Microelectromechanical mirror and mirror array

• US 6,480,320 B2
• Filed: 02/07/2001
• Issued: 11/12/2002
• Est. Priority Date: 02/07/2001
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Transparent Optical, Inc.
• Inventors: Nasiri, Steven S.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Spector, David N.
• Application Number:
  US09/779,189
• Publication Number:
  US 20020131679A1
• Time in Patent Office: 643 Days
• Field of Search: 359/290, 359/291, 385/18
• US Class Current: 359/291
• CPC Class Codes: B81B 3/0062 Devices moving in two or more dimensions, i.e. having special features which allow movement in more than one dimension
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A freely rotatable microelectromechanical mirror and mirror array. Each mirror is connected to a plate flexibly suspended from a plurality of actuators by a plurality of plate flexures. The actuators are flexibly suspended from a support structure by a plurality of actuator flexures. The support structure is held above and electrically isolated from a reference layer by a plurality of standoff posts. The reference layer contains a plurality of actuation means such as control electrodes to move the actuators in first and second directions when actuated. Control voltages can be selectively applied to selective control electrodes to selectively move the actuators, and extend the plurality of plate flexures. The extended plate flexures create a net restoring force or torque to translate or rotate the freely movable plate. The plate and attached mirror are thereby translated or rotated about an arbitrary axis of rotation without stress.

Claims

1. An electrostatically actuated plate, comprising:

a reference surface having a plurality of control electrodes;

a support frame held above the reference surface by a plurality of standoff posts;

a plurality of electrostatic actuators flexibly suspended from the support frame and respectively held over the plurality of control electrodes; and

a freely movable plate flexibly suspended from the plurality of electrostatic actuators and held above the reference surface.

2. The plate of claim 1, wherein each electrostatic actuator is suspended from the support frame by a pair of torsional flexures that define an axis of rotation about which the electrostatic actuator is rotatable toward its respective control electrode.

3. The plate of claim 2, wherein the freely movable plate is flexibly suspended from the plurality of electrostatic actuators by a respective plurality of torsional flexures.

4. The plate of claim 3, further comprising addressing circuitry to selectively apply voltages to selected ones of the plurality of control electrodes to selectively rotate respective ones of the plurality of electrostatic actuators toward their control electrodes.

5. The plate of claim 4, wherein each electrostatic actuator is held above a respective pair of control electrodes having first and second members and is rotatable in first and second directions toward the respective first and second members of the pair of control electrodes.

6. The plate of claim 5, wherein each torsional flexure connecting an electrostatic actuator to the freely movable plate is configured to pull the plate away from the reference surface and toward the electrostatic actuator when the actuator is rotated in the first direction, and to pull the plate toward the reference surface and toward the electrostatic actuator when the actuator is rotated in the second direction.

7. The plate of claim 6, wherein the freely movable plate is configured to rotate by an arbitrary angle in an arbitrary angular direction by applying selected voltages to selected ones of the plurality of control electrodes.

8. The plate of claim 7, wherein the plurality of electrostatic actuators can be rotated to critical angles that are proportional to critical forces, further comprising extending the critical force that can be applied to a selected one of the electrostatic actuators by selectively rotating selected others of the plurality of electrostatic actuators.

9. The plate of claim 7, wherein the plurality of electrostatic actuators are rotated by a first angle, and wherein the freely movable plate is configured to be rotated by a second angle that is a magnification of the first angle.

10. The plate of claim 9, wherein the plurality of electrostatic actuators are symmetrically distributed about and flexibly connected to the freely movable plate.

11. The plate of claim 10, wherein the plurality of electrostatic actuators symmetrically distributed about the freely movable plate comprise three electrostatic actuators distributed about the plate at 120 degree intervals.

12. The plate of claim 10, wherein the plurality of electrostatic actuators symmetrically distributed about the freely movable plate comprise four electrostatic actuators distributed about the plate at 90 degree intervals.

13. A microelectromechanical mirror, comprising:

a reference surface having a plurality of control electrodes;

a support frame held above the reference surface by a plurality of standoff posts;

a plurality of electrostatic actuators flexibly suspended from the support frame and respectively held over the plurality of control electrodes;

a freely movable plate flexibly suspended from the plurality of electrostatic actuators and held above the reference surface; and

a mirrored surface connected to the freely movable plate.

14. The mirror of claim 13, wherein the mirrored surface comprises a highly polished metal.

15. The mirror of claim 13, further comprising a mirror support post coupled between the freely movable plate and the mirrored surface.

16. The mirror of claim 13, wherein each electrostatic actuator is suspended from the support frame by a pair of torsional flexures that define an axis about which the electrostatic actuator is rotatable toward its respective control electrode.

17. The mirror of claim 13, wherein the freely movable plate is flexibly suspended from the plurality of electrostatic actuators by a respective plurality of torsional flexures.

18. The mirror of claim 16, further comprising addressing circuitry to selectively apply voltages to selected ones of the plurality of control electrodes to selectively rotate respective ones of the plurality of electrostatic actuators toward their control electrodes.

19. The mirror of claim 18, wherein each electrostatic actuator is held above a respective pair of control electrodes having first and second members and is rotatable in first and second directions toward the respective first and second members of the pair of control electrodes.

20. The mirror of claim 19, wherein each torsional flexure connecting an electrostatic actuator to the movable plate is configured to flexibly pull the plate away from the reference surface and toward the electrostatic actuator when the actuator is rotated in the first direction, and to flexibly pull the plate toward the reference surface and toward the electrostatic actuator when the actuator is rotated in the second direction.

21. The mirror of claim 19, wherein the mirrored surface is configured to rotate by an arbitrary angle in an arbitrary angular direction by applying selected voltages to selected ones of the plurality of control electrodes.

22. The mirror of claim 19, wherein the plurality of electrostatic actuators can be rotated to critical angles that are proportional to critical forces, further comprising extending the critical force that can be applied to a selected one of the electrostatic actuators by selectively rotating selected others of the plurality of electrostatic actuators.

23. The mirror of claim 19, wherein the plurality of electrostatic actuators are rotated by a first angle, and wherein the freely movable plate is configured to be rotated by a second angle that is a magnification of the first angle.

24. The mirror of claim 21, wherein the plurality of electrostatic actuators are symmetrically distributed about and flexibly connected to the freely movable plate.

25. The mirror of claim 24, wherein the plurality of electrostatic actuators coupled to the freely movable plate comprise three electrostatic actuators.

26. The mirror of claim 24, wherein the plurality of electrostatic actuators coupled to the electrostatically actuated plate comprise four electrostatic actuators.

27. A freely movable plate, comprising:

a plurality of actuators flexibly suspended over a reference surface from a support structure;

a plurality of actuation means for respectively actuating the plurality of actuators; and

a freely movable plate flexibly suspended from the plurality of actuators by a plurality of torsional plate flexures.

28. The plate of claim 27, wherein the support structure comprises a support frame held over the reference surface by a plurality of standoff posts.

29. The plate of claim 27, wherein the support structure comprises a plurality of standoff post pairs, and wherein each actuator is suspended over the reference surface by a respective pair of standoff posts.

30. The plate of claim 27, further comprising addressing circuitry to selectively apply power to selected ones of the plurality of actuation means to selectively actuate respective ones of the plurality of actuators.

31. The plate of claim 30, wherein the freely movable plate is controllably moved in a selected direction by selectively actuating selected ones of the plurality of actuators.

32. The plate of claim 31, wherein the freely movable plate is controllably moved in a vertical direction toward or away from the reference surface.

33. The plate of claim 31, wherein the freely movable plate is controllably rotated about an arbitrary angle of rotation.

34. The plate of claim 30, wherein the plurality of actuators are from among the group comprising electrostatic, electromagnetic, piezoelectric, and thermal actuators.

35. The plate of claim 34, wherein the actuation means for respectively actuating the plurality of actuators are respectively from among the group comprising electrostatic, electromagnetic, piezoelectric, and thermal actuation means.

36. The plate of claim 35, wherein the plurality of actuation means for respectively actuating the plurality of actuators comprise means for respectively rotating the plurality of actuators.

37. The plate of claim 36, wherein the plurality of actuators are configured to rotate and are flexibly suspended from the reference surface by a respective plurality of torsional flexures.

38. The plate of claim 35, wherein the plurality of actuation means for respectively actuating the plurality of actuators comprise means for respectively translating the plurality of actuators.

39. The plate of claim 36, wherein the plurality of actuators are configured to be translated and are flexibly suspended from the reference surface by a respective plurality of bendable flexures.

40. A microelectromechanical mirror, comprising:

a plurality of actuators flexibly suspended over a reference surface from a support structure;

a plurality of actuation means for respectively actuating the plurality of actuators;

a freely movable plate flexibly suspended from the plurality of actuators by a plurality of torsional plate flexures; and

a mirrored surface connected to the freely movable plate.

41. The mirror of claim 40, wherein the support structure comprises a support frame held over the reference surface by a plurality of standoff posts.

42. The mirror of claim 40, wherein the support structure comprises a plurality of standoff post pairs, and wherein each actuator is suspended over the reference surface by a respective pair of standoff posts.

43. The mirror of claim 40, further comprising addressing circuitry to selectively apply power to selected ones of the plurality of actuation means to selectively actuate respective ones of the plurality of actuators.

44. The mirror of claim 43, wherein the microelectromechanical mirror is controllably moved in a selected direction by selectively actuating selected ones of the plurality of actuators.

45. The mirror of claim 44, wherein the microelectromechanical mirror is controllably moved in a vertical direction toward or away from the reference surface.

46. The mirror of claim 44, wherein the microelectromechanical mirror is controllably rotated about an arbitrary angle of rotation.

47. The mirror of claim 43, wherein the plurality of actuators are from among the group comprising electrostatic, electromagnetic, piezoelectric, and thermal actuators.

48. The mirror of claim 47, wherein the actuation means for respectively actuating the plurality of actuators are respectively from among the group comprising electrostatic, electromagnetic, piezoelectric, and thermal actuation means.

49. The mirror of claim 48, wherein the plurality of actuation means for respectively actuating the plurality of actuators comprise means for respectively rotating the plurality of actuators.

50. The mirror of claim 49, wherein the plurality of actuators are configured to rotate and are flexibly suspended from the reference surface by a respective plurality of torsional flexures.

51. The mirror of claim 48, wherein the plurality of actuation means for respectively actuating the plurality of actuators comprise means for respectively translating the plurality of actuators.

52. The mirror of claim 51, wherein the plurality of actuators are configured to be translated and are flexibly suspended from the reference surface by a respective plurality of bendable flexures.

53. A microelectromechanical mirror array, comprising a plurality of microelectromechanical mirrors wherein each mirror comprises:

a reference surface having a plurality of control electrodes;

a support frame held above the reference surface by a plurality of standoff posts;

a plurality of electrostatic actuators flexibly suspended from the support frame and respectively held over the plurality of control electrodes;

a freely movable plate flexibly suspended from the plurality of electrostatic actuators and held above the reference surface; and

a mirrored surface connected to the freely movable plate.

54. The mirror array of claim 53, wherein the mirrored surface of each mirror in the array comprises a highly polished metal.

55. The mirror array of claim 53, further comprising a mirror support post coupled between the freely movable plate and the mirrored surface of each mirror in the array.

56. The mirror array of claim 53, wherein each electrostatic actuator in each mirror in the array is suspended from the mirror'"'"'s support frame by a pair of torsional flexures that define an axis of rotation about which the electrostatic actuator is rotatable toward its control electrode.

57. The mirror array of claim 53, wherein the freely movable plate of each mirror in the array is flexibly suspended from the mirror'"'"'s plurality of electrostatic actuators by a respective plurality of torsional flexures.

58. The mirror array of claim 56, further comprising addressing circuitry to selectively apply voltages to selected ones of the plurality of control electrodes of selected mirrors in the array to selectively rotate respective ones of the plurality of electrostatic actuators of selected mirrors in the array toward their control electrodes.

59. The mirror array of claim 58, wherein each electrostatic actuator of each mirror in the array is held above a respective pair of control electrodes having first and second members and wherein each electrostatic actuator is rotatable in first and second directions toward the respective first and second members of the pair of control electrodes.

60. The mirror array of claim 59, wherein each torsional flexure connecting an electrostatic actuator to a movable plate in each mirror in the array is configured to flexibly pull the plate away from the reference surface and toward the electrostatic actuator when the actuator is rotated in the first direction, and to flexibly pull the plate toward the reference surface and toward the electrostatic actuator when the actuator is rotated in the second direction.

61. The mirror array of claim 59, wherein each mirror in the array is configured to selectively rotate by an arbitrary angle in an arbitrary angular direction when selected voltages are applied to selected ones of the mirror'"'"'s plurality of control electrodes.

62. The mirror array of claim 59, wherein the plurality of electrostatic actuators can be rotated to critical angles that are proportional to critical forces, further comprising extending the critical force that can be applied to a selected one of the electrostatic actuators of a mirror in the array by selectively rotating selected others of the plurality of electrostatic actuators of the mirror in the array.

63. The mirror array of claim 59, wherein the plurality of electrostatic actuators of a mirror in the array are rotated by a first angle, and wherein the mirror is configured to be rotated by a second angle that is a magnification of the first angle.

64. A microelectromechanical mirror array, comprising a plurality of microelectromechanical mirrors wherein each mirror comprises:

a plurality of actuators flexibly suspended over a reference surface from a support structure;

a plurality of actuation means for respectively actuating the plurality of actuators;

a freely movable plate flexibly suspended from the plurality of actuators by a plurality of torsional plate flexures; and

a mirrored surface connected to the freely movable plate.

65. The mirror array of claim 64, wherein the support structure for each mirror in the array comprises a support frame held over the reference surface by a plurality of standoff posts.

66. The mirror array of claim 64, wherein the support structure for each mirror in the array comprises a plurality of standoff post pairs and each actuator of each mirror in the array is suspended over the reference surface by a pair of standoff posts.

67. The mirror array of claim 64, further comprising addressing circuitry to selectively apply power to selected ones of the plurality of actuation means of selected mirrors to selectively actuate respective ones of the selected mirror'"'"'s plurality of actuators.

68. The mirror array of claim 67, wherein a mirror in the array is controllably moved in a selected direction by selectively actuating selected ones of the mirror'"'"'s plurality of actuators.

69. The mirror array of claim 68, wherein a mirror in the array is controllably moved in a vertical direction toward or away from the reference surface.

70. The mirror array of claim 68, wherein a mirror in the array is controllably rotated about an arbitrary angle of rotation.

71. The mirror array of claim 67, wherein for each mirror in the array the plurality of actuators are from among the group comprising electrostatic, electromagnetic, piezoelectric, and thermal actuators.

72. The mirror array of claim 71, wherein for each mirror in the array the actuation means for respectively actuating the plurality of actuators are respectively from among the group comprising electrostatic, electromagnetic, piezoelectric, and thermal actuation means.

73. The mirror array of claim 72, wherein for each mirror in the array the plurality of actuation means for respectively actuating the plurality of actuators comprise means for respectively rotating the plurality of actuators.

74. The mirror array of claim 73, wherein for each mirror in the array the plurality of actuators are configured to rotate and are flexibly suspended from the reference surface by a respective plurality of torsional flexures.

75. The mirror array of claim 72, wherein for each mirror in the array the plurality of actuation means for respectively actuating the plurality of actuators comprise means for respectively translating the plurality of actuators.

76. The mirror array of claim 75, wherein for each mirror in the array the plurality of actuators are configured to be translated and are flexibly suspended from the reference surface by a respective plurality of bendable flexures.