Liquid crystal cells – elements and systems – Nominal manufacturing methods or post manufacturing...
Reexamination Certificate
2002-09-27
2004-05-25
Dudek, James (Department: 2871)
Liquid crystal cells, elements and systems
Nominal manufacturing methods or post manufacturing...
C225S002000, C225S103000
Reexamination Certificate
active
06741320
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display panel, and more particularly, to a method for cutting a liquid crystal display panel to separate a plurality of unit LCD panels from the mother substrate.
2. Discussion of the Related Art
In general, a liquid crystal display (hereinafter, referred to as “LCD”) device displays a picture by individually supplying a data signal according to picture information to the liquid crystal cell arranged in a matrix form and controlling light transmittance of the liquid crystal cells.
In the LCD device, thin film transistor (hereinafter, referred to as “TFT”) array substrates are formed on a large mother substrate, and color filter substrates are formed on another mother substrate. By attaching the two mother substrates, a plurality of unit LCD panels are simultaneously formed. Since yield can be increased by simultaneously forming a plurality of the unit LCD panels on a glass substrate of a large area, a process of cutting the attached two mother substrates into unit LCD panels is required.
Conventionally, the cutting process includes a scribing process of forming a predetermined cutting line on the surface of the substrate with a diamond pen having a hardness higher than the glass substrate and a breaking process of cutting by applying a physical force. The cutting process of the unit LCD panel will be described in detail with reference to the accompanied drawings.
FIG. 1
is a schematic plane view showing a unit LCD panel formed from a TFT array substrate and a color filter substrate attached to face into each other.
In
FIG. 1
, an LCD panel
10
includes a picture display unit
13
having a plurality of liquid crystal cells arranged in a matrix form, a gate pad unit
14
connected to a plurality of gate lines of the picture display unit
13
, and a data pad unit
15
connected to a plurality of data lines of the picture display unit
13
.
The gate pad unit
14
and the data pad unit
15
are formed at the marginal portion of the TFT array substrate
1
. The marginal portion does not overlap the color filter substrate
2
.
The gate pad unit
14
provides a scan signal supplied from the gate driver integrated circuit to the gate lines of the picture display unit
13
. The data pad unit
15
supplies picture information supplied from the data driver integrated circuit to the data lines of the picture display unit
13
.
The data lines receiving the picture information and the gate lines receiving the scan signal are disposed to be perpendicularly crossed with each other on the TFT array substrate
1
of the picture display unit
13
. At the crossed portion, a TFT is formed for switching the liquid crystal cells, and a pixel electrode is formed to be connected to the TFT for driving the liquid crystal cells. Further, a protective layer is formed at the entire surface to protect the electrode and the TFT.
At the color filter substrate
2
of the picture display unit
13
, a plurality of color filters are formed to be separated by cell regions with a black matrix, and a common transparent electrode corresponding to the pixel electrode are formed at the TFT array substrate
1
.
A cell gap is formed between the TFT array substrate
1
and the color filter substrate
2
so that the two substrates are spaced apart from and face into each other. The TFT array substrate
1
and the color filter substrate
2
are attached by a sealant (not shown) formed at the exterior of the picture display unit
13
. A liquid crystal layer (not shown) is formed at the space between the TFT array substrate
1
and the color filter substrate
2
.
FIG. 2
is a cross-sectional view showing a plurality of the unit LCD panels formed in the first mother substrate having the TFT array substrates and the second mother substrate having the color filter substrates of FIG.
1
.
As shown in
FIG. 2
, a plurality of the unit LCD panels are formed in such a manner that one side of the TFT array substrates
1
is protruded as much as a dummy region
31
.
This is because the gate pad unit
14
and the data pad unit
15
are formed at the marginal portion where the TFT array substrates
1
and the color filter substrates
2
do not overlap.
Thus, the color filter substrates
2
formed on the second mother substrate
30
are formed to be isolated as much as the dummy regions
31
corresponding to the area that the TFT array substrates
1
formed in the first mother substrate
20
are protruded.
Each unit LCD panel is disposed at the first and second mother substrates
20
and
30
so that the first and second mother substrates
20
and
30
are used at the maximum. Depending on a model, the unit LCD panels are generally formed to be isolated as much as the dummy regions
32
. Dummy regions
21
for a process margin are also formed in the marginal portions of the first and second mother substrates
20
and
30
.
After the first mother substrate
20
where the TFT array substrates
1
are formed and the second mother substrate
30
where the color filter substrates
2
are formed are attached to each other, the LCD panels are individually cut through the scribing process and the breaking process. The dummy regions
31
formed at the region where the color filter substrates
2
of the second mother substrate
30
are isolated. The dummy regions
32
isolating the unit LCD panels and the dummy regions
21
formed at the marginal potion of the first and second mother substrates
20
and
30
, are simultaneously removed.
As shown in
FIG. 2
, in case of a model in which the dummy regions
31
,
32
, and
21
are formed on the first and second mother substrates
20
and
30
, as the number of unit LCD panels which can be formed on the first and second mother substrates
20
and
30
is limited, efficiency in using the first and second mother substrates
20
and
30
is reduced and accordingly, productivity is decreased.
Taking the above problems into consideration, a cross-sectional structure of the first and second mother substrates in which the dummy regions
32
are not formed by preventing the unit LCD panels from being separated from each other, was suggested as shown in FIG.
3
.
The cutting process to the unit LCD panels shown in
FIG. 3
will now be described with reference to the sequential exemplary views,
FIGS. 4A
to
4
J.
As shown in
FIG. 4A
, the first and second mother substrates
20
and
30
attached to face into each other are loaded on a first table
33
.
Next, as shown in
FIG. 4B
, the first table
33
is moved in one direction to sequentially form a plurality of first scribing lines
42
on the first mother substrate
20
with a cutting wheel
41
.
After the first and second mother substrates
20
and
30
in
FIG. 4C
are rotated by 90°, the first table
33
is moved back to its original position to sequentially form a plurality of second scribing lines
43
on the surface of the first mother substrate
20
through the cutting wheel
41
.
FIG. 4D
illustrates the first and second mother substrates
20
and
30
, which are overturned and loaded on a second table
34
. While the second table
34
is moved in one direction, the second mother substrate
30
is pressed by a breaking bar
44
along the second scribing lines
43
so that a crack is transmitted on the first mother substrate
20
.
Next, as shown in
FIG. 4E
, the first and second mother substrates
20
and
30
are rotated by 90°. While the second table
34
is moved back to its original position, the second mother substrate
30
is pressed by the breaking bar
44
along the first scribing lines
42
, so that a crack is transmitted on the first mother substrate
20
.
As shown in
FIG. 4F
, the first and second substrates
20
and
30
are loaded on a third table
35
. A plurality of third scribing lines
46
are sequentially formed on the surface of the second mother substrate
30
with a cutting wheel
45
by moving the third table
35
in one direction.
Thereafter, the first and second mother substrates
20
and
30
are rotated by 90°, as sh
Chae Kyung-Su
Shin Sang-Sun
Dudek James
Duong Tai
L.G.Philips LCD Co., Ltd.
Morgan & Lewis & Bockius, LLP
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