LIQUID CRYSTAL DISPLAY DEVICE

• US 20110221984A1
• Filed: 02/16/2011
• Published: 09/15/2011
• Est. Priority Date: 03/09/2010
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: MATSUMORI, Masaki, Tomioka, Yasushi
• Granted Patent: US 8,580,357 B2
• Time in Patent Office: Days
• US Class Current: 349/33
• CPC Class Codes: C09K 19/56 Aligning agents
• CPC Class Codes: C09K 2323/027 Polyimide
• CPC Class Codes: G02F 1/133723 Polyimide, polyamide-imide
• CPC Class Codes: G02F 1/133738 for homogeneous alignment
• 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 1/134372 for fringe field switching [FFS] where the common electrode is not patterned

Abstract

A liquid crystal display device includes: a pair of substrates, at least one of which is transparent; a liquid crystal layer placed between the pair of substrates; an electrode group, formed on at least one of the pair of substrates, for applying an electric field to the liquid crystal layer; and an alignment control film placed on at least one of the pair of substrates, in which the alignment control film is formed of polyimide and a precursor of the polyimide, each of the polyimide and the precursor of the polyimide contains, as a material, a specific cyclobutanetetracarboxylic acid dianhydride derivative and aromatic diamine, and the alignment control film is provided with alignment capability by photo-alignment treatment.

Claims

1. A liquid crystal display device, comprising:

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

a liquid crystal layer placed between the pair of substrates;

an electrode group, formed on at least one of the pair of substrates, for applying an electric field to the liquid crystal layer; and

an alignment control film placed on at least one of the pair of substrates,

wherein the alignment control film is formed of polyimide and a precursor of the polyimide,

each of the polyimide and the precursor of the polyimide contains, as a material, a cyclobutanetetracarboxylic acid dianhydride derivative represented by the following chemical formula (1) and aromatic diamine, and

the alignment control film is provided with alignment capability by photo-alignment treatment;

2. The liquid crystal display device according to claim 1, wherein the aromatic diamine contains at least one kind of aromatic diamines selected from a compound group represented by the following chemical formulae (101) to (110):

3. The liquid crystal display device according to claim 2, wherein the aromatic diamine contains at least two different kinds of aromatic diamines selected from a compound group represented by the following chemical formulae (101) to (110).

4. The liquid crystal display device according to claim 1, wherein a tetracarboxylic acid dianhydride used as a material for the polyimide and the precursor of the polyimide contains the cyclobutanetetracarboxylic acid dianhydride derivative represented by the chemical formula (1) in a ratio of 70 mol % to 100 mol %.

5. The liquid crystal display device according to claim 1, wherein each of the polyimide and the precursor of the polyimide further contains, as a material, the cyclobutanetetracarboxylic acid dianhydride derivative represented by the following chemical formula (2):

6. The liquid crystal display device according to claim 1, wherein the precursor of the polyimide contains a polyamide acid alkyl ester having an alkyl group of a carbon number of 1 to 4.

7. The liquid crystal display device according to claim 1, wherein the electrode group is formed on only any one of the pair of substrates.

8. The liquid crystal display device according to claim 1, wherein a pretilt angle of the liquid crystal layer is 1 degree or less.

9. The liquid crystal display device according to claim 1, wherein at least two of Z¹ to Z⁴ in the chemical formula (1) are substituents each represented by —

NR₂, —

SR, —

OH, —

COR, —

(CH₂)_n—

COOR, —

CN, or —

NO₂ (R'"'"'s each independently represent a hydrogen atom or an alkyl group having a carbon number of 1 to 4, and n represents an integer of 0 to

     2), and the others are hydrogen atoms.

10. The liquid crystal display device according to claim 1, wherein each of the polyimide and the precursor of the polyimide contains, as a material, at least two kinds of the cyclobutanetetracarboxylic acid dianhydride derivatives each represented by the chemical formula (1) and having different number of substituents.