Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2002-04-19
2004-12-21
Nguyen, Dung (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S143000
Reexamination Certificate
active
06833897
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an In-Plane Switching (IPS) mode liquid crystal display (LCD) device and, more particularly, to an IPS-LCD device with a color filter formed on an array substrate.
2. Description of the Related Art
In a conventional twisted nematic LCD (TN-LCD) device, liquid crystal molecules are twisted between two facing electrodes respectively formed on two substrates, in which an electric field is generated in an approximately vertical direction to the plane of the two substrates. To achieve the aim of wide viewing angle, an in-plane switching mode LCD (IPS-LCD) device has been proposed, in which common electrodes and pixel electrodes are formed on the same substrate (TFT array substrate) and an in-plane electric field therebetween is generated to rearrange the liquid crystal molecules along the in-plane electric field. Accordingly, the IPS-LCD device has been used for improving viewing angle, contrast ratio and color shift.
FIG. 1A
is a top view showing a conventional IPS-LCD device.
FIG. 1B
is a sectional diagram along line A—A shown in FIG.
1
A. The IPS-LCD device has an array substrate
10
, a color filter (CF) substrate
12
, and a liquid crystal layer
14
formed in a gap between the two parallel substrates
10
and
12
. On the array substrate
10
, a plurality of traverse-extending scanning electrodes
16
and a plurality of lengthwise-extending signal electrodes
18
are arranged in a matrix form to define rectangular-shaped pixel areas
20
. Also, in each pixel area
20
a strip-shaped pixel electrode
22
is disposed between two strip-shaped common electrodes
24
which are the branches of a common line
24
A, and both of the pixel electrode
22
and the common electrode
24
are parallel to the signal electrodes
18
. Moreover, each pixel area
20
has a thin-film transistor (TFT) structure
26
with a drain electrode electrically connected to the pixel electrode
22
. When a voltage is applied to electrodes, an in-plane electric field is produced between the pixel electrode
22
and the common electrode
24
.
In processing the array substrate
10
, the scanning electrodes
16
and the common electrodes
24
are patterned on the same level plane, and then covered by a gate insulating layer
17
. Next, the signal electrodes
18
and the pixel electrodes
22
are patterned on the gate insulating layer
17
. Thereafter, a first orientation layer
19
is formed to cover the entire surface of the array substrate
10
. On the CF substrate
12
, a plurality of black matrix layers
13
, a color resin layer
15
, and a second orientation layer
21
are successively stacked and faced to the liquid crystal layer
14
. This black matrix layer
13
is provided so as to hide the TFT structure
26
, the scanning electrode
16
, the signal electrode
18
, and the like with respect to the external field of this TFT structure
26
.
However, in the above structure, the common electrodes
24
and the pixel electrodes
22
are opaque to result in a low transmittance. Also, the common electrodes
24
adjacent to the signal electrode
18
, serving as shielding electrodes, are required to avoid a lateral field between the pixel electrode
22
and the signal electrode
18
. Therefore, in the area I, an aperature ratio is less than desired. Furthermore, in the area II, since a short by coupling the common line
24
A and the scanning electrode
16
in the manufacturing process is often generated, the yield is reduced.
SUMMARY OF THE INVENTION
The present invention is an IPS-LCD device having a color filter on the array substrate and a common electrode overlapping the signal electrode to solve the above-mentioned problems.
The in-plane switching mode liquid crystal display (IPS-LCD) device has a lower glass substrate and an upper glass substrate disposed parallel to each other. A plurality of transverse-extending scanning electrodes and a plurality of lengthwise-extending signal electrodes are patterned on the lower glass substrate to define a plurality of pixel areas. In each pixel area, at least a lengthwise-extending pixel electrode and at least two lengthwise-extending common electrodes are formed on the same level plane of the lower glass substrate, wherein the pixel electrode is disposed at the interval between the common electrodes. Also, a color resin layer is sandwiched between the signal electrodes and the common electrodes. Moreover, the common electrode is located over the signal electrode across two adjacent pixel areas.
Accordingly, it is a principle object of the invention to provide the color filter on the array substrate.
It is another object of the invention to avoid a lateral field generated between the signal electrode and the pixel electrode.
Yet another object of the invention is to prevent light leakage between the signal electrode and the common electrode.
It is a further object of the invention to achieve a high aperture ration in the IPS-LCD device.
Still another object of the invention is to reduce the coupling between the common electrode and the scanning electrode.
Another object of the invention is to avoid electron charges remaining on the electrodes so as to prevent the image-sticking problem.
It is an object of the invention to increase the yield.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.
REFERENCES:
patent: 5745207 (1998-04-01), Asada et al.
patent: 5852485 (1998-12-01), Shimada et al.
patent: 6177970 (2001-01-01), Kim
patent: 6208399 (2001-03-01), Ohta et al.
Lee Seok Lyul
Tanaka Sakae
Hannstar Display Corp.
Merchant & Gould P.C.
Nguyen Dung
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