Liquid crystal panel having tilted liquid crystal molecules and liquid crystal display using the liquid crystal panel

• US 6,507,381 B1
• Filed: 05/15/1998
• Issued: 01/14/2003
• Est. Priority Date: 05/26/1997
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Shimada, Shinji, Ogishima, Kiyoshi, Takafuji, Yutaka, Katsuya, Yoko
• Primary Examiner(s): Parker, Kenneth
• Application Number:
  US09/079,285
• Time in Patent Office: 1,705 Days
• Field of Search: 349/178, 349/136, 349/123, 349/37, 349/13.D, 345/96, 345/87
• US Class Current: 349/130
• CPC Class Codes: G02F 1/1337 Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
• CPC Class Codes: G02F 1/13373 Disclination line; Reverse tilt
• CPC Class Codes: G02F 1/133742 for homeotropic alignment
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general

Abstract

A liquid crystal layer, made of a liquid crystal material having a negative dielectric anisotropy, is sealed between an opposing substrate and a pixel substrate that are arranged face to face with each other; thus, a liquid crystal panel of the birefringence control type is constructed. In this liquid crystal panel, the liquid crystal molecules, provided as the liquid crystal material, are kept in an oriented state in which they incline by an angle in the range of 3° to 10° with respect to the direction that is normal to the opposing substrate and the pixel substrate. Upon application of a driving voltage to the liquid crystal layer, since the pretilt angle, which is the initial angle of inclination of the liquid crystal molecules, is set at a value greater than that of a conventional apparatus, the occurrence of reverse tilt regions can be suppressed. Thus, the disclination line, which is formed by the effect of electric potentials exerted between the adjacent pixels, is shifted toward the edge of the pixel. The shift of the disclination line suppresses the occurrence of disclination in a wider region, thereby increasing the effective reflectance of the pixels.

Claims

1. A liquid crystal panel comprising:

a pixel substrate having scanning lines extending in a first direction, signal lines extending in a second direction crossing said scanning lines, switching elements, pixel electrodes arranged in a matrix forming rows in the first direction and columns in the second direction, and an alignment film, wherein each of the pixel electrodes is connected to a corresponding one of said scanning lines and a corresponding one of said signal lines through a corresponding one of said switching elements;

an opposing substrate having an electrode layer and an alignment film;

a liquid crystal layer sealed between said pixel substrate and said opposing substrate; and

a driving system for driving said scanning lines and said signal lines,

wherein the molecules of the liquid crystal layer have a negative dielectric anisotropy and incline with a pretilt angle in a range of 3°

to 10°

with respect to the direction which is normal to said pixel substrate or said opposing substrate,

wherein the alignment direction of the alignment films of said pixel substrate and said opposing substrate is at an angle of about 45°

with respect to the first direction, and

wherein said driving system drives said scanning lines and said signal lines such that adjacent groups of two or more adjacent pixels at least in a row direction are supplied with driving voltages of opposite polarity.

2. A liquid crystal display device comprising one or more liquid crystal display panels in accordance with claim 1.

3. The liquid crystal panel as defined in claim 1, wherein said driving system drives the scanning lines and data lines such that adjacent groups of two or more adjacent pixels in a row direction are supplied with driving voltages of opposite polarity and adjacent groups of two or more adjacent pixels in a column direction are supplied with driving voltages of opposite polarity.