LIGHTING DEVICE FOR A VEHICLE, AND METHOD FOR PRODUCING A LIGHTING DEVICE FOR A VEHICLE

Abstract

A lighting device for a vehicle, in particular a headlamp for a vehicle, having at least one light source, from which light emanates during the operation of the lighting device, a diffractive optical unit, including a plurality of gratings, which form a grating cell array, the light passing through the grating cell array during the operation of the lighting device in such a way that a light distribution is created in the outer area of the vehicle, at least one of the gratings of the grating cell array being designed as a volume hologram.

Claims

1. A lighting device for a vehicle, the lighting device comprising: at least one light source, from which light emanates during an operation of the lighting device; and a diffractive optical unit, including a plurality of gratings, which form a grating cell array, the light passes through the grating cell array during the operation of the lighting device such that a light distribution is created in an outer area of the vehicle, wherein at least one of the gratings of the grating cell array is a volume hologram.

2. The lighting device according to claim 1, wherein at least two or each of the gratings of the grating cell array is/are designed as a volume hologram.

3. The lighting device according to claim 1, wherein the at least one volume hologram is a computer-generated hologram.

4. The lighting device according to claim 1, wherein at least two of the gratings of the grating cell array have different inclinations of their Bragg planes.

5. The lighting device according to claim 1, wherein the light emanating from the light source is divergent, in particular the inclinations of the Bragg planes of at least two gratings of the grating cell array are adapted to the divergence of the light of the light source.

6. The lighting device according to claim 1, wherein the optical unit has a curved surface, on which the grating cell array is mounted or into which the grating cell array is introduced, and wherein the inclinations of the Bragg planes of at least two gratings of the grating cell array are adapted to the curvature of the surface.

7. The lighting device according to claim 1, wherein the optical unit includes at least one volume hologram used as a Fresnel lens.

8. The lighting device according to claim 1, wherein the light distribution generated by the lighting device in the outer area of the vehicle is a low-beam light distribution or a high-beam light distribution.

9. A method for manufacturing a lighting device for a vehicle according to claim 1, in particular for manufacturing a headlamp for a vehicle, the method comprising: providing a diffractive optical unit having a plurality of gratings, which form a grating cell array; and providing the at least one of the gratings of the grating cell array is designed as a volume hologram.

10. The method according to claim 9, wherein at least one grating designed as a volume hologram is introduced into a light-sensitive source material by means of an exposure process.

11. The method according to claim 10, wherein an object beam and a reference beam are overlapped on or in the light-sensitive recording material during the exposure process in order to imprint the at least one grating designed as a volume hologram into the source material.

12. The method according to claim 10, wherein a master hologram is exposed during the exposure process, the light emanating from the master hologram impinging on the source material in order to imprint the at least one grating designed as a volume hologram into the source material.

13. The method according to claim 9, wherein the at least one grating designed as a volume hologram is introduced into a source material or applied to a source material by means of a nano 3D printing.

14. The lighting device according to claim 1, wherein the lighting device is a headlamp for a motor vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0019] FIG. 1 shows a schematic view of a detail of an example embodiment of a lighting device according to the invention; and

[0020] FIG. 2 shows a schematic view of a detail of an example embodiment of a lighting device according to the invention.

DETAILED DESCRIPTION

[0021] The example embodiments of a lighting device according to the invention comprise a light source, from which light emanates during the operation of the lighting device. The specific embodiments further comprise a diffractive optical unit 1, including a plurality of gratings 2, which form a grating cell array. Light 3 emanating from the light source passes through the grating cell array in such a way that a light distribution 4 is created in the outer area of the vehicle. In addition to gratings 2, diffractive optical unit 1 may also comprise Fresnel lenses.

[0022] By illuminating the grating cell array, light packets are distributed in such a way that a low-beam light distribution, for example, is created in the target plane, as in the exemplary embodiment according to FIG. 1. For example, three partial light beams 3a, 3b, 3c are drawn in FIG. 1, which emanate from three gratings 2a, 2b, 2c. Parts 4a, 4b, 4c of light distribution 4 generated by the three partial light beams 3a, 3b, 3c are also indicated in FIG. 1.

[0023] Gratings 2 widen light 3 in such a way and deflect it in such a way that desired light distribution 4 is created by superimposing all local widened areas and deflections.

[0024] FIG. 2 shows another possible distribution for generating a symbol projection. A finer resolution of light distribution 4 may also be achieved by increasing the number of gratings 2 of the grating cell array.

[0025] Gratings 2 of the grating cell array are designed as volume holograms. The gratings and possibly the Fresnel lenses are introduced into the source material, for example by means of an exposure process or by nano 3D printing. In particular, the source material may be a light-sensitive photopolymer, into which the grating and possibly Fresnel lenses may be introduced by means of an exposure method, as in holography methods known from the prior art.

[0026] For example, an object beam and a reference beam may thus be overlapped on or in the light-sensitive recording material in order to imprint the gratings and possibly the Fresnel lenses into the source material. Alternatively, a master hologram may also be exposed, the light emanating from the master hologram impinging on the source material in order to imprint the gratings and possibly the Fresnel lenses into the source material.

[0027] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.