Method and device for modulating light

• US 7,839,556 B2
• Filed: 08/20/2007
• Issued: 11/23/2010
• Est. Priority Date: 05/05/1994
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Miles, Mark W.
• Primary Examiner(s): Sugarman; Scott J
• Assistant Examiner(s): Thomas; Brandi N
• Application Number:
  US11/841,726
• Publication Number:
  US 20080036795A1
• Time in Patent Office: 1,191 Days
• Field of Search: 359290-292, 359/298
• 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 1/213 Fabry-Perot type
• 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: G02F 2203/09 transflective
• 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 2300/06 : Passive matrix structure, i.e. with direct application of both column and row voltages to the light emitting or modulating elements, other than LCD or OLED
• CPC Class Codes: G09G 2360/142 : the light being detected by light detection means within each pixel
• 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 3/22 : using controlled light sources
• CPC Class Codes: G09G 3/34 : by control of light from an independent source
• 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. A device for modulating light comprising:

a light modulating element having a first wall and a second wall defining a cavity, wherein at least one of the walls is movable relative to the other; and

a circuit configured to periodically apply a plurality of pulses having varying widths across the first and second layers, the plurality of pulses being configured to control the relative movement of the first and second walls.

2. The device of claim 1, wherein at least one of the pulses has a duty cycle of less than 100 percent.

3. The device of claim 1, wherein at least one of the pulses has a duty cycle of less than 50 percent.

4. The device of claim 1, wherein the intensity of modulated light is controlled at least in part by duty cycle.

5. The device of claim 4, wherein the light modulating element is a pixel in a display.

6. The device of claim 5, wherein the pixel is activated by one of the plurality of pulses.

7. The device of claim 6, wherein the pixel remains activated for a remainder of the period.

8. A device for modulating light comprising:

first and second layers separated by a space, wherein a dimension of the space is changeable from a first value to a second value in response to a voltage applied across the first and second layers, and wherein the first and second layers are substantially parallel when the dimension of the space is the first and second value; and

a control circuit configured to apply a continuous voltage across the first and second lays to maintain the dimension of the space at a prescribed height.

9. A device for modulating light, comprising:

first and second substantially non-absorptive layers separated by a space, wherein a dimension of the space is changeable in response to a voltage applied across the first and second layers; and

a control circuit configured to apply a continuous voltage across the first and second layers to maintain the dimension of the space at a prescribed height.