Packaged micromirror array for a projection display

• US 20040218293A1
• 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 7,012,731 B2
• Time in Patent Office: Days
• US Class Current: 359/850
• 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 packaged micromirror array for a projection display, comprising:

array of micromirrors that are capable of movement between an OFF state and an ON state by pulse width modulation to achieve a gray scale image on a target; and

wherein each micromirror corresponds to a pixel in a viewed image on the target;

a package having a light transmissive window, wherein the array of micromirrors is disposed in the package having the light transmissive window;

a rectangular mask disposed on or above the micromirror array;

wherein each micromirror has a single convex protrusion in the direction of a side of the rectangular array and has no substantial sides parallel to said side of the rectangular array;

wherein a horizontal row of micromirrors extends corner to corner in the row parallel to a side of the rectangular 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 rectangular 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 packaged micromirror array of claim 1, further comprising bond wires at one end of the package electrically connecting the micromirror array to the package for actuation of the micromirrors.

3. The packaged micromirror array of claim 2, further comprising a rectangular mask.

4. The packaged micromirror array of claim 3, wherein the mask is formed on the package window and extends around a periphery of the micromirror array.

5. The packaged micromirror array of claim 4, wherein a molecular scavenger is provided within the package.

6. The packaged micromirror array of claim 3, wherein a getter is provided within the package.

7. The packaged micromirror array of claim 6, wherein a source of stiction reducing agent is provided within the package.

8. The packaged micromirror array of claim 6, wherein the micromirrors are capable of rotating at least +12 degrees to the ON position.

9. The packaged micromirror array of claim 8, in HDTV format.

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

11. The packaged micromirror array of claim 8, wherein the micromirrors are positioned on a lattice aligned at an angle to the sides of the rectangular array.

12. The packaged micromirror array of claim 10, 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.

13. The packaged micromirror array of claim 12, 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.

14. The packaged micromirror array of claim 12, 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.

15. The packaged micromirror array of claim 1, wherein a molecular scavenger is provided within the package.

16. The packaged micromirror array of claim 13, wherein the micromirrors comprise metal and a dielectric material, wherein the dielectric material is a nitride, carbide or oxide of silicon.

17. The packaged micromirror array of claim 12, wherein the package is a hermetic package.

18. The packaged micromirror array of claim 1, wherein the package is a partially hermetic package.

19. The packaged micromirror array of claim 17, wherein the micromirror array comprises circuitry and electrodes on a semiconductor substrate, and bond wires for electrically connecting the substrate to the package.

20. The packaged micromirror array of claim 19, wherein hinges of the micromirrors extend parallel to leading and trailing sides of the rectangular mask.

21. The packaged micromirror array of claim 20, wherein at least 1000 micromirrors are in the micromirror array.

22. The packaged micromirror array of claim 21, wherein the micromirrors are tiled together.

23. The packaged micromirror array of claim 22, wherein millions of micromirrors are provided.

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

25. The packaged micromirror array of claim 24, wherein the micromirror array is a rectangular array and wherein each micromirror has a switching axis substantially parallel to at least one side of the array.

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

27. The packaged micromirror array of claim 26, wherein each micromirror comprises a hinge and micromirror plate that are disposed in different planes, and wherein the hinge has a width of from 0.1 to 10 um.

28. The packaged micromirror array of claim 27, wherein the thickness of the micromirror plate is from 200 to 7300 angstroms.

29. The packaged micromirror array of claim 27, further comprising a light absorbing layer under the micromirrors to decrease light scatter through the gaps between the micromirrors.

30. The packaged micromirror array of claim 8, wherein from 64,000 to 2,000,000 micromirrors are provided in the array.

31. The packaged micromirror array of claim 8, wherein from 2,000,000 to 3,000,000 micromirrors are provided in the array.

32. The packaged micromirror array of claim 10, wherein the micromirror array has an area of from 1 cm² to 1 in².

33. The packaged micromirror array of claim 11, wherein the micromirror has a resolution of 1,920,000 or higher.

34. The packaged micromirror array of claim 8, having QXGA format.

35. The packaged micromirror array of claim 7, having UXGA format.

36. The packaged micromirror array of claim 1, wherein the micromirrors are L-shaped.

37. The packaged micromirror array of claim 1, wherein the micromirrors are V-shaped.

38. The packaged micromirror array of claim 8, wherein the micromirrors are square.

39. The packaged micromirror array of claim 1, wherein the micromirrors are four-sided.

40. The packaged micromirror array of claim 32, wherein the micromirrors are non-square rectangles.

41. The packaged micromirror array of claim 1, wherein the micromirrors are in the shape of a parallelogram.

42. The packaged micromirror array of claim 1, wherein the micromirrors have a single convex protrusion on a first side and a single concave cut-out on an opposite side.

43. The packaged micromirror array of claim 8, further comprising an agent for reducing stiction and a getter within the package.

44. The packaged micromirror array of claim 43, wherein micromirrors that are in an adjacent row and column have coincident sides that are not parallel to sides of the rectangular array.

45. The packaged micromirror array of claim 43, wherein the micromirrors are disposed corner to corner in rows and columns which rows and columns are parallel to sides of the rectangular array.

46. The packaged micromirror array of claim 43, wherein pixel controller cells are disposed at each micromirror with row and column wires connecting to the pixel controller cells, each column wire connecting to a pixel controller cell in every other row and each row wire connecting to a pixel controller cell in every other column.

47. The packaged micromirror array of claim 6, wherein the number of row wires times column wires is twice the number of micromirrors in the array.

48. The packaged micromirror array of claim 1, wherein the angle of the OFF state is different from a non-deflected state and is less in magnitude than the ON state of the micromirror.