Projection display

• US 20040218149A1
• Filed: 05/28/2004
• Published: 11/04/2004
• Est. Priority Date: 08/30/2000
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Huibers, Andrew G.
• Granted Patent: US 7,172,296 B2
• Time in Patent Office: Days
• US Class Current: 353/50
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G03B 21/28 Reflectors in projection beam in illumination beam G03B21/2066
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

In order to minimize light diffraction along the direction of switching and more particularly light diffraction into the acceptance cone of the collection optics, in the present invention, micromirrors are provided which are not rectangular. Also, in order to minimize the cost of the illumination optics and the size of the display unit of the present invention, the light source is placed orthogonal to the rows (or columns) of the array, and/or the light source is placed orthogonal to a side of the frame defining the active area of the array. The incident light beam, though orthogonal to the sides of the active area, is not however, orthogonal to any substantial portion of sides of the individual micromirrors in the array. Orthogonal sides cause incident light to diffract along the direction of micromirror switching, and result in light ‘leakage’ into the ‘on’ state even if the micromirror is in the ‘off’ state. This light diffraction decreases the contrast ratio of the micromirror. The micromirrors of the present invention result in an improved contrast ratio, and the arrangement of the light source to micromirror array in the present invention results in a more compact system. Another feature of the invention is the ability of the micromirrors to pivot in opposite direction to on and off positions (the on position directing light to collection optics), where the movement to the on position is greater than movement to the off position. A further feature of the invention is a package for the micromirror array, the package having a window that is not parallel to the substrate upon which the micromirrors are formed. One example of the invention includes all the above features.

Claims

1. A projection display, comprising:

a light source for providing light to an array of micromirrors;

an array of micromirrors, each micromirror having a shape defined by a plurality of micromirror sides;

wherein light from the light source is incident on the array of micromirrors during operation;

wherein the array has four sides and wherein there are no micromirror sides of micromirrors in the array that are parallel to any array sides;

and wherein micromirrors are capable of movement between an OFF state and an ON state and wherein each micromirror corresponds to a pixel in a viewed image.

2. The projection display of claim 1, further comprising a color wheel.

3. The projection display of claim 1, further comprising a light pipe.

4. The projection display of claim 1, wherein the light source is an arc lamp.

5. The projection display of claim 1, which is a rear projection TV.

6. The projection display of claim 1, which is a front projection TV.

7. The projection display of claim 1, wherein no micromirror sides are parallel to the incident light beam when viewed from above the array.

8. The projection display of claim 1, wherein the incident light beam is incident orthogonally to a side of the array.

9. The projection display of claim 1, wherein the micromirrors are positioned on a lattice aligned at an angle to the X and Y axes of the array.

10. The projection display of claim 1, wherein the micromirrors comprise micromirror plates that are connected via hinges to a substrate, and wherein the substrate, micromirror plates and hinges are disposed in different planes.

11. The projection display of claim 1, wherein a first gap is defined between the hinge and the micromirror plate, and a second gap is defined between the micromirror plate and the substrate.

12. The projection display of claim 1, wherein a first gap is defined between the substrate and the hinge and a second gap is defined between the hinge and the micromirror plate.

13. The projection display of claim 1, wherein the array of micromirrors is disposed in a package having a light transmissive window.

14. The projection display of claim 1, wherein a mask is provided as part of the package.

15. The projection display of claim 1, wherein the mask is formed on the package window and extends around a periphery of the micromirror array.

16. The projection display of claim 1, wherein a molecular scavenger is provided within the package.

17. The projection display of claim 1, wherein a getter is provided within the package.

18. The projection display of claim 1, wherein a source of stiction reducing agent is provided within the package.

19. The projection display of claim 1, further comprising a color wheel, a light pipe and a TIR prism.

20. The projection display of claim 1, wherein the micromirrors are tiled together

21. The projection display of claim 1, wherein from 64,000 to 2,000,000 micromirrors are provided in the array.

22. The projection display of claim 1, further comprising a TIR prism.

23. The projection display of claim 1, wherein from 2,000,000 to 3,000,000 micromirror are provided in the array.

24. The projection display of claim 1, wherein the micromirror array has an area of from 1 cm² to 1 in².

25. The projection display of claim 1, wherein the micromirror has a resolution of 1,920,000 or higher.

26. The projection display of claim 1 having HDTV format.

27. The projection display of claim 1, having QXGA format.

28. The projection display of claim 1, having UXGA format.

29. A projection display comprising a light source;

an array of movable micromirror elements; and

a collection optics;

wherein each micromirror element in the array has a switching axis substantially parallel to at least one side of the active area of the array, and at an angle of from 35 to 60 degrees to all sides of the micromirror element.