LIQUID CRYSTAL PANEL, LIQUID CRYSTAL DISPLAY DEVICE AND TERMINAL DEVICE

• US 20070222927A1
• Filed: 03/22/2007
• Published: 09/27/2007
• Est. Priority Date: 03/27/2006
• Status: Active Grant

• Current Assignee: NLT Technologies, Ltd. (Tianma Microelectronics Company Limited)
• Original Assignee: NEC Corporation, NEC LCD Technologies Limited (Tianma Microelectronics Company Limited)
• Inventors: UEHARA, Shinichi, MATSUSHIMA, Jin, SUMIYOSHI, Ken
• Granted Patent: US 8,134,663 B2
• Time in Patent Office: Days
• US Class Current: 349/117
• CPC Class Codes: G02F 1/133541 Circular polarisers
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133634 the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
• CPC Class Codes: G02F 1/133636 with twisted orientation, e.g. comprising helically oriented LC-molecules or a plurality of twisted birefringent sublayers
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/134372 for fringe field switching [FFS] where the common electrode is not patterned
• CPC Class Codes: G02F 2413/13 Positive birefingence
• CPC Class Codes: G02F 2413/14 Negative birefingence

Abstract

To provide a liquid crystal panel capable of realizing excellent display performance using a circular polarizing plate therein, and a liquid crystal display device and a terminal device using the same, with respect to a semi-transmission type liquid crystal display device in a horizontal electric field mode (In-Plane Switching: IPS).

A viewer-side circular polarizing plate and a backside circular polarizing plate are disposed outside of a viewer-side substrate and a backside substrate respectively, and a viewer-side compensation plate and a backside compensation plate are disposed between the respective polarizing plates and substrates to reduce a refractive index anisotropy of a liquid crystal layer.

Claims

1. A liquid crystal panel comprising a backside substrate, a viewer-side substrate, and a liquid crystal layer in between those two substrates, where a pixel area is configured with a reflective display area in which a light from a viewer-side is reflected, and a transmissive display area in which a light from a backside is transmitted, and where a liquid crystal layer at least in a transmissive display area is driven by a horizontal electric field with an applied voltage parallel to a substrate surface, wherein

the liquid crystal layer has a refractive index anisotropy in a display surface thereof,

the liquid crystal panel further comprising:

circular polarizing plates individually disposed outside of the backside substrate and the viewer-side substrate respectively; and

a compensator disposed in at least either one of intervals between the circular polarizing plates and the liquid crystal layer for reducing the refractive index anisotropy of the liquid crystal layer.

2. The liquid crystal panel, as claimed in claim 1, wherein the compensator is a compensation plate, and the compensation plates are disposed individually between the respective substrates and the circular polarizing plates, those two compensation plates reduce a refractive index anisotropy of the liquid crystal layer in the transmissive display area, and one of those two compensation plates reduces a refractive index anisotropy of the liquid crystal layer in the reflective display area.

3. The liquid crystal display panel, as claimed in claim 2, wherein thickness of the liquid crystal layer is different between the reflective display area and the transmissive display area.

4. The liquid crystal panel, as claimed in claim 2, wherein the two compensation plates have equivalent characteristics.

5. The liquid crystal panel, as claimed in claim 1, wherein the compensator is a compensation plate, and the compensation plate is disposed in either intervals of the respective substrates and the circular polarizing plates, and the one compensation plate reduces a refractive index anisotropy of the liquid crystal layer in the reflective display area and a refractive index anisotropy of the liquid crystal layer in the transmissive display area.

6. The liquid crystal panel, as claimed in claim 5, wherein the compensation plate is set in a value with which the refractive index anisotropy of the liquid crystal layer in the transmissive display area is counteracted so that the liquid crystal layer has isotropy.

7. The liquid crystal panel, as claimed in claim 5, wherein thickness of the liquid crystal layer is even between the reflective display area and the transmissive display area.

8. The liquid crystal panel, as claimed in claim 1, wherein intensity of an electric field for driving the liquid crystal layer is weaker in the reflective display area than in the transmissive display area.

9. The liquid crystal panel, as claimed in claim 1, wherein an interval between electrodes generating a horizontal electric field in the reflective display area is wider than an interval of electrodes generating a horizontal electric field in the transmissive display area.

10. The liquid crystal panel, as claimed in claim 1, wherein the liquid crystal layer is parallel-aligned, and the compensator is a compensation plate, and the compensation plate uses a negative A plate of retardation film therefor, in which a direction of an extraordinary refractive index of the negative A plate is set in a direction in which refractive index anisotropy of the liquid crystal layer under no voltage application is maximum.

11. The liquid crystal panel, as claimed in claim 1, wherein the liquid crystal layer is parallel-aligned, and the compensator is a compensation plate, and the compensation plate uses a biaxial retardation film therfor, and between an A axis and a B axis of the biaxial retardation film, the axis having a smaller refractive index anisotropy is set in a direction in which refractive index anisotropy of the liquid crystal layer under no voltage application is maximum.

12. The liquid crystal panel, as claimed in claim 1, wherein the liquid crystal layer is twist-aligned, the compensator is a compensation plate, and the compensation plate uses a twisted-nematic retardation plate therefor.

13. The liquid crystal panel, as claimed in claim 12, wherein an orientation direction of liquid crystal molecules near the viewer-side substrate and an orientation direction of liquid crystal molecules near the backside substrate in the liquid crystal layer are arranged in line symmetry centering a perpendicular line to an electric field direction in the display surface.

14. The liquid crystal panel, as claimed in claim 1, wherein the compensator is a compensation layer, and the compensation layer is arranged at least in either one of areas between the liquid crystal layer and each of the substrates.

15. The liquid crystal panel, as claimed in claim 1, wherein the compensator is a polymer network compensation layer, and the polymer network compensation layer is arranged between the substrates.

16. The liquid crystal panel, as claimed in claim 1, wherein:

electrodes for generating a horizontal electric field are a parallel electrode pair;

a width of the electrodes is smaller than a thickness of the liquid crystal layer;

orientation of liquid crystal molecules between the electrodes is changed by the electric field generated by the parallel electrode pair;

orientation of liquid crystal molecules on the electrodes is changed like the liquid crystal molecules between the electrodes by conforming to the change in the orientation; and

director direction of the liquid crystal molecules on the electrodes is a direction different from a direction of the electric field on the electrodes.

17. The liquid crystal panel, as claimed in claim 1, comprising a pixel magnifying device for optically magnifying the pixel.

18. A liquid crystal display device comprising the liquid crystal panel as claimed in claim 1, for a display unit.

19. A terminal device comprising the liquid crystal display device as claimed in claim 18.

20. The terminal device, as claimed in claim 19, is a portable telephone, a personal digital assistant, a game machine, a digital camera, a camcorder, a videoplayer, a laptop computer, a cash dispenser, or a vending machine.