JPH08286173A - Multicolored liquid crystal display device - Google Patents

Abstract

PURPOSE: To provide a multicolored liquid crystal display device which is low in power consumption, bright, free from parallax, superior in visibility, rich in display color, and easily manufactured by laminating a high molecule dispersion type liquid crystal layer and a low molecule liquid crystal layer at least at pixel parts. CONSTITUTION: A display layer 6 is sandwiched between a transparent substrate (front plate) 3 having a transparent pixel electrode 2 provided with a switching element 1 and a substrate (back plate) 5 having a reflecting electrode 4. The display layer 6 consists of the high molecule dispersion type liquid crystal layer 9 formed by dispersing liquid crystal 7 containing dichroic pigments in high molecules 8 in grains and the low molecule liquid crystal layer 10 containing dichroic pigments. A reflection type liquid crystal display device is made low in power consumption since no back light is used. Further, a reflection type and a transmission type both use a subtractive color mixture system by dichroic pigments for display, so the utilization efficiency of light is high and the display is bright; and two kinds of dichroic pigment layers are close to each other, so parallax is small and visibility is superior even in a slanting direction, so that the display device having rich display colors can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor liquid crystal display device, and more particularly to a multicolor liquid crystal display device which has low power consumption and is bright and has excellent visibility.

[0002]

2. Description of the Related Art As a multicolor display device using liquid crystal, S
A simple matrix drive display in which a TN type liquid crystal cell is combined with a micro color filter or an active matrix drive display in which a TN type liquid crystal cell is combined with a micro color filter is generally used. Since these displays use a polarizing plate, the light utilization efficiency is usually extremely low at around 3-5%,
For this reason, a fairly bright backlight must be used, and there is a problem of high power consumption. Therefore, when it is used as a display for a battery-powered portable device, there are disadvantages such as an increase in weight due to the battery and a short usable time per charge.

[0003]

In order to solve the above problems, some reflective multicolor liquid crystal display devices that can be used without a backlight have been proposed. SID '
92 digest, p437 has a phase transition type guest.
A display in which a host liquid crystal is combined with a two-color micro color filter has been reported. Since a phase change type guest host cell does not require a polarizing plate, TN
It is known that it can be more than twice as bright as a standard type or STN type display. However, in this display, the use of a micro color filter consisting of two complementary colors, magenta and green, causes half of the incident light to be absorbed by the color filter. Therefore, the brightness is not sufficient in practical use.

In Nikkei Microdevice, January 1994, p99, a display is reported in which the color is controlled by the magnitude of the voltage by utilizing the coloring due to the birefringence of TN or STN liquid crystal. Since this display does not use an additive color mixture method using a micro color filter, there is no light loss due to the color filter. However, since a polarizing plate is used, there still remains a problem in brightness. Further, the display on this display is always colored, and there is also a problem that the most natural display for humans such as black characters on a white background cannot be displayed.

Optical. Eng. , 23, 3, p247, a method of stacking a plurality of guest-host cells and performing color display by subtractive color mixing has been proposed. Although this method is excellent in light utilization efficiency, in a high-definition matrix display, there is a problem that displacement of each layer occurs when the cell is observed obliquely. Further, since the guest-host cell cannot perform high time division driving, when a large-capacity display is made, an active matrix type display in which a switching element is arranged for each pixel must be used. This method has a problem that a plurality of active matrix substrates are required and the cost is significantly increased. Therefore, in view of the above circumstances, an object of the present invention is low power consumption, yet bright,
An object of the present invention is to provide a multicolor liquid crystal display device which has no parallax, is excellent in visibility, has abundant display colors, and is easy to manufacture.

[0006]

The above objects can be solved by the present invention described below. That is, the present invention is a multicolor display device in which a display layer is sandwiched between a pair of electrode substrates, at least one of which has a light-transmitting property, wherein the display layer is a liquid crystal containing a dichroic dye in the form of droplets. A multicolor liquid crystal characterized in that a polymer-dispersed liquid crystal layer dispersed in a liquid crystal layer and a low-molecular liquid crystal layer containing a dichroic dye having a hue different from that of the dichroic dye are laminated at least in a pixel portion. It is a display device.

[0007]

In the case of the reflection type liquid crystal display device, the backlight is not used, so that the power consumption is low. Also, for both reflective and transmissive types, the dichroic dye contained in the polymer-dispersed liquid crystal layer and the dichroic dye contained in the low-molecular liquid crystal layer are used to display by the subtractive color mixture method so that the light utilization efficiency is improved. High and bright,
Since the two types of dichroic dye layers are in close contact with each other, the parallax is small and the visibility is excellent even when the display is obliquely observed, and the display colors are abundant. Furthermore, since the polymer dispersed liquid crystal layer is patterned on the pixel electrode of each pixel part and the low molecular weight liquid crystal layer is filled after the cell is assembled, it is more difficult to manufacture than the case where a conventional two-layer display device is used in combination. Is easy. In particular, if the polymer dispersion type liquid crystal layer is patterned by the electrodeposition method, the patterning can be performed without making difficult alignment on the pixel electrode formed in advance.

[0008]

FIG. 1 shows a reflection type multicolor liquid crystal display device as an example of the multicolor liquid crystal display device according to the present invention. A display layer 6 is sandwiched between a transparent substrate (front plate) 3 having a transparent pixel electrode 2 provided with a switching element 1 and a substrate (rear plate) 5 having a reflective electrode 4. The display layer 6 is
The liquid crystal 7 containing a dichroic dye is composed of a polymer-dispersed liquid crystal layer 9 dispersed in a polymer 8 in the form of particles, and a low-molecular liquid crystal layer 10 containing a dichroic dye. In the example of the multicolor liquid crystal display device shown in FIG. 1, the pixel portion A (9a) in the polymer dispersed liquid crystal layer 9 has a blue dichroic dye, and the pixel portion B (9b) has a red dichroic pigment. A black dichroic dye is added to the organic dye and the low-molecular liquid crystal layer 10. The liquid crystal forming the low-molecular liquid crystal layer and the liquid crystal in the polymer-dispersed liquid crystal layer are both nematic liquid crystals or chiral nematic liquid crystals having positive dielectric anisotropy. A positive type is used as the dichroic dye which is dissolved in the liquid crystal and whose molecular alignment changes in association with the liquid crystal. The amount of the dichroic dye added is 1.0 to the liquid crystal.
5.0% by weight is preferred.

The operation principle of the multicolor liquid crystal display device of the present invention will be described. In the state where no voltage is applied, it is desirable that the liquid crystal in the low-molecular liquid crystal layer has any one of homogeneous, twist, focal conic, and planar orientations, but the orientation is somewhat disturbed or distorted. May be. Further, the liquid crystal in the polymer-dispersed liquid crystal layer has a distorted orientation regulated by the capsule wall surface when no voltage is applied, and the direction of the liquid crystal average director in each capsule is random.

Further, when no voltage is applied, the light absorption of the dichroic dye in the low molecular weight liquid crystal layer and the light absorption of the dichroic dye in the polymer-dispersed liquid crystal layer are strong and are in each cell. Light absorption by the dyes is added up, and in the example of FIG. 1, the color is black. At this time, the light absorptivity of this cell is enhanced by imparting light scattering properties to the polymer dispersed liquid crystal layer. This phenomenon is explained as follows. The light incident on the cell is not necessarily absorbed by the time it reaches the reflective electrode, but the light reaching the reflective electrode is reflected by the reflective electrode with a certain angular distribution, and the reflected light is again the dye in the cell. Be absorbed by. The light that is not further absorbed reaches the front plate / air interface. However, the traveling angle of this light is large due to scattering by the polymer-dispersed liquid crystal. For this reason, the proportion of light that is totally reflected at the front plate / air interface is high. Therefore, the reflected light on the substrate surface is again absorbed by the dye in the cell.
The light absorption rate can be increased by utilizing such multiple absorption of light.

On the other hand, when a voltage is applied to this cell, both the liquid crystal in the polymer dispersed liquid crystal layer and the liquid crystal in the low molecular weight liquid crystal layer are oriented in the electric field direction due to their dielectric anisotropy. Try to change the direction of the director. However,
Since the liquid crystal in the polymer dispersed liquid crystal layer receives the anchoring force from the wall surface of the capsule, it requires a higher electric field than the liquid crystal in the low molecular liquid crystal to rearrange in the electric field direction. Therefore, when a low voltage is applied to the pixel unit A,
Only the liquid crystal in the low-molecular liquid crystal layer changes the orientation, and the light absorption by the dichroic dye added therein is weakened. Therefore, the pixel portion exhibits the hue of the dichroic dye added to the liquid crystal in the polymer-dispersed liquid crystal layer, for example, blue.

Further, when a higher voltage is applied to the pixel portion A, not only the liquid crystal in the low molecular weight liquid crystal layer but also the liquid crystal in the polymer dispersed liquid crystal layer are aligned in the electric field direction. For this reason, light absorption by both dyes added to the liquid crystal is weakened, and the pixel portion exhibits a white color. On the other hand, the pixel portion B can be changed to black-colored (red) -white by the applied voltage value according to the same principle. When such fine pixels of different hues are alternately arranged, human vision
The color exhibited by each pixel is recognized as an additive color mixture. Therefore, in the cell of FIG. 1, if each of the pixel portions A and B is switched in three stages, eight types of display as shown in Table 1 are possible due to the additive color mixture.

[0013]

[Table 1]

In the example of Table 1, the liquid crystal in the low molecular weight liquid crystal layer is 4
It is shown that V is aligned in the electric field direction, and the liquid crystal in the polymer dispersed liquid crystal layer is aligned in the electric field direction at 8V. The applied voltage value in each pixel is not limited to three levels, and in practice, the above-mentioned colors can be changed in multiple levels.

Next, as another example of the multi-color liquid crystal display device of the present invention, in FIG. 2, the liquid crystal in the low-molecular liquid crystal layer is a nematic liquid crystal having a negative dielectric anisotropy or a polymer dispersed liquid crystal. An example of a cell structure in which a nematic liquid crystal having a positive dielectric anisotropy is used as the liquid crystal in the layer is shown. In the low-molecular liquid crystal layer, a positive dichroic dye that is dissolved in the liquid crystal and changes its molecular arrangement in cooperation with the liquid crystal is used. The amount of the dichroic dye added is preferably 1.0 to 5.0% by weight based on the liquid crystal. Figure 2
In the example of the multicolor liquid crystal display device, the pixel portion A (9a) in the polymer dispersed liquid crystal layer 9 contains a blue dichroic dye and the pixel portion B.
(9b) contains a red dichroic dye, and the low-molecular liquid crystal layer 1
In 0, a yellow dichroic dye is added. In the initial alignment when no voltage is applied, it is desirable that the liquid crystals in the low molecular weight liquid crystal layer have homeotropic alignment.

In the case of a liquid crystal having a negative dielectric anisotropy, when a voltage is not applied, the dye in the low-molecular liquid crystal layer is weakly absorbed, so that a color tone is exhibited by the dye in the polymer-dispersed liquid crystal layer.
On the other hand, when a low voltage is applied to the pixel portion A, the liquid crystal forming the low molecular weight liquid crystal layer is aligned in a direction (homogeneous) orthogonal to the electric field, and thus absorption by the dye is enhanced. Therefore, the light absorption of the dichroic dye in the low-molecular liquid crystal layer and the light absorption of the dichroic dye in the polymer-dispersed liquid crystal layer are strong, and the color tones of both layers are a subtractive color mixture. Then it turns green. Further, when a high voltage is applied to the pixel portion A, the liquid crystal in the polymer dispersed liquid crystal layer is aligned in the direction of the electric field, so that the light absorption by the dichroic dye in the polymer dispersed liquid crystal layer is weakened, The hue of the dye in the low-molecular liquid crystal layer, for example, yellow is exhibited.

In the cell structure of FIG. 2 as well, by controlling the voltage applied to both the A and B pixels, the color tone by the additive color mixture of both the A and B pixels can be displayed, and each of the pixel portions A and B has three stages. By switching to, eight kinds of displays as shown in Table 2 are possible.

[0018]

[Table 2]

In the example of Table 2, the liquid crystal in the low molecular weight liquid crystal layer is 4
It is shown that the liquid crystal in the polymer-dispersed liquid crystal layer is oriented in the direction perpendicular to the electric field at V, and is oriented in the electric field direction at 8V. As another aspect, in the cells of FIGS. 1 and 2, the pixel electrode on the active matrix substrate side can be a reflective type and the other electrode can be a transparent electrode. As yet another aspect, a transparent multi-color liquid crystal display device can be obtained by using transparent electrodes for both the front plate and the back plate and providing a backlight on the outside of the back plate. The color of the dye added to the polymer-dispersed liquid crystal layer and the color of the dye added to the low-molecular liquid crystal layer are not limited to those shown in FIGS. Further, three or more pixels having different color tones may be provided.

The transparent substrate used in the liquid crystal display device of the present invention is a transparent substrate such as glass or polymer film used in conventionally known liquid crystal display devices. In the case of a reflection type, an opaque substrate can be used as the back plate in addition to the transparent substrate, and ceramics, polymer films, polymer sheets, and glass cloth, paper, composite materials based on synthetic fiber cloth, etc. Used. Pixel electrodes corresponding to each pixel are patterned on the front plate with a transparent conductive material such as ITO, SnO ₂ and ZnO, and each pixel has a three-terminal element MOSFFT, a TFT, and a two-terminal element. MIM, MSI, diode ring, back to
A back diode and a switching element such as a varistor are provided.

Further, in the case of a reflection type, the electrode of the back plate is required to have a function as a reflection plate, so that the scattering angle in which the reflection angle is gathered in the normal direction (0 degree) with respect to the vertically incident light. It is desirable to have good properties for good contrast and brightness. Light with a large reflection angle is not preferable because it is totally internally reflected at the front plate / air interface even when the light absorption of the liquid crystal display layer and the scattering property of the polymer dispersed liquid crystal layer are sufficiently weak. Further, if the scattering angle is excessively concentrated in the vicinity of 0 degree, the brightness of the cell will change significantly depending on the angle of the observation direction and the ambient light, which is not practically desirable. As the electrode having such light reflectivity, a highly reflective metal having conductivity, for example, aluminum,
An electrode having a surface uneven shape made of silver, chromium, nickel or the like is preferable.

In order to collect the reflected light near the center, it is desirable that the unevenness be formed with a gentle slope. As a method of forming such unevenness, a sandblast method, a chemical etching method, a honing method, an anodizing method, a sol-gel method, a molding method, a photolithography method, a method of roughening by heating or curing shrinkage, a dispersion of particles A film forming method using the above resin, a method utilizing phase separation of a blend polymer, a method combining these, and the like are preferably used. Further, the electrodes on the back plate may be patterned if necessary. When the reflective electrode is formed in a pattern such as a stripe corresponding to each pixel pitch, a polychromatic polymer dispersed liquid crystal layer can be formed in a pixel pattern by selectively energizing each electrode. It is possible.

As the electrode forming method, vacuum deposition, ion plating, sputtering, CVD, plasma CV
Any of D, electroless plating, and electroplating is possible, but as a simple method, vacuum deposition and sputtering are particularly preferably used. As a method of patterning a metal thin film,
The etching method using a photoresist is common.

Further, it is also possible to use a transparent electrode substrate made of the above-mentioned transparent conductive material and having a reflection plate attached thereto.
For the purpose of controlling the initial alignment of the liquid crystal in the low molecular weight liquid crystal layer, it is preferable to provide an alignment film on the electrode on the side in contact with the low molecular weight liquid crystal layer. Further, it is also used in some cases to form an alignment film on the polymer dispersed liquid crystal layer. Further, in order to prevent color mixture with adjacent pixels and to prevent malfunction due to leakage current of the switching element due to external light,
It is preferable to form a light shielding layer between the pixels and on the switching element.

Next, a method of manufacturing the multicolor liquid crystal display device of the present invention will be described. In the present invention, it is necessary that the liquid crystal in the polymer dispersed liquid crystal layer does not seep out of the layer and that the liquid crystal in the low molecular liquid crystal layer does not enter the polymer dispersed liquid crystal layer. If bleeding or penetration occurs, the liquid crystal in the low-molecular liquid crystal layer and the liquid crystal in the polymer-dispersed liquid crystal layer are mixed with each other, and the color display characteristics are deteriorated. Therefore, it is desirable that the liquid crystal in the polymer-dispersed liquid crystal layer is completely enclosed in an independent capsule wall.

Various methods are known for encapsulating liquid crystals, but the liquid crystal encapsulation method of the present invention is required to satisfy various conditions as described below. 1. As described above, in order to prevent the liquid crystal in the polymer dispersed liquid crystal layer and the liquid crystal in the low molecular weight liquid crystal layer from being mixed with each other,
The liquid crystal capsule wall requires high strength and hiding power. 2. It is known that the electro-optical characteristics of the liquid crystal / polymer composite film are strongly influenced by the particle size of the dispersed liquid crystal, and in order to obtain a film having excellent characteristics, the particle size of the liquid crystal capsule should be 1 It is necessary to control the particle size to about 2 microns and to make the particle size as uniform as possible.

3. It is known that when the liquid crystal inside the capsule is oriented by an electric field, the liquid crystal receives a binding force (anchoring force) from the polymer interface, and the magnitude of the anchoring force varies depending on the polymer material used. There is. Therefore, from the viewpoint of reducing the driving voltage and the hysteresis, it is necessary to select a material having a small anchoring force for the liquid crystal used as the capsule wall material. 4. The voltage applied to the liquid crystal / polymer composite film is distributed between the polymer and the liquid crystal, but in order to increase the voltage distributed to the liquid crystal, it is preferable to make the capsule wall as thin as possible.

5. If the dye added to the liquid crystal also colors the capsule wall, it will cause residual color when a voltage is applied. Therefore, it is necessary to select a capsule wall material that does not incorporate the dye as much as possible. 6. In the encapsulation process, it is necessary to select a dye or a material that does not deteriorate the liquid crystal. 7. It is necessary to select a material and an encapsulation method that do not mix an organic ionic compound that deteriorates the voltage holding characteristic into the liquid crystal. 8. It must be stable over time.

The microcapsules satisfying the above conditions can be produced by interfacial polymerization, in-situ polymerization,
Although a coacervation method or the like can be used, the method disclosed in Japanese Patent Application No. 5-263103 is particularly preferably used as a liquid crystal encapsulation method that satisfies all the above requirements. In this method, a liquid crystal in which a monomer having a small anchoring force is added to a liquid crystal is dispersed in an aqueous solution, and the monomer is polymerized to be encapsulated, so that the wall surface in contact with the liquid crystal is a material having a small anchoring force. And supplying a material for the capsule wall from the aqueous phase side to provide a capsule wall having strength and heat resistance on the outside of the capsule wall.

As the dispersion method of the above liquid crystal, a mixing method using various stirring devices such as an ultrasonic disperser or a dispersion method such as a film emulsification method is effective. It is preferable because the particle size of the liquid crystal capsule can be arbitrarily set by the pore size and a sharp particle size distribution can be realized. A normal printing method such as screen printing can be used as a method for forming a multicolor polymer dispersed liquid crystal containing different dyes for each pixel, but it is possible to form a uniform pattern in a predetermined area on a predetermined position of the electrode substrate. The electrodeposition coating method is most preferably used for coating.

The electrodeposition coating as used herein means that a main electrode serving as a coating substrate and a counter electrode are arranged in a coating liquid and electricity is applied to electrically adsorb or deposit them on the substrate, and then the coating substrate is taken out. The coating film is obtained by removing the solvent. The following four methods are possible as a method for forming a polychromatic polymer-dispersed liquid crystal layer by the electrodeposition coating method. (1) An electrode made of a conductive film divided into a plurality of regions is provided on an electrically insulating substrate, a voltage is selectively applied to each electrode, and an electrodeposition coating method is applied on the electrode to which the voltage is applied. To form a polymer-dispersed liquid crystal layer, and repeating the above procedure to form a polychromatic polymer-dispersed liquid crystal layer on each electrode.

(2) A positive resist layer is applied on a conductive substrate, a predetermined pattern is formed by photolithography, and a polymer dispersed liquid crystal layer is formed in the resist opening where the electrodes are exposed by electrodeposition coating. By further removing a part of the resist into a predetermined pattern by a photolithography method to expose the electrode and forming a polymer dispersed liquid crystal layer of a different hue on the exposed electrode by repeating Method of forming multicolor polymer dispersed liquid crystal layer (3) Applying a resist layer on a conductive substrate, forming a predetermined pattern by photolithography, and electrodeposition coating the resist opening where the electrode is exposed By forming a polymer dispersed liquid crystal layer by the method, removing the resist, applying another resist layer, and repeating the same steps. Method for forming multicolor polymer dispersed liquid crystal layer

(4) A method of transferring the polymer dispersed liquid crystal layer patterned by the above method 1, 2 or 3 onto a display substrate by using a substrate different from the display electrode. To prepare the coating liquid for electrodeposition coating, add a dichroic dye to the liquid crystal,
Microcapsules containing these are manufactured, and the microcapsules are dispersed in a matrix resin aqueous solution to prepare. The matrix resin used preferably contains a resin having an ionic dissociative functional group, which becomes insoluble in water and precipitates by the exchange of electrons.

Depending on the matrix resin used, there are an anion electrodeposition method for depositing on the anode and a cation electrodeposition method for depositing on the cathode. In the present invention, either of these can be applied. When the polymer dispersed liquid crystal layer is formed on the transparent electrode, a metal oxide such as ITO is usually used as the main electrode as the transparent electrode. When an ITO substrate or the like is used as a cathode as a main electrode and cation electrodeposition is performed, the crystal of the conductive film on the substrate surface is altered by a neutralizing agent that is an acidic compound during electrodeposition, and a blackish brown high resistance opaque substance is obtained. It is more preferable to use the anion electrodeposition method.

As the matrix resin for electrodeposition, a resin having an ion dissociative group is used. For example, as the polymer for anion electrodeposition, an adduct of natural drying oil and maleic acid, an alkyd resin having a carboxyl group introduced, Epoxy resin-maleic acid adduct, carboxyl group-introduced polybutadiene resin, copolymer of acrylic acid or methacrylic acid and its ester, etc. are used, and have other polymer or functional group depending on the characteristics of electrodeposition film. The organic compound may be introduced into the polymer skeleton. When transparency is required, acrylic or polyester polymers are suitable. In addition, the amount of hydrophilic functional groups such as carboxyl groups and hydroxyl groups in the polymer is important.If the hydrophilic groups are too large, the electrodeposition layer will not be sufficiently insolubilized to form a non-uniform film, and if too small, the neutralization will occur. The water solubility of is insufficient.

As the resin for cationic electrodeposition, an epoxy resin having an amine added thereto, a cationized polybutadiene resin, a cationized acrylic resin, etc. are used. Add melamine, blocked isocyanate, etc. to the liquid,
In some cases, the coating film is thermally cured by eutectoid. The addition amount of the matrix resin is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the liquid crystal. If the amount of the liquid crystal used is too small, not only the transparency when the voltage is turned on is insufficient, but also a large amount of voltage is required to bring the film into a transparent state. If the amount used is too large, not only the scattering (turbidity) when the voltage is turned off becomes insufficient, but also the strength of the film decreases, which is not preferable.

A suitable neutralizing agent is further added to the coating solution. In the case of the anion electrodeposition method, examples of the neutralizing agent include potassium hydroxide and sodium hydroxide as the inorganic substance, and examples of the organic substance include triethylamine and diethylenetriamine. When the ion-dissociative group is a carboxyl group, the amount of addition of these neutralizing agents is a ratio of 0.2 to 2 equivalents per equivalent of the carboxyl group. Further, as an auxiliary agent that can be used, a surfactant for imparting dispersion stability to the liquid crystal-containing microcapsules, or a surfactant for facilitating escape of gas generated by hydrolysis of water from the deposited film, and fusion of matrix resin Examples thereof include an organic solvent for accelerating, a leveling agent for improving the smoothness of the coating film, and a defoaming agent.

As the organic solvent, isopropanol, n
-Butyl alcohol, t-butyl alcohol, benzyl alcohol, cyclopropanol, methyl cellosolve,
Ethyl cellosolve, isopropyl cellosolve, butyl cellosolve, diethylene glycol methyl ether, etc. are used. As described above, the polymer-dispersed liquid crystal layer preferably has a light-scattering ability in the state where no voltage is applied in order to enhance the display contrast. Therefore, it is preferable that the liquid crystal used has a high anisotropy in the refractive index, and Δn = 1.
Those of 5 to 2.5 are preferably used.

On the other hand, when liquid crystals in the polymer-dispersed liquid crystal layer are aligned in the direction of the electric field under application of an electric field, the scattering property of the polymer-dispersed liquid crystal layer is suppressed in order to suppress reflection at the front plate / air interface. Is preferably lost. Therefore, the refractive index of the polymer (matrix resin and capsule wall) forming the polymer-dispersed liquid crystal layer is close to the ordinary refractive index of liquid crystal,
It is preferably highly transparent. In order to provide the cell with a high voltage holding property, it is preferable that the liquid crystal mainly contains a halogen-based liquid crystal compound.

After forming a polymer dispersed liquid crystal layer on one electrode substrate, a cell whose gap is controlled by a spacer is formed, and a dichroic dye is provided in the gap between the polymer dispersed liquid crystal layer and the other electrode substrate. By injecting the added liquid crystal of
A low molecular weight liquid crystal layer is formed. Spacers for controlling the gap are preferably dispersed on the substrate before the polymer-dispersed liquid crystal layer is provided in advance. The spacer here means a particle or fiber having a certain system, which is used for the purpose of controlling the cell gap, and is a plastic particle, a glass particle, or a glass generally used in a liquid crystal optical element. Fibers and the like are preferably used.

As a method of spraying the spacer, generally used wet spraying and dry spraying can be applied. In order to prevent the spacer from falling into the bath in the subsequent electrodeposition step, it is preferable that the spacer be fixed to the substrate by using a hot-melt type adhesive, but since it is attached by charging, It can be applied without necessarily sticking. Cell bonding and liquid crystal injection process are TN type and S type.
The method used in the conventional cell assembly process such as the TN type can be used as it is. That is, after applying a sealant to the substrate on which the liquid crystal / polymer composite film is formed or the other substrate, the upper and lower substrates are aligned and pressure-bonded, and the sealant is cured by heat or UV. After that, liquid crystal is injected from the liquid crystal injection port, and finally the injection port is sealed.

Since the liquid crystal / polymer composite film has a smaller average film thickness than the particle system of the spacer, the cell gap is liquid crystal /
It will be controlled by the spacers scattered in the polymer composite membrane. At the time of pressure bonding, there is still a gap between the liquid crystal / polymer composite film and the counter electrode. This gap is filled with the injected liquid crystal. The sealant is applied using a screen printing machine or a dispenser. As the sealant, one-component curable epoxy resin, UV curable resin or the like is used. It is preferable that a spacer for securing a panel gap is kneaded in the sealant.

The liquid crystal is injected by the following procedure. First, the cell is left under a reduced pressure atmosphere for a while, and when the inside of the cell is sufficiently decompressed, the liquid crystal inlet is brought into contact with the liquid crystal reservoir. After contacting for a while, the atmosphere is returned to normal pressure. Liquid crystal is injected into the cell through the injection port and fills the gap. Let stand for several hours until the panel gap, which has become smaller due to the pressure difference, becomes uniform. In order to control the cell thickness, a weak pressure is usually applied and pressing is performed for several to ten and several hours. After that, the injection port is sealed. The sealing is usually performed by UV curing using a UV curing resin.

At the time of injecting the liquid crystal, heating or pressurization may be performed for the purpose of increasing the speed. Furthermore, in order to completely separate the liquid crystals in the polymer-dispersed liquid crystal layer, or the liquid crystal in the low-molecular liquid crystal layer and the liquid crystal in the polymer-dispersed liquid crystal layer,
A curable resin or the like can be filled or coated on the polymer-dispersed liquid crystal layer or in the gaps formed between pixels.

[0045]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. Example 1 After sandblasting, a film of aluminum was vacuum-deposited on a glass substrate whose surface was roughened by chemical etching with HF, and a stripe shape having a width of 250 μm and a pitch of 300 μm was formed by etching using a photoresist. A reflective electrode substrate having a reflective electrode pattern was formed. In addition, one end of this stripe pattern has 1
A step of 2 cm was provided for each book.

On the above reflective electrode substrate, a pressure-sensitive adhesive coating spacer having a particle diameter of 8 μm (XC-61 manufactured by Natco) was used.
0) was wet-sprayed and baked at 120 ° C. for 15 minutes. Next, a liquid crystal capsule was produced as follows. The following 2 in which 0.80 g of a red pigment (SI-426, manufactured by Mitsui Toatsu Dye) or 1.5 g of blue pigment (M-412, manufactured by Mitsui Toatsu Dye) was added as a dichroic pigment to an oil phase liquid crystal. Emulsions of various compositions were obtained by a membrane emulsification system (manufactured by Ise Chemical Industry Co., Ltd.) using porous glass.

Oil phase smectic liquid crystal TL-205 (manufactured by Merck) 100.00 g Dichroic dye (red) 0.80 g 2 Ethylhexyl acrylate 5.50 g Urethane acrylate A 1.10 g Azobisisobitylonitrile 0.06 g Water Phase-modified polyvinyl alcohol T-50 (Nippon Gosei Kagaku Kogyo Co., Ltd.) 5.50 g Ion-exchanged water 214.50 g Structural formula of the urethane acrylate A

[0048]

Embedded image

After heating the obtained emulsion at 85 ° C. for 5 hours, 370 g of ion-exchanged water was added to the dispersion, and at 70 ° C., 66 g of an aqueous prepolymer solution (4.5 g of 37% aqueous formaldehyde solution was added with 1. After adding 5 g and reacting at 60 ° C for 15 minutes, ion-exchanged water 60
g) was slowly added dropwise. 80 g of a hydrochloric acid aqueous solution having a pH of 2.5 was added dropwise, and the mixture was further reacted at 70 ° C. for 4 hours to form a double capsule wall. The microcapsules were settled by a centrifuge, and the average particle size was 1.8μ.
m microcapsules were obtained.

Using the obtained two-color microcapsules, electrodeposition coating solutions having the following compositions were prepared. Microcapsules 48.0 g Anionic acrylic resin 2.7 g Triethylamine 0.5 g Ethanol 5.5 g Ion-exchanged water 340.0 g A stainless steel plate is placed as the cathode and reflected as the anode in the capsule dispersion in which the blue dye is added first. The electrode substrate was immersed, and every other electrode was electrified at 20 V for 30 seconds. Pull up the glass substrate, wash with water, and then 6
It was dried at 0 ° C. for 5 hours.

Subsequently, the electrode substrate was similarly immersed in the capsule dispersion containing the red dye, and all electrodes were energized at 20 V for 30 seconds. Pull up the glass substrate, wash it with water,
It dried at 60 degreeC for 5 hours. As described above, the liquid crystal polymer composite film containing the blue dye and the liquid crystal polymer composite film containing the red dye were alternately formed on the reflective electrode substrate. The film thicknesses were all about 4.5 μm. A 700 Å polyvinyl alcohol film is formed on a TFT substrate having a pixel array of 300 μm × 300 μm by a spin coating method, a sealant is applied, and the liquid crystal polymer composite film is aligned with the reflective electrode substrate. And pasted together to cure the sealant.

Next, a low-molecular liquid crystal mixture having the following composition was injected while maintaining the cell at a constant temperature of 80 ° C. SI800 (Mitsui Toatsu Dye) 2.04 g SI486 (Mitsui Toatsu Dye) 0.48 g SI426 (Mitsui Toatsu Dye) 0.48 g TL-205 (Merck) 90.50 g CB-15 (Merck) 6.50g

One hue of the polymer liquid crystal layer of the multicolor display liquid crystal device formed as described above (displayed as pixel portion A in FIG. 1, hereinafter referred to as pixel portion A) is blue, and the other hue ( When the pixel portion B in FIG. 1 (hereinafter referred to as the pixel portion B) is red and the hue of the low-molecular liquid crystal layer is black, it shows black when no voltage is applied, and the ambient light reflectance at this time is 3 It was 0.3%. When 25 V was applied to the pixel unit A and the voltage applied to the pixel unit B was changed to 0 to 25 V, the entire hue continuously changed to gray, red, and white.
On the other hand, when 25 V was applied to the pixel unit B and the voltage applied to the pixel unit A was changed to 0 to 25 V, the entire hue continuously changed to gray, blue, and white.

The hue when a voltage of 25 V was applied to both pixel portions A and B was white as described above, and the reflectance at this time was 27%. The reflectance is measured by measuring the reflected light intensity in the normal direction using a parallel light beam of halogen light incident at an angle of 30 ° from the normal direction, and setting the reflected light intensity of a white paper as 100%. Was calculated.

[0055]

[Effect] In the case of the reflection type liquid crystal display device, low power consumption can be achieved because no backlight is used. For both reflective and transmissive types, the dichroic dye contained in the polymer-dispersed liquid crystal layer and the dichroic dye contained in the low-molecular liquid crystal layer are used, or the subtractive color mixture method is used together. Since it is displayed in a highly efficient manner, the two types of dichroic dye layers are in close contact with each other, so there is little parallax even when viewing the display from an oblique direction, and the display color is excellent. A variety of display devices can be created.

Furthermore, when a polymer-dispersed liquid crystal layer is patterned on the pixel electrode of each pixel portion and a low-molecular liquid crystal layer is filled after cell assembly, when a conventional two-layer display device is used in combination. In comparison, it is easier to manufacture. In particular, if the polymer dispersed liquid crystal layer is patterned by the electrodeposition method, the patterning can be easily and accurately performed without making difficult alignment on the pixel electrode formed in advance.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a multicolor liquid crystal display device of the present invention.

FIG. 2 is a configuration diagram showing an example of a multicolor liquid crystal display device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Switching element 2 ... Transparent pixel electrode 3 ... Transparent substrate (entire plate) 4 ... Reflective electrode 5 ... Substrate (rear plate) 6 ... Display layer 7 ... Liquid crystal 8 ... Polymer 9 ... Polymer dispersed liquid crystal layer 9a ... Pixel Part A 9b ... Pixel part B 10 ... Low-molecular liquid crystal layer

Claims (8)

[Claims] 1. A multicolor display device in which a display layer is sandwiched between a pair of electrode substrates, at least one of which has a light-transmitting property, wherein the display layer has a liquid crystal containing a dichroic dye in the form of droplets in a polymer. A polymer-dispersed liquid crystal layer dispersed in, and a low-molecular liquid crystal layer containing a dichroic dye having a hue different from that of the dichroic dye,
A multicolor liquid crystal display device, which is laminated at least in a pixel portion. 2. The multicolor liquid crystal display device according to claim 1, wherein the dichroic dyes in the polymer-dispersed liquid crystal layer are different between adjacent pixels. 3. The multicolor liquid crystal display device according to claim 1, wherein a plurality of pixels are arranged in a matrix. 4. One of the electrodes is light-reflecting.
3. The multicolor liquid crystal display device according to any one of 3 above. 5. The multicolor liquid crystal display device according to claim 1, wherein a switching element is formed in each pixel. 6. The multicolor liquid crystal display device according to claim 1, wherein a chiral nematic liquid crystal is added to the low-molecular liquid crystal layer. 7. The multicolor liquid crystal display device according to claim 1, wherein an alignment film is formed on the electrode substrate on the low-molecular liquid crystal layer side. 8. The multicolor liquid crystal display device according to claim 1, wherein the polymer dispersed liquid crystal layer is formed on the electrode by an electrodeposition coating method.