JPH01114823A - Manufacturing method of liquid crystal display device - Google Patents

Abstract

PURPOSE:To uniformly such and seal and adhesive agent into a liquid crystal cell in a shorter time than usual by constituting the title method of a process for sucking a second adhesive agent of a roughly prescribed quantity into the liquid crystal cell from a liquid crystal injection port, and a process for hardening the second adhesive agent. CONSTITUTION:After an outflow of a liquid crystal from a liquid crystal injection port has stopped in a state that a liquid crystal cell is pressed, an adhesive agent 4 for sealing is applied to the liquid crystal injection port 3 of the liquid crystal cell. Also, pressure bodies 5a, 5b are eliminated, and the adhesive agent 4 for sealing is sucked into the liquid crystal cell 6 by an elastic deformation, etc. of warp of a substrate. As a result of having studied experimentally a heating temperature extending from a room temperature to about 120 deg.C, it is decided that viscosity of the adhesive agent used for sealing drops from about 100 deg.C and the adhesive agent invades instantaneously and it is not suitable for a mass production. As for the time t2sec required for sucking this adhesive agent for sealing, it is decided experimentally that it is t2=about 20 in case of the liquid crystal cell of 6mum thickness of the liquid crystal layer and about 18mm<3> volume.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a liquid crystal display device for displaying characters or images, and more particularly to a method for manufacturing a liquid crystal display device for displaying characters or images. The present invention relates to a method for manufacturing the device.

BACKGROUND ART As a conventional technique, there is a method for manufacturing a liquid crystal display device having a structure as shown in FIG. 8, as disclosed in, for example, Japanese Unexamined Patent Publication No. 60-24518.

FIG. 8a is a sectional view of a liquid crystal cell, and FIG. 8a is a plan view of the liquid crystal cell. In these figures, 19 and 20
21 is a flexible substrate made of a plastic film or sheet, 21 is an adhesive layer provided around the substrate, and 22 is a cell thickness control material made of various materials such as glass fiber, polymer fine particles, etc. , film, etc., but it is said that the use of polymer fine particles is particularly preferable. 23 is a space in which the liquid crystal is to be accommodated. When injecting liquid crystal into a liquid crystal cell with this structure from the liquid crystal injection port 24, the liquid crystal injection method is, for example, by leaving the liquid crystal cell in a vacuum system to reduce the pressure inside the cell, and then injecting the liquid crystal into the liquid crystal injection port of the cell. is introduced into the liquid crystal, the liquid crystal is brought to atmospheric pressure, and using the pressure difference between the liquid crystal pressure and the internal pressure of the liquid crystal cell and the capillary phenomenon, the liquid crystal is injected into the liquid crystal cell so that a surplus liquid is generated. Fill it up. When the liquid crystal cell is filled with liquid crystal, the surface of the liquid crystal cell is uniformly pressurized to remove excess liquid from the liquid crystal injection port of the liquid crystal cell to the outside of the system, and then the liquid crystal injection port is sealed. In this case, the liquid crystal cell surface can be pressurized by any device with a smooth surface such as a roller or a press plate, and the liquid crystal injection port of the cell can be sealed using an ultrasonic welder or the like. This means that it is possible.

However, since this method seals the liquid crystal cell under pressure, it requires a considerable amount of time to suck the adhesive used for sealing into the liquid crystal cell, and is not considered suitable for mass production. When sealed for a short time, the amount of adhesive sucked into the liquid crystal cell is small, which seems to be disadvantageous in terms of reliability in terms of moisture resistance and image quality.

According to another method, a liquid crystal cell is sandwiched between plates with smooth surfaces such as glass plates and fixed by pressure, and then liquid crystal is injected into the liquid crystal cell from a liquid crystal injection port of the liquid crystal cell. When injecting liquid crystal, since both sides of the liquid crystal cell are suppressed by smooth surfaces, injection is carried out in just the right amount. Therefore, after injecting liquid crystal into the cell, it is only necessary to seal the injection port as is. It is. According to this method, there is no change in the volume of the liquid crystal when the adhesive necessary for sealing is sucked into the panel, so the adhesive applied to the liquid crystal injection port is only sucked into the liquid crystal cell by capillary action, and the adhesive is absorbed into the liquid crystal cell. It has the disadvantage that it requires a considerable amount of inhalation time and is not suitable for mass production.

Furthermore, other conventional techniques include, for example, Japanese Patent Application Laid-Open No. 59-2
As shown in Japanese Patent No. 18424, there is a method for manufacturing a liquid crystal display device as shown in FIG.

FIG. 9a is a sectional view showing the first manufacturing method, and FIG. 9 is a sectional view showing the second manufacturing method, and a plan view of an adhesive reservoir according to the manufacturing method.

In FIG. 9a, 26 is a squeegee, 26 is a screen,
27 is a pattern of the screen 26, 28 is a liquid crystal cell, 2
9 is a sealing opening of the liquid crystal cell, 30 is a printing stage, and 31 is a sealing adhesive. The screen used was 50 mesh, the emulsion thickness was 40 μm, and the printing conditions were a squeegee pressure of approximately 5 to 9.
7 m, and the squeegee speed was approximately smm/sea. At this time, when approximately 200 poise of resin was used as the sealing adhesive, a liquid crystal cell was created with a uniform cell thickness and a moderate amount of sealing adhesive penetrating into the cell injection port. . According to another second manufacturing method, as shown in FIG. 9, 25 is a squeegee, 32 is a screen without a pattern, 28 is a liquid crystal cell, 29 is a sealing opening of the liquid crystal cell,
30 is a printing stage, 33 is an adhesive reservoir 33' for sealing.
This is a film with a

As shown in FIG. 9, a screen 32 without a pattern
A polyester film 33 with an adhesive reservoir 33' for sealing is placed under it, and the adhesive layer 33 is
When the adhesive was collected in ' and the same procedure as in the above example was carried out,
A cell similar to that of the above example was created. However, according to this method, the liquid crystal will move as the squeegee moves, but the disadvantage is that the gap between the liquid crystal cells cannot be accurately drawn due to the traces of the squeegee's movement, such as restoring the warpage of the glass substrate and elastic deformation of the spacer. Furthermore, it is necessary to make the speed at which the liquid crystal flows out from the liquid crystal inlet of the liquid crystal cell almost equal to the moving speed of the squeegee, but this is extremely difficult, and judging from the configuration, the squeegee does not move the liquid crystal cell. As the adhesive is applied to the liquid crystal injection port at the same time as the liquid crystal passes through, the amount of sealing adhesive sucked into the liquid crystal cell is small, and it is inferior in terms of moisture resistance, resulting in a markedly poor image quality. This seems to have the drawback of poor reliability.

Problems that the invention sought to solve As described above, in the conventional method, the adhesive applied to the liquid crystal injection port of the liquid crystal cell is sucked into the liquid crystal cell by capillary action, and it takes time for the adhesive to be sucked into the liquid crystal cell. Not only is it unsuitable for mass production, but if time efficiency is emphasized, the amount of adhesive absorbed into the liquid crystal cell decreases, which adversely affects image quality due to moisture absorption, etc., and has the drawbacks of reliability.
It is difficult to completely seal the liquid crystal.

The present invention has been made in view of the above points, and it is possible to manufacture a liquid crystal display device suitable for mass production with a simple configuration, and to perform complete liquid crystal sealing.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides liquid crystals by injecting and sealing liquid crystal into a liquid crystal cell consisting of a set of substrates with electrodes and a first adhesive interposed between the substrates. When manufacturing a display device, a step of injecting the liquid crystal into the liquid crystal cell in a vacuum without pressurizing the liquid crystal cell at room temperature, and a step of pressurizing the liquid crystal cell with a pressurizing body in a heated state, a step of standing still for t1 seconds under pressure in a heated state; a step of applying a second adhesive to the liquid crystal injection port of the liquid crystal cell in the heated state; and a step of applying the second adhesive to the liquid crystal cell in the heated state. It is characterized by comprising the steps of: allowing a predetermined amount of the second adhesive to be sucked into the liquid crystal cell from the liquid crystal injection port by leaving the pressure body still for a second after removing the pressure body; and curing the second adhesive. The present invention provides a method for manufacturing a liquid crystal display device.

Effect: According to the manufacturing method described above, after liquid crystal is injected into the liquid crystal cell at room temperature without applying pressure, the liquid crystal cell is pressurized with a pressurizing body in a heated state to remove excess liquid crystal from the outside of the liquid crystal cell, and then the liquid crystal cell is sealed. Apply the adhesive to the liquid crystal injection port, remove the pressurizing body of the liquid crystal cell, and inhale a certain amount of adhesive from the liquid crystal injection port into the liquid crystal cell by elastic deformation of the glass substrate of the liquid crystal cell.
It cures, has an extremely short penetration time, and is easy to control the amount of adhesive, making it suitable for mass production.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings. The basic structure of a liquid crystal display device is a combination of a polarizing plate and a panel filled with liquid crystal between a pair of electrode substrates. It displays shading based on the difference in refractive properties. A liquid crystal display device manufactured based on the manufacturing method of the present invention is shown in FIGS. 6 and 7.

In FIG. 6, the liquid crystal display device includes a front glass plate 9 having a transparent electrode 7 and an alignment film 8 thereon, a TPT element (transistor element composed of a thin film transistor and used for switching the voltage applied to the pixel electrode) part 1o, and Pixel section 1
1 and a liquid crystal display substrate 13 on which an alignment film 12 is attached, there is a sealant 14 mixed with a predetermined spacer in the periphery. 16, a large number of spacers 16 are present.

Polarizing plates 17 and 18 are attached to both sides of the front glass plate 9 and the liquid crystal display substrate 13.

FIG. 7 shows the structure on the substrate 13 side, where G is TPT.
The gate electrode of the device, I is an insulating film, the channel active region made of amorphous silicon, and M are the source and drain electrodes.

Here, a method for manufacturing a liquid crystal display device according to the present invention will be described. As described above, in the liquid crystal display device of the present invention, a liquid crystal cell is assembled using a pair of glass plates and an adhesive interposed between them, and a part of the adhesive is released within the liquid crystal cell to form a liquid crystal injection port. It is manufactured by injecting and sealing liquid crystal.

Also, warping of the glass substrate occurs due to the formation of gelatin films, transparent electrodes, metals, insulating films, alignment films, etc. on the glass substrate, but when observing the assembled liquid crystal cell under a single wavelength light source, the liquid crystal It is known that the area near the center of the cell has a medium height of about 1 μm. In this state, liquid crystal is injected into the liquid crystal cell at room temperature in a vacuum without pressurizing the liquid crystal cell.

It has been experimentally found that it takes about 30 minutes to fill a liquid crystal cell with a gap thickness of about eμm and a volume of about 18 m111'' by applying pressure to the liquid crystal cell. It has been found that if liquid crystal is injected into a liquid crystal cell in a vacuum while the liquid crystal cell is in a medium-high state, the liquid crystal will be filled within 6 minutes.Therefore, this method of manufacturing a liquid crystal display device is advantageous in terms of time and can improve the efficiency of mass production. Fig. 1a is a plan view of the vicinity of the liquid crystal injection port 3 of the liquid crystal cell 2 filled with the liquid crystal 1.Fig. FIG. 4 is a plan view of a liquid crystal cell sealed with 4. FIG.

In addition, by injecting the liquid crystal at room temperature, the volatile components contained in the liquid crystal in a vacuum are less likely to evaporate than when heated, and the viscosity does not change, so it can be reused by passing it through a filter. It is available and cost-effective.

Next, the liquid crystal cell filled with liquid crystal was pressurized using a pressurizing body to correct the warpage of the liquid crystal cell and obtain a uniform gap between the liquid crystal cells. This will be explained based on FIG. 2. 40 for a liquid crystal cell with a liquid crystal layer thickness of 6 μm and a volume of about 1'am3.
It was confirmed that the outflow of liquid crystal with a diameter of about 2 minutes stopped under heating conditions of 'C. At room temperature, it took about 5 minutes. This seems to be because heating the liquid crystal cell lowers the viscosity of the liquid crystal, making it easier to flow out. The material of the pressurizing body 5 used here may be a metal such as aluminum or stainless steel, a rigid body such as a resin such as Teflon, or a flexible structure such as silicone rubber. However, in the case of a rigid body, if hard dust or glass chippings are present between the liquid crystal cell 6 and the pressurizing body 5, there is a problem that local gap defects will occur within the liquid crystal cell. Therefore, it is necessary to take measures such as using a pressurizing body made only of silicone rubber, or using silicone rubber only for the screen portion of the liquid crystal cell and surrounding it with metal such as aluminum. When we experimentally used a pressurizer to press the screen area of a liquid crystal cell using silicone rubber, we were able to obtain a uniform thickness of the liquid crystal layer, and there were no concerns about defects and the image quality was good.

The pressurizing body of the present invention is made of a rigid member 5b made of aluminum or the like and a flexible member 5b made of silicone rubber, and a hollow is formed inside the aluminum and silicone rubber is fitted therein.

FIG. 3 shows a sectional view of a pressurizing body according to an embodiment of the present invention. Third
As shown in Figure B, one side of the flexible structure member made of silicone rubber A is processed to be flat, and when it comes into contact with the surface of aluminum C, which has a hollow inside, it becomes difficult to peel off. Further, a conical convex portion d is provided on the other surface,
Figure 3 shows a state in which a liquid crystal cell is sandwiched between pressurizing bodies and pressurized. When brought into contact with the liquid crystal cell 6, an air layer e is formed between the convex parts, and the silicone rubber easily peels off from the liquid crystal cell. . By further applying pressure, the convex portion deforms and applies uniform pressure to the liquid crystal cell, making it possible to ideally press the liquid crystal cell.

In addition, while the liquid crystal flows out from the liquid crystal inlet after pressurizing the liquid crystal cell with the pressurizing body, in the pressurized state, the cross-sectional area of the liquid crystal inlet, the volume of the liquid crystal cell, the warping of the substrate, and the pressing force due to the pressurizing body It is known that the standing time of 11 seconds varies due to factors such as this. The pressing force was experimentally increased from tskg to 20kq.
The size of the liquid crystal injection port is from 1 mm to 3 m.
The liquid crystal outflow time was measured for about 2 minutes when the substrate warpage was approximately 6 μm larger than the gap between the liquid crystal layers. However, in a liquid crystal cell having - liquid crystal injection ports, the relationship between the liquid crystal outflow time and the pressing force when the cross-sectional area of the liquid crystal injection port is approximately 2 × 10-2 is shown in Figure 4a, and the liquid crystal outflow The relationship between time and substrate warpage is shown in Figure 4. As a condition, the pressing force is skg, and a pressure of about 0.6 kq/- is applied to the liquid crystal cell. Under this magnitude of pressure, when a pressurizing body with a combination of a rigid body and a flexible structure was used, defects such as local gap defects in the liquid crystal cell, which would be fatal to image quality, did not occur. The shaded area shows the range of measured values obtained in the experiment. Furthermore, when there are multiple liquid crystal injection ports, the liquid crystal outflow time is thought to be shortened.

Next, after the liquid crystal stops flowing out from the liquid crystal injection port while the liquid crystal cell is pressurized, a sealing adhesive is applied to the liquid crystal injection port of the liquid crystal cell. Further, the pressurizing body is removed and the sealing adhesive is sucked into the liquid crystal cell by elastic deformation of the substrate. When the heating temperature was experimentally investigated from room temperature to about 120'C, it was found that the viscosity of the adhesive used for sealing decreased from about 100C and it penetrated instantly, making it unsuitable for mass production.

It has been experimentally found that a temperature between room temperature and about 80° C. is suitable for inhaling the sealing adhesive into the panel with good control.

It has been experimentally found that the time t2 seconds required for inhaling the sealing adhesive is approximately 20 in a liquid crystal cell in which the liquid crystal layer has a thickness of 6 μm and a volume of approximately 18 m1113.

In addition, in the case of a large board of size 4, the thickness of the liquid crystal layer is 6μ.
In the case of m, the sealing adhesive was inhaled at 1θ seconds. In addition, in the case of a small substrate, the warpage is about 1 μm and the thickness of the liquid crystal layer is 6 μm.
It took about 46 seconds for a liquid crystal cell with a volume of s mm3.

From the above actual and experimental results, the standing time t2 from removing the pressurizing body of the liquid crystal cell to curing the sealing adhesive is 0≦t2≦
It seems to be in the range of 60.

In Figure 5 a, the thickness of the liquid crystal layer is 6 μm and the volume is 18 ml.
Figure 6 shows the relationship between the time for the sealing adhesive to be sucked into the liquid crystal cell and the warping of the substrate in case 13, and Figure 6 shows the relationship between the time for the sealing adhesive to be sucked into the liquid crystal cell and the pressing force. Show the diagram. It can be seen that the above relationship is satisfied. The shaded area shows the range of measured values obtained in the experiment.

Finally, in curing the sealing adhesive, it is necessary that it harden instantly to ensure sufficient time management after the pressure of the liquid crystal cell's pressurizing body is released. An ultraviolet curable resin was used as a material that satisfies these conditions. When an ultraviolet curing resin that completely cures under ultraviolet irradiation conditions of 26 mW for 180 seconds was used experimentally, sufficiently good results were obtained.

As methods for heating a liquid crystal cell, there are heat transfer heating using a heater, radiation heating using a heating furnace, and radiation heating using infrared rays. Experimentally, we tried various methods to maintain the temperature at 40'C and measured the temperature by fixing a thermocouple on the surface of the liquid crystal cell. The surface temperature of the liquid crystal cell could be maintained at 40'C by increasing the set temperature to 60'C. In addition, in radiation heating using a heating furnace, the temperature of the surface of the liquid crystal cell could be maintained at 40'C by setting the heating furnace at 40°C and heating for 10 minutes or more.

In the case of radiant heating using infrared rays, it was found that when a 1 oow infrared lamp was placed at a height of 30 cm from the liquid crystal cell and irradiated with irradiation, the temperature reached 40° C. in about 5 minutes.

When a liquid crystal display device was manufactured experimentally through the above steps using a simple heating furnace, a liquid crystal display device with a uniform liquid crystal layer thickness and good image quality was obtained.

As described above, according to this embodiment, the liquid crystal injection time can be shortened compared to the conventional method, and the sealing adhesive can be sucked and sealed uniformly into the liquid crystal cell in a shorter time than the conventional method, and the liquid crystal layer of the liquid crystal display device can be uniformly formed. It was found that the film has the advantage of being able to maintain a certain thickness and providing good image quality.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) The uniform thickness of the liquid crystal layer of a liquid crystal display device can be maintained to a degree that causes no practical problems.

(2) Liquid crystal sealing of a liquid crystal display device can be performed stably and uniformly in a relatively short time.

(3) A liquid crystal display with excellent display quality can be obtained.

(4) A large amount of processing can be performed relatively stably.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a liquid crystal display device manufactured by the method of manufacturing a liquid crystal display device of the present invention, FIG. 2 is a perspective view showing the method of manufacturing a liquid crystal display device of the present invention, and FIG. 3 is a configuration of a pressurizing body. FIG. 4 is a relationship diagram showing liquid crystal outflow time, FIG. 6 is a relationship diagram showing sealant suction time, and FIG. 6 is a liquid crystal display manufactured using the method for manufacturing a liquid crystal display device of the present invention. 7 is a sectional view of the TPT element part and pixel part of the same liquid crystal display device, FIG. 8 is a plan view showing a method of manufacturing a liquid crystal display device in a conventional example, and FIG. 9 is another conventional example. FIG. 2 is an explanatory diagram showing a manufacturing method. 1...Liquid crystal, 2...Liquid crystal cell, 3...
...Liquid crystal injection port, 4...Sealing adhesive,
sa, 5b... Pressure body, 6... Liquid crystal cell, 7... Transparent electrode, 8... Alignment film,
9... Front glass, 10... TFT element section, 11... Pixel section, 12... Alignment film, 13... Liquid crystal display Board for, 14...
・Sealant, 16...Liquid crystal, 1θ...
Spacer, 17...Polarizing plate, 1 day...
Polarizing plate, 19.20...Flexible substrate, 21...
... Adhesive layer, 22 ... Cell thickness control material, 2
3... Space to accommodate the liquid crystal, 24...
・Liquid crystal injection port, G...Gate electrode, engineering...
...Insulating film, M...Channel active part made of amorphous silicon, M...Source/drain electrode, 25...Squeegee, 2θ...
Screen, 27...Screen pattern, 2
8...Liquid crystal cell, 29...Sealing port of liquid crystal cell, 30...Printing stage, 31...
...Sealing adhesive, 32...No pattern screen, 33...Film, 33'...
・Adhesive for sealing. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure ((L) Figure 2 Figure 4 Figure 5 ((L) Dry 1 stripe Wood Figure 8 (L) Space for LCD 1

Claims (2)

[Claims] (1) When manufacturing a liquid crystal display device by injecting and sealing liquid crystal into a liquid crystal cell consisting of a pair of electrode-equipped substrates and a first adhesive interposed between the substrates, the liquid crystal cell is pressurized at room temperature. a step of injecting the liquid crystal into the liquid crystal cell in a vacuum without heating; a step of pressurizing the liquid crystal cell with a pressure body in a heated state; and a step of leaving the liquid crystal cell still in the heated and pressurized state for a predetermined period of time. , a second liquid crystal injection port is inserted into the liquid crystal injection port of the liquid crystal cell in a heated state.
The pressurizing body of the liquid crystal cell is removed in a heated state, and the pressure body is left standing for a predetermined period of time, and a substantially constant amount of the second adhesive is applied from the liquid crystal injection port into the liquid crystal cell. A method for manufacturing a liquid crystal display device, comprising the steps of: inhaling the second adhesive; and curing the second adhesive. (2) The pressurizing body consists of a rigid body and a member with a flexible structure, and the rigid body has a boring, and the member with the flexible structure has a first surface that is flat and a second surface that has a predetermined number of surfaces. The device has a convex portion, and the convex portion is formed in a conical shape and at a predetermined interval, the second surface is a surface that comes into contact with the liquid crystal cell, and the first surface is a surface that contacts the middle of the rigid body. It is the surface that comes into contact with the bore,
2. The method of manufacturing a liquid crystal display device according to claim 1, wherein the pressurizing body pressurizes the liquid crystal cell after the liquid crystal is injected.