KR100493376B1 - In-plane switching mode liquid crystal display device - Google Patents

Abstract

The present invention is to provide a transverse electric field type liquid crystal display device which can improve brightness by removing the foreground by changing the overlap form between the common electrode and the data electrode according to the rubbing direction. The display device includes a common wiring formed in the same direction as the gate wiring in a pixel area defined by a data wiring and a gate wiring, a plurality of common electrodes branched from the common wiring, and data formed at a predetermined distance from each of the common electrodes. In a transverse electric field type liquid crystal display device having an electrode and rubbed in a first direction, an electric field formation direction between the data electrode and the common electrode is overlapped with the rubbing direction by overlapping an edge portion of the data electrode inside the common electrode. It is characterized by matching.

Description

In-plane switching mode liquid crystal display device

The present invention relates to a liquid crystal display device, and more particularly to a transverse electric field type liquid crystal display device.

One of the display devices, Cathode Ray Tube (CRT) has been used mainly for monitors such as TVs, measuring devices, information terminal devices, etc., but the size and weight of CRT itself make it necessary to reduce the size and weight of electronic products. Couldn't respond positively.

In order to replace the CRT, liquid crystal display (LCD), which has the advantages of light and thin, has been actively developed, and recently, the liquid crystal display (LCD) has been developed enough to perform a role as a flat panel display device. Demand is on the rise.

In general, a low cost and high performance thin film transistor liquid crystal display (TFT-LCD) uses an amorphous silicon thin film transistor as a switching device. Currently, the liquid crystal display device is a VGA (Video Graphic Array; maximum resolution is 640 x 480 pixels). It aims at high resolution with SVGA (800 × 600) and XVGA (1024 × 768).

The development of the TFT-LCD industry and its application has been accelerated by the increase in size and the increase in resolution, and much effort has been made in terms of simplification of the manufacturing process and improvement of yield for the purpose of increasing productivity and low cost.

Such TFT-LCDs are currently required to have a large area, but there is a problem of changing the contrast ratio according to the viewing angle. To solve this problem, a twisted nematic liquid crystal display equipped with an optical compensation plate is provided. Various liquid crystal display devices such as devices, multi domain liquid crystal display devices, and the like have been proposed. However, it is still difficult to solve the problem that the contrast ratio decreases and the color changes depending on the viewing angle.

Accordingly, in order to realize a wide viewing angle, a transverse electric field type liquid crystal display device which controls an arrangement of liquid crystals by an electric field parallel to the substrate has been proposed.

1 is a plan view of a transverse electric field type liquid crystal display device according to the related art.

As shown in FIG. 1, the gate line 11 and the data line 13 are disposed in a vertical direction to define a plurality of pixel areas, and the common electrode 15 and the data electrode 17 are located in the pixel area. It is formed in a direction parallel to the data line 13. For reference, FIG. 1 illustrates only a unit pixel.

The common line 15a parallel to the gate line 11 is further formed in the pixel area, and the common electrode 15 integrated with the common line 15a is branched from the common line. The material of the common electrode 15 is made of metal, and the data electrode 17 is made of metal or transparent indium tin oxide (ITO). The common electrode 15 and the gate wiring 11 are formed in the same process, and the data wiring 13 and the data electrode 17 are formed in the same process.

As shown in the drawing, the conventional transverse electric field type liquid crystal display device has a portion ("A" to "H") in which the data electrode 17 and the common electrode 15 overlap in the pixel area. Although the overlapping edge portions form a right angle, this is only a design structure, and when the pattern is actually completed, as shown in FIG. 2, the overlapping edge portions have a round shape.

In this case, when the rubbing direction is taken into consideration, an area in which the distortion of the electric field occurs in the rubbing direction of the "A" region to the "H" region occurs.

In fact, when the rubbing direction is the direction shown in Fig. 2, even if the pattern states of the areas "A", "C", "F", and "H" have a round shape, the round is in the same direction as the rubbing direction. The electric field between the common electrode 15 and the data electrode 17 in the region is also the same as the rubbing direction. On the contrary, since the patterns of the regions "B", "D", "E", and "G" are rounded in the direction opposite to the rubbing direction, the electric field is also formed in the direction opposite to the rubbing direction. In the regions "D", "E", and "G", since the direction of rotation of the liquid crystal is reverse to the rubbing direction, a disclination occurs in the portion.

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3A is a cross-sectional view taken along the line II ′ of FIG. 1, and FIG. 3B is a cross-sectional view taken along the line II-II ′ of FIG. 1. As shown in the drawing, the transverse electric field type liquid crystal display device according to the prior art includes a first substrate 10, a common wiring 15a formed on the first substrate 10, and a common wiring 15a. A plurality of common electrodes branched in a direction orthogonal to each other, a gate insulating film 16 formed on the entire surface of the first substrate 10 including the common wiring 15a, and formed on the gate insulating film 16. And a data electrode 17 overlapping a predetermined portion 15. For reference, S1 of FIGS. 3A and 3B shows an overlap area between the common electrode 15 and the data electrode 17, and L1. Denotes the distance between the edge of the common electrode 15 and the edge of the data electrode 27.

A second difference (not shown) facing the first substrate 10 includes a light difference for preventing light leakage from the data wiring 13, the gate wiring 11, and the thin film transistor formed on the first substrate 10. A single layer (not shown) and a color filter layer (not shown) for expressing color are formed, and a liquid crystal layer (not shown) is formed between the first substrate 10 and the second substrate.

The operation of the transverse electric field type liquid crystal display device according to the related art is as follows.

When a driving voltage is applied from an external driving circuit (not shown), a transverse electric field parallel to the substrate is generated between the data electrode 17 and the common electrode 15. Accordingly, the liquid crystal molecules oriented in the liquid crystal layer rotate in a state parallel to the substrate according to the transverse electric field, and as a result, the amount of light passing through the liquid crystal layer is controlled. At this time, since the gray scale display is driven while the liquid crystal molecules are parallel to the substrate, the difference in the light transmittance according to the viewing angle is reduced.

However, in the conventional transverse electric field type liquid crystal display as described above, since the edges of the data electrode and the common electrode formed in the pixel region overlap each other regardless of the rubbing direction, a portion in which an electric field is formed in a direction opposite to the rubbing direction occurs. Therefore, the foreground (Disclination) occurs in the portion, there was a problem that the brightness is reduced accordingly.

The present invention has been made to solve the above-described problems of the prior art, and the transverse electric field type liquid crystal display which can improve luminance by eliminating the foreground by changing the overlap form between the common electrode and the data electrode according to the rubbing direction. The purpose is to provide a device.

According to an aspect of the present invention, a transverse electric field type liquid crystal display device includes a common wiring formed in the same direction as the gate wiring in a pixel region defined by a data wiring and a gate wiring, and a plurality of common branches branched from the common wiring. A transverse electric field type liquid crystal display device having an electrode and a data electrode formed at a predetermined distance from each of the common electrodes, wherein the edge portion of the data electrode overlaps the inside of the common electrode in the rubbing field type liquid crystal display device. The electric field forming direction between the data electrode and the common electrode is made to coincide with the rubbing direction.

Such a transverse electric field type liquid crystal display device of the present invention determines the overlap position between the common electrode and the data electrode in consideration of the rubbing direction, thereby preventing the electric field from being formed in the opposite direction to the rubbing direction, thereby eliminating the phenomenon of disclination. There is a characteristic.

To this end, the edge portion of the data electrode of the portion where the electric field can be generated in the direction opposite to the rubbing direction is disposed inside the electrode.

Hereinafter, the transverse electric field type liquid crystal display device of the present invention will be described with reference to the accompanying drawings.

4 is a plan view of a transverse electric field type liquid crystal display device according to an exemplary embodiment of the present invention.

As shown in FIG. 4, the data wiring 33 and the gate wiring 31 are vertically and horizontally disposed on the first substrate to define a pixel region, and the data wiring 33 and the gate wiring 31 intersect each other. The thin film transistor TFT is formed at the site. A plurality of common electrodes 35 are formed in the pixel area in the same direction as the data lines 33 by branching in the direction perpendicular to the common wiring 35a and the common wiring 35a. The data electrode 37 is formed at a predetermined distance from the substrate 35. The common electrode 35 is formed of the same material, for example, metal or indium tin oxide (ITO), on the same plane as the gate wiring 31. The data electrode 37 is formed of the same material, for example, metal or ITO, on the same plane as the data line 33.

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At this time, when the rubbing direction is the direction (a direction) shown in the drawing, the data electrodes of the portions ("B", "D", "E", and "G") in which the electric field is formed in the opposite direction to the rubbing direction in the past (37) The data electrode of the portion ("A", "C", "F", "H") where the edge portion is positioned inward of the common electrode 35 and the electric field is formed in the same direction as the rubbing direction ( The edge portion of the 37 is positioned outside the common electrode 35. Thus, as shown in the plan view of FIG. 5, the common electrode 35 and the data electrode 37 in the region where the common electrode and the data electrode overlap. The electric field between) is formed in the same direction with respect to the rubbing direction.

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Here, the reason for changing the electric field direction by changing the overlap positions of the common electrode 35 and the data electrode 37 will be described in contrast with the prior art.

FIG. 6A illustrates the electric field direction (arrow) between the common electrode and the data electrode according to the prior art, and FIG. 6B illustrates the electric field direction between the common electrode and the data electrode according to the present invention.

In the prior art having an edge portion of the data electrode 37 positioned outside the common electrode 35 as shown in FIG. 6A, an electric field is formed between the round portion of the data electrode and the common electrode adjacent thereto. The direction of is changed in the direction opposite to the rubbing direction along the electric field direction.

On the other hand, in the present invention in which the edge portion of the data electrode 37 is located inside the common electrode 35 as shown in FIG. 6B, the direction of the liquid crystal does not change with respect to the rubbing direction, so that the direction of the liquid crystal also coincides with the rubbing direction. .

In this way, the edge portions of the data electrodes 37 overlapping the common electrodes 35 are arranged inward (parts in which an electric field opposite to the rubbing direction is formed) and outward (in the same direction as the rubbing direction) relative to the common electrode 35. By selectively forming the electric field, the electric field can be formed in the same direction as the rubbing direction in all edge portions of the data electrode 37 overlapping the common electrode 35 as shown in FIG. 5. .

That is, in the state in which the pattern is completed, even if the edge portion of each pattern has a round shape, since the round is formed in the same direction as the rubbing direction, the foreground does not occur because the rotation direction of the liquid crystal has a forward direction with respect to the rubbing direction. .

If the rubbing direction is in the b direction, the overlapping position of the data electrode 37 and the common electrode 35 will be changed as shown in FIG. 7.

That is, as shown in Fig. 7, the edge portion of the data electrode 37 of the portion ("A", "C", "F", "H") in which the electric field is formed in the direction opposite to the rubbing direction (b direction) Is positioned inside the common electrode 35, and the edge portion of the data electrode 37 of the portion ("B", "D", "E", "G") in which an electric field is formed in the same direction as the rubbing direction is Located outside the common electrode 35.

8A is a cross-sectional view taken along the line II ′ of FIG. 4, and FIG. 8B is a cross-sectional view taken along the line II-II ′ of FIG. 4, and shows a data electrode 37 in a portion in which an electric field is formed in the same direction as the rubbing direction. The edge portion of) is positioned outside the common electrode 35, and the edge portion of the data electrode 37 of the portion in which the electric field is formed in the same direction as the rubbing direction is positioned inside the common electrode 35. Here, reference numeral 36 denotes a gate insulating film.

In the above embodiment, the data electrode 37 is patterned to have a structure in which an edge portion of the data electrode 37 is selectively formed inside or outside of the common electrode 35 in consideration of the rubbing direction, but the common electrode 35 The above-described structure may be realized by patterning the above-described structure. The reference numeral “35a” described above is a common wiring formed parallel to the gate wiring, and the common electrode 35 is formed by branching from the common wiring 35a. .

Meanwhile, in the present exemplary embodiment, when the data electrode is patterned while the common electrode is patterned, the overlapping position of the data electrode is determined in consideration of the rubbing direction. However, when patterning the common electrode, the rubbing direction is already taken into consideration. Afterwards, the data electrode may be patterned in a normal manner to implement the above effects.

As described above, the transverse electric field type liquid crystal display device of the present invention has the following effects.

By determining the overlap position between the common electrode and the data electrode in consideration of the rubbing direction, since the edge portions of the pattern are rounded in the same direction as the rubbing direction in the state where the pattern of the common electrode and the data electrode is completed, the foreground (Disclination) ) Does not occur, and the luminance can be improved accordingly.

1 is a plan view of a transverse electric field type liquid crystal display device according to the related art

2 is a plan view of a transverse electric field type liquid crystal display device according to the related art, and shows a direction of an electric field according to a pattern deformation.

3A is a cross-sectional view taken along the line II ′ of FIG. 1.

3B is a cross-sectional view taken along the line II-II 'of FIG. 1.

4 is a plan view of a transverse electric field type liquid crystal display device according to the present invention;

5 is a plan view of a transverse electric field type liquid crystal display device according to an exemplary embodiment of the present invention, illustrating a direction of an electric field according to a pattern deformation.

6a to 6b are comparative drawings of the related art for explaining the transverse electric field type liquid crystal display device of the present invention.

7 is a plan view of a transverse electric field type liquid crystal display device according to an embodiment of the present invention, in which a rubbing direction is changed.

8A is a cross-sectional view taken along the line II ′ of FIG. 4.

8B is a cross-sectional view taken along the line II-II 'of FIG. 4.

Explanation of symbols for main parts of the drawings

31: gate wiring 33: data wiring

35 common electrode 37 data electrode

Claims (3)

A transverse electric field rubbing in a first direction, having a plurality of common electrodes formed in the same direction as the data lines in the pixel region defined by the data lines and the gate lines, and data electrodes formed at a predetermined distance from the common electrodes; In the type liquid crystal display device, In the part where the electric field is formed in the direction opposite to the rubbing direction, the edge portion of the data electrode overlaps the inside of the common electrode to form the edge portion of the common electrode in a round structure. In the portion where the electric field is formed in the same direction as the rubbing direction, the edge portion of the data electrode is overlapped to the outside of the common electrode to form the edge portion of the data electrode in a round structure. And a direction in which an electric field is formed between the data electrode and the common electrode coincides with the rubbing direction. delete The transverse electric field liquid crystal display device according to claim 1, wherein the common electrode is formed of the same material on the same plane as the gate wiring.