Micromirrors with OFF-angle electrodes and stops

• US 20030214639A1
• Filed: 05/13/2003
• Published: 11/20/2003
• Est. Priority Date: 08/03/2000
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Huibers, Andrew G., Patel, Satyadev, Spindt, Christopher J., Heureux, Peter J.
• Granted Patent: US 7,099,065 B2
• Time in Patent Office: Days
• US Class Current: 353/98
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 2203/058 Rotation out of a plane parallel to the substrate
• CPC Class Codes: B81B 3/0051 For defining the movement, i.e. structures that guide or limit the movement of an element mechanical arrangements for preventing or damping vibration or shock H01H3/60
• CPC Class Codes: C10L 1/026 for compression ignition
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A spatial light modulator is disclosed, along with methods for making such a modulator that comprises an array of mirror devices each having at least a first electrode and a second electrode. The first electrode is designated for driving the mirror plate of the micromirror device to an ON state, and the second electrode is designated for driving the mirror plate to an OFF state. The two electrodes can be disposed on the same side of the mirror plate but on opposite sides of the rotation axis of the mirror plate for driving the mirror plate to rotate in opposite directions. Alternatively, the two electrodes can be disposed on the opposite sides of the mirror plate, but on the same side of the rotation axis of the mirror plate for driving the mirror plate to rotate in opposite directions. The ON state and OFF state of the mirror plate can be defined by stops. The stops may be formed on substrate(s), hinge structures holding the mirror plates of the micromirror device and/or a desired location within the micromirror device. Alternatively, the electrodes for the ON state and the OFF state can be used as stops, either individually or in combination, or in combination with other component(s), such as substrate(s) of the micromirror device. The OFF state angle and the ON state angle are preferably different.

Claims

1. A spatial light modulator comprising:

an array of pixels, each pixel comprising micromirrors on a substrate, each micromirror comprising a reflective plate held by a hinge and being movable by more than one electrode, each micromirror movable by a first electrode for moving the micromirror to an ON position at a positive angle from a non-actuated position, and a second electrode for moving the micromirror to an OFF position that is at a negative angle relative to a non-deflected rest position, the second electrode being disposed on a side of the reflective plate opposite to that of the first electrode.

2. The spatial light modulator of claim 1, wherein the ON position is at an angle of 10 degrees or more from the non-deflected position.

3. The spatial light modulator of claim 2, wherein the OFF position is at an angle of −

1 to −

8 degrees from the non-deflected position.

4. The spatial light modulator of claim 1, wherein the OFF position is at an angle of from −

1 to −

8 degrees from the non-deflected position.

5. The spatial light modulator of claim 1, wherein the ON angle is 10 degrees or more and the OFF angle is a negative angle and less than 10 degrees.

6. The spatial light modulator of claim 1, wherein the hinge is connected to the mirror plate at a point not at the center of the mirror plate.

7. The spatial light modulator of claim 1, wherein the hinge is disposed in a different plane from the mirror plate.

8. The spatial light modulator of claim 6, wherein the hinge is disposed in a different plane from the mirror plate.

9. The spatial light modulator of claim 1, wherein each pixel comprises separately operable first electrode and wherein multiple pixels share a common second electrode.

10. The spatial light modulator of claim 9, wherein the common second electrode is a conductive film strip that extends along a row or column of pixels.

11. The spatial light modulator of claim 9, wherein the common second electrode is a conductive grid used for applying an electric field to all pixels at a time.

12. The spatial light modulator of claim 9, wherein when first electrodes actuate a first group of micromirrors, a voltage from the common second electrode deflects micromirrors not in the first group.

13. The spatial light modulator of claim 1, wherein the first electrode of each pixel is disposed on a second substrate positioned proximate to said substrate.

14. The spatial light modulator of claim 1, wherein the second electrode of each pixel is disposed on a second substrate positioned proximate to said substrate.

15. The spatial light modulator of claim 1, wherein said substrate is a substrate transmissive to visible light.

16. The spatial light modulator of claim 1, wherein said substrate is a semiconductor substrate.

17. The spatial light modulator of claim 4, wherein the OFF position is at an angle of from −

2 to −

6 degrees from the non-deflected position.

18. The spatial light modulator of claim 17, wherein the OFF position is at an angle of from −

3 to −

5 degrees.

19. The spatial light modulator of claim 17, wherein the ON position is at an angle of from 14 to 18 degrees.

20. The spatial light modulator of claim 1, wherein the reflective plate abuts said substrate in the ON position.

21. The spatial light modulator of claim 1, wherein the reflective plate abuts a protrusion in the ON state, the protrusion disposed with a gap between the plate and said first electrode.

22. The spatial light modulator of claim 21, wherein the protrusion is connected to a post which holds the micromirror to said substrate.

23. The spatial light modulator of claim 21, wherein the reflective plate abuts an electrically conductive layer of the protrusion.

24. The spatial light modulator of claim 23, wherein the electrically conductive layer comprises an early transition metal oxide or nitride.

25. The spatial light modulator of claim 1, wherein the reflective plate abuts said substrate in the OFF position.

26. The spatial light modulator of claim 1, wherein the reflective plate abuts a protrusion in the OFF state, the protrusion disposed with a gap between the plate and said first electrode.

27. The spatial light modulator of claim 26, wherein the protrusion is connected to a post which holds the micromirror to said substrate.

28. The spatial light modulator of claim 26, wherein the reflective plate abuts an electrically conductive layer of the protrusion.

29. The spatial light modulator of claim 28, wherein the electrically conductive layer comprises an early transition metal oxide or nitride.

33. The spatial light modulator of claim 1, wherein multiple pixels share a common second electrode disposed on said substrate.

34. The spatial light modulator of claim 1, wherein the second electrode is an anti-reflective coating on said substrate that reduces reflections of incident visible light.

35. The spatial light modulator of claim 1, wherein the second electrode is an electrically conductive layer within a multi-layer anti-reflective coating on said substrate.

36. The spatial light modulator of claim 1, wherein the second electrode is disposed with a gap between the second electrode and the reflective plate and is on the same side of the reflective plate as the first electrode.

37. The spatial light modulator of claim 36, wherein the second electrode is disposed closer to the reflective plate than the first electrode.

38. The spatial light modulator of claim 1, wherein the second electrode is held via posts to said substrate and the first electrode is disposed on a second substrate bonded to said substrate.

39. The spatial light modulator of claim 1, wherein the second electrode is part of a multi layer OFF state stop.

44. The spatial light modulator of claim 1, wherein the OFF position is at an angle of from −

1 to −

8 degrees from the non-deflected position.

45. The spatial light modulator of claim 1, wherein the ON angle is 10 degrees or more and the OFF angle is a negative angle and less than 10 degrees.

57. The spatial light modulator of claim 44, wherein the OFF position is at an angle of from −

2 to −

6 degrees from the non-deflected position.

58. The spatial light modulator of claim 57, wherein the OFF position is at an angle of from −

3 to −

5 degrees.

59. The spatial light modulator of claim 57, wherein the ON position is at an angle of from 14 to 18 degrees.

40. (Asymmetric plus off state stop) A spatial light modulator comprising:

an array of micromirrors on a substrate, each micromirror comprising a reflective plate being movable by more than one electrode, a first electrode for moving the micromirror to an ON position at an angle of 10 degrees or more from a non-actuated position, and a second electrode for moving the micromirror to an OFF position that is at an angle of from −

1 to −

8 degrees, wherein a micromirror stop is disposed on a side of the reflective plate opposite to that of the substrate, the reflective plate abutting the stop at a predetermined distance from the substrate and at an angle of from −

1 to−

8 degrees.

41. (asymmetric plus off state stop) A spatial light modulator comprising an array of pixels, each pixel comprising a micromirror having a reflective plate held via a hinge and capable of movement upon application of an electrostatic force from a non-deflected position, a first electrode for moving the micromirror to an ON position, a first stop for stopping the micromirror at a predetermined ON angle, a second electrode for moving the micromirror to an OFF position and a second stop for stopping the micromirror at the OFF position at an angle that is in the opposite direction from a non-deflected state of the micromirror and less than the ON angle.

42. The spatial light modulator of claim 41, wherein the ON position is at an angle of 10 degrees or more from the non-deflected position.

43. The spatial light modulator of claim 42, wherein the OFF position is at an angle of −

1 to −

8 degrees from the non-deflected position.

46. The spatial light modulator of claim 41, wherein the hinge is connected to the reflective plate at a point not at the center of the plate.

47. The spatial light modulator of claim 41, wherein the hinge is disposed in a different plane from the plate.

48. The spatial light modulator of claim 46, wherein the hinge is disposed in a different plane from the mirror plate.

49. The spatial light modulator of claim 41, wherein each pixel comprises separately operable first electrode and wherein multiple pixels share a common second electrode.

50. The spatial light modulator of claim 49, wherein the common second electrode is a conductive strip that extends along a row or column of pixels.

51. The spatial light modulator of claim 49, wherein the common second electrode is a conductive grid used for applying an electrostatic force to all pixels at a time.

52. The spatial light modulator of claim 49, wherein when first electrodes actuate a first group of micromirrors, a voltage from the common second electrode deflects micromirrors not in the first group.

53. The spatial light modulator of claim 41, wherein the first electrode of each pixel is disposed on a second substrate positioned proximate to said substrate.

54. The spatial light modulator of claim 41, wherein the second electrode of each pixel is disposed on a second substrate positioned proximate to said substrate.

55. The spatial light modulator of claim 41, wherein said substrate is a substrate transmissive to visible light.

56. The spatial light modulator of claim 41, wherein said substrate is a semiconductor substrate.

60. The spatial light modulator of claim 41, wherein the reflective plate abuts said substrate in the ON position.

61. The spatial light modulator of claim 41, wherein the reflective plate abuts a protrusion in the ON state, the protrusion disposed with a gap between the plate and said first electrode.

62. The spatial light modulator of claim 61, wherein the protrusion is connected to a post which holds the micromirror to said substrate.

63. The spatial light modulator of claim 61, wherein the reflective plate abuts an electrically conductive layer of the protrusion.

64. The spatial light modulator of claim 63, wherein the electrically conductive layer comprises an early transition metal oxide or nitride.

65. The spatial light modulator of claim 41, wherein the reflective plate abuts said substrate in the OFF position.

66. The spatial light modulator of claim 41, wherein the reflective plate abuts a protrusion in the OFF state, the protrusion disposed with a gap between the plate and said first electrode.

67. The spatial light modulator of claim 66, wherein the protrusion is connected to a post which holds the micromirror to said substrate.

68. The spatial light modulator of claim 66, wherein the reflective plate abuts an electrically conductive layer of the protrusion.

69. The spatial light modulator of claim 68, wherein the electrically conductive layer comprises an early transition metal oxide or nitride.

70. The spatial light modulator of claim 41, comprising an ON state stop and on OFF state stop, each stop being connected to posts formed on said substrate.

71. The spatial light modulator of claim 70, wherein the ON state and OFF state stops are disposed in the same plane.

72. The spatial light modulator of claim 70, wherein the ON state and OFF state stops are disposed in different planes.

73. The spatial light modulator of claim 41, wherein multiple pixels share a common second electrode disposed on said substrate.

74. The spatial light modulator of claim 41, wherein the second electrode is an anti-reflective coating on said substrate that reduces reflections of incident visible light.

75. The spatial light modulator of claim 41, wherein the second electrode is an electrically conductive layer within a multi-layer anti-reflective coating on said substrate.

76. The spatial light modulator of claim 41, wherein the second electrode is disposed with a gap between the second electrode and the reflective plate and is on the same side of the reflective plate as the first electrode.

77. The spatial light modulator of claim 76, wherein the second electrode is disposed closer to the reflective plate than the first electrode.

78. The spatial light modulator of claim 41, wherein the second electrode is held via posts to said substrate and the first electrode is disposed on a second substrate bonded to said substrate.

79. The spatial light modulator of claim 41, wherein the second electrode is part of a multi layer OFF state stop.

80. The spatial light modulator of claim 41, wherein the second electrode is disposed on a side of the reflective plate opposite to that of the first electrode.

81. The spatial light modulator of claim 41, wherein the second electrode is disposed on the same side of the reflective plate as the first electrode but on an opposite side of the axis of rotation.

82. A spatial light modulator comprising:

an array of pixels comprising micromirrors on a visible light transmissive substrate, each micromirror comprising a micromirror plate held by a hinge on the light transmissive substrate and further comprising a first stopping mechanism for stopping the micromirror at a predetermined angle in an ON position, and a second stopping mechanism for stopping the micromirror at a predetermined angle in an OFF position.

30. The spatial light modulator of claim 101, comprising an ON state stop and on OFF state stop, each stop being connected to posts formed on said substrate.

31. The spatial light modulator of claim 30, wherein the ON state and OFF state stops are disposed in the same plane.

32. The spatial light modulator of claim 30, wherein the ON state and OFF state stops are disposed in different planes.

83. The spatial light modulator of claim 82, wherein the first stopping mechanism is the light transmissive substrate.

84. The spatial light modulator of claim 83, wherein the second stopping mechanism is the light transmissive substrate.

85. The spatial light modulator of claim 83, wherein the second stopping mechanism is a protrusion spaced by a gap away from the micromirror plate and disposed on a side of the micromirror plate opposite to that of the light transmissive substrate.

86. The spatial light modulator of claim 82, wherein the first stopping mechanism is a protrusion spaced by a gap away from the micromirror plate and disposed on a side of the micromirror plate opposite to that of the light transmissive substrate.

87. The spatial light modulator of claim 86, wherein the second stopping mechanism is the light transmissive substrate.

88. The spatial light modulator of claim 86, wherein the second stopping mechanism is a protrusion spaced by a gap away from the micromirror plate and disposed on a side of the micromirror plate opposite to that of the light transmissive substrate.

89. The spatial light modulator of claim 82, wherein the light transmissive substrate is glass or quartz.

90. The spatial light modulator of claim 82, wherein the ON position is at an angle of 10 degrees or more from the non-deflected position.

91. The spatial light modulator of claim 90, wherein the OFF position is at an angle of −

1 to −

8 degrees from the non-deflected position.

92. The spatial light modulator of claim 82, wherein the hinge is connected to the reflective plate at a point not at the center of the plate.

93. The spatial light modulator of claim 82, wherein the hinge is disposed in a different plane from the plate.

94. The spatial light modulator of claim 82, wherein each pixel comprises a separately operable first electrode and wherein multiple pixels share a common second electrode.

95. The spatial light modulator of claim 94, wherein the common second electrode is a conductive strip that extends along a row or column of pixels.

96. The spatial light modulator of claim 94, wherein the common second electrode is a conductive grid used for applying an electrostatic force to all pixels at a time.

97. The spatial light modulator of claim 95, wherein when first electrodes actuate a first group of micromirrors, a voltage from the common second electrode deflects micromirrors not in the first group.

98. The spatial light modulator of claim 82, wherein the first electrode of each pixel is disposed on a second semiconductor substrate positioned proximate to said light transmissive substrate.

99. The spatial light modulator of claim 82, wherein the second electrode is part of an anti-reflection coating.

100. The spatial light modulator of claim 82, wherein the second electrode covers substantially all of the light transmissive substrate and is substantially transparent.

101. The spatial light modulator of claim 82, wherein the second electrode is a fully or partially opaque layer formed as strips or a grid on the light transmissive substrate.

102. The spatial light modulator of claim 82, wherein the second electrode comprises a transition metal.

103. A spatial light modulator comprising an array of micromirrors, electrodes for selectively actuating the micromirrors to a first position at an angle from a resting position, and an anti-reflective coating on a light transmissive substrate, the coating having an electrically conductive layer which acts as a second electrode when a voltage is applied thereto to actuate the micromirrors to a second position different from the first position.

104. A spatial light modulator comprising an array of micromirrors, electrodes for selectively actuating the micromirrors to a first position at an angle from a resting position, and separate or overlapping strips of electrically conductive material on a light transmissive substrate, the strips disposed proximate to gaps between adjacent micromirrors, the strips connected to a voltage source.