin film transistor 51, on which said light source 2 is mounted and to which same is connected. Each thin film transistor 51 is mounted on and electrically connected to the first interconnection layer 41 level with a through-hole 33 so as to be connected to the second interconnection layer 42. These thin film transistors 51 thus form an active matrix making it possible to address and control each of the light sources 2, all of the light sources 2 thus forming an active matrix screen.

[0039] In order to control this active matrix, the lighting module 1 comprises a connector 6 for receiving an instruction for controlling the light sources 2. This may for example be an instruction to display a pictogram or a message on said screen, in particular generated by a computer of the motor vehicle, for example on the basis of data relating to the environment of the motor vehicle. By way of example, this may be an instruction to display a pictogram informing an external observer of the opening of a door of the motor vehicle, a pictogram informing a motorist following the motor vehicle of the presence of ice on the road, or information relating to the traffic.

[0040] In order to be mechanically connected to the glass substrate 3 and electrically connected to the second interconnection layer 42, the connector 6 comprises an adhesive anisotropic conductive film 61 fixed to a flexible printed circuit board 62. The film 61 thus allows the board 62 to be fixed on an edge of the second face 32 of the glass substrate 3 while electrically connecting this board to the second interconnection layer 42.

[0041] The lighting module 1 further comprises a control unit 7 arranged to selectively control the active matrix on the basis of the control instructions received by the connector 6. In the example described, the control unit 7 is mounted directly on the flexible printed circuit board 62.

[0042] Non-limitingly, on receipt of a control instruction, the control unit 7 may be arranged to scan the matrix of transistors 51 vertically, applying a selection voltage to each of the rows in succession and, for each row selected during the scan, to simultaneously apply, on the basis of the control instruction, an activation or deactivation signal to each column of the matrix so as to cause or prevent the emission of light by the light source 2 associated with the transistor 51 addressed by the selected row and this column. As the matrix is active, each transistor 51 maintains the light source 2 associated therewith in an on or off state while the remaining rows are scanned.

[0043] It will be observed from [FIG. 1] that the glass substrate 3 has a convex curved shape, from the viewpoint of an observer situated outside the motor vehicle. In order to be able to shape this glass substrate 3 into this convex curved shape, the substrate 3 has a thickness of between 100 μm and 200 μm, making it flexible and thus allowing it to be given a curvature with a radius of curvature of between 90 mm and 500 mm, without the risk of weakening the various components mounted on this substrate 3, particularly on the second face 32

[0044] In addition, in order to be able to maintain this convex curved shape, the lighting module 1 comprises a support member 8 on which the glass substrate 3 is mounted. The support member has a face 81 for receiving the glass substrate 3 having a convex curved profile. It will further be noted that the support member 8 is also provided with means for fixing this member 8 in the tail light, which makes it possible to leave the edges of the glass substrate 3 free and thus give it a floating appearance. In addition, the support member 8 makes it possible to dissipate the heat emitted by the light sources 2 and transferred to this support member 8 via the through-holes 33. Finally, it is possible to add a thermal interface, between the face 81 for receiving the glass substrate 3 and the second face 32 of the glass substrate, for example formed from an organic material having particular thermal conductivity properties, in particular a thermal conductivity coefficient greater than 1 W/m/° C., filling the clearances and spaces between the face 81, the second face 32 and the various components that may be mounted on this second face 32.

[0045] [FIG. 2] shows a second embodiment of a lighting module 10 according to the invention.

[0046] Unlike in the embodiment in [FIG. 1], each light source 2 is mounted directly on the first interconnection layer 41. The plurality of light sources 2 thus forms a passive matrix screen. The lighting module 10 comprises a plurality of devices 52 for controlling the supply of electrical power to the light sources 2, each control device 52 being mounted on the second face 32 of the glass substrate 3 level with a through-hole 33 in order to control the supply of electrical power to the light source 2 mounted level with said through-hole 33.

[0047] In addition, the control unit 7 is incorporated into a ball grid array, which is mounted on the second interconnection layer 42 to control the passive matrix on the basis of the control instructions received by the connector 6.

[0048] It will be noted that in the example described, the receiving face 81 of the support member 8 is provided with a plurality of recesses 82 arranged to accommodate each of the control devices 52. The support member 8 thus also makes it possible to dissipate the heat emitted by these control devices 52. Finally, as in [FIG. 1], it is possible to add a thermal interface between the face 81 and the second face 32 of the substrate 3.

[0049] [FIG. 3] shows a third embodiment of a lighting module 100 according to the invention.

[0050] Unlike in the embodiment in [FIG. 1], each light source 2 is mounted directly on the first interconnection layer 41. The lighting module 100 comprises integrated microcircuits 53, also mounted on this interconnection layer. In the variant shown, groups of light sources 2 are each connected, via the interconnection layer 41, to one of these integrated microcircuits 53, which thus controls these light sources 2. The light sources 2 and the integrated microcircuits 53 thus form an active matrix. The plurality of light sources 2 thus forms an active matrix screen selectively controlled, as in [FIG. 1], by the control unit 7 on the basis of the control instructions received by the connector 6.

[0051] [FIG. 4] shows a fourth embodiment of a lighting module 1000 according to the invention.

[0052] Unlike in the embodiment in [FIG. 1], each light source 2 is mounted directly on the first interconnection layer 41. The interconnection layer 41 comprises a plurality of thin connection sub-layers incorporating a plurality of integrated microcircuits 54. Each light source 2 is each connected, via the interconnection layer 41, to one of these integrated microcircuits 54, which thus controls this or these light source(s) 2. The light sources 2 and the integrated microcircuits 54 of the thin connection sub-layers thus form an active matrix screen selectively controlled, as in [FIG. 1], by the control unit 7 on the basis of the control instructions received by the connector 6.

[0053] The foregoing description clearly explains how the invention is able to achieve its stated objectives, in particular by proposing a lighting module comprising a plurality of light sources mounted on a glass substrate provided with interconnection through-holes. It will thus be appreciated that using a glass substrate makes it possible to reduce the substrate thickness until it is flexible and a convex curve can thus be applied thereto in order to obtain a screen with a uniform appearance that is visible in a wide field of view while following the curvature of the lighting device incorporating this lighting module. In addition, the use of through-holes means that the light sources that make up the screen can be addressed selectively without the need for specific connection arrangements on an edge of the substrate which would be visible, it being in particular possible for the connection arrangements to be positioned on a face of the substrate that is not visible. A screen with a floating appearance can thus be produced.

[0054] In any event, the invention is not limited to the embodiments specifically described in this document, and extends, in particular, to any equivalent means and to any technically operational combination of these means. In particular, a substrate made from a ceramic other than glass may be envisaged. Other types of light source than the one described may also be envisaged, and in particular light sources with larger dimensions, for example of between 80 μm and 300 μm. Other types of through-hole than the one described may also be envisaged, for example through-holes that are filled with a conductive material in order to interconnect the first and second interconnection layers. The application to the first face of the substrate of an opaque coating in a dark color and with a matt appearance may also be envisaged.