In-plane switching mode liquid crystal display device

Details In-plane switching mode liquid crystal display device In-plane switching mode liquid crystal display device

1998-09-08

2001-10-02

Dudek, James A. (Department: 2871)

Liquid crystal cells, elements and systems

Particular structure

Having significant detail of cell structure only

C349S143000

Reexamination Certificate

active

06297866

ABSTRACT:

This application claims the benefit of Korean Patent Application No. 1997-46190, filed Sep. 8, 1997, 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
To solve the problem of viewing angle limitation in twisted nematic LCDs, a multi-domain LCD, such as a two-domain TN LCD (TDTN LCD) and a domain divided TN LCD (DDTN LCD), and a TN LCD including an optical compensation film have ben proposed. In these LCDs, however, a contrast ratio is decreased and a color shift is generated according to a viewing angle.
Further, for the purpose of a wide viewing angle, an in-plane switching mode LCD has also been proposed.
FIG. 1
is a plan view of a unit pixel of a conventional in-plane switching mode active matrix LCD. As shown in the drawing, the LCD comprises a data bus line
1
and a gate bus line
2
, in which lines
1
and
2
are arranged perpendicularly and/or horizontally in a matrix on a transparent substrate thereby defining a unit pixel region. A common line
5
is arranged parallel to the gate bus line
2
in the pixel region. A thin film transistor (TFT) is formed adjacent a cross point of the data bus line
1
and the gate bus line
2
. A common electrode
11
and a data electrode
19
are formed in the pixel region.
FIG. 2
is a sectional view according to line I-I′ of FIG.
1
. As shown in the drawing, the TFT includes a gate electrode
10
electrically coupled to the gate bus line
2
, a gate insulator
13
on the gate electrode
10
, an amorphous silicon (a-Si) semiconductor layer
15
on the gate insulator
13
, an n+ a-Si layer
16
on the semiconductor layer
15
, and source/drain electrodes
17
,
18
which are electrically coupled to the data bus line
1
and the data electrode
19
, respectively.
The common electrode
11
is electrically coupled to the common line
5
, and the data electrode
19
is electrically coupled to the drain electrode
18
. Further, a passivation layer
20
and a first alignment layer (not illustrated) are deposited on the data electrode
19
and the gate insulator
13
.
On a second substrate
4
, a black matrix
6
is formed to prevent a light leakage around the TFT, the data bus line
1
, and the gate bus line
2
. A color filter layer
7
, an over-coat layer
8
, and a second alignment layer (not illustrated) are formed on the black matrix
6
in sequence. Finally, a liquid crystal layer is formed between the first and second alignment layer.
FIG. 3
is a drawing showing a structure of the electrodes driving a liquid crystal according to the conventional in-lane switching mode LCD.
Referring to
FIG. 3
, when a voltage is applied to the liquid crystal layer, the liquid crystal
30
has an average rotation of 45 degrees by the electric field between the common electrode
111
and the data electrode
119
thereby generating a gray inversion in a rotating direction. In particular, in a gray mode, yellow color is presented at +45 degrees of azimuth angle, and blue color is presented at −45 degrees of azimuth angle to a polarizer P by an optical anisotropy of the liquid crystal.
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 having no color-shift and no gray inversion by zigzag patterns of a plurality of electrodes which apply a plane electric field.
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 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 pair of electrodes applying a plane electric field in said liquid crystal layer, the electrodes being at an angle &thgr; with respect to said data bus line and substantially parallel to each other; and a liquid crystal layer between said first and second substrates.
In another aspect of the present invention, a method of forming a liquid crystal display device comprises the steps of forming first and second substrates; forming a data bus line and a gate bus line arranged in a matrix on said first substrate and defining a unit pixel region; forming a pair of electrodes applying a plane electric field in said liquid crystal, the electrodes being at an angle &thgr; with respect to said data bus line and substantially parallel to each other; and forming a liquid crystal layer between said first and second substrates.
In another feature according to the present invention, a pixel region is divided into a plurality of sub-pixel regions by a plurality of data electrode and common electrode in which the electrodes are in each of sub-pixel regions and this structure is symmetric to another structure in an adjacent sub-pixel region. It is preferable to divide a pixel region into four sub-pixel region.
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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