Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Reexamination Certificate
2000-11-01
2003-05-06
Dudek, James (Department: 2871)
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
C349S143000, C349S139000
Reexamination Certificate
active
06559904
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a liquid crystal display, and more particularly to a liquid crystal display with a high aperture ratio that is adapted to increase an aperture ratio.
2. Description of the Related Art
Generally, a liquid crystal display (LCD) tends toward wider applications by virtue of its characteristics such as light weight, thin thickness and low power driving, etc. Accordingly, the LCD has been used for office automation equipment and video/audio equipment, etc. The LCD controls a transmitted amount of a light beam in response to a data signal applied to a plurality of control switches arranged in a matrix type to display a desired picture on the screen.
Referring to
FIG. 1
, the conventional LCD includes a source electrode
14
branched from a data wire
22
to apply an image signal, a gate electrode
4
branched from a gate wire
24
to apply a scanning signal, and a drain electrode
16
for applying a data signal to a pixel electrode
20
. A number of data wires
22
are provided in a vertical direction on a substrate
2
to transmit a data signal applied from a data driver (not shown) to each source electrode
14
. A number of gate wires
24
are provided in a horizontal direction on the substrate
2
in such a manner so as to cross each data wire
22
to transmit a scanning signal applied from a gate driver (not shown) to each gate electrode
4
. At this time, a scanning signal transmitted from the gate wire
24
is applied to the gate electrode
4
to transmit a data signal to the drain electrode
16
. In other words, the gate electrode
4
switches the data signal in response to the scanning signal. The data signal transmitted to the drain electrode
16
in this manner is applied to the pixel electrode
20
to control a transmitted amount of a light beam.
Hereinafter, a thin film transistor (TFT) provided at each intersection between each data wire
22
and each gate wire
24
will be described with reference to FIG.
2
. As shown in
FIG. 2
, the TFT includes a gate electrode
4
provided at the upper portion of the substrate
2
to apply a scanning signal, an active layer
26
provided to transmit a data signal in response to the scanning signal, a gate insulator
6
for electrically isolating the active layer
26
from the gate electrode
4
, a source electrode
14
, a drain electrode
16
for applying a data signal to the. pixel electrode
20
, and a protective film
18
for protecting the source electrode
14
and the drain electrode
16
.
The active layer
26
consists of a semiconductor layer
8
formed by vapor-depositing an amorphous silicon (a-Si), and ohmic contact layers
10
formed by vapor-depositing a n+ a-Si at both upper portions of the semiconductor layer
8
. A stopper layer
12
is provided between the ohmic contact layers
10
to electrically isolate the ohmic contact layers
10
from each other. Since a channel allowing electrons to be moved therethrough is formed in the active layer
26
when a scanning signal with a high level is applied to the gate electrode
4
, a data signal at the source electrode
14
is transmitted, via the active layer
26
, to the drain electrode
16
. On the other hand, since the channel formed in the active layer is shut off when a scanning signal with a low level is applied to the gate electrode
4
, the transmission of a data signal to the drain electrode
16
is stopped. The protective film
18
plays a role to protect the source electrode
14
and the drain electrode
16
as well as to electrically isolate the pixel electrode from the data wire
22
. In this case, the protective film
18
has a high dielectric constant resulting in cross talk. For instance, SiN
x,
used as a protective film of amorphous silicon, has a certain dielectric constant (e.g., 6.4 to 6.6) to generate coupling between the pixel electrode
20
and the data wire
22
, thereby causing cross talk. In order to solve this problem, the data wire
22
and the pixel electrode
20
are spaced by a desired distance d (e.g., 3 to 5 &mgr;m) from each other as shown in FIG.
1
. It is desirable that the pixel electrode is made from an indium thin oxide (ITO) to transmit a light beam. In this case, a light beam progressing from a light-guide plate (not shown) into the substrate
2
is transmitted at an area provided with the pixel electrode
29
while being shut off at the other area. In other words, a light beam is shut off at an area corresponding to the space between the pixel electrode
20
and the data wire
22
. As a result, the conventional LCD has a problem in that an aperture ratio is deteriorated.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a liquid crystal display with a high aperture ratio that is adapted to heighten an aperture ratio.
In order to achieve these and other objects of the invention, a liquid crystal display device with a high aperture ratio according to an embodiment of the present invention includes a pixel electrode having one side thereof consisting of a portion overlapping with a data wire and a portion spaced from the data wire in such a manner that overlapping areas at both sides of the data wire is equal to each other.
A liquid crystal display device with a high aperture ratio according to another embodiment of the present invention includes a data wire formed to alternately have a first width and a second width; pixel electrodes formed in such a manner so as to be overlapped by a desired distance at both sides of the data wire having the first width and to be spaced by a desired distance at both sides of the data wire having the second width.
A liquid crystal display device with a high aperture ratio according to still another embodiment of the present invention includes a data wire formed to be shifted by a desired distance to the left from a reference line and to be shifted by a desired distance to the right from the reference line; a first pixel electrode formed in such a manner so as to overlap with the data wire shifted to the left by a desired distance and to be spaced by a desired distance from the data wire shifted to the right; and a second pixel electrode formed in such a manner so as to be spaced by a desired distance from the data wire shifted to the left and to overlap with the data wire shifted to the right by a desired distance.
REFERENCES:
patent: 5936685 (1999-08-01), Ito et al.
patent: 5986723 (1999-11-01), Nakamura et al.
patent: 6249325 (2001-06-01), Ohkawata et al.
patent: 6326641 (2001-12-01), Choi
patent: 10153799 (1998-06-01), None
Kwak Dong Yeung
Lee Gun Hee
Park Kwang Sup
Birch & Stewart Kolasch & Birch, LLP
Dudek James
LG Philips LCD CO, Ltd.
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