Micromirror array

• US 20040223240A1
• Filed: 05/28/2004
• Published: 11/11/2004
• 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 7,167,297 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 die singulated from a wafer and having an array of micromirrors in a two dimensional arrangement formed thereon;

wherein the micromirrors are positioned above circuitry and electrodes for electrostatically actuating the micromirrors;

wherein the micromirrors are four-sided and have no sides parallel to sides of the die;

wherein the micromirror array is rectangular and has an area of from 1 cm² to 1 in²;

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; and

wherein a plurality of row wires and column wires are provided for addressing the micromirrors and where the number of row wires times the number of column wires is greater than the number of pixels.

2. The die of claim 1, wherein the number of row wires times the number of column wires is twice the number of pixels.

3. The die of claim 1, wherein the number of micromirrors is from 1,920,000 to 3,145,278.

4. The die of claim 1, wherein the micromirrors are in UXGA format.

5. The die of claim 1, wherein the micromirrors are in HDTV format.

6. The die of claim 1, wherein an axis of rotation of the micromirrors is parallel to a side of the die.

7. The die of claim 1, wherein the micromirrors are square.

8. The die of claim 1, wherein the micromirrors are positioned on a lattice aligned at an angle to the X and Y axes of the die.

9. The die 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.

10. The die of claim 9, 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.

11. The die of claim 9, 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.

12. The die of claim 1, 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.

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

14. The die of claim 1, wherein the micromirrors are tiled together.

15. The die of claim 1, wherein each micromirror has a switching axis substantially parallel to at least one side of the array.

17. The die of claim 1, wherein both the ON and OFF states of the micromirrors are in a position other than a flat non-deflected state.

18. The die of claim 1, 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.

16. The die of claim 34, wherein the thickness of the micromirror plate is from 200 to 7300 angstroms.

19. A die singulated from a wafer and having an array of micromirrors in a two dimensional arrangement formed thereon;

wherein the micromirrors are formed above circuitry and electrodes for electrostatically actuating the micromirrors;

wherein the micromirrors have no sides parallel to sides of the array;

wherein the micromirror array has an area of from 1 cm² to 1 in²;

and wherein a plurality of row wires and column wires are provided for addressing the micromirrors and where the number of row wires times the number of column wires is twice the number of pixels.