KR20080039116A - Method for aging rubbing clothes and method for rubbing alignmemet layer using aged rubbing clothes by thereof - Google Patents

Abstract

A method for aging a rubbing cloth, and a method for rubbing an alignment layer using the aged rubbing cloth are provided to lower luminance at black of a liquid crystal device and increase a contrast ratio. A rubbing cloth(212) is prepared. The rubbing cloth is wrapped on a rubbing roller(213). The rubbing roller wrapped with the rubbing cloth is disposed on a dummy substrate(210), in which an x axis is a longer side direction and y axis is a shorter side direction, such that it makes a certain angle with respect to the x axis of the dummy substrate. The rubbing roller is rotated in the x axis direction to perform aging thereon. A substrate with an alignment layer formed thereon is rubbed with the aged rubbing cloth.

Description

METHOD FOR AGING RUBBING CLOTHES AND METHOD FOR RUBBING ALIGNMEMET LAYER USING AGED RUBBING CLOTHES BY THEREOF}

1 is a cross-sectional view schematically showing a cross section of a liquid crystal display device according to the prior art.

Figure 2 is a flow chart schematically showing a manufacturing process of the liquid crystal display device according to the prior art.

Figure 3 is a perspective view schematically showing how rubbing proceeds.

4 shows the direction of coin testing and settling.

5 is a perspective view showing the aging of the rubbing cloth according to the present invention.

6 is a graph of the contrast ratio according to the aging direction when aging with different aging directions.

<Explanation of symbols for the main parts of the drawings>

110: substrate

111: alignment film

112, 212: Loving gun

113, 213: Loving Roller

210: dummy substrate

The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly, to a method of aging before rubbing an alignment layer of a substrate.

Recently, with the development of various portable electronic devices such as mobile phones, PDAs, and notebook computers, there is an increasing demand for flat panel display devices for light and thin applications. Such flat panel displays are being actively researched, such as LCD (Liquid Crystal Display), PDP (Plasma Display Panel), FED (Field Emission Display), VFD (Vacuum Fluorescent Display), but mass production technology, ease of driving means, Liquid crystal display devices (LCDs) are in the spotlight for reasons of implementation.

1 is a cross-sectional view schematically showing a cross section of a liquid crystal display device according to the prior art. As shown in the figure, the liquid crystal display device 1 includes a liquid crystal layer 7 formed between the first substrate 5 and the second substrate 3 and between the first substrate 5 and the second substrate 3. It consists of.

The first substrate 5 is a substrate on which a thin film transistor (TFT), which is a driving element, is formed. Although not shown in the drawing, a plurality of pixels are formed, and each pixel is formed of a thin film transistor.

The upper substrate 3 is a color filter substrate, and a color filter layer for realizing color is formed. In addition, a pixel electrode and a common electrode are formed on the first substrate 5 and the second substrate 3, respectively, and an alignment film for aligning liquid crystal molecules of the liquid crystal layer 7 is coated.

The first substrate 5 and the second substrate 3 are bonded by a sealing material 9, and a liquid crystal layer 7 is formed therebetween to drive the first substrate 5. The device displays the information by controlling the amount of light passing through the liquid crystal layer by driving the liquid crystal molecules.

The manufacturing process of the liquid crystal display device is largely a driving element thin film transistor substrate process for forming a driving element on the first substrate 5 and a color filter substrate process and a cell process for forming a color filter on the second substrate 3. The manufacturing process of the liquid crystal display device according to the prior art will be described with reference to FIG. 2 as follows.

First, a plurality of gate lines and data lines are formed on the first substrate 5 by a driving element thin film transistor process to define pixel regions, and the gate lines are formed in each of the pixel regions. And a thin film transistor which is a driving element connected to the data line (S101). In addition, the driving device is connected to the thin film transistor through the thin film transistor process to form a pixel electrode for driving the liquid crystal layer as a signal is applied through the thin film transistor.

In addition, the second substrate 3 is formed with a color filter layer and a common electrode of R, G, B to implement color by a color filter process (S104). Subsequently, an alignment film is applied to the second substrate 3 and the first substrate 5, respectively, and then alignment control force or surface is applied to the liquid crystal molecules of the liquid crystal layer formed between the second substrate 3 and the first substrate 5. In order to provide a fixing force (ie, a pretilt angel and an orientation direction), the alignment layer is rubbed (S102 and S105). Subsequently, the first substrate 5 is spread with a spacer for keeping the cell gap constant and a sealing material is applied to the outer portion of the second substrate 3, and then the first substrate 5 is applied. And the second substrate 3 by applying pressure (S103, S106, S107). On the other hand, the first substrate 5 and the second substrate 3 is made of a large area of the substrate. In other words, a plurality of panel regions are formed on a large-area substrate, and a TFT and a color filter layer, which are driving elements, are formed in each of the panel regions, so that the substrate must be cut and processed to produce a single liquid crystal panel. (S108). Thereafter, a liquid crystal layer is formed on each of the liquid crystal panels processed as described above, and the liquid crystal panel is encapsulated, thereby inspecting each liquid crystal panel to produce a liquid crystal display device (S109 and S110).

As described above, the manufacturing process of the liquid crystal display device undergoes a process of forming and rubbing an alignment layer. The formation of the alignment layer refers to a process of forming a thin film by applying a uniform thickness to a substrate using a polymer, and generally polyimide-based organic molecules are mainly used. After the formation of the alignment layer, a cloth (rubbing cloth) is wound on the rubbing rollers and a process of rubbing the alignment layer in a certain direction is called rubbing, which is called a rubbing, and the liquid crystal molecules are aligned in a predetermined direction according to the rubbing direction. .

After rubbing, the alignment of liquid crystal molecules in a predetermined direction changes the orientation according to the applied voltage, and the degree of transmission of light varies according to the degree of alignment, thereby displaying an image.

However, when a new rubbing cloth is rolled on a rubbing roller and used immediately for rubbing of the alignment film, the rubbing cloth is often not uniformly formed, and thus the rubbed alignment film also has poor uniformity. Therefore, before the new rubbing cloth is used, it is wound on the rubbing rollers and subjected to an alignment step of performing rubbing on the test substrate (dummy substrate) several times before entering the process. This is called aging, and typically tens to hundreds of rubbings are tested.

The problem is that the black and white contrast ratio (hereinafter, contrast ratio) of the liquid crystal panel after rubbing varies greatly depending on the aging direction, and the quality of the liquid crystal panel when the contrast ratio varies depending on the aging direction of the rubbing cloth. This non-uniform, liquid crystal panel may deviate from the quality standard.

In order to solve the above problems, the present invention provides a method of aging before rubbing the alignment layer of the substrate. In particular, the rubbing cloth has a special direction so that the contrast ratio is increased, but the luminance when black is reduced. The purpose is to provide a liquid crystal panel with good display quality.

The rubbing cloth aging method of the present invention for solving the above object comprises the steps of preparing a rubbing roller winding the rubbing cloth, the x-axis of the dummy substrate of the x-axis, the short-axis direction is the y-axis direction of the rubbing roller Arranging to achieve a predetermined angle, and rotating the rubbing roller in parallel with the x-axis direction to perform aging.

At this time, the inclination angle of the rubbing roller is characterized in that the angle is greater than 5 ° and less than 40 ° and the direction of the inclination includes an aging method for rubbing so that the trapping of the rubbing cloth is formed in the right direction.

In addition, the rubbing cloth having a grain formed on the right side is used for both the alignment layer of the thin film transistor substrate and the alignment layer of the color filter substrate to perform rubbing.

The method of rubbing an alignment layer of a liquid crystal display device, including the step of aging the rubbing cloth, includes preparing a rubbing cloth, winding the rubbing cloth on a rubbing roller, and applying the wrapped rubbing cloth to the method of claim 1. Aging and rubbing the substrate with the aged rubbing cloth.

Hereinafter, the present invention will be described with reference to the drawings.

3 is a perspective view schematically showing how rubbing proceeds according to an embodiment of the present invention. The rubbing cloth 112 is generally wound and attached to a rubbing roller (rubbing roller; 113), the process of forming a rubbing cloth on the rubbing roller 113 is called a winding cloth.

The rubbing is performed while rotating the rubbing roller 113 on which the rubbing cloth 112 is wound on the substrate 110 to which the alignment layer 111 is applied. At this time, rubbing proceeds while the substrate 110 moves in one direction 115.

By the way, if the rubbing cloth itself is not a uniform texture of the fabric (hereinafter, sacking) it is very important that the rubbing cloth is uniformly trapped because the substrate to be rubbed later will be a non-uniform substrate. If the rubbing cloth is not uniform, the liquid crystal may not be aligned in a certain direction, resulting in light leakage, which may result in a defect in which the luminance in the black state is increased. In addition, the high luminance in the black state causes the contrast ratio between white and black to become small, resulting in a problem of deterioration in image quality.

Therefore, the new rubbing cloth is wound on the rubbing roller and then subjected to the aging process of the rubbing cloth using a dummy substrate before being applied to the mass production process, thereby uniformly forming the rubbing on the rubbing cloth. Aging refers to aligning the grains of the fabric by repeating rubbing a dozen rollers several tens to hundreds of times on the dummy roller, and proceeding to make the rubbing of the rubbing cloth uniform.

In the present invention, the aging process is characterized by aging in a specific direction. In the method for aging a rubbing cloth according to the present invention, the rubbing of the rubbing cloth is formed by aging in a specific direction. That is, it is characterized in that the long axis direction of the rubbing roller and the lying down direction of the trapping is formed to be a constant angle. In this way, the rubbing roller in which the rubbing cloth formed in the predetermined direction is wound is placed on the substrate at a predetermined angle to perform rubbing.

The aging method of the present invention is characterized in that trapping is formed in the right direction. Meaning that the trappings are formed in the right direction can be confirmed through a coin test (coin test), Figure 4 shows a method of finding out the trapping of the rubbing gun by testing with a coin according to an embodiment of the present invention. As shown in the figure, when there is a long side (H) and a short side (h) of the rubbing cloth, one side with the coin is placed high with the coin (C) raised vertically to the long side (H). At this time, the coin (C) is moved by the law of gravity, the direction of the coin is determined according to the direction of the rubbing gun rubbing. Here, it is said that trapping is formed in the right (R, right) direction when moved to the right based on the short axis direction, and trapped is formed in the left (L, left) direction when it is moved to the left.

The present invention includes aging so that all the rubbing cloths wound on the rubbing roller are formed in the R direction.

Figure 5 shows the aging of the rubbing roller winding the rubbing cloth in the dummy substrate according to an embodiment of the present invention. In order to ensure that the trapping of the rubbing cloth is formed in a specific direction, the rubbing roller is disposed at an angle with respect to the x-axis of the dummy substrate having the x-axis of the long side and the y-axis of the short side. The rubbing roller is rotated in the x-axis direction to advance while rotating the substrate as if rubbing. This process proceeds aging.

In particular, as described above, the rubbing roller is arranged to have a predetermined angle with the x-axis, but the direction of the rubbing roller is characterized in that it proceeds while rotating in parallel in the x-axis direction. The rubbing roller is fixed in position by an axis that fixes the rubbing roller at both ends. The aging process is performed by rotating the rubbing roller while moving the rubbing roller shaft in the x-axis direction of the substrate. Since the rubbing roller is aged in a state inclined at a predetermined angle in parallel to the x-axis direction, the rubbing cloth wound on the rubbing roller receives a force in an oblique direction. Therefore, the trapping of the rubbing cloth is aged at a predetermined angle.

In order to ensure that the trapping of the rubbing cloth is formed in a specific direction, it is preferable to arrange the rubbing roller 213 on which the rubbing cloth 212 is wound at an angle to the dummy substrate 210 at the time of aging. That is, when the long axis and the short axis of the substrate are referred to as the x-axis and the y-axis, they are arranged to have a positive or negative slope on the xy plane. At this time, by adjusting the angle when arranging the rubbing roller 213 as described above, it is possible to adjust the inclination of arranging the rubbing roller so that the angle of the trapping of the rubbing cloth 212 comes out in the R direction, the value of the rubbing roller The aging process proceeds by taking the appropriate value to get this R direction. The aging process is performed by rotating the rubbing roller 213 on the dummy substrate 210 over a plurality of times.

At this time, the substrate used in the liquid crystal display according to the present invention is two opposing substrates such as a substrate on which a thin film transistor is formed and a substrate on which a color filter is formed, and both substrates are characterized in that trapping is formed in the R direction.

The following table shows white luminance, black luminance, and contrast ratio CR when rubbing the alignment layer after the rubbing cloth was formed to have a trapping in a specific direction (R or L). At this time, the unit of brightness is nit, and the angle of the rubbing cloth in the direction of R or L was set to have a value of 5 degrees or more and 40 degrees or less, respectively. The rubbing cloth was divided into a color filter substrate (CF rubbing cloth) and a thin film transistor substrate (TFT rubbing cloth) to represent respective data values.

<Table>

As shown in the above table, it can be seen that the luminance and contrast ratio of the liquid crystal display device remain different after rubbing the alignment layer depending on whether the rubbing of the rubbing cloth through aging is R or L. Contrast ratio when rubbing the alignment film of the color filter substrate and the thin film transistor substrate in order with rubbing cloths having trapping in L, L (hereinafter referred to as L / L method), L / R, R / L, and R / R directions Have values of 494, 693, 529, and 770, respectively, and their values are shown graphically in FIG. Coin shift in Figure 6 represents the direction of the coin, CR is the contrast ratio L / L, L / R, R / L, R / R is the color filter substrate and the thin film transistor substrate, respectively, in the L and R direction A rubbing with a rubbing cloth is shown.

The lower the luminance in black and the higher the contrast ratio, the higher the image quality. Among the aged rubbing cloths, L / R and R / R have higher contrast ratios than L / L, but higher values than R / L. Among them, it can be seen that the contrast ratio has a remarkably high value in the liquid crystal display device rubbed with a rubbing cloth aged with R / R.

Here, in particular, when the trapping of the rubbing cloth rubbing the thin film transistor substrate is in the R direction, the impact on the contrast ratio is greater than when the trapping of the rubbing cloth rubbing the color filter substrate is in the R direction. That is, the value of the contrast ratio is greatly influenced by the trapping direction of the rubbing cloth used in the thin film transistor, and when the direction of the trapping is R, the contrast ratio is large. Therefore, the rubbing cloth rubbing the thin film transistor substrate is preferably aging in the R direction. Do.

The reason that the rubbing cloth aged in a specific direction affects the contrast because it is affected by the step difference caused by the structure formed on the substrate used for the liquid crystal display device. Each structure, including the thin film transistor formed on the substrate is stepped in a specific direction, even after rubbing to create a non-uniform surface causes a problem that the light leakage or contrast ratio is reduced. At this time, especially when rubbing by the rubbing cloth aged in the R direction serves to reduce the step has the advantage of reducing the above problems.

In addition, in the case of liquid crystal display devices that need to orient the liquid crystal in a specific direction such as IPS (In Plane Switching) method, the thin film transistor substrate or the color filter substrate may be applied after giving directionality to the trapping itself of the rubbing cloth through aging. The rubbing has the advantage of easily aligning the liquid crystal.

The reason why the contrast ratio in the R direction or the L direction of the rubbing cloth for rubbing the thin film transistor substrate may be different from that of the color filter substrate, and there may be various reasons. The structure is formed, and thus, there is a cause that the uniformity of the liquid crystal is lower than that of the color filter substrate. That is, the effect of increasing the uniformity when rubbing the alignment film of the substrate is expected to be great by aging in the rubbing cloth specific R direction of the thin film transistor substrate.

At this time, the contrast ratio when the thin film transistor is fixed with the rubbing cloth in the L direction or the R direction does not have a large difference in the L direction or the R direction. However, since the rubbing cloth in the R direction has a better contrast ratio, the color filter substrate is also preferably rubbed in the R direction.

Therefore, in the present invention, as a result of rubbing the alignment film between the thin film transistor substrate and the color filter substrate in the R direction, as compared to the rubbing cloth that has undergone the aging process without the directivity, the luminance in the black and the contrast ratio can be increased. It works. This is related to the image quality of the liquid crystal display device, which makes it possible to provide a high quality liquid crystal display device according to the direction of rubbing trap as described above.

The present invention is not limited only to the structure as described above. The above-described structure is only one example for explaining the present invention. For example, the most suitable direction of trapping may vary depending on the type of substrate used in the liquid crystal display, the circuit or other structure formed on the substrate, the type or thickness of the alignment layer, and thus may be aged.

In addition, in the exemplary embodiment of the present invention, two opposing substrates are described as a thin film transistor substrate and a color filter substrate. However, the present invention may also be applied to a COT structure in which a color filter is formed on the thin film transistor substrate.

Accordingly, the scope of the present invention should not be defined by the above detailed description, but should be defined by the appended claims.

Therefore, in the present invention, by providing a method for aging trapping of the rubbing cloth for rubbing the thin film transistor substrate and the color filter substrate in the R direction, the uniformity in the arrangement of the liquid crystal can be increased. In addition, there is an advantage that the liquid crystal display device can provide a liquid crystal display device having a low luminance in black and a high contrast ratio. Therefore, the present invention makes it possible to provide a high quality liquid crystal display device.

Claims (6)

Preparing a rubbing roller in which the rubbing cloth is wound; Arranging the rubbing roller at an angle with respect to the x axis of the dummy substrate having a long side direction of the x-axis and a short side direction of the y-axis; A rubbing cloth aging method comprising the step of proceeding the aging by rotating the rubbing roller parallel to the x-axis direction. The method of claim 1, The rubbing roller aging method, characterized in that the predetermined angle with respect to the x-axis is greater than 5 ° and less than 40 °. The method of claim 2, A rubbing cloth aging method, characterized in that rubbing so that the trapping of the rubbing cloth is formed in the right direction. Preparing a rubbing cloth; Winding the rubbing cloth onto a rubbing roller; Arranging the rubbing roller winding the rubbing cloth at an angle with respect to the x axis of the dummy substrate having a long side direction of an x axis and a short side direction of a y axis; Rotating the rubbing roller in the x-axis direction to perform aging; And rubbing the substrate on which the alignment layer is formed with the aged rubbing cloth. The method of claim 4, wherein And rubbing the substrate comprises rubbing the thin film transistor substrate. The method of claim 5, And rubbing the substrate further comprises rubbing the color filter substrate.

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