Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1998-06-05
2001-12-25
Wu, Xiao (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S100000, C345S088000
Reexamination Certificate
active
06333729
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a liquid crystal display device employing thin film transistors (“TFTs”), used as a switch matrix, and more particularly to a liquid crystal display device adapted to be driven with digital video data.
2. Description of the Prior Art
Recently, there has been used a signal transfer system changing of an analog image signal into a digital image signal feasible to the compression of information, in order to provide the high resolution picture with a viewer. A liquid crystal display panel has been developed that may be driven with the digital image signal instead of the existing analog image signal.
An digital-type liquid crystal display apparatus based on this development, as shown in
FIG. 1
, comprises a gate driver
12
for driving gate lines GL of a liquid crystal display panel, and a number of data driver integrated circuit, hereinafter referred simply to as “ID-IC”, for time-divisionally driving data lines DL of the liquid crystal display panel
10
. In the liquid crystal display panel
10
, the TFTs, although not shown, are located at in intersections of the gate lines GL with the data lines DL, and liquid crystal cells are connected to each of these TFTs. The gate driver
12
drives the gate lines GL sequentially for the horizontal scanning interval every frame period through a gate control signal. In other words, the gate driver
12
sequentially drives the TFTs included in the liquid crystal panel
10
for every one line. Further, the D-ICs
14
convert video data into analog data signals every horizontal scanning interval using a data control signal and applies the converted analog video signal to the data lines DL. Specifically, each of the D-ICs
14
input video data corresponding to its input lines and converts the input video data into analog video signals. Also, each of the D-ICs
14
supplies the analog video signals to the data lines DL connected to the output line thereof. Accordingly, liquid crystal cells for a single line connected to the TFTs for that line control the light transmissivity in accordance with a voltage level of that line.
In the digital-type liquid crystal display apparatus having a configuration described above, since the D-ICs
14
drive the data lines corresponding to their output terminal, it has a disadvantage in that a great number of D-ICs are required, and that, hence, the circuit configuration and volume becomes large.
In order to overcome such a disadvantage in the conventional digital-type liquid crystal display apparatus, there has been suggested a liquid crystal display apparatus using time division demultiplexing. Examples of this liquid crystal display apparatus of time division system include one disclosed, in an article published in the 1993 edition of the IEEE Journal, titled “An LCD Addressed by a-Si:H TFTs with Peripheral poly-Si TFT Circuit” by Tanaka et al., and an article published, through “Euro Display '96”, titled “Ar
+
Laser Annealed Poly-Si TFT for Large Area LCDs” by Kato et al. According to these articles, the time divisional liquid crystal display apparatus improves the ON/OFF speed of TFTs by forming the TFTs to have a dual layer of a polycrystalline Si and an amorphous Si. Further, the time divisional liquid crystal display apparatus allows date lines to be time-divisionally driven by inserting a demultiplexer between output terminals of each of D-ICs and the data lines. According, the time divisional liquid crystal display apparatus could reduce a required amount of D-ICs into below half.
In the time divisional liquid crystal display apparatus, however, since the demultiplexer switches the data lines, the distance between data lines driven with a single demultiplexer becomes large. This causes a complication in the wiring arrangement of the liquid crystal display panel as well as a distortion of video signal. Also, since D-ICs have to sample video data for one line sequentially, sampling clocks with a frequency corresponding to the number of video data for one line should be supplied to the D-ICs.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a liquid crystal display apparatus which can simplify a circuit configuration and a wiring structure thereof.
It is other object of the present invention to provide a liquid crystal display apparatus which can retard a sampling period of video data.
In order to obtain said objects of the invention, a liquid crystal display apparatus according to an aspect of the present invention comprises: (1) a liquid crystal panel in which picture element cells are arranged at each of intersections of a plurality of data lines with a plurality of gate lines; (2) a first data driver circuit for supplying a plurality of video signals; (3) a second data driver circuit for supplying a plurality of video signals; and (4) a plurality of demultiplexing circuit each receiving a respective one of the video signals supplied from a respective one of the first and second data driver circuits and selectively outputting the respective video signals to a respective group of said plurality of data lines.
Furthermore, a liquid crystal display apparatus according to another aspect of the present invention comprises: (1) a liquid crystal panel in which red, green, and blue picture element cells are arranged at intersections of a plurality of data lines with a plurality of gate lines, the red, green, and blue picture elements being repeated in a horizontal axis thereof; (2) a first data driver circuit for supplying a plurality of video signals; (3) a second data driver circuit for supplying a plurality of video signals; and (4) a plurality of demultiplexing circuits each receiving a respective one of the video signals supplied from a respective one of the first and second data driver circuits and selectively outputting the respective video signal to a respective group of said plurality of data lines.
Furthermore, a liquid crystal display apparatus according to still another aspect of the present invention comprises: (1) a liquid crystal panel in which picture element cells are arranged at each of a plurality of intersections of n data lines with m gate lines, where n and m are positive intergers; (2) a plurality of multiplexing means, n divided by p in number, each said multiplexing means for outputting a data signal to p of the n data lines, where p is a positive integer less than n; and (3) data driver circuits, q in number, for time divisionally driving the plurality of demultiplexing means, where q is a positive integer.
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Finnegan Henderson Farabow Garrett & Dunner L.L.P.
LG Electronics Inc.
Wu Xiao
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