Colored liquid crystal display having a reflector which reflects different wavelengths of light for different incident angles

• US 5,691,790 A
• Filed: 08/04/1995
• Issued: 11/25/1997
• Est. Priority Date: 08/04/1995
• Status: Expired due to Term

• Current Assignee: Tyco Electronics Corporation (TE Connectivity Limited)
• Original Assignee: Raychem Corporation (TE Connectivity Limited)
• Inventors: Drzaic, Paul S., Havens, John
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): MILLER, CHARLES LELAND
• Application Number:
  US08/511,161
• Time in Patent Office: 844 Days
• Field of Search: 349/86, 349/113, 349/115, 359/15, 359/19
• US Class Current: 349/113
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133543 Cholesteric polarisers
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605

Abstract

A colored reflective liquid crystal display employs a liquid crystal light valve switchable between a light scattering and a transmissive state. Positioned on the non-viewing side of the light valve is a reflector which reflects light of selected wavelengths and transmits the other wavelengths.

Claims

1. A colored reflective liquid crystal display, comprising

a light valve which substantially scatters light in a scattering state and is substantially transparent in a non-scattering state, comprising a liquid crystal composite wherein plural volumes of liquid crystal material are dispersed in an encapsulating medium;

said light valve having a viewing and a non-viewing side, wherein some of the light scattered in the scattering state is forwardly scattered; and

a reflector disposed on said non-viewing side of said light valve which reflects white light toward said viewing side when said light valve is in the scattering state, and reflects colored light toward said viewing side when said light valve is in the non-scattering state, wherein the wavelength of the light reflected by said reflector is dependent on the incidence angle of the light.

2. A display according to claim 1, wherein said liquid crystal material is nematic.

3. A display according to claim 2, wherein said nematic liquid crystal material includes a pleochroic dye.

4. A display according to claim 1, wherein said liquid crystal material is cholesteric.

5. A display according to claim 4, wherein said liquid crystal material is cholesteric.

6. A display according to claim 1, wherein said display further includes a dark absorber optically coupled to said reflector on the side of said reflector away from said light valve.

7. A display according to claim 6, wherein said liquid crystal material is nematic.

8. A display according to claim 1, wherein said reflector is a holographic reflector.

9. A display according to claim 8, wherein said display further includes a dark light absorber optically coupled to said reflector on the side of said reflector away from said light valve.

10. A display according to claim 8, wherein said liquid crystal material is nematic.

11. A display according to claim 8, wherein said liquid crystal material is cholesteric.

12. A display according to claim 1, wherein plural red, green and blue pixels are formed by using red, green and blue reflectors.

13. A display according to claim 12, wherein said reflectors are holographic reflectors.

14. A display according to claim 12, wherein said reflectors are polymeric cholesteric reflectors.

15. A display according to claim 12, wherein the liquid crystal material is nematic.

16. A display according to claim 12, wherein the liquid crystal material is cholesteric.

17. A display according to claim 1, wherein said reflector is a polymeric cholesteric reflector.

18. A display according to claim 17, wherein said display further includes a dark light absorber optically coupled to said reflector on the side of said reflector away from said light valve.

19. A display according to claim 17, wherein the liquid crystal material is nematic.

20. A display according to claim 17, wherein the liquid crystal material is cholesteric.