Devices and methods for enhancing color shift of interferometric modulators

• US 8,736,949 B2
• Filed: 12/20/2011
• Issued: 05/27/2014
• Est. Priority Date: 07/31/2007
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Kothari, Manish, Sethi, Gaurav, Griffiths, Jonathan Charles, Worthington, Eric
• Primary Examiner(s): Spector, David N
• Application Number:
  US13/331,094
• Publication Number:
  US 20120092749A1
• Time in Patent Office: 889 Days
• Field of Search: 359/290, 359/291, 359/292, 359/295, 359/578, 359/580, 359/584, 359/588, 359/589
• 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: 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 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 including a textured surface which refracts light in a substantially random pattern, 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 alter the effective angle of view over the display element.

2. The optical structure of claim 1, wherein the textured surface includes at least one optical feature having a curved surface.

3. The optical structure of claim 1, wherein the display element includes:

a reflective layer; and

an absorber layer which is at least partially transmissive to incident light, wherein the absorber layer is located between the reflective layer and the overlying layer.

4. The optical structure of claim 1, wherein the textured surface is located on a side of the overlying layer facing the display element.

5. The optical structure of claim 1, wherein the textured surface is located on a side of the overlying layer facing away from the display element.

6. The optical structure of claim 1, wherein the textured surface is disposed within the overlying layer.

7. The optical structure of claim 1, wherein the display element is configured such that an increase in the angle of view will result in color shift as the angle of view increases.

8. The optical structure of claim 1, wherein the textured surface includes a substantially planar region oriented at a non-zero angle to the display element.

9. The optical structure of claim 1, wherein the display element includes an interferometric modulator stack, wherein the interferometric modulator stack includes:

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.

10. The optical structure of claim 9, wherein the absorber and the reflector include substantially the same material.

11. The optical structure of claim 9, wherein the reflective layer is at least partially transmissive to incident light.

12. The optical structure of claim 9, wherein the spacer layer has a substantially constant thickness.

13. A method of fabricating an optical structure, comprising:

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

overlaying the display element with a layer having a textured surface which refracts light in a substantially random pattern, 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 alter the effective angle of view over the display element.

14. The method of claim 13, wherein the textured surface includes at least one optical feature having a curved surface.

15. The method of claim 13, wherein the display element includes:

a reflective layer; and

an absorber layer which is at least partially transmissive to incident light, wherein the absorber layer is located between the reflective layer and the overlying layer.

16. The method of claim 13, wherein the display element is configured such that an increase in the angle of view will result in color shift as the angle of view increases.

17. The method of claim 13, wherein the textured surface includes a substantially planar region oriented at a non-zero angle to the display element.