CN1942790A - Elliptical polarizing plate and image display - Google Patents

Abstract

The present invention provides an elliptical polarizing plate which is characterized in that an optical film comprising a lamination of a phase difference film (A) composed of a thermoplastic polymer containing a cyclic polyolefin resin, uniaxially oriented, and having a positive refractive index anisotropy (nx>nY nz) where nx, ny and nz are refractive indexes in the directions of the X-axis in which the in-plane refractive index is the greatest, the Y-axis perpendicular to the X-axis and the Z-axis in the thickness direction, and a phase difference film (B) fixed to homeotropic alignment and having a positive refractive index anisotropy (nz1>nx1 ny1) where nx1, ny1 and nz1 are refractive indexes in the directions of the X-axis in which the in-plane refractive index is the greatest, the Y-axis perpendicular to the X-axis and the Z-axis in the thickness direction is laminated on one side of a polarizer such that the delay axis of the phase difference film (A) and the absorption axis of the polarizer are perpendicular to each other. When the elliptical polarizing plate is employed in an in-plane switching active matrix liquid crystal display, lowering of contrast at a wide view angle can be suppressed and a high improvement effect of color shift is achieved.

Description

Elliptical polarizer and image display device

technical field

The present invention relates to an elliptically polarizing plate in which an optical film on which a retardation film is laminated and a polarizer are laminated. In addition, the present invention also relates to image display devices such as liquid crystal display devices, organic EL (electroluminescence) display devices, and PDPs using the above-mentioned elliptically polarizing plate. In particular, the elliptically polarizing plate of the present invention is suitable for use in an active matrix liquid crystal display device of a transverse electric field system (IPS mode).

Background technique

Conventionally, as a liquid crystal display device, a so-called TN mode liquid crystal display device in which liquid crystal having a positive dielectric constant anisotropy is twisted horizontally aligned between substrates facing each other has been mainly used. However, in the TN mode, in terms of drive characteristics, even if black display is attempted, liquid crystal molecules near the substrate cause birefringence, resulting in light leakage, making it difficult to display complete black. On the other hand, the liquid crystal display device of the transverse electric field method forms a parallel electric field on the liquid crystal substrate between the pixel electrode and the common electrode to perform pixel display. Black display is possible and wide viewing angles are obtained.

However, although in the conventional active matrix liquid crystal display device of the transverse electric field method, almost complete black display can be performed in the normal direction of the panel, when the panel is observed from a direction deviated from the normal direction, the off-disposition In the direction of the optical axis direction of the polarizing plates above and below the liquid crystal cell, light leakage, which cannot be avoided due to the characteristics of the polarizing plates, occurs, resulting in a narrow viewing angle and a decrease in contrast. In addition, when viewed from an oblique direction, the optical path of light becomes longer, and the apparent retardation of the liquid crystal layer changes. Therefore, if the viewing angle is changed, the wavelength of transmitted light changes, the color of the visible screen changes, and color shift occurs depending on the viewing direction.

Various proposals are disclosed for suppressing a decrease in contrast depending on a viewing angle or improving color shift in such a transverse electric field type liquid crystal display device (Patent Document 1, Patent Document 2). For example, Patent Document 1 proposes a technique in which a compensation layer having optical anisotropy is interposed between a liquid crystal layer and a pair of polarizing plates sandwiching the liquid crystal layer. This technique is effective in improving color shift, but is insufficient in suppressing a decrease in contrast. In addition, Patent Document 2 proposes a technique in which first and second retardation plates are interposed between a liquid crystal layer and a pair of polarizing plates sandwiching the liquid crystal layer. It is described that this technique is effective in suppressing a decrease in contrast and improving color shift, but a higher improvement effect is required.

Patent Document 1: Japanese Unexamined Patent Application Publication No. 11-133408

Patent Document 2: JP-A-2001-242462

Contents of the invention

The object of the present invention is to provide a kind of elliptically polarizing plate laminated with retardation film and polarizer, it is characterized in that, when being applied to the active matrix type liquid crystal display device of transverse electric field mode, can suppress the contrast ratio in the wide viewing angle. Reduced, and the improvement effect of color shift is high.

Another object of the present invention is to provide an image display device using the above-mentioned elliptically polarizing plate. In particular, it is possible to provide a lateral electric field type active matrix liquid crystal display device capable of suppressing a decrease in contrast at a wide viewing angle and having a high effect of improving color shift.

The inventors of the present invention conducted earnest studies to solve the above-mentioned problems, and as a result, found that the above-mentioned object can be achieved by an elliptically polarizing plate shown below, and completed the present invention.

That is, the present invention relates to an elliptically polarizing plate characterized in that an optical film formed by laminating the retardation film A described below and the retardation film B described below is on one side of the polarizer, and the retardation film The slow axis of A is laminated in such a way that it is perpendicular to the absorption axis of the polarizer, wherein: the retardation film A is composed of a thermoplastic polymer containing a cyclic polyolefin resin, and the direction in which the in-plane refractive index is the largest is the X axis, and When the direction perpendicular to the X-axis is the Y-axis, the thickness direction is the Z-axis, and the refractive indices in each axis direction are nx, ny, and nz respectively, it has positive refractive index anisotropy with unidirectional orientation (nx>nynz); Retardation film B is fixed in homeotropic alignment. When the in-plane refractive index is the largest direction is the X axis, the direction perpendicular to the X axis is the Y axis, the thickness direction is the Z axis, and the refractive indices in each axis direction are respectively nx ₁ , ny ₁ , and nz ₁ have positive refractive index anisotropy (nz ₁ >nx ₁ ny ₁ ).

The retardation film A and the retardation film B are laminated on the above-mentioned elliptically polarizing plate of the present invention. The retardation film A has the compensation function produced by the unidirectional positive refractive index anisotropy, and the retardation film B can also control the retardation in the thickness direction. In this way, it is possible to suppress a decrease in contrast due to a change in the axis of the polarizer caused by a change in viewing angle, to improve color shift, and to compensate for a wide viewing angle.

In addition, the retardation film A contains a cyclic polyolefin resin. Cyclic polyolefin resins have a small photoelastic modulus, and can suppress unevenness that tends to occur in tensile stress and durability tests, etc., especially when used in large panels such as transverse electric field systems (IPS mode).

In addition, the slow axis of the retardation film A of the elliptically polarizing plate of the present invention is laminated perpendicularly to the absorption axis of the polarizer. The orthogonal arrangement as described above is preferable in terms of obtaining high contrast.

In addition, the optical film laminated with the retardation film A and the retardation film B is laminated on the polarizer, and the optical film also serves as a protective film, so it can be thin and lightweight, and can suppress a decrease in contrast and improve color shift. preferred.

From the standpoint of suppressing a reduction in contrast at a wide viewing angle and improving the color shift, it is preferable to form an optical film by laminating the polarizer, retardation film A, and retardation film B in this order.

In the above-mentioned elliptically polarizing plate, as the above-mentioned retardation film A, a film containing a norbornene-based resin is preferably used. A film containing a norbornene-based resin is preferable in terms of excellent durability under high temperature and high temperature and high humidity conditions.

In the above-mentioned elliptically polarizing plate, in order to suppress a decrease in contrast and a color shift at a wide viewing angle, the retardation film B is preferably such that the retardation in the thickness direction: {((nx ₁ +ny ₁ )/2)-nz ₁ }× d (thickness: nm) is -500 nm to -10 nm. The retardation in the thickness direction of the retardation film B is more preferably -300 nm to -30 nm. More preferably, it is -200nm - -50nm.

In the above-mentioned elliptically polarizing plate, the retardation film B is not particularly limited as long as it has the above-mentioned refractive index, but a film containing a side chain type liquid crystal polymer is preferable. In addition, as the material of the retardation plate propyl ether B, a material whose in-plane refractive index becomes small in the stretching direction, that is, a so-called negative optical material can be exemplified. Examples of such materials include styrene-based resins, acrylic resins, and the like.

In the above-mentioned elliptically polarizing plate, as the retardation film A, a λ/4 plate can be used.

Furthermore, the present invention relates to an image display device characterized in that the above-mentioned elliptically polarizing plate is laminated. As an image display device, it is preferably used in a liquid crystal display device, and is particularly preferably used in an active matrix liquid crystal display device whose driving mode is an in-situ electric field system (IPS) mode. An image display device such as a liquid crystal display device using the elliptically polarizing plate can realize a wide viewing angle, and can suppress a decrease in contrast when viewing a display screen from an oblique side, thereby improving color shift.

A liquid crystal display device can be formed by arranging the elliptically polarizing plate of the present invention on one side or both sides of a liquid crystal cell instead of a conventional polarizing plate. The configuration of the elliptically polarizing plate of the present invention relative to the liquid crystal cell is not particularly limited. From the perspective of display quality, it is preferable to make the optical film laminated with the retardation film A and the retardation film B be positioned at the liquid crystal cell side (that is, the above-mentioned optical film is positioned on the polarizer. and the liquid crystal cell), and in the liquid crystal display device, the above-mentioned optical film is arranged between the polarizers arranged in the crossed Nicols. In addition, in the organic EL display device, the elliptically polarizing plate is disposed on the metal electrode, but the polarizer is preferably laminated at the position farthest from the liquid crystal cell or the metal electrode.

Description of drawings

FIG. 1 is a cross-sectional view and a conceptual diagram of an elliptically polarizing plate of the present invention.

Fig. 2 is a cross-sectional view and a conceptual diagram of an elliptically polarizing plate of the present invention.

FIG. 3 is one form of a conceptual diagram of a liquid crystal display device of the present invention.

FIG. 4 is one form of a conceptual diagram of a liquid crystal display device of a comparative example.

In the figure, A: retardation film satisfying nx>nynz, B: retardation film satisfying nz ₁ >nx 1ny ₁ , 1a: polarizer, 2: optical film, LC: liquid _crystal cell.

Detailed ways

The elliptically polarizing plate of the present invention will be described below with reference to FIG. 1 and FIG. 2 . As shown in FIGS. 1 and 2 , in the elliptically polarizing plate of the present invention, an optical film 2 laminated with a retardation film A and a retardation film B is laminated on one side of a polarizer 1a. In addition, as shown in FIGS. 1 and 2, a protective film 1b may be laminated on the other side of the polarizer 1a. This is shown as a polarizing plate 1 . The aforementioned optical film 2 also serves as a protective film for the polarizer 1a. In addition, the elliptically polarizing plate of the present invention is laminated such that the slow axis of the retardation film A is perpendicular to the absorption axis of the polarizer 1a.

In the elliptically polarizing plate shown in FIG. 1 and FIG. 2, the stacking order of the above-mentioned optical film 2 with respect to the polarizer 1a is not particularly limited, but when it is installed in a liquid crystal display device, the reduction in contrast and color shift can be suppressed. From the point of view, it is preferable to stack the retardation film A and the retardation film B in order starting from the polarizer 1 a as shown in FIG. 1 . In addition, in FIG. 1 and FIG. 2 , the polarizer 1a, the retardation film A, and the retardation film B are laminated via an adhesive layer or an adhesive layer. The pressure-sensitive adhesive layer or the pressure-sensitive adhesive layer may be in the form of one layer or two or more layers overlapped.

The retardation film A used is a film in which the direction in which the in-plane refractive index of the film is maximized is defined as the X-axis, the direction perpendicular to the X-axis is defined as the Y-axis, and the thickness direction of the film is defined as the Z-axis. When the refractive indices in the respective axial directions are nx, ny, and nz, nx>nynz is satisfied. That is, the three-dimensional refractive index ellipsoid uses a material in which the refractive index of the main axis in one direction is larger than that of the other two directions and optically exhibits positive unidirectionality.

The retardation film A can be obtained by uniaxially or biaxially stretching a polymer film composed of a thermoplastic polymer containing a cyclic polyolefin resin in the plane direction. As a cyclic polyolefin resin, a norbornene-type resin can be illustrated, for example.

Examples of norbornene-based resins include (1) ring-opening (co)polymers of norbornene-based monomers, further polymerized by addition of maleic acid, addition of cyclopentadiene, etc. (2) Resins obtained by addition polymerization of norbornene-based monomers; (3) Norbornene-based monomers and ethylene or α- Resins obtained by addition-type copolymerization of olefin-based monomers such as olefins, etc. A polymerization method and a hydrogenation method can be performed by a usual method.

Examples of the above-mentioned norbornene-based monomers include norbornene and its alkyl and/or alkylene substituted products, such as 5-methyl-2-norbornene, 5-dimethyl-2- Polar substituents such as norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, etc.; bicyclic Pentadiene, 2,3-dihydrodicyclopentadiene, etc.; dimethyloctahydronaphthalene, its alkyl and/or alkylene substituents, and polar substituents such as halogen, for example, 6-methyl -1,4:5,8-Dimethylbridge-1,4,4a,5,6,7,8,8a-Octahydronaphthalene, 6-Ethyl-1,4:5,8-Dimethylbridge- 1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethylene-1,4:5,8-dimethyl bridge-1,4,4a,5,6,7, 8,8a-octahydronaphthalene, 6-chloro-1,4:5,8-dimethyl bridge-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-cyano-1 , 4: 5,8-Dimethylbridge-1, 4, 4a, 5, 6, 7, 8, 8a-octahydronaphthalene, 6-pyridyl-1, 4: 5,8-Dimethylbridge-1, 4,4a,5,6,7,8,8a-octahydronaphthalene, 6-methoxycarboxy-1,4:5,8-dimethyl bridge-1,4,4a,5,6,7,8 , 8a-octahydronaphthalene, etc.; 3-4 polymers of dicyclopentadiene, for example, 4,9:5,8-dimethyl bridge-3a, 4, 4a, 5, 8, 8a, 9, 9a-octahydro-1H-fluorene, 4,11:5,10:6,9-trimethyl bridge 3a, 4, 4a, 5, 5a, 6, 9, 9a, 10, 10a, 11, 11a-dodecahydro -1H-cyclopentadiene anthracene, etc.

The above-mentioned norbornene-based resin may be used in combination with other cycloolefins capable of ring-opening polymerization within the range that does not impair the object of the present invention. Specific examples of such cycloolefins include compounds having one reactive double bond, such as cyclopentene, cyclooctene, and 5,6-dihydrodicyclopentadiene.

The norbornene-based resin has a number average molecular weight (Mn) of 25,000 to 200,000, preferably 30,000 to 100,000, more preferably 40,000 to 80,000, as measured by gel permeation chromatography (GPC) using a toluene solvent. When the number average molecular weight is within the above range, excellent mechanical strength, good solubility, moldability, and good operability in casting can be achieved.

When the above-mentioned norbornene-based resin is obtained by hydrogenating a ring-opening copolymer of a norbornene-based monomer, a hydrogenation rate of 90% or more is generally used from the viewpoint of heat deterioration resistance, light deterioration resistance, and the like. substance. Preferably it is 95% or more. More preferably, it is 99% or more.

Specific examples of the film containing the above-mentioned norbornene-based resin include Zenonoa film manufactured by Nippon Zenon Co., Ltd., Alton film manufactured by JSR Corporation, and the like.

From the viewpoint of suppressing a decrease in contrast and improving color shift, it is effective that the front retardation ((nx-ny)×d (thickness: nm)) of the retardation film A is 50 to 210 nm. The aforementioned front phase difference is preferably 70 nm or more, further 80 nm or more, further 90 nm or more. In addition, the above front retardation is preferably 200 nm or less, more preferably 190 nm or less. The thickness (d) of the retardation film A is not particularly limited, but is preferably 1 to 200 μm, more preferably 2 to 100 μm.

Retardation film B is fixed to be vertically oriented. When the direction in which the in-plane refractive index is the largest is set as the X-axis, the direction perpendicular to the X-axis is set as the Y-axis, and the thickness direction is set as the Z-axis, the refractive index in each axis direction is When nx ₁ , ny ₁ , and nz ₁ are respectively used, a film satisfying positive refractive index anisotropy (nz ₁ >nx ₁ ny ₁ ) is used. The phase difference film B can be obtained by aligning a liquid crystal material with a vertical alignment agent, for example. As a liquid crystal compound that can be vertically aligned, for example, a nematic liquid crystal compound is known. An overview of such alignment techniques for liquid crystal compounds is described in, for example, Chemical Review 44 (Surface Improvement, edited by the Chemical Society of Japan, pages 156 to 163).

In addition, as the above-mentioned liquid crystal material, for example, one having positive refractive index anisotropy and containing a monomer unit (a) containing a side chain of a liquid crystalline segment and a monomer unit (b) containing a side chain of a non-liquid crystalline segment can be used. Side chain type liquid crystal polymers are formed. The above-mentioned side chain type liquid crystal polymer can achieve vertical alignment of the liquid crystal polymer without using a vertical alignment film.

The above-mentioned monomer unit (a) is a unit including a side chain having nematic liquid crystallinity, and examples thereof include the general formula (a)

[chemical 1]

(wherein, R ¹ represents a hydrogen atom or a methyl group, a represents a positive integer of 1 to 6, X ¹ represents a -CO ₂ - group or -OCO- group, R ² represents a cyano group, an alkane with 1 to 6 carbon atoms Oxygen group, fluorine group or alkyl group having 1 to 6 carbon atoms, b and c represent an integer of 1 or 2. ) represents a monomer unit.

In addition, the monomer unit (b) is a unit having a linear side chain, for example, general formula (b):

[Chem 2]

(wherein, ^R3 represents a hydrogen atom or a methyl group, ^R4 represents an alkyl group with 1 to 22 carbon atoms, a fluoroalkyl group with 1 to 22 carbon atoms, or the general formula (b1):

[Chem 3]

Wherein, d represents a positive integer of 1 to 6, and R ⁵ represents an alkyl group having 1 to 6 carbon atoms. ) represents a monomer unit.

In addition, the ratio of the monomer unit (a) to the monomer unit (b) is not particularly limited and varies depending on the type of the monomer unit, but if the ratio of the monomer unit (b) is too large, the side chain type liquid crystal polymer Since liquid crystal monodomain orientation is not shown, (b)/{(a)+(b)}=0.01-0.8 (molar ratio) is preferable. Especially more preferably, it is 0.1 to 0.5.

In addition, as a liquid crystal polymer capable of forming a vertically aligned liquid crystal film, a monomer containing a monomer unit (a) containing a side chain of a liquid crystalline fragment described above and a monomer containing a side chain of a liquid crystal fragment having an alicyclic ring structure can be mentioned. A side chain type liquid crystal polymer of the unit (c).

Above-mentioned monomeric unit (c) is the unit that has the side chain of nematic liquid crystallinity, for example can enumerate general formula (c):

[chemical 4]

(wherein, R ⁶ represents a hydrogen atom or a methyl group, h represents a positive integer of 1 to 6, X ² represents a -CO ₂ - group or -OCO- group, e and g represent an integer of 1 or 2, and f represents 0 to 6 Integer of 2, R ⁷ represents a cyano group, an alkyl group having 1 to 12 carbon atoms. ) represents a monomer unit.

In addition, the ratio of the monomer unit (a) to the monomer unit (c) is not particularly limited and varies depending on the type of the monomer unit, but if the ratio of the monomer unit (c) is too large, the side chain type liquid crystal polymer Since liquid crystal monodomain orientation is not shown, (c)/{(a)+(c)}=0.01-0.8 (molar ratio) is preferable. Particularly more preferably, it is 0.1 to 0.6.

The liquid crystal polymer that can form the retardation film B is not limited to the liquid crystal polymer having the monomer units exemplified above, and the monomer units exemplified above may be combined appropriately.

The weight average molecular weight (GPC) of the side chain type liquid crystal polymer is preferably 2,000 to 100,000. By adjusting the weight average molecular weight within such a range, performance as a liquid crystal polymer can be exhibited. If the weight-average molecular weight of the side-chain type liquid crystal polymer is too small, the film-forming property of the alignment layer tends to be poor, so the weight-average molecular weight is more preferably 2.5 thousand or more. On the other hand, when the weight-average molecular weight is too large, the orientation as a liquid crystal tends to be poor and it is difficult to form a uniform orientation state, so the weight-average molecular weight is more preferably 50,000 or less.

In addition, the side chain type liquid crystal polymers exemplified above can be prepared by copolymerizing acrylic monomers or methacrylic monomers corresponding to the above-mentioned monomer units (a), monomer units (b), and monomer units (c). modulation. In addition, monomers corresponding to the monomer unit (a), the monomer unit (b), and the monomer unit (c) can be synthesized by known methods. The preparation of the copolymer can be carried out by, for example, a polymerization method such as a conventional acrylic monomer such as a radical polymerization method, a cationic polymerization method, or an anionic polymerization method. In addition, when the radical polymerization method is applied, various polymerization initiators can be used, but among them, it is preferable to use azobisisobutyronitrile or dibenzoyl peroxide, which decompose at an intermediate temperature without high or low decomposition temperature. the polymerization initiator.

A photopolymerizable liquid crystal compound can be mixed with the above-mentioned side chain type liquid crystal polymer to be used as a liquid crystal composition. The photopolymerizable liquid crystal compound is a liquid crystal compound having at least one unsaturated double bond such as an acryloyl group or a methacryloyl group as a photopolymerizable functional group, and a liquid crystal compound having nematic liquid crystallinity is favorably used. As such a photopolymerizable liquid crystal compound, the acrylate or methacrylate used as the said monomer unit (a) can be illustrated. As a photopolymerizable liquid crystal compound, in order to improve durability, it is preferable to have 2 or more photopolymerizable functional groups. As such a photopolymerizable liquid crystal compound, the following chemical formula 5 can be illustrated, for example:

[chemical 5]

(In the formula, R represents a hydrogen atom or a methyl group, A and D represent 1,4-phenylene or 1,4-cyclohexylene independently of each other, and X represent -COO-, -OCO- or -O group-, B represents 1,4-phenylene, 1,4-cyclohexylene, 4,4'-biphenylene or 4,4'-dicyclohexylene, m and n are independent of each other, represents an integer of 2 to 6.) represents a cross-linked nematic liquid crystal monomer and the like. In addition, as a photopolymerizable liquid crystal compound, a compound in which the terminal "H ₂ C=CR-CO ₂ -" in the above-mentioned Compound 5 is substituted with a vinyl ether group or an epoxy group, or a compound in which "-(CH ₂ ) _m -" and/or "-(CH ₂ ) _n -" are replaced by "-(CH ₂ ) ₃ -C ^* H(CH ₃ )-(CH ₂ ) ₂ -" or "-(CH ₂ ) ₂ -C ^* H(CH ₃ )-(CH ₂ ) ₃ -” compounds.

The above-mentioned photopolymerizable liquid crystal compound, by heat treatment, as a liquid crystal state, for example, makes it exhibit a nematic liquid crystal layer, and vertically aligns with the side chain type liquid crystal polymer, and then, by polymerizing or crosslinking the photopolymerizable liquid crystal compound, it can be made The durability of the vertical alignment liquid crystal film is improved.

The ratio of the photopolymerizable liquid crystal compound to the side chain type liquid crystal polymer in the liquid crystal composition is not particularly limited, and may be appropriately determined in consideration of the durability of the vertically aligned liquid crystal film to be obtained, but usually the photopolymerizable liquid crystal compound:side chain type liquid crystal polymer is preferably preferably Chain type liquid crystal polymer (weight ratio) = about 0.1:1 to 30:1, particularly preferably 0.5:1 to 20:1, further preferably 1:1 to 10:1.

In the above-mentioned liquid crystal composition, a photopolymerization initiator is usually contained. Various photopolymerization initiators can be used without particular limitation. As a photoinitiator, Irgacure 907, Irgacure 184, Irgacure 651, Irgacure 369 etc. by Ciba Specialty Chemicals Co., Ltd. can be illustrated, for example. The amount of photopolymerization initiator to be added can be added in an amount that does not disturb the vertical orientation of the liquid crystalline composition in consideration of the type of photopolymerizable liquid crystal compound, the compounding ratio of the liquid crystalline composition, and the like. Usually, it is preferably about 0.5 to 30 parts by weight with respect to 100 parts by weight of the photopolymerizable liquid crystal compound. Especially preferably, it is 3 weight part or more.

Retardation film B is produced by coating a vertically aligned side chain type liquid crystal polymer on a substrate, then vertically aligning the side chain type liquid crystal polymer in a liquid crystal state, and immobilizing it while maintaining the aligned state. And carried out. In addition, in the case of using a vertical alignment liquid crystal composition containing the above-mentioned side chain type liquid crystal polymer and a photopolymerizable liquid crystal compound, after applying it on the substrate, then making the liquid crystal composition into a In the liquid crystal state, it is vertically aligned and irradiated with light while maintaining the aligned state.

The substrate coated with the above-mentioned side chain type liquid crystal polymer and liquid crystal composition may be in any shape of glass substrate, metal foil, plastic plate or plastic film. The plastic film is not particularly limited as long as it does not change at the temperature of orientation, for example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, diacetic acid Films made of transparent polymers such as cellulose polymers such as cellulose and cellulose triacetate, polycarbonate polymers, and acrylic polymers such as polymethyl methacrylate. A vertical alignment film may not be provided on the substrate. The thickness of the substrate is usually about 10 to 1000 μm.

The method for coating the above-mentioned side chain type liquid crystal polymer or liquid crystal composition on the substrate includes a solution coating method using a solution in which the side chain type liquid crystal polymer or liquid crystal composition is dissolved in a solvent, or Among the melt coating methods of melting the liquid crystal polymer or liquid crystal composition, a method of coating a solution of a side chain type liquid crystal polymer or liquid crystal composition on a support substrate by a solution coating method is preferable.

As a method of coating a solution of a side chain type liquid crystal polymer or a liquid crystal composition adjusted to a desired concentration using the above-mentioned solvent on a substrate, for example, a roll coating method, a gravure coating method, a spin coating method, etc., can be used. method, rod coating method, etc. After coating, the solvent is removed to form a liquid crystal polymer layer or a liquid crystal composition layer on the substrate. The conditions for removing the solvent are not particularly limited, and the solvent can be substantially removed as long as the liquid crystal polymer layer or liquid crystal composition layer does not flow or flow. Usually, the solvent is removed by drying at room temperature, drying in a drying oven, heating on a hot plate, or the like. Among these coating methods, the gravure coating method used in the present invention is preferable from the viewpoint of easy and uniform coating over a large area.

Next, the side-chain type liquid crystal polymer layer or the liquid crystal composition layer formed on the support substrate is brought into a liquid crystal state and vertically aligned. For example, heat treatment is performed to vertically align the side chain type liquid crystal polymer or liquid crystal composition in the liquid crystal state in the liquid crystal temperature range. As a heat treatment method, it can be performed by the method similar to the above-mentioned drying method. The temperature of the heat treatment is different depending on the type of the side chain type liquid crystal polymer or liquid crystal composition used and the support substrate, so it cannot be generalized, but it is usually performed in the range of 60 to 300°C, preferably 70 to 200°C. In addition, the heat treatment time varies depending on the heat treatment temperature and the type of side chain type liquid crystal polymer or liquid crystal composition or substrate used, and cannot be generalized, but is usually selected in the range of 10 seconds to 2 hours, preferably 20 seconds to 30 minutes. When it is shorter than 10 seconds, vertical alignment formation may not proceed sufficiently. Among these orientation temperatures and processing time, in view of operability and mass production, the present invention preferably has an orientation temperature of 80-150° C. and a processing time of about 30 seconds to 10 minutes.

After the heat treatment is finished, a cooling operation is performed. The cooling operation can be performed by taking out the heat-treated vertically aligned liquid crystal film from the heating environment in the heat treatment operation to room temperature. In addition, forced cooling such as air cooling and water cooling is also possible. The alignment is fixed by cooling the above vertical alignment layer of the side chain type liquid crystal polymer to below the glass transition temperature of the side chain type liquid crystal polymer.

In the case of a liquid crystal composition, light irradiation is carried out to the vertically aligned liquid crystal alignment layer thus fixed, so that the photopolymerizable liquid crystal compound is polymerized or crosslinked, and the photopolymerizable liquid crystal compound is fixed to obtain a vertically aligned liquid crystal film with improved durability. layer. Light irradiation is performed by ultraviolet irradiation, for example. In order to sufficiently promote the reaction, the ultraviolet irradiation conditions are preferably in an inert gas atmosphere. Typically, a high-pressure mercury ultraviolet lamp with an illuminance of about 80 to 160 mW/cm ² is used typically. Other types of lamps such as metahalide UV lamps and incandescent lamps can also be used. In addition, the surface temperature of the liquid crystal layer when irradiated with ultraviolet rays is properly adjusted within the liquid crystal temperature range by using cold mirrors, water cooling and other cooling or speeding up the line speed.

In this way, a film of a side chain type liquid crystal polymer or a liquid crystal composition is produced, and fixed while maintaining the orientation, to obtain a retardation film B. The thickness of the vertically aligned liquid crystal film of the present invention is not particularly limited, and the thickness of the coated vertically aligned liquid crystal film layer composed of the above-mentioned side chain type liquid crystal polymer is preferably about 0.3-200 μm, more preferably 0.5-200 μm. If it is less than 0.3 μm, the film thickness is too thin, so it is difficult to control the thickness. When it exceeds 200 μm, when mounted on an image display device, there is an orientation in which the viewing angle of up, down, left, and right is expanded, and on the contrary, a narrowed orientation may occur. The retardation film B may be used without peeling from the substrate or without peeling from the substrate.

Lamination of the phase difference film A and the phase difference film B can use an adhesive layer or an adhesive layer. There are no particular restrictions on the material forming the adhesive layer or the adhesive layer, for example, acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine-based or rubber-based polymers, etc. material as the base polymer. It is particularly preferable to use an adhesive such as an acrylic adhesive that is excellent in optical transparency, exhibits appropriate wettability, coagulation, and adhesive properties, and is excellent in weather resistance, heat resistance, and the like.

Formation of an adhesive layer or an adhesive layer can be performed by an appropriate method. As an example, for example, in a solvent composed of a suitable solvent such as toluene or ethyl acetate alone or in a mixture, the base polymer or its composition is dissolved or dispersed to prepare a solution of about 10 to 40% by weight, and the Appropriate development methods such as casting method or coating method, the method of directly attaching the solution on the above-mentioned substrate or liquid crystal film, or forming an adhesive layer or an adhesive layer on the spacer as described above, and transferring it to the above-mentioned liquid crystal film The way on the layer and so on.

In addition, in the adhesive layer or the adhesive layer, for example, natural or synthetic resins, especially tackifying resins, fillers, pigments, etc. composed of glass fibers, glass beads, metal powders, other inorganic powders, etc., may also be contained. Colorants, antioxidants and other additives. Moreover, microparticles|fine-particles may be contained and light-diffusion property may be provided.

The thickness of the pressure-sensitive adhesive layer or adhesive layer can be appropriately determined according to the purpose of use, adhesive force, etc., and is generally 1 to 500 μm, preferably 5 to 200 μm, and particularly preferably 10 to 100 μm.

The adhesive layer or the exposed surface of the adhesive layer may be temporarily covered with a spacer in order to prevent contamination or the like before use in practical use. In this way, contact with the adhesive layer or adhesive layer in normal operating conditions can be prevented. As the spacer, on the basis of satisfying the above-mentioned thickness conditions, for example, plastic films, rubber sheets, paper, cloth, Conventionally, suitable separators such as non-woven fabrics, nets, foamed sheets, metal foils, and laminates thereof, which have been coated with suitable sheets, are suitable.

In addition, it is also possible to use, for example, a salicylate-based compound, a benzophenol-based compound, a benzotriazole-based compound, or a cyanoacrylate-based Compounds, nickel complex compounds and other ultraviolet absorbers are treated to make them have ultraviolet absorbing ability, etc.

The polarizer is not particularly limited, and various polarizers can be used. As a polarizer, for example, on hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and ethylene-vinyl acetate copolymer-based partially saponified films, adsorption of iodine or Dichroic materials such as dichroic dyes and uniaxially stretched materials; polyolefin-based oriented films such as dehydration-treated products of polyvinyl alcohol or dehydrochloric acid-treated products of polyvinyl chloride, etc. Among them, a polarizer obtained by stretching a polyvinyl alcohol-based film and absorbing and aligning a dichroic material (iodine, dye) is preferable. The thickness of the polarizer is not particularly limited, but is usually about 5 to 80 μm.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching it, for example, can be produced by dipping polyvinyl alcohol in an aqueous solution of iodine, dyeing it, and stretching it to 3 to 7 times its original length . If necessary, it may be immersed in an aqueous solution of boric acid, potassium iodide, or the like. In addition, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed with water before dyeing. Washing the polyvinyl alcohol-based film with water not only removes dirt and anti-blocking agents on the surface of the polyvinyl alcohol-based film, but also prevents unevenness such as staining by swelling the polyvinyl alcohol-based film. Stretching may be performed after dyeing with iodine, stretching may be performed while dyeing, or dyeing with iodine may be performed after stretching. Stretching may also be performed in an aqueous solution of boric acid, potassium iodide, or the like, or in a water bath.

The above-mentioned optical film (retardation film A or retardation film B) is laminated on one side of the polarizer, and usually has a protective film on the other side. The protective film is preferably a material that is generally used as a protective film for polarizers and has good properties in terms of transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like. As the material of the above-mentioned protective film, for example, polyester-based polymers such as polyethylene terephthalate or polyethylene naphthalate; cellulose-based polymers such as diacetyl cellulose or triacetyl cellulose; Polymers; Acrylic polymers such as polymethyl methacrylate; Styrenic polymers such as polystyrene or acrylonitrile-styrene copolymer (AS resin); Polycarbonate polymers, etc. In addition, as examples of polymers forming the above-mentioned transparent protective film, polyolefin-based polymers such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and ethylene-propylene copolymers can also be exemplified. ; vinyl chloride polymers; amide polymers such as nylon or aromatic polyamide; imide polymers; sulfone polymers; polyether sulfone polymers; polyether-ether ketone polymers; polyphenylene sulfide Ether-based polymers; vinyl alcohol-based polymers, vinylidene chloride-based polymers; polyvinyl butyral-based polymers; allyl-based polymers; polyoxymethylene-based polymers; epoxy-based polymers; or Mixtures of the above-mentioned polymers, etc. Further examples include protective films made of acrylic, urethane, acrylic urethane, epoxy, silicone, and other thermosetting and ultraviolet curable resins.

In addition, polymer films described in Japanese Patent Laid-Open No. 2001-343529 (WO 01/37007), for example, comprising (A) a thermoplastic resin having a substituted and/or unsubstituted imino group in a side chain, and (B) ) A resin composition of a thermoplastic resin having substituted and/or unsubstituted phenyl and nitrile groups in the side chain. As a specific example, a film of a resin composition containing an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be cited. As the film, a film composed of a mixed extrusion product of a resin composition or the like can be used.

From the viewpoint of polarization characteristics and durability, a transparent film that can be used particularly preferably is a triacetylcellulose film whose surface has been subjected to saponification treatment with alkali or the like. The thickness of the transparent film can be appropriately determined, but it is generally about 10 to 500 μm from the viewpoint of handling properties such as strength and handleability, and thin layer properties. It is more preferably 20 to 300 μm, and still more preferably 30 to 200 μm.

In addition, it is best not to color the protective film. Therefore, it is preferable to use Rth=[(nx+ny)/2-nz] d (where nx and ny are the main refractive indices in the plane of the film, nz is the refractive index in the film thickness direction, and d is the film thickness). A protective film with a retardation value in the film thickness direction of -90nm to +75nm. By using a protective film having a retardation value (Rth) in the thickness direction of -90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the protective film can be almost eliminated. The retardation value (Rth) in the thickness direction is more preferably -80 nm to +60 nm, particularly preferably -70 nm to +45 nm.

The aforementioned polarizer and protective film are adhered with a water-based adhesive or the like. Examples of the water-based adhesive include polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based, water-based polyurethane, and water-based polyester.

As the above-mentioned protective film, hard coating, antireflection treatment, antiblocking treatment, treatment for the purpose of diffusion or antiglare can be performed.

The purpose of the hard coat treatment is to prevent damage to the surface of the polarizer, for example, by adding an appropriate UV-curable resin such as acrylic or silicone to the surface of the transparent protective film, which has good hardness, sliding properties, etc. Formation of a method such as a cured film. The purpose of antireflection treatment is to prevent reflection of external light on the surface of the polarizing plate, and it can be accomplished by forming a conventional antireflection film or the like. In addition, anti-blocking treatment is performed to prevent sticking to adjacent layers.

In addition, the purpose of implementing anti-glare treatment is to prevent external light from being reflected on the surface of the polarizer and interfere with the recognition of the transmitted light of the polarizer. In an appropriate manner, it is formed by imparting a fine uneven structure to the surface of the protective film. As the fine particles contained in the formation of the above-mentioned surface fine uneven structure, for example, particles made of silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, cadmium oxide, antimony oxide, etc. Transparent particles such as conductive inorganic particles composed of other components, organic particles composed of cross-linked or uncross-linked polymers, etc. When forming the fine uneven structure on the surface, the amount of fine particles used is usually about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin for forming the fine uneven structure on the surface. The antiglare layer may also serve as a diffusion layer that diffuses light transmitted through the polarizer to widen the viewing angle (viewing angle widening function, etc.).

In addition, the above-mentioned anti-reflection layer, anti-adhesion layer, diffusion layer and anti-glare layer may be provided on the transparent protective film itself, or may be provided as another optical layer separately from the transparent protective film.

The elliptically polarizing plate of the present invention is preferably used in an IPS mode liquid crystal display device. An IPS mode liquid crystal display device includes a liquid crystal cell including: a pair of substrates sandwiching a liquid crystal layer, an electrode group formed on one of the pair of substrates, and a dielectric electrode sandwiched between the substrates. An anisotropic liquid crystal composition material layer, an alignment control layer formed on opposite sides of the pair of substrates for aligning molecules of the liquid crystal composition material in a predetermined direction, and a driving mechanism for applying a driving voltage to the electrode group. The electrode group has an arrangement structure such that a parallel electric field is mainly applied to the interface between the alignment control layer and the liquid crystal composition material layer.

The elliptically polarizing plate of the present invention is disposed on at least one of the viewing side and the incident side of the liquid crystal cell. FIG. 3 is a case where the elliptically polarizing plate of FIG. 1 is disposed on the viewing side. As shown in FIG. 3 , the elliptically polarizing plate preferably has the optical film 2 on the liquid crystal cell LC side. In Fig. 3, a polarizing plate 1' is disposed on the opposite side (light incident side) to the liquid crystal cell 4 on which the elliptically polarizing plate is disposed. The absorption axes of the polarizing plate 1' arranged on both sides of the substrate of the liquid crystal cell LC and the absorption axis of the elliptically polarizing plate (polarizing plate 1) are arranged in a state of being perpendicular to each other. As the polarizing plate 1', a polarizing plate in which a protective film 1b is laminated on both sides of a polarizer 1a is generally used.

The above-mentioned liquid crystal display device in FIG. 3 is an example of a liquid crystal cell, and the elliptically polarizing plate of the present invention can be applied to other various liquid crystal display devices.

Example

An example is given below to describe one embodiment of the present invention, but the present invention is not limited to the examples.

In addition, the refractive index and phase difference of each optical film were measured by using an automatic birefringence measuring device (manufactured by Oji Scientific Instruments Co., Ltd., automatic birefringence meter KOBRA21ADH) to measure the principal refractive index nx at λ=590 nm in the film plane and in the thickness direction. , ny, nz characteristics to implement.

Reference example

(polarizer)

A polyvinyl alcohol film is dipped in warm water to swell, dyed in an iodine/potassium iodide aqueous solution, and then uniaxially stretched in a boric acid aqueous solution to obtain a polarizer. The single transmittance, parallel transmittance, and crossed transmittance of this polarizer were measured with a spectrophotometer, and the transmittance was 43.5%, and the degree of polarization was 99.9%.

Example 1

(retardation film A)

A norbornene-based unstretched film with a thickness of 100 μm (Aiton film manufactured by JSR Co., Ltd.) was uniaxially stretched to 1.3 times at 170°C. The obtained stretched film thickness: 80 μm, front phase difference: 100 nm. The obtained stretched film has uniaxially stretched positive refractive index anisotropy (nx>nynz).

(retardation film B)

[chemical 6]

Prepare the polymeric liquid crystal ( A solution in which 20 parts by weight of Paliocolor LC242 (manufactured by BASF) and 3 parts by weight of a photoinitiator (Irgacure 907: manufactured by Chiba Specialty Chemicals) are dissolved in 75 parts by weight of cyclohexanol relative to the polymerizable liquid crystal. Next, the solution was coated on the Zeonoa film of Japan’s Zenon Corporation using a bar coater, and after drying and alignment at 100° C. for 10 minutes, it was cured by irradiating ultraviolet rays to obtain a vertically aligned liquid crystal film layer with a thickness of 1.0 μm. As a result of measuring the optical phase difference of this sample (measuring light incident from perpendicular or oblique to the surface of the sample), the front phase phase difference was approximately 0, and it was confirmed that the phase difference increased as the incident angle of the measurement light increased. vertical orientation. The retardation in the thickness direction of the vertical alignment liquid crystal film layer is -100nm.

(elliptical polarizer)

On one side of the polarizer obtained in the reference example, a triacetyl cellulose (TAC) film with a thickness of 80 μm, a retardation in the front surface: 6 nm, and a retardation in the thickness direction: 60 nm was bonded with a polyvinyl alcohol-based adhesive to form a transparent protective layer. . On the other side of the polarizer, the absorption axis of the polarizer is perpendicular to the slow axis of the retardation film A by means of a polyvinyl alcohol-based adhesive. Retardation film B. Then, the ゼゼオノァ film was peeled off to obtain an elliptically polarizing plate.

Example 2

(retardation film A)

A norbornene-based unstretched film having a thickness of 100 μm (Aiton film manufactured by JSR Co., Ltd.) was uniaxially stretched to 1.4 times at 170°C. The obtained stretched film thickness: 70 μm, front phase difference: 180 nm. The obtained stretched film has positive refractive index anisotropy (nx>nynz) which has been uniaxially stretched.

(retardation film B)

In Example 1, except having made the thickness of the vertical alignment liquid crystal thin film layer into 0.5 micrometers, it carried out similarly to Example 1, and obtained the vertical alignment liquid crystal thin film layer. The retardation in the thickness direction of the vertical alignment liquid crystal film layer is -50nm.

(elliptical polarizer)

In Example 1, except having used what was obtained above as retardation film A and retardation film B, it carried out similarly to Example 1, and obtained the elliptically polarizing plate.

Example 3

(retardation film A)

A norbornene-based unstretched film with a thickness of 100 μm (Aiton film manufactured by JSR Co., Ltd.) was uniaxially stretched to 1.35 times at 175°C. The obtained stretched film thickness: 75 μm, front phase difference: 140 nm. The obtained stretched film has uniaxially stretched positive refractive index anisotropy (nx>nynz).

(retardation film B)

In Example 1, the vertical alignment liquid crystal thin film layer was obtained like Example 1 except having made the thickness of the vertical alignment liquid crystal thin film layer into 1.3 micrometers. The retardation in the thickness direction of the vertical alignment liquid crystal film layer is -130nm.

(elliptical polarizer)

In Example 1, except having used what was obtained above as retardation film A and retardation film B, it carried out similarly to Example 1, and obtained the elliptically polarizing plate.

Comparative example 1

On one side of the polarizer obtained in the reference example, a triacetyl cellulose (TAC) film with a thickness of 80 μm, a retardation in the front surface: 6 nm, and a retardation in the thickness direction: 60 nm was bonded with a polyvinyl alcohol-based adhesive to form a transparent protective layer. . On the other side of the polarizer, a triacetyl cellulose (TAC) film having a thickness of 80 μm, a front retardation of 6 nm, and a retardation in the thickness direction of 60 nm was bonded with a polyvinyl alcohol-based adhesive to obtain a polarizer.

Comparative example 2

On one side of the polarizer obtained in the reference example, a triacetyl cellulose (TAC) film with a thickness of 40 μm, a retardation in the front surface: 3 nm, and a retardation in the thickness direction: 40 nm was bonded with a polyvinyl alcohol-based adhesive to form a transparent protective layer. . On the other side of the polarizer, a triacetyl cellulose (TAC) film with a thickness of 40 μm, a front retardation of 3 nm, and a thickness direction retardation of 40 nm was bonded with a polyvinyl alcohol-based adhesive to obtain a polarizer.

Comparative example 3

(retardation film A')

At 175°C, a polycarbonate film with a thickness of 80 μm was uniaxially stretched to 1.3 times. The obtained stretched film thickness: 50 μm, front phase difference: 300 nm. The obtained stretched film has uniaxially stretched positive refractive index anisotropy (nx>nynz).

(retardation film B)

In Example 1, except having made the thickness of the vertical alignment liquid crystal thin film layer into 3.0 micrometers, it carried out similarly to Example 1, and obtained the vertical alignment liquid crystal thin film layer. The retardation in the thickness direction of the vertical alignment liquid crystal film layer is -300nm.

(elliptical polarizer)

In Example 1, an elliptically polarizing plate was obtained in the same manner as in Example 1, except that the retardation film A' and the retardation film B obtained above were used instead of the retardation film A.

(evaluate)

The following evaluations were performed on the elliptically polarizing plate or polarizing plate obtained above. The results are shown in Table 1.

(angle of view)

The elliptically polarizing plates obtained in Examples 1 to 3 were arranged on the viewing side of the liquid crystal cell in the IPS mode, as shown in FIG. 3 . As shown in FIG. 4 , the polarizing plates obtained in Comparative Examples 1 and 2 were arranged on the viewing side of the liquid crystal cell in the IPS mode. Instead of the elliptically polarizing plate used in Example 1, the elliptically polarizing plate obtained in Comparative Example 3 was used. On the other hand, the polarizing plate obtained in Comparative Example 1 was disposed on the incident side (backlight side).

The above-mentioned liquid crystal display device was made to display a white image and a black image, and the Y value in the XYZ display system in the direction of up and down, left and right, diagonal 45°-225°, and diagonal 135°-315° was measured using EZcontrast 160D manufactured by ELDIM, x value, y value. The angle at which the value of the contrast (Y value (white image)/Y value (black image)) at this time is 25 degrees or more is defined as the viewing angle.

(Unevenness caused by bonding stress)

The elliptically polarizing plate or polarizing plate (400 mm×300 mm) obtained above was bonded to an alkali glass using a roller using an acrylic adhesive (20 μm) to form a crossed Nicol prism. After the backlight was irradiated, unevenness due to stress after bonding was visually confirmed on the basis of the machine diagram.

○: Light leakage cannot be confirmed.

×: Light leakage can be confirmed.

(heating durability)

Using an acrylic adhesive (20 μm), use a roller (roller) to press-bond the elliptically polarizing plate or polarizing plate (300mm×200mm) obtained above on the alkali glass to make it into a crossed Nicol prism, and then use Autoclave at 50°C, 5 atmospheres, 15 minutes to remove air bubbles. Furthermore, after irradiating the backlight, the peripheral unevenness after 100-hour injection|throwing-in in the environment of 80 degreeC was visually confirmed based on the following reference|standard.

○: Light leakage cannot be confirmed.

×: Light leakage can be confirmed.

Table 1 Example 1 Example 2 Example 3 Comparative example 1 Comparative example 2 Comparative example 3 angle of view 70 70 65 40 40 30 uneven stress ○ ○ ○ ○ ○ x Heating Durability ○ ○ ○ ○ ○ x

Industrial availability

The elliptically polarizing plate of the present invention is suitable for image display devices such as liquid crystal display devices, organic EL (electroluminescence) display devices, and PDPs. In particular, the elliptically polarizing plate of the present invention is preferably used in an active matrix liquid crystal display device of a transverse electric field system (IPS mode).

Claims (9)

1. An elliptical polarizer, characterized in that, An optical film formed by laminating the retardation film A described below and the retardation film B described below, on one side of the polarizer such that the slow axis of the retardation film A is perpendicular to the absorption axis of the polarizer cascading, The retardation film A is composed of a thermoplastic polymer containing a cyclic polyolefin resin, and the direction in which the in-plane refractive index is the largest is defined as the X-axis, the direction perpendicular to the X-axis is defined as the Y-axis, and the thickness direction is defined as When the refractive index of the Z-axis and each axis direction is respectively set as nx, ny, nz, it has positive refractive index anisotropy with unidirectional orientation (nx>nynz); The retardation film B is fixed in a vertical orientation, and the direction in which the in-plane refractive index is the largest is set as the X axis, the direction perpendicular to the X axis is set as the Y axis, the thickness direction is set as the Z axis, and the directions of each axis are When the refractive indices are nx ₁ , ny ₁ , and nz ₁ , they have positive refractive index anisotropy (nz ₁ >nx ₁ ny ₁ ). 2. elliptically polarizing plate according to claim 1, is characterized in that, From the polarizer, the optical films were stacked in order of retardation film A and retardation film B. 3. elliptically polarizing plate according to claim 1, is characterized in that, The retardation film A is a film containing a norbornene-based resin. 4. elliptically polarizing plate according to claim 1, is characterized in that, The retardation in the thickness direction of the retardation film B: {((nx ₁ +ny ₁ )/2)-nz ₁ }×d (thickness: nm) is -500 nm to -10 nm. 5. elliptically polarizing plate according to claim 1, is characterized in that, The retardation film B is a film containing a side chain type liquid crystal polymer. 6. elliptically polarizing plate according to claim 1, is characterized in that, Retardation film A is a λ/4 plate. 7. An image display device, characterized in that, The elliptically polarizing plate according to any one of claims 1 to 6 is laminated. 8. A liquid crystal display device, characterized in that, The elliptically polarizing plate according to any one of claims 1 to 6 is laminated. 9. The liquid crystal display device according to claim 8, wherein: The driving mode is a transverse electric field method (IPS mode).

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