Liquid crystal display having backscattering polarizer

• US 6,215,537 B1
• Filed: 04/08/1999
• Issued: 04/10/2001
• Est. Priority Date: 11/12/1998
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Iwata, Shuji, Oda, Kyoichiro, Tsumura, Akira, Matsukawa, Fumio
• Primary Examiner(s): Ton, Toan
• Application Number:
  US09/288,514
• Time in Patent Office: 733 Days
• Field of Search: 349/96, 349/98, 349/64, 349/115, 349/9, 349/95
• US Class Current: 349/98
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 2203/03 scattering

Abstract

A liquid crystal display includes: a scattering-polarizer provided between a liquid crystal and a back light for transmitting a polarization component in one direction of light from back light, but scattering and reflecting a polarization component in a direction which is orthogonal thereto: and a scattered light reflector reflecting the reflected and scattered light toward scattering-polarizer along with the polarization component in above mentioned one direction. Thus, a liquid crystal display which is inexpensive and has high display quality with reduced power consumption is obtained.

Claims

1. A liquid crystal display allowing display of a liquid crystal from a front of said liquid crystal by transmitting light emitted from a back light provided behind said liquid crystal through said liquid crystal, comprising:

a scattering-polarizer provided between said back light and said liquid crystal for transmitting a polarization component in one direction of light from said back light and reflecting with scattering a polarization component in a direction orthogonal to said one direction in a direction which is opposite to a travelling direction of light; and

a scattered light reflector reflecting said reflected and scattered light toward said scattering-polarizer including said polarization component in said one direction;

the side of said liquid crystal facing said scattering-polarizer being exposed to said scattering-polarizer such that light passing from said scattering-polarizer to said liquid crystal and polarized by said scattering-polarizer is not subject to further polarization prior to reaching the liquid crystal.

2. The liquid crystal display according to claim 1, wherein said back light includes a fluorescent tube emitting light and a reflector reflecting light and directing the reflected light toward said scattering-polarizer, and

said reflector functions as said scattered light reflector.

3. The liquid crystal display according to claim 1, further comprising a lens sheet provided between said scattering-polarizer and said scattered light reflector for refracting and transmitting said light transmitted with scattering from said scattering-polarizer and collecting it onto said scattered light reflector.

4. The liquid crystal display according to claim 3, further comprising a scattering-controlling-film provided between said scattering-polarizer and said lens sheet for transmitting light having a relatively small angle of incidence of light reflected with scattering from said scattering-polarizer as it is and transmitting with scattering diagonally directed light having a relatively large angle of incidence,

said lens sheet refracting and transmitting said transmitted and scattered light diagonally directed from said scattering-controlling-film and collecting it onto said scattered light reflector.

5. The liquid crystal display according to claim 3, further comprising a scattering-controlling-film provided between said lens sheet and said scattered light reflector for transmitting with scattering light having a relatively small angle of incidence of light reflected with scattering by said scattering-polarizer and transmitted through said lens sheet, and for transmitting diagonally directed light having a relatively large angle of incidence as it is.

6. The liquid crystal display according to claim 1, further comprising a scattering-controlling-film provided between said scattering-polarizer and said scattered light reflector for transmitting light reflected with scattering by said scattering-polarizer while changing an angle of scattering in accordance with an angle of incidence.

7. The liquid crystal display according to claim 1, wherein said transmission of polarization component in said one direction through said scattering-polarizer is performed with a small amount of scattering.