Illumination device

Patent metadata

Field	Value
Publication number	US-11732860-B2
Application number	US-201816605942-A
Country	US
Kind code	B2
Filing date	Apr 25, 2018
Priority date	Apr 27, 2017
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

Abstract

With a simple configuration, a clear illumination area with suppressed blurring is formed, and a form such as position, shape, and size thereof is changed. Divergent light from a point light source is shaped by a collimating optical system and emitted to a hologram element. Since the point light source is arranged at a front focal position of the collimating optical system, the light emitted from the collimating optical system is emitted to the hologram element as parallel light, and diffracted light therefrom forms an illumination area at a predetermined position on an illumination target surface. A light scanning part rotating about a predetermined rotation axis is arranged between the point light source and the collimating optical system, and light incident on the collimating optical system is scanned. By this scanning, an incident angle of the parallel light incident on the hologram element changes, and the illumination area changes.

First claim

The invention claimed is:

1. An illumination device comprising:
a point light source generation part which generates a point light source;
a diffractive optical element which forms a predetermined illumination area on a predetermined illumination target surface by diffracted light generated by diffracting parallel light incident at a predetermined incident angle;
a collimating optical system which shapes divergent light from the point light source into parallel light; and
a light scanning part which scans light by emitting the incident light while changing a direction of the light,
wherein the point light source, the light scanning part, the collimating optical system, and the diffractive optical element are arranged such that the divergent light from the point light source is incident on the diffractive optical element from one of the light scanning part and the collimating optical system through another,
wherein the collimating optical system is arranged such that a front focal position of the collimating optical system coincides with a position of the point light source,
wherein the incident angle of the parallel light incident on the diffractive optical element is changed by scanning of the light scanning part, and
wherein the diffractive optical element is formed with a diffraction pattern in which at least one of a position, a shape, and an area of the illumination area formed on the predetermined illumination target surface changes according to the change of the incident angle of the parallel light.

2. The illumination device according to claim 1 , wherein
the divergent light from the point light source is given to the collimating optical system through the light scanning part, and the parallel light shaped by the collimating optical system is incident on the diffractive optical element, and
the direction of the light incident on the collimating optical system is changed by the scanning of the light scanning part, and the incident angle of the parallel light incident on the diffractive optical element is changed.

3. The illumination device according to claim 2 , wherein
the light scanning part includes a transmission type scanning body which emits light incident on a first surface from a second surface and a scanning mechanism which performs scanning while rotating the transmission type scanning body about at least one axis, and
the divergent light from the point light source is transmitted through the transmission type scanning body to be directed to the collimating optical system, and a direction of the light transmitted through the transmission type scanning body is changed in at least one direction by the scanning of the scanning mechanism.

4. The illumination device according to claim 2 , wherein
the light scanning part includes a reflection type scanning body having a reflection surface which reflects and emits incident light and a scanning mechanism which performs scanning while rotating the reflection type scanning body about at least one axis, and
the divergent light from the point light source is reflected by the reflection type scanning body to be directed to the collimating optical system, and a direction of the light reflected by the reflection type scanning body is changed in at least one direction by the scanning of the scanning mechanism.

5. The illumination device according to claim 1 , wherein the divergent light from the point light source is given to the light scanning part through the collimating optical system, and the parallel light shaped by the collimating optical system is incident on the light scanning part, and
the incident angle of parallel light incident on the diffractive optical element is changed by the scanning of the light scanning part.

6. The illumination device according to claim 5 , wherein the light scanning part includes a transmission type scanning body which emits light incident on a first surface from a second surface and a scanning mechanism which performs scanning while rotating the transmission type scanning body about at least one axis, and
the parallel light from the collimating optical system is transmitted through the transmission type scanning body to be directed to the diffractive optical element, and a direction of the parallel light transmitted through the transmission type scanning body is changed in at least one direction by the scanning of the scanning mechanism.

7. The illumination device according to claim 5 , wherein a light scanning part includes a reflection type scanning body having a reflection surface which reflects and emits incident light and a scanning mechanism which performs scanning while rotating the reflection type scanning body about at least one axis, and
the parallel light from the collimating optical system is reflected by the reflection type scanning body to be directed to the diffractive optical element, and a direction of the parallel light reflected by the reflection type scanning body is changed in at least one direction by the scanning of the scanning mechanism.

8. The illumination device according to claim 5 , wherein the light scanning part performs periodic scanning in at least one direction, and the incident angle of the parallel light incident on the diffractive optical element changes periodically.

9. The illumination device according to claim 5 , wherein the diffractive optical element is formed with a diffraction pattern of which a diffraction direction changes according to the change of the incident angle of the parallel light.

10. The illumination device according to claim 5 , wherein the diffractive optical element is configured by a hologram element which forms a reproduced image on the predetermined illumination target surface by the diffracted light, and the illumination area is formed by the reproduced image.

11. The illumination device according to claim 10 , wherein an interference fringe of object light from a diffusion plate of a predetermined shape and parallel reference light is recorded in the hologram element, and
wherein when the light scanning part scans the parallel light incident on the hologram element, scanning is performed to increase or decrease a reference angle with an incident angle of the parallel reference light as the reference angle.

12. The illumination device according to claim 11 , wherein the hologram element is a CGH in which the interference fringe obtained by computer calculation is recorded.

13. The illumination device according to claim 11 , wherein the diffractive optical element includes a plurality of element diffractive optical parts, and
wherein each of the element diffractive optical parts forms the same illumination area on the illumination target surface on the basis of parallel incident light incident at a common reference angle.

14. The illumination device according to claim 13 , wherein the diffractive optical element includes the plurality of element diffractive optical parts arranged in a two-dimensional matrix on a predetermined arrangement plane.

15. The illumination device according to claim 5 , wherein the light scanning part has a function of two-dimensionally scanning light by emitting the light while changing a direction of the incident light with respect to two orthogonal directions, and a position of an illumination area formed on the illumination target surface is changed two-dimensionally.

16. The illumination device according to claim 5 , wherein when an aggregate area of a plurality of different illumination areas formed on the illumination target surface is called an illumination zone, the light scanning part performs

Assignees

• Dainippon Printing Co Ltd

Inventors

• Kurashige Makio
• NISHIO Shumpei

Classifications

• F21S41/675 Primary

  by moving reflectors · CPC title

• F21V14/06

  by movement of refractors {(in vehicle head lamps F21S41/635)} · CPC title

• G02B26/0875 Primary

  by means of one or more refracting elements · CPC title

• G02B26/105

  with one or more pivoting mirrors or galvano-mirrors (G02B26/101 takes precedence) · CPC title

• G02B27/425

  in illumination systems (mask illumination systems in photolithographic systems G03F7/70158) · CPC title