Transflective liquid crystal display device having a reflective polarizer

• US 6,008,871 A
• Filed: 01/20/1998
• Issued: 12/28/1999
• Est. Priority Date: 01/20/1997
• Status: Expired due to Term

• Current Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Okumura, Osamu
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Eisenhut, Heidi L.
• Application Number:
  US09/009,530
• Time in Patent Office: 707 Days
• Field of Search: 349/114, 349/162, 349/64, 349/61, 349/113
• US Class Current: 349/61
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one

Abstract

A transflective liquid crystal display device comprising a liquid crystal panel made of liquid crystal compound sandwiched between a pair of opposing substrates having transparent electrodes, a polarizer disposed on the viewer'"'"'s side of said liquid crystal panel, a reflective polarizer disposed on the opposite side of the liquid crystal panel as the polarizer, and a backlight assembly. The reflective polarizer reflects light having a predetermined polarization orientation and transmits light having a different polarization orientation from the predetermined polarization orientation. Also, the backlight assembly is substantially black in a non-emissive state.

Claims

1. A transflective liquid crystal display device comprising:

a liquid crystal panel;

a reflective polarizer disposed on an opposite side as a viewer'"'"'s side of said liquid crystal panel, said reflective polarizer reflecting light having a predetermined polarization orientation and transmitting light having a different polarization orientation from said predetermined polarization orientation; and

a backlight assembly disposed on an opposite side of said reflective polarizer as said liquid crystal panel, said backlight assembly having a luminance factor of 40% or less in a non-emissive state.

2. The liquid crystal display device of claim 1 wherein said backlight assembly includes a member for emitting light in a direction toward said reflective polarizer and a light absorbing body capable of absorbing light incident from a direction of said reflective polarizer.

3. A liquid crystal display device of claim 1 wherein said backlight assembly includes a light source, a light guide for emitting light from said light source in a direction toward said reflective polarizer and a light absorbing body capable of absorbing light incident from a direction of said reflective polarizer.

8. A transflective liquid crystal display device of claim 1, further comprising a polarizer disposed on said viewer'"'"'s side of said liquid crystal panel.

9. A transflective liquid crystal display device of claim 1 wherein said reflective polarizer comprises a birefringent multi-layered dielectric film.

10. A transflective display liquid crystal device of claim 1 wherein said reflective polarizer comprises a cholesteric layer and a quarter wave plate.

11. A transflective display liquid crystal device of claim 1 wherein said backlight assembly comprises an EL element with a light absorbing body disposed on a rear surface thereof.

12. A transflective liquid crystal display device of claim 2 wherein said member comprises a light source and a light guide, and said light absorbing body is disposed on a back surface of said light guide.

13. A transflective liquid crystal display device of claim 12 wherein said light source is a fluorescent tube or LED.

14. A transflective liquid crystal display device of claim 1 wherein an organic LED, a VRD or flat CRT is employed as said backlight assembly.

4. A transflective liquid crystal display device comprising:

a liquid crystal panel including a liquid crystal layer sandwiched between a pair of substrates, said liquid crystal layer being adapted to enable switching between a first state for reflecting a first polarized light component having a predetermined orientation while transmitting a second polarized light component having a different orientation than that of said first polarized light component and a second state for transmitting essentially all light; and

a backlight assembly disposed on a back of said liquid crystal panel, said backlight assembly having a light absorbing capability in a non-emissive state.

5. A transflective liquid crystal display device comprising:

a liquid crystal panel;

a reflective polarizer disposed on an opposite side of said liquid crystal panel as a viewer'"'"'s side, said reflective polarizer reflecting light having a predetermined polarization orientation and transmitting light having a different polarization orientation from said predetermined polarization orientation; and

a backlight assembly having a luminance factor of 40% or less in a non-emissive state disposed on an opposite side of said reflective polarizer as said liquid crystal panel, wherein said liquid crystal panel is capable of emitting light towards the reflective polarizer incident from said viewer'"'"'s side of said liquid crystal panel, and wherein a polarization axis of the light emitted from said liquid crystal panel can be varied corresponding to an ON and OFF state of said backlight assembly so as to make a displayed color in said ON state and a displayed color in said OFF state of the backlight assembly have a complimentary color relationship.

6. A transflective liquid crystal display device of claim 5 wherein the liquid crystal panel is driven by applying voltage to nodes formed on each crossing point of a plurality of data lines and a plurality of scanning lines, and wherein a polarizing axis of light emitted from said liquid crystal panel is varied by changing said voltage applied to said nodes corresponding to an ON and OFF state of said backlight assembly.

7. A transflective liquid crystal display device of claim 6 wherein data signals applied to said data lines are converted so as to change said voltage applied to said nodes corresponding to said ON and OFF state of said backlight assembly.