Full symmetrical wide-viewing angle display

• US 7,564,522 B2
• Filed: 05/23/2005
• Issued: 07/21/2009
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: Kopin Corporation
• Original Assignee: Kopin Corporation
• Inventors: Ong, Hiap L.
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Chung, David Y
• Application Number:
  US11/136,331
• Publication Number:
  US 20050270457A1
• Time in Patent Office: 1,520 Days
• Field of Search: 349/117, 349/119
• US Class Current: 349/117
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133634 the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
• CPC Class Codes: G02F 1/1362 Active matrix addressed cells G02F1/134336, G02F1/134363 take precedence
• CPC Class Codes: G02F 1/136277 formed on a semiconductor substrate, e.g. of silicon
• CPC Class Codes: G02F 2413/02 Number of plates being 2

Abstract

A microdisplay including a light-transmissive active circuit layer, the active circuit layer having an optical birefringence value that contributes to an asymmetrical viewing space and an optical compensator to compensate for the optical birefringence value of the active circuit layer. The optical compensator can include a retardation film, a c-plate, and/or a passive circuit layer. The passive circuit layer can be fabricated to equivalent specifications of the active circuit layer.

Claims

1. A microdisplay, comprising:

a light-transmissive active circuit layer, the active circuit layer having an optical birefringence value that contributes to an asymmetrical viewing space;

an optical compensator to compensate for at least a portion of the optical birefringence value of the active circuit layer, wherein the optical axis of the compensator is vertical with respect to the plane of the compensator, and wherein the optical compensator compensates an optical birefringence value in a range between about 0.02 μ

m and about 0.05 μ

m; and

a layer including a liquid crystal material.

2. The microdisplay of claim 1, wherein the optical compensator includes a retardation film or a c-plate.

3. The microdisplay of claim 1, wherein the optical compensator is disposed at the same side as the active circuit layer with respect to the liquid crystal layer and has a negative birefringence value.

4. The microdisplay of claim 1, wherein the optical compensator is disposed opposite the active circuit layer with respect to the liquid crystal layer and has a positive birefringence.

5. The microdisplay of claim 4, wherein the optical compensator includes a passive circuit layer and the passive circuit layer is fabricated to equivalent specifications of the active circuit layer.

6. The microdisplay of claim 1, wherein the optical compensator is disposed in close proximity to an outer surface of the active circuit layer.

7. The microdisplay of claim 6, wherein the optical compensator is integrated with a wide viewing angle film.

8. The microdisplay of claim 1, wherein the active circuit layer includes a CMOS circuit.

9. The microdisplay of claim 8, wherein the CMOS circuit includes a plurality of thin-film-transistors.

10. The microdisplay of claim 1, wherein the active circuit layer includes an array of pixel electrodes, having a pixel dimension of less than about 50 microns.

11. The microdisplay of claim 1, wherein the liquid crystal material is selected from the group comprising twisted-nematic liquid crystal material, single-domain tilted vertical alignment liquid crystal material, and multi-domain vertical alignment liquid crystal material.

12. The microdisplay of claim 1, wherein the optical birefringence value is less than 0.03 μ

m.

22. The microdisplay of claim 1, wherein the active circuit layer includes an array of pixel electrodes, having a pixel dimension of less than about 50 microns.

13. A method for compensating an asymmetrical viewing space of a microdisplay having an active circuit layer with an optical birefringence value that contributes to the asymmetrical viewing space, comprising:

adding an optical compensator to compensate for at least a portion of the optical birefringence value of the active circuit layer,

wherein the optical axis of the compensator is vertical with respect to the plane of the compensator, and wherein the compensator compensates an optical birefringence of the active circuit layer in a range between about 0.02 μ

m and about 0.05 μ

m.

14. The method of claim 13, wherein the optical compensator is a retardation film or a c-plate.

15. The method of claim 13, wherein the optical compensator is disposed at the same side as the active circuit layer with respect to the liquid crystal layer and has a negative birefringence value.

16. The method of claim 13, wherein the optical compensator is disposed opposite the active circuit layer with respect to the liquid crystal layer and has a positive birefringence.

17. The method of claim 16, wherein the optical compensator is passive circuit layer and the passive circuit layer is fabricated to equivalent specifications of the active circuit layer.

18. The method of claim 13 further comprising disposing the optical compensator in close proximity to an outer surface of the active circuit layer.

19. The method of claim 13, wherein the optical compensator is integrated with a wide viewing angle film.

20. The microdisplay of claim 13, wherein the active circuit layer includes a CMOS circuit.

21. The microdisplay of claim 20, wherein the CMOS circuit includes a plurality of thin-film-transistors.

23. The microdisplay of claim 13, wherein the liquid crystal material is selected from the group comprising twisted-nematic liquid crystal material, single-domain tilted vertical alignment liquid crystal material, and multi-domain vertical alignment liquid crystal material.

24. The microdisplay of claim 13 wherein the optical birefringence value is less than 0.03 μ

m.

25. A microdisplay, comprising:

means for displaying an image through an active circuit layer having an optical birefringence value that contributes to an asymmetrical viewing space;

means for compensating for at least a portion of the optical birefringence of the active circuit layer, wherein the optical axis of the compensator is vertical with respect to the plane of the compensator, and wherein the means for compensating compensates an optical birefringence value of the active circuit layer in a range between about 0.02 μ

m and about 0.05 μ

m; and

a layer including a liquid crystal material.