KR100658072B1 - Fringe field switching mode lcd - Google Patents

Abstract

The present invention discloses a fringe field driving liquid crystal display having high transmittance and high opening ratio. The disclosed invention includes a data bus line and a gate bus line intersecting on a lower substrate to define a unit pixel; A TFT disposed near an intersection of the data bus line and the gate bus line and serving as a switching; A slit pixel electrode comprising a plate type counter electrode and a plurality of branches, the plate type counter electrode being overlapped with an insulating layer interposed therebetween to generate a fringe field; An upper substrate disposed to face the lower substrate and having a plurality of color filter layers and a black matrix; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; And first and second alignment layers disposed on inner surfaces of the upper and lower substrates, respectively, and having a predetermined rubbing axis, and further extending the pixel electrode portions disposed adjacent to the data bus lines to overlap the data lines. The counter electrode is also extended to be disposed adjacent to the data bus line, and the rubbing axis of the second alignment layer has an angle between 0 and 45 degrees with the fringe field when the liquid crystal molecules have negative dielectric anisotropy. In the case of positive dielectric anisotropy, it is characterized by having an angle between 45 and 90 degrees.

Description

Fringe field drive liquid crystal display {FRINGE FIELD SWITCHING MODE LCD}

1A is a plan view illustrating a fringe field driving liquid crystal display according to the related art.

1B is a view for explaining the electrode structure of the fringe field driving liquid crystal display device according to the prior art.

2 is a voltage distribution field distribution diagram according to the prior art;

3A is a plan view showing a fringe field driving liquid crystal display device according to the present invention;

3B is a view for explaining the electrode structure of the fringe field driving liquid crystal display device according to the present invention.

4A is a voltage distribution field distribution diagram in accordance with the present invention.

4B is an electric field distribution diagram of adjacent pixels according to the present invention;

5A through 5B are structural diagrams of pixel electrodes according to another exemplary embodiment of the present invention.
* Description of the symbols for the main parts of the drawings *

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1: gate bus line 3: data bus line

11: Common Bus Line 13: Thin Film Transistor (TFT)

15: pixel electrode 17: counter electrode

19: black matrix

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fringe field driving liquid crystal display (FFS-LCD), and more particularly, to a fringe field driving liquid crystal display having a high opening ratio, a high transmittance, and a wide viewing angle.

In general, FFS mode-LCD is proposed to improve the low aperture ratio and transmittance of general IPS (In-Plane Switching) mode LCD, and has already been filed in Korean Patent Application No. 98-9243.

Since the fringe field switching mode uses a fringe field, the liquid crystal is operated by forming a field in a pixel adjacent to a data bus line to which a driving signal is not applied, and light is leaked by such an unnecessary electric field. cross talk).

To solve this problem, the width of the black matrix was extended and shielding metals were placed at the edges of the counter electrodes, that is, adjacent to the data bus lines.

1A is a plan view illustrating a fringe field driving liquid crystal display according to the related art, in which a gate pixel line 1 and a data bus line 3 vertically intersect on a lower substrate made of glass to define a unit pixel, The thin film transistor 13 serving as a switching role is disposed near the intersection point. On the unit pixel area, a plate-shaped counter electrode 7 and a pixel electrode 5 having a plurality of branches overlap each other. The common bus line 11 is disposed in contact with the edge of the counter electrode 7 and periodically applies a common signal. The black matrix 9 is disposed on an upper substrate (not shown) corresponding to the edge of the pixel electrode 5.

FIG. 1B is a cross-sectional view taken along the line AA ′ of FIG. 1A, and a shielding metal 8 is disposed at the edge of the plate-shaped counter electrode 7 on the lower substrate 10b. The black matrix 9 arranged to correspond to the data bus line 3 is extended to correspond not only to the shielding metal 8 but also to an edge portion of the pixel electrode 5. Although not shown, 6 denotes an insulating film.

In addition, a first alignment film and a second alignment film (not shown) are coated on the inner surfaces of the upper and lower substrates 10a and 10b, and the rubbing axis of the second alignment film is a liquid crystal molecule having negative dielectric anisotropy, It has an angle between 0 and 45 degrees with the fringe field, and when it has positive dielectric anisotropy, it is characterized by having an angle between 45 and 90 degrees.

FIG. 2 is a voltage distribution field distribution diagram according to the prior art. When a driving signal is applied along a gate bus line, as shown in FIG. A strong fringe field 13 is formed between 5). The field is also formed in the portion adjacent to the data bus line 3, but light leakage is blocked by the expanded black matrix 9.

In addition, the shielding metal 8 disposed at the edge of the counter electrode 7 adjacent to the data bus line 3 prevents light leakage due to cross talk with adjacent pixels not receiving a data signal. give. Although not shown in the figure, 14 denotes a liquid crystal molecule.

However, the fringe field driving liquid crystal display extended the black matrix of the upper substrate by arranging the shielding metal for preventing the cross talk, which caused a decrease in the aperture ratio.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and the pixel electrode is improved so that the transmittance and aperture ratio can be improved while eliminating the shielding metal without expanding the black matrix as in the past to prevent cross talk. It is an object of the present invention to provide a fringe field driving liquid crystal display device that has been expanded or added, and that has widened the counter electrode.

In order to achieve the above object of the present invention, the present invention, the data bus line and the gate bus line arranged on the lower substrate cross-defined to define a unit pixel; A TFT disposed near an intersection of the data bus line and the gate bus line and serving as a switching; A slit pixel electrode comprising a plate type counter electrode and a plurality of branches, the plate type counter electrode being overlapped with an insulating layer interposed therebetween to generate a fringe field; An upper substrate disposed to face the lower substrate and having a plurality of color filter layers and a black matrix; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; And first and second alignment layers disposed on inner surfaces of the upper and lower substrates, respectively, and having a predetermined rubbing axis, wherein the pixel electrode portions disposed adjacent to the data bus lines are added or extended to overlap the data lines. The counter electrode is extended to be adjacent to the data bus line, and the rubbing axis of the second alignment layer has an angle between the fringe field and 0 to 45 degrees when the liquid crystal molecules have negative dielectric anisotropy, In the case of positive dielectric anisotropy, it is characterized by having an angle between 45 and 90 degrees.

Herein, the distance between the counter electrode and the data bus line is within 0 to 3 μm, and the counter electrode and the data bus line are disposed to be adjacent or overlapping with each other. The black matrix on the upper substrate facing the data bus line may be arranged to be reduced by overlapping the pixel electrode and the data bus line.

In addition, another object of the present invention is a data bus line and a gate bus line arranged on the lower substrate to define a unit pixel; A TFT disposed near an intersection of the data bus line and the gate bus line and serving as a switching; A plate-type counter electrode disposed on the unit pixel region with an insulating layer therebetween to generate a fringe field; A pixel electrode having branches corresponding to each other along a unit pixel central axis parallel to the data bus line; An upper substrate disposed to face the lower substrate and having a plurality of color filter layers and a black matrix; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; Overlapping with the data bus line by adding or expanding a pixel electrode portion disposed on the inner surface of the upper and lower substrates, the first and second alignment layers having a predetermined rubbing axis, and arranged adjacent to the data bus line; And the counter electrode is also extended to be adjacent to the data bus line, and the rubbing axis of the second alignment layer has an angle between 0 and 25 degrees with the fringe field when the liquid crystal molecules have negative dielectric anisotropy. In the case of positive dielectric anisotropy, the angle is between 45 and 70 degrees.
In addition, another object of the present invention is a data bus line and a gate bus line arranged on the lower substrate to define a unit pixel; A TFT disposed near an intersection of the data bus line and the gate bus line and serving as a switching; A plate-type counter electrode disposed on the unit pixel region with an insulating layer therebetween to generate a fringe field; A pixel electrode having branches corresponding to each other along a unit pixel central axis parallel to the gate bus line; An upper substrate disposed to face the lower substrate and having a plurality of color filter layers and a black matrix; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; Overlapping with the data bus line by adding or expanding a pixel electrode portion disposed on the inner surface of the upper and lower substrates, the first and second alignment layers having a predetermined rubbing axis, and arranged adjacent to the data bus line; And the counter electrode is also extended to be adjacent to the data bus line, and the rubbing axis of the second alignment layer has an angle between 0 and 25 degrees with the fringe field when the liquid crystal molecules have negative dielectric anisotropy. In the case of positive dielectric anisotropy, the angle is between 45 and 70 degrees.

According to the present invention, the branch-shaped pixel electrodes arranged at the edge of the unit pixel region are extended or added to overlap the data bus lines, and the counter electrodes are extended to be disposed adjacent to the data bus lines, thereby preventing cross talk. The aperture ratio can be improved.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.
3A is a plan view illustrating a fringe field driving liquid crystal display according to the present invention, in which a gate pixel line 1 and a data bus line 3 vertically intersect on a lower substrate made of glass to define unit pixels, The thin film transistor 13 serving as a switching role is disposed near the intersection point of the gate bus line 1 and the data bus line 3. On the unit pixel area, a plate-shaped counter electrode 17 is extended to be adjacent to the data bus line 3. The pixel electrode 15 having a plurality of branches overlapped on the counter electrode 3 is additionally disposed in a conventional shielding area so as to be adjacent to or overlap the data bus line 3. The black matrix 19 on the upper substrate disposed to correspond to the data bus line 3 is reduced to correspond to the portion of the extended pixel electrode 15.

FIG. 3B is a view for explaining the electrode structure of the fringe field driving liquid crystal display device according to the present invention, wherein the plate type counter electrode 17 on the lower substrate is disposed adjacent to the data bus line 3. The pixel electrode 15 is added to the edge of the unit pixel, that is, the portion adjacent to the data bus line 3. The distance between the data bus line 3 and the pixel electrode 15 is approximately 0 to 6 mu m, preferably 0 to 3 mu m. The black matrix 19 of the upper substrate corresponding to the data bus line 3 is reduced in size so as to correspond to the vicinity of the data bus line 3.

Although not shown, a first alignment layer and a second alignment layer are coated on inner surfaces of the upper and lower substrates 10a and 10b, and the rubbing axis of the second alignment layer is the fringe field when the liquid crystal molecules have negative dielectric anisotropy. And having an angle between 0 and 45 degrees, and having a positive dielectric anisotropy, the angle between 45 and 90 degrees with respect to the gate electrode direction.

The data bus line 3 and the pixel electrode 15 may be arranged to overlap each other at 0 μm or less, and overlap within 2/3 of the width of the data bus line 3.

4A is a voltage distribution field distribution diagram according to the present invention. When a data signal is applied through the pixel electrode 15, a strong fringe field 13 is formed in the pixel electrode 15 and the counter electrode 17 to form a liquid crystal. Actuates the molecules 14. Electric fields generated near the data bus line 3 and causing light leakage are blocked by the newly added and overlapping pixel electrode 15.

FIG. 4B is an electric field distribution diagram of adjacent pixels according to the present invention. As shown in FIG. 4B, a field for generating a cross talk in a pixel to which a signal is not applied is also added with a pixel electrode added instead of the position of a conventional shielding electrode. It is blocked by 15) and no light leakage occurs. In addition, if the black matrix 19 of the upper substrate is made of a metal material such as chromium (Cr) instead of resin, the pixel is not applied when electrically connected to the counter electrode 17 of the lower substrate 10b. Since liquid crystal drive due to field distortion between the electrode and the data bus electrode in the applied state can be reduced, light leakage can be reduced more reliably.

5A through 5B are structural diagrams of a pixel electrode according to another exemplary embodiment of the present invention. As shown in FIG. 5A through 5B, the structure of the pixel electrode is centered on a central axis of a unit pixel parallel to the data bus line 3. ) Branches to have a certain angle and correspond to the '∧' shape. In the same manner, in FIG. 5B, a branch of the pixel electrode 25b is formed at a predetermined angle to correspond to the gate bus line 1 at the center axis of the unit pixel parallel to the gate bus line 1. I had it.

The structure of the pixel electrode is a structure that can achieve a wide viewing angle by removing the color shift, and is the same as the electrode structure of the present invention described above, but the rubbing axis of the liquid crystal array is different.

Although not shown, first and second alignment layers are coated on inner surfaces of the upper and lower substrates, and the rubbing axis of the second alignment layer has an angle between 45 and 70 degrees with the fringe field when the liquid crystal molecules have positive dielectric anisotropy. And has an angle between 0 and 25 degrees when the liquid crystal molecules have negative dielectric anisotropy.

According to the present invention, the pixel electrodes are arranged to overlap up to a predetermined portion of the data bus line, and the counter electrodes are also disposed close to the data bus line so that there is no need to extend the black matrix, and no shielding metal is disposed, thereby preventing cross talk. And a fringe field drive liquid crystal display device capable of improving the aperture ratio.

As described in detail above, according to the present invention, the following effects are obtained.

The pixel electrode may be added or extended to overlap the data bus line, and the counter electrode may also be extended to be adjacent to the data bus line to improve the aperture ratio and prevent cross talk.

Various embodiments are obvious to those skilled in the art without departing from the spirit and spirit of the invention and can be easily invented. Thus, the claims appended hereto are not limited to those described above, and the claims are intended to cover all of the patented novelties inherent in this invention, and also to those skilled in the art to which this invention pertains. It includes all features processed evenly by the ruler.

Claims (8)

A data bus line and a gate bus line intersected on the lower substrate to define a unit pixel; A TFT disposed near an intersection of the data bus line and the gate bus line and serving as a switching; A slit pixel electrode comprising a plate type counter electrode and a plurality of branches, the plate type counter electrode being overlapped with an insulating layer interposed therebetween to generate a fringe field; An upper substrate disposed to face the lower substrate and having a plurality of color filter layers and a black matrix; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; And It is disposed on the inner surface of the upper and lower substrate, respectively, and includes a first and second alignment layer having a predetermined rubbing axis, A pixel electrode portion disposed adjacent to the data bus line is added or extended to overlap the data bus line, and the counter electrode is also extended to be disposed adjacent to the data bus line, The rubbing axis of the second alignment layer has an angle between 0 and 45 degrees with the fringe field when the liquid crystal molecules have negative dielectric anisotropy, and an angle between 45 and 90 degrees when the liquid crystal molecules have positive dielectric anisotropy. A fringe field drive liquid crystal display device. The method of claim 1, A fringe field drive liquid crystal display device, wherein the distance between the counter electrode and the data bus line is 0 to 3 µm. The method of claim 2, And a counter field and a data bus line overlapping each other. The method of claim 1, The extended pixel electrode overlaps with less than 2/3 of the width of the data bus line. The method according to claim 1 or 4, And a black matrix on the upper substrate facing the data bus line can be arranged in such a way that the pixel electrode and the data bus line overlap each other. The method of claim 1, The fringe field driving liquid crystal display device electrically connecting the counter electrode and the black matrix.         A data bus line and a gate bus line intersected on the lower substrate to define a unit pixel; A TFT disposed near an intersection of the data bus line and the gate bus line and serving as a switching; A plate-type counter electrode disposed on the unit pixel region with an insulating layer therebetween to generate a fringe field; A pixel electrode having branches corresponding to each other along a unit pixel central axis parallel to the data bus line; An upper substrate disposed to face the lower substrate and having a plurality of color filter layers and a black matrix; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; And It is disposed on the inner surface of the upper and lower substrate, respectively, and includes a first and second alignment layer having a predetermined rubbing axis, A pixel electrode portion disposed adjacent to the data bus line is added or extended to overlap the data bus line, and the counter electrode is also extended to be disposed adjacent to the data bus line, The rubbing axis of the second alignment layer has an angle between 0 and 25 degrees with the fringe field when the liquid crystal molecules have negative dielectric anisotropy, and an angle between 45 and 70 degrees when the liquid crystal molecule has positive dielectric anisotropy. A fringe field drive liquid crystal display device.         A data bus line and a gate bus line intersected on the lower substrate to define a unit pixel; A TFT disposed near an intersection of the data bus line and the gate bus line and serving as a switching; A plate-type counter electrode disposed on the unit pixel region with an insulating layer therebetween to generate a fringe field; A pixel electrode having branches corresponding to each other along a unit pixel central axis parallel to the gate bus line; An upper substrate disposed to face the lower substrate and having a plurality of color filter layers and a black matrix; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; And It is disposed on the inner surface of the upper and lower substrate, respectively, and includes a first and second alignment layer having a predetermined rubbing axis, A pixel electrode portion disposed adjacent to the data bus line is added or extended to overlap the data bus line, and the counter electrode is also extended to be disposed adjacent to the data bus line, The rubbing axis of the second alignment layer has an angle between 0 and 25 degrees with the fringe field when the liquid crystal molecules have negative dielectric anisotropy, and an angle between 45 and 70 degrees when the liquid crystal molecule has positive dielectric anisotropy. A fringe field drive liquid crystal display device.

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