Spring-ring micromechanical device

• US 6,147,790 A
• Filed: 05/13/1999
• Issued: 11/14/2000
• Est. Priority Date: 06/02/1998
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Knipe, Richard L., Meier, Robert E.
• Primary Examiner(s): Ben, Loha
• Application Number:
  US09/311,009
• Time in Patent Office: 551 Days
• Field of Search: 359/290, 359/291, 359/295, 359/846, 359/850, 359/224, 359/871, 347/239, 73/514.35, 73/514.36
• 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 rigid deflectable member (302, 314, 326) suspended over the substrate, and at least one spring (328) supported above the substrate and spaced apart from the rigid deflectable member. The spring resists deflection of the rigid deflectable member when the rigid deflectable member deflects to contact the spring. The improved micromechanical device is constructed by fabricating at least one support structure (116) on a substrate, fabricating at least one spring spaced apart from the substrate and supported by at least one of the support structures, and fabricating a deflectable member spaced apart from both the substrate and spring, and supported by at least one of the support structures. The improved micromechanical device is useful in a projection display system in which a micromirror device selectively reflects incident light, as directed by a controller electrically connected to the micromirror device, and the selectively reflected light is focused onto an image plane. The micromirror device is comprised an array of micromirror elements, each comprised of: a substrate, a spring supported by the substrate, and a deflectable rigid member supported by the substrate and spaced apart from the spring. The deflectable rigid member including a mirror to deflect toward the spring, which resists the deflection of the deflectable rigid member.

Claims

1. An improved micromechanical device comprising:

a substrate;

a rigid deflectable member suspended over said substrate; and

at least one spring supported above said substrate and spaced apart from said rigid deflectable member, said spring operable to resist deflection of said rigid deflectable member when deflection of said rigid deflectable member creates contact between said rigid deflectable member and said spring.

2. The improved micromechanical device of claim 1, said spring operable to prevent contact between said substrate and said rigid deflectable member.

3. The improved micromechanical device of claim 1, said rigid deflectable member capable of overcoming resistance by said spring and contacting said substrate.

4. The improved micromechanical device of claim 1, said spring comprising a leaf spring supported above said substrate.

5. The improved micromechanical device of claim 1, said spring comprising an elastic strip suspended above said substrate between two supports on said substrate.

6. The improved micromechanical device of claim 5, said elastic strip operable to deflect upon contact with said deflectable member.

7. The improved micromechanical device of claim 5, said elastic strip operable to twist upon contact with said deflectable member.

8. The improved micromechanical device of claim 5, said elastic strip comprising at least one thin section and at least one thick section, said thin section operable to twist upon contact between said elastic strip and said deflectable member.

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

10. The improved micromechanical device of claim 1 further comprising at least one address electrode supported by said substrate and positioned to allow a voltage differential between said address electrode and said rigid deflectable member to deflect said rigid deflectable member.

11. The improved micromechanical device of claim 1, said at least one spring comprising at least one metal strip.

12. The improved micromechanical device of claim 1, said at least one spring comprising at least one leaf spring underneath said rigid deflectable member on each side of a rotational axis.

13. The improved micromechanical device of claim 1, said rigid deflectable member supported above said substrate by at least one torsion beam and operable to rotate in either of two directions about an axis formed by said torsion beam.

14. The improved micromechanical device of claim 13, said at least one spring comprising:

at least one spring on each side of said axis.

15. The improved micromechanical device of claim 13, said spring comprising a ring-shaped spring supported by at least two support structures.

16. The improved micromechanical device of claim 15, said ring-shaped spring further comprising at least one nub extending from said ring-shaped spring.

17. The improved micromechanical device of claim 15, said ring-shaped spring further comprising at least one thin section, said thin section operable to twist upon contact between said ring-shaped spring and said deflectable member.

18. The improved micromechanical device of claim 1, said rigid deflectable member comprising:

a torsion beam yoke;

a mirror support spacervia; and

a mirror.

19. The improved micromechanical device of claim 18, wherein contact between said substrate and said torsion beam yoke limits deflection of said rigid deflectable member.

20. The improved micromechanical device of claim 18, wherein contact between said substrate and said mirror limits deflection of said rigid deflectable member.

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

fabricating at least one support structure on a substrate;

fabricating at least one spring spaced apart from said substrate and supported by said at least one support structure; and

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

22. The method of claim 21, wherein said at least one spring is fabricated between said deflectable member and said substrate.

23. The method of claim 21, wherein said deflectable member and said at least one spring are fabricated on a common at least one support structure.

24. The method of claim 21, said step of fabricating at least one spring comprising the step of fabricating a metal strip extending away from said at least one support structure.

25. The method of claim 21, said step of fabricating at least one spring comprising the step of fabricating a metal strip suspended between at least two of said at least one support structure.

26. The method of claim 21, said step of fabricating at least one spring comprising the step of fabricating a metal strip suspended between at least two of said at least one support structure, said metal strip fabricated having a thin portion operable to twist upon contact between said metal strip and said deflectable member.

27. 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 supported by said substrate; and

a deflectable rigid member supported by said substrate and spaced apart from said spring, said deflectable rigid 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 rigid member upon contact between said spring and said deflectable rigid 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 rigid members thereby selectively reflecting light striking said deflectable rigid 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.