Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-10-22
2004-05-25
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S073000, C349S155000, C349S187000, C349S189000
Reexamination Certificate
active
06741317
ABSTRACT:
This application claims the benefit of Korean Patent Application No. 61968/2000, filed in Korea on Oct. 20, 2000, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device and a liquid crystal injection method in which a polymer wall is placed in the inside of a large panel and liquid crystal injection openings are formed on each of smaller panels created by a polymer wall, in order to simultaneously inject a liquid crystal in each opening.
2. Discussion of the Related Art
As shown in
FIG. 1
, a liquid crystal display device comprises a color filter substrate
10
and a thin film transistor (TFT) substrate
20
, which are positioned parallel to each other at the top and bottom, respectively, of the liquid crystal display device. A sealed liquid cell that contains the liquid crystal surrounds the substrate
10
. The liquid crystal display, using a property of liquid crystal having dielectric anisotropy, exhibits characters, numbers, and other optional designs. Such an arrangement has been widely used for display panel sections of electronic equipment such as watches.
The color filter substrate
10
includes a transparent substrate
11
, a color filter layer
12
and a black matrix (BM) film
13
formed on the inside of the transparent substrate
11
. Furthermore, a common electrode
14
made of ITO material is formed abutting the color filter layer
12
and the BM film
13
.
The TFT substrate
20
comprises a plurality of gate bus lines
22
and data bus lines
23
formed on the inside of a lower transparent substrate
21
. A plurality of switching elements shown as TFTs
24
are positioned close to the intersections of the gate bus lines
22
and the data bus lines
23
. A plurality of square-shaped pixel electrodes
25
are surrounded by the gate bus lines
22
and the data bus lines
23
and are connected to the drain electrodes of the TFTs
24
.
Well-known liquid crystal injection methods of a liquid crystal display include an injection method using a capillary effect and an induction method using a vacuum.
As an example of injection methods, a DIP method in which liquid crystal is injected inside of a panel using a capillary effect is shown in FIG.
2
. Referring to
FIG. 2
, the DIP method comprises a first process of generating a vacuum in a vacuum chamber
1
; a second process of pressing a liquid crystal
1
b
of a liquid crystal container (LC container)
1
c
in the vacuum chamber
1
to an injection opening (not shown) of a liquid crystal
1
a
cell, after the vacuum is generated in the vacuum chamber
1
; a third process of injecting the liquid crystal
1
b
of the LC container
1
c
in the liquid crystal cell
1
a
by a capillary effect; the pressure difference between the inside of the liquid crystal cell
1
a
and that of the vacuum chamber
1
causes the pressure of the vacuum chamber
1
to increase to atmospheric pressure; and, a fourth process of separating the LC container
1
c
when all of the liquid crystal
1
b
is injected into the liquid crystal cell
1
a.
In other words, according to the liquid crystal injection method described above, a vacuum is generated in the vacuum chamber
1
, and a guidance section of the LC container
1
c
on the inside of the vacuum chamber
1
and an injection opening of the liquid crystal cell
1
a
are joined by applying a certain degree of pressure.
When the liquid crystal of the LC container
1
c
and the injection opening of the liquid crystal cell
1
a
are combined, the liquid crystal
1
b
of the LC container
1
c
is injected inside of the liquid crystal cell
1
a
by a capillary effect and by the pressure difference between the inside of the liquid crystal cell
1
a
and the vacuum chamber
1
. Once all of the liquid crystal
1
b
is injected in the liquid crystal cell
1
a
, the LC container
1
c
is separated and the liquid crystal injection process is complete.
As stated above, the vacuum is generated in the vacuum chamber
1
before the liquid crystal cell
1
a
and the LC container
1
c
are combined and the liquid crystal
1
b
is injected in the liquid crystal cell
1
a
by a capillary effect and by the pressure difference between the inside of the liquid crystal cell
1
a
and the vacuum chamber
1
.
However, there is a problem in the liquid crystal injection method employing the aforementioned capillary effect and pressure difference in that the liquid injection time is increased as a panel is enlarged. Namely, a large-scale panel and narrow cell spacing require a great deal of effort, especially during the injection process, and as a result, productivity is relatively low.
In order to overcome the problems in the liquid crystal injection method using such capillary action, methods including lowering the viscosity of the liquid crystal (heating) or increasing the pressure difference inside the panel have been utilized.
As shown in
FIG. 3
, an injection opening and exhaust openings are formed in a panel
10
placed inside a heating/pressing chamber
80
. An injection connector
11
is connected to the injection opening and exhaust connectors
12
are connected to the exhaust openings. First to ninth valves
51
-
59
function to open and close pipe
70
, and traps
41
and
42
function to prevent reverse-flow.
In addition, in order to pump the inside of the panel
10
using a first pump
21
, the seventh valve
57
and the third valve
53
are closed, whereas the first valve
51
, the second valve
52
and the fourth valve
54
are opened, respectively, making the inside of the panel a high vacuum state by using the first pump
21
.
Next, the first valve
51
connected to the injection connector
11
is closed in order to maintain the high vacuum state, and the third valve
53
connected to a deformation pressing tank
30
is opened and then pumped in order to defoam the liquid crystal inside of the defoamation pressing tank
30
.
In this state, by opening the first valve
51
, the seventh valve
57
and the eighth valve
58
, and adding pressure on the outside of the defoamation pressing tank
30
, the liquid crystal inside of the tank is injected through the third valve
53
, the first valve
51
and the injection connector
11
.
The mechanical relation according to the method described above is as follows: V∝&Dgr;P/&eegr;, wherein, V is an injection speed; &Dgr;P is a pressure difference between a panel and a chamber; and, &eegr; is viscosity of liquid crystal. Here, the liquid crystal injected into the panel
10
is induced through an exhaust connector
12
according to the second pump
22
. That is, the injection connector
11
is for injecting liquid crystal, and the exhaust connector
12
is for taking in the liquid crystal resulting in the reduction of liquid crystal injection time.
Unfortunately, the injection-exhaust method shown in
FIG. 3
has several problems in that during a whole period of liquid crystal injection time in a large-scale panel, an exhaust section should be continuously opened. Thus, if chemically volatile material is included in the liquid crystal, then such material easily evaporates through the open exhaust connector. Further, since the injection speed is forced to speed up, it is always possible to damage the surface of an alignment layer due to a flow of liquid crystal.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a liquid crystal display and liquid crystal injection method that substantially obviate one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention to provide a liquid crystal display device and injection method for reducing liquid crystal injection time by forming polymer walls to make small panels, where a liquid crystal injection opening is assigned to each panel, and through a connector combining each injection opening and liquid crystal supply section, every small panel is at a high vacuum state for liq
Choi Su Seok
Choi Suk Won
Chowdhury Tarifur R.
LG. Philips LCD Co. Ltd.
Morgan & Lewis & Bockius, LLP
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