JPH0519239A - Liquid crystal cell and liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide the liquid crystal cell and liquid crystal display device which are drastically decreased in driving voltage, is sharpened in the threshold value of electrooptical characteristics and has an excellent contrast. CONSTITUTION:The liquid crystal cell has a polymer layer 10 dispersed with small liquid crystal drops communicating with each other and at least two transparent conductive substrates 15, 15 crimping this polymer layer 10. The average grain sizes of the small liquid crystal drops are within a >=2mum and <=8mum range and the diameters of the small liquid crystal drops have the grain size distribution in which the number of the small liquid crystal drops having the average grain size within a + or -2mum range is >=80% of the total number of the small liquid crystal drops. Further, the ratio at which the entire volume of the small liquid crystal drops occupies the entire volume of the polymer layer 10 is in a >=50% and <=95% range and the critical surface tension of the polymer used for the polymer layer 10 is <=35dynes/cm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal cell and a liquid crystal display device, and more particularly, to a liquid crystal droplet and a polymer which are in communication by changing the difference in refractive index between the liquid crystal droplet and the polymer which are in communication with each other by an external voltage. The present invention relates to a liquid crystal cell using a liquid crystal display mode for controlling light scattering at an interface and a liquid crystal display device using the liquid crystal cell.

[0002]

2. Description of the Related Art Liquid crystal display devices are used, for example, in flat panel display devices such as projection televisions and personal computers, or in display plates, windows, doors, walls, etc. that utilize the shutter effect.

Conventionally, as a mode of operation of a liquid crystal display device, a TN (Twisted Nematic) mode and a STN (Super Twisted Nematic) mode using a nematic liquid crystal applying an electro-optical effect have been put into practical use and widely used. Has been. Also, an FLC (Ferroelectric Liqid Crystal) mode using a ferroelectric liquid crystal has been proposed. A liquid crystal display device using these operation modes requires a polarizing plate and also requires a liquid crystal alignment process. On the other hand, a DS (Dynamic
Scattering: Dynamic scattering mode, PC (Phase Chbange)
: Phase transition) mode is also available.

Recently, a mode in which a polarizing plate is not required and an alignment treatment of liquid crystal is not required, and the birefringence of the liquid crystal is applied to electrically control whether the liquid crystal is in a transparent state or a white turbid state Is proposed. This mode is based on changing the orientation of liquid crystal molecules in liquid crystal spherical droplets dispersed in a support medium (polymer) by an electric field to match the refractive index of the liquid crystal molecules with the refractive index of the support medium. That is, in the state where no electric field is applied, the optical axes of liquid crystal droplets are randomly arranged, the ordinary light refractive index does not match the refractive index of the polymer, and opaque white is shown by light scattering. When an electric field is applied, the optical axes of the liquid crystal droplets are aligned in the direction of the electric field, and the ordinary light refractive index matches the refractive index of the polymer, so scattering is reduced and the liquid crystal becomes transparent.

The following types of liquid crystal cells and liquid crystal display devices operating in this mode have been proposed.

(A) A method disclosed in JP-A-58-501631 in which a liquid crystal is contained in a polymer capsule.
Since the liquid crystal droplets are independent cells, the driving voltage that causes a change in the liquid crystal orientation is large, and therefore the range of use is narrow.

(B) A method in which a liquid crystal is deposited by curing a mixture of a light or thermosetting resin and a liquid crystal, as disclosed in Japanese Patent Publication No. 61-502128, and liquid crystal droplets are formed in the resin. . For this method, Japanese Patent Laid-Open No. 3-7
2317 discloses a method for controlling a liquid crystal droplet size.
Since the manufacturing method using phase separation is used, it is difficult to precisely control the liquid crystal droplet size.

(C) A method disclosed in Japanese Patent Application Laid-Open No. 3-59515, in which a porous polymer film is impregnated with liquid crystal. In this method, phase separation is not used when creating liquid crystal droplets, so the degree of freedom in the selection of applicable resins and liquid crystals is very large, and the polymer porous membrane can be sufficiently purified. However, at present, the liquid crystal droplet size cannot be controlled sufficiently.

(D) A method disclosed in Japanese Patent Application Laid-Open No. 3-46621, in which polymer beads serving as a light scattering source are suspended in a liquid crystal between two transparent electrodes. With this method,
Although the light scattering intensity is high, it is difficult to uniformly disperse the beads, and display unevenness easily occurs.

(E) As disclosed in JP-A-3-61926, in order to reduce the driving voltage, the liquid crystal droplets and the polymer are formed at the interface between the liquid crystal droplets and the polymer in the polymer dispersed device. Method to reduce the interaction of.

[0011]

As described above, the conventional dispersion mode (liquid crystal droplets dispersed in a polymer)
According to the liquid crystal display device utilizing the above, there is a problem that the size of the liquid crystal droplet size is not sufficiently uniform and the interaction between the polymer and the liquid crystal is large, so that the driving voltage is large. Further, since the sizes of the liquid crystal droplets are not sufficiently uniform, liquid crystal droplets of various diameters are present, and the driving voltage is different for each liquid crystal droplet. As a result, there arises a problem that the threshold in electro-optical characteristics lacks agility. Further, since there are many small-sized liquid crystal droplets having low light scattering ability, there is a problem that the display contrast is relatively low.

Accordingly, the present invention provides a liquid crystal cell and a liquid crystal display device having excellent contrast by reducing the drive voltage and increasing the threshold value in electro-optical characteristics. .

[0013]

In order to solve the above problems, the present inventor has made a technique for making the particle size distribution of liquid crystal droplets uniform to the limit and the interaction at the interface between the liquid crystal droplets and the polymer. The method of reducing the above has been earnestly studied. As a result, when the condition that the particle size distribution of liquid crystal droplets has an unprecedented uniformity and the surface energy of the surface of the polymer in contact with the liquid crystal is low, a low voltage that could not be achieved so far is obtained. They have found that it is possible to manufacture a liquid crystal cell and a liquid crystal display device using a light dispersion mode that is driven, has agile electro-optical characteristics, and is excellent in contrast, and completed the present invention.

That is, according to the present invention, communicating liquid crystal droplets are dispersed, and at least one polymer layer sandwiched between at least two conductive substrates is provided, and the average particle diameter of the liquid crystal droplets is It has a particle size distribution in which the diameter of the liquid crystal droplets is in the range of 2 μm or more and 8 μm or less and the diameter of the liquid crystal droplets is in the range of average particle diameter ± 2 μm or more and 80% or more of the total number. A liquid crystal in which the total volume of the liquid crystal droplets accounts for 50% or more and 95% or less of the total volume of the polymer layer, and the critical surface tension of the polymer used in the polymer layer is 35 dynes / cm or less. A cell, a signal electrode and a scan electrode arranged in a matrix, a switching transistor arranged at each intersection of the signal electrode and the scan electrode, and connected to the switching transistor. The liquid crystal cell includes a first substrate on which a pixel electrode is formed and a second substrate on which a counter electrode for the pixel electrode is formed, and the liquid crystal cell described above is sandwiched between the first and second substrates. A liquid crystal display device is provided.

Hereinafter, the present invention will be described specifically and in detail.

According to the results of studies by the present inventors, when the average particle size of liquid crystal droplets is smaller than 2 μm, the number of liquid crystal droplets which are not scattered by visible light increases, and as a result, the light scattering property when no voltage is applied. Will fall. Moreover, when a voltage is applied to the liquid crystal, the liquid crystal does not become sufficiently transparent. On the other hand, if the average particle size of the liquid crystal droplets is larger than 8 μm, the liquid crystal droplets occupy most of the cell gap, and the blocking property of the light scattering characteristics when no voltage is applied decreases. Not preferable. Therefore, the range of the average particle size of the liquid crystal droplets is preferably 2 μm or more and 8 μm or less, and more preferably 3 μm or more and 5 μm or less.

The most important feature of the present invention lies in the uniformity of the particle size distribution of liquid crystal droplets and the manufacturing method of the liquid crystal cell.

The liquid crystal cell is manufactured as follows. First, a light or thermosetting resin and fine particles having an extremely uniform particle size distribution are mixed, and this mixture is uniformly applied on a substrate to be an electrode, and then the resin in the mixture is cured by light or heat. Further, the hardened resin, that is, the fine particles dispersed in the polymer are eluted with a solvent in which the well dissolves, and a porous membrane having a large number of communicating small spherical pores is formed. The porous film is impregnated with a liquid crystal material, and another electrode is bonded onto the porous film on the opposite side of the already attached electrode to form a liquid crystal cell.

As described above, this manufacturing method is characterized in that the fine particles are used as a type of holes for liquid crystal droplets. Therefore, the particle size of liquid crystal droplets is determined by the particle size of fine particles,
The uniformity of the particle size distribution of liquid crystal droplets depends on the uniformity of the particle size distribution of fine particles. As the material for the fine particles, polymer beads such as polymer latex, or inorganic fine particles such as calcium sulfite and monodisperse silica fine particles may be used.
In the method of the present invention, which requires a uniform particle size distribution, the advanced in colloid and interface method is used.
Science (Advances in Colloid and Interface Scie
nce) 13 (1980) 101 to 140, it is most preferable to use latex fine particles prepared by the method described in the above, since the particle size distribution can be controlled best.

The uniformity of the particle size distribution of the liquid crystal droplets affects the lowering of the driving voltage of the liquid crystal display device and the agility of the threshold value in the electro-optic crystal characteristics. There are liquid crystal droplets that operate at various drive voltages from large to small, and as a result, the liquid crystal display device has a high drive voltage, and the agility of the operation behavior is reduced. Therefore, the uniformity of the particle size distribution of liquid crystal droplets is a very important factor for liquid crystal display devices.
The liquid crystal droplet size distribution is such that the liquid crystal droplet size is the average particle size ± 2.
The number of liquid crystal droplets within the range of μm is preferably 80% or more of the total number. Further, it is preferable that the number of the liquid crystal droplets in which the particle diameter of the liquid crystal droplets is within the range of the average particle diameter ± 2 μm is 90% or more of the total number.

The thickness of the polymer layer containing liquid crystal droplets is 5 μm.
m or more and 18 μm or less, and more preferably 10
It is not less than μm and not more than 15 μm. When this thickness is less than 5 μm, the light scattering property when no voltage is applied is insufficient,
On the other hand, when it is larger than 18 μm, the electric field strength for voltage driving of the liquid crystal element is insufficient and sufficient transparency cannot be obtained when a voltage is applied, or the driving voltage needs to be increased. High drive voltage means high power consumption,
It also means that a drive circuit such as a TFT (Thin Film Transistor) needs to be improved.

The volume fraction of the entire liquid crystal droplets in the polymer layer containing the liquid crystal droplets is preferably 50% or more and 95% or less, and more preferably 70% or more and 85% or less. If the volume fraction of the liquid crystal is less than 50%, the number of times the incident light is scattered by the liquid crystal droplets is reduced, so that sufficient light scattering intensity cannot be obtained. Also,
When the volume fraction of the liquid crystal is larger than 95%, the physical volume of the polymer wall is lowered due to the reduction of the volume fraction of the polymer, and the polymer network cannot be formed and maintained.

Another point of the present invention is the critical surface tension of the polymeric material. The inventors of the present invention have found that when the critical surface tension of the polymer material is increased, the interaction between the liquid crystal and the polymer is increased, and as a result, the driving voltage is increased, and even if the liquid crystal droplets have a uniform particle size distribution. However, it has been found that the object of the present invention cannot be achieved. The liquid crystal in contact with the solid surface usually has a critical change in the interaction strength between the liquid crystal and the polymer at the point where the critical surface tension γ _c of the solid surface and the surface tension γ ₁ of the liquid crystal become equal,
The orientation of liquid crystal near the solid surface is homogeneous (γ ₁
-Γ _c <0) to homeotropic (γ ₁ −γ _c > 0)
It can be changed to Molecular Crystals and Liqu
id Cryst-als), Vol. 24, pp. 59-68 (1973). Further, the surface tension of a liquid crystal having a highly polar functional group such as a cyano group in the molecule is often 35 dynes / cm or more, and the surface tension of a fluorine-based liquid crystal having a small surface tension is about 30 dynes / cm. Therefore, the critical surface tension of the polymer used in the present invention is preferably 35 dynes / cm or less, more preferably 30 dynes / cm or less.

The polymer material used is a resin or the like prepared by curing a light or thermosetting resin with light or heat.

Examples of the light or thermosetting resin include C
Acrylic acid and acrylate having 3 or more long-chain alkyl groups or benzene rings, more specifically, isobutyl acrylate, stearyl acrylate, lauryl acrylate, isoamyl acrylate, n-butyl methacrylate, n-lauryl methacrylate. , Tridecyl methacrylate, n-stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-
Phenoxyethyl methacrylate, bisphenol A dimethacrylate, bisphenol A diacrylate, and a polyfunctional resin having two or more functional groups such as 1,4-butanediol dimethacrylate and 1,6-hexane for increasing the physical strength of the polymer. Diol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, more preferably a halogenated, especially chlorinated or fluorinated, resin of these monomers, for example 2.2.3. 4.4.4-Hexafluorobutyl methacrylate, 2.2.3.3.4.4-4
Hexachlorobutyl methacrylate, 2.2.3.3-
Tetrafluoropropyl methacrylate, 2.2.3.3
-Tetrachloropropyl methacrylate, perfluorooctylethyl methacrylate, perchlorooctylethyl methacrylate, perfluorooctylethyl acrylate, perchlorooctylethyl acrylate.
As the thermosetting resin, ethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, epoxy resin represented by glycidyl ethers such as 1.6-hexanediol diglycidyl ether, polyurethane resin having an isocyanate group, Alternatively, a silicone resin having a double bond containing Si can be used. These monomers may be used alone or in combination of two or more. Moreover, you may mix and use the polymer and oligomer which were chlorinated or fluorinated with these monomers as needed. Furthermore, in order to make the light or heat reaction more perfect and ensure the physical strength,
Peroxide which does not react in the first step of light or heat reaction may be added to the above monomer in advance and further heated after the completion of the first step of curing to proceed the reaction.

The liquid crystal is an organic substance mixture which exhibits a liquid crystal state at around room temperature and has a positive dielectric anisotropy, and includes nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal and the like. These liquid crystals may be mixed, and nematic liquid crystals or nematic liquid crystals to which cholesteric liquid crystals are added are particularly preferable in terms of characteristics.
More preferred is a liquid crystal having a low surface tension for use by impregnating a porous material having a low critical surface tension, and a liquid crystal having a functional group such as a fluorine atom which lowers the surface tension in a compound. Specifically, as commercially available liquid crystal materials (mixed composition), ZLI-4792, ZLI-4801-000,
There are fluorine-based liquid crystals such as ZLI-4801-001 (Merck).

The present invention achieves the object by simultaneously optimizing the conditions of the average particle size of the liquid crystal droplets, the particle size distribution, the liquid crystal content and the critical surface tension of the polymer used. The effect of the present invention cannot be sufficiently brought out only by satisfying the condition of.

[0028]

EXAMPLES Examples and comparative examples of the present invention will be described in detail below with reference to tables and drawings.

FIG. 1 shows a sectional view of an embodiment of the liquid crystal cell according to the present invention. Further, FIG. 2 shows a sectional view of an embodiment of the liquid crystal display device according to the present invention.

As shown in FIG. 1, the liquid crystal droplets 11 communicating with each other are dispersed in the polymer layer 10, and the polymer layer 10 is sandwiched between two transparent conductive substrates 15. Polymer layer 10
Details of the polymer, the liquid crystal, and the conductive substrate 15 used for are described below.

Although the polymer layer 10 is sandwiched between two transparent conductive substrates in this embodiment, two or more transparent conductive substrates may be used, or two or more transparent conductive substrates may be used. One of the transparent conductive substrates may be opaque or reflective.

The liquid crystal display device according to the embodiment has a structure in which two conductive substrates 16 and 17 are opposed to each other and the above liquid crystal cell is sandwiched between the conductive substrates 16 and 17. The conductive substrate 16 is composed of the transparent insulating layer 12 and the alignment electrode 13, and the conductive substrate 17 is composed of the transparent insulating layer 12 and the pixel electrode 14. As shown in FIG. 2, on the conductive substrate 17, signal lines and scanning lines (not shown) arranged in a matrix and TFTs arranged at their intersections.
(Not shown) and the pixel electrode 14 are arranged. Also,
A counter electrode 13 is arranged on the other conductive substrate 16 so as to face the pixel electrode 14. This structure is called a TFT system and is well known.

Example 1 0.3 g of trimethylolpropane trimethacrylate,
A mixture of 1.7 g of perfluorooctylethyl methacrylate and 0.06 g of irgacure184 manufactured by Ciba-Geigy, having an average particle size of 4.2 μm and an average particle size of ± 2
The number of particles within μm is 9 with respect to the total number of particles.
8 g of polystyrene particles having a particle size distribution of 5% were thoroughly mixed in 20 ml of ethyl alcohol. Then, after air-drying by the bar coat method, the layer thickness is 10 μm.
The mixture was attached to glass with ITO (a mixture of indium oxide and tin oxide) (Nippon Sheet Glass' ITO-500 flint glass with flint glass) so that the above became, and further air-dried in nitrogen. Then, the resin was cured by irradiating with ultraviolet rays for 2 minutes at a location 100 mm below the metal halide lamp (80 W). It was left under nitrogen at 100 ° C. for 1 hour for a more complete cure.

Then, the polystyrene fine particles were gradually dissolved with butyl acetate, and butyl acetate was removed with dry acetone and dried to obtain a porous body. When the cross section of the produced porous body was observed by SEM (scanning electron microscope), the average pore diameter was 4.3 μm, and the average pore diameter was ± 2 μm.
It was revealed that the number of pores within the range was 93% with respect to the total number of pores (the liquid crystal 11 shown in FIG. 1 was impregnated when measuring the average pore diameter). The diameter R of each spherical portion of the communicating hole was measured before impregnation with the liquid crystal 11).

Keep the liquid crystal cell thickness at 12 μm with a spacer,
A liquid crystal cell was created by impregnating the liquid crystal ZLI-3219 manufactured by Merck.

The volume fraction of the liquid crystal in the porous body was determined by extracting the liquid crystal in the liquid crystal cell with acetone and quantifying the amount.
As a result, the volume fraction of the liquid crystal in this case was 76%.

The critical surface tension of the resin used was such that the used monomer was sandwiched between PET (polyethylene terephthalate) film lumirror manufactured by Toray and irradiated with ultraviolet rays, and then the contact angle was measured with a series of standard wetting index liquids to obtain a contact angle of 0. The extrapolated value was defined as the critical surface tension γ _c . As a result, the critical surface tension γ _c in this case was 25 dynes / cm.

The electro-optical characteristics were measured using the liquid crystal display device prepared as shown in FIG.

The electro-optical characteristics of the produced liquid crystal cell are judged from the threshold voltage V _th and the saturation voltage V _s . The threshold voltage V _th is 10% of the value obtained by subtracting the light transmittance T ₀ when no voltage is applied from the light transmittance saturation value T _s (when a high voltage is applied). It is the applied voltage when it reaches.
In addition, the saturation voltage V _s is equal to the saturation value T of the light transmittance.
90% of the value obtained by subtracting the light transmittance T ₀ when no voltage is applied from _s
It is the applied voltage when the transmittance of is reached. The threshold value V _th of the first embodiment is 2.6 V, the saturation voltage V _s is 5.1 V,
The driving voltage was extremely low compared to the conventional liquid crystal cell, and the characteristics were excellent agility.

The straight-line light transmittance of the prepared liquid crystal cell was 0.9% when no voltage was applied, and was 8% when a 50V AC voltage was applied.
It was 2.1%, and good contrast was obtained.

As the liquid crystal material, E-8, E-44, ZLI-1289 (manufactured by Merck Ltd.) and the like can be used in addition to the liquid crystal material used in this embodiment.

Examples 2 and 3 and Comparative Examples 1 and 2 Average particle size is 1.3 μm (Comparative Example 1), 2.1 μm (Example 2), 7.8 μm (Example 3), 10.2 μm (Comparison) Example 2) and using polystyrene fine particles having a particle size distribution in which the number of particles having an average particle size within ± 2 μm is approximately 95% of the total number of particles, liquid crystal is used as in Example 1. A cell was prepared, and electro-optical characteristics (threshold voltage V _th , saturation voltage V _s ) and light transmission characteristics (straight-line light transmittance T ₀ when no voltage was applied, when 50 V AC voltage was applied) were obtained as in Example 1. The straight light transmittance T ₅₀ ) was measured. The results are shown in Table 1. From this table, it can be seen that Comparative Example 1 has a larger threshold voltage V _th than Examples 2 and 3, and Comparative Example 2 has a poorer contrast than Examples 2 and 3.

[0043]

[Table 1]

Examples 4 and Comparative Examples 3 and 4 The average particle size is about 4 μm, and the particle size is ± 2.
The number of particles within the range of μm is based on the total number of particles,
A liquid crystal cell was prepared in the same manner as in Example 1 using polystyrene fine particles having a particle size distribution of 82% (Example 4), 70% (Comparative Example 3) and 50% (Comparative Example 4). Similarly, electro-optical characteristics (threshold voltage V _th , saturation voltage V _s ) and light transmission characteristics (straight light transmittance T ₀ when no voltage is applied, straight light transmittance T ₅₀ when 50 V AC voltage is applied) are measured. did. The results are shown in Table 2. From this table, it is understood that Comparative Examples 3 and 4 have a larger threshold voltage V _{th and} inferior contrast as compared with Example 4.

[0045]

[Table 2]

Example 5 and Comparative Examples 5 and 6 When the polystyrene fine particles used in Example 1 and the curable resin were mixed, 0.3 g of trimethylolpropane trimethacrylate, 1.7 g of perfluorooctylethylmethacrylate and Ciba Geigy were used. Made by irgacure184 0.06g
The amount of polystyrene fine particles added to the mixture was 1.3 g (Comparative Example 5), 3.0 g (Example 5), 48 g.
(Comparative Example 6, 10 parts of ethyl alcohol to dilute the mixture)
The liquid crystal cell having various volume fractions of liquid crystal is prepared in the same manner as in Example 1, and the electro-optical characteristics (threshold voltage) are added in the same manner as in Example 1. V _th , saturation voltage V _s ) and light transmission characteristics (straight light transmittance T ₀ when no voltage was applied, straight light transmittance T ₅₀ when 50 V AC voltage was applied) were measured. The results are shown in Table 3. From this table, it is understood that Comparative Example 5 has a larger threshold voltage V _{th and} inferior contrast as compared with Example 5.

In Comparative Example 6, the strength of the polymer matrix prepared was weak and stable display characteristics could not be measured.

[0048]

[Table 3]

Example 6, Comparative Examples 7 and 8 Using the polystyrene fine particles used in Example 1, 1.7 g of n-stearyl methacrylate, 0.3 g of trimethylolpropane trimethacrylate and Ciba Geigy ir
a mixture with 0.06 g of gacure184 (Example 6), or
A mixture of 1.7 g of 2-hydroxyethyl acrylate, 0.3 g of trimethylolpropane trimethacrylate and 0.06 g of irgacure184 manufactured by Ciba-Geigy (Example 7), or 1.7 g of 2-acryloyloxyethylsuccinic acid and trimethylolpropanetri. Using a mixture of 0.3 g of methacrylate and 0.06 g of irgacure184 manufactured by Ciba-Geigy (Example 8), a liquid crystal cell having different chemical affinity of the inner wall of the porous body was prepared, and electro-optical characteristics (threshold The value voltage V _th , the saturation voltage V _s ), the light transmission characteristics (the straight light transmittance T ₀ when no voltage was applied, the straight light transmittance T ₅₀ when a 50 V AC voltage was applied) and the critical surface tension γ _c were measured. The results are shown in Table 4. From this table, it is understood that Comparative Examples 7 and 8 have a large critical surface tension, and as a result, the threshold voltage V _th is larger than that of Example 6.

[0050]

[Table 4]

Examples 7, 8 and 9 Using the method described in Example 1, a polymer matrix having a very uniform pore size distribution was prepared, and the matrix was used as a liquid crystal component by ZLI-4792 (Example 7) manufactured by Merck. , ZLI-48
01-000 (Example 8) and ZLI-4801-001 (Example 9) were impregnated to prepare a liquid crystal cell in the same manner as in Example 1, and electro-optical characteristics (threshold voltage V _th , saturation voltage V _s ) and light transmission characteristics (straight light transmittance T ₀ when no voltage was applied, straight light transmittance T ₅₀ when 50 V AC voltage was applied) were measured. The results are shown in Table 5.

[0052]

[Table 5]

[0053]

As described in detail above, according to the present invention, the large driving voltage and the low contrast, which are the most obstacles in the polymer dispersion type liquid crystal cell and the liquid crystal display device, can be solved at once. Therefore, the present invention is extremely important in industrial production of polymer-dispersed liquid crystal cells.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a liquid crystal cell according to the present invention.

FIG. 2 is a sectional view of an embodiment of a matrix liquid crystal display device according to the present invention.

[Explanation of symbols]

10 Polymer 11 LCD 12 Transparent insulation layer 13 Counter electrode 14 Pixel electrode 15,16,17 Conductive substrate

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Fumiaki Funada             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Within Yap Co., Ltd.

Claims (2)

[Claims] 1. A liquid crystal cell in which communicating liquid crystal droplets are dispersed and comprising at least one polymer layer sandwiched by at least two conductive substrates, wherein the liquid crystal droplets have an average particle size of 2 μm. As described above, the number of the liquid crystal droplets within the range of 8 μm or less and the diameter of the liquid crystal droplets within the range of the average particle diameter ± 2 μm is 80 with respect to the total number of the liquid crystal droplets.
%, And the ratio of the total volume of the liquid crystal droplets to the total volume of the polymer layer is 50%.
% To 95%, and the critical surface tension of the polymer used in the polymer layer is 35 dynes.
/ Cm or less, a liquid crystal cell. 2. A signal electrode and a scanning electrode arranged in a matrix, a switching transistor arranged at each intersection of the signal electrode and the scanning electrode, and a pixel electrode connected to the switching transistor. First
And a second substrate on which a counter electrode for the pixel electrode is formed, wherein the liquid crystal cell according to claim 1 is sandwiched between the first and second substrates. Characteristic liquid crystal display device.