Optical display including a cholesteric layer, a display device and a diffusing layer on an exit side of the cholesteric layer

• US 7,030,949 B2
• Filed: 05/29/2002
• Issued: 04/18/2006
• Est. Priority Date: 06/01/2001
• Status: Expired due to Fees

• Current Assignee: Dai Nippon Printing Company Limited
• Original Assignee: Dai Nippon Printing Company Limited
• Inventors: Kashima, Keiji
• Primary Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US10/156,770
• Publication Number:
  US 20020180915A1
• Time in Patent Office: 1,420 Days
• Field of Search: 349/112, 349/115, 349/98, 349/106, 349/175, 349/176
• US Class Current: 349/115
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal

Abstract

A wavelength-selecting optical element includes a cholesteric layer that reflects or transmits either of a right-handed circularly polarized light component and a left-handed circularly polarized light component in a selected wavelength band of an incident light; and a diffusing layer disposed on the exit side of the cholesteric layer to diffuse the circularly polarized light component reflected or transmitted by the cholesteric layer. The cholesteric layer may be a color filter having a red, a green and a blue pixel region for each of pixels. Each of the pixel regions reflects or transmits either of a right-handed circularly polarized light component and a left-handed circularly polarized light component in a selected wavelength band of an incident light.

Claims

1. An optical display comprising:

a display device adapted to display an image by modulating light;

a cholesteric layer disposed on an optical path for the light that penetrates the display device, the cholesteric layer being adapted to reflect or transmit either of a right-handed circularly polarized light component and a left-handed circularly polarized light component in a selected wavelength band of the light, the cholesteric layer being a hardened layer having cholesteric regularity and formed of a material selected from the group consisting of a hardened polymerizable monomer, a hardened polymerizable oligomer, and a liquid crystal polymer; and

a diffusing layer disposed on an exit side of the cholesteric layer to diffuse the circularly polarized light component reflected or transmitted by the cholesteric layer.

2. The optical display according to claim 1, wherein the display device is a liquid crystal display device.

3. The optical display according to claim 1, wherein the cholesteric layer is a color filter including red, green and blue pixel regions.

4. The optical display according to claim 1, wherein the diffusing layer is formed of a transparent resin containing a diffusing agent of fine particles of an organic or inorganic material.

5. The optical display according to claim 4, wherein a difference in refractive index between the transparent resin and the diffusing agent is in a range of 0.02 to 1.0.

6. The optical display according to claim 4, wherein the diffusing agent has a particle size in a range of 5 nm to 50 μ

m.

7. The optical display according to claim 1, wherein a surface of the diffusing layer has a haze with respect to a direction normal to the surface in a range of 3 to 85.

8. The optical display according to claim 7, wherein a difference between a haze of the surface of the diffusing layer with respect to a direction normal to the surface and a haze of the surface of the diffusing layer with respect to oblique directions at ±

60°

to the normal to the surface is in a range of 0.1 to 7.

9. The optical display according to claim 1, wherein a surface of the diffusing layer has a surface roughness Ra of 2 μ

m or below.

10. The optical display according to claim 9, wherein the surface of the diffusing layer has a surface roughness Ra of 0.3 μ

m or below.