Stock material or miscellaneous articles – Liquid crystal optical display having layer of specified... – With bonding or intermediate layer of specified composition
Reexamination Certificate
1999-07-01
2001-05-29
Wu, Shean C. (Department: 1756)
Stock material or miscellaneous articles
Liquid crystal optical display having layer of specified...
With bonding or intermediate layer of specified composition
C252S299500, C349S153000, C349S155000, C349S190000
Reexamination Certificate
active
06238754
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device, a color filter substrate used therein and a color filter member.
A liquid crystal display device comprises two electrode substrates each having an alignment film and arranged such that the alignment films of the two substrates face each other and a liquid crystal layer arranged between the two substrates. The two electrode substrates are bonded to each other with a sealing member arranged in the peripheral region of the substrate and an end-sealing material. Also, a granular spacer or a spacer column made of a resin and formed by a photolithography method is arranged between the two substrates for keeping these two substrates a predetermined distance apart from each other. For allowing the liquid crystal display device to perform a color display, colored layers of red (R), green (G) and blue (B) are arranged on one of the substrates and, as desired, a transparent protective layer made of a resin is formed on the substrate having colored layers and a switching element mounted thereto.
In a liquid crystal display device of the particular construction, nonuniformity such as an image sticking and a display unevenness taking place after the durability (reliability) test are derived from the members in direct contact with the liquid crystal layer or the alignment film such as the sealing member, the end-sealing material, the spacer material, the protective layer and the colored layer.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a liquid crystal display device that permits preventing the display unevenness, etc. derived from the members in direct contact with the liquid crystal layer or the alignment film.
Another object is to provide a member of a colored layer of a liquid crystal display device that permits preventing the display unevenness, etc. derived from the members in direct contact with the liquid crystal layer or the alignment film.
In the present invention, total amounts of an alkyl acid, phenyl carboxylic acid, a phenyl carboxylic acid derivative, phenylene dicarboxylic acid, a phenylene dicarboxylic acid derivative, an alkyl amine, aniline, an aniline derivative, phenylene diamine, a phenylene diamine derivative, phenyleneamine carboxylic acid, a phenyleneamine carboxylic acid derivative and an alkyl imide contained in or extracted from the sealing member, the end-sealing material, the spacer, the colored layer, etc. is controlled to fall within a predetermined range so as to prevent alignment unevenness and image sticking.
The alignment unevenness or image sticking is considered to take place by eluation into the liquid crystal or adsorption on the alignment film of organic impurities contained in the sealing member, the end-sealing material, the spacer material, the colored layer, etc. such as an alkyl acid, phenyl carboxylic acid, a phenyl carboxylic acid derivative, phenylene dicarboxylic acid, a phenylene dicarboxylic acid derivative, an alkyl amine, aniline, an aniline derivative, phenylene diamine, a phenylene diamine derivative, phenyleneamine carboxylic acid, a phenyleneamine carboxylic derivatives an alkyl imide, a phthalimide derivative, a cyano benzene derivative, and a dicyano benzene derivative, when the liquid crystal layer is held between the electrode substrates to assemble a liquid crystal display device. In other words, the alignment unevenness or image sticking is considered to take place in the case where the sealing member, the end-sealing material, the spacer material, the colored layer, etc. include a region that is brought into direct contact with the liquid crystal layer or the alignment film. It is considered reasonable to understand that the impurities contained in the sealing member, the end-sealing material, the spacer material, the colored layer, etc. permeate into the liquid crystal layer or the alignment film that are included in the display region so as to bring about eluation of these impurities into the liquid crystal layer and adsorption of these impurities on the alignment film so as to generate the alignment unevenness and image sticking. These impurities have been found to be contained in large amounts in, particularly, the green layer and the black layer included in the colored layers. Pigments G7 and G36 are generally used as parts of the green coloring material and the black coloring material of the color filter included in the liquid crystal display device. The impurities given above are contained in large amounts in these pigments. Further, impurities are contained in large amounts in the dispersant and polymer components used for dispersing these pigments into a colored paste. It is also conceivable that impurities are mixed unexpectedly in the resist preparation step in which the colored paste is mixed and dispersed. Further, the pigments and the dispersant are considered to be decomposed under high temperatures, by contact with an alkali or by exposure to an ultraviolet light, so as to generate the organic impurities noted above. Therefore, the green layer has been found to cause large amounts of impurities to be generated in the liquid crystal layer and the alignment film, compared with the red or blue layer. It is possible to suppress generation of the organic impurities by suitably refining the pigment and dispersant for preparation of a resist used for forming the green layer and by suitably selecting the materials used for the refining.
The present inventors have conducted a simple evaluation test in respect of the influences (particularly, image sticking) given to the display when various organic and inorganic substances are contained in a liquid crystal cell and when the materials used are refined. The experiment was conducted as follows.
Specifically, a TN liquid crystal cell was prepared by coating an alignment film on each of an array substrate having a switching element and a pixel electrode formed on a glass substrate and a counter substrate having a counter electrode formed on a glass substrate, followed by arranging these two substrates to permit the alignment films to face each other with a liquid crystal layer interposed therebetween. Two kinds of alignment film materials and two kinds of liquid crystal materials were used in the experiment, and the image sticking and display unevenness taking place after a durability (reliability) test were evaluated under the conditions that various organic and inorganic substances were attached to the alignment films. Table 1 shows the results.
TABLE 1
Display characteristics
Liquid crystal A
Liquid crystal B
nonuniform image
nonuniform image
sticking
onuniform
sticking
onuniform
Alignment
reliability (display
reliability (display
Attached substance
film
unevenness)
unevenness)
1
phthalic acid
P1
x/x
x/x
2
phthalic acid
P2
x/x
x/x
3
terephthalic acid
P1
x/x
x/x
4
terephthalic acid
P2
x/x
&Dgr;/x
5
para-phthalic acid
P1
x/x
x/x
6
para-phthalic acid
P2
&Dgr;/x
&Dgr;/&Dgr;
7
dichlorophthalic acid
P1
x/x
x/x
8
dichlorophthalic acid
P2
x/x
&Dgr;/x
9
benzoic acid
P1
x/x
&Dgr;/x
10
benzoic acid
P2
x/x
&Dgr;/&Dgr;
11
decanoic acid
P1
x/x
x/x
12
decanoic acid
P2
x/x
&Dgr;/x
13
tetradecanoic acid
P1
x/x
x/x
14
tetradecanoic acid
P2
x/x
&Dgr;/x
15
acetic acid
P1
x/x
&Dgr;/x
16
acetic acid
P2
&Dgr;/x
&Dgr;/&Dgr;
17
oxalic acid
P1
x/x
x/x
18
oxalic acid
P2
&Dgr;/&Dgr;
&Dgr;/&Dgr;
19
hexadecamine
P1
x/x
&Dgr;/&Dgr;
20
hexadecamine
P2
x/x
&Dgr;/&Dgr;
21
aniline
P1
x/x
&Dgr;/&Dgr;
22
aniline
P2
&Dgr;/x
&Dgr;/&Dgr;
23
N-methyl aniline
P1
x/x
&Dgr;/x
24
N-methyl aniline
P2
x/x
&Dgr;/&Dgr;
25
phthalic acid amide
P1
x/x
x/x
26
phthalic acid amide
P2
&Dgr;/&Dgr;
&Dgr;/&Dgr;
27
N-methylamino aniline
P1
x/x
x/x
28
N-methylamino aniline
P2
x/x
&Dgr;/&Dgr;
29
para-chlorobenzoic acid
P1
x/x
&Dgr;/&Dgr;
30
para-chlorobenzoic acid
P2
&Dgr;/x
&Dgr;/&Dgr;
31
table salt
P1
◯/◯
◯/◯
32
hydrochloric acid
P2
◯/◯
◯/◯
33
calcium carbonate
P1
◯/◯
◯/◯
34
phthalic anhydride
P2
◯/◯
◯/◯
3
Akiyoshi Muneharu
Fukuoka Nobuko
Hatoh Hitoshi
Manabe Atsuyuki
Manabe Masumi
Kabushiki Kaisha Toshiba
Pillsbury & Winthrop LLP
Wu Shean C.
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