JPH05281526A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To realize high contrast and high quality display by including a projection composed of light absorbing material and plastic resin, thereby controlling dispersed light to control the deterioration and malfunction of an active element and the opening angle for the dispersed light. CONSTITUTION:In a light dispersion type liquid crystal display element comprising two sheets of substrates 1, 2, at least one of which has transparency is provided with signal lines 5, 6, an picture element electrode 4, a nonlinear element or an active element 3, which is an active element, formed on every picture element electrode and a light emulation layer including a liquid crystal material and a transparent solid material, the light dispersion type liquid crystal display element includes a projection 7 with a light absorbing material and a plastic resin on either an active element 3 or on signal lines 5, 6. Accordingly, since a leakage dispersed light from an adjoining picture electrode in the state of dispersing light may be shut off by the projection 7, a contrast ratio may be improved by making it feasible to control the acquired directly travelling transmission light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device that does not use a polarizing plate, and more specifically, it can electrically control the blocking and transmission of a visual field, and particularly displays characters and figures. By switching the display electrically with high-speed responsiveness, display devices for decorative display boards such as advertising boards, watches, calculators, and display devices that require a bright screen, for example, high contrast and high precision display performance are required. And a display device for a projection, etc.

[0002]

2. Description of the Related Art As a liquid crystal display element, an active matrix type liquid crystal display element having an active element, which is a non-linear element or an active element, for each pixel electrode has been put into practical use as the amount of processed information increases. These are TN type devices using nematic liquid crystal, in which liquid crystal molecules are arranged in a specific arrangement by an alignment film formed on a substrate, and the linearly transmitted light transmitted through a polarizing plate is manipulated for each pixel electrode. This is to obtain a highly precise display.

In such an active matrix type liquid crystal display element, deterioration of the active element due to incident light and malfunction of an electric signal applied to a scanning signal line can be prevented, and the aperture angle of transmitted light is increased. As a method of controlling the above, a structure in which a black matrix is provided between the substrate and the active element or the signal line is designed to realize a high contrast ratio and high quality display.

On the other hand, as a method for producing a large-sized and inexpensive liquid crystal display body which does not require a polarizing plate or an alignment film and has a bright contrast, a liquid crystal droplet is dispersed in a polymer by encapsulating the liquid crystal, and the polymer is prepared. A method of forming a film is known.

Further, as a technique for enabling low voltage drivability, which is an important characteristic required for practical use of a liquid crystal display device, higher contrast, and time-division drivability, JP-A-63-63
-240460 discloses a liquid crystal device having a structure in which a transparent solid substance is distributed in a three-dimensional network in a continuous layer of a liquid crystal material.

These use nematic liquid crystals or cholesteric liquid crystals, and the scattering of incident light due to the matching of the refractive indices of the liquid crystal material and the polymer material or the random orientation of the liquid crystal molecules is expressed by an electrical operation to display Was to do.

The light-scattering liquid crystal display device composed of such a liquid crystal material and a polymer has a stronger forward scattering property than the conventional light-scattering liquid crystal display device using DS mode, cholesteric-nematic phase transition or smectic liquid crystal. It is said that a high contrast ratio can be obtained, and as a technique for practical use thereof, for example, an active matrix method or an optical system system in which an active element that is a nonlinear element or an active element is provided for each pixel electrode A light-scattering type liquid crystal display device that uses a method of reducing the size has been reported.

[0008]

However, the above-mentioned light-scattering type liquid crystal display element has not yet been sufficiently obtained. The main reason for this is that in the light-modulating layer consisting of a liquid crystal material and a transparent solid substance, when light is scattered, the scattered light reaches up to the adjacent pixel electrode part, which enables precise display. It wasn't.

That is, unlike the conventional TN type liquid crystal display element, since the display is performed by the contrast of the white turbidity due to light scattering and the transparent state due to light transmission, deterioration or malfunction of the active element and the opening angle of scattered light are controlled. No suitable method was found.

The problem to be solved by the present invention is to control the scattered light so as to control the deterioration or malfunction of the active element and the aperture angle of the scattered light, and further to provide a high-contrast, high-quality light-scattering liquid crystal display. Provide elements, in particular
An object of the present invention is to provide a transmission type or projection type liquid crystal display device equipped with this light scattering type liquid crystal display element.

[0011]

In order to solve the above-mentioned problems, the present invention has two substrates, at least one of which is transparent, and at least one substrate is formed for each signal line, pixel electrode and pixel electrode. A non-linear element or an active element that is an active element, and the other substrate has an electrode layer,
A light-scattering type liquid crystal display device having a light control layer made of a liquid crystal material and a transparent solid substance between the two substrates, wherein a protrusion made of a light absorbing material and a synthetic resin is provided on the active device or on the signal line. A liquid crystal display element is provided.

The substrate used in the present invention may be a rigid material such as glass or metal, or a flexible material such as a plastic film. The two substrates are opposed to each other and are separated by an appropriate distance. Also, at least one of them
The light control layer having transparency and a liquid crystal layer sandwiched between the two and a layer having a transparent solid substance should be visible from the outside world. However, complete transparency is not essential.

If the liquid crystal device is used to act on light passing from one side of the device to the other, the two substrates are both given suitable transparency. . Appropriate transparent or opaque electrodes may be disposed on the entire surface or a part of the substrate, depending on the purpose. In addition, at least one of the substrates needs to have a signal line, a pixel electrode, and an active element which is a nonlinear element or an active element formed for each pixel electrode.
However, in the case of a flexible material such as plastic, it can be used for the liquid crystal display element of the present invention after being fixed to a rigid material such as glass or metal.

The peripheral portions of the two substrates are fixed by using a well-known sealant. Further, usually, a spacer for maintaining a gap may be interposed as in the known liquid crystal device.

As the spacer, for example, Mylar,
Alumina, rod-type glass fiber, glass beads, polymer beads, and other various liquid crystal cells can be used.

The liquid crystal material used in the present invention does not need to be a single liquid crystal compound, and may be a mixture containing two or more kinds of liquid crystal compounds or substances other than the liquid crystal compounds. What is normally recognized as a liquid crystal material in this technical field may be used, and one having a positive dielectric anisotropy is preferable. The liquid crystal used is preferably a nematic liquid crystal, a smectic liquid crystal or a cholesteric liquid crystal, and a nematic liquid crystal is particularly preferable. In order to improve the performance, a cholesteric liquid crystal, a chiral nematic liquid crystal, a chiral smectic liquid crystal or the like, or a chiral compound may be appropriately contained.

The liquid crystal material used in the present invention is preferably a blended composition comprising one or more compounds selected from the compound group shown below, and the characteristics of the liquid crystal material, that is, the phase transition between the isotropic liquid and the liquid crystal. Temperature, melting point, viscosity, refractive index anisotropy (Δ
n), dielectric anisotropy (Δε), solubility with a polymerizable composition and the like can be appropriately selected and blended for use.

Examples of the liquid crystal material include 4-substituted benzoic acid 4'-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4'-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4'-substituted biphenyl ester, 4- (4-substituted cyclohexanecarbonyloxy)
Benzoic acid 4'-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4'-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4'-substituted cyclohexyl ester, 4-substituted 4'-substituted Biphenyl, 4-substituted phenyl 4'-substituted cyclohexane, 4
-Substituted 4 "-substituted terphenyl, 4-substituted biphenyl 4'-substituted cyclohexane, 2- (4-substituted phenyl)
Examples thereof include 5-substituted pyrimidines, and among these compounds, compounds having a cyano group at least at one end of the molecule are particularly preferable.

In the case of a liquid crystal display device having a light control layer composed of a liquid crystal material and a transparent solid substance between two substrates, a light control layer forming material containing a liquid crystal material, a polymerizable composition and a polymerization initiator. The content of the liquid crystal material therein is preferably 60% by weight or more, and particularly preferably in the range of 70 to 90% by weight.

The transparent solid substance formed in the light control layer may be one in which a liquid crystal material is dispersed in the form of liquid droplets in a polymer, but one having a three-dimensional network structure is more preferable.

It is preferable that the three-dimensional network portion of the transparent solid substance is filled with a liquid crystal material, and the liquid crystal material forms a continuous layer. By forming a disordered state of the liquid crystal material, It is indispensable for forming the optical boundary surface and expressing the scattering of light.

Synthetic resins are suitable as these transparent solid substances. A photo-curable resin obtained by polymerizing a polymer-forming monomer or oligomer is preferable as a material that gives a three-dimensional network structure.

As a method of forming a three-dimensional network structure by the transparent solid substance formed between the substrates, a substrate sandwiched between two substrates having protrusions made of a synthetic resin and a light absorbing material is formed. A method of polymerizing the photopolymerizable composition by irradiating it with ultraviolet rays while keeping the material for forming the photolayer in an isotropic liquid state can be mentioned.

Examples of the polymer-forming monomer forming the transparent solid substance include styrene, chlorostyrene,
α-methylstyrene, divinylbenzene: As a substituent, methyl, ethyl, propyl, butyl, amyl, 2-
Ethylhexyl, octyl, nonyl, dodecyl, hexadecyl, octadecyl, cyclohexyl, benzyl, methoxyethyl, butoxyethyl, phenoxyethyl, allyl, methallyl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-chloro-2-hydroxypropyl, Acrylate, methacrylate or fumarate having a group such as dimethylaminoethyl, diethylaminoethyl, etc .; ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-butylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, tri Mono (meth) acrylates such as methylolpropane, glycerin and pentaerythritol, or poly (meth) a Relate; vinyl acetate, vinyl butyrate or vinyl benzoate, acrylonitrile, cetyl vinyl ether, limonene, cyclohexene, diallyl phthalate, diallyl isophthalate, 2-, 3- or 4
-Vinyl pyridine, acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-hydroxymethyl acrylamide or N-hydroxyethyl methacrylamide and their alkyl ether compounds; 2 mol or more of ethylene oxide or propylene oxide per 1 mol of neopentyl glycol. Di (meth) acrylate of diol obtained by addition; Di or tri (meth) acrylate of triol obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane; 2 moles per 1 mole of bisphenol A. Di (meth) acrylate of diol obtained by adding the above ethylene oxide or propylene oxide; 1 mol of 2-hydroxyethyl (meth) acrylate and phenylisocyanate Reaction products of bets or n- butyl isocyanate 1 mol, dipentaerythritol poly (meth) acrylate, and the like.

As the polymer-forming oligomer forming the transparent solid substance, for example, epoxy (meth) acrylate, polyester (meth) acrylate, polyurethane (meth) acrylate, polyether (meth) acrylate, etc. may be used. it can.

As the polymerization initiator, for example, 2-hydroxy-2-methyl-1-phenylpropan-1-one ("Darocur 1173" manufactured by Merck), 1-hydroxycyclohexyl phenyl ketone ("Ciba Geigy" manufactured by Ciba Geigy) is used. Irgacure 184 "), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one (Merck" Darocur 1116 "), benzyl dimethyl ketal (Ciba Geigy" Irgacure 65 "
1 "), 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1 (" Irgacure 907 "manufactured by Ciba Geigy), 2,4-diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd.) "Kayacure DETX") and ethyl p-dimethylaminobenzoate ("Kayacure-EPA" manufactured by Nippon Kayaku Co., Ltd.), isopropyl thioxanthone ("Kantacure IT" manufactured by Ward Prekinsop)
X ") and a mixture of ethyl p-dimethylaminobenzoate and the like.

The synthetic resin forming the protrusions, which is one of the features of the present invention, may be a resin such as gelatin, casein, fish glue, etc., but polyester, polyvinyl alcohol, polyvinylpyrrolidone, polyimide resin, urethane resin, Synthetic resins such as epoxy resins and melamine resins are preferable, and acrylic resins are particularly preferable.

A photopolymerizable resin is preferable when it is formed by a known photolithography method. As a method of forming the protrusions, for example, a protrusion forming material composed of the synthetic resin material and the light absorbing material may be formed by a photolithography method, or the protrusions composed of the synthetic resin may be formed. After the formation, the surface of the protrusion may be covered with a light absorbing material.

As such a method, for example, a dyeing method, a vapor deposition method, an electrodeposition method, a photosensitive coloring polymer method, or various printing methods such as silk screen, offset, intaglio, letterpress and gravure can be used. .

In the dyeing method, by optimizing the dye concentration, temperature, pH, etc. of the dyeing bath according to the dye used,
After forming a projection of acrylic resin, urethane resin, epoxy resin or the like that can obtain uniform spectral characteristics, the surface of the projection is chemically treated with tannic acid or the like to obtain a projection according to the present invention. Can be formed.

In the electrodeposition method, as a resin having excellent stability,
The protrusions such as polyester and melamine resin can be colored by electrophoresis with an organic pigment such as phthalocyanine and perylene, and the protrusions according to the present invention can be formed.

In various printing methods, an organic pigment, an inorganic pigment, carbon black or the like can be mixed with the above-mentioned resin and used, and the number of processing steps is small, a precise pattern can be formed, and a large area can be obtained. It is a suitable method that can be produced also in the case of.

The material forming the protrusions has a high electrical insulating property, does not dissolve in the polymerizable composition in the light control layer forming material, is chemically stable, and is liquid crystal. In order not to reduce the resistance value of the material, it is preferable that the material does not contain an ionic substance.

In addition to this, for example, a buffer layer is provided on the active element and the signal line, and the protrusion according to the present invention is formed on the buffer layer.
Similar goals can be achieved.

The buffer layer formed here may be an inorganic material or an organic material. For example, SiN may be used as the inorganic material and polyimide or the like may be used as the organic material.

As a method of manufacturing the liquid crystal display element of the present invention, for example, a synthetic resin and light absorption are provided on a substrate having a signal line, a pixel electrode and an active element which is a non-linear element or active element formed for each pixel electrode. A protrusion made of a material is formed by the above-described forming method, and a liquid crystal material, a polymerizable composition, a polymerization initiator, an optional component, a chain transfer agent, and a light A light control layer composed of a liquid crystal material and a transparent solid substance is produced by polymerizing the polymerizable composition by irradiating with actinic rays through a light control layer forming material composed of a sensitizer, a dye, a cross-linking agent and the like. It can be manufactured by forming layers.

[0037]

In the liquid crystal display element of the present invention, the protrusions made of the synthetic resin and the light absorbing material formed on the active element or the signal line cause the leakage from the adjacent pixel electrodes in the state where the light is scattered. Since the scattered light can be blocked, it is possible to control the obtained straight transmitted light and improve the contrast ratio.

Furthermore, by preventing the deterioration of the active element due to scattered light and eliminating the influence on the signal line, especially on the OFF current signal, malfunction can be reduced.

Further, the liquid crystal display element of the present invention can be mounted as a transmissive or transmissive liquid crystal display device. In this case, a backlight may be installed on the side of the substrate having the active element for the purpose of eliminating the displacement due to the parallax between each pixel electrode and the color filter. In this case, a black matrix, which is a conventionally known technique, is used as the active element or Forming between the signal line and the substrate is not particularly limited in the liquid crystal display element of the present invention.

The protrusion according to the present invention is also useful for other light scattering type liquid crystal display devices such as DS type display, cholesteric-nematic phase transition display, and thermal writing display liquid crystal display device using smectic liquid crystal. It is a thing.

[0041]

EXAMPLES Examples of the present invention will be shown below with reference to FIGS. 1 to 9 to explain the present invention more specifically. However, the invention is not limited to these examples.

FIG. 1 shows a conventional active matrix liquid crystal display device. In FIG. 1, 1 is a substrate, 2 is a counter substrate having a transparent electrode layer, 3 is an active element which is a nonlinear element or an active element, 4 is a pixel electrode, and 5 and 6 are signal lines. Is.

Between the substrates 1 and 2, there is a light control layer composed of a liquid crystal material and a transparent solid substance, which can scatter or transmit incident light by an electric operation.

2 to 9 show an example of the liquid crystal display device of the present invention. As in the case of FIG. 1, a light control layer made of a liquid crystal material and a transparent solid substance is present between the two substrates of the liquid crystal display elements of FIGS. 2 to 9.

In FIG. 2, reference numeral 7 denotes a protrusion formed on the active element and the signal line, which is made of a light absorbing material and a synthetic resin.

In the liquid crystal display element of the present invention, the shape of the protrusion can be changed for the purpose of obtaining the viewing angle characteristics suitable for the application of the mounted liquid crystal display element.

FIG. 2 shows a liquid crystal display element in which a synthetic resin projection containing the light absorbing material according to the present invention is formed on the active element 3, the pixel electrode 4, the signal lines 5 and 6 of FIG. The cross section of the protrusion in AA ′ of FIG. 2 has a rectangular shape, and the display in front of the liquid crystal display element can be made the best.

FIG. 3 shows a projection formed such that the cross section taken along the line AA 'in FIG. 2 forms a parallelogram, which is useful as a liquid crystal display element used in the driver's seat, the cockpit, etc. It is a thing.

FIG. 4 shows a projection formed such that the cross section taken along the line AA 'in FIG. 2 has a trapezoidal shape, and a characteristic in which the display quality is emphasized for the purpose of obtaining a higher contrast ratio. Is obtained.

FIG. 5 shows a trapezoidal cross section taken along the line AA 'in FIG. 2 which is the reverse of that shown in FIG. 4, and provides characteristics that emphasize bright display and wider viewing angle characteristics.

FIG. 6 shows a substrate 1 having active elements.
A synthetic resin is formed in a layered or columnar shape on the signal lines 5 and 6 and the active element 3, and is placed on one of the counter substrates 2.
A protrusion is further formed in a portion facing the layer or the protrusion formed on the substrate 1 made of the light absorbing material and the synthetic resin.

In this structure, the role of preventing the deterioration of the active element and the malfunction of the signal line and the role of controlling the scattered light and the straight transmitted light are divided into two substrates. The improvement of the yield or the efficiency of the manufacturing process of the liquid crystal display device is achieved.

FIG. 7 shows a structure in which the heights of the protrusions on the active element 3 and the signal lines 5 and 6 are changed.
This structure makes it possible to smoothly perform the step of injecting the light control layer forming material during the step of manufacturing the liquid crystal display element.

FIG. 8 has a rectangular cross section taken along the line AA 'in FIG. 2, but an electrical connection is made between the active element 3 and the signal lines 5 and 6 and the synthetic resin projection. Buffer layer 8 that is highly reliable and chemically stable
And the projections of the present invention are formed on the buffer layer.

FIG. 9 shows a black matrix 9 formed between the active element 3 or the signal lines 5 and 6 and the substrate. Each pixel when mounted as a transmissive or transmissive liquid crystal display device. It is useful in a liquid crystal display element in which a backlight is installed on the side of a substrate having an active element for the purpose of eliminating a disparity between electrodes and a color filter.

The liquid crystal display elements of FIGS. 2 to 9 of the present invention have excellent visual characteristics, and a clear display which cannot be obtained by the conventional light-scattering type liquid crystal display element was obtained.

[0057]

INDUSTRIAL APPLICABILITY The present invention can control scattered light and straight transmitted light in the liquid crystal display element of the MIM or TFT type light-scattering liquid crystal display element, and the active element by the scattered light can be controlled. Degradation and O of signal line
By preventing changes in FF current, there is no malfunction and
It enables high contrast and high quality display.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a structure of a conventional liquid crystal display element.

FIG. 2 is a schematic view showing an example of a structure of a liquid crystal display element of the present invention.

FIG. 3 is a cross-sectional view showing an example of the structure of the liquid crystal display element of the present invention.

FIG. 4 is a cross-sectional view showing an example of the structure of the liquid crystal display element of the present invention.

FIG. 5 is a cross-sectional view showing an example of the structure of the liquid crystal display element of the present invention.

FIG. 6 is a schematic view showing an example of the structure of the liquid crystal display element of the present invention.

FIG. 7 is a schematic view showing an example of the structure of the liquid crystal display element of the present invention.

FIG. 8 is a cross-sectional view showing an example of the structure of the liquid crystal display element of the present invention.

FIG. 9 is a cross-sectional view showing an example of the structure of the liquid crystal display element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Counter substrate having an electrode layer 3 Active element which is a non-linear element or an active element 4 Pixel electrode 5 Signal line 6 Signal line 7 Synthetic resin projection containing a light absorbing material 8 Buffer layer having insulation 9 Black matrix

Claims (3)

[Claims] 1. At least one of two substrates, at least one of which is transparent, has a signal line, a pixel electrode, and an active element which is a nonlinear element or an active element formed for each pixel electrode, and the other. The substrate of has an electrode layer,
A light-scattering type liquid crystal display device having a light control layer made of a liquid crystal material and a transparent solid substance between the two substrates, wherein a protrusion made of a light absorbing material and a synthetic resin is provided on the active device or on the signal line. A liquid crystal display device comprising: 2. The liquid crystal display element according to claim 1, wherein the protrusion is a synthetic resin whose surface is covered with a light absorbing material. 3. A transmissive or projection type liquid crystal display device equipped with the liquid crystal display device according to claim 1.