JP2815822B2 - Liquid crystal panel manufacturing method - Google Patents

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 panel.

[0002]

2. Description of the Related Art A conventional liquid crystal panel manufacturing method will be described. A TFT (thin film transistor) substrate in which transistor elements are arranged in a matrix on a glass substrate, and a CF (color filter) substrate in which a black matrix and R, G, and B pixels are arranged in a matrix, an alignment agent made of polyimide. Is formed by a flexographic printing method or the like, and then subjected to an orientation treatment by a rubbing treatment or the like.

Next, a sealant made of an epoxy resin or the like is formed in a ring shape on one of the TFT substrate and the CF substrate by a screen printing method, and then a plurality of spherical spacers are uniformly arranged. Next, the TFT substrate and C
An F panel is placed on a positioning device so as to face up and down, and after positioning, pressure and bonding are performed to produce an empty panel.

[0004] Next, the empty panel is taken out of the positioning device, and is left in an oven maintained at 150 ° C for about 1 hour to cure the sealant while uniformly pressing, thereby forming a predetermined gap. FIG. 2 shows the posture (substrate posture) of the empty panel during the curing step of the sealant. In FIG. 2, 1 is a TFT substrate, 2 is a CF substrate, 3 is a sealant, 4
Is a spacer. As shown in FIG. 2, the TFT substrate 1 and the CF substrate 2 are in a posture perpendicular to the direction of gravity during the curing step of the sealant.

Thereafter, liquid crystal was injected into the empty panel, and the injection port was sealed to obtain a liquid crystal panel.

[0006]

In the above-mentioned conventional manufacturing method, after the TFT substrate and the CF substrate are accurately aligned,
The sealant is heated and cured while maintaining the accuracy of the alignment. However, a difference in the coefficient of linear expansion due to the difference in the glass material between the TFT substrate and the CF substrate, and warping of the bonded substrates due to the weight of the substrates occur. Due to the warpage of the substrate, a difference occurs in the total pitch between the TFT substrate and the CF substrate, and the alignment accuracy between the TFT substrate and the CF substrate is deteriorated, the gap accuracy is reduced, and the display quality such as contrast is deteriorated. There was a problem.

[0007] In order to solve such a problem, a method of temporarily fixing the TFT substrate and the CF substrate using an ultraviolet curable resin has been considered. However, also in this method, since the temporary fixing adhesive is applied to the edge of the panel, that is, outside the effective pixels, it is not possible to prevent the warpage of the substrate,
It was not effective against a decrease in position accuracy in the effective screen caused by the difference in the total pitch.

It has also been proposed to use an ultraviolet-curable resin as the sealant. However, in consideration of the adhesiveness to the substrate and the effect on the liquid crystal, the resin is a combination of ultraviolet and heat-curable. The influence of heat at the time is inevitable, and it cannot be said that it is effective in preventing the warpage of the substrate due to its own weight. SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a liquid crystal panel which prevents a decrease in alignment accuracy of two substrates due to warpage of a substrate during curing of a sealant, has a high gap accuracy, and has excellent display quality such as contrast. It is to be.

[0009]

According to a first aspect of the present invention, there is provided a method of manufacturing a liquid crystal panel, wherein a first substrate and a second substrate are aligned with each other via a sealant to form an empty panel, and the sealant is applied. A method for manufacturing a liquid crystal panel, in which liquid crystal is injected into an empty panel after being cured, wherein the curing of the sealant is performed while keeping the attitude of the empty panel parallel to the direction of gravity.

[0010] The method for manufacturing a liquid crystal panel according to claim 2 is characterized in that:
In the method of manufacturing a liquid crystal panel according to the first aspect, when the sealant is cured, the inside of the empty panel is evacuated and pressurized by atmospheric pressure. According to a third aspect of the present invention, in the method for manufacturing a liquid crystal panel according to the first aspect, when the sealant is cured, the empty panel is pressed by a press.

[0011]

According to the present invention, after the first substrate and the second substrate are aligned with each other via the sealant, when the sealant is cured, the posture of the empty panel is kept parallel to the direction of gravity. By performing in a state, the warpage of the substrate, which has been conventionally caused by the weight of the substrate, can be prevented, so that a decrease in alignment accuracy due to the warpage of the substrate is prevented, and the gap of the effective pixel portion is formed uniformly. A liquid crystal panel having excellent display quality such as contrast and the like can be realized.

[0012]

Embodiments of the present invention will be described below. [First Embodiment] First, a method for manufacturing a liquid crystal panel according to a first embodiment of the present invention will be described. A N-methyl-2-pyrrolidone solution of polyamic acid is deposited on a TFT substrate in which transistor elements are arranged in a matrix on a glass substrate, and a CF substrate in which a black matrix and R, G, B pixels are arranged in a matrix. The film is formed by flexographic printing so as to have a thickness of 800 Å. After heating these substrates at 190 ° C. for 90 minutes to obtain a polyimide film, an orientation treatment is performed with a cloth made of rayon.

Next, a sealant made of an epoxy resin or the like is formed in a ring shape on one of the TFT substrate and the CF substrate by a screen printing method, and the average particle diameter is 5 μm.
Are dispersed at a density of 100 pieces / mm ² . A temporary fixing adhesive made of an ultraviolet curable resin was applied to the substrate at four places outside the effective pixel area by a dispenser.

Thereafter, the TFT substrate and the CF substrate are mounted on a positioning device so as to face each other via a sealant and a spacer, and after accurate positioning, 0.3 kg / cm ^2.
While applying pressure, ultraviolet rays are irradiated at a light amount of 500 mJ / cm ² , and the temporarily-fixed adhesive is cured and bonded to form an empty panel. Take out the empty panel that has been pasted from the alignment device, make the inside of the empty panel vacuum by the vacuum packing method, pressurize it evenly by atmospheric pressure, and keep the posture of the empty panel (substrate posture) parallel to the direction of gravity. , 15
By heating at 0 ° C. for 60 minutes, the sealant is hardened to form a predetermined gap. FIG. 1 shows the posture of the empty panel (substrate posture) during the curing step of the sealant. In FIG. 1, 1 is a TFT substrate, 2 is a CF substrate, 3
Is a sealant, and 4 is a spacer. As shown in FIG. 1, the TFT substrate 1 and CF
The substrate 2 has a posture parallel to the direction of gravity.

Thereafter, liquid crystal is injected into the empty panel, and the injection port is sealed to obtain a liquid crystal panel. The liquid crystal panel of this embodiment has a positioning accuracy of ± 2 μm between the TFT substrate and the CF substrate.
m, and the in-plane gap was uniform. In addition, after sealing the liquid crystal injection port, the liquid crystal panel obtained by pasting a polarizing plate has no light leakage from the black matrix end, the in-plane gap accuracy is ± 0.2 μm and the gap accuracy is high,
The liquid crystal panel was excellent in quality without a decrease in contrast.

As described above, according to this embodiment, the TFT
After accurately aligning the substrate and the CF substrate, when the sealant is cured, the position of the empty panel is kept parallel to the direction of gravity when the sealing panel is cured. It is possible to prevent warpage and ensure the alignment accuracy of the TFT substrate and the CF substrate obtained by the alignment device even after the seal hardening process, and it is possible to uniformly form a gap in the effective pixel portion, and to use the sealant. Shrinkage during curing, the effects of stress due to substrate warpage and thermal expansion, etc. are alleviated, making it possible to manufacture panels with high alignment accuracy, without problems such as color unevenness, and without lowering contrast. A liquid crystal panel having excellent quality can be obtained.

Second Embodiment Next, a second embodiment of the present invention will be described.
The manufacturing method of the liquid crystal panel of the embodiment will be described. The process is the same as that of the first embodiment until the TFT substrate and the CF substrate are bonded with a temporary fixing adhesive made of an ultraviolet curing resin. The empty panel on which the bonding is completed is taken out of the positioning device, and the empty panel is pressed uniformly by a press by a pressing method, and as shown in FIG. 1, the posture of the empty panel (substrate posture) is made parallel to the direction of gravity. The sealing agent is cured by heating while keeping the temperature at 150 ° C. for 60 minutes to form a predetermined gap. Thereafter, liquid crystal is injected into the empty panel, and the injection port is sealed to obtain a liquid crystal panel.

In the liquid crystal panel of this embodiment, the alignment accuracy between the TFT substrate and the CF substrate was within ± 2 μm, and the in-plane gap was uniform. In addition, the liquid crystal panel obtained by sealing the liquid crystal injection port and pasting the polarizing plate has no light leakage from the edge of the black matrix, an in-plane gap accuracy of ± 0.2 μm, a high gap accuracy, and a decrease in contrast. There was no liquid crystal panel of excellent quality.

As described above, according to this embodiment, as in the first embodiment, the posture of the empty panel (substrate posture) is kept parallel to the direction of gravity when the sealant is hardened, thereby achieving a difference from the first embodiment. Similar effects can be obtained. Comparative Example Next, a comparative example will be described.

Until the TFT substrate and the CF substrate are bonded together with a temporary fixing adhesive made of an ultraviolet curing resin, the first
This is the same as the embodiment. The bonded empty panel is taken out of the alignment device, and while uniformly pressing the empty panel by the vacuum packing method, the attitude of the empty panel (substrate attitude) is perpendicular to the direction of gravity as in the conventional example shown in FIG. Keep 1
By heating at 50 ° C. for 60 minutes, the sealant is hardened to form a predetermined gap. Thereafter, liquid crystal is injected into the empty panel, and the injection port is sealed to obtain a liquid crystal panel.

The alignment accuracy between the TFT substrate and the CF substrate according to this comparative example was ± 10 μm or more because the panel was warped by its own weight. In addition, the liquid crystal panel obtained by attaching the polarizing plate after sealing the liquid crystal injection port causes light leakage from the end of the black matrix, the in-plane gap accuracy is ± 0.6 μm, the gap accuracy is low, and the contrast is lowered. The liquid crystal panel was inferior in display quality.

From this comparative example, it is clear that the effect of the above embodiment was obtained by keeping the posture of the empty panel (substrate posture) parallel to the direction of gravity when the sealant was cured.

[0023]

According to the method of manufacturing a liquid crystal panel of the present invention, when the first substrate and the second substrate are aligned with each other via the sealant and the sealant is cured, the posture of the empty panel is changed by gravity. By keeping the substrate parallel to the direction, the warpage of the substrate, which has conventionally occurred due to the weight of the substrate, can be prevented. A liquid crystal panel having a uniform gap and excellent display quality such as contrast can be realized.

[Brief description of the drawings]

FIG. 1 is a view showing a posture (substrate posture) of an empty panel during a curing step of a sealant in an embodiment of the present invention.

FIG. 2 is a view showing a posture (substrate posture) of an empty panel during a curing step of a sealant in a conventional example.

[Explanation of symbols]

 Reference Signs List 1 TFT substrate 2 CF substrate 3 Sealant 4 Spacer

Claims (3)

(57) [Claims] 1. A liquid crystal panel according to claim 1, wherein the first substrate and the second substrate are aligned with each other via a sealant to form an empty panel, and after the sealant is cured, liquid crystal is injected into the empty panel. A method of manufacturing a liquid crystal panel, wherein the curing of the sealant is performed while keeping the position of the empty panel parallel to the direction of gravity. 2. The method for manufacturing a liquid crystal panel according to claim 1, wherein when the sealant is cured, the inside of the empty panel is evacuated and pressurized by atmospheric pressure. 3. The method for manufacturing a liquid crystal panel according to claim 1, wherein the empty panel is pressurized by a press when the sealant is cured.