FR3009061A1 - LIGHTING SYSTEM WITH IMPROVED DIFFUSED RADIATION SHAPING - Google Patents

Abstract

This lighting system for a motor vehicle comprises: - at least one primary light source (12) emitting light radiation, called incident radiation (L), and - means (14) for the spatial distribution of the incident radiation (L) to form scattered radiation (D). The spatial distribution means (14) comprise a holographic surface (16) comprising at least one holographic zone dedicated to the spatial distribution of the light radiation according to a volume beam of predetermined shape, the dedicated holographic zone receiving the incident radiation (L) to emit diffused radiation (D) having the shape of the predetermined shape of the volume beam.

Description

FIELD OF THE INVENTION The present invention relates to the technical field of lighting systems for motor vehicles, and more particularly to an illumination system with improved diffused radiation shaping.

Already known in the state of the art, in particular from EP 2 063 170, a lighting system for a motor vehicle comprising: at least one primary light source emitting a light radiation, said incident radiation, and means for spatially distributing the incident radiation to form scattered radiation. In EP 2 063 170, the primary light source is a laser source which may include, for example, a laser diode and collimating optics. A usual laser source for the type of application envisaged in EP 2 063 170 emits a collimated radiation beam with a diameter of, for example, between 0.1 and 2 mm.

Furthermore, in EP 2,063,170, the means of spatial distribution of the incident radiation comprise scanning means receiving the light radiation of the primary light source and distributing it spatially on a wavelength conversion device. The wavelength conversion device comprises a substrate of transparent material on which is deposited a thin layer of phosphorescent material. It will be noted that the skilled person understands by "phosphorescent material" a material having a phosphorescent behavior and constituted by different chemical elements not necessarily containing phosphorus. The scanning means comprise a micromirror movable around two axes.

The light radiation returned by the scanning means passes through the wavelength conversion device which re-emits white light radiation. The lighting system disclosed in EP 2,063,170 further comprises an imaging optical system receiving the white light re-transmitted by the wavelength conversion device and projecting this white light in front of the vehicle to form a beam of light. lighting. In such a lighting system, the wavelength conversion device is located in the vicinity of a focal plane of the imaging optical system. The mobile micro-mirror scanning means are relatively effective but they are part of a complex technology to implement, in particular because it requires complex means for driving and controlling the movement of the micro-mirror. Indeed, it is necessary to control the movement of the micro-mirror around two different axes or to replace the single micro-mirror by two micro-mirrors movable around two respective axes. Moreover, it is necessary to control the movement of each micro-mirror at very high frequencies. The purpose of the invention is to propose a lighting system of the type described above comprising means for spatial distribution of the incident radiation that are simpler to implement than the micro-mirror spatial distribution means, while allowing the where appropriate, effective management of the lighting adaptation of a motor vehicle. For this purpose, the subject of the invention is a lighting system for a motor vehicle comprising: at least one primary light source emitting a light radiation, called incident radiation, and means for spatially distributing the incident radiation to form a radiation diffused, characterized in that the spatial distribution means comprise a holographic surface comprising at least one holographic zone dedicated to the spatial distribution of the light radiation according to a volume beam of predetermined shape, the dedicated holographic zone receiving the incident radiation to emit scattered radiation having the shape of the volume beam of predetermined shape. The holographic zone makes it possible, from a collimated incident radiation, to form a predetermined shape of a volume beam, the predetermined shape of the volume beam being chosen, for example, so as to form a high beam, a dipped beam, a position lamp or any other form of fire adapted to particular driving conditions. The invention thus makes it possible to form a volume beam of predetermined shape with very simple means, without resorting to a scanning micro-mirror and therefore without resorting to means for moving and controlling a micro-mirror. A lighting system according to the invention may further comprise one or more of the following optional features: the holographic surface comprises a plurality of holographic zones each dedicated to the spatial distribution of the light radiation according to a predetermined volume beam, the different holographic zones forming volume beams of different predetermined shapes, the system further comprising means for relative displacement of the incident radiation and the holographic surface; the holographic surface is carried by a rotating disk; - 3 - - the relative displacement means comprising means selected from means for moving the disk in rotation, translational displacement means of the incident radiation and means for translational movement of the disk; the different holographic zones are arranged on different sectors of several concentric rings of the disc; at least one dedicated holographic zone is covered with a prism for orienting the scattered radiation; the predetermined shape of the volume beam is chosen so as to form a high beam, a dipped beam, a sidelamp or any other form of fire adapted to particular driving conditions; the system comprises a wavelength converting device receiving the scattered radiation having the shape of the predetermined shape of the volume beam in order to convert the wavelength thereof; the incident radiation is tuned relative to the wavelength conversion device so as to re-emit white light radiation; the system comprises an optical imaging system for receiving the white light re-transmitted by the wavelength conversion device and for projecting this white light in front of the vehicle to form a lighting beam, the device for converting the light wavelength being located in the vicinity of a focal plane of the imaging optical system; the primary light source comprises a laser source forming a collimated emitted radiation beam with a diameter of between 0.1 and 2 mm. The subject of the invention is also a method for managing the adaptation of the lighting of a motor vehicle, characterized in that the following steps are carried out: the evolution of the rolling conditions of the vehicle is detected, and, by means of a lighting system as defined above, the relative position of the incident radiation and the disk is changed as a function of the evolution of rolling conditions so as to displace the incident radiation on successive holographic zones forming volume beams of predetermined shapes evolving according to the evolution of rolling conditions. This method allows a simple and effective management of the adaptation of the lighting of a motor vehicle.

The invention will be better understood on reading the description which follows, given solely by way of example and with reference to the appended drawings, in which: FIG. 1 is a schematic perspective view of a system of lighting according to the invention; FIG. 2 is a view of a rotating disk carrying the holographic surface of the lighting system shown in FIG. 1; FIG. 3 is a diagrammatic sectional view of the disk shown in FIG. 2 showing holographic zones covered with orientation prisms of the scattered radiation; FIGS. 4 to 6 show successive views illustrating the evolution, thanks to the lighting system illustrated in the preceding figures, of the shape of a lighting beam in function, respectively, of first, second and third conditions of particular driving. FIG. 1 shows a lighting system according to the invention designated by the general reference 10. The lighting system 10 comprises a primary light source 12 of conventional type emitting a light radiation, called incident radiation. The primary light source 12 comprises a laser source formed, in the example described, by a laser diode emitting a light radiation, called laser radiation L, whose wavelength is between 400 nanometers and 500 nanometers, and preferably close 450 or 460 nanometers. These wavelengths correspond to colors ranging from blue to near ultraviolet.

Preferably, the radiation emitted by the laser source forms a collimated beam with a diameter of between 0.1 and 2 mm. The primary light source 12 may, in a variant, comprise an optical device combining in a single beam several laser radiations, for example using optical fibers or devices taking advantage of the different polarizations of different laser sources. The lighting system 12 also comprises means 14 for spatially distributing the incident radiation L to form a scattered radiation D. Referring to FIGS. 1 and 2, it can be seen that the spatial distribution means 14 comprise a holographic surface 16 which, in the illustrated example, is carried by a rotating disc 18, more particularly by a face of this disc 18. The disc 18 is made of a conventional material, for example polymer, in which the holographic surface 16 is formed by a method conventional, for example a method of etching, stamping or injection. In the example illustrated in FIG. 1, the lighting system 10 also comprises a conventional wavelength conversion device 20 receiving the scattered radiation D by the spatial distribution means 14. The incident radiation L, emitted by the light source 12 is tuned to the wavelength conversion device 20 to re-emit white light B radiation. For this purpose, the wavelength conversion device 20 comprises, for example, a substrate of transparent material covered by a thin layer of phosphorescent material. Thus, in a known manner, each point of the phosphorescent material layer of the device 20 receiving the scattered radiation D re-emits, a light radiation of different wavelength, and in particular a light that can be considered as "white", it is that has a plurality of wavelengths between about 400 nanometers and 800 nanometers within the visible light spectrum. This emission of white light occurs according to a lambertian emission diagram, that is to say with a uniform luminance in all directions. In the example shown in FIG. 1, the scattered radiation D by the spatial distribution means 14 passes through the wavelength conversion device 20 which re-emits the white light radiation B. Thus, the device 20 converts the length of the wave of the scattered radiation D (predetermined volume beam). A conventional imaging optical system 22 receives the white light B re-emitted by the wavelength conversion device 20 and projects this white light ahead of the vehicle to form a lighting beam.

Note that the wavelength conversion device 20 is located in the vicinity of a focal plane of the imaging optical system 22. According to a variant not shown, the wavelength conversion device 20 comprises a substrate forming mirror which is covered by the layer of phosphorescent material. Moreover, the spatial distribution means 14 and the imaging optical system 22 are arranged on the same reflecting side of the mirror formed by the substrate. In this variant, the layer of phosphorescent material being deposited on the reflective substrate for the scattered radiation D by the spatial distribution means 14, it is ensured that the scattered radiation D which would not have encountered a grain of phosphorescent material before having completely passed through the layer of phosphorescent material, may encounter a grain of phosphorescent material after being reflected by the reflective substrate. Referring to FIG. 2, it can be seen that the holographic surface comprises several holographic zones Z each dedicated to the spatial distribution of the light radiation L along a predetermined volume beam. Indeed, each dedicated holographic zone receives the incident radiation to emit a scattered radiation D having the shape of the predetermined shape of the volume beam. In the example illustrated in FIG. 1, the incident radiation L passes through the disc 18 -6 and, consequently, the holographic surface 16, a first face of the disc 18 receiving the incident ray L and the second face of the disc 18, opposite. at the first face, emitting the scattered light beam D. Alternatively, the holographic surface 16 could be a reflective surface.

The different holographic zones Z form volume beams of different predetermined shapes. The predetermined shape of each volume beam is selected so as to form a high beam, a dipped beam, a sidelamp or any other form of fire adapted to particular driving conditions. It will be noted that in the example illustrated in FIG. 2, the different holographic zones Z are arranged on different sectors of several concentric rings of the disc 18. The position of a holographic zone Z on the disc 18 is marked in FIG. the torque (An, Bn) in which An indicates the circumferential position of the zone Z on the disk 18 and Bn indicates the radial position of the zone Z on the disk 18.

As a variant, the holographic zones Z could be distributed differently, for example spirally on the disk 18. Preferably, as shown in FIG. 3, at least some dedicated holographic zones Z are each covered with a prism 24 of orientation of the scattered radiation D. The shape of the prism 24 is adapted to the predetermined shape and to the orientation of the volume beam that is to be obtained. It should be noted that the holographic zones Z may have substantially identical or different areas. Of course, according to a very simplified variant, the holographic surface 16 could have only one holographic zone Z dedicated to the spatial distribution of the light radiation according to a single predetermined volume beam. This single holographic zone Z could be covered by a prism 24 for directing the scattered radiation D. The illumination system 10 further comprises means for relative displacement of the incident radiation L and the holographic surface 16.

In the example described, the relative displacement means comprise conventional means 26 for moving the disc 18 in rotation (shown schematically in FIG. 2) and conventional means 28 for translational displacement of the incident radiation comprising means for moving the source primary luminaire 12 (shown schematically in FIG. 1).

In a variant, instead of the translational displacement means 28 of the light source 12, the relative displacement means of the incident radiation L and of the holographic surface 16 could comprise means for translational movement of the disk 18. in case of failure of the lighting system 10, in particular in the event of failure of the relative displacement means of the primary light source 12 and the disk 18, security means may advantageously be provided, for example return means, such as springs, automatically placing the light source 12 and the disk 18 in a relative position forming a beam of scattered light radiation D glare-free, for example forming a dipped beam or a fog lamp. Where appropriate, the lighting system 10 comprises closed-loop control means for controlling the relative position of the primary light source 12 and the disc 18. These control means may comprise in particular patterns reflecting the incident light radiation L arranged on the holographic surface 16 around at least some holographic zones Z. The lighting system 10 according to the invention makes it possible to effectively manage the adaptation of the lighting of a motor vehicle according to the method comprising the following steps: the evolution of rolling conditions of the vehicle is detected, and, by means of the displacement means 26, 28, the relative position of the incident radiation L is evolved as a function of the evolution of rolling conditions. and disk 18 to move the incident radiation L over successive holographic zones Z forming volume beams of predetermined shapes are evolving according to the changing driving conditions. With the displacement means 26, 28 the incident radiation L is moved continuously along adjacent holographic zones Z or in jumps between non-adjacent Z zones. The identical duplication of certain holographic zones Z in different parts of the holographic surface 16 may make it possible to avoid significant leaps in the incident radiation L when it is desired to change the shape of the scattered radiation volume beam D, for example between a first zone Z intended to form a high beam and a second zone Z intended to form a dipped beam, not adjacent to the first zone Z. A driver of a vehicle equipped with the lighting system 10 may control, by for example, the transition from a high beam function to a low beam function by means of a control acting on the displacement means 26, 28 which move the incident radiation L of a first zone Z intended to form a beam. high beam at a second zone Z intended to form a passing beam. FIG. 4 shows different successive views of volume beams of different predetermined shapes obtained by illumination, by the incident radiation L, of different holographic zones Z traversed successively, along the radial arrow F4 (see FIG. 2). on the holographic surface 16, by the incident radiation L. In the case illustrated in FIG. 4, the shapes of the diffuse radiation beam D are changing to take account of the approximation of a first vehicle carrying the lighting system 10 relative to to a second vehicle that precedes it: the non-illuminating notch E of the beam widens as the first vehicle approaches the second vehicle. FIG. 5 shows different successive views of volume beams of different predetermined shapes obtained by illumination, by the incident radiation L, of different holographic zones Z successively traversed, following the circumferential arrow F5 (see FIG. 2) on the surface. 16 in the case illustrated in FIG. 5, the shapes of the diffuse radiation D-volume beams change to take account of the crossing of a first vehicle carrying the lighting system 10 with a second vehicle relatively. remote, the two vehicles being in a relative turn relative to each other: the non-illuminating notch E of the beam is of substantially constant width but moves from right to left.

FIG. 6 shows different successive views of volume beams of different predetermined shapes obtained by illumination, by incident radiation L, of different holographic zones Z successively traversed, along the spiral section arrow F6 (see FIG. 2). on the holographic surface 16, by the incident radiation L.

In the case illustrated in FIG. 6, the shapes of the volume beams of diffused radiation D change to take account of the crossing of a first vehicle carrying the lighting system 10 with a second vehicle: the non-illuminating notch E of the beam 'widens, the closer the first vehicle gets to the second vehicle, and moves from right to left.

The invention is not limited to the embodiment shown. In particular, the optical imaging system 22 is not necessary in some cases, especially when the holographic zones Z directly generate volume beams of predetermined shapes equivalent to those obtained by the optical imaging system 22.

Similarly, the wavelength conversion device 20 is not necessary in certain cases, in particular in the case of a primary light source directly emitting lights of different colors giving in combination a white light formed laser sources of different colors emitting parallel beams (each zone Z is then composed of several adjacent diffractive optics giving a beam of identical shape for the different wavelengths that correspond to them, that is to say for each beam indicant and therefore each laser source) or in the case of a primary light source formed by a low power laser diode whose wavelength does not need to be converted (colored beam, realizing for example a function of signaling).

Claims (6)

REVENDICATIONS1. Lighting system for a motor vehicle comprising: - at least one primary light source (12) emitting light radiation, called incident radiation (L), and - means (14) for spatially distributing the incident radiation (L) to form a diffused radiation (D), characterized in that the spatial distribution means (14) comprise a holographic surface (16) comprising at least one holographic zone (Z) dedicated to the spatial distribution of the light radiation according to a predetermined volume beam, the dedicated holographic zone (Z) receiving the incident radiation (L) for emitting diffused radiation (D) having the shape of the predetermined shape-shaped volume beam. 2. The system of claim 1, wherein the holographic surface (16) comprises a plurality of holographic zones (Z) each dedicated to the spatial distribution of the light radiation (L) according to a volume beam of predetermined shape, the different holographic zones (Z). forming the volume beams of different predetermined shapes, the system further comprising means (26, 28) for relative displacement of the incident radiation (L) and the holographic surface (16). 3. System according to claim 1 or 2, wherein the holographic surface (16) is carried by a rotating disc (18). 4. System claims 2 and 3 taken together, wherein the relative displacement means (26, 28) comprising means selected from means (26) for moving the disc (18) in rotation, moving means (28). in translation of the incident radiation (L) and means for translational movement of the disk (18). 5. System claims 2 and 3 taken together, wherein the different holographic zones (Z) are arranged on different sectors of several concentric rings of the disc (18). 6. System according to any one of the preceding claims, wherein at least one dedicated holographic zone (Z) is covered with a prism (24) for directing the scattered radiation (D). The system according to any one of the preceding claim, wherein the predetermined shape of the volume beam is selected so as to form a high beam, a low beam, a sidelamp or any other form of fire adapted to particular driving conditions. A system according to any one of the preceding claims, comprising a wavelength converting device (20) receiving the scattered radiation having the shape of the predetermined shape-shaped volume beam for converting the wavelength thereof. The system of claim 8, wherein the incident radiation (L) is tuned relative to the wavelength converting device (20) so as to re-emit white light radiation (B). A system according to any one of the preceding claims, comprising an imaging optical system (22) for receiving the white light (B) re-transmitted by the wavelength converting device (20) and projecting the same. white light (B) in front of the vehicle to form a lighting beam, the wavelength converting device (20) being located in the vicinity of a focal plane of the imaging optical system (22). 11. System according to any one of the preceding claims, wherein the primary light source (12) comprises a laser source forming a collimated emitted radiation beam with a diameter of between 0.1 and 2 mm. 12. A method for managing the adaptation of the lighting of a motor vehicle, characterized in that the following steps are carried out: the evolution of the rolling conditions of the vehicle is detected, and, by means of of a lighting system according to claim 2, the relative position of the incident radiation (L) and the disk (18) is changed, depending on the evolution of rolling conditions, so as to displace the incident radiation. (I) on successive holographic zones (Z) forming volume beams of predetermined shapes evolving according to the evolution of rolling conditions. 10