JPH0534696A - Production of liquid crystal electrooptical element - Google Patents

Abstract

PURPOSE:To execute gap control with high accuracy and uniform orientation with good mass productivity by increasing the cell thickness after injection and subjecting the cell to a post treatment. CONSTITUTION:A vacuum valve 108 is opened while the empty liquid crystal cell 101 is kept heated by a heater 105 in the state of closing a leak valve 109. A table 106 is lifted to bring a pot 103 contg. a liquid crystal into contact with the cell where the vacuum evacuation is executed for a prescribed period of time. The liquid crystal is heated up to the phase higher than the temp. at which the liquid crystal exhibits a smectic phase. After the liquid crystal closes the injection port of the liquid crystal, the valve 108 is closed and the valve 109 is opened to restore the atm. pressure in the vessel. The liquid crystal is completely injected into the cell by resting for a prescribed period of time and thereafter, the cell is taken out. Several sheets of the taken out liquid crystal cells 101 injected with the liquid crystals thicker than the prescribed thickness are set. A dummy substrate 114 and an intermediate plate 113 are disposed in suitable positions. The upper and lower fixing plates of jigs are fixed and a pressure is impressed to a pressurizing elastic body 112. The inside of a heating vessel 110 is heated up to the temp. at which the liquid crystal has the phase higher than the smectic phase. The cells are cooled and hermetically sealed while the sells are held impressed with the pressure.

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 electro-optical element, and more particularly to a method for manufacturing a liquid crystal electro-optical element having a smectic phase.

[0002]

2. Description of the Related Art Conventionally, in a method of manufacturing a liquid crystal electro-optical element using a smectic liquid crystal, two substrates are made to face each other with an electrode and an alignment film facing each other, and a thickness of a liquid crystal layer is controlled between them. In order to reduce the viscosity of the liquid crystal under reduced pressure, both substrates are fixed by a patterned adhesive frame (seal) excluding the liquid crystal injection port on both substrates. The liquid is injected while being heated to a temperature higher than the temperature showing the smectic phase, cooled until the liquid crystal enters the smectic phase, and the injection port is sealed with an adhesive. Further, if necessary, this liquid crystal electro-optical element is reheated to a temperature higher than the temperature showing a smectic phase and gradually cooled to make the orientation uniform.

[0003]

However, in the conventional method for manufacturing a liquid crystal electro-optical element, in a general cell manufacturing process in which the cell center portion is thicker than a desired value in an empty cell state before liquid crystal injection. Due to the feature of (1), the desired cell thickness cannot be obtained unless the cell is sealed at the moment when the liquid crystal has entered the cell.
Moreover, it is necessary to determine the termination of the injection at a temperature above the smectic phase, and it is difficult for the desired cell thickness to be achieved when cooled to the smectic phase. Therefore, the timing of sealing is difficult, and if it is too early, it becomes thin, and if it is too late, the center tends to become thick.

Further, there is a problem in that it is very difficult to control the thickness of the liquid crystal cell, for example, it is difficult to inject and seal the liquid crystal into many cells at one time.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to achieve high-accuracy gap control and excellent alignment of a liquid crystal electro-optical element having a smectic phase at the same time, and to achieve mass productivity. It is to provide a good manufacturing method.

[0006]

In order to solve the above-mentioned problems, the method for manufacturing a liquid crystal electro-optical element of the present invention shows at least particles or pillars for gap control and a smectic phase between two substrates. In a liquid crystal electro-optical element that holds a liquid crystal and seals the periphery, the thickness of the liquid crystal layer before sealing the liquid crystal electro-optical element is made thicker than a desired thickness, and then the liquid crystal electro-optical element is made to have a smectic phase. After heating or applying pressure after applying pressure to a temperature higher than the indicated temperature, and further cooling the liquid crystal electro-optical element to a temperature indicating the smectic layer while applying the pressure to obtain a desired liquid crystal layer thickness. , Which is characterized by being sealed.

[0007]

According to the above-mentioned structure of the present invention, the liquid crystal layer thickness is once thickened by setting the injection time longer by taking advantage of the feature that the cell center portion becomes thicker at the time of manufacturing the cell, and then at a temperature higher than that of the smectic phase. By heating the liquid crystal to lower its viscosity and cooling it while applying a pressure necessary for cell homogenization, it is possible to perform uniform gap control with a desired cell thickness while expelling excess liquid crystal. Further, since the above-mentioned operation is carried out while cooling, the heat capacity of the apparatus is naturally gradually cooled so that the alignment of the liquid crystal can be made uniform at the same time. Therefore, the method of the present invention does not require severe setting and management of manufacturing conditions.

[0008]

1 is a schematic view of a partial structure of an apparatus for showing a manufacturing method according to the present invention.

FIG. 1A shows an apparatus for injecting liquid crystal, which has a vacuum and heating mechanism. Reference numeral 101 is a liquid crystal electro-optical element (liquid crystal cell), 102 is a container wall for evacuating, 103 is a liquid crystal pot, 104 is liquid crystal, 105 is a heater, 106 is a vertical movement table, 107 is an apparatus table, 108 is A vacuum valve for vacuuming, and a leak valve 109 for leaking vacuum. With the leak valve 109 closed, the heater 105 heats the empty liquid crystal cell 101 and opens the vacuum valve 108.
The inside of the container is evacuated, and when the chamber is evacuated for a predetermined time, the table 106 is raised to bring it into contact with the jar 103 containing the liquid crystal to raise the liquid crystal to a temperature above the temperature exhibiting the smectic phase, and the injection port of the liquid crystal cell is opened. After the liquid crystal is blocked, 108
And the leak valve 109 is opened and the inside of the container is returned to atmospheric pressure and left for a predetermined time to completely inject the liquid crystal and then take it out. Figure 1
(B) is a schematic view of an apparatus for uniformizing cell thickness and alignment after liquid crystal injection, which has a pressurizing and heating mechanism. 11
Reference numeral 0 is an inner wall surface of the heating device, 111 is a fixing jig for applying pressure to the liquid crystal cell, 112 is a pressure mechanism for applying pressure, and a gas having a constant pressure is introduced into a rubber-like elastic body whose periphery is normally fixed. Then inflate it into a balloon. Reference numeral 113 is an intermediate plate, which is a cushioning material for preventing thickness unevenness due to adhesion of dust and the like, and 114 is a dummy substrate made of glass, metal or the like. Several liquid crystal cells 101 taken out from the vacuum apparatus of FIG. 1 (a) and injected to a thickness greater than a predetermined thickness are set on a jig 111 for pressurization, and a dummy substrate 114 and an intermediate plate 113 are arranged at appropriate positions. To do. Further, after fixing the upper and lower fixing plates of the jig of 111, pressure is applied to the pressurizing elastic body 112 for pressurizing, and the inside of the heating container 110 is heated to a temperature at which the liquid crystal phase is higher than the smectic phase, A liquid crystal electro-optical element is prepared by cooling and sealing while applying pressure.

FIG. 2 is a schematic view showing an example of a liquid crystal electro-optical element manufactured by the present invention. 2A is a plan view and FIG.
(B) is a schematic sectional view.

Reference numerals 202 and 203 denote substrates, 201 and 204 denote upper and lower electrodes, 205 denotes a seal, 206 denotes a liquid crystal alignment film, and 20.
Reference numeral 7 is a gap control gap material, and 208 is a liquid crystal.

Example 1 The liquid crystal electro-optical element shown in FIG. 2 was prepared. First, glass substrates 202 and 203
Electrodes 201 and 204 made of ITO are respectively formed on the top in a pattern, and an alignment film 206 made of polyimide is further rubbed thereon, and then a gap member 207 of about 2.3 μm is sprinkled at 100 to 500 / mm ^2. The two substrates were attached by a seal 205 to form a 10-inch size liquid crystal cell. The liquid crystal cell 101 was set in the vacuum device shown in FIG. 1A, and a smectic liquid crystal exhibiting ferroelectricity as a liquid crystal material (ZLI-4655-00 manufactured by Merck & Co., Inc.).
0) was used to inject the isotropic phase at a temperature of about 80 ° C. to obtain a liquid crystal cell having a thickness of about 3 μm. This liquid crystal cell is shown in FIG.
Set in a device having a heating and pressurizing mechanism in (b),
The inside of the heating container 110 is heated to about 80 ° C. to be 0.2 to 1.0.
112 was pressurized within a pressure range of kg / cm ² , then cooled, excess liquid crystals were discharged, and sealed at a room temperature. The completed liquid crystal cell has 1.7 to 2.1 ± 0.
It had a cell thickness in the range of 1 μm and excellent alignment uniformity. The absolute value of the cell thickness can be freely determined by the applied pressure and the size and amount of the gap material to be dispersed. Further, when a polarizing plate and a driving circuit were provided and operated in this ferroelectric liquid crystal electro-optical element, the front surface was uniform and a good contrast ratio was obtained.

Example 2 A liquid crystal electro-optical element having the structure shown in FIG. 2 was prepared. In this embodiment, it is a thermal writing type smectic liquid crystal electro-optical element. Electrode film 20 on lower substrate
4, an A1 film was formed in a pattern, silane was used as the alignment film 206, and 10.5 μm was used as the gap material 207.
A liquid crystal cell having a size of 7 m was used by using a liquid crystal cell having a size of m. This liquid crystal cell before liquid crystal injection is set in the apparatus shown in FIG. 1 (a) by setting 10 liquid crystal cells 101 vertically and heating the inside of the container wall 102 for vacuuming.
01 was heated to 70 ° C., which is higher than the phase showing the smectic phase, and the liquid crystal vat 103 was set on the up-and-down moving table 106 and evacuated for a certain time to immerse the liquid crystal cell 101 in the vase to inject liquid crystal. Further, a cyanobiphenyl-based smectic liquid crystal was used as a liquid crystal material, and 70 ° C. was a temperature range showing a nematic phase or an isotropic phase, a liquid crystal cell thickness was about 15 μm, and cooling was performed at the same temperature while applying pressure as in Example 1. When it reached room temperature, it was sealed. Finished 10
The thickness unevenness between the liquid crystal cells is 10.0 ± 0.1μ
It was confirmed that it was m and was excellent in uniformity and mass productivity.

The above examples show a part of the present invention.
The structure and type of the liquid crystal electro-optical element can be adapted as long as it is a liquid crystal element exhibiting a smectic phase, and the structure and method of the liquid crystal injection / pressurization heating device and the number of liquid crystal cells to be processed can be arbitrarily set. ..

[0015]

As described above, according to the present invention, after the liquid crystal is thickened at the time of injecting the liquid crystal and then injected, the liquid crystal is heated to a temperature higher than the temperature showing the smectic phase and pressure is applied. Since the liquid crystal is cooled to a desired liquid crystal thickness, the precision of time management at the time of liquid crystal injection becomes unnecessary, and since the precision of the thickness is not required at this stage, many liquid crystal electro-optical elements can be processed at one time. Further, since cooling is performed while applying pressure, cell thickness control and uniform alignment treatment can be performed simultaneously. Therefore, mass productivity is improved overall. In addition, since the gap material particles or columns in the liquid crystal cell have a structure in which the element is constantly applied with pressure applied, it is possible to reduce the strength reduction against external stress peculiar to the smectic liquid crystal element. Have.

[Brief description of drawings]

FIG. 1 is a schematic view of a partial structure of an apparatus for showing a manufacturing method according to the present invention, in which (a) is an apparatus for injecting liquid crystal, and (b) is a cell thickness and orientation uniformization after injecting liquid crystal. 2 is a schematic diagram of an apparatus for.

FIG. 2 is a schematic view showing an example of a liquid crystal electro-optical element manufactured by the present invention, (a) is a plan view, and (b) is a schematic cross-sectional view.

[Explanation of symbols]

 101 Liquid Crystal Cell 102 Container Wall 103 Liquid Crystal Vase 104 Liquid Crystal 105 Heater 106 Vertical Moving Table 107 Device Table 108 Vacuum Valve 109 Leak Valve 201 Upper Electrode 202 Upper Substrate 203 Lower Substrate 204 Lower Electrode 205 Seal 206 Alignment Film 207 Gap Material 208 Liquid Crystal

Claims (1)

Claim: What is claimed is: 1. A liquid crystal electro-optical element comprising a pair of substrates, at least particles or pillars for gap control, and a liquid crystal exhibiting a smectic phase being sandwiched between the substrates, and the periphery thereof being sealed. The thickness of the liquid crystal layer before sealing the liquid crystal electro-optical element is made thicker than a desired thickness, and then the liquid crystal electro-optical element is heated while applying pressure at a temperature higher than the temperature showing a smectic phase or after applying pressure after heating. Then, the liquid crystal electro-optical element is cooled to a temperature exhibiting a smectic phase in a state where pressure is applied, the thickness of the liquid crystal layer is adjusted to a desired value, and then the liquid crystal electro-optical element is sealed.