Projector with image plane modal vibration for speckle reduction

• US 9,778,478 B1
• Filed: 10/04/2016
• Issued: 10/03/2017
• Est. Priority Date: 10/04/2016
• Status: Active Grant

• Current Assignee: Christie Digital Systems USA Incorporated (Ushio Incorporated)
• Original Assignee: Christie Digital Systems Incorporated (Ushio Incorporated)
• Inventors: Adema, Daniel Robert, Pastrik, Darren, Hill, Graham
• Primary Examiner(s): Chowdhury, Sultan
• Assistant Examiner(s): Owens, Danell L
• Application Number:
  US15/285,047
• Time in Patent Office: 364 Days
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G03B 21/005 Projectors using an electronic spatial light modulator but not peculiar thereto
• CPC Class Codes: G03B 21/142 Adjusting of projection optics
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light

Abstract

A projector with image plane modal vibration for speckle reduction is provided. The projector includes: a laser light source; a light modulator; and optics that convey light from the laser to the modulator and project modulated light from the modulator, the optics comprising an image plane. The projector further includes: a surface comprising at least a first region located at the image plane, the first region being at least as large as an image formed at the image plane, the first region configured to one or more of transmit and reflect the image; and at least three actuators, positions of interaction of the actuators with the surface are asymmetric relative to the surface, the actuators configured to generate respective moving surface waves in the first region at respective frequencies, the respective frequencies comprising non-integer multiples of each other.

Claims

1. A projector comprising:

a laser light source;

a light modulator;

optics configured to convey light from the laser light source to the light modulator and to project modulated light from the light modulator, the optics comprising an image plane at which an image is formed by the optics by the light from the laser light source;

a surface comprising at least a first region located at the image plane, the first region being at least as large as the image formed at the image plane, the first region configured to one or more of transmit and reflect the image formed at the image plane; and

at least three actuators, positions of interaction of the least three actuators with the surface are asymmetric relative to the surface, the at least three actuators configured to generate respective moving surface waves in the first region at respective frequencies, the respective frequencies comprising non-integer multiples of each other.

2. The projector of claim 1, wherein the respective frequencies further comprise non-harmonics of each other.

3. The projector of claim 1, wherein the positions of interaction of the at least three actuators to the surface are selected to eliminate standing nodes formed by the respective moving surface waves in at least the first region.

4. The projector of claim 1, wherein each of the at least three actuators are configured to change a respective frequency of the respective moving surface waves from a first respective frequency to one or more respective harmonic frequencies.

5. The projector of claim 4, wherein each of the at least three actuators are configured to change the respective frequency of the respective moving surface waves from the first respective frequency to the one or more respective harmonic frequencies and back to the first respective frequency in a sequence.

6. The projector of claim 1, wherein each of the at least three actuators are positioned to interact with the surface outside the first region.

7. The projector of claim 1, wherein each of the at least three actuators comprise an eccentrically mounted rotational motor.

8. The projector of claim 1, wherein the first region is configured to transmit the image formed at the image plane, the surface further comprising a second region connected to the first region, and the positions of interaction of the at least three actuators with the surface are located in the second region.

9. The projector of claim 1, wherein the surface comprises a front side, located at the image plane, and a back side, the first region located on the front side and configured to reflect the image formed at the image plane, the positions of interaction of the at least three actuators to the surface being located the back side.

10. The projector of claim 1, wherein the surface comprises a front side, located at the image plane, a back side, and a second region connected to the first region, the first region located on the front side and configured to reflect the image formed at the image plane, the positions of interaction of the at least three actuators to the surface being located at one or more of the back side and in the second region.

11. The projector of claim 1, further comprising a mounting apparatus, the surface being attached to the mounting apparatus at one or more mount points.

12. The projector of claim 11, wherein each of the one or more mount points comprises a damping apparatus configured to damp one or more of the respective moving surface waves in the first region.

13. The projector of claim 11, wherein each of the one or more mount points is located outside of the first region.

14. The projector of claim 1, wherein the optics comprises an integrating rod located between the laser light source and the light modulator, and the image plane is located to receive images from an output face of the integrating rod such that the first region of the surface changes relative light paths of the light from the laser light source in the images.

15. The projector of claim 1, wherein the surface comprises one or more of glass, high temperature glass, plastic, and high temperature plastic.

16. The projector of claim 1, further comprising a rigid-body vibrating device configured to induce rigid body vibration of the surface.