KR100691317B1 - liquid crystal injection device and liquid crystal injection method - Google Patents

Abstract

end. FIELD OF THE INVENTION The invention described in the claims belongs to: A liquid crystal display device having a columnar spacer of "V" shape which functions to keep the cell gap uniform.

I. The technical problem to be solved by the present invention: Since the conventional columnar spacer has a square shape, the light leakage due to poor rubbing occurs around the spacer in the liquid crystal display, the contrast is reduced, and a relatively high stepped spacer is applied. Due to the printing failure of the alignment film around the spacer due to light leakage defects may occur due to the upper and lower plates twisted, and also because the spacer inhibits the flow of the liquid crystal when the liquid crystal is injected to solve the problem that the injection speed of the liquid crystal is long.

All. Summary of the Invention Solution of the Invention: In the present invention, the columnar spacer is designed to have a "V" shape to have an inclination angle with respect to the rubbing direction, and to have a pointed portion of the spacer with respect to the liquid crystal injection direction, thereby deteriorating rubbing. Solve the problem and improve the liquid crystal injection speed.

Description

Liquid crystal injection device and liquid crystal injection method             

1 is a flowchart illustrating a manufacturing process of a general liquid crystal cell.

2 is a view showing a pressure-sensitive liquid crystal injection method commonly used.

Figure 3 is a graph showing the relationship between the time and pressure when the pressure-sensitive liquid crystal injection.

4 is a cross-sectional view of a general liquid crystal display device.

5 is a plan view of a liquid crystal display device employing a conventional columnar spacer.

FIG. 6 is a schematic plan view of a liquid crystal display using a "V" columnar spacer according to the present invention; FIG.

7 is a view showing a method of injecting liquid crystal into a liquid crystal display using a "V" shaped columnar spacer according to the present invention.

<Description of Symbols for Main Parts of Drawings>

 150: "V" shaped spacer 100: active matrix substrate

 200: counter substrate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing process of a liquid crystal display device, and more particularly, to a device for injecting liquid crystal into a panel and a liquid crystal injection method by the device.

In general, a liquid crystal display includes a lower plate that is a substrate on which thin film transistors are arranged, and an upper plate on which a color filter is printed, and a liquid crystal is positioned between the upper plate and the lower plate.

A brief manufacturing process of the liquid crystal cell and its operation in the liquid crystal display are as follows.

Two substrates, namely, a common electrode is formed on one side of each inner side facing the upper plate and the lower plate, and a pixel electrode is formed on the other side, and the electrodes are arranged to face each other, and then between the upper plate and the lower plate. The liquid crystal is injected at the interval of and the inlet is sealed. The liquid crystal cell is completed by attaching polarizing plates to the outer side of the upper plate and the lower plate, respectively.

In addition, the light transmittance of the liquid crystal cell is controlled by a voltage applied to each electrode (pixel electrode, common electrode), and the characters / images are displayed by the optical shutter effect.

The liquid crystal cell process may be characterized in that the process is relatively few compared to the thin film transistor (TFT) process or the color filter process. The overall process may be roughly divided into an alignment layer forming process for forming liquid crystal molecules, a cell gap forming process, a cell cutting process, and the like.

Hereinafter, the manufacturing process of the liquid crystal display device described above will be described with reference to the accompanying drawings.

FIG. 1 is a flowchart illustrating a manufacturing process of a liquid crystal cell that is generally applied. In the st1 step, a lower plate is first prepared. A plurality of thin film transistors (TFTs) are arranged in the lower plate as switching elements, and pixel electrodes are formed in one-to-one correspondence with the TFTs.

The st2 step is to form an alignment layer on the lower plate.

The alignment layer formation includes deposition and rubbing of a polymer thin film. The polymer thin film is commonly referred to as an alignment layer, and should be deposited with a uniform thickness over the entire lower plate, and rubbing should also be uniform.

The rubbing is a main process of determining the initial alignment direction of the liquid crystal. The rubbing of the alignment layer enables normal driving of the liquid crystal and has uniform display characteristics.

In general, an organic layer of organic alignment is mainly used for the alignment layer.

The rubbing process refers to rubbing the alignment layer in a predetermined direction using a cloth, and the liquid crystal molecules are aligned according to the rubbing direction.

The st3 step represents a process of printing a seal pattern.

The seal pattern in the liquid crystal cell forms a gap for injecting the liquid crystal, and serves to prevent leakage of the injected liquid crystal.                         

The seal pattern is a step of forming a thermosetting resin in a desired pattern constantly, and screen printing has become mainstream.

The st4 step represents a process of dispersing a spacer.

In the manufacturing process of the liquid crystal cell, a spacer of a constant size is used to keep the gap between the upper and lower plates precise and uniform. Therefore, the spacer should be dispersed at a uniform density with respect to the lower plate, and the dispersion method can be largely divided into a wet dispersion method in which the spacer is mixed with an alcohol and sprayed and a dry dispersion method in which only the spacer is dispersed.

In addition, the dry dispersion is divided into an electrostatic spraying method using static electricity and an antistatic spraying method using gas pressure. The electrostatic scattering method is widely used in a liquid crystal cell having a structure susceptible to static electricity.

After the spacer spreading process is completed, the process of bonding the upper plate as the color filter substrate and the lower plate as the thin film transistor array substrate is performed (st5).

The joint arrangement of the top plate and the bottom plate is determined by the margin given in the design of each substrate, and usually a precision of several μm is required. If the two substrates are out of the bonding error range, light leaks out, and thus the desired image quality characteristics cannot be expected when the liquid crystal cell is driven.

The st6 step is a step of cutting the liquid crystal cell prepared in the st1 to st5 step into a unit cell.

In general, the liquid crystal cell is subjected to a process of forming a plurality of liquid crystal cells on a large glass substrate, and then separating them into one liquid crystal cell, which is a cell cutting process.

In the initial manufacturing process of the liquid crystal display device, a liquid crystal is injected into several cells at the same time, and then a cell unit is cut. However, as the cell size increases, the liquid crystal is injected after cutting into unit cells.

The cell cutting process is made of a diamond pen having a hardness higher than that of a glass substrate, and a scribe process for forming a cutting line on the surface of the substrate and a break process for applying force.

The st7 step is a step of injecting liquid crystal into the liquid crystal cell cut into each unit cell.

The unit liquid crystal cell has a gap of several μm in an area of several hundred cm 2. Therefore, the vacuum injection method using the pressure difference between the inside and outside of the cell is most widely used as a method of effectively injecting liquid crystal into a cell having such a structure.

Since the liquid crystal injection method using the pressure difference as described above requires the longest time in the liquid crystal cell process, it is important to set the optimum conditions in terms of productivity.

2 is a diagram illustrating a process of injecting liquid crystal into a cell in general.

In general, in order to inject liquid crystal into the cell 2, a vacuum device 6 in which the cell 2 can be mounted and a container 8 containing the liquid crystal 10 are required.

First, the air existing in the cell 2 is removed from the vacuum device 6.

At this time, fine air bubbles in the liquid crystal 10 are injected into the cell 2 and, as time passes, defects may occur when these are combined to form bubbles. Therefore, a degassing process is required to remove bubbles existing in the liquid crystal 10 by leaving it in vacuum for a long time in order to remove fine air bubbles present in the liquid crystal.

The defoaming process as described above may be solved by simultaneously loading the liquid crystals in the process of extracting the vacuum of the cell 2.

In order to inject the liquid crystal, a vacuum degree of several mTorr is usually required.

In addition, when the pressure is rapidly changed in order to reduce the process time, the liquid crystal may be deformed and the cell 2 may be deformed and damaged. Therefore, verification of the process conditions is required.

Liquid crystal injection is generally a dipping method of dipping a unit cell in a liquid crystal tray. However, since a large amount of liquid crystal is consumed, a touch method of contacting only the injection hole 4 to the liquid crystal 10 has been introduced. Hereinafter, a touch method will be described.

When the air existing in the cells 2 to the liquid crystal 10 is sufficiently removed by the vacuum device 6, the liquid crystal inlet 4 of the cell 2 is filled in the container 8 containing the liquid crystal 10. Soak in.

At this time, since there is no pressure difference between the liquid crystal 10 and the cell 2, the liquid crystal 10 is injected into the cell 2 by capillary action at the beginning of liquid crystal injection, and then the vacuum apparatus 6 Injecting nitrogen into the inside of the cell 2 causes the liquid crystal 10 to be sucked into the cell 2 due to the pressure difference between the inside of the cell 2 and the inside of the vacuum device 6.

3 is a graph showing the degree of vacuum with respect to the time of the vacuum apparatus 6, in which the region A is the time to extract the vacuum from the vacuum apparatus 6, and the region B is the time at which the liquid crystal is injected.

The cell 2 in which the liquid crystal injection is completed needs a process of preventing the liquid crystal injected into the liquid crystal injection hole 4 from flowing out. In general, after applying the ultraviolet curable resin using a dispenser (dispensor), the liquid crystal injection hole 4 is sealed by irradiating ultraviolet rays.

As described above, in the conventional liquid crystal display, spacers are used to uniformly maintain a gap (cell gap) between a pair of substrates. Such spacers are typically beads or fibers with a fine particle diameter and are sprinkled on one substrate in the manufacture of the liquid crystal device. For example, a method of manufacturing a liquid crystal display comprising distributing beads as spacers is quite simple, and beads or fibers have been used as spacers for most conventional liquid crystal displays.

4 shows an example of such conventional liquid crystal displays. The liquid crystal display includes a substrate 19 (hereinafter referred to as an active matrix substrate) on which thin film transistors (TFTs) 20 and pixel electrodes 21 are formed, and a substrate 18 on which opposing electrodes 22 are formed ( Hereinafter referred to as an opposing substrate, wherein the substrates are disposed opposing. The liquid crystal layer 26 is disposed between the counter electrode 18 and the active matrix substrate 19. On the surfaces of the active matrix substrate 19 and the opposing substrate 18, liquid crystal alignment films 23 and 24 are formed facing the liquid crystal layer 26, respectively. Spacers 25 are provided between the opposing substrate 18 and the active matrix substrate 19 to keep the cell gap uniform.

A liquid crystal device using spacers other than the beads or fibers is proposed, for example, in Japanese Patent No. 6-67135.

The technique disclosed in this publication involves transcribing pre-patterned column spacers. More specifically, the technique forms the alignment films on the surfaces of the active matrix substrate and the opposing substrate; Rubbing treatment on the alignment films; Forming columnar spacers made of black resin at predetermined positions of the substrate, neither the active matrix nor the opposing substrate; Transfer these spacers to non-pixel portions of the opposing substrate (eg, portions above the gate line and the data line); An opposite substrate to which the active matrix substrate and the spacers are transferred are disposed opposite; Filling the gap between the substrates with a liquid crystal material to form a liquid crystal layer.

However, these conventional techniques have the following problem.

The method involving scattering beads or fibers as spacers is simple, but the density of scattered spacers tends to vary with location. This makes it difficult to keep the cell gap uniform and causes display defects due to aggregation of the spacers.

In addition, in a method involving transferring patterned columnar spacers, it is difficult to form the spacers precisely at a predetermined position because of insufficient degree of alignment and shrinkage of the substrate.                         

In recent years, very fine technology has been required for liquid crystal devices such that the size of each pixel is 100 μm × 100 μm or less. As a result, light scattering from spacers having a diameter of about 5 μm or liquid crystal molecules adjacent to the spacers has been a problem to be solved. A method has been proposed that includes coloring spacers to reduce light scattering from the spacers. However, this method has problems such as deterioration of the reliability and display characteristics of the liquid crystal device due to the elution of impurities from the spacers to the liquid crystal layer, and thus has not been put to practical use at present.

Meanwhile, a method of transferring the patterned columnar spacers to maintain a cell gap has been developed, and a method of forming a spacer on the alignment layer of the opposing substrate 18 or the active matrix substrate 19 by photo-development has been proposed.

However, as shown in FIG. 5 showing the columnar spacer formation structure according to the photographic shape, the columnar spacer 25 'is formed in a substantially rectangular shape, and thus the columnar spacer 25' is formed. When rubbing the opposing substrate 18 or the active matrix substrate 19, rubbing defects occur at the edges of the spacer 25 ', and the liquid crystal molecules do not operate properly at the rubbing portions. Display defects occur, and even in the case of injecting the liquid crystal, the injection speed of the liquid crystal and the one surface of the spacer 25 ′ are vertically disposed, thereby causing a problem of significantly lowering the injection speed.

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a liquid crystal display device having a structure of a spacer in which a rubbing defect is solved and a liquid crystal injection speed is improved in a liquid crystal display device having a columnar spacer. It is done.

In order to achieve the above object, in the present invention, the first substrate and the second substrate having a liquid crystal injection hole, bonded to each other with a gap; A plurality of “V” shaped spacers arranged in a pattern on any one of the first substrate and the second substrate to maintain a gap between the first substrate and the second substrate; A liquid crystal positioned between the first substrate and the second substrate; A first alignment layer and a second alignment layer each having an alignment direction between each of the first substrate and the second substrate and the liquid crystal are provided.

Preferably, the spacer is positioned at the blocking portion of the first substrate and the second substrate.

Preferably, the spacer is characterized in that the acrylate (acrylates) material.

In addition, the present invention includes the steps of: forming an alignment film, each having a first substrate and a second substrate on which a liquid crystal injection hole is defined; In order to maintain a distance between the first substrate and the second substrate, a dielectric material is deposited on the alignment layer on any one of the first substrate and the second substrate, and a plurality of the dielectric materials are directed toward the vertex in the direction of the liquid crystal injection hole. Patterning two “V” shaped spacers; Rubbing the alignment layer; Bonding the first substrate and the second substrate to each other; And injecting liquid crystal between the first substrate and the second substrate through the liquid crystal injection hole.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

FIG. 6 illustrates the shape of a column spacer 150 for maintaining a cell gap of a liquid crystal display according to the present invention.

On the other hand, the columnar spacer 150 having a "V" shape according to the present invention can be formed on both the active matrix substrate 100 or the opposing substrate 200.

In addition, a liquid crystal display including amorphous silicon thin film transistors (a-Si: H) is used to implement the present invention. The present invention can also be implemented by a simple liquid crystal display device and an active matrix liquid crystal device using high temperature or low temperature polysilicon.

In addition, the present invention is not only twisted nematic (TN) mode, but also all display modes (eg, inplane switching (IPS), polymer dispersed type (PD), ferroelectricliquid) crystal type (FLC)).

As shown in FIG. 6, the columnar spacer 150 is formed to be inclined at a predetermined angle with respect to the rubbing direction. This is a structure capable of minimizing rubbing defects that may occur in a conventional spacer having a square shape.

That is, since the columnar spacer 150 according to the present invention basically takes the shape of "V", the rubbing defect can be reduced by minimizing the area of the spacer, and the load that can be tolerated per unit area is similar to the conventional one. do.

In addition, since the “V” shaped spacer 150 according to the present invention is disposed convexly in the liquid crystal injection direction, the liquid crystal injection time can be shortened because the liquid crystal injection does not interfere with the flow of liquid crystal injection. That is, as shown in FIG. 7, when the liquid crystal is injected, the horizontal component of the spacer which hinders the flow in the flow direction of the liquid crystal is insignificant, so that the injection speed of the liquid crystal is increased as compared with the conventional square spacer. .

Meanwhile, the columnar spacer 150 having a “V” shape according to the present invention can be formed on both the active matrix substrate 100 and the opposing substrate 200, and the screen matrix region, that is, the black matrix region excluded from the opening portion. It is formed in, for example, acrylates (acrylates), cyclized isoprene rubber, phenol resins, novolak resins, and the like are used, preferably acrylates.

In addition, the number of the columnar spacers 150 according to the present invention may be controlled by appropriately designing the pattern of the photomask, and one to many may be formed per pixel.

Here, the "V" shaped columnar spacer according to the present invention is obtained by forming an alignment layer in a process of a general liquid crystal display device, and then applying and patterning the acrylate on the alignment layer, and forming the alignment layer after formation of the spacer. The rubbing process is performed.                     

Referring to the operation of the columnar spacer having a "V" shape according to the present invention described above are as follows.

The liquid crystal display according to the present invention includes a liquid crystal layer disposed between a pair of substrates and "V" shaped columnar spacers for controlling a gap between the pair of substrates. The columnar spacer is disposed at an interface side between at least one of the pair of substrates. Since the spacers of the liquid crystal display according to the present invention are columnar, the upper and lower surfaces of the spacers contact the substrates.

That is, the area where the spacers contact the substrates is large compared to the contact area of conventional spherical spacers in contact with the substrates in points. Thus, the columnar spacers not only control the cell gap stably and accurately, but also reduce stress concentration on the contact portions between the substrates and the spacers. Therefore, according to the present invention, a liquid crystal display device excellent in pressure resistance and impact resistance can be obtained.

According to the present invention, since the columnar spacers holding the gaps of both substrates are "V" shaped and have a convex arrangement in the diagonal direction and the liquid crystal injection direction, each having a predetermined angle in the rubbing direction and the liquid crystal injection direction, respectively. Since rubbing defects on the outer periphery of the spacer can be reduced and the arrangement of the " V " shaped spacer is convex in the flow direction of the liquid crystal, the injection speed of the liquid crystal can be improved.

As described above, the liquid crystal display having the "V" columnar spacer according to the present invention has the following features.

First, the columnar spacer according to the present invention has the advantage of being able to withstand the same load while occupying a smaller area than the conventional square spacer.

 Second, since the cross-sectional area of the spacer of the present invention is relatively small compared to the existing columnar spacers, the area due to poor rubbing around the spacer is reduced, thereby reducing the possibility of light leakage defects due to poor bonding.

Third, since the arrangement of the "V" shaped spacer according to the present invention is disposed diagonally at a predetermined angle with respect to the rubbing direction, there is an advantage of minimizing rubbing defects that may occur in the outer periphery of the spacer.

Fourth, since the "V" shaped spacer according to the present invention is arranged convex with respect to the injection direction of the liquid crystal, the injection speed of the liquid crystal is reduced because the disturbance of the liquid crystal flow is minimized during the liquid crystal injection.

Claims (8)

A first substrate and a second substrate having a liquid crystal injection hole and bonded to each other with a gap therebetween; A plurality of “V” shaped spacers arranged in a pattern on any one of the first substrate and the second substrate to maintain a gap between the first substrate and the second substrate; A liquid crystal positioned between the first substrate and the second substrate; A first alignment layer and a second alignment layer having respective alignment directions between each of the first substrate and the second substrate and the liquid crystal; Liquid crystal display comprising a. The method according to claim 1, The spacer is a liquid crystal display device positioned in the blocking portion of the first substrate and the second substrate. The method according to claim 1, The spacer is a liquid crystal display of acrylates. The method according to claim 1, And a “V” shaped vertex of the spacer facing the liquid crystal injection hole. The method according to claim 1, The “V” shaped spacer is inclined with respect to the alignment direction of the first alignment layer and the second alignment layer. Forming an alignment layer and having a first substrate and a second substrate on which a liquid crystal injection hole is defined; In order to maintain a distance between the first substrate and the second substrate, a dielectric material is deposited on the alignment layer on any one of the first substrate and the second substrate, and a plurality of the dielectric materials are directed toward the vertex in the direction of the liquid crystal injection hole. Patterning two “V” shaped spacers; Rubbing the alignment layer; Bonding the first substrate and the second substrate to each other; Injecting a liquid crystal between the first substrate and the second substrate through the liquid crystal injection hole; Liquid crystal display manufacturing method comprising a. The method according to claim 6, The spacer is a liquid crystal display manufacturing method of the acrylate material. The method according to claim 6, The first substrate and the second substrate have openings and blocking portions at positions corresponding to each other, and the spacers are positioned at the blocking portions.

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