Electro-optical package with drop-in aperture

• US 6,762,868 B2
• Filed: 11/09/2001
• Issued: 07/13/2004
• Est. Priority Date: 11/16/2000
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Kocian, Thomas A., Liu, Jwei Wien
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US09/990,952
• Publication Number:
  US 20020056900A1
• Time in Patent Office: 977 Days
• Field of Search: 359/237, 359/290, 359/291, 359/298, 359/808, 359/819, 359/811, 359/214, 359/224, 372/32, 372/20
• US Class Current: 359/237
• CPC Class Codes: B81B 7/0067 for controlling the passage of optical signals through the package
• CPC Class Codes: H01L 23/552 Protection against radiation, e.g. light or electromagnetic waves
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A drop-in aperture 20, which improves the performance and lowers the cost of electro-optical SLM packages. The disclosed package provides a separate metal light shield (aperture) 20 and antireflective coated cover 33, and positions the aperture 20 inside the package 40 in close proximity to the SLM'"'"'s 41 surface. This approach further uses an on-chip SLM light shield to define the projected screen border, thereby making the edge definition of the metal drop-in aperture less critical. Therefore, the cover can be mounted well away from the plane of the SLM, which relaxes the defect requirements of the cover and lowers the cost of the overall package. The package of this invention improves the performance and lifetime and lowers the cost of projection display systems.

Claims

1. A spatial light modulator package, comprising:

a substrate;

a case molded to said substrate and defining a package cavity;

a spatial light modulator in said cavity;

a cover cooperating with said substrate to enclose said spatial light modulator and allowing light to pass through said cover to said spatial light modulator; and

an aperture spaced apart from said cover between said cover and said spatial light modulator.

2. The spatial light modulator package of claim 1, wherein said aperture is stamped metal.

3. The spatial light modulator package of claim 1, wherein:

said aperture is separate from said cover glass; and

said aperture is mounted on a surface inside said package cavity and in close proximity to said spatial light modulator.

4. The spatial light modulator package of claim 1, wherein said aperture prevents said light from reaching surfaces around perimeter of said spatial light modulator.

5. The spatial light modulator package of claim 1, further comprising:

a light shield fabricated on the surface of said spatial light modulator chip.

6. The spatial light modulator package of claim 1, wherein said cover is mounted out of the focal plane of the spatial light modulator.

7. The spatial light modulator package of claim 1, said cover having an anti-reflective coating.

8. The spatial light modulator package of claim 1, said spatial light modulator being a micromirror.

9. The spatial light modulator package of claim 1, further comprising:

an environmental control material carrier in said cavity; and

getters held by said carrier.

10. The spatial light modulator package of claim 9, wherein said getters are comprised of moisture collecting desiccants.

11. The spatial light modulator package of claim 10 wherein said aperture and carrier are combined.

12. A projection display comprising:

a light source for producing a beam of light;

a first condenser lens for focusing said beam of light;

a color filter wheel for filtering said focused beam of light;

a second condenser lens for focusing said filtered beam of light;

a spatial light modulator array mounted in a package with a drop-in aperture and window for spatially modulating said beam of light; and

a projection lens for focusing said spatially modulated beam of light on an image plane.

13. The projection display of claim 12 wherein:

said spatial light modulator array is a micromirror array; and

said aperture is mounted in close proximity to said micromirror array to limit the light reaching the area surrounding said micromirror array; and

said cover glass is mounted out of the focal plane of said micromirror array.

14. The projection display of claim 12 further comprising at least one environmental control material carrier.

15. The projection display of claim 14 wherein said environmental control material carrier holds at least one environmental control material selected from the group consisting of:

moisture collecting desiccants and lubricant storage reservoirs.

16. A spatial light modulator package, comprising:

a substrate defining a package cavity;

a spatial light modulator in said cavity;

a cover cooperating with said substrate to enclose said spatial light modulator and allowing light to pass through said cover to said spatial light modulator; and

an aperture spaced apart from said cover and between said cover and said spatial light modulator.

17. The spatial light modulator package of claim 16, wherein said aperture is stamped metal.

18. The spatial light modulator package of claim 16, wherein:

said aperture is mounted closer to the plane of said spatial light modulator than to the plane of said cover.

19. The spatial light modulator package of claim 16, said cover having an anti-reflective coating.

20. The spatial light modulator package of claim 16, said spatial light modulator being a micromirror.

21. The spatial light modulator package of claim 16, further comprising:

an environmental control material carrier in said cavity; and

getters held by said carrier.

22. The spatial light modulator package of claim 21 wherein said aperture and carrier are combined.

23. A projection display comprising:

a light source for producing a beam of light on a light path;

a spatial light modulator on said light path for spatially modulating said beam of light, said spatial light modulator comprising;

a substrate defining a package cavity;

a modulation device in said cavity;

a cover cooperating with said substrate to enclose said modulation device and allowing light to pass through said cover to said modulation device; and

an aperture spaced apart from said cover and between said cover and

said modulation device; and

a projection lens on said light path for focusing said spatially modulated beam of light onto an image plane.

24. The projection display of claim 23 wherein:

said spatial light modulator array is a micromirror array; and

said aperture is mounted in close proximity to said micromirror array to limit the light reaching the area surrounding said micromirror array; and

said cover glass is mounted out of the focal plane of said micromirror array.

25. The micromirror projection display of claim 23 further comprising at least one environmental control material carrier.

26. A method of packaging a spatial light modulator, the method comprising:

providing a package substrate;

attaching a spatial light modulator to said substrate;

attaching an aperture to said substrate in proximity to said spatial light modulator to limit light from reaching regions selected from the group consisting of regions of said substrate, regions of said spatial light modulator, bond wires, bond pads, and other peripheral structures; and

attaching a cover to said substrate to enclose said aperture and said spatial light modulator.

27. The method of claim 26, said attaching a spatial light modulator comprising attaching a micromirror device to said substrate.

28. The method of claim 26, said attaching an aperture to said substrate comprising attaching said aperture to a case attached to said substrate.

29. The method of claim 26, said attaching a cover to said substrate comprising attaching said cover to a case attached to said substrate.