JP2003315544A - Polarizing film and liquid crystal display using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display which imparts color reproducibility favorably comparable to that of a cathod-ray tube while maintaining high lumi nous efficiency. <P>SOLUTION: The high color reproducibility of a polarizing film is realized by forming regions in which an organic pigment absorbing only light of a specified wavelength in the visible ray region is dispersed on the polarizing film by using the organic pigment with extremely narrow light absorption half bandwidth as the polarizing film so as to suppress a color purity deteriorating phenomenon, in other words, by imparting a function as a second color filter thereto. The position of the light absorption band peak brought about by the regions in which the organic pigment is dispersed is made to be as near as possible to a point where spectral transmittance curves of respective colors of color filters intersect with each other. Thereby the polarizing film is designed so as to efficiently suppress color purity deterioration caused by mixing in of an illumination light spectrum on a shoulder part of the color filter. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel polarizing film for improving the image characteristics of a liquid crystal display device, and a transmissive or semi-transmissive liquid crystal display device using the polarizing film, and more specifically to high illumination. The present invention relates to a technique for improving image color reproducibility of a liquid crystal display device while maintaining efficiency.

[0002]

2. Description of the Related Art Recently, a transmissive liquid crystal display (display) device has been widely used as a display device for a monitor for a personal computer or a flat-screen TV. In particular, recently, a color filter obtained by a method such as a pigment dispersion method is used. The full-color liquid crystal displays that it possesses are becoming mainstream, and are rapidly becoming popular as display devices that replace conventional cathode ray tubes.

These liquid crystal display devices have extremely high luminous efficiency and low power consumption as compared with the conventionally used cathode ray tubes and plasma displays, and are therefore popular all over the world as standard home televisions. This is considered extremely preferable from the viewpoint of maintaining the global environment.

However, it has been pointed out that when a liquid crystal display device is used for displaying television images or the like in which a cathode ray tube has been mainly used, the vividness of an image is insufficient as compared with that of a cathode ray tube. The vividness of the color, which is the most important characteristic of the color display device, is decisively inferior to that of a cathode ray tube, which is a factor that hinders its widespread use.

One of the reasons for this is that the light emission principle of the transmissive (or semi-transmissive) liquid crystal display device is that the display pixel itself does not emit light, but the illumination light incident from the back surface of the panel is used. Are listed. That is, since the color filter cuts the specific spectrum of the illumination light to obtain a color display, the characteristics of the light source, the filter, the polarizing plate, the alignment film, and the like affect the color purity. (Red, blue, green) It is difficult to obtain essentially high color purity as compared with a cathode ray tube or a plasma display that emits light by exciting phosphors of each color with an electron beam or plasma.

Further, since color purity is essentially determined by a color filter, a method of realizing high color reproducibility by using a color filter having a sharp spectral transmission characteristic can be considered, but it is used for aligning liquid crystal. Since a high temperature process is used during the process of forming the alignment film, the color materials that can be used are limited to pigments with poor color reproducibility, so a color filter with sharp spectral transmission characteristics is actually used. There is also the problem that this is extremely difficult.

In addition, since the color filter section is generally provided inside the liquid crystal cell, it is necessary to consider the polarization shift in the filter section, and due to such circumstances peculiar to the liquid crystal cell, it has a sharp spectral characteristic. The method of improving color reproducibility by using a color filter is naturally limited.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems of the prior art, and since it has low power consumption, it has essentially excellent characteristics for television use. However, the present invention relates to a liquid crystal display device, which has been hindered from spreading due to poor color reproducibility, and a technique for imparting color reproducibility comparable to that of a cathode-ray tube while maintaining high luminous efficiency. The present invention relates to a polarizing film used for imparting properties.

[0009]

A polarizing film used in a transmissive or semi-transmissive liquid crystal display according to the present invention has a light absorption function of a specific wavelength in a visible light region consisting of a region in which an organic dye is dispersed, In addition, the light absorption half-value width of the organic dye corresponding to each specific wavelength is 60 nm or less.

The number of light absorption peaks in the visible light region, which is a region in which the organic dye is dispersed, is 1 or more and less than 3.

A resin coating layer may be provided on the surface of the polarizing film, and the organic dye may be dispersed in the resin coating layer.

The region in which the organic dye is dispersed may be obtained by dispersing the organic dye in the adhesive provided on the polarizing film.

The polarizing film has a diffusion angle of 1 ° to 120 °.
It is preferable to have a light diffusing function.

An ultraviolet absorber and / or a light stabilizer can be blended in the region where the organic dye is dispersed.

An ultraviolet absorbing layer may be provided on the polarizing film.

The liquid crystal display device according to the present invention is
A light source comprising a cold cathode tube and / or a hot cathode tube; a back light source means having a light uniformizing means for converting the light source light into a substantially uniform surface light source; a polarizing film; and a color filter, As a polarizing film, having a light absorption function of a specific wavelength in the visible light region consisting of a region in which an organic dye is dispersed, and a light absorption peak in the visible light region, from the overlap point in the spectral transmittance characteristics of each color of the color filter. The one located in the range of ± 30 nm is used.

A pigment dispersion type color filter can be used in the liquid crystal display device according to the present invention.

The organic dye used in the polarizing film according to the present invention may be a squaryl-based dye and / or a tetraazaporphyrin-based dye.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a liquid crystal display device according to the present invention will be described below. FIG. 1 is a schematic view showing a sectional structure of a transmissive liquid crystal display device according to an embodiment of the present invention.

The transmissive liquid crystal display device shown in FIG. 1 is installed on the back light source means, that is, the back light 10 having the light uniformizing means for converting the light from the light source into a substantially uniform surface light source, and on the upper surface of the back light 10. And a liquid crystal panel 11.

The liquid crystal panel 11 is installed on the upper surface of the backlight 10, and the polarizing film 11a, the glass substrate 11b, the TFT gate array 11c, the liquid crystal layer 11d, and the color filter 1 are arranged upward from the backlight 10 side.
1e, a glass substrate 11f, and a polarizing film 11g are sequentially provided.

The polarizing film 11a of the present invention has a structure shown in FIG.
As shown in, a region in which an organic dye having an extremely sharp absorption peak that cuts only a specific wavelength region with an extremely narrow width is dispersed is provided, and the number of the absorption peak is preferably in the visible light region. 1 or more and less than 5, particularly preferably 1 or more and less than 3, very preferably 2,
Moreover, the absorption peak is located at an appropriate position. This effect makes it possible to control the color reproduction range of the liquid crystal display device extremely flexibly without providing a new component, which will be described in detail later.

Here, the polarizing film in the present invention is used in a liquid crystal cell to function as a liquid crystal shutter,
It means a film having a function of extracting only a specific polarized component. That is, a mode in which a substance typified by iodine or a dichroic dye is orientated and arranged to absorb only a specific polarized light to extract the polarized light, a cholesteric liquid crystal alignment layer, and a large number of dielectrics. An example is a reflection-type polarizer that extracts only a specific polarization component by using a laminated body made of a body. Above all, a polarizing film obtained by adsorbing iodine or a dichroic absorption dye onto a polyvinyl alcohol-based resin film and uniaxially stretching is used in an extremely large number, and these polarizing films can be preferably used also in the present invention.

The liquid crystal display device according to the present invention utilizes the electro-optical effect of liquid crystal molecules, that is, optical anisotropy (refractive index anisotropy), orientation, etc., and applies or applies an electric field to any display unit. To change the alignment state of the liquid crystal,
A display is performed by using a liquid crystal cell that is an array of optical shutters and is driven by changing the light transmittance or reflectance.

More specifically, a transmission type simple matrix driving super twisted nematic mode, a transmission type active matrix driving twisted nematic mode,
Transmissive active matrix drive in-plane switching mode, transmissive active matrix drive vertical aligned mode, transflective simple matrix drive super twisted nematic mode, transflective active matrix drive twisted nematic mode, reflective simple matrix drive super twisted nematic Examples include liquid crystal display elements of modes, reflective active matrix drive twisted nematic mode, and the like.

In particular, the liquid crystal display device targeted by the present invention is a liquid crystal display device having a color filter 11e, and as shown in FIG. 1, the color filter is generally arranged inside the liquid crystal cell. Also,
As the color filter method, it is preferable to use a pigment dispersion method, which is excellent in durability against heating and light fastness, from the viewpoint of productivity and quality.

Typical pigments used in the pigment dispersion type color filter are, for example, dianthraquinone type for red color, halogenated copper phthalocyanine type for green color, and copper phthalocyanine type for blue color. By using acrylic or epoxy acrylate as a base resin to disperse and photopolymerize to form a pigment dispersion layer. By repeating photolithography for each color, R
A typical mode is to obtain a color filter in which GB colors are arranged.

The pigment-dispersed color filter thus formed has excellent light resistance and heat resistance, and does not deteriorate even during the firing process of the polyimide-based liquid crystal alignment film.
Although it has practically preferable characteristics, on the other hand, sharp spectral transmittance characteristics, which are important for improving color purity, are difficult to make into ultrafine particles and finely dispersed pigments by the pigment dispersion method. There is a problem in that it is difficult to realize the above and it is difficult to perform display with excellent color reproducibility.
That is, as shown in FIG. 2, the spectral transmittance characteristic of a general color filter does not have a perfectly sharp peak, but has a gentle shoulder portion, so that the brightness (brightness) is When a color filter is designed to be kept at a high value, the emission spectrum is essentially mixed in the shoulder portion, and in a general cold cathode tube as a light source, the sub-spectrum component that deteriorates the color reproducibility from the phosphor is small. However, since it is emitted, this adversely affects the color purity.

Therefore, in the present invention, in order to suppress the phenomenon that the color purity deteriorates due to the above problems, an organic dye having an extremely narrow half-width of light absorption is used for the polarizing film, and only a specific wavelength in the visible light region is used. A region in which an organic dye that absorbs is dispersed is formed and, so to speak, a function as a second color filter is imparted to achieve high color reproducibility. Moreover, the position of the light absorption peak due to the region in which the organic dye is dispersed is located as close as possible to the point where the spectral transmittance curves of the respective colors of the color filters overlap (overlap point), and the illumination light spectrum of the shoulder portion of the color filter The design is such that deterioration in color purity due to mixing can be efficiently suppressed.

That is, in the case of organic dyes, the absorption wavelength can be controlled extremely finely by designing an appropriate molecule, and the absorption peak is designed so that there is no absorption peak other than the target wavelength. Therefore, it becomes possible to selectively remove only the illumination light component in the vicinity of the shoulder portion, which is important in the present invention, and as a result, the color purity can be reduced so much without sacrificing the brightness. It is possible to improve only.

That is, as a specific mode of the narrow peak, as shown in FIG. 3, the light absorption rate at each light absorption peak in the region where the organic dye is dispersed is used as a reference.
When the width of the absorption spectrum when the light absorptance becomes half the light absorption half-value width, the light absorption half-value width is at least 60 nm or less, more preferably 55 nm or less, and further preferably 50 nm or less. The area where the organic dye is dispersed is designed.

Further, as shown in FIG. 2, the position of the absorption peak is based on the point (overlap point) where the transmittances of the respective colors are equal, which are determined from the spectral transmittance characteristic diagram of the respective colors of the color filter. The molecular design of the organic dye is made so that the absorption peak position due to the region in which the organic dye is dispersed is as close as possible to this overlap point. Specifically, the absorption peak position of the polarizing film is preferably located at ± 30 nm, more preferably ± 25 nm, further preferably ± 20 nm from the overlap point.

Further, in the present invention, since an organic dye having an excellent ability to selectively cut only a specific wavelength is used, an extra absorption band may be generated as compared with a filter obtained by dispersion of metal ions. There is a feature that it does not exist, and it is preferable to make use of this feature so that the number of absorption peaks in the visible light region is as small as possible. That is, when a filter is made of an inorganic substance or the like, in addition to the main absorption peak, a slight absorption peak appears in an unintended part, which causes deterioration of color tone, etc. In many cases, a problem that does not occur occurs, but in the present invention,
Since the region in which the organic dye is dispersed is used for wavelength cutting, the absorption wavelength can be accurately controlled, and only the specific wavelength can be selectively absorbed.

More specifically, the number of the absorption peaks in the visible light region is preferably 1 or more and less than 5, particularly preferably 1 or more and less than 3 and extremely preferably 2, which does not cut an extra wavelength region. It is possible to cut only the required wavelength. Further, in the present invention, the visible light region means a wavelength region of 360 nm to 800 nm.

In the polarizing film of the present invention, the organic dye that is preferably used in the region in which the organic dye is dispersed has excellent controllability of absorption wavelength in the visible light region, and has a narrow half-width of absorption spectrum and sharpness. As described above, organic dye compounds having various absorption peaks are suitable. Specific examples include squarylium compounds (diphenyl squarylium compounds, pyrazole squarylium compounds), tetraazaporphyrin compounds, and the like.
For example, as the diphenylsquarylium compound suitable for use in the overlapping points in the red and green color filter transmittance distribution curves, the compounds represented by the following general formula (I) are typical examples.

[0036]

[Chemical 1] [In the formula (I), R ¹ represents an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent, or a substituent. An allyoloxy group which may have or a halogen atom is shown.
Here, adjacent R ^{1 s} may be joined together to form an alkanediyl group or an alkylenedioxy group. R ²
Represents a hydrogen atom or a monovalent substituent, and G ¹ represents —N
A group represented by R ³ — (wherein R ³ represents a hydrogen atom or an alkyl group) or an oxygen atom, and G ² represents a carbonyl group or a sulfonyl group (here, G ^{When 2} is a sulfonyl group, R ² is not a hydrogen atom.). m, n and p are integers of 0 or more and m + n +
p is 5 or less. However, these substituents on the benzene ring may be different from each other on the other benzene ring, and in one benzene ring, m and n are 2 or less.
In the above cases, the groups represented by R ¹ and G ¹ -G ² -R ² may be different from each other with other substituents in the same ring. ]

More specifically, the compounds represented by the general formulas (I-1) to (I-56) shown in [Chemical formula 2] to [Chemical formula 9] are mentioned as typical examples.

[0038]

[Chemical 2]

[0039]

[Chemical 3]

[0040]

[Chemical 4]

[0041]

[Chemical 5]

[0042]

[Chemical 6]

[0043]

[Chemical 7]

[0044]

[Chemical 8]

[0045]

[Chemical 9]

Further, as a tetraazaporphyrin compound suitable for use at the overlapping points in the red and green color filter transmittance distribution curves, a compound of the general formula (II) shown in [Chemical Formula 10] is a typical example. Can be mentioned.

[0047]

[Chemical 10] [In formula (II), R ^{1 to} R ⁸ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, an amino group, or an optionally substituted alkyl group,
An alkoxy group which may have a substituent, an aryl group which may have a substituent, an aryloxy group which may have a substituent, an alkylamino group which may have a substituent, A dialkylamino group which may have a substituent, an alkylthio group which may have a substituent, or an arylthio group which may have a substituent are represented by R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ , and R ⁷ and R ⁸ may be connected to each other to form an aliphatic carbocycle. M represents two hydrogen atoms, a divalent metal atom, a trivalent mono-substituted metal atom, a tetravalent di-substituted metal atom or an oxy metal atom. ]

More specifically, the compounds represented by the general formulas (II-1) to (II-9) shown in [Chemical Formula 11] are listed as typical examples.

[0049]

[Chemical 11]

Pyrazole-based squarylium compounds suitable for use at the overlap points in the blue and green color filter transmittance distribution curves include
A typical example is the compound represented by the general formula (III) shown in [2].

[0051]

[Chemical 12] [In the formula (III), Y ₁ represents a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent, and each Y ₁ may be the same. It may be different. Y ₂ represents a hydrogen atom, an alkyl group which may have a substituent, an amino group which may have a substituent,
It represents an alkoxycarbonyl group which may have a substituent, and each Y ₂ may be the same or different. X represents an -O- or -NH- group. ]

More specifically, the compounds of the general formulas (III-1) to (III-8) shown in [Chemical Formula 13] are mentioned as typical examples.

[0053]

[Chemical 13]

Here, these squarylium compounds can be produced, for example, by the method described in Angew. Chem. 77 680-681 (1965) or in accordance therewith. In addition, these tetraazaporphyrin dyes are described in J.
It can be produced according to the method described in Gen. Chem. USSR vol.47, 1954-1958 (1977).

Further, in the present invention, in order to further improve the color reproducibility and obtain a vivid display image, the wavelength of 400
It is preferable to add a dye that selectively absorbs even in the vicinity of nm to the dye dispersion layer.

As this dye, for example, a dipyrazolylmethine dye of the general formula (IV) shown in [Chemical Formula 14] is suitable.

[0057]

[Chemical 14] [In the formula (IV), R ⁹ represents an alkyl group which may have a substituent, an aryl group which may have a substituent or a hydrogen atom, and R ¹⁰ has a substituent. An optionally alkyl group, an alkoxy group which may have a substituent, an alkoxycarbonyl group which may have a substituent, an aryl group which may have a substituent, an aryloxy group, a substituent An aryloxycarbonyl group which may have, an amino group which may have a substituent or a hydrogen atom,
R ¹¹ represents an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent or a hydrogen atom, and X represents oxygen. An atom or an NH group, and R ¹⁰ , R ¹¹ , and X
May be different from each other between both pyrazole rings. ]

More specifically, the compounds of the general formulas (IV-1) to (IV-9) shown in [Chemical Formula 15] are mentioned as typical examples.

[0059]

[Chemical 15]

Here, these pyrazolylmethine compounds can be produced, for example, by the method described in Liebigs Ann. Chem., 1680-1688 (1976), or in accordance with it.

In the present invention, as described above, the region in which the organic dye is dispersed is provided in order to precisely control the spectral distribution of the illumination light in the visible light region. However, the organic dye controls the absorption spectrum. Although excellent in properties, there is a problem that it is easily deteriorated by light and heat. Therefore, in the present invention, a so-called ultraviolet absorber and / or a so-called ultraviolet absorber having a function of an ultraviolet absorbing action, a free radical stabilizing action, an antioxidant action, etc., in the region where the organic dye is dispersed.
Alternatively, a light stabilizer is preferably arranged. Here, typically, organic ultraviolet absorbers (benzophenone-based, benzotriazole-based, ozanilide-based, formamidine-based), inorganic ultraviolet absorbers, hindered amine-based light stabilizers, aryl ester-based light stabilizers, phenol-based Antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants may be mentioned, and it is preferable to mix these in an appropriate amount so as not to sacrifice the optical characteristics and suppress the deterioration of the organic dye.

More specifically, for example, as an organic ultraviolet absorber, 2- (2'-hydroxy-5'-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5' -Di-t-butylphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, phenyl salsylate, 4-t-butylphenyl salsylate, 2,5 -Di-t-butylphenyl-
4-hydroxybenzoic acid n-hexadecyl ester,
2,4-di-t-butylphenyl-3 ′, 5′-di-t
-Butyl-4'-hydroxybenzoate and the like can be mentioned.

Further, examples of the inorganic ultraviolet absorber include titanium oxide, zinc oxide, cerium oxide, iron oxide, barium sulfate and the like. Here, as the ultraviolet absorber, the wavelength at which the transmittance becomes 50% is 350 to 420 nm.
Is preferable, and more preferably 360 to 400
The wavelength is shorter than 350 nm, the ultraviolet absorption ability is weak, and the wavelength longer than 420 nm is strongly colored, which is not preferable.

Further, in addition to the embodiment in which the ultraviolet absorber and / or the light stabilizer is blended in the region in which the organic dye is dispersed as described above, a layer which absorbs ultraviolet rays which has a serious influence on photodegradation is separately provided. It is also possible to provide an embodiment in which the deterioration of the organic dye is suppressed. That is, a mode in which a region in which the organic dye is dispersed is sandwiched between ultraviolet absorbing and / or reflecting layers can be implemented.

By using these organic dyes and providing a region in which the organic dyes are dispersed in order to realize the above-mentioned spectral characteristics, a polarizing film suitable for use in the present invention can be obtained. A mode in which the organic dye of the present invention is dispersed in the constituent polyvinyl alcohol resin can also be implemented. However, the most preferable method for obtaining the region in which the organic dye is dispersed in the present invention is to provide the resin coating layer 12 on the surface of the polarizing film 11a as shown in FIG.
A mode in which an organic dye is dispersed in the resin coating layer 12 can be mentioned.

This is because the coating film thickness and the dispersibility are easily controlled, so that the optical characteristics (transmission spectrum characteristics) can be easily managed and the cost is low.
As a typical example, a mode in which an organic dye is dispersed in a light and / or thermosetting resin, a binder resin and the organic dye are dispersed in a solvent, and after coating, the solvent is evaporated to leave only the binder resin. And the like.

Here, as the photocurable resin, a monofunctional acrylate, a monofunctional methacrylate, a polyfunctional acrylate, a polyfunctional methacrylate and the like are typical, and a photopolymerizable monomer excellent in dispersibility of an organic dye is selected, It is possible to obtain a region in which an organic dye having a desired light absorption property is dispersed by irradiating with ultraviolet light using a photopolymerization initiator such as an acetophenone type, a benzoin type, or a benzophenone type.

Examples of suitable binder resins include polyacrylate resins, polycarbonate resins, ethylene-vinyl alcohol copolymer resins,
Examples thereof include ethylene-vinyl acetate copolymer resins, AS resins, polyester resins and the like.

Further, since the polarizing film of the present invention is used by being laminated on the glass substrate of the liquid crystal cell, the adhesive material is arranged on one side, but the organic dye is dispersed in the adhesive layer. Is also possible. In such a mode, it is not necessary to newly provide a coating layer for dispersing the organic dye, and therefore, there is an advantage that the structure can be simplified.

A light diffusing function can be imparted to the polarizing film of the present invention. That is, a light control sheet (light diffusing sheet) having a function of diffusing light is usually arranged in an optical system of a back light source means (backlight) found in a conventional liquid crystal display, and a light guide body is provided. The pattern appearance was prevented and the quality of the surface light source was improved. However, these light diffusing layers are usually obtained by coating substantially transparent resin beads on a transparent film, and a process very similar to the process of coating the organic dye dispersion layer on the polarizing film described above. In the present invention, it is not necessary to perform these separately, and as shown in FIG. 1, the coating liquid for coating on the polarizing film 11a contains the substantially transparent beads 13 and the organic dye. By mixing and coating, not only the process can be omitted, but also the dimming sheet can be reduced and the liquid crystal display can be made thinner.

As a preferable range of this light diffusing property, FIG.
As shown in FIG. 4A, when collimated light such as the laser beam 14 is made incident on the polarizing film 11g having the light diffusing property, as shown in FIG. It is expressed using a diffusion angle, which is defined as a half width of the emission angle distribution, and the value of the diffusion angle is preferably 1 ° to 120 °, more preferably 5 ° to 90 °, and further preferably 10 ° to 60 °. Given as.

More specifically, substantially spherical beads typified by silica, polyacrylate, polystyrene, and silicone are blended and dispersed so as to have the above diffusion angle, and uniformly coated on the surface of the polarizing film. As shown in FIG. 1, the spherical beads 13 have the effect of diffusing the illumination light from the backlight 10. This is very convenient because the glare and pattern appearance can be suppressed appropriately and the adhesion of the polarizing film to the light guide can be suppressed.

In addition to the above, various methods can be cited as a method of imparting light diffusing property to the polarizing film of the present invention. For example, an embodiment of matting the surface of the polarizing film to obtain a light diffusing layer, a polarizing film Examples include a mode in which high refractive index fine particles such as glass powder are dispersed therein or the polarizing film itself is foamed to generate a difference in refractive index to obtain a light diffusion layer.

[0074]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the above-mentioned gist.
The present invention is not limited to the following examples.

(Example 1) A commercially available iodine type polarizing film (transmittance 44%, polarization degree 99.9%) was used as a base material, and polymethylmethacrylate resin (manufactured by Mitsubishi Rayon Co., Ltd., DIANAL BR-80) as a binder resin. ) Is added to the 25 wt% toluene solution of formula I-35 and the diphenyl squarylium compound is added to the binder resin in an amount of 0.16.
0 wt%, 0.053 wt% of the pyrazole-based squarylium compound represented by the formula III-3, and spherical beads made of acrylic resin having an average particle diameter of 35 μm were added to the binder resin component 7
8 wt% of each is mixed to prepare a coating liquid, which is coated on the polarizing film by a bar coating method, dried, and uniformly weighed at 4.8 g / m ² (calculated as binder resin content). After coating, the solvent was dried to obtain the polarizing film of the present invention. Collimated light of a He-Ne laser whose beam diameter was expanded by an afocal type optical system was made incident on the polarizing film, and the distribution of the quantity of outgoing light at each outgoing angle was measured as shown in FIG. 4, resulting in a diffusion angle of 17 degrees. It was confirmed that a polarizing film having a light diffusion property suitable for use in this invention was obtained.

As shown in FIG. 1, a polarizing film having a region in which the organic dye is dispersed is used as a transmission type active matrix driven twisted nematic mode liquid crystal panel (1
The liquid crystal panel was obtained by sticking it on the back surface of a 5.1 inch size) and sticking an ordinary polarizing film on the front surface. Further, a liquid crystal display device is constructed by using a side light type surface light source device having a cold cathode tube as a light source and a backlight light source. The backlight is turned on, the liquid crystal panel is driven so that each color of RGB is turned on, and the chromaticity value when each color is turned on is measured using a luminance meter (BM-7 manufactured by Topcom).
Shown in.

Since the color reproducibility has been improved, the image has a vivid and crisp display, and a liquid crystal display device having no discomfort even when a DVD (digital video disc) or a television image is displayed is obtained.

Further, the diphenyl squarylium compound has a light absorption peak with a half-width of light absorption of 25 nm at a position 13 nm from the overlap point of the color filter, and the pyrazole-based squarylium compound has a light absorption peak at a position 8 nm from the overlap point. It has a light absorption peak with a full width at half maximum of 41 nm, and since only two light absorption peaks are formed in the region in which the organic dye is dispersed, unnecessary spectra are not cut, and the color is extremely efficient. It was confirmed that the emission spectrum that reduces reproducibility was cut.

Example 2 A commercially available iodine type polarizing film (transmittance: 44%, polarization degree: 99.9%) was used as a base material, and a polymethylmethacrylate resin (manufactured by Mitsubishi Rayon, Dianal BR-80, manufactured by Mitsubishi Rayon Co., Ltd.) was used. ) In a 20 wt% dimethoxyethane solution, the tetraazaporphyrin compound of formula II-2 was added to the binder resin component in an amount of 0.
113 wt%, 0.053 wt% of the pyrazole-based squarylium compound represented by the formula III-3, and glass spherical beads having an average particle diameter of 12 μm with respect to the binder resin content of 15
0.3 wt% each of UV absorbers consisting of 0 wt% and 2- (2'-hydroxy-5'-t-butylphenyl) benzotriazole was mixed to prepare a coating liquid, and the coating liquid was bar-coated. Method was applied to the polarizing film, dried, and uniformly applied at a basis weight of 3.9 g / m ² (calculated as binder resin content), and then the solvent was dried to obtain the polarizing film of the present invention. Collimated light of a He-Ne laser whose beam diameter was expanded by an afocal type optical system was made incident on the polarizing film, and the distribution of the quantity of outgoing light at each outgoing angle was measured as shown in FIG.
It was confirmed that a polarizing film having a light diffusion property suitable for use in this invention was obtained.

As shown in FIG. 1, a polarizing film having a region in which the organic dye is dispersed is used as a transmissive active matrix driven twisted nematic mode liquid crystal panel (1
The liquid crystal panel was obtained by sticking it on the back surface of a 5.1 inch size) and sticking an ordinary polarizing film on the front surface. Further, a liquid crystal display device is constructed by using a side light type surface light source device having a cold cathode tube as a light source and a backlight light source. The backlight is turned on, the liquid crystal panel is driven so that each color of RGB is turned on, and the chromaticity value when each color is turned on is measured using a luminance meter (BM-7 manufactured by Topcom).
Shown in.

Since the color reproducibility is improved, the image becomes a vivid and crisp display, and a liquid crystal display device is obtained in which a DVD (digital video disk) or a television image is displayed without any discomfort.

Further, the tetraazaporphyrin compound has a light absorption peak with a light absorption half-value width of 32 nm at a position 8 nm from the overlap point of the color filter, and the pyrazole-based squarylium compound has a light absorption peak at a position 8 nm from the overlap point. It has a light absorption peak with a light absorption half-value width of 40 nm, and since only two light absorption peaks are formed in the region in which the organic dye is dispersed, unnecessary spectra are not cut and the efficiency is extremely high. It was confirmed that the emission spectrum, which deteriorates the color reproducibility, was well cut.

(Comparative Example) In the liquid crystal display device described in Example, Example 1 was used except that the region in which the organic dye and the transparent beads were dispersed was not provided on the polarizing film.
A liquid crystal display device was prepared and evaluated in the same manner as in. The results are shown in Table 1.

[0084]

[Table 1]

[0085]

As described above, by using the polarizing film of the present invention, it is possible to impart a color reproducibility comparable to that of a cathode ray tube while maintaining the high luminous efficiency of the liquid crystal display device. It was Therefore,
INDUSTRIAL APPLICABILITY The present invention makes it possible to popularize a large amount of liquid crystal televisions with low power consumption and a low environmental load, and to significantly reduce carbon dioxide, and has an extremely high industrial utility value.

[Brief description of drawings]

FIG. 1 is a schematic exploded perspective view of a transmissive liquid crystal display device using a polarizing film according to the present invention.

FIG. 2 is a spectral transmittance characteristic diagram of each color of a color filter.

FIG. 3 is a diagram showing characteristics of spectral transmittance (absorptivity) of a polarizing filter according to the present invention.

4A and 4B are explanatory diagrams of a diffusion angle.

[Explanation of symbols]

10 backlight 11 LCD panel 11a Polarizing film 11b, 11f glass substrate 11c TFT gate array 11d liquid crystal layer 11e color filter 11g Polarizing film 12 Resin coating layer 13 beads 14 laser beam

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H042 BA02 BA03 BA20                 2H048 BA02 BA45 BA66 BB02 BB04                       BB10 BB42 CA04 CA15 CA19                       CA23 CA24 CA27                 2H049 BA02 BA17 BA27 BB03 BB12                       BB63 BB66 BC22                 2H091 FA02Y FA08X FA08Z FA16Z                       FB02 LA16 LA20

Claims (8)

[Claims] 1. A transmissive type which has a light absorption function of a specific wavelength in a visible light region composed of a region in which an organic dye is dispersed, and the organic dye corresponding to each specific wavelength has a light absorption half-value width of 60 nm or less. Or a polarizing film used for a transflective liquid crystal display. 2. The polarizing film according to claim 1, wherein the number of light absorption peaks in the visible light region, which is a region in which the organic dye is dispersed, is 1 or more and less than 3. 3. A resin coating layer is provided on the surface,
The polarizing film according to claim 1 or 2, wherein the organic dye is dispersed in the resin coating layer. 4. The polarizing film according to claim 1, having a light diffusion function with a diffusion angle of 1 ° to 120 °. 5. The polarizing film according to claim 1, wherein an ultraviolet absorber and / or a light stabilizer is blended in a region in which the organic dye is dispersed. 6. A back light source means comprising a light source comprising a cold cathode tube and / or a hot cathode tube, and a light homogenizing means for converting the light from the light source into a substantially uniform surface light source, a polarizing film, and a color filter. In a liquid crystal display device comprising: a polarizing film according to any one of claims 1 to 5, a light absorption peak in a visible light region consisting of a region in which the organic dye is dispersed, A liquid crystal display device, which is located within a range of ± 30 nm from the overlap point in the spectral transmittance characteristic. 7. The liquid crystal display device according to claim 6, wherein the color filter is a pigment dispersion type color filter. 8. The liquid crystal display device according to claim 6, wherein the organic dye is made of squarylium-based and / or tetraazaporphyrin-based.