KR100756835B1 - Fringe field switching mode lcd device - Google Patents

Abstract

Field of the Invention [0002] The present invention relates to a fringe field driving mode liquid crystal display, and more particularly, to a liquid crystal display capable of suppressing a residual image effect.

The present invention discloses a fringe field driving mode liquid crystal display device having counter electrodes and pixel electrodes each having a slit shape with at least one insulating film interposed therebetween and having double domains in the upper and lower sides, An upper domain including a counter electrode, and a lower domain formed symmetrically with the upper domain, according to an embodiment of the present invention. Thereby, the afterimage effect can be suppressed.

Description

FIELD FIELD SWITCHING MODE LCD DEVICE [0001]

1 is a plan view illustrating a conventional fringe field driving mode liquid crystal display device.

2 is a plan view illustrating a fringe field driving mode liquid crystal display device according to the present invention.

3 is a cross-sectional view illustrating charge distribution according to an embodiment of the present invention;

Description of the Related Art [0002]

100: lower substrate 102: counter electrode

103: gate bus line 107: data bus line

109: pixel electrode 200a: upper domain

200b: sub domain 300: common signal line

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fringe field switching mode LCD device, and more particularly, to a fringe field driving mode liquid crystal display device capable of reducing a sticking image.

In general, a high aperture ratio and a high transmittance liquid crystal display (Fringe Field switching mode LCD) have been proposed in order to improve the low aperture ratio and transmittance of a general IPS mode liquid crystal display device, and filed in Korean Patent Application No. 98-9243.

Such a high aperture ratio and high transmittance liquid crystal display device has a structure in which a counter electrode and a pixel electrode are formed of a transparent conductor and an interval between the counter electrode and the pixel electrode is narrower than an interval between the upper and lower substrates, thereby forming a fringe filed.

Such a high aperture ratio and high transmittance liquid crystal display device is shown in Fig.

The gate bus line 3 and the data bus line 7 are arranged on the lower substrate 1 so as to define unit pixels and the intersection point of the gate bus line 3 and the data bus line 7 A thin film transistor (TFT) is disposed.

The counter electrode 2 is formed as a transparent conductor for each unit pixel, and has a rectangular plate shape. The counter electrode 2 is contacted with the common signal line 30, and receives a common signal continuously. The common signal line 30 has a first portion 30a parallel to the gate bus line 3 and in contact with a predetermined portion of the counter electrode 2 and a second portion 30b parallel to the data bus line 7 from the first portion 30a. And a second portion 30b, which is disposed between the counter electrode 2 and the data bus line 7, respectively. At this time, the second portion 30b is insulated from the data bus line 7.                         

The pixel electrode 9 is formed in each unit pixel space so as to overlap with the counter electrode 2. The pixel electrode 9 includes a comb tooth portion 9a formed parallel to the data bus line 7 and formed at equal intervals and a bar 9b connected to a predetermined portion of the TFT while connecting one end of the comb tooth portion 9a And a bar 9c connecting the other end of the comb 9a. Here, the counter electrode 2 and the pixel electrode 9 are insulated with an insulating film (not shown) interposed therebetween.

Although not shown in the drawing, the upper substrate facing the lower substrate 1 is opposed and oppositely arranged with a width larger than the distance between the pixel electrode 9 and the counter electrode 2.

However, in the conventional FFS structure, since the counter electrode 5 is deposited on the entire surface of the pixel, the interval between the pixel electrode 9 and the overlapped portion is large. Thus, a strong electric field is formed between the pixel electrode 9 and the counter electrode 2 to drive the liquid crystal.

At this time, since an insulating film having a large dielectric constant exists between the pixel electrode 9 and the counter electrode 2, the capacitance value is large and ion adsorption and interface polarization occur at the insulating film interface, so that the residual DC component existing in the drain signal . These residual DC components cause liquid crystals to be influenced, resulting in a residual image in which a specific pattern continues to exist.

Accordingly, it is an object of the present invention to provide a fringe field driving mode liquid crystal display device capable of effectively reducing a residual image effect by suppressing a residual DC component due to a strong electric field.

According to an aspect of the present invention, there is provided a fringe field drive mode liquid crystal display device including a counter electrode and a pixel electrode having a slit shape with at least one insulating film interposed therebetween, The apparatus comprising: an upper domain including at least two counter electrodes between the pixel electrodes; and a lower domain formed symmetrically with the upper domain.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a plan view illustrating a fringe field driving liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 3 is a cross-sectional view illustrating an electric field distribution of a fringe field driving liquid crystal display of the present invention.

As shown in the figure, gate bus lines 103 and data bus lines 107 are arranged on the lower substrate 100 to define unit pixels in the form of a matrix, and gate bus lines 103 and data buses A thin film transistor (TFT) is disposed in the vicinity of the intersection of the line 107.

A counter electrode 102 in a unit pixel is formed as a transparent conductor for each unit pixel, and a plurality of comb teeth 102a and a slit are formed. At this time, the unit pixel is composed of the upper domain 200a and the lower domain 200b so as to have a dual-domain structure, thereby forming the comb portion 102a and the counter electrode 102 of the slit structure having different shapes.

The counter electrode 102 is contacted with the common signal line 300 and receives a common signal continuously. The common signal line 300 includes a first portion 300a parallel to the gate bus line 103 and in contact with a predetermined portion of the counter electrode 200 and a second portion 300a parallel to the data bus line 107 from the first portion 300a. And a second portion 300b, which is disposed between the counter electrode 102 and the data bus line 107, respectively. At this time, the second portion 300b is insulated from the data bus line 107.

The pixel electrode 109 is formed in each unit pixel space in a shape having a plurality of comb teeth portions 109a and slits under an insulating film (not shown) above the counter electrode 102. [ At this time, the pixel electrode 109 is formed in a shape of a comb 109a and a slit of different shapes in the upper and lower domains 200a and 200b, like the counter electrode 102.

The pixel electrode 109 is connected to a predetermined portion of the thin film transistor TFT while connecting one end of the comb tooth portion 109a and the comb tooth portion 109a which are parallel to the data bus line 107 and are spaced apart from each other, (109b) and a bar (109c) connecting the other end. Here, the counter electrode 102 and the pixel electrode 109 are insulated with an insulating film (not shown) interposed therebetween.

The counter electrode 102 and the pixel electrode 109, which are differently formed as described above, are specifically formed as follows.

A counter electrode 102 having comb teeth 102a formed at densely spaced intervals and a pixel electrode 109 having comb teeth 109a formed at a relatively wide interval are formed on the upper domain 200a. The upper domain 200a having at least two comb teeth 102a of at least two counter electrodes 102 is formed between the comb teeth 109a of the pixel electrode 109. [

The comb tooth portion 102a of the counter electrode 102 and the comb tooth portion 109a of the pixel electrode 109 formed in the lower domain 200b are formed symmetrically to those formed in the upper domain 200a. That is, the counter electrode 102 having the comb-like portions 102a formed at relatively wide intervals and the pixel electrode 109 having the comb-like portions 109a formed at the closely spaced intervals, for example, the comb- The lower domain 200b having at least two comb tooth portions 109a of at least two pixel electrodes 109 is formed.

3 is a cross-sectional view showing an electric field distribution formed between the counter and the pixel electrode having the above structure.

(a) shows the electric field distribution occurring between each electrode in the upper domain. Two comb teeth portions 102a of the counter electrode 102 are passed between the comb teeth 109a of the pixel electrode 109. As shown in Fig. A stacked structure of an insulating film 350, for example, a gate insulating film and a protective film deposited after forming a thin film transistor (not shown) is interposed between the pixel electrode 102 and the counter electrode 102. At this time, the residual electric charge existing in the insulating film 350 or the interface appears as an unbalanced distribution between the insulating films 350 due to the strong electric field generated between the pixel electrode 109 and the adjacent counter electrode 102.

Further, the residual charge is polarized by the electric field, and the internal DC is formed. However, since a weak electric field is formed between the electrodes which are farther than the conventional pixel electrode, an uneven distribution of the residual electric charges is generated, so that the influence due to the afterimage can be reduced.

On the other hand, (b) shows the electric field distribution occurring between the electrodes in the lower domain 200b. The comb tooth portion 102a of the counter electrode 102 and the comb tooth portion 109a of the pixel electrode 109 are formed symmetrically with the electrode structure of the upper domain 200a to form the comb tooth portion 109a of the counter electrode 102 and the comb tooth portion 109a of the pixel electrode 109, Make the electric field distribution different. This imbalance of the charge distribution existing in the insulating film facilitates the movement of the charge.

Although the liquid crystal is mainly driven by a strong electric field, the liquid crystal in a portion where a weak electric field is applied between the counter electrodes 102 can be moved simultaneously under the influence of the adjacent liquid crystal change.

2, an intermediate bar 109d connecting the comb tooth portions 109a of the pixel electrode 109 on the upper and lower domains 200a and 200b is formed at the middle portion of the pixel electrode 109, . This can reduce the resistance of the pixel electrode 109 and make it possible to move the charged or remaining charge well.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. Will be clear to those who have knowledge of.

According to the fringe field driving mode liquid crystal display of the present invention, the unit pixel is divided into an upper domain and a lower domain, and an electrode structure having symmetry is formed to vary the electric field distribution existing in the insulating layer. This makes it possible to easily remove the accumulated charge by facilitating the movement of charges by providing an imbalance of the charge distribution existing in the insulating film. Therefore, the capacitance value due to the afterimage can be reduced, and the driving voltage can be reduced.                     

Further, an intermediate bar is formed in the middle of the pixel electrode to reduce the pixel electrode resistance. This makes it possible to easily move the charge for driving the liquid crystal and to reduce the pixel vertical voltage difference due to the resistance difference.

Therefore, the residual DC component due to the strong electric field can be suppressed, and the afterimage effect can be effectively reduced.

Claims (2)

A fringe field driving mode liquid crystal display device having a double domain of upper and lower sides, each having counter electrodes and pixel electrodes each having at least two comb portions under at least one insulating film, An upper domain including at least two comb electrodes of the counter electrodes between the comb electrodes of the pixel electrodes, And a lower domain formed symmetrically with the upper domain. The method according to claim 1, Wherein the pixel electrode forms an intermediate bar at an intermediate portion of the electrode to connect the comb teeth portions.

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