Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-07-02
2002-01-01
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S096000
Reexamination Certificate
active
06335719
ABSTRACT:
This application claims the benefit of Korean Patent Application No. P98-27035, filed on Jul. 4, 1998, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a technique for driving a liquid crystal panel in a liquid crystal display device, and more particularly to a liquid crystal panel driving method for driving a liquid crystal panel in a dot inversion system and an apparatus thereof.
2. Description of the Related Art
Generally, a liquid crystal display device controls the light transmissivity of liquid crystal cells in a liquid crystal panel to display a picture corresponding to a video signal. Such a liquid crystal display device uses three driving methods, such as a frame inversion system, a line inversion system and a dot inversion system, so as to drive the liquid crystal cells in the liquid crystal panel.
In a liquid crystal panel driving method of the frame inversion system, polarities of data signals applied to the liquid crystal cells are inverted whenever the frame is changed. In a liquid crystal panel driving method of the line inversion system, polarities of data signals applied to the liquid crystal cells are inverted in accordance with lines on the liquid crystal panel, that is, gate lines. In a liquid crystal panel driving method of the dot inversion system, data signals having polarities contrary to the adjacent liquid crystal cells on the gate lines and to the adjacent liquid crystal cells on the data lines are applied to each liquid crystal cell in the liquid crystal panel, and the polarities of data signals applied to all liquid crystal cells in the liquid crystal panel are inverted every frame. In other words, in the dot inversion system, data signals are applied to the liquid crystal cells in the liquid crystal panel in such a manner that the positive (+) polarity and the negative (−) polarity appear alternately, as shown in
FIG. 1
, as the data signals go from the liquid crystal cell at the left upper end into the liquid crystal cells at the right side and into the liquid crystal cells at the lower side when a video signal in the odd-numbered frame is displayed; while data signals are applied to the liquid crystal cells in the liquid crystal panel in such a manner that the positive (+) polarity and the negative (−) polarity appear alternately, as shown in
FIG. 2
, as the data signals go from the liquid crystal cell at the left upper end into the liquid crystal cells at the right side and into the liquid crystal cells at the lower side when a video signal in the even-numbered frame is displayed.
The dot inversion system in the above three liquid crystal panel driving methods allows data signals having polarities contrary to data signals applied to the liquid crystal cells adjacent in the vertical and horizontal direction to be applied to certain liquid crystal cells, and thus provides a better quality of picture compared with the frame and line inversion systems. Due to this advantage, a liquid crystal driving method of the dot inversion system has been mainly used in the industry.
However, a specific pattern, for example, a check pattern, a subpixel pattern or a windows shut-down mode pattern, may be displayed when the liquid crystal panel driving method of the dot inversion system is used. In this case, a frame inversion effect appears in the liquid crystal panel driving method of dot inversion. Depending on the images being displayed, a flicker may be generated and the picture quality is deteriorated in a picture displayed by the liquid crystal panel driving method of the dot inversion system. For example, when a potential difference between data signals applied to liquid crystal cells indicated with the oblique lines and the remaining cells in the liquid crystal cells in the liquid crystal panel as shown in
FIG. 3
is large, only liquid crystal cells indicated with the oblique lines are assumed to be driven in a pattern having the polarities inverted every frame. In other words, only liquid crystal cells indicated with the oblique lines in
FIG. 3
seem to be driven with the frame inversion system. Due to this, in the liquid crystal panel driving method of the dot inversion system, a flicker noise emerging on the screen is dictated by a picture pattern. As a result, the picture quality displayed by the liquid crystal panel driving method of the dot inversion system is inconsistent.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a liquid crystal panel driving method and apparatus that is adaptive for stably keeping picture quality independently of a picture pattern as well as improving picture quality.
In order to achieve these and other objects of the invention, a liquid crystal panel driving method according to one aspect of the present invention includes the steps of dividing a liquid crystal panel into a plurality of blocks; responding liquid crystal cells included in each block to data signals having polarities contrary to the adjacent liquid crystal cells; responding to each of the liquid crystal cells included in each block are data signals having polarities contrary to data signals applied to the liquid crystal cells included in the adjacent blocks; and responding in all liquid crystal cells in the liquid crystal panel are data signals having opposite polarities every predetermined interval.
A liquid crystal panel driving apparatus according to another aspect of the present invention includes signal coupling means for applying data signals to the liquid crystal panel in such a manner that the liquid crystal cells are driven by one line unit; and polarity control means for controlling the data signals applied to the liquid crystal panel in such a manner that the liquid crystal panel is divided into a plurality of blocks and that each block responds to data signals having polarities contrary to the data signals applied to the adjacent blocks.
A liquid crystal display device according to still another aspect of the present invention includes a liquid crystal panel having picture elements and transistors connected to each of the picture elements, said picture elements being positioned at intersections in which a plurality of gate lines cross a plurality of source lines; a gate driver, connected to the plurality of gate lines, for sequentially applying a scanning signal to the gate lines; and a source driver for supplying data voltages to the plurality of source lines in such a manner that the liquid crystal panel is divided into a plurality of blocks, that the polarities of data voltages applied to the picture elements adjacent to each other in the horizontal and vertical direction within each block are contrary to each other, and that a polarity arrangement of the data voltages applied between the blocks adjacent in the horizontal and vertical direction is contrary to each other.
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.
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.
REFERENCES:
patent: 4842371 (1989-06-01), Yasuda et al.
patent: 5648793 (1997-07-01), Chen
patent: 5886679 (1999-03-01), Matsuda et al.
patent: 6020870 (2000-02-01), Takahashi et al.
patent: 6075507 (2000-06-01), Miyahara et al.
An Kil Bum
Moon Bem Jin
LG. Philips LCD Co. Ltd.
Long Aldridge & Norman LLP
Patel Nitin
Shalwala Bipin
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