High yield spring-ring micromirror

• US 6,285,490 B1
• Filed: 12/30/1999
• Issued: 09/04/2001
• Est. Priority Date: 12/30/1998
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Knipe, Richard L., Huffman, James D., Meier, Robert E.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Magee, John J.
• Application Number:
  US09/475,730
• Time in Patent Office: 614 Days
• Field of Search: 359/291, 359/224, 359/290, 359/298, 345/108, 347/239
• US Class Current: 359/291
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

An improved micromechanical device comprising a substrate (104), a deflectable member (102) suspended over the substrate (104), at least one spring-ring (124) supported above the substrate (104); and at least one address electrode (110) spaced apart from substrate (104). The spring-ring (124) resists deflection of the deflectable member (102) when the deflectable member (102) deflects to contact the spring-ring (124). By moving the address electrode (110) off the substrate level, the micromirror is much more immune to particle-caused short circuits, and a planer surface on which to fabricate the mirror (102) is provided without the need to utilize an inverse spacer layer.

Claims

1. An improved micromechanical device comprising:

a substrate;

a spring-ring suspended over said substrate;

at least one address electrode supported over said substrate; and

a deflectable member supported over said spring-ring and said address electrode by a torsion beam hinge, said deflectable member operable to rotate about said torsion beam hinge in response to a voltage differential between said deflectable member and said address electrode, said spring-ring operable to resist deflection of said deflectable member when deflection of said deflectable member creates contact between said deflectable member and said spring-ring.

2. The improved micromechanical device of claim 1, said deflectable member comprising a mirror.

3. A method of fabricating an improved micromechanical device, said method comprising the steps of:

fabricating at least two support structure on a substrate;

fabricating at least one spring-ring spaced apart from said substrate and supported by at least one of said at least two support structures;

fabricating at least one address electrode spaced apart from said substrate and supported by at least one of said at least two support structures; and

fabricating a deflectable member spaced apart from said substrate, said at least one spring-ring, and said at least one address electrode, and supported by at least one of said at least one support structures, said deflectable member operable to move into contact with said spring-ring and said spring-ring operable to resist further movement of said deflectable member.

4. The method of claim 3, said steps of fabricating at least one spring-ring and fabricating at least one address electrode performed simultaneously.

5. The method of claim 3, said steps of fabricating at least one spring-ring and fabricating at least one address electrode performed simultaneously, wherein said at least one spring-ring and said at least one address electrode are equally spaced away from said substrate.

6. The method of claim 3, said step of fabricating at least one spring-ring comprising the step of fabricating a metal strip suspended between at least two of said at least one support structures.

7. A display system comprising:

a light source capable of providing a light beam along a light path;

a micromirror device on said light path, said micromirror device comprised an array of micromirror elements, each said micromirror element comprised of;

a substrate;

a spring-ring supported by and spaced apart from said substrate;

an address electrode supported by and spaced apart from said substrate; and

a deflectable member supported by said substrate and spaced apart from said spring, said deflectable member comprising a mirror in said light path and operable to deflect toward said spring, said spring operable to resist said deflection of said deflectable member upon contact between said spring and said deflectable member;

a controller electrically connected to said micromirror device, said controller providing electrical signals to said micromirror device to cause said micromirror device to selectively deflect said deflectable members thereby selectively reflecting light striking said deflectable members along a projection light path; and

projection optics located in said projection light path, said projection optics operable to focus light reflected by said micromirror device onto an image plane.