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

technical field

[0001] The invention relates to the technical field of lighting and signaling, more particularly for applications in the automotive field. Previous technique

[0002] It is generally known to create a cutoff beam using one or more bending light modules. Such a light module typically comprises a collector with a reflective surface of revolution having an elliptical profile, shaped like a cap within a half-space delimited by a horizontal plane. An essentially point light source, such as a light-emitting diode (LED), is located at a first focus of the reflective surface and illuminates the half-space in the direction of said surface. The rays are thus reflected convergently towards a second focus of the reflective surface. Another reflective surface, usually flat, with a cutoff edge at the second focus, ensures upward reflection of the rays that do not pass precisely through the second focus. These rays are then refracted downwards by a thick lens into the lighting beam.This reflective surface is commonly referred to as a "bender" because it bends the rays upwards towards the projection lens, preventing them from forming the upper part of the light beam. Such a light module has the disadvantage of requiring significant precision in the positioning of the bender and the cut edge. Furthermore, the projection lens must be thick due to its short focal length, which increases its weight and complicates its production, particularly due to the risk of sink marks. In addition, the collector has a certain height and, consequently, a certain amount of vertical space.

[0003] The published patent document WO 2020 / 025171 A1 discloses a light module, particularly for motor vehicles, comprising a collector with a reflective surface that collects and reflects light rays emitted by a light source into a light beam, similar to a folding light module. The light module also includes a projection optical system, such as a lens, specifically configured to project the light beam, forming an image of the collector's reflective surface. To this end, the projection optical system has a focal point located on the reflective surface, for example, at its rear edge, so as to properly image said edge and form a sharp cut in the projected light beam. Some rays emitted by the light source and not reflected by the collector's reflective surface may, however, reach the projection optical system and degrade the projected light beam.For this purpose, a screen, or blocker, is placed in front of the light source. The construction of the screen or blocker, particularly in the context of industrial implementation, is not covered in this course. Description of the invention

[0004] The invention aims to overcome at least one of the drawbacks of the aforementioned prior art. More specifically, the invention aims to provide an implementation of the prior art screen that is optically efficient and industrially feasible.

[0005] The invention relates to a light module comprising a light source capable of emitting light rays; a platform supporting the light source; a collector with a reflective surface configured to collect and reflect the light rays into a light beam reflected along an optical axis; an optical system configured to project the reflected light beam by imaging a part of the reflective surface; a screen located in front of the light source, 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; remarkable in that the screen extends along a transverse direction with a constant section and is arranged on the platform.

[0006] The term "direct rays" refers to light rays that, in the absence of a screen, could directly reach the entrance face of the optical system; in other words, reach the entrance face of the optical system without having been first deflected by an optical element, particularly the reflecting surface. These direct rays, especially those emitted parallel or nearly parallel to the optical axis, would contribute to the projected light beam in the absence of a screen without having been shaped by the collector and the reflecting surface, which is undesirable.

[0007] Advantageously, the collector and the reflective surface have a cap or half-shell shape. Advantageously, the reflective surface has an elliptical or parabolic profile of revolution about an axis parallel to the optical axis. According to an advantageous embodiment of the invention, the transverse direction is perpendicular to the optical axis.

[0008] According to the invention, the screen has an end face, opposite the mounting 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 that is opposite the side of the screen facing the mounting plate. As will be seen later, the end face, or end zone, can be continuous or comprise several faces or portions separated by an edge.

[0009] According to 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. In an advantageous embodiment of the invention, the end face of the screen has a straight portion inclined at least 10° towards the rear and the mounting plate. The profile in question is transverse to the principal direction of the screen, corresponding to the transverse direction, meaning that the profile lies in a longitudinal plane parallel to the optical axis.

[0010] According to an advantageous embodiment of the invention, the screen has a rear face that collects 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 d is measured between a front edge of the light source and a rear edge of the back face of the screen.

[0011] According to an advantageous embodiment of the invention, the rear face of the screen forms part of the end face of the screen. In particular, all or part of the rear face of the screen may form part of the end face of the screen. At least a portion of the rear face then forms a portion of the end face.

[0012] 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.

[0013] Alternatively, that portion of the rear face forming part of the screen's end face may be separated from the rest of the screen's end face by an edge. The end face may then comprise one or more edges separating different faces or portions.

[0014] According to an advantageous embodiment of the invention, the screen section is triangular, circular, oval or pentagonal.

[0015] According to an advantageous embodiment of the invention, the screen is made of metallic material.

[0016] According to an advantageous embodiment of the invention, the screen is fixed to the plate by welding, brazing and / or gluing.

[0017] According to an advantageous embodiment of the invention, the screen is free of surface treatment of the reflective type and / or of the light-absorbing type.

[0018] The features of the invention are advantageous in that they allow the screen to be positioned close to the light source, thus enabling the screen to be sized, particularly in height, thereby avoiding the interception of rays from the reflected light beam. They also allow the mounting plate to be extended forward beyond the screen and, to the same extent, a heat sink for cooling the light source to be extended beneath the mounting plate, i.e., on a face opposite to that supporting the light source. The features of the invention are also advantageous from an industrialization standpoint, in that the screens can be cut from a bar with the required cross-section and in that they allow the screens to be positioned and fixed as desired on different mounting plate designs. Brief description of the drawings

[0019] [ Fig 1 ] is a schematic, side-view representation of a light module according to a first embodiment of the invention; [ Fig 2 ] is a schematic representation, viewed from above, of the luminous module of the figure 1 ; Fig 3 ] is a side and perspective illustration of the light source, screen and collector of the light module of the first embodiment of the invention; [ Fig 4 ] is a side and perspective illustration of the light source, screen and collector of a light module according to a second embodiment of the invention; [ 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. Detailed description

[0020] In the description that follows, the terms "front" and "back" refer to a principal direction of ray propagation along the optical axis.

[0021] THE figures 1 to 3 illustrate a light module according to a first embodiment of the invention.

[0022] There figure 1 is a schematic side view of light module 2.

[0023] The light module 2 essentially comprises a light source 4, a mounting 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 said beam. Other optical projection systems besides the projection lens are conceivable, such as one or more mirrors.

[0024] 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. Specifically, the light source 4 emits light rays into a half-space delimited by the principal plane of said source, in a principal direction perpendicular to said plane and to the optical axis 10.

[0025] The collector 8 comprises a main body 8.1 in the shape of a shell or dome, and a reflective surface 8.2 on the inner face of the main body 8.1. The reflective surface 8.2 may advantageously have an elliptical or parabolic profile. It is advantageously a surface of revolution about an axis parallel to the optical axis. Alternatively, it may be a freeform surface. It may also have several sectors. The shell or dome-shaped collector 8 is advantageously made of materials with good heat resistance, for example, glass or synthetic polymers such as polycarbonate (PC) or polyetherimide (PEI).

[0026] The term "parabolic" generally applies to reflectors whose surface has a single focal point, that is, a zone of convergence for light rays such that light rays emitted by a light source placed at this convergence zone are projected over a great distance after reflection from the surface. Projected over a great distance means that these light rays do not converge towards a zone 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 do converge, this convergence zone is located at a distance greater than or equal to 10 times the dimensions of the reflector. A parabolic surface may or may not have parabolic sections. A reflector with such a surface can, in particular, be used alone to create a beam of light.

[0027] The light source 4 is positioned at a focus of the reflecting surface 8.2 such that its rays are collected and reflected into a beam of light along the optical axis. At least some of these reflected rays have angles of inclination α with respect to the optical axis that are less than or equal to 10°, thus meeting Gaussian conditions, which produce stigmatism, i.e., a sharp projected image. Advantageously, these are the rays reflected by the rear part of the reflecting surface 8.2.

[0028] The projection lens 12 is advantageously a biconvex lens, that is, with a convex entrance face 12.1 and a convex exit face 12.2. The lens 12 is described as thin, for example less than 6 mm, due to the shallow angle of the rays to be deflected. The lens 12 has a focal point 12.3 which is located, along the optical axis 10, at the level of the light source 4 or behind said source. In this case, the focal point 12.3 is located on the reflective surface 8.2 of the collector 8, more precisely at its rear edge, which is also referred to here as the lower edge.

[0029] The reflective surface, if it is of the elliptical type, has a second focus located in front of the lens 12 and at a distance from the optical axis 10. It should be noted that it is also possible that this focus is located behind the lens and / or on the optical axis, preferably close to the lens, so as to reduce the width of the beam at the entrance face of the lens.

[0030] The light module 2 includes a screen 14 positioned in front of the light source 4 and opposite the reflective surface 8.2 of the collector 8, with a rear face 14.2 adapted to collect the direct light rays 16 emitted forwards directly by the source 4, i.e., rays not intersecting the reflective surface 8.2. This measure is useful for preventing the presence of stray light rays that could contribute to the formation of the light beam without actually being imaged. These direct rays 16, particularly those parallel or nearly parallel to the optical axis 10, could then potentially illuminate an upper part of the light beam, which is undesirable in the case of a cutoff beam.

[0031] There figure 2 is a schematic view of the top of the light module 2 of the figure 1 .

[0032] 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 stage 6. The screen extends along the transverse direction 14.1 so as to intercept or collect the direct light rays that, in the absence of the screen 14, would reach the entrance face 12.1 of the projection lens 12 and interfere with the projected light beam. This allows these stray rays to be intercepted. The screen has a constant cross-section along the transverse direction 14.1. In this case, the cross-section is pentagonal, more specifically a regular pentagon. One of the five sides of the pentagon is positioned against the stage 6, and two adjacent sides, located at the rear of the screen and adjacent to the side positioned against the stage 6, form the rear face 14.2 of the screen 14.

[0033] The screen 14 is advantageously made of metallic and / or plastic material, particularly by extrusion. Its cross-section is advantageously solid, that is to say free of hollows or voids of material.

[0034] The rear face 14.2 of the screen 12 is advantageously free of any reflective and / or absorbent surface treatment. The portion of direct light rays 16 incident on the rear face 14.2 that is reflected is actually partly reflected towards the reflective surface 8.2 of the collector 8 and partly towards the mounting plate. The portion of direct light rays 16 reflected towards the mounting plate is then mostly absorbed there. The portion of direct light rays 16 reflected towards the reflective surface 8.2 of the collector 8 is reflected at angles of incidence such that it is subsequently reflected forward at a distance from the lens 12. However, it is possible to provide an absorbent or reflective optical coating or treatment on the rear face 14.2, depending in particular on various parameters such as the screen material and the overall 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.

[0035] There figure 3 is a side view and perspective illustration of the light source, screen and collector of light module 2 of the figures 1 and 2 .

[0036] We can observe that the distance d, along the optical axis (not shown but corresponding to a horizontal direction to the figure 3The distance between the light source 4 and the screen 14 is reduced, preferably less than or also at 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 part of the figure 3 It is easy to understand that bringing the screen 14 closer to the light source 4 reduces its height and, consequently, positions its end face 14.3 opposite the plate (not shown in the diagram). figure 3 ), at a distance from the collector 8 and its reflective surface 8.2. This distance avoids any interference with the reflected light rays.

[0037] It can also be observed that the end face of the screen 14, also called the end zone, has a convex profile. This includes, in this case, a rounded 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, with respect 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 therefore 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.

[0038] 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 disposed 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.

[0039] The rear right-hand portion 14.3.3 is inclined rearward and toward the plate (not shown) at an angle γ which is advantageously greater than or equal to 10°. The front right-hand portion 14.3.2 is inclined forward and toward the plate at an angle β. The radius of curvature r is advantageously greater than or equal to 0.1 mm and / or less than 1 mm. This radius of curvature r and the angle γ allow the direct light rays incident on the said rear right portion 14.3.3 and rounded portion 14.3.1 to be reflected so as not to reach the projection lens (not shown).

[0040] There 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.

[0041] 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.

[0042] The light module 102 differs from the light module 2 of the first embodiment only in that the screen 114 has a triangular rather than a pentagonal cross-section. The triangular cross-section is preferably an equilateral triangle. The distance d , along the optical axis (not shown but corresponding to a horizontal direction to the figure 4 ), between the light source 104 and the screen 114, is similarly reduced, preferably less than or also at 4mm.

[0043] 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 inclinations β and γ of the straight front portions 114.3.2 and rear portions 114.3.3 are greater. The end face 114.3 is formed by a continuous surface created by the rounded portion 114.3.1 and the two straight portions 114.3.2 and 114.3.3.

[0044] Also, the rear face 114.2 is formed entirely by the rear right 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.

[0045] With this arrangement, the part of the direct light rays reflected by the rear face 114.2 is entirely directed towards the collector 8, unlike the first embodiment where a part is reflected towards the platinum (not shown).

[0046] There figure 5is 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.

[0047] 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.

[0048] The luminous module 202 differs from the luminous module 2 of the first and second embodiments only in that the screen 214 has a circular cross-section rather than a pentagonal or triangular one. The circular cross-section preferably has a constant radius around its entire periphery, although it is understood that this section may exhibit a certain ovality, in particular an elliptical shape. The distance d, along the optical axis (not shown but corresponding to a horizontal direction to the figure 5 ), between the light source 204 and the screen 214, is similarly reduced, preferably less than or equal to 4mm.

[0049] The end face 214.3 of the screen 214 is convex. It differs 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 in this case is a rounded portion 214.3.1, that is to say, it has no straight portion. This rounded portion has a radius of curvature r which can be substantially larger than the radius of curvature r rounded portions 14.3.1 and 114.3.1 of the first and second embodiments of the invention.

[0050] 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, part of the direct light rays reflected by the rear face 214.2 are directed towards the collector 208 and another part are directed towards the plate (not shown).

[0051] In general, particularly for the three embodiments described above, the screen can be attached to the base plate by welding, brazing, and / or bonding. The screen is advantageously made of metallic material, especially by extrusion. In this case, brazing and / or welding is particularly suitable. The required length can be cut from a bar with the desired cross-section, such as one of those shown above.

[0052] Generally speaking, the total height of the screen, in a direction perpendicular to the optical axis, is advantageously between 0.5 and 5mm.

[0053] It is understood that shapes other than pentagonal, triangular and circular 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.

[0054] The light modules of the invention can be used to form regulatory vehicle lighting beams, including a horizontal cutoff function, commonly referred to as "code" or "low-beam" in English, or a continuous cutoff function, commonly referred to as "route" or "high-beam" in English. These functions are well known to those skilled in the art.

Claims

1. A luminous 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 the light rays in a reflected light beam along an optical axis (10); - an optical system (12) configured to project the reflected light beam by imaging part of the reflective surface (8.2; 108.2; 208.2); - a screen (14; 114; 214) which is in front of the light source (4; 104; 204), along a main direction of propagation of the reflected light beam, and is configured to gather light rays coming directly from the source, referred to as direct rays (16), which are likely, in the absence of the screen (14), to directly reach the entry face of the optical system (12); characterized in that the screen (14; 114; 214) extends along a transverse direction (14.1; 114.1; 214.1) with a constant cross section and is disposed on the plate (6) in that the screen (14; 114; 214) has an end face (14.3; 114.3; 214.3), opposite the plate (6), which is convex, and has a transverse profile comprising a rounded portion (14.3.1; 114.3.1; 214.3.1) with a radius of curvature rgreater than or equal to 0.1 mm, the profile in question being transverse to the main direction of the screen, corresponding to the transverse direction, which means that the profile is in a longitudinal plane parallel to the optical axis (10).

2. The luminous module (2;102; 202) as claimed in claim 1, wherein the transverse direction (14.1; 114.1; 214.1) is perpendicular to the optical axis (10).

3. The luminous module (2; 102; 202) as claimed in claim 1 or 2, wherein the end face (14.3; 114.3; 214.3) of the screen (14; 114; 214) has a straight portion (14.3.3; 114.3.3) which is inclined by at least 10° toward the rear and the plate (6).

4. The luminous module (2; 102; 202) as claimed in one of claims 1 to 3, wherein the screen (14; 114; 214) has a rear face (14.2; 114.2; 214.2) which gathers the direct rays (16) and is at a distance d, along the optical axis (10), from the light source (4; 104; 204) that is less than or equal to 10 mm, preferably less than or equal to 4 mm.

5. The luminous module (2; 102; 202) as claimed in claims 2 and 4, 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).

6. The luminous module (2; 102; 202) as claimed in one of claims 1 to 5, wherein the cross section of the screen (14; 114; 214) is triangular, circular, oval or pentagonal.

7. The luminous module (2; 102; 202) as claimed in one of claims 1 to 6, wherein the screen (14; 114; 214) is made of a metal material.

8. The luminous module (2; 102; 202) as claimed in one of claims 1 to 7, wherein the screen (14; 114; 214) is attached to the plate (6) by welding, soldering and / or adhesive bonding.

9. The luminous module (2; 102; 202) as claimed in one of claims 1 to 8, wherein the screen (14; 114; 214) is free of surface treatment of the light-reflecting and / or light-absorbing type.

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