JPH11305247A - Method and device for injecting liquid crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide simple liquid crystal injecting method and device having high mass-productivity. SOLUTION: The method for fitting a connection jig 1 to a liquid crystal injection port 10 of a liquid crystal display body 9, reducing the pressure of the inside of the body 9 by suction through the jig 1 connected to a vacuum pump through a connection pipe 7 and injecting the liquid crystal to the inside of the body 9 through the jig 1 connected to a liquid crystal storing container 2 by the connection pipe 7 has a process for separating connection between the jig 1 and the connection pipe 7 connected to the jig 1 after supplying the liquid crystal from the container 2 to the jig 1.

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. More specifically, the present invention relates to an improvement in a liquid crystal injection method and an injection device.

[0002]

2. Description of the Related Art A liquid crystal display uses a liquid crystal display in which a liquid crystal layer is provided in a gap between two glass substrates with electrodes, and is a device for displaying characters, numerals, figures, pictures, etc. by the electro-optic effect. Are known. Currently, TN (Twisted N
ematic), STN (SupertwistedNematic), FLC (Ferr
oelectric Liquid crystal), IPS (In-Plane switch)
ing) and other driving modes are known. Such a liquid crystal injection device and a liquid crystal injection method for a liquid crystal display are mainly classified into the following three types.

(1) A liquid crystal display body provided with an inlet and a liquid crystal dish containing liquid crystal are placed in a vacuum-capable container, the vacuum container is evacuated, and then the inlet is brought into contact with the liquid crystal dish. A method of injecting liquid crystal into a liquid crystal display using a pressure difference in the process of returning to atmospheric pressure (Japanese Patent Publication No. 58-49853).

(2) The liquid crystal display body is provided with an exhaust port in addition to the injection port, and a connection jig is provided at the injection port and the exhaust port (JP-A-7-24429).
No. 0), a liquid crystal is injected from an injection port, and at the same time, a liquid crystal is injected into a liquid crystal display by suction from an exhaust port (Japanese Patent Laid-Open No. 8-262461).

(3) A method of attaching a connection jig to an injection port of a liquid crystal display, evacuating the inside of the liquid crystal display, and injecting liquid crystal from the injection port through the same connection jig (Japanese Patent Laid-Open Publication No. Hei. No. 102316).

The method (1) has the following disadvantages, but is a liquid crystal injection method which causes less alignment unevenness and bubbles and has a high product yield. Disadvantages of this method are that the degree of pressure reduction is limited in order to prevent evaporation of the liquid crystal, and furthermore, volatile liquid crystal components cannot be used. In addition, in this method, a liquid crystal dish is used, so that a larger amount of liquid crystal is necessary.Moreover, when the inside of the vacuum vessel is evacuated, foaming is generated from the liquid crystal contained in the liquid crystal dish, and furthermore, a sudden boiling occurs in the vacuum vessel. And the liquid crystal cell is contaminated, and as a result, the amount of liquid crystal used increases and it takes time to clean the vacuum container and the like. Further, as the size of the liquid crystal display increases, there is a disadvantage that the vacuum container itself must be increased in size.

The method (2) has an advantage that a vacuum vessel is not required, but since this method has an exhaust port other than an inlet, not only a step of sealing the exhaust port is required, but also a method of sealing the exhaust port is required. The increase in the number of sealing steps causes a problem of lowering the yield.

The method (3) does not require a vacuum vessel as in the method (2). However, unlike the method (2), a step of sealing an exhaust port is not required, and all liquid crystal injection methods are required. Is the simplest method and device configuration.

[0009]

As described above, the method (3) is the simplest of the conventional liquid crystal injection methods for a liquid crystal display. However, it is difficult to increase the degree of vacuum in the liquid crystal display.
A sealing structure is required to prevent air bubbles from entering the liquid crystal display body, and the connecting jig and the connecting pipe connected thereto are integrated. Therefore, the liquid crystal injection device is occupied while the liquid crystal is being injected into the liquid crystal display, and there is a problem that the operation rate of the liquid crystal injection device is low. For this reason, in order to mass-produce the liquid crystal display, it is necessary to increase the number of liquid crystal injection devices, which has been a factor of increasing the cost of the liquid crystal display.

[0010]

In order to solve the above-mentioned problems, the relationship between the structure of the connection jig and the hermeticity has been intensively studied. As a result, the connection jig is equivalent to the amount of liquid crystal filled in the liquid crystal display. When the inside of the liquid crystal display is evacuated by providing a gap, the gap in the connection jig acts as a suction cup to enhance the sealing performance, and the liquid crystal injection port is provided through the connection jig. When injecting liquid crystal from the connection jig, the liquid crystal filled in the gap inside the connection jig covers the entire liquid crystal injection port, so it is understood that the liquid crystal itself works to enhance the sealing performance, and it is connected with the connection jig and it It has been found that the airtightness can be maintained even when the connection pipe is separated.

According to the liquid crystal injection method of the present invention, a connection jig is attached to a liquid crystal injection port of a liquid crystal display, and the inside of the liquid crystal display is suctioned under reduced pressure through the connection jig connected to a vacuum pump by a connection pipe. Then, a method of injecting liquid crystal into the inside of the liquid crystal display through the connection jig connected to the liquid crystal storage container by a connection pipe, and after the liquid crystal is supplied from the liquid crystal storage container to the connection jig, A step of disconnecting the connection jig from the connection pipe connected to the connection jig is included, and the entire liquid crystal display body is filled with only the liquid crystal supplied to the connection jig.

According to the liquid crystal injecting device of the present invention, the liquid crystal display is composed of a connecting jig, a liquid crystal storage container, a pressure reducing device, a plurality of open / close valves, and a plurality of connecting tubes. A gap corresponding to the amount of the liquid crystal is provided, and the connection jig and the connection pipe connected to the connection jig are configured to be easily attached and detached.

According to the present invention, the step of disconnecting the connection jig from the connection pipe connected to the connection jig immediately after the liquid crystal is supplied from the liquid crystal storage container to the connection jig is introduced. Thus, while the liquid crystal is being injected into the liquid crystal display, no liquid crystal injection device is required, and the liquid crystal injection device can shift to a step of supplying liquid crystal to the next liquid crystal display. Therefore, for mass production of liquid crystal displays, there is an effect that the number of liquid crystal injection devices does not increase and the injection time per one increases with an increase in the number of liquid crystal displays to be injected. This can contribute to cost reduction of the liquid crystal display.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings.

[0015]

FIG. 7a shows an overall view of a liquid crystal display. The size of the liquid crystal display 9 is 270 mm (one long side) x 20
A transparent glass substrate having a thickness of 1.1 mm, a thickness of 1.1 mm and a polished surface was used. The amount of liquid crystal filled in the liquid crystal display is about 0.2 ml. A common electrode, a signal electrode, a pixel electrode, and the like were formed on these substrates, and an alignment film was formed on the outermost surface. In this embodiment, polyimide is adopted as the alignment film, and is coated with a printing machine and has a thickness of 0.07 to 0.1 after baking.
m. After that, an alignment process was performed on the surface of the alignment film to align the liquid crystal. The alignment treatment was performed using a rubbing machine and a buff cloth made of rayon as a rubbing roll. For bonding the upper and lower substrates, an appropriate amount of polymer beads was mixed in a sealant (epoxy resin), and printed on the substrate so as to have the seal 12 of FIG. 7 using a seal mask. Thereafter, the sealing agent was temporarily cured, and the upper and lower substrates were combined. Then, while pressing the two substrates using a press,
The sealant was cured. In the panel surface, spherical polymer beads are sandwiched between substrates, and a gap is set to 6.
0 μm. The rubbing angle of this liquid crystal display was set to 45 degrees with respect to the short side, and the liquid crystal display was arranged orthogonally between the upper and lower substrates. FIG. 7b shows an enlarged view of the injection port portion of the liquid crystal display.
The width (L1) of the liquid crystal injection port 10 is 30 mm. Then, an ultraviolet curing agent is applied from the outside to the cut surfaces of the two glass substrates on both sides of the liquid crystal injection port on the short side of the liquid crystal display so as to come into contact with the ends of the sealing portion, and is cured by curing. Fifteen
Was provided. The length (L2) of the flattening protective film 15 is 10 mm. This flattening protective film is for shortening the operation time for attaching the connection jig to the liquid crystal display, and not only the positioning is facilitated by the presence of the flattening protective film, but also
There is also an effect of improving adhesion. As shown in FIG. 8, by devising the sealing structure, the same effect can be obtained even without the flattening protective film. FIG. 8A shows a structure in which the width of the sealant at the inlet is increased. FIG. 8B shows a structure in which the sealing agent at the injection port is folded back to the short side. FIG. 8C shows a structure in which the sealing agent at the injection port portion is brought closer to the short side. FIG. 8D shows a structure in which the sealant is brought close to the short side only near the injection port.

The liquid crystal injection device used in this embodiment will be described with reference to FIG. The liquid crystal injection device includes a connection jig 1, a liquid crystal storage container 2, two pressure reducing devices (3, 3a) having a rotary pump, a leak valve, and a Pirani gauge, four open / close valves (4, 5, 5a, 6), 9 Connection pipes (7, 7a,
7b, 7c, 7d, 7e, 7f, 7g, 7h) and a liquid crystal recovery container 11. The connection jig 1 is connected to the liquid crystal storage container 2 and the connection pipe (7, 7a, 7b) via the open / close valve 4. Be linked. On the other hand, the connection jig 1 is connected to the liquid crystal recovery container 11 via connection valves (7, 7c, 7d) via an opening / closing valve 5. The liquid crystal storage container 2 is connected to the pressure reducing device 3 via connection valves (7e, 7f) via an opening / closing valve 6. The liquid crystal recovery container 11 is connected to the connection pipe (7 g,
7h), it is connected to the pressure reducing device 3a.

As shown in FIG. 2C, the connection jig 1 is made of silicone rubber in a U-shape, and the depression of the connection jig is a portion into which the injection port of the liquid crystal display is inserted. The width (L3) was 1.8 mm, which was smaller than the thickness of the liquid crystal display to improve the adhesion. Fig. 2d shows the inside of the connection jig 1.
As shown in FIG. 2, a space (liquid crystal pool) 14 for storing liquid crystal is provided. This gap gives the connection jig an effect like a suction cup. The connecting jig 1 is provided with a cylindrical connecting pipe connecting portion 13 for connecting to the connecting pipe, and penetrates to the bottom side. FIG. 2A shows a state in which a connection jig is attached to the liquid crystal display body, and also shows a positional relationship with a connection pipe 7 to be connected. The distal end of the connecting pipe has a tapered structure so that it can be brought into close contact with the connecting pipe when inserted into the connecting pipe connecting portion 13, and the connection can be easily released. FIG. 2B illustrates a state where the connecting pipe is attached to the connecting pipe connecting part 13.

When such a liquid crystal injection device is used, liquid crystal injection into a liquid crystal display is divided into an injection preparation operation and an injection operation. First, the injection preparation operation will be described with reference to the flowcharts of FIGS. Before the liquid crystal injection operation, all open / close valves should be closed (Step 1).
01). A liquid crystal storage container 2 having an inner volume of 100 ml was filled with 50 ml of a liquid crystal 8 of ZLI1132 manufactured by Merck and sealed. In step 102, the decompression device 3 connected to the liquid crystal storage container
The rotary pump was activated. In step 103, the open / close valve 6 is opened, and it is confirmed that the pressure in the liquid crystal storage container has been reduced to 10 Pa while monitoring the Pirani vacuum gauge attached to the pressure reducing device 3 (step 104).
Then, the opening / closing valve 6 was closed. Thereafter, the rotary pump was stopped (step 106). In step 107,
The leak valve attached to the pressure reducing device 3 was opened. In step 108, the open / close valve 6 is opened, and it is confirmed that the pressure in the liquid crystal storage container has reached 80,000 Pa (atmospheric pressure is about 100,000 Pa) (step 109), and the open / close valve 6 is closed (step 110). . In step 111, the leak valve attached to the pressure reducing device 3 was closed. These series of operations are operations for removing dissolved air in the liquid crystal, and may be performed once while the liquid crystal in the liquid crystal storage container is present.
Next, in step 112, the rotary pump of the decompression device 3a connected to the liquid crystal collection container was operated. Step 1
At 13, the open / close valve 5a is opened, and it is confirmed that the pressure in the liquid crystal collection container is reduced to 1 Pa while monitoring the Pirani vacuum gauge attached to the pressure reducing device 3a (step 114).
The injection preparation operation was completed.

Next, FIGS. 1 and 4 show the injection operation.
This will be described with reference to the flowchart of FIG. As shown in FIG. 2A, a liquid crystal display 9 in which the connection jig 1 is connected to the injection port 10 is prepared in advance. In step 201, the connecting pipe 7 is inserted into the connecting pipe connecting portion 13 of the connecting jig 1 and connected. In step 202, the open / close valve 5 is opened. In step 203, while monitoring the Pirani vacuum gauge, it was confirmed that the pressure in the liquid crystal display was reduced to 5 Pa.
At 04, the on-off valve 5 was closed. In step 205, the open / close valve 4 was opened. After confirming in step 206 that liquid crystal starts to be injected into the connection jig 1 and the liquid crystal display, in step 207, the open / close valve 4 was closed. In step 208, the connection pipe 7 was removed from the connection jig 1. In step 209, the liquid crystal remaining in the connection pipes (7a, 7c) was recovered in the liquid crystal recovery container at a negative pressure by opening the on-off valve 5. In step 210, it was confirmed that the liquid crystal was collected in the liquid crystal storage container, and in step 211, the on-off valve 5 was closed. A series of liquid crystal injection operations was completed. This series of liquid crystal injection operations requires about 10 minutes. After confirming that it is the last liquid crystal display to be injected in step 212, in step 213, the rotary pump of the pressure reducing device 3a is stopped. Finally, in step 214, the leak valve of the decompression device 3a is opened to end the injection operation.

After removing the connection pipe 7 from the connection jig 1 connected to the liquid crystal display, as shown in FIGS. 5A, 5B and 5C, a gap (liquid crystal) inside the connection jig 1 is formed. The liquid crystal stored in the pool 14 naturally fills the liquid crystal display due to the effect of the pressure difference. 5a, 5b, and 5c show the state of filling of the liquid crystal after 10 minutes, 45 minutes, and 85 minutes, respectively. It took 90 minutes for the liquid crystal to completely fill the liquid crystal display. Since the amount of liquid crystal filled in the liquid crystal display is about 0.2 ml, the connection jig 1
It is sufficient that the gap inside is not less than 0.3 ml. Further, when two liquid crystal injection ports having a width of 30 mm were provided in the upper short side of the liquid crystal display and liquid crystal was injected, the liquid crystal injection time was reduced to 60 minutes. In addition, by heating the connection jig from room temperature (25 ° C.) to 40 ° C. with a ribbon heater, the viscosity of the liquid crystal was reduced, and the liquid crystal injection time was further reduced to 45 minutes.

In this embodiment, the connection between the connection jig and the connection pipe is
As shown in FIG. 2A, the connecting pipe has a tapered distal end so that the connecting pipe is in close contact.
The liquid crystal injection operation can be performed even if a ring is used or a structure in which a ring is used. In addition, if it is electrically automatically attached and detached, the injection operation time can be reduced.

In this embodiment, as shown in FIG.
Although the liquid crystal collection container 11 is used, the pressure in the liquid crystal storage container is reduced by opening the valve 4, so that even if the liquid crystal is collected in the liquid crystal storage container, the same liquid crystal injection operation as in the present embodiment is performed. Can be implemented. In this case, since the liquid crystal collection container 11 is unnecessary, the connection pipe 7d is connected to the pressure reducing device 3a from the open / close valve 5.
It may be connected directly to. In addition, 3 and 3a are used as pressure reducing devices
And the same liquid crystal injection operation as in this example could be performed.

FIG. 6 is a diagram showing a state in which a series of liquid crystal injection operations is repeated 10 times. It takes 10 minutes for a series of liquid crystal injection operations, and since the filling time of the liquid crystal in one liquid crystal display element is 90 minutes, when the series of liquid crystal injection operations to the tenth liquid crystal display element is started, The filling of the first liquid crystal display element has already been completed. The time from the start of the liquid crystal injection operation to the first liquid crystal display element to the filling of the liquid crystal in the tenth liquid crystal display element was 190 minutes in total. Therefore, when a series of liquid crystal injection operations is repeated 10 times, the liquid crystal filling time per liquid crystal display element is 19 minutes.
After the injection is completed, the connection jig 1 is detached from the liquid crystal display 9, and
After cleaning, it is reused.

In this embodiment, when the number of liquid crystal injections increases, the liquid crystal filling time per one liquid crystal display element becomes shorter. For example, when a series of liquid crystal injection operations is repeated 30 times, the liquid crystal filling time per one liquid crystal display is further reduced to 13 minutes.

Comparative Example A liquid crystal display and a liquid crystal injecting device similar to those in the above embodiment were used, but a series of liquid crystal injecting operations were changed as follows.

After the liquid crystal is supplied from the liquid crystal storage container to the connection jig, the liquid crystal is filled in the entire liquid crystal display body while maintaining the connection between the connection jig and the connection pipe connected to the connection jig. A conventional liquid crystal injection method was performed. It took 100 minutes to fill one liquid crystal display with liquid crystal, including the step of reducing the pressure inside the liquid crystal display. This operation was repeated 10 times, and the time spent in this repeated operation was 1,000 minutes, the liquid crystal filling time per liquid crystal display was 100 minutes, and the method was not particularly dependent on the number of liquid crystal displays. Met. If it is attempted to fill 10 liquid crystal displays with liquid crystal within the same time as in the above embodiment, a total of 5 liquid crystal injection devices are required.

[0027]

According to the present invention, the speed of liquid crystal injection can be increased.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a liquid crystal injection method and a liquid crystal injection device according to the present invention.

FIG. 2 is an explanatory view of a connection jig according to the present invention.

FIG. 3 is a flowchart of a liquid crystal injection preparation operation according to the present invention.

FIG. 4 is a flowchart of a liquid crystal injection operation according to the present invention.

FIG. 5 is a diagram showing a liquid crystal filling state of a liquid crystal display according to the present invention.

FIG. 6 is an explanatory diagram of a liquid crystal injection method according to the present invention.

FIG. 7 is an explanatory diagram of a liquid crystal display used in the present invention.

FIG. 8 is an explanatory diagram of a seal portion of the liquid crystal display used in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Connection jig, 2 ... Liquid crystal storage container, 3, 3a ... Decompression device, 4, 5, 5a, 6 ... Opening / closing valve, 7, 7a, 7b,
7c, 7d, 7e, 7f, 7g, 7h Connection pipe, 8 Liquid crystal, 9 Liquid crystal display, 10 Liquid crystal injection port, 11 Liquid crystal recovery container, 12 Seal part, 13 Connection pipe connection part, 14 …
Liquid crystal pool, 15: flattening protective film.

Claims (2)

[Claims] 1. A connection jig is attached to all the liquid crystal injection ports of a liquid crystal display having at least one or more liquid crystal injection ports, and the liquid crystal is connected to the liquid crystal via a connection pipe connected to a vacuum pump by a connection pipe. A method of injecting liquid crystal into the inside of a liquid crystal display via the connection jig connected to the liquid crystal storage container by a connecting pipe after suctioning the inside of the display under reduced pressure. After the liquid crystal is supplied, the method includes a step of disconnecting the connection jig from the connection pipe connected to the connection jig, and the entire liquid crystal display body is entirely filled with the liquid crystal supplied to the connection jig. A liquid crystal injection method characterized by filling. 2. An apparatus for injecting liquid crystal into a liquid crystal display having at least one liquid crystal injection port, comprising: a connection jig, a liquid crystal storage container, a pressure reducing device, a plurality of open / close valves,
It is composed of a plurality of connection pipes, the connection jig has a gap corresponding to the amount of liquid crystal filled in the liquid crystal display, and the connection jig can be attached to and detached from the connection pipe connected to the connection jig. Characteristic liquid crystal injection device.