MEMS switch with set and latch electrodes

• US 7,446,927 B2
• Filed: 09/23/2005
• Issued: 11/04/2008
• 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): Lester; Evelyn A.
• Application Number:
  US11/234,826
• Publication Number:
  US 20060066937A1
• Time in Patent Office: 1,138 Days
• Field of Search: 359/223, 359/224, 359290-292, 359/295, 359/298
• US Class Current: 359/290
• 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 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G09G 3/3466 based on interferometric effect
• CPC Class Codes: H04N 5/7458 the modulator being an array of deformable mirrors, e.g. digital micromirror device [DMD]
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

A MEMS device is electrically actuated with a voltage placed across a first electrode (702) and a moveable material (714). The device may be maintained in an actuated state by latch electrodes (730a, 730b) that are separate from the first electrode.

Claims

1. A MEMS switch device comprising:

a substrate;

at least two support posts supported by said substrate;

an electrostatically moveable electrode supported above said substrate by said support posts; and

at least two switch terminals that are selectably electrically connected or disconnected based at least in part on the position of the moveable electrode;

first and second latch electrodes, each located between said support posts adjacent one or more peripheral portions of the moveable electrode; and

a set electrode located adjacent a central portion of the moveable electrode,

wherein said moveable electrode is configured to actuate to an actuated position based on electrostatic attraction between said moveable electrode and said set electrodes and is configured to be maintained in substantially the actuated position based on electrostatic attraction between the moveable electrode and the first and second latch electrodes.

2. The MEMS device of claim 1, wherein the set electrode is in a central region between said at least two support posts.

3. The MEMS device of claim 2, wherein at least one of said latch electrodes is positioned between said central region and one of said support posts.

4. The MEMS device of claim 2, wherein at least one of the first and second latch electrodes is positioned between one of said switch terminals and one of said support posts.

5. The MEMS device of claim 1, wherein the set electrode is in a central region of said device, and the first and second latch electrodes are electrically isolated from the set electrode.

6. The MEMS device of claim 1, wherein said switch terminals are supported by said substrate.

7. The MEMS device of claim 4, wherein said switch terminals are connected when said moveable electrode is positioned proximate to said substrate.

8. A display system comprising:

an array of MEMS display elements;

one or more MEMS switches coupled to said array, wherein at least one of said MEMS switches comprises;

a substrate;

at least two support posts supported by said substrate;

an electrostatically moveable electrode supported above said substrate by said support posts; and

at least two switch terminals that are selectably connected or disconnected according to the position of the moveable electrode;

first and second latch electrodes, each located between said support posts adjacent one or more peripheral portions of the moveable electrode; and

a set electrode located adjacent a central portion of the moveable electrode, wherein said moveable electrode is configured to actuate to an actuated position in response to an electrostatic attraction between a central portion of said moveable electrode and said set electrode, and is configured to be maintained in substantially the actuated position based on electrostatic attraction between first and second peripheral portions of said moveable electrode and the first and second latch electrodes, respectively.

9. The display system of claim 8, additionally comprising a driver circuit coupled to said array.

10. The display system of claim 8, further comprising:

a processor that is in electrical communication with said display, said processor being configured to process image data; and

a memory device in electrical communication with said processor.

11. The device of claim 9, wherein said driver circuit is configured to send at least one signal to said display.

12. The device of claim 11, further comprising:

a controller configured to send at least a portion of said image data to said driver circuit.

13. The device of claim 10, further comprising:

an image source module configured to send said image data to said processor.

14. The device of claim 13, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

15. The device of claim 10, further comprising:

an input device configured to receive input data and to communicate said input data to said processor.

16. A method of operating a MEMS switch comprising:

electrically connecting or disconnecting first and second electrical components by moving an electrostatically moveable element from a first position to a second position by applying a first voltage across a set electrode and the moveable element, the first voltage establishing an electrostatic attraction between the set electrode and a central portion of the moveable element; and

maintaining said moveable element in said second position by applying a second voltage across the moveable element and first and second latch electrodes, the second voltage establishing an electrostatic attraction between each of the first and second latch electrodes and first and second peripheral portions of the moveable element, respectively.

17. The method of claim 16, wherein said second voltage is less than said first voltage.

18. A MEMS switch comprising:

a first electrode electrostatically moveable between first and second positions;

switch terminals selectably electrically connected or disconnected according to a position of said first electrode;

means for establishing an electrostatic force on a central portion of the moveable element so as to move said moveable electrode from said first position to said second position; and

means for establishing an electrostatic force on a peripheral portion of the moveable element so as to maintain said moveable electrode in said second position, said means for establishing the electrostatic force on the peripheral portion being separately controllable from said means for establishing the electrostatic force on the central portion.

19. The MEMS switch of claim 18, wherein said moving means for establishing the electrostatic force on the central portion comprises a first electrode.

20. The MEMS switch of claim 18 or 19, wherein said means for establishing the electrostatic force on the peripheral portion comprises a second electrode.

21. A method of making a MEMS switch comprising:

forming switch terminals between a pair of support posts on a substrate;

forming an electrostatically moveable electrode on said support posts; and

forming first and second latch electrodes between said support posts adjacent said moveable electrode; and

forming a set electrode between said first and second latch electrodes adjacent a central portion of said moveable membrane,

wherein said moveable electrode is configured to actuate to an actuated position based on electrostatic attraction between a central portion of said moveable electrode and said set electrode, and is configured to be maintained in substantially the actuated position based on electrostatic attraction between first and second peripheral portions of said moveable electrode and the first and second latch electrodes, respectively.

22. The method of claim 21, comprising forming said set electrode in a central region of said MEMS switch.

23. The method of claim 22, comprising forming at least one latch electrode between said central region and one of said support posts, said at least one latch electrode being electrically isolated from said set electrode.

24. A MEMS switch made with the method of claim 21.