Active matrix type liquid crystal display apparatus

• US 20070178250A1
• Filed: 02/21/2007
• Published: 08/02/2007
• Est. Priority Date: 05/16/1997
• Status: Active Grant

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Inventors: Kondo, Katsumi, Tomioka, Yasushi, Miwa, Takao, Yokokura, Hisao
• Granted Patent: US 7,790,248 B2
• Time in Patent Office: Days
• US Class Current: 428/1.260
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/02 Alignment layer characterised by chemical composition
• CPC Class Codes: C09K 2323/025 Polyamide
• CPC Class Codes: C09K 2323/027 Polyimide
• CPC Class Codes: G02F 1/133397 for suppressing after-image or image-sticking
• CPC Class Codes: G02F 1/1337 Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
• CPC Class Codes: G02F 1/133784 by rubbing
• CPC Class Codes: G02F 1/133788 by light irradiation, e.g. linearly polarised light photo-polymerisation
• 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 2202/023 curable

Abstract

An active matrix type liquid crystal display apparatus has a pair of substrates, at least one of the substrates being transparent; a liquid crystal layer arranged between the pair of substrates; and electrode structure for generating an electric field having a dominant component parallel to a surface of the substrate and passing through the liquid crystal layer, the electrode structure being formed on one of the pair of substrates; a pair of alignment layers formed on respective surfaces in contact with the liquid crystal layer of the pair of substrates; and a pair of polarizing plates arranged so as to sandwich the pair of substrates, wherein the glass transition temperature Tg of a boundary surface between said liquid crystal layer and the alignment layer is higher than the nematic-isotropic phase transition temperature T(N-I) of a liquid crystal composite forming the liquid crystal layer.

Claims

1. An active matrix type liquid crystal display apparatus having a plurality of thin film transistors, comprising:

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

a liquid crystal layer arranged between the pair of substrates;

an alignment layer arranged between the liquid crystal layer and one of the pair of substrates; and

a pair of polarizing plates arranged on the opposite sides of the pair of substrates to the liquid crystal layer;

wherein

the alignment layer is photoreactive and made of one of polyimide and polyamic acid including 1,2,3,4-cyclobutane-tetracarbonic acid.

2. An active matrix type liquid crystal display apparatus according to claim 1, wherein the relation 0.2 μ

m<

Δ

n·

d<

0.5 μ

m is satisfied, where Δ

n is an anisotropy of refractive index of the liquid crystal layer and d is a thickness of the liquid crystal layer.

3. An active matrix type liquid crystal display apparatus according to claim 1, wherein the alignment layer is made of an organic polymer of polyimide group.

4. An active matrix type liquid crystal display apparatus according to claim 3, wherein a weight average molecular weight of the organic polymer is not smaller than 10,000 and not larger than 300,000.

5. An active matrix type liquid crystal display apparatus according to claim 3, wherein a ration of weight average molecular weight/number average molecular weight is not larger than 2.

6. An active matrix type liquid crystal display apparatus according to claim 3, wherein the organic polymer contains one of a polymer precursor and a polymer curable by being subjected to irradiation treatment of at least one of heat, light and radiation rays.

7. An active matrix type liquid crystal display apparatus according to claim 6, wherein the one of a polymer precursor and a polymer has any one of ethylene group, acetylene group, diacetylene group and maleimide group.

8. An active matrix type liquid crystal display apparatus according to claim 1, which further comprises a transparent organic polymer arranged between the alignment layer and the one of the substrates, the transparent organic polymer being thicker in thickness than the alignment layer.

9. An active matrix type liquid crystal display apparatus according to claim 1, wherein a glass transition temperature Tg of the alignment layer is not lower than 300°

C.