KR20000014528A - Light visual field angle liquid crystal display apparatus - Google Patents

Abstract

PURPOSE: A light visual field angle liquid crystal display apparatus is provided to enlarge a light visual field angle of a liquid crystal display apparatus and prevent miss-matching between patterns formed on an upper substrate and a lower substrate. CONSTITUTION: The apparatus comprises a first substrate, a common electrode formed on the first substrate and having a first opening pattern for separately orienting a liquid crystal, a second substrate corresponding to the first substrate, and a pixel electrode formed on the second substrate and having second opening pattern for separately orienting the liquid crystal. An end edge of the first and the second opening pattern is separated at more than matching error of the second substrate intervals.

Description

Wide viewing angle liquid crystal display device

The present invention relates to a wide viewing angle liquid crystal display device.

In general, a liquid crystal display device has a structure in which a liquid crystal is injected between two substrates, and the amount of light transmitted is controlled by adjusting the intensity of the electric field applied thereto.

A vertically aligned twisted nematic (VATN) type liquid crystal display includes a pair of transparent substrates having transparent electrodes formed on an inner surface thereof, a liquid crystal material between two transparent substrates, and an outer surface of each transparent substrate. It consists of two polarizers attached to and polarizing light. In the state in which no electric field is applied, the liquid crystal molecules are vertically oriented with respect to the two substrates, and when the electric field is applied, the liquid crystal molecules filled between the two substrates are parallel to the substrate and twist in a spiral with a constant pitch.

In the case of the VATN liquid crystal display, the liquid crystal molecules are vertically aligned with respect to the substrate in the state in which no electric field is applied, and thus, when the polarizing plate is perpendicular to each other, light may be completely blocked in the state in which the electric field is not applied. That is, since the luminance of the off state is very low in the normally black mode, a high contrast ratio may be obtained as compared with a conventional twisted nematic liquid crystal display. However, in a state where an electric field is applied, particularly in a state where a gradation voltage is applied, as in the normal twisted nematic mode, there is a problem in that the viewing angle is narrow due to a large difference in retardation of light depending on the viewing direction of the liquid crystal display. .

In order to improve the viewing angle characteristic, an opening pattern is formed on the transparent electrode of the liquid crystal display substrate or a projection pattern is formed on the substrate surface to form different regions in which the alignment directions of the liquid crystal molecules are reversed around the pattern. However, misalignment may occur between the patterns of the upper and lower substrates, and such mismatches cause defects such as light leakage or a short circuit between the two substrates.

An object of the present invention for solving this problem is to widen the viewing angle of the liquid crystal display.

Another object of the present invention is to prevent mismatching between patterns formed on upper and lower substrates.

1 to 3 are cross-sectional views illustrating the principle of divided alignment of a vertically aligned liquid crystal display according to an exemplary embodiment of the present invention.

4 is a plan view illustrating a pattern for split alignment of the vertically aligned liquid crystal display according to the first exemplary embodiment of the present invention;

5A to 5C are enlarged views of a portion A of FIG. 4,

6 is a plan view illustrating a pattern for split alignment of a vertically aligned liquid crystal display according to a second exemplary embodiment of the present invention.

7A to 7C are enlarged views of a portion B of FIG. 6,

8A to 8C are enlarged views of portion C of FIG. 6.

In order to solve the above problems, in the liquid crystal display according to the present invention, patterns for splitting and aligning liquid crystals are formed on upper and lower substrates, respectively, and adjacent ends of the upper and lower substrate patterns are matched with the upper and lower substrates. The intervals exceed the error degree or are overlapped with the width equal to or greater than the matching error.

As described above, the viewing angle can be widened by varying the alignment direction of the liquid crystal molecules using the upper and lower patterns, and the end portions of the adjacent patterns are formed to have a gap greater than the left and right matching error or overlap the width of the matching error. It is possible to prevent display quality deterioration caused by a mismatch between two substrates.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

FIG. 1 illustrates a proposed structure and principle for compensating a viewing angle in a vertical alignment liquid crystal display according to an exemplary embodiment of the present invention, and illustrates a structure in which protrusions for split alignment are formed on a liquid crystal display substrate.

As shown in FIG. 2, serrated protrusions 100 are formed on the lower and upper substrates 1 and 2, and the protrusions 100 are arranged at a predetermined distance from each other, and the height of the protrusions 100 is It is about 1-2 micrometers. In addition, the vertical alignment films 3 and 4 are formed on the protrusions 100, respectively.

Since the protrusions 100 are arranged to be perpendicular to the surface by the alignment force of the alignment layers 3 and 4, the liquid crystal molecules 5 around the protrusions 100 are not exposed to the surface of the protrusions 100 when no electric field is applied. It will be tilted in a direction perpendicular to.

If a sufficient electric field is applied between the two substrates 1, 2, the liquid crystal molecules 5 are arranged in parallel to the substrates 1, 2 while being twisted since they tend to be perpendicular to the direction of the electric field. In the initial state, since the liquid crystal molecules 5 on both sides of the protrusion 100 are inclined by a predetermined angle in opposite directions, the liquid crystal molecules 5 lie along the initial inclined direction. Is moved so that the lying direction is reversed, so that two regions in which the inclination directions of the liquid crystal molecules 5 are opposite to each other with respect to the center line of the protrusion 100 are compensated, and the optical characteristics of the two regions are compensated to each other to widen the viewing angle. do.

FIG. 2 illustrates a proposed structure and principle for compensating a viewing angle in a vertically aligned liquid crystal display according to an exemplary embodiment of the present invention, in which an opening pattern for divided alignment is formed on a transparent electrode of a liquid crystal display substrate. Indicates.

As shown in FIG. 2, portions of the transparent pixel electrode 20 on the lower substrate 1 and the transparent common electrode 30 on the upper substrate 2 are removed to form opening patterns 200, respectively. The opening patterns 200 are arranged at a predetermined distance from each other.

When voltage is applied to the pixel electrode 20 and the common electrode 30, a fringe field in which an electric field is bent is formed near the opening pattern 200, so that the liquid crystal molecules 5 form the centerline of the opening pattern 200. On the basis of the two sides are formed inclined in the opposite direction from each other. Thus, the optical properties are compensated and the viewing angle is widened.

3 illustrates a proposed structure and principle for compensating a viewing angle in a vertically aligned liquid crystal display according to an exemplary embodiment of the present invention.

As shown in FIG. 3, an opening pattern 200 in which a part of the transparent pixel electrode 20 is removed is formed on the lower substrate 1, and the upper substrate 2 is spaced apart from the opening pattern 200 by a predetermined distance. The protrusion 100 is formed at the point. In addition, the alignment film 4 covers the protrusion 100.

In this way, the liquid crystal molecules 5 are bipartially oriented in different directions between the patterns 200 and 100 formed above and below each other.

Using the method of forming the patterns 200 and 100 in such embodiments, it is possible to perform a split orientation without a process such as rubbing, and to very finely adjust regions having different arrangements of liquid crystal molecules or to make various shapes. There is an advantage.

However, when the divided alignment is performed, characteristics of the panel such as luminance, response speed, and afterimage vary depending on the type of the alignment. Therefore, it becomes an important problem how to form the patterns for the split orientation.

This pattern form is illustrated in FIGS. 4 to 6.

First, the first embodiment of the present invention shown in FIG. 4 will be described. In FIG. 4, only one pixel area is illustrated, and only the patterns of the upper and lower substrates are illustrated without other components, such as a thin film transistor and wiring. Such patterns may be formed in the form of protrusions on both the upper and lower substrates, or may be formed in the form of opening patterns, and may be formed in the form of protrusions on the upper substrate and in the form of opening patterns on the lower substrate. The case where the opening pattern is formed in all the board | substrates is demonstrated, for example.

4 is a plan view illustrating an opening pattern for split alignment of the vertically aligned liquid crystal display according to the first exemplary embodiment of the present invention.

As shown in FIG. 4, the liquid crystal display according to the present invention includes a thin film transistor substrate 1, which is a lower plate, and a color filter substrate (not shown), which is an upper plate.

Opening patterns 250 and 150 in which a part of the pixel electrode 20 of the thin film transistor substrate 1 and a part of the common electrode (not shown) of the color filter substrate are removed are formed, and accordingly, when the electric field is applied, the opening pattern ( The fringe fields are formed by 250 and 150. The opening patterns 250 and 150 alternately appear on the upper plate 1 and the lower plate.

Referring to the shapes of the opening patterns 250 and 150, a rectangular annular opening pattern 150 is formed in the color filter substrate, and a cross-shaped opening pattern 250 is formed in the thin film transistor substrate 1. . In this case, the opening patterns formed on the color filter substrate and the thin film transistor substrate in both the horizontal direction and the vertical direction alternately appear.

On the other hand, the rectangular annular opening pattern 150 formed on the color filter substrate is formed in the shape of the center of each side is cut off, but this is formed in this way to transmit a signal to the common electrode, the opening pattern formed on the two substrates ( Edges 150 and 250 may be formed to be as close as possible so that the micro area defined by the opening patterns 150 and 250 formed on the two substrates is formed close to the closed rectangle when the liquid crystal display is viewed from above.

The width of the opening patterns 150 and 250 is narrowed toward the center of each side from the vertex of the rectangular ring formed so that the opening pattern 150 is bent, and also the width of the opening patterns 150 toward the edge from the center of the cross-shaped opening pattern 250. Narrows. In this case, the opening pattern formed on one of the substrates has an angle greater than 90 degrees at the bent portion, and when viewed from above, the opening pattern formed at both substrates has an angle smaller than 90 degrees, and thus the disclination at the end portion. This decreases.

The upper and lower substrates may have a protrusion pattern instead of the opening patterns 150 and 250 or a case in which the opening pattern and the protrusion pattern are formed on the upper and lower substrates, respectively. In this case, the principle and effect of the divided alignment are similar.

FIG. 5A is a plan view illustrating an enlarged view of a portion A of FIG. 4, and illustrates a case where patterns deviate by a range equal to or greater than a matching error at a region where an area division boundary meets.

As shown in FIG. 5A, when an upper and lower plate matching error occurs and the opening pattern 250 of the upper color filter substrate is shifted (S1) beyond the matching degree error Lx in one direction, the upper color filter substrate An end portion of the opening pattern 250 largely escapes an end portion of the opening pattern 250 formed in the pixel electrode 20 of the lower thin film transistor substrate and overlaps the opening pattern 250 inside the pixel electrode 20. . Therefore, irregular texture of liquid crystal molecules occurs between the overlapped portions and the ends of the opening patterns 250.

In the case of the projection pattern, not the opening pattern, as described above, the height of the projection is about 1 to 2 μm and the distance between the two substrates is 3 to 4 μm, which may cause a problem of shorting of the upper and lower plate protrusions.

In order to prevent such top and bottom plate matching errors from occurring, the horizontal direction formed in the thin film transistor substrate from the left or right edge of the opening pattern 150 formed in the vertical direction in the color filter substrate as shown in FIG. 5B. The distance to the right or left end of the opening pattern 250 is greater than or equal to the matching degree error Lx. In this case, the boundary between the opening patterns 150 and 250 does not meet when the left and right matching error occurs.

Alternatively, as shown in FIG. 5C, the degree of overlapping the width of the opening pattern 150 in the vertical direction with the opening pattern 250 in the horizontal direction is greater than or equal to the matching degree error Lx. In this case, even when left and right matching errors occur, the boundaries of the spaced region division patterns do not meet each other.

FIG. 5 is a plan view illustrating a projection pattern for divided alignment of a vertically aligned liquid crystal display according to a second exemplary embodiment of the present invention. FIG.

The liquid crystal display according to the second exemplary embodiment of the present invention includes a thin film transistor substrate which is a lower plate and a color filter substrate which is an upper plate.

Projections 190 and 180 are formed on the pixel electrode 20 of the lower plate and the common electrode of the upper plate.

The protrusions 180 formed on the color filter substrate and the protrusions 190 formed on the thin film transistor substrate are both formed in the shape of being bent in a sawtooth shape at the center of the vertical direction of the pixel, and the protrusions 180 and 190 formed on the two substrates alternate with each other. It is formed. The branch protrusion 182 is formed to cross the center of the sawtooth shape, and the protrusion of the thin film transistor substrate is formed at a portion where the boundary of the pixel electrode 20 and the protrusion 180 of the color filter substrate meet. Branch projections 181 extending toward 190 are formed. In this way, the edges of the projections of the upper and lower plates are close to each other, and the projections are formed at an obtuse angle to eliminate the foreground.

Instead of the protrusion patterns 180 and 190 of the upper and lower substrates, the opening pattern may be formed in the same shape as in the second embodiment, or the protrusion pattern may be formed in the upper plate and the opening pattern may be formed in the same shape in the lower plate.

FIG. 7A is a plan view illustrating an enlarged view of portion B of FIG. 4.

As shown in FIG. 7A, the upper and lower plate matching errors are generated, so that the protrusions 180 of the upper color filter substrate are shifted in the vertical direction (S2) so that the branch protrusions 181 and the protrusions 180 of the lower thin film transistor substrate are formed. Overlaps. As mentioned above, since the heights of the protrusions 180, 181, and 190 are 1 to 2 mu m, and the two substrate gaps are 3 to 4 mu m, a short circuit between the protrusions may occur.

In order to prevent this, as shown in FIG. 8B, the boundary between the branch protrusion 181 and the lower protrusion 190 is formed to have an interval greater than or equal to the interval between the vertical matching errors Ly. This can prevent the occurrence of short circuit of the projections between the upper and lower plates.

In addition, when the projections are spaced apart, the edge of the pixel electrode 20 is exposed so that the irregular arrangement of the liquid crystal molecules does not occur so that the horizontal matching degree error Lx is positioned inside the pixel electrode 20.

8A is a plan view illustrating an enlarged view of portion C of FIG. 4.

As shown in FIG. 8A, branch protrusions 182 formed in a shape that crosses the center of the sawtooth-shape portion due to a top and bottom plate matching error are shifted toward the protrusions 190 of the thin film transistor substrate (shift: S3). In this case, the two protrusions 182 and 190 are shorted to generate a short circuit of the upper and lower substrates.

In the case of an opening pattern rather than a projection pattern, irregular arrangement structure of liquid crystal molecules occurs at the overlapping portion.

In order to prevent this, as shown in FIG. 8B, the branch protrusion 182 is formed to have a distance equal to or greater than the vertical and horizontal matching errors Ly and Lx with the protrusion 190 of the thin film transistor substrate.

Alternatively, as shown in FIG. 8C, the two protrusions 182 and 190 overlap with a width equal to or more than the horizontal matching error Lx.

As described above, in the vertical alignment liquid crystal display using split alignment according to the exemplary embodiment of the present invention, the viewing angle may be widened by varying the alignment direction of the liquid crystal molecules using various protrusion patterns, and the end of the protrusion or opening pattern may be increased. Is formed to have a gap equal to or greater than the left and right matching error or overlaps with a width equal to or greater than the matching error, thereby preventing display quality degradation due to occurrence of a matching error of the two substrates.

Claims (3)

First substrate, A common electrode formed on the first substrate and having a first opening pattern for partially aligning the liquid crystal; A second substrate corresponding to face the first substrate, A pixel electrode formed on the second substrate and having a second opening pattern for dividing and aligning the liquid crystal; The adjacent end portions of the first and second opening patterns may be spaced apart from each other by more than a matching degree error of the first substrate and the second substrate, or overlap with a width equal to or more than the matching degree error. First substrate, A first protrusion formed on the first substrate, for dividing and aligning the liquid crystal; A second substrate corresponding to face the first substrate, It is formed on the second substrate and includes a second projection for dividing the alignment of the liquid crystal, Adjacent ends of the first and second protrusions are spaced apart from each other by mismatching errors of the first substrate and the second substrate, or overlapping with a width greater than the mismatching error. First substrate, Projections formed on the first substrate for dividing and aligning the liquid crystal; A second substrate corresponding to face the first substrate, A pixel electrode formed on the second substrate, the pixel electrode having an opening pattern for partially aligning the liquid crystal; Adjacent ends of the protrusions and the opening patterns may be spaced apart from each other by mismatching errors of the first substrate and the second substrate, or overlapping with a width greater than the mismatching error.