PROJECTION-TYPE DISPLAY DEVICES WITH REDUCED SPECKLE

• US 20070195276A1
• Filed: 04/27/2007
• Published: 08/23/2007
• Est. Priority Date: 07/16/2003
• Status: Abandoned Application

• Current Assignee: Transpacific Image LLC (Intellectual Ventures LLC)
• Original Assignee: Transpacific Image LLC (Intellectual Ventures LLC)
• Inventors: Plut, William
• Application Number:
  US11/741,217
• Publication Number:
  US 20070195276A1
• Time in Patent Office: Days
• US Class Current: 353/31
• CPC Class Codes: G03B 21/005 Projectors using an electronic spatial light modulator but not peculiar thereto
• CPC Class Codes: G03B 21/16 Cooling; Preventing overheating
• CPC Class Codes: H04N 9/3141 Constructional details thereof details not peculiar to the presence of an electronic spatial light modulator G03B21/14

Abstract

Described herein are display devices that provide projection-type video output and use lasers to generate light. To reduce any speckle effects for a projected image cast by a projector onto of a non-specular surface, the present invention decreases coherence of the laser-generated light. Coherence reduction is accomplished by introducing a coherence diffuser in a light path of the laser light. Arranging the coherence diffuser in an unfocused light beam reduces both temporal and spatial coherence in the light. Arranging the rotating diffuser at the focus of a beam reduces only the temporal coherence while maintaining the spatial coherence.

Claims

1. A projection-type display device comprising:

a set of lasers for producing light;

a coherence diffuser arranged to intercept light produced by the set of lasers and to reduce coherence in the light;

an optical modulation device for selectively transmitting light produced by the set of lasers according to video data included in a video signal provided to the optical modulation device;

an optics system, arranged to receive light produced by the set of lasers before receipt by the optical modulation device, configured to increase flux area of the light produced by the set of lasers; and

a projection lens system for projecting light transmitted by the optical modulation device along a projection path.

2. The display device of claim 1 wherein the coherence diffuser reduces temporal coherence in the light produced by the set of lasers.

3. The display device of claim 2 wherein the coherence diffuser is arranged to intercept light at a focal location of the light produced by the set of lasers.

4. The display device of claim 1 wherein the coherence diffuser reduces both temporal and spatial coherence in the light produced by the set of lasers.

5. The display device of claim 4 wherein the coherence diffuser is arranged to intercept light at a location where the light produced by the set of lasers is not focused.

6. The display device of claim 1 wherein the coherence diffuser includes a transparent member that is moved in an optical path of the light produced by the set of lasers.

7. The display device of claim 6 wherein the coherence diffuser comprises a transparent glass or plastic screen that is moved by a coherence diffuser motor.

8. The display device of claim 1 wherein the set of lasers includes a plurality of red lasers for producing light including a wavelength between about 615 nanometers and about 690 nanometers.

9. The display device of claim 1 wherein the set of lasers includes a plurality of blue lasers for producing light including a wavelength between about 420 nanometers and about 500 nanometers.

10. The display device of claim 1 wherein the set of lasers includes a plurality of green lasers for producing light including a wavelength between about 510 nanometers and about 570 nanometers.

14. The display device of claim 10 wherein one of the set of red lasers, the set of green lasers and the set of blue lasers include a diode laser.

11. A projection-type display device comprising:

a set of red lasers for producing light including a wavelength between about 615 nanometers and about 690 nanometers;

a set of green lasers for producing light including a wavelength between about 510 nanometers and about 570 nanometers;

a set of blue lasers for producing light including a wavelength between about 420 nanometers and about 500 nanometers;

a coherence diffuser arranged to intercept light produced by the set of red lasers, intercept light produced by the set of green lasers and intercept light produced by the set of blue lasers, and adapted to reduce coherence in the light produced by the set of red lasers, reduce coherence in the light produced by the set of green lasers and reduce coherence in the light produced by the set of blue lasers;

an optical modulation device configured to selectively transmit light according to video data included in a video signal provided to the optical modulation device;

an optics system, arranged to receive light produced by the set of red lasers, the light produced by the set of green lasers and the light produced by the set of blue lasers before receipt by the optical modulation device, and configured to increase flux area of the light produced by the set of red lasers, the light produced by the set of green lasers and the light produced by the set of blue lasers; and

a projection lens system configured to project light transmitted by the optical modulation device along a projection path.

12. The display device of claim 11 wherein the coherence diffuser reduces both temporal and spatial coherence in the light produced by the set of red lasers, light produced by the set of green lasers and light produced by the set of blue lasers.

13. The display device of claim 11 wherein the display device comprises a common optical path that sequentially transmits light produced by the set of red lasers, light produced by the set of green lasers and light produced by the set of blue lasers, and wherein the coherence diffuser is arranged to intercept light along the common optical path.

15. A method for producing an image using a projection-type display device, the method comprising:

producing light using a set of lasers;

reducing coherence in the light using a coherence diffuser arranged to intercept light produced by the lasers;

increasing flux area of the light produced by the lasers before transmission onto an optical modulation device;

selectively transmitting light produced by the lasers according to video data included in a video signal provided to the optical modulation device; and

outputting light transmitted by the optical modulation device along a projection path.

16. The method of claim 15 wherein the set of lasers includes a diode laser.

17. The method of claim 15 wherein reducing coherence in the light comprises reducing temporal coherence in the light.

18. The method of claim 17 wherein the coherence diffuser is arranged to intercept light at a focal location of the light produced by the lasers.

19. The method of claim 15 wherein reducing coherence in the light comprises reducing both temporal and spatial coherence in the light.

20. The method of claim 19 wherein the coherence diffuser is arranged to intercept light at a location where the light produced by the lasers is not focused.