FR3009065A1 - OPTICAL DEVICE FOR A MOTOR VEHICLE - Google Patents

Abstract

The subject of the invention is an optical device for propagating light rays for a light device, in particular for a motor vehicle, comprising: a guide (1) for the propagation of light rays; at least two collectors (2a, 2b, 2c); ) each configured to produce, upon reception of a beam from a light source (4a, 4b, 4c), an input beam in the guide (1), characterized in that the collectors (2a, 2b, 2c ) are configured to focus the input beam, each in a predetermined focus area (14). Application to the automotive industry

Description

The present invention relates in particular to an optical device that can be used for emitting light. A preferred application relates to the automotive industry for the production of signaling and / or lighting devices, in particular vehicle headlights. In the latter field, the use of optical guides has grown strongly in recent years. It is generally substantially elongated elements in the case of linear guides, transparent material with a typically circular section. The guide cooperates most often with a light source placed at one of its ends. This assembly propagates light rays in the guide, towards the end of the guide longitudinally opposite the source, by internal reflection on the surfaces of the guide. This is the case of the device presented in document DE-A1-19939087. In this publication, a guide cooperates with several sources that supply it with light. Each source is placed at one end of a collimator dedicated to this source. The rays coming from the source are received by the collimator which sends them towards the guide common to all the sources. The use, for the same guide, two or more light sources is problematic in terms of beam homogeneity and the invention aims to provide a solution to this difficulty. One aspect of the invention relates to an optical device for propagating light rays for a light device, in particular for a motor vehicle, comprising: a light ray propagation guide, at least two collectors each configured to produce, receiving a beam from a light source, an input beam in the guide. This guide is advantageously such that the collectors are configured to focus the input beam, each in a predetermined focusing zone. Thus, it is possible to precisely adjust the shape and the position of the beam coming from each source entering the guide by means of the definition of the adapted focusing zones. Thanks to the invention, the beams of the beam entering the guide are better distributed and, surprisingly, the applicant has found the elimination of hot spots corresponding to areas of the projected beam where the light intensity was abnormally high, generally at the expense of other areas of the beam. Overall, the invention also makes it possible to better control the shape of the beams and to improve the efficiency of the device. It should be noted that, by improving the control of the beams entering the guide, it is possible to multiply the number of sources operating simultaneously without producing a heterogeneous output beam. In an advantageous case, each of the collectors comprises an elliptical profile reflection wall. This elliptical profile (which does not mean that the collector imperatively has a strictly elliptic section-shaped section, profiles similar to "elliptical pseudo" ellipse portions are also suitable in the interpretation to be given to the profile terms elliptic) and the definition of its foci allow to position effectively the source and the projection area. According to another option of the invention, each of the collectors is configured so that all the rays impacting the reflection wall is reflected so as to enter directly into the guide. It is understood that the focusing principle of the invention is a very advantageous element to put into practice this characteristic of entering direct and total rays in the guide. Indeed, the placement of the focusing zone ensures a precise adjustment of the path followed by the rays reflected by the collector. The direct input of the rays reflected by the wall of the collector further has the advantage of preserving, between the collector and the guide, a propagation portion (such as a connection branch between collector and guide) of the spokes in which it there is no impact of rays on the walls. In this way, the shape of this portion, its manufacturing tolerances or other geometrical constraints have no consequences on the optical operation of the device. In addition, the device can receive at this level additional bodies such as fasteners that will not interfere with the beams. According to other optional cases that can be implemented alone or in any combination, the device is such that: the focusing zone is a focusing point; the focusing zone is a line segment directed along the axis of the guide; the focusing zone is a portion of a plane containing the axis of the guide; the reflection wall comprises a plurality of facets; the focusing zone is situated partly in the guide and partly upstream of the guide according to the direction of propagation of the light rays; the focusing areas of the collectors are different; the focusing areas of the collectors are identical; each of the collectors comprises an input diopter with a ray admission cavity of the light beam coming from the source; each of the collectors comprises an input diopter with a curved profile whose outer surface is convex; - The curved profile forms a bottom portion of said cavity, the convexity of the curved profile being directed towards the inside of the cavity; it comprises, for each of the collectors, a branch of propagation of the input beam between the outlet of the collector and the inlet of the guide, so that there are as many branches as collectors; the collectors, the branches and the guide are formed integrally in one piece of a single material; it comprises at least one mechanical fastener integral with a branch; the guide comprises successive prisms along the axis of the guide and configured to produce an output of light rays along the guide; The invention also relates to a light device, in particular for a motor vehicle, comprising an optical device according to the invention. According to one embodiment, this light device comprises an optical device according to the invention and as many light sources as collectors.

According to other optional cases that can be implemented alone or in any combination, the light device according to the invention is such that: the light sources are disposed at the entrance of the cavities of the collectors; the light sources are light-emitting diodes; - The light sources are placed on a printed circuit board (or PCB "Printed Circuit Board"); according to an advantageous embodiment, all the light sources associated with the optical device are on the same printed circuit board. The light device according to the invention can be: - a lighting device of the road still called lighting device (the use of the terms "lighting device" without further specification, is intended for a lighting device of the road , for example a front headlight of vehicle also called headlight, - a signaling device, for example a direction indicator, or a rear position light, or even a position light, or even a diurnal position light still called DRL ("Day Running Light"); - an interior lighting device, namely a device inside the passenger compartment of the vehicle for illuminating the latter to achieve ambient illumination; Another aspect of the invention is a vehicle equipped with at least one device and / or at least one system of the invention as indicated above Other features, objects and advantages of the present invention will appear on reading the description d cut which follows and from the accompanying drawings given as non-limiting examples and in which: - Figure 1 shows an overall perspective view of one embodiment of the invention with two light sources. FIG. 2 illustrates light ray paths in the device of the invention. - Figure 3 shows more particularly the effect of the focus of the invention in the guide. - Figure 4 shows a top view of the example of Figure 1 in a first case of focusing. FIG. 5 shows a view from above of the example of FIG. 1 in a second case of focusing. - Figure 6 reveals a third case of focusing and the formation of facets on the collectors. FIG. 7 shows an embodiment of the invention with three sources. - Figure 8 illustrates a possibility of light output along the guide.

The case shown in the various figures is particularly suitable for installation in a projector at the front of a motor vehicle. In general, the invention makes it possible to couple several light sources 4a, 4b, 4c with an optical guide 1. This coupling is operated in a characteristic manner by means of collectors 2a, 2b, 2c allowing a concentration of the rays in zones predetermined spaces ensuring optimized control of the introduction of rays in the guide. Thus, it is possible to effectively couple a guide 1 and several sources that can operate simultaneously. Indeed, a preferred application of the invention is the formation of a device in which the light sources participate in the realization of the same lighting function. Non-limiting, they may be long-range high beam, or daytime running lights known by the acronym DRL (for Day Running Light). The device of the invention comprises light sources 4a, 4b, 4c mentioned above and whose position is only shown schematically in the figures.

At least one of the light sources 4a, 4b, 4c may consist of one or more light-emitting diodes (LEDs). Moreover, in one embodiment, the sources are arranged relative to the device so as to be located in the same plane as is apparent for example from Figures 4 and 5. This allows to position them on the same control card (such than those known as PCB for Printed Circuit Board). There may be for example two or three sources, as, respectively, in the case of Figures 1 to 6 and Figure 7. In the case of Figure 1, a first source 4a is placed in the immediate vicinity of a first end of a collector 2a described in more detail below.

Similarly, the second source 4b cooperates with an end 5 of a collector 2b. FIG. 2 illustrates more particularly how the rays emitted by a source, 4a in this case, are received by the collector 2a. This figure shows only one source set, collector and connection branch for the sake of simplification. This is also the case in FIG. 3. It is understood that the principle represented for a single source assembly, collector, connection branch can be reproduced for the other sets that comprises the device to be produced. The collector 2a in FIG. 2 carries an input diopter for the rays emitted by the source. This diopter is here formed by the wall of a cavity 5 retreating towards the inside of the collector 2a.

Advantageously, the source 4a is located in a plane where the mouth of the cavity 5 is located. It can be centered on this mouth. The cavity 5 delimits, forming an input diopter, a space for propagation in the air of the rays Rs coming from the source 4a, until the rays Rs impact the wall of the cavity 5. In the illustrated embodiment, this wall comprises two parts. A cavity bottom portion 6 corresponds to the base of the cavity 5 and is opposite the average direction of transmission of the source 2a. It preferably has a curved profile whose convexity is directed towards the cavity 5. It may not be limited to a curvilinear profile such as an arcuate profile. Another part of the wall is a side wall 7 joining the bottom 6 to the mouth of the cavity 5. In the case shown, it is a trapezoidal profile wall in a plane passing through the axis 10 of the guide 1 and of circular section in a plane perpendicular to the axis 10. In the example, the side wall 7 flares in the direction of the mouth of the cavity. On the basis of a radius Rs of the source 4a, a radius R1 is propagated in the collector 2a, by transmission. This radius R1 then impacts a wall 13 of the collector 2a configured to reflect the light so as to form a reflected ray R2. In the case of the invention, the deviations operated by the collector 2a are such that the rays Rs originating from the source are processed so as to produce focused R2 rays. Thus, as can be seen in FIG. 2, the rays R2 converge towards a focusing zone 14. The latter is advantageously positioned so that the rays R 2 enter directly into the guide 1. By this is meant that the rays R 2 do not touch the walls of the intermediate space between collector 2a and guide 1, and in particular, they do not touch the walls of the branches 3a, 3b described in detail later. The focusing zone 14 may be a point as in the example in FIGS. 1 to 4. It may also be a one-dimensional location and in particular a straight line segment as in FIG. the segment is directed along the axis 10 of the guide 1. In a third case revealed by FIG. 6, the focusing zone 14 is two-dimensional, in the form of a portion of a plane which preferably includes the axis 10 of the guide. It is not absolutely necessary for the focusing zone 14 to be located inside the guide 1. Furthermore, the zone 14 may extend partly upstream of the guide 1 and partly in the guide 1. The FIG. 5 presents this possibility. Moreover, a first variant embodiment consists in defining an identical focusing zone 14 for all sources 4a, 4b, 4c. Another variant is to define different focus areas 14 at least between two sources 4a, 4b, 4c.

This variant makes it possible to optimize the spatial distribution of the rays entering the guide and therefore to increase the homogeneity of the output beam. In all cases, the invention makes it possible to finely control the beam, coming from a source 4a, 4b, 4c, entering the guide 1. FIG. 3 illustrates this advantage by schematizing the definition of an incoming beam cone 16. in the guide 1, around an average direction 9a corresponding to the average direction of transmission of the source 4a. To achieve the concentration of the rays by the collectors 2a, 2b, 2c, the figures illustrate a preferred implementation exploiting elliptical reflection surfaces at the walls 13. Overall, the focusing zone 14 corresponds to one of the focal points of a elliptical profile of the wall 13, profile in a plane passing through the axis 10 or parallel thereto. Figures 2 to 6 show an illustration of this profile in vertical section. The source 4a, 4b, 4c is located at another focus of the elliptical profile. The optical system is preferably composed of two focal points, including a source focus and a secondary focus focus. The beams coming from the sources 4a, 4b 4c are refracted by the surfaces 7 and 6. For the beams refracted by the surface 6, these are directly focused on the secondary focus. For the retracted beams of the surface 7, these are then redirected to the surface 2a, then the secondary focus. In a general manner, the wall of the cavity 5 and the reflection wall 13 are arranged so as to produce the focusing in the desired zone 14. In section along a plane perpendicular to the axis 10 or the average direction of emission 9a, 9b, the collectors advantageously have a circular or oval profile. The focusing principle schematized in Figures 2 and 3 is duplicated for as many sets / collectors as necessary. Thus, in FIG. 4, two sources 4a, 4b each emit in a mean direction, respectively 9a, 9b. In the example, these directions are symmetrical with respect to the axis 10 of the guide. In addition this case shows a focus in the same area 14, here punctual. In another variant, with reference to FIG. 7, three sources 4a, 4b, 4c and three collectors 2a, 2b, 2c are used. Preferably, the sources 4a, 4b, 4c are distributed at three points angularly spaced 120 ° in a circle centered on the axis 10 of the guide 1. In another aspect, the invention comprises connecting branches, forming a physical junction between collectors and guide. As indicated above, the invention has the advantage of avoiding any impact of rays between collectors and guide. As a result, the branches 3a, 3b realize only one transmission and are the place of propagation of rays without contact with their wall. The wall of the branches can thus have any shape, as long as it does not interfere with the beams propagated between collectors and guide. The wall of the branches can be used to receive fastening elements (such as attachment tabs) of the device. Due to the convergence of the beams propagating from each source 4a, 4b, 4c, towards the focusing zone, the branches 3a, 3b are also brought to meet. FIG. 6 illustrates another option of the invention in which the reflection wall 13 in the collector 4a, 2b, 2c comprises facets 15. By facets is meant a plurality of flat surfaces or surfaces having a curvilinear longitudinal profile but a straight profile along their width that is to say along a cutting plane perpendicular to the average direction of transmission 9a, 9b of the source. These latter are advantageously juxtaposed according to the periphery of the collectors 2a, 2b, 2c. For example, between 8 and 14 facets can be made. The facets 15 give volume to the focusing area and standardize the output beam. In the illustration, the branches 3a, 3b are also faceted but this is not absolutely necessary because the wall of the branches is not optically active.

The invention also implements a guide 1 which is a part of the optical device for the propagation of light rays. In the case of FIG. 1, it presents a rectilinear shape, but other forms of guides, in particular of the linear type, fall within the scope of the invention. The guide 1 is linear in that it has an elongate shape defined by a longitudinal direction (shown in the examples of the figures by the axis 10 in Figure 2 and 4 in particular) along a variable geometric line according to the chosen configuration. The guide 1 can be rectilinear, follow a convex curvilinear profile as the illustrated curved shape or follow different curves along its length. In a preferred embodiment of the invention illustrated in FIG. 8, along the guide 1, a reflecting surface, provided with prisms 12 successively succeeding one another, makes it possible to reflect certain rays so that they propagate in the guide and other rays with such incidence that they come out of the guide. Thus, progressively along the guide, the rays are reflected so as to leave the guide. The reflection surface provided with prisms is thus designed to generate a beam coming out of a lateral face of the guide 1. It will be noted the particular importance of the homogeneity of the distribution of rays in the guide to produce a good distribution rays issuing along said guide. An advantage of such guides is that their shape may vary, for example with a curvature along the guide, while maintaining a homogeneous appearance of the light emission produced along the guide even when the source is located at one end. The guide 1 may be of circular section so as to adopt a cylindrical envelope or have any other section (elliptical, square or oval for example). Transparent polymers are nonlimitingly suitable for its production and that of the collectors 2a, 2b, 2c and branches 3a, 3b, such as polycarbonate or PMMA (for polymethylmethacrylate). Advantageously, the assembly formed by the collectors 2a, 2b, 2c, the branches 3a, 3b and the guide 1 is in one piece and made in one piece of the same material such as those mentioned above. It can be a part obtained by injection. The invention is not limited to the previously described embodiments but extends to all embodiments in accordance with his spirit.

Claims (19)

REVENDICATIONS1. An optical device for propagating light rays for a light device, particularly for a motor vehicle, comprising: - a light ray propagation guide (1), - at least two collectors (2a, 2b, 2c) each configured to produce, receiving a beam from a light source (4a, 4b, 4c), an input beam in the guide (1), characterized in that the collectors (2a, 2b, 2c) are configured to focus the beam each of which is in a predetermined focusing zone (14). 2. Optical device according to claim 1, wherein each of the collectors (2a, 2b, 2c) comprises a reflection wall (13) elliptical profile. 3. Optical device according to the preceding claim, wherein each of the collectors (2a, 2b, 2c) is configured so that all the rays impacting the reflection wall (13) is reflected so as to enter directly into the guide (1). . 4. Optical device according to one of the preceding claims, wherein the focusing zone (14) is a focus point. 5. Optical device according to one of claims 1 to 3, wherein the focusing zone (14) is a line segment directed along the axis (10) of the guide (1). 6. An optical device according to one of claims 1 to 4 wherein the focusing area (14) is a portion of a plane containing the axis (10) of the guide (1). 7. Optical device according to the preceding claim wherein the reflection wall (13) comprises a plurality of facets (15). 8. Optical device according to one of the three preceding claims wherein the focusing zone (14) is located partly in the guide (1) and partly upstream of the guide (1) in the direction of propagation of light rays. 9. Optical device according to one of the preceding claims wherein the focusing areas (14) of the collectors (2a, 2b, 2c) are different. 10. Optical device according to one of claims 1 to 8 wherein the focusing areas (14) of the collectors (2a, 2b, 2c) are identical. 11. Optical device according to one of the preceding claims wherein each of the collectors (2a, 2b, 2c) comprises an input diopter with a cavity (5) of ray input of the light beam from the source (4a, 4b, 4c). 12. Optical device according to one of the preceding claims, wherein each of the collectors (2a, 2b, 2c) comprises an input diopter with a curved profile whose outer surface is convex. 13. An optical device according to claims 11 and 12 in combination, wherein the curved profile forms a bottom portion (6) of said cavity (5), the convexity of the curved profile being directed towards the inside of the cavity (5). . 14. Optical device according to one of the preceding claims comprising, for each of the collectors (2a, 2b, 2c), a branch (3a, 3b) of propagation of the input beam between the outlet of the collector (2a, 2b, 2c). ) and the entrance of the guide (1). 15. Optical device according to the preceding claim wherein the collectors (2a, 2b, 2c), the branches (3a, 3b) and the guide (1) are formed integrally in one piece of a single material. 16. Luminous device including motor vehicle comprising an optical device according to one of the preceding claims and as many light sources as collectors. 17. Light device according to the preceding claim combined with claim 11 or 13 wherein the light sources are disposed at the entrance of the cavities (5) of the collectors (2a, 2b, 2c). 18. Light device according to claim 18 or 19, wherein the light sources are light-emitting diodes. 19. Light device according to one of the two preceding claims, wherein all the sources are placed on a printed circuit board.