JPS63188118A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To form a clear display and image by dispersing resin spacers whose diameter is larger than a gap width between two substrates at a normal temperature, and glass fiber spacers, whose diameter is smaller than said gap width, in liquid crystal and allowing spacers to follow up the volume change of a liquid crystal layer at a high temperature as well as a low temperature. CONSTITUTION:Resin spacers 41 and glass fiber spacers 42 control the gap width between two substrates 21 and 22, namely, the thickness of a liquid crystal layer 1, and rein spacers 41 have a diameter D1 in an initial state and have such elasticity that they are deformed up to the diameter D2 of glass fiber specers 42 when an external stress is applied. That is, the diameter D1 of resin spacers 41 is larger than the thickness of the liquid crystal layer 1 and the diameter D2 of glass fiber spacers 42 is smaller than this thickness. Since resin spacers having the diameter larger than the thickness (d) of the liquid crystal and glass fiber spacers having the diameter smaller (d) are dispersed in liquid crystal, spacers follow up the volume change of the liquid crystal layer in the negative pressure state by deformation of resin spacers, and the liquid crystal is uniform throughout between substrates.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to liquid crystal devices such as liquid crystal displays and liquid crystal shutters in which liquid crystal is sealed in the gap between two substrates. Regarding control.

(Prior Art and its Problems) Liquid crystal devices such as liquid crystal display devices and liquid crystal shutters are frequently used as output display devices for watches and calculators, and as image forming parts of image forming devices. In the future, the demand for them will continue to increase, and they are being used in many fields, including car instruments, where they are used under severe weather-resistant conditions.

As shown in FIG. 3, a liquid crystal display device, which is an example of a conventionally well-known liquid crystal device, has a liquid crystal layer 1 formed by two substrates 21 and 22 having means 23 and 24 for applying an electric field to the liquid crystal layer 1 and alignment means 25 and 26. was enclosed. The thickness of the liquid crystal layer 1 was controlled by a sealing material 3 disposed around the substrates 21 and 22 and glass fiber spacers 4 dispersed in the liquid crystal N1. Although its thickness varies depending on the liquid crystal material of the liquid crystal layer l, it is generally about 5 to 15 μm, so a glass fiber spacer 4 is used to control the thickness.
In this case, a substantially cylindrical body having a diameter substantially the same as the above-mentioned thickness was used.

At room temperature, no internal or external stress is acting on the liquid crystal N1 enclosed by the substrates 21 and 22.

However, the liquid crystal display device having the above-mentioned configuration has a decisive problem in that it is impossible to display clearly in an environment where temperature changes are severe.

That is, the volume change rate due to heat of the liquid crystal layer 1 is about three orders of magnitude larger than that of the glass fiber spacer 4, so in a high temperature region of around 60°C, for example, the thickness of the liquid crystal layer 1 decreases due to thermal expansion of the liquid crystal. becomes larger than the diameter of the base If! 21.22 has an inherent distortion,
Warpage occurs, and color unevenness occurs due to differences in the thickness of the liquid crystal Nl.

Further, for example, in a low temperature region of around -20° C., the thickness of the liquid crystal JW1 becomes extremely small due to the diameter of the glass fiber spacer 4 due to thermal contraction of the liquid crystal, and vacuum bubbles are generated in the liquid crystal Nl. Even if the vacuum bubble returns to room temperature, the liquid crystal N
1, it is difficult to eliminate, and the display area is dotted with black dots.

(Objective of the present invention) The present invention has been devised in view of the above-mentioned problems, and its purpose is to provide spacers with a spacer capable of controlling the volume change of the liquid crystal layer not only at room temperature but also at high and low temperatures. It is an object of the present invention to provide a liquid crystal device that provides followability and is capable of clear display and image formation.

(Specific means for solving the problem) In the liquid crystal device, a resin spacer with a diameter larger than the gap width between the two substrates at room temperature and a resin spacer with a smaller diameter are included in the liquid crystal. The reason is that the glass fiber spacers are dispersed, and the difference in diameter between the resin spacer and the glass fiber spacer is set to be 0.3 to 2.0 μm.

(Example) Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a partial sectional view of a liquid crystal display device which is an example of the liquid crystal device of the present invention. Note that the same parts as in FIG. 3 are given the same reference numerals. A liquid crystal display device includes a liquid crystal layer 1, two substrates 21 and 22 sandwiching the liquid crystal layer 1, and a substrate 2 for sandwiching the liquid crystal layer 1.
1 and 22.

The liquid crystal layer 1 is a twisted nematic liquid crystal obtained by mixing a predetermined optically active substance into a nematic liquid crystal, or a liquid crystal material having a smectic phase.

The substrates 21 and 22 are made of glass, transparent resin, etc.
Electrodes 23 and 24 that apply an electric field to the liquid crystal layer 1 for display purposes are adhered to the inner surface in contact with the liquid crystal N1 in a predetermined shape.

Furthermore, alignment films 25 and 26 for determining the alignment of liquid crystal molecules in the liquid crystal layer 1 are deposited on the electrodes 23 and 24. The alignment films 25 and 26 are formed, for example, by applying a polyimide resin to a thickness of about 1.500 mm and rubbing in a predetermined direction.

The sealing material 3 seals the liquid crystal material sandwiched between the substrates 21 and 22, and is made of thermosetting resin such as epoxy resin.

Here, the resin spacer 41 and the glass fiber spacer 42 control the gap width between the two substrates 21 and 22 and the thickness of the liquid crystal layer l. The resin spacer 41 has a diameter D1 in its initial state, and has elasticity that allows it to deform to the diameter Dt of the glass fiber spacer 42 when external stress is applied.

For example, divinylbenzene copolymer is used as the material.

The characteristic feature of the present invention is that the diameter of the resin spacer 41 is larger than the thickness of the liquid crystal layer l, and the diameter Dz of the glass fiber spacer 42 is smaller than the thickness of the liquid crystal Jil.

That is, the resin spacer 41 is pressed by both substrates 21.22 and is in a deformed state or the alignment film 25 on the substrate 21.22.
．． Some parts are at mag 26.

First, the sealing material 3 is attached to the periphery of the three substrate sides of the substrate 21.22 on which the electrodes 23.24 and the alignment films 25.26 are adhered.
is applied using a thick film method, etc. Next, two boards 21 and 22
A resin spacer 4 is placed on one board side to define the gap.
1 and glass fiber spacers 42 in predetermined amounts. Then, the other substrate is superimposed so that the inner surfaces of the two substrates 21 and 22 face each other, and they are bonded under heat and pressure (Fig. 2 (a)
(see l). The glass fiber spacer 42 plays the role of maintaining the gap between the two substrates 21 and 22 during this heat and pressure bonding. The glass fiber spacer 42 serves as a pillar supporting the two substrates 21 and 22, and the resin spacer 4
Define the limits of deformation of 1.

As a result, the effect of stress due to heat and pressure on the resin spacer 41 is minimized, and a predetermined elasticity can be maintained. Note that the resin spacer 41 has the same height as the diameter D2 of the glass fiber spacer 42 due to deformation.

Next, after both substrates 21 and 22 are joined, when the pressure is released, the gap between the two substrates 2L22 is defined by the diameter DI of the restored resin spacer 41. And seal material 3
A liquid crystal material is injected from a liquid crystal injection port (not shown) formed in a part of the substrate to form a liquid crystal layer 1 (see FIG. 2(b)).

Next, in order to make the thickness of the liquid crystal layer smaller than the diameter D1 of the resin spacer 41 and larger than the diameter D2 of the glass fiber spacer 42 due to the above-mentioned structure, a predetermined pressure is applied from the substrate 21.22. The liquid crystal injection port is hermetically sealed (see Figure 2 (C).
)reference).

When sealing the injection port of the liquid crystal display device manufactured as described above, a pressure sufficient to deform the resin spacer 41 was applied to the liquid crystal layer 1. Therefore, the liquid crystal layer 1 was subjected to a pressure release (a force that pulls the glass toward the inner surface). ) is working. Further, an elastic force acts on the resin spacer 41 to return the deformed state to the initial state.

In this normal temperature state, as shown in FIG. 1(a), the thickness of the liquid crystal layer 1 is d, and the two substrates 21 and 22 are supported by the deformed resin spacer 41. That is, the height of the deformed spacer 41 (the length of the minor axis in the drawing) also becomes d (the diameter in the initial state is nl:I)1>d). At this time, the pressure relief acts, pulling the substrates 21 and 22 toward the inner surface, and
The liquid crystal layer 1 is made uniform over the entire surface of the substrate by the resin spacer 41 supporting 1.22.

Now, when the liquid crystal display device is placed in a high temperature state, volumetric expansion occurs in the liquid crystal layer 1. FIG. 1(b) is a partial cross-sectional view of a liquid crystal display device in a state where the volume expansion is maximum and which enables clear display. It becomes the same as the diameter D1. This state is a critical point at which the above-described pressure relief applied to the liquid crystal layer 1 is eliminated. If the volumetric expansion occurs in the liquid crystal layer 1 any more, the above-mentioned pressure relief is canceled and expansion force is applied from the liquid crystal layer 1 side to the substrate 21.22 as in the prior art, causing distortion and warping of the substrate 21.22. occurs.

In other words, according to the present invention, the liquid crystal layer 1 is removed by the action of the resin spacer 41 and the pressure reduction on the liquid crystal layer 1 in the range from the thickness d of the liquid crystal layer 1 at room temperature to the initial diameter D1 of the resin spacer 41. 1 can be maintained at a uniform thickness over the entire surface of the substrate.

Furthermore, when the liquid crystal display device is placed in a low temperature state, volumetric contraction occurs in the liquid crystal layer 1. FIG. 1 (C1 is a partial cross-sectional view of a liquid crystal display device in a state where the volumetric shrinkage is maximum and can provide a clear display.

The thickness dl of the liquid crystal layer 1 is the same as the diameter Dt of the glass fiber spacer 42. At this time, the resin spacer 41 is more deformed than at room temperature, or is partially embedded in the alignment film 25, 26, and its height is the thickness dA of the liquid crystal layer l! is the same as That is, the resin spacer 41 needs to have elasticity that allows it to be deformed to at least the diameter D2 of the glass fiber spacer 42.

In this state, the above-described pressure relief and volume shrinkage force are generated in the liquid crystal layer 1, but the two substrates 21 and 22 are supported by the glass fiber spacer 42 whose volume change rate is extremely small.

If volumetric contraction occurs in the liquid crystal layer 1 further than this, vacuum bubbles will be generated in the liquid crystal layer 1 as in the prior art, and black non-display points will be scattered in the display area of the liquid crystal display device.

In other words, according to the present invention, the liquid crystal layer 1 can be uniformly distributed over the entire surface by removing pressure from the liquid crystal layer 1 and by using the resin spacer 41 in the range from the thickness d of the liquid crystal N1 at room temperature to the diameter D2 of the glass fiber spacer 42. It can be kept thick.

Next, resin spacer 41 and glass fiber spacer 4
The diameter and spray amount of No. 2 will be explained in detail.

The diameters D1 and D2 of the resin spacer 41 and the glass fiber spacer 42 vary depending on the thickness of the liquid crystal layer 1 of the liquid crystal display device and the temperature range that ensures clear display, but if the diameter Dt of the glass fiber spacer 42 is X μm, The diameter D+ of the spacer 41 is set from (x+0.3) to (x+
2.0) It is desirable to set it to μm.

Assuming that the diameter of the resin spacer 41 is less than (X+0.3) μm, the resin spacer 41 is used to apply pressure relief to the liquid crystal Nl.
When the glass fiber spacer 42 is slightly deformed (FIG. 2(C)), the glass fiber spacer 42 is already in contact with the side substrate 21, 22,
Or, due to some volume shrinkage of the liquid crystal layer l, the side substrate 21.2
2. Define the gap.

That is, sufficient compensation in the low temperature region cannot be achieved.

In addition, when the diameter of the resin spacer 41 is (x+2.0) μm or more, when the two substrates 21 and 22 are bonded under heat and pressure (
(FIG. 2+al), stress such as heat and pressure more than necessary is applied to the resin spacer 42, and the resin spacer 42 lacks a predetermined elasticity, thereby narrowing the temperature compensation range.

Note that the above-mentioned diameter is an average value, and it is optimal if it is uniform, but it does not matter if a very small number of diameters are exempted from this range.

Next, resin spacer 41 and glass fiber spacer 4
The amount of spraying 2 is based on the thickness of the substrate 21, 22 and the thickness d of the liquid crystal layer 1.
Depending on the situation, the glass fiber spacer 42 does not break when the two substrates 21.22 are bonded under heat and pressure, and even when the substrates 21.22 are bonded with slightly distorted stress.
An amount of application is required that can act as a support to maintain uniformity between the layers. For example, 4 pieces/mrd or more is sufficient.

The resin spacer 41 is heated within a temperature range that ensures clear display.
It is necessary to have the above-mentioned elasticity and to have an amount of spraying that can follow the liquid crystal layer 1. For example, it is 10 to 50 pieces/md. That is, 10
50 pieces/m in the high temperature range when it is less than 50 pieces/m rrr
If it is more than m cd, the followability in the low temperature region will deteriorate.

Note that although the upper limit of the glass fiber spacer 42 is not particularly set, it can be set to a level that does not interfere with clear display in consideration of cost.

Although the present invention uses a liquid crystal display device in the embodiment, it can also be widely applied to liquid crystal shutters and liquid crystal switches for forming images on photoreceptors of copying machines, printers, and the like.

(Effects of the Invention) As described above, in the liquid crystal device of the present invention, when d is the gap between two substrates at room temperature, that is, the thickness of the liquid crystal layer, the liquid crystal has a diameter larger than d. supporting pacer and d
Because the glass fiber spacer has a smaller diameter than By deforming the resin spacer, it follows the volume change of the liquid crystal layer in a depressurized state, and it is possible to achieve a uniform liquid crystal layer over the entire surface of the board, enabling clear display without any color unevenness or black spots or vacuum bubbles. becomes.

[Brief explanation of the drawing]

FIG. 1(C) is a partial sectional view in the high temperature region, and FIG. 1(C) is a partial sectional view in the main manufacturing process of the same low temperature. It is a partial sectional view of the display device. 1... Liquid crystal layer 21.22... Substrate 23.24... Electrode 25.26... Alignment film 3... Seal material 41... Resin spacer

Claims (3)

[Claims] (1) In a liquid crystal device in which a liquid crystal is sealed in a gap between two substrates, a resin spacer with a diameter larger than the width of the gap between the two substrates at room temperature and a glass with a smaller diameter are included in the liquid crystal. A liquid crystal device characterized by dispersing fiber spacers. (2) The liquid crystal device according to claim 1, wherein the difference in diameter between the resin spacer and the glass fiber spacer is 0.3 to 2.0 μm. (3) The resin spacer has elasticity that can be deformed to at least the diameter of the glass fiber spacer, and
2. The liquid crystal device according to claim 1, wherein the liquid crystal device is always in contact with the two substrates.