Micro electro mechanical system using comb and parallel plate actuation

• US 7,863,799 B1
• Filed: 03/01/2008
• Issued: 01/04/2011
• Est. Priority Date: 03/02/2007
• Status: Active Grant

• Current Assignee: AG Systems Incorporated (Lenz, Inc.)
• Original Assignee: AG Systems Incorporated (Lenz, Inc.)
• Inventors: Godil, Asif Aziz
• Primary Examiner(s): Leung; Quyen
• Assistant Examiner(s): KENERLY, TERRANCE L
• Application Number:
  US12/074,027
• Time in Patent Office: 1,039 Days
• Field of Search: 310/309, 310/308, 310/310, 385/315, 359/872
• US Class Current: 310/309
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: H02N 1/006 of the gap-closing type H02N1/004 takes precedence

Abstract

The present invention combines electrostatic comb with parallel plate actuation in a novel design to create a robust low voltage MEMS Micromirror. Other unique advantages of the invention include the ability to close the comb fingers for additional reliability and protection during mirror snapping with over voltage.

Claims

1. A micro electro mechanical system, comprising:

a rotor structure comprising;

a first electrically conductive surface area that is part of a first side of the rotor structure and is electrically coupled to a first bondpad,

a first portion of a first torsional hinge extending out of a second side of the rotor structure and is electrically coupled to the first bondpad,

a first portion of a second torsional hinge extending out of a third side, that is opposite the second side, of the rotor structure and is electrically coupled to the first bondpad, wherein the first and second torsional hinges are collinear and define an axis of rotation around which the rotor structure rotates, and

a first snapping tab extending out of a fourth side of the rotor structure that is electrically coupled to the first bondpad;

a stator structure comprising a second electrically conductive surface area that is electrically coupled to a second bondpad, wherein the rotor structure rotates from a first position to a second position due to an electrostatic force that is produced, between the first and second electrically conductive surface areas, based on a first voltage potential that is applied between the first and second bondpads;

a second portion of the first torsional hinge, that is mechanically coupled to the stator structure and the first portion of the first torsional hinge;

a second portion of the second torsional hinge, that is mechanically coupled to the stator structure and the first portion of the second torsional hinge, wherein the first and second torsional hinges produce a mechanical force that resists the rotation of the rotor structure; and

a first aperture that is electrically coupled to the first bondpad and is electrically isolated from the second electrically conductive surface area, wherein the first snapping tab makes both an electrical and a mechanical contact with the first aperture when the rotor structure rotates to a third position based on a second voltage potential, that is applied between the first and second bondpads.

2. The micro electro mechanical system of claim 1, wherein the first aperture mechanically restricts both the rotation of the rotor structure to essentially the third position and the lateral displacement of the rotor structure in a plane that is substantially orthogonal to a rotational plane, wherein the rotational plane is orthogonal to the axis of rotation.

3. The micro electro mechanical system of claim 2, wherein the first and second torsional hinges provides a restoring mechanical force that rotates the rotor structure back to the first position whenever the voltage potential that is applied between the first and second bondpads is less than a third voltage potential.

4. The micro electro mechanical system of claim 1, wherein the rotor structure further comprising:

a light reflective surface that is formed on a fifth side, which is opposite the first side, of the rotor structure.

5. The micro electro mechanical system of claim 1, wherein the rotor structure further comprising:

a metallic surface that is formed on a fifth side, which is opposite the first side, of the rotor structure, wherein the metallic surface is a transducer used to transmit or receive electromagnetic waves signal.

6. The micro electro mechanical system of claim 1, wherein the first electrically conductive surface area comprises a first planar and a first comb structure.

7. The micro electro mechanical system of claim 6, wherein the second electrically conductive surface area comprises a second planar structure, which is substantially parallel to the first planar structure, and a second comb structure which is dimensioned according to the first comb structure to avoid mechanical contact with the first comb structure when the rotor structure rotates.

8. The micro electro mechanical system of claim 1, wherein the first electrically conductive surface area comprises a closed comb structure.

9. The micro electro mechanical system of claim 8, wherein the second electrically conductive surface area comprises a comb structure that is dimensioned according to the closed comb structure to avoid mechanical contact with the closed comb structure when the rotor structure rotates.

10. The micro electro mechanical system of claim 1, wherein both the second portion of the first torsional hinge and the second portion of the second torsional hinge are electrically coupled to the first bondpad.

11. The micro electro mechanical system of claim 1, wherein at least one of the stator structure and the rotor structure is formed using a silicon on insulator wafer.

12. The micro electro mechanical system of claim 11, wherein both the second portion of the first torsional hinge and the second portion of the second torsional hinge are rigidly attached to at least one of the stator structure and the silicon on insulator wafer.

13. The micro electro mechanical system of claim 12, wherein the silicon on insulator wafer is a semiconductor wafer.

14. The micro electro mechanical system of claim 3, wherein the rotor structure further comprising:

a second snapping tab extending out of a sixth side of the rotor structure, that is opposite the fourth side of the rotor structure, and is electrically coupled to the first bondpad, wherein the rotor structure is substantially symmetrical and substantially balanced with respect to the axis of rotation.

15. The micro electro mechanical system of claim 14, wherein the stator structure further comprising:

a third electrically conductive surface area, which is electrically isolated from the second electrically conductive surface area, wherein the third electrically conductive surface area is electrically coupled to a third bondpad.

16. The micro electro mechanical system of claim 15, wherein the rotor structure rotates from the first position to a fourth position due to an electrostatic force that is produced, between the first and third electrically conductive surface areas, based on a fourth voltage potential that is applied between the first and third bondpads.

17. The micro electro mechanical system of claim 16, further comprising:

a second aperture that is electrically coupled to the first bondpad and is electrically isolated from the second and third electrically conductive surface area, wherein the second snapping tab makes both an electrical and a mechanical contact with the second aperture when the rotor structure rotates to a fifth position.

18. The micro electro mechanical system of claim 17, wherein the rotor structure rotates to the fifth position based on a fifth voltage potential that is applied between the first and third bondpads.

19. The micro electro mechanical system of claim 18, wherein the second aperture mechanically restricts both the rotation of the rotor structure to essentially the fifth position, and the lateral displacement of the rotor structure in a plane that is substantially orthogonal to a rotational plane, wherein the rotational plane is orthogonal to the axis of rotation.

20. The micro electro mechanical system of claim 19, wherein the first and second torsional hinges provides a restoring mechanical force that rotates the rotor structure back to the first position whenever the voltage potential that is applied between the first and third bondpads is less than the third voltage potential.