JPH01210929A - Liquid crystal display device and liquid crystal display element to be used in said device - Google Patents

Abstract

PURPOSE:To obtain the title device having high density by constituting the device of a liquid crystal display element inserting a film-shaped liquid crystal layer between a pair of substrates provided with electrodes and a driving device constituted of a laser device and a voltage impressing device. CONSTITUTION:A liquid crystal display element is constituted of a hardened product obtd. by setting a photosettable compd. such as monoacrylate, diacrylate, etc., forming a network structure or being distributed in a form of capsules, a nematic or smectic liquid crystal material, etc., in the voids of the hardened product, and a film shaped liquid crystal layer contg. a dye in the hardened product or in the liquid crystal material and being inserted between a pair of substrates provided with electrodes. When the display element is written, the writing is executed at high temp. by scanning with a laser device. When the written display is erased, written information is erased simultaneously by impressing electric voltage to the electrodes with a voltage impressing device. Thus, a large sized display device having many picture elements is obtd. easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device in which a liquid crystal substance is dispersed and held in a cured material matrix, and a liquid crystal display element suitable therefor.

[Prior art] Recently, H.G. Craighead et al.
ys, 1. ett, .

40 (1) 22 (1982), by taking advantage of the refractive index anisotropy of liquid crystal, a film-like liquid crystal in which a liquid crystal substance is dispersed in a matrix of a cured resin is placed between a pair of electrode-attached substrates. Sandwiched liquid crystal display elements are attracting attention.

Specifically, these methods use a film-like liquid crystal in which a porous body is impregnated with a liquid crystal material or a liquid crystal material is encapsulated in microcapsules, and the refractive index of the liquid crystal is changed depending on the presence or absence of voltage application. Transmission and scattering are controlled by adjusting the refractive index of the constituting porous body and the outer wall of the microcapsule.

This film-like liquid crystal is a useful method that can overcome the drawbacks of the principle DS (dynamic scattering) mode and PC (phase change) mode without using a polarizing plate.

In addition, J. L. Ferguson and others developed film-like liquid crystals using nematic liquid crystals microencapsulated using polyvinyl alcohol (Japanese Patent Publication No. 58-58).
01631), N. Pearlman et al. (Japanese Patent Application Laid-Open No. 60-252687), and J. W. Doane et al.
et al. (Japanese Patent Publication No. 1983-502128) created a film-like liquid crystal obtained by dispersing and curing liquid crystal in an epoxy resin.

However, although these are suitable for overall transmission-scattering control such as in dimming applications, since they are basically transmission-scattering control, multiplex driving is difficult, and many It was not suitable for use in display devices that control pixels by turning them on and off.

[Problems to be solved by the invention] Also, JP-A-55-96922 and JP-A-62-231
No. 930 discloses that microencapsulated film-like liquid crystal is sandwiched between a pair of substrates with electrodes and voltage is applied to control the polarization of the liquid crystal and drive the liquid crystal.

However, if the microcapsule is sandwiched between substrates, it tends to be difficult to print thinly, and it is difficult to control a uniform thickness. In addition, since the substrates are sandwiched, it is difficult to maintain a uniform gap between the substrates, and the drive voltage is high to drive only by voltage application, making multiplex driving difficult.

For this reason, it has been difficult to realize a display device having a large number of pixels using film-like liquid crystals.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes a film-like liquid crystal layer in which a pigment and a liquid crystal substance are dispersed and held in a matrix of a cured product, which is attached to a pair of electrodes. A liquid crystal display device comprising: a liquid crystal display element sandwiched between substrates; and a driving device comprising a laser device for driving the liquid crystal display element and a voltage application device for applying voltage to electrodes.
A liquid crystal display element is formed by sandwiching a film-like liquid crystal layer in which a pigment and a smectic liquid crystal substance are dispersed and held in a cured matrix between a pair of substrates with electrodes, a laser device for writing on the liquid crystal display element, and a voltage applied to the electrodes. A liquid crystal display device comprising: a driving device comprising a voltage applying device for applying and erasing all at once; The film-like liquid crystal layer, in which the pigment and the liquid crystal material are dispersed and held in the cured matrix, is divided into sections for each color in a desired pattern and sandwiched between a pair of electrode-attached substrates. The present invention provides a liquid crystal display element characterized by the following.

According to the present invention, it is possible to easily obtain a high-density display device having a large number of pixels using a film-like liquid crystal that is easy to manufacture into a large-area device.

In the present invention, a film-like liquid crystal layer in which a pigment and a liquid crystal substance are dispersed in a cured material matrix is used, and this is sandwiched between a pair of electrode-attached substrates to form a liquid crystal display element, and a laser device for driving the liquid crystal layer is used. A driving device comprising a voltage applying device for applying a voltage to the electrode is provided.

In particular, when a film-like liquid crystal layer using a smectic liquid crystal material is used as the liquid crystal material, and a laser device is used to scan the liquid crystal display element to thermally write and erase, a voltage is applied to the electrodes by a voltage application device. It is preferable to use a liquid crystal display device in which the voltage is applied and erased all at once.

In this film-like liquid crystal layer, in which pigment and liquid crystal substance are dispersed and held in the matrix of the cured product, the cured product obtained by curing the curable compound exists in the form of a network or capsule, and the liquid crystal substance exists in the gaps or voids. The pigment may be incorporated into a cured product or may be present in a liquid crystal material.

This curable compound may be any compound that can be cured to form a network-like or capsule-like cured product, and materials that form various polymers can be used.

In the present invention, it is preferable to use a photocurable compound and photocure it to form a matrix of the cured product.

Specific examples of this photocurable compound include monoacrylate, diacrylate, N-4ta acrylamide,
N-vinylpyrrolidone, styrene and their derivatives,
polyol acrylate, polyester acrylate,
Examples include compounds having monofunctional and polyfunctional vinyl groups such as urethane acrylate, epoxy acrylate, silicone acrylate, fluoroalkyl acrylate, acrylate having a polybutadiene skeleton, isocyanuric acid skeleton, or hydantoin skeleton, unsaturated cycloacetal, etc. .

The liquid crystal substances used in the present invention include nematic liquid crystal substances, smectic liquid crystal substances, etc., and they may be used alone or as a composition, but in order to satisfy various performance requirements such as operating temperature range and operating voltage, It can be said that it is more advantageous to use a composition.

In particular, when performing thermal writing by scanning with a laser device, it is preferable to use a smectic liquid crystal material having a smectic A phase. In this case, normal smectic A
Like a smectic liquid crystal display device having a phase, a laser device is used for writing, and a voltage application device can be used for erasing by applying a voltage all at once.

Furthermore, when the cured material constituting the matrix is dissolved in the liquid crystal material by heating, it can be used in combination with a nematic liquid crystal material and driven using a laser device and a voltage application device in combination.

Specifically, when using a normal nematic liquid crystal material with positive dielectric anisotropy, if the melted part is heated with a laser device and then cooled while a voltage is applied,
The liquid crystal molecules are aligned substantially perpendicular to the substrate, or nearly so. Thereby, in this state, the refractive index of the liquid crystal material is made to match the refractive index of the cured material, so that light is transmitted. On the other hand, in a portion that is cooled without applying a voltage, the liquid crystal molecules are almost randomly oriented. As a result, in this state, the refractive index of the liquid crystal material does not match the refractive index of the cured material, and light becomes scattered. As a result, when light is applied from one side and the image is projected, pixels where light is scattered become dark, pixels through which light is transmitted become bright, and an image is displayed.

According to this method, a high-density projection type liquid crystal display device can be easily obtained. This also applies when a smectic liquid crystal material having a smectic A phase is used.

In addition, if the polarization is sufficiently maintained, a pair of polarizing films can be sandwiched between them as in a conventional twisted nematic liquid crystal display device.

The pigment may be any pigment that can impart a desired color, and may be contained only in the cured product after curing, may remain in the liquid crystal material, or may be contained in both. Good too. By using three types of pigments, preparing a mixture of liquid crystal material, curable compound, and pigment for three ROB colors, that is, three types, and printing in a desired pattern, a large-area projection type liquid crystal display can be created. You can get the equipment.

In particular, by using a liquid crystal substance and a photocurable compound and undergoing a photocuring process, the liquid crystal substance and the cured product are fixed by phase separation, resulting in a structure in which the liquid crystal substance is scattered in the matrix of the cured product, and the liquid crystal The distribution of the cured product becomes uniform, and elements with excellent appearance quality and productivity can be easily produced.

When manufacturing the device of the present invention, the curable compound and the liquid crystal substance may be mixed in a ratio of about 5:95 to 75:25, and a viscous substance may be used instead of liquid.

In addition, the mixture of the curable compound and the liquid crystal substance for forming the film-like liquid crystal layer may be used alone or in combination with the curable compound and the liquid crystal substance. It may also contain a modifier for the element. Specifically, it contains crosslinking agents, surfactants, diluents, thickeners, antifoaming agents, adhesion agents, stabilizers, absorbents, polymerization accelerators, chain transfer agents, polymerization inhibitors, etc. good.

When manufacturing the device of the present invention, the mixture of the curable compound, liquid crystal substance, and pigment to be prepared may be a liquid or a viscous substance, as long as it is uniformly mixed, and the mixture is optimal depending on the method of manufacturing the device. All you have to do is choose something. For example, In, O, -
It is generally more convenient to inject in liquid form into a cell whose periphery is sealed by arranging glass substrates with transparent electrodes such as 3nO, SnO, etc. to face each other. When applying it to a substrate and trying to overlap opposing substrates, it is more convenient to use -m in a viscous state.

It is appropriate to set the inter-substrate gap to 7 to 40 .mu.m if operation is possible at 5 to 100 .mu.m, or considering applied voltage and contrast during on/off.

When a nematic liquid crystal material is used as the liquid crystal material and the refractive index of the cured product is made to match the ordinary refractive index (n,) or extraordinary light refraction* (n,) of the liquid crystal material, the material held on the substrate before curing is If the contents are uniformly dissolved, they are colorless and transparent, but after curing they become cloudy due to refractive index scattering caused by the unaligned liquid crystal material and the cured product. In the device of the present invention created in this way, when a voltage higher than the threshold voltage is applied, the liquid crystal substance begins to align, and the refractive index approaches that of the cured product, causing the transmittance to decrease. As a result, the refractive index matches that of the cured product, resulting in a highly transparent state.

Further, the refractive index of the cured product can be made to match the refractive index (n8) when the liquid crystal material used is randomly oriented.

Random alignment here means that all liquid crystal molecules are not aligned parallel or perpendicular to the substrate surface.
This indicates that the cured product is oriented in various directions due to the influence of the networks or capsules that make up the matrix of the cured product.

In this case, when no voltage is applied, the refractive index of the unaligned (randomly oriented) liquid crystal material and the cured product are the same, and therefore a transmissive state is exhibited. Conversely, when a voltage is applied, the liquid crystal material aligns and the refractive index of the liquid crystal (
No or ne) and the refractive index of the cured product obtained by photocuring no longer match, resulting in a scattering state a (that is, a cloudy state)
This will show the following.

In the present invention, by utilizing this phenomenon, after the liquid crystal material is heated by a laser and becomes transparent, it is cooled while applying a voltage or without applying a voltage, thereby making the material transparent.
Can cause scattering. Depending on the voltage application state during cooling, the transparent-scattering state does not change after cooling even if the voltage is turned off, allowing bistable driving as in the case of a smectic liquid crystal display element.

Note that if a material is used in which the liquid crystal molecules are not aligned in the matrix of the cured product, such as a mesh or a capsule, but are aligned on the substrate surface, it can also be used as a liquid crystal display device that supports polarization.

However, normally in such a film-like liquid crystal, when the voltage is turned off, the liquid crystal molecules tend not to align to the substrate surface but to the matrix surface of the cured product, and the liquid polymers appear to be oriented in random directions. In many cases, the polarization is disturbed when the voltage is turned off, so that it is preferable to use a transmission-scattering type.

Note that when matching the refractive index of this cured product and the refractive index (not nes nx) of the liquid crystal material used, it is preferable to match them completely; It is sufficient to match them to the extent that they do not cause any adverse effects. Specifically, it is preferable to keep the difference in refractive index to about 0.15 or less. this is,
The cured product is swollen by the liquid crystal substance, and the refractive index becomes closer to that of the liquid crystal substance than the original refractive index of the cured product, so even if there is a difference of this degree, almost all light is transmitted.

In the present invention, it is preferable to use a photocurable compound and photocure it to form a matrix of the cured product.

In the present invention, in the case of a monochromatic color, a mixture of a curable compound, a liquid crystal substance, and a pigment may be supplied all over the electrode-equipped substrate and cured.

In addition, in the case of multiple colors, a mixture of a curable compound, a liquid crystal substance, and a pigment for each color is applied to the electrode-attached substrate in the desired pattern and cured, and then the mixture is added to the cured product matrix. A film-like liquid crystal layer in which a pigment and a liquid crystal substance are dispersed and held may be provided in a desired pattern by dividing it into sections for each color. Specifically, a film-like liquid crystal layer in the three colors of RGB can be easily formed in a stripe or mosaic shape by a printing method or the like.

By using a plastic substrate as the substrate with electrodes,
A long liquid crystal display element using a continuous plastic film can be easily manufactured.

By using a film-like liquid crystal with a matrix of liquid crystal, pigment, and curable compound, it is possible to produce highly reliable liquid crystal display elements with low risk of short-circuiting between the upper and lower transparent electrodes even when the area is large. It can be easily manufactured. Note that in order to reduce unevenness in the state of light transmission, it is preferable that the substrate gap be constant to some extent. For this reason, it is preferable to arrange spacers for controlling the gap, such as glass particles, plastic particles, ceramic particles, etc. in the gap between the substrates. Specifically, a mixture of a curable compound, a liquid crystal substance, and a pigment containing a spacer for controlling the substrate gap may be supplied to the substrate 1-1, or a spacer may be supplied before or after supplying the mixture, and the other The substrates may be stacked on top of each other. In this case, by applying pressure after stacking them and then curing them, a more uniform gap between the substrates can be easily achieved.

Such a liquid crystal display element can be used as a large-area, high-density display element.

When the substrate of this liquid crystal display element is made of plastic or thin glass, a protective plate made of plastic or glass is laminated for further protection, or the substrate is made of tempered glass, laminated glass, etc.
Various applications are possible, such as wire-filled glass.

In particular, a plastic substrate is used as a substrate with electrodes to form a liquid crystal display element, electrode lead lines are attached, and this is placed between two glass plates slightly larger than the liquid crystal display element with an adhesive material layer such as polyvinyl butyral interposed between them. It is preferable to use the liquid crystal display element and the glass plate by holding them together and curing the adhesive material layer by heating or light irradiation to integrate the liquid crystal display element and the glass plate into a laminated glass shape. Among them, by using polyvinyl butyral as the adhesive material, it is possible to obtain a structure extremely similar to that of ordinary laminated glass.

To manufacture this liquid crystal display element, it is possible to prepare two substrates of a desired shape and combine them to manufacture the liquid crystal display element, or to use a continuous plastic film substrate, or to use a long glass substrate. It may also be manufactured by using a method of manufacturing and cutting it later.

As described above, the present invention uses a driving device consisting of a laser device and a voltage application device for applying a voltage to an electrode.
By driving, high-density display is easily possible.

This laser device may be any device that can locally heat and melt the film-like liquid crystal layer or cause a phase transition of the liquid crystal.

When applying a voltage for driving using a voltage application device, it is sufficient to apply an alternating current voltage that changes the alignment of the liquid crystal. Specifically, 10 to 100011 at 5 to 100V
An alternating current voltage of about z may be used as long as it changes the light transmission state of the element or a voltage that provides a constant orientation.

In addition, color filters can be used together with other displays such as ordinary TN liquid crystal display elements, electrochromic display elements, electroluminescence display elements, etc.
(It may be used as tl, and various applications are possible.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 100 parts of polyvinyl alcohol aqueous solution, 8 parts of Smectic A liquid crystal composition (RS-7J manufactured by BDH) and red U
0.4 parts of V ink (rllV161-Standard Red J manufactured by Toka Shiki Kagaku Co., Ltd.) and 0.008 parts of a photopolymerization initiator (Glocure 1116J manufactured by Merck & Co., Ltd.) were dispersed.This emulsified dispersion was dispersed into a 0.3 mm square. A mosaic pattern was printed on solid ITO and dried.

In addition, instead of the red UV ink, an emulsified dispersion containing a green UV ink (manufactured by Toka Dye Chemical Co., Ltd. r UV161-Standard Color Line) was placed in a 0.3+am square mosaic shape adjacent to the red UV ink using solid ITO. Printed on top and let dry. In addition, instead of the red UV ink, 0.3 part of an emulsified dispersion containing a blue UV ink (R UV161-Standard Buddhist statue, manufactured by Toka Dye Chemical Co., Ltd.) was used to print the red UV ink and green UV ink in a m-square mosaic. It was printed on the solid ITO of the unmarked area and dried.

In this way, a substrate was created on which red, green, and blue film-like liquid crystal layers were printed in a mosaic pattern.

This substrate was laminated with another ITO-coated substrate, and the ink was cured by UV irradiation to form a projection type liquid crystal display element.

Thermal writing was performed on this liquid crystal display element using a semiconductor laser, and a full-color image was displayed on the screen by illuminating it from the back side with a three-primary color wavelength fluorescent lamp.

Example 2 Instead of the polyvinyl alcohol aqueous solution of Example 1, 7
A projection type liquid crystal display element was prepared in the same manner as in Example 1 except that 100 parts of polyurethane latex was used.

Thermal writing was performed on this liquid crystal display element using a semiconductor laser, and a full-color image was displayed on the screen by illuminating it from the back side with a three-primary color wavelength fluorescent lamp.

Example 3 1 part of acrylic photopolymerizable resin, 1 part of smectic A liquid crystal composition (rS-7J manufactured by BDH), 0.5 part of red UV ink (uvtet-standard color red manufactured by Toka Dye Chemical Co., Ltd.) , and 0.01 part of benzoin isopropyl ether as a photocuring initiator were uniformly dissolved and printed on a plastic film with ITO in the same manner as in Example 1.

After that, add only the pigments to green and blue 71? A mixture using Group I was printed in the same manner as in Example 1 to create a substrate on which red, green, and blue film-like liquid crystal layers were printed in a mosaic pattern.

This substrate was laminated with another ITO-coated substrate, and UV was irradiated to cause photocuring and phase separation between the liquid crystal material and the matrix of the cured material, thereby producing a projection type liquid crystal display element.

Thermal writing was performed on this liquid crystal display element using a semiconductor laser, and a full-color image was displayed on the screen by illuminating it from the back side with a three-primary color wavelength fluorescent lamp.

Example 4 Glass plates were placed on both sides of the liquid crystal display element of Example 3 with polyvinyl butyral films interposed therebetween, and the glass plates were brought into close contact with the liquid crystal display element and imaged by heating and pressurizing them in an autoclave.

The device imaged in this way was safe against external pressure and had high reliability.

[Effects of the Invention] As described above, the present invention provides a novel liquid crystal display device, in which a film-like liquid crystal layer in which a liquid crystal substance and a pigment are dispersed and held in a cured matrix is attached to a pair of electrode-attached substrates. According to the present invention, it is possible to easily provide a liquid crystal display device which has a large area and displays a desired color.

In the present invention, by forming a film-like liquid crystal layer using a mixture of a curable compound, a liquid crystal substance, and an M material, productivity is excellent and a large liquid height display device can be easily manufactured.

In order to make a conventional liquid crystal display device colored, it is necessary to form a color filter above or below the electrodes of a substrate and to inject a liquid crystal material into a liquid crystal cell using such a substrate. In contrast, in the liquid crystal display device of the present invention,
This requires only one step of printing a mixture of a curable compound, a liquid crystal substance, and a pigment, resulting in extremely high productivity.

Furthermore, unlike ordinary liquid crystal materials, it is not in a liquid state after curing, so there is less risk of short circuits between substrates, and large-sized liquid crystal display devices, for example, 1 m square liquid crystal display devices, can be easily manufactured.

Furthermore, by providing a protective plate on at least one side of this substrate, safety is improved, and in particular, by providing protective plates on both sides, damage becomes less likely to occur.

Particularly, when a plastic substrate is used as a substrate, although productivity is good, the strength is poor, so that when the area is increased, the substrate is easily damaged or bent. Therefore, the effect of providing protective plates on both sides is great. Among these, by using a glass plate as a protective plate and bonding it with an adhesive material such as polyvinyl butyral, the structure is similar to laminated glass, making it safe and reliable.

The liquid crystal display device of the present invention is an element with excellent appearance quality and productivity, and is suitable for large-area, curved display, and is particularly suitable for projection-type liquid crystal display devices.

In addition to this, the present invention can be applied in various other ways as long as the effects of the present invention are not impaired.

Claims (3)

[Claims] (1) A liquid crystal display element consisting of a film-like liquid crystal layer in which a pigment and a liquid crystal substance are dispersed and held in a cured material matrix is sandwiched between a pair of electrode-attached substrates, a laser device for driving it, and a voltage applied to the electrodes. 1. A liquid crystal display device comprising: a voltage applying device for applying a voltage; and a driving device comprising a voltage applying device. (2) A liquid crystal display element consisting of a film-like liquid crystal layer in which a pigment and a smectic liquid crystal substance are dispersed and held in a cured material matrix is sandwiched between a pair of electrode-attached substrates, and a laser device and electrode for writing on the liquid crystal display element. 1. A liquid crystal display device comprising: a driving device comprising a voltage applying device for applying a voltage and erasing the data all at once. (3) A mixture of a cured physical compound, a pigment, and a liquid crystal substance is applied to a substrate with electrodes in a desired pattern and cured to form a film-like liquid crystal layer in which the pigment and liquid crystal substance are dispersed and held in the matrix of the cured substance. 1. A liquid crystal display device characterized in that the device is divided into compartments for each color in a desired pattern and sandwiched between a pair of electrode-attached substrates.