Methods and apparatus for spatial light modulation

• US 7,391,552 B2
• Filed: 10/11/2006
• Issued: 06/24/2008
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Pixtronix, Incorporated (Qualcomm, Inc.)
• Inventors: Barton, Roger W., Hagood, Nesbitt W.
• Primary Examiner(s): Choi; William C
• Application Number:
  US11/546,937
• Publication Number:
  US 20070030555A1
• Time in Patent Office: 622 Days
• Field of Search: 359/247, 359/261, 359290-292, 359/295, 359/298, 359/302, 359/317, 359/233, 349/66, 349/67
• US Class Current: 359/290
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0078 Side-by-side arrangements, e.g. for large area displays

Abstract

Improved apparatus and methods for spatial light modulation are disclosed which utilize optical cavities having both front and rear reflective surfaces. Light-transmissive regions are formed in the front reflective surface for spatially modulating light.

Claims

1. A method of forming an image, comprising:

introducing light into a reflective optical cavity including a plurality of light-transmissive regions through which light can escape the reflective optical cavity;

allowing the introduced light to escape the reflective optical cavity through at least one of the light-transmissive regions;

providing a plurality of light modulators, each having at least first and second states, wherein, in the first state, a light modulator obstructs a corresponding light-transmissive region thereby preventing light introduced into the reflective optical cavity from illuminating an image pixel that corresponds to the light-transmissive region, and in the second state, the light modulator allows light escaping the reflective optical cavity through the corresponding light-transmissive region to illuminate the image pixel corresponding to the light-transmissive region; and

forming an image by selectively controlling the states of the plurality of light modulators.

2. The method of claim 1, comprising distributing the introduced light substantially evenly throughout the reflective cavity.

3. The method of claim 1, wherein introducing the light comprises alternately illuminating a plurality of different colored light sources.

4. The method of claim 1, wherein the selectively controlling the state of a light modulator comprises altering a voltage applied to a light modulator.

5. The method of claim 4, wherein the light modulator comprises a MEMS-based shutter assembly.

6. The method of claim 4, wherein the light modulator comprises a liquid crystal component.

7. The method of claim 1, comprising selectively reflecting ambient light impinging on the corresponding ones of the light-transmissive regions through which the introduced light is allowed to escape.

8. The method of claim 1, wherein at least one light-transmissive region comprises an aperture.

9. The method of claim 8, wherein the reflective optical cavity comprises a first reflective surface and a second reflective surface at least partially facing the first reflective surface, and wherein the aperture is formed into the surface of the first reflective surface.

10. The method of claim 1, wherein at least one light-transmissive region comprises a filter.

11. The method of claim 1, wherein at least one light-transmissive region comprises a liquid crystal component.

12. The method of claim 1, wherein the reflective optical cavity comprises a first reflective surface including the plurality of light-transmissive regions and a second reflective surface at least partially facing the first reflective surface.

13. The method of claim 1, comprising introducing the introduced light into a light guide substantially contained within the reflective cavity.

14. The method of claim 1, wherein the light modulator comprises a MEMS-based light modulator.

15. The method of claim 1, wherein in the first state, the light modulator obstructs the corresponding light transmissive region by at least partially filtering light escaping the reflective optical cavity through the corresponding light-transmissive region.

16. The method of claim 1, wherein in the first state, the light modulator obstructs the corresponding light transmissive region by at least partially blocking light escaping the reflective optical cavity through the corresponding light-transmissive region.

17. The method of claim 1, wherein in the first state, the light modulator obstructs the corresponding light transmissive region by at least partially deflecting light escaping the reflective optical cavity through the corresponding light-transmissive region.

18. A method of forming an image, comprising:

introducing light into a reflective optical cavity including a first reflective surface in which a plurality of apertures corresponding to respective display pixels in multiple rows and columns of the image are formed and a second reflective surface at least partially facing the first reflective surface; and

forming an image by allowing the introduced light to escape the reflective optical cavity through at least one of the apertures to illuminate respective corresponding display pixels.

19. The method of claim 18 wherein the first reflective surfaces comprises a mirror.

20. The method of claim 18 wherein the first reflective surfaces comprises a metallic layer.

21. The method of claim 18 wherein the first reflective surfaces comprises a dielectric layer.

22. The method of claim 18 comprising providing a plurality of light modulators corresponding to respective display pixels.

23. The method of claim 22 wherein forming an image comprises selectively controlling states of the plurality of light modulators.

24. The method of claim 22 wherein the light modulators have at least a first and second state, wherein, in the first state, a light modulator obstructs a corresponding aperture thereby preventing light introduced into the reflective optical cavity from illuminating an image pixel that corresponds to the aperture, and in the second state, the light modulator allows light escaping the reflective optical cavity through the corresponding aperture to illuminate the image pixel corresponding to the aperture.

25. The method of claim 22 wherein the light modulators comprise MEMS-based light modulators.

26. The method of claim 22 wherein the light modulators comprise a liquid crystal component.

27. The method of claim 22 wherein the light modulators are separated from the first reflective surface by a gap, which is less than or equal to about 100 μ

m wide.

28. The method of claim 18, wherein light escaping the reflective optical cavity passes through a filter.

29. The method of claim 18, comprising introducing the introduced light into a light guide substantially contained within the reflective cavity.

30. The method of claim 18, wherein introducing the light comprises alternately illuminating a plurality of different colored light sources.