KR100717186B1 - fringe field switching mode liquid crystal display device - Google Patents

Abstract

The present invention discloses a fringe field drive liquid crystal display device. In the disclosed fringe field drive liquid crystal display device, a gate bus line and a data bus line are cross-aligned to limit unit pixels, and a transparent conductor is formed within the unit pixels. Fringe-field driven liquid crystal display in which a common thin film transistor substrate in which a common electrode of a common electrode type and a slit type pixel electrode of a transparent conductor are overlapped with an insulating layer interposed therebetween is bonded to a color filter substrate through a liquid crystal. In the apparatus, the slit of the pixel electrode is inclined to extend along the gate busline direction, and divided into three along the gate busline direction, wherein the slit portions disposed at both edges of the three divided slit portions are disposed in the center. It has a larger slit angle relative to the gate busline than the slit portion. The. According to the present invention, the slit of the pixel electrode is divided into three along the gate busline direction, and the data at both edge portions of the pixel electrode are increased by making the slit angle of both edge portions larger than the slit angle of the center portion with respect to the gate busline. It is possible to prevent the liquid crystal drive from being affected by unwanted field components such as bus lines.

Description

Fringe field switching mode liquid crystal display device

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view schematically showing a lower array substrate of a fringe field drive liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a plan view schematically illustrating a lower array substrate of a fringe field driving liquid crystal display device according to a second embodiment of the present invention. FIG.

3 is a plan view schematically showing a lower array substrate of a fringe field drive liquid crystal display device according to a first embodiment of the present invention;

4 is a plan view schematically showing a lower array substrate of a fringe field driving liquid crystal display device according to a second embodiment of the present invention.

5 is a graph showing the voltage vs. the absolute transmittance according to the change in the slit angle of the pixel electrode.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fringe field driving liquid crystal display device, and more particularly, to change the structure of the pixel electrode so as not to be affected by liquid crystal driving from unwanted field components such as data bus lines at both edge portions of the pixel electrode. The present invention relates to a fringe field drive liquid crystal display device.

In general, liquid crystal displays have characteristics such as light weight, thinness, and low power consumption, and thus are used in terminals or video devices of various information devices in place of cathode ray tubes. In particular, a thin film transistor liquid crystal display (TFT-LCD) equipped with a thin film transistor (TFT-LCD) has excellent response characteristics and is suitable for high pixel numbers, thereby realizing high quality and large display devices.

In particular, the fringe field driving liquid crystal display device has an insulating film between the common electrode and a parabolic fringe field formed between the pixel electrodes so that all liquid crystal molecules interposed between the upper and lower substrates are operated to pass through the polarizing plate. It is a structure made to realize high brightness and wide viewing angle by letting the whole light proceed.

FIG. 1 is a plan view schematically illustrating a lower array substrate of a fringe field driving liquid crystal display device as a first embodiment, and a first embodiment will be described with reference to FIG. 1.

In the thin film transistor array substrate 10, as illustrated in FIG. 1, the gate bus line 11 and the data bus line 13 are cross-aligned to define unit pixels, and the intersection portion includes a TFT (a switching element). 15) is arranged. The common electrode 17 made of a transparent conductor is disposed in the unit pixel, and the pixel electrode 19 is disposed in the unit pixel so as to overlap the common electrode 17. The pixel electrode 19 is also made of a transparent conductor and is electrically insulated by the common electrode 17 and an insulating layer (not shown). The pixel electrode 19 has a slit structure having a plurality of slits which are inclined to extend along the gate bus line 13 direction and are spaced apart at predetermined intervals, one end of which is the source electrode of the TFT 15 (symbol display). No). Reference numeral 21 denotes a common bus line.

FIG. 2 is a plan view schematically illustrating a lower array substrate of a fringe field driving liquid crystal display device according to a second exemplary embodiment.

The conventional second embodiment is the same as the first embodiment, but differs in terms of the shape of the pixel electrode. The pixel electrode 19a according to the second exemplary embodiment is formed in a slit structure having a plurality of slits spaced apart at predetermined intervals while being inclined along the gate bus line 11. 21 has a shape inclined symmetrically with respect to each other.

The above-described prior arts have no difficulty in realizing excellent transmittance characteristics and wide viewing angle characteristics in comparison with the IPS mode. However, when such a structure is applied, it is possible to remove from unwanted field components such as data bus lines at both edges of the pixel electrode. Due to the influence of the liquid crystal drive, there was a limit in raising the level of the FFS-LCD, such as gray-to-grey response speed characteristics, after-image and electro-optical characteristics of the FFS mode.

Accordingly, in order to solve the above problem, an object of the present invention is to prevent the liquid crystal driving from undesired field components such as data bus lines at both edge portions of the pixel electrode so that the gray-to-grey response speed characteristics, afterimage and FFS modes To provide a fringe field drive liquid crystal display device that can improve the electro-optical properties.

In order to achieve the above object, the present invention, the gate bus line and the data bus line is cross-arranged unit pixels are limited, the unit pixel is a common electrode of the transparent electrode type using a transparent conductor and a slit type using a transparent conductor In a fringe field driving liquid crystal display device in which a lower thin film transistor substrate having pixel electrodes overlapping each other with an insulating layer interposed therebetween is bonded to a color filter substrate through liquid crystal, the slit of the pixel electrode is oriented in a gate bus line direction. Extend inclined along the gate busline, and the slit portions disposed at both edges of the divided slit portions have a larger slit angle with respect to the gate busline than the slit portion disposed in the middle. A fringe field drive liquid crystal display device is provided.

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The slit in the middle portion preferably maintains an angle of 5 to 20 degrees with respect to the gate bus line.

Preferably, the slits at both edge portions are made larger by 4 to 20 degrees than the slits at the center portions.

The first polarizing plate disposed on the lower thin film transistor substrate and the second polarizing plate disposed on the color filter substrate may be further added.

It is preferable that the transmission axis of the first polarizing plate and the transmission axis of the second polarizing plate are arranged perpendicular to each other, and any one of the transmission axis of the first polarizing plate and the transmission axis of the second polarizing plate coincides with the rubbing direction of the substrate. .

When the dielectric anisotropy is positive, the liquid crystal is preferably rubbed in a direction parallel to the gate bus line.

In the case where the dielectric anisotropy is negative, the liquid crystal is preferably rubbed so as to be arranged in a direction parallel to the data bus line.

Preferably, the slit angles of both edge portions are the same.

In addition, in order to achieve the above object, the present invention, the gate bus line and the data bus line is cross-arranged, the unit pixel is limited, in the unit pixel, a common electrode in the form of a transparent electrode using a transparent conductor and a slit using a transparent conductor A fringe field drive in which a pixel electrode of a type is overlapped with an insulating layer interposed therebetween, and a lower thin film transistor substrate having a common bus line arranged to pass through the center of the unit pixel is bonded to a color filter substrate through a liquid crystal. In the liquid crystal display device, the slit of the pixel electrode extends along the gate bus line direction, is divided into two with respect to the common bus line, and has a shape inclined symmetrically to each other, and is divided into three along the gate bus line direction. , The slit parts placed at both edges of the divided slit parts Minute to provide a fringe field driven liquid crystal display device, characterized in that the slit has a large angle relative to the gate bus line more.

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(Example)

Hereinafter, a fringe field driving liquid crystal display device according to the present invention will be described with reference to the accompanying drawings.

FIG. 3 is a plan view schematically illustrating a lower array substrate of a fringe field driving liquid crystal display device as a first embodiment of the present invention. Referring to FIG. 3, the first embodiment of the present invention will be described below.

In the lower thin film transistor substrate 40, the gate bus line 41 and the data bus line 43 are cross-arranged to limit unit pixels, and in the unit pixel, a common electrode 47 having a through electrode type using a transparent conductor. And the pixel electrode 49 of the slit structure using the transparent conductor are overlapped with an insulating layer (not shown) interposed therebetween. Reference numeral 51 denotes a common busline.

At this time, the slit of the pixel electrode 49 in each unit pixel is inclined in the direction of the gate bus line 41 and extends, in particular, in the areas A, B, and C along the direction of the gate bus line 41. The slit angles of the slit portions (corresponding to the region A and C) disposed at both edges of the gate bus line 41 are further divided than the slit angles of the slit portion (corresponding to the region B) disposed at the center. It is largely designed. Preferably, the center slit (region B) maintains an angle of 5 to 20 degrees with respect to the gate bus line 41, and the slit (corresponding to region A and region C) of both edge portions of the center portion Make it larger by 4-20 degrees than the slit (B area). Here, the slits (corresponding to the region A and the region C) of both edge portions have the same slit angle with respect to the gate bus line 41.

Although not shown in the drawing, the lower thin film transistor substrate 40 having the above configuration has a structure bonded to the color filter substrate through the liquid crystal.

Here, a first polarizing plate (not shown) is disposed on the rear surface of the lower thin film transistor substrate 40 having the above configuration, and a second polarizing plate (not shown) is disposed on the rear surface of the color filter substrate. In addition, the transmission axis of the first polarizing plate and the transmission axis of the second polarizing plate are arranged to be perpendicular to each other, so that any one of the transmission axis of the first polarizing plate and the transmission axis of the second polarizing plate coincides with the rubbing direction of the substrate. Is produced.

On the other hand, the liquid crystal is rubbed in a direction parallel to the gate bus line 41 when the dielectric anisotropy is positive, and rubbed so as to be arranged in a direction parallel to the data bus line 43 when the dielectric anisotropy is negative. .

Therefore, in the first embodiment of the present invention, the pixel electrodes of the slit structure are divided into three, and the slits on both edge portions are arranged to be larger than the slit angle of the center portion on the basis of the gate bus line. Undesired field components, such as data buslines, are not affected by liquid crystal drive. In other words, even if the portion of the unit pixel near the data bus line, that is, the disclination line from the edge of the unit pixel increases gray, the unit pixel can be prevented from extending into the center region of the unit pixel. As a result, it is possible to improve gray-to-grey response speed characteristics, afterimage problems, and electro-optical characteristics of the FFS mode.

FIG. 4 is a plan view schematically illustrating a lower array substrate of a fringe field drive liquid crystal display device according to a second embodiment of the present invention, and is located in a unit pixel of the fringe field drive liquid crystal display device in a dual domain. The slit of the pixel electrode is divided into three. Hereinafter, a second embodiment of the present invention will be described with reference to FIG. 4.

As shown in FIG. 4, in the lower thin film transistor substrate 60, the gate bus line 61 and the data bus line 63 are cross-arranged to limit unit pixels, and a unit electrode using a transparent conductor in the unit pixel. The common electrode 67 of the shape and the pixel electrode 69 having a comb-shaped slit structure using a transparent conductor are disposed to overlap each other with an insulating layer (not shown) interposed therebetween, and to pass through the center of the unit pixel. 71) is arranged.

The pixel electrode 69 in each unit pixel has a plurality of slits that extend inclined along the gate bus line 41, wherein the slits are divided into two with respect to the common bus line 71 and symmetrically arranged to each other. It has a photographic shape, in particular, divided into three along the direction of the gate bus line 61, the slits (A1 region and C1 region) of both edge portions with respect to the gate bus line 61 is the slit (B1 region) of the center portion It is designed to have a larger slit angle.

Preferably, the center slit (B1 region) maintains an angle of 5 to 20 degrees with respect to the gate bus line 61, and the slit (A1 region and C1 region) of both edge portions is a slit (B1) in the center portion. Larger than the region) by 4 to 20 degrees.

The lower thin film transistor substrate 60 having the above-described configuration is bonded to the color filter substrate (not shown) through a liquid crystal (not shown).

Here, a first polarizing plate (not shown) is disposed on the rear surface of the lower thin film transistor substrate 60 having the above configuration, and a second polarizing plate (not shown) is disposed on the rear surface of the color filter substrate. In addition, the transmission axis of the first polarizing plate and the transmission axis of the second polarizing plate are arranged to be perpendicular to each other, and any one of the transmission axis of the first polarizing plate and the transmission axis of the second polarizing plate is made to match the rubbing direction of the substrate. .

On the other hand, the liquid crystal is rubbed in a direction parallel to the gate bus line 61 when the dielectric anisotropy is positive, and rubbed so as to be arranged in a direction parallel to the data bus line 63 when the dielectric anisotropy is negative. .

FIG. 5 is a graph showing voltage versus absolute transmittance according to the slit angle change of the pixel electrode, and shows absolute transmittance according to voltage when the slit angle is 7 °, 11 °, 15 °, 19 °, and 23 °, respectively. .

According to the present invention, as shown in FIG. 5, the transmittance curve according to the overall voltage becomes wider as the curve becomes smoother and the overall driving voltage also increases. At this time, the angles of the slits (areas A and C) of both edge portions are 4 to 20 degrees greater than the slits (areas B) of the center portion, and the angle of the slits (areas B) of the center portion is most appropriately maintained at 5 to 20 degrees. It can be seen. Therefore, in the slits (regions A and C) of both edge portions having a large slit angle, the liquid crystal driving is less affected by unwanted field components such as external data bus lines.

Accordingly, in the second embodiment of the present invention, the pixel electrodes having the slit structure are divided into two with respect to the common bus line to be symmetrical with each other, and divided into three in the data bus line direction, and both edge portions are referred to with respect to the gate bus line. The angles of the slits (areas A1 and C1) are arranged to be larger than the slits (B1) in the center portion, so that the edges of the pixel electrodes are not affected by liquid crystal driving from unwanted field components such as data bus lines. do. As a result, it is possible to improve gray-to-grey response speed characteristics, afterimage problems, and electro-optical characteristics of the FFS mode.

As described above, the present invention divides the pixel electrode of the sullet structure by three, and the slit at both edges with respect to the gate bus line has a slit angle larger than the slit in the center, thereby providing data at both edges of the pixel electrode. It is possible to improve the gray-to-grey response speed characteristics, after-image problems, and electro-optical characteristics of the FFS mode by being unaffected by liquid crystal driving from unwanted field components such as buslines.

On the other hand, in the present invention, the pixel electrode of the slit structure is divided into two with respect to the common bus line to have a symmetrical shape, and divided into three in the direction of the gate bus line, and the slit angles of both edge portions based on the gate bus line are adjusted. By making it larger than the center slit angle, the gray-to-gray response speed characteristics, after-image problems, and the electric field of the FFS mode are prevented from being affected by liquid crystal driving from unwanted field components such as data bus lines at both edge portions of the pixel electrode. Optical properties can be improved.

Claims (11)

The gate bus line and the data bus line are cross-arranged to limit unit pixels, and within the unit pixel, a common electrode in the form of a transparent electrode and a slit pixel electrode in the form of a transparent conductor overlap each other with an insulating layer interposed therebetween. In the fringe field driving liquid crystal display device wherein the lower thin film transistor substrate is arranged to be bonded to the color filter substrate via the liquid crystal. The slit of the pixel electrode is inclined to extend along the gate busline direction, and is divided into three along the gate busline direction, and the slit portions disposed at both edges of the three divided slit portions are disposed more than the slit portion disposed in the middle. A fringe field drive liquid crystal display device having a large slit angle with respect to a bus line. The fringe field drive liquid crystal display device according to claim 1, wherein the center slit maintains an angle of 5 to 20 degrees with respect to the gate bus line. The fringe field driving liquid crystal display device according to claim 1, wherein the slits at both edge portions are made larger by 4 to 20 degrees than the slits at the center portions. The fringe field driving liquid crystal display of claim 1, further comprising a first polarizing plate disposed on the lower thin film transistor substrate and a second polarizing plate disposed on the color filter substrate. 5. The rubbing direction of claim 4, wherein the transmission axis of the first polarizing plate and the transmission axis of the second polarizing plate are perpendicular to each other, and any one of the transmission axis of the first polarizing plate and the transmission axis of the second polarizing plate is in a rubbing direction of the substrate. A fringe field drive liquid crystal display device, characterized in that: The fringe field drive liquid crystal display device according to claim 1, wherein the liquid crystal is subjected to rubbing in a direction parallel to the gate bus line when the dielectric anisotropy is positive. The fringe field drive liquid crystal display device according to claim 1, wherein the liquid crystal is subjected to a rubbing process so as to be arranged in a direction parallel to the data bus line when the dielectric anisotropy is negative. The fringe field drive liquid crystal display device according to claim 1, wherein the slit angles of both edge portions are the same. The gate bus line and the data bus line are cross-arranged to limit unit pixels, and within the unit pixel, a common electrode in the form of a transparent electrode and a slit pixel electrode in the form of a transparent conductor overlap each other with an insulating layer interposed therebetween. In the fringe field driving liquid crystal display device, the lower thin film transistor substrate having a common bus line arranged so as to pass through the center of the unit pixel is bonded to a color filter substrate via a liquid crystal. The slit of the pixel electrode extends along the gate bus line direction and is divided into two with respect to the common bus line, and has a shape inclined to be symmetrical to each other, and is divided into three along the gate bus line direction. Fringe field driving liquid crystal display device, characterized in that the slit portions disposed at both edges have a larger slit angle with respect to the gate busline than the slit portions disposed in the center. 10. The fringe field driving liquid crystal display device according to claim 9, wherein the center slit maintains an angle of 5 to 20 degrees with respect to the gate bus line. 10. The fringe field driving liquid crystal display device according to claim 9, wherein the slits at both edge portions are made larger by 4 to 20 degrees than the slits at the center portions.

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