Altering temporal response of microelectromechanical elements

• US 7,119,945 B2
• Filed: 03/03/2004
• Issued: 10/10/2006
• Est. Priority Date: 03/03/2004
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Cummings, William J., Kothari, Manish
• Primary Examiner(s): Lester, Evelyn A
• Application Number:
  US10/794,737
• Publication Number:
  US 20050195467A1
• Time in Patent Office: 951 Days
• Field of Search: 359/201, 359/202, 359/223, 359/224, 359/225, 359290-292, 359/298, 359/318, 359/846, 359849-851, 359/872
• US Class Current: 359/292
• 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 26/0833 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 7/1821 for rotating or oscillating mirrors
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

An array of movable elements is arranged on a substrate. Each element has a cavity and a movable member to move through the cavity. The pressure resistance of the elements varies, allowing actuation signals to be manipulated to activate elements with different pressure resistance at different levels of the actuation signal.

Claims

1. An array of elements on a substrate, each element comprising:

a cavity; and

a movable member configured to move through the cavity, wherein the movable member of a first element has a first resistance to motion in a first state and the movable member of a second element has a second resistance to motion in the first state, and wherein the first resistance is different from the second resistance such that the first element and the second element have different actuation times.

2. The array of claim 1, wherein the movable member comprises holes to allow gas to escape when the movable member moves.

3. The array of claim 2, wherein different elements in the array have different patterns of holes.

4. The array of claim 1, wherein the movable member comprises a flexible portion and a rigid portion such that when the movable member moves through the cavity, the flexible portion collapses to trap gas between the rigid portion and the substrate.

5. The array of claim 1, wherein the movable member comprises a movable mirror formed from a support layer.

6. The array of claim 1, wherein the movable member comprises a movable mirror suspended over the cavity by at least one support post.

7. The array of claim 6, wherein the support post comprises support rails.

8. The array of claim 7, wherein the support rails comprise holes to allow gas to escape.

9. The array of claim 1, wherein each element further comprises a support layer to block edges of the movable member thereby trapping gas between the movable member and the substrate.

10. The array of claim 1, wherein the first movable member is configured to have a mechanical stiffness that is different from the second movable member.

11. The array of claim 1, the array further comprising an x-y grid of modulator elements forming a pixel, wherein modulator elements at an outer edge of the pixel are arranged so as to actuate first, increasing the resistance to motion of the movable member of elements at the middle of the pixel.

12. The array of claim 11, wherein the modulator elements at the outer edge of the pixel have lower mechanical stiffness, thereby causing gas to trap under the elements at the middle of the pixel.

13. The array of claim 1, wherein each element is configured to operate as at least one of the following devices:

display elements, switches, tunable capacitors, and interferometric modulator elements.

14. The array of claim 1, each element further comprising at least one of a bump and a groove defining at least a portion of the cavity to facilitate gas flow.

15. The array of claim 1, wherein the first element is actuated before the second element when the same actuation signal is applied to both elements.

16. The array of claim 1, wherein each element is in the first state when no actuation signal is applied to the element.

17. The array of claim 16, wherein each element is in a second state when the element is actuated by an actuation signal.

18. A method of manufacturing an array of elements, the method comprising:

forming movable members displaced from a substrate over a cavity such that a movable member of a first element has a first resistance to motion in a first state and the movable member of a second element has a second resistance to motion in the first state, wherein the first resistance is different from the second resistance such that the first element and the second element have different actuation times.

19. The method of claim 18, wherein the first resistance is configured to be different from the second resistance by manufacturing the first element to have a lower mechanical resistance than the second element, thereby causing the first element to actuate in such a manner as to force gas into the cavity of the second element.

20. The method of claim 18, wherein forming movable members further comprises forming movable members with holes patterned in a surface of the movable member.

21. The method of claim 20, wherein the holes form a first pattern on at least one of the movable members, and the holes form a second pattern on others of the movable members.

22. The array of claim 18, wherein each element is in the first state when no actuation signal is applied to the element.

23. The array of claim 22, wherein each element is in a second state when the element is actuated by an actuation signal.

24. A method of operating an array of light modulator elements on a substrate arranged into subarrays as pixels, the method comprising:

providing an actuation signal at a first level, thereby causing a first set of elements in the pixel to actuate thereby trapping gas between other elements in the pixel and the substrate; and

providing an actuation signal at a second level, causing a second set of elements in the pixel to actuate according to a response time determined by the pressure resistance.

25. The method of claim 24, wherein causing a first set of elements to actuate further comprises causing elements on a first edge of the pixel to actuate.

26. The method of claim 24, wherein causing a first set of elements to actuate further comprises causing elements along a second edge to actuate simultaneously with the elements along a first edge.

27. The method of claim 24, wherein causing a first set of elements to actuate further comprises causing elements along a second edge to actuate after the elements along a first edge.

28. The method of claim 24, wherein the second set of elements alter the pressure resistance of the elements by holes patterned in their surfaces.

29. An array of interferometric modulators, each interferometric modulator comprising:

a first layer;

a second layer comprising a movable member, wherein the movable member further comprises holes to allow gas to escape when the movable member moves; and

a cavity defined by the first and second layers,

wherein the movable member is configured to move through the cavity in a direction substantially perpendicular to the first layer, and wherein the holes of a first interferometric modulator of the array have a first configuration and the holes of a second interferometric modulator of the array have a second configuration different from the first configuration.

30. The array of claim 29, wherein the movable member of a first interferometric modulator is configured to have a different resistance to motion from the movable member of a second interferometric modulator.

31. The array of claim 29, wherein one of the first and second layer is fully reflective and the other is partially reflective.

32. The array of claim 29, wherein the movable member is movable through a range of positions including an actuated position an unactuated position.

33. The array of claim 29, wherein each interferometric modulator reflects light of a first set of wavelengths when the movable member is unactuated, and reflects no light or light of a second set of wavelengths when the movable member is actuated.

34. The array of claim 29, wherein the first configuration comprises a first pattern and the second configuration comprises a second pattern different from the first pattern.

35. The array of claim 29, wherein the first configuration comprises a first size and the second configuration comprises a second size different from the first size.