Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-11-30
2004-03-16
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S037000, C349S043000
Reexamination Certificate
active
06707524
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fringe field switching (FFS) mode liquid crystal display (LCD), and in particular to an FFS mode LCD and a fabrication method therefor which can improve an image quality by separately aligning one pixel so that pixel voltages can offset each other to be a zero voltage.
2. Description of the Background Art
A conventional thin film LCD is used as an information display device such as an information display window of a portable terminal, a screen display of a notebook computer, and a monitor of a laptop computer.
Especially, the LCD can replace a general cathode ray tube type monitor (CRT), which has high industrial applicability.
In the conventional LCD is generated a remaining image of a previous frame for a few seconds. Even though a fixed image pattern is applied to the liquid crystal for a predetermined time and the image pattern is removed, the image pattern remains weakly for a predetermined time.
In an in plane switching (IPS) mode or a fringe field switching (FFS) mode for embodying a field angle wider than a general TN mode, the remaining image is maintained for a long time.
Ions are moved in one direction due to DC voltage elements transmitted in driving the liquid crystal, and thus a signal voltage is distorted to generate the remaining image.
Such a remaining image is frequently generated in the IPS mode LCD for driving the liquid crystal by forming electrodes on one substrate, as compared with the TN mode LCD for driving the liquid crystal by forming electrodes on upper and lower substrates.
The conventional FFS mode LCD will now be explained with reference to
FIGS. 1 and 2
.
FIG. 1
is a cross-sectional view illustrating a pixel structure of the conventional FFS mode LCD.
FIG. 2
is a plan view illustrating the pixel structure of the conventional FFS mode LCD.
The conventional FFS mode LCD forms a first transparent electrode Vcom;
4
on a glass substrate
2
, and forms an insulating film
6
thereon.
A second transparent electrode Vdd;
8
is formed on the insulating film.
A plus frame voltage and a minus frame voltage are applied to the pixel electrode
8
. Accordingly, the voltages offset each other, and an average voltage becomes zero.
However, slight DC elements are generally applied between the plug frame and the minus frame due to parasitic capacitance. Here, reference numeral
10
denotes gate lines, and
12
denotes data lines.
As described above, positive ions are moved in a cathode direction due to the DC elements, and fixed to a rear film in the cathode direction.
As a result, the signal voltage is distorted by the ions fixed to the rear film of the cathode electrode region. In the case of negative ions, the ions are moved in an anode direction, to cause the remaining image.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a fringe field switching mode liquid crystal display and a fabrication method therefor which can remove a remaining image due to a residual DC voltage, by dividing a fringe field switching mode pixel into at least two, and enabling the adjacent pixels to have opposite polarities, so that the voltages applied to the pixel has a zero voltage state.
In order to achieve the above-described object of the invention, there is provided a fringe field switching mode liquid crystal display, including: gate lines and data lines aligned on a transparent insulating substrate to vertically cross each other; common electrode lines aligned horizontally to the gate lines; a pixel region defined in a space formed by the gate lines and data lines; a first transparent electrode formed in the pixel region, and divided into at least two regions; and a second transparent electrode insulated from the first transparent electrode, and divided on the first transparent electrode as many as the first transparent electrode, a data voltage being applied to the second transparent electrode in a first region and to the first transparent electrode in a second region, a sum of the voltages applied to the pixel region having a zero voltage.
In addition, there is provided a method for fabricating a fringe field switching mode liquid crystal display having gate lines and data lines aligned on a transparent insulating substrate to vertically cross each other, common electrode lines aligned horizontally to the gate lines, a thin film transistor formed by a source and drain extended from the data line, and the gate line, and a pixel region defined in a space formed by the gate lines and data lines, including the steps of: forming a first transparent electrode in the pixel region to be divided into at least two regions; and forming a second transparent electrode to be insulated from the first transparent electrode and divided on the first transparent electrode as many as the first transparent electrode, a data voltage being applied to the second transparent electrode in a first region and to the first transparent electrode in a second region, a sum of the voltages applied to the pixel region having a zero voltage.
REFERENCES:
patent: 5448385 (1995-09-01), Deffontaines et al.
patent: 2001/0043303 (2001-11-01), Shibahara et al.
An Chi Wook
Ha Pyung Soo
Jung Hee Chul
Kim Chul Ha
Boe-Hydis Technology Co., Ltd.
Duong Tai
Ladas & Parry
Parker Kenneth
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