Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2002-04-19
2004-11-30
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S129000, C349S130000, C349S133000
Reexamination Certificate
active
06825897
ABSTRACT:
This application claims the benefit of the Korean Patent Application No. P2002-013643 filed on Mar. 13, 2002, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display panel, and more particularly, to an indicator for deciding a grinding amount of liquid crystal display panel and a method for detecting grinding failure using the same. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for simplifying a grinding detection process in grinding a marginal portion of a unit liquid crystal display panel after cutting into the unit panels from the large mother substrate.
2. Discussion of the Related Art
Generally, a liquid crystal display (LCD) panel is cut into a plurality of unit LCD panels to improve yield. For simultaneously producing LCD panels, a plurality of thin film transistors and color filters are formed on two different mother substrates. Thereafter, the two mother substrates are attached to each other.
Conventionally, cutting of the unit LCD panel is performed through the process of forming a scribing line on the surface of the mother substrate with a wheel having a hardness higher than glass and breaking the mother substrate scribing line. The process for fabricating an LCD apparatus will be described with reference to the accompanied drawings.
FIG. 1
is a schematic cross-sectional view illustrating a first mother substrate including thin film transistor array substrates and a second mother substrate including color filter substrates. The first and second mother substrates are attached to each other, thereby forming a plurality of unit LCD panels.
With reference to
FIG. 1
, the unit LCD panels are formed so that one side of thin film transistor array substrates
1
is formed to be protruded more than color filter substrates
2
. This is because a gate pad unit (not shown) and a data pad unit (not shown) are formed at the marginal portion of the thin film transistor array substrates
1
that do not overlap the color filter substrates
2
.
Therefore, the color filter substrates
2
formed on the second mother substrate
30
are formed apart for the area of a dummy region
31
corresponding to the region where the thin film transistor array substrates
1
are protruded on the first mother substrate
20
.
Also, the respective unit LCD panels are positioned to effectively utilize the first and second mother substrates
20
and
30
. The unit LCD panels are formed apart for the area of the dummy region
32
depending on the model.
The first mother substrate
20
where the thin film transistor array substrates
1
are included, and the second mother substrate
30
where the color filter substrates
2
are included, are attached to each other. Thereafter, the LCD panels are cut into an individual panel. The dummy region
31
, where the color filter substrates
2
of the second mother substrate
30
are formed, and the dummy region
32
for separating the unit LCD panels are simultaneously removed at this time.
After cutting the second mother substrate
30
into the unit LCD panels, a shorting line formed at the marginal portion of the thin film transistor array substrate
1
for intercepting static electricity is removed. In this process, a sharp corner of the unit LCD panel is ground. The static electricity may occur at the shorting line when a conductive film is formed on the thin film transistor array substrate
1
. Also, by grinding the sharp corner of the LCD panel, pieces are not separated from the corner of the unit LCD panel by the external impact and prevent an operator from being damaged by the sharp corner of the unit LCD panel in the fabrication process.
The method for grinding the conventional unit LCD panel and a method for detecting a grinding amount will be described in detail with reference to the accompanied drawing.
FIG. 2
is a schematic plane view of the conventional unit LCD panel.
With reference to
FIG. 2
, a unit LCD panel
10
includes a picture display unit
13
that liquid crystal cells are arranged in a matrix form, a gate pad unit
14
for connecting a plurality of gate lines GL
1
to GLm of the picture display unit
13
to a gate driver integrated circuit (not shown), to which a gate signal is applied, and a data pad unit
15
for connecting a plurality of data lines DL
1
to DLn of the picture display unit
13
to a data driver integrated circuit (not shown), to which the picture information is applied. The gate pad unit
14
and the data pad unit
15
are formed at the marginal portion of the thin film transistor array substrate
1
where both side edges are protruded comparing to the color filter substrate
2
.
At the region where the data lines DL
1
to DLn and the gate lines GL
1
to GLm vertically cross one another, a thin film transistor for switching the liquid crystal cell is formed therein. A pixel electrode is formed to be connected to the thin film transistor for driving the liquid crystal cell. A passivation film is formed on the entire surface to protect the data lines DL
1
to DLn, the gate lines GL
1
to GLm, the thin film transistors, and the electrodes.
Also, a shorting line (not shown) for electrically shorting out the conductive films is formed at the marginal portion of the thin film transistor array substrate
1
, to remove static electricity which may be generated in forming the data lines DL
1
to DLn, the gate lines GL
1
to GLm, and the electrodes on the thin film transistor array substrate
1
.
At the color filter substrate
2
of the picture display unit
13
, a plurality of color filters are coated and separated by cell regions with a black matrix. A common transparent electrode corresponding to the pixel electrode is formed at the thin film transistor array substrate
1
.
A cell gap is formed between the thin film transistor array substrate
1
and the color filter substrate
2
so that the two substrates are spaced apart and face into each other. The thin film transistor array substrate
1
and the color filter substrate
2
are attached by a sealing unit (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 thin film transistor array substrate
1
and the color filter substrate
2
.
On the other hand, a plurality of tap marks
50
a
to
50
j
are formed and separated from one another for aligning the data lines DL
1
to DLn, the gate lines GL
1
to GLm to contact a plurality of pins of the gate driver integrated circuit and the data driver integrated circuit.
The above unit LCD panel
10
must be ground to have a sloped edge from the end of the unit LCD panel
10
to the grinding line R
1
, as shown in the expansion region EX
1
of FIG.
2
. However, the actual ground line of the unit LCD panel
10
has an error margin D
1
from the grinding line Rl. When the error is beyond the error margin D
1
, it is determined that the grinding is defective.
To detect the failure, an operator must separate the ground unit LCD panel
10
from the production line for a predetermined period. Thereafter, an additional apparatus should be used to determine whether the actual ground line of the unit LCD panel
10
is beyond the error margin D
1
by using a high magnifying power camera or a projector positioned in the measuring apparatus.
In the method for the grinding detection of the conventional liquid crystal display panel, the ground unit liquid crystal panel
10
is separated from the production line for a predetermined period. Then, the unit LCD panel is measured by using an additional apparatus to determine whether the actual ground line of the unit LCD panel
10
is beyond the error margin D
1
with a high magnifying power camera or a projector positioned in the measuring apparatus.
As described previously, the operation of examining the grinding amount with the measuring apparatus, after the operator separates the unit liquid crystal panel from the production line to measure the grinding amo
Chae Kyung-Su
Choo Hun-Jun
Lim Jong Go
Chowdhury Tarifur R.
Kim Richard H
LG.Philips LCD Co. , Ltd.
Morgan & Lewis & Bockius, LLP
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