JPS638630A - Injecting method for liquid crystal - Google Patents

Abstract

PURPOSE:To reduce pressure up to a high degree of vacuum without changing the composition of liquid crystal components and to sufficiently exhaust air by cooling liquid crystal held in a pressure reduction room up to a point close to its melting point in a pressure reduction process. CONSTITUTION:At the time of reducing the pressure of a blank cell 10 by reducing the pressure of the pressure reduction room 1, the liquid crystal 20 held in a liquid crystal tank 30 is cooled from a room temperature up to a point close to the melting point. When the pressure of the pressure reduction room 1 is reduced by driving a pressure reducing device 60, the degree of vacuum in the room 1 is sufficiently obtained without changing the composition of the liquid crystal 20. The pressure in the room 1 is increased under the state that an injection port 101 of the cell 10 is dipped into the liquid crystal 20, inert gas is led into the room 1 and then the pressure in the room 1 is returned to atmospheric pressure. When the liquid crystal 20 is heated up to the room temperature and left as it is, the liquid crystal 20 is injected into a space 103 by the differential pressure between the high degree of vacuum and the atmospheric pressure and the space 104 is filled with the liquid crystal 20 to form a liquid crystal cell.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for injecting liquid crystal into a hollow cell, and more specifically, by cooling the liquid crystal injected into the hollow cell, the components of the liquid crystal are A liquid crystal TT six-person method that allows the composition of the liquid crystal to remain unchanged during the depressurization process and to obtain a sufficient depressurized state so that no air bubbles remain in the empty cell even in the case of a large-volume empty cell. available.

[Prior Art] Conventionally, there is a vacuum impregnation method as a method for injecting liquid crystal into a hollow cell. This vacuum impregnation method is shown in FIG. According to this, an empty cell 10a having an injection port 101a is connected to a liquid crystal 2
10'''2 to 1O-4t inside the decompression chamber 1a using the decompression device 60a.
A step of reducing the pressure inside the empty cell 10a by reducing the pressure in the empty cell 10a, and returning the pressure inside the decompression chamber 1a to atmospheric pressure using the pressure booster ff130a with the injection port 101a of the empty cell 10a immersed in the liquid crystal 2Oa. A liquid crystal injection method has been known which includes a step of injecting liquid crystal 20a into an empty cell 10a using a pressure difference between the inside of the empty cell 10a and the pressure reduction chamber 1a. (For example, according to Japanese Patent Application Laid-open No. 7820/1982.) [Problems to be solved by Fe Ming] The above-mentioned conventional method had the following problems.

(b) In the step of reducing the pressure inside the vacuum chamber 1a and reducing the pressure inside the empty cell 10a, the liquid crystal 20a held in the vacuum chamber 7a is affected by the vacuum, causing components of high vapor pressure in the liquid crystal 2Oa to become liquid crystals 2Oa.
It contains a liquid crystal component called a viscosity reducer to prevent the viscosity from increasing at low temperatures. This material has smaller molecules and higher vapor pressure than normal liquid crystal materials. ) is evaporated during the reduced pressure and the liquid crystal 20 to be injected into the empty cell 10a.
The problem is that the composition of component a changes.

(b) If a cell with a large internal space volume is used as the empty cell 10a, due to the reasons mentioned in (a) above, the empty cell 1
In the case where it is not possible to reduce the pressure to a high degree of vacuum so that no air bubbles remain in the liquid crystal 20a, and the air in the internal space where the liquid crystal 20a is injected cannot be sufficiently removed, some air bubbles remain. There is.

An object of the present invention is to provide a liquid crystal injection method that solves the above problems.

[Means for Solving Problems] The liquid crystal injection method of the present invention includes the steps of arranging an empty cell having an injection port in a vacuum chamber for holding liquid crystal, and reducing the pressure in the vacuum chamber to fill the empty cell. A step of reducing the pressure, and immersing the injection port of the empty cell in the liquid crystal to increase the pressure in the vacuum chamber and confirming that the liquid crystal held in the empty cell (has been cooled to near its melting point). This is a characteristic feature.

According to the present invention, the composition of the liquid crystal component does not change when the pressure in the vacuum chamber is reduced, and even in a large empty cell with a volume of 1 m, no air bubbles remain inside the cell.

The empty cell used in the liquid crystal injection method of the present invention has a hollow interior, and refers to an empty cell in which no liquid crystal is injected. This empty cell in which liquid crystal is injected is called a liquid crystal cell.

The decompression chamber can be hermetically sealed, and empty cells can be arranged inside in groups of 50 to 100 cells. In this case, a large number of empty cells are arranged in parallel with the injection ports facing the liquid crystal tank! The injection ports of the large number of empty cells can be simultaneously held in a state of being immersed in the liquid crystal of the liquid crystal tank by a moving device which will be described later. The vacuum chamber includes a liquid crystal tank that holds liquid crystal, a device that moves the empty cell toward or away from the liquid crystal tank while holding the empty cell, and a device that introduces an inert gas into the vacuum chamber in a reduced pressure state. A pressure intensifier that increases the pressure and returns it to atmospheric pressure, a pressure reducer that discharges the air in the vacuum chamber and reduces the pressure inside the vacuum chamber, and a temperature 'A? that can control the humidity of the liquid crystal in the liquid crystal tank. It is equipped with two devices. Conventional devices such as the device for moving the empty cells, the pressure reducing device, the pressure increasing device, etc. can be used as they are.

The temperature adjustment device is capable of lowering the temperature of the liquid crystal held in the liquid crystal tank to near the melting point of the liquid crystal, maintaining this temperature, and heating the temperature of the liquid crystal that has been lowered to near the melting point to raise it to air temperature. be. The temperature control device used is one that controls the temperature of the liquid crystal by circulating a heat medium, or one that controls the temperature of the liquid crystal electrically.

[Function of the Invention] According to the liquid crystal injection method of the present invention, after an empty cell is placed in a reduced pressure chamber that holds liquid crystal, the liquid crystal is cooled to near its melting point by a temperature adjustment device, and becomes like this! During return, the pressure in the pressure reduction chamber is reduced by the pressure reduction device to create a vacuum of 10-3 to 10-5 torr. In this state, the empty cell is immersed with its injection port in the liquid crystal held in the vacuum chamber. At the same time, decompression is stopped,
Inert gas is introduced into the reduced pressure chamber from the pressure booster, and the reduced pressure chamber becomes atmospheric pressure. On the other hand, the liquid crystal held in the reduced pressure chamber by the temperature adjustment device is heated and reaches room temperature in about 5 minutes, and its viscosity decreases. In this state, liquid crystal is injected to fill the internal space due to the large pressure difference between the empty cell and the reduced pressure chamber.

[Effect of the Invention 1] According to the liquid crystal injection method of the present light 11i1, in the pressure reduction step, the liquid crystal held in the pressure reduction chamber is cooled to near its melting point. Therefore, a component (thinning agent) of high vapor pressure of the liquid crystal in the liquid crystal component does not evaporate even when the pressure in the vacuum chamber decreases.

As a result, the degree of vacuum in the decompression chamber and the empty cell can be sufficiently increased without changing the composition of the liquid crystal component. In addition, even if the empty cell has a large internal space volume, the air in the internal space of the empty cell is exhausted to prevent air bubbles from remaining.

Therefore, in the step of injecting the liquid crystal into the empty cell, the liquid crystal can be reliably injected into the empty cell. At the same time, it is possible to manufacture a liquid crystal cell with excellent quality liquid crystal.

[Example] Examples of the liquid crystal injection method of the present invention are shown in FIGS. 1, 2, and 3.
The explanation will be given based on FIGS. 4, 5, 6, and 7.

The liquid crystal injection method of the embodiment is characterized in that the liquid crystal held in the vacuum chamber is cooled to near its melting point in the vacuum step.

First, the decompression chamber 1, empty cell 10, and liquid crystal 2 used in this example
0.LCD! 130, temperature W4 regulating device 31, moving device 40
．． The pressure increase device 50, pressure reduction device 60, etc. will be explained.

The decompression chamber 1 includes an empty cell 1o and a liquid crystal tank 30 containing a liquid crystal 20.
Then, while holding the empty cell 10, approach the liquid crystal tank 30,
Alternatively, a moving device 40 for moving away, a pressure increasing device 50 for introducing an inert gas (for example, nitrogen gas) into the decompression chamber 1, and a pressure increasing device 50 for discharging the air in the decompression chamber 1 and the empty cell 10 and reducing the pressure. It has a pressure reducing device 60 that reduces the pressure in the chamber 1, and a heat medium circulation circuit 320 connected to the liquid crystal tank 30, and circulates the heat medium whose temperature has been adjusted in advance to a required temperature with the liquid crystal tank 3o interposed. , LCD 1fF30
It is equipped with a temperature adjustment device 310 that can control the temperature of the liquid crystal 20 inside.

The empty cell 10 is filled with liquid crystal and has a length of 25 cm and a width of 5 cl. The empty cell 10 consists of two plates 102, 102 and two plates 102.10.
An adhesive layer 103 is arranged in a frame shape between the two and adheres the two, forming a space 104 in which the liquid crystal 20 is accommodated and a liquid crystal injection port 101 communicating with the space 104.

As the liquid crystal 20, a liquid crystal manufactured by Merck & Co. (ZL I-1701) containing a high vapor pressure component (thinning agent) is used. This liquid crystal 2o has a melting point of -15°C and a nematic phase transition temperature of +61°C.

The liquid crystal W430 has a liquid crystal 20 on the upper part with the wall surface 301 as a boundary.
A recessed portion 302 for inserting and holding the heat medium, and a heat medium chamber 303 surrounding the recessed portion 302 are formed. In addition, the liquid crystal tank 30 is made of a material with high thermal conductivity, such as copper, for the wall surface 301 forming at least the four parts 302 that conduct heat from the heat medium to the liquid crystal 20, and the contact surface with the liquid crystal 20 is made of fluororesin. is coated.

The temperature adjustment device 31 includes a temperature controller 310 installed outside the decompression chamber 1 and equipped with a heat exchanger (not shown), a heat medium chamber 303 of the liquid crystal tank 30 housed in the decompression chamber 1, and a temperature controller 310. A heat medium delivery passage 321 and a heat medium return passage 3 that connect the heat medium chamber 303, respectively.
22 to form a heat medium circulation circuit 320, and an adjustment valve 3 that can adjust the flow rate of the heat medium in the circulation circuit 320.
It is equipped with 30. Further, Freon is used as a heat medium.

A vacuum pump can be used as the pressure reducing device 60. Also, decompression chamber 1
A vacuum valve 6 is connected to a passage 610 connecting the pressure reducing device 60 and the vacuum valve 6.
It is equipped with 20. Further, the pressure increase device 50 can use a cylinder filled with an inert gas. The pressure increase device 50 and the pressure reduction chamber 1 are connected by a passage 510 including a relief valve (pressure regulating valve) 520.

The liquid crystal injection method of this embodiment will be described below.

(1) Step of arranging the injection port 101 in the empty cell 10 and the liquid crystal 20 in the decompression chamber 1.

In this process, 50 to 100 empty cells 10 are placed in advance in the third
As shown in the figure, after being placed between jig plates 402 and 402 with an elastic body 401 interposed therebetween and fixed with bolts 403 and nuts 404, the moving frame ff14 in the decompression chamber 1
0, each empty cell 10 is held with its injection port 101 facing the liquid crystal tank 30. In this state, the decompression chamber 1 is sealed.

(2) A step of reducing the pressure inside the empty cell 10 by reducing the pressure inside the reduced pressure v1.

In this step, the liquid crystal 20 held in the liquid crystal tank 30 is cooled from room temperature to near its melting point (-15° C.). In this case, the temperature Iff adjustment device 310 is activated, and the heat medium kept at a constant temperature (target cooling temperature) by the temperature adjustment device 310 circulates in the II+ ring circuit 320 as shown by the arrow. Due to the circulation of this heat medium, the liquid crystal fl! The liquid crystal 20 held by the liquid crystal 30 is cooled to approximately the same temperature as the heat medium. This causes the liquid crystal 20 to reach its melting point (minus 15
℃).

Along with the above cooling effect, the pressure reducing device 60 is operated l''Il:IJ to reduce the pressure in the reduced pressure chamber 1. (The relationship between the degree of vacuum of the reduced pressure v1 and the temperature of the liquid crystal 20 is as shown in FIG. 6.

In other words, even if the pressure reduction time is the same, the lower the temperature of the liquid crystal 20, the higher the degree of vacuum achieved. Furthermore, Fig. 7 shows the relationship between the temperature of the liquid crystal 20 during depressurization and the nematic phase transition temperature, and when the temperature of the liquid crystal 20 during depressurization is lowered to -14°C, the initial phase transition temperature increases by 61°C. remains almost unchanged. On the other hand, when the temperature of the liquid crystal 20 increases when the pressure is reduced, the phase transition temperature increases, indicating that the composition of the liquid crystal 20 has changed.

) Thus, the degree of vacuum in the decompression chamber 1 becomes sufficient without changing the composition of the liquid crystal 20.

(3> With the injection port 101 of the empty cell 10 immersed in 20, the pressure inside the decompression chamber 1 is increased, and the liquid crystal 20 is placed inside the empty cell 10.
The process of injecting.

In this step, the injection port 101 of the liquid crystal cell 10 shown in FIG.
Immersed in 0. After immersion, the operation of the pressure reducing device 60 is stopped. In this case, passage 610 is closed by vacuum valve 620.

Next, inert gas is introduced into the reduced pressure chamber 1 from the pressure booster 50, and the inside of the reduced pressure chamber 1 is returned to atmospheric pressure. Thereafter, the temperature adjustment device 310 raises the temperature of the heat medium to a certain level and causes the heat medium to circulate and flow within the circulation circuit 320. In addition, the liquid crystal 20 held in the liquid crystal tank 30 is heated and raised to room temperature. (The time required for the temperature to rise to room temperature is about 5 minutes. Also, it may be heated above room temperature if necessary.) It is left in this state for about 1 hour. Liquid crystal 2 held in liquid crystal tank 30
0 is gradually injected into the space 104 inside the empty cell 10 due to the large pressure difference between the high degree of vacuum inside the liquid crystal cell 10 and the atmospheric pressure inside the decompression chamber 1.

About one hour after the start of the injection amount, the space 10 in the empty cell 10
4 is filled with liquid crystal 20 and becomes a liquid crystal cell.

After this, the decompression chamber 1 is opened and the liquid crystal cell is taken out to the outside.
The injection port 101 is sealed.

(Modified example) A modification of the embodiment of the present invention will be explained based on FIG. 8.

Note that explanations of the structure and operation of the same parts as those of the above embodiment will be omitted.

In the case of this modification, a device that electrically controls the temperature of the liquid crystal 20 is used as a temperature adjustment device 31 for cooling the liquid crystal 20 held in the liquid crystal tank 30 in the decompression chamber 1 in the decompression process. .

For example, an electric circuit 360 is used that includes a Bertier element 340 whose Bertier effect is reduced by 1q when energized, a power source 3501, and other necessary components. Furthermore, an N-type semiconductor and a P-type semiconductor can be used as the Vertier element.

[Brief explanation of drawings]

FIG. 1 is a schematic view showing the main part of the embodiment of the present invention, and is a partial sectional view showing the state before the injection port 101 of the empty cell 10 is immersed in the liquid crystal 20. FIG. Figure 2 shows an empty cell 10 before liquid crystal injection.
FIG. What about figure 3? 12100 is a side view of a portion 'IJLi1'i showing a state in which the empty cell 10 is attached and fixed to the jig plate 402. FIG. FIG. 4 is a partial cross-sectional view showing a state in which the empty cell 10 has been moved downward from the position shown in FIG. 1 and the injection port 101 has been immersed 20 km into the liquid crystal. FIG. 5 is a partial sectional view showing a state in which the liquid crystal 20 held in the liquid crystal tank 30 is injected into the empty cell 10 due to the pressure difference in the embodiment of the present invention. FIG. 6 is a diagram showing the relationship between the liquid crystal temperature in vacuum and the ultimate degree of vacuum in the embodiment of the present invention. FIG. 7 is a cross-sectional view of the embodiment of the present invention under vacuum.

Claims (2)

[Claims] (1) A step of placing an empty cell having an injection port in a vacuum chamber holding a liquid crystal, a step of reducing the pressure inside the vacuum chamber to reduce the pressure inside the empty cell, and a step of disposing the empty cell having an injection port into the liquid crystal. In a liquid crystal injection method comprising a step of increasing the pressure in the vacuum chamber and injecting the liquid crystal into the empty cell while the liquid crystal is immersed in the vacuum cell, the liquid crystal held in the vacuum chamber in the vacuum step is near the melting point of the liquid crystal. A liquid crystal injection method that is characterized by being cooled to a maximum temperature. (2) The liquid crystal injection method according to claim 1, wherein the liquid crystal is heated in the step of injecting the liquid crystal to reduce the viscosity of the liquid crystal.