Light emitting device for a motor vehicle

Abstract

A light emitting device comprising an optical device and a first printed circuit board on which a light source is fastened, the light source comprising a light emitting region and a protective housing surrounding the light emitting region, a first height of the protective housing relative to a flat surface of the first printed circuit board being greater than a second height of the light emitting region, the light-emitting device is characterized in that the light-emitting device comprises a shielding cover, the shielding cover is arranged between the optical device and the light emitting area so as to prevent light from the light emitting area from being reflected on the protective shell and reaching the optical device, and the shielding cover directly abuts against the first printed circuit board and / or directly abuts against the light source.

Description

[0001] The invention relates to a lighting device for a motor vehicle.

[0002] Nowadays, motor vehicle optical systems include superpixelated LED-type light sources that enable the display of changing images. However, the use of such light sources in vehicle optical systems requires solving a number of problems.

[0003] First, the clarity of the image projected by the light source may be adversely affected by reflection phenomena of light from the light emission area on components located in the optical system and close to the light emission area. In particular, light reflection may be caused by the reflective surface of the protective housing, which overhangs the light emission area of ​​the light source.

[0004] Furthermore, the operation of the light source may be disturbed by external electromagnetic fields generated by electronic components located near the light source.

[0005] Additionally, the heat generated by the light source must be removed to avoid damaging electronic components located in or near the light source.

[0006] Additionally, the components of the optical system must be protected from the damaging properties of the sun's rays penetrating through the lenses of the optical system.

[0007] The object of the present invention is to provide a lighting device that makes it possible to overcome the above-mentioned constraints. In particular, the present invention makes it possible to produce a lighting device that is simple and reliable and that at the same time makes it possible to filter the light reflections on the protective housing adjacent to the light emission zone of the lighting device, protect the lighting device from the influence of solar rays and ambient electromagnetic fields, and dissipate the heat generated by the light emission zone.

[0008] To this end, the present invention relates to a light emitting device, which comprises an optical device and a first printed circuit board, a light source is fastened to the first printed circuit board, the light source comprises a light emitting area and a protective shell surrounding the light emitting area, a first height of the protective shell relative to a first direction perpendicular to a flat surface of the first printed circuit board pointing toward the optical device, measured relative to the flat surface, is greater than a second height of the light emitting area relative to the flat surface measured in the first direction,

[0009] The light emitting device comprises a shield arranged between the optical device and the light emitting area to prevent light from the light emitting area from being reflected on the protective housing and reaching the optical device, the shield directly abutting against the first printed circuit board and / or directly abutting against the light source.

[0010] In one embodiment, the shield rests directly on the light emission area and / or on a protective housing of the light source.

[0011] In one embodiment, the mask extends along the main surface and comprises openings for the passage of light generated by the light emitting area, delimited by inner edges protruding from the main surface or in continuation of the main surface.

[0012] In one embodiment, the end of the inner edge of the mask has a chamfer oriented toward the light emission area, for example a 45 degree chamfer.

[0013] In one embodiment, inner edges of the mask protrude from a major surface of the mask, and ends of the inner edges directly abut against the light emission area so as to border a perimeter of the light emission area.

[0014] In one embodiment, the shield rests directly against a heat sink disposed adjacent the light emitting device to promote cooling of the light emitting area.

[0015] In one embodiment, the mask is made of a flexible material, allowing the inner edges to match the shape of the light emitting area.

[0016] In one embodiment, the inner edge of the mask is in the continuation of the main surface of the mask, and a portion of the main surface of the mask directly rests on the protective housing.

[0017] In one embodiment, the mask is made of metal, in particular of aluminum or stainless steel.

[0018] In one embodiment, the shield forms a Faraday cage, and the light source is placed inside the Faraday cage.

[0019] The drawings show, by way of example, embodiments of a light emitting device according to the invention.

[0020] Figure 1 An embodiment of a light emitting device according to the invention is schematically shown.

[0021] Figure 2 A cross-sectional view of a printed circuit board is schematically shown, on which a light emitting area and a protective housing are fastened.

[0022] Figure 3 Embodiments of light sources are shown.

[0023] Figure 4 A top view of a first embodiment of a light emitting device according to the present invention is shown.

[0024] Figure 5 A cross-sectional view of a first embodiment of a light emitting device according to the present invention is shown.

[0025] Figure 6A cross-sectional view of a second embodiment of a light emitting device according to the present invention is shown.

[0026] Figure 7 A cross-sectional view of a third embodiment of a light emitting device according to the present invention is shown.

[0027] Figure 1 A first embodiment of a light emitting device according to the invention is shown.

[0028] The light emitting device 10 mainly comprises:

[0029] - a light source 1, comprising a light emitting area 11 and a protective housing 12 surrounding the light emitting area 11,

[0030] a first printed circuit board 2 having a surface 21 to which the light emission area 11 and the protective housing 12 are fastened,

[0031] - an optical device 3, which may be, for example, a lens, and

[0032] A mask 4 , which is arranged between the light emission area 11 and the optical device 3 .

[0033] Preferably, the light source 1 is an LED, the structure of which is as follows: Figure 2 and Figure 3 Describe in detail.

[0034] Figure 2 A first schematic diagram is provided in which the light emitting area 11 is surrounded by the protective resin 12 .

[0035] The light emitting region 11 is divided into a first region 111, which is referred to as an active region including photon emitting substances, and a second region 112, which is referred to as a technical region not including photon emitting substances.

[0036] The active region 111 includes physical substances that emit photons when current passes through the active region, thereby generating blue light. The active region 111 also includes a phosphor layer that converts the blue light into white light.

[0037] Active area 111 is also referred to as a "pixel matrix". The photon emitting material is divided into a plurality of pixels. Each pixel can be individually controlled to emit photons. Each pixel of matrix 111 is capable of emitting light over 180 degrees. In one embodiment, pixel matrix 111 may include 25,000 pixels.

[0038] The technical area 112 is located at the periphery of the active area 111. In other words, the technical area 112 is a thin strip that adjoins the periphery of the active area 111 and does not emit any light. The width of the technical area 112 is of the order of 500 microns, or even 300 microns.

[0039] In a preferred embodiment, the protective housing 12 is a protective resin 12 molded around the technical area 112 .

[0040] In the remainder of this document, the terms "protective casing" and "protective resin" are used interchangeably.

[0041] The light emitting area 11 and the protective resin 12 are secured on the flat surface 21 of the first printed circuit board 2 .

[0042] A first direction d1 is defined perpendicular to the flat surface 21 of the first printed circuit board 2 , the direction d1 being oriented towards the optical device 3 .

[0043] In the described embodiment, a first height h1 of the protective resin 12 relative to the flat surface 21 measured in the first direction d1 is greater than a second height h2 of the light emitting area 11 relative to the flat surface 21 measured in the first direction d1. In other words, the height h1 of the protective resin 12 exceeds the height h2 of the light emitting area 11. For example, the height h1 is greater than the height h2, and the difference Δh between the two heights can be, for example, 0.2 mm to 0.3 mm.

[0044] Figure 3 Schematically shown is a light source 1 or LED 1 comprising a light emitting area 11 and a protective resin 12 as described above. In this more detailed view, the structure of the LED 1 emerges more precisely. In particular, a pixel matrix 111 is shown in association with a switch matrix 13.

[0045] The LED 1 further comprises a second printed circuit board 14 intended to control the switch matrix 13. The assembly constituted by the pixel matrix 111 and the switch matrix 13 is fastened on the second printed circuit board 14, for example by soldering.

[0046] The second printed circuit board 14 enables the state of each pixel of the LED 1 to be controlled independently, making it lit or switched off. A network of wired connections 15 enables each of the pixels to be controlled. The wired connections 15 are provided between the emitting surface 11 and the second printed circuit board 14 .

[0047] The function of the protective resin 12 is to protect the wired connection network 15. To this end, the protective resin 12 completely encapsulates the wired connection network 15. Therefore, the height difference Δh between the emitting surface 11 and the protective resin 12 is due to the volume occupied by the wired connection network 15 and the excess thickness of the resin required to encapsulate the ends of the wired connections 15 connected to the emitting surface 11.

[0048] In addition, in order to better thermally insulate the wired connection network, the protective resin is preferably light-colored to avoid absorbing heat.

[0049] The excessive thickness of the protective resin 12 and its ability to reflect light result in parasitic light reflections in the LED 1 .

[0050] In order to neutralize parasitic light reflections, the lighting device 10 comprises a mask 4 arranged between the optical device 3 and the light emitting area 11. The function of the mask 4 is to prevent light from the light emitting area 11 and reflected on the protective resin 12 from reaching the optical device 3.

[0051] In other words, the mask 4 has been integrated into the light emitting device 10 in order to block light reflections (which are caused by an excess thickness Δh of the protective resin 12 relative to the emission area 11 ) before they reach the optical device 3 .

[0052] In the absence of the mask 4, the emission area 11 adjacent to the protective resin 12 defines the first light beam 20, as shown in FIG. Figures 5 to 7 The first light beam 20 corresponds to the light emitted by the emission area 11 and reaching the optical device 3 without being reflected on the protective resin 12 .

[0053] The mask 4 with which the light emitting device 10 is equipped extends along a main surface 41 and comprises an opening 42 delimited by an inner edge 43 , the opening 42 allowing the light generated by the light emission zone 11 to pass towards the optical device 3 .

[0054] In the presence of the mask 4, the emission area 11 then defines a second light beam 30 corresponding to the light emitted by the emission area 11 reaching the optical device 3 after passing through the mask 4. Depending on the shape of the opening 42, the light beam 20 may have various shapes, for example a conical shape if the opening 42 is circular.

[0055] Advantageously, the shape of the opening 42 is defined so as to make the second light beam 30 substantially identical to the first light beam 20 and so as to filter the light rays resulting from reflections on the protective resin 12 .

[0056] The end 431 of the inner edge 43 of the mask has a chamfer 432 oriented toward the light emission area 11 , for example a 45 degree chamfer. The chamfer has the effect of preventing the light from the emission area 11 from being reflected on the end 431 of the inner edge 43 .

[0057] The main surface 41 is preferably parallel to the surface of the light emission area 11 .

[0058] Advantageously, the shield 4 is made of a light-absorbing material, in particular, the shield 4 is made of a dark material. This feature of the shield 4 has a first effect of preventing the light from the emission area 11 from reflecting on the shield 4. It also has the effect of protecting the luminous device 10 from the damaging effects of the sun's rays penetrating into the luminous device 10 via the optical device 3.

[0059] References below Figures 4 to 7 Various embodiments of the mask 4 are described. Depending on the embodiment, the mask 4 rests directly on the first printed circuit board 2 and / or directly on the light source 1. In the case where the mask rests on the light source 1, the mask 4 can rest directly on the light emission area 11 and / or on the protective housing 12.

[0060] therefore,

[0061] -In Figure 4 and Figure 5 In the first embodiment described, the mask 4 rests on an emitting surface 11 forming part of an LED 1 which is itself fastened to a first printed circuit board 2.

[0062] -In Figure 6 In the second embodiment described, the mask 4 rests on a protective resin 12 forming part of the LED 1, which is itself fastened to the first printed circuit board 2, and

[0063] -In Figure 7 In the third embodiment described, the mask 4 abuts against the first printed circuit board 2 .

[0064] In the first embodiment, the inner edge 43 of the mask 4 projects from the main surface 41 ; in the second and third embodiments, the inner edge 43 of the mask 4 is in the continuation of the main surface 41 .

[0065] Figure 4 and Figure 5 A first embodiment of a light emitting device 10 according to the present invention is schematically shown in a top view and in a cross-sectional view, respectively.

[0066] In the first embodiment, the inner edge 43 of the mask 4 is substantially perpendicular to the main surface 41 of the mask 4 and is oriented towards the light emission area 11. The end 431 of the inner edge 43 is in contact with the light emission area 11 so as to abut the periphery of the light emission area 11. Advantageously, the contact between the end 431 and the light emission area 11 is made close to the technical area 112 of the light emission area 11.

[0067] Advantageously, in the first embodiment, the chamfer 432 is oriented to face both the light emission area 11 and the protective resin 12 .

[0068] Advantageously, the mask 4 is made of a flexible material, thereby allowing the inner edge 43 to be matched to the shape of the light emission zone 11, in particular allowing the end 431 of the inner edge 43 to be in contact with the emission zone 11 while being as close as possible to the technical zone 112. In addition, the mask 4 may have cutouts 44, thereby making it easier to adjust the inner edge 43 to the shape of the light emission zone 11. Adjusting the inner edge 43 to the shape of the emission zone may require overlapping at the boundaries of the cutouts 44: in this case, at at least one cutout 44, the first boundary of the cutout overlaps with the second boundary of the cutout.

[0069] exist Figure 6 In the second embodiment shown, the inner edge 43 of the mask 4 is in the continuation of the main surface 41 of the mask 4, and a portion 411 of the main surface of the mask rests directly on the protective resin 12. Due to their shape and the absorption of light by their material, the inner edge of the mask 4 (in particular due to the end 431 and the chamfer 432) blocks the light coming from the emission area 11 and reflected on the protective resin 12.

[0070] exist Figure 7 In the third embodiment shown, the inner edge 43 of the mask 4 is in the continuation of the main surface 41 of the mask 4, and the mask 4 directly abuts against the first printed circuit board 2 (the connection between the mask 4 and the first printed circuit board 2 is not formed in the embodiment shown in FIG. Figure 7 ). As in the second embodiment, due to their shape and the absorption of light by their material, the inner edges of the mask 4 (particularly due to the end 431 and the chamfer 432) block the light coming from the emission area 11 and reflected on the protective resin 12.

[0071] Depending on the embodiment, and in particular in the third embodiment, the shield 4 may also be used to protect electronic components 6 located near the optical device 10 and not forming part of the optical device 4 from the sun's rays. In contrast, in the second embodiment, the shield 4 would not be able to fulfil this function and an additional sun protection device 7 would be required to protect the electronic components 6 arranged near the LED 1.

[0072] In some embodiments, in particular in the first embodiment of the light emitting device 10, the shield 4 is connected to a heat sink 5, which is arranged near the light emitting device 10 to promote cooling of the light emitting area 11 via the thermal path 8. In order to promote thermal removal of heat from the emission area 11, the shield 4 must have a minimum thickness, which can depend on the material from which the shield 4 is composed.

[0073] Advantageously, the shield 4 can form a Faraday cage, in which the light source 1 (or LED 1) is placed, thereby limiting the passage of ambient electromagnetic waves in the direction of the light source 1. In one embodiment, the Faraday cage formed by the shield 4 also protects equipment around the LED 1 from electromagnetic emissions from the LED 1.

[0074] Finally, the lighting device according to the invention makes it possible to overcome the problems encountered during the use of LED-type light sources in motor vehicle optical systems, more particularly when the protective housing of the LEDs generates light reflections that tend to disturb the image projected by the lighting device.

[0075] The mask according to the invention is placed as close as possible to the light source, making it possible to eliminate reflected rays while retaining a useful beam substantially equivalent to that which would be obtained without the mask.

[0076] In one embodiment, a shield according to the present invention is in contact with the light emitting area of ​​the LED and thus allows heat generated by the LED to be dissipated via a thermal path connecting the shield to a heat sink.

[0077] Advantageously, the shield according to the invention also protects the LED (and the electronic components surrounding the LED) from the sun's rays which tend to penetrate via the lens of the lighting device, and also from electromagnetic radiation.

Claims

1. A light emitting device (10), comprising an optical device (3) and a first printed circuit board (2), a light source (1) being fastened to the first printed circuit board, the light source comprising a light emitting area (11) and a protective shell (12) surrounding the light emitting area (11), a first height (h1) of the protective shell (12) relative to the flat surface (21) measured in a first direction (d1) perpendicular to a flat surface (21) of the first printed circuit board (2) pointing toward the optical device (3) being greater than a second height (h2) of the light emitting area (11) relative to the flat surface (21) measured in the first direction (d1), characterized in that: The light-emitting device (10) comprises a mask (4), which is arranged between the optical device (3) and the light-emitting area (11) so as to prevent the light from the light-emitting area (11) from being reflected on the protective housing (12) and reaching the optical device (3), and the mask (4) directly abuts against the first printed circuit board (2) and / or directly abuts against the light source (1).

2. Lighting device according to the preceding claim, characterized in that The mask (4) directly abuts against the light emitting area (11) and / or against the protective housing (12) of the light source (1).

3. A lighting device as claimed in any one of the preceding claims, characterized in that The mask (4) extends along a main surface (41) and comprises an opening (42) delimited by an inner edge (43) for the passage of light generated by the light emitting area (11), the inner edge (43) protruding from the main surface (41) or in the continuation of the main surface (41).

4. Lighting device according to the preceding claim, characterized in that The end (431) of the inner edge (43) of the mask has a chamfer (432) oriented toward the light emitting area (11), for example, a chamfer of 45 degrees.

5. The light emitting device (10) according to any one of claims 3 and 4, characterized in that The inner edge (43) of the mask (4) protrudes from the main surface (41) of the mask (4), and the end (431) of the inner edge directly abuts against the light emitting area (11) so as to abut the periphery of the light emitting area (11).

6. Lighting device (10) according to the preceding claim, characterized in that The shield (4) rests directly on a heat sink (5) arranged near the light emitting device (10) in order to promote cooling of the light emitting area (11).

7. The lighting device (10) according to any one of claims 5 and 6, characterized in that The mask (4) is made of a flexible material, thereby allowing the inner edge (43) to match the shape of the light emitting area (11).

8. The light emitting device according to any one of claims 3 to 7, characterized in that The inner edge (43) of the mask (4) is in the continuation of the main surface (41) of the mask (4), and a portion (411) of the main surface of the mask directly rests on the protective shell (12).

9. The lighting device (10) according to one of the preceding claims, characterized in that The shield (4) is made of metal, in particular, of aluminum or stainless steel.

10. The lighting device (10) according to one of the preceding claims, characterized in that The mask (4) forms a Faraday cage, and the light source (1) is placed in the Faraday cage.

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