An optical module having a lens that projects the irradiated surface of a concentrator and a screen that blocks stray direct light.

Abstract

The invention relates to a light-emitting module (2) comprising a light source (4) capable of emitting a light beam, a plate (6) supporting the light source (4), a collector (8) having a reflective surface (8.2) configured to collect and reflect the light beam 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), and a screen (14) located in front of the light source (4) along the main direction of propagation of the reflected light beam and configured to collect light rays, called direct rays (16), coming directly from the light source. The screen (14) extends with a constant cross section in a transverse direction (14.1) and is arranged on the plate (6).

Description

[Technical field]

[0001] The present invention relates to the field of lighting and signalling, more particularly for applications in the motor vehicle field. [Background technology]

[0002] It is a common practice to create a cut-off illumination beam by using one or more light emitting modules with a bender. Such a light emitting module conventionally comprises a collector with a reflective surface of revolution with an ellipsoidal profile. The collector has the shape of a cap in a half space bounded by a horizontal plane. A light source of the light emitting diode type, which is essentially a point source, is located at a first focal point of the reflective surface and emits light in the half space in the direction of said surface. The light rays are then reflected in a converging manner towards the second focal point of the reflective surface. Another (generally flat) reflective surface with a cut-off edge at the second focal point ensures the upward reflection of the light rays that do not pass exactly through the second focal point. These light rays are then refracted towards the bottom of the illumination beam by a thick lens. This reflective surface is commonly called a "bender" in that it "bends" those light rays (which would otherwise form the upper part of the illumination beam) towards the top of the projection lens. Such a light emitting module has the drawback that it requires high accuracy in the positioning of the benders and the cut-off edges. Moreover, the projection lens must be thick due to its short focal length, which increases its weight and makes it difficult to manufacture (especially in terms of sink marks). Also, the collector has a considerable height and therefore a considerable volume in the height direction.

[0003] WO2020 / 025171A1 discloses a light emitting module, in particular for motor vehicles. The module comprises a collector with a reflecting surface that collects and reflects the light rays emitted by the light source into a light beam, as well as a light emitting module with a bender. The light emitting module also comprises a projection optical system, in particular configured to project the light beam by forming an image of the reflecting surface of the collector (for example a lens). For this purpose, the projection optical system has a focal point located on the reflecting surface, for example at the rear edge of the reflecting surface, so as to accurately image (image) the edge and form a sharp cut in the projected light beam. However, certain light rays emitted by the light source that are not reflected by the reflecting surface of the collector can reach the projection optical system and degrade the projected light beam. For this purpose, a screen (blocking body) is provided that is arranged in front of the light source. This teaching does not address the manufacture of a screen or block, especially in the context of industrial applications. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 025171 Brochure Summary of the Invention

[0005] The aim of the present invention is to alleviate at least one of the above-mentioned drawbacks of the prior art, in particular to bring about an industrially viable use of the screens based on the prior art, with better performance from an optical point of view.

[0006] The subject of the invention is a light source capable of emitting a light beam, a plate supporting the light source, and a device for collecting and reflecting the light beam. A light-emitting module comprising a collector having a reflective surface configured to form 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, and a screen located in front of the light source along the main direction of propagation of the reflected light beam and configured to capture light rays, referred to as direct rays, coming directly from the light source, the screen being notable in that it is arranged on a plate extending with a constant cross section along the lateral direction.

[0007] "Direct rays" should be understood to mean rays that would reach the entrance surface of the optical system directly in the absence of a screen, i.e., rays that would reach the entrance surface of the optical system without being previously deflected by optical elements (especially reflective surfaces). These direct rays (especially those emitted parallel or nearly parallel to the optical axis) would, in the absence of a screen, result in a projected light beam that is not shaped by a collector or reflective surface, which is undesirable.

[0008] The collector and the reflecting surface preferably have the shape of a cap or half shell. The reflecting surface preferably has an elliptical or parabolic profile exhibiting rotational symmetry about an axis parallel to the optical axis.

[0009] According to an advantageous embodiment of the invention, the lateral direction is perpendicular to the optical axis.

[0010] According to an advantageous embodiment of the invention, the screen has a convex end face facing away from the plate, which may also be called an edge area. This end face (or edge area) corresponds to the side of the screen opposite the side of the screen facing towards the plate. As will be seen below, the end face (or edge area) may be continuous or may have several faces or sections separated by corners.

[0011] According to an advantageous embodiment of the invention, the edge face of the screen has a transverse profile with curved portions with a radius of curvature r of 0.1 mm or more and / or straight portions inclined towards the rear and towards the plate by at least 10°, said profile being oriented transverse to the main direction of the screen, which corresponds to the horizontal direction, meaning that the profile lies in a longitudinal plane parallel to the optical axis.

[0012] According to an advantageous embodiment of the invention, the screen has a rear surface that captures the direct light rays, said rear surface being at a distance d along the optical axis of no more than 10 mm, preferably no more than 4 mm, from the light source, said distance d being advantageously measured between the leading edge of the light source and the trailing edge of the rear surface of the screen.

[0013] According to an advantageous embodiment of the invention, the rear surface of the screen is part of the edge surface of the screen. In particular, all or part of the rear surface of the screen can be part of the edge surface of the screen. In that case, at least a part of the rear surface forms part of the edge surface.

[0014] The portion of the rear surface that forms part of the edge surface may form a continuous surface with the remainder of the edge surface of the screen (i.e., the portion of the rear surface is not separated from the remainder of the edge surface by a corner).

[0015] Alternatively, the part of the rear surface that forms part of the edge surface of the screen may be separated from the remainder of the edge surface of the screen by an angle, in which case the edge surface may comprise one or more angles separating different surfaces or portions.

[0016] According to an advantageous embodiment of the invention, the cross section of the screen is triangular, circular, oval (a circular shape having a flattened property including an elliptical shape, an egg shape, etc.) or pentagonal.

[0017] According to an advantageous embodiment of the invention, the screen is made of a metallic material.

[0018] According to an advantageous embodiment of the invention, the screen is attached to the plate by welding, brazing and / or adhesive bonding.

[0019] According to an advantageous embodiment of the invention, the screen is free of a light-reflecting and / or light-absorbing surface treatment.

[0020] The solution according to the invention is advantageous in that it allows the screen to be placed close to the light source, thus making it possible to reduce the dimensions of the screen (in particular its height). This means that the rays of the reflected light beam are not blocked and that the plate is not extended forward beyond the screen, nor is the cooling radiator for the light source extended likewise on the underside of the plate (i.e. on the side opposite to that which supports the light source). The solution according to the invention is also advantageous from the point of view of industrialization, in that it allows the screen to be cut from a bar of material with the desired cross section and that it allows the screen to be positioned and attached as desired on various types of plates. [Brief description of the drawings]

[0021] [Figure 1] 1 is a schematic side view of a light emitting module according to a first embodiment of the present invention; [Diagram 2] Schematic depiction of the light-emitting module in Figure 1 as seen from above. [Diagram 3] FIG. 2 is a perspective side view of a light source, a screen, and a collector of the light emitting module according to the first embodiment of the present invention. [Figure 4] FIG. 11 is a perspective side view of a light source, a screen, and a collector of a light-emitting module according to a second embodiment of the present invention. [Diagram 5] FIG. 11 is a perspective side view of a light source, a screen, and a collector of a light-emitting module according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] In the following description, the concepts "front" and "rear" refer to the main direction of propagation of the light rays along the optical axis.

[0023] 1 to 3 show a light emitting module according to a first embodiment of the present invention.

[0024] FIG. 1 is a schematic side view of the light-emitting module 2. As shown in FIG.

[0025] The light emitting 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 reflected light beam along an optical axis 10 of the module, and a projection lens 12 for projecting said beam. Projection optics other than a projection lens are also conceivable, in particular one or more reflecting mirrors.

[0026] Here, generally according to the invention, the light source 4 is advantageously of the semiconductor type, for example in particular a light emitting diode, and in particular emits light rays in a main direction perpendicular to a main plane of the light source 4 and to the optical axis 10, within a half space defined by said main plane.

[0027] The collector 8 comprises a body 8.1 in the form of a shell or cap and a reflecting surface 8.2 on the inner surface of the body 8.1. The reflecting surface 8.2 can advantageously have an elliptical or parabolic profile. The surface is advantageously a surface of revolution about an axis parallel to the optical axis. Alternatively, it may be a free-form surface. The surface may also have several portions. The collector 8 in the form of a shell or cap is advantageously made of a material exhibiting good heat resistance, for example glass or synthetic polymers such as polycarbonate (PC) or polyetherimide (PEI).

[0028] The expression "parabolic" generally applies to reflectors whose surface has a single focal point, i.e. a single point where the light rays converge, and where the light rays emitted by a light source located at this point of convergence are projected over a long distance after being reflected from the surface. "Projected over a long distance" means that the light rays do not converge towards a point located at least 10 times the dimension of the reflector. In other words, the reflected light rays do not converge towards a single point of convergence, or if they do, this point of convergence is located at a distance of more than 10 times the dimension of the reflector. A parabolic surface may therefore have or not have a parabolic portion. Reflectors with such surfaces are in particular used to create a light beam by themselves.

[0029] The light source 4 is arranged at the focal point of the reflecting surface 8.2 so that its light rays are collected and reflected into a reflected light beam along an optical axis. At least some of these reflected light rays have an inclination angle α of less than 10° with respect to said optical axis, so as to be under the so-called Gaussian condition, which makes it possible to obtain astigmatism (i.e. sharpness of the projected image). The light rays are advantageously reflected by the rear part of the reflecting surface 8.2.

[0030] The projection lens 12 is advantageously a biconvex lens, i.e. with a convex entrance surface 12.1 and a convex exit surface 12.2. The lens 12 is said to be thin (for example less than 6 mm) due to the gentle slope of the light rays to be deflected. The lens 12 has a focal point 12.3 located at or behind the light source 4 along the optical axis 10. In this case, the focal point 12.3 is located on the reflecting surface 8.2 of the collector 8, more precisely at its rear edge (which in this case is also the lower edge).

[0031] The reflective surface, if it is elliptical, has a second focal point located in front of the lens 12 and spaced from the optical axis 10. It should be noted that this focal point could also be located behind the lens and / or on the optical axis (preferably close to the lens) to reduce the beam width at the entrance face of the lens.

[0032] The light-emitting module 2 comprises a screen 14 arranged in front of the light source 4 and facing the reflecting surface 8.2 of the collector 8. The screen 14 has a rear surface 14.2 capable of collecting the direct light rays 16 emitted directly forward by the light source 4 (i.e. not hitting the reflecting surface 8.2). Such a measure is useful to avoid the presence of parasitic rays that may take part in the formation of the light beam (but without being imaged, strictly speaking). These direct light rays 16 (especially those parallel or nearly parallel to the optical axis 10) may then illuminate the upper part of the light beam, which is undesirable in the case of a cut-off illumination beam.

[0033] FIG. 2 is a schematic plan view of the light-emitting module 2 of FIG.

[0034] It can be seen that the screen extends along a transverse direction 14.1, which is preferably perpendicular to the optical axis 10 and parallel to the plate 6. The screen extends along the transverse direction 14.1 in such a way that it blocks or captures direct rays that would otherwise reach the entrance surface 12.1 of the projection lens 12 and interfere with the projected light beam. This results in blocking these parasitic rays. The screen has a constant cross section along the transverse direction 14.1. In this case, the cross section is pentagonal, more particularly a regular pentagon. One of the five sides of the pentagon is placed on the plate 6, and the two adjacent sides located at the rear of the screen adjacent to the side placed on the plate 6 form the rear face 14.2 of the screen 14.

[0035] The screen 14 is advantageously made from metal and / or plastic material, in particular by extrusion, and its cross section is advantageously flat, i.e. without any recesses or voids in the material.

[0036] Advantageously, the rear face 14.2 of the screen 12 is not provided with a light-reflecting or light-absorbing surface treatment. The part of the direct light 16 incident on said rear face 14.2 and reflected is in fact reflected partly towards the reflecting surface 8.2 of the collector 8 and partly towards the plate. The part of the direct light 16 reflected towards the plate is then mainly absorbed there. The part of the direct light 16 reflected towards the reflecting surface 8.2 of the collector 8 is reflected at an angle of incidence such that it is then reflected forward at a distance from the lens 12. However, depending on various parameters, in particular the material of the screen and the overall geometry of the light-emitting module, it is possible to provide an absorbing or reflective optical treatment or coating on the rear face 14.2. In the case of a reflective treatment or coating, it is conceivable to provide absorbing sites that can absorb the direct light thus reflected.

[0037] FIG. 3 is a perspective side view of the light source, screen and collector in the light emitting module 2 of FIGS.

[0038] It can be seen that the distance d between the light source 4 and the screen 14 along the optical axis (not shown, but corresponding to the horizontal direction in FIG. 3) is shortened (preferably to 4 mm or less). This distance is measured between the front edge of the light source 4 and the rear edge of the screen (specifically the rear edge of the rear surface 14.2 of the screen 14). This shortened distance offers the advantage from an optical point of view that the screen can thus capture and block the direct rays while not blocking any of the rays reflected by the reflecting surface 8.2 of the collector 8. In particular, considering the left part of FIG. 3, by moving the screen 14 closer to the light source 4, it is possible to reduce its height so that its end surface 14.3, which is opposite the plate (not shown in FIG. 3), is distanced from the collector 8 and from its reflecting surface 8.2. This distance makes it possible to avoid any collision with the reflected rays.

[0039] It can also be seen that the edge face (also called end area) of the screen 14 has a convex profile. In this case, it comprises a curved portion 14.3.1 with a radius of curvature r and two straight portions 14.3.2 and 14.3.3 inclined at angles β and γ, respectively, 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 curved portion 14.3.1 (the latter is therefore in the middle). The edge face 14.3 is thus formed by a continuous surface formed by the curved portion 14.3.1 and the two straight portions 14.3.2 and 14.3.3.

[0040] The rear straight portion 14.3.3 is part of the rear surface 14.2. In particular, the side of the pentagon at the rear of the screen that is not adjacent to the side that is disposed on the plate forms the rear straight portion 14.3.3. Thus, part of the rear surface 14.2 of the screen is part of the edge surface 14.3 of the screen.

[0041] The rear straight portion 14.3.3 is inclined towards the rear and towards the plate (not shown) by an angle γ, which is advantageously equal to or greater than 10°. The front straight portion 14.3.2 is inclined towards the front and towards the plate (not shown). The radius of curvature r is advantageously equal to or greater than 0.1 mm and / or smaller than 1 mm. This radius of curvature r and the angle γ make it possible to reflect direct rays incident on the rear straight portion 14.3.3 and on the curved portion 14.3.1 in such a way that they do not reach the projection lens (not shown).

[0042] FIG. 4 is a perspective side view of a light source, a screen, and a collector of a light emitting module according to a second embodiment of the present invention.

[0043] Reference numbers from the first embodiment are used to indicate corresponding or identical elements, but these numbers are increased by 100. The descriptions of these elements are also incorporated within the context of the first embodiment of the invention.

[0044] The light-emitting module 102 differs from the light-emitting module 2 of the first embodiment only in that the screen 114 has a triangular, and no longer pentagonal, cross section. The triangular cross section is preferably an equilateral triangle. The distance d between the light source 104 and the screen 114 along the optical axis (not shown, but corresponding to the horizontal direction in FIG. 4) is likewise reduced (preferably to 4 mm or less).

[0045] The end face 114.3 of the screen 114 differs somewhat from that of the screen 14 of the first embodiment of the invention, essentially in that the slopes β and γ of the front straight portion 114.3.2 and the rear straight portion 114.3.3 are larger. The end face 114.3 is formed of a continuous surface formed by a curved portion 114.3.1 and two straight portions 114.3.2 and 114.3.3.

[0046] The rear surface 114.2 is also defined by a generally rear linear portion 114.3.3, so that the entire rear surface 114.2 of the screen is part of the edge surface 114.3 of the screen.

[0047] This arrangement means that the portion of the direct light reflected by the rear face 114.2 is reflected entirely towards the collector 8, in contrast to the first embodiment where a portion is reflected towards a plate (not shown).

[0048] FIG. 5 is a perspective side view of a light source, a screen, and a collector of a light emitting module according to a third embodiment of the present invention.

[0049] The reference numbers of the first embodiment are used to indicate corresponding or identical elements, but these numbers are incremented by 200. The descriptions of these elements are also incorporated within the context of the first embodiment of the invention.

[0050] The light-emitting module 202 differs from the light-emitting modules 2 of the first and second embodiments only in that the screen 214 has a circular, and no longer pentagonal or triangular, cross section. The circular cross section preferably has a constant radius over its entire circumference, but it should be understood that this cross section may also have a certain degree of flattening (in particular an elliptical shape). The distance d between the light source 204 and the screen 214 along the optical axis (not shown, but corresponding to the horizontal direction in FIG. 5) is likewise reduced (preferably to 4 mm or less).

[0051] The end face 214.3 of the screen 214 is convex. It differs essentially from that of the screens 14 and 114 of the first and second embodiments of the invention in that this face comprises a single part (i.e. does not have any straight parts), which in this case is the curved part 214.3.1. This curved part has a radius of curvature r that can be significantly larger than the radius of curvature r of the curved parts 14.3.1 and 114.3.1 of the first and second embodiments of the invention.

[0052] The rear face 214.2 is also formed by a generally curved portion 214.3.1. The entire rear face 214.2 of the screen 214 is therefore part of the edge face 214.3 of the screen 214. As in the first embodiment, and in contrast to the second embodiment, thanks to the curved shape of the rear face 214.2, a part of the direct light beam reflected by the rear face 214.2 is reflected towards the collector 208 and another part is reflected towards a plate (not shown).

[0053] In general (especially for the three embodiments described above), the screen can be attached to the plate by welding, brazing and / or adhesive bonding. The screen is advantageously made from a metallic material, in particular by extrusion. In this case, attachment by welding and / or brazing is particularly suitable. The required lengths can be cut from a bar having the desired cross section (such as one of those presented above).

[0054] Also generally, the overall height of the screen (perpendicular to the optical axis) is advantageously in the range 0.5 to 5 mm.

[0055] It should be understood that shapes other than pentagonal, triangular, and circular are contemplated, so long as the rear surface can absorb or reflect direct light rays toward the plate and / or concentrator so that they do not reach the projection optics (in this case, the projection lens) (even after being reflected by the concentrator's reflective surface).

[0056] The light emitting module of the invention can be used to provide a standard illumination light beam for a motor vehicle, such as, in particular, low beam and high beam lighting functions, which functions are per se well known to the person skilled in the art.

Claims

1. a light source (4; 104; 204) capable of emitting a light beam, a plate (6) supporting said light source (4; 104; 204); a collector (8; 108; 208) having a reflecting surface (8.2; ​​108.2; 208.2) adapted to collect and reflect said light beam into a reflected light beam along an optical axis (10); an optical system (12) adapted to project said reflected light beam by imaging a portion of said reflecting surface (8.2; ​​108.2; 208.2); a screen (14; 114; 214) in front of said light source (4; 104; 204) along the main direction of propagation of said reflected light beam and configured to capture light rays, called direct rays (16), coming directly from said light source; Equipped with A light-emitting module (2; 102; 202), characterized in that the screen (14; 114; 214) extends with a constant cross section along a transverse direction (14.1; 114.1; 214.1) and is arranged on the plate (6).

2. 2. The light emitting module (2; 102; 202) according to claim 1, wherein the lateral direction (14.1; 114.1; 214.1) is perpendicular to the optical axis (10).

3. 3. A light-emitting module (2; 102; 202) according to claim 1 or 2, characterized in that the screen (14; 114; 214) has a convex end face (14.3; 114.3; 214.3) on the side facing away from the plate (6).

4. 4. A light-emitting module (2; 102; 202) according to claim 3, wherein the end faces (14.3; 114.3; 214.3) of the screen (14; 114; 214) have a transverse profile with curved portions (14.3.1; 114.3.1; 214.3.1) with a radius of curvature r of 0.1 mm or more and / or straight portions (14.3.3; 114.3.3) inclined at least 10° towards the rear and towards the plate (6).

5. 5. The light emitting module (2; 102; 202) according to claim 1, wherein the screen (14; 114; 214) has a rear surface (14.2; 114.2; 214.2) that captures the direct light beam (16), the rear surface (14.2; 114.2; 214.2) being located at a distance d along the optical axis (10) of 10 mm or less, preferably 4 mm or less, from the light source (4; 104; 204).

6. 6. A light-emitting module (2; 102; 202) according to claim 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).

7. 7. The light emitting module (2; 102; 202) according to any one of the preceding claims, wherein the cross section of the screen (14; 114; 214) is triangular, circular, oval or pentagonal.

8. The light emitting module (2; 102; 202) according to any one of the preceding claims, wherein the screen (14; 114; 214) is made of a metallic material.

9. 9. The light emitting module (2; 102; 202) according to any one of the preceding claims, wherein the screen (14; 114; 214) is attached to the plate (6) by welding, brazing and / or adhesive bonding.

10. 10. The light-emitting module (2; 102; 202) according to any one of the preceding claims, wherein the screen (14; 114; 214) is free of any light-reflecting and / or light-absorbing surface treatment.

Images