KR20030058546A - Lcd device driving in spacer field switching mode - Google Patents

Abstract

PURPOSE: A liquid crystal display driven in a spacer field switching mode is provided to form a vertical electric field between a pixel electrode and a relative electrode, or form a horizontal electric field between spacers and the pixel electrode or the relative electrode, thereby realizing vertical and horizontal on/off driving and improving a view angle. CONSTITUTION: An array substrate(30) has a thin film transistor and a pixel electrode(24) formed of an ITO(Indium Tin Oxide) material. A color filter substrate(40) faces the array substrate and has color filters and a relative electrode(32) of the ITO material. A liquid crystal layer is interposed between the array substrate and the color filter substrate, and includes a plurality of liquid crystal molecules. A plurality of spacers(42) are dispersed between the array substrate and the color filter substrate to maintain a cell gap, and electrically connected with the pixel electrode or the relative electrode.

Description

LCD DEVICE DRIVING IN SPACER FIELD SWITCHING MODE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display for driving in a spacer field switching mode in which a wide viewing angle is realized using a conductive spacer connected to an ITO electrode.

As is well known, liquid crystal displays have been developed in place of the CRT (Cathod-ray tube). In particular, the thin film transistor liquid crystal display device has been in the spotlight in the information display of a portable terminal device, the screen display of a notebook PC, the monitor of a laptop computer, etc., and thus, the utilization of the thin film transistor as a display device that can replace the CRT has been very high. .

Such a thin film transistor liquid crystal display device has typically adopted TN (Twist Nematic) mode as a driving mode, but the TN mode has a disadvantage in that its viewing angle is narrow, and thus its use is limited. Accordingly, in-plane switching (IPS) mode has been proposed as a driving mode that can improve the viewing angle. Although the IPS mode liquid crystal display implements a wide viewing angle, it has limitations in terms of aperture ratio and transmittance. Indicated.

Accordingly, a fringe field switching mode liquid crystal display (hereinafter referred to as FFS-LCD) capable of improving the aperture ratio and transmittance while maintaining the characteristics of the wide viewing angle of the IPS mode liquid crystal display has been proposed by the present applicant. And Korean Patent Application No. 98-9243.

The FFS-LCD has a structure in which a counter electrode and a pixel electrode are formed of a transparent metal such as ITO so that a gap between the electrodes is smaller than a cell gap, and a fringe field is generated between the electrodes. As a result, all of the liquid crystal molecules present on the electrodes are operated to realize high opening ratio and high transmittance, as well as high brightness and wide viewing angle.

FIG. 1 is a plan view showing an array substrate of a conventional FFS-LCD. As shown in FIG. 1, a gate bus line 2 and a data bus line 6 are alternately arranged so that a unit pixel is defined. Near the intersection between 2 and 6, a thin film transistor (TFT) is arranged as a switching element.

A counter electrode 4 having a plate shape and made of a transparent conductive film such as ITO is disposed in the unit pixel, and the common bus line 3 is located at a position in the unit pixel spaced apart from the gate bus line 2 as far as possible. It is arranged in parallel with the gate bus line (2). The common bus line 3 is formed to continuously supply a common signal to the counter electrode 4, and is formed at the same time as the gate bus line 2 and extends in parallel with the data bus line 6. And light blocking means disposed at both edges of the counter electrode 4.

A pixel electrode 8 having a slit shape and made of a transparent conductive film such as ITO is arranged to overlap the counter electrode 4 in the unit pixel with an insulating film (not shown) interposed therebetween, and a part of the thin film transistor It is in contact with (TFT).

Although not shown, the array substrate having the above-described structure is bonded to the color filter substrate having the black matrix and the color filter and interposed between the liquid crystal layer composed of negative liquid crystal molecules. In this case, the array substrate and the color filter substrate are bonded to have a larger gap than the gap between the counter electrode and the pixel electrode provided in the array substrate.

In the FFS-LCD, negative liquid crystal molecules are rotated by causing the pixel electrode 8 to cause a potential difference between the liquid crystal molecules on the counter electrode 4 that serves as storage and the common electrode Vcom. As a result, the light that has advanced through the polarizing plate proceeds toward the color filter substrate to display a predetermined image.

However, the FFS-LCD has a superior viewing angle compared to the IPS and TN mode liquid crystal display devices, but due to unwanted parasitic capacitance due to overlapping of the counter electrode and the pixel electrode, the residual image is long when the same image is implemented for a long time. Problems in terms of the screen quality, such as the) remains badly. In particular, in order to improve such a problem, it is necessary to supplement the system, but above all, the structural improvement of the panel is necessary.

Accordingly, an object of the present invention is to provide a liquid crystal display device of a novel driving method that is driven in a spacer field switching mode capable of realizing a wide viewing angle while solving the afterimage problem.

1 is a plan view showing a conventional fringe field switching mode liquid crystal display device.

2 is a cross-sectional view showing a spacer field switching mode liquid crystal display according to an embodiment of the present invention.

3 is a view for explaining the operation principle of the spacer field switching mode liquid crystal display according to an embodiment of the present invention.

4 is a cross-sectional view illustrating a spacer field switching mode liquid crystal display according to another exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

22: protective film 24: pixel electrode

30: array substrate 32: counter electrode

34: overcoat layer 40: color filter substrate

42: spacer TFT: thin film transistor

According to an aspect of the present invention, there is provided a liquid crystal display device including: an array substrate including a thin film transistor and a pixel electrode made of ITO; A color filter substrate disposed to face the array substrate and having a color filter and a counter electrode made of ITO; A liquid crystal layer interposed in the space between the array substrate and the color filter substrate and including several liquid crystal molecules; And a spacer dispersed between the array substrate and the color filter substrate to maintain a cell gap, the spacer being electrically connected to any one of the pixel electrode and the counter electrode while being made of a conductive material having the same size as the cell gap. Characterized in that.

Herein, the spacer further includes a non-conductive spacer having a smaller size than the cell gap, and a neutral, alkaline, or weakly acidic organic material of silane and tetramethyldisilazane (TMDS) is coated on the surface thereof.

In addition, any one of the pixel electrode and the counter electrode to which the conductive spacer is connected may be provided in a stripe type in addition to the plate type.

According to the present invention, since the liquid crystal is driven by the vertical transverse electric field using the conductive spacer, it is possible to implement a wide viewing angle, and also to solve the afterimage problem in the FFS-LCD.

(Example)

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

2 is a cross-sectional view illustrating a spacer field switching mode liquid crystal display device according to an exemplary embodiment of the present invention, wherein reference numeral 22 denotes a protective film, 24 a pixel electrode, 30 an array substrate, 32 a counter electrode, and 34 an overcoat layer. 40 denotes a color filter substrate, 42 denotes a conductive spacer, and TFT denotes a thin film transistor.

As shown, the spacer field switching mode liquid crystal display device of the present invention, like the typical TN mode liquid crystal display device, the array substrate 30 is provided with a thin film transistor (TFT) and pixel electrode 24 of ITO material, The color filter substrate 40 including the color filter (not shown) and the counter electrode 32 made of ITO is bonded under the interposition of the liquid crystal layer (not shown) including several liquid crystal molecules, and the substrates 30 , 40 is interposed between the spaces, that is, the structure in which the space 42 is interposed to maintain the cell gap (Cell gap).

In the spacer field switching mode liquid crystal display device as described above, the spacer 42 is made of a conductive material unlike the conventional art. The conductive spacer 42 is the pixel electrode 24 disposed on the top of the array substrate 30. Is electrically connected to the In addition, as will be described later, the spacer 42 may be electrically connected to the counter electrode 32 of the color filter substrate 40 by changing the structure of the array substrate 30 and the color filter substrate 40. .

In addition, a neutral, alkaline, or slightly acidic organic material (not shown) of silane and TMDS (Tetramethyldisilazane) is coated on the surface of the spacer 42 to prevent impurities from adsorbing when the liquid crystal display is driven. For example, such an organic substance is applied after the conductive spacers are scattered on the array substrate 30, or after the conductive spacers are scattered on the color filter substrate 40.

In addition, the spacer 42 may be made of a conductive material having the same size as the cell gap, and may also include a non-conductive spacer made of a non-conductive material having a smaller size than the cell gap.

In addition, the present invention includes any one of the pixel electrode 24 and the counter electrode 32, for example, an electrode that is not electrically connected to the spacer 42 in a stripe type other than a plate type. In this case, the viewing angle is further improved.

In the liquid crystal display of the present invention, a conductive spacer is interposed, and a vertical transverse electric field is generated between the pixel electrode and the counter electrode by electrically connecting the conductive spacer to the pixel electrode or the counter electrode. / Off) operation is performed.

In detail, FIG. 3 is a view for explaining a principle of operation of a spacer field switching mode liquid crystal display according to an exemplary embodiment of the present invention. As shown in FIG. 3, a spacer 42 made of a conductive material is used to form substrates 30 and 40. In the case where a voltage of "+" is applied to the pixel electrode 24 and a voltage of "-" is applied to the counter electrode 32 as it is electrically connected to the pixel electrode 24 while being interposed therebetween, The spacer 42 has a potential of "+", whereby a vertical electric field is formed between the pixel electrode 24 and the counter electrode 32, and between the conductive spacer 42 and the counter electrode 32. The transverse electric field is formed.

Therefore, in the spacer field switching mode liquid crystal display of the present invention, the viewing angle can be further improved by generating both vertical and horizontal electric fields, and the liquid crystal molecules between the spacers move vertically, and the liquid crystal near the spacer is moved. Since the molecules rotate horizontally, they perform vertical on / off and rotational on / off driving simultaneously, so that afterimages in the FFS-LCD only perform horizontal on / off driving. The problem can be solved.

4 is a cross-sectional view schematically showing a spacer field switching mode liquid crystal display device according to another embodiment of the present invention. As shown, the liquid crystal display device in this embodiment has a conductive spacer 42 having a color filter substrate. It has a structure electrically connected to the counter electrode 32 of the (40).

To this end, the array substrate 30 is manufactured in a structure in which the pixel electrode 24 is covered with the protective film 22, and the color filter substrate 40 has the counter electrode 32 disposed on the overcoat layer 34. It is manufactured by the structure.

The other remaining components have the same structure as those in the above-described embodiment.

Similar to that of the previous embodiment, the liquid crystal display in this embodiment also generates vertical and horizontal electric fields at the same time by interposing conductive spacers, thereby improving the viewing angle and solving the afterimage problem.

On the other hand, in the above embodiments, by adjusting the size and design of the spacer made of a conductive material, it is possible to improve the transmittance of the liquid crystal display device, and also to significantly reduce the light leakage caused by the spacer.

As described above, the present invention forms a vertical electric field between the pixel electrode and the counter electrode by electrically connecting the spacer for maintaining the cell gap with the counter electrode of the pixel electrode or the color filter substrate of the array substrate while forming a conductive material. Of course, a horizontal electric field may be formed between the spacer and the pixel electrode or the counter electrode.

Therefore, with regard to both vertical and horizontal on / off driving, the viewing angle can be improved, and the afterimage can be prevented.

In addition, this invention can be implemented in various changes in the range which does not deviate from the summary.

Claims (6)

An array substrate including a thin film transistor and a pixel electrode made of ITO; A color filter substrate disposed to face the array substrate and having a color filter and a counter electrode made of ITO; A liquid crystal layer interposed in the space between the array substrate and the color filter substrate and including several liquid crystal molecules; And Scattered to maintain a gap between the array substrate and the color filter substrate, the spacer includes a spacer formed of a conductive material having the same size as the cell gap and electrically connected to any one of the pixel electrode and the counter electrode. Liquid crystal display device characterized in that. The liquid crystal display of claim 1, wherein the spacer further comprises a non-conductive spacer having a size smaller than a cell gap. According to claim 1, wherein the surface of the spacer A liquid crystal display device characterized in that a neutral, alkaline, or slightly acidic organic material of silane and TMDS (Tetramethyldisilazane) is coated. The liquid crystal display of claim 1, wherein the pixel electrode is disposed on an uppermost portion of the array substrate, and the spacer is electrically connected to the pixel electrode of the array substrate. The liquid crystal display of claim 1, wherein the counter electrode is disposed on an uppermost portion of the color filter substrate, and the spacer is electrically connected to the counter electrode of the color filter substrate. The liquid crystal display of claim 1, wherein any one of the pixel electrode and the counter electrode is provided in a stripe type.