Micromirrors and hinge structures for micromirror arrays in projection displays

• US 7,019,880 B1
• Filed: 08/25/2004
• Issued: 03/28/2006
• Est. Priority Date: 08/25/2004
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Reflectivity, Inc. (Texas Instruments, Inc.)
• Inventors: Huibers, Andrew, Patel, Satyadev
• Primary Examiner(s): Dang, Hung Xuan
• Assistant Examiner(s): TRA, TUYEN Q
• Application Number:
  US10/927,562
• Publication Number:
  US 20060050353A1
• Time in Patent Office: 580 Days
• Field of Search: 359/238, 359/290, 359/291, 359/292, 359/295, 359/222, 359/223, 359/224, 359/230, 359/320
• US Class Current: 359/238
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

The micromirror of the present invention comprises a mirror plate having thereon a cavity allowing deformation of a hinge attached to the mirror plate and deflection of the mirror plate in operation.

Claims

1. A spatial light modulator, comprising:

an array of micromirrors, each micromirror comprising a deformable hinge and a deflectable reflective mirror plate attached to the deformable hinge, wherein the mirror plate comprises a cavity in a surface of the mirror plate;

wherein a portion of the deformable hinge is disposed within the cavity at least during a rotation of the mirror plate.

2. The spatial light modulator of claim 1, wherein the micromirror further comprises:

a substrate; and

a post by which the mirror plate and the hinge of the micromirror is held on the substrate.

3. The spatial light modulator of claim 2, wherein the substrate is transmissive to visible light.

4. The spatial light modulator of claim 2, wherein the cavity is an elongated trench;

and

wherein the portion of the hinge is disposed within the trench then the mirror plate is not deflected.

5. The spatial light modulator of claim 2, wherein the hinge has a surface that is aligned to the same plane as the reflective surface of the minor plate.

6. The spatial light modulator of claim 5, wherein the surface of the hinge comprises a light blocking layer.

7. The spatial light modulator of claim 2, wherein the hinge is exposed to a light that is directed to the reflective surface of the minor plate for being modulated.

8. The spatial light modulator of claim 7, wherein the binge projects a shadow on the reflective surface of the mirror plate in the presence of the incident light.

9. The spatial light modulator of claim 2, wherein the hinge is outside the cavity when the mirror plate is not deflected, but inside the cavity when the mirror plate is deflected.

10. The spatial light modulator of claim 9, wherein the hinge is exposed to a light beam directed to the reflective surface of the mirror plate.

11. The spatial light modulator of claim 2, wherein the substrate is glass or quartz.

12. The spatial light modulator of claim 2, wherein the mirror plates is operable to switch between an ON state and an OFF state, wherein the mirror plate is rotated to an ON state angle in the ON state, and to an OFF state angle other than the ON state angle in the OFF state.

13. The spatial light modulator of claim 12, wherein the ON state angle is 10°

or more relative to the substrate.

14. The spatial light modulator of claim 12, wherein the ON state angle is 12°

or more relative to the substrate.

15. The spatial light modulator of claim 12, wherein the ON state angle is 14°

or more relative to the substrate.

16. The spatial light modulator of claim 2, wherein the mirror plate is substantially square.

17. The spatial light modulator of claim 2, wherein the mirror plate has a zigzagged edge.

18. The spatial light modulator of claim 1, further comprising:

an array of electrodes and circuitry with each electrode and circuitry being associated with a micromirror of the micromirror array for deflecting the mirror plate of the micromirror.

19. The spatial light modulator of claim 18, wherein the electrodes and circuitry are formed on a separate substrate than a substrate on which the micromirrors are formed.

20. The spatial light modulator of claim 18, wherein the electrodes and circuitry are formed on a substrate on which the micromirrors are formed.

21. The spatial light modulator of claim 1, wherein the cavity is located in a reflecting surface of the mirror plate.

22. The spatial light modulator of claim 1, wherein the cavity is located in a surface opposite to a reflecting surface of the mirror plate.

23. The spatial light modulator of claim 22, wherein the reflecting surface has no cavity and is substantially flat.

24. The spatial light modulator of claim 1, wherein the hinge extends the cavity.

25. The spatial light modulator of claim 1, wherein the hinge is a torsion hinge and is operable to rotate proximate to or within the cavity.

26. The spatial light modulator of claim 1, wherein the cavity is disposed such that the cavity faces an electrode provide for rotating said mirror plate.

27. A projection system, comprising;

an illumination system providing a light beam;

a spatial light modulator of claim 1;

an optical element for directing the light onto or from the spatial light modulator; and

a display target.

28. The system of claim 27, wherein the illumination system further comprises:

a light source;

a lightpipe; and

a color filter.

29. The system of claim 28, wherein the color filter is positioned between the light source and lightpipe.

30. The system of claim 28, wherein the color filter is positioned after lightpipe and the light source along a propagation path of light from the light source.

31. A spatial light modulator, comprising:

an array of micromirrors, each of which comprises a deformable hinge; and

deflectable mirror plate attached to the deformable hinge, wherein the mirror plate has a reflective surface that is substantially flat without a dent, and another surface having a cavity.

32. The spatial light modulator of claim 31, wherein the micromirror further comprises:

a substrate; and

a non-deflectable post directly connecting the mirror plate to the substrate.

33. The spatial light modulator of claim 31, wherein at least a portion of the deformable hinge is disposed in the cavity.

34. The spatial light modulator of claim 31, wherein the deformable hinge is connected to a portion of the cavity via a contact.