Multi-domain liquid crystal display device

Details Multi-domain liquid crystal display device Multi-domain liquid crystal display device

2002-12-03

2004-06-15

Chowdhury, Tarifur R. (Department: 2871)

Liquid crystal cells, elements and systems

Particular structure

Having significant detail of cell structure only

C349S143000, C349S038000, C349S046000

Reexamination Certificate

active

06750935

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display device (LCD), and more particularly, to a liquid crystal display device having a side or auxiliary electrode.
2. Description of the Related Art
Recently, an LCD has been proposed where the liquid crystal is not aligned and the liquid crystal is driven by common-auxiliary electrodes insulated from pixel electrodes.
FIG. 1
is sectional view of pixel unit of the conventional LCDs.
Regarding conventional LCDs, a plurality of gate bus lines arranged in a first direction on a first substrate and a plurality of data bus lines arranged in a second direction on the first substrate divide the first substrate into a plurality of pixel regions. A thin film transistor (TFT) applies image signal delivered from the data bus line to a pixel electrode
13
on a passivation layer
37
. The TFT is formed on each pixel region and comprises a gate electrode, a gate insulator, a semiconductor layer, a source electrode, and a drain electrode, etc. Side electrode
15
is formed surrounding the pixel electrode
13
on the gate insulator, thereon passivation layer
37
is formed over the whole first substrate, and a part of pixel electrode
13
overlaps side electrode
15
.
Alternatively, pixel electrode
13
is formed on the gate insulator, and passivation layer
37
is formed over the whole first substrate.
On second substrate, a common electrode
17
is formed and together with pixel electrode
13
applies electric field to a liquid crystal layer. Side electrode
21
and open area (slit)
27
distort the electric field applied to the liquid crystal layer. Then in a unit pixel liquid crystal molecules are driven variously. This means that when voltage is applied to the LCD, dielectric energy due to the distorted electric field arranges the liquid crystal directors in needed or desired positions.
In the LCD, however, open area
27
in common electrode
17
or pixel electrode
13
is necessary, and the liquid crystal molecules could be driven stably when the open area is wider. If the electrodes do not have an open area or the width of the open area is narrow, the electric field distortion needed to divide the pixel region becomes weak. Then, when voltage over a threshold voltage, V
th
, is applied, the time needed to stabilize the liquid crystal directors increases. In particular, the response time can be over 100 msec. At this time, disclination occurs from the area where the liquid crystal directors are parallel with a transmittance axis of the polarizer, which results in a decrease in brightness. Further, according to the surface state of LCDs, the liquid crystal texture has an irregular structure.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an LCD 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 multi-domain LCD having high response time characteristics and high brightness by stable arrangement of liquid crystal molecules.
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 the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, a multi-domain liquid crystal display device comprises first and second substrates racing each other; a liquid crystal layer between said first and second substrates; a plurality of gate bus lines arranged in a first direction on said first substrate and a plurality of data bus lines arranged in a second direction on said first substrate to define a pixel region; a pixel electrode electrically charged through said data bus line in said pixel region; a common-auxiliary electrode surrounding said pixel electrode on a same layer whereon said gate bus line is formed; a gate insulator over said whole first substrate; a passivation layer on said gate insulator over said whole first substrate; a light shielding layer on said second substrate; a color filter layer on said light shielding layer; a common electrode on said color filter layer; and an alignment layer on at least one substrate 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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