JPH0449691B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an electro-optical device such as a display device, and in particular to a method for manufacturing a smectate liquid crystal element using a smectate liquid crystal that is a ferroelectric liquid crystal.

Recently, with the rapid spread of information devices such as televisions and personal computers, the demand for display devices has increased significantly. These display devices are overwhelmingly CRTs due to their large display capacity.
is used. On the other hand, although liquid crystal display devices have the advantage of being thin, they are not widely used for slightly larger screens because of their small display capacity.

The present inventor has invented a display device using a chiral smect liquid crystal, which is a completely new display method that overcomes the limitations of conventional liquid crystal display devices, and has filed a separate application for the same.

[Prior art]

Liquid crystal display elements using smectic liquid crystals have been known for a long time. For example, JP-A-56-
It is disclosed in JP-A-107216 and JP-A-59-34516.

Ferroelectric liquid crystal was developed in 1975 by Meyer (J.de.phys.36,
69, 1975) and its existence was demonstrated.

The liquid crystal synthesized at that time was commonly known as DOBAMBC (2
-Methylbutyl P-[(P-n-decyloxybenzylidene)amino]) It is still actively used in research on ferroelectric liquid crystals. Generally, a chiral smect liquid crystal has a molecular arrangement as shown in FIG.

That is, as shown in FIG. 3A, the liquid crystal molecules 1 have a layered structure. The long axis direction of the liquid crystal molecules in each layer is constant within the layer, but each layer is tilted by θ with respect to the normal direction A of the layer, and the direction of the tilt is rotated, forming a helical structure as a whole. .

A chiral smect liquid crystal has a helical structure, and the period of the helix is usually on the order of several μm. When a chiral smectoid liquid crystal is injected into a cell with a gap of about 1 to 3 μm, which is thinner than the period of the helix, the helical structure disappears. The molecular arrangement structure after the helical structure disappears is shown in FIG. FIG. 4 is a plan view of the liquid crystal cell, and the liquid crystal molecules are parallel to the cell substrate. That is, the long axes of the liquid crystal molecules are parallel to the substrate and are tilted by +θ or -θ from the normal direction A of the layers. Both states are stable, and by applying a voltage a transition occurs between the two states, which is used for display.

[Problem that the invention seeks to solve]

However, since the above-mentioned smectic liquid crystal is generally pasty at room temperature and has no fluidity, and the cell gap must be made very small, it is very difficult to fill the smectic liquid crystal into a cell in a short time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a smectage liquid crystal element, which allows smectage liquid crystal to be easily injected into a cell in a short time even if the cell gap is very small.

[Means for solving problems]

The manufacturing method of the present invention solves the above-mentioned problems, and includes a step of bonding the periphery between the upper and lower substrates, at least one of which is transparent, with an adhesive layer to form a liquid crystal cell to form a gap, and a step of forming a liquid crystal cell in the liquid crystal cell. a step of applying a smectic liquid crystal onto the substrate near the liquid crystal injection hole, a step of placing the liquid crystal cell in a vacuum to exclude air inside it, and then heating the liquid crystal cell to improve the fluidity of the smectate liquid crystal. The liquid crystal injection hole is filled with a sealant, and the liquid crystal injection hole is filled with a sealing material.

[Effect]

In this way, when a glue-like smectic liquid crystal is applied to the substrate near the liquid crystal injection hole and the air inside the liquid crystal cell is removed, the liquid crystal cell is heated, and the smectic liquid crystal turns into liquid or cholesteric liquid crystal. Phase transition occurs and fluidity increases. Then, this fluidized liquid crystal spreads over the substrate and blocks the liquid crystal injection hole. Thereafter, when the degree of vacuum outside the liquid crystal cell is lowered, the liquid crystal is introduced into the cell by the gas pressure.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, 12 is an upper substrate, 13 is a lower substrate, and at least the upper substrate 12 is made of a transparent material such as glass. The upper substrate 12 and the lower substrate 13 are bonded together using an adhesive layer 14 so as to be placed facing each other. At this time, the gap between the two substrates is 1~
Spacers such as glass fiber pieces or alumina particles of a predetermined diameter are sprinkled between the substrates and both substrates are pressed from the outside so that the distance is maintained constant between 3 μm. These glass fiber pieces, alumina particles, etc. are mixed into the adhesive layer 14, and this mixed adhesive layer 14
It can also be used as a spacer. Also,
The upper substrate 12 and the lower substrate 13 are not completely aligned, and the lower substrate 13 protrudes from the upper substrate.

The adhesive layer 14 has a thickness of 20 to 50 μm around the lower substrate 13.
It is formed by a method such as screen printing to a certain thickness. As the adhesive layer 14, epoxy resin, low melting point glass, etc. are used. This adhesive layer 14 extends to a portion protruding from a portion of the periphery of the lower substrate 13 overlapping with the upper substrate 12, and forms a closed rectangle as a whole. Therefore, after the upper and lower substrates are bonded together, this adhesive layer 14 is
The parts where the upper and lower substrates overlap are crushed to a thickness of several μm, but the parts that protrude are crushed to a thickness of 20 to 50 μm.
The thickness is maintained.

After the liquid crystal cell is formed in this manner, a paste-like chiral smect liquid crystal is applied onto the substrate, as shown in the process block diagram of FIG.

After the upper and lower substrates are bonded together in this manner, an appropriate amount of chiral smecting liquid crystal 15 is coated on the lower substrate between the adhesive layer 14a on the protruding portion of the lower substrate 13 and the upper substrate 12. after that,
This liquid crystal cell is left in a vacuum to remove the air inside. At this time, since all two sides of the cell function as exhaust holes, the exhaust speed is significantly improved.

Thereafter, when the cell is heated until the chiral smectic liquid crystal becomes a liquid state or a cholesteric phase, the paste-like chiral smectic liquid crystal 15 coated on the lower substrate increases its fluidity and the lower substrate 13 It will spread upward and close the gap between the upper and lower boards. However, since the adhesive layer is formed even on the protruding portion of the lower substrate 13 and functions as a dam 14a, the liquid crystal does not widely flow out onto the lower substrate. Side surfaces of the lower substrate 13 and upper substrate 12 and the weir 14a
Due to the presence of the liquid crystal and the surface tension, the fluidized liquid crystal can be maintained in a raised state and prevented from flowing out of the weir 14a.

Next, lower the degree of vacuum outside the liquid crystal cell. Then,
Because the inside of the cell maintains a high vacuum, the fluidized liquid crystal that fills the gap between the upper and lower substrates is forced into the cell through this gap.
At this time, since the liquid crystal is maintained in a raised state as described above, the liquid crystal is effectively and easily introduced into the cell by external gas pressure. Further, since the gap 16 between the upper and lower substrates extends over all two sides of the cell and also functions as a liquid crystal injection hole, the liquid crystal filling speed can be greatly improved.

After filling the liquid crystal, an injection hole sealing material such as silicone rubber adhesive is pushed into the gap between the upper and lower substrates used as the liquid crystal injection hole 16 to seal the cell and complete the smectate liquid crystal element.

FIG. 5 shows another embodiment.

In FIG. 5, 52 is an upper substrate, 53 is a lower substrate, 54 is an adhesive layer, 54a is a weir, and 55 is a chiral smect liquid crystal. This is the same as the embodiment shown in FIG. 1 in that they are bonded together while maintaining a constant interval.

However, the adhesive layer 54 is provided around the overlapping portion of the upper substrate 52 and the lower substrate 53, and only a part of it is cut out to form the liquid crystal injection hole 56, and the weir 54a is not bonded. The difference is that it is provided separately from layer 54.

The weir 54a is located near the liquid crystal injection hole 56 and the lower substrate 53.
A silicone rubber adhesive or the like is formed on the extension part so as to extend in a direction substantially perpendicular to the opening surface of the injection hole 56. The weirs 54a are provided on both sides of the injection hole 56 so as to be in contact with the adhesive layer 54, and the glue-like chiral smect liquid crystal is
It is applied on the lower substrate 53 between the book dams near the injection hole 56. After that, by vacuuming and heating,
Liquid crystals have increased fluidity, but due to surface tension, weir 54
a and the side surface of the upper substrate 52 in a raised state and spread along the side surface of the upper substrate, so that the end of the weir 55 opposite to the injection hole 56 is opened, as shown in FIG. Even if the weir is closed, the liquid crystal will not flow out from the opening of this weir, and there is no need to keep it closed. Next, by lowering the degree of vacuum, injecting chiral smectic liquid crystal, and sealing the injection hole 56, a smectic liquid crystal element is completed.

In this embodiment as well, the weir 54a may be made of the same material as the adhesive layer 54, for example, an epoxy adhesive, and may be formed simultaneously with the adhesive layer 54 by a method such as screen printing. In addition, the liquid crystal injection hole is not placed on the side of the cell, but on the upper substrate 12, 52 or the lower substrate 13.
53 may be formed by making a hole.

Furthermore, although the above embodiments have only been described with respect to chiral smectic liquid crystals, it goes without saying that the method of the present invention can also be applied to other smectic liquid crystals that are pasty at room temperature.

If the liquid crystal is injected from multiple locations on the left and right, as in the embodiment shown in FIG. 1 or FIG. Can be filled.

〔Effect of the invention〕

The manufacturing method of the present invention involves coating a smectate liquid crystal on a substrate near a liquid crystal injection hole provided in a liquid crystal cell, placing the liquid crystal cell in a vacuum to remove air inside, and then heating the liquid crystal cell. The liquid crystal injection hole is increased by increasing the fluidity of the smectic liquid crystal, thereby blocking the liquid crystal injection hole, and after that, the degree of vacuum outside the liquid crystal cell is lowered and liquid crystal is injected, and then the liquid crystal injection hole is filled with a sealing material. Therefore, even if the cell gap is very small or the smectic liquid crystal is pasty, the liquid crystal can be injected into the cell very easily and in a short time.

[Brief explanation of drawings]

FIG. 1 is a plan view of a smectic liquid crystal element for explaining the manufacturing method of the present invention, FIG. 2 is a process block diagram showing an embodiment of the present invention, and FIG.
FIGS. A, B and FIG. 4 are explanatory diagrams showing molecular alignment of a chiral smectic liquid crystal, and FIG. 5 is a plan view of a smectic liquid crystal element for explaining another embodiment of the present invention. 12, 52... Upper substrate, 13, 53... Lower substrate, 14, 54... Adhesive layer, 14a, 54a...
Weir, 15, 55... chiral smect liquid crystal, 16, 56... liquid crystal injection hole.

Claims (1)

[Claims] 1. A step of forming a liquid crystal cell by bonding the periphery between the upper and lower substrates, at least one of which is transparent, with an adhesive layer to form a gap, and a step of forming a liquid crystal cell on the substrate near the liquid crystal injection hole provided in the liquid crystal cell. A step of applying a smectic liquid crystal, a step of placing the liquid crystal cell in a vacuum and eliminating air inside, and then heating the liquid crystal cell to increase the fluidity of the smectic liquid crystal, thereby filling the liquid crystal injection hole. A method for manufacturing a smectic liquid crystal element, comprising a step of blocking, a step of lowering the degree of vacuum outside the liquid crystal cell, and a step of filling the liquid crystal injection hole with a sealing material. 2. The method of manufacturing a smectic liquid crystal element according to claim 1, wherein liquid crystal injection holes are formed on opposite sides of the liquid crystal cell, and liquid crystal is injected from both sides of the liquid crystal cell.