MEMS device having a layer movable at asymmetric rates

• US 7,550,810 B2
• Filed: 02/23/2006
• Issued: 06/23/2009
• Est. Priority Date: 02/23/2006
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Mignard, Marc, Kogut, Lior
• Primary Examiner(s): Wilson; Allan R.
• Application Number:
  US11/360,162
• Publication Number:
  US 20070194630A1
• Time in Patent Office: 1,216 Days
• Field of Search: 257/415, 257/417, 257/419, 345/85, 359/239
• US Class Current: 257/419
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81B 2201/054 Microvalves
• CPC Class Codes: B81B 2203/053 Translation according to an axis perpendicular to the substrate
• CPC Class Codes: B81B 3/0078 Constitution or structural means for improving mechanical properties not provided for in B81B3/007 - B81B3/0075
• 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 2300/06 Passive matrix structure, i.e. with direct application of both column and row voltages to the light emitting or modulating elements, other than LCD or OLED
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

A microelectromechanical (MEMS) device includes a substrate and a movable layer mechanically coupled to the substrate. The movable layer moves from a first position to a second position at a first rate and from the second position to the first position at a second rate faster than the first rate. The MEMS device further includes an adjustable cavity defined between the substrate and the movable layer and containing a fluid. The MEMS device further includes a fluid conductive element through which the fluid flows at a first flowrate from inside the cavity to outside the cavity upon movement of the movable layer from the second position to the first position and through which the fluid flows at a second flowrate slower than the first flowrate from outside the cavity to inside the cavity upon movement of the movable layer from the first position to the second position.

Claims

1. A microelectromechanical (MEMS) device comprising:

a substrate;

a movable layer mechanically coupled to the substrate, the movable layer movable between a first position and a second position, wherein the movable layer is configured to move from the first position to the second position at a first rate and wherein the movable layer is configured to move from the second position to the first position at a second rate that is faster than the first rate;

a cavity defined between the substrate and the movable layer, the cavity containing a fluid; and

a fluid conductive element through which the fluid is configured to flow at a first flowrate from inside the cavity to outside the cavity upon movement of the movable layer from the second position to the first position and through which the fluid is configured to flow at a second flowrate from outside the cavity to inside the cavity upon movement of the movable layer from the first position to the second position, the second flowrate slower than the first flowrate, wherein the fluid conductive element comprises at least one aperture through the movable layer, wherein the fluid conductive element further comprises at least one stopple that at least partially restricts fluid flow through the aperture.

2. The MEMS device of claim 1, wherein the second rate is about 100 times faster than the first rate.

3. The MEMS device of claim 1, wherein the second position is further from the substrate than is the first position.

4. The MEMS device of claim 1, wherein the MEMS device is substantially reflective to incident light when the movable layer is in the first position and wherein the MEMS device is substantially non-reflective to incident light when the movable layer is in the second position.

5. The MEMS device of claim 1, further comprising a partially reflective layer between the substrate and the movable layer.

6. The MEMS device of claim 1, wherein the fluid comprises air.

7. The MEMS device of claim 1, wherein the fluid comprises water.

8. The MEMS device of claim 1, wherein the at least one aperture comprises a first opening area on a surface of the movable layer facing towards the substrate and a second opening area on a surface of the movable layer facing away from the substrate, the second opening area smaller than the first opening area.

9. The MEMS device of claim 1, wherein the at least one stopple comprises a flap at least partially covering the aperture.

10. The MEMS device of claim 1, wherein the at least one stopple comprises flexible material.

11. The MEMS device of claim 1, further comprising at least one plug on the substrate, wherein the plug restricts fluid flow through the at least one aperture when the movable layer is in the first position, wherein the first position is closer to the substrate than is the second position.

12. The MEMS device of claim 11, wherein the plug and the substrate comprise the same material.

13. The MEMS device of claim 11, wherein the plug is coupled to the at least one aperture when the movable layer is in the first position.

14. The MEMS device of claim 1, further comprising a support structure between the movable layer and the substrate.

15. The MEMS device of claim 14, wherein the support structure includes at least one wall surrounding the cavity, the at least one wall configured to inhibit fluid flow between inside the cavity and outside the cavity.

16. The MEMS device of claim 14, wherein the fluid conductive element comprises at least one aperture through the support structure.

17. The MEMS device of claim 16, wherein the at least one aperture through the support structure comprises a first opening area on a surface of the support structure layer facing towards the cavity and a second opening area on a surface of the support structure facing away from the cavity, the second opening area smaller than the first opening area.

18. The MEMS device of claim 16, wherein the fluid conductive element comprises at least one stopple of the at least one aperture that at least partially restricts fluid flow through the at least one aperture through the support structure.

19. The MEMS device of claim 18, wherein the at least one stopple of the at least one aperture comprises a flap at least partially covering the at least one aperture through the support structure.

20. The MEMS device of claim 18, wherein the at least one stopple comprises flexible material.

21. The MEMS device of claim 14, wherein the fluid conductive element comprises at least one plug on the support structure corresponding to the at least one aperture through the movable layer, wherein the plug restricts fluid flow through the at least one aperture when the movable layer is in the first position, wherein the first position is closer to the substrate than is the second position.

22. The MEMS device of claim 21, wherein the plug and the support structure comprise the same material.

23. The MEMS device of claim 14, wherein the fluid conductive element comprises at least one aperture through the support structure and at least one corresponding plug on the movable layer, wherein the plug restricts fluid flow through the at least one aperture through the support structure when the movable layer is in the first position, wherein the first position is closer to the substrate than is the second position.

24. The MEMS device of claim 1, further comprising:

a display;

a processor in electrical communication with the display, the processor configured to process image data; and

a memory device in electrical communication with the processor.

25. The MEMS device of claim 24, further comprising a driver circuit configured to send at least one signal to the display.

26. The MEMS device of claim 25, wherein the driver circuit is compatible with a super twisted nematic (STN) display.

27. The MEMS device of claim 25, wherein the driver circuit is configured to refresh the display at a frequency greater than about once per 30 milliseconds.

28. The MEMS device of claim 1, wherein the device has a first reflectivity when the movable layer is in the first position and a second reflectivity when the movable layer is in the second position, the first reflectivity different than the second reflectivity.

29. The MEMS device of claim 1, wherein the device comprises a spatial light modulator.

30. The MEMS device of claim 1, wherein the device comprises an optical modulator.