System and method for charge control in a MEMS device

• US 8,014,059 B2
• Filed: 11/04/2005
• Issued: 09/06/2011
• 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): TRA, TUYEN Q
• Application Number:
  US11/267,939
• Publication Number:
  US 20070058095A1
• Time in Patent Office: 2,132 Days
• Field of Search: 359/290, 359/291, 359/292, 359/293, 359/295, 359/298, 359/247, 359/302, 359/337.22, 359/346, 359/370, 359/398, 359/498, 359/577, 372/20, 372/25, 372/26, 372/30, 372/32, 385/14, 385/16, 385/24
• US Class Current: 359/292
• 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 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

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. An electronic device for at least partially displaying a pixel of a displayable image comprising:

a first reflector and a second reflector defining an optical cavity therebetween selective of a visible wavelength at an intensity by optical interference; and

,

a charge-controlling mechanism to allow optical properties of the optical cavity to be varied by controlling an amount of charge stored on the first and the second reflectors such that at least one of the visible wavelength and the intensity are variably selectable in correspondence with the pixel of the displayable image.

2. The electronic device of claim 1, wherein the mechanism comprises a charge-sharing capacitor.

3. The electronic device of claim 2, wherein the mechanism further comprises a voltage source and a second capacitor in parallel with the first reflector and the second reflector, the mechanism switching between the voltage source and the charge-sharing capacitor, the second capacitor, the first reflector, and the second reflector.

4. The electronic device of claim 1, wherein the mechanism comprises a controlled current source and circuitry for controlling a time interval that the current source is applied to the first reflector and the second reflector.

5. The electronic device of claim 1, wherein the first reflector is a top, semi-reflective reflector, and the second reflector is a bottom, highly reflective reflector.

6. The electronic device of claim 1, wherein the mechanism allows a thickness of the optical cavity to be varied to variably select at least one of the visible wavelength and the intensity.

7. The electronic device of claim 1, wherein the mechanism comprises a flexure operatively coupled to one of the first and the second reflectors.

8. The electronic device of claim 7, wherein the flexure is a non-linear flexure that has non-linear spring functionality.

9. The electronic device of claim 1, wherein the optical cavity operates in accordance with a contact mode in which the first and the second reflectors come into contact with one another, and a non-contact mode in which the first and the second reflectors are separated from one another, such that a thickness of the optical cavity therebetween is controllable by the mechanism to select color.

10. The electronic device of claim 1, wherein the optical cavity has a sufficiently great thickness to produce an order of spectral response of a color corresponding to the visible wavelength that is greater than one.

11. The electronic device of claim 1, further comprising a third reflector between the first reflector and the second reflector such that the optical cavity encompasses a first gap between the first reflector and the third reflector and a second gap between the third reflector and the second reflector.

12. The electronic device of claim 1, wherein both the visible wavelength and the intensity are variably selectable in correspondence with the pixel of the displayable image.

13. The electronic device of claim 1, wherein the optical cavity is operates in accordance with multiple levels, each level corresponding to at least one of a different color and a different intensity of the different color.

14. The electronic device of claim 1, wherein the visible wavelength of which the optical cavity is selective is fixed as a color component wavelength, and the intensity of the color component wavelength is variably selectable in correspondence with a corresponding color component of the pixel of the displayable image.

15. The electronic device of claim 1, wherein the optical cavity is one of reflectively selective and transmissively selective.

46. The display device of claim 4, wherein each optical resonant cavity is operable in a contact mode in which the first and the second reflectors come into contact with one another, and a non-contact mode in which the first and the second reflectors are separated from one another.

16. An electronic device for at least partially displaying a pixel of a displayable image comprising:

a first reflector and a second reflector defining an optical cavity therebetween selective of a visible wavelength at an intensity by optical interference; and

,

means for controlling an amount of charge stored on the first and the second reflectors to vary optical properties of the optical cavity to variably select at least one of the visible wavelength and the intensity in correspondence with the pixel of the displayable image.

17. The electronic device of claim 16, wherein a thickness of the optical cavity is variable.

18. The electronic device of claim 16, further comprising a non-linear flexure having non-linear spring functionality.

19. The electronic device of claim 16, wherein the optical cavity is operable in a contact mode in which the first and the second reflectors come into contact with one another, and a non-contact mode in which the first and the second reflectors are separated from one another.

20. The electronic device of claim 16, wherein the optical cavity has a sufficiently great thickness to produce an order of spectral response of a color corresponding to the visible wavelength that is greater than one.

21. The electronic device of claim 16, further comprising a third reflector between the first reflector and the second reflector such that the optical cavity encompasses a first gap between the first reflector and the third reflector and a second gap between the third reflector and the second reflector.

22. The electronic device of claim 16, wherein the optical cavity is operable in accordance with multiple levels, each level corresponding to at least one of a different color and a different intensity of the different color.

23. A display device comprising:

a plurality of electrically adjustable optical resonant cavities to correspondingly display a plurality of pixels of a displayable image by optical interference such that the plurality of cavities are divided into a plurality of cavity groups, each cavity group variably selecting a visible wavelength at an intensity corresponding to a color and an intensity of a corresponding pixel of the displayable image; and

at least one charge-controlling mechanism to allow optical properties of the optical resonant cavities to be varied by controlling an amount of charge stored over the cavities.

24. The display device of claim 23, wherein each cavity group comprises a sub-plurality of the plurality of cavities, each cavity of the sub-plurality of each cavity group selecting a different static color wavelength at a variably intensity corresponding to a different color component of a pixel of the displayable image to which the cavity group corresponds.

25. The display device of claim 23, wherein each of at least one of the plurality of cavities operates in three different states.

26. The display device of claim 23, wherein the plurality of cavities are each of one of a plurality of types, each of the plurality of types having three different operable states.

27. The display device of claim 23, wherein each cavity group comprises a red wavelength-selecting cavity selecting a red intensity corresponding to a red color component of a pixel of the displayable image to which the cavity group corresponds, a green wavelength-selecting cavity selecting a green intensity corresponding to a green color component of a pixel of the displayable image to which the cavity group corresponds, and a blue wavelength-selecting cavity selecting a blue intensity corresponding to a blue color component of a pixel of the displayable image to which the cavity group corresponds.

28. The display device of claim 23, further comprising, for each optical resonant cavity, a first reflector and a second reflector defining the optical resonant cavity therebetween, and a flexure operatively coupled to one of the first and the second reflectors.

29. The display device of claim 28, wherein the flexure has a non-linear spring functionality.

30. The display device of claim 28, wherein each optical resonant cavity is operable in a contact mode in which the first and the second reflectors come into contact with one another, and a non-contact mode in which the first and the second reflectors are separated from one another.

31. The display device of claim 28, wherein each optical resonant cavity has a sufficiently great thickness to produce an order of spectral response greater than one.

32. The display device of claim 28, further comprising, for each optical resonant cavity, a third reflector between the first and the second reflectors, such that each optical resonant cavity encompasses a first gap between the first and the third reflectors and a second gap between the third and the second reflectors.

33. An electronic device for at least partially displaying a pixel of a displayable image comprising:

a first reflector, a second reflector, and a third reflector in between the first and the second reflectors defining an optical cavity inclusive of a first gap between the first reflector and the third reflector, and a second gap between the second reflector and the third reflector, the optical cavity selective of a visible wavelength at an intensity by optical interference; and

,

a mechanism to allow optical properties of the optical cavity to be varied by controlling an amount of charge stored over the cavity such that at least one of the visible wavelength and the intensity are variably selectable in correspondence with the pixel of the displayable image.

34. The electronic device of claim 33, wherein both the visible wavelength and the intensity are variably selectable in correspondence with the pixel of the displayable image.

35. The electronic device of claim 33, wherein the optical cavity operates in accordance with multiple levels, each level corresponding to at least one of a different color and a different intensity of the different color.

36. The electronic device of claim 33, wherein the visible wavelength of which the optical cavity is selective is fixed as a color component wavelength, and the intensity of the color component wavelength is variably selectable in correspondence with a corresponding color component of the pixel of the displayable image.

37. The electronic device of claim 33, wherein the optical cavity is one of reflectively selective and transmissively selective.

38. A display device comprising:

a plurality of electrically adjustable optical resonant cavities to correspondingly display a plurality of pixels of a displayable image by optical interference,

wherein the plurality of cavities are divided into a plurality of cavity groups, each cavity group variably selecting a visible wavelength at an intensity corresponding to a color and an intensity of a corresponding pixel of the displayable image.

39. The display device of claim 38, wherein each cavity group comprises a sub-plurality of the plurality of cavities, each cavity of the sub-plurality of each cavity group selecting a different static color wavelength at a variably intensity corresponding to a different color component of a pixel of the displayable image to which the cavity group corresponds.

40. The display device of claim 38, wherein each of at least one of the plurality of cavities operates in three different states.

41. The display device of claim 38, wherein the plurality of cavities are each of one of a plurality of types, each of the plurality of types having three different operable states.

42. The display device of claim 38, wherein each cavity group comprises a red wavelength-selecting cavity selecting a red intensity corresponding to a red color component of a pixel of the displayable image to which the cavity group corresponds, a green wavelength-selecting cavity selecting a red intensity corresponding to a green color component of a pixel of the displayable image to which the cavity group corresponds, and a blue wavelength-selecting cavity selecting a red intensity corresponding to a blue color component of a pixel of the displayable image to which the cavity group corresponds.

43. The display device of claim 38, further comprising at least one charge-controlling mechanism to allow optical properties of the optical resonant cavities to be varied by controlling an amount of charge stored over the cavities.

44. The display device of claim 38, further comprising, for each optical resonant cavity, a first reflector and a second reflector defining the optical resonant cavity therebetween, and a flexure operatively coupled to one of the first and the second reflectors.

45. The display device of claim 44, wherein the flexure has a non-linear spring functionality.

47. The display device of claim 44, wherein each optical resonant cavity has a sufficiently great thickness to produce an order of spectral response greater than one.

48. The display device of claim 44, further comprising, for each optical resonant cavity, a third reflector between the first and the second reflectors, such that each optical resonant cavity encompasses a first gap between the first and the third reflectors and a second gap between the third and the second reflectors.

49. An electronic device for at least partially displaying a pixel of a displayable image comprising:

a first reflector, a second reflector, and a third reflector in-between the first and the second reflectors defining an optical cavity inclusive of a first gap between the first reflector and the third reflector, and a second gap between the second reflector and the third reflector, the optical cavity selective of a visible wavelength at an intensity by optical interference; and

,

a mechanism to allow optical properties of the optical cavity to be varied, such that at least one of the visible wavelength and the intensity are variably selectable in correspondence with the pixel of the displayable image.

50. The electronic device of claim 49, wherein both the visible wavelength and the intensity are variably selectable in correspondence with the pixel of the displayable image.

51. The electronic device of claim 49, wherein the optical cavity operates in accordance with multiple levels, each level corresponding to at least one of a different color and a different intensity of the different color.

52. The electronic device of claim 49, wherein the visible wavelength of which the optical cavity is selective is fixed as a color component wavelength, and the intensity of the color component wavelength is variably selectable in correspondence with a corresponding color component of the pixel of the displayable image.

53. The electronic device of claim 49, wherein the optical cavity is one of reflectively selective and transmissively selective.