Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-03-17
2002-06-04
Ton, Toan (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S040000, C349S096000
Reexamination Certificate
active
06400435
ABSTRACT:
This application claims the benefit of Korean Patent Application No. 1998-34648, filed on Aug. 26, 1998, 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, an in-plane switching mode liquid crystal display device.
2. Discussion of the Related Art
Recently, in-plane switching mode liquid crystal display devices (IPS-LCDs) have been widely studied for improving the viewing angle characteristic. The liquid crystal molecules in these devices are nearly horizontally aligned.
FIG. 1
is a plan view of a unit pixel of a conventional in-plane switching mode active matrix LCD, and
FIG. 2
is a sectional view according to line I-I′ of FIG.
1
.
As shown in the drawings, in the conventional LCD, a gate bus line
1
and a data bus line
2
are arranged perpendicularly and/or horizontally in a matrix on a first substrate
10
thereby defining a unit pixel region. A common line
16
is arranged parallel to the gate bus line
1
in the pixel region. A thin film transistor (TFT) is formed adjacent a cross point of the gate bus line
1
and the data bus line
2
. A common electrode
11
and a data electrode
19
are formed in the pixel region.
The TFT includes a gate electrode
12
electrically coupled to the gate bus line
1
, a gate insulator
13
on the gate electrode
12
, an amorphous silicon (a-Si) semiconductor layer
15
on the gate insulator
13
, an ohmic contact layer
17
on the semiconductor layer
15
, and source/drain electrode
19
which are electrically coupled to the data bus line
2
and the data electrode
20
, respectively.
The common electrode
11
is electrically coupled to the common line
16
, and the data electrode
20
is electrically coupled to the source/drain electrode
19
. Further, a passivation layer (not illustrated) and a first alignment layer
21
are deposited on the substrate
10
, and a polarizer
35
a
is provided on an opposing surface of the substrate
10
.
On a second substrate
23
, a light shielding layer
25
is formed to prevent light leakage around the TFT, the gate bus line
1
, and the data bus line
2
. A color filter layer
27
, and a second alignment layer
29
are formed on the light-shielding layer
25
in sequence.
An electric field shielding layer
30
and an analyzer
35
b
are formed on an opposing surface of the substrate
23
. The electric field shielding layer
30
includes a transparent metal such as indium tin oxide(ITO).
A liquid crystal layer
40
is formed between the first and second substrates.
When a voltage is not applied to the LCD having the above structure, liquid crystal molecules in the liquid crystal layer
40
are aligned according to alignment directions of the first and second alignment layers
21
and
29
. However, when a voltage is applied between the common electrode
11
and the data electrode
20
, the liquid crystal molecules become aligned in parallel extending in the directions of the dotted arrows in
FIG. 1
of the common and data electrode.
For an electric field from a direction of the analyzer
35
b,
the electric field shielding layer
30
prevents the apparatus from being affected by such electric field. However, when a protection film on the analyzer
35
b
is removed and/or a user rubs the surface of the substrate
23
to remove a dust on the surface, static electricity may be generated. To discharge the static electricity, many long hours are needed. This static electricity in the apparatus produces a strange electric field (dotted arrows in the vertical direction in
FIG. 2
) which disturbs or interferes with a desirable plane electric field.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an in-plane switching mode LCD that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide an in-plane switching mode LCD that prevents or minimizes the formation of static electricity.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by 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 and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, an in-plane switching mode liquid crystal display device comprises first and second opposed substrates; a liquid crystal layer between said first and second substrates; a data bus line and a gate bus line arranged in a matrix on said first substrate and defining a unit pixel region; a common electrode and a data electrode, the common and data electrodes applying a plane electric field in said liquid crystal; an electric field shielding layer on said second substrate, the electric field shielding layer shielding the apparatus from a strange electric field; and a discharge member electrically coupled to said electric field shielding layer for discharging static electricity.
In another aspect of the present invention, an in-plane switching mode liquid crystal display device comprises first and second opposed substrates; a liquid crystal layer between said first and second substrates; an electric field shielding layer on said second substrate, the electric field shielding layer shielding the apparatus from a strange electric field; and a discharge member electrically coupled to said electric field shielding layer for discharging static electricity.
In another aspect of the present invention, an in-plane switching mode liquid crystal display device comprises first and second substrates having inner surfaces; a gate bus line and a data bus line arranged in a matrix on said first substrate and defining a unit pixel region; a common line arranged parallel to the gate bus line in the pixel region; a TFT formed adjacent a cross point of the gate bus line and the data bus line; a common electrode and a data electrode formed in the pixel region, wherein the common electrode is electrically coupled to the common line, and the data electrode is electrically coupled to the source/drain electrode; a passivation layer and a first alignment layer deposited on the first substrate; a polarizer provided on an opposing surface of the first substrate; a light shielding layer on the second substrate to prevent light from leaking around the TFT, the gate bus line, and the data bus line; a color filter layer and a second alignment layer formed on the light shielding layer in sequence; an electric field shielding layer formed on an opposing surface of the second substrate, wherein the electric field shielding layer includes a transparent metal such as ITO; a discharge member electrically coupled to the electric field shielding layer; an analyzer on the electric field shielding layer; and a liquid crystal layer between said first and second substrates.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
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Son Ki Sup
Won Hyun Goo
LG. Philips LCD Co. Ltd.
Long Aldridge & Norman LLP
Ton Toan
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