Lighting device for a motor vehicle
Patent Information
- Application Number
- EP2023833112
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-12-19
- Filing Date
- 2023-12-19
- Publication Date
- 2025-10-29
AI Technical Summary
Automotive vehicle optics using ultra-pixelated LED light sources suffer from undesirable light reflections caused by reflective surfaces in the protective housing, which affect the sharpness of projected images.
A lighting device design featuring a protective housing with a specific height and surface geometry that prevents light reflections, including a first surface oriented between the housing's heights to intercept and redirect rays away from the optical device, and optionally incorporating a grained or convex surface to further attenuate reflections.
The solution effectively reduces light reflections, ensuring that projected images remain sharp by directing reflected rays outside the optical path, thereby enhancing the clarity and reliability of the lighting device.
Smart Images
Figure 1.1
Abstract
Description
Luminous device for motor vehicle
[0001] The invention relates to a lighting device for a motor vehicle.
[0002] Today's automotive optics include ultra-pixelated LED light sources that can project images of various shapes. However, using such a light source in a vehicle optic can generate undesirable effects.
[0003] Indeed, the sharpness of the images projected by the light source may be penalized by phenomena of reflection of the rays coming from the light ray emitting zone on elements located in the optics and close to the light ray emitting zone. In particular, light reflections may be caused by a reflective surface of a protective housing, said reflective surface overhanging the light ray emitting zone of the light source.
[0004] The aim of the invention is to provide a lighting device that overcomes the constraints described above. In particular, the invention makes it possible to produce a lighting device that is simple and reliable and that makes it possible to filter light reflections on a protective housing bordering the light ray emitting zone of the lighting device.
[0005] To this end, the invention relates to a light device comprising an optical device and a first printed circuit on which is fixed a light source comprising a light ray emitting zone and a protective housing surrounding the light ray emitting zone, a first height of the protective housing relative to a flat surface of the first printed circuit, measured in a first direction directed towards the optical device perpendicular to said flat surface, being strictly greater than a second height of the light ray emitting zone relative to the flat surface measured in the first direction. In addition, a first surface of the housing oriented towards the light ray emitting zone and comprised between the first height and the second height is defined so as to prevent rays coming from the light ray emitting zone from being reflected on said first surface and reaching the optical device.
[0006] In one embodiment of the light device, the housing covers and / or protects electrical connections connecting the first printed circuit to the light source and / or the first height is determined by the size of the electrical connections.
[0007] In one embodiment of the light device, the first surface is a planar surface extending between the light ray emitting area and an upper surface of the housing. In addition, the first surface is perpendicular to both the light ray emitting area and the upper surface, a first angle formed between the first surface and the upper surface being equal to 90 degrees and having a rounded profile with a radius strictly less than 50 micrometers.
[0008] In one embodiment of the light device, the first surface is a planar surface bordering the light ray emitting area and a second angle formed between the first surface and the light ray emitting area is strictly greater than 160 degrees or the second angle is strictly less than 90 degrees.
[0009] In one embodiment of the light device, the first surface is grained and the roughness of a graining of the first surface is strictly greater than 8 micrometers.
[0010] In one embodiment of the light device, a groove is provided at an upper surface of the housing, proximate the first surface, and the groove defines a housing tab supporting the first surface.
[0011] In one embodiment of the light device, the housing tab extends above the first surface.
[0012] In one embodiment of the light device, the first surface is convex, and a center of curvature of the first surface and the light source are located on the same side of the first surface.
[0013] The attached drawings represent, by way of example, an embodiment of a light device according to the invention.
[0014] Diagrammatically represents an embodiment of a light device according to the invention.
[0015] It schematically represents a sectional view of a printed circuit on which a light emitting zone and a protective casing are fixed.
[0016] Illustrates one embodiment of a light source.
[0017] Illustrates light reflections on a protective housing in an embodiment of the housing without implementing the invention.
[0018] The figure represents a protective housing according to a first embodiment of the invention.
[0019] Illustrates light reflections on a protective housing according to the first embodiment of the invention.
[0020] The figure represents a protective housing according to a second embodiment of the invention.
[0021] Illustrates light reflections on a protective housing according to the second embodiment of the invention.
[0022] The figure represents a protective housing according to a third embodiment of the invention.
[0023] Illustrates light reflections on a protective housing according to the third embodiment of the invention
[0024] A first embodiment of a light device according to the invention is represented by the.
[0025] The light device 10 mainly comprises, - a light source 1 comprising a light ray emitting zone 11, and a protective housing 12 surrounding the light ray emitting zone 11, - a first printed circuit 2 having a surface 21 on which the light ray emitting zone 11 and the protective housing 12 are fixed, and - an optical device 3, which may be for example a lens.
[0026] Preferably, the light source 1 is an LED, the structure of which is detailed in Figures 2 and 3. As a note, in Figures 2 and 3, the housing 12 is shown according to a first embodiment which is described later in the document. In addition, other embodiments of the housing 12, in particular a second and a third embodiment, are also described later in this document.
[0027] Provides a first schematic representation of the light ray emitting zone 11 surrounded by the protective housing 12.
[0028] The light ray emitting zone 11 is divided into a first zone 111 called active comprising photon emitting material, and a second zone 112 called technical not comprising photon emitting material.
[0029] Active area 111 comprises a physical material that emits photons when an electric current passes through it, thus generating blue light. Active area 111 also comprises a phosphor layer that transforms blue light into white light.
[0030] The active area 111 is also referred to as a “pixel array.” The photon-emitting material is decomposed into pixels. Each pixel can be individually controlled to emit photons. Each pixel in the array 111 is capable of emitting light rays over 180 degrees. In one embodiment, the pixel array 111 may comprise 25,000 pixels.
[0031] The active area 111 defines an emission cone 4 of the light source, the emission cone being more specifically represented on the. In order to project the sharpest possible light area, the light rays contained in the emission cone 4 must come directly from the active area 111. In other words, it is not desirable for reflected rays to be contained in the emission cone 4.
[0032] The technical zone 112 is located on the periphery of the active zone 111. In other words, the technical zone 112 is a thin strip which borders the periphery of the active zone 111 and which does not emit light. The order of magnitude of the width of the technical zone 112 is 500 microns, or even 300 microns.
[0033] In a preferred embodiment, the protective housing 12 is a protective resin 12 molded around the technical area 112.
[0034] In the remainder of the document, the terms “protective casing” and “protective resin” are used interchangeably.
[0035] The light ray emitting area 11 and the protective resin 12 are fixed on a flat surface 21 of the first printed circuit 2.
[0036] A first direction d1 is defined, perpendicular to the flat surface 21 of the first printed circuit 2, the direction d1 being oriented towards the optical device 3.
[0037] In the embodiment described, a first height h1 of the protective resin 12 relative to the flat surface 21, measured along the first direction d1, is strictly greater than a second height h2 of the light ray emitting zone 11 relative to the flat surface 21, measured along the first direction d1. In other words, the height h1 of the protective resin 12 exceeds the height h2 of the light ray emitting zone 11. For example, the height h1 is strictly greater than the height h2, the difference Δh between the two heights being able to be, for example, from 0.2 to 0.3 millimeters.
[0038] Schematically represents the light source 1, or LED 1, comprising the light ray emitting zone 11 and the protective resin 12 previously described. In this more detailed view, the structure of the LED 1 appears more precisely. In particular, the pixel matrix 111 is shown associated with a switch matrix 13, also called “switch matrix 13”.
[0039] The LED 1 also comprises a second printed circuit 14 intended to control the switch matrix 13. The assembly consisting of the pixel matrix 111 and the switch matrix 13 is fixed to the second printed circuit 14, for example by soldering.
[0040] The second printed circuit 14 makes it possible to independently control the state of each pixel of the LED 1 as being lit or off. A network of wire connections 15 makes it possible to control each of the pixels. The wire connections 15 are arranged between the emitting surface 11 and the second printed circuit 14.
[0041] The protective resin 12 has the role of protecting the network of wire connections 15. For this purpose, the protective resin 12 completely envelops the network of wire connections 15. Thus, the height difference Δh between the emitting surface 11 and the protective resin 12 is due to the volume occupied by the network of wire connections 15 and the excess thickness of resin necessary to envelop the ends of the wire connections 15 connected to the emitting surface 11.
[0042] In addition, for better thermal insulation of the wired connection network, the protective resin is preferably light in color, so as not to absorb heat.
[0043] The extra thickness of the protective resin 12, and its ability to reflect light contribute to generating parasitic light reflections in the LED 1. Indeed, in an embodiment described by the of a housing 17 without implementation of the invention, the housing 17 may comprise an at least partially rounded surface 171 bordering the emitting surface 11. Thus, without implementation of the invention, the geometry of the housing 17 may allow a light ray R1 coming from the emitting zone 11 to be reflected on a surface of the housing, in particular on a rounded edge of the housing 17 and generate a beam of rays R2, certain rays being contained in the cone 4 and reaching the optical device 3.
[0044] In order to limit the quantity of reflected light rays reaching the optical device 3, a housing 12 according to the invention comprises a first surface 121 oriented towards the light ray emitting zone 11 and comprised between the first height h1 and the second height h2, the first surface being defined so as to prevent rays coming from the light ray emitting zone 11 from being reflected on said first surface 121 and reaching the optical device 3.
[0045] In an advantageous embodiment, all the surfaces 121 of the housing oriented towards the light ray emitting zone 11 and comprised between the first height h1 and the second height h2 are defined so as to prevent rays coming from the light ray emitting zone 11 from being reflected on these surfaces 121 and reaching the optical device 3.
[0046] In the remainder of the document, the term “surface 121” or “first surface 121” refers to the first surface(s) 121 defined so as to prevent rays from the light ray emitting zone 11 from being reflected on these surfaces 121 and reaching the optical device 3.
[0047] With reference to Figures 5 to 10, different embodiments of the surface 121 are described below. In the described embodiments, the first surface 121 is a flat surface bordering the light ray emitting zone 11.
[0048] A first embodiment of the surface 121 is detailed by the. In this embodiment, the first surface 121 extends between the light ray emitting zone 11 and an upper surface 122 of the housing 12. In addition, the first surface 121 is perpendicular to both the light ray emitting zone 11 and the upper surface 122. Furthermore, a first angle 123 formed between the first surface 121 and the upper surface 122 is equal to 90 degrees. Furthermore, the first angle 123 has a rounding 125 with a radius strictly less than 50 micrometers.
[0049] As illustrated by the, in the first embodiment of the invention, a ray R3 coming from the emitting zone 11 can be reflected on the first surface 121. In this case, the reflection generates a reflected ray R4, which is substantially symmetrical to the ray R3 along an axis of symmetry perpendicular to the surface 121. The ray R4 thus produced passes through the cone 4 without reaching the optical device 3.
[0050] A second embodiment of the surface 121 is detailed by the. In this embodiment, a second angle 124 formed between the first surface 121 and the light ray emitting zone 11 is strictly greater than 135 degrees, or even 140 degrees, or even 150 degrees. Thus, grazing rays coming from the emitting zone - that is to say rays whose trajectory is close to the first surface 121 - are reflected in an area outside the light device.
[0051] Indeed, as illustrated by the, in the second embodiment of the invention, a ray R5 coming from the emitting zone 11 can be reflected on the first surface 121. In this case, the reflection generates a reflected ray R6, which is substantially symmetrical to the ray R5 along an axis of symmetry perpendicular to the surface 121. The ray R6 thus produced is directed towards the outside of the light device 10. The ray R6 therefore does not reach the optical device 3.
[0052] A third embodiment of the surface 121 is detailed in the. In this embodiment, the second angle 124 formed between the first surface 121 and the light ray emitting zone 11 is strictly less than 90 degrees. Advantageously, a “V” shaped groove 126 is made at the upper surface 122 of the housing 12, close to the surface 121. The groove 126 delimits a housing tab 127 supporting the surface 121 as well as a free space giving flexibility to the housing tab 127. Indeed, the housing 12 being preferably made by molding, it is advantageously designed so that it is easily demolded. In the embodiment described, the flexibility of the tab 127 and the free space created by the groove 126 allow the housing 12 to be demolded.
[0053] Preferably, the housing tab 127 extends above the first surface 121.
[0054] As illustrated by the, in the second embodiment of the invention, a ray R7 coming from the emitting zone 11 can be reflected on the first surface 121. In this case, the reflection generates a reflected ray R8, which is substantially symmetrical to the ray R7 along an axis of symmetry perpendicular to the surface 121. The ray R8 thus produced is confined to a zone close to the emitting zone 11. The ray R8 therefore does not reach the optical device 3.
[0055] In a fourth embodiment, the first surface 121 may be grained: in other words, the first surface 121 has a relief in the form of small, tightly packed grains. In this embodiment of the invention, the physical properties of the first surface 121 are thus modified in order to attenuate the light reflections on the first surface 121. Indeed, the presence of grains on the first surface 121 generates a diffusion of the light. The roughness Ra of the graining of the first surface 121 may be quantified by measuring, over a certain length of the first surface 121, the average of the peaks and valleys of the first surface 121. Advantageously, the roughness Ra of the graining of the first surface 121 is strictly greater than 8 micrometers.
[0056] In the fourth embodiment, even if the shape of the housing 12 is likely to generate reflections of rays coming from the emitting zone 11, the light reflection is attenuated by the graining of the first surface 121.
[0057] Alternatively, the fourth embodiment could be combined with any of the first, second or third embodiments, thereby benefiting from the joint effects of the shape and graining of the first surface 121.
[0058] In alternative or complementary embodiments to the previously described embodiments, the first surface 121 may be convex, a center of curvature of the first surface 121 and the light source 1 being located on the same side of the first surface 121.
[0059] In other words, if we consider two spaces delimited between them by the first surface 121, only one of the two spaces comprises both the center of curvature of the first surface 121 and the light source 1.
Claims
A light device (10) comprising an optical device (3) and a first printed circuit (2) on which is fixed a light source (1) comprising a light ray emitting area (11) and a protective housing (12) surrounding the light ray emitting area (11), a first height (h1) of the protective housing (12) relative to a flat surface (21) of the first printed circuit (2), measured in a first direction (d1) directed towards the optical device (3) perpendicular to said flat surface (21), being strictly greater than a second height (h2) of the light ray emitting area (11) relative to the flat surface (21) measured in the first direction (d1), wherein a first surface (121) of the housing (12) oriented towards the light ray emitting area (11) and comprised between the first height (h1) and the second height (h2),is defined so as to prevent rays from the light ray emitting area (11) from being reflected on said first surface (121) and reaching the optical device (3)., Lighting device according to the preceding claim, characterized in that the housing (12) covers and / or protects electrical connections connecting the first printed circuit (2) to the light source (1) and / or in that the first height (h1) is determined by the size of the electrical connections. Illumination device according to one of the preceding claims, characterized in that the first surface (121) is a flat surface extending between the light ray emitting zone (11) and an upper surface (122) of the housing (12), and in that the first surface (121) is perpendicular to both the light ray emitting zone (11) and the upper surface (122), a first angle (123) formed between the first surface (121) and the upper surface (122) being equal to 90 degrees and having a rounded profile (125) with a radius strictly less than 50 micrometers. Luminous device according to one of claims 1 or 2, characterized in that the first surface (121) is a flat surface bordering the light ray emitting zone (11) and in that- a second angle (124) formed between the first surface (121) and the light ray emitting zone (11) is strictly greater than 160 degrees or- the second angle (124) is strictly less than 90 degrees. Luminous device (10) according to one of the preceding claims, characterized in that the first surface (121) is grained and in that the roughness of a graining of the first surface (121) is strictly greater than 8 micrometers. Luminous device (10) according to one of the preceding claims, characterized in that a groove (126) is formed at an upper surface (122) of the housing (12), close to the first surface (121), and in that the groove (126) delimits a housing tab (127) supporting the first surface (121). Luminous device (10) according to the preceding claim, characterized in that the housing tab (127) extends above the first surface (121). Illuminating device (10) according to one of the preceding claims, characterized in that the first surface (121) is convex and in that a center of curvature of the first surface (121) and the light source (1) are located on the same side of the first surface (121).