Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-09-19
2002-10-29
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S138000, C349S143000
Reexamination Certificate
active
06473142
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 dielectric frames of which dielectric constant is different from that of liquid crystal.
2. Description of the Related Art
Recently, a LCD has been proposed where the liquid crystal is not aligned, and the liquid crystal is driven by common electrode
17
having open areas
19
.
FIG. 1
is sectional view of pixel unit of the conventional LCD.
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. The TFT is formed on each pixel region and comprises a gate electrode, a gate insulator, a semiconductor layer, an ohmic contact layer, a source electrode, and a drain electrode, etc.
Alternatively, a passivation layer is formed over the whole first substrate, and pixel electrode
13
is connected to the drain electrode thereon.
On a second substrate, a light shielding layer
25
is formed to shield any light leakage from gate and data bus lines, and the TFT, a color filter layer
23
is formed on the light shielding layer, an over coat layer
45
is formed on the color filter layer, a common electrode
17
is formed to have open area
19
on the over coat layer, spacers
51
are dispersed to maintain the gap between the first and second substrates thereon, and a liquid crystal layer is formed between the first and second substrates.
Pixel electrode
13
and open area (slit)
19
of the common electrode
17
distort the electric field applied to the liquid crystal layer. Then, liquid crystal molecules are driven variously in a unit pixel. 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 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.
And, 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.
Moreover, because spacer
51
is not fixed and is mobile, there is problem that the distribution of the spacers is not uniform in the LC cell.
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 wide viewing angle by multi-domain 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 the first and second substrates, a plurality of gate bus lines arranged in a first direction on the first substrate and a plurality of data bus lines arranged in a second direction on the first substrate to define a pixel region, a pixel electrode electrically charged through the data bus line in the pixel region, a color filter layer on the second substrate, a common electrode on the color filter layer, dielectric frames in the pixel region, and an alignment layer on at least one substrate between the first and second substrates.
The dielectric frame is patterned, and dielectric constant of the dielectric frame is lower than dielectric constant of the liquid crystal layer.
The dielectric frame includes photosensitive materials, preferably includes a material selected from the group consisting of photoacrylate and BCB (BenzoCycloButene).
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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Konovalov et al, “Multidomain Vertically Aligned Mode”, Proc. of SID, 1998.
Bae Sung Joon
Kim Kyeong Jin
Yoo Jang Jin
LG. Philips LCD Ltd.
McKenna Long & Aldridge
Parker Kenneth
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