JP2000275656A - Method and device for producing liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method and device for the producing a liquid crystal display device with superior productivity by which failures in cutting a seal caused during heating and curing the sealing material is suppressed, and the gap can be formed highly uniformly over the entire panel. SOLUTION: A thermosetting sealing material is applied on at least one substrate 10, while leaving an injection port to inject a liquid crystal, and then the other substrate 11 is laminated thereon. The substrates 10, 11 laminated with the uncured sealing material is disposed in a reduced pressure state to deaerate the space between the substrates 10, 11. While pressing the substrates 10, 11 as in a deaerated state, the sealing material is heated and cured to form a cell 25 of a prescribed gap between the substrates. Then a liquid crystal is injected into the cell 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal display devices include personal computers, word processors,
It has been applied to liquid crystal televisions, etc., and has recently been widely used as OA displays and projection TVs.
The display quality is improving year by year. Generally, characteristics such as the response speed, contrast, viewing angle, and display uniformity of a liquid crystal display element are closely related to the thickness of the liquid crystal layer, that is, the cell gap.

In such a liquid crystal display element, a liquid crystal sandwiched between two substrates is sealed with a sealing material, and a spacer for securing a gap between liquid crystal cells exists in the sealing material.

The above-mentioned general method of manufacturing a liquid crystal cell encloses a liquid crystal by printing or dispenser drawing a resin adhesive containing glass fiber on an electrode substrate so as to have a liquid crystal injection port. For example, a thermosetting sealing material is formed, resin or silica spheres are uniformly dispersed on the electrode substrate as a spacer for securing a gap between the substrates, and the two substrates are bonded to each other. Then, the sealing material is heated and cured while pressing the electrode substrate to secure a predetermined cell gap, and unnecessary portions of the substrate are cut to complete a liquid crystal cell, and the liquid crystal is filled in the cell by a conventional method such as a vacuum injection method. The liquid crystal is injected and the liquid crystal injection port is sealed to complete a liquid crystal display element.

Here, in order to ensure the uniformity of the cell gap, it is necessary to cure the sealing material in a state where the bonded substrates are uniformly pressed. As a device for forming a cell gap, a pressure press using a heating platen is generally used, but in order to achieve uniform pressing, it is necessary to bond two high-precision pressure-heating platens with high accuracy. Yes, the structure of the device is very complicated and costly. In addition, there are many problems related to productivity such as breakage of the substrate due to foreign matter contamination, and recently, a decompression press device having a simple device structure has been used.

FIG. 4 shows an example of a conventional vacuum press machine. That is, the substrate 3 bonded with the sealing material
0 and 31 are arranged on a surface plate 32, and a partition film 33 is disposed on the substrates 30 and 31.
The pressure is reduced by a vacuum pump 34 so that the substrates 30 and 31 are uniformly pressed at atmospheric pressure and the sealing materials are cured by heaters 35 and 36 disposed above and below the substrates 30 and 31. It is.

[0007]

However, the conventional depressurizing press device presses the substrates 30 and 31 by the atmospheric pressure, so that uniform pressing is possible.
Since the substrates 30 and 31 are pressed at the same time as the inside of the substrate 1 is depressurized, there are two effects, that is, the effect of depressurization and the effect of reducing the distance between the bonded substrates 30 and 31 by pressing.
The air in the cell 37 is discharged from between the substrates 30 and 31. At this time, the passage of the air is only the inlet, and the inlet also becomes smaller at the same time as the interval between the substrates 30 and 31 becomes narrower. Therefore, the pressure in the cell 37 is high, and the air in the cell 37 cuts off the seal and escapes outside the cell due to the decrease in the viscosity of the seal material due to the heat when the seal material is heated and cured. A defect occurs that a part of is cut off. When the seal breaks, the liquid crystal cannot be injected by a vacuum injection method, which is a conventional method, and the yield, that is, the productivity is deteriorated.

FIGS. 5 and 6 are schematic views showing a process for manufacturing a liquid crystal display device using the vacuum press apparatus shown in FIG.

In the bonding step shown in FIG.
0, a thermosetting sealing material (ES-55 manufactured by Mitsui Chemicals, Inc.) in which 2 wt% of a glass fiber of φ5 μm is mixed.
00) is screen-printed so as to have an injection port 41, and resin beads having a diameter of 5 μm are
After dispersing 200 pieces / square mm, the other substrate 31 is bonded. The distance between the pair of substrates 30 and 31 at the time of bonding was 20 μm.

In the sealing material curing step shown in FIG. 6, the bonded substrates 30 and 31 are placed on a glass platen 32, and the pressure between the platen 32 and the silicon resin film 33 is reduced to 0.3 atm. The bonded substrates 30 and 31 were pressed by the silicon resin film 33, and in this state, the sealing material 40 was cured by heating the substrate so that the substrate temperature would be 150 ° C., thereby manufacturing a liquid crystal display element.

The cell gap of the obtained liquid crystal display element is
Interference gap measuring device (MS-20 manufactured by Otsuka Electronics Co., Ltd.)
0), the average cell gap was 5.015 μm.
m, the deviation to it was 0.005 μm, and the gap accuracy was obtained. However, the pressure was applied at the same time as the pressure was reduced, the size of the injection port 41 was reduced, and the pressure in the cell was increased. Seal breakage occurred.

The present invention has been made to solve the above-mentioned problems, and a liquid crystal display element which suppresses a seal breakage occurring when a sealing material is cured, has a high uniformity of a gap over the entire surface of a panel, and is excellent in productivity. It is an object of the present invention to provide a manufacturing method and a manufacturing apparatus.

[0013]

According to a method of manufacturing a liquid crystal display device of the present invention, a sealing material is arranged so that at least one of the substrates has an injection port for enclosing a liquid crystal, and the other substrate is opposed to the sealing material. The pair of substrates bonded with the uncured sealing material is depressurized, the space between the substrates is degassed, the sealing material is cured while pressing the pair of substrates in the degassed state, and the predetermined substrate gap is set. Is formed, and liquid crystal is injected into the cell. As the above sealing material, for example, a thermosetting sealing material is used.

According to the method of manufacturing a liquid crystal display element of the present invention, a pressure reducing step of reducing the pressure of a pair of substrates bonded with an uncured sealing material, and curing the sealing material while pressing the pair of bonded substrates. Since the pressing / curing step is a separate step, in the depressurizing step, it is possible to prevent the injection port of the sealing material from being narrowed by the pressing, and it is possible to efficiently perform deaeration between the substrates. Further, in the pressing / curing step, the degassed substrate is uniformly pressed, and the sealing material can be cured in a state where the pressure between the substrates is low, so that the sealing material is prevented from being cut due to a rise in the pressure in the cell. be able to.

The manufacturing apparatus for a liquid crystal display element according to the present invention comprises: a decompression tank; a partition which divides the inside of the decompression tank into a pair of internal regions; a platen provided in one of the internal regions for mounting a substrate;
A substrate heating device provided in at least one of the internal regions so as to face the surface plate; and a pressure control device for controlling the pressure in each internal region, wherein one internal region has a lower pressure than the other internal region. In this state, the partition wall is bent so as to press the substrate.

According to the apparatus for manufacturing a liquid crystal display element of the present invention, a pair of substrates bonded with an uncured sealing material is placed on a platen in a decompression tank, and the pressure in the decompression tank is reduced by a pressure controller. Thus, degassing between the substrates can be performed. In this degassed state, the pressure in the other internal region is increased by the pressure control device from the one internal region where the substrate is disposed, whereby the partition wall is bent to uniformly press the substrate, and further the substrate is heated by the substrate heating device. The sealing material can be heated and cured in a state where the pressure between the cells is low, and the sealing material can be prevented from being cut due to an increase in the pressure in the cell.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method and an apparatus for manufacturing a liquid crystal display element according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a schematic sectional view of an apparatus for manufacturing a liquid crystal display element. In FIG. 1, reference numeral 22 denotes a main body 13 and an upper lid 14.
The inside of the decompression tank 22 is sealed by an O-ring 15. A partition film 16 made of a silicone resin film is provided in the upper lid 14 to divide the inside of the decompression tank 22 into a pair of internal regions A and B. In the internal area B, a glass surface plate 12 on which a pair of substrates 10 and 11 bonded together with an uncured thermosetting type sealing material is placed. In the internal regions A and B, the glass platen 1 is sandwiched between the substrates 10 and 11 and the glass platen 12.
Heaters 20 and 21 serving as a substrate heating device for curing the sealant are provided so as to face 2. Further, ventilation paths 23 and 24 are opened in the inner regions A and B, and the ventilation paths 23 and 24 are respectively provided with the control valve 1.
It is connected to a vacuum pump 19 via 7 and 18. The ventilation paths 23 and 24, the control valves 17 and 18, and the vacuum pump 19 constitute a pressure control device that controls the pressure in the internal regions A and B.

Then, the internal regions A and B are simultaneously depressurized by the vacuum pump 19 to depressurize the substrates 10 and 11 bonded together with the uncured thermosetting sealing material.
That is, since only pressure reduction is performed without pressing, the inlet of the sealing material is not narrowed, and deaeration between the substrates 10 and 11 can be performed. In this degassed state, the inside of the internal region A is returned to the atmospheric pressure by the control valve 17, so that the pressure difference between the internal region A and the internal region B causes the partition wall film 16 to bend and press the substrates 10 and 11 uniformly. In this pressed state, the sealing material between the substrates 10 and 11 is heated and cured by the heaters 20 and 21.

FIGS. 2 and 3 are schematic views of a process for manufacturing a liquid crystal display element using the manufacturing apparatus of FIG.

In the bonding step shown in FIG. 2, a thermosetting sealing material (ES-550, manufactured by Mitsui Chemicals, Inc.) in which 2 wt% of glass fiber having a diameter of 5 μm is mixed on the substrate 10 is used.
0) 26 is screen-printed so as to have an injection port 27, and resin beads of φ5 μm are
After dispersing by 00 pieces / square mm, the other substrate 11 is bonded. The distance between the pair of substrates 10 and 11 at the time of bonding was 20 μm.

In the sealing material curing step shown in FIG. 3, the bonded substrates 10 and 11 are placed on a glass platen 12, and the internal regions A and B in the decompression tank 22 are simultaneously depressurized to 0.3 atm. The space between the substrates 10 and 11 was evacuated. In this degassed state, the internal area A is returned to the atmospheric pressure, and the substrates 10 and 11 are pressed by the deflection of the partition wall film 16 and heated by the heaters 20 and 21 so that the substrate temperature becomes 150 ° C. Then, the sealing material 26 was cured to produce a liquid crystal display element having a cell gap of 5 μm.

The cell gap of the obtained liquid crystal display element was measured with an interference gap measuring device (MS-200 manufactured by Otsuka Electronics Co., Ltd.).
, The average cell gap was 5.015 μm
And the deviation for it is 0.005 μm and 20 μm.
m can be efficiently degassed by reducing the pressure in the state of the substrate spacing of m
The rise in the pressure inside 5 was small, and there was no breakage of the seal when the seal material 26 was cured by heating.

According to the manufacturing method and the manufacturing apparatus of the liquid crystal display element thus configured, the step of reducing the pressure of the pair of substrates 10 and 11 bonded by the uncured sealing material 26 and the step of reducing the pressure Since the step of pressing / heating the substrates 10 and 11 is a separate step, it is possible to prevent the injection port 27 of the sealing material 26 from being narrowed by the pressing in the decompression step, and to efficiently deaerate the substrates 10 and 11. be able to. In the pressing / heating step, the substrate 1 in a degassed state
0 and 11 are uniformly pressed, and the sealing material 26 can be heated and cured in a state where the pressure between the substrates 10 and 11 is low. The uniformity of the gap is high over the entire surface of the panel, and the sealing material 26 is generated during the heating and curing of the sealing material. And the yield of the seal is improved and the productivity is excellent.

Although the glass platen is used as the platen 12 in the above-described embodiment, similar results can be obtained by using a ceramic platen or a metal platen. Also, in the partition material,
Similar results were obtained when not only silicon resin films but also films having excellent heat resistance such as organic films and metal thin films were used.

Although the heaters 20, 21 are provided so as to sandwich the platen 12, it is also possible to provide only one of the heaters 20, 21.

In the above embodiment, the substrates 10, 1
1, a thermosetting sealing material 26 is disposed between
Although an example of heating and hardening at 0 and 21 has been described, an ultraviolet-curable sealing material may be provided in place of the thermosetting sealing material 26 and cured by irradiating ultraviolet rays. In this case, the partition wall film 16 is made of a material that transmits ultraviolet light, and an ultraviolet irradiation source is provided at that position instead of the heater 20 in the internal region A. If the surface plate 12 is made of a material that transmits ultraviolet light, an ultraviolet irradiation source can be provided at that position instead of the heater 21.

[0028]

According to the method of manufacturing a liquid crystal display element of the present invention, a pressure reducing step of reducing the pressure of a pair of substrates bonded with an uncured sealing material, and a step of removing the sealing material while pressing the pair of bonded substrates. Since the pressing / curing step for curing is a separate step, it is possible to prevent the injection port of the sealing material from being narrowed by the pressing in the decompression step, and it is possible to efficiently perform deaeration between the substrates. In the pressing / curing step, the degassed substrate is uniformly pressed, and the sealing material can be cured in a state where the pressure between the substrates is low, and the uniformity of the gap is high over the entire panel, and the sealing is performed. It suppresses poor seal breakage that occurs at the time of material hardening, improves yield and is excellent in productivity.

According to the apparatus for manufacturing a liquid crystal display element of the present invention, a pair of substrates bonded with an uncured sealing material is placed on a platen in a decompression tank, and the pressure in the decompression tank is reduced by a pressure controller. Thus, degassing between the substrates can be performed. In this degassed state, the pressure in the other internal region is increased by the pressure control device from the one internal region where the substrate is disposed, whereby the partition wall is bent to uniformly press the substrate, and further the substrate is heated by the substrate heating device. The sealing material can be heated and cured in a state where the pressure is low, and the uniformity of the gap is high over the entire panel,
In addition, defective seal breakage that occurs during heat curing of the sealing material is suppressed, yield is improved, and productivity is excellent.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an apparatus for manufacturing a liquid crystal display element according to an embodiment of the present invention.

FIG. 2 is a schematic view of a manufacturing process of the liquid crystal display element in one embodiment of the present invention.

FIG. 3 is a schematic view of a manufacturing process of the liquid crystal display element in one embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a conventional vacuum press machine.

FIG. 5 is a schematic view of a manufacturing process of a liquid crystal display element using a conventional vacuum press.

FIG. 6 is a schematic view of a manufacturing process of a liquid crystal display element using a conventional vacuum press.

[Explanation of symbols]

 A, B Internal area 10, 11 Substrate 12 Glass surface plate 16 Partition film 17, 18 Control valve 19 Vacuum pump 20, 21 Heater (substrate heating device) 22 Decompression tank 23, 24 Vent path 25 Cell 26 Sealing material 27 Inlet

Claims (3)

[Claims] 1. A step of arranging a sealing material on at least one substrate so as to have an injection port for enclosing a liquid crystal, and bonding the other substrate facing each other, and bonding with an uncured sealing material. A step of depressurizing the pair of substrates and degassing between the substrates, and a step of curing the sealing material while pressing the pair of substrates in the degassed state to form cells at a predetermined substrate interval, Injecting a liquid crystal into the cell. 2. The method according to claim 1, wherein the sealing material is of a thermosetting type. 3. A decompression tank, a partition which divides the inside of the decompression tank into a pair of internal regions, a platen provided in the one internal region and on which a substrate is placed, and the platen is provided so as to face the platen. A substrate heating device provided in at least one of the internal regions, and a pressure control device for controlling the pressure in each of the internal regions, wherein the one internal region is at a lower pressure than the other internal region; An apparatus for manufacturing a liquid crystal display element, wherein a partition wall is bent so as to press the substrate.