FR2939868A1 - Optical system for head light or signaling light of motor vehicle, has light source propagated in single diffusion screen, and insulating separating film separating functions for realization of multiple main optical functions through screen - Google Patents

Abstract

The system (100) has a light source (111) propagated in a single diffusion screen (110), where the light source produce luminous rays. An insulating separating film (112) separates the functions for realization of multiple main optical functions through the screen. The screen diffuses a light beam via multiple reduced surface zones having an assembly of micro-asperities or a specific optical surface. The optical surface disperses a part of luminous rays being propagated in the screen towards the outside of the screen. The light source is formed by multiple LEDs of different colors. The main optical functions include functions of stop, lantern, direction indicator, backup light, fog light, side marker, or side repeater.

Description

The present invention relates to an optical system for a motor vehicle. By optical system means an element forming part or all of a lighting or signaling device for a motor vehicle, having at least one light source and means for producing at least one optical function; by optical function means the production of a regulatory light beam for the realization of some of the projectors or lights mentioned below. The field of the invention is, in general, that of projectors or motor vehicle lights. In this field, we know different types of projectors, among which we find essentially: - position lights, intensity and low range; - low beam, or codes, of higher intensity and range on the road close to 70 meters; - long-range headlamps and long-range headlamps with an area of vision on the road of approximately 200 meters; advanced projectors, called dual mode, which combine the functions of low beam and high beam by incorporating a removable cover; fog lights; - signaling lamps, in particular front and rear direction indicators, reversing lights, lanterns or night lights, lateral warning devices such as those known as side markers for traffic lights, lateral or side repeater positions for lateral return lights; diurnal position light signaling devices, called DRL devices (for Daytime Running Light in English) ... The field of application of the invention is essentially that relating to stop lights, direction indicators, lantern or DRL.

For all these projectors and lights, traditionally, we use light sources such as halogen lamps, or type discharge lamps. But in recent years, automotive suppliers have proposed the use of light-emitting diodes, also called LEDs; this use is for example traffic lights or taillights. Electroluminescent diodes have a number of advantages. First, for a long time, it is known that this type of diode does not radiate omnidirectionally, but radiates in a half space opposite to a substrate that supports the P-N junction of the diode considered; thus, using a more directional radiation, the amount of energy lost is less important than with discharge lamps or halogen lamps. Then, these diodes have recently been perfected in terms of power (or power level) of radiation. In addition, the diodes manufactured emit radiation for a long time in the red, but now also in white and orange, which increases the scope of their possible uses. The amount of heat they release is relatively limited, and a number of constraints, related to heat dissipation, however, remains important for power LEDs. Finally, LEDs consume less energy, even at equal radiated power, than discharge lamps or halogen lamps; they are compact, and their particular shape offers new possibilities for the realization and arrangement of the complex surfaces associated with them, in particular by arranging them on electronic supports of the flexible electronic support type.

More and more, especially to meet the aesthetic criteria desired by car manufacturers, the use of LEDs has grown. This use makes it possible, in particular, to produce projection devices presenting original volumes, for example by placing the LEDs three-dimensionally, that is to say on a non-planar support substrate, within the projectors considered, or else using elements of light guide type. Furthermore, optical systems have recently been proposed in which different LEDs were specifically used to make a light curtain by means of a screen internal to the optical systems, in which the light produced by the diode or the diodes propagates. The term "light curtain" designates an illuminated surface of a portion of an optical system, the illumination being produced by light rays circulating inside a volume defined in particular by the illuminated surface. Advantageously, the illumination produced is as continuous as possible, without the effect of pixelation. In recently proposed optical systems, the illumination by means of the LEDs by light curtain made it possible to achieve a main optical function of the stoplight type, or lantern or direction indicator. However, known optical systems propose to perform only one main function, forcing the automotive supplier to assemble several optical systems in order to achieve a set of main functions constituting an optical unit of a motor vehicle; this set of optical systems generally occupying a large volume and being poorly optimized. For this purpose, the object of the invention proposes a solution to the disadvantages which have just been exposed. Thus in the invention, there is provided an optical system for a motor vehicle carrying out a main optical function and comprising in particular: a single diffusion screen; at least one light source of LED type, each LED of said optical system producing a set of light rays propagating in said diffusion screen; said optical system having function separation means for performing a plurality of optical functions by said single broadcast screen. Optical system means an element forming part or all of a projector device, having at least one light source and means for producing at least one optical function; by main optical function is meant the production of a regulatory light beam for the realization of some of the lighting or signaling devices mentioned above. In addition to the main features mentioned above, the optical system for a motor vehicle, according to the invention, may have one or more additional characteristics below, considered individually or in any technically possible combination: said single broadcast screen diffuses a light beam via a plurality of reduced surface areas having a set of micro-asperities or a specific optical surface capable of dispersing outwardly of said diffusion screen at least a portion of the light rays propagating in said diffusion screen; said surfaces, particularly in the form of disks, have a diameter of between two tenths of a millimeter and six tenths of a millimeter, typically four tenths of a millimeter; said plurality of main optical functions performed comprises the functions of the stop type, of the lantern type, of the direction indicator type, of the reversing light type, of the fog lamp type, of the side marker type, or of the side repeater type; said separation means for carrying out a plurality of main optical functions are formed by slots locally modifying the direction of the light rays in said diffusion screen; said separation means for carrying out a plurality of main optical functions are formed by optical means redirecting said set of light beams into said diffusion screen substantially parallel to the optical axis of said LEDs projected onto the surface. said separation means for carrying out a plurality of main optical functions are formed by a separating film modifying at least one direction of propagation, the incidence of light rays; said separator film is a film that reflects all or part of the wavelengths of the light sources of the system; said separator film is a film absorbing certain wavelengths of the light sources; said at least one light source is formed by a plurality of LEDs of different colors. The present invention also relates to a headlamp or a signaling light of a motor vehicle equipped with an optical system according to the invention, with its main characteristics, and possibly one or more additional features just mentioned.

Other features and advantages of the invention will emerge more clearly from the description which is given below, by way of indication and in no way limiting, with reference to the appended figures, among which: FIGS. 1-A, 1-B and 1-C illustrate different schematic representations of a first exemplary embodiment of an optical system according to the invention; FIG. 2 illustrates a schematic representation of a second exemplary embodiment of an optical system according to the invention; - Figures 3-A and 3-B illustrate different schematic representations of a third embodiment of an optical system according to the invention.

The different elements appearing in several figures will have kept, unless otherwise specified, the same reference. FIGS. 1-A, 1-B and 1-C show a first exemplary embodiment of an optical system according to the invention respectively illustrating a first off aspect, a second aspect and a third aspect of the optical system performing different main functions. . The various figures show schematically the optical system, according to the invention, as it is visible by an observer placed at the rear of a vehicle equipped with the optical system in question. In these figures, the optical system 100 according to the invention is formed by a diffusion screen 110 and a plurality of LEDs 111 producing light rays intended to propagate in the diffusion screen 110. The diffusion screen 110 is made of a transparent plastic material, in particular of the polymethyl methacrylate type, also called PMMA (for Polymethyl methacrylate) or PC (for Polycarbonate) with high transmission. The diffusion screen 110 is characterized by a front face 101, a rear face 102, these two faces being linked by a periphery 103, having a lower edge 104, an upper edge 105, a first lateral edge 106 and a second lateral edge. 107. The front face 101 is the face of the optical system directly visible by an observer placed facing the optical system in question.

Advantageously, the LEDs 111 are all arranged on the same plane substrate, not shown, which ensures their maintenance and control. The LEDs 111 are arranged opposite the lower edge 104, for example, at which the light rays they produce enter the diffusion screen 110. The light rays thus propagate in the volume defined by the broadcast screen 110, to exit the broadcast screen 110 at the front face 101 where at least one main optical function is performed. For this, the diffusion screen 110 consists of a plurality of minidisks (not shown), with diameters between 2 and 6 tenths of a millimeter, allowing, thanks to the micro-asperities they present, to diffuse towards the outside the diffusion screen 110 through the front face 101, at least a portion of the light rays. To describe such a diffusion surface, we often speak of a micro-optical surface. According to this first exemplary embodiment of the invention, the diffusion screen 110 comprises a separator film 112 inserted in the diffusion screen 110 during its manufacture by injection. The separator film 112 makes it possible to separate the volume of the diffusion screen 110 into a plurality of volumes defining zones for the realization of the different optical functions; the separator film 112 particularly insulating a central area 113 of the light rays of the diffusion screen 110 in the illustrated embodiment. The separator film 112 is a reflective film isolating the central zone 113 from the rest of the diffusion screen 110, thus creating a first peripheral zone 114 and a second peripheral zone 115. Thus, the light rays, emitted by one or more central LEDs. of the plurality of LEDs 111, are confined and reflected within the central zone 113 delimited by the separator film 112. Advantageously, the separator film 112 is a flexible plastic film aluminized or metallized reflecting all the incident rays. Thus, by integrating into the optical system 100 a plurality of LEDs of different colors, typically the usual red, orange or white colors, it is possible to obtain separate colored areas, performing different main optical functions. These optical functions are made from a single diffusion screen 110, and have no unsightly visual discontinuity between the different zones when the LEDs are off.

According to another embodiment, the separator film 112 is a color film filtering the unwanted color, the color film being able to filter the light rays of only one of the red or amber colors only, for example the orange light rays emerging from the central area 113.

Figure 1-A particularly illustrates a first aspect of the optical system 100 visible by an observer when the LEDs are off, the observer then seeing only one diffusion screen without discontinuity. FIG. 1-B particularly illustrates a second aspect of the optical system 100 producing a lantern main function at the periphery of the diffusion screen, in the peripheral zones 114 and 115, and a principal direction indicator function in the central zone 113; the main lantern function is realized by means of red LEDs and the main direction indicator function is realized by means of orange LEDs. FIG. 1-C particularly illustrates a third aspect of the optical system 100 producing a lantern main function at the periphery of the diffusion screen, in the peripheral zones 114 and 115, and of a main brake light function in the central zone 113 ; the main lantern function and the main brake light function being realized by means of red LEDs. The difference in light intensity between the lantern function and the stop light function is achieved, for example, by the use of higher class diodes or simply by increasing the area illuminated by the LEDs reserved for the fire function. stop. FIG. 2 shows a second exemplary embodiment of an optical system 200 according to the invention. FIG. 2 diagrammatically illustrates the optical system 200, according to the invention, directly visible by an observer placed in front of the optical system in question. In this second embodiment, the optical system 200 has the same characteristics, unless otherwise specified, as the optical system 100 described above.

In FIG. 2, the optical system 200 according to the invention is formed by a diffusion screen 210 and by a plurality of LEDs 111 producing light rays intended to propagate in the diffusion screen 210.

According to this second exemplary embodiment of the invention, the diffusion screen 210 comprises thin air slots 212 and 211 inserted inside the volume formed by the diffusion screen 210 during its manufacture by injection.

The thin air slots 212 and 211 make it possible to separate the light rays propagating inside the volume of the diffusion screen 210 in a plurality of volumes corresponding to the zones 215, 216 and 217 of the diffusion screen 210. ; the thin air slots 212 and 211 confining, for example, the light rays propagating in the central zone 217 of the diffusion screen 210.

By the refractive index change due to the air present in the thin air slots 212 and 211, the light rays propagating, for example in the central zone 217, are reflected totally, by total reflection, on the walls. lateral to the central zone 217 so as to remain confined inside the central zone 217. The total reflection of the light rays inside the central zone 217 is made possible for light rays having a higher angle of incidence. at a critical value. Typically, the critical angle of refraction is given by the equation 6, ,,, = Aresin (n- '), where n1 and n2 are respectively the refractive indices of a medium 1 and a medium 2 , the light ray passing from the middle 1 to the middle 2.

Similarly, the light rays propagating in the peripheral zones 216 and 217 are totally reflected on the side walls of the peripheral zones 215 and 216.

The different zones 215, 216 and 217 are separated from each other at least partially by a thin air slot 211, 212; said thin air slot 211, 212 not extending to the ends of the diffusion screen 210 so that the different zones 216, 215 and 217 comprise mechanical links between them.

The diffusion screen 210 comprises a lower part 218, which is not visible by an observer placed facing the optical system in question, in which collimators 213 are arranged opposite the LEDs 111 thus forming a so-called optical input optics. collimation.

By optical collimation means an optical device for obtaining a beam of light rays of reduced divergence in projection on the surface 101 relative to the natural opening of the beam from the source. The lower part 218 is a part of the diffusion screen 210 preferably made during the injection of the diffusion screen 210. However, in order to simplify the embodiment of the lower part 218, it is possible to realize said lower portion 218 without presence of micro-asperities. This second embodiment of the invention makes it possible to use known collimators having the particularity of actually being slightly divergent because the light source is not a point source. Thus, slightly divergent light rays coming out of the input optics are reflected on the sidewalls of the considered areas. To further simplify the optical system according to the invention, it is possible to dispense with the use of collimators previously described in the lower part 218. However, in order to have light rays having angles of incidence required to obtain a total reflection of the rays incident on the walls of the zones 215, 216 and 217, it is necessary to have a lower part 218 of a relatively large height in order to eliminate the parasitic light rays not having the good incident angles. Finally, this lower portion 218 is necessarily a masked area, not visible by the observer, for example by means of an opaque plastic part, because of its potentially highly inhomogeneous appearance. By integrating into the optical system 200 a plurality of LEDs of different colors, typically the usual red, orange or white colors, it is possible to obtain separate colored areas, performing different main optical functions, from the single screen of diffusion 210, and not having unsightly visual discontinuity between the different areas when the LEDs are off. FIG. 2 particularly illustrates an aspect of the optical system 200 producing a lantern main function at the periphery of the diffusion screen, in the peripheral zones 215 and 216, and a principal direction indicator function in the central zone 217; the main lantern function being realized by means of red LEDs and the main function direction indicator being realized by means of amber LEDs.

Figures 3-A, 3-B show a third embodiment of an optical system 300 according to the invention. The various figures schematically illustrate the optical system 300, according to the invention, directly visible by an observer placed facing the optical system in question.

In this third embodiment, the optical system 300 has the same characteristics, unless otherwise specified, as the optical systems 100 and 200 described above. In the various figures, the optical system 300 according to the invention is formed by a diffusion screen 310 and by a plurality of LEDs 111 producing light rays intended to propagate in the diffusion screen 310. According to this third exemplary embodiment of the invention, the optical system 300 comprises an input optic 311 located in a lower part 312 of the diffusion screen 310. In this third embodiment, the separation of the light rays in the diffusion screen 310, performing different main optical functions, is performed only by means of the input optics 311 and its mode of injection of the light rays emitted by the plurality of LEDs 111. For this purpose, the input optics 311 is formed by a plurality of collimation optics 313 disposed opposite each LEDs 111; the collimation optics 313 for returning the light rays emitted by the LEDs parallel to the optical axis of said LEDs 111. Thus, the collimation optics 313 separate the light rays coming from different LEDs in order to create several main optical functions by means of a single broadcast screen 310.

For this purpose, FIG. 3-B illustrates an illuminated appearance of the optical system 300 realizing a flashing main function in a central zone 316. The light rays coming from the central LED are confined within the central zone 316 and do not propagate not in the peripheral areas 317 and 318 of the broadcast screen.

On the other hand, FIG. 3-A illustrates more particularly the diffusion screen 310 when the LEDs 111 are off; in this state, the broadcast screen 310 has no visual element allowing an observer to view the location of the different main optical functions. This characteristic makes it possible to bring a particular signature to the vehicle.

However, the light source, that is to say the plurality of LEDs 111, is not punctual, some light rays do not propagate perfectly parallel to the mounting axis of the LEDs 111, preventing a clear separation different areas 316, 317, 318 performing different optical functions. In order to remedy this problem, the collimators 313 are advantageously collimating optics comprising eccentric foci slightly offset on the edges of the light source and symmetrical with respect to an axis of symmetry corresponding to the mounting axis of the LEDs, so that a part of the collimated light rays are initially convergent then divergent. Thus, the path of the light rays is mastered inside the diffusion screen 310. Thus, according to the invention, the optical system for a motor vehicle makes it possible, within a single homogeneous diffusion screen, to provide a plurality of functions. different light optics. The different optical functions are performed separately without the light rays of an optical function interfering with the light rays of a second optical function. The optical system according to the invention also makes it possible to increase the styling effect of the vehicle by providing homogeneous vehicle optics without permanent visual separation of the optical functions. The invention has been particularly described for a planar broadcast screen; however, the invention is also applicable to all forms of diffusion screen such as for example those having a curved shape.

Claims (12)

REVENDICATIONS1. Optical system (100, 200, 300) for a motor vehicle performing a main optical function and comprising in particular: - a single diffusion screen (110, 210, 310); at least one LED light source (111), each LED of said optical system (100, 200, 300) producing a set of light beams propagating in said diffusion screen (110, 210, 310); said optical system (100, 200, 300) being characterized in that it comprises means (112, 211, 212, 213, 313) for separating functions for carrying out a plurality of main optical functions through said single broadcast screen (110, 210, 310). 2. Optical system (100, 200, 300) for a motor vehicle according to the preceding claim characterized in that said single diffusion screen (110, 210, 310) diffuses a light beam via a plurality of reduced surface areas having a set of micro-asperities or a specific optical surface, able to disperse to the outside of said diffusion screen (110, 210, 310) at least a portion of the light rays propagating in said diffusion screen (110, 210, 310). 3. optical system (100, 200, 300) for a motor vehicle according to claim 2 characterized in that said optical surfaces of reduced size are disks having a diameter between two tenths of millimeters and six tenths of millimeters, typically four tenths of millimeters. 4. Optical system (100, 200, 300) for a motor vehicle according to one of claims 1 to 3 characterized in that said plurality of main optical functions performed comprises stop type functions, lantern type, direction indicator type , of the reversing light type, the fog lamp type, the side marker type, or the side repeater type; 5. optical system (200) for a motor vehicle according to one of claims 1 to 4 characterized in that said means (211, 212) for separating for the realization of a plurality of main optical functions are formed by locally modifying slots the direction of the light rays in said diffusion screen (210). 6. optical system (200, 300) for a motor vehicle according to one of claims 1 to 5 characterized in that said means (213, 313) of separation for the realization of a plurality of main optical functions are formed by means optical redirecting said set of light beams in said diffusion screen (210, 310) substantially parallel to the optical axis of said LEDs projected onto the surface (110). 7. optical system (100) for a motor vehicle according to one of claims 1 to 4 characterized in that said means (112) for separating for the realization of a plurality of main optical functions are formed by a separator film modifying at least in a direction of propagation, the incidence of light rays. 8. optical system (100) for a motor vehicle according to claim 7 characterized in that said separator film (112) is a film reflecting all or part of the wavelengths of the light sources of the system. 9. optical system (100) for a motor vehicle according to claim 7 characterized in that said separator film (112) is a film absorbing certain wavelengths of the light sources of the system 30 10. optical system (100, 200, 300) for a motor vehicle according to one of claims 1 to 8 characterized in that said at least one light source (111) is formed by a plurality of LEDs of different colors. Optical system (100, 200, 300) for a motor vehicle according to claim 10, characterized in that the LEDs have colors that can be individually modified by means of a suitable control. 12. Projector or traffic signal of a motor vehicle characterized in that it is equipped with the optical system (100, 200, 300) according to one of claims 1 to 11.