SCANNING LIGHT DEVICE, NOTABLY FOR A MOTOR VEHICLE, PROVIDED WITH A LIGHT RAY FOLDING ELEMENT, AND HEADLIGHT COMPRISING SUCH A LIGHT DEVICE

Abstract

The invention relates to a scan light device for a motor vehicle, comprising at least one light source capable of emitting light rays, characterized in that it comprises a wavelength conversion element arranged to receive the light rays on a zone and to re-emit a light radiation to produce a light beam, in that the device further comprises an element for folding the light rays back to the conversion element, and scan means configured to scan the folding element with the light rays in a first direction, the scan of the light rays being performed between extreme positions of these light rays in said first direction, the folding element being configured to deflect the light rays when they are at these extreme positions to a central part of the zone of the conversion element so as to form the central part of the light beam.

Claims

1. Scan light device for a motor vehicle, comprising at least one light source capable of emitting light rays, characterized in that it comprises a wavelength conversion element arranged to receive the light rays on a zone and to re-emit a light radiation to produce a light beam, in that the device further comprises an element for folding the light rays back to the conversion element, and scan means configured to scan the folding element with the light rays in a first direction, the scan of the light rays being performed between extreme positions in said first direction, the folding element being configured to deflect the light rays which are at said extreme positions to a central part of the zone of the conversion element so as to form the central part of the light beam.

2. Light device according to claim 1, wherein the scan of the light rays being performed by passing through central positions of the light rays, said central positions being situated substantially midway between the extreme positions, the folding element is configured to deflect the light rays which are at said central positions to the edges of the zone so as to form the sides of the light beam.

3. Light device according to claim 2, wherein the folding element is configured to: deflect the scanned light rays from a first extreme position to a central position on the zone, such that these deflected light rays scan the zone from said central part of the zone to a first edge of the zone; and deflect the scanned light rays from said central position to a second extreme position opposite the first extreme position on the zone, such that these deflected light rays scan the zone from the central part of the zone to a second edge of the zone opposite the first edge.

4. Light device according to claim 1, wherein the folding element comprises two reflecting faces.

5. Light device according to claim 4, wherein the reflecting faces are adjacent and form a V, the interior of the V being intended to reflect the light rays.

6. Light device according to claim 5, wherein the folding element is arranged in the axis of the scan means such that the vertex of the V receives the central positions of the light rays.

7. Light device according to claim 6, wherein the folding element is a mirror provided with two planes forming the two reflecting faces.

8. Light device according to claim 1, wherein the light device comprises an optical projection system arranged at the output of the device to at least partly produce the light beam.

9. Light device according to claim 1, wherein the light device comprises a mobile secondary mirror arranged between the folding element and the conversion element on the path of the light rays, the secondary mirror being configured to deflect the light rays in a second direction.

10. Device according to claim 1, wherein the folding element is mobile and configured to make the light rays scan in a second direction.

11. Device according to claim 1, wherein the scan means are configured to make the light rays scan in a second direction.

12. Device according to claim 1, wherein the scan means are provided with a mobile micromirror configured to make the light rays scan in the first direction.

13. Device according to claim 1, wherein the conversion element comprises a substrate and a layer of a photoluminescent material, for example comprising phosphorus or yttrium-aluminum-garnet.

14. Device according to claim 1, wherein the light source is at least one laser diode.

15. Motor vehicle headlight comprising a light according to claim 1.

Description

[0039] The invention will be better understood in light of the following description which is given purely as an indication and which is not intended to limit it, accompanied by the attached drawings:

[0040] FIG. 1 schematically illustrating a side view of a first embodiment of a device according to the invention,

[0041] FIG. 2 schematically illustrating the device in plan view, the folding element being a mirror,

[0042] FIG. 3 schematically illustrating a side view of a second embodiment of a device according to the invention.

[0043] FIGS. 1 and 3 represent a light device 1, notably for a motor vehicle, according to a first embodiment and a second embodiment of the invention. The device 1 comprises at least one light source 2 capable of emitting light rays 9. Here, the light source 2 is for example one or more laser diodes. The light source 2 can also comprise an optical device combining several laser radiations, for example using optical fibers or devices exploiting different polarizations of different laser sources. The light device 1 comprises, preferably, one or more lenses 6 for collimating the light rays 9 arranged at the output of the source 2.

[0044] The device 1 also comprises a wavelength conversion element 5 configured to receive the light rays 9 on a zone 10, and to re-emit a light radiation to produce a light beam, not represented in the figures. The conversion element 5 modifies the wavelength of the rays 9 to obtain the desired color for the illumination of the headlight, for example white light. The conversion element 5 is for example provided with a transparent substrate and a layer of a photoluminescent material, for example a phosphorus-based.

[0045] In a first variant, the light rays 9 pass through the conversion element 5, changing color to form the light beam. In a second variant, the conversion element 5 is configured to deflect the light rays 9, the substrate having the properties of a mirror.

[0046] The device 1 is, preferably, provided with an optical projection system, not represented in the figures, which is used to project the light beam from the conversion element to the outside of the device. For that, the optical projection system is arranged substantially in the optical axis of re-emission of the light beam from the conversion element.

[0047] The device 1 further comprises an element 3 for folding the light rays 9 back to the conversion element 5, and scan means 4 configured to scan the folding element 3 with the light rays 9. The scan means 4 receive the light rays 9 from the source 2 and return it to the folding element 3. Thus, the folding element 3 is positioned on the optical path of the light rays 9, between the scan means 4 and the conversion element 5.

[0048] The scan 20 is represented in FIG. 2, which is a plan view of the device 1 of the first embodiment. The scan 20 is performed at a speed that is sufficiently high for the eye not to perceive the scan and for the conversion element to transmit the light rays substantially continuously for the eye. Furthermore, the amplitude of the scan 20 defines the displacement of the light rays 9, and therefore the central positions 14 and extreme positions 12, 13 which they take during the scan 20. The central positions 14 are at the center of the scan 20, and the extreme positions 12, 13 are at the ends of the scan 20.

[0049] It can be seen that the scan 20 is performed in a first direction 18, for example horizontal, so as to obtain a horizontal displacement of the light rays 9 on the zone 10. The rays 9 scan the folding element 3 between two extreme positions 12 and 13. The two extreme positions 12 and 13 of the rays 9 are preferably chosen so that the lit zone 10 covers substantially the entire surface of the folding element 3.

[0050] According to the invention, the folding element 3 is configured to deflect the extreme positions 12, 13 of the light rays 9 to a central part 11 of the zone 10 of the conversion element 5 so as to form the central part of the light beam. The central part 11 is situated substantially in the middle of said zone 10 and is defined here in a first direction of extension of said zone 10. Thus, the extreme positions of the scan 20, for which illumination is more intense because of the movement of the scan means, form the central part of the light beam, the latter consequently having a greater light intensity than the other parts of the light beam.

[0051] Preferably, the folding element 3 is also configured to deflect the central positions 14 of the light rays 9 to the edges 15, 16 of the zone 10 so as to form the sides of the light beam. Thus, the sides of the light beam have a lower intensity than the central part, because the central positions 14 of the scan 20 have a lower intensity than the extreme positions 12, 13.

[0052] The folding element 3 thus makes it possible to invert, in the direction 18 of scan, the distribution of the light intensity produced on the conversion element 5 by the scan means 4 and the light rays 9.

[0053] In the first embodiment of FIG. 2, the folding element 3 is a mirror provided with two planes forming the two reflecting faces 21, 22, which are adjacent and form a V. The vertex 23 of the V forms the junction between the two reflecting faces 21, 22, the interior of the V being intended to reflect the light rays 9 to the conversion element 5.

[0054] The V-shaped mirror is arranged in the axis of the scan means (4) such that the scan 20 of the rays is centered on the mirror, and thus such that the vertex 23 of the V receives and reflects the central positions 14 of the scan 20, whereas the free wings of the V reflect the extreme positions 12, 13. Thus, the central positions 14 of the scan 20 are returned to the two edges 15, 16 of the zone 10.

[0055] In another embodiment, not represented in the figures, the folding element is a prism of which two faces form the two reflecting faces. The prism is configured to operate in the same way as the V-shaped mirror.

[0056] The scan means 4 are for example provided with a mobile micromirror making it possible to scan the folding element 3 by reflection of the light rays 9 to the folding element 3. The scan 20 is performed in a first direction 18 of the surface of the folding element 3, which is for example a horizontal direction. The micromirror is driven by a periodic movement produced by an actuator (not represented), which uses, for example, a resonance effect of the micromirror provoked, for example by electrodes to make it oscillate. The movement of the micromirror is for example worked about an axis of rotation orthogonal to the first direction 18 in order for the light rays 9 to scan the surface of the folding element 3 in said first direction 18.

[0057] In a first variant embodiment of FIG. 1, the folding element 3 is mobile and configured to make the light rays 9 scan in a second direction 24, preferably substantially at right angles to the first direction, in order to produce a movement of the rays which is displaced easily on the conversion element 5. The second direction is for example vertical. Thus, a large zone 10 of the conversion element 5 can easily be scanned by the light rays 9. The movement of the folding element 3 is represented by the arrow 8.

[0058] In a second variant embodiment, represented in FIG. 3, a mobile secondary mirror 7 is used, which can also be a micromirror. It is for example arranged between the folding element 3 and the conversion element 5. The secondary mirror 7 is configured to displace the light rays 9 on the conversion element 5 in the second direction 24. The arrow 17 represents the movement of the secondary mirror 7. The folding element 3 is fixed in this second variant.

[0059] In a third variant embodiment, the scan means 4 are also configured to scan the conversion element 5 with the light rays 9 in the second direction 24. In other words, it is the same micromirror which scans the surface of the folding element 3 with the light rays 9 in both directions 18, 24. The micromirror therefore follows another movement, for example rotational, about a second axis of rotation at right angles to the preceding one. Thus, the micromirror makes it possible for the light rays to scan the conversion element 5 both horizontally and vertically. The folding element 3 is also fixed in this third variant.

[0060] In the above description, the micromirrors mentioned as scan means are for example of MEMS type. However, the invention is in no way limited to this scan means and can use other kinds of scan means such as, for example, a series of mirrors arranged on a rotary element, the rotation of the element generating a scan of the conversion element by the light rays.