Interferometric optical display system with broadband characteristics

• US 7,643,203 B2
• Filed: 04/10/2006
• Issued: 01/05/2010
• Est. Priority Date: 04/10/2006
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Gousev, Evgeni, Mienko, Marek, Xu, Gang
• Primary Examiner(s): Mack; Ricky L
• Assistant Examiner(s): Thomas; Brandi N
• Application Number:
  US11/401,023
• Publication Number:
  US 20070236774A1
• Time in Patent Office: 1,366 Days
• Field of Search: 359/290, 359/291, 359/292, 359/295, 359/298
• US Class Current: 359/291
• 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 29/49124 On flat or curved insulated base, e.g., printed circuit, etc.

Abstract

Broad band white color can be achieved in MEMS display devices by incorporating a material having an extinction coefficient (k) below a threshold value for wavelength of light within an operative optical range of the interferometric modulator. One embodiment provides a method of making the MEMS display device comprising depositing said material over at least a portion of a transparent substrate, depositing a dielectric layer over the layer of material, forming a sacrificial layer over the dielectric, depositing an electrically conductive layer on the sacrificial layer, and forming a cavity by removing at least a portion of the sacrificial layer. The suitable material may comprise germanium, germanium alloy of various compositions, doped germanium or doped germanium-containing alloys, and may be deposited over the transparent substrate, incorporated within the transparent substrate or the dielectric layer.

Claims

1. An interferometric display device, comprising:

means for transmitting light; and

means for interferometrically reflecting light through said transmitting means, wherein said interferometrically reflecting means comprises an absorber over a portion of the transmitting means and a movable reflective layer over the absorber, wherein said absorber has an extinction coefficient (k) below a threshold value for wavelengths of light within an operative optical range of the interferometrically reflecting means.

2. The interferometric display device of claim 1, wherein said threshold value is about 2.5.

3. The interferometric display device of claim 1, wherein said extinction coefficient (k) remains substantially constant for wavelengths of light within said operative optical range of the interferometrically reflecting means.

4. The interferometric display device of claim 1, wherein said extinction coefficient (k) decreases as the wavelength of light increases within said operative optical range of the interferometrically reflecting means.

5. The interferometric display device of claim 1, wherein the absorber has a refractive index (n) that increases as the wavelength of light increases within said operative optical range of the interferometrically reflecting means.

6. The interferometric display device of claim 5, wherein said absorber has an n to k ratio from about 2.5 to about 6.

7. The interferometric display device of claim 5, wherein said absorber has an n to k ratio of about 3.

8. The interferometric display device of claim 1, wherein said transmitting means comprises a transparent substrate.

9. The interferometric display device of claim 1, wherein said reflecting means comprises an interferometric modulator comprising a layer of material having an extinction coefficient (k) below a threshold value for wavelengths of light within an operative optical range of the interferometric modulator.

10. The interferometric display device of claim 9, wherein said threshold value is about 2.5.

11. The interferometric display device of claim 9, wherein the extinction coefficient (k) remains substantially constant for wavelengths of light within said operative optical range of the interferometric modulator.

12. The interferometric display device of claim 9, wherein the extinction coefficient (k) decreases as the wavelength of light increases within said operative optical range of the interferometric modulator.

13. The interferometric display device of claim 9, wherein said material has a refractive index (n) that increases as the wavelength of light increases within said operative optical range of the interferometric modulator.

14. The interferometric display device of claim 13, wherein said material has an n to k ratio from about 2.5 to about 6.

15. The interferometric display device of claim 13, wherein said material has an n to k ratio of about 3.

16. The interferometric display device of claim 9, wherein said layer of material is deposited over said transmitting means.

17. The interferometric display device of claim 9, wherein said layer of material is integrated into said transmitting means.

18. The interferometric display device of claim 17, wherein said transmitting means comprises a transparent substrate and said material is integrated into said transparent substrate.

19. The interferometric display device of claim 1, wherein said absorber comprises germanium, germanium alloy, doped germanium or doped germanium-containing alloy.

20. The interferometric display device of claim 19, wherein said absorber further comprises a metal layer.

21. The interferometric display device of claim 20, wherein said metal layer comprises a material selected from the group consisting of chromium, molybdenum, refractive metals, and refractive alloys.

22. A MEMS display device comprising:

a substrate upon which incident light enters; and

an array of interferometric modulators deposited on said substrate, wherein said array comprises a movable reflective layer over said substrate and an absorber between said reflective layer and said substrate, wherein said absorber has an extinction coefficient (k) below a threshold value for wavelengths of light within an operative optical range of the interferometric modulator.

23. The MEMS display device of claim 22, wherein said threshold value is about 2.5.

24. The MEMS display device of claim 22, wherein said extinction coefficient (k) remains substantially constant for wavelengths of light within said operative optical range of the interferometric modulator.

25. The MEMS display device of claim 22, wherein said extinction coefficient (k) decreases as the wavelength of light increases within said operative optical range of the interferometric modulator.

26. The MEMS display device of claim 22, wherein said absorber has a refractive index (n) that increases as the wavelength of light increases within said operative optical range of the interferometric modulator.

27. The MEMS display device of claim 26, wherein said absorber has an n to k ratio from about 2.5 to about 6.

28. The MEMS display device of claim 26, wherein said absorber has an n to k ratio of about 3.

29. The MEMS display device of claim 22, wherein said substrate is a transparent substrate.

30. The MEMS display device of claim 27, wherein said transparent substrate comprises glass or plastic.

31. The MEMS display device of claim 22, wherein said absorber comprises germanium, a germanium alloy, doped germanium or doped germanium-containing alloy.

32. The MEMS display device of claim 31, wherein said absorber further comprises a metal layer.

33. The MEMS display device of claim 32, wherein said metal layer comprises a material selected from the group consisting of chromium, molybdenum, refractive metals, and refractive alloys.

34. The MEMS display device of claim 22, wherein said absorber is deposited over said transparent substrate.

35. The MEMS display device of claim 22, wherein said absorber is integrated into the transparent substrate.

36. The MEMS display device of claim 22, wherein said operative optical range is from about 400 nm to about 700 nm.

37. The MEMS display device of claim 22, wherein said MEMS device comprises a cellular telephone.

38. The MEMS display device of claim 22, comprising:

a processor that is in electrical communication with the array, the processor being configured to process image data; and

a memory device in electrical communication with the processor.

39. The MEMS display device of claim 38, further comprising a driver circuit configured to send at least one signal to the array.

40. The MEMS display device of claim 39, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

41. The MEMS display device of claim 38, further comprising an image source module configured to send the image data to the processor.

42. The MEMS display device of claim 41, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

43. The MEMS display device of claim 38, further comprising an input device configured to receive input data and to communicate the input data to the processor.