JPS62203123A - Flexible liquid crystal display element - Google Patents

Abstract

PURPOSE:To hold the thickness of a thin liquid crystal layer uniform with accuracy, to obtain a liquid crystal display surface of large area or optional desired size or in an optional desired shape,and to facilitate handling by fixing a weir between flexible substrates. CONSTITUTION:A transparent electrode film 2, an oriented film 4, cells 5 of a liquid crystal material sectioned by a weir 4, an oriented film 6, a transparent electrode film 7, and a flexible substrate 8 are arranged on a flexible substrate 1 in this order. The weir 4 needs to be adhered or fixed completely to at least one substrate side surface, e.g. entire oriented films 3 and 6 by a printing method, etc., and not merely sandwiched between the substrates. The weir 4 may be sectioned in, for example, a proper shape, e.g. triangular or hexagonal shape in addition to a square and a rectangular shape, but the shape needs to form continuous cells in a matrix.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flexible liquid crystal display element, particularly a liquid crystal display element suitable for displaying a large area or any desired shape or size.

[Conventional technology] In recent years, liquid crystal display devices have become increasingly larger in area, but those using conventional glass substrates have disadvantages in terms of impact resistance, weight, workability, etc. There are high hopes for the practical application of flexible transparent substrates.

By the way, one of the important techniques in manufacturing liquid crystal display devices is to maintain a uniform thickness of liquid crystal material between substrates, and this technique is particularly important in the case of flexible substrates. To this end, conventional methods have been proposed such as using fibers, metal oxide particles, polymer microbeads, mesh-like thin films, porous polymer films, etc. as spacers, or forming ribs or supports in places on the substrate. However, each has drawbacks in terms of processability, uniformity, long-term stability, liquid crystal behavior characteristics, etc., and each has limitations on usage conditions.

Furthermore, in conventional liquid crystal display devices, the retained liquid crystal material forms a continuous layer between the substrates, and the sides of the substrates must be completely sealed to prevent leakage from the sides. For this purpose, it is extremely difficult to continuously encapsulate a liquid crystal material between long substrates and then cut the substrates at arbitrary positions to produce display elements of arbitrary sizes and shapes.

[Problems to be Solved by the Invention] Therefore, the purpose of the present invention is to solve the above-mentioned conventional difficulties,
It can easily create flexible, large-area liquid crystal displays, and is particularly effective when it is necessary to maintain a thin liquid crystal layer of several microns in thickness with high accuracy and uniformity, such as when using ferroelectric materials. An object of the present invention is to provide a flexible liquid crystal display element.

Another object of the present invention is to be able to efficiently manufacture a continuous long display element, to prevent liquid crystal material from leaking out even without the need for a special seal, and to produce a display element of any desired size and shape. An object of the present invention is to provide a flexible liquid crystal display element that is economical, easy to process, and easy to handle.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides that, instead of the conventional method of holding a liquid crystal material between a pair of substrates as a continuous layer using a spacer, one of the substrates is A liquid crystal material is encapsulated independently from each other in a number of small cells completely separated by a matrix-like continuous weir of uniform thickness made of a polymeric material and fixed between flexible substrates.

Note that here, the weir is not simply sandwiched between the substrates, but is fixed to the substrates by means such as printing.

Transparent flexible substrates used in the present invention include polyester, polycarbonate, polysulfone, polyethersulfone, polyetherketone, polyphenylene sulfide, polyetherimide, polyallyl ester, polyacrylonitrile, polyvinyl fluoride, polyvinylidene fluoride, and polyester. Transparency of acetate, etc., chemical resistance (chemical resistance to liquid crystal material alignment film coating chemicals, etc.)
A film or sheet made of a polymeric material having excellent heat resistance (heat resistance in processes such as transparent electrode vapor deposition 9 peripheral resin heat sealing) is preferable.

Among these, non-grade polymeric materials with a small birefringence are particularly preferred because they do not cause coloring due to interference and provide a wide viewing angle.

Generally, these film sheets have a thickness of 50 mm.
~300 μm is used.

The transparent electrode formed on the surface of the flexible substrate may be made of metal oxides such as indium, tin, cadmium, antimony, composite oxides of these metals, or gold,
It is possible to use palladium or the like made by vapor deposition or sputtering to a thickness of usually 100 to 2,000, or a known material such as an electropolymerized film of polypyrrole, polythiophene, or the like. As in the case of conventional liquid crystal display elements, the transparent electrode is formed as a so-called pattern electrode or an x-y matrix electrode on the whole or part of the substrate on the side that comes into contact with the liquid crystal.

Furthermore, an alignment film for aligning the liquid crystal substance can be formed on the transparent electrode surface of the flexible substrate, if necessary. Such an alignment film is usually made of polyimide,
By diluting and dissolving epoxy, polyamide, polyester, polyisocyanate, polyvinyl alcohol, polybutadiene, polyisoprene, organic silane, etc. in a predetermined solvent, coating, drying to form a thin film, and then rubbing in a certain direction. can get. Or again,
Such an alignment film can also be formed by obliquely depositing SiO or 5ill, by irradiating with an electron beam or plasma, or by applying a solution of lecithin, stearic acid, organic silane, etc.

Formation of cells on the flexible substrate surface is achieved by fixing a matrix-like weir of uniform thickness made of a polymeric material to one substrate surface on which a transparent electrode or an alignment film is further formed in advance on the transparent electrode.

[Function] According to the present invention, by fixing a weir between flexible substrates, a thin liquid crystal layer can be maintained with high accuracy and uniformity in thickness, and a liquid crystal display with a large area or any desired shape or size can be formed. It is possible to construct a flexible liquid crystal display element that has a surface and is easy to handle, and is also easy to manufacture.

[Example] The present invention will be described in detail below with reference to the drawings.

1 and 2 show an example of the structure of a flexible liquid crystal display element of the present invention, where 1 and 8 are flexible substrates, and on this substrate 1, a transparent electrode film 2, an alignment film 3, a As shown in FIG. 2, cells 5 of liquid crystal material partitioned by weirs 4, alignment films 6, transparent electrode films 7, and flexible substrates 8 are arranged in this order. In FIG. 1, the weir 4 is
It must be completely adhered or fixed to at least one substrate side surface, in this example the entire surface of the alignment film 3 or 6, by means such as printing, and must not be sandwiched between the substrates in a car.

! The cross-sectional shape of a4 may be any suitable shape, such as a triangle as shown in Figure 3 or a hexagon as shown in Figure 4, in addition to a square or rectangle as shown in Figure 2. Yes, but it is necessary that such shapes form continuous cells in the form of a matrix.

In particular, the shape of the inner wall of the cell 5 is preferably circular in terms of more uniform operation of the liquid crystal material and suppression of light reflection by the weir 4.

Furthermore, from the viewpoint of improving the area ratio of the liquid crystal substance effective for display, as shown in FIG. is most preferred.

In FIG. 5, A, B, and C indicate the center of the circular cell 5, and AA', B-8', and C-C' indicate the center of the circular cell 5.
The radii of A-B, B-C, and C-A indicate the distance between cells 5.

Regarding the size of cell 5, 10-3 to 10' mm2
If it is less than to""am2, the effect of the cell wall surface on the operation of the liquid crystal substance will appear, and if it is more than 101 mm2, the existence of the weir 4 will be noticeable when viewing the liquid crystal display from a close distance. Easy to notice.

A more preferable size of the cell 5 is 10-2 to 100 mm
It is 2.

On the other hand, the width (minimum part) of weir 4 is lO~100
Preferably it is μI. If it is smaller than 10 μm,
Adhesive sealability with the surface of the flexible substrate tends to be incomplete, and on the other hand, if it is 100 μm or more, the effective display area of the liquid crystal material decreases, which is undesirable. The height of the weir 4, that is, the thickness of the layer of liquid crystal material, depends on the liquid crystal material used, but is usually in the range of 2 to 100 μm. It is necessary to completely separate and encapsulate the liquid crystal substance within the cell 5, and for this purpose, the height of the weir 4 is required to be highly uniform over the entire surface of the substrate. Generally, a thicker liquid crystal layer requires a higher voltage for its operation, which is undesirable.

As for the method of forming the weir, a printing method, a lithography method, an electrophotographic method, an embossing method, etc. can be used. Among these, the printing method and the lithography method are preferable in terms of ease and accuracy in adjusting the width and thickness of the weir.

In the printing method, a weir is formed by transferring an emulsion or solution of a polymer material onto the substrate surface using methods such as offset, gravure, letterpress, or screen. Among them, the offset method can accurately form a weir with a height of several micrometers. Therefore, it is a more preferable method when an extremely thin liquid crystal layer is required.

On the other hand, in the lithography method, a photosensitive polymer material coated to a certain thickness on a substrate is partially cured or decomposed by visible light, ultraviolet rays, electron beams, X-rays, etc. to form any desired pattern. Although this method is expensive, it is possible to form a weir with higher precision and is therefore preferable.

The polymer materials used as the weir in the present invention include polyamide, polyester, polyimide, polysiloxane, and polysulfone.

Polyether sulfone type, polyvinyl alcohol type, polyvinyl chloride type, polybutadiene type, polyisoprene type, polyacrylonitrile type, polyacrylamide type, polyacrylate type, epoxy type, siloxane type, fluorine type, phenol type, urethane type, cellulose, It is preferably an ester-based polymer, which has chemical resistance to liquid crystal substances, and has a refractive index and a contact rate close to those of the liquid crystal substance.

If necessary, an improving agent to improve adhesion to the substrate and a coloring agent such as a dye to improve contrast can be added to these polymeric substances.

As the photosensitive polymer material, there is used a material that has a basic skeleton of a polymer such as that used in the above-mentioned weir, and that hardens or decomposes when irradiated with ultraviolet rays, electron beams, X-rays, or the like. Such substances include photopolymerizable monomer types such as acryloyl groups, acrylamide groups, and glycidyl groups, and crosslinking-reactive photosensitive groups such as diazo groups, azide groups, cinnamoyl groups, and benzalacetophenone (chalcone) groups as side chains. Polymeric types with terminals, aromatic diazides, aromatic nitrenes.

Polymethyl vinyl ketone and polyvinylphenyl ketone are low-molecular photosensitive compounds consisting of a photosensitive compound such as anthraquinone and a polymer containing a reactive group.

There are photo-degradable materials such as polysulfone, and any of these can be used as the weir in the present invention.

The liquid crystalline substance used in the present invention may be any of the so-called smectic type, nematic type, cholesteric type, or a mixture of these types, which exhibit electro-optic effect or thermo-optic effect, and can be used in conventional liquid crystal displays. can also be adapted.

In order to fill the liquid crystal material into the cell, the liquid crystal material is filled into the cell by coating the liquid crystal material on the surface of the substrate with a weir formed thereon, by printing, or by dipping the substrate into the liquid crystal material, and then The other facing substrate is laminated using a press roll or the like, with the surface on which the alignment film and electrodes are formed facing inside. At this time, in order to prevent air bubbles from remaining in the cell,
It is more preferable to perform filling and lamination under vacuum.

For adhesion between the weir surface and the facing layer, there are cases where a certain amount of adhesion can be obtained by simply pressing lightly with a press roll, etc., and it can be used as is, but if stronger adhesion is required,
A method of using a heat-adhesive substance for the polymer material forming the weir or the alignment film material as the facing layer, adding an adhesion improver, a hot roll pressing method, or an adhesive on the surface of the weir or alignment film. It is possible to use a method such as partial application of .

The substrate obtained by encapsulating the liquid crystal material in this way may be used as is as a flexible liquid crystal display element, but usually the substrate surface is coated with polarizers, moisture-proof films, reflectors, color filters, etc. It is used by further providing a light diffusing plate, a reinforcing plate, etc. Furthermore, an element for transistor driving or nonlinear driving can be provided on one of the transparent electrodes.

Furthermore, full-color display can be achieved by alternately filling guest-host liquid crystal materials containing three color pigments in independent cells separated from each other by the weir of the present invention, similar to the arrangement in conventional color filters. It is also possible to use it as an element.

Next, specific examples of the present invention will be shown, but the present invention is not limited only to these examples.

Example 1 Polyvinyl alcohol was applied to the conductive surface of a polyester transparent conductive film (120 μm) on which indium oxide was vapor-deposited.
% aqueous solution was spray applied, heat treated at 150° C., and then rubbed in one direction with a polyester cloth to form an alignment film. On this alignment film, by offset printing method using UV curable ink mainly composed of epoxy acrylate,
Print a weir with a circular inner wall in a honeycomb arrangement as shown in Figure 5, and open the cell! 1(A-B) is 300 μm
, cell radius (A-A') is 135μm, height is 5μm
m weir (after drying) was formed. After filling the cell with biphenyl-based TN type liquid crystal (BDH E-7) by coating, a polyester film with a polyvinyl alcohol alignment film formed on a transparent conductive film was similarly applied in the rubbing direction of the alignment film. The layers were laminated with the alignment film on the inner surface so that they were perpendicular to each other, and were lightly pressed together using a press roll at 80°C.

Even if the substrate thus obtained is cut at will, the liquid crystal will not leak out. Furthermore, when polarizers were provided on both surfaces of the substrate along the direction of the alignment film and a voltage was applied between the electrodes or the voltage was interrupted, bright and dark contrasts were clearly shown.

Example 2゜A 1% methyl ethyl ketone solution of epoxy resin was coated on the conductive surface of the transparent conductive film used in Example 1 using a roll coater.
After coating and heat-treating at 150° C., rubbing was performed in one direction with a polyester cloth to form an alignment film. A cyclized polyisoprene photoresist (OMR-83, manufactured by Tokyo Ohka Co., Ltd.) was applied with a roll coater and then dried to obtain a film with a thickness of 8 μm. As in Example 1, the photoresist film was exposed to light through a mask having a pattern as shown in FIG. 5, and then exposed and rinsed to form a weir. The obtained cell is a cell open circuit! ! (A-B) is 180μ11 cell radius (A-A
') was 80μ peak, and the height of the weir was uniform with an accuracy of ±5%.

Inside this cell, a guest-host type nematic liquid crystal (BDH, biphenyl liquid crystal E-8) containing a dichroic dye is added.
, Dye D-62wt%) by a coating method, a transparent conductive polyester film with an alignment film of semi-hardened epoxy resin formed on the transparent conductive surface was aligned in a homogeneous alignment direction, and the alignment film surface was aligned. Inside, 80
It was lightly crimped with a press roll at ℃. The laminated substrate obtained by this method does not leak liquid crystal even when cut freely, and a polarizer is provided on one surface of the substrate in alignment with the direction of the alignment film, and between the electrodes taken out from the edge. By applying a voltage to , a colored-colorless response was shown.

[Effects of the Invention] As is clear from the above, according to the present invention, by providing a weir, a thin liquid crystal layer can be maintained with high accuracy and uniformity in thickness, and can be applied over a large area or in any desired shape or size. It is possible to construct a flexible liquid crystal display element having a liquid crystal display surface with good handling properties, and also easy to manufacture.

The flexible liquid crystal display element of the present invention uses electrodes formed with a pattern or an X-Y matrix,
For displaying characters, numbers, single images of symbols, etc., on the displays of personal computers, televisions, word processors, clocks, calculators, measuring instruments, bulletin boards, sign display boards, and even light shutters, writing boards, etc. It can be used by taking advantage of its advantages such as being flexible, allowing for any desired size, and being lightweight.

[Brief explanation of drawings]

FIG. 1 is a flexible liquid crystal display element of the present invention. FIGS. 3 and 4 are cross-sectional views showing two examples of matrix-like weir shapes. FIG. 5 is a weir with a honeycomb arrangement and a circular inner wall. It is a sectional view showing an example of a shape. 1.8... Flexible substrate, 2.7... Transparent electrode film, 3.6... Alignment film, 4... Weir, 5... Liquid crystal cell. Figure 1 〒2=`` 2,7; Hill E June wo Sai&R @ 5: Not yet! I5 eaves type Wajima

Claims (1)

[Claims] 1) In a liquid crystal display element in which a liquid crystal substance is sealed between a pair of transparent flexible substrates arranged opposite to each other through transparent electrodes, a polymer substance having a uniform thickness and continuous in a matrix shape is disposed between the flexible substrates. 1. A flexible liquid crystal display element, characterized in that a weir consisting of a weir is fixed thereto, and a liquid crystal substance is independently sealed in a plurality of cells separated from each other by the weir.