JP3497372B2 - Manufacturing method of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate rubbing without developing any crack of an alignment layer or the disturbance of an alignment state. SOLUTION: A pile constituted of rayon is used for a rubbing cloth to be used for an alignment layer processing (rubbing) for uniformly aligning liquid crystal molecules. Then, the water content W of the rubbing cloth is controlled so as to be 8%<=W<=12% by maintaining it in a thermo-hygrostat. In controlling the water content of the rubbing cloth, the temperature and humidity of the thermo-hygrostat is maintained respectively so as to be 25 deg.C and 50%, and in leaving the rubbing cloth in the thermo-hygrostat for 24 hours, the water content of the rubbing cloth is set so as to be almost 10%. Also, the pile constituted of rayon is used as the rubbing cloth so that the water content of the rubbing cloth can be easily controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device in which a liquid crystal material is sandwiched between a pair of substrates, and more particularly to an alignment treatment by a rubbing method using a rubbing cloth.

[0002]

2. Description of the Related Art Rubbing is performed on a substrate on which an alignment film made of polyimide or the like is formed, and a non-woven fabric (rubbing cloth) made of rayon or the like around a cylindrical rubbing roller.
Is attached, and the substrate is moved while rotating the rubbing roller, or the rubbing roller itself is moved while rotating the rubbing roller, whereby the surface of the alignment film is rubbed.

The rubbing has the following problems. First, the pile is removed from the rubbing cloth to generate foreign matter. Further, static electricity is generated due to friction between the substrate and the rubbing cloth, and the alignment state is disturbed by discharging between the electrodes formed on the substrate. Further, when a large amount of the substrate is rubbed, the pile of the rubbing cloth is disturbed to damage the alignment film or disturb the alignment state. If the alignment film is scratched or the alignment state is disturbed, the pretilt angle of the liquid crystal molecules varies, and the display quality of the liquid crystal display device is degraded.

When the rubbing cloth is stuck to the rubbing roller, a double-sided tape is used, but the sticking of the rubbing cloth is uneven, for example, when the rubbing cloth is not partially stuck (so-called floating) or rubbing. When the adhesion strength between the cloth and the rubbing roller is low, the alignment film is scratched or the alignment state is disturbed as described above, and the pretilt angle of the liquid crystal molecules is varied to deteriorate the display quality of the liquid crystal display device.

In order to solve such problems, Japanese Patent Laid-Open Nos. 1-225918 and 5-249467.
The following method has been proposed in the publication.

The method proposed in Japanese Unexamined Patent Publication No. 1-225918 is such that rubbing is performed in an atmosphere having a humidity of 50% or more,
The static electricity generated by the friction between the substrate and the rubbing cloth is reduced.

The method proposed in JP-A-5-249467 is to reduce the static electricity generated by rubbing between the substrate and the rubbing cloth by rubbing in an atmosphere having a humidity of 50 to 70%.

[0008]

However, in the above two methods, since the rubbing cloth is attached to the rubbing roller with the double-sided tape, the adhesion strength between the rubbing cloth and the double-sided tape and the rubbing roller and the double-sided tape is uniform. It is difficult to keep it on, and the rubbing cloth floats. As a result, the distance between the rubbing cloth and the substrate becomes uneven,
The alignment film is scratched or the alignment state is disturbed, and the pretilt angle of the liquid crystal molecules is varied, so that the display quality of the liquid crystal display device is deteriorated.

Further, although static electricity generated by friction between the substrate and the rubbing cloth can be reduced, it is not satisfactory.

The present invention has been made in view of the above conventional problems, and provides a method of manufacturing a liquid crystal display device capable of rubbing without damaging the alignment film or disturbing the alignment state. It is intended to be provided.

[0011]

In order to achieve the above-mentioned object, a method of manufacturing a liquid crystal display device according to the present invention is a liquid crystal display device in which an alignment treatment for aligning liquid crystal molecules is performed by a rubbing method using a rubbing cloth. in the manufacturing method, the
Constant temperature and humidity to set the water content of the rubbing cloth to the set value
The method is characterized by having a step of storing the rubbing cloth in a tank for a certain period of time, and performing an orientation treatment with the water content of the rubbing cloth being 8% to 12%.

The method of manufacturing a liquid crystal display device according to the present invention is characterized in that, in the method of manufacturing a liquid crystal display device described above , the alignment treatment is performed in an atmosphere having a humidity of 40% to 80%.

Further, according to the method of manufacturing a liquid crystal display device of the present invention, a rubbing cloth having a water content of 8% to 12% is attached to a rubbing roller, and the humidity is 40% to 80% in an atmosphere.
It is characterized in that the alignment treatment is carried out after leaving it for 0 to 30 hours.

The method for manufacturing a liquid crystal display device of the present invention is characterized in that, in the method for manufacturing a liquid crystal display device described above , the pile of the rubbing cloth is made of rayon.

According to the method of manufacturing a liquid crystal display device of the present invention , in order to adjust the water content of the rubbing cloth to a set value.
There is a process to store the rubbing cloth in a constant temperature and humidity chamber for a certain time.
Then, by performing the orientation treatment with the water content of the rubbing cloth set to 8% to 12%, the adhesion strength between the double-sided tape for sticking the rubbing cloth on the rubbing roller and the rubbing cloth can be increased. It prevents floating or peeling of the rubbing cloth, and does not cause a problem of damaging the alignment film. Furthermore, the amount of static electricity generated during the alignment treatment can be reduced, and since the piles of the rubbing cloth do not stick to each other, a good alignment state can be obtained.

The amount of static electricity generated during the alignment treatment is synergistic with that of controlling the water content of the rubbing cloth to 8% to 12% by carrying out the alignment treatment in an atmosphere having a humidity of 40% to 80%. Can be sufficiently reduced.

Further, a rubbing cloth having a water content of 8% to 12% is attached to a rubbing roller by using a double-sided tape,
After leaving it in an atmosphere of humidity 40% to 80% for 20 hours to 30 hours, by performing an orientation treatment, the adhesion strength between the rubbing cloth and the double-sided tape can be improved without lowering the workability when replacing the rubbing cloth. The height can be raised to prevent the rubbing cloth from floating or peeling off during the alignment treatment.

Further, since the pile of the rubbing cloth is made of rayon, the water content of the rubbing cloth is 8% to 12%.
It becomes easy to control.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory view showing the water content of the rubbing cloth, and FIG. 2 is an explanatory view showing the adhesion strength of the rubbing cloth.

An outline of a general manufacturing method of a liquid crystal display device is as follows. Here, an STN type liquid crystal display device will be described as an example.

Patterning of transparent electrodes formed on a pair of substrates Forming an alignment film on a pair of substrates Alignment treatment on an alignment film on a pair of substrates Arranging a gap holding material on one substrate Forming a seal on the other substrate Pair of substrates In the following, the "alignment treatment for the alignment films of the pair of substrates" will be described. Since the other manufacturing method is the same as the conventional manufacturing method, description thereof will be omitted.

The rubbing cloth used for the alignment treatment (rubbing) for uniformly aligning the liquid crystal molecules is, for example, Y manufactured by Yoshikawa Kako Co., Ltd.
A pile of rayon such as A-18R is used. The rubbing cloth is stored in a constant temperature and humidity chamber so that the water content (W) of the rubbing cloth is 8% ≦ W ≦ 12%.
To control.

As an example of controlling the water content of the rubbing cloth, as shown in FIG. 1, a constant temperature and humidity chamber is set at a temperature of 25 ° C. and a humidity of 50.
%, And when the rubbing cloth is left standing in this constant temperature and humidity chamber for 24 hours, the water content of the rubbing cloth is about 10%. Further, by using a rubbing cloth whose pile is made of rayon, it becomes easy to control the water content of the rubbing cloth.

The water content of this rubbing cloth is 8% ≦ W ≦ 12
If it is outside the range of%, the adhesion strength between the acrylic double-sided tape for sticking the rubbing cloth to the rubbing roller and the rubbing cloth becomes low, and the rubbing cloth floats or peels off, which damages the alignment film. Occurs. Furthermore, if the water content of the rubbing cloth is less than 8%, the amount of static electricity generated during rubbing cannot be sufficiently reduced. Furthermore, the water content of the rubbing cloth is 1
When the amount is more than 2%, the piles absorb moisture and the adjacent piles stick to each other, resulting in non-uniform rubbing and scratching the alignment film or disturbing the alignment state to cause variations in the pretilt angle of liquid crystal molecules.

The water content of the rubbing cloth is measured by heating a small amount of the rubbing cloth at 150 ° C., flowing dry nitrogen gas into the rubbing cloth, and removing the nitrogen gas which has become wet nitrogen gas by containing the generated steam. The measurement is performed by the Karl Fischer method.

When rubbing, the humidity (H) of the room in which the rubbing device is installed is controlled to 40% ≤H≤80%. When the humidity is lower than 40%, the amount of static electricity generated during rubbing increases, abnormal discharge of static electricity occurs, the alignment state is disturbed and pixel destruction occurs, and when the humidity is higher than 80%, rubbing is performed by pseudo contact. The device malfunctions.
The temperature is controlled at 25 ° C ± 3 ° C.

The rubbing roller has a water content of 8% ≦.
The rubbing cloth with W ≦ 12% is attached with an acrylic double-sided tape, for example, TL-83S-U manufactured by Lintec Co., and the rubbing roller with the rubbing cloth attached is stored in a room where the humidity is 40% ≦ H ≦ 80%. In this state, it is left for 20 hours ≤ standing time ≤ 30 hours and then used for rubbing.

In this way, as shown in FIG. 2, the adhesion strength between the acrylic double-sided tape and the rubbing cloth and the rubbing roller is optimized, in other words, the adhesion strength between the rubbing cloth and the rubbing roller is optimized. Can be planned. The water content of the rubbing cloth is 10%, and the atmosphere for leaving is 25 ° C. and 60% humidity.

If this leaving time is shorter than 20 hours,
If the adhesion strength is low and the rubbing cloth peels off during rubbing and the standing time is longer than 30 hours, the adhesion strength between the rubbing cloth and the acrylic double-sided tape is sufficient, but the adhesion strength between the rubbing roller and the acrylic double-sided tape is If the acrylic double-sided tape is too high, it becomes difficult to peel the acrylic double-sided tape from the rubbing roller, and the workability when the rubbing cloth is replaced is significantly reduced.

The adhesion strength of the rubbing cloth is measured by sticking an acrylic double-sided tape on a plate made of the same material as the rubbing roller, and sticking a uniform size rubbing cloth on it. Then, the plate to which the rubbing cloth is attached is fixed, the rubbing cloth is pulled at a constant speed, and the maximum tensile strength immediately before peeling is obtained as the adhesion strength.

Table 1 shows the amount of static electricity on the surface of the alignment film when rubbing was performed under the above conditions. Table 2 shows the display quality of the liquid crystal display device manufactured by rubbing in this embodiment.

[0032]

[Table 1]

As shown in Table 1, when the humidity is less than 40% and the water content of the rubbing cloth is less than 8%, the static electricity amount on the surface of the alignment film is 10 kV or more, which is not a satisfactory value. Further, when the moisture content of the rubbing cloth is less than 8% at a humidity of 40% to 80%, the static electricity amount on the surface of the alignment film is 8 kV, which is not a satisfactory value.

On the other hand, when the humidity is less than 40% and the water content of the rubbing cloth is 8% to 12%, the static electricity amount on the surface of the alignment film is 7 k.
The value of V is almost satisfactory. Furthermore, humidity 40% ~
When the water content of the rubbing cloth is 80% and 8% to 12%, the static electricity amount on the surface of the alignment film is less than 5 kV, which is a satisfactory value.

[0035]

[Table 2]

As shown in Table 2, when the humidity is less than 40% and the water content of the rubbing cloth is less than 8%, the display quality of the liquid crystal display device is poor, and the water content of the rubbing cloth is 40% to 80%. Is less than 8%, the display quality of the liquid crystal display device is somewhat poor.

On the other hand, when the moisture content of the rubbing cloth is less than 40% and the water content of the rubbing cloth is 8% to 12%, the display quality of the liquid crystal display device is almost good, and the water content of the rubbing cloth is 8% at the humidity of 40% to 80%. In the case of% -12%, the display quality of the liquid crystal display device is good.

[0038]

As described above, according to the method of manufacturing a liquid crystal display device of the present invention, the water content of the rubbing cloth is set.
Keep the rubbing cloth in the constant temperature and humidity chamber for a certain time
The tube has a tube forming step, and the rubbing cloth has a water content of 8% to 12%.
By performing the alignment treatment as%, the rubbing cloth is prevented from being lifted or the rubbing cloth is peeled off, and the alignment film is not damaged. Furthermore, the amount of static electricity generated during the alignment treatment can be reduced, and since the piles of the rubbing cloth do not stick to each other, a good alignment state can be obtained.

The amount of static electricity generated during the alignment treatment is increased by the synergistic effect of controlling the water content of the rubbing cloth to 8% to 12% by performing the alignment treatment in an atmosphere having a humidity of 40% to 80%. Can be sufficiently reduced.

A rubbing cloth having a water content of 8% to 12% was attached to the rubbing roller by using a double-sided tape,
By leaving the rubbing cloth in an atmosphere having a humidity of 40% to 80% for 20 hours to 30 hours, and then performing the orientation treatment, the rubbing cloth floats or is rubbed during the orientation treatment without lowering the workability when the rubbing cloth is replaced. It is possible to prevent the peeling.

Further, since the pile of the rubbing cloth is made of rayon, the water content of the rubbing cloth is 8% to 12%.
It becomes easy to control.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a water content of a rubbing cloth.

FIG. 2 is an explanatory diagram showing the adhesion strength of a rubbing cloth.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-1-225918 (JP, A) JP-A-1-298315 (JP, A) JP-A-3-208019 (JP, A) JP-A-5- 249267 (JP, A) JP-A-3-126916 (JP, A) JP-A-3-239220 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/1337

Claims (2)

(57) [Claims] 1. An alignment treatment for aligning liquid crystal molecules is performed by Rabin.
LCD device manufactured by rubbing method
In the manufacturing method, a rubbing cloth having a water content of 8% to 12% is coated with a double-sided tape.
Affix to a rubbing roller using a
After leaving it in an 80% atmosphere for 20 to 30 hours,
Aligning treatment is performed with the water content of the bing cloth being 8% to 12%.
A method of manufacturing a liquid crystal display device, comprising: 2. An alignment treatment for aligning liquid crystal molecules is performed by Rabin.
LCD device manufactured by rubbing method
In the manufacturing method, a rubbing cloth having a water content of 8% to 12% is coated with a double-sided tape.
Affix to a rubbing roller using a
After leaving it in an 80% atmosphere for 20 to 30 hours,
The moisture content of the bing cloth is 8% to 12%, and the humidity is 40%.
Characterized by performing the alignment treatment in an atmosphere of 80% to 80%
Liquid crystal display device manufacturing method.