Micromirrors and hinge structures for micromirror arrays in projection displays

• US 20060044519A1
• Filed: 08/25/2004
• Published: 03/02/2006
• Est. Priority Date: 08/25/2004
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Huibers, Andrew, Patel, Satyadev
• Granted Patent: US 7,436,572 B2
• Time in Patent Office: Days
• US Class Current: 353/30
• CPC Class Codes: G02B 26/008 in the form of devices for effecting sequential colour changes, e.g. colour wheels
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G03B 21/008 using micromirror devices
• CPC Class Codes: H04N 5/7458 the modulator being an array of deformable mirrors, e.g. digital micromirror device [DMD]

Abstract

A spatial light modulator is disclosed, along with methods for making such a modulator. The spatial light modulator comprises an array of micromirrors each having a hinge and a micromirror plate held via a hinge on a substrate, the micromirror plate being attached to the hinge such that the micromirror plate can rotate along a rotation axis and the hinge structure is located between the micromirror plate and the light source. The mirror plate is formed between the hinge and the substrate on which the hinge is formed. As a result, the hinge is exposed to the incident light during the operation.

Claims

1. A projection system, comprising:

an illumination system proving a incident light beam;

a spatial light modulator having an array of micromirrors, each of which comprises;

a substrate;

a deformable hinge; and

a mirror plate attached to the hinge such that the mirror plate is operable to rotate on the substrate;

wherein the hinge and the mirror plate are formed in separate planes parallel to the substrate when the mirror plate is not deflected, and wherein the hinge plane is closer to the incident light than the mirror plate plane; and

an optical element for directing the light onto or away from the spatial light modulator.

2. The system of claim 1, wherein the hinge is position relative to the mirror plate such that a portion of the mirror plate is shadowed of the hinge under the incident light beam.

3. The system of claim 1, wherein the substrate is transmissive to visible light.

4. The system of claim 3, wherein the substrate is glass.

5. The system of claim 1, further comprising:

another substrate having an array of electrodes and circuitry formed thereon.

6. The system of claim 1, wherein the substrate has an array of electrodes and circuitry formed thereon.

7. The system of claim 1, wherein the hinge is a torsion hinge.

8. The system of claim 1, wherein the illumination comprises:

a light source providing a light beam for the system;

a light pipe for conducting the light beam onto the spatial light modulator; and

a color wheel having a set of color segments.

9. The system of claim 8, wherein the color wheel is positioned between the light source and the light pipe.

10. The system of claim 8, wherein the color wheel is positioned after the light source and the light pipe in a propagation path of the light beams.

11. A projection system, comprising:

an illumination system providing a light beam;

a spatial light modulator having an array of micromirrors, each of which comprises;

a substrate;

a deformable hinge; and

a mirror plate attached to the hinge such that the mirror plate is operable to rotate on the substrate;

wherein the hinge and the mirror plate are located such that a portion of the mirror plate is underneath the hinge viewed along a direction of the incident light;

an optical element; and

a display target.

12. A projector, comprising:

a light source for providing a beam of light;

a condensing lens for condensing the light from the light source onto a spatial light modulator, said spatial light modulator further comprising;

a substrate that is transmissive to visible light;

a first gap below the substrate;

a mirror plate below the first gap;

a second gap below the mirror plate; and

a hinge below the second gap;

a display target; and

wherein the light beam impinges a surface of the mirror plate through the light transmissive substrate from the same side of the hinge.

13. The projector of claim 12, wherein the hinge of the spatial light modulator is connected to the substrate via a plurality of posts extending from the bottom surface of the substrate.

14. The projector of claim 12, wherein the hinge further comprises a flexible portion that is connected to the posts and which extends across the mirror plate and is connected to the mirror plate.

15. The projector of claim 12, further comprising a circuit substrate positioned below and spaced apart from the visible light transmissive substrate.

16. The projector of claim 12, wherein the mirror plate is held on the bottom surface of the visible light transmissive substrate;

and wherein the mirror plate has first and second portions such that during deflection of the mirror plate, the second portion of the mirror plate moves towards the bottom surface as the first portion moves away from the bottom surface.

17. The projector of claim 14, wherein said circuit substrate comprises an electrode for creating attraction between the mirror plate and the circuit substrate.

18. The projector of claim 12, wherein the mirror plate includes a conductive layer.

19. The projector of claim 12, wherein the hinge is a torsion hinge.

20. The projector of claim 16, wherein the second portion of the mirror plate is constructed so as to abut against the visible light transmissive substrate to thereby limit deflection of the mirror plate.

21. The projector of claim 12, wherein the hinge has a zigzagged edge.

22. A spatial light modulator, comprising:

an optically transmissive substrate having thereon a deflectable element, the deflectable element comprising a hinge which is disposed on the same side of the deflectable element as the optically transmissive substrate.

23. The spatial light modulator of claim 22, wherein the hinge comprises a flexible portion that extends across and which is connected to the mirror plate, said flexible portion is formed on the same said of the mirror plate as the optically transmissive substrate.

24. The spatial light modulator of claim 22, wherein the hinge has a zigzagged edge.

25. The spatial light modulator of claim 22, further comprising:

a silicon substrate having an electrode and circuitry formed thereon, wherein the silicon substrate is disposed below and spaced apart from the visible light transmissive substrate.

26. The spatial light modulator of claim 22, wherein the mirror plate further comprises a reflecting layer for reflecting visible light.

27. The spatial light modulator of claim 26, wherein the mirror plate further comprises a conducting layer.

28. A spatial light modulator, comprising:

a semiconductor substrate having a deflectable element formed thereon, the deflectable element comprising a hinge which is disposed on the opposite side of the deflectable element as the semiconductor substrate.

29. A micromirror device, comprising:

a silicon substrate;

a first gap on the silicon substrate;

a mirror plate on the first gap;

a second gap on the mirror plate; and

a hinge on the mirror plate, wherein the mirror plate is attached to the hinge such that the mirror plate can rotate relative to the silicon substrate.

30. The device of claim 29, wherein the hinge comprises a flexible portion that extends across the mirror plate, said flexible portion being disposed on the second gap and the mirror plate.

31. The device of claim 29, wherein the mirror plate includes a reflection layer that reflects visible light.

32. The device of claim 29, wherein the mirror plate includes a conducting layer.

33. The device of claim 29, wherein the silicon substrate further comprises an electrode and circuitry for deflecting the mirror plate.

34. A micromirror device, comprising:

a substrate that is transmissive to visible light;

a first gap below the substrate;

a hinge below the first gap;

a second gap below the hinge; and

a mirror plate below the second gap, wherein the mirror plate is attached to the hinge such that the mirror plate can rotate relative to the substrate.

35. The device of claim 34, further comprising:

a circuitry substrate having a circuitry formed thereon, wherein the circuitry substrate is disposed below and spaced apart from the mirror plate for deflecting the mirror plate.

36. The device of claim 34, wherein the mirror plate further comprises a reflecting layer for reflecting visible light.

37. The device of claim 36, wherein the mirror plate further comprises a conducting layer.

38. A method of making a projector, comprising:

providing a light source, a collection lens, a projection lens and a display target;

providing a spatial light modulator, wherein the spatial light modulator comprises;

a substrate that is transmissive to visible light;

a first gap below the substrate;

a hinge below the first gap;

a second gap below the hinge;

a mirror plate below the second gap; and

arranging the spatial light modulator, the collection lens, the light source, the projection lens and the display target such that, a light beam from the light source is focused by the collection lens onto the mirror plate through the glass substrate, and reflected by the mirror plate, the reflected light being collected by the projection lens and projected onto the display target.