Systems and methods for driving MEMS display

• US 7,702,192 B2
• Filed: 06/21/2006
• Issued: 04/20/2010
• Est. Priority Date: 06/21/2006
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Sampsell, Jeffrey B.
• Primary Examiner(s): HEALY, BRIAN
• Application Number:
  US11/472,880
• Publication Number:
  US 20070296691A1
• Time in Patent Office: 1,399 Days
• Field of Search: 385/14, 385/15, 385/16, 385/17, 385/18, 385/24, 385/1, 385/901, 356/73.1, 345/31, 345/108
• US Class Current: 385/15
• CPC Class Codes: G02B 27/0006 with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation G02B1/18 takes precedence; cleaning in general B08B
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3466 based on interferometric effect
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

Systems and methods for driving a display of MEMS devices are disclosed. In one embodiment, a display device comprises an array of MEMS display elements, at least one test deflecting element, and a deflection sensing circuit connected to the test deflecting element, the deflection sensing circuit being configured to monitor deflection of the test deflecting element without actuating the test deflection element and to provide a signal indicative of one or more parameters affecting operation of the array of MEMS display elements based on the deflection.

Claims

1. A display device, comprising:

an array of MEMS display elements;

at least one test deflecting element;

a deflection sensing circuit connected to the test deflecting element, the deflection sensing circuit being configured to monitor deflection of the test deflecting element without actuating the test deflection element and to provide a signal indicative of one or more parameters affecting operation of the array of MEMS display elements based on the deflection; and

a driving circuit connected to the array of MEMS display elements and the deflection sensing circuit, the driving circuit being configured to drive the array of MEMS display elements based at least in part on the signal communicated from the deflection sensing circuit.

2. The device of claim 1, wherein the deflection sensing circuit is located in the driving circuit.

3. The device of claim 1, wherein each MEMS display element comprises an interferometric modulator, the interferometric modulator comprising an electrode layer, a deflecting element, and a gap defined by the electrode layer and the deflecting element, wherein the deflecting element moves within the gap in response to a voltage applied between the deflecting element and the electrode layer.

4. The device of claim 1, wherein deflection of the test deflecting element is a function of one or more parameters affecting operation of the array of MEMS display elements.

5. The device of claim 1, wherein the signal indicative of one or more parameters affecting operation of the array of MEMS display elements comprises a signal indicative of deflection of the test deflecting element.

6. The device of claim 1, wherein the test deflecting element is formed on a substrate.

7. The device of claim 6, wherein the deflection sensing circuit is configured to monitor deflection of the test deflecting element by monitoring the capacitance between the test deflecting element and the substrate.

8. The device of claim 6, wherein the deflection sensing circuit is configured to apply a substantially constant voltage between the test deflecting element and the substrate.

9. The device of claim 6, wherein the deflection sensing circuit is configured to adjust the voltage applied between the test deflecting element and the substrate to a first voltage such that deflection of the test deflecting element is substantially the same as a reference value.

10. The device of claim 9, wherein the signal indicative of one or more parameters affecting operation of the array of MEMS display elements comprises the first voltage.

11. The device of claim 9, wherein deflection of the test deflecting element is at the reference value when a reference voltage is applied between the test deflecting element and the substrate and the test deflecting element is at a reference temperature.

12. The device of claim 3, wherein the test deflecting element and the deflecting element of the array of interferometric modulators have, respectively, a first and a second electromechanical response, wherein the first and second electromechanical responses have a predetermined relationship with each other.

13. The device of claim 12, wherein the first and second electromechanical response each is a function of temperature.

14. The device of claim 3, wherein the test deflecting element and the deflecting element of the array of interferometric modulators are substantially the same.

15. The device of claim 3, wherein the scale of the test deflecting element is substantially larger than of the deflecting element of the array of interferometric modulators.

16. The device of claim 3, wherein the test deflecting element and the deflecting element of the array of interferometric modulators are made of substantially the same material.

17. The device of claim 3, wherein the test deflecting element and the deflecting element of the array of interferometric modulators are formed by substantially the same process.

18. The device of claim 3, wherein the test deflecting element and the deflecting element of the array of interferometric modulators are formed substantially at the same time.

19. The device of claim 1, wherein the test deflecting element and the array of interferometric modulators are formed on a common substrate.

20. The device of claim 1, wherein the deflection sensing circuit is configured to monitor deflection substantially continuously.

21. The device of claim 1, further comprising:

a display;

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

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

22. The device of claim 21, further comprising a driver circuit configured to send at least one signal to the display.

23. The device of claim 22, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

24. The device of claim 21, further comprising an image source module configured to send said image data to said processor.

25. The device of claim 24, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

26. The device of claim 21, further comprising an input device configured to receive input data and to communicate said input data to said processor.

27. The device of claim 1, wherein one or more parameters affecting operation of the array of MEMS display elements comprise temperature.

28. The device of claim 1, wherein one or more parameters affecting operation of the array of MEMS display elements comprise aging.

29. A display device, comprising:

an array of MEMS display elements;

an array of test deflecting elements formed on a substrate, each test deflecting element being connected in parallel; and

a deflection sensing circuit connected to the array of test deflecting elements, the deflection sensing circuit being configured to monitor capacitance of the array of test deflecting elements and to provide a signal indicative of one or more parameters affecting operation of the array of MEMS display elements based on the capacitance; and

a driving circuit connected to the array of MEMS display elements and the deflection sensing circuit, the driving circuit being configured to drive the array of MEMS display elements based at least in part on the signal communicated from the deflection sensing circuit.

30. The device of claim 29, wherein each MEMS display element comprises an interferometric modulator, the interferometric modulator comprising an electrode layer, a deflecting element, and a gap defined by the electrode layer and the deflecting element, wherein the deflecting element moves within the gap in response to a voltage applied between the deflecting element and the electrode layer.

31. The device of claim 29, wherein deflection of each test deflecting element is a function of one or more parameters affecting operation of the array of MEMS display elements.

32. The device of claim 29, wherein the signal indicative of one or more parameters affecting operation of the array of MEMS display elements comprises a signal indicative of the capacitance.

33. The device of claim 29, wherein the deflection sensing circuit is configured to apply a common and substantially constant voltage between each test deflecting element and the substrate.

34. The device of claim 33, wherein the deflection sensing circuit is configured to adjust the common voltage applied between each test deflecting element and the substrate to a first voltage such that deflection of each test deflecting element is substantially the same as a reference value.

35. The device of claim 34, wherein the signal indicative of one or more parameters affecting operation of the array of MEMS display elements comprises the first voltage.

36. The device of claim 34, wherein deflection of each test deflecting element is at the reference value when a reference voltage is applied between the test deflecting element and the substrate and the test deflecting element is at a reference temperature.

37. The device of claim 30, wherein each test deflecting element and the deflecting element of the array of interferometric modulators have, respectively, a first and a second electromechanical response, wherein the first and second electromechanical responses have a predetermined relationship with each other.

38. The device of claim 37, wherein the first and second electromechanical response each is a function of temperature.

39. The device of claim 30, wherein each test deflecting element and the deflecting element of the array of interferometric modulators are substantially the same.

40. The device of claim 30, wherein each test deflecting element and the deflecting element of the array of interferometric modulators are made of substantially the same material.

41. The device of claim 30, wherein the array of test deflecting elements and the deflecting element of the array of interferometric modulators are formed by substantially the same process.

42. The device of claim 30, wherein the array of test deflecting elements and the deflecting element of the array of interferometric modulators are formed substantially at the same time.

43. The device of claim 29, wherein the array of test deflecting elements and the array of interferometric modulators are formed on a common substrate.

44. The device of claim 29, further comprising a driving circuit connected to the array of MEMS display elements and the deflection sensing circuit, the driving circuit being configured to provide signals to drive the array of MEMS display elements based on the signal communicated from the deflection sensing circuit.

45. The device of claim 29, wherein the deflection sensing circuit is configured to keep each test deflection element from being actuated.

46. The device of claim 29, wherein the one or more parameters affecting operation of the array of MEMS display elements comprise temperature.

47. The device of claim 29, wherein the one or more parameters affecting operation of the array of MEMS display elements comprise aging.

48. A method of driving an array of interferometric modulators, the method comprising:

applying a voltage across one or more test deflecting elements, wherein the voltage is chosen such that the one or more test deflecting elements stays unactuated;

measuring a deflection of the one or more test deflecting elements; and

providing driving signals to an array of interferometric modulators based at least in part on the deflection measurement.

49. The method of claim 48, wherein measuring deflection comprises measuring the capacitance between the one or more test deflecting elements and the substrate.

50. The method of claim 48, wherein the voltage is substantially constant.

51. The method of claim 48, wherein the deflection is function of one or more parameters affecting operation of the array of interferometric modulators.

52. The method of claim 51, wherein the one or more parameters comprise temperature.

53. The method of claim 51, wherein the one or more parameters comprise aging.

54. A method of driving an array of interferometric modulators, the method comprising:

applying a variable voltage across one or more test deflecting elements, the variable voltage comprising a DC component;

adjusting the voltage of the DC component to a value such that deflection of the one or more test deflecting elements is substantially the same as a reference value, wherein the one or more test deflecting elements stays unactuated; and

providing driving signals to an array of interferometric modulators based at least in part on the value.

55. The method of claim 54, wherein measuring deflection comprises measuring the capacitance between the one or more test deflecting elements and the substrate.

56. A display device, comprising:

means for displaying image data;

at least one test deflecting element being different from the displaying means; and

means for monitoring deflection of the test deflecting element, the deflecting monitoring means being configured to monitor deflection of the test deflecting element without actuating the test deflection element and to provide a signal indicative of one or more parameters affecting operation of the displaying means based on the deflection; and

means for driving the displaying means based on the signal.

57. The device of claim 56, wherein the displaying means comprises an array of interferometric modulators.

58. The device of claim 56, wherein the one or more parameters comprise temperature.

59. The device of claim 56, wherein the one or more parameters comprise aging.