Liquid crystal display device

• US 7,245,336 B2
• Filed: 02/03/2006
• Issued: 07/17/2007
• Est. Priority Date: 03/18/1998
• Status: Expired due to Fees

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd.
• Inventors: Kondo, Katsumi, Adachi, Masaya, Hiyama, Ikuo, Tsumura, Makoto, Mori, Yuji, Hirakata, Jun-ichi
• Primary Examiner(s): Ngo; Huyen
• Assistant Examiner(s): QI, ZHI QIANG
• Application Number:
  US11/346,328
• Publication Number:
  US 20060125978A1
• Time in Patent Office: 529 Days
• Field of Search: 349/96, 349/9, 349 61- 65
• US Class Current: 349/96
• CPC Class Codes: G02F 1/133531 characterised by the arrangement of polariser or analyser axes
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133543 Cholesteric polarisers
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

A liquid crystal display device includes an illumination device, a light control element arranged at a projected light side of the illumination device, a reflective polarizer arranged at an upper portion of the light control element so that the transmission axis of polarized light is adjusted, a liquid crystal display element for controlling polarization of projected light projected from the reflective polarizer, and a screen arranged at an upper portion of the liquid crystal display element. The light control element includes an isotropic medium without birefringence.

Claims

1. A liquid crystal display device comprising:

an illumination device,

a light control element arranged at a projected light side of said illumination device,

a reflective polarizer arranged at an upper portion of said light control element so that the transmission axis of polarized light is adjusted so as to increase the transmission rate of the projected light from said illumination device,

a liquid crystal display element for controlling polarization of projected light projected from said reflective polarizer, and

a screen arranged at an upper portion of said liquid crystal display element;

wherein the light control element includes an isotropic medium without birefringence.

2. A liquid crystal display device comprising:

an illumination device;

a light control element arranged at a projected light side of the illumination device;

a reflective polarizer arranged at an upper portion of the light control element so that a polarized light transmission axis of the reflective polarizer is adjusted so as to be substantially perpendicular or substantially parallel to a direction of stripes of the light control element;

a liquid crystal display element for controlling polarization of projected light projected from the reflective polarizer; and

a screen arranged at an upper portion of the liquid crystal display element;

wherein the light control element comprises an isotropic medium having no birefringence, and is the only light control element arranged between the illumination device and the reflective polarizer;

wherein the illumination device includes;

a flat waveguide having a front plane and a rear plane, the front plane of the waveguide constituting a light projecting plane of the waveguide, the rear plane of the waveguide, having numerous depressed planes, protruded planed, or steps, the depressed planes, protruded planes, or steps having respective slightly declined planes;

a light source arranged adjacent to the waveguide; and

a reflector arranged at the rear plane of the waveguide, the reflector either contacting the rear plane of the waveguide directly, or being spaced from the rear plane of the waveguide via an air layer;

wherein the waveguide and the light source are composed so that projected light from the light source is propagated in the waveguide and projected from the light projecting plane of the waveguide; and

wherein the declined planes of the reflector are mirrors.

3. A liquid crystal display device as claimed in claim 2,

wherein the declined planes form stripes on the reflector;

and

wherein the stripes on the reflector are substantially parallel to a major axis direction of a pixel of the liquid crystal display element.

4. A liquid crystal display device according to claim 2, wherein the reflective polarizer is arranged so that the polarized light transmission axis of the reflective polarizer is approximately parallel to a major axis direction of a pixel the liquid crystal display element.

5. A liquid crystal display device according to claim 4,

wherein the reflective polarizer is composed so as to have a light directivity in a minor axis direction of the pixel;

and

wherein the screen is composed so as to broaden projected light in the minor axis direction of the pixel.

6. A liquid crystal display device according to claim 5, wherein the screen is composed so as to absorb external light and to transmit the projected light from the illumination device.

7. A liquid crystal display device according to claim 2, further comprising a birefringent medium arranged between the illumination device and the light control element.

8. A liquid crystal display device according to claim 2, wherein the liquid crystal display element includes:

at least a pair of transparent substrates;

a liquid crystal layer interposed between the pair of transparent substrates; and

a pair of absorption type polarizers arranged so that the pair of transparent substrates are held between the pair of absorption type polarizers.

9. A liquid crystal display device according to claim 8, further comprising a reflective color selective layer corresponding to the pixel of the liquid crystal display element.

10. A liquid crystal display device according to claim 9, wherein the liquid crystal layer, the reflective polarizer, the absorption type polarizers, and the reflective color selective layer are arranged so that a stripe direction of the reflective color selective layer coincides with an axis in a scattering direction of the screen.