Micromirror array for projection TV

• US 20040218292A1
• Filed: 05/28/2004
• Published: 11/04/2004
• Est. Priority Date: 08/03/2001
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Huibers, Andrew G.
• Granted Patent: US 7,023,606 B2
• Time in Patent Office: Days
• US Class Current: 359/850
• 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. An array of micromirrors formed on a substrate for use in a projection TV,

wherein the mirrors are disposed in an array having HDTV format;

and

wherein a horizontal row of micromirrors extends corner to corner in the row parallel to a side of the array, and wherein vertical lines corresponding to addressing columns extend from each micromirror in the row and connect to every other row of micromirrors; and

wherein a vertical column of micromirrors extends corner to corner in the column parallel to a side of the array, and wherein horizontal lines corresponding to addressing rows extend from each micromirror in the column and connect to every other column of micromirrors.

2. The micromirrors of claim 1, wherein the axis of rotation of the micromirrors is parallel to a side of the array.

3. The micromirrors of claim 1, wherein the micromirrors are square.

4. The micromirrors of claim 3, wherein the micromirrors are positioned on a lattice aligned at an angle to the X and Y axes of the array.

5. The micromirrors of claim 4, 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.

6. The micromirrors of claim 5, 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.

7. The micromirrors of claim 5, 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.

8. The micromirrors of claim 7, wherein a gap between adjacent micromirrors is between 0.1 um and 10 um.

9. The micromirrors of claim 8, wherein the micromirrors are disposed on a silicon substrate.

10. The micromirrors of claim 9, wherein a pluality of row wires and column wires are provided for addressing the micromirrors between ON states and OFF states and wherein the number of row wires times the number of column wires is greater than the number of micromirrors.

11. The micromirrors of claim 10, wherein the number of row wires times the number of column wires is twice the number of micromirrors.

12. The micromirrors of claim 1, wherein the ON and OFF positions of the micromirrors are defined by structure against which the micromirrors impinge.

13. The micromirrors of claim 1, wherein the ON and OFF positions of the micromirrors are defined by the micromirrors abutting one and/or a second substrate or structure thereon.

14. The micromirrors of claim 10, wherein the micromirrors are formed on a substrate adjacent circuitry and electrodes, at least two electrodes are disposed adjacent each micromirror, one electrode for electrostatically pulling the adjacent micromirror to an off position, and another electrode for electrostatically pulling the adjacent micromirror to an on position.

15. The micromirrors of claim 1, wherein the circuitry and electrodes are formed on the same substrate as the micromirrors.

16. The micromirrors of claim 12, further comprising additional electrodes for stopping movement of the adjacent micromirror when the micromirror arrives at the on or off position.

17. The micromirrors of claim 16, wherein the additional electrodes are at the same potential as the adjacent micromirror.

18. The micromirrors of claim 1, wherein the micromirrors comprise metal and a dielectric material.

19. The micromirrors of claim 18, wherein the dielectric material is a nitride, carbide or oxide of silicon.

20. The micromirrors of claim 10, wherein hinges of the micromirrors extend parallel to leading and trailing sides of the micromirror array.

21. The micromirrors of claim 20, wherein the micromirrors have four predominant sides.

22. The micromirrors of claim 21, wherein the sides of the micromirrors are of equal lengths.

23. The micromirrors of claim 22, wherein the micromirrors are tiled together.

24. The micromirrors of claim 1, wherein the OFF state of the micromirrors is at an angle less than the opposite angle of the micromirrors in the ON state.

25. The micromirrors of claim 23, wherein each micromirror has a switching axis substantially parallel to at least one side of the array.

26. The micromirrors of claim 25, wherein each micromirror has a switching axis that is at an angle of from 35 to 60 degrees to all sides of the micromirror.

27. The micromirrors of claim 26, wherein the thickness of the micromirror plate is from 200 to 7300 angstroms.

28. The micromirrors of claim 27, wherein both the ON and OFF states of the micromirrors are in a position other than a flat non-deflected state.

29. The micromirrors of claim 28, wherein the micromirrors are connected via underlying hinges to a substrate by means of an electrically conductive material that is aluminum, a metal alloy or a conductive ceramic compound.

30. The micromirrors of claim 28, wherein each micromirror is provided with a first electrode for deflecting the micromirror in a one direction, a second electrode for deflecting the micromirror in a second direction, and a third electrode for stopping movement of the micromirror.

31. The micromirrors of claim 1, wherein the micromirror array has an area of from 1 cm² to 1 in².

32. The micromirrors of claim 31, wherein the micromirror has a resolution of 1,920,000 pixels or higher.

33. The micromirrors of claim 1, having UXGA format.

34. The micromirrors of claim 1, wherein there are no substantial micromirror sides that are perpendicular to any array sides.

35. The micromirrors of claim 1, wherein each micromirror has four substantially straight sides, none of which are parallel to leading or trailing sides of the array which is rectangular.

36. A plurality of micromirrors in a two dimensional array for use in a projection TV, wherein the micromirrors are disposed in the array having HDTV format, and wherein a pluality of row wires and column wires are provided for addressing the micromirrors between ON states and OFF states and wherein the number of row wires times the number of column wires is greater than the number of micromirrors.

37. The micromirrors of claim 36, wherein the number of row wires times the number of column wires is twice the number of micromirrors.

38. The micromirrors of claim 36, wherein a horizontal row of micromirrors extends corner to corner in the row parallel to a side of the array, and wherein vertical lines corresponding to addressing columns extend from each micromirror in the row and connect to every other row of micromirrors;

and wherein a vertical column of micromirrors extends corner to corner in the column parallel to a side of the array, and wherein horizontal lines corresponding to addressing rows extend from each micromirror in the column and connect to every other column of micromirrors

39. The micromirrors of claim 38, wherein the micromirrors are square.