KR20030001889A - Apparatus For Rubbing An Alignment layer Of Liquid Crystal Display Device - Google Patents

Abstract

PURPOSE: A device for rubbing an alignment film of a liquid crystal display device is provided to remove the generation of the ununiform orientation pattern and the rubbing scratches or vertical/horizontal stripes by attaching the rubbing clothing to a belt instead of attaching the rubbing clothing to a rubbing roll. CONSTITUTION: A device for rubbing an alignment film of a liquid crystal display device includes a stage(26) securing a substrate(20) and advancing in one direction, first and second rollers(21,22) mounted on the stage by a predetermined interval, a belt(24) mounted to the first and second roller to be driven, rubbing clothing attached to an outer surface of the belt, and a third roller(23) mounted between the belt to lift or lower between the belt for pressing the belt downwardly.

Description

Apparatus For Rubbing An Alignment layer Of Liquid Crystal Display Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment film rubbing device for a liquid crystal display device (LCD), and more particularly to an alignment film rubbing device for a liquid crystal display device to ensure uniformity of alignment film rubbing with respect to a large area substrate.

Recently, the liquid crystal display device, one of the flat panel display devices that are attracting attention, is an element that changes the optical anisotropy by applying an electric field to a liquid crystal that combines the liquidity and the optical properties of the crystal, which is applied to a conventional cathode ray tube. Compared with its low power consumption, small volume, large size, and high definition, it is widely used.

The liquid crystal display device includes a color filter substrate on which a color filter layer and a common electrode are formed, a thin film transistor substrate on which a thin film transistor and a pixel electrode are formed, and a liquid crystal layer formed between the two substrates. The liquid crystal molecules of should be oriented in a specific direction.

Therefore, in order to align the liquid crystal molecules in a specific direction, an organic polymer film called an alignment film must be artificially formed on the substrate and subjected to rubbing to impart anisotropy.

That is, polyamic acid, soluble polyimide, and the like are applied to the upper surface of the substrate, and then cured at a temperature of about 60 ° C. to about 80 ° C. and about 80 ° C. to about 200 ° C., and then polyimidized. Various alignment patterns are formed on the surface of the polyimide film.

Here, the rubbing process is performed by rotating a cylindrical rubbing roll wound with a rubbing cloth such as rayon or nylon and rubbing while applying physical friction to the surface of the polyimide film.

The rubbing method currently used is a technology that attaches a rubbing cloth to the rubbing roll and then rotates the rubbing roll to leave a uniform groove on the alignment layer.The rubbing roll rotates and moves without moving the rubbing stage on which the substrate is mounted for each type. And a rubbing head moving method for rubbing the alignment film, and a rubbing stage moving method for rubbing the alignment film by rotating the rubbing roll in place.

However, there is a high possibility of failure such as a vertical band or a horizontal band failure due to a gap between seams at the site to which the rubbing cloth is attached, and a failure of lifting the end of the cloth due to the cloth attachment state.

Hereinafter, an alignment film rubbing device of a liquid crystal display device according to the related art will be described with reference to the accompanying drawings.

1 is a perspective view for explaining a conventional alignment film rubbing process, Figures 2a and 2b is a perspective view and a cross-sectional view for explaining the problem of the conventional alignment film rubbing device. 3 is a flowchart illustrating a method of manufacturing a general liquid crystal display device.

3 is a perspective view for explaining an alignment film rubbing process according to a second embodiment of the prior art.

As shown in FIG. 1, a conventional alignment film rubbing device includes a cylindrical rubbing roll 14, a rubbing cloth 15 attached to an outer circumferential surface of the rubbing roll 14, and a central axis of the rubbing roll 14. It is composed of a support 13 connected to support the rubbing roll.

Here, the method of attaching the rubbing cloth to the rubbing roll consists of attaching a strong double-sided tape to the outer circumferential surface of the rubbing roll, attaching the rubbing cloth to the rubbing roll through the double-sided tape and aging for about 12 hours. .

However, all of these processes are made by hand, especially bare hands, due to the strong adhesive force of the double-sided tape, which causes the adhesive force at the edge portion of the rubbing cloth touched by the hand to fall, causing the rubbing cloth at the edge portion to be lifted as shown in FIG. 2A.

In addition, foaming may be caused by double-sided tape adhesiveness or rubbing cloth, and foaming may occur depending on the degree of adhesion. And, as shown in Figure 2b, when the rubbing cloth is attached, the seams of the rubbing cloth may not fit, may cause a step of the rubbing cloth.

As described above, when the rubbing cloth adhered is poor, vertical / horizontal bands, scratches, etc. are generated when the alignment layer is rubbed, and the alignment of the liquid crystal molecules becomes uneven, which causes unevenness on the screen when the liquid crystal is driven. This is a major reason for lowering the reliability of the display element, the display quality of which is the key.

On the other hand, the size of the rubbing roll and rubbing cloth should be longer than the diagonal length of the substrate to correspond to the rubbing angle, the size of the rubbing roll and rubbing cloth should also increase as the substrate becomes larger.

As the size of the rubbing device components increases, rubbing becomes uneven and the reliability of the device is lowered. In particular, since the rubbing cloth is attached to the outer circumferential surface of the rubbing roll using a double-sided tape, as the size of the rubbing cloth increases, the adhesion uniformity and the angle uniformity of the rubbing cloth are also disadvantageous.

A method of manufacturing a liquid crystal display device using the alignment layer rubbing device will now be described in detail with reference to FIG. 3.

First, the cleaning process (S100) is performed to remove foreign substances on the substrate on which the various patterns are formed, and after the alignment film printing process (S101) for printing the alignment film raw material liquid on the upper surface of the substrate using an alignment film printing apparatus, the alignment film raw material liquid The alignment film curing step (S102) of applying heat to the curing is performed.

Next, an alignment film rubbing step (S103) is carried out by rubbing the surface of the cured alignment film using a rubbing device to form a groove.

That is, as shown in FIG. 1, the substrate 10 on which the alignment layer 12 is formed is mounted on the upper surface of the stage 16, and the rubbing roll is up / down to maintain a constant gap between the substrate and the rubbing roll. . Next, the driving roller 17 is rotated by the power of the driving motor (not shown) to move the rubbing stage 16 at the rated speed to advance the substrate 10 in one direction, and at the same time, the rubbing roll connected to the support 13. 14 contacts the alignment film 12 of the substrate 10 advancing at the bottom thereof, and then leaves grooves in the surface of the alignment film 12 while rotating in place.

Usually, the rotating speed of a rubbing roll shall be about 1250-1500 rpm.

In order to have uniform display characteristics, it is important to uniformly form grooves in a large area, which is possible by aligning the polymer chains on the alignment layer surface in a predetermined direction by rubbing the alignment layer surface with a rubbing cloth at a uniform pressure and speed.

After the alignment film forming process is completed, a seal pattern serving as an adhesive on the edge of the upper substrate is formed in the remaining regions except for the liquid crystal inlet, and the spacers are scattered on the lower substrate.

Next, the two substrates are opposed to each other, and light is leaked out of a given margin so that a precision of about several micrometers (μm) is usually required.

In this case, the upper substrate of the substrate is a color filter substrate having a color filter layer and a common electrode formed thereon, and the lower substrate is a thin film transistor substrate having a thin film transistor and a pixel electrode formed in each pixel region defined by gate wiring and data wiring.

Then, the cell cutting process (S106) which cut | disconnects the opposingly bonded board | substrate into a unit cell is performed. The cell cutting process includes a scribing process for forming lines on the upper and lower substrate surfaces in order to cut two completely bonded substrates to a required size, and a break process for impacting the scribed lines to separate the substrates.

Finally, the liquid crystal display device is completed by injecting the liquid crystal between the two substrates cut into the unit cells and encapsulating the liquid crystal inlet such that the liquid crystal does not flow out (S107).

The alignment film rubbing device of the liquid crystal display device as described above has the following problems.

First, in the process of attaching the rubbing cloth, the rubbing cloth of the edge portion is lifted or the seam of the rubbing cloth is not matched, thereby causing a step of the rubbing cloth. As described above, when a defect occurs in the rubbing cloth adhered state, the alignment state due to rubbing may be locally uneven, and rubbing scratches or vertical / horizontal bands may occur. This causes a stain on the screen, which is a major reason for degrading the quality of the display element.

Second, as the substrate becomes larger, the size of the rubbing roll and the rubbing cloth becomes larger, and thus the rubbing becomes uneven because the adhesion uniformity of the rubbing cloth and the angular uniformity of the rubbing cloth trapping are disadvantageous.

Third, when the rubbing roll is rotated at a high speed, the uniformity of the alignment pattern due to the poor adhesion of the rubbing cloth becomes more severe due to the increased vibration of the rubbing roll.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an alignment film rubbing device for a liquid crystal display device to solve the rubbing defects generated when the rubbing cloth is attached by using a plurality of rollers.

1 is a perspective view for explaining an alignment film rubbing process of the prior art;

2A and 2B are a perspective view and a cross-sectional view for explaining the problem of the conventional alignment film rubbing device.

3 is a process flowchart for explaining a manufacturing method of a general liquid crystal display device.

4A and 4B are a perspective view and a cross-sectional view for explaining the alignment film rubbing device according to the present invention.

5A to 5D are cross-sectional views for explaining the alignment film rubbing process according to the present invention.

* Explanation of symbols on the main parts of the drawings

20: substrate 21, 22: first, second drive roller

23: auxiliary roller 24: belt

25: Loving Gun 26: Stage

In order to achieve the above object, an alignment film rubbing device of a liquid crystal display device according to the present invention includes a stage on which a substrate is mounted and advanced in one direction, a first roller and a second roller installed to be spaced apart from each other by a predetermined distance from the upper side of the stage, And a belt driven across the first roller and the second roller, a rubbing cloth attached to an outer circumferential surface of the belt, and a third roller provided to be able to move up and down between the belt.

Hereinafter, referring to the accompanying drawings, an alignment film rubbing device of a liquid crystal display according to the present invention will be described in detail.

4A and 4B are a perspective view and a cross-sectional view for explaining the alignment film rubbing apparatus according to the present invention, and FIGS. 5A to 5D are cross-sectional views for explaining the alignment film rubbing process according to the present invention.

4A and 4B, the alignment film rubbing device according to the present invention includes a substrate 20 to which the alignment film is applied, a stage 26 on which the substrate 20 is mounted, and advances in one direction at a rated speed, and the In order to advance the stage 26, a driving roller (not shown) provided on the lower surface of the stage, and the first driving roller 21 and the second driving roller installed at the same height above the stage 25 and spaced apart by a predetermined interval ( 22 and a drive motor (not shown) connected to the first drive roller 21 or the second drive roller 22 to provide power for rotating the first and second drive rollers 21 and 22. And a belt 24 driven between the first driving roller 21 and the second driving roller 22 in one direction, and a rayon and nylon-based rubbing cloth attached to the outer circumferential surface of the belt 24. ) Up and down between the belt and freely in place And a tension adjustment auxiliary roller 23 provided so as to before, is connected to the central axis of the auxiliary roller (23) consists of a support (not shown) which supports the auxiliary roller.

The alignment layer rubbing device allows the alignment layer on the upper surface of the substrate 20 to be rubbed by the rubbing cloth 25 attached to the belt 24 while pressing the belt 24 downward as the auxiliary roller 23 descends. Then, the belt 24 to which the rubbing cloth 25 is attached is moved in one direction by the first and second driving rollers 21 and 22. The substrate 20 is moved in one direction by the advancing stage 26 to form an alignment pattern on the surface of the alignment film.

Therefore, the defect which arises when sticking a rubbing cloth to a rubbing roll can be prevented.

Here, the first and second drive rollers 21 and 22 and the auxiliary roller 23 are installed in the coaxial direction, at least one of the first and second drive rollers 21 and 22 should be driven, and the roller The speed of rotation depends on the size of each roller, but is generally about 1250-1500rpm. The first and second driving rollers 21 and 22 are designed not only for forward rotation but also for reverse rotation, so that after the rubbing process is completed, the position of the rubbing cloth 25 can be returned to the position before the process.

When the rubbing cloth 25 is attached to the belt 24, the rubbing cloth 25 may be attached to the front surface of the belt 24 or attached to a predetermined portion of the belt 24 in a size corresponding to the substrate size.

The rubbing cloth 25 is designed to be slightly larger than the size of the substrate 20, and the rubbing cloth 25 may be directly rubbed with the first and second driving rollers 21 and 22 without attaching the rubbing cloth to the belt 24. .

In order to give a predetermined angle to the rubbing of the rubbing cloth formed on the alignment layer, the first and second driving rollers 21 and 22 and the auxiliary roller 23 on the upper side of the stage are rotated at an angle or the advancing direction of the substrate 20 is fixed. Just turn it at an angle.

Referring to FIGS. 5A to 5D, the manufacturing method of the liquid crystal display device using the alignment film rubbing device of the present invention will be described.

First, a black matrix is formed on the color filter substrate to prevent light leakage, and red, green, and blue colors are formed by using a dyeing method, an electrodeposition method, a pigment dispersion method, and a coating method between the black matrices. After forming the filter layer, the common electrode is formed by depositing ITO on the entire surface including the color filter layer.

Next, a plurality of gate wirings and data wirings are formed on the array substrate, and a thin film transistor including a gate electrode, a gate insulating film, a semiconductor layer, and a source / drain electrode is formed at an intersection of the two wirings. A pixel electrode of ITO material connected to the drain electrode is formed.

Subsequently, as an example of the alignment film undiluted solution on the color filter substrate or the array substrate on which the various patterns are formed, polyimide acid is dropped and applied evenly by a rotary coating method, and then cured at high temperature and dried to polyimide. Next, the substrate on which the polyimide-oriented alignment film is formed is loaded into the rubbing stage.

As shown in FIG. 5A, when the substrate 20 is mounted on the stage 26, the auxiliary roller 23 receiving the data of the substrate thickness from the previous process descends to an appropriate position, and as shown in FIG. 5B, the substrate 20. ) To maintain a constant gap.

Next, as shown in FIG. 5C, the stage 26 on which the substrate 20 is mounted is advanced at the rated speed, and the belt 24 with the rubbing cloth 25 is attached to the first driving roller 21 or the second. It is driven in one direction by the drive roller 22.

At this time, the auxiliary roller 23 is rotated in place by the driven belt 24 to press the belt downward, the rubbing cloth 25 rubs the surface of the polyimide film on the substrate 20 to form an orientation pattern do.

After the rubbing process is finished, as shown in FIG. 5D, the auxiliary roller 23 is raised to prepare for the next rubbing process, and the first driving roller 21 or the second driving roller 22 is rotated in the reverse direction to form the rubbing cloth ( 25) Rewind to the other side.

After the rubbing process is completed as described above, the color filter substrate and the array substrate are opposed to each other, and the liquid crystal is sealed in a space of several m therebetween to complete the liquid crystal display device.

For reference, as described above, the rubbing process may be performed while advancing the substrate and rotating the rubbing device in place, but the rubbing process may be performed while the rubbing device is rotated and moved forward while the substrate is fixed.

In the alignment film rubbing device according to the present invention, since the rubbing cloth is not attached to the rubbing roll, even if the rubbing roll is rotated at a high speed, there is no fear of unevenness of the alignment pattern due to the increase in vibration.

On the other hand, the method described above is a twisted nematic (TN) mode, a ferroelectric (FLC) mode, polysilicon (IPS) mode in addition to the in-plane switching (IPS) mode of inducing a parallel electric field by forming a common electrode and a pixel electrode on the substrate It can be used for poly-silicon mode and vertical alignment mode.

The alignment film rubbing device of the liquid crystal display device of the present invention as described above has the following effects.

First, the defect caused when the rubbing cloth is attached is eliminated by not attaching the rubbing cloth to the rubbing roll.

That is, by incorrectly attaching the rubbing cloth to the rubbing roll, the seam of the rubbing cloth is not matched or the rubbing cloth is lifted, resulting in vertical / horizontal bands or scratches on the surface of the alignment layer. Can be oriented and staining on the screen can be prevented.

Therefore, the display quality of the device is improved.

Second, since the rubbing cloth is not attached to the rubbing roll, the cause of the nonuniformity of the alignment pattern is eliminated due to the vibration increase due to the high speed rotation of the rubbing roll.

Claims (10)

A stage on which the substrate is mounted and advanced in one direction; First and second rollers disposed to be spaced apart from each other by a predetermined distance from an upper side of the stage; A belt driven between the first roller and the second roller; A rubbing cloth attached to an outer circumferential surface of the belt; And a third roller provided so as to be able to move up and down between the belts. 2. The apparatus of claim 1, wherein the third roller presses the belt downward. 2. The apparatus of claim 1, wherein the first, second, and third rollers are provided coaxially. 2. The apparatus of claim 1, wherein the first and second rollers are provided at the same height. 2. The alignment film rubbing device according to claim 1, wherein an alignment film is formed on the substrate. 2. The apparatus of claim 1, wherein at least one of the first and second rollers is driven. The apparatus of claim 1, wherein the first and second rollers are capable of forward rotation and reverse rotation. The rubbing device of claim 1, wherein the rubbing cloth is attached to the entire area of the belt or attached to a portion of the belt. 2. The apparatus of claim 1, wherein the rubbing cloth is larger in size than the area of the substrate. 2. The apparatus of claim 1, wherein the third roller has a central axis thereof connected to a support.