System and method of illuminating interferometric modulators using backlighting

• US 8,040,588 B2
• Filed: 02/25/2008
• Issued: 10/18/2011
• Est. Priority Date: 09/27/2004
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Chui, Clarence, Tung, Ming-Hau
• Primary Examiner(s): Dinh; Jack
• Application Number:
  US12/036,668
• Publication Number:
  US 20090225394A1
• Time in Patent Office: 1,331 Days
• Field of Search: 359290-292, 359/298, 359/247, 359/260, 359/261, 359/263, 359315-318
• US Class Current: 359/290
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3466 based on interferometric effect
• CPC Class Codes: H04M 1/22 Illumination; Arrangements for improving the visibility of characters on dials
• CPC Class Codes: H04N 5/7458 the modulator being an array of deformable mirrors, e.g. digital micromirror device [DMD]
• CPC Class Codes: H04W 52/027 by controlling a display operation or backlight unit
• CPC Class Codes: Y02D 30/70 in wireless communication networks
• CPC Class Codes: Y10S 359/90 Methods

Abstract

An interferometric modulator array device with backlighting is disclosed. The interferometric modulator array device comprises a plurality of interferometric modulator elements, wherein each of the interferometric modulator elements comprises an optical cavity. The interferometric modulator array includes an optical aperture region, and at least one reflecting element is positioned so as to receive light passing through the optical aperture region and reflect at least a portion of the received light to the cavities of the interferometric modulator elements. In some embodiments, the interferometric modulator elements may be separated from each other such that an optical aperture region is formed between adjacent interferometric modulator elements.

Claims

1. A light-modulating array comprising:

a first light-modulating element comprising a first reflective surface situated above a substrate and a second reflective surface spaced from the first reflective surface of the first light-modulating element;

a second light-modulating element comprising a first reflective surface situated above the substrate and a second reflective surface spaced from the first reflective surface of the second light-modulating element;

a light source situated over a side of the first and second light-modulating elements, the side opposite to a viewing side from which the light-modulating array is configured to be viewed;

an optical aperture region between the first light-modulating element and the second light-modulating element, light propagating from the light source configured to pass through the optical aperture region; and

a reflecting element configured to reflect at least a portion of the passed light towards at least one of the first and second light-modulating elements, wherein the portion of the passed light is reflected off a reflecting surface of the reflecting element, said reflecting surface of the reflecting element being sloped with respect to the substrate.

2. The light-modulating array of claim 1, wherein the light source is uncollimated.

3. The light-modulating array of claim 2, wherein a width of the reflecting element is greater than a width of the optical aperture region.

4. The light-modulating array of claim 2, wherein a width of the reflecting element is at least about three times greater than a width of the optical aperture region.

5. The light-modulating array of claim 2, wherein a width of the reflecting element extends beyond each side of the optical aperture region by at least a width of the optical aperture region.

6. The light-modulating array of claim 2, further comprising a collimating optic between the light source and the reflecting element.

7. The light-modulating array of claim 6, wherein the collimating optic comprises a lens.

8. The light-modulating array of claim 6, wherein a width of the reflecting element is no greater than a width of the optical aperture region.

9. The light-modulating array of claim 2, further comprising an optical film between the light source and the reflecting element, the optical film configured to eliminate light propagating from the light source at extreme angles.

10. The light-modulating array of claim 1, wherein the first reflective surface of the first and second modulating elements are movable with respect to the second reflective surface of the first and second modulating elements respectively to provide light modulation.

11. The light-modulating array of claim 9, wherein a width of the reflecting element is no greater than a width of the optical aperture region.

12. The light-modulating array of claim 1, wherein the light source is collimated.

13. The light-modulating array of claim 12, wherein a width of the reflecting element is no greater than a width of the optical aperture region.

14. The light-modulating array of claim 1, wherein the reflecting element has a width between about 1 μ

m and about 10 μ

m.

15. The light-modulating array of claim 1, wherein the reflecting element has a height between about 200 Å

and about 1000 Å

.

16. The light-modulating array of claim 1, wherein the reflecting element is configured to reflect at least a portion of the passed light towards both the first and second light-modulating elements.

17. The light-modulating array of claim 1, further comprising at least one additional reflecting element, each of the reflecting elements configured to reflect at least a portion of the passed light towards at least one of the first and second light-modulating elements.

18. The light-modulating array of claim 1, wherein the first and second modulating elements comprise spatial light modulators configured to form an image.

19. The light-modulating array of claim 1, wherein the first and second modulating elements comprise interferometric modulators.

20. The light-modulating array of claim 19, wherein the sloped reflecting surface is between the substrate and the light-modulating elements.

21. The light-modulating array of claim 1, wherein the modulating elements comprise electromechanical mirrors.

22. The light-modulating array of claim 1, wherein the array comprises a microelectromechanical system (MEMS) comprising the modulating elements.

23. The light-modulating array of claim 1, wherein the sloped reflecting surface is curved.

24. The light-modulating array of claim 1, wherein the reflecting element has flat or planar sections tilted with respect to the substrate.

25. The light-modulating array of claim 1, wherein the reflecting element is disposed on a side of the substrate opposite a viewing side of the substrate.

26. The light-modulating array of claim 1, wherein the reflecting element is situated between the first and second light-modulating elements.

27. A reflective display device comprising the light-modulating array of claim 1.

28. The light-modulating array of claim 1, wherein the sloped reflecting surface has a substantially concave geometry.

29. The light-modulating array of claim 1, wherein the sloped reflecting surface has a substantially convex geometry.

30. The light-modulating array of claim 1, further comprising a mask aligned with the reflecting element, the mask configured to at least partially obstruct a view of the reflecting element.

31. The light-modulating array of claim 30, wherein the mask comprises at least a portion of an etalon.

32. The light-modulating array of claim 31, wherein the portion of the etalon comprises one or more layers of partially reflective material and one or more spacing layers.

33. The light-modulating array of claim 1, wherein the reflecting element comprises a shaped feature and a reflecting material over the shaped feature.

34. The light-modulating array of claim 1, wherein the reflecting element is configured to scatter light into at least one of the first and second light-modulating elements.

35. The light-modulating array of claim 1, wherein the reflecting element is configured to deflect light into at least one of the first and second light-modulating elements.

36. The light-modulating array of claim 1, wherein the reflecting element is generally circularly symmetrical.

37. The light-modulating array of claim 1, wherein the reflecting element has a non-uniform geometry.

38. The light-modulating array of claim 37, wherein the sloped reflective surface is micro-etched to increase deflection of light.

39. The light-modulating array of claim 37, wherein the sloped reflective surface is micro-etched to increase scattering of light.

40. The light-modulating array of claim 1, wherein the sloped reflecting surface is rough.

41. The light-modulating array of claim 1, wherein the sloped reflecting surface is stepped or jagged.

42. The light-modulating array of claim 1, wherein the sloped reflecting surface is smooth.

43. The light-modulating array of claim 1, wherein the sloped reflecting surface is diffuse.

44. The light-modulating array of claim 1, wherein the sloped reflecting surface is specular.

45. The light-modulating array of claim 1, further comprising a planarization material covering the reflecting element.

46. The light-modulating array of claim 45, wherein the planarization layer comprises a substantially optically transmissive material.

47. A light-modulating array comprising:

a first means for modulating light including a first reflective surface situated above a substrate and a second reflective surface spaced from the first reflective surface of the first light-modulating means;

a second means for modulating light including a first reflective surface situated above the substrate and a second reflective surface spaced from the first reflective surface of the second light-modulating means;

a means for illumination situated over a side of the first and second light-modulating means, the side opposite to a viewing side from which the light-modulating array is configured to be viewed;

a means for passing light, said light-passing means between the first light-modulating means and the second light-modulating means, light propagating from the illumination means configured to pass through the light-passing means; and

a means for reflecting at least a portion of the passed light towards at least one of the first and second light-modulating means, wherein the portion of the passed light is reflected off a reflecting surface of the reflecting means, said reflecting surface being sloped with respect to the substrate.

48. The light-modulating array of claim 47, wherein the first light-modulating means comprises a first light-modulating element, or wherein the second light-modulating means comprises a second light-modulating element, or wherein the illumination means comprises a light source, or wherein the light-passing means comprises an optical aperture region, or wherein the light reflecting means comprises a reflecting element.

49. The light-modulating array of claim 47, wherein the illumination means is uncollimated.

50. The light-modulating array of claim 49, wherein a width of the light reflecting means is greater than a width of the light-passing means.

51. The light-modulating array of claim 49, wherein a width of the light reflecting means is at least about three times greater than a width of the light-passing means.

52. The light-modulating array of claim 49, wherein a width of the light reflecting means extends beyond each side of the light-passing means region by at least a width of the light-passing means.

53. The light-modulating array of claim 49, further comprising a means for collimating light between the illumination means and the light reflecting means.

54. The light modulating array of claim 53, wherein the light collimating means comprises a collimating optic.

55. A spatial light modulator comprising:

a light-modulating array including a plurality of means for modulating light, each light-modulating means having a cavity defined by first and second optical surfaces;

at least one means for passing light, said light-passing means in said light-modulating array; and

at least one means for receiving light passing through the light-passing means and for reflecting at least a portion of the received light to said cavity, the reflecting means formed between a substrate and the plurality of light-modulating means, wherein the at least one means for reflecting light has a sloped surface.

56. The light-modulating array of claim 55, wherein each of the plurality of light-modulating means comprises a light-modulating element, or wherein the light-passing means comprises an optical aperture region, or wherein the light reflecting means comprises a reflecting element.

57. The light-modulating array of claim 55, wherein the plurality of light-modulating means comprises a plurality of interferometric modulators.