Liquid crystal display

• US 6,493,054 B2
• Filed: 04/05/2001
• Issued: 12/10/2002
• Est. Priority Date: 04/06/2000
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Advanced Display Technologies
• Inventors: Tamatani, Akira, Nakashima, Ken, Mizunuma, Masaya
• Primary Examiner(s): DUDEK, JAMES A
• Application Number:
  US09/825,953
• Publication Number:
  US 20010038430A1
• Time in Patent Office: 614 Days
• Field of Search: 349/141, 349/128, 349/130, 349/123
• US Class Current: 349/123
• CPC Class Codes: G02F 1/133753 with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]

Abstract

A liquid crystal display of the present invention includes: a pair of substrates, at least one of which is transparent; a liquid crystal layer being interposed between said pair of substrates; electrodes for applying an electric field to liquid crystals molecules in said liquid crystal layer; active switching elements connected with said electrodes; an alignment film being formed on a surface of at least one of said pair of substrates, said surface being contacted with said liquid crystal layer; and an optical device for controlling a transmission of light in cooperation with alignment of said liquid crystal molecules in each pixel, said means being located on at least one said pair of substrates; wherein an aligning direction of each liquid crystal molecule in each pixel is ranged between −2 degrees to +2 degrees with respect to an average aligning direction θ_1c of said liquid crystal layer.

Claims

1. A liquid crystal display comprising:

a pair of substrates, at least one of which is transparent;

a liquid crystal layer interposed between said pair of substrates;

electrodes configured to apply an electric field to liquid crystal molecules in said liquid crystal layer;

active switching elements connected with said electrodes;

an alignment film formed on a surface of at least one of said pair of substrates, said surface contacting said liquid crystal layer; and

an optical device configured to control a transmission of light in cooperation with alignment of said liquid crystal molecules in each pixel, said optical device being located on at least one said pair of substrates;

wherein said alignment film is subjected to a rubbing treatment with a rubbing strength so that an aligning direction in a plane parallel to the substrate of each liquid crystal molecule in each pixel is ranged between −

2 degrees to +2 degrees with respect to an average aligning direction of said liquid crystal layer.

2. The liquid crystal display of claim 1, wherein said alignment film which is formed on at least one of said pair of substrates is made of organic substance and subjected to an alignment treatment by means of a rubbing treatment.

3. The liquid crystal display of claim 2, wherein a rubbing strength L of said rubbing treatment is represented as follows:

4. The liquid crystal display of claim 1, wherein said aligning direction of said each liquid crystal molecule in an interface between one of said pair of substrates and said liquid crystal layer is substantially identical to said aligning direction of said each liquid crystal molecule in an interface between the other one of said pair of substrates and said liquid crystal layer.

5. The liquid crystal display of claim 1, wherein said optical device is a pair of polarizing plates, each of said pair of polarizing plates being arranged outside each of said pair of substrates, an absorption axis of one of said pair of polarizing plates is substantially perpendicular to another absorption axis of the other one of said pair of polarizing plates.

6. The liquid crystal display of claim 5, wherein a direction θ

_p1 of said absorption axis of a polarizing plate of said pair of polarizing plates which is closer to an observer and an average aligning direction θ

_1c of said liquid crystal have a relation of |θ

_1c|−

2°

23 |θ

_p1|≦

|θ

_1c|+3°

, or a direction θ

_p2 of said absorption axis of the other polarizing plate which is more distant from said observer and the average aligning direction θ

_1c of said liquid crystal have a relation of |θ

_1c|−

2°

≦

|θ

_p2|≦

θ

_1c|+3°

.

7. The liquid crystal display of claim 6, wherein said direction θ

_p1, of said absorption axis of a polarizing plate of said pair of polarizing plates which is closer to an observer or said direction θ

_p2 of said absorption axis of the other polarizing plate which is more distant from said observer is substantially equal to said average aligning direction in said liquid crystal layer during black display.

8. A liquid crystal display comprising:

a pair of substrates, at least one of which is transparent;

a liquid crystal layer interposed between said pair of substrates;

electrodes configured to apply an electric field to liquid crystal molecules in said liquid crystal layer, said electrodes being formed on said pair of substrates and arranged along a longitudinal direction;

active switching elements connected with said electrodes;

an alignment film formed on a surface of at least one of said pair of substrates, said surface contacting said liquid crystal layer; and

an optical device configured to control a transmission of light in cooperation with alignment of said liquid crystal molecules in each pixel, said optical device being located on at least one said pair of substrates,

wherein an aligning direction in a plane parallel to the substrate of each liquid crystal molecule in each pixel is ranged between −

2 degrees to +2 degrees with respect to an average aligning direction θ

_1c of said liquid crystal layer,

an angle between a rubbing direction of said alignment film and said longitudinal direction of said electrodes is between 0°

C. and 40°

C.,

said alignment film which is formed on at least one of said pair of substrates is made of organic substance and subjected to an alignment treatment by way of a rubbing treatment, and

a rubbing strength L of said rubbing treatment is represented as follows;