JPH0829792A - Production of liquid crystal display panel - Google Patents

Abstract

PURPOSE:To improve irradiation accuracy and use efficiency of UV rays to cure a sealing resin, to obtain a sufficiently hardened state of the sealing resin by irradiation of UV rays in a short time, and to obtain a liquid crystal display panel in which the display state shows no change of colors and threshold voltage to the adjacent area to the sealing resin when the panel is turned on. CONSTITUTION:An optical lens 8 is attached to the slit part S of a UV shielding mask 4 and this UV-shielding mask 4 is laminated so that the slit part S overlaps the sealing resin 6 of a panel 6. The sealing resin is irradiated with UV rays through the optical lens 8 on the slit part S. Thus, the width of optical path when UV rays transmit through the sealing resin 6 is made min. while the energy of focused light is increased. Thereby improving the irradiation accuracy and use efficiency of UV rays and hardening the sealing resin 6 enough with UV rays in a short time.

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 panel.

[0002]

2. Description of the Related Art In a liquid crystal display panel, glass beads or plastic beads are arranged in the liquid crystal part in order to make the thickness of the liquid crystal material layer sandwiched between glass substrates uniform, and in order to separate the liquid crystal from the external environment. , A resin seal mixed with glass fiber is used. As a method of enclosing the liquid crystal material between the glass substrates, there are a vacuum injection method and a dropping method, and the latter is superior in terms of manufacturing efficiency. A method of dropping a liquid crystal material on a glass substrate on one side (JP-A-62-89).
In Japanese Patent Laid-Open No. 025 and Japanese Patent Laid-Open No. 63-179323), an ultraviolet curable resin is used as a seal resin, and the liquid crystal material is cured by irradiation with ultraviolet rays while being in contact therewith.

FIG. 4 shows a step of curing the sealing resin by ultraviolet rays in this conventional manufacturing method. In FIG. 4, 1 is a reflection plate, 2 is an ultraviolet lamp, 3 is incident light, 4 is an ultraviolet blocking mask provided with a slit S, 5 is an indium tin oxide thin film electrode (ITO electrode) and orientation on a glass substrate. A substrate on which a film is formed, 6 is a sealing resin made of an ultraviolet curable resin, and 7 is a liquid crystal.

This conventional curing of the sealing resin by ultraviolet rays is performed by dropping a nematic liquid crystal material on the rubbing-treated surface of one of the two substrates 5 having the ITO electrode and the alignment film formed on the glass substrate, and vacuuming. After assembling the liquid crystal panel by adhering the two substrates 5 inside so that the respective rubbing treated surfaces are on the inside, as shown in FIG. 4, the UV blocking mask 4 is placed on the liquid crystal display panel for display. The liquid crystal 7 that serves as a portion is protected, and ultraviolet rays are irradiated by the ultraviolet lamp 2 through a slit S provided in a portion corresponding to the sealing resin 6 to cure the sealing resin 6.

[0005]

However, according to the above-mentioned conventional method, the ultraviolet rays passing through the slit S of the ultraviolet shielding mask 4 are applied to the liquid crystal 7 portion at the time of resin sealing,
The liquid crystal 7 is prone to decomposition and alteration, and in particular, the birefringence of the liquid crystal 7 changes, and Δn · d (Δn is the birefringence, d is the gap of the liquid crystal cell) becomes small, and the color at the time of resin sealing is the display area. There was a problem that it became whiter.

When three ultraviolet curable resins A, B, and C are used as the seal resin 6, liquid crystal panels are respectively assembled, and the resin is cured by ultraviolet irradiation according to the structure shown in FIG. 4 to evaluate the resin seal. The results obtained are shown in (Table 1). The UV curable resin A is cured by UV irradiation for a short period of time, but alignment is difficult at the time of laminating substrates, and the UV curable resins B and C cannot be sufficiently cured by UV irradiation for a short period of time. The one that was easy to position when pasting was used. In addition, the evaluation of the resin seal includes the threshold voltage measurement of the liquid crystal panel, the dielectric constant / specific resistance value measurement in the low frequency region, and the seal resin peeling strength test.

[0007]

[Table 1] As shown in (Table 1), when the ultraviolet irradiation time is 90 seconds, the ultraviolet curable resins A and B are sufficiently cured,
The UV curable resin C cannot be sufficiently cured.
As described above, the ultraviolet irradiation time to the sealing resin 6 which is an ultraviolet curable resin is required to be at least 90 seconds or more, and when unevenness such as a short irradiation time occurs, impurities such as insufficient curing are applied to the liquid crystal 7 portion when the sealing is insufficient. Exudation of the ionic component causes a partial change in the threshold voltage. For this reason, when a double seal structure is formed by using a seal resin insoluble in the liquid crystal material in a portion in contact with the liquid crystal 7, there is a problem that the seal resin insoluble in the liquid crystal material has a weak adhesive strength.

The object of the present invention is to improve the irradiation accuracy and utilization efficiency of ultraviolet rays for curing the sealing resin, to obtain sufficient curing of the sealing resin by irradiation of ultraviolet rays for a short time, and to display the sealing resin in the lighting display state. It is an object of the present invention to provide a method for manufacturing a liquid crystal display panel, which can realize a good liquid crystal display panel that does not change color and threshold voltage.

[0009]

A method of manufacturing a liquid crystal display panel according to claim 1, wherein a step of assembling the panel by sealing the liquid crystal with an ultraviolet curable resin to sandwich the liquid crystal between a pair of substrates, and an ultraviolet ray. An optical lens is provided in the slit portion of the shielding mask, the slit portion of the ultraviolet shielding mask is arranged at a position overlapping with the ultraviolet curable resin of the panel, and the ultraviolet curable resin is irradiated with ultraviolet rays through the optical lens provided in the slit portion to make the resin. And a curing step.

A method of manufacturing a liquid crystal display panel according to a second aspect is the method of manufacturing a liquid crystal display panel according to the first aspect, wherein ultraviolet shielding masks provided with optical lenses in slits are arranged on both sides of the panel, It is characterized by irradiating ultraviolet rays from both sides to cure the ultraviolet curable resin. The method for manufacturing a liquid crystal display panel according to claim 3 is the method for manufacturing a liquid crystal display panel according to claim 1, wherein the optical axis of the optical lens provided on the ultraviolet shielding mask is set outside the liquid crystal portion of the panel. It is characterized by

[0011]

According to the manufacturing method of the first aspect, the optical lens is provided in the slit portion of the ultraviolet shielding mask, the slit portion of the ultraviolet shielding mask is arranged at a position overlapping with the ultraviolet curable resin of the panel, and the slit portion is provided. By irradiating the ultraviolet curable resin with the ultraviolet rays through the optical lens, the optical path width at the time when the ultraviolet rays pass through the ultraviolet curable resin can be minimized and the condensing power can be increased. Therefore, the irradiation accuracy and utilization efficiency of ultraviolet rays are improved, sufficient curing of the sealing resin (ultraviolet curing resin) can be obtained by irradiation of ultraviolet rays for a short time, and the change in color and threshold voltage changes until the lighting display state reaches the sealing resin. A good liquid crystal display panel can be realized.

Further, according to the manufacturing method of claim 2,
By arranging UV blocking masks with optical lenses in the slits on both sides of the panel and irradiating UV rays from both sides of the panel, sufficient curing of the sealing resin (UV curing resin) can be obtained with shorter UV irradiation. To be Further, according to the manufacturing method of the third aspect, by setting the optical axis of the optical lens so as to be off the outside of the liquid crystal portion of the panel, it is possible to easily prevent alteration of the liquid crystal material.

[0013]

Embodiments of the present invention will be described in detail below. (First Embodiment) First, a method of manufacturing the liquid crystal display panel of the first embodiment will be described. FIG. 1 is a schematic view showing a step of curing a seal resin by ultraviolet rays in a method of manufacturing a liquid crystal display panel according to a first embodiment of the present invention. In FIG. 1, 1 is a reflection plate, 2 is an ultraviolet lamp, 3 is incident light, 4 is an ultraviolet blocking mask provided with an optical lens 8 in the slit S portion, and 5 is an indium tin oxide thin film electrode ( A substrate having an ITO electrode) and an alignment film formed thereon, 6 is a sealing resin made of an ultraviolet curable resin, and 7 is a liquid crystal.

First, the steps until the sealing resin is cured by ultraviolet rays will be described. Two substrates with ITO electrodes formed on glass substrates were prepared, and an aromatic polyamic acid solution (P, manufactured by Chisso Petrochemical Co., Ltd. was used on each substrate.
SI-A-2201) was applied by a spinner so that the film thickness would be 800 Å. After the preliminary curing heat treatment at 80 ° C. for 15 minutes, a thermal curing treatment at 240 ° C. for 1 hour was performed to form a polyimide alignment film.

Next, the alignment film surface of each substrate (first substrate and second substrate) is subjected to 240 by a normal rubbing method.
Orientation treatment was performed so as to form a twist structure. Next, 0.1 wt% of a glass fiber having a diameter of 6 μm was mixed with an ultraviolet curable resin outside the ITO electrode pixel of the first substrate, and screen printing was performed with a predetermined line width. Further, on the rubbing-treated surface of the second substrate, glass beads with a heat-fixing resin having a diameter of 6 microns (Catalyst Kasei Kogyo Co., Ltd., Masago-sphere), which guarantees a required gap thickness, have a density of about 150 / m 2.
sprayed at m ² . Then, the glass beads were heat-fixed to the second substrate at 150 ° C.

After that, a nematic liquid crystal material (for STN: ZLI-22 manufactured by Merck & Co., Inc.) is formed so that the required gap thickness is obtained.
93: Addition of a chiral liquid crystal material that ensures a twist angle of 240 °) was uniformly dropped on the rubbing-treated surface of the first substrate. Then, in a vacuum, the first substrate and the second substrate
The substrates of (1) and (2) were attached so that the respective rubbing-treated surfaces were on the inside, and the pressure was reduced to atmospheric pressure to complete the assembly of the liquid crystal panel.

After that, the ultraviolet curing resin, which is the sealing resin 6, is cured by the method shown in FIG. That is, this embodiment is characterized in that the ultraviolet blocking mask 4 having the optical lens 8 provided in the slit S portion is used, and the ultraviolet blocking mask 4 is installed so that the slit S portion overlaps the sealing resin 6 of the liquid crystal panel. did. Then, the ultraviolet lamp 2 provided with the reflection plate 1 was turned on, and ultraviolet irradiation was performed for a predetermined time. The irradiation time is the minimum time 9 confirmed in the conventional example.
An ultraviolet irradiation experiment was performed for 60 seconds and 30 seconds based on 0 second.

Also in this first embodiment, as in the conventional example, three ultraviolet curable resins A,
With respect to the cases of using B and C, the liquid crystal panels were assembled, the resin was cured by ultraviolet irradiation, and the resin seal was evaluated. The results are shown in Table 2. As described in the conventional example, the ultraviolet curable resin A is cured by irradiation of ultraviolet rays for a short time, but the alignment is difficult at the time of laminating the substrates, and the ultraviolet curable resins B and C are sufficiently irradiated by ultraviolet rays for a short time. A material that could not be cured but was easy to align when the substrates were laminated was used. Further, in the resin seal evaluation, as in the conventional example, the threshold voltage measurement of the liquid crystal panel, the dielectric constant / specific resistance value measurement in the low frequency region and the seal resin peel strength test are used as evaluation items.

[0019]

[Table 2] As shown in (Table 2), for the ultraviolet curable resin A,
Sufficient curing was obtained when the UV irradiation time was 60 seconds. Also, for the UV curable resins B and C, the UV irradiation time 9
Sufficient cure was obtained at 0 seconds. According to this embodiment,
The optical lens 8 is provided in the slit S portion of the ultraviolet shielding mask 4, the slit S portion of the ultraviolet shielding mask 4 is arranged at a position overlapping the sealing resin 6 of the panel, and the sealing resin is provided through the optical lens 8 provided in the slit S portion. By irradiating 6 with ultraviolet rays, it is possible to minimize the optical path width at the time when the ultraviolet rays pass through the sealing resin 6 and increase the light collecting power. Therefore, the irradiation accuracy and utilization efficiency of ultraviolet rays are improved, and as can be seen from the comparison between (Table 1) and (Table 2), sufficient curing of the sealing resin 6 can be obtained by irradiation of ultraviolet rays for a short time, and the lighting display state can be improved. However, it is possible to realize a good liquid crystal display panel in which there is no change in color and threshold voltage even before the sealing resin and a uniform display state can be obtained.

(Second Embodiment) Next, a method of manufacturing the liquid crystal display panel of the second embodiment will be described. FIG. 2 is a schematic view showing a step of curing the seal resin by ultraviolet rays in the method of manufacturing a liquid crystal display panel according to the second embodiment of the present invention. 2, the same parts as those in FIG. 1 are designated by the same reference numerals.

Also in the second embodiment, as in the first embodiment, a liquid crystal display panel using the ultraviolet curing resins A, B and C as the sealing resin 6 is assembled, and then the method shown in FIG. Thus, the ultraviolet curable resin which is the seal resin 6 is cured. In this embodiment, the ultraviolet blocking masks 4 provided with the optical lens 8 in the slit S portion used in the first embodiment are installed on both sides of the liquid crystal display panel, and both ultraviolet lamps 2 are turned on for a predetermined time. UV irradiation was performed. The irradiation time was set to 60 seconds and 30 seconds based on 90 seconds as in the first embodiment. Similar to the first embodiment, the results of resin curing by ultraviolet irradiation and resin seal evaluation are shown in (Table 2).

As shown in (Table 2), the ultraviolet curable resin A
As for No. 3, sufficient curing was obtained with the ultraviolet irradiation time of 30 seconds. Also, with respect to the ultraviolet curable resins B and C, sufficient curing was obtained when the ultraviolet irradiation time was 60 seconds. According to this embodiment, the ultraviolet shielding masks 4 provided with the optical lenses 8 in the slit portions S are arranged on both sides of the panel, and ultraviolet rays are irradiated from both sides of the panel, so that the sealing resin 6 is irradiated in a shorter time. Sufficient curing is obtained.

(Third Embodiment) Next, a method of manufacturing the liquid crystal display panel of the third embodiment will be described. FIG. 3 is a schematic view showing a step of curing the seal resin by ultraviolet rays in the method of manufacturing a liquid crystal display panel according to the third embodiment of the present invention. In FIG. 3, 9 is an optical lens, and 10 is an ultraviolet shielding mask, and the same parts as in FIG.

Also in the third embodiment, as in the first embodiment, a liquid crystal display panel using the ultraviolet curable resins A, B and C as the sealing resin 6 is assembled and then the method shown in FIG. Thus, the ultraviolet curable resin which is the seal resin 6 is cured. In this embodiment, an ultraviolet blocking mask 4 in which an optical lens 9 whose focus optical axis is off the outside of the liquid crystal 7 is provided in the slit S portion is used, and an ultraviolet blocking mask 10 is provided between the ultraviolet blocking mask 4 and the liquid crystal panel. It is installed between them to prevent ultraviolet rays from entering the liquid crystal 7 portion. Then, the ultraviolet lamp 2 was turned on, and ultraviolet irradiation was performed for a predetermined time. The irradiation time was set to 60 seconds and 30 seconds based on 90 seconds as in the first embodiment. Similar to the first embodiment, the results of resin curing by ultraviolet irradiation and resin seal evaluation are shown in (Table 2).

As shown in (Table 2), the ultraviolet curable resins A, B and C were sufficiently cured when the ultraviolet irradiation time was 30 seconds. According to this embodiment, by setting the optical axis of the optical lens 9 so as to deviate outside the liquid crystal 7 portion of the panel, it becomes possible to easily prevent alteration of the liquid crystal material. Further, by disposing the ultraviolet ray blocking mask 4 provided with the optical lens 9, the ultraviolet ray blocking mask 10 and the ultraviolet ray lamp 2 having the reflecting plate 1 on both sides of the panel as in the second embodiment, the irradiation time Needless to say, can be shortened further.

In the above example, a good liquid crystal display panel was realized in which the sample which was sufficiently cured was free from color change and threshold voltage change until the lighting display state was near the sealing resin.

[0027]

According to the method of manufacturing a liquid crystal display panel of claim 1, an optical lens is provided in the slit portion of the ultraviolet shielding mask, and the slit portion of the ultraviolet shielding mask is arranged at a position overlapping with the ultraviolet curing resin of the panel, and the slit is formed. By irradiating the ultraviolet curable resin with ultraviolet rays through the optical lens provided in the portion, the optical path width at the time when the ultraviolet rays pass through the ultraviolet curable resin can be minimized and the light collecting power can be increased. Therefore, the irradiation accuracy and utilization efficiency of ultraviolet rays are improved, sufficient curing of the sealing resin (ultraviolet curing resin) can be obtained by irradiation of ultraviolet rays for a short time, and the change in color and threshold voltage change until the lighting display state reaches the sealing resin. Without
A good liquid crystal display panel that can obtain a uniform display state can be realized.

Further, in the method for manufacturing a liquid crystal display panel according to the second aspect, an ultraviolet ray shielding mask having an optical lens provided in a slit portion is arranged on both sides of the panel, and ultraviolet rays are irradiated from both sides of the panel to shorten the time. Sufficient curing of the sealing resin (ultraviolet curable resin) can be obtained by irradiating the ultraviolet ray. Further, in the method for manufacturing a liquid crystal display panel according to the third aspect, it is possible to easily prevent the liquid crystal material from deteriorating by setting the optical axis of the optical lens so as to be out of the liquid crystal portion of the panel.

[Brief description of drawings]

FIG. 1 is a schematic view showing a step of curing a sealing resin by ultraviolet rays in a method of manufacturing a liquid crystal display panel according to a first embodiment of the present invention.

FIG. 2 is a schematic view showing a step of curing a seal resin by ultraviolet rays in a method of manufacturing a liquid crystal display panel according to a second embodiment of the present invention.

FIG. 3 is a schematic view showing a step of curing a seal resin by ultraviolet rays in a method of manufacturing a liquid crystal display panel according to a third embodiment of the present invention.

FIG. 4 is a schematic view showing a sealing resin curing step by ultraviolet rays in a conventional method for manufacturing a liquid crystal display panel.

[Explanation of symbols]

 1 Reflector 2 Ultraviolet Lamp 3 Incident Light 4,10 Ultraviolet Blocking Mask 5 Substrate 6 Seal Resin 7 Liquid Crystal 8, 9 Optical Lens

Claims (3)

[Claims] 1. A step of assembling a panel by sealing the liquid crystal with an ultraviolet curable resin to sandwich the liquid crystal between a pair of substrates, and providing an optical lens in a slit portion of the ultraviolet shielding mask,
A liquid crystal display including a step of arranging a slit portion of the ultraviolet shielding mask in a position overlapping with the ultraviolet curable resin of the panel, and irradiating the ultraviolet curable resin with ultraviolet rays through an optical lens provided in the slit portion to cure the resin. Panel manufacturing method. 2. The ultraviolet-shielding mask having an optical lens in the slit portion is arranged on both sides of the panel, and ultraviolet rays are irradiated from both sides of the panel to cure the ultraviolet-curing resin. Liquid crystal display panel manufacturing method. 3. The method of manufacturing a liquid crystal display panel according to claim 1, wherein the optical axis of the optical lens provided on the ultraviolet shielding mask is set outside the liquid crystal portion of the panel.