JPH0421850B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for injecting liquid crystal materials used in various display devices into liquid crystal cells.

As is well known, liquid crystals are sensitive to external electric fields, magnetic fields,
It is widely used in display devices for characters, symbols, and images because its optical properties easily change when a stimulus such as heat is applied. Most liquid crystal materials are liquid organic compounds, and changes in their optical properties occur due to changes in the orientation of the molecules of the liquid crystal material or disturbances in the motion of the molecules.
Therefore, in order to use liquid crystals in actual display devices,
Synthesize a new organic compound that exhibits liquid crystallinity to suit the application, add a predetermined amount of solvent or dye to the liquid crystal, or create a compound with precisely controlled component ratios and purity.
Technological developments regarding various liquid crystals, such as mixing more than one type of liquid crystal, are being carried out.

Now, in order to manufacture a display device using a liquid crystal, the liquid crystal is placed in a container (hereinafter referred to as a container) in which substrates such as glass having transparent electrodes of a predetermined size and shape are placed facing each other at a narrow interval. liquid crystal cells). The technique for filling the liquid crystal cell with liquid crystal is important because it affects the performance, productivity, price, etc. of the display device, and various methods are used. However, conventional filling methods have various drawbacks.

The disadvantages of the conventional method will be explained below while explaining the most common conventional method of filling liquid crystal cells.

FIG. 1a is a schematic diagram for explaining a conventional liquid crystal filling method, in which a plurality of hollow liquid crystal cells 1 are arranged side by side in a cassette 2. A liquid crystal injection port 10 into the liquid crystal cell 1 is directed downward. In this figure, the injection port 10 is located at a corner of the liquid crystal cell 1. On the other hand, a liquid crystal storage container 3 (hereinafter referred to as a pan) containing liquid crystal 4 is placed opposite to the liquid crystal cell 1 and cassette 2 described above. After placing the entire structure in a vacuum evacuation device (not shown) and evacuating the inside of the liquid crystal cell 1, the pan 3 is mechanically pushed up or the liquid crystal cell 1 and the cassette 2 are mechanically pushed down to remove the liquid crystal cell. The injection port 10 of No. 1 is immersed into the liquid crystal 4. After that, if the entire vacuum state is broken, the hollow interior of the liquid crystal cell 1 will be in a vacuum state,
The liquid crystal 4 is filled in such a way that it is sucked into the interior through the injection port 10.

This conventional method has many drawbacks as described below. First is the shape of bread 3. Since the pan 3 is V-shaped, the surface area of the liquid crystal 4 becomes large. Therefore, when the vacuum is evacuated, the liquid crystal material and solvent evaporate to a large extent, causing the liquid crystal component ratio to deviate from a predetermined value, which adversely affects the performance of the liquid crystal and causes variations in performance.

Next, when the inlet 10 is located at the center of the side of the liquid crystal cell 1, as has been very commonly used in the past (see Fig. 1b), the inlet 10 is located at the position where the cassette is present. The type of cassette, depending on the type of liquid crystal cell,
It is necessary to change the size, resulting in poor productivity and high costs. Even if the type and size of the cassette is changed, it is inevitable that the distance from the corner of the liquid crystal cell 1 to the injection port 10 will become longer. Therefore, it is necessary to increase the depth of immersion of the liquid crystal cell 1 into the liquid crystal 4.
This increases the amount of liquid crystal that adheres to the surface of the liquid crystal cell, increasing loss. Especially in the case of a liquid crystal cell where the injection port 10 is located in the center of the side of the liquid crystal cell 1,
The size of bread 3 also had to be changed, which was very uneconomical.

In addition, in the case of a liquid crystal cell 1 having a more advanced structure such as one in which a plurality of liquid crystal cells are integrated as shown in FIG. is not possible.

Furthermore, the conventional method also has the following drawbacks. That is, in this method, the liquid crystal injection port faces downward. The process after filling the liquid crystal is to seal the injection port with an adhesive such as resin, so you can either take it out one by one from the cassette and seal it.
The complicated process of first transferring the liquid crystal cell group to a cassette with the injection port facing upward and then sealing it is necessary. As described above, the conventional liquid crystal injection method has various drawbacks.

The present invention provides a method and an apparatus for injecting liquid crystal into a liquid crystal cell, which eliminates the above-mentioned drawbacks and allows a liquid crystal cell with high performance and little variation in performance to be obtained with high productivity.

Below, the basic liquid crystal injection method of this invention will be explained in the second section.
The description will be made in accordance with the order of the filling steps schematically shown in the figure.

In the figure, reference numeral 30 is a liquid crystal reservoir, ie, a pan according to the present invention for injecting liquid crystal into the liquid crystal cell 1. This pan 30 has an opening 31 in its upper part into which a group of liquid crystal cells arranged side by side in the cassette 2 can be inserted all at once, and a reservoir in its lower part in which the liquid crystal 4 can be stored with a small surface area. It has a section 32. Then, as shown in FIG. 2b, after setting the pan 30 so that the reservoir 32 is located at the bottom and putting in the necessary amount of liquid crystal 4, a group of liquid crystals housed in the cassette 2 is inserted into the injection port 10. The pan 30 is installed so as to face the opening 31 and be inserted into the pan 30 from the opening. Thereafter, as shown in FIG. 2c, a group of liquid crystal cells is inserted into the pan 30 through the opening so as to be in contact with or slightly apart from the flat inner surface of the pan 30. If the entire structure is evacuated in this state using a vacuum evacuation device, the hollow interior of the first group of liquid crystal cells will be in a vacuum state. At this time, air bubbles existing in the liquid crystal 4 in the pan 30 are also removed.

Thereafter, while still in a vacuum state, the pan 30, the first group of liquid crystal cells, and the cassette 2 are integrated and rotated about 90 degrees as shown in FIG. 2d, so that the inner surface of the pan 30 is almost horizontal. (in the illustrated embodiment, the rotation is counterclockwise). The purpose of this rotational movement is to immerse the inlet 10 of the liquid crystal cell 1 that has been moved into the liquid crystal 4, so a 90 degree rotation is not necessarily necessary. Next, if the overall vacuum state is broken to atmospheric pressure, or if nitrogen gas or the like is used to make the pressure higher than atmospheric pressure, the inside of the liquid crystal cell 1 will be in a vacuum state, so the liquid crystal 4 will become as shown in Figure 2 e and f. When the liquid crystal cell changes its state, it is sucked into the liquid crystal cell and filled. Since the width (gap) of the hollow region in the liquid crystal cell is narrow, about 10 μm, capillary phenomena also contribute to filling. When the filling of the liquid crystal into the liquid crystal cell is completed, the whole is gently rotated again as shown in FIG. 2g (in the case of this figure, the rotation is clockwise). At that time, the liquid crystal 4, which had moved to the position where the liquid crystal cell is present, returns to the reservoir 32 of the pan 30 again. FIG. 2h shows a state in which the liquid crystal has completely returned to the reservoir 32 of the pan 30. Next, from bread 30, cassette 2
The filling process is completed by taking out one group of liquid crystal cells together with the liquid crystal cells. This situation is shown in Figure 2i.

By using the liquid crystal injection method of the present invention as described above, the above-mentioned conventional drawbacks can be almost completely eliminated for the following reasons.

Compared to the pan 3 having the structure shown in FIGS. 1a to 1c, according to the present invention, the liquid crystal in a vacuum state is
Since it is housed in the reservoir 31 of the pan 30, the surface area where evaporation occurs relative to the volume is smaller than in the past, and there is little need to consider changes in the components. In addition, in the method of the present invention, as can be easily understood from FIG. There is no need to change the cassette, whether it is in the middle of the side or in the center of the side, and there is no need to change the pan, which greatly improves work efficiency. Furthermore, a liquid crystal cell having a more advanced structure than the one in which a plurality of liquid crystal cell groups are integrated as shown in FIG. 1c can be processed without any problem. Furthermore, if only the size of the opening 31 of the pan 30 is designed, liquid crystal cells of different sizes can be filled with the same device, thereby improving workability and productivity.

As mentioned above, the fact that the side of the liquid crystal cell where the inlet is located is parallel to the liquid crystal surface in which it is immersed means that the immersion depth of the liquid crystal cell into the liquid crystal can be made very shallow, and therefore the panning The amount of liquid crystal charged into the reservoir 32 of 30 can be minimized, and the amount of wasteful liquid crystal adhering to the surface of the liquid crystal cell can also be suppressed to a small amount.

Furthermore, according to the present invention, the liquid crystal cell after being filled with liquid crystal can be taken out with the injection port facing upward while still being packed in the cassette, as shown in FIG. 2i. This makes it possible to automatically supply the liquid to the sealing process.

As explained above, by following the liquid crystal injection method of the present invention, a liquid crystal cell filled with high performance and stable liquid crystal can be obtained economically and with good productivity. Therefore, it is considered to have extremely large industrial value.

Next, an embodiment of the liquid crystal injection device according to the present invention will be described with reference to FIG. Figure 3a is a schematic side view of the device, and Figure 3d is a perspective view of the device, particularly the rotating mechanical parts.

This injection device is an embodiment of a device that simultaneously loads five cassettes containing one group of liquid crystal cells. Each group of liquid crystal cells is housed in each of these cassettes 2, and the one group of liquid crystal cells can be inserted into the opening 31 of the pan 30. This pan 30 is attached to a holder 6 for accurate positioning and fixing, and is housed in a tank 7 provided with five partitions. A rotary shaft 5 is provided protruding from both sides of the tank 7 so that the tank can rotate. The rotating shaft 5 is supported by an arm 8 extending from a pedestal 9, and the tank 7 is therefore suspended by both arms 8 which protrude from the pedestal 9 and are provided on both sides thereof. The frame 9 is fixed to a fixed base 11, and a damper 1 is installed to prevent the tank 7 from jumping up.
2 is provided.

The tank 7 placed in the space is designed to be able to rotate around the rotating shaft 5, and one of the arms 8 that supports the rotating shaft 5 is provided with an arm 8 that allows the tank 7 to be rotated at a desired angle. An angle lock pin 13 is provided for fixation, and a manual handle 14 is connected to the angle lock pin 13 so that this rotation can be performed manually. Further, on the other side of the arm 8, a device 15 that detects and controls the rotation angle of the tank is provided in connection with the rotation shaft 5 in order to automatically control the rotation angle of the tank.

Then, the manual handle 14 or the angle detection
Using the control device 15, the tank 7 containing the pan 30 and the cassette 2 is rotated counterclockwise to a desired angle to fill the liquid crystal cell 1 with liquid crystal 4, and then the tank is rotated counterclockwise to return to the return position. If it is returned to normal, the liquid crystal will be filled.

One embodiment of the present invention has been described above, taking as an example the cassette shown in FIG. 2 and the apparatus shown in FIG. 3 using this cassette. It goes without saying that it is entirely possible to change the above as appropriate or to use other additional devices.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining a conventional method of injecting liquid crystal into a liquid crystal cell, and FIG. 1a is a schematic diagram showing the arrangement and positional relationship of a liquid crystal cell, a cassette, a liquid crystal, and a liquid crystal reservoir. Figure b is a diagram showing the positional relationship between the cassette and the injection port when the injection port of the liquid crystal cell is located at the center of the side of the liquid crystal cell. Figure c is a diagram showing the positional relationship between the cassette and the injection port when a plurality of liquid crystal cells are integrated to form one liquid crystal cell. FIG. 2 is a schematic diagram showing the order of the filling process using the liquid crystal injection method according to the present invention. FIG. 3 shows an embodiment of a liquid crystal injection device according to the present invention, in which FIG. 3a is a side view and FIG. 3b is a perspective view. 1... Liquid crystal cell; 2... Cassette; 4... Liquid crystal; 5... Rotation axis; 6... Holder; 7... Tank; 8... Arm; 9... Mount; 10... Liquid crystal note of liquid crystal cell Entrance; 11... Fixed stand; 12... Damper; 13... Angle lock pin; 14... Manual handle; 15... Angle control device; 30... Liquid crystal reservoir (pan); 31... Opening; 32... ...Reservoir.

Claims (1)

[Claims] 1. Using a liquid crystal container having an opening for inserting a liquid crystal cell and a liquid crystal reservoir located below the opening, the vertical inner surface of the opening has an injection port for the liquid crystal cell located above. The liquid crystal container is inserted and fixed so as to be close to the liquid crystal container, and then the liquid crystal container is rotated in the normal direction under a reduced pressure atmosphere so that it becomes almost horizontal, and the liquid crystal cell is placed inside the liquid crystal that has been moved to the opening area of the liquid crystal container. A method for injecting a liquid crystal, comprising: immersing the injection port in the liquid crystal cell, releasing the reduced pressure atmosphere to inject and fill the liquid crystal cell, and then inverting the liquid crystal container to the return position again. 2. A liquid crystal container having an opening for inserting a liquid crystal cell and a liquid crystal reservoir communicating with the opening, and a liquid crystal container and a liquid crystal cell with the inlet side inserted into the opening of the liquid crystal container are housed and fixed. a container storage section that can be used;
A liquid crystal injection device comprising: a vacuum evacuation device capable of maintaining the entire container storage part in a reduced pressure atmosphere; and a rotation mechanism capable of rotating the container storage part forward and backward by a predetermined angle. 3. The liquid crystal injection device according to claim 2, wherein one or more container storage units are arranged in parallel according to the number of liquid crystal containers. 4. The liquid crystal injection device according to claim 2, wherein the rotation mechanism includes a rotation shaft protruding from both sides of the container storage section, and rotation angle locking means connected to the rotation shaft.