Controlling micro-electro-mechanical cavities

• US 20020149828A1
• Filed: 02/13/2002
• Published: 10/17/2002
• Est. Priority Date: 05/05/1994
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Iridigm Display Corporation (Qualcomm, Inc.)
• Inventors: Chui, Clarence, Miles, Mark W.
• Granted Patent: US 6,710,908 B2
• Time in Patent Office: Days
• US Class Current: 359/260
• 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 26/08 for controlling the direction of light in light guides G02B6/35
• 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 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 1/216 using liquid crystals, e.g. liquid crystal Fabry-Perot filters
• CPC Class Codes: G02F 2203/03 scattering

Abstract

Among other things, a cavity having a cavity dimension is configured so that the cavity dimension changes in response to electrostatic forces applied to the cavity, and at least two electrical structures are configured to apply electrostatic forces in the vicinity of the cavity, the electrical structures being independently controllable.

Claims

1. Apparatus comprising

a cavity having a cavity dimension, the cavity being configured so that the cavity dimension changes in response to electrostatic forces applied to the cavity, and

at least two electrical structures configured to apply electrostatic forces in the vicinity of the cavity, the electrical structures being independently controllable.

2. The apparatus of claim 1 in which the cavity dimension is determined by a distance between two walls, and the cavity dimension determines optical properties of the cavity.

3. The apparatus of claim 2 in which the optical properties include interference.

4. The apparatus of claim 2 in which the optical properties include reflectance.

5. The apparatus of claim 1 in which the two electrical structures comprise electrodes.

6. The apparatus of claim 1 in which the electrical structures lie on a wall of the cavity.

7. The apparatus of claim 6 in which the electrical structures lie side by side on the wall of the cavity.

8. The apparatus of claim 1 in which the cavity comprises an interference modulator and the cavity dimension determines an optical state of the modulator.

9. The apparatus of claim 1 in which changes in the cavity dimension that occur in response to the electrostatics forces are characterized by hysteresis.

10. The apparatus of claim 1 also including a second cavity adjacent to the cavity, the cavity and the second cavity sharing a common wall.

11. The apparatus of claim 1 also including stops within the cavity, the stops defining an intermediate cavity dimension between a minimum cavity dimension and a maximum cavity dimension.

12. The apparatus of claim 11 in which the stops define channels between them in which portions of a wall of the cavity lie in response to electrostatic forces.

13. The apparatus of claim 11 in which one of the electrical structures comprises electrodes embedded within the stops.

14. The apparatus of claim 11 in which the stops lie on a movable wall of the cavity.

15. The apparatus of claim 14 also including apertures in a second wall of the cavity configured to receive the stops.

16. The apparatus of claim 1 also including

additional cavities having cavity dimensions, each of the cavities being configured so that its cavity dimension changes in response to electrostatic forces applied to the cavity, and

additional electrical structures configured to apply electrostatic forces in the vicinities of the cavities, each of the additional cavities being associated with at least two of the additional electrical structures, the electrical structures with which each of the cavities is associated being independently controllable.

17. The apparatus of claim 16 in which at least some of the electrical structures associated with at least some of the respective cavities are coupled together.

18. The apparatus of claim 16 in which the cavities are organized in groups by coupling together of selected electrical structures.

19. The apparatus of claim 18 in which the coupling comprises bus conductors.

20. The apparatus of claim 18 in which the coupling comprises bus elements fabricated on multiple levels of the apparatus.

21. Apparatus comprising

an array of interferometric modulators, p1 actuation electrodes associated with the respective interferometric modulators, and

a pattern of conductors connecting the actuation electrodes in groups.

22. The apparatus of claim 21 in which the groups comprise rows or columns of the actuation electrodes.

23. The apparatus of claim 21 in which the groups comprise pixels of a display.

24. The apparatus of claim 21 in which each of the interferometric modulators is associated with more than one of the electrodes.

25. The apparatus of claim 24 in which the pattern of conductors connects different ones of the electrodes associated with each of the interferometric modulators in a configuration that enables them to be energized independently.

26. The apparatus of claim 21 in which the electrodes are arranged on walls of cavities of the interferometric modulators.

28. The method of claim 27 in which the one structure is energized to move an element of the cavity to a first position, and the other electrical structure is energized to maintain the element in the first position.

29. The method of claim 28 also including de-energizing the one structure while the other structure remains energized.

30. The method of claim 27 also including controlling the energizing of the one electrical structure and the other electrical structure to effect more than two optical states of the cavity.

31. The method of claim 27 also including energizing one electrical structure to apply an electrostatic force in the vicinity of each of multiple other cavities, and independently energizing another electrical structure to apply an electrostatic force in the vicinity of each of the multiple other cavities.

32. The method of claim 31 also including controlling the energizing of the electrical structures to independently control the optical states of groups of one or more of the cavities.

27. A method comprising

energizing one electrical structure to apply an electrostatic force in the vicinity of a cavity,

independently energizing another electrical structure to apply an electrostatic force in the vicinity of a cavity.