KR20020078492A - Apparatus for Liquid Crystal Display - Google Patents

Abstract

PURPOSE: A liquid crystal display device is provided to prevent the generation of disclination lines for improving the transmissivity, luminance and the viewing angle for obtaining the high quality in-plane switching vertical align mode liquid crystal display. CONSTITUTION: A liquid crystal display device includes upper and lower substrates facing each other, a liquid crystal layer interposed between the upper and lower substrates, common electrodes(302a) and pixel electrodes(302b) disposed on an inner surface of the lower substrate for driving the liquid crystal molecules(307a), and a plurality of auxiliary electrodes(304) formed on an inner surface of the upper substrate with a certain width by a certain interval to react to the electrodes on the lower substrate.

Description

Liquid crystal display {Apparatus for Liquid Crystal Display}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to include a plurality of auxiliary electrodes on an upper substrate, thereby suppressing the occurrence of the declining line and improving the transmittance deterioration phenomenon. Relates to a device.

Generally, In Plane Switching-Vertically Alligned mode Liquid Crystal Display (hereinafter referred to as IPS-VA LCD) is referred to as In Plane Switching mode Liquid Crystal Display (hereinafter referred to as "In Plane Switching-Vertically Alligned mode Liquid Crystal Display"). , A liquid crystal proposed to improve the slow response speed, which is a characteristic of the IPS LCD, and to exclude a rubbing process for forming a domain of a Vertally Alligned Mode Liquid Crystal Display (VA LCD). It is a display device.

The IPS-VA LCD adopts the vertical alignment while controlling the liquid crystal molecules by parallel field, so that the liquid crystal molecules respond quickly and form a double domain by electric field without additional rubbing process. It is very excellent.

A schematic description of an IPS-VA LCD according to the prior art is as follows.

1A and 1B are cross-sectional views illustrating an IPS-VA LCD according to the prior art.

In the prior art IPS-VA LCD, as shown in FIG. 1A, the upper and lower substrates 101 and 105, the common electrode 102a and the pixel electrode disposed in parallel at a predetermined distance to form an electric field. 102b, first and second vertical alignment layers 103 and 106 for vertically arranging the liquid crystal molecules 107a constituting the liquid crystal layer 107, and polarizers 108 disposed on outer surfaces of the upper and lower substrates. And a decomposer 109 and a phase compensating plate 110 for compensating the refractive index anisotropy of the liquid crystal molecules.

The conventional IPS-VA LCD having the above configuration operates as follows.

In the conventional IPS-VA LCD, when an electric field is formed between the common electrode 102a and the pixel electrode 102b, the liquid crystal molecules 107a that are vertically arranged are arranged in parallel with the electric field. Then, the light passing through the polarizer 108 arranged such that the polarization axis is at an angle of about 45 degrees with the electric field is passed through the liquid crystal layer 107 and the decomposer 110.

Figure 1c is a view showing the results of the simulation of the conventional IPS-VA LCD.

In the conventional IPS-VA LCD, as shown in FIG. 1C, the liquid crystal molecules 107a are symmetrically centered on the center of the common electrode 102a and the pixel electrode 102b according to the ellipse and the horizontal electric field shape. Are arranged. Therefore, it can be seen that the left and right viewing angle characteristics are improved and the transmittance is also improved.

2 is a view showing a simulation result of a conventional IPS-VA LCD having a configuration different from the above.

As shown in FIG. 3, there is no difference from the structure shown in FIG. 1A except that the auxiliary electrode 200 is further disposed on the upper substrate.

On the other hand, IPS-VA LCD according to the prior art has the following problems.

In the conventional IPS-VA LCD, as shown in FIG. 1B, the liquid crystal molecules present at the center of the common electrode and the pixel electrode and the liquid crystal molecules present at the top of each electrode are the same from the liquid crystal molecules at both sides thereof. It maintains its initial vertical arrangement because it is simultaneously forced in opposite directions. Therefore, light does not leak in this portion, and a disclination line is generated on the screen.

In addition, in another IPS-VA LCD according to the related art, since the auxiliary electrode 300 is disposed on the upper substrate, the above-described disclination line does not occur, but the transmittance is relatively lowered. There is a problem.

Accordingly, the present invention has been made to solve the problems of the prior art, an object of the present invention is to provide a plurality of auxiliary electrodes on the upper substrate in-plane switching that can suppress the occurrence of the declining line and improve the transmittance decrease phenomenon It is to provide a vertical alignment liquid crystal display device.

1A and 1B are cross-sectional views illustrating an in-plane switching vertically aligned mode liquid crystal display device according to the prior art.

FIG. 1C is a view showing a simulation result of an in-plane switching vertical alignment liquid crystal display device according to the related art. FIG.

2 is a view showing a simulation result of another in-plane switching vertical alignment liquid crystal display device according to the prior art.

3A and 3B are cross-sectional views illustrating an in-plane switching vertically aligned mode liquid crystal display device according to the present invention.

Figure 3c is a view showing the results of the simulation of the in-plane switching vertical alignment liquid crystal display device according to the present invention.

4 to 7 are views showing the results of a simulation of the in-plane switching vertical alignment liquid crystal display device according to various embodiments of the present invention.

<Description of the symbols for the main parts of the drawings>

301; Lower substrate 302a; Common electrode

302b; Pixel electrodes 303 and 306; Vertical alignment film

304; Auxiliary electrode 305; Upper board

307; Liquid crystal layer 307a; Liquid crystal molecules

308; Polarizer 309; Decomposer

310; Phase Compensation Plate

The liquid crystal display device according to the present invention for achieving the object of the present invention, the upper and lower substrates facing each other; A liquid crystal layer interposed between the upper and lower substrates; A liquid crystal display device disposed on an inner surface of the lower substrate and including a common electrode and a pixel electrode for driving a liquid crystal, wherein the upper substrate inner surface has an arbitrary width and an arbitrary distance, and an electrode formed on the inner surface of the lower substrate. It characterized in that a plurality of auxiliary electrodes for interacting to drive the liquid crystal is formed.

Hereinafter, a liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings.

3A and 3B are cross-sectional views illustrating a liquid crystal display device according to the present invention.

In the liquid crystal display according to the present invention, as shown in FIG. 3A, the lower substrate 301 and the upper substrate 305 are disposed to face each other with the liquid crystal layer 307 interposed therebetween. Here, the common electrode 302a and the pixel electrode 302b for driving the liquid crystal molecules 307a in the liquid crystal layer 307 to induce an electric field perpendicular to the substrate and an elliptical electric field on the lower substrate 301. It is arrange | positioned at arbitrary intervals. At this time, the common electrode 302a and the pixel electrode 302b are preferably arranged at equal intervals. In addition, the liquid crystal molecules 307a are preferably liquid crystals having a positive dielectric anisotropy.

On the other hand, a plurality of auxiliary electrodes 304 are also arranged in the upper substrate 305 in a slit structure, and the auxiliary electrodes 304 are preferably made of a transparent conductor, for example, ITO. In this case, the auxiliary electrode 304 on the upper substrate 305 is formed so that its length is not shorter than that of each of the common electrode 302a and the pixel electrode 302b on the lower substrate 301. It is disposed to overlap the common electrode 302a. Here, the common electrode 307a and the pixel electrode 307b on the lower substrate are composed of an opaque or transparent conductor. If the aperture ratio and the transmittance are considered, the transparent conductor is preferable, and the transparent conductor is preferably ITO.

Inner surfaces of the lower substrate 301 and the upper substrate 305 are provided with alignment layers 303 and 306 for arranging the liquid crystal molecules 307a in a predetermined direction, and the alignment layers 303 and 306 are liquid crystal displays. In the device, when the electric field is not applied, the long axis of the liquid crystal molecules 307a is arranged so as to be perpendicular to the surfaces of the lower substrate 301 and the upper substrate 305.

The outer surface of the lower substrate 301 and the upper substrate 305 is provided with a polarizing plate for deflecting incident light in one direction, that is, a polarizer 308 and a decomposer 309, the transmission axis (not shown) of the polarizer 308 C) and the transmission axis (not shown) of the decomposer 309 are attached to be orthogonal to each other.

At this time, the transmission axis (not shown) of the polarizer 308 is advantageously attached to have an angle difference of 45 degrees with the electric field is advantageous to obtain the maximum transmittance. In addition, a phase correction plate 310 is disposed between the upper substrate 305 and the decomposer 309 to compensate for refractive anisotropy of the liquid crystal.

Hereinafter, the in-plane switching vertically aligned mode liquid crystal display (IPS-VA LCD) having the above configuration operates as follows.

Before the voltage is applied to the liquid crystal display, as shown in FIG. 3A, the liquid crystal molecules 307a in the liquid crystal layer 307 may have long axes of the liquid crystal molecules 307a under the influence of the vertical alignment layers 303 and 306. The substrates are arranged in a form perpendicular to the substrates 301 and 305.

Therefore, the light passing through the polarizer 308 is blocked by not passing through the decomposer 309 to indicate a dark state. In this case, the refractive index anisotropy of the liquid crystal molecules 307a is compensated for by the phase compensator 310 to achieve a completely dark state on both the front and side surfaces of the screen.

In contrast, when a voltage is applied to the liquid crystal display, horizontal and elliptical electric fields are formed between the common electrode 302a, the pixel electrode 302b, and the auxiliary electrode 304 as shown in FIG. 3B. That is, the closer to the lower substrate 301, the horizontal electric field is formed, and the closer to the upper substrate 305, the elliptical electric field is formed. Accordingly, in the liquid crystal molecules 307a having a positive dielectric anisotropy, their long axes are arranged perpendicular to the electric field.

In this case, an electric field substantially perpendicular to the substrates 301 and 305 is formed between the common electrode 302a and the pixel electrode 302b disposed on the lower substrate 301, thereby providing liquid crystal molecules having positive dielectric anisotropy. The long axis of 307a is arranged perpendicular to the electric field. As a result, the transmittance is generated by the vertically arranged liquid crystal molecules 307a, so that no disclination line is generated on the screen.

3C illustrates a liquid crystal display device according to the present invention, specifically, a liquid crystal molecule 307a having a positive dielectric anisotropy, wherein the common electrode 302a and the pixel electrodes 302b on the lower substrate 301 are spaced at an interval of 10 μm. The common electrode 302a and the pixel electrode 302b are arranged in a length of 5 mu m, and the result of the simulation for 100 mV after a voltage of 6 V is applied is shown.

As shown in FIG. 3C, the liquid crystal molecules 307a are arranged along horizontal and elliptical electric fields, and exist in a center portion between the common electrode 302a and the pixel electrode 302b disposed on the lower substrate. Liquid crystal molecules are also arranged horizontally rather than perpendicular to the substrate, leaving no room for on-screen disclination lines. Accordingly, it can be seen through the drawings that the viewing angle as well as the transmission are also improved.

4 to 7 illustrate simulation results of a liquid crystal display according to another exemplary embodiment of the present invention under the same condition as the exemplary embodiment of FIG. 3.

In the liquid crystal display according to another exemplary embodiment of the present invention, as shown in FIG. 4, the auxiliary electrode 404 on the upper substrate overlaps the gap between the common electrode 402a and the pixel electrode 402b on the lower substrate. The distance between the common electrode 402a and the pixel electrode 402b on the lower substrate is less than that.

In addition, as shown in FIG. 5, the auxiliary electrode 504 on the upper substrate overlaps the common electrode 502a and the pixel electrode 502b on the lower substrate, and the length of the auxiliary electrode 504 is on the lower substrate. It is equal to the length of 502a and the pixel electrode 502b.

In addition, as shown in FIG. 6, the auxiliary electrode 604 on the upper substrate is disposed at a portion overlapping the gap between the common electrode 602a and the pixel electrode 602b on the lower substrate, and the common electrode on the lower substrate. It is not longer than the interval between 602a and the pixel electrode 602b.

As shown in FIG. 7, the auxiliary electrode 704 on the upper substrate overlaps with the common electrode 702a on the lower substrate, and the length thereof is not longer than the length of the common electrode 702a.

Here, in the liquid crystal display device according to another embodiment of the present invention shown in Figs. 4 to 7, it is advantageous that the auxiliary electrode on the upper substrate is made of a transparent conductor, for example, ITO, in terms of aperture ratio and transmittance. On the other hand, the common electrode and the pixel electrode on the lower substrate is composed of a transparent conductor or an opaque conductor, it is advantageous in terms of the aperture ratio and transmittance it is composed of a transparent conductor such as ITO.

The embodiments disclosed herein are adopted to illustrate the present invention and are not intended to limit the present invention thereto. In addition, it can implement in various changes in the range which does not deviate from the summary of this invention.

As described above, the liquid crystal display according to the present invention has the following effects.

In the present invention, by providing a slit-shaped auxiliary electrode on the upper substrate, no disclination line is generated, thereby improving transmittance, brightness, and viewing angle, thereby enabling a higher quality inplane switching vertical alignment mode liquid crystal display.

Claims (11)

Upper and lower substrates facing each other; A liquid crystal layer interposed between the upper and lower substrates; A liquid crystal display device comprising a common electrode and a pixel electrode disposed on an inner surface of the lower substrate to drive a liquid crystal. And a plurality of auxiliary electrodes formed on the inner surface of the upper substrate and having a predetermined width and a predetermined spacing, and interacting with electrodes formed on the inner surface of the lower substrate to drive the liquid crystal. The method of claim 1, And the auxiliary electrode is disposed to overlap the common electrode on the lower substrate and is not shorter than the length of the common electrode. The method of claim 1, And the auxiliary electrode is disposed at a portion overlapping a gap between the common electrode and the pixel electrode on the lower substrate, and is not shorter than a gap between the common electrode and the pixel electrode on the lower substrate. The method of claim 1, And the auxiliary electrode is disposed to overlap the common electrode and the pixel electrode on the lower substrate, and has the same length as the common electrode and the pixel electrode on the lower substrate. The method of claim 1, And the auxiliary electrode is disposed at a portion overlapping the gap between the common electrode and the pixel electrode on the lower substrate and is not longer than the gap between the common electrode and the pixel electrode on the lower substrate. The method of claim 1, And the auxiliary electrode overlaps with the common electrode on the lower substrate and is not longer than the length of the common electrode. The method according to claim 1 to 6, And the auxiliary electrode is formed of a transparent conductor. The method of claim 7, wherein The transparent conductor is ITO, characterized in that the liquid crystal display device. The method according to claim 1 to 6, And a common electrode and a pixel electrode on the lower substrate are made of a transparent conductor or a transparent conductor. The method of claim 9, The transparent conductor is ITO, characterized in that the liquid crystal display device. The method of claim 9, And a common gap between the common electrode and the pixel electrode on the lower substrate.