KR19990003557A - Liquid crystal display device and manufacturing method - Google Patents

Abstract

The present invention is disclosed in a liquid crystal display device and a high manufacturing method which have no light leakage and have improved left and right viewing angles.

Disclosed is a liquid crystal display device comprising an upper and lower substrate facing each other, a liquid crystal interposed between the upper and lower substrates, and an upper and lower alignment layer formed on a liquid crystal facing surface of the upper and lower substrates. The molecules in the cell are characterized in that when the electric field is not applied, arranged in a scalloped shape.

Description

Liquid crystal display device and manufacturing method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display element and a method for manufacturing the same, and more specifically, an upper and lower alignment layer formed on a liquid crystal interposed between opposing upper and lower substrates and upper and lower substrates, and a liquid crystal opposing surface of the upper and lower substrates. It relates to a liquid crystal display device and a method of manufacturing the same.

Generally, a liquid crystal display element constitutes display elements, such as a television and a graphic display. In particular, the active matrix type liquid crystal display device has high-speed response characteristics and is suitable for a high number of pixels, thereby greatly contributing to realizing high quality, large size, color screen, and the like of a display screen.

The liquid crystal display device includes a pair of transparent insulating substrates, a thin film transistor and a pixel electrode formed on at least one substrate, a color filter and a counter electrode on the other substrate, and a liquid crystal material between the pair of glass substrates. This is done by encapsulation. This liquid crystal display element has an electric field formed between the pixel electrode and the counter electrode, and is driven in accordance with this electric field direction.

Such a liquid crystal display element determines the characteristic by contrast ratio which is the brightness of the screen at the time of electric field application with respect to the brightness of the screen when an electric field is not applied, and left and right viewing angles.

Conventionally, an In Plane Switching mode (IPS) having excellent contrast ratio and right and left viewing angles has been proposed.

In the liquid crystal display of the IPS mode, the counter electrode 2 and the pixel electrode 4, which are electrodes for operating the liquid crystal interposed between the lower substrate 1 and the upper substrate 6 facing each other, are illustrated in FIG. 1A. As described above, they are formed on the lower substrate 1 with different steps.

Here, the counter electrode 2 is formed on the surface of the lower substrate 1 together with the gate line (not shown), and a gate insulating film 3 is formed on the lower substrate 1. At this time, the counter electrode 2 has a rectangular frame shape when viewed in a planar form, and is represented by a pair of patterns on the cross section. Thereafter, data lines (not shown) and pixel electrodes 4 are formed in predetermined portions of the gate insulating film 3. In this case, the pixel electrode 4 is spaced apart from the counter electrode 2. Thereafter, a lower alignment layer 5, preferably a horizontal alignment layer, is formed above the resultant, so that the liquid crystal molecules 6 are arranged in a predetermined direction before an electric field is applied to the liquid crystal display element.

On the other hand, the color filter 7 and the upper alignment film 8 are formed in the opposing upper substrate 6.

Although not shown in the drawing, a polarizing plate (not shown) for deflecting incident light in a predetermined direction is provided on the rear surfaces of the lower substrate 1 and the upper substrate 6. Here, the polarization axis of the polarizing plate formed on the back side of the lower substrate 1 coincides with the rubbing axis of the lower alignment layer 5. In addition, the lower alignment layer 5 and the upper alignment layer 8 are antiparallel rubbing so that the liquid crystals are arranged in the same direction. The part indicated by the arrow in the figure is the rubbing direction.

As described above, when the electric field is not applied, the liquid crystal display of the IPS mode is arranged such that the rubbing side of the alignment layer 5 and the long axis of the liquid crystal molecules coincide with each other. In this case, a predetermined pretilt angle is given to the alignment film 5 in order to improve the response speed of the liquid crystal display small value. Therefore, the liquid crystal molecules are arranged to be horizontal to the substrate surface, and are preliminary at a predetermined angle.

On the other hand, when an electric field is applied, as shown in FIG. 1B, an electric field F is formed between the counter electrode 2 and the pixel electrode 4. Then, the long axis of the liquid crystal molecules 6 is driven in parallel with the electric field direction. At this time, incident light is leaked. At this time, when the electric field is applied, since the liquid crystal is lying down (in the case of liquid crystal having a positive dielectric anisotropy), the left and right viewing angles are improved, and when the electric field is not applied, the light is completely blocked, so the contrast ratio is improved.

However, the above-mentioned liquid crystal display element of the IPS mode is given a predetermined pre-tilt angle, which causes the following problems.

That is, since the counter electrode 2 and the pixel electrode 4 have a predetermined step, a reverse tilt domain in which the liquid crystal molecules lie in the opposite direction to the array direction is generated at this step portion. This reverse tilt domain phenomenon (indicated by R in FIG. 1A) causes a problem of leakage of light when no electric field is applied.

In order to improve this, when the pretilt is applied at a larger angle, the left and right viewing angles are different, which causes a problem that the left and right phase difference characteristics are deteriorated.

Accordingly, an object of the present invention is to provide a liquid crystal display device capable of preventing the reverse tilt domain phenomenon due to the pretilt angle of the liquid crystal display device and improving the left and right phase difference characteristics.

1A and 1B are cross-sectional views for explaining a conventional liquid crystal display device.

2 is a cross-sectional view of a liquid crystal display device according to the present invention.

* Explanation of symbols for main parts of the drawings

10 lower substrate 11: alignment film

20: upper substrate 25: liquid crystal

26: liquid crystal molecules

In order to achieve the above object of the present invention, the liquid crystal display device of the present invention, the upper and lower substrates facing each other, the liquid crystal interposed between the upper and lower substrates, the image formed on the liquid crystal facing surface of the upper and lower substrates A liquid crystal display device comprising a lower alignment film, wherein the molecules in the liquid crystal are arranged in a fan shape when no electric field is applied.

In addition, the method of manufacturing a liquid crystal display device as described above may include providing a lower substrate having electrodes and an upper substrate opposite thereto, forming an alignment layer on each of the upper and lower substrates, and aligning the alignment layers in the same direction. Performing a parallel rubbing, bonding the upper and lower substrates, and injecting a liquid crystal between the upper and lower substrates.

According to the present invention, by rubbing the upper and lower alignment layers in parallel so that the liquid crystal molecules are arranged in an unapplied fan shape of an electric field between the upper and lower substrates, there is an advantage of preventing light leakage when the electric field is turned off and improving the viewing angle. have.

EXAMPLE

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

2 is a cross-sectional view schematically showing a liquid crystal display device according to the present invention.

Referring to FIG. 2, a lower substrate 10 having a gate line (not shown) and a data line (not shown), a counter electrode (not shown), and a pixel electrode (not shown) arranged in an active matrix form. ) And an upper substrate 20 opposed thereto. At this time, the upper substrate 20 is provided with a color filter (not shown) and a black matrix (not shown) for dividing the color filters.

The liquid crystal 25 made of a plurality of liquid crystal molecules 26 is interposed between the lower substrate 10 and the upper substrate 20.

Here, alignment layers 11 and 21 for arranging the liquid crystal molecules 26 in a predetermined direction when no electric field is applied to the liquid crystal display elements on the opposite surfaces of the liquid crystal 25 of the lower substrate 10 and the upper substrate 20. Is formed. At this time, the upper and lower alignment layers 11 and 21 according to the present embodiment are parallel rubbing in the same direction, as indicated by arrows in the drawing, and at the same time, about 2 to 10 on both alignment layers 11 and 21. Rubbing is carried out to have a pretilt angle θ of about degrees. Then, the liquid crystal molecules 26 are arranged in a fan shape between the upper and lower substrates 20 and 10, as shown in FIG. 2.

Thus, when the liquid crystal molecules are arranged in a fan shape, no reverse tilt domain is generated even if a step is present, and even if the pretilt angle is a relatively large value, light leakage is prevented by the self-compensation effect, and the liquid crystal display device is symmetrical in up, down, left, and right directions. As a result, the left and right viewing angles are improved.

In the present embodiment, a liquid crystal display device of the IPS mode in which the counter electrode and the pixel electrode are formed on the lower substrate has been described as an example. However, the present invention is not limited thereto, and any liquid crystal molecules are arranged in a fan shape by parallel rubbing. It is included in the invention.

As described in detail above, according to the present invention, by rubbing the upper and lower alignment layers in parallel so that the liquid crystal molecules are arranged in an unapplied fan shape of an electric field between the upper and lower substrates, light leakage is prevented when the electric field is turned off, and a viewing angle is obtained. There is an advantage to improve.

Thus, reverse tilt domain phenomenon is prevented.

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

Claims (5)

A liquid crystal display device comprising an opposing upper and lower substrates, a liquid crystal interposed between the upper and lower substrates, and an upper and lower alignment layers formed on the liquid crystal opposing surfaces of the upper and lower substrates, wherein the molecules in the liquid crystals have an electric field. A liquid crystal display device, characterized in that when not applied, arranged in a fan shape. The liquid crystal display of claim 1, wherein the molecules in the liquid crystal are pretilted at a predetermined angle when no electric field is applied. 3. The liquid crystal display of claim 2, wherein the molecules in the liquid crystal are pretilt of 2 to 10 °. 4. Providing a lower substrate having electrodes and an upper substrate opposite thereto, forming an alignment layer on each of the upper and lower substrates, rubbing the alignment layers in the same direction, and bonding the upper and lower substrates together. And injecting a liquid crystal between the upper and lower substrates. The method of claim 4, wherein in the rubbing of the alignment layer, the molecules in the liquid crystal are rubbed to be pretilt.