Deflection mechanisms in micromirror devices

• US 20050088721A1
• Filed: 11/05/2004
• Published: 04/28/2005
• Est. Priority Date: 01/10/2003
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Huibers, Andrew G., Richards, Peter, Combes, Michel, Patel, Satyadev
• Granted Patent: US 7,215,458 B2
• Time in Patent Office: Days
• US Class Current: 359/291
• CPC Class Codes: G09G 2320/04 Maintaining the quality of display appearance
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833

Abstract

A method and apparatus for operating spatial light modulator have been disclosed herein. The spatial light modulator comprises an array of micromirror devices, each of which further comprises a reflective deflectable mirror plate attached to a deformable hinge, and an addressing electrode for addressing and deflecting the mirror plate.

Claims

1-17. -17. (canceled)

18. A method for operating a micromirror device having a deflectable reflective mirror plate that is attached to a deformable hinge held on a substrate, and an addressing electrode that is positioned proximate to the mirror plate, the method comprising:

upon receiving an ON state signal, applying a first voltage to the mirror plate and a second voltage to the addressing electrode such that the mirror plate is rotated to an ON state angle of 12°

degrees or more from a non-deflected state, wherein the difference between said two voltages is 30 volts or more.

19. The method of claim 18, wherein the ON state angle is 1420 degrees or more relative to the non-deflected state.

20. The method of claim 18, further comprising:

upon receiving an OFF state signal, adjusting at least one of the applied voltages such that the voltage difference between the mirror plate and addressing electrode is 17 volts or less.

21. The method of claim 20, wherein the second voltage changes 10 volts or more when the mirror plate switches between the ON and OFF state.

22. The method of claim 20, wherein the second voltage changes 15 volts or more when the mirror plate switches between the ON and OFF state.

23. The method of claim 20, wherein the second voltage changes 20 volts or more when the mirror plate switches between the ON and OFF state.

24. The method of claim 20, wherein the change of the second voltage is from 13 to 25 volts when the mirror plate switches between the ON and OFF state.

25. The method of claim 20, wherein the second voltage changes polarity when the mirror plate switches between the ON and OFF state.

26. The method of claim 20, wherein the mirror plate is switched between the ON and OFF state with at most one addressing electrode.

27. The method of claim 18, further comprising:

connecting the addressing electrode to a voltage node that is formed by a connection of a drain of a MOS transistor and a first plate of a storage capacitor, wherein the transistor further comprises a source that is connected to a bitline, and a gate that is connected to a wordline; and

wherein the storage capacitor further comprises a second plate that is connected to a pumping signal whose voltage varies over time when the mirror plate is switched between the ON and OFF state.

28. The method of claim 18, further comprising:

maintaining the second voltage at the addressing electrode for 10 microseconds or more.

29. The method of claim 27, further comprising:

maintaining the second voltage at the addressing electrode for 300 microseconds or more.

30. The method of claim 18, further comprising:

maintaining the second voltage at the addressing electrode for a time from 100 microseconds to 700 microseconds.

31. The method of claim 18, further comprising:

maintaining a voltage difference between the first and second voltages at the mirror plate and addressing electrode for 10 microseconds or more.

32. The method of claim 18, further comprising:

maintaining a voltage difference between the first and second voltages at the mirror plate and addressing electrode for 300 microseconds or more.

33. The method of claim 18, further comprising:

maintaining a voltage difference between the first and second voltages at the mirror plate and addressing electrode for a time from 100 to 700 microseconds.

34. The method of claim 18, further comprising:

placing the addressing electrode at a position such that the distance between the mirror plate and the addressing electrode is from 3 to 9 microns.

35. The method of claim 18, further comprising:

placing the addressing electrode at a position such that the distance between the mirror plate and the addressing electrode is from 4 to 7 microns.

36. The method of claim 18, further comprising:

placing the addressing electrode at a position such that the distance between the mirror plate and the addressing electrode is around 5.5 microns.

36-1. The method of claim 18, further comprising:

placing the addressing electrode at a position such that the distance between the mirror plate and the addressing electrode is around 5.5 microns.

37. A method for operating a micromirror device having a deflectable reflective mirror plate that is attached to a deformable hinge held on a substrate, and an addressing electrode that is positioned proximate to the mirror plate, the method comprising:

upon receiving an OFF state signal, applying a first voltage to the mirror plate and a second voltage to the addressing electrode such that the voltage difference between the addressing electrode and mirror plate is 17 volts or less under which the mirror plate returns to its natural resting state.

38. The method of claim 37, further comprising:

connecting the addressing electrode to a voltage node that is formed by a connection of a drain of a MOS transistor and a first plate of a storage capacitor, wherein the transistor further comprises a source that is connected to a bitline, and a gate that is connected to a wordline; and

wherein the storage capacitor further comprises a second plate that is connected to a pumping signal whose voltage varies over time when the mirror plate is switched between the ON and OFF state.

39. The method of claim 38, further comprising:

maintaining the second voltage at the addressing electrode for 10 microseconds or more.

40. The method of claim 39, further comprising:

maintaining the second voltage at the addressing electrode for 300 microseconds or more.

41. The method of claim 38, further comprising:

maintaining the second voltage at the addressing electrode for a time from 100 microseconds to 700 microseconds.

42. The method of claim 38, further comprising:

maintaining a voltage difference between the first and second voltages at the mirror plate and addressing electrode for 10 microseconds or more.

43. The method of claim 42, further comprising:

maintaining a voltage difference between the first and second voltages at the mirror plate and addressing electrode for 300 microseconds or more.

44. The method of claim 42, further comprising:

maintaining a voltage difference between the first and second voltages at the mirror plate and addressing electrode for a time from 100 to 700 microseconds.

45. The method of claim 38, further comprising:

placing the addressing electrode at a position such that the distance between the mirror plate and the addressing electrode is from 3 to 9 microns.

46. The method of claim 45, further comprising:

placing the addressing electrode at a position such that the distance between the mirror plate and the addressing electrode is from 4 to 7 microns.

47. The method of claim 46, further comprising:

placing the addressing electrode at a position such that the distance between the mirror plate and the addressing electrode is around 5.5 microns.

48. The method of claim 38, further comprising:

upon receiving an ON state signal, applying a first voltage to the mirror plate and a second voltage to the addressing electrode such that the mirror plate is rotated to an ON state angle of 8°

degrees or more from a non-deflected state, wherein the difference between said two voltages is 22 volts or less but sufficient enough to move rotate the mirror plate to the ON state.

49. The method of claim 48, wherein the second voltage changes 10 volts or more when the mirror plate switches between the ON and OFF state.

50. The method of claim 48, wherein the second voltage changes 15 volts or more when the mirror plate switches between the ON and OFF state.

51. The method of claim 48, wherein the second voltage changes 20 volts or more when the mirror plate switches between the ON and OFF state.

52. The method of claim 48, wherein the change of the second voltage is from 13 to 25 volts when the mirror plate switches between the ON and OFF state.

53. The method of claim 48, wherein the second voltage changes polarity when the mirror plate switches between the ON and OFF state.

87. A projection system, comprising:

an illumination system;

a spatial light modulator of claim 48;

and

a projection lens.

88. The spatial light modulator of claim 87, wherein the illumination system further comprises an arc lamp, a light pipe, and a color filter.

89. The spatial light modulator of claim 88, wherein the color filter is positioned between the arc lamp and the light pipe.

90. The spatial light modulator of claim 88, wherein the color filter is positioned behind the light pipe at a propagation path of illumination light from the arc lamp.

54. A spatial light modulator, comprising:

an array of micromirrors, each of which comprises;

a substrate; and

a deflectable mirror plate attached to a deformable hinge that is held on the substrate such that the mirror plate is operable to rotate to an ON state and an OFF state; and

an array of addressing electrodes for addressing and deflecting the mirror plates, wherein a change of a voltage on the addressing electrode when the mirror plate switches between the ON and OFF state is 10 volts or more.

55. The method of claim 54, wherein change of the voltage is 15 volts or more when the mirror plate switches between the ON and OFF state.

56. The method of claim 55, wherein change of the voltage is 20 volts or more when the mirror plate switches between the ON and OFF state.

57. The method of claim 55, wherein change of the voltage is from 13 to 20 volts when the mirror plate switches between the ON and OFF state.

58. The method of claim 54, wherein the voltage on the addressing electrode changes polarity when the mirror plate switches between the ON and OFF state.

59. The spatial light modulator of claim 54, wherein the mirror plate is positioned at a different plane parallel to the substrate than the hinge when the mirror plate is not deflected.

60. The spatial light modulator of claim 54, wherein each of the micromirror only one addressing electrode for deflecting the micromirror.

61. The spatial light modulator of claim 60, wherein the mirror plate of the micromirror device has an area of 400 um² or less.

62. The spatial light modulator of claim 61, wherein the mirror plate of the micromirror device has an area of 225 um² or less.

63. The spatial light modulator of claim 62, wherein the mirror plate of the micromirror device has an area of 100 um² or less.

64. The spatial light modulator of claim 60, wherein the mirror plate is operable to rotate to an ON state angle that is 8°

degrees or more relative to the substrate.

65. The spatial light modulator of claim 64, wherein the ON state angle is 10°

degrees or more.

66. The spatial light modulator of claim 64, wherein the ON state angle is 12°

degrees or more.

67. The spatial light modulator of claim 64, wherein the ON state angle is 14°

degrees or more.

68. The spatial light modulator of claim 60, wherein the voltage difference between the mirror plate and the addressing electrode is from 5.5 volts to 20 volts.

69. The spatial light modulator of claim 68, wherein the voltage difference between the mirror plate and the addressing electrode is from 7.5 volts to 18 volts.

70. The spatial light modulator of claim 54, wherein the voltage difference between the mirror plate and the addressing electrode is from 10 volts to 22 volts.

71. The spatial light modulator of claim 54, wherein the mirror plate has a voltage that is 20 volts or more.

72. The spatial light modulator of claim 54, wherein the voltage on the mirror plate is 30 volts or more.

73. The spatial light modulator of claim 54, wherein addressing electrode has a voltage that is 7.5 volts or more.

74. The spatial light modulator of claim 54, wherein the voltage on the addressing electrode is 15 volts or more.

75. The spatial light modulator of claim 54, a voltage difference of 17 volts or more is present between the mirror plate and the addressing electrode when the mirror plate is at an OFF state.

76. The spatial light modulator of claim 75, wherein the OFF state corresponds to the mirror plate parallel to the substrate.

77. The spatial light modulator of claim 54, wherein the addressing electrode has an area of generally 75% or more of the area of the mirror plate.

78. The spatial light modulator of claim 54, wherein the addressing electrode has an area of generally 95% or more of the area of the mirror plate.

79. The spatial light modulator of claim 54, wherein the mirror plates are formed on a light transmissive substrate, while the addressing electrodes are formed at a semiconductor substrate.

80. The spatial light modulator of claim 54, wherein the mirror plates and addressing electrodes are formed on a same substrate.

81. The spatial light modulator of claim 54, wherein the voltage difference between the mirror plate and the addressing electrode lasts for 10 microseconds or more.

82. The spatial light modulator of claim 54, wherein the voltage difference between the mirror plate and the addressing electrode lasts for 300 microseconds or more.

83. The spatial light modulator of claim 54, wherein the voltage difference between the mirror plate and the addressing electrode lasts for a time period from 100 to 700 microseconds.

84. The spatial light modulator of claim 54, wherein the addressing electrode at a position such that the distance between the mirror plate and the addressing electrode is from 3 to 9 microns.

85. The spatial light modulator of claim 54, wherein the addressing electrode at a position such that the distance between the mirror plate and the addressing electrode is from 4 to 7 microns.

86. The spatial light modulator of claim 54, wherein the addressing electrode at a position such that the distance between the mirror plate and the addressing electrode is around 5.5 microns.

91. A method of operating a spatial light modulator that comprises an array of micromirror devices, each of which comprises a reflective deflectable mirror plate attached to a deformable hinge;

and an addressing electrode for addressing deflecting the mirror plate, the method comprising;

applying a mirror voltage on the mirror plate;

applying a first voltage on the addressing electrode so as to rotate the mirror plate to a first operation state; and

applying a second voltage state on the addressing electrode such that the mirror plate rotates to a second operation state, where in the second voltage and first voltage have opposite polarities.

92. The method of claim 91, wherein the first operation is an ON state at which the mirror plate has an angle of 12°

or more relative to a non-deflected state.

93. The method of claim 92, wherein the angle is 14°

or more relative to the non-deflected state.

94. The method of claim 92, wherein the second operation state is an OFF state.

95. The method of claim 94, wherein the voltage difference between the mirror plate and addressing electrode has an absolute value of 17 volts or less.

96. The method of claim 91, wherein the difference between the first and second voltage on the addressing electrode when the mirror plate switches between the first and second operation states has an absolute value of 10 volts or more.

97. The method of claim 96, wherein the absolute value is 15 volts or more.

98. The method of claim 96, wherein the absolute value is from 13 to 25 volts.

99. The method of claim 92, wherein the voltage difference between the mirror plate and the addressing electrode when the mirror plate is at the ON state is 30 volts or more.

100. The method of claim 91, further comprising:

connecting the addressing electrode to a voltage output node at a connection of a first plate of a capacitor and a drain of a transistor, wherein the transistor comprises a gate connected to wordline signal, and a source connected to bitline signal; and

wherein the capacitor comprises a second plate connected to a change-pumping signal whose voltage varies over time during operation.