Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Reexamination Certificate
2003-04-25
2004-08-17
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
C349S187000
Reexamination Certificate
active
06778230
ABSTRACT:
This application claims the benefit of Korean Application No. P2002-78377 filed in Korea on Dec. 10, 2002, which is hereby incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display panel, and more particularly to a liquid crystal display panel that is adapted to preventing static electricity from coming into picture display part and a fabricating method thereof.
2. Description of the Related Art
Generally, a liquid crystal display uses an electric field across a liquid crystal having dielectric anisotropy to control the light transmittance of the liquid crystal. A liquid crystal display panel includes a plurality of liquid crystal cells in a matrix that each contain liquid crystal and a transistor. The matrix of liquid crystal cells is controlled using a driver circuits so that a picture is displayed on the liquid crystal display panel.
More particularly, the liquid crystal display panel is provided with gate lines in one direction and data lines in other direction such that the gate lines and data lines cross over each other. Each liquid crystal cell is adjacent to a crossover of a gate line and a data line. A common electrode is provided in all of the liquid crystal cells of the liquid crystal display panel. A pixel electrode is provided in each of the liquid crystal cells. A Thin Film Transistor (“TFT”) is also provided in each of the liquid crystal cells. Each of the pixel electrodes is connected to a data line through a source electrode and a drain electrode of a TFT. Accordingly, the TFTs of a display part of a liquid crystal display panel are used as switching devices for apply electric fields to the liquid crystal in the liquid crystal cells from the data lines. Each of the gate electrodes of the TFTs is connected to a gate line, which allows pixel voltage signals from the data lines to be applied to the pixel electrodes in response to scan signals from the gate lines.
The driver circuits include a gate driver for driving the gate lines and a data driver for driving the data lines. The gate driver sequentially applies scan signals to the gate lines to sequentially drive the liquid crystal cells of the liquid crystal display panel. The data driver applies video signals to each data line whenever the gate signal is applied to any one of the gate lines. Accordingly, the light transmittance is controlled by way of the electric field applied between the pixel electrodes and the common electrode in accordance with the video signal, thereby displaying a picture on all of the liquid crystal cells of a liquid crystal display panel.
The TFT of a liquid crystal display panel can use an active semiconductor layer formed of amorphous silicon or polycrystalline silicon. An amorphous type liquid crystal display panel that uses TFTs with an amorphous silicon active layer has the advantages of all the TFTs across a matrix of liquid crystal cells having relatively the same electrical characteristics and being relatively stable in their electrical responsiveness. However, the low carrier mobility of the TFTs in an amorphous type liquid crystal display panel makes it difficult to improve pixel density. In the alternative, the poly-type liquid crystal display panel that uses TFTs with a polycrystalline silicon active layer has the advantage of higher pixel density because the polycrystalline silicon active layer has a high carrier mobility. Further, fabricating costs can be reduced because the driver circuits can be mounted on the same substrate as the liquid crystal display panel.
FIG. 1
is a plan view illustrating a configuration of a poly-type liquid crystal display in the related art. As shown in
FIG. 1
, a liquid crystal display device includes a liquid crystal display panel
10
with a gate driver
12
for driving gate lines GL
1
to GLn of the liquid crystal display panel
10
and a data driver
14
for driving data lines DL
1
to DLm of the liquid crystal display panel
10
. The gate driver
12
sequentially drives the gate lines GL
1
to GLn with gate control signals in horizontal periods for each frame of a video signal. The gate driver
12
turns on the TFTs in a horizontal line, so as to allow the data lines DL
1
to DLm to be connected to a horizontal row of liquid crystal cells.
The data driver
14
of the liquid crystal display device in
FIG. 1
takes samples of a plurality of digital data signals and converts the sampled signals into analog data signals for each horizontal period. The data driver
14
applies the analog data signals to the data lines DL
1
to DLm. Accordingly, the liquid crystal cells connected to the turned-on TFTs control the light transmittance in response to the data signals from the data lines DL
1
to DLm, respectively.
The liquid crystal display device of
FIG. 1
also includes multiplexers MUX
1
to MUXk connected between the data driver
14
and the data lines DL
1
to DLm. Each multiplexer MUX
1
to MUXk is connected to a plurality of data lines, such as the three data lines DLi to DLi+2. Each multiplexer MUX
1
to MUXk sequentially applies the video signals, which are supplied from the data driver
14
through a data input line DILi, to three data lines DLi to DLi+2 in accordance with a first to a third control signal supplied through a first to a third control line CL
1
to CL
3
. To this end, each multiplexer MUX
1
to MUXk includes three switching devices SW
1
to SW
3
each connected between a data input line DILi connected to the data driver
14
and respective one of three data lines DLi to DLi+2. Each switching device SW
1
to SW
3
is normally implemented as an MOS transistor. Each of three switching devices SW
1
to SW
3
included in the multiplexer MUX receives the first to third control signals at each gate electrode of the switching devices SWi. The first to third control signals have an enable interval, where the control signals progress sequentially to each other and repeatedly, such as an interval of high logic. Accordingly, three switching devices SW
1
to SW
3
included in the multiplexer are sequentially turned on for each horizontal period to allow the three data lines DLi to DLi+2 to be connected to the data input line DILi, which is connected to the data driver
14
. The multiplexers MUX
1
to MUXk are formed within the liquid crystal display panel
10
together with a picture display part
16
. Typically, the multiplexers MUX
1
to MUXk are located adjacent to the picture display part
16
of the liquid crystal display panel
10
.
The picture display part
16
has groups of red R, green G and blue B pixels. Each of the red R, green G and blue B pixels consists of a liquid crystal cell with a thin film transistor and liquid crystal. A color filter provided in liquid crystal cell of either red, green and blue respectively defines a red R, green G and blue B pixel.
A fabricating process of such a liquid crystal display panel is divided into a substrate patterning process, an alignment film forming process and a substrate bonding/liquid crystal injection process. The substrate patterning process is subdivided into a patterning process of an upper substrate and a patterning process of a lower substrate. The upper substrate is provided with a black matrix, a color filter and a common electrode. The lower substrate is provided with signal lines, such as the data lines and gate lines, and TFTs for the liquid crystal cells. Subsequently, pixel electrodes are provided for each of the pixel cells. In addition, a plurality of multiplexers for driving the data lines on a basis of time-division is also formed on the lower substrate. Subsequently, an alignment film is formed on either or both the common electrode and the pixel electrodes.
In the substrate bonding/liquid crystal injection process, a sealant is applied to one of the upper and lower substrate. The upper and lower substrates are then bonded together while leaving a hole for injection of liquid crystal between the upper and lower substrates. After the liquid
Jang Jeong Woo
Park Jae Deok
LG.Philips LCD Co. , Ltd.
Morgan & Lewis & Bockius, LLP
Parker Kenneth
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