WO2009028428A1

WO2009028428A1 - Elliptic polarization plate and liquid crystal display device

Info

Publication number: WO2009028428A1
Application number: PCT/JP2008/065058
Authority: WO
Inventors: Yuji Takahashi; Satoru Ikeda; Tetsuya Uesaka
Original assignee: Nippon Oil Corporation
Priority date: 2007-08-31
Filing date: 2008-08-18
Publication date: 2009-03-05

Abstract

Provided is an elliptic polarization plate having excellent view angle improving effects. In the elliptic polarization plate, a polarization plate, a first optical anisotropic layer and a second optical anisotropic layer are laminated in this order. The first optical anisotropic layer satisfies inequalities of 0.8≤NZ1≤1.6 and 120≤Re1≤250. The layers are laminated so that the slow axis of the first optical anisotropic layer and the absorption axis of the polarization plate orthogonally intersect with each other. The phase difference of the second optical anisotropic layer within a surface with a wavelength of 550nm is 30-150nm. The second optical anisotropic layer is a liquid crystal film composed of a liquid crystalline polymer exhibiting optically positive uniaxial characteristic and has a fixed nematic hybrid orientation structure having a liquid crystal molecule average tilt angle of 5-50°. The orientation direction of the second optical anisotropic layer and the absorption axis of the polarization plate are laminated in parallel, and the elliptic polarization plate is used in a TN type liquid crystal display device by having the second optical anisotropic layer side on the liquid crystal cell side.

Description

Elliptical polarizing plate and liquid crystal display device

[Technical field]

The present invention relates to an elliptically polarizing plate including two optically anisotropic layers and a liquid crystal display device having excellent viewing angle characteristics in which the elliptically polarizing plate is disposed, and more particularly to a TN type liquid crystal display device. Light

[Background]

Currently used most often as a liquid crystal display (hereinafter also referred to as L C D)

A nematic liquid crystal having an alignment structure in which a helical axis is in the normal direction of the glass substrate between a pair of glass substrates on which transparent electrodes are formed, and the twist angle is about 90 degrees. A normally white (hereinafter also referred to as NW) mode sandwiched between a pair of linearly polarizing films arranged so that their absorption axes are orthogonal to each other. LCD (hereinafter also referred to as TN—LCD). In the NW mode TN-LCD, when no voltage is applied, the incident linearly polarized light is emitted by rotating 90 degrees due to the optical rotation of the liquid crystal cell, resulting in a white state. When a voltage is applied, the liquid crystal molecules Rises with respect to the glass substrate, the optical rotation disappears, and the incident linearly polarized light is emitted while maintaining this state, so that it becomes a black state. In addition, gradation display is performed by using the white state, the black state, and the intermediate state.

However, nematic liquid crystals used in LCDs have a rod-like molecular structure and a positive refractive index anisotropy with a large refractive index in the direction of the molecular axis, and the polarization state of light that passes obliquely through the LCD. The change is different from the normal direction of the LCD due to the phase difference due to the refractive index anisotropy of the liquid crystal. For this reason, when viewing the display from an angle deviating from the normal direction of the LCD, it shows viewing angle characteristics such as a decrease in contrast and gradation inversion that reverses the gradation display. The improvement of the viewing angle characteristics can be achieved mainly by improving the viewing angle characteristics in black display, that is, when a voltage is applied. Since the liquid crystal molecules are aligned in a state that is nearly perpendicular to the glass substrate when a voltage is applied, this state is referred to as a positive refractive index anisotropic body having an optical axis in the normal direction of the glass substrate. As a retardation film for compensating for this, a method using a retardation film having an optical axis in the normal direction of the film and having negative refractive index anisotropy has been reported (Patent Document 1, Patent Reference 2). However, in an actual LCD, even when voltage is applied, the liquid crystal molecules in the vicinity of the glass substrate remain tilted near the glass substrate due to the binding force of the alignment film on the substrate. In a retardation film having an optical axis in the normal direction of the film and having negative refractive index anisotropy, it is difficult to sufficiently compensate the polarization state caused by the liquid crystal cell.

In order to compensate for the liquid crystal molecules in such a tilted state, there is also a method using a disc-shaped liquid crystal film in which the optical axis is in a direction inclined from the normal direction of the film and has negative refractive index anisotropy. Have also been proposed (Patent Literature 3, Patent Literature 4). However, with these methods, although the compensation state for the liquid crystal cell in the voltage application state is improved, it is expensive to synthesize and film the disk-like liquid crystal molecules, and the applied voltage is lower, so the tilt is reduced. In the halftone display state where the liquid crystal part of the state increases and takes a more complicated alignment form, the compensation becomes incomplete, so the viewing angle of the display contrast is improved, but the gradation inversion phenomenon is improved. As a result, only incomplete viewing angle characteristics can be obtained.

As another method, the viewing angle characteristics can be improved by using a retardation plate having the same positive refractive index anisotropy as that of liquid crystal but having the optical axis inclined from the film normal direction. It has been proposed (Patent Document 5, Patent Document 6, Patent Document 7).

In these reports, the use of a retardation plate having a positive refractive index anisotropy and an optical axis inclined from the normal direction of the film suppresses gradation inversion of the liquid crystal cell. However, only the incomplete viewing angle characteristics have been obtained with respect to the viewing angle of the display contrast.

In Patent Document 8, as a liquid crystal display device combining a retardation film in which liquid crystal molecules having positive refractive index anisotropy are tilted and a uniaxial film, a polarizing plate tilted alignment film / uniaxial film TN liquid crystal cell 1 A liquid crystal display device comprising an axial film, a Z-oriented film, and a Z polarizing plate has been proposed. However, this configuration is not sufficient to completely compensate the viewing angle of the display contrast, and the viewing angle characteristics are only incomplete.

Thus, the optical compensator used to improve the viewing angle characteristics of TN-LCD However, there has not been found any device that can dramatically improve the total viewing angle characteristics including not only the display contrast but also the gradation inversion, and there is a need for further improvements.

(1) Patent Document 1: Japanese Patent Laid-Open No. 2-0 1 5 2 3 9

(2) Patent Document 2: Japanese Patent Laid-Open No. 3-10 3 8 2 3

(3) Patent Document 3: Japanese Patent Application Laid-Open No. Sho 6 3-2 3 9 4 2 1

(4) Patent Document 4: Japanese Patent Laid-Open No. 6-2 1 4 1 1 6

(5) Patent Document 5: Japanese Patent Laid-Open No. 5-0 80 3 2 3

(6) Patent Document 6: Japanese Patent Application Laid-Open No. 7-3 0 6 4 0 6

(7) Patent Document 7: International Publication No. 9 6/1 0 7 7 3 Pamphlet

(8) Patent Document 8: Japanese Patent Application Laid-Open No. 10-1 1 2 3 5 0 6

[Disclosure of the Invention]

In the present invention, when placed in a liquid crystal cell, an elliptically polarizing plate that can significantly improve the viewing angle characteristics of both contrast and gradation reversal, and by placing it, the contrast is high and the viewing angle dependency is low. An object is to provide a liquid crystal display device. As a result of intensive studies by the present inventors in view of the powerful situation, the optically anisotropic layer having an NZ coefficient of 0.8 to 1.6 and a liquid crystalline polymer exhibiting optically positive uniaxiality are substantially used. An optical compensation layer formed by combining the two optically anisotropic layers having a structure in which the nematic hybrid alignment formed by the liquid crystalline polymer in the liquid crystal state is fixed. It has been found that the viewing angle characteristics of both display contrast and gradation reversal can be greatly improved by laminating and using the films in a specific order with respect to the polarizing plate and the liquid crystal cell, and the present invention has been completed.

That is, the means for solving the above problems are as follows.

[1] An elliptically polarizing plate in which a polarizing plate, a first optically anisotropic layer, and a second optically anisotropic layer are laminated in this order, wherein the first optically anisotropic layer is: [1] and

[2], and the slow axis of the first optically anisotropic layer and the absorption axis of the polarizing plate are laminated so that the second optically anisotropic layer has a wavelength The in-plane retardation value at 5 50 nm is 30 to 15 O nm, and the average tilt angle of the liquid crystal molecules is 5 ° to 50 °. Nematic hybrids that are The second optical anisotropy is a liquid crystal film in which the alignment structure is fixed, and is laminated so that the alignment direction of the second optically anisotropic layer and the absorption axis of the polarizing plate are parallel to each other. An elliptically polarizing plate that is used in a twisted nematic (TN) type liquid crystal display device such that the layer side is on the liquid crystal cell side.

[1] 0. 8≤N Z 1≤ 1. 6

[2] 1 20≤R e l≤ 250

(Where NZ 1 is NZ 1 = (n 1-nz 1) / (nxl — nyl) and R el is defined by R el = (nxl — nyl) X d 1 [nm] D 1 is the thickness [nm] of the first optical anisotropic layer, and nxl and ny 1 are for light with a wavelength of 550 nm. The main refractive index in the plane of the first optical anisotropic layer, nz 1 is the main refractive index in the thickness direction for light with a wavelength of 550 nm, and nxl> nyl.

[2] The elliptically polarizing plate according to [1], wherein the first optically anisotropic layer is made of a thermoplastic polymer containing a cyclic polyolefin resin.

[3] The elliptically polarizing plate according to [1], wherein the first optically anisotropic layer is made of a thermoplastic polymer containing a cellulose resin.

[4] A TN liquid crystal display device comprising at least one elliptically polarizing plate as described in [1] above.

[5] From the viewing side, the first polarizing plate, the first optically anisotropic layer, the second optically anisotropic layer, the TN liquid crystal cell, the second optically anisotropic layer, and the first optically anisotropic layer A TN liquid crystal display device in which an isotropic layer, a second polarizing plate, and a backlight are arranged in this order, wherein the first optically anisotropic layer includes the following [1] and [2]: The slow axis of the first optical anisotropy layer on the viewer side and the absorption axis of the first polarizing plate are perpendicular to each other, and the slow axis of the first optical anisotropic layer on the backlight side and the second axis The second optically anisotropic layer has an in-plane retardation value of 30 to 150 nm at a wavelength of 550 nm, and is optically laminated. Is a liquid crystal film in which a nematic hybrid alignment structure in which the average tilt angle of the liquid crystal molecules is 5 ° to 50 ° is fixed to the liquid crystal polymer exhibiting positive uniaxiality, and the second light on the viewer side The orientation direction of the anisotropic layer is parallel to the absorption axis of the first polarizing plate, and the orientation direction of the second optical anisotropic layer on the backlight side is parallel to the absorption axis of the second polarizing plate. TN type liquid crystal characterized by being laminated Display device.

[1] 0. 8≤N Z 1≤ 1. 6

[2] 1 20≤R e l≤ 250

(Where NZ 1 is NZ 1 = (nx 1-nz 1) Z (nx 1-ny 1) and R el is R el = (nx 1-ny 1) X d 1 [nm Where d 1 is the thickness [nm] of the first optical anisotropic layer, and nxl and ny 1 are wavelengths 550 The main refractive index in the plane of the first optical anisotropic layer for nm light, nz 1 is the main refractive index in the thickness direction for light with a wavelength of 550 nm, and nxl> nyl.

[6] The TN liquid crystal display device according to the above [4] or [5], wherein the first optically anisotropic layer is made of a thermoplastic polymer containing a cyclic polyolefin resin.

[7] The TN liquid crystal display device according to [4] or [5], wherein the first optically anisotropic layer is made of a thermoplastic polymer containing a cellulose resin.

[8] When no voltage is applied, the alignment direction of the liquid crystal molecules on the cell substrate on the viewing side in the TN liquid crystal cell is the nematic hybrid alignment structure of the second optically anisotropic layer on the adjacent viewing side. The alignment direction of the liquid crystal molecules on the cell substrate on the backlight side is the second optical anisotropic layer on the backlight side. The TN type according to any one of the above [4] to [7], wherein the liquid crystal film is fixed in an antiparallel relationship with the alignment direction of the liquid crystal film in which the nematic hybrid alignment structure is fixed. Liquid crystal display device.

[The invention's effect]

According to the present invention, when arranged in a liquid crystal cell, an elliptically polarizing plate that can greatly improve the viewing angle characteristics of both contrast and gradation reversal, and by placing it, the contrast is high and the viewing angle depends. A liquid crystal display device with less property can be provided.

[Best Mode for Carrying Out the Invention]

Hereinafter, the present invention will be described in detail. The elliptically polarizing plate of the present invention includes a translucent protective film, a polarizing element, a first optically anisotropic layer having an NZ coefficient of 0.8 to 1.6, and an optically high uniaxial liquid crystallinity. Consists of at least a second optically anisotropic layer composed of a liquid crystal film in which molecules are fixed in a nematic hybrid alignment structure

The elliptically polarizing plate of the present invention will be described with reference to FIG. As shown in FIG. 1, the elliptically polarizing plate of the present invention has a structure in which a polarizing plate, a first optically anisotropic layer, and a second optically anisotropic layer are laminated in this order. Here, the polarizing plate may have a structure having a translucent protective film on both sides of the polarizing element or a structure having a translucent protective film only on one side of the polarizing element. In the case of a structure having a translucent protective film only on one side, the first optically anisotropic layer also serves as a protective film for the polarizing element. A translucent protective film may be included between the polarizing element and the first optically anisotropic layer, but it is preferable to directly provide the first optically anisotropic layer from the viewpoint of durability and thickness. The elliptically polarizing plate of the present invention is laminated so that the slow axis of the first optical anisotropic layer and the absorption axis of the polarizing plate are perpendicular to each other, and the slow phase of the second optical anisotropic layer is The axes are laminated so that the absorption axis of the polarizing plate is parallel.

In the elliptically polarizing plate shown in Fig. 1, the order of lamination of the optically anisotropic layer with respect to the polarizing plate is polarized as shown in Fig. 1 because it suppresses the decrease in contrast and color shift when mounted on a liquid crystal display device. It is preferable to laminate the first optically anisotropic layer and the second optically anisotropic layer in this order from the plate side. In FIG. 1, the polarizing plate, the first optically anisotropic layer, and the second optically anisotropic layer are laminated via an adhesive layer or an adhesive layer. The pressure-sensitive adhesive layer or the adhesive layer may be a single layer, or may be a superposed form of two or more layers. Hereafter, the structural member used for this invention is demonstrated in order.

First, the polarizing plate used in the present invention has a translucent protective film on both sides or one side of the polarizing element.

The polarizing element is not particularly limited, and various types can be used. Examples of the polarizing element include hydrophilic polymer films such as polybulal alcohol film, partially formalized polybulal alcohol film, and ethylene / vinyl acetate copolymer partially saponified film. Uniaxially stretched by adsorbing dichroic substances such as reactive dyes, dehydrated polybulal alcohol and dehydrochlorinated polychlorinated blu And the like, and the like. Among these, those obtained by stretching a polyvinyl alcohol film and adsorbing and orienting a dichroic material (iodine, dye) are preferably used. The thickness of the polarizing element is not particularly limited, but is generally about 5 to 80 μππι.

A polarizing element in which a polyvinyl alcohol film is dyed with silicon and uniaxially stretched is prepared by, for example, dyeing polybulal alcohol in an aqueous solution of silicon and stretching it 3 to 7 times the original length. can do. If necessary, it can be immersed in an aqueous solution of boric acid or potassium oxalate. Furthermore, if necessary, the polybulal alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, non-uniformity such as uneven dyeing can be achieved by swelling the poly alcohol alcohol film. There is also an effect to prevent this. Stretching may be performed after dyeing with iodine, or may be performed while dyeing, or may be performed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

A light-transmitting protective film is provided on both sides or one side of the polarizing element. The light-transmitting protective film is usually preferably one that is excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, isotropic properties, and the like. Examples of the material for the translucent protective film include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, senorelose polymers such as dicetinoresenorelose and triacetinoresenorelose, and polymethyl methacrylate. Examples include acryl-based polymers, styrene-based polymers such as polystyrene acrylonitrile, styrene copolymers (AS resins), and polycarbonate-based polymers. In addition, cyclic polyolefins having a cycloalkane structure or norbornene structure, polyolefin polymers such as polyethylene, polypropylene, ethylene propylene copolymer, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamides, imi Polymer, sulfone polymer, polyether sulfone polymer, polyetheretherketone polymer, polyphenylene norfide polymer, vinylenoreconolole polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer Rimmer, polyoxymethylene polymer, epoxy polymer, or Limer blends are examples of polymers that form translucent protective films. In addition, acrylic, urethane, acrylic urethane, epoxy, silicone, and other thermosetting or ultraviolet curable resins can be used.

A translucent protective film that can be particularly preferably used in terms of flatness, polarization characteristics, durability, and the like is a triacetyl cellulose film and a cyclic polyolefin having a norbornene structure. The thickness of the protective film can be determined as appropriate, but is generally about 10 to 500 / zm from the viewpoints of workability such as strength and handleability and thin layer properties. 10 to 300 μm is particularly preferable, and 10 to 200 m is more preferable. Moreover, it is preferable that a translucent protective film has as little color as possible. Therefore, R th = [(nx + ny) / 2-nz] X d (where nx and ny are the main refractive index in the film plane, nz is the refractive index in the film thickness direction, and d is the film thickness) A translucent protective film having a retardation value in the film thickness direction represented by the formula of 10 nm to +100 nm is preferably used. By using a film having such a thickness direction retardation value (R th) of −10 nm to about 100 nm, the coloring (optical coloring) of the polarizing plate caused by the translucent protective film can be substantially reduced. Can be resolved. The thickness direction retardation value (R t h) is more preferably 10 nm to 10 70 nm, especially 0 η π! ~ +50 nm is preferred. Further, the in-plane retardation value represented by Re = (nx-ny) Xd is preferably 20 nm or less, more preferably 10 nm or less, and more preferably closer to 0 nm.

The polarizing element and the translucent protective film are usually in close contact with each other through an aqueous adhesive or the like. Examples of the water-based adhesive include polybulal alcohol-based adhesive, gelatin-based adhesive, vinyl-based latex, water-based polyurethane, water-based polyester, and the like. As the translucent protective film, there can be used a hard coat layer, an antireflection treatment, an anti-sticking treatment, or a treatment intended for diffusion or anti-glare.

Hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate. For example, a light-cured cured film with an appropriate UV curable resin such as acrylic or silicone is used to transmit light. It can be formed by a method of adding to the surface of the protective film. Antireflection treatment is aimed at preventing reflection of external light on the surface of the polarizing plate. It can be achieved by forming an antireflection film or the like according to the conventional method. In addition, the anti-sticking treatment is performed for the purpose of preventing adhesion between adjacent layers. Anti-glare treatment is applied to prevent the external light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by the sand plast method or embossing method. It can be formed by providing a fine concavo-convex structure on the surface of the translucent protective film by an appropriate method such as a method or a compounding method of transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle diameter of 0.5 to 50 / ί. Transparent fine particles such as inorganic fine particles that may be conductive and organic fine particles composed of a crosslinked or uncrosslinked polymer are used. In the case of forming a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight with respect to 100 parts by weight of the transparent resin forming the surface fine uneven structure, and 5 to 25 Part by weight is preferred. The anti-glare layer may also serve as a diffusion layer (such as a viewing angle expansion function) for diffusing the light transmitted through the polarizing plate to expand the viewing angle. The antireflection layer, the anti-sticking layer, the diffusion layer, the antiglare layer, etc. can be provided on the transparent protective film itself, or can be provided separately from the transparent protective layer as an optical layer. it can.

The first optically anisotropic layer used in the present invention is not particularly limited as long as it has excellent transparency and uniformity, but a polymer stretched film or an optical compensation film made of liquid crystal can be preferably used. Examples of the stretched polymer film include a uniaxial or biaxial retardation film composed of a cellulose-based, polycarbonate-based, polyarylate-based, polysulfone-based, polyacrylic-based, polyethersulfone-based, or cyclic olefin-based polymer. it can. The first optically anisotropic layer exemplified here may be composed only of a polymer stretched film, may be composed only of an optical compensation film made of liquid crystal, or is composed of a polymer stretched film and liquid crystal. Both optical compensation films can be used together. Of these, cyclic olefin-based celluloses are preferable in terms of cost uniformity, film uniformity, and low birefringence wavelength dispersion characteristics, thereby suppressing color modulation of image quality. In addition, as the optical compensation film made of liquid crystal, various liquid crystalline polymer compounds exhibiting liquid crystallinity of main chain type and side chain type, for example, liquid crystalline polyester, liquid crystalline polycarbonate, liquid crystalline polyacrylate, etc. And optical compensation films composed of 'low molecular weight liquid crystals having a reactive group that can be increased in molecular weight by cross-linking after orientation, etc., and these can be formed on a transparent support substrate even by a self-supporting single film. It may be done.

In the present invention, the retardation value Re1 of the first optically anisotropic layer at a wavelength of 550 nm is adjusted to 120 to 250 nm. Here, Re1 is an in-plane retardation value of the first optical anisotropic layer defined by Re1 = (nxl−ny1) Xd1 [nm]. d 1 is the thickness of the first optically anisotropic layer [nm], 1 1 and 117 1 are the main refractive indices in the plane of the first optically anisotropic layer for light having a wavelength of 550 nm, and nx 1> nyl. If the value of Re1 is greater than 250 nm or less than 120 nm, the viewing angle improvement effect may be poor.

The NZ coefficient NZ 1 of the first optically anisotropic layer is adjusted to 0.8 to 1.6. Particularly preferred is 1.0 to 1.4. Here, NZ 1 is NZ 1 = (n x l—n z 1) / (n x 1 -ny 1). nxl and ny 1 are the main refractive indices in the plane of the first optical anisotropic layer for light with a wavelength of 550 nm, nz 1 is the main refractive index in the thickness direction for light with a wavelength of 550 nm, and nxl> nyl. If the value of N Z 1 is greater than 1.6 or less than 0.8, the viewing angle improvement effect may be poor.

The first optically anisotropic layer is usually laminated on the opposite side of the polarizing element on which one side of the transparent protective film is laminated (bonded). Although a translucent protective film may be included between the polarizing element and the first optically anisotropic layer, it is preferable to directly provide the first optically anisotropic layer from the viewpoint of durability and thickness.

The second optically anisotropic layer used in the present invention is a liquid crystalline polymer that exhibits optically positive uniaxiality, specifically, a liquid crystalline polymer that exhibits optically positive uniaxiality, or at least An optically positive uniaxial liquid crystalline polymer composition containing one kind of the liquid crystalline polymer compound, and the liquid crystalline polymer compound or the liquid crystalline polymer composition formed in a liquid crystal state. This is a layer including at least a liquid crystal film in which a nematic hybrid alignment structure having an average tilt angle of 5 to 50 degrees is fixed.

The nematic hybrid alignment referred to in the present invention refers to an alignment form in which liquid crystal molecules are nematically aligned, and the angle between the director of the liquid crystal molecules and the film plane at this time is different between the upper surface and the lower surface of the film. Therefore, the vicinity of the upper interface and the lower interface Since the angle formed by the director and the film plane is different in the vicinity, it can be said that the angle continuously changes between the upper surface and the lower surface of the film. Figure 2 shows a schematic diagram of the nematic hybrid alignment structure.

In addition, in the film in which the nematic hybrid alignment state is fixed, the directors of the liquid crystal molecules are oriented at different angles at all positions in the film thickness direction. Therefore, the film no longer has an optical axis when viewed as a film structure. Such a compensation film in which the nematic hybrid orientation is fixed is not optically equivalent between the upper surface and the lower surface of the film. Therefore, when it is arranged in the TN liquid crystal cell described above, the viewing angle expansion effect is slightly different depending on which side is arranged on the liquid crystal cell side. In the present invention, it is desirable that the surface having the larger angle formed by the director of the liquid crystal polymer and the plane of the film is disposed closest to the liquid crystal cell among the upper and lower surfaces of the compensation film.

The average tilt angle as used in the present invention means the average value of the angle formed by the director of the liquid crystal molecule and the film plane in the film thickness direction of the liquid crystal film. In the liquid crystal film to be used in the present invention, the angle formed by the director and the film plane near the one interface of the film is usually 20 to 90 degrees as an absolute value, preferably 40 to 90 degrees, more preferably Has an angle of 70 to 90 degrees, and on the opposite side of the surface, the absolute value is usually 0 to 20 degrees, preferably 0 to 10 degrees, and its average tilt angle Is usually 5 to 50 degrees as an absolute value, preferably 20 to 45 degrees, more preferably 25 to 45 degrees, and most preferably 35 to 45 degrees. If the average tilt angle is out of the above range, it is not desirable because it may cause a decrease in contrast when viewed from an oblique direction. The average tilt angle can be obtained by applying the crystal rotation method.

The liquid crystal film constituting the second optically anisotropic layer used in the present invention is optically as long as the nematic hybrid alignment state as described above is fixed and has a specific average tilt angle. It may be formed from any liquid crystal exhibiting positive uniaxiality. For example, a liquid crystal film obtained by forming a low-molecular liquid crystal substance in a nematic hybrid alignment in a liquid crystal state and then fixing by photocrosslinking or thermal crosslinking, or a liquid crystalline polymer in a nematic hybrid alignment in a liquid crystal state and then cooling. Using a liquid crystal film obtained by fixing the orientation Can. The liquid crystal film as used in the present invention does not ask whether the film itself exhibits liquid crystallinity, but means a film obtained by forming a liquid crystal substance such as a low molecular liquid crystal or a liquid crystalline polymer into a film. .

Next, the manufacturing method of the liquid crystal film used for this invention is demonstrated. The method for producing the liquid crystal film is not limited to these, but the liquid crystal compound or composition described above is developed on a substrate having orientation ability, and the liquid crystal compound or composition is oriented. Thereafter, the alignment state can be fixed by cooling or, if necessary, light irradiation and / or heat treatment. In some cases, the first optical anisotropic layer can be used as a substrate having orientation ability.

As a method of forming a liquid crystal layer by spreading a liquid crystal compound or composition on a substrate having orientation ability, a method of directly applying a liquid crystal compound or composition on a substrate in a molten state, a liquid crystal compound or a composition After applying the solution of the product on the substrate, the coating film is dried and the solvent is distilled off.

Regardless of the method of directly applying the liquid crystalline compound or composition, or the method of applying a solution, the coating method is not particularly limited as long as it is a method that ensures the uniformity of the coating film, and is publicly known. The method can be adopted. Examples include spin coating, die coating, curtain coating, dip coating, and roll coating.

In the method of applying a solution of a liquid crystal compound or composition, it is preferable to include a drying step for removing the solvent after the application. The drying step can be any known method without particular limitation as long as the uniformity of the coating film is maintained. For example, a method such as a heater (furnace) or hot air blowing is used.

Subsequently, the liquid crystal layer formed on the substrate is formed into a liquid crystal alignment by a method such as heat treatment, and is fixed by cooling and, if necessary, curing by light irradiation and Z or heat treatment. In the first heat treatment, the liquid crystal composition is heated to the temperature range where the liquid crystal composition is used, whereby the nematic hybrid alignment is performed by the self-alignment ability inherent in the liquid crystal composition. The conditions for the heat treatment cannot be generally stated because the optimum conditions and limit values vary depending on the liquid crystal phase behavior temperature (transition temperature) of the liquid crystal composition to be used, but are usually 10 ° C to 2500 ° C, preferably Heat treatment at a temperature in the range of 30 ° C. to 160 ° C., a temperature above the glass transition point (T g) of the liquid crystalline composition, and more preferably at a temperature higher than T g by 10 ° C. It is preferable to do this. If the temperature is too low, the alignment of the liquid crystal may not proceed sufficiently, and if the temperature is high, the substrate may be adversely affected. The heat treatment time is usually in the range of 3 seconds to 30 minutes, preferably 10 seconds to 20 minutes. If the heat treatment time is shorter than 3 seconds, the alignment of the liquid crystal may not be completed sufficiently, and if the heat treatment time exceeds 30 minutes, the productivity will be deteriorated. In addition, the substrate is not optically isotropic, or the substrate obtained is opaque in the wavelength range of use of the elliptical polarizing plate that is ultimately intended, or the substrate is too thick, which hinders actual use. In the case where there is a problem such as generation of a film, a form transferred from the form formed on the substrate to another substrate that does not become an obstacle in the intended use wavelength region or a stretched film having a retardation function can be used. As a transfer method, a known method can be employed. For example, as described in Japanese Patent Laid-Open No. 4-7570 17 or Japanese Patent Laid-Open No. 5-3 3 3 1 13, the liquid crystal layer is aligned via an adhesive or an adhesive which will be described later. Examples include a method of transferring only the liquid crystal layer by laminating a substrate used for alignment after laminating a substrate different from the substrate used in the above.

In addition, the film thickness of the elliptical polarizing plate obtained by laminating the liquid crystal films to exhibit a viewing angle improvement effect more suitable for the liquid crystal display device depends on the type of the target liquid crystal cell and various Since it depends on the optical parameters, it cannot be generally stated, but usually 0.2 μπ! To 10 μm, preferably 0.3 to 5 μm, particularly preferably 0.5 μπ! It is in the range of ~ 2 μπι. If the film thickness is less than 0.2 m, sufficient improvement (compensation) effect may not be obtained. If the film thickness exceeds 10 μπι, the display may be unnecessarily colored.

In addition, the in-plane apparent retardation value when viewed from the normal direction of the liquid crystal film is perpendicular to the refractive index in the direction parallel to the director (hereinafter referred to as _ne ) in the nematic hybrid oriented film. Refractive index in the direction (hereinafter referred to as no) Force S is different, and when the value obtained by subtracting no from no is the apparent birefringence, the apparent retardation value is the apparent birefringence And the absolute film thickness. This apparent retardation value can be easily obtained by polarization optical measurement such as ellipsometry. The apparent retardation value of the liquid crystal film used as the compensation element is usually 30 nm to 1550 nm, preferably for monochromatic light with a wavelength of 5500 nm, preferably 3 0 η π! ˜13 ° nm, particularly preferably 30 ηπ! It is in the range of ~ 100 nm. When the apparent retardation value is less than 30 nm, there is a possibility that a sufficient viewing angle expansion effect cannot be obtained. On the other hand, if it is larger than 150 nm, unnecessary coloration may occur in the liquid crystal display when viewed from an oblique direction. Next, the manufacturing method of the elliptically polarizing plate of this invention is demonstrated.

The elliptically polarizing plate of the present invention has a laminated form in the order of polarizing plate / first optical anisotropic layer / second optical anisotropic layer (the description of the pressure-sensitive adhesive layer or adhesive layer is omitted). The order of stacking does not matter.

For example, (1) a polarizing plate, a first optically anisotropic layer, and a second optically anisotropic layer are laminated in an appropriate order so as to have the above-described configuration. (2) (3) A laminate in which the first optical anisotropic layer and the second optical anisotropic layer are laminated in advance on the polarizing plate. Laminate, etc.

Adhesive layers and adhesive layers used for lamination (hereinafter sometimes referred to as "adhesives" together with adhesives and adhesives) are used as optically anisotropic layers. There is no particular limitation as long as it has sufficient adhesive strength against the optical properties and does not impair the optical properties of the optically anisotropic layer. For example, acrylic resin, methacrylic resin, silicone polymer, polyester , Polyurethane, Polyamide, Polyether, Epoxy resin system, Ethylene vinyl acetate copolymer system, Fluorine system, Rubber system, etc. Can do. In addition, various reactive types such as a thermosetting type and / or a photocurable type and an electron beam curable type can be exemplified. These adhesives include those having the function of a transparent protective layer for protecting the optically anisotropic layer. Among these, those having excellent optical transparency, such as acryl-based pressure-sensitive adhesives, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used. The adhesive layer can be formed by an appropriate method. As an example, for example, about 10 to 40% by weight of a viscous / adhesive obtained by dissolving or dispersing a base polymer or a composition thereof in a solvent composed of a single solvent or a mixture of appropriate solvents such as toluene and ethyl acetate. A solution is prepared, and the solution is applied by an appropriate development method such as a casting method or a coating method. Examples thereof include a method of directly attaching on the optically anisotropic layer, or a method of forming an adhesive layer on the separator according to the above and transferring it onto the optically anisotropic layer. In the adhesive / adhesive layer, for example, natural or synthetic resins, in particular, tackifier resins, fillers and pigments made of glass fiber, glass beads, metal powder, other inorganic powders, etc. It may contain additives such as colorants and antioxidants. Further, it may be an adhesive layer containing fine particles and exhibiting light diffusibility.

When the optically anisotropic layers are bonded to each other via an adhesive layer or a pressure-sensitive adhesive layer, the surface of the optically anisotropic layer is surface-treated to improve the adhesion to the adhesive layer or the pressure-sensitive adhesive layer. Can be improved. The surface treatment means is not particularly limited, and surface treatment methods such as corona discharge treatment, sputtering treatment, low-pressure UV irradiation, and plasma treatment that can maintain the transparency of the liquid crystal layer surface can be suitably employed. Among these surface treatment methods, corona discharge treatment is good.

The liquid crystal cell used in the present invention will be described. The TN-type liquid crystal cells used in the present invention are classified according to the drive system: simple matrix system, TFT (Thin Film Transistor) electrode using active elements as electrodes, MIM (Metal I Insulator Meter) It can be subdivided as in the active matrix method using electrodes and TFD (Thin Fi 1 m diode) electrodes. In the present invention, a remarkable effect can be exhibited for any driving type TN liquid crystal cell.

The TN type liquid crystal cell used in the present invention has an in-plane retardation represented by the product of the refractive index anisotropy (厶 n) of the liquid crystal in the liquid crystal cell and the thickness (d) of the liquid crystal layer of the liquid crystal cell. R e) Force Usually 250 η π! ˜520 nm, preferably 300 nm to 500 nm, particularly preferably 350 nm to 450 nm. If it is larger than 520 nm, the viewing angle improvement effect when combined with a compensation film described later may be poor, and the response speed may be slow. On the other hand, if it is smaller than 250 nm, when combined with the compensation film, the viewing angle may be improved, but the front brightness and contrast may be reduced.

The TN liquid crystal cell preferably gives a pretilt angle to the liquid crystal molecules in advance in order to reduce alignment defects of the liquid crystal molecules of the nematic liquid crystal. The pretilt angle is usually less than 5 °. In general, in the TN liquid crystal cell, the major axis of the nematic liquid crystal in the liquid crystal cell is twisted by about 90 ° between the upper and lower substrates. When no voltage is applied to the liquid crystal cell, the incident linearly polarized light is emitted with a 90 ° twist due to its optical rotation. When a voltage is applied to the liquid crystal cell, the long axes of the liquid crystal molecules are aligned in the direction of the electric field and the optical rotation disappears. Therefore, in order to sufficiently obtain this optical rotation effect, the twist angle of the TN type liquid crystal cell used in the present invention is usually 70 ° to 110 °, preferably 85 ° to 95. It is desirable that The twist direction of the liquid crystal molecules in the liquid crystal cell can be either left or right. A configuration of a TN type liquid crystal display device using the elliptically polarizing plate of the present invention will be described.

The TN type liquid crystal display device of the present invention is a liquid crystal display device having at least one elliptically polarizing plate of the present invention, but an arrangement having one each on both sides of the TN type liquid crystal cell is desirable. That is, from the viewing side, “ellipsoidal polarizing plate (polarizing plate first optical anisotropic layer second second optical anisotropic layer order) ZTN liquid crystal cell elliptic polarizing plate (second optical anisotropic layer Z The first optically anisotropic layer is arranged in the order of Z polarizing plate) Z back light. The angle between the pretilt direction of the liquid crystal layer in the liquid crystal cell and the tilt direction of the second optically anisotropic layer made of the liquid crystal film in which the nematic hybrid alignment structure is fixed is in the range of 150 ° to 180 °. More preferably, it is 160 to 180 degrees, and particularly preferably 17 to 180 degrees. If the angle between the two is smaller than 1550 degrees, there is a possibility that a sufficient viewing angle compensation effect cannot be obtained.

The angle formed between the slow axis of the first optical anisotropic layer and the tilt direction of the second optical anisotropic layer is preferably in the range of 60 ° to 90 °, more preferably 70 ° to 90 degrees, particularly preferably 80 degrees to 90 degrees. If the angle between the two is less than 60 degrees, there is a risk that a sufficient viewing angle compensation effect cannot be obtained.

Further, the angle formed by the absorption axis of the polarizing plate and the slow axis of the first optically anisotropic layer is preferably in the range of 60 ° to 90 °, more preferably 70 ° to 90 °, Particularly preferred is 80 to 90 degrees. If the angle between the two is less than 60 degrees, there is a risk that a sufficient viewing angle compensation effect cannot be obtained.

The liquid crystal display device of the present invention can be provided with other constituent members in addition to the constituent members described above. For example, mainly obtained by stretching a transparent plastic film or sheet Various types of retardation films, films with fixed liquid crystal orientation, light diffusion layers, backlights, light control films, light guide plates, prism sheets, color filters, etc. can be arranged. These can be appropriately selected from conventionally known ones and used.

[Example]

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The phase difference value (R e) in this example is a value at a wavelength of 550 nm unless otherwise specified.

In addition, the refractive index and retardation of each optical film are measured by using an automatic birefringence measuring device (manufactured by Oji Scientific Instruments Co., Ltd., automatic birefringence meter). KOBRA2 1 ADH). In addition, the viewing angle (equal contrast curve) of the liquid crystal display device was measured using a viewing angle measuring device (EZ corn tr a 160 R made by ELD IM).

(Polarizing element)

The polybulal alcohol film was immersed in warm water to swell, then dyed with an iodine / calorium oxalate aqueous solution, and then uniaxially stretched in an aqueous boric acid solution to obtain a polarizing element. These polarizing elements were examined for single transmittance, average transmittance, and orthogonal transmittance with a spectrophotometer. As a result, the transmittance was 43.5% and the polarization degree was 99.9%.

(First optical anisotropic layer)

A 100 μm-thick norbornene-based unstretched film (Jurton film made by JSR) was stretched biaxially and vertically at 230 ° C. The obtained stretched film had a thickness of ₈₀ μ ιη, retardation value R e 1 is approximately 220 nm, NZ coefficient NZ 1 1. was 2.

(Second optically anisotropic layer)

According to JP-A-6-347742, a second optical anisotropy comprising a liquid crystal film having a film thickness of 0.65 / m with a fixed nematic hybrid orientation having an average tilt angle of 44 degrees in the film thickness direction. A layer was made. The phase difference value was 70 nm.

(Ellipse polarizing plate) Triacetyl cellulose (TAC) film (40 / _ίπι, manufactured by Fuji Film Co., Ltd.) is immersed in a 2% by weight aqueous solution of hydroxylated hydrogen for 5 minutes at room temperature, subjected to test treatment, washed in running water, and dried. I let you. An experimental TAC film was bonded to one surface of the polarizing element obtained above using an acrylic adhesive to form a translucent protective layer. Adhering the first optically anisotropic layer to the other surface of the polarizing element via an adhesive layer so that the absorption axis of the polarizing element and the slow axis of the first optically anisotropic layer are orthogonal, Next, the second optically anisotropic layer was bonded via an adhesive so that the absorption axis of the polarizing element of the polarizing element and the slow axis of the second optically anisotropic layer were parallel, and an elliptically polarizing plate was attached. Obtained.

(Liquid crystal display device)

A conceptual diagram of a liquid crystal display device in which the elliptically polarizing plate obtained above is arranged will be described with reference to FIG. 3, and its axis configuration will be described with reference to FIG. A transparent electrode 3 made of a material with high transmittance such as ITO is provided on the substrate 1, and a counter electrode 4 made of a material with high transmittance such as ITO is provided on the substrate 2, and a transparent electrode A liquid crystal layer 5 made of a liquid crystal material exhibiting positive dielectric anisotropy is sandwiched between 3 and the counter electrode 4. On the opposite surface of the substrate 2 where the counter electrode 4 is formed, an elliptically polarizing plate 1 5 (second optically anisotropic layer 1 1, first optically anisotropic layer 1 2, polarizing element 7 and translucency A protective film 9) and an elliptically polarizing plate 1 6 (second optically anisotropic layer 1 3, first optically different layer) on the opposite side of the surface of the substrate 1 on which the transparent electrode 3 is formed. An anisotropic layer 14, a polarizing element 8, and a translucent protective film 10). A backlight 17 is provided on the back side of the translucent protective film 10.

The liquid crystal cell 6 used was ZLI-4792 (manufactured by Merck) as the liquid crystal material, and the liquid crystal layer thickness was 4. The pretilt angle at the substrate interface of the liquid crystal layer was 3 degrees, and the Re of the liquid crystal cell was approximately 4 15 nm. The absorption axis of the polarizing element, the slow axis of the first and second optically anisotropic layers, and the pretilt direction at both interfaces of the liquid crystal cell are shown in FIG.

Figure 5 shows the contrast ratio from all directions, with the contrast ratio of the transmittance ratio of white display 0V and black display 5V (white display) / (black display). The solid line shows a contrast ratio of 50. Concentric circles represent the same viewing angle and are drawn at intervals of 20 degrees. Therefore, the viewing angle of the outermost circle represents 80 degrees (hereinafter the same). Figure 5 shows that it has good viewing angle characteristics.

In Example 1, the retardation value R el of the first optical anisotropic layer is 240 nm, the NZ coefficient NZ 1 is 1.0, the average tilt angle of the second optical anisotropic layer is 37 degrees, A liquid crystal display device similar to that of Example 1 was produced, except that the retardation value was 80 nm. Figure 6 shows the contrast ratio from all directions, with the transmittance ratio of white display 0V and black display 5V (white display) Z (black display) as the contrast ratio.

Figure 6 shows that it has good viewing angle characteristics.

In Example 1, a 100 μm thick TAC film (manufactured by Koni Riki Co., Ltd.) was stretched biaxially and longitudinally at 160 ° C., thickness 50 μπι, retardation value A liquid crystal display device similar to that of Example 1 was prepared, except that Re 1 was approximately 220 nm and the NZ coefficient NZ 1 was 1.2.

Fig. 7 shows the contrast ratio from all directions, with the contrast ratio of the transmittance of white display 0V and black display 5V (white display) / (black display).

Figure 7 shows that it has good viewing angle characteristics.

In Example 1, the arrangement order of the first optical anisotropic layer 1 2 and the second optical anisotropic layer 1 1 is changed, and the first optical anisotropic layer 14 and the second optical anisotropy are further changed. A liquid crystal display device similar to that of Example 1 was produced except that the arrangement order of the layers 13 was changed. Figure 8 shows an outline of the liquid crystal display device. The pretilt directions of the polarizing element, the first and second optically anisotropic layers, and the liquid crystal cell interface are the same as in Example 1 (FIG. 4). Figure 9 shows the contrast ratio from all directions, with the contrast ratio of the transmittance ratio of white display 0V and black display 5V (white display) / (black display).

As for viewing angle characteristics, comparing Example 1 and Comparative Example 1, it can be seen from FIGS. 5 and 9 that Comparative Example 1 has poor viewing angle characteristics compared to Example 1. <Comparative Example 2>

A liquid crystal display device similar to that of Example 1 was produced, except that in Example 1, the first optically anisotropic layers 12 and 14 were omitted. An outline of the liquid crystal display device is shown in FIG.

Figure 11 shows the contrast ratio from all directions, with the contrast ratio of the transmittance of white display 0 V and black display 5 V (white display) / (black display).

As for the viewing angle characteristics, comparing Example 1 and Comparative Example 2, it can be seen from FIG. 5 and FIG. 11 that the viewing angle characteristics are greatly improved by using the first optically anisotropic layer. I understand. <Comparative Example 3>

A laminated structure was the same as that of Comparative Example 2, but liquid crystal display devices with different shaft configurations were produced. That is, the absorption axes of the polarizing elements 7 and 8, the tilt directions of the liquid crystal films 11 and 13 and the pretilt directions of both interfaces of the liquid crystal cell 6 were arranged under the conditions described in FIG. Figure 13 shows the contrast ratio from all directions, with the transmittance ratio of white display OV and black display 5 V (white display) Z (black display) as the contrast ratio.

Regarding viewing angle characteristics, comparing Example 1 and Comparative Example 3, it can be seen from FIG. 5 and FIG. 13 that the viewing angle characteristics are greatly improved by using the first optically anisotropic layer. I understand.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of the elliptically polarizing plate of the present invention.

FIG. 2 is a schematic diagram of the alignment structure of the liquid crystal film constituting the second optically anisotropic layer.

FIG. 3 is a cross-sectional view schematically showing the liquid crystal display device of Example 1.

FIG. 4 is a plan view showing the angular relationship between the absorption axis of the polarizing plate, the slow axis of the polymer stretched film, the tilt direction of the liquid crystal film, and the pretilt direction of the liquid crystal cell in Example 1.

FIG. 5 is a graph showing the contrast ratio when the liquid crystal display device in Example 1 is viewed from all directions. FIG. 6 is a graph showing the contrast ratio when the liquid crystal display device in Example 2 is viewed from all directions.

FIG. 7 is a graph showing the contrast ratio when the liquid crystal display device in Example 3 is viewed from all directions.

FIG. 8 is a cross-sectional view schematically showing the liquid crystal display device of Comparative Example 1.

FIG. 9 is a diagram showing the contrast ratio when the liquid crystal display device in Comparative Example 1 is viewed from all directions.

FIG. 10 is a cross-sectional view schematically showing the liquid crystal display devices of Comparative Example 2 and Comparative Example 3.

FIG. 11 is a diagram showing the contrast ratio when the liquid crystal display device in Comparative Example 2 is viewed from all directions.

FIG. 12 is a plan view showing the angular relationship among the absorption axis of the polarizing plate, the tilt direction of the liquid crystal film, and the pretilt direction of the liquid crystal cell in Comparative Example 3.

FIG. 13 is a diagram showing a contrast ratio when the liquid crystal display device in Comparative Example 3 is viewed from all directions.

(Explanation of symbols)

I, 2: substrate, 3: transparent electrode, 4: counter electrode, 5: liquid crystal layer, 6: liquid crystal cell, 7: first polarizing element, 8: second polarizing element, 9, 10: translucency Protective film

II, 1 3 _: second optically anisotropic layer, 1 2, 14: first optically anisotropic layer

1 5 and 1 6: Elliptical polarizer, 1 7: Knock light

[Industrial applicability]

The present invention provides an elliptically polarizing plate that can greatly improve the viewing angle characteristics of both contrast and gradation reversal. By disposing it in a liquid crystal cell, a liquid crystal display device with high contrast and less viewing angle dependency is provided. Industrial value is great because it can be provided.

Claims

The scope of the claims

1. An elliptically polarizing plate in which a polarizing plate, a first optical anisotropic layer, and a second optical anisotropic layer are laminated in this order, wherein the first optical anisotropic layer is: [1] and

Satisfying [2], and the slow axis of the first optical anisotropic layer and the absorption axis of the polarizing plate are laminated so that the second optical anisotropic layer has a wavelength A nematic liquid crystal polymer having an in-plane retardation value at 550 nm of 30 to 15 O nm and an optically positive uniaxial liquid crystal molecule with an average tilt angle of 5 ° to 50 °. The liquid crystal film has a hybrid alignment structure fixed, and is laminated so that the alignment direction of the second optical anisotropic layer and the absorption axis of the polarizing plate are parallel to each other. An elliptically polarizing plate characterized by being used in a twisted nematic (TN) type liquid crystal display device such that the isotropic layer side is the liquid crystal cell side.

[1] 0. 8≤NZ 1≤ 1. 6

[2] 1 20≤R e l≤ 250

(Here, NZ 1 is NZ 1 = (nxl—nzl) (nxl—nyl). Also, R el is the first defined by R el = (nxl—nyl) X d 1 [nm]. Is the in-plane retardation value of the optically anisotropic layer of 1. d 1 is the thickness [nm] of the first optically anisotropic layer, and nxl and ny 1 are the first for light of wavelength 550 nm. The main refractive index in the plane of the optically anisotropic layer, nz 1 is the main refractive index in the thickness direction for light with a wavelength of 550 nm, and nxl> nyl.

2. The elliptically polarizing plate according to claim 1, wherein the first optically anisotropic layer is made of a thermoplastic polymer containing a cyclic polyolefin resin.

3. The elliptically polarizing plate according to claim 1, wherein the first optically anisotropic layer is made of a thermoplastic polymer containing a cellulose resin.

4. A TN liquid crystal display device comprising at least one elliptically polarizing plate according to claim 1.

5. From the viewer side, first polarizing plate, first optical anisotropic layer, second optical anisotropic layer, TN liquid crystal cell, second optical anisotropic layer, first optical anisotropic A TN liquid crystal display device in which a conductive layer, a second polarizing plate, and a backlight are arranged in this order, wherein the first optical anisotropic layer satisfies the following [1] and [2] and is visually Side of the first optical The slow axis of the isotropic layer and the absorption axis of the first polarizing plate are orthogonal to each other, and the slow axis of the first optically anisotropic layer on the backlight side and the absorption axis of the second polarizing plate are orthogonal to each other. The second optically anisotropic layer has an in-plane retardation value of 30 to 150 nm at a wavelength of 550 nm, and is optically positive uniaxial liquid crystal A liquid crystal film in which a nematic hybrid alignment structure in which the average tilt angle of liquid crystal molecules is 5 ° to 50 ° is fixed, and the alignment direction of the second optical anisotropic layer on the viewer side It is laminated so that the absorption axis of the polarizing plate 1 is parallel, and the orientation direction of the second optical anisotropic layer on the backlight side is parallel to the absorption axis of the second polarizing plate. TN type liquid crystal display device.

[1] 0. 8≤NZ 1≤ 1. 6

[2] 1 20≤R e l≤ 250

(Here, NZ 1 is NZ 1 = (n X 1-nz 1) / (nxl— nyl). Also, R el is defined by R el = (nxl— nyl) X d 1 [nm] Where d 1 is the thickness [nm] of the first optical anisotropic layer, and nxl and ny 1 are light having a wavelength of 550 nm. The main refractive index in the plane of the first optical anisotropic layer with respect to, nz 1 is the main refractive index in the thickness direction for light with a wavelength of 550 nm, and nxl> nyl.

6. The TN type liquid crystal display device according to claim 4, wherein the first optically anisotropic layer is made of a thermoplastic polymer containing a cyclic polyolefin resin.

7. The TN type liquid crystal display device according to claim 4, wherein the first optically anisotropic layer is made of a thermoplastic polymer containing a cellulose resin.

8. When no voltage is applied, the alignment direction of the liquid crystal molecules on the cell substrate on the viewing side in the TN liquid crystal cell is fixed to the nematic hybrid alignment structure of the second optically anisotropic layer on the adjacent viewing side. The alignment direction of the liquid crystal molecules on the cell substrate on the backlight side is the nematic of the second optical anisotropic layer on the backlight side. 8. The TN liquid crystal display device according to claim 4, wherein the TN liquid crystal display device is disposed so as to have an antiparallel relationship with the alignment direction of the liquid crystal film in which the hybrid alignment structure is fixed.