KR100614695B1 - Han mode lcd and method for manufacturing the same - Google Patents

Abstract

The present invention discloses a HAN mode liquid crystal display device and a method of manufacturing the same. The present invention discloses a lower substrate having a pixel electrode; An upper substrate bonded to the lower substrate at a predetermined distance and having a counter electrode forming an electric field together with the pixel electrode; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; A first alignment agent interposed between the liquid crystal layer and the lower substrate; And a second alignment agent interposed between the liquid crystal layer and the upper substrate, wherein one of the first alignment agent and the second alignment agent is a horizontal alignment agent, and the other is a vertical alignment agent. Either of the second or second alignment agent is formed of a photo alignment agent, and the other is formed of a polyimide.

Description

ICH mode liquid crystal display device and its manufacturing method {HAN MODE LCD AND METHOD FOR MANUFACTURING THE SAME}

1A and 1B are cross-sectional views of a conventional H.N mode liquid crystal display device.

2A to 2C are cross-sectional views of a liquid crystal display of HAN mode according to an embodiment of the present invention.

(Explanation of symbols for the main parts of the drawing)

20: lower substrate 22: vertical alignment agent

30 upper substrate 32 photoaligning agent

32a: horizontal alignment agent

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to an etch-a yen (hereinafter referred to as HAN) comprising an upper substrate having a vertical alignment agent formed thereon, a lower substrate facing and having a horizontal alignment agent formed therebetween, and a liquid crystal interposed therebetween. It relates to a liquid crystal display element in mode.

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 high quality, large size, and color display of a display screen.

Herein, a liquid crystal display of a hybrid alignment nemetic (HAN) mode among various conventional liquid crystal modes will be described with reference to FIGS. 1A and 1B.

Referring to FIG. 1A, upper and lower substrates 1 and 2 face each other with the liquid crystal layer 3 interposed therebetween. A horizontal alignment agent 4 is formed between the upper substrate 1 and the liquid crystal layer 3 to align the long axis of the liquid crystal molecules 3a horizontally with the surfaces of the substrates 1 and 2. A vertical alignment agent 5 is formed between the liquid crystal layers 3 to orient the long axes of the liquid crystal molecules 3a perpendicularly to the surfaces of the substrates 1 and 2. In this case, a counter electrode (not shown) is formed between the upper substrate 1 and the vertical alignment agent 4, and a pixel electrode (not shown) is disposed between the lower substrate 2 and the horizontal alignment agent 5, respectively. Is formed. In addition, upper and lower polarizers (not shown) are provided on the back surfaces of the upper and lower substrates 1 and 2 facing each other, and the polarization axes of the upper and lower polarizers are crossed. At this time, the horizontal alignment agent 5 is rubbed in a predetermined direction, and this rubbing axis coincides with the polarization axis of the lower polarizing plate.

Before the electric field is formed in the liquid crystal display device of the HAN mode having such a configuration, the long axis of the liquid crystal molecules 3a is arranged perpendicular to the surface of the lower substrate 2. The longer axis is arranged in parallel with the surface of the substrates 1 and 2 under the influence of the horizontal alignment agent 4 on the upper substrate 1 side toward the upper substrate 1. Therefore, light passing through the lower polarizer passes through the upper polarizer, and the screen becomes white.

On the other hand, when a voltage is applied, an electric field perpendicular to the substrates 1 and 2 between the upper and lower substrates 1 and 2, more preferably, between the counter electrode and the pixel electrode of the lower substrate 2. Is formed. Accordingly, the liquid crystal molecules 3a (when the dielectric anisotropy is positive) are arranged such that the long axis is perpendicular to the substrate such that the electric field and the long axis coincide. Accordingly, the light passing through the lower polarizer is blocked by the upper polarizer (not shown), so that the screen becomes dark.

However, the above-described conventional liquid crystal display of the HAN mode has the following problems.

First, the horizontal alignment agent 4 and the vertical alignment agent 5 of the liquid crystal display element of the HAN mode described above are all optical alignment agents whose orientation is determined by light, and such horizontal and vertical alignment agents (4,5) Is formed on the substrate resultant surface in an unaligned state, and then proceeds to a predetermined light treatment to have orientation. In addition, the light treatment is performed under the same conditions so that the horizontal and vertical alignment agents 4 and 5 of the HAN mode liquid crystal display are provided with the same force, that is, the force (hereinafter, anchoring force) to anchor the liquid crystal molecules.

However, as described above, when the horizontal and vertical alignment agents 4 and 5 are optically treated to have the same anchoring force, even when an electric field is applied, the liquid crystal molecules 3a exert the same force from the horizontal and vertical alignment agents 4 and 5. As a result, the balance of force is not broken, so it cannot easily move in the electric field direction. As a result, since the moving time of the liquid crystal molecules is delayed, the main purpose of the HAN mode liquid crystal display device to improve the response speed is not achieved.

In addition, since the photo-alignment agent is very sensitive to heat or physical force, the photo-alignment agent is formed on the upper and lower substrate result surfaces, and then the bonding process of the upper and lower substrates is performed. It is easy to be changed or damaged by the force. As such, when the characteristics of the alignment agent are changed or damaged, the liquid crystal molecules 3a cause a misalignment, and the screen characteristics are deteriorated.

Accordingly, an object of the present invention is to provide a HAN mode liquid crystal display device capable of improving the response speed.

Moreover, another object of this invention is to provide the manufacturing method of the HAN mode liquid crystal display element which can prevent the characteristic change and damage of an oriented film.

In order to achieve the above object of the present invention, according to one aspect of the invention, the lower substrate having a pixel electrode; An upper substrate bonded to the lower substrate at a predetermined distance and having a counter electrode forming an electric field together with the pixel electrode; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; A first alignment agent interposed between the liquid crystal layer and the lower substrate; And a second alignment agent interposed between the liquid crystal layer and the upper substrate, wherein one of the first alignment agent and the second alignment agent is a horizontal alignment agent, and the other is a vertical alignment agent, and the first alignment agent Any one of the first and second alignment agents is formed of a photo alignment agent which is oriented by application of light after bonding of the lower substrate and the upper substrate, and the other is formed of polyimide to have different anchoring forces.

The dielectric anisotropy of the liquid crystal molecules in the liquid crystal layer is characterized in that 2 to 15 or -15 to -2, the product of the refractive index anisotropy of the liquid crystal molecules and the upper and lower substrates is 0.3 to 1.6㎛.

According to another aspect of the invention, preparing a lower substrate having a first alignment agent having a direction in a predetermined direction on the surface on which the pixel electrode is formed; Preparing an upper substrate facing the lower substrate, the upper substrate having a second alignment agent provided with directivity by light without having any orientation on the surface on which the counter electrode is formed; Bonding the upper and lower substrates so that the first and second alignment agents face each other; And irradiating light at the bottom of the lower substrate to impart orientation to the second alignment agent, wherein either the first alignment agent or the second alignment agent is a horizontal alignment agent, and the other is a vertical alignment. Characterized in that the Jane.

In addition, the present invention provides a method for preparing a lower substrate, comprising: preparing a lower substrate on which a first alignment agent to be provided by light is provided without having any orientation on a surface on which a pixel electrode is formed; Preparing an upper substrate facing the lower substrate and having a second alignment agent having a direction in a predetermined direction on a surface on which the counter electrode is formed; Bonding the upper and lower substrates so that the first and second alignment agents face each other; And irradiating light from the outside of the upper substrate to impart orientation to the first alignment agent, wherein either the first alignment agent or the second alignment agent is a horizontal alignment agent, and the other is vertical. It is an alignment agent, It is characterized by the above-mentioned.

According to the present invention, a horizontal alignment agent made of photo-alignment agent is formed on the upper substrate, and a vertical alignment agent made of general polyimide is formed on the lower substrate. Accordingly, since the anchoring forces of the two alignment agents are not the same, when the electric field is applied, the balance of the anchoring force between the vertical alignment agent and the horizontal alignment agent is quickly broken, so that the liquid crystal molecules operate quickly in the electric field direction. Accordingly, the response speed is greatly improved.

In addition, since the horizontal alignment agent made of the light alignment agent undergoes light treatment after thermal bonding of the upper and lower substrates, the horizontal alignment agent is not affected by heat and physical force. Therefore, the characteristic change and damage of an aligning agent can be reduced, and a screen characteristic is improved.

(Example)

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

2A to 2C are cross-sectional views of the liquid crystal display of the HAN mode according to the embodiment of the present invention.

As shown in FIG. 2A, a lower substrate 20 including a pixel electrode (not shown) and an upper substrate 30 including a counter electrode (not shown) are prepared. On one side of the lower substrate 20, a vertical alignment agent 22 made of a general polyimide, rather than a photo alignment agent, is formed. On the other hand, one side of the upper substrate 30 does not have any orientation, when the light is applied, the light alignment agent 32 having an orientation is formed.

Then, as shown in FIG. 2B, the seal 28 is printed on the edge of the lower substrate 20 on which the vertical alignment agent 22 is formed by a known screen printing technique. At this time, as the seal 28 is known, the portion to be injected thereafter is formed to be opened. Subsequently, the upper substrate 30 faces the photo alignment agent 32 and the vertical alignment agent 22 to face each other, and then the upper substrate 30 and the lower substrate 20 are thermally bonded to have a predetermined distance. At this time, even if the upper and lower substrates 30 and 20 are thermally bonded together, the photoaligning agent 32 formed on the upper substrate 30 is not treated to have any orientation and orientation, and thus does not affect the film.

Then, as shown in FIG. 2C, the mask 50 including the transmission part 50a and the light blocking part 50b is disposed on the bottom surface of the lower substrate 20, and then light is incident from the bottom surface of the substrate. In this way, as the light passing through the mask 50 is incident on the photoaligning agent 32, the photoaligning agent 32 is given a predetermined directionality and anchoring force, and becomes the horizontal alignment agent 32a. At this time, in the light treatment for forming the horizontal alignment agent 32a, in order to obtain a more symmetrical viewing angle characteristic, it is preferable to perform light treatment so that the horizontal alignment agent 32a has directionality in at least two symmetric directions.

Subsequently, although not shown in the figure, a liquid crystal including several liquid crystal molecules is injected between the lower substrate 20 and the upper substrate 30 through the open area of the seal 28 to form the upper and lower substrates 30 and 20. The liquid crystal layer is formed between the layers. Here, the liquid crystal molecules may use both positive and negative dielectric anisotropy (Δε), and preferably, a liquid crystal having a dielectric anisotropy (Δε) of 2 to 15 or -15 to -2. In addition, in order to obtain an appropriate screen transmittance, the phase delay value defined by the product of the distance between the upper and lower substrates and the refractive index anisotropy (Δn) of the liquid crystal molecules is suitably about 0.3 to 1.6 µm.

In such a HAN mode liquid crystal display device, the alignment agent 32 formed on the upper substrate 30 is a photo alignment agent, and the alignment agent 22 formed on the lower substrate 20 is formed of polyimide, which is a general alignment agent component. Therefore, the two alignment agents 32 and 22 do not have the same anchoring force because the components, the alignment conditions, and the alignment methods of the alignment agents are different. Accordingly, when an electric field is formed between the pixel electrode and the relative full width, the balance of the anchoring force is quickly broken between the vertical alignment agent 22 and the horizontal alignment agent 32a, so that the liquid crystal molecules operate quickly in the electric field direction.

In addition, since the horizontal alignment agent 32a undergoes light treatment after thermal bonding of the upper and lower substrates 30 and 20, the horizontal alignment agent 32a is not affected by heat and physical force.

This invention is not limited only to the above-mentioned embodiment. In the present embodiment, the vertical alignment agent 22 is formed on the lower substrate 20, and the horizontal alignment agent 32 is formed on the upper substrate 30. On the contrary, the horizontal alignment agent is formed on the lower substrate. Vertical alignment agents may be formed on the substrate.

In this embodiment, the alignment agent formed on the upper substrate is used as the photoalignment agent, and the alignment agent formed on the lower substrate is formed using the general alignment agent. On the contrary, the alignment agent formed on the upper substrate is used as the general alignment agent. After the alignment agent formed in the above is a photoalignment agent, the same effect can be obtained even if light processing is performed by injecting light from the outside of the upper substrate after joining the upper and lower substrates.

As described in detail above, according to the present invention, a horizontal alignment agent made of photo-alignment agent is formed on the upper substrate, and a vertical alignment agent made of general polyimide is formed on the lower substrate. Accordingly, since the anchoring forces of the two alignment agents are not the same, when the electric field is applied, the balance of the anchoring force between the vertical alignment agent and the horizontal alignment agent is quickly broken, so that the liquid crystal molecules operate quickly in the electric field direction. Accordingly, the response speed is greatly improved.

In addition, since the horizontal alignment agent made of the light alignment agent undergoes light treatment after thermal bonding of the upper and lower substrates, the horizontal alignment agent is not affected by heat and physical force. Therefore, the characteristic change and damage of an aligning agent can be reduced, and a screen characteristic is improved.

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

Claims (13)

A lower substrate having a pixel electrode; An upper substrate bonded to the lower substrate at a predetermined distance and having a counter electrode forming an electric field together with the pixel electrode; A liquid crystal layer interposed between the upper and lower substrates and including several liquid crystal molecules; A first alignment agent interposed between the liquid crystal layer and the lower substrate; And A second alignment agent interposed between the liquid crystal layer and the upper substrate; Any one of the first and second alignment agents is a horizontal alignment agent, and the other is a vertical alignment agent, Any one of the first alignment agent and the second alignment agent is formed of a photo alignment agent that is oriented by the application of light after bonding the lower substrate and the upper substrate, and the other is formed of polyimide to have different anchoring force Liquid crystal display element of HAN mode. The liquid crystal display device according to claim 1, wherein the first alignment agent is a vertical alignment agent and is formed of a general alignment agent, and the second alignment agent is a horizontal alignment agent and is formed of a photo alignment agent. The liquid crystal display of claim 1, wherein the first alignment agent is a horizontal alignment agent and is formed of a general alignment agent, and the second alignment agent is a vertical alignment agent and is formed of a photo alignment agent. The liquid crystal display of claim 1, wherein the first alignment agent is a vertical alignment agent and is formed of a photo alignment agent, and the second alignment agent is a horizontal alignment agent and is formed of a general alignment agent. The liquid crystal display device of HAN mode according to claim 1, wherein the first alignment agent is a horizontal alignment agent and a photo alignment agent, and the second alignment agent is a vertical alignment agent and a general alignment agent. The liquid crystal display device according to claim 1, wherein the dielectric anisotropy of the liquid crystal molecules in the liquid crystal layer is 2 to 15 or -15 to -2. The HAN mode liquid crystal display device according to claim 1, wherein the product of the refractive index anisotropy of the liquid crystal molecules and the distance between the upper and lower substrates is 0.3 to 1.6 mu m. Preparing a lower substrate on which a first alignment agent having a direction in a predetermined direction is formed on a surface on which the pixel electrode is formed; Preparing an upper substrate facing the lower substrate, the upper substrate having a second alignment agent provided with directivity by light without having any orientation on the surface on which the counter electrode is formed; Bonding the upper and lower substrates so that the first and second alignment agents face each other; And Irradiating light from the bottom of the lower substrate to impart orientation to the second alignment agent, Any one of the first alignment agent or the second alignment agent is a horizontal alignment agent, and the other is a vertical alignment agent manufacturing method of a HAN mode liquid crystal display device. 9. The method of claim 8, wherein the first alignment agent is a vertical alignment agent, and the second alignment agent is a horizontal alignment agent. The method of manufacturing an HAN mode liquid crystal display device according to claim 8, wherein the first alignment agent is a horizontal alignment agent, and the second alignment agent is a vertical alignment agent. Preparing a lower substrate on which a first alignment agent to be oriented by light is provided without any orientation on the surface on which the pixel electrode is formed; Preparing an upper substrate facing the lower substrate and having a second alignment agent having a direction in a predetermined direction on a surface on which the counter electrode is formed; Bonding the upper and lower substrates so that the first and second alignment agents face each other; And Irradiating light from the outside of the upper substrate to impart orientation to the first alignment agent, Any one of the first alignment agent or the second alignment agent is a horizontal alignment agent, and the other is a vertical alignment agent manufacturing method of a HAN mode liquid crystal display device. The method of claim 11, wherein the first alignment agent is a vertical alignment agent, and the second alignment agent is a horizontal alignment agent. 12. The method for manufacturing a HAN mode liquid crystal display device according to claim 11, wherein the first alignment agent is a horizontal alignment agent, and the second alignment agent is a vertical alignment agent.

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