Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-12-08
2003-06-03
Dudek, James (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
Reexamination Certificate
active
06573967
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a structure of seal materials to seal liquid crystal material injected between a facing electrode substrate carrying a facing electrode and a drive circuit substrate carrying a drive circuit of a liquid crystal display apparatus, and further relates to a method for fabricating a liquid crystal display apparatus having such structure of the seal materials.
2. Description of the Related Art
In a liquid crystal display apparatus, a drive circuit substrate carrying TFT (Thin Film Transistor) devices for driving liquid crystal material and a facing electrode substrate carrying a facing electrode to be faced to each of the TFT devices are piled together with a spacer and seal materials. The liquid crystal material is then injected in a space between the above mentioned drive circuit substrate and facing electrode substrate through an injection gate provided at one portion of the seal materials.
FIG. 3A
is a plan view for showing a seal structure employed in a conventional liquid crystal display apparatus and
FIG. 3B
is a sectional view taken along a line IIIB—IIIB of the conventional liquid crystal display apparatus depicted in FIG.
3
A.
In a following discussion, a direction of an arrow &agr; is called an upper side, an opposite direction thereof is called a lower side, a direction of an arrow &bgr; is called a left side and an opposite side thereof is called a right side.
As shown in
FIG. 3A
, a rectangular effective picture element area
12
is positioned at a central part of a rectangular facing electrode substrate
10
and a plurality of facing electrodes and an orientation film are provided (not shown in the figure) on this facing electrode substrate
10
within this effective picture element area
12
. Seal materials
14
are arranged at peripheries of this effective picture element area
12
. These seal materials
14
are formed in a rectangular shape along peripheries of the effective picture element area
12
like a rectangular picture frame.
These seal materials
14
are formed almost all peripheries of the effective picture element area
12
except a portion of an injection gate
16
for injecting the liquid crystal material. In addition, the injection gate
16
is to be sealed from outside by a sealant
20
after injection of the liquid crystal material into a space between the facing electrode substrate
10
and a drive circuit substrate
1
.
In addition, an electrode portion
18
to connect this liquid crystal display apparatus to an outside circuit by a connector (not shown in the figure) is provided on the upper side of the drive circuit substrate
1
.
Then the facing electrode substrate
10
is piled on the drive circuit substrate
1
with afore-mentioned predetermined space by way of the above mentioned seal materials
14
and a plurality of spacers supported by the seal materials
14
, in which each of the spacers may be a small ball. Both the facing electrode substrate
10
and the drive circuit substrate
1
are joined together by hardening of the seal materials
14
.
By the way, spaces between the effective picture element area
12
and the seal materials
14
surrounding peripheries of the effective picture element area
12
is not uniform in the conventional liquid crystal display apparatus.
In other words, in
FIG. 3A
, a space between an upper side periphery of the effective picture element area
12
and an upper side of the seal materials
14
is defined as A′ and a space between a left or right side periphery of the effective picture element area
12
and a left or right side of the seal materials
14
is defined as B′. In this case, the space A′ and the space B′ are not equal and in
FIG. 3A
, the space A′ is larger than the space B′ (A′>B′). This is because wiring for the above described electrode portion
18
and a peripheral circuit portion for driving TFT devices are concentrated near the upper side of the drive circuit substrate
1
. These TFT devices are mounted on the drive circuit substrate
1
.
However, when the space between the effective picture element area
12
and the seal materials
14
shows non-uniform, uniformity of the space between the facing electrode substrate
10
and the drive circuit substrate
1
in the effective picture element area
12
is deteriorated in case of jointing both facing electrode substrate
10
and the drive circuit substrate
1
.
In addition, in the conventional seal materials of the liquid crystal display apparatus, a portion of the seal materials are removed at the injection gate
16
for injecting liquid crystal material and this removed portion also causes the non-uniformity of the space between the facing electrode substrate
10
and the drive circuit substrate
1
in the effective picture element area
12
.
Quality of the liquid crystal display apparatus is deteriorated by this non-uniformity of the space between the facing electrode substrate
10
and the drive circuit substrate
1
in the effective picture element area
12
.
FIG. 4
is an illustration showing the condition where an interference fringe is observed by irradiation of a sodium vapor lamp to the conventional liquid crystal display apparatus that has non-uniform space between the facing electrode substrate
10
and the drive circuit substrate
1
.
As shown in
FIG. 4
, an interference fringe
24
is observed with curved form along peripheries of the effective picture element area
12
. And further the interference fringe
24
is invaded even into the effective picture element area
12
, so that it is understood that the space between the facing electrode substrate
10
and the drive circuit substrate
1
is not uniform.
In order to correct the non-uniformity of the space between the facing electrode substrate
10
and the drive circuit substrate
1
, the space between the outer periphery of the effective picture element area
12
and the inner periphery of the seal materials
14
is set to be uniform by enlarging partially the width of the seal materials
14
. But in this case, it is probable to occur a disorder of the orientation between the seal materials and the liquid crystal material, so that there is a problem that the facing electrode substrate
10
and the drive circuit substrate
1
have to be put on one another with increased pressure.
In addition, another spacer is may be provided in the effective picture element area
12
at the facing electrode substrate
10
and the drive circuit substrate
1
, but in the case where the additional spacer is formed by a TFT fabrication processing at boundaries of the picture element of the drive circuit substrate
1
, it becomes more difficult to correct the non-uniformity of the space between the facing electrode substrate
10
and the drive circuit substrate
1
because of the strength of the liquid crystal display apparatus.
SUMMARY OF THE INVENTION
A primary object of the present invention is to present a liquid crystal display apparatus having a new structure of seal materials which can improve an uniformity of a space between a drive circuit substrate and a facing electrode substrate in an effective picture element area and a method for fabricating such liquid crystal display apparatus.
In order to achieve the above object, a liquid crystal display apparatus of a type having a drive substrate and a facing electrode substrate superimposed and joined each other via spacer and seal material is disclosed. The drive substrate carries drive devices for driving liquid crystal material, the facing electrode substrate carries facing electrodes facing to the drive devices, and the liquid crystal material is injected between the drive substrate and the facing electrode substrate, wherein the seal material includes an outer seal formed along outer peripheries of the drive substrate and the facing electrode substrate and an inner seal formed inside of the outer seal, and a space between the out side portion of an effective picture element area constituting drive device
Fukumori Hiromi
Fukumoto Hirohide
Shima Syuichi
Taniguchi Kouichi
Depke Robert J.
Dudek James
Holland & Knight LLC
Sony Corporation
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