Illumination device and/or a liquid crystal display device

• US 20020176164A1
• Filed: 02/08/2002
• Published: 11/28/2002
• Est. Priority Date: 04/03/2001
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Takahashi, Naoki, Motomura, Hironori
• Granted Patent: US 6,724,446 B2
• Time in Patent Office: Days
• US Class Current: 359/487
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence

Abstract

There is provided an illuminator having a planar light source unit having reflectance of from 50 to 90% with respect to light in a state in which the light is emitted from a light source provided separately from the planar light source and incident on the planar light source unit, and a reflective type polarizer disposed on a light exit side of the planar light source unit so that a reflected light component and a transmitted light component of polarized light can be obtained from natural light incident on the reflective type polarizer. There is provided a liquid-crystal display device having an illuminator defined above, and a liquid-crystal display panel disposed on an upper side of the reflective type polarizer in the illuminator.

Claims

1. An illuminator comprising:

a planar light source unit having reflectance of from 50 to 90% a with respect to light in a state in which the light is emitted from a light source provided separately from the planar light source and incident on said planar light source unit; and

a reflective type polarizer disposed on a light exit side of said planar light source unit so that a reflected light component and a transmitted light component of polarized light can be obtained from natural light incident on said reflective type polarizer.

2. An illuminator according to claim 1, wherein the reflectance of said planar light source unit is selected to be not lower than 70% whereas the polarized light reflectance of said reflective type polarizer is selected to be not lower than 40%.

3. An illuminator according to claim 1, wherein said reflective type polarizer is one of a linearly polarized light separating sheet and a circularly polarized light separating sheet, said linearly polarized light separating sheet being made of a multilayer laminate of at least two kinds of materials different in refractive index, said circularly polarized light separating sheet being made of cholesteric liquid-crystal layers.

4. An illuminator according to claim 1, wherein said reflective type polarizer is one of a reflective type polarizer having a light-diffusing layer on its light exit side and a reflective type polarizer diffusing transmitted light.

5. A liquid-crystal display device comprising an illuminator according to claim 1, and a liquid-crystal display panel disposed on an upper side of said reflective type polarizer in said illuminator.