Spatial light modulator with integrated optical compensation structure

• US 8,111,445 B2
• Filed: 01/15/2008
• Issued: 02/07/2012
• Est. Priority Date: 02/03/2004
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Chui, Clarence, Sampsell, Jeffrey B., Cummings, William J., Tung, Ming-Hau
• Primary Examiner(s): Mack, Ricky
• Assistant Examiner(s): TRA, TUYEN Q
• Application Number:
  US12/014,657
• Publication Number:
  US 20080112039A1
• Time in Patent Office: 1,484 Days
• Field of Search: 359/290, 359/291, 359/292, 359/298, 359/223, 359/224, 359/320, 359/322
• US Class Current: 359/291
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02F 1/1335 Structural association of cells with optical devices, e.g. polarisers or reflectors
• CPC Class Codes: G02F 1/13356 characterised by the placement of the optical elements
• CPC Class Codes: G02F 1/21 by interference

Abstract

A spatial light modulator comprises an integrated optical compensation structure, e.g., an optical compensation structure arranged between a substrate and a plurality of individually addressable light-modulating elements, or an optical compensation structure located on the opposite side of the light-modulating elements from the substrate. The individually addressable light-modulating elements are configured to modulate light transmitted through or reflected from the transparent substrate. Methods for making such spatial light modulators involve fabricating an optical compensation structure over a substrate and fabricating a plurality of individually addressable light-modulating elements over the optical compensation structure. The optical compensation structure may be a passive optical compensation structure. The optical compensation structure may include one or more of a supplemental frontlighting source, a diffuser, a black mask, a diffractive optical element, a color filter, an anti-reflective layer, a structure that scatters light, a microlens array, and a holographic film.

Claims

1. A display device comprising:

a substrate;

an array of display pixels configured to form an image, each display pixel comprising at least one individually addressable light-modulating element arranged over the substrate and configured to interferometrically modulate incident visible light, said at least one individually addressable light-modulating element comprising;

an optical stack including a reflective layer disposed over the substrate;

a movable element; and

an air gap between the reflective layer and the movable element forming an optical cavity that changes size with movement of said movable element thereby interferometrically modulating incident visible light that forms part of the image; and

an optical compensation structure;

wherein the array of display pixels is arranged between the substrate and the optical compensation structure, and

wherein for said at least one individually addressable light-modulating element said optical stack is closer to the substrate and said moveable element is closer to said optical compensation structure and an optical path extending from the optical stack to the optical compensation structure passes through only one air gap that changes size with movement of said moveable element thereby interferometrically modulating incident visible light that forms part of the image.

2. The display device of claim 1 in which the optical compensation structure comprises a black mask.

3. The display device of claim 1 in which the optical compensation structure comprises a color filter.

4. The display device of claim 1 in which the optical compensation structure comprises a diffuser.

5. The display device of claim 1 in which the optical compensation structure comprises an anti-reflective layer.

6. The display device of claim 1 in which the optical compensation structure comprises a plurality of scattering elements.

7. The display device of claim 1 in which the optical compensation structure comprises a microlens array.

8. The display device of claim 1 in which the optical compensation structure comprises a diffractive optical element.

9. The display device of claim 1 in which the optical compensation structure comprises a planarization layer that comprises a scattering element.

10. The display device of claim 1 in which the optical compensation structure comprises a holographic film that mitigates a shift in reflected color with respect to an angle of incidence of the light transmitted through the substrate.

11. The display device of claim 1 in which the optical compensation structure comprises a black mask and a color filter.

12. The display device of claim 1 in which the optical compensation structure comprises a black mask and a diffuser.

13. The display device of claim 1 in which the optical compensation structure comprises a color filter and a diffuser.

14. The display device of claim 1 further comprising a planarization layer.

15. The display device claim 1 in which the substrate is at least partially reflective.

16. The display device of claim 1 in which the optical compensation structure is a passive optical compensation structure.

17. The display device of claim 1 in which the substrate is at least partially transparent.

18. The display device of claim 1 in which the substrate is partially transparent and partially reflective.

19. The display device of claim 1, wherein the light-modulating elements are reflective.

20. A spatial light modulator comprising:

a substrate;

a plurality of individually addressable interferometric light-modulating elements arranged over the substrate and configured to modulate incident visible light, each of the interferometric light-modulating elements comprising an optical stack including a reflective layer disposed over the substrate, a cavity comprising an air gap and disposed between the optical stack and a movable wall, said cavity configured to change size with the movement of the movable wall thereby interferometrically modulating incident visible light to form at least part of an image; and

at least one optical compensation structure, the plurality of individually addressable interferometric light-modulating elements being arranged between the substrate and the optical compensation structure, the optical compensation structure comprising a structure selected from the group consisting of an anti-reflective layer, a diffractive optical element, a structure that scatters light, a diffuser, a microlens array, and a holographic film,

wherein for each of said plurality of individually addressable light-modulating elements, said optical stack is closer to the substrate and said moveable wall is closer to said optical compensation structure and an optical path extending from the optical stack to the optical compensation structure passes through only one cavity configured to change size with the movement of the movable wall thereby interferometrically modulating incident visible light to form said at least part of the image.

21. The spatial light modulator of claim 20, wherein the at least one optical compensation structure comprises a black mask.

22. The spatial light modulator of claim 20, wherein the at least one optical compensation structure comprises a color filter.

23. The spatial light modulator of claim 20 further comprising a planarization layer.

24. The spatial light modulator of claim 20 in which the substrate is at least partially reflective.

25. The spatial light modulator of claim 20 in which the optical compensation structure is a passive optical compensation structure.

26. The spatial light modulator of claim 20 in which the substrate is at least partially transparent.

27. The spatial light modulator of claim 20 in which the substrate is partially transparent and partially reflective.

28. A display device comprising:

a substrate;

an array of display pixels configured to form an image, each display pixel comprising a means for interferometrically modulating light, said interferometrically light-modulating means comprising;

an optical stack including a reflective layer disposed over the substrate;

a movable element; and

an optical cavity disposed between the optical stack and the movable element, said optical cavity comprising an air gap that changes size with movement of said movable element thereby interferometrically modulating incident visible light to form part of the image; and

a means for compensating light;

wherein the array of display pixels is operatively arranged between the substrate and the means for compensating light, and

wherein for said means for interferometrically modulating light, said optical stack is closer to the substrate and said moveable element is closer to said means for compensating light and an optical path extending from the optical stack to the means for compensating light passes through only one cavity configured to change size with the movement of the movable element thereby interferometrically modulating incident visible light to form part of the image.

29. The display device of claim 28 in which the means for modulating light comprises at least one interferometric modulator.

30. The display device of claim 28 in which the means for compensating light comprises a structure selected from the group consisting of a diffractive optical element, a diffuser, an anti-reflective layer, a plurality of scattering elements, a microlens array, and a holographic film.

31. The display device of claim 28 in which the means for compensating light comprises a diffuser.

32. The display device of claim 28, wherein the means for compensating light comprises a black mask.

33. The display device of claim 28, wherein the means for compensating light comprises a color filter.