Double substrate reflective spatial light modulator with self-limiting micro-mechanical elements

• US 7,012,733 B2
• Filed: 12/01/2004
• Issued: 03/14/2006
• Est. Priority Date: 06/19/1995
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Reflectivity, Inc. (Texas Instruments, Inc.)
• Inventors: Huibers, Andrew G.
• Primary Examiner(s): THOMPSON, TIMOTHY J
• Application Number:
  US11/001,807
• Publication Number:
  US 20050111074A1
• Time in Patent Office: 468 Days
• Field of Search: 359/291, 359/290, 359/223, 359/224, 359/238, 359/578, 359/579, 359/846, 359/847, 359/849
• US Class Current: 359/291
• CPC Class Codes: G02B 26/08 for controlling the direction of light in light guides G02B6/35
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

A spatial light modulator including first and second substrate, and an array of deflectable elements disposed within a gap between the first and second substrates is disclosed herein. For electrostatically actuating the deflectable elements, an array of electrodes and circuitry is provided and positioned proximate to the deflectable elements.

Claims

1. A spatial light modulator device, comprising:

a first substrate that is a semiconductor substrate having an array of electrodes and circuitry;

a second substrate having an array of deflectable elements; and

wherein the electrodes are associated with the deflectable elements for deflecting the deflectable elements.

2. The spatial light modulator device of claim 1, wherein the first and second substrate are bonded together forming a space therebetween, in which space the deflectable elements are enclosed.

3. The spatial light modulator device of claim 1, wherein deflectable elements are microelectromechanical deflectable elements.

4. The spatial light modulator device of claim 1, wherein the distance between the substrates is from 1 to 5 microns.

5. The spatial light modulator device of claim 1, wherein the substrate having the deflectable elements further comprises:

a dielectric layer.

6. The spatial light modulator device of claim 3, wherein the substrate having the deflectable elements further comprises:

another dielectric layer, wherein said another dielectric layer has an optical index different from that of the dielectric layer.

7. The spatial light modulator device of claim 2, wherein the substrates are bonded together with the spacer therebetween using an adhesive.

8. The spatial light modulator device of claim 7, wherein the adhesive is epoxy.

9. The spatial light modulator device of claim 1, wherein the substrates are aligned together such that each deflectable element is aligned with an electrode.

10. The spatial light modulator device of claim 7, wherein the spacer is positioned outside the plurality of deflectable elements.

11. The spatial light modulator device of claim 1, wherein the deflectable elements are mirror plates.

12. The spatial light modulator device of claim 1, where in the deflectable element comprises a ceramic material.

13. The spatial light modulator device of claim 1, wherein the deflectable element comprises a light reflection layer.

14. The spatial light modulator device of claim 13, wherein each mirror plate is attached to a hinge such that the mirror plate is operable to rotate.

15. The spatial light modulator device of claim 14, wherein the ceramic material is silicon dioxide or silicon nitride.

16. The spatial light modulator device of claim 14, wherein the hinge is a torsion hinge.

17. The spatial light modulator device of claim 14, wherein the mirror plate comprise a first and second portions such that during the rotation of the mirror plate, the second portion moves towards the glass substrate and the first portion moves away from the glass substrate;

and wherein the hinge and the mirror plate are positioned in different planes.

18. A projector, comprising:

a light source providing an illumination light;

a spatial light modulator for modulating the illumination light, comprising

a first substrate that is a semiconductor substrate having an array of electrodes and circuitry;

a second substrate having an array of deflectable elements; and

wherein the electrodes are associated with the deflectable elements for deflecting the deflectable elements; and

a display target on which the modulated light is projected so as to produce a desired image.

19. A spatial light modulator device, comprising:

a first substrate having an array of circuitry and electrodes;

an array of deflectable elements fabricated on a second substrate that is a semiconductor substrate; and

wherein the first and second substrates are coupled to each other such that the deflectable elements are operable to be actuated by the electrodes.

20. The spatial light modulator device of claim 19, further comprising a spacer that is positioned within the plurality of deflectable elements.

21. The spatial light modulator device of claim 19, wherein the first and second substrates are bonded together with the spacer between the first and second substrates.

22. The spatial light modulator device of claim 19, wherein the distance between the substrates is from 1 to 5 microns.

23. The spatial light modulator device of claim 20, wherein the first substrate further comprises:

a dielectric layer.

24. The spatial light modulator device of claim 23, wherein the first substrate further comprises:

another dielectric layer, wherein said another dielectric layer has an optical index different from that of the dielectric layer.

25. The spatial light modulator device of claim 19, wherein the substrates are bonded together with the spacer in between using with an adhesive.

26. The spatial light modulator device of claim 25, wherein the adhesive is epoxy.

38. A projector, comprising:

a light source providing an illumination light;

a spatial light modulator of claim 22, 27, or 33 for modulating the illumination light; and

a display target on which the modulated illumination light is projected.

27. A double substrate device, comprising:

first and second substrates, one of which is a silicon substrate forming a gap therebetween;

an array of deflectable elements positioned within the gap so as to reflect when in their ON state, an incident light to a display target for producing a desired image.

an array of electrodes for actuating the deflectable elements;

wherein the first and second substrates are bonded together with a bonding material; and

wherein the bonding material comprises epoxy.

28. The device of claim 27, wherein the first and second substrates are bonded with a spacer that is disposed within the gap.

29. The device of claim 28, wherein the spacer is disposed around the perimeter the substrates.

30. The device of claim 28, wherein the distance between the substrates is from 1 to 5 microns.

31. The device of claim 28, where in the first substrate further comprises:

a dielectric layer.

32. The device of claim 28, wherein the deflectable elements are deflectable reflective micromirrors, each being attached to a torsion hinge such that the micromirror is operable to rotate relative to the substrates.

37. A method of modulating light, comprising:

providing a double substrate device of claim 27;

directing an incoming light beam onto the deflectable elements;

applying a voltage bias between the deflectable element and the electrode so as to deflect the deflectable element due to electrostatic attraction; and

deflecting the light beam back through said one of the two substrates.

33. A spatial light modulator device, comprising:

an array of deflectable elements;

a silicon substrate; and

wherein the deflectable elements are held by another substrate other than the silicon substrate above the silicon substrate such that the deflectable elements are operable to reflect an incident light so as to produce an desired image; and

wherein the two substrates are bonded together with a spacer disposed between the two substrates.

34. The spatial light modulator device of claim 33, wherein the deflectable elements are micromirrors.

35. The spatial light modulator device of claim 33, wherein the two substrates are bonded together with a bonding material.

36. The spatial light modulator device of claim 33, wherein the spacer is within the micromirrors.