High angle micro-mirrors and processes

• US 6,970,280 B2
• Filed: 11/16/2004
• Issued: 11/29/2005
• Est. Priority Date: 02/12/2003
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Reflectivity, Inc. (Texas Instruments, Inc.)
• Inventors: Patel, Satyadev R., Huibers, Andrew G., Heureux, Peter J.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): CHOI, WILLIAM C
• Application Number:
  US10/990,835
• Publication Number:
  US 20050078349A1
• Time in Patent Office: 378 Days
• Field of Search: 359/223, 359/224, 359/230, 359/290, 359/291, 359/295, 359/298, 359/318, 359/855, 359/225, 348/770, 348/771, 310/36
• US Class Current: 359/290
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A micro-mirror that comprises a substrate, a hinge structure formed on the substrate and a mirror plate attached to the hinge structure is provided for use in display systems. The mirror plate is capable of rotating from a non-deflected resting state to a state that is at least 14° degrees. In operation, the micro-mirror switches between an “ON”-state and “OFF”-state, which are defined in accordance with a rotational position of the mirror plate. The OFF state can be a non-deflected position of the micro-mirror (generally parallel to the substrate), the same angle (though opposite direction) as the ON state, or an angle less than the ON state (though in the opposite direction). Reflected light from the “ON” and “OFF” states are thus separated and the contrast ratio is improved.

Claims

1. A projection system comprising:

a light source;

a spatial light modulator comprising an array of micro-mirrors;

condensing optics, wherein light from the light source is focused as a cone of light with an axis onto the array of micro-mirrors;

projection optics for projecting light selectively reflected from the array of micro-mirrors;

a controller for selectively actuating micro-mirrors in the array of micro-mirrors;

wherein the array of micro-mirrors comprises a substrate and a plurality of mirror plates disposed in a first state in a plane parallel to the substrate, each mirror plate held on the substrate by a hinge structure that comprises a hinge that is spaced apart from the mirror plate so as to define a gap between the hinge and the mirror plate, wherein the hinge structure and mirror plate are constructed so as to be capable of being actuated from the first state to a second state that is at least 14°

(fourteen degrees) from the first state, and wherein the first axis of the cone of light incident on the micro-mirrors is at an angle relative to a line perpendicular to the plane parallel to the substrate of at least 28 (twenty eight) degrees.

2. The projection system of claim 1, wherein the second state of the micro-mirror plate is about 16°

degrees or more from the first state.

3. The projection system of claim 1, wherein the second state of the micro-mirror plate is 17.5°

degrees or more from the first state.

4. The projection system of claim 1, wherein the first state is a state when the mirror plate is parallel to the substrate.

5. The projection system of claim 1, further comprising:

a set of electrodes and circuitry formed on the substrate for controlling the micro-mirror.

6. The projection system of claim 5, wherein the hinge structure further comprises one or more posts formed on the substrate that rotatably hold the mirror plate via the hinge.

7. The projection system of claim 5, wherein the hinge structure further includes:

first and second posts standing on the substrate; and

the hinge attached to the first and second posts.

8. The projection system of claim 5, further comprising a torsion hinge for rotatably connecting the mirror plate to the substrate.

9. The projection system of claim 8, wherein the torsion hinge is disposed on a side of the mirror plate opposite to that of the substrate and defining a gap between the torsion hinge and the mirror plate.

10. The projection system of claim 9, wherein the substrate is a light transmissive substrate.

11. The projection system of claim 8, wherein the hinge comprises a conductive ceramic layer.

12. The projection system of claim 11, wherein the ceramic layer comprises a nitride or oxide of a metalloid or early transition metal.

13. The projection system of claim 11, wherein the hinge further comprises an electrically conductive layer formed on the ceramic layer.

14. The projection system of claim 13, wherein the electrically conductive layer comprises a conductive ceramic, elemental metal, intermetallic compound or metal alloy.

15. The projection system of claim 5, wherein the mirror plate is a substantially four-sided plate with an axis of rotation off-set from a diagonal of the plate.

16. The projection system of claim 5, wherein the torsion hinge is disposed between the mirror plate and the substrate, which is a semiconductor substrate.

17. The projection system of claim 5, wherein the first axis of the cone of light incident on the micro-mirrors is at an angle relative to a line perpendicular to the plane parallel to the substrate of at least 30 (thirty) degrees.

18. A spatial light modulator for use in a projection system, comprising:

an array of micro-mirrors, each micro-mirror comprising;

a substrate;

a mirror plate formed on the substrate, the mirror plate having a non-deflected resting state, the mirror plate held on the substrate by a hinge structure that comprises a hinge that is spaced apart from the mirror plate so as to define a gap between the hinge and the mirror plate; and

wherein the mirror plate operates in a binary-mode that includes an ON-state and OFF-state, the ON-state being at least 14°

(fourteen degrees) from the non-deflected resting state.

19. The spatial light modulator of claim 18, wherein the OFF-state is the non-deflected resting state.

20. The spatial light modulator of claim 19, wherein the ON-state is from 15°

(fifteen degrees) to 27°

(twenty seven degrees) from the non-deflected resting state.

21. The spatial light modulator of claim 19, wherein the ON-state of the mirror plate turns a pixel of an image on, and the OFF-state of the mirror plate turns the pixel off.

22. The spatial light modulator of claim 21, wherein the OFF state is not the non-deflected resting state.

23. The spatial light modulator of claim 19, wherein the substrate is a substrate transmissive to visible light.

24. The spatial light modulator of claim 18, wherein the hinge structure further includes:

a first and second posts; and

a hinge attached to the first and second posts and the mirror plate, with the hinge disposed in a different plane than the mirror plate, such that the mirror plate can rotate relative to the substrate by the hinge.

25. The spatial light modulator of claim 24, further comprising:

a set of electrodes and circuitry formed on the substrate for controlling the micro-mirror, the substrate being a silicon substrate.

26. A projection system comprising:

a light source;

a spatial light modulator comprising;

a substrate;

an array of micro-mirrors comprising an array of mirror plates connected to the substrate via a hinge, wherein the size of the mirror plates is less than 20 microns; and

wherein the mirror plates operate in a binary-mode including an ON state and an OFF state, the ON-state being at least 14°

(fourteen degrees) from a non-deflected resting state of the mirror plates;

a condensing optics, whereby the light from the light source is focused as a cone of light with an axis onto the array of micro-mirrors; and

a projection optics for projecting light selectively reflected from the array of mirror plates.

27. The projection system of claim 26, further comprising:

a controller for selectively actuating the mirror plates;

wherein the array of mirror plates are operable to be in a first state in a plane parallel to the substrate;

wherein each mirror plate is held on the substrate by a hinge structure that comprises the hinge that is spaced apart from the mirror plate so as to define a gap between the hinge and the mirror plate; and

wherein the first axis of the cone of light incident on the micro-mirrors is at an angle relative to a line perpendicular to the plane parallel to the substrate of at least 28°

(twenty eight) degrees.

28. The projection system of claim 27, wherein the first state is a state when the mirror plate is parallel to the substrate.

29. The projection system of claim 27, further comprising:

a set of electrodes and circuitry formed on the substrate for controlling the micro-mirror.

30. The projection system of claim 29, wherein the hinge structure further comprises one or more posts formed on the substrate that rotatably hold the mirror plate via the hinge.

31. The projection system of claim 30, wherein the hinge structure further includes:

first and second posts standing on the substrate; and

the hinge attached to the first and second posts.

32. The projection system of claim 31, further comprising a torsion hinge for rotatably connecting the mirror plate to the substrate.

33. The projection system of claim 32, wherein the hinge comprises a conductive ceramic layer.

34. The projection system of claim 33, wherein the ceramic layer comprises a nitride or oxide of a metalloid or early transition metal.

35. The projection system of claim 33, wherein the hinge further comprises an electrically conductive layer formed on the ceramic layer.

36. The projection system of claim 35, wherein the electrically conductive layer comprises a conductive ceramic, elemental metal, intermetallic compound or metal alloy.

37. The projection system of claim 29, wherein the first axis of the cone of light incident on the micro-mirrors is at an angle relative to a line perpendicular to the plane parallel to the substrate of at least 30 (thirty) degrees.