White interferometric modulators and methods for forming the same

• US 20070121118A1
• Filed: 01/25/2007
• Published: 05/31/2007
• Est. Priority Date: 05/27/2005
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Cummings, William, Mignard, Marc, Kogut, Lior, Tung, Ming-Hau, Gally, Brian
• Granted Patent: US 7,884,989 B2
• Time in Patent Office: Days
• US Class Current: 356/477
• 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 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833

Abstract

An iterferometric modulator array is configured to reflect a broad band spectrum of optical wavelengths by arranging a reflector and a partially transparent substrate in a non-parallel relationship.

Claims

1. An optical Micro-Electro-Mechanical System (MEMS) device comprising:

a partially transparent substrate; and

a reflector, wherein the reflector and the substrate are configured to form an optical interferometric resonance cavity therebetween wherein the substrate and the reflector are non-parallel with respect to one another.

2. The device of claim 1, wherein the reflector is positioned with an angle of between about I degree and about 20 degrees with respect to the substrate.

3. The device of claim 1, wherein the cavity is optically resonant over a substantially continuous range of wavelengths.

4. The device of claim 1, wherein the cavity is optically resonant over substantially the entire visible spectrum.

5. The device of claim 4, wherein light reflected from the cavity and through the substrate is substantially white.

6. The device of claim 1, wherein the substrate comprises texture and the spectrum of resonance wavelengths of the cavity is determined at least in part by the texture.

7. The device of claim 6, wherein the texture comprises at least one of a trench, a cavity, and a protrusion.

8. The device of claim 1, further comprising a stop configured to constrain the reflector to a predetermined position and wherein the spectrum of resonance wavelengths of the cavity is determined at least in part by the predetermined position of the reflector.

9. The device of claim 1, wherein the substrate comprises a first electrode, wherein a first gap between a first portion of the reflector and the substrate is configured to be modified by a first voltage applied across the first electrode and the reflector.

10. The device of claim 9, wherein the first electrode is positioned closer to a first peripheral edge of the reflector than to a second peripheral edge of the reflector.

11. The device of claim 9, wherein the substrate further comprises a second electrode, wherein a second gap between a second portion of the reflector and the substrate is configured to be modified by a second voltage applied across the second electrode and the reflector.

12. The device of claim 11, wherein the light reflected from the cavity and through the substrate is selectively substantially white, substantially minimized, or substantially colored, according to the magnitudes of the first and second voltages.

13. The device of claim 1, wherein the substrate comprises an electrode and the spectrum of resonance wavelengths of the cavity is determined at least in part by an application of an actuation voltage between the electrode and the reflector, and wherein the electrostatic force generated by the application of the actuation voltage is greater on a first side of the reflector than on a second side of the reflector.

14. The device of claim 13, wherein the reflector is attached to a support structure at a central portion of the reflector.

15. The device of claim 13, wherein the reflector is attached to a support structure at a peripheral portion of the reflector.

16. The device of claim 1, wherein the reflector is attached to a support structure at a position offset from a center point on the reflector, and the spectrum of resonance wavelengths of the cavity is determined at least in part by the position of the attachment.

17. The device of claim 16, wherein the support structure is configured to deform in response to forces generated by application of an actuation voltage to the device.

18. The device of claim 16, wherein the reflector is configured to pivot about a point near or on the support structure.

19. The device of claim 16, wherein the reflector is configured to deflect towards the substrate in response to forces generated by application of an actuation voltage to the device.

20. The device of claim 16, further comprising an electrode positioned such that the reflector is between the electrode and the substrate, wherein the reflector is configured to deflect away from the substrate in response to forces generated by application of an actuation voltage between the reflector and the electrode.

21. The device of claim 1, wherein the reflector is attached to a support structure and the support structure comprises an asymmetry, and the spectrum of resonance wavelengths of the cavity is determined at least in part by the asymmetry of the support structure.

22. The device of claim 20, wherein a force generated by application of an actuation voltage to the device generates a greater force on a first side of the support structure than on a second side of the support structure.

23. The device of claim 20, a first side of the support structure is more compliant than a second side of the support structure.

24. The device of claim 20, a first side of the support structure is farther from the substrate than a second side of the support structure.

25. The device of claim 1, wherein the reflector is configured to move to a position such that the reflector is substantially adjacent and substantially parallel to the substrate.

26. The device of claim 1, wherein the contrast ratio of light reflected from the cavity and through the substrate with the reflector at first and second positions is at least 4.

27. The device of claim 26, wherein the light reflected from the cavity and through the substrate with the reflector at the first position is substantially white.

28. The device of claim 26, wherein light reflected from the cavity and through the substrate with the reflector at the second position of the plurality of positions is substantially colored.

29. The device of claim 1, further comprising:

a display;

a processor that is configured to communicate with the display, the processor being configured to process image data; and

a memory device that is configured to communicate with the processor.

30. The device of claim 29, further comprising a driver circuit configured to send at least one signal to the display.

31. The device of claim 30, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

32. The device of claim 29, further comprising an image source module configured to send the image data to the processor.

33. The device of claim 32, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

34. The device of claim 29, further comprising an input device configured to receive input data and to communicate the input data to the processor.

35. An optical Micro-Electro-Mechanical System (MEMS) device comprising means for interferometric ally modulating light so as to reflect light from a single cavity having a substantially broad band spectrum.

36. The device of claim 35, wherein the modulating means comprises:

a partially transparent substrate; and

a reflector, wherein the reflector and the substrate form an optical interferometric resonance cavity therebetween and wherein the substrate and the reflector are non-parallel with respect to one another.

37. The device of claim 35, wherein the device reflects light of a substantially continuous range of wavelengths.

38. The device of claim 35, wherein the device reflects light of substantially the entire visible spectrum.

39. The device of claim 35, wherein the device reflects light appearing substantially white.

40. A method of manufacturing an optical Micro-Electro-Mechanical System (MEMS) device, the method comprising:

providing a partially transparent substrate; and

forming a reflector, wherein the reflector and the substrate are configured to form an optical interferometric resonance cavity therebetween wherein the substrate and the reflector are non-parallel with respect to one another.

41. The method of claim 40, further comprising forming texture in the substrate, wherein the spectrum of resonance wavelengths of the cavity is determined at least in part by the texture.

42. The method of claim 40, further comprising forming a structure on the substrate, wherein the spectrum of resonance wavelengths of the cavity is determined at least in part by the structure.

43. The method of claim 40, further comprising:

forming an electrode in or on the substrate; and

forming an actuation element,

wherein the spectrum of resonance wavelengths of the cavity is determined at least in part by an asymmetric application of actuation voltage between the electrode and the actuation element.

44. The method of claim 40, further comprising:

forming a support structure; and

attaching the reflector to the support structure at a position offset from a center point on the reflector.

45. The method of claim 40, further comprising:

forming a support structure, wherein the support structure is asymmetric about a geometric center of the support structure.

46. An optical Micro-Electro-Mechanical System (MEMS) device manufactured by the method of claim 40.