Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-02-16
2002-01-01
Sikes, William I (Department: 2164)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
Reexamination Certificate
active
06335776
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 multi-domain liquid crystal display device having a side or auxiliary electrode on a layer whereon a pixel electrode is formed.
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 side electrodes insulated from pixel electrodes.
FIGS. 1A
to
1
C are sectional views of pixel units 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
4
. 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
4
is formed over the whole first substrate, and a part of pixel electrode
13
overlaps side electrode
15
(refer to FIG.
1
A). Alternatively, pixel electrode
13
is formed on the gate insulator, passivation
4
is formed over the whole first substrate. Afterward, side electrode
15
is formed as overlapping a part of pixel electrode
13
(refer to FIG.
1
B). Moreover, it is possible to pattern the pixel electrode
13
by etching and dividing the pixel region (refer to FIG.
1
C).
On second substrate
33
, a common electrode
17
is formed and together with pixel electrode
13
applies electric field to a liquid crystal layer. Side electrode
15
and open area (slit)
19
distort the electric field applied to the liquid crystal layer, and then in an 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 a needed position.
In the LCDs, however, open area
19
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 rapid response 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 facing 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 common electrode on said second substrate; a pixel electrode electrically charged through said data bus line to drive said liquid crystal layer with said common electrode; a side electrode on a same layer whereon said pixel electrode is formed; a passivation insulating said pixel and side electrodes from electrodes and bus lines other than the pixel and side electrodes; and an alignment layer on at least one substrate between said first and second substrates.
In another aspect of the present invention, a multi-domain liquid crystal display device comprises first and second substrates facing 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 common electrode on said second substrate; a pixel electrode coupled to the data bus line; a side electrode on a same layer as said pixel electrode; and a passivation insulating said pixel and side electrodes.
In another aspect of the present invention, a method of making a multi-domain liquid crystal display device comprises the steps of forming first and second substrates facing each other; forming a liquid crystal layer between said first and second substrates; forming 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; forming a common electrode on said second substrate; forming a pixel electrode electrically charged through said data bus line to drive said liquid crystal layer with said common electrode; forming a side electrode on a same layer whereon said pixel electrode is formed; forming a passivation insulating said pixel and side electrodes from electrodes and bus lines other than the pixel and side electrodes; and forming an alignment layer on at least one substrate between said first and second substrates.
In a further aspect of the present invention, a method of making a multi-domain liquid crystal display device comprises the steps of forming first and second substrates facing each other; forming a liquid crystal layer between said first and second substrates; forming 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; forming a common electrode on said second substrate; forming a pixel electrode coupled to the data bus line; forming a side electrode on a same layer as said pixel electrode; and forming a passivation insulating said pixel and side electrodes.
In a further aspect of the present invention, a method of making a liquid crystal display device first and second substrates, the method comprising the steps of: forming 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; forming a transistor corresponding to the pixel region having gate, source, and drain electrodes; forming a pixel electrode electrically charged through said data bus line to drive said liquid crystal layer with a common electrode; forming an auxiliary electrode on a same layer whereon said pixel electrode is formed, the auxiliary electrode and the pixel electrode being electrically insulated from each other; forming the common electrode on said second substrate; and forming a liquid crystal layer between said first and second substrates, wherein said pixel region is divided into at least two portions and liquid crystal molecules in said liquid crystal layer in each of the at least two portions
Kim Kyeong Jin
Yoo Jang Jin
Chowdhury Tarifur R.
LG. Philips LCD Co. Ltd.
Long Aldridge & Norman LLP
Sikes William I
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