Method and device for modulating light with a time-varying signal

• US 20050231790A1
• Filed: 03/01/2005
• Published: 10/20/2005
• Est. Priority Date: 05/05/1994
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Iridigm Display Corporation (Qualcomm, Inc.)
• Inventors: Miles, Mark W.
• Granted Patent: US 7,012,732 B2
• Time in Patent Office: Days
• US Class Current: 359/290
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G02B 2006/12104 Mirror; Reflectors or the like
• 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: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: G02B 27/01 Head-up displays
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 6/12 of the integrated circuit kind electric integrated circuits H01L27/00
• CPC Class Codes: G02F 1/13725 based on guest-host interaction G02F1/13762, G02F1/13737, take precedence
• CPC Class Codes: G02F 1/169 based on orientable non-spherical particles having a common optical characteristic, e.g. suspended particles of reflective metal flakes
• CPC Class Codes: G02F 1/216 using liquid crystals, e.g. liquid crystal Fabry-Perot filters
• CPC Class Codes: G02F 2203/03 scattering
• CPC Class Codes: G06F 3/1431 using a single graphics controller
• CPC Class Codes: G06F 3/1446 display composed of modules, e.g. video walls
• CPC Class Codes: G06F 3/147 using display panels
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2300/0452 : Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 3/001 : using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: G09G 3/2014 : by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/2074 : using sub-pixels
• CPC Class Codes: G09G 3/2077 : by a combination of two or more gradation control methods
• CPC Class Codes: G09G 3/3466 : based on interferometric effect
• CPC Class Codes: G09G 5/02 : characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H01Q 9/26 : with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength resonant loop antennas H01Q7/00

Abstract

Light in the visible spectrum is modulated using an array of modulation elements, and control circuitry connected to the array for controlling each of the modulation elements independently, each of the modulation elements having a surface which is caused to exhibit a predetermined impedance characteristic to particular frequencies of light. The amplitude of light delivered by each of the modulation elements is controlled independently by pulse code modulation. Each modulation element has a deformable portion held under tensile stress, and the control circuitry controls the deformation of the deformable portion. Each deformable element has a deformation mechanism and an optical portion, the deformation mechanism and the optical portion independently imparting to the element respectively a controlled deformation characteristic and a controlled modulation characteristic. The deformable modulation element may be a non-metal. The elements are made by forming a sandwich of two layers and a sacrificial layer between them, the sacrificial layer having a thickness related to the final cavity dimension, and using water or an oxygen based plasma to remove the sacrificial layer.

Claims

1-53. -53. (canceled)

54. A device for modulating light, comprising:

first and second layers separated by a space, wherein a dimension of said space is changeable in response to a voltage applied across said first and second layers; and

a control circuit configured to apply the voltage across the first and second layers to maintain the dimension of said space at a desired height, said voltage comprising a time-varying signal.

55. The device of claim 54, wherein the voltage signal is periodic.

56. The device of claim 55, wherein the voltage signal comprises a square-wave with a duty cycle of less than 100 percent.

57. The device of claim 56, wherein the voltage signal comprises a square-wave having a duty cycle of approximately 50 percent.

58. The device of claim 54, wherein said control circuit is configured to change said dimension of said space by changing said voltage.

59. The device of claim 55, wherein the voltage signal comprises a sinusoidal signal.

60. The device of claim 54, wherein the voltage signal comprises a stream of pulses.

61. The device of claim 60, wherein the pulses vary in width.

62. The device of claim 54, wherein said voltage controls intensity of light modulated by the device

63. The device of claim 54, wherein said voltage causes modulation of light to produce at least one color.

64. The device of claim 54, further comprising a plurality of first and second layers, each being separated by a respective space, wherein each of the plurality of first and second layers comprises at least a portion of a picture element.

65. The device of claim 64, wherein each of the plurality of first and second layers is controlled independently.

66. The device of claim 54, wherein the dimension of said space is substantially zero when the voltage applied across the first and second layers exceeds a threshold voltage difference.

67. The device of claim 66, wherein the dimension of said space is different from zero when the voltage applied across the first and second layers is below the threshold voltage difference.

68. A method of controlling first and second layers separated by a space, a dimension of said space being changeable in response to a voltage applied across said first and second layers, the method comprising:

applying said voltage across the first and second layers to maintain the dimension of said space at a desired height, said voltage being varying over time.

69. The method of claim 68, wherein applying said voltage comprises applying a stream of pulses.

70. The method of claim 69, further comprising varying the width of said pulses.

71. The method of claim 68, further comprising controlling intensity of light modulated by said device by controlling said applied voltage.

72. The method of claim 68, further comprising independently controlling application of said voltage across a plurality of first and second layers.

73. The method of claim 68, further comprising reducing the dimension of said space to a height of substantially zero when the voltage applied across the first and second layers exceeds a threshold voltage difference.

74. The method of claim 68, further comprising maintaining the dimension of said space at a height different than zero when the voltage applied across the first and second layers is below a threshold voltage difference.

75. The device of claim 68, wherein applying said the voltage comprises applying a sinusoidal signal.

76. The method of claim 68, wherein applying said voltage comprises applying a stream of pulses.

77. The method of claim 76, further comprising varying width of pulses in said stream of pulses.

78. The method of claim 68, further comprising modulating light to produce at least one color.

79. The method of claim 78, further comprising displaying at least a portion of a picture element.

80. The method of claim 68, further comprising controlling intensity of light.

81. The method of claim 68, further comprising reducing the dimension of said space to a height of substantially zero when the voltage applied across the first and second layers exceeds a threshold voltage difference.

82. The method of claim 68, further comprising adjusting the dimension of said space to a height different from zero when the voltage applied across the first and second layers is below a threshold voltage difference.

83. A device for modulating light, comprising:

first and second means for adjusting a dimension of a space there between, wherein the dimension of said space is changeable in response to a voltage applied across said first and second adjusting means; and

means for controlling application of the voltage across said first and second adjusting means to maintain the dimension of said space at a desired height, said voltage comprising a time-varying signal.

84. The device of claim 83, wherein the voltage signal is periodic.

85. The device of claim 83, wherein the voltage signal comprises a square-wave with a duty cycle of less than 100 percent.

86. The device of claim 83, wherein the voltage signal comprises a square-wave having a duty cycle of approximately 50 percent.

87. The device of claim 83, wherein said controlling means is configured to change said height of said space by changing said voltage.

88. The device of claim 83, wherein the voltage signal comprises a sinusoidal signal.

89. The device of claim 83, wherein the voltage signal comprises a stream of pulses.

90. The device of claim 89, wherein the pulses vary in width.

91. The device of claim 83, wherein said voltage across said first and second adjusting means causes modulation of light to produce at least one color.

92. The device of claim 91, wherein said voltage across said first and second adjusting means controls the intensity of the modulated light.

93. The device of claim 83, further comprising a plurality of means for adjusting dimensions of a plurality of spaces, each being separated by a respective space, wherein each of the plurality of adjusting means comprises at least a portion of a picture element.

94. The device of claim 83, wherein each of the plurality of adjusting means is controlled independently.

95. The device of claim 83, wherein the dimension of said space is substantially zero when the voltage applied across the first and second adjusting means exceeds a threshold voltage difference.

96. The device of claim 95, wherein the dimension of said space is different from zero when the voltage applied across the first and second adjusting means is below the threshold voltage difference.