JPH04140717A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To obtain a high switching speed even when a liquid crystal cell is thick and a voltage is low by providing a layer of a composite body of liquid crystal and a transparent material between a couple of electrodes so that the both are mixed and one of them is dispersed. CONSTITUTION:As the transparent material, PMMA is obtained by using a liquid crystal material and ferroelectric liquid crystal is mixed with a solvent, stirred, and then an ultrasonic wave is applied to disperse the liquid crystal material uniformly. Then a transparent glass substrate which has an electrode patterned on a substrate is coated with the mixture of the liquid crystal and transparent material, the solvent is removed, and the other substrate where an electrode is formed is stuck. This liquid crystal device has the liquid crystal oriented at random while no voltage is applied between the electrodes provided to the upper and lower substrates and light is scattered. When a voltage is applied, on the other hand, the liquid crystal is oriented in a specific direction according to the direction of the electric field and electro-optical effect is generated by the anisotropy of the refractive index that the liquid crystal material has, thereby transmitting the light.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a liquid crystal enclosing film that can be formed over a large area, and provides an electro-optical device that has a wide field of view and is capable of producing moving images.

This liquid crystal device is used in electrical equipment for office automation (OA), such as laptop personal computers.

[Prior art]

Conventionally, liquid crystal display devices use nemastic liquid crystal.
＼ type and STN type liquid crystal only types have been put into practical use. Also, a device using only ferroelectric liquid crystal has been proposed.

However, these devices use polarizing plates on the front and back surfaces of the liquid crystal display device, and also involve an alignment process using an alignment film on the electrodes. On the other hand, as a method for producing a high-contrast liquid crystal display device without performing these alignment treatments, there is a known method in which liquid crystal or liquid crystal grains are dispersed in a polymer by encapsulation of liquid crystal, and this is made into a polymer film. There is. As the encapsulation material, gelatin, gum arabic, polyhinyl alcohol, etc. have been proposed. (Unexamined Japanese Patent Publication No. 58-501631. USP
(No. 4,435,047) These are encapsulated liquid crystal molecules or are aligned in the direction of an electric field by the application of a voltage, and have translucency when the refractive index of the liquid crystal and the refractive index of the polymer are equal.

Also, when the electric field is removed, the liquid crystal molecules become randomly arranged, and because the refractive index of the liquid crystal is different, light is scattered at the boundary,
It blocks the transmission of light and becomes cloudy.

[Invention or problem to be solved]

In such a liquid crystal device, 1) it can be driven at a low voltage, 2) the speed is sufficiently fast, 3) it can be used as a reflective liquid crystal device, 14) even at a cell pressure of 2.5 to 10 μm, o, i milliseconds ( The ability to drive at 100 u seconds or less is required as a practical characteristic.

No liquid crystal device has been proposed that satisfies these conditions and provides an optical response fast enough to display moving images without using a polarizing plate.

The present invention is intended to eliminate such drawbacks, and the details thereof will be described below.

[Means to solve the problem]

In order to simultaneously solve the above four problems, the present invention mixes both liquid crystal and transparent material in a layer having an electro-optic effect generating layer (composite of liquid crystal and transparent material) between a pair of electrodes. , and one of them is decentralized.

In addition, the present invention achieves high speed response by adding ferroelectric liquid crystal as a dispersed liquid crystal material to a transparent substance,
The present invention also relates to a liquid crystal device that increases the amount of transmitted light by four times without using a polarizing plate.

Smectic liquid crystal is used as the liquid crystal material.

Moreover, this smectic liquid crystal has ferroelectricity. This smectic liquid crystal is a blend of 10 to 20 liquid crystal materials (a mixture of a plurality of single materials), or a liquid crystal material in which at least one of the liquid crystal materials (single material) contains fluorine.

Further, as the light-transmitting substance, a highly light-transmitting resin, usually an organic resin, is used.

It may also be an organic resin that is cured by ultraviolet light, such as polymethylmethacrylate-1-(PMMA). In addition, by mixing a fluorine compound ferroelectric material, such as polyvinylidene fluoride (1 to 100%), in a transparent material, the refractive index of the transparent resin matches that of the liquid crystal material when an electric field is applied. Encouraging others is effective.

In addition, these translucent substances and smectic liquid crystals are
80-80. /20 was mixed. The present invention is accomplished by applying an alternating current electric field to these.

The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples and can be applied to a wide range of applications.

〔Example〕

In this example, a ferroelectric liquid crystal having the characteristics described below was mixed in a solvent using PMMA as a liquid crystal material as a translucent substance, half-stirred, and ultrasonic waves were applied to make the liquid crystal material uniform. Made it disperse.

At this time, heating is performed at the same time, and the liquid crystal material or Tokichi phase (liquid) is
It was very effective to disperse the material uniformly by stirring and applying ultrasonic waves, and then lowering the temperature to the temperature of the liquid crystal phase.

Next, this mixture of liquid crystal and light-transmitting material was applied onto a transparent glass substrate on which electrodes had been patterned, the solvent was removed, and the other substrate with electrodes formed thereon was laminated.

If this bonding is performed in a vacuum device, the solvent can be removed and the air bubbles between the substrate, the liquid crystal, and the light-transmitting material mixture can be removed at the same time.

In the liquid crystal device manufactured in this manner, when no voltage is applied between the electrodes provided on the upper and lower substrates, the liquid crystal is randomly oriented and light is scattered. Furthermore, when a voltage is applied, the liquid crystal aligns in a specific direction according to the direction of the electric field, and due to the anisotropy of the refractive index of the liquid crystal material, an electro-optical effect occurs, allowing light to pass through. At this time, when the refractive index value of the liquid crystal material in the light transmission direction when an electric field is applied matches the refractive index value of the light-transmitting material, the most light is transmitted.

In this example, the liquid crystal material used is a liquid crystal material containing at least an ester-based ferroelectric liquid crystal material, and its phase series is Iso-5mA-3mC"-Cry, and its transition temperature is Iso-5mA-3mC"-Cry. -3mA-3mC"-Cr7 40°C 36.7°C o'C, the dielectric constant anisotropy was positive, and the refractive index anisotropy value Δn was about 0.2. The value of spontaneous polarization is 12nC
/cnl'.

〔effect〕

Compared to the case of using a conventionally known TN liquid crystal, the present invention has the advantage that even if the electrode spacing is 5 to 10 μm thick,
Moreover, its switching speed is 40 μsec or less, which is more than 100 times faster, and since it uses liquid crystal material or smectic liquid crystal, it has a dielectric property with a relative dielectric constant of 10 to 100, and as a result, the same electric field However, the force exerted on the liquid crystal to force the molecules to normalize is very strong.

As a result, a high switching speed can be achieved even with a low electric field strength, ie, a large thickness of the liquid crystal cell, and a low voltage.

In conventional ferroelectric liquid crystals using polarizing plates, the cell thickness was extremely thin at 1.3 to 2.3 μm. However, because the thickness was too narrow, short circuits occurred between the upper and lower substrate electrodes due to dust, etc., which caused problems in practical use. If this was set to 2.5 to 10 μm, for example 5 μm, the generation rate of this noyote would be reduced, the electric field strength between the substrates would be reduced, and a switching speed of 100 μsec or less could be obtained.

Furthermore, since no polarizing plate is used, the amount of light transmitted through the liquid crystal device can be increased four times compared to conventional devices requiring polarizing plates.

Claims (1)

[Claims] 1. A pair of substrates having electrodes, at least one of which is translucent, and an electro-optic effect generating layer supported between the substrates, the electro-optic effect generating layer being made of a smectic liquid crystal material. A liquid crystal device characterized by having a transparent substance. 2. A liquid crystal device according to claim 1, wherein the smectic liquid crystal has a chiral smectic layer.