DEVICES AND METHODS FOR ENHANCING COLOR SHIFT OF INTERFEROMETRIC MODULATORS

• US 20110026095A1
• Filed: 10/12/2010
• Published: 02/03/2011
• Est. Priority Date: 07/31/2007
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Sethi, Gaurav, Griffiths, Jonathan C., Worthington, Eric, Kothari, Manish
• Granted Patent: US 8,081,373 B2
• Time in Patent Office: Days
• US Class Current: 359/290
• 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: G02B 3/0043 Inhomogeneous or irregular arrays, e.g. varying shape, size, height
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: G02B 5/045 Prism arrays

Abstract

The color reflected by an interferometric modulator may vary as a function of the angle of view. A range of colors are thus viewable by rotating the interferometric modulator relative to an observer. By placing a textured layer between an observer and an interferometric modulator, a pattern which includes the range of colors may be viewed by the observer, and the range of colors may thus be viewable from a single viewing angle.

Claims

1. An assembly, comprising:

an interferometric modulator stack, comprising;

an absorber layer which is at least partially transmissive to incident light;

a reflective layer fixed relative to the absorber layer; and

a spacer layer disposed between the absorber layer and the reflective layer and defining an interferometric gap within the interferometric modulator stack, and

a textured layer disposed on the side of the absorber layer opposite the reflective layer, wherein the textured layer comprises at least one optical feature having a curved surface.

2. The assembly of claim 1, wherein the textured layer is configured such that the assembly reflects a pattern of multiple colors.

3. The assembly of claim 2, wherein the color pattern reflected by the assembly is distinguishable by an observer.

4. The assembly of claim 2, wherein the color pattern varies as a function of the angle of view.

5. The assembly of claim 1, wherein the spacer layer has a substantially constant thickness.

6. The assembly of claim 1, wherein the at least one optical feature is configured to alter an effective angle of view of at least a portion of interferometric modulator stack.

7. The assembly of claim 6, wherein the optical feature comprises a prismatic structure.

8. The assembly of claim 6, wherein the feature comprises a spherical lens.

9. The assembly of claim 6, wherein the substrate comprises a first surface located adjacent the interferometric stack and a second surface located on the opposite side of the substrate from the interferometric stack, wherein the first surface of the substrate comprises said optical feature.

10. The assembly of claim 6, wherein the substrate comprises a first surface located adjacent the interferometric stack and a second surface located on the opposite side of the substrate from the interferometric stack, wherein the second surface of the substrate comprises said optical feature.

11. The assembly of claim 6, wherein the textured layer comprises planar outer surfaces, and wherein said optical feature is disposed within the textured layer.

12. The assembly of claim 1, additionally comprising a substrate disposed between the textured layer and the absorber layer, wherein the substrate is bonded to the textured layer via an adhesive.

13. The assembly of claim 12, wherein the adhesive comprises a material having substantially the same index of refraction as an adjacent layer.

14. The assembly of claim 12, wherein the adhesive comprises an optical structure disposed within the adhesive.

15. The assembly of claim 1, wherein at least one of the layers within the assembly is colored.

16. The assembly of claim 1, wherein the reflective layer is at least partially transmissive to incident light.

17. The assembly of claim 16, wherein the absorber and the reflector comprise substantially the same material and thickness.

18. The assembly of claim 16, additionally comprising a second textured layer disposed on the side of the interferometric modulator stack adjacent the reflective layer.

19. The assembly of claim 16, additionally comprising a light guiding layer disposed on the side of the interferometric modulator stack adjacent the reflective layer, wherein the light guiding layer is configured to reflect light towards the interferometric modulator stack.

20. The assembly of claim 1, additionally comprising a light guiding layer disposed between the textured layer and the absorber layer, wherein the light guiding layer is configured to reflect light towards the absorber layer.

21. The assembly of claim 1, wherein the interferometric modulator stack is configured to reflect at least a second-order color within the visible range when viewed at an angle normal to the interferometric modulator stack.

22. An optical structure, comprising:

a display element, wherein the wavelengths of light reflected by the display element are a function of the angle of view; and

an overlying layer comprising a surface having a texture configured to refract light in a pattern perceived as substantially random by an observer, wherein said textured surface forms a boundary between a first material having a first index of refraction and a second material having a second index of refraction, and wherein light reflected by the display element is refracted at the textured surface to vary the effective angle of view over the display element.

23. The optical structure of claim 22, wherein the display element is configured such that an increase in the angle of view will result in significant color shift as the angle of view increases.

24. The optical structure of claim 22, wherein the textured surface comprises a substantially planar region oriented at a non-zero angle to the display element.

25. The optical structure of claim 22, wherein the textured surface comprises a curved region.

26. The optical structure of claim 22, wherein the textured surface does not comprise a pattern which can be immediately distinguished by an observer.

27. An optical structure, comprising:

means for interferometrically modulating light, wherein the color reflected by said modulating means varies as a function of angle of view; and

means for refracting light reflected by said modulating means to vary the effective angle of view over the modulating means and to refract light in a pattern perceived as substantially random pattern by an observer.

28. The optical structure of claim 27, wherein the modulating means comprise an interferometric modulator.

29. The optical structure of claim 27, wherein the refracting means comprise a surface having a substantially random texture.