Methods and apparatus for spatial light modulation

• US 7,619,806 B2
• Filed: 11/06/2006
• Issued: 11/17/2009
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Pixtronix, Incorporated (Qualcomm, Inc.)
• Inventors: Payne, Richard S., Steyn, Jasper Lodewyk, Hagood, Nesbitt W. IV
• Primary Examiner(s): Choi; William C
• Application Number:
  US11/594,042
• Publication Number:
  US 20070091038A1
• Time in Patent Office: 1,107 Days
• Field of Search: 359/197, 359/198, 359/223, 359/224, 359/230, 359/233, 359/290, 359/291
• 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 display apparatus comprising:

an array of MEMS-based light modulators;

a liquid in which the array of MEMS-based light modulators is at least partially immersed, and

a transparent substrate on which the array of MEMS-based light modulators are formed, wherein the liquid has a first index of refraction, the transparent substrate has a second index of refraction, and the first index of refraction substantially matches the second index of refraction.

2. The display apparatus of claim 1, wherein the liquid is sealed into a cavity formed between the transparent substrate and a transparent body.

3. The display apparatus of claim 2, wherein the transparent substrate is spaced away from and opposite to the transparent body and the liquid fills a gap existing between the MEMS-based light modulators and the transparent body.

4. The display apparatus of claim 2, wherein the transparent body comprises a cover plate.

5. The display apparatus of claim 2, wherein the transparent body comprises a light guide.

6. This display apparatus of claim 1, wherein the liquid has an index of refraction of less than about 1.5.

7. The display apparatus of claim 1, wherein the liquid has a dielectric constant of above about 2.0.

8. The display apparatus of claim 1, wherein the liquid is a lubricant.

9. The display apparatus of claim 1, wherein the liquid has a viscosity below about 10 centipoise.

10. The display apparatus of claim 1, wherein the liquid has a dielectric breakdown strength above about 10,000 V/cm.

11. The display apparatus of claim 1, wherein MEMS-based light modulators of the array have surfaces that come into contact during operation of the display apparatus, and the liquid reduces stiction between the surfaces of the MEMS-based light modulators when the surfaces are in contact.

12. The display apparatus of claim 1, wherein the liquid comprises one of de-ionized water, methanol, ethanol, silicone oils, fluorinated silicone oils, dimethylsiloxane, polydimethylsiloxane, hexamethyldisiloxane, and diethylbenzene.

13. The display apparatus of claim 1, wherein the MEMS-based light modulators in the array of MEMS-based light modulators comprise shutters.

14. The display apparatus of claim 13, comprising an aperture layer having a plurality of apertures formed therein positioned proximate the array of MEMS-based light modulators.

15. The display apparatus of claim 14, wherein the aperture layer comprises a reflective material.

16. The display apparatus of claim 14, wherein the aperture layer comprises one of a dielectric mirror and a metal.

17. The display apparatus of claim 14, wherein the shutters are positioned less than about 100 microns from the aperture layer.

18. The display apparatus of claim 14, wherein the shutters are positioned less than about 10 microns from the aperture layer.

19. A display apparatus comprising:

an array of MEMS-based light modulators; and

a liquid in which the array of MEMS-based light modulators is at least partially immersed, wherein the liquid comprises a silicone oil.

20. The display apparatus of claim 19, wherein the liquid is sealed into a cavity formed between a substrate, on which the array of MEMS-based light modulators are formed, and a transparent body.

21. The display apparatus of claim 20, wherein the substrate is spaced away from and opposite to the transparent body and the liquid fills a gap existing between the MEMS-based light modulators and the transparent body.

22. The display apparatus of claim 20, wherein the transparent body comprises a cover plate.

23. The display apparatus of claim 22, wherein the substrate is transparent.

24. The display apparatus of claim 23, wherein the liquid has a first index of refraction, the substrate has a second index of refraction, and wherein the first index of refraction substantially matches the second index of refraction.

25. The display apparatus of claim 20, wherein the liquid has a first index of refraction, the transparent body has a second index of refraction, and wherein the first index of refraction substantially matches the second index of refraction.

26. The display apparatus of claim 25, wherein the transparent body comprises a light guide.

27. This display apparatus of claim 19, wherein the liquid has an index of refraction of less than about 1.5.

28. The display apparatus of claim 19, wherein the liquid has a dielectric constant of above about 2.0.

29. The display apparatus of claim 19, wherein the liquid is a lubricant.

30. The display apparatus of claim 19, wherein the liquid has a viscosity below about 10 centipoise.

31. The display apparatus of claim 19, wherein the liquid has a dielectric breakdown strength above about 10,000 V/cm.

32. The display apparatus of claim 19, wherein MEMS-based light modulators of the array have surfaces that come into contact during operation of the display apparatus, and the liquid reduces stiction between surfaces of the MEMS-based light modulators when the surfaces are in contact.

33. The display apparatus of claim 19, wherein the MEMS-based light modulators in the array of MEMS-based light modulators comprise shutters.

34. The display apparatus of claim 33, comprising an aperture layer having a plurality of apertures formed therein positioned proximate the array of MEMS-based light modulators.

35. The display apparatus of claim 34, wherein the aperture layer comprises a reflective material.

36. The display apparatus of claim 34, wherein the aperture layer comprises one of a dielectric mirror and a metal.

37. The display apparatus of claim 34, wherein the shutters are positioned less than about 100 microns from the aperture layer.

38. The display apparatus of claim 34, wherein the shutters are positioned less than about 10 microns from the aperture layer.

39. The display apparatus of claim 19, wherein the liquid comprises a fluorinated silicone oil.

40. The display apparatus of claim 19, wherein the liquid comprises a siloxane.