Method and apparatus for providing brightness control in an interferometric modulator (IMOD) display

• US 8,004,743 B2
• Filed: 04/21/2006
• Issued: 08/23/2011
• Est. Priority Date: 04/21/2006
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Mignard, Marc
• Primary Examiner(s): MACK, RICKY LEVERN
• Application Number:
  US11/408,753
• Publication Number:
  US 20070247704A1
• Time in Patent Office: 1,950 Days
• Field of Search: 359/365, 359/295, 359/265
• US Class Current: 359/295
• 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: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 3/3466 based on interferometric effect
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

Methods and systems for providing brightness control in an interferometric modulator (IMOD) display are provided. In one embodiment, an interferometric modulator display pixel is provided that includes a microelectromechanical systems (MEMS) interferometric modulator having an associated first color spectrum, and a color absorber located substantially in front of the interferometric modulator display pixel, in which the color absorber has an associated second color spectrum. The microelectromechanical systems (MEMS) interferometric modulator is operable to shift the first color spectrum relative to the second color spectrum to control a visual brightness of the interferometric modulator display pixel independent of a color of the interferometric modulator display pixel.

Claims

1. An interferometric modulator display pixel comprising:

an electromechanical systems interferometric modulator having an associated first color spectrum indicating a reflectance of light at a first peak wavelength,

wherein the electromechanical systems interferometric modulator is operable to shift the first color spectrum relative to a second color spectrum to control a visual brightness of the interferometric modulator while said interferometric modulator appears substantially the same color, the second color spectrum indicating absorption of light except at a second peak wavelength that is different from the first peak wavelength, and

wherein the interferometric display pixel comprises a reflective display pixel.

2. The interferometric modular display pixel of claim 1, further comprising a color absorber, the second color spectrum being the color spectrum of the color absorber.

3. The interferometric modulator display pixel of claim 1, wherein the visual brightness of the interferometric modulator display pixel increases with greater overlap between the first color spectrum and the second color spectrum, and decreases with less overlap between the first color spectrum and the second color spectrum.

4. The interferometric modulator display pixel of claim 1, further comprising a light source.

5. The interferometric modulator display pixel of claim 1, wherein

the interferometric modulator display pixel comprises a plurality of color space regions, each color space region having a corresponding color spectrum associated therewith;

and

the interferometric modulator display pixel further comprises a color absorber located substantially in front of each color space region, each color absorber having an associated color spectrum,

wherein the electromechanical systems interferometric modulator is operable to shift the color spectrum of each color space region relative to a color spectrum of a corresponding color absorber to control a visual brightness of a color associated with each color space region.

6. The interferometric modulator display pixel of claim 5, wherein the plurality of color space regions comprises one or more of a red color space region, a green color space region, or a blue color space region.

7. The interferometric modulator display pixel of claim 2, wherein one or more light sources provides light at the second color spectrum associated with the color absorber.

8. The interferometric modulator display pixel of claim 7, wherein the one or more light sources comprise a narrow spectrum light source or a broad spectrum light source.

9. The interferometric modulator display pixel of claim 8, wherein the narrow spectrum light source comprises a laser or a light-emitting diode (LED).

10. The interferometric modulator display pixel of claim 8, wherein the broad spectrum light source comprises a mercury lamp or a carbon arc lamp.

11. The interferometric modulator display pixel of claim 1, wherein the electromechanical systems interferometric modulator comprises:

a first electrode layer;

a second electrode layer;

a support structure which separates the first electrode layer from the second electrode layer; and

a reflective surface movable between a first position and a second position, wherein movement of the reflective surface between the first position and the second position shifts the first color spectrum relative to the second color spectrum.

12. The interferometric modulator display pixel of claim 11 wherein the reflective surface is on a reflective layer coupled to the second electrode layer.

13. The interferometric modulator display pixel of claim 11 wherein the reflective surface is on the second electrode layer.

14. A display comprising the interferometric modulator display pixel of claim 1.

15. The display of claim 14, further comprising:

a processor that is in electrical communication with the interferometric modulator display pixel, the processor being configured to process image data; and

a memory device in electrical communication with the processor.

16. The display of claim 15, further comprising:

a first controller configured to send at least one signal to the interferometric modulator display pixel; and

a second controller configured to send at least a portion of the image data to the first controller.

17. The display of claim 15, further comprising an image source module configured to send the image data to the processor.

18. The display of claim 17, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

19. The display of claim 15, further comprising an input device configured to receive input data and to communicate the input data to the processor.

39. The display of claim 14, wherein the display is configured as a reflective display.

40. The interferometric modulator display pixel of claim 1, further comprising a controller configured to provide multiple levels of brightness control for the color output of the interferometric modulator by controlling the shift of the first color spectrum relative to the second color spectrum.

43. The display of claim 39, wherein the reflective display is configured to produce an image by modulation of incident ambient light.

20. An interferometric modulator display pixel comprising:

means for interferometrically modulating light, said modulating means having an associated first color spectrum indicating a reflectance of light at a first peak wavelength; and

a means for absorbing light and thereby producing a color, the light absorbing means having an associated second color spectrum indicating absorption of light except at a second peak wavelength that is different from the first peak wavelength,

wherein the modulating means is operable to shift the first color spectrum relative to the second color spectrum to control a visual brightness of the modulating means independent of the color of the modulating means, and

wherein the interferometric display pixel is configured as a reflective display pixel.

26. The interferometric modulator of claim 20, wherein the visual brightness of the interferometric modulator increases with greater overlap between the first color spectrum and the second color spectrum, and decreases with less overlap between the first color spectrum and the second color spectrum.

27. The interferometric modulator of claim 20, further comprising one or more light sources.

28. The interferometric modulator of claim 20, wherein

the interferometric modulator comprises a plurality of color space regions, each color space region having a corresponding color spectrum associated therewith;

and

the interferometric modulator further comprises a color absorber located substantially in front of each color space region, each color absorber having an associated color spectrum,

wherein the modulating means is operable to shift the color spectrum of each color space region relative to a color spectrum of a corresponding color absorber to control a visual brightness of a color associated with each color space region.

29. The interferometric modulator of claim 28, wherein the plurality of color space regions comprises one or more of a red color space region, a green color space region, or a blue color space region.

30. The interferometric modulator display pixel of claim 20, further comprising one or more light sources that provides illumination at the second peak wavelength associated with the light absorbing means.

31. The interferometric modulator of claim 20, wherein the modulating means comprises a micro electromechanical system.

32. The interferometric modulator of claim 20, wherein the modulating means comprises:

a first electrode layer;

a second electrode layer;

a support that separates the first electrode layer from the second electrode layer; and

a reflective surface movable between a first position and a second position, wherein movement of the reflective surface between the first position and the second position shifts the first color spectrum relative to the second color spectrum.

45. A reflective display comprising the interferometric modulator display pixel of claim 20.

46. The display of claim 45, wherein the reflective display is configured to produce an image by modulation of incident ambient light.

21. A method of manufacturing an interferometric modulator, the method comprising:

providing a substrate;

forming an optical stack on the substrate;

forming a moveable reflective layer over the optical stack, said moveable reflective layer and said optical stack together having an associated first color spectrum indicating a reflectance of light at a first peak wavelength; and

providing a color absorber, the color absorber absorbing light except light within a second range of wavelengths that is different from the first-peak wavelength,

wherein said moveable reflector layer is operable to shift the first color spectrum relative to the second color spectrum to control visual brightness of the interferometric modulator such that said interferometric modulator provides multiple levels of brightness of a color, and

wherein the interferometric modulator display is included in a reflective display pixel.

22. The method of claim 21, wherein the color absorber is formed on a surface of the substrate opposite of the optical stack.

23. The method of claim 21, wherein the color absorber is formed on a surface of the substrate on a same side as the optical stack.

24. The method of claim 21, wherein forming an optical stack on the substrate and forming a moveable reflective layer over the optical stack comprises:

forming a first conductive layer on the substrate;

depositing an oxide layer over the first conductive layer;

depositing a sacrificial layer over the oxide layer;

forming a plurality of first support posts to support a second conductive layer;

forming the second conductive layer over the sacrificial layer and the plurality of first support posts; and

etching away the sacrificial layer.

25. An interferometric modulator manufactured in accordance with the method of claim 21.

47. A reflective display comprising the interferometric modulator of claim 25.

48. The display of claim 47, wherein the reflective display is configured to produce an image by modulation of incident ambient light.

33. An interferometric modulator display pixel comprising:

an electromechanical system interferometric modulator having an associated first color spectrum corresponding to reflectance of light, said first color spectrum having a first peak wavelength; and

a color absorber, the color absorber having an associated second color spectrum corresponding to absorption of light, said second color spectrum comprising a second peak transmission wavelength having reduced absorption that is different from the first peak wavelength,

wherein the electromechanical systems interferometric modulator is operable to shift the first color spectrum relative to the second color spectrum to control a visual brightness of the interferometric modulator such that said interferometric modulator is configured to provide multiple levels of brightness of color light, and

wherein the interferometric display pixel comprises a reflective display pixel.

34. The interferometric modulator display pixel of claim 33, wherein the visual brightness of the interferometric modulator display pixel increases with greater overlap between the first color spectrum and the second color spectrum, and decreases with less overlap between the first color spectrum and the second color spectrum.

35. The interferometric modulator display pixel of claim 33, wherein

the interferometric modulator display pixel comprises a plurality of color space regions, each color space region having a corresponding color spectrum associated therewith;

and

the interferometric modulator display pixel further comprises a color absorber located substantially in front of each color space region, each color absorber having an associated color spectrum,

wherein the electromechanical system interferometric modulator is operable to shift the color spectrum of each color space region relative to a color spectrum of a corresponding color absorber to control a visual brightness of a color associated with each color space region.

36. The interferometric modulator display pixel of claim 35, wherein the plurality of color space regions comprises one or more of a red color space region, a green color space region, or a blue color space region.

37. The interferometric modulator display pixel of claim 33, wherein one or more light sources provides light at the second peak transmission wavelength associated with the color absorber.

38. The interferometric modulator display pixel of claim 33, wherein the electromechanical system interferometric modulator comprises:

a first electrode layer;

a second electrode layer;

a support structure which separates the first electrode layer from the second electrode layer; and

a reflective surface movable between a first position and a second position, wherein movement of the reflective surface between the first position and the second position shifts the first color spectrum relative to the second color spectrum.

41. The interferometric modulator display pixel of claim 33, further comprising a controller configured to provide said multiple levels of brightness for the color light output by the interferometric modulator by controlling the shift of the first color spectrum relative to the second color spectrum.

42. A reflective display comprising the interferometric display pixel of claim 33.

44. The display of claim 42, wherein the reflective display is configured to produce an image by modulation of incident ambient light.

49. A display pixel comprising:

a reflective electro-mechanical device comprising;

a substrate;

an optical stack disposed on a first side of the substrate, said optical stack comprising a first partially reflective layer; and

a second reflective layer disposed on said first side of the substrate, the reflective electro-mechanical device having an associated first color spectrum indicating a reflectance of light at a first peak wavelength; and

a color filter having an associated second color spectrum, said second color spectrum comprising a second peak transmission wavelength that is different from the first peak wavelength,

wherein ambient light incident from a second side of the substrate is interferometrically modulated by the reflective electro-mechanical device and is viewable from said second side of the substrate, and

wherein the reflective electro-mechanical device is operable to shift the first color spectrum relative to the second color spectrum to provide multiple levels of visual brightness of color light.

50. The display pixel of claim 49, wherein the visual brightness of the reflective electro-mechanical device increases with greater overlap between the first color spectrum and the second color spectrum, and decreases with less overlap between the first color spectrum and the second color spectrum.

51. The display pixel of claim 49, further comprising a light source.

52. The display pixel of claim 51, wherein one or more light sources provides light at the second color spectrum associated with the color filter.

53. The display pixel of claim 52, wherein the one or more light sources comprise a narrow spectrum light source or a broad spectrum light source.

54. The display pixel of claim 53, wherein the narrow spectrum light source comprises a laser or a light-emitting diode (LED).

55. The display pixel of claim 53, wherein the broad spectrum light source comprises a mercury lamp or a carbon arc lamp.

56. The display pixel of claim 49, wherein the second reflective layer is movable between a first position and a second position, wherein movement of the second reflective layer between the first position and the second position shifts the first color spectrum relative to the second color spectrum.

57. A display comprising the display pixel of claim 49.

58. The display of claim 57, wherein the display comprises a reflective display.

59. The display pixel of claim 49, further comprising a controller configured to provide multiple levels of brightness control for the color output of the reflective electro- mechanical device by controlling the shift of the first color spectrum relative to the second color spectrum.

60. The display pixel of claim 49, wherein the reflective electro-mechanical device is configured to produce an image by modulation of incident ambient light.

61. The display pixel of claim 60, further comprising a controller configured to control said reflective electro-mechanical device to provide multiple levels of visual brightness for the color light output by the reflective electro-mechanical device by controlling the shift of the first color spectrum relative to the second color spectrum so as to produce said image by modulation of incident ambient light.