System and method for multi-level brightness in interferometric modulation

• US 7,302,157 B2
• Filed: 04/01/2005
• Issued: 11/27/2007
• Est. Priority Date: 09/27/2004
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Chui, Clarence
• Primary Examiner(s): HAHM, SARAH UH YOUNG
• Application Number:
  US11/096,545
• Publication Number:
  US 20060067643A1
• Time in Patent Office: 970 Days
• Field of Search: 385/39, 385/40, 385/147, 385/901, 359/247, 359/254
• US Class Current: 385/147
• 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 2300/0439 Pixel structures
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/207 by domain size control G09G3/3637 takes precedence
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/3466 based on interferometric effect
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

A display having a plurality of reflective display elements. In one embodiment, the display elements comprise at least one electrode having a plurality of active areas. In one embodiment, at least two of the sizes of the active areas are different with respect to each other, e.g., they are non-uniform in size. The interferometric modulators have a plurality of states, wherein selected ones of the interferometric modulators are configured to be actuated depending differing electrostatic forces in the interferometric modulators. The electrostatic forces in the interferometric modulators are different at least in part due to variations in the sizes of the active areas of the electrodes.

Claims

1. A display device, comprising:

at least one array of interferometric modulators, selected interferometric modulators comprising at least one electrode having a plurality of active areas of different sizes, the selected interferometric modulators actuating depending upon varying electrostatic forces in the interferometric modulators, the electrostatic forces in the interferometric modulators varying at least in part due to variations in the sizes of the active areas of electrodes in the selected interferometric modulators, wherein each of the interferometric modulators comprises a cavity and light is interferometrically modulated by the cavity and the electrodes.

2. The display device of claim 1, wherein at least one of the electrodes having the plurality of active areas of different sizes have a substantially staircase shape from a viewing perspective of the display element.

3. The display device of claim 1, wherein at least one of the electrodes having the plurality of active areas of different sizes have a pyramidal shape from a viewing perspective of the display element.

4. The display device of claim 1, additionally comprising a latch electrode for modifying an activation voltage threshold of at least one of the interferometric modulators.

5. The display device of claim 4, wherein the latch electrode is placed proximate to an end of an active area of the interferometric modulators.

6. The display element of claim 1, further comprising a latch electrode configured to substantially equalize a deactivation voltage of two or more of the interferometric modulators.

7. A display comprising:

a plurality of reflective display elements, each of the display elements having;

a first electrode;

a second electrode having a substantially non-uniform width, wherein the second electrode spans at least two display elements; and

a cavity between the first electrode and the second electrode, wherein light is interferometrically modulated by the cavity and the first and second electrodes.

8. The display of claim 7, wherein the first electrode is perpendicular to the second electrode.

9. The display element of claim 7, wherein the display element has a first optical property when the second electrode is in a non-activated state with respect to the first electrode, and wherein the display element has a second optical property when the second electrode is in an activated state with respect to the first electrode.

10. The display of claim 7, wherein the second electrode has a substantially staircase shape from a viewing perspective of the display.

11. The display of claim 7, wherein the second electrode has a pyramidal shape from a viewing perspective of the display.

12. The display of claim 7, additionally comprising a latch electrode for modifying an activation voltage threshold of at least one of the reflective display elements.

13. The display of claim 12, wherein the latch electrode is placed proximate to an end of an active area of the reflective display elements.

14. The display of claim 7, further comprising a latch electrode configured to substantially equalize a deactivation voltage of two or more of the reflective display elements.

15. A method comprising:

providing a voltage to an electrode having a substantially non-uniform width;

in response to the provided voltage, activating selected ones of a plurality of reflective display elements, the reflective display elements including an interferometric modulator comprising a second electrode and a cavity between the non-uniform width electrode and the second electrode; and

interferometrically modulating light by the cavities and the first and second electrodes.

16. The method of claim 15, additionally comprising providing a latch voltage so to modify an activation voltage threshold of at least one of the reflective display elements.

17. The method of claim 16, wherein providing the latch voltage comprises providing the latch voltage to a latch electrode located proximate to an active area of the second electrode, and further wherein activating selected ones of the plurality of reflective display elements comprises activating two or more of the reflective display elements in response to different voltage levels, and deactivating two or more of the reflective display elements in response to substantially the same voltage level.

18. The method of claim 16, wherein the voltage provided to the substantially non-uniform width electrode is at a first level, the method further comprising:

providing a second voltage level to the second electrode of two or more of the reflective display elements, wherein activating the selected ones of a plurality of reflective display elements comprises activating two or more reflective display elements in response to different second voltage levels and deactivating two or more of the reflective display elements in response to substantially the same second voltage level.

19. The method of claim 18, wherein providing the second voltage comprises providing the second voltage level within a range wherein the two or more reflective display elements each maintain the activated or deactivated state.

20. The method of claim 15, wherein the electrode has a substantially staircase shape from a viewing perspective of the display.

21. The method of claim 15, wherein the electrode has a pyramidal shape from a viewing perspective of the display.

22. A reflective display element comprising:

a first electrode having a non-uniform width; and

a second electrode, wherein selected portions of the first electrode are configured to be activated in response to varying a difference in the voltage between the first electrode and the second electrode, the first and second electrode included within an interferometric modulator and forming a cavity therebetween, wherein light is interferometrically modulated by the cavity and the first and second electrodes.

23. The reflective display element of claim 22, wherein the first electrode is positioned substantially perpendicular to the second electrode.

24. The display element of claim 22, additionally comprising a latch electrode for modifying an activation voltage threshold of at least one of the reflective display elements.

25. A method comprising:

varying a difference in voltage between a first electrode and a second electrode, wherein the first electrode has a non-uniform shape, and wherein the varied voltage results in a change in an optical characteristic of an interferometric modulator;

in response to the varied voltage, selectively activating or deactivating fractional portions of the second electrode; and

interferometrically modulating light by a cavity of the interferometric modulator and the first and second electrodes, the cavity of the interferometric modulator being between the first and second electrodes.

26. The method of claim 25, additionally comprising providing a latch voltage to maintain the actuated portion of the second electrode in an actuated state.