JP2002169019A - Retardation film and reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reflection luminance, contract and viewing angle characteristics of a reflection type liquid crystal display device and to avoid coloring. SOLUTION: The retardation film consists of a polymer film having 30 to 115 nm retardation Re450 measured at 450 nm wavelength and 60 to 130 nm retardation Re590 measured at 590 nm wavelength and satisfying Re590-Re450 >=2 nm. The retardation film is used for the reflection type liquid crystal display device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a retardation plate and a reflection type liquid crystal display device using the same.

[0002]

2. Description of the Related Art A reflection type liquid crystal display device is used as a display of a portable device such as a portable information terminal, a portable game machine or a portable telephone because a backlight is not required and the power consumption is small. The reflection type liquid crystal display device includes a reflection plate,
It has a basic structure combining a liquid crystal cell and a polarizing film. Regarding the display mode of the liquid crystal cell, TN (Twisted
Nematic), STN (Supper Twisted Nematic), HA
N (Hybrid Aligned Nematic), HPDLC (Holograp
hic Polymer Dispersed Liquid Crystal), GH (Gues
Various display modes such as t-Host) have been proposed.
TN mode and GH mode reflective liquid crystal display devices are:
It has already been put to practical use. In a transmission type liquid crystal display device, two polarizing films are indispensable, but in a reflection type liquid crystal display device, λ / 4 is used.
By using a plate, an image can be displayed even with one polarizing film. When one polarizing film is reduced, light does not attenuate,
A bright image can be displayed. A reflection type liquid crystal display device having a λ / 4 plate is disclosed in JP-A-10-186357.
There is a description in the publication.

In a reflection type liquid crystal display device having a λ / 4 plate, the performance of the λ / 4 plate is very important. Conventional λ / 4
Although the plate is referred to as a “λ / 4 plate”, the plate has a specific wavelength of λ / 4.
Most achieved / 4. If the wavelength range in which λ / 4 can be achieved is narrow, the contrast of a displayed image is reduced. JP-A-5-27118 and JP-A-5-271
No. 19 discloses a retardation plate in which a birefringent film having a large retardation and a birefringent film having a small retardation are laminated such that their optical axes are orthogonal to each other. However, when two films are stacked, the λ / 4 plate becomes thicker, and the advantage of a thin reflective LCD device is reduced. Further, when the light passes through the thick λ / 4 plate, the light is attenuated, and the reflection luminance is reduced. Further, problems such as a decrease in contrast of an image viewed from an oblique direction and a change in tint were also observed.

[0004] WO 00/65384 discloses a retardation plate composed of one sheet of cellulose ester film containing an aromatic compound. This retardation plate is made of one piece of cellulose ester film and has a wavelength of λ / 4 in a wide wavelength range.
Or, λ / 2 is achieved. When the retardation plate achieves λ / 4, specifically, Re450 which is a retardation value measured at a wavelength of 450 nm is 100 to 12
Re590, which is 5 nm, which is a retardation value measured at a wavelength of 590 nm, is 120 to 160 nm, and satisfies the relationship of Re590-Re450 ≧ 2 nm. When the retardation plate described in WO 00/65384 is incorporated in a reflection type liquid crystal display device as a λ / 4 plate, the reflection luminance, contrast, and viewing angle characteristics can be improved without impairing the advantages of the liquid crystal display device being thin. An improved image can be displayed.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reflection type liquid crystal display device which displays an image in which the tint is eliminated in addition to the reflection luminance, contrast and viewing angle characteristics. Another object of the present invention is to provide a retardation plate that can eliminate the tint of the reflection type liquid crystal display device.

[0006]

The object of the present invention has been achieved by the following reflective liquid crystal display devices (1) to (6). (1) Re450, which is a retardation value measured at a wavelength of 450 nm, is 30 to 115 nm and a wavelength of 590
Re590, which is a retardation value measured in nm, is 60 to 130 nm, and Re590-Re
A retardation plate comprising one polymer film satisfying a relationship of 450 ≧ 2 nm.

(2) Re450, a retardation value measured at a wavelength of 450 nm, is 40 to 115 nm; Re550, a retardation value measured at a wavelength of 550 nm, is 60 to 125 nm;
Re590, which is a retardation value measured in nm, is 70 to 130 nm, and Re590-Re
The retardation plate according to (1), which satisfies the relationship of 550 ≧ 2 nm. (3) The refractive index nx in the in-plane slow axis direction, the refractive index ny in the direction perpendicular to the slow axis in the plane, and the refractive index nz in the thickness direction are 1 ≦ (nx−nz). ) / (Nx−n)
y) The retardation plate according to (1), which satisfies the relationship of ≦ 2.

(4) The retardation plate according to (1), wherein the polymer film is a cellulose ester film. (5) The retardation plate according to (4), wherein the polymer film is a stretched cellulose ester film. (6) SA which is the maximum stretching ratio and SB which is the stretching ratio in the direction perpendicular to the stretching direction are 1 <SA / SB ≦
The retardation plate according to (5), which satisfies the relationship of (3).

(7) A reflection type liquid crystal display device provided with a reflection plate, a liquid crystal cell, a retardation plate, and a polarizing film, wherein the retardation plate has a retardation value Re450 of 30 to 115 nm measured at a wavelength of 450 nm. And the wavelength is 590n
Re590, which is the retardation value measured in m, is 7
0-130 nm, and Re590-Re4
A reflective liquid crystal display device comprising a single polymer film satisfying a relationship of 50 ≧ 2 nm. (8) The reflection type liquid crystal display device according to (7), wherein the reflection plate, the liquid crystal cell, and the polarizing film are laminated in this order, and the retardation plate is disposed between the reflection plate and the polarizing film.

[0010]

As a result of the present inventor's research on a retardation plate made of a single polymer film, surprisingly, the present inventors have found that a retardation plate that achieves λ / 4 in a wide wavelength range has It has been found that better results may be obtained with a retarder having a lower retardation value. That is, in the reflection type liquid crystal display device, the conventional λ
If a retardation plate having a lower retardation value is used instead of the / 4 plate (described in WO00 / 65384), the tint of the image (particularly, the tint occurring in a gray region) can be eliminated. The reason for this is presumed that the difference between the retardation value corresponding to λ / 4 and the lower retardation value of the retardation plate eliminates the coloring of the image.
As a result, in the present invention, in addition to the reflection luminance, contrast and viewing angle characteristics of the image displayed on the reflection type liquid crystal display device, the color tone is eliminated only by using the retardation plate made of one polymer film. can do.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Reflection type liquid crystal display device] A typical reflection type liquid crystal display device includes, in order from the bottom, a lower substrate, a reflection electrode, a lower alignment film, a liquid crystal layer, an upper alignment film, a transparent electrode, and an upper substrate. ,
It consists of a retardation plate and a polarizing film. The lower substrate and the reflective electrode constitute a reflector, and the lower to upper alignment films constitute a liquid crystal cell. The retardation plate can be arranged at any position between the reflection plate and the polarizing film. In the case of color display, a color filter layer is further provided. The color filter layer is preferably provided between the reflective electrode and the lower alignment film or between the upper alignment film and the transparent electrode. A reflective plate may be separately attached using a transparent electrode instead of the reflective electrode.
A metal plate is preferable as the reflector used in combination with the transparent electrode. If the surface of the reflector is smooth, only the specular reflection component may be reflected and the viewing angle may be narrowed. Therefore, it is preferable to introduce an uneven structure on the surface of the reflection plate. When the surface of the reflection plate is flat (instead of introducing an uneven structure on the surface), a light diffusion film may be attached to one side (cell side or outside) of the polarizing film.

The liquid crystal cell is a TN (twisted nematic).
Type, STN (Supper Twisted Nematic) type or HAN
(Hybrid Aligned Nematic) type is preferred.
The twist angle of the TN type liquid crystal cell is preferably from 40 to 100 °, more preferably from 50 to 90 °, and most preferably from 60 to 80 °.
The value of the product (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer is preferably 0.1 to 0.5 μm, and 0.2 to 0.4 μm. It is more preferred that there be. The twist angle of the STN type liquid crystal cell is 180
To 360 °, preferably 220 to 270 °
゜ is more preferable. The value of the product (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer is preferably 0.3 to 1.2 μm.
More preferably, it is 5 to 1.0 μm. HAN
In the type liquid crystal cell, the liquid crystal is substantially vertically aligned on one substrate, and the pretilt angle on the other substrate is 0 to 4.
It is preferably 5 °. The refractive index anisotropy of the liquid crystal layer (Δ
The value of the product (Δnd) of (n) and the thickness (d) of the liquid crystal layer is
The thickness is preferably from 0.1 to 1.0 μm, and more preferably from 0.3 to 0.8 μm. The substrate on which the liquid crystal is vertically aligned may be a substrate on the reflection plate side or a substrate on the transparent electrode side. The polarizing film includes an iodine-based polarizing film, a dye-based polarizing film using a dichroic dye, and a polyene-based polarizing film. The iodine-based polarizing film and the dye-based polarizing film are generally manufactured using a polyvinyl alcohol-based film. The polarization axis of the polarizing film corresponds to a direction perpendicular to the stretching direction of the film. The reflection type liquid crystal display device can be used in a normally white mode in which the display is bright when the applied voltage is low and a dark display when the applied voltage is high, or in a normally black mode in which the display is dark when the applied voltage is low and the display is bright when the applied voltage is high. . Normally white mode is preferred.

[Phase plate] The phase plate has a wavelength of 450 nm.
Is 30 to 115 nm (preferably 60 to 110 nm, more preferably 70 to 100 nm), and the wavelength 59
The retardation value (Re590) measured at 0 nm is 60 to 130 nm (preferably 90 to 130 nm)
And satisfies the relationship of Re590-Re450 ≧ 2 nm. More preferably, Re590-Re450 ≧ 5 nm, and Re590-Re450 ≧ 10.
Most preferably, it is nm. The retardation value (Re450) measured at a wavelength of 450 nm is 40 to 11
5 nm (more preferably 60 to 110 nm, more preferably 75 to 90 nm), and a retardation value (Re550) measured at a wavelength of 550 nm of 60 to 125 nm (more preferably 80 to 125 nm, further preferably 90 to 125 nm). Yes, wavelength 590
The retardation value (Re590) measured in nm is 7
0 to 130 nm (more preferably 90 to 130 n
m, more preferably 97 to 130 nm), and preferably satisfies the relationship of Re590-Re550 ≧ 2 nm. More preferably, Re590-Re550 ≧ 5 nm, and Re590-Re550 ≧ 5 nm.
Most preferably, it is 10 nm. Also, Re550
It is also preferable that -Re450 ≧ 10 nm. The retardation value (Re) is calculated according to the following equation. Retardation value (Re) = (nx−ny) × d where nx is the in-plane refractive index of the retardation plate in the slow axis direction (in-plane maximum refractive index); ny is the retardation The index of refraction in the direction perpendicular to the slow axis in the plane of the plate; and d is
This is the thickness (nm) of the phase difference plate.

Further, the retardation plate is preferably made of one polymer film satisfying the following equation. 1 ≦ (nx−nz) / (nx−ny) ≦ 2, where nx is the in-plane refractive index in the plane of the retardation plate; ny is the in-plane retardation of the retardation plate The refractive index in the direction perpendicular to the axis; and nz is the refractive index in the thickness direction of the retarder. The thickness of one polymer film constituting the phase difference plate is preferably 5 to 1000 μm, more preferably 10 to 500 μm, and more preferably 4 to 500 μm.
The thickness is more preferably 0 to 200 μm, and most preferably 70 to 120 μm. The retardation value described above is a value lower than the original λ / 4. Due to the residual phase difference of the liquid crystal cell, the optimum value of the optical characteristics of the λ / 4 plate may be lower than the original λ / 4 as described above. The retardation plate having the above optical properties can be manufactured by the following materials and methods.

[Polymer] The polymer of the polymer film is preferably a cellulose ester, and more preferably a lower fatty acid ester of cellulose. The lower fatty acid means a fatty acid having 6 or less carbon atoms. The number of carbon atoms is preferably 2 (cellulose acetate), 3 (cellulose propionate) or 4 (cellulose butyrate). Cellulose acetate is particularly preferred. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate may be used. The average degree of acetylation (acetylation degree) of cellulose acetate is preferably from 45.0 to 62.5%, more preferably from 55.0 to 61.0%.

[Retardation raising agent] In order to adjust the retardation value at each wavelength, a retardation raising agent can be added to the polymer film.
The retardation increasing agent is preferably used in the range of 0.05 to 20 parts by mass, more preferably in the range of 0.1 to 10 parts by mass, and more preferably 0.2 to 10 parts by mass, based on 100 parts by mass of the polymer. More preferably, it is used in the range of 0.5 to 5 parts by mass, and most preferably, it is used in the range of 0.5 to 2 parts by mass. Two or more retardation increasing agents may be used in combination. The retardation increasing agent preferably has a maximum absorption in a wavelength region of 250 to 400 nm. It is preferable that the retardation increasing agent has substantially no absorption in the visible region.

As the retardation increasing agent, it is preferable to use a compound having at least two aromatic rings. In the present specification, the “aromatic ring” includes an aromatic hetero ring in addition to an aromatic hydrocarbon ring. The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring). Aromatic heterocycles are generally unsaturated heterocycles. The aromatic hetero ring is preferably a 5-, 6-, or 7-membered ring, more preferably a 5- or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of the aromatic hetero ring include a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, a pyrazole ring, a furazane ring, a triazole ring, a pyran ring, and a pyridine ring. , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring. As the aromatic ring, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring, a pyrazine ring and a 1,3,5-triazine ring are preferable.

The number of aromatic rings contained in the retardation increasing agent is preferably 2 to 20, preferably 2 to 12
Is more preferably, 2 to 8 is more preferable, and 2 to 6 is most preferable. The bonding relationship between two aromatic rings can be classified into (a) a case where a condensed ring is formed, (b) a case where they are directly connected by a single bond, and (c) a case where they are bonded via a linking group. , A spiro bond cannot be formed). The connection relationship is (a)-
Any of (c) may be used.

Examples of the condensed ring (condensed ring of two or more aromatic rings) of (a) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, Naphthacene ring, pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline Ring, isoquinoline ring,
A quinolidine ring, a quinazoline ring, a cinnoline ring, a quinoxaline ring, a phthalazine ring, a pteridine ring, a carbazole ring, an acridine ring, a phenanthridine ring, a xanthene ring, a phenazine ring, a phenothiazine ring, a phenoxatiin ring, a phenoxazine ring and a thianthrene ring; included. Preferred are a naphthalene ring, an azulene ring, an indole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, a benzotriazole ring and a quinoline ring. The single bond in (b) is preferably a bond between carbon atoms of two aromatic rings. Two aromatic rings may be linked by two or more single bonds to form an aliphatic ring or a non-aromatic heterocyclic ring between the two aromatic rings.

The connecting group (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is an alkylene group, alkenylene group, alkynylene group, -CO-, -O
-, -NH-, -S- or a combination thereof is preferred. Examples of the linking group consisting of a combination are shown below. Note that the left and right relationships in the following examples of the linking group may be reversed. c1: -CO-O-c2: -CO-NH-c3: -alkylene-O-c4: -NH-CO-NH-c5: -NH-CO-O-c6: -O-CO-O-c7: -O-alkylene-O-c8: -CO-alkenylene-c9: -CO-alkenylene-NH-c10: -CO-alkenylene-O-c11: -alkylene-CO-O-alkylene-O-CO
-Alkylene-c12: -O-alkylene-CO-O-alkylene-O-
CO-alkylene-O-c13: -O-CO-alkylene-CO-O-c14: -NH-CO-alkenylene- c15: -O-CO-alkenylene-

The aromatic ring and the linking group may have a substituent. Examples of the substituent include a halogen atom (F, C
l, Br, I), hydroxyl, carboxyl, cyano, amino, nitro, sulfo, carbamoyl, sulfamoyl, ureido, alkyl, alkenyl, alkynyl, aliphatic acyl, aliphatic acyloxy, alkoxy, alkoxycarbonyl , Alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamide group, aliphatic substituted amino group, aliphatic substituted carbamoyl group, aliphatic substituted sulfamoyl group, aliphatic substituted ureido group and non-aromatic Group heterocyclic groups.

The alkyl group preferably has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable.
The alkyl group may further have a substituent (eg, hydroxy, carboxy, alkoxy group, alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl,
-Hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl and 2-diethylaminoethyl. The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable.
The alkenyl group may further have a substituent. Examples of the alkenyl group include vinyl, allyl and 1-hexenyl. The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl, 1-butynyl and 1-hexynyl.

The number of carbon atoms of the aliphatic acyl group is 1 to 1
It is preferably 0. Examples of the aliphatic acyl group include acetyl, propanoyl and butanoyl. The aliphatic acyloxy group preferably has 1 to 10 carbon atoms. Examples of the aliphatic acyloxy group include acetoxy. The alkoxy group preferably has 1 to 8 carbon atoms. The alkoxy group may further have a substituent (eg, an alkoxy group). Examples of alkoxy groups (including substituted alkoxy groups) include methoxy, ethoxy, butoxy and methoxyethoxy. The alkoxycarbonyl group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonyl group include methoxycarbonyl and ethoxycarbonyl. The alkoxycarbonylamino group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonylamino group include methoxycarbonylamino and ethoxycarbonylamino.

The number of carbon atoms of the alkylthio group is 1 to 1
It is preferably 2. Examples of the alkylthio group include methylthio, ethylthio and octylthio.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include methanesulfonyl and ethanesulfonyl. The aliphatic amide group preferably has 1 to 10 carbon atoms. Examples of the aliphatic amide group include acetamide. The aliphatic sulfonamide group preferably has 1 to 8 carbon atoms. Examples of the aliphatic sulfonamide group include methanesulfonamide, butanesulfonamide and n-octanesulfonamide. The aliphatic substituted amino group preferably has 1 to 10 carbon atoms. Examples of the aliphatic substituted amino group include dimethylamino, diethylamino and 2-carboxyethylamino. The aliphatic substituted carbamoyl group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted carbamoyl group include methylcarbamoyl and diethylcarbamoyl. The aliphatic substituted sulfamoyl group preferably has 1 to 8 carbon atoms. Examples of the aliphatic substituted sulfamoyl group include methylsulfamoyl and diethylsulfamoyl. The aliphatic substituted ureido group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted ureido group include methyl ureide. Examples of the non-aromatic heterocyclic group include piperidino and morpholino. The molecular weight of the retardation increasing agent is preferably from 300 to 800. WO00 /
No. 65384.

[Infrared absorber] An infrared absorber can be added to the polymer film in order to adjust the retardation value at each wavelength. The infrared absorber is preferably used in the range of 0.01 to 5 parts by mass, more preferably in the range of 0.02 to 2 parts by mass, and more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the polymer. It is more preferably used in the range of 1 part by mass, and most preferably used in the range of 0.1 to 0.5 part by mass.
Two or more infrared absorbers may be used in combination. The infrared absorber preferably has a maximum absorption in a wavelength range of 750 to 1100 nm, and more preferably has a maximum absorption in a wavelength range of 800 to 1000 nm. It is preferred that the infrared absorber has substantially no absorption in the visible region.

It is preferable to use an infrared absorbing dye or an infrared absorbing pigment as the infrared absorbing agent, and it is particularly preferable to use an infrared absorbing dye. The infrared absorbing dye includes an organic compound and an inorganic compound. It is preferable to use an infrared absorbing dye which is an organic compound. Organic infrared absorbing dyes include cyanine compounds, metal chelate compounds, aminium compounds, diimonium compounds, quinone compounds, squarylium compounds and methine compounds. For the infrared absorbing dye, coloring material, 61 [4] 2
15-226 (1988), and Chemical Industry, 43-5.
3 (1986, May).

When examining the types of dyes from the viewpoint of infrared absorption function or absorption spectrum, infrared absorption dyes developed in the technical field of silver halide photographic materials are excellent. Infrared absorbing dyes developed in the technical field of silver halide photographic light-sensitive materials include dihydroperimidine squarylium dyes (described in US Pat. No. 5,380,635 and Japanese Patent Application No. 8-189817) and cyanine dyes (JP-A No. No. 62-123454, No. 3-138640, No. 3
-21542, 3-226736, 5-31
Nos. 3305 and 6-43583, Japanese Patent Application No. 7-435.
269097 and EP 0430244), pyrylium dyes (JP-A-3-13864).
Nos. 0 and 3-21542) and diimmonium dyes (JP-A-3-138640 and JP-A-3-2115).
No. 42), pyrazolopyridone dyes (described in JP-A-2-282244), indoaniline dyes (described in JP-A-5-323500 and JP-A-5-323501), polymethine dyes (described in JP-A-3-26765). Nos. 4,190,343 and EP 37796.
No. 1), oxonol dyes (JP-A-3-93)
No. 46), anthraquinone dyes (Japanese Unexamined Patent Publication No.
13654), a naphthalocyanine dye (described in US Pat. No. 5,099,899) and a naphtholactam dye (described in European Patent 568,267).

[Production of polymer film] It is preferable to produce a polymer film by a solvent casting method. In the solvent casting method, a film is manufactured using a solution (dope) in which a polymer is dissolved in an organic solvent. The organic solvent is an ether having 3 to 12 carbon atoms,
It is preferable to include a solvent selected from ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. Ethers, ketones and esters may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, -O-, -CO- and -COO-) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any one of the functional groups.

Examples of the ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolan, tetrahydrofuran, anisole and phenetole. Examples of the ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone. Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of the organic solvent having two or more types of functional groups include
Includes 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol. The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen atoms in halogenated hydrocarbons is preferably 25 to 75 mol%, and preferably 3 to 75 mol%.
The content is more preferably 0 to 70 mol%, still more preferably 35 to 65 mol%, and 40 to 60 mol%.
Most preferably, it is mol%. Methylene chloride is a typical halogenated hydrocarbon. Two or more organic solvents may be used as a mixture.

The polymer solution can be prepared by a general method. The general method means that the treatment is performed at a temperature of 0 ° C. or higher (normal temperature or high temperature). The solution can be prepared using a dope preparation method and apparatus in a usual solvent casting method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly, methylene chloride) as the organic solvent. The amount of the polymer is adjusted so that the obtained solution contains 10 to 40% by mass. More preferably, the amount of polymer is from 10 to 30% by weight. In the organic solvent (main solvent), any additives described below may be added.
The solution can be prepared by stirring the polymer and the organic solvent at room temperature (0 to 40 ° C.). The highly concentrated solution may be stirred under pressure and heating conditions. Specifically, the polymer and the organic solvent are placed in a pressurized container and hermetically sealed, and the mixture is stirred while being heated under pressure to a temperature not lower than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 2
It is 00 ° C, more preferably 80 to 110 ° C.

The components may be roughly mixed in advance and then placed in a container. Moreover, you may put in a container sequentially. The container must be configured to be able to stir. The container can be pressurized by injecting an inert gas such as nitrogen gas. Further, an increase in the vapor pressure of the solvent due to heating may be used.
Alternatively, each component may be added under pressure after the container is sealed. When heating, it is preferable to heat from outside the container. For example, a jacket-type heating device can be used. Alternatively, a plate heater may be provided outside the container, and the entire container may be heated by circulating the liquid through piping. It is preferable to provide a stirring blade inside the container and stir using the stirring blade. The stirring blade preferably has a length reaching the vicinity of the container wall. At the end of the stirring blade, a scraping blade is preferably provided to renew the liquid film on the container wall. Instruments such as a pressure gauge and a thermometer may be installed in the container. Dissolve each component in the solvent in the container.
The prepared dope is taken out of the vessel after cooling, or is taken out and then cooled using a heat exchanger or the like.

The solution can be prepared by a cooling dissolution method. In the cooling dissolution method, the polymer can be dissolved even in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can dissolve a polymer by a usual dissolution method, the cooling dissolution method has an effect that a uniform solution can be obtained quickly. In the cooling dissolution method, first, a polymer is gradually added to an organic solvent with stirring at room temperature. The amount of polymer is between 10 and 4 in this mixture.
It is preferable to adjust so as to contain 0% by mass. More preferably, the amount of polymer is from 10 to 30% by weight. Further, an optional additive described below may be added to the mixture.

Next, the mixture is cooled to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -10 ° C).
To -20 ° C, most preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). Upon such cooling, the mixture of polymer and organic solvent solidifies. The cooling rate is preferably 4 ° C./min or more, and 8 ° C./min.
Minutes or more, and most preferably 12 ° C./minute or more. The higher the cooling rate, the better, but the theoretical upper limit is 10,000 ° C./sec.
0 ° C./sec is a technical upper limit, and 100 ° C./sec is a practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at which the cooling is started and the final cooling temperature by the time from when the cooling is started to when the temperature reaches the final cooling temperature.

Further, the temperature is raised to 0 to 200 ° C (preferably 0 to 150 ° C, more preferably 0 to 120 ° C,
Upon heating to (most preferably 0 to 50 ° C.), the polymer dissolves in the organic solvent. The temperature may be raised only by leaving it at room temperature or may be heated in a warm bath. Heating rate is 4
C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The heating rate is preferably as fast as possible.
00 ° C / sec is the theoretical upper limit, 1000 ° C / sec is the technical upper limit, and 100 ° C / sec is the practical upper limit. Note that the heating rate is a value obtained by dividing the difference between the temperature at which heating is started and the final heating temperature by the time from when the heating is started until the final heating temperature is reached. . As described above, a uniform solution is obtained. If the dissolution is insufficient, the operation of cooling and heating may be repeated.
Whether or not the dissolution is sufficient can be determined only by visually observing the appearance of the solution.

In the cooling dissolution method, it is desirable to use a closed container in order to avoid water contamination due to dew condensation during cooling. Also, in the cooling and heating operation, pressurization during cooling,
By reducing the pressure during the heating, the dissolution time can be shortened. In order to perform pressurization and decompression, it is desirable to use a pressure-resistant container. According to differential scanning calorimetry (DSC), a 20% by mass solution of cellulose acetate (degree of acetylation: 60.9%, viscosity average polymerization degree: 299) dissolved in methyl acetate by a cooling dissolution method was 3%.
A pseudo phase transition point between the sol state and the gel state exists near 3 ° C., and below this temperature, the gel state becomes uniform. Therefore,
This solution must be stored at a temperature equal to or higher than the quasi phase transition temperature, preferably at a temperature of about 10 ° C. plus the gel phase transition temperature. However, the pseudo phase transition temperature varies depending on the average acetylation degree of cellulose acetate, the average degree of viscosity polymerization, the solution concentration, and the organic solvent used.

From the prepared polymer solution (dope), a polymer film is produced by a solvent casting method. The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35%. It is preferable that the surface of the drum or the band is finished in a mirror state. The casting and drying methods in the solvent casting method are described in US Pat.
No. 36310, No. 2367603, No. 2492078
Nos. 2492977, 2492978, 26
No. 07704, No. 2739069, No. 2739070
Nos., British Patent Nos. 640731 and 736892, Japanese Patent Publication Nos. 45-4554 and 49-5614,
JP-A-60-176834 and JP-A-60-203430
And JP-A-62-115035. The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. It is preferable to dry the film by blowing it for 2 seconds or more. The obtained film is peeled off from the drum or band, and further heated at 100 to 160 ° C.
It is also possible to evaporate the residual solvent by drying with a high-temperature air having a temperature which is sequentially changed up to the above. The above method is described in Tokuhei 5-178.
No. 44 discloses this. According to this method, the time from casting to stripping can be reduced. In order to carry out this method, it is necessary that the dope gels at the surface temperature of the drum or band during casting. The solution (dope) prepared as described above satisfies this condition.

A plasticizer can be added to the polymer film in order to improve mechanical properties or to increase a drying speed. As the plasticizer, a phosphoric acid ester or a carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP)
And tricresyl phosphate (TCP). Representative carboxylic esters include phthalic esters and citric esters. Examples of phthalate esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DB
P), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include:
Includes O-acetyl triethyl citrate (OACTE) and O-acetyl tributyl citrate (OACTB). Examples of other carboxylic esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic esters. Phthalate ester plasticizers (DMP, DEP, DBP, D
OP, DPP, DEHP) are preferably used. DE
P and DPP are particularly preferred. The amount of the plasticizer added is preferably 0.1 to 25% by mass, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass of the amount of the cellulose ester.

[0038] The polymer film has a deterioration inhibitor (eg,
Antioxidants, peroxide decomposers, radical inhibitors, metal deactivators, acid scavengers, amines). Regarding the deterioration inhibitor, JP-A-3-199201, 5-
1907073, 5-194789, 5-27
Nos. 1471 and 6-107854. The amount of the deterioration inhibitor added is preferably 0.01 to 1% by mass of the solution (dope) to be prepared.
More preferably, it is from 0.2 to 0.2% by mass. When the amount is less than 0.01% by mass, the effect of the deterioration inhibitor is hardly recognized. If the amount exceeds 1% by mass, bleed out (bleeding out) of the deterioration inhibitor onto the film surface may be observed. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT)
Can be mentioned.

The polymer film is further subjected to a stretching treatment to obtain a refractive index (refractive index nx in the in-plane slow axis direction, refractive index ny in the direction perpendicular to the in-plane slow axis, and refractive index n in the thickness direction).
It is preferable to adjust z). When the intrinsic birefringence is positive, the refractive index increases in the direction in which the polymer chains are oriented.
When stretching such a polymer having a positive intrinsic birefringence,
Usually, the refractive index satisfies nx> ny ≧ nz. This is because the x-component of the polymer chain oriented in the in-plane direction is increased by stretching, and the z-component is minimized. Thereby, the relationship of 1 ≦ (nx−nz) / (nx−ny) can be satisfied. Further, (nx−nz) / (n
In order to satisfy the relationship of (x-ny) ≦ 2, the stretching ratio of uniaxial stretching may be controlled, or the refractive index may be adjusted by performing unbalanced biaxial stretching. Specifically, uniaxial stretching or unbalanced biaxial stretching is performed so that the maximum stretching ratio SA and the stretching ratio SB in the direction perpendicular to the stretching direction satisfy the relationship of 1 <SA / SB ≦ 3. What is necessary is just to implement. The stretching ratio is a relative value when the length before stretching is set to 1. SB may be a value less than 1 (in other words, contract). If the relationship of the above expression is satisfied, SB may be a value less than 1. Further, the stretching ratio is adjusted so that the front retardation satisfies the definition described above. The stretching process is a simultaneous process,
It may be a sequential process.

[0040]

EXAMPLES Example 1 (Preparation of Retardation Plate) The following composition was put into a mixing tank, and stirred with heating to dissolve each component to prepare a cellulose acetate solution (dope).

組成 Composition of cellulose acetate solution ───────セ ル ロ ー ス 100% by mass of cellulose acetate having a degree of acetylation of 59.7% triphenyl phosphate (plasticizer) 7 2.8 parts by mass Biphenyldiphenyl phosphate (plasticizer) 3.9 parts by mass The following retardation enhancer 1.0 part by mass Tribenzylamine 2.0 parts by mass methylene chloride (first solvent) 336 parts by mass methanol (second solvent) ) 30 parts by mass ────────────────────────────────────

[0042]

Embedded image

The obtained dope was cast using a band casting machine. After casting, when the amount of the residual solvent became about 25% by mass, the film was peeled off from the band. While transporting the film, the film was dried using hot air having an outlet temperature of 145 ° C. until the residual solvent amount became 2.0% by weight or less. The thickness of the obtained film was 87 μm. Next, the film was stretched using a roll stretching machine. The roll stretching machine was composed of a main zone including a preheating zone, a stretching zone, and a cooling zone, and temperature adjustment was performed by combining each roll (induction heating jacket roll), a casing provided in a stretching section, warm air, and infrared rays. Stretching is performed at a film surface temperature of 130.
C., and stretched in a direction parallel to the casting direction. The direction perpendicular to the stretching direction was freely shrunk. After stretching, the film was cooled and wound up. The stretch ratio of the obtained film was 1.46 times and the thickness was 81 μm. In this manner, a retardation plate made of a cellulose acetate film was produced.

Using the multi-wavelength Abbe refractometer (DR-M2, manufactured by Atago Co., Ltd.), the retardation (Re) value of the produced retardation plate was measured at wavelengths of 450 nm, 550 nm and 590 nm. In addition, the wavelength 550
The refractive index nx in the direction of the in-plane slow axis, the refractive index ny in the direction perpendicular to the slow axis in the plane, and the refractive index nz in the thickness direction at nm are obtained, and (nx-nz) / (nx-ny) is obtained. The value was calculated. Table 1 shows the above results.

(Preparation of Polarizing Plate) A transparent protective film, a polarizing film and the prepared retardation plate were laminated in this order to obtain a polarizing plate. The angle between the slow axis of the retardation plate and the polarizing axis of the polarizing film is 4
Adjusted to 5 ゜.

(Preparation of Reflective Liquid Crystal Display Device) A polarizing plate and a retardation plate were peeled off from a panel of a commercially available reflective liquid crystal display device (La Vie, manufactured by NEC Corporation), and a polarizing plate was prepared instead. Were laminated on a liquid crystal cell in the order of a retardation film, a polarizing film, and a transparent protective film. When a voltage was applied to the liquid crystal display device and the image was visually evaluated, it was confirmed that neutral gray was displayed without coloration in both white display and black display. Next, when the contrast ratio of the reflection luminance was measured using a measuring device (EZcontrast160D, manufactured by Eldim), the contrast ratio from the front was 26, and the viewing angle at which the contrast ratio was 3 was 120 ° or more in the vertical direction and the horizontal direction. It was 120 ° or more.

Example 2 (Preparation of Retardation Plate) The dope obtained in Example 1 was cast to prepare a film having a thickness of 108 μm. The obtained film was stretched by the roll stretching machine used in Example 1.
The stretching was performed at a film surface temperature of 130 ° C., and the film was stretched in a direction parallel to the casting direction. The stretching ratio of the obtained film is 1.3.
5 times, and the thickness was 101 μm. In this manner, a retardation plate made of a cellulose acetate film was produced. Optical measurement was performed on the produced retardation plate in the same manner as in Example 1. The results are shown in Table 1.

(Preparation of Polarizing Plate) A transparent protective film, a polarizing film and the prepared retardation plate were laminated in this order to obtain a polarizing plate. The angle between the slow axis of the retardation plate and the polarizing axis of the polarizing film is 4
Adjusted to 5 ゜.

(Preparation of Reflective Liquid Crystal Display Device) A polarizing plate and a retardation plate were peeled off from a panel of a commercially available reflective liquid crystal display device (La Vie, manufactured by NEC Corporation), and a polarizing plate was prepared instead. Were laminated on a liquid crystal cell in the order of a retardation film, a polarizing film, and a transparent protective film. When a voltage was applied to the liquid crystal display device and the image was visually evaluated, it was confirmed that neutral gray was displayed without coloration in both white display and black display.

Example 3 (Preparation of Retardation Plate) Thickness 1 obtained by casting in Example 2
The 08 μm film was stretched by the roll stretching machine used in Example 1. The stretching was performed at a film surface temperature of 130 ° C., and the film was stretched in a direction parallel to the casting direction. The stretch ratio of the obtained film was 1.38 times and the thickness was 99 μm. In this manner, a retardation plate made of a cellulose acetate film was produced. Optical measurement was performed on the produced retardation plate in the same manner as in Example 1. The results are shown in Table 1.

(Preparation of Polarizing Plate) A transparent protective film, a polarizing film and the prepared retardation plate were laminated in this order to obtain a polarizing plate. The angle between the slow axis of the retardation plate and the polarizing axis of the polarizing film is 4
Adjusted to 5 ゜.

(Preparation of Reflective Liquid Crystal Display Device) A polarizing plate and a retardation plate were peeled off from a panel of a commercially available reflective liquid crystal display device (La Vie, manufactured by NEC Corporation), and a polarizing plate was prepared instead. Were laminated on a liquid crystal cell in the order of a retardation film, a polarizing film, and a transparent protective film. When a voltage was applied to the liquid crystal display device and the image was visually evaluated, it was confirmed that neutral gray was displayed without coloration in both white display and black display.

Example 4 (Preparation of Retardation Plate) The following composition was put into a mixing tank, and the components were dissolved by stirring with heating to prepare a cellulose acetate solution (dope).

<< Composition of Cellulose Acetate Solution >>セ ル ロ ー ス 100% by mass of cellulose acetate having a degree of acetylation of 59.7% triphenyl phosphate (plasticizer) 7 2.8 parts by mass Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by mass Retardation increasing agent used in Example 1 0.5 parts by mass Tribenzylamine 2.0 parts by mass Methylene chloride (first solvent) 336 parts by mass methanol (Second solvent) 30 parts by mass ────────────────────────────────────

The obtained dope was cast to a thickness of 109 μm.
m was prepared. The obtained film was stretched by the roll stretching machine used in Example 1. The stretching was performed at a film surface temperature of 130 ° C., and the film was stretched in a direction parallel to the casting direction.
The stretching ratio of the obtained film was 1.42 times and the thickness was 102 μm. In this manner, a retardation plate made of a cellulose acetate film was produced. Optical measurement was performed on the produced retardation plate in the same manner as in Example 1. The results are shown in Table 1.

(Preparation of Polarizing Plate) A transparent protective film, a polarizing film and the prepared retardation plate were laminated in this order to obtain a polarizing plate. The angle between the slow axis of the retardation plate and the polarizing axis of the polarizing film is 4
Adjusted to 5 ゜.

(Preparation of Reflective Liquid Crystal Display) A polarizing plate and a retardation plate were peeled off from a panel of a commercially available reflective liquid crystal display (La Vie, manufactured by NEC Corporation), and a polarizing plate was prepared instead. Were laminated on a liquid crystal cell in the order of a retardation film, a polarizing film, and a transparent protective film. When a voltage was applied to the liquid crystal display device and the image was visually evaluated, it was confirmed that neutral gray was displayed without coloration in both white display and black display.

Example 5 (Preparation of Retardation Plate) The dope obtained in Example 4 was cast to prepare a film having a thickness of 120 μm. The obtained film was stretched by the roll stretching machine used in Example 1.
The stretching was performed at a film surface temperature of 130 ° C., and the film was stretched in a direction parallel to the casting direction. The stretching ratio of the obtained film is 1.3.
It was eight times and the thickness was 110 μm. In this manner, a retardation plate made of a cellulose acetate film was produced. Optical measurement was performed on the produced retardation plate in the same manner as in Example 1. The results are shown in Table 1.

(Preparation of Polarizing Plate) A transparent protective film, a polarizing film and the prepared retardation plate were laminated in this order to obtain a polarizing plate. The angle between the slow axis of the retardation plate and the polarizing axis of the polarizing film is 4
Adjusted to 5 ゜.

(Preparation of Reflective Liquid Crystal Display Device) A polarizing plate and a retardation plate were peeled off from a panel of a commercially available reflective liquid crystal display device (La Vie, manufactured by NEC Corporation), and a polarizing plate prepared instead. Were laminated on a liquid crystal cell in the order of a retardation film, a polarizing film, and a transparent protective film. When a voltage was applied to the liquid crystal display device and the image was visually evaluated, it was confirmed that neutral gray was displayed without coloration in both white display and black display.

Example 6 (Preparation of Retardation Plate) The following composition was charged into a mixing tank, and the components were dissolved by stirring with heating to prepare a cellulose acetate solution (dope).

<< Composition of Cellulose Acetate Solution >>セ ル ロ ー ス 100% by mass of cellulose acetate having a degree of acetylation of 59.7% triphenyl phosphate (plasticizer) 7 2.8 parts by mass Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by mass Retardation increasing agent used in Example 1 1.3 parts by mass Tribenzylamine 2.0 parts by mass Methylene chloride (first solvent) 336 parts by mass methanol (Second solvent) 30 parts by mass ────────────────────────────────────

The obtained dope was cast to a thickness of 107 μm.
m was prepared. The obtained film was stretched by the roll stretching machine used in Example 1. The stretching was performed at a film surface temperature of 130 ° C., and the film was stretched in a direction parallel to the casting direction.
The stretch ratio of the obtained film was 1.35 times and the thickness was 101 μm. In this manner, a retardation plate made of a cellulose acetate film was produced. Optical measurement was performed on the produced retardation plate in the same manner as in Example 1. The results are shown in Table 1.

(Preparation of Polarizing Plate) A transparent protective film, a polarizing film and the prepared retardation plate were laminated in this order to obtain a polarizing plate. The angle between the slow axis of the retardation plate and the polarizing axis of the polarizing film is 4
Adjusted to 5 ゜.

(Preparation of Reflective Liquid Crystal Display Device) A polarizing plate and a retardation plate were peeled off from a panel of a commercially available reflective liquid crystal display device (La Vie, manufactured by NEC Corporation), and the polarizing plate was prepared instead. Were laminated on a liquid crystal cell in the order of a retardation film, a polarizing film, and a transparent protective film. When a voltage was applied to the liquid crystal display device and the image was visually evaluated, it was confirmed that neutral gray was displayed without coloration in both white display and black display.

[0066]

[Table 1] Table 1 ──────────────────────────────────── Retardation plate Re (450) Re (550) Re (590) (nx-nz) / (nx-ny) ─────────────────────────────── １ Example 1 90 nm 99 nm 102 nm 1.5 Example 2 92 nm 101 nm 104 nm 1.7 Example 3 109 nm 120 nm 124 nm 1.5 Example 4 89 nm 102 nm 107 nm 1.6 Example 5 90 nm 103 nm 108 nm 1.7 Example 6 95 nm 101 nm 103 nm 1.7 ────────────────────────────────────

Continued on the front page F term (reference) 2H049 BA02 BA06 BA25 BB03 BB16 BB49 BC03 BC22 2H091 FA02Y FA08X FA08Z FA11Z FA16Z FA34Z FB02 FB12 FC07 FD06 FD10 HA07 HA10 KA02 KA03 LA19 LA20 4F071 AA12 BC12 AE22

Claims (8)

[Claims] 1. The retardation value Re450 measured at a wavelength of 450 nm is 30 to 115 nm, and the retardation value Re450 measured at a wavelength of 590 nm is Re.
590 is 60 to 130 nm, and Re59
A retardation plate comprising a single polymer film satisfying a relationship of 0-Re450 ≧ 2 nm. (2) Re450, which is a retardation value measured at a wavelength of 450 nm, is 40 to 115 nm;
R which is a retardation value measured at a wavelength of 550 nm
e550 is 60 to 125 nm, and the wavelength is 590 nm.
Re590, which is the retardation value measured in
１３０130 nm, and Re590-Re55
The retardation plate according to claim 1, wherein a relationship of 0 ≧ 2 nm is satisfied. 3. An in-plane refractive index nx in the slow axis direction.
The refractive index ny in the direction perpendicular to the in-plane slow axis and the refractive index nz in the thickness direction are 1 ≦ (nx−nz) /
The retardation plate according to claim 1, wherein a relationship of (nx-ny) ≤2 is satisfied. 4. The retardation plate according to claim 1, wherein the polymer film is a cellulose ester film. 5. The retardation film according to claim 4, wherein the polymer film is a stretched cellulose ester film. 6. The maximum stretch ratio SA and the stretch ratio SB in a direction perpendicular to the stretching direction are 1 <SA.
6. The retardation plate according to claim 5, wherein a relationship of / SB ≦ 3 is satisfied. 7. A reflection type liquid crystal display device comprising a reflection plate, a liquid crystal cell, a retardation plate, and a polarizing film, wherein the retardation plate comprises:
Re which is a retardation value measured at a wavelength of 450 nm
450 is 30 to 115 nm, Re590 which is a retardation value measured at a wavelength of 590 nm is 60 to 130 nm, and Re590-Re450
A reflective liquid crystal display device comprising a single polymer film satisfying a relationship of ≧ 2 nm. 8. The reflection type liquid crystal display device according to claim 7, wherein the reflection plate, the liquid crystal cell and the polarizing film are laminated in this order, and the retardation plate is arranged between the reflection plate and the polarizing film.