Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2002-05-16
2004-11-23
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S043000, C349S149000, C349S152000, C257S059000
Reexamination Certificate
active
06822719
ABSTRACT:
The present invention claims the benefit of Korean Patent Application No. P2001-28978 filed in Korea on May 25, 2001, 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 a method for manufacturing the same, and more particularly, to a liquid crystal display device and a method for manufacturing the same in which a uniform alignment film is formed.
2. Discussion of the Related Art
FIG. 1
is a cross sectional view of a liquid crystal display device according to the related art. In
FIG. 1
, the liquid crystal display device includes a liquid crystal display panel
10
, a light source
20
, and a driving circuit
30
. The liquid crystal display panel
10
includes an upper substrate
1
and a lower substrate
2
opposed to each other at a constant interval with a liquid crystal layer
3
interposed therebetween. The upper substrate
1
includes a black matrix layer
4
and a color filter layer
5
. The lower substrate
2
includes a plurality of gate lines and a plurality of data lines, a pixel electrode, and a thin film transistor (TFT). The gate lines and the data lines are arranged at constant intervals along first and second directions. The intersection of a gate line and a data line defines a pixel region. The pixel electrode and the TFT are formed in the pixel region.
FIG. 2
is a plane view of the lower substrate shown in
FIG. 1
, and
FIG. 3
is an enlarged view of a pad of the lower substrate shown in FIG.
1
. In
FIGS. 2 and 3
, each of the gate and data lines of the pixel region
60
are electrically connected to a driving circuit
30
, thereby providing a signal to each of the gate and data lines. Gate pads
40
and
50
electrically interconnect each of the gate lines to the driving circuit
30
, and data pads
40
-
1
and
50
-
1
electrically interconnect each of the data lines to the driving circuit
30
.
A method for manufacturing a liquid crystal display panel according to the related art will now be described.
During processing of a TFT substrate (a lower substrate), a gate electrode, a gate line, and a gate pad are formed at an end of the gate line on a substrate, and a gate insulating film is formed thereupon. A semiconductor layer and an ohmic contact layer are formed on the gate insulating film. The semiconductor layer and the ohmic contact layer are used as channels of the thin film transistor. Source and drain electrodes are formed on the ohmic contact layer. A data line is formed to cross the gate line, and a data pad is formed at an end of the data line. A pixel electrode is formed to electrically connect with the drain electrode, thereby forming the TFT substrate.
During processing of a color filter substrate (a upper substrate), a black matrix layer is formed on a substrate, and color filter layers of R, G, and B are formed on the black matrix layer. The black matrix layer prevents light from being transmitted to a region other than the pixel electrode. Then, a common electrode is formed on the color filter layers to supply a voltage to the liquid crystal layer, thereby forming the color filter substrate. Thereafter, both the lower and upper substrates are attached to each other, and a liquid crystal is injected therebetween, thereby forming a liquid crystal cell.
Display characteristics such as light transmissivity, response time, viewing angle, and contrast, for example, of a liquid crystal display device are dependent upon an arrangement of liquid crystal molecules. Accordingly, an alignment film
7
is formed on the lower and upper substrates to uniformly control alignment of the liquid crystal molecules. In general, the alignment film
7
is formed by depositing, hardening and rubbing an alignment material. For example, a polyimide or polyamide based material is deposited on the lower and upper substrate, and hardened. Then, the hardened material is rubbed with a rubbing cloth attached to a rotating drum to form a fine groove, thereby aligning the liquid crystal molecules.
However, the related art liquid crystal display device according to the related art has several problems. For example, a step difference occurs in the lower substrate between a region where the pads
40
and
40
-
1
are formed and a region C where no pads are formed, as shown in FIG.
3
. The region where the pads
40
and
40
-
1
are formed is higher than the region C. Accordingly, during the rubbing process of the lower substrate, an abnormal portion is created in the rubbing cloth due to the step difference. For this reason, a spot is generated in the alignment film by the rubbing cloth. Specifically, a relatively high pretilt angle is formed in the alignment film when rubbed with a rubbing cloth having the abnormal portion as compared to an alignment film rubbed with a rubbing cloth not having the abnormal portion. A liquid crystal display device having an alignment film with a relatively high pretilt angle has low threshold voltage characteristics when driven. Accordingly, the low threshold voltage characteristics result in abnormal display portions, thereby degrading display characteristics of the liquid crystal display device.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a liquid crystal display device and a method for manufacturing the same that substantially obviates one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a liquid crystal display device and a method for manufacturing the same, in which a spot of an alignment film generated during a rubbing process is removed, so that the alignment film is uniformly formed.
Additional features of the invention will be set forth in part in the description which follows, and in part will become apparent from the description, or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a liquid crystal display device includes a first substrate, a second substrate opposing the first substrate, a plurality of gate lines and a plurality of data lines on the first substrate, a plurality of gate pads, each gate pad disposed at a first end of each gate line, a plurality of data pads, each data pad disposed at a first end of each data line, a dummy portion between the pads, the dummy portion having a same pattern as a pattern of the plurality of gate pads and a pattern of the plurality of data pads, a plurality of thin film transistors at a cross point of the gate and data lines, a first alignment layer on the first substrate, and a liquid crystal layer between the first substrate and the second substrate.
In another aspect, a method for manufacturing a liquid crystal display device includes forming a gate electrode, a plurality of gate lines, a plurality of gate pads, and dummy portions on a first substrate, each dummy portion having a pattern similar to a pattern of the plurality of gate pads in a region between the plurality of gate pads, forming a gate insulating film on the first substrate, forming a semiconductor layer and a ohmic contact layer on the gate insulating film, forming a source and drain electrode, a plurality of data lines, and a plurality of data pads on the first substrate, forming a passivation film on the first substrate, forming pixel electrodes on the passivation film, and forming a first alignment layer on the first substrate.
In another aspect, a method for manufacturing a liquid crystal display device, includes forming a gate electrode, a plurality of gate lines, and a plurality of gate pads on a first substrate, forming a gate insulating film on a first substrate, forming a semiconductor layer and a ohmic contact layer on the gate insulating film, forming s
Park Cheol Woo
Song Hyun Ho
Chowdhury Tarifur R.
LG. Phillips LCD Co., Ltd.
Morgan & Lewis & Bockius, LLP
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