Light module with a lens imaging the illuminated surface of a collector and a screen blocking stray direct rays

Abstract

The invention relates to a light module (2) comprising a light source (4) capable of emitting light rays; a plate (6) bearing the light source (4); a collector (8) with a reflective surface (8.2) configured to collect and reflect the light rays into a reflected light beam along an optical axis (10); an optical system (12) configured to project the reflected light beam by imaging a portion of the reflective surface (8.2); a screen (14) located in front of the light source (4), in a main direction of propagation of the reflected light beam, and configured to collect light rays coming directly from the source, which rays are referred to as direct rays (16); wherein the screen (14) extends in a transverse direction (14.1) with a constant cross-section and is arranged on the plate (6).

Description

[0001] DESCRIPTION

[0002] TITLE: LIGHT MODULE WITH A LENS IMAGING THE ILLUMINATED SURFACE OF A COLLECTOR AND A SCREEN BLOCKING STRAY DIRECT RAYS

[0003] Technical field

[0004] The invention relates to the technical field of lighting and signaling, more particularly for applications in the automotive field.

[0005] Prior art

[0006] It is generally known to produce a cut-off lighting beam using one or more folding light modules. Such a light module conventionally comprises a collector with a reflective surface of revolution with an elliptical profile, in the form of a cap in a half-space delimited by a horizontal plane. An essentially point light source, of the light-emitting diode type, is located at a first focus of the reflective surface and illuminates in the half-space in the direction of said surface. The rays are thus reflected in a convergent manner towards a second focus of the reflective surface. Another reflective surface, generally planar, with a cut-off edge at the second focus ensures an upward reflection of the rays which do not pass precisely through the second focus, these rays then being refracted by a thick lens towards the bottom of the lighting beam.This reflective surface is commonly referred to as a "folder" because it "folds" the rays that would otherwise form an upper part of the lighting beam towards the top of the projection lens. Such a light module has the disadvantage of requiring significant precision in the positioning of the folder and the cut-off edge. Also, the projection lens must be a thick lens due to its short focal length, which increases its weight and complicates its production, such as shrinkage defects. In addition, the collector has a certain height and, therefore, a certain height requirement.

[0007] Published patent document WO 2020 / 025171 A1 discloses a light module, in particular for a motor vehicle, comprising a collector with a reflective surface collecting and reflecting the light rays emitted by a light source into a light beam, similar to a folding light module. The light module also comprises a projection optical system, such as a lens, specifically configured to project the light beam in question by forming an image of the reflective surface of the collector. For this purpose, the projection optical system has a focus located on the reflective surface, for example at a rear edge thereof so as to correctly image said edge and form a sharp cut-off in the projected light beam. However, certain rays emitted by the light source and not reflected by the reflective surface of the collector may reach the projection optical system and degrade the projected light beam.For this purpose, a screen, or blocker, is provided in front of the light source. The production of the screen or blocker, particularly in the context of industrial implementation, is not covered in this teaching.

[0008] Statement of the invention

[0009] The invention aims to overcome at least one of the drawbacks of the aforementioned state of the art. More specifically, the invention aims to propose an implementation of the screen of the state of the art, which is optically efficient and industrially usable.

[0010] The invention relates to a light module comprising a light source capable of emitting light rays; a plate supporting the light source; a collector with a reflective surface configured to collect and reflect the light rays into a reflected light beam along an optical axis; an optical system configured to project the reflected light beam by imaging a portion of the reflective surface; a screen located in front of the light source, along a main direction of propagation of the reflected light beam, and configured to collect light rays coming directly from the source, called direct rays; remarkable in that the screen extends along a transverse direction with a constant section and is arranged on the plate.

[0011] "Direct rays" means light rays which, in the absence of the screen, are capable of directly reaching the input face of the optical system, or in other words, of reaching the input face of the optical system without having been deflected beforehand by an optical element, in particular by the reflecting surface. These direct rays, in particular those emitted parallel or almost parallel to the optical axis, would contribute to the projected light beam in the absence of the screen without having been shaped by the collector and the reflecting surface, which is not desirable.

[0012] Advantageously, the collector and the reflecting surface have a cap or half-shell shape. Advantageously, the reflecting surface has an elliptical or parabolic profile of revolution around an axis parallel to the optical axis.

[0013] According to an advantageous embodiment of the invention, the transverse direction is perpendicular to the optical axis.

[0014] According to an advantageous embodiment of the invention, the screen has an end face, opposite the plate, which is convex. The end face can also be called the end zone. This end face, or end zone, corresponds to the side of the screen which is opposite the side of the screen facing the plate. As will be seen later, the end face, or the end zone, can be continuous or comprise several faces or portions separated by an edge.

[0015] According to an advantageous embodiment of the invention, the end face of the screen has a profile comprising a rounded portion with a radius of curvature greater than or equal to 0.1 mm and / or a straight portion inclined at least 10° towards the rear and the plate. The profile in question is transverse to the main direction of the screen, corresponding to the transverse direction, meaning that the profile is in a longitudinal plane parallel to the optical axis.

[0016] According to an advantageous embodiment of the invention, the screen has a rear face collecting the direct rays located at a distance d, along the optical axis, from the light source which is less than or equal to 10 mm, preferably less than or equal to 4 mm. Advantageously, the distance is measured between a front edge of the light source and a rear edge of the rear face of the screen.

[0017] According to an advantageous embodiment of the invention, the rear face of the screen is part of the end face of the screen. In particular, all or part of the rear face of the screen may be part of the end face of the screen. At least part of the rear face then forms a portion of the end face.

[0018] Said part of the rear face forming a portion of the end face may form a continuous face with the rest of the end face of the screen, that is to say that said part of the rear face is not separated from the rest of the end face by an edge. Alternatively, said part of the rear face forming a portion of the end face of the screen may be separated from the rest of the end face of the screen by an edge. The end face may then comprise one or more edges separating different faces or portions.

[0019] According to an advantageous embodiment of the invention, the section of the screen is triangular, circular, oval or pentagonal.

[0020] According to an advantageous embodiment of the invention, the screen is made of metallic material.

[0021] According to an advantageous embodiment of the invention, the screen is fixed to the plate by welding, brazing and / or gluing.

[0022] According to an advantageous embodiment of the invention, the screen is free from surface treatment of the reflective type and / or the light-absorbing type.

[0023] The measures of the invention are advantageous in that they allow the screen to be placed close to the light source, which makes it possible to dimension the screen with a reduced size, in particular a reduced height, thus avoiding intercepting rays of the reflected light beam, and also to extend the plate forward beyond the screen and to extend to the same extent a radiator for cooling the light source, under the plate, that is to say to a face opposite to that supporting the light source. The measures of the invention are also advantageous from an industrialization point of view, in that the screens can be cut from a bar having the desired section and in that they allow the screens to be positioned and fixed as desired on different plate models.

[0024] Brief description of the drawings

[0025] [Fig 1] is a schematic representation, in side view, of a light module according to a first embodiment of the invention;

[0026] [Fig 2] is a schematic representation, viewed from above, of the light module of Figure 1;

[0027] [Fig 3] is a side view and perspective illustration of the light source, the screen and the collector of the light module of the first embodiment of the invention; [Fig 4] is a side view and perspective illustration of the light source, the screen and the collector of a light module according to a second embodiment of the invention;

[0028] [Fig 5] is a side view and perspective illustration of the light source, screen and collector of a light module according to a third embodiment of the invention.

[0029] Detailed description

[0030] In the following description, the notions "front" and "back" refer to a principal direction of propagation of rays along the optical axis.

[0031] Figures 1 to 3 illustrate a light module according to a first embodiment of the invention.

[0032] Figure 1 is a schematic side view of the light module 2.

[0033] The light module 2 essentially comprises a light source 4, a plate 6 supporting the light source 4, a collector 8 capable of reflecting the light rays emitted by the light source 4 to form a light beam reflected along an optical axis 10 of the module, and a projection lens 12 for said beam. Other optical projection systems than the projection lens are conceivable, such as in particular one or more mirrors.

[0034] Here, as generally according to the invention, the light source 4 is advantageously of the semiconductor type, such as in particular a light-emitting diode. In particular, the light source 4 emits light rays in a half-space delimited by the main plane of said source, in a main direction perpendicular to said plane and to the optical axis 10.

[0035] The collector 8 comprises a main body 8.1 in the form of a shell or cap, and a reflective surface 8.2 on the inner face of the main body 8.1. The reflective surface 8.2 may advantageously have a profile of the elliptical or parabolic type. It is advantageously a surface of revolution around an axis parallel to the optical axis. Alternatively, it may be a free-form surface. It may also comprise several sectors. The collector 8 in the form of a shell or cap is advantageously made of materials having good heat resistance, for example glass or synthetic polymers such as polycarbonate (PC) or polyether imide (PEI).

[0036] The term "parabolic type" generally applies to reflectors whose surface has a single focus, i.e. a zone of convergence of the light rays such that the light rays emitted by a light source placed at this convergence zone are projected at a great distance after reflection on the surface. Projected at a great distance means that these light rays do not converge towards an area located at least 10 times the dimensions of the reflector. In other words, the reflected rays do not converge towards a convergence zone or, if they converge, this convergence zone is located at a distance greater than or equal to 10 times the dimensions of the reflector. A surface of the parabolic type may therefore have parabolic portions or not. A reflector with such a surface can in particular be used alone to create a light beam.

[0037] The light source 4 is arranged at a focus of the reflecting surface 8.2 so that its rays are collected and reflected into a reflected light beam along the optical axis. At least a portion of these reflected rays have inclination angles α relative to said optical axis which are less than or equal to 10°, so as to be in the so-called Gaussian conditions, making it possible to obtain stigmatism, that is to say sharpness of the projected image. These are advantageously the rays reflected by the rear portion of the reflecting surface 8.2.

[0038] The projection lens 12 is advantageously a bi-convex lens, i.e. with a convex entrance face 12.1 and a convex exit face 12.2. The lens 12 is said to be thin, for example less than 6 mm, due to the low inclination of the rays to be deflected. The lens 12 has a focus 12.3 which is located, along the optical axis 10, at the level of the light source 4 or even behind said source. In this case the focus 12.3 is located on the reflecting surface 8.2 of the collector 8, more precisely at its rear edge, here also the lower edge.

[0039] The reflecting surface, if it is of the elliptical type, has a second focus located at the front of the lens 12 and at a distance from the optical axis 10. It should be noted that it is also possible for this focus to be located at the rear of the lens and / or on the optical axis, preferably close to the lens, so as to reduce the width of the beam at the level of the entrance face of the lens.

[0040] The light module 2 comprises a screen 14 arranged in front of the light source 4 and facing the reflective surface 8.2 of the collector 8, with a rear face 14.2 capable of collecting the direct light rays 16 emitted forward directly by the source in question 4, that is to say not meeting the reflective surface 8.2. Such a measure is useful for avoiding the presence of stray light rays likely to participate in the formation of the light beam without being strictly speaking imaged. These direct rays 16, in particular those which are parallel or quasi-parallel to the optical axis 10, will then potentially illuminate an upper part of the light beam, which is not desirable in the case of a cut-off lighting beam.

[0041] Figure 2 is a schematic top view of the light module 2 of Figure 1.

[0042] It can be observed that the screen extends along the transverse direction 14.1 which is preferably perpendicular to the optical axis 10 and preferably parallel to the plate 6. The screen extends along the transverse direction 14.1 so as to intercept or collect the direct light rays likely, in the absence of the screen 14, to reach the entry face 12.1 of the projection lens 12 and to interfere with the projected light beam. This thus makes it possible to intercept these parasitic rays. The screen has a constant section along the transverse direction 14.1. In the present case, the section in question is pentagonal, more particularly a regular pentagon. One of the five sides of the pentagon is arranged against the plate 6 and two adjacent sides, located at the rear of the screen and adjacent to the side arranged against the plate 6, form the rear face 14.2 of the screen 14.

[0043] The screen 14 is advantageously made of metallic and / or plastic material, in particular by extrusion. Its section is advantageously solid, that is to say free of hollows or voids of material.

[0044] The rear face 14.2 of the screen 12 is advantageously free of surface treatment of the reflective type and / or of the light-absorbing type. The part of the direct light rays 16 incident on the rear face 14.2 in question which is reflected is in reality partly towards the reflective surface 8.2 of the collector 8 and partly towards the plate. The part of direct light rays 16 reflected towards the plate is then mainly absorbed there. The part of direct light rays 16 reflected towards the reflective surface 8.2 of the collector 8 is with angles of incidence such that they are then reflected forwards at a distance from the lens 12. It is however possible to provide an absorbent or reflective optical coating or treatment on the rear face 14.2, in particular depending on various parameters such as the material of the screen and the general geometry of the light module.In the case of a reflective coating or treatment, it is then possible to provide an absorption zone capable of absorbing the direct light rays thus reflected.

[0045] Figure 3 is a side view and perspective illustration of the light source, screen and collector of the light module 2 of Figures 1 and 2.

[0046] It can be observed that the distance d, along the optical axis (not shown but corresponding to a horizontal direction in Figure 3), between the light source 4 and the screen 14, is reduced, preferably less than or equal to 4 mm. This distance is measured between a front edge of the light source 4 and a rear edge of the screen, more precisely a rear edge of the rear face 14.2 of the screen 14. This reduced distance provides an optical advantage in that the screen can thus collect and block direct light rays while not intercepting any of the light rays reflected by the reflective surface 8.2 of the collector 8. Indeed, considering the left-hand part of Figure 3, it is easily understood that bringing the screen 14 closer to the light source 4 makes it possible to reduce its height and, therefore, to place its end face 14.3, opposite the plate (not shown in Figure 3), at a distance from the collector 8 and its reflective surface 8.2.This distance helps avoid any interference with reflected light rays.

[0047] It can also be observed that the end face of the screen 14, also called the end zone, has a convex profile. This comprises in this case a rounded portion 14.3.1 with a radius of curvature and two straight portions 14.3.2 and 14.3.3 inclined at an angle [3 and y, respectively relative to a direction parallel to the optical axis. These two straight portions 14.3.2 and 14.3.3 are on either side of the rounded portion 14.3.1 which is then central. The end face 14.3 is thus formed by a continuous surface formed by the rounded portion 14.3.1 and the two straight portions 14.3.2 and 14.3.3.

[0048] The rear right portion 14.3.3 is part of the rear face 14.2. In particular, the side of the pentagon located at the rear of the screen and not adjacent to the side arranged against the plate forms the rear right portion 14.3.3. A part of the rear face 14.2 of the screen is therefore part of the end face 14.3 of the screen.

[0049] The rear straight portion 14.3.3 is inclined backwards and towards the plate (not shown) by the angle y which is advantageously greater than or equal to 10°. The front straight portion 14.3.2 is inclined forwards and towards the plate by the angle [3. The radius of curvature advantageously remains greater than or equal to 0.1 mm and / or less than 1 mm. This radius of curvature and the angle y allow the direct light rays incident on said rear straight portion 14.3.3 and rounded portion 14.3.1 to be reflected so as not to reach the projection lens (not shown).

[0050] Figure 4 is a side view and perspective illustration of the light source, screen and collector of a light module according to a second embodiment of the invention.

[0051] The reference numbers of the first embodiment are used to designate identical or corresponding elements, these numbers being increased by 100. Reference is also made to the description of these elements in the context of the first embodiment of the invention.

[0052] The light module 102 differs from the light module 2 of the first embodiment only in that the screen 114 has a triangular section and no longer a pentagonal one. The triangular section is preferably an equilateral triangle. The distance d, along the optical axis (not shown but corresponding to a horizontal direction in Figure 4), between the light source 104 and the screen 114, is similarly reduced, preferably less than or equal to 4 mm.

[0053] The end face 114.3 of the screen 114 is somewhat different from that of the screen 14 of the first embodiment of the invention, essentially in that the inclinations |3 and y of the front 114.3.2 and rear 114.3.3 straight portions are greater. The end face 114.3 is formed by a continuous surface formed by the rounded portion 114.3.1 and the two straight portions 114.3.2 and 114.3.3. Also, the rear face 114.2 is formed integrally by the rear straight portion 114.3.3. The entire rear face 114.2 of the screen is therefore part of the end face 114.3 of the screen.

[0054] By this arrangement, the part of the direct light rays reflected by the rear face 114.2 is entirely reflected in the direction of the collector 8, unlike the first embodiment where a part is reflected towards the platinum (not shown).

[0055] Figure 5 is a side view and perspective illustration of the light source, screen and collector of a light module according to a third embodiment of the invention.

[0056] The reference numbers of the first embodiment are used to designate identical or corresponding elements, these numbers being increased by 200. Reference is also made to the description of these elements in the context of the first embodiment of the invention.

[0057] The light module 202 differs from the light module 2 of the first and second embodiments only in that the screen 214 has a circular section and no longer pentagonal or triangular. The circular section is preferably with a constant radius over the entire periphery, it being understood, however, that this section may have a certain ovality, in particular an elliptical shape. The distance d, along the optical axis (not shown but corresponding to a horizontal direction in FIG. 5), between the light source 204 and the screen 214, is similarly reduced, preferably less than or equal to 4 mm.

[0058] The end face 214.3 of the screen 214 is convex. It is different from those of the screens 14 and 114 of the first and second embodiments of the invention, essentially in that this face comprises a single portion which is in this case a rounded portion 214.3.1, that is to say does not have any straight portion. This rounded portion has a radius of curvature r which may be substantially greater than the radius of curvature r of the rounded portions 14.3.1 and 114.3.1 of the first and second embodiments of the invention.

[0059] Also, the rear face 214.2 is formed entirely by the rounded portion 214.3.1. The entire rear face 214.2 of the screen 214 is therefore part of the end face 214.3 of the screen 214. Similar to the first embodiment and unlike the second embodiment, due to the rounded shape of the rear face 214.2, a portion of the direct light rays reflected by the rear face 214.2 is in the direction of the collector 208 and another portion is in the direction of the plate (not shown).

[0060] Generally speaking, particularly for the three embodiments described above, the screen can be fixed to the plate by welding, brazing and / or gluing. The screen is advantageously made of metallic material, particularly by extrusion. Fixing by brazing and / or welding is particularly suitable in this case. The necessary length can be cut from a bar having the desired section, such as one of those presented above.

[0061] Still generally, the total height of the screen, in a direction perpendicular to the optical axis, is advantageously between 0.5 and 5mm.

[0062] It is understood that shapes other than pentagonal, triangular and circular shapes are conceivable provided that the rear face has the capacity to absorb direct light rays or to reflect them towards the plate and / or towards the collector so that after reflection by the reflective surface of the collector, these rays do not reach the optical projection system, in this case the projection lens.

[0063] The light modules of the invention can be used to form light beams for regulatory lighting of motor vehicles, such as in particular a horizontal cut-off lighting function, commonly referred to as "code" or "low-beam" in English, or without cut-off, commonly referred to as "road" or "high-beam" in English. These functions are in themselves well known to those skilled in the art.

Claims

DEMANDS [Claim 1.] Light module (2; 102; 202) comprising: - a light source (4; 104; 204) capable of emitting light rays; - a plate (6) supporting the light source (4; 104; 204); - a collector (8; 108; 208) with a reflective surface (8.2; ​​108.2; 208.2) configured to collect and reflect light rays into a reflected light beam along an optical axis (10); - an optical system (12) configured to project the reflected light beam by imaging a part of the reflective surface (8.2; ​​108.2; 208.2); - a screen (14; 114; 214) located in front of the light source (4; 104; 204), along a principal direction of propagation of the reflected light beam, and configured to collect light rays coming directly from the source, called direct rays (16); characterized in that the screen (14; 114; 214) extends along a transverse direction (14.1; 114.1 ; 214.1 ) with a constant section and is arranged on the plate (6). [Claim 2.] Light module (2; 102; 202) according to claim 1, wherein the transverse direction (14.1; 114.1; 214.1) is perpendicular to the optical axis (10). [Claim 3.] Light module (2; 102; 202) according to any one of claims 1 and 2, wherein the screen (14; 114; 214) has an end face (14.3; 114.3; 214.3), opposite the plate (6), which is convex. [Claim 4.] Light module (2; 102; 202) according to claim 3, wherein the end face (14.3; 114.3; 214.3) of the screen (14; 114; 214) has a cross profile comprising a rounded portion (14.3.1; 114.3.1; 214.3.1) with a radius of curvature greater than or equal to 0.1 mm and / or a straight portion (14.3.3; 114.3.3) inclined at least 10° towards the rear and the plate (6). [Claim 5.] Light module (2; 102; 202) according to any one of claims 1 to 4, wherein the screen (14; 114; 214) has a rear face (14.2; 114.2; 214.2) collecting direct rays (16) located at a distance d, along the optical axis (10), from the light source (4; 104; 204) which is less than or equal to 10mm, preferably less than or equal to 4mm. [Claim 6.] Light module (2; 102; 202) according to claims 2 and 5, wherein the rear face (14.2; 114.2; 214.2) of the screen (14; 114; 214) is part of the end face (14.3; 114.3; 214.3) of the screen (14; 114; 214). [Claim 7.] Light module (2; 102; 202) according to any one of claims 1 to 6, wherein the screen section (14; 114; 214) is triangular, circular, oval or pentagonal. [Claim 8.] Light module (2; 102; 202) according to any one of claims 1 to 7, wherein the screen (14; 114; 214) is made of metallic material. [Claim 9.] Light module (2; 102; 202) according to any one of claims 1 to 8, wherein the screen (14; 114; 214) is fixed to the plate (6) by welding, brazing and / or gluing. [Claim 10.] Light module (2; 102; 202) according to any one of claims 1 to 9, wherein the screen (14; 114; 214) is free of surface treatment of the reflective type and / or of the absorbing type for light.

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