Systems and methods using interferometric optical modulators and diffusers

• US 7,944,602 B2
• Filed: 10/28/2009
• Issued: 05/17/2011
• 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
• Primary Examiner(s): Ben; Loha
• Application Number:
  US12/607,932
• Publication Number:
  US 20100165443A1
• Time in Patent Office: 566 Days
• Field of Search: 359290-295, 359/298, 359237-239, 359/245, 359/260, 359/321, 359/13, 359/15, 359/22, 359/24, 356/405, 356/406, 356/408, 356/422, 356/425, 356/450, 356/486, 356/493, 356/502, 345/32, 345/33, 345/84, 345/85, 345/102, 345/173, 345/520, 257/222, 257/290, 257/364, 257/709
• 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: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

Various embodiments include interferometric optical modulators comprising a substrate layer having a thickness between about 0.1 mm to about 0.45 mm thick and a method for manufacturing the same. The interferometric modulator can be integrated together with a diffuser in a display device. The thin substrate permits use of a thicker diffuser. The thinner substrate may increase resolution and reduce overall thickness of the interferometric modulator. The thicker diffuser may provide increased diffusion and durability.

Claims

1. A spatial light modulator comprising:

a substrate having a first side and a second side;

a plurality of pixels disposed over the first side of the substrate, the plurality of pixels having a pitch, each of the plurality of pixels comprising an interferometric light modulator configured to be individually actuated to modulate light in response to an electrical signal, each of said interferometric light modulators comprising a resonant optical cavity; and

a diffuser spaced apart from said resonant optical cavities by less than about the pitch of said plurality of pixels such that the spatial light modulator is configured to achieve a contrast greater than about 5 to 1 for a displayed test pattern of alternating white and black lines having a spatial period of approximately the pitch of said plurality of pixels.

2. The spatial light modulator of claim 1, wherein the spatial light modulator is configured to have a reflectivity at a viewing angle of about 45°

that is greater than about 75% of the reflectivity of the spatial light modulator when viewed from normal.

3. The spatial light modulator of claim 1, wherein the diffuser is disposed sufficiently close to said plurality of pixels that light incident on a first portion of the diffuser disposed over a first pixel of the plurality of pixels is not scattered into a second pixel of the plurality of pixels, the second pixel adjacent the first pixel.

4. The spatial light modulator of claim 1, wherein the pitch of the plurality of pixels is less than about 0.45 mm.

5. The spatial light modulator of claim 1, wherein the pitch of the plurality of pixels is less than about 0.3 mm.

6. The spatial light modulator of claim 1, wherein the pitch of the plurality of pixels is less than about 0.2 mm.

7. The spatial light modulator of claim 1, wherein the pitch of the plurality of pixels is less than about 0.1 mm.

8. The spatial light modulator of claim 1, wherein said diffuser comprises a plurality of diffuser elements for said plurality of pixels.

9. The spatial light modulator of claim 1, wherein at least a portion of said diffuser comprises optical power.

10. The spatial light modulator of claim 1, wherein said diffuser is disposed over the second side of said substrate.

11. The spatial light modulator of claim 10, wherein said spatial light modulator is configured such that the first side of said substrate is distal to a viewer of said spatial light modulator and the second side of said substrate is proximal to said viewer.

12. The spatial light modulator of claim 1, wherein said diffuser is disposed between the first side of said substrate and said plurality of pixels.

13. The spatial light modulator of claim 1, wherein said spatial light modulator is configured such that light incident on said spatial light modulator passes through said diffuser before entering said resonant optical cavities.

14. The spatial light modulator of claim 1, wherein said spatial light modulator comprises a reflective spatial light modulator.

15. The spatial light modulator of claim 1, wherein said interferometric light modulator comprises:

a partial reflector; and

a movable reflector spaced from said partial reflector by a gap to provide said resonant optical cavity, said movable reflector configured to move with respect to said partial reflector to alter said gap to interferometrically modulate light, said movable reflector configured to move in response to an electrical signal.

16. The spatial light modulator of claim 15, further comprising an electrode configured to cause said movable reflector to move with respect to said partial reflector in response to the electrical signal, said electrode disposed on the same side of the gap as said partial reflector.

17. A method of forming a spatial light modulator, the method comprising:

forming a plurality of interferometric light modulating elements over a substantially transparent substrate, said plurality of interferometric light modulating elements having a spatial pitch, each of said interferometric light modulating elements comprising a resonant optical cavity;

providing a diffuser spaced apart from the resonant optical cavities of said plurality of interferometric light modulating elements by less than approximately the spatial pitch; and

forming electrodes configured to allow individual electrical actuation of the interferometric light modulating elements.

18. The method of claim 17, wherein forming the plurality of interferometric light modulating elements comprises forming the plurality of interferometric light modulating elements over a first side of the substantially transparent substrate and providing the diffuser comprises providing the diffuser over a second side of the substantially transparent substrate.

19. The method of claim 17, wherein forming said plurality of interferometric light modulating elements comprises forming said plurality of interferometric light modulating elements such that said spatial pitch is less than about 0.45 mm.

20. The method of claim 17, wherein forming said plurality of interferometric light modulating elements comprises forming said plurality of interferometric light modulating elements such that said spatial pitch is less than about 0.3 mm.

21. The method of claim 17, wherein forming said plurality of interferometric light modulating elements comprises forming said plurality of interferometric light modulating elements such that said spatial pitch is less than about 0.2 mm.

22. The method of claim 17, wherein forming said plurality of interferometric light modulating elements comprises forming said plurality of interferometric light modulating elements such that said spatial pitch is less than about 0.1 mm.

23. The method of claim 17, wherein providing said diffuser comprises applying said diffuser to said substrate using an adhesive.

24. The method of claim 17, wherein providing said diffuser further comprises providing an optical texture on a surface of the diffuser.

25. The method of claim 24, wherein providing said optical texture comprises providing at least one of a holographic lens, a diffractive lens, or a Fresnel lens.

26. The method of claim 17, further comprising applying at least one layer or coating to said diffuser, said at least one layer or coating comprising at least one of an antireflective layer or coating, an antiglare layer or coating, or an anti-scratch layer or coating.

27. The method of claim 17, wherein forming said plurality of interferometric light modulating elements comprises, for each element:

forming a partial reflector; and

forming a movable reflector spaced from the partial reflector by a gap thereby forming said resonant optical cavity, said movable reflector configured to move toward said partial reflector to alter said resonant optical cavity to interferometrically modulate light.

28. The method of claim 27, wherein said electrodes are formed on the same side of the gap as said partial reflector.

29. A spatial light modulator formed using the method of claim 17.

30. The spatial light modulator of claim 29, wherein the spatial light modulator is configured to achieve a contrast greater than about 5 to 1 for a displayed test pattern of alternating white and black lines having a spatial period of approximately the spatial pitch of the plurality of pixels.

31. A spatial light modulator comprising a plurality of pixels having a spatial pitch, each of said pixels comprising:

means for spatially modulating light by interferometrically modulating reflectivity of said light, said spatial light modulating means comprising a resonant optical cavity; and

means for diffusing said light, said diffusing means disposed with respect to said resonant optical cavity by less than approximately the spatial pitch of said plurality of pixels,

wherein the spatial light modulating means is configured to achieve a contrast greater than about 5 to 1 for a displayed test pattern of alternating white and black lines having a spatial period of approximately the spatial pitch of said plurality of pixels.

32. The spatial light modulator of claim 31, wherein the spatial light modulating means comprises:

a partial reflector; and

a movable reflector spaced from said partial reflector by a gap to provide said resonant optical cavity, said movable reflector configured to move with respect to said partial reflector to alter said gap in response to an electrical signal.

33. The spatial light modulator of claim 32, further comprising means for conducting electricity, said conducting means configured to cause said movable reflector to move with respect to said partial reflector in response to the electrical signal, said conducting means disposed on the same side of the gap as said partial reflector.

34. The spatial light modulator of claim 31, wherein said diffusing means comprises a diffuser disposed a distance from said resonant optical cavity that is less than said spatial pitch.