Spatial light modulators with non-uniform pixels

• US 7,158,279 B2
• Filed: 10/19/2004
• Issued: 01/02/2007
• Est. Priority Date: 10/19/2004
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Grasser, Regis, Huibers, Andrew, Patel, Satyadev, Heureux, Peter
• Primary Examiner(s): Ben; Loha
• Application Number:
  US10/969,503
• Publication Number:
  US 20060082856A1
• Time in Patent Office: 805 Days
• Field of Search: 359290-292, 359/295, 359/298, 359/224, 359/226, 345/690, 345/694, 345/697, 345/84, 257/436, 257/443, 438/7, 438/14, 438/104
• US Class Current: 359/290
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: H04N 9/3114 by using a sequential colour filter producing one colour at a time
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

A micromirror array comprises micromirrors of different properties for use particularly in display systems. Micromirrors of different properties can be arranged within the micromirror array according to a predetermined pattern, or randomly. However, it is advantageous to arrange the micromirrors with different properties within the micromirror array neither in complete order nor complete in random.

Claims

1. A spatial light modulator, comprising:

a micromirror array comprising a set of micromirrors in an active region and a set of micromirrors in an inactive region, wherein the micromirrors in the active region correspond to viewed image pixels, while the micromirrors in the inactive region do not; and

wherein the micromirrors in the active region comprise a first micromirror that is different from a second micromirror in the same active region.

2. The spatial light modulator of claim 1, wherein the first and second micromirrors each comprise a deflectable reflective mirror plate attached to a deformable hinge that is held by a hinge support on a substrate.

3. The spatial light modulator of claim 2, wherein the mirror plates of the first and second micromirrors are different.

4. The spatial light modulator of claim 3, wherein the mirror plates are different in shape.

5. The spatial light modulator of claim 3, wherein the minor plates are different in reflectivity to visible light.

6. The spatial light modulator of claim 3, wherein the mirror plates comprise different materials.

7. The spatial light modulator of claim 3, wherein the mirror plates each are a multilayered structure.

8. The spatial light modulator of claim 4, wherein one of the mirror plates has a diamond shape, while the other has a zigzagged edge.

9. The spatial light modulator of claim 3, wherein the mirror plates have different vertical distance from the substrate.

10. The spatial light modulator of claim 3, wherein the mirror plates are different in size.

11. The spatial light modulator of claim 3, wherein the first micromirror has a post that directly connects the hinge support of the first micromirror to the substrate, while the second micromirror does not.

12. The spatial light modulator of claim 11, wherein the hinge support of the second micromirror is connected to the hinge support of the first micromirror.

13. The spatial light modulator of claim 3, wherein the first and second micromirrors are not adjacent.

14. The spatial light modulator of claim 3, wherein the mirror plates of the first and second micromirrors have different maximum rotation angles in a rotation direction.

15. The spatial light modulator of claim 3, wherein the minor plate of the first micromirror is operable to rotate asymmetrically, while the mirror plate of the second micromirror is not.

16. The spatial light modulator of claim 3, wherein the mirror plates each comprise a reflecting layer composed of a metallic material.

17. The spatial light modulator of claim 16, wherein the metallic material is aluminum, titanium, silver, or gold.

18. The spatial light modulator of claim 3, wherein the micromirrors in the active region comprise a first sub-array and second sub-array of micromirrors, wherein the micromirrors in different sub-array have different properties.

19. The spatial light modulator of claim 18, wherein a total number of micromirrors in the first sub-array accounts far 90% or more of a total number of micromirrors in the active region.

20. The spatial light modulator of claim 18, wherein a total number of micromirrors in the first sub-array accounts for 70% or more of a total number of micromirrors in the active region.

21. The spatial light modulator of claim 18, wherein a total number of micromirrors in the first sub-array accounts for 50% or more of a total number of micromirrors in the active region.

22. The spatial light modulator of claim 18, wherein the micromirrors in the active region comprise a third micromirror that is different from both of the first and second micromirrors.

23. The spatial light modulator of claim 2, wherein the mirror plates and hinges are formed on different planes parallel to the substrate when the mirror plates are not deflected.

24. The spatial light modulator of claim 1, wherein the micromirrors in the active region comprise a first and second sub-array of micromirrors;

wherein the first sub-array has a pitch different from a pitch of the second sub-may with the pitch being defined as a center-to-centre distance between adjacent micromirrors.

25. The spatial light modulator of claim 1, wherein the micromirrors in the active region comprise a first and second sub-array of micromirrors;

wherein the first sub-array has a gap different from a gap of the second sub-array with the gap being defined as the shortest distance between adjacent micromirrors.

26. A display system, comprising:

an illumination system providing an illumination light for the system;

a spatial light modulator at claim 10; and

an optical element directing the illumination light to and from the spatial light modulator.

27. A spatial light modulator, comprising:

an array of micromirrors in an active region and an inactive region, wherein the micromirrors in the active region each correspond to an image pixel;

wherein the active region comprises a first sub-array of micromirrors and a second sub-array of micromirrors, wherein the first and second sub-arrays are different in pitch or gap with the pitch being defined as a center-to-center distance between adjacent micromirrors; and

the gap being defined as the shortest distance between two adjacent micromirrors.

28. The spatial light modulator of claim 27, wherein the micromirrors of the first sub-array each correspond to a visual image pixel, while the micromirrors of the second sub-array do not.

29. The spatial light modulator of claim 27, wherein the micromirrors of the first sub-array each correspond to an image pixel, while the micromirrors of the second sub-array do not.

30. The spatial light modulator of claim 27, wherein the first sub-array comprises a first micromirror and a different second micromirror.

31. The spatial light modulator of claim 30, wherein the first and second micromirrors each comprise a deflectable reflective mirror plate attached to a deformable hinge that is held by a hinge support on a substrate.

32. The spatial light modulator of claim 31, wherein the mirror plates are different in shape.

33. The spatial light modulator of claim 32, wherein one of the mirror plates has a diamond shape, while the other has a zigzagged edge.

34. The spatial light modulator of claim 31, wherein the mirror plates are different in reflectivity to visible light.

35. The spatial light modulator of claim 31, wherein the mirror plates comprise different materials.

36. The spatial light modulator of claim 31, wherein the mirror plates each are a multilayered structure.

37. The spatial light modulator of claim 31, wherein the mirror plates have different vertical distance from the substrate.

38. The spatial light modulator of claim 31, wherein the mirror plates and hinges are formed on different planes parallel to the substrate when the mirror plates are not deflected.

39. The spatial light modulator of claim 31, wherein the mirror plates are different in size.

40. The spatial light modulator of claim 31, wherein the first micromirror has a post that directly connects the hinge support of the first micromirror to the substrate, while the second micromirror does not.

41. The spatial light modulator of claim 40, wherein the hinge support of the second micromirror is connected to the hinge support of the first micromirror.

42. The spatial light modulator of claim 31, wherein the mirror plates of the first and second micromirrors have different maximum rotation angles in a rotation direction.

43. The spatial light modulator of claim 31, wherein the mirror plate of the first micromirror is operable to rotate asymmetrically, while the minor plate of the second micromirror is not.

44. The spatial light modulator of claim 31, wherein the mirror plates each comprise a reflecting layer composed of a metallic material.

45. The spatial light modulator of claim 31, wherein the mirror plate comprises a metallic material that is aluminum, titanium, silver, or gold.

46. The spatial light modulator of claim 30, wherein the first and second micromirrors are not adjacent.

47. The spatial light modulator of claim 27, wherein the micromirror array comprises an active region and an inactive region;

wherein the micromirrors in the active region comprises a first sub-array and second sub-array of micromirrors, wherein the micromirrors in different sub-array have different properties.

48. The spatial light modulator of claim 47, wherein a total number of micromirrors in the first sub-array accounts for 90% or more of a total number of micromirrors in the active region.

49. The spatial light modulator of claim 47, wherein a total number of micromirrors in the first sub-array accounts for 70% or more of a total number of micromirrors in the active region.

50. The spatial light modulator of claim 47, wherein a total number of micromirrors in the first sub-array accounts for 50% or more of a total number of micromirrors in the active region.

51. The spatial light modulator of claim 47, wherein the micromirrors in the active region comprise a third micromirror that is different from both of the first and second micromirrors.

52. A display system, comprising:

an illumination system providing an illumination light for the system;

a spatial light modulator of claim 27; and

an optical element directing the illumination light to and from the spatial light modulator.

53. A method of fabricating a micromirror array device, comprising:

preparing a set of masks at least one of which having a first area corresponding to a first micromirror and a second area corresponding to a second micromirror, wherein the first and second areas are different;

forming an array of micromirrors, comprising;

providing a substrate;

depositing a sacrificial material on the substrate; and

forming a plurality of series of structural layers of the micromirrors, comprising;

applying the set of masks such that at least two micromirrors in the array are different with each of the two different micromirrors being associated with an image pixel in operation; and

removing the sacrificial material.