MECHANICAL LIGHT MODULATORS WITH STRESSED BEAMS

• US 20090195855A1
• Filed: 02/12/2009
• Published: 08/06/2009
• Est. Priority Date: 02/23/2006
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Pixtronix, Incorporated (Qualcomm, Inc.)
• Inventors: Barton, Roger W., Hagood, Nesbitt W., Payne, Richard S., Fijol, John J., Steyn, Jasper Lodewyk, Andersson, Mark B., Brosnihan, Timothy J., Wu, Joyce H.
• Granted Patent: US 8,526,096 B2
• Time in Patent Office: Days
• US Class Current: 359/290
• CPC Class Codes: G02B 26/00 Optical devices or arrangements for the control of light using movable or deformable optical elements control of light by modification of the optical properties of the media of the elements involved therein G02F1/00
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3433 using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices using liquid crystal devices G09G3/36; using electrochromic devices G09G3/38

Abstract

The invention relates to a spatial light modulator including a substrate having a surface and a modulation assembly coupled to the substrate including a modulation element and a compliant beam. The modulation assembly is configured to limit the bending of the compliant beam towards an opposing surface that would otherwise be caused by inherent stresses within the compliant beam. The invention also relates to a method of manufacturing a spatial light modulator including the steps of forming and releasing a modulation assembly that has a modulation element and a compliant beam formed in a pre-release position to have an intended inherent stress state. As a result of the stress state in the compliant beam, upon release of the compliant beam, the compliant beam bends into a rest position which is different than the pre-release position, where the rest position is based in part on the intended inherent stress state.

Claims

1. A spatial light modulator comprising:

a substrate having a surface; and

a modulation assembly coupled to the substrate including a modulation element and a compliant beam, wherein the modulation assembly is configured to limit the bending of the compliant beam towards an opposing surface that would otherwise be caused by inherent stresses within the compliant beam.

2. The spatial light modulator of claim 1, wherein the modulation assembly is configured such that the compliant beam has first and second ends and is coupled to the substrate at a first anchor.

3. The spatial light modulator of claim 2, wherein the modulation assembly is configured such that the compliant beam is coupled to the first anchor at the first end.

4. The spatial light modulator of claim 2, wherein the modulation assembly is configured such that the compliant beam is shaped to extend away from the first anchor from the first end and curve back towards the first anchor towards the second end.

5. The spatial light modulator of claim 2, wherein the modulation assembly is configured such that the compliant beam is coupled to the first anchor between the first and second ends.

6. The spatial light modulator of claim 2, comprising a second anchor, and wherein the modulation assembly is configured such that the compliant beam is further coupled to the substrate at the second anchor.

7. The spatial light modulator of claim 1, wherein the modulation assembly is configured such that the compliant beam has first and second ends that couple to a common anchor deposited on the substrate, and the shape of the compliant beam forms a loop.

8. The spatial light modulator of claim 7, wherein the loop comprises a first loop portion extending away from the common anchor and a second loop portion returning to the common anchor, wherein the length of the first loop portion is substantially greater than the length of the second loop portion.

9. The spatial light modulator of claim 7, wherein the loop comprises a first loop portion extending away from the common anchor and a second loop portion returning to the common anchor, wherein at least one of the first loop portion and the second loop portion includes a secondary loop.

10. The spatial light modulator of claim 1, wherein the modulation assembly comprises a second compliant beam, and wherein the modulation assembly is configured such that both the compliant beam and the second compliant beam attach to the modulation element.

11. The spatial light modulator of claim 1, wherein the modulation assembly comprises a stationary structure that is not coupled to the compliant beam, and wherein the modulation assembly is configured such that the stationary structure limits the bending of the compliant beam.

12. The spatial light modulator of claim 11, wherein the stationary structure comprises a sliding surface.

13. The spatial light modulator of claim 1, wherein the limitation of bending yields an intended beam rest position.

14. The spatial light modulator of claim 1, comprising a plurality of attachment points coupling the compliant beam to the substrate at positions on the compliant beam selected to promote the bending of the beam being limited by the modulation assembly configuration.

15. The spatial light modulator of claim 1, wherein the compliant beam comprises first and second beam materials coupled to one another, and wherein the first beam material has a first stress state, and the second beam material has a second, different stress state, thereby promoting the bending of the beam being limited by the modulation assembly configuration.

16. The spatial light modulator of claim 1, wherein the compliant beam is shaped to promote the bending of the beam being limited by the modulation assembly configuration.

17. A method of manufacturing a spatial light modulator comprising:

forming a modulation assembly including a modulation element and a compliant beam, wherein the compliant beam is formed in a pre-release position to have an intended inherent stress state, and

releasing the modulation assembly;

whereby, as a result of the stress state in the compliant beam, upon release of the compliant beam, the compliant beam bends into a rest position which is different than the pre-release position, wherein the rest position is based in part on the intended inherent stress state.

18. The method of claim 17, wherein the compliant beam comprises first and second faces, each perpendicular to a surface of a substrate, and wherein the intended inherent stress state comprises stress components local to the first face that substantially differ from stress components local to the second face.

19. The method of claim 18, wherein the magnitude of the stress components local to the first face are greater than the stress components local to the second face.

20. The method of claim 18, wherein stress components local to the first face are tensile while stress components local to the second face are compressive.

21. The method of claim 17, wherein the intended inherent stress state is selected such that a portion of the compliant beam, in the rest position, is separated from an opposing surface by no more than a predetermined distance, and wherein, upon actuation, the compliant beam is drawn towards the opposing surface.

22. The method of claim 17, wherein the intended inherent stress state is selected such that a portion of the compliant beam in the rest position is separated from an opposing surface by at least a predetermined distance, and wherein, upon actuation, the compliant beam is drawn towards the opposing surface.

23. The method of claim 17, wherein the intended inherent stress state is selected such that a portion of the compliant beam, in the rest position, is separated from an opposing surface by no more than a predetermined distance, and wherein, upon actuation, the compliant beam is drawn away from the opposing surface.

24. The method of claim 17, wherein the intended inherent stress state is selected such that a portion of the compliant beam in the rest position is separated from an opposing surface by at least a predetermined distance, and wherein, upon actuation, the compliant beam is drawn away from the opposing surface.

25. The method of claim 24, wherein the beam, in its rest position, is curved.

26. The method of claim 17, wherein forming the modulation assembly comprises forming the compliant beam by coupling first and second beam materials to one another, and wherein the first beam material has a first stress state, and the second beam material has a second, different stress state.

27. The method of claim 17, wherein the inherent stress state comprises a stress gradient.

28. The method of claim 17, wherein upon release, the beam bends into an intended rest position.

29. The method of claim 17, wherein forming the modulation assembly comprises forming the compliant beam to have a first shape prior to releasing the modulation assembly and to have a different shape in the rest position.