Interferometric modulation

• US 6,055,090 A
• Filed: 01/27/1999
• Issued: 04/25/2000
• Est. Priority Date: 05/05/1994
• Status: Expired due to Term

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Etalon, Inc.
• Inventors: Miles, Mark W.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Lester, Evelyn A.
• Application Number:
  US09/238,340
• Time in Patent Office: 454 Days
• Field of Search: 359/290, 359/291, 359/584, 359/579, 359/578, 359/589, 345/84, 345/85
• US Class Current: 359/291
• 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 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

Abstract

An interferometric modulator (Imod) cavity has a reflector and an induced absorber. A direct view reflective flat panel display may include an array of the modulators. Adjacent spacers of different thicknesses are fabricated on a substrate by a lift-off technique used to pattern the spacers which are deposited separately, each deposition providing a different thickness of spacer. Or a patterned photoresist may be used to allow for an etching process to selectively etch back the thickness of a spacer which was deposited in a single deposition. A full-color static graphical image may be formed of combined patterns of interferometric modulator cavities. Each cavity includes a reflector, and an induced absorber, the induced absorber including a spacer having a thickness that defines a color associated with the cavity.

Claims

1. A direct view reflective flat panel display comprising an array of interferometric modulators, each of said modulators comprising

a reflector surface, and

a transmissive induced absorber that attenuates light incident upon it interposed between the reflective surface and a medium from which radiation is incident on the display, the induced absorber having radiation admittance characteristics that match the admittance of the reflector surface to the admittance of the incident medium.

2. The display of claim 1 wherein the array comprises a set of analog interferometric modulators arranged to be tuned to a specific reflective state.

3. The display of claim 1 wherein the array comprises sets of the interferometric modulators the respective sets being arranged to switch between different pairs of reflective states.

4. The display of claim 1 wherein the brightness of each of the modulators is controlled by pulse width modulation.

5. The display of claim 1 wherein the brightness of each of the modulators is controlled by spatial dithering.

6. The display of claim 1 wherein the brightness of each of the modulators is controlled by a combination of pulse width modulation and spatial dithering.

7. The display of claim 1 wherein the array is sealed by a backplane.

8. The display of claim 7 where the backplane comprises a monolithic element.

9. The display of claim 7 wherein the backplane is attached.

10. The display of claim 7 wherein the backplane supports electrodes which modify the electromechanical response of the pixels.

11. The display of claim 1 where each of the modulators is actuated by electrostatic forces.

12. The display of claim 1 wherein an optical compensation mechanism is used to mitigate or eliminate a shift in color with respect to viewing angle.

13. The display of claim 1 wherein an optical compensation mechanism is used to provide supplemental frontlighting.

14. The display of claim 1 wherein an optical compensation mechanism is used to mitigate or eliminate a shift in color with respect to viewing angle, and to provide supplemental frontlighting.

15. The display of claim 1 wherein the array is fabricated on the substrate along with electronic circuitry.

16. A full-color static graphical image comprising

an array of interferometric modulator cavities, each cavity including

a reflector, and

an induced absorber, the induced absorber including a spacer having a fixed thickness that defines a color associated with the cavity, the fixed thicknesses being different for respective ones of the cavities in accordance with the static graphical image.

17. The image of claim 16 in which the brightness of different cavities is determined by spatial dithering.

18. A full-color static graphical image comprising patterns of image elements, the elements of each of the patterns comprising interferometric cavities sharing a common fixed cavity thickness that defines a color associated with the pattern, the patterns together producing the image.

19. The image of claim 18 in which the brightness of the different patterns is determined by spatial dithering.

20. The image of claim 18 wherein the image elements are formed on a substrate.

21. The image of claim 18 wherein the color of one of the patterns is black.

22. The image of claim 18 wherein the color perceived by a viewer of the image varies with angle of viewing.