MEMS device having deformable membrane characterized by mechanical persistence

• US 7,936,497 B2
• Filed: 07/28/2005
• Issued: 05/03/2011
• 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, Kothari, Manish
• Primary Examiner(s): Mack; Ricky L
• Assistant Examiner(s): Tra; Tuyen Q
• Application Number:
  US11/192,438
• Publication Number:
  US 20060077156A1
• Time in Patent Office: 2,105 Days
• Field of Search: 359/290, 359/291, 359/292, 359/295, 359/298, 359/220, 359/223, 359/224, 359/320, 359/323, 359/324
• 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 3/3466 based on interferometric effect

Abstract

An interferometric modulator is provided having a faster deformation time constant on actuation than relaxation time constant upon release from actuation. In some embodiments, apertures are formed in a mechanical membrane to decrease pressure, including liquid and/or gas pressures, on the membrane when actuated. In other embodiments, a dampening layer is disposed in close proximity above the membrane to apply greater downward pressure on the membrane and therefore slow the motion of the membrane when released from an actuated state. Other embodiments comprise structures, such as a heating element or vacuum device, to manipulate pressures above and/or below the mechanical membrane to affect the mechanical persistence of the display device.

Claims

1. A microelectromechanical (MEMS) device, comprising:

a substrate;

a movable first layer, the first layer and the substrate configured to have a first cavity therebetween, the first cavity having a first pressure, the first layer movable with respect to the substrate in response to a voltage applied to at least the first layer and wherein movement of the first layer deforms the first cavity;

a second layer, separate from the substrate, and disposed so the first layer is between the second layer and the substrate, the second layer and the first layer configured to have a second cavity therebetween, the second cavity having a second pressure; and

a structure, separate from the first and second layers, the structure being in fluid communication with at least one of the first and second cavities, the structure configured to manipulate at least one of the first and second pressures to alter a speed of the movable first layer when the movable first layer is actuated and released;

wherein at least one of the second layer and the substrate are at least partially transparent to light incident upon the device.

2. The MEMS device of claim 1, wherein the structure is in fluid communication with both the first and second cavities, the structure configured to manipulate both the first and second pressures.

3. The MEMS device of claim 1, wherein one of the first pressure and the second pressure is a gas pressure.

4. The MEMS device of claim 3, wherein the first pressure and the second pressure are air pressures.

5. The MEMS device of claim 1, wherein one of the first pressure and the second pressure is a liquid pressure.

6. The MEMS device of claim 1, wherein the structure comprises a heating element.

7. The MEMS device of claim 6, wherein the second layer is disposed between the heating element and the first layer.

8. The MEMS device of claim 7, further comprising a back plate, wherein the second layer is disposed between the back plate and the first layer.

9. The MEMS device of claim 8, wherein the heating element is disposed between the back plate and the second layer.

10. The MEMS device of claim 6, wherein the second layer comprises at least one aperture fluidly coupling the second cavity and the heating element.

11. The MEMS device of claim 10, wherein the first layer comprises at least one aperture fluidly coupling the first cavity and the second cavity.

12. The MEMS device of claim 1, wherein the structure comprises a vacuum device.

13. The MEMS device of claim 12, wherein the vacuum device is configured to manipulate the first and second pressures independently from one another.

14. The MEMS device of claim 13, further comprising at least one support structure between the substrate and the first layer, the at least one support structure comprising at least one aperture such that the first cavity is in fluid communication with the vacuum device.

15. The MEMS device of claim 14, further comprising at least one support structure between the first layer and the second layer, the at least one support structure comprising at least one aperture such that the second cavity is in fluid communication with the vacuum device.

16. The MEMS device of claim 12, wherein the vacuum device is configured to manipulate the first and second pressures together.

17. The MEMS device of claim 12, wherein the second layer comprises at least one aperture, wherein the first layer comprises at least one aperture, and wherein the first and second cavities are in fluid communication with one another.

18. The MEMS device of claim 1, wherein the second layer is spaced from the first layer by a distance between 200 to 2000 angstroms.

19. The MEMS device of claim 18, further comprising a back plate, wherein the second layer is disposed between the back plate and the first layer.

20. The MEMS device of claim 1, wherein the substrate comprises glass.

21. The MEMS device of claim 20, further comprising a third layer disposed between the first layer and the substrate, wherein the movable first layer is reflective of light and the third layer is partially reflective of light.

22. The MEMS device of claim 1, further comprising:

a display;

a processor that is in electrical communication with said display, said processor being configured to process image data;

a memory device in electrical communication with said processor.

23. The MEMS device of claim 22, further comprising:

a driver circuit configured to send at least one signal to said display.

24. The MEMS device of claim 23, further comprising:

a controller configured to send at least a portion of said image data to said driver circuit.

25. The MEMS device of claim 22, further comprising:

an image source module configured to send said image data to said processor.

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

27. The MEMS device of claim 22, further comprising:

an input device configured to receive input data and to communicate said input data to said processor.

28. A microelectromechanical (MEMS) device, comprising:

a substrate;

a first layer comprising at least one aperture, the first layer and the substrate configured to have a first cavity therebetween, the first layer movable with respect to the substrate in response to a voltage applied to at least the first layer; and

a second layer comprising at least one aperture, the second layer and the first layer configured to have a second cavity therebetween, wherein the first and second cavities are in fluid communication through the at least one aperture of the first layer.

29. The MEMS device of claim 28, further comprising a back plate, wherein the second layer is disposed between the back plate and the first layer.

30. The MEMS device of claim 28, wherein the second layer is spaced from the first layer by a distance between 200 to 2000 angstroms.

31. The MEMS device of claim 28, wherein the second layer is between 1000 angstroms to 10 microns thick.

32. The MEMS device of claim 28, further comprising:

a display;

a processor that is in electrical communication with said display, said processor being configured to process image data;

a memory device in electrical communication with said processor.

33. The MEMS device of claim 32, further comprising:

a driver circuit configured to send at least one signal to said display.

34. The MEMS device of claim 33, further comprising:

a controller configured to send at least a portion of said image data to said driver circuit.

35. The MEMS device of claim 28, further comprising:

an image source module configured to send said image data to said processor.

36. The MEMS device of claim 35, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

37. The MEMS device of claim 28, further comprising:

an input device configured to receive input data and to communicate said input data to said processor.

38. The MEMS device of claim 28, wherein the substrate comprises glass.

39. The MEMS device of claim 28, further comprising a third layer disposed between the first layer and the substrate, wherein the movable first layer is reflective of light and the third layer is partially reflective of light.

40. The MEMS device of claim 28, wherein the at least one aperture of the first layer and the at least one aperture of the second layer are not aligned with one another.

41. The MEMS device of claim 28, wherein the first and second layers each comprise edge portions, wherein the at least one aperture of the first or second layer is formed on an edge portion of the first or second layer.

42. The MEMS device of claim 28, wherein the substrate, first layer and second layer comprise a pixel.

43. The MEMS device of claim 42, further comprising an array of pixels.

44. A microelectromechanical (MEMS) device, comprising:

means for supporting a MEMS device;

means for reflecting light, the supporting means and the reflecting means configured to have a first cavity therebetween, the first cavity having a first pressure;

means for enclosing a second cavity, wherein said second cavity is located between said enclosing means and said reflecting means, the second cavity having a second pressure; and

means for manipulating at least one of the first and second pressures.

45. The MEMS device of claim 44, wherein the means for manipulating at least one of the first and second pressures comprises at least one of the following:

a heating element and a vacuum device.

46. The MEMS device of claim 44, wherein said supporting means comprise a substrate.

47. The MEMS device of claim 44, wherein said reflecting means comprises a reflective material.

48. The MEMS device of claim 44, wherein said enclosing means comprises a layer of material.

49. The MEMS device of claim 48, wherein said reflecting means is configured to be movable, and said enclosing means is configured to dampen movement of the reflecting means.

50. The MEMS device of claim 49, further comprising a back plate, wherein the enclosing means is disposed between the back plate and reflecting means.

51. The MEMS device of claim 50, wherein the manipulating means is located on said back plate.

52. The MEMS device of claim 44, wherein said enclosing means comprises a back plate.

53. The MEMS device of claim 44, wherein one of the first pressure and the second pressure is a gas pressure.

54. The MEMS device of claim 44, wherein the first pressure and the second pressure are air pressures.

55. The MEMS device of claim 44, wherein one of the first pressure and the second pressure is a liquid pressure.

56. A microelectromechanical (MEMS) device, comprising:

means for supporting a MEMS device;

means for conducting electricity, the conducting means comprising at least one aperture, the conducting means configured to be movable with respect to the supporting means in response to a voltage applied to at least the conducting means, the supporting means and the conducting means configured to have a first cavity therebetween; and

means for dampening movement of the conducting means, the dampening means comprising at least one aperture, the conducting means and the dampening means configured to have a second cavity therebetween.

57. The MEMS device of claim 56, wherein said supporting means comprise a substrate.

58. The MEMS device of claim 56, wherein said conducting means comprises a conductive material.

59. The MEMS device of claim 58, wherein said conducting means comprises a reflective material.

60. The MEMS device of claim 56, wherein said dampening means comprises a layer of material.

61. The MEMS device of claim 56, further comprising a back plate, wherein the dampening means is disposed between the back plate and the conducting means.

62. A microelectromechanical (MEMS) device comprising:

a substrate;

a movable layer mechanically coupled to the substrate, the movable layer movable between a first position and a second position, wherein the movable layer is configured to move from the second position to the first position at a first rate and wherein the movable layer is configured to move from the first position to the second position at a second rate that is faster than the first rate;

a cavity defined between the substrate and the movable layer; and

a fluid conductive element comprising at least one aperture through which fluid within the MEMS device is configured to flow, wherein the fluid flows from inside the cavity to outside the cavity through the fluid conductive element at a first flowrate upon movement of the movable layer from the first position to the second position and from outside the cavity to inside the cavity through the fluid conductive element at a second flowrate upon movement of the movable layer from the second position to the first position, the second flowrate slower than the first flowrate.

63. The MEMS device of claim 62, wherein the fluid conductive element comprises a layer disposed on a side of the movable layer opposite the substrate.

64. The MEMS device of claim 62, wherein the first position is further from the substrate than is the second position.

65. The MEMS device of claim 62, wherein the MEMS device is substantially reflective to incident light when the movable layer is in the second position and wherein the MEMS device is substantially non-reflective to incident light when the movable layer is in the first position.

66. The MEMS device of claim 62, further comprising a partially reflective layer between the substrate and the movable layer.

67. The MEMS device of claim 62, wherein the fluid comprises air.

68. The MEMS device of claim 62, wherein the fluid comprises a liquid.

69. The MEMS device of claim 62, wherein the fluid conductive element comprises at least one aperture through the movable layer.

70. The MEMS device of claim 62, further comprising a support structure between the movable layer and the substrate.

71. The MEMS device of claim 70, wherein the support structure includes at least one wall surrounding the cavity, the at least one wall configured to inhibit fluid flow between inside the cavity and outside the cavity.