JP5503985B2 - Liquid crystal display device with wide viewing angle circularly polarizing plate - Google Patents

Description

  The present invention relates to a liquid crystal panel and a liquid crystal display device having the liquid crystal panel.

  The liquid crystal display device market is rapidly expanding, and linearly polarized liquid crystal display devices for TV applications and linearly polarized liquid crystal display devices and circularly polarized liquid crystal display devices are widely used for mobile applications.

  Recently, there has been a demand for a large-sized liquid crystal display device with little reflection on the display surface even in a bright room or outdoors. In order to realize such a liquid crystal display device, it is necessary to suppress reflection on the liquid crystal panel using a circularly polarized light mode. However, when it is attempted to suppress reflection in the circular polarization mode, it is not easy to compensate the oblique viewing angle, and there is a problem that it cannot be accurately compensated as in the linear polarization mode. Specifically, there is a problem that light leaks in an oblique direction during display.

  Further, it is known that the contrast is improved by arranging the λ / 4 plate and the polarizer in a predetermined positional relationship (Patent Document 1).

JP 2009-37049 A

  The present invention has been made to solve the above-described conventional problems, and a main object of the present invention is to provide a liquid crystal display device in which light leakage in an oblique direction is suppressed in the circular polarization mode and the viewing angle is accurately compensated. There is.

  The present inventor has designed the phase difference of the compensation plate so that green light (550 nm) is absorbed by the polarizer on the viewing side when performing optical compensation in the oblique direction. Since the wavelength differs depending on the wavelength, the polarization state of green light and the polarization state of blue light (450 nm) just before entering the polarizer on the viewing side are different (coordinates on the Poincare sphere are different). The present inventors have found that the problem of blue light leakage can be solved by matching the phase difference chromatic dispersion of the liquid crystal cell and the phase difference chromatic dispersion of the λ / 4 plate, thereby completing the present invention.

That is, according to the present invention, a liquid crystal panel is provided. The liquid crystal panel includes a first polarizer, a first optical compensation layer that functions as a λ / 4 plate, a liquid crystal cell, a second optical compensation layer that functions as a λ / 4 plate, and nz>nx>. A third optical compensation layer having a refractive index relationship of ny and a second polarizer are provided in this order from the viewing side, and the retardation wavelength dispersion value (Re _cell [450] / Re _{cell of the} liquid crystal _cell). [550]) is α _cell, and the average retardation wavelength dispersion value (Re _{λ / 4} [450] / Re _{λ / 4} [550]) of the first optical compensation layer and the second optical compensation layer is α _{λ / 4} and was at the time, α λ _{/ 4 /} α _cell is 0.95 to 1.02.
In a preferred embodiment, the α _{λ / 4} is 0.9 to 1.05.
In a preferred embodiment, the α _cell is 0.9 to 1.02.
In a preferred embodiment, an angle formed between the absorption axis of the first polarizer and the slow axis of the first optical compensation layer is substantially 45 degrees or substantially 135 degrees.
In a preferred embodiment, an angle formed between the absorption axis of the second polarizer and the slow axis of the second optical compensation layer is substantially 45 degrees or substantially 135 degrees.
In a preferred embodiment, the absorption axis of the second polarizer and the slow axis of the third optical compensation layer are substantially parallel.
In a preferred embodiment, the Nz coefficient of the first optical compensation layer and the second optical compensation layer satisfies a relationship of 1.6 <Nz ≦ 2.4.
In a preferred embodiment, the Nz coefficient of the third optical compensation layer satisfies a relationship of −2 ≦ Nz ≦ −0.1.
In a preferred embodiment, the liquid crystal cell is a VA mode.
According to another aspect of the present invention, a liquid crystal display device is provided. The liquid crystal display device includes the liquid crystal panel.

  According to the present invention, it is possible to provide a liquid crystal display device in which light leakage in an oblique direction is suppressed in the circular polarization mode and the viewing angle is accurately compensated. Specifically, in the present invention, the relationship between the retardation wavelength dispersion of the liquid crystal cell and the retardation wavelength dispersion of the first and second optical compensation layers functioning as a λ / 4 plate is appropriately adjusted to The light leakage of blue light is suppressed by bringing the polarization state of the blue light on the Poincare sphere closer to the polarization state of the green light immediately before entering the polarizer. Thereby, the light leakage of the diagonal direction can be suppressed.

It is a schematic sectional drawing of the liquid crystal panel by preferable embodiment of this invention. It is a schematic sectional drawing explaining the orientation state of the liquid crystal molecule of the liquid crystal layer in a VA mode liquid crystal cell.

Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.
(Definition of terms and symbols)
The definitions of terms and symbols in this specification are as follows.
(1) Refractive index (nx, ny, nz)
“Nx” is the refractive index in the direction in which the in-plane refractive index is maximum (that is, the slow axis direction), “ny” is the refractive index in the direction perpendicular to the slow axis in the plane, and “nz” "Is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
The in-plane retardation (Re) refers to the in-plane retardation value of a layer (film) at 23 ° C. and a wavelength of 550 nm unless otherwise specified. Re is obtained by Re = (nx−ny) × d, where d (nm) is the thickness of the layer (film). In this specification, Re [λ] refers to the in-plane retardation of a layer (film) at 23 ° C. and a wavelength of λ nm.
(3) Thickness direction retardation (Rth)
Thickness direction retardation (Rth) is a retardation value in the thickness direction of a layer (film) at a wavelength of 550 nm unless otherwise specified. Rth is obtained by Rth = {(nx + ny) / 2−nz} × d, where d (nm) is the thickness of the layer (film). In this specification, when Rth [λ] is indicated, it means a phase difference in the thickness direction of a layer (film) at 23 ° C. and a wavelength λnm.
(4) Nz coefficient An Nz coefficient is calculated | required by Nz = (nx-nz) / (nx-ny).
(5) λ / 4 plate The λ / 4 plate is an electro-optic birefringent plate that serves to rotate the polarization plane of the light beam, and ¼ wavelength between linearly polarized light that vibrates in directions perpendicular to each other. It has the function which produces the optical path difference of. That is, it means that the phase between the ordinary ray component and the extraordinary ray component acts so as to be shifted by a quarter cycle and converts circularly polarized light into plane polarized light (or plane polarized light into circularly polarized light).

A. Overview of Liquid Crystal Panel FIG. 1 is a schematic cross-sectional view of a liquid crystal panel according to one embodiment of the present invention. In FIG. 1, a liquid crystal panel 100 includes a first polarizer 10, a first optical compensation layer 20 that functions as a λ / 4 plate, a liquid crystal cell 30, and a second optical compensation that functions as a λ / 4 plate. It has the layer 40, the 3rd optical compensation layer 50 which has the relationship of refractive index of nz>nx> ny, and the 2nd polarizer 60 in this order from the visual recognition side. Although not shown, a protective layer may be provided on the opposite side of the liquid crystal cell of the first polarizer 10 and the second polarizer 60 as necessary. Similarly, the liquid crystal cell side of the first polarizer 10 and the second polarizer 60, that is, between the first polarizer 10 and the first optical compensation layer 20 and between the second polarizer 60 and the third polarizer 60. A protective layer may be provided between the optical compensation layer 50 and the optical compensation layer 50. In the case where the first optical compensation layer or the third optical compensation layer can function as a protective layer for the first polarizer or the second polarizer, respectively, the protective layer on the liquid crystal cell side may not be provided. By not providing the protective layer on the liquid crystal cell side, it can contribute to thinning of the liquid crystal panel.

  The first polarizer and the first optical compensation layer are laminated so that the absorption axis and the slow axis define an arbitrary appropriate angle. The angle formed between the absorption axis of the first polarizer and the slow axis of the first optical compensation layer is preferably substantially 45 degrees or substantially 135 degrees. In this specification, “substantially 45 degrees” includes a range of 45 degrees ± 3.0 degrees, and preferably 45 degrees ± 1.0 degrees. Further, “substantially 135 degrees” includes a range of 135 degrees ± 3.0 degrees, preferably 135 degrees ± 1.0 degrees.

  The second polarizer and the second optical compensation layer are laminated so that the absorption axis and the slow axis define an arbitrary appropriate angle. The angle formed by the absorption axis of the second polarizer and the slow axis of the second optical compensation layer is preferably substantially 45 degrees or substantially 135 degrees.

  The second polarizer and the third optical compensation layer are laminated so that the absorption axis and the slow axis define an arbitrary appropriate angle. The absorption axis of the second polarizer and the slow axis of the third optical compensation layer are preferably substantially parallel. In this specification, “substantially parallel” includes a range of 0 ° ± 3.0 °, and preferably 0 ° ± 1.0 °.

  The first polarizer and the second polarizer are typically stacked so that their absorption axes are substantially orthogonal to each other. In the present specification, “substantially orthogonal” includes a range of 90 ° ± 3.0 °, preferably 90 ° ± 1.0 °.

In the liquid crystal panel of the present invention, the retardation wavelength dispersion value (Re _cell [450] / Re _cell [550]) of the liquid crystal cell is α _cell, and the first optical compensation layer and the second optical compensation layer When the average phase difference chromatic dispersion value (Re _{λ / 4} [450] / Re _{λ / 4} [550]) is α _{λ / 4} , α _{λ / 4} / α _cell is 0.95 to 1.02. , Preferably 0.95 to 1.01, and more preferably 0.95 to 1.00. Thus, the phase difference wavelength dispersion of the liquid crystal cell and the phase difference wavelength dispersion of the optical compensation layer functioning as a λ / 4 plate satisfy a predetermined relationship, so that the blue light just before entering the viewing-side polarizer can be obtained. The polarization state approaches the polarization state of green light, and thereby light leakage in an oblique direction can be suppressed. Here, the average retardation wavelength dispersion value (Re _{λ / 4} [450] / Re _{λ / 4} [550]) is the in-plane retardation Re ₁ [450] of the first optical compensation layer at 23 ° C. and a wavelength of 450 nm. And the in-plane retardation Re ₂ [450] of the _second optical compensation layer, the in-plane retardation Re ₁ [550] of the first optical compensation layer and the second optical at 23 ° C. and a wavelength of 550 nm. It is obtained as a ratio to the average value with the in-plane retardation Re ₂ [550] of the compensation layer. In this specification, the average value of the in-plane retardation Re ₁ [λ] of the first optical compensation layer and the in-plane retardation Re ₂ [λ] of the second optical compensation layer at 23 ° C. and the wavelength λ nm. Is represented as Re _{λ / 4} [λ]. Further, the retardation wavelength dispersion value α _cell of the liquid crystal _cell is a dispersion value of the retardation when measured from a polar angle of 40 degrees and an azimuth angle of 45 degrees in a state where no electric field is generated.

B. First Optical Compensation Layer The first optical compensation layer 20 functions as a λ / 4 plate. The in-plane retardation Re ₁ of the first optical compensation layer is preferably 80 to 200 nm, more preferably 100 to 180 nm, and particularly preferably 120 to 160 nm. The thickness direction retardation Rth ₁ of the first optical compensation layer is preferably 100 to 380 nm, more preferably 120 to 360 nm, and particularly preferably 150 to 340 nm. Preferably, the first optical compensation layer has a refractive index relationship of nx>ny> nz. The Nz coefficient of the first optical compensation layer preferably shows a relationship of 1.6 <Nz ≦ 2.4, and more preferably 1.8 ≦ Nz ≦ 2.4. By having such optical characteristics, the first optical compensation layer functions as a λ / 4 plate and can suitably perform optical compensation for the liquid crystal cell.

The phase difference chromatic dispersion of the first optical compensation layer preferably has a relationship of α ₁ = 0.9 to 1.05 when Re ₁ [450] / Re ₁ [550] is α ₁ , Preferably, a relationship of α ₁ = 0.92 to 1.05 is shown. By using the first optical compensation layer having such retardation wavelength dispersion in combination with a second optical compensation layer and a liquid crystal cell, which will be described later, light leakage in the oblique direction is suppressed in the circular polarization mode, and the viewing angle is reduced. Thus, a liquid crystal panel and a liquid crystal display device in which is accurately compensated can be obtained.

  The first optical compensation layer can be formed of any suitable material. Specific examples include stretched films of polymer films. The resin forming the polymer film is preferably a norbornene resin, a polycarbonate resin, a polyvinyl acetal resin, a cellulose resin, or the like because an optical compensation layer having the above optical characteristics can be suitably obtained. .

  The norbornene-based resin is a resin that is polymerized using a norbornene-based monomer as a polymerization unit. Examples of the norbornene-based monomer include norbornene and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl. 2-Norbornene, 5-ethylidene-2-norbornene, and the like, polar substituents such as halogens thereof; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene Substituents and polar group substituents such as halogen such as 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-oct Hydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene and the like; 3-pentamer of cyclopentadiene, for example, 4,9: 5,8-dimethano-3a, 4 4a, 5,8,8a, 9,9a-octahydro-1H-benzoin 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene and the like. It is done. The norbornene-based resin may be a copolymer of a norbornene-based monomer and another monomer.

  As the polycarbonate resin, an aromatic polycarbonate is preferably used. The aromatic polycarbonate can be typically obtained by a reaction between a carbonate precursor and an aromatic dihydric phenol compound. Specific examples of the carbonate precursor include phosgene, bischloroformate of dihydric phenols, diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, dinaphthyl carbonate and the like. Can be mentioned. Among these, phosgene and diphenyl carbonate are preferable. Specific examples of the aromatic dihydric phenol compound include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, and bis (4-hydroxyphenyl). ) Methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) butane, 2, 2-bis (4-hydroxy-3,5-dipropylphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethyl And cyclohexane. You may use these individually or in combination of 2 or more types. Preferably, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane are Used. In particular, it is preferable to use both 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane.

  Arbitrary appropriate methods can be employ | adopted as a preparation method of the said stretched film. Examples of the stretching method include lateral uniaxial stretching, fixed end biaxial stretching, and sequential biaxial stretching. A specific example of the fixed-end biaxial stretching includes a method of stretching a polymer film in the short direction (lateral direction) while running in the longitudinal direction. This method can be apparently lateral uniaxial stretching. The stretching temperature and the stretching ratio can be appropriately set according to the type of polymer film, desired optical properties, and the like. The thickness of the obtained stretched film is typically 20 to 100 μm, preferably 20 to 80 μm.

C. Second Optical Compensation Layer The second optical compensation layer 40 functions as a λ / 4 plate. Plane retardation Re ₂ of the second optical compensation layer is preferably 80 to 200 nm, more preferably 100 to 180 nm, particularly preferably 120 to 160 nm. Thickness direction retardation Rth ₂ of the second optical compensation layer is preferably 100～380Nm, more preferably 120～360Nm, particularly preferably 150～340Nm. Preferably, the second optical compensation layer has a refractive index relationship of nx>ny> nz. The Nz coefficient of the second optical compensation layer preferably shows a relationship of 1.6 <Nz ≦ 2.4, and more preferably 1.8 ≦ Nz ≦ 2.4. By having such optical characteristics, the second optical compensation layer functions as a λ / 4 plate and can suitably perform optical compensation for the liquid crystal cell.

The retardation wavelength dispersion of the second optical compensation layer preferably has a relationship of α ₂ = 0.9 to 1.05 when Re ₂ [450] / Re ₂ [550] is α ₂ , Preferably, a relationship of α ₂ = 0.92 to 1.05 is shown. By using the second optical compensation layer having such retardation wavelength dispersion in combination with the first optical compensation layer and a liquid crystal cell described later, light leakage in the oblique direction is suppressed in the circular polarization mode, and the field of view is reduced. A liquid crystal panel and a liquid crystal display device whose corners are accurately compensated can be obtained.

  The second optical compensation layer can be formed of any appropriate material. Specific examples include stretched films of polymer films. As the material for forming the polymer film and the method for producing the stretched film, the same material and method for producing the first optical compensation layer can be adopted. In one preferable embodiment, the second optical compensation layer can be obtained by using the same forming material and manufacturing method as the first optical compensation layer. In this case, the second optical compensation layer may have the same optical characteristics as the first optical compensation layer.

D. Third Optical Compensation Layer The third optical compensation layer 50 has a refractive index relationship of nz>nx> ny. The in-plane retardation Re ₃ of the third optical compensation layer is preferably 30 to 200 nm, more preferably 45 to 180 nm, and particularly preferably 60 to 150 nm. The thickness direction retardation Rth ₃ of the third optical compensation layer is preferably −300 to −10 nm, more preferably −250 to −20 nm, and particularly preferably −200 to −50 nm. The Nz coefficient of the third optical compensation layer preferably shows a relationship of −2 ≦ Nz ≦ −0.1, more preferably −1.5 ≦ Nz ≦ −0.1. By using the third optical compensation layer having such a phase difference, light leakage in the oblique direction of the polarizer can be suitably compensated.

As the third optical compensation layer, for example, a retardation plate described in JP2009-37049A can be used. Specifically, the third optical compensation layer can be typically formed of a material having a negative intrinsic birefringence value (Δn ⁰ ). Here, the intrinsic birefringence value Δn ⁰ is a value calculated by the equation (1). In the formula, [pi is circle ratio, N is the Avogadro's number, D is the density, M is the molecular weight, n _a is the average refractive index, alpha _a molecular chain axis direction of the polarizability of the polymer, alpha _b polymer The polarizability in the direction perpendicular to the molecular chain axis.
Δn ⁰ = (2π / 9) (N · D / M) [(n _a +2) ² / n _a ] (α _a −α _b ) (1)

  Examples of the material having a negative intrinsic birefringence value include a vinyl aromatic polymer. Examples of the vinyl aromatic polymer include polystyrene, styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, and p-carboxystyrene. , Vinyl aromatic monomers such as p-phenylstyrene, ethylene, propylene, butadiene, isoprene, (meth) acrylonitrile, α-chloroacrylonitrile, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) Examples thereof include copolymers with other monomers such as acrylic acid, maleic anhydride and vinyl acetate. Among these, polystyrene or a copolymer of styrene and maleic anhydride can be suitably used.

  For materials with a negative intrinsic birefringence value, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, a dispersant, a chlorine scavenger, a flame retardant, and a crystallization as necessary. Nucleating agent, antiblocking agent, antifogging agent, release agent, pigment, organic or inorganic filler, neutralizing agent, lubricant, decomposition agent, metal deactivator, antifouling agent, antibacterial agent and other resins, Known additives such as thermoplastic elastomers can be added as long as the effects of the invention are not impaired.

  Any appropriate method can be adopted as a method for producing the third optical compensation layer. For example, on both sides of a material having a negative intrinsic birefringence value, a multilayer structure in which other materials are laminated via an adhesive resin layer is formed by coextrusion, and the resulting multilayer structure is biaxially stretched. It can be obtained by heat treatment as necessary. A material having a positive intrinsic birefringence value can be used as long as the intrinsic birefringence value of the multilayer structure is negative. Even if the material has a low intrinsic birefringence value that is difficult to stretch by itself and has a low strength, it can be stretched by forming a multilayer structure in which other materials having a low glass transition temperature are laminated on both sides, The third optical compensation layer can be formed with high productivity at a temperature at which birefringence easily develops without breaking.

  The thickness of the third optical compensation layer can be appropriately set so as to obtain a desired in-plane retardation and thickness direction retardation. The thickness is typically 20 μm to 200 μm, preferably 20 μm to 160 μm, and more preferably 20 μm to 150 μm.

E. Liquid Crystal Cell The liquid crystal cell 30 includes a pair of substrates 31, 31 ′ and a liquid crystal layer 32 as a display medium sandwiched between the substrates 31, 31 ′. One substrate (color filter substrate) 31 is provided with a color filter and a black matrix (both not shown). On the other substrate (active matrix substrate) 31 ', a switching element (typically TFT) (not shown) for controlling the electro-optical characteristics of the liquid crystal and a scanning line (not shown) for supplying a gate signal to this switching element. ) And a signal line (not shown) for supplying a source signal, and a pixel electrode (not shown). The color filter may be provided on the active matrix substrate 31 ′ side. A distance (cell gap) between the substrates 31 and 31 'is controlled by a spacer (not shown). For example, an alignment film (not shown) made of polyimide is provided on the side of the substrates 31, 31 ′ in contact with the liquid crystal layer 32.

  Any appropriate drive mode can be adopted as the drive mode of the liquid crystal cell. The VA mode is preferable. FIG. 2 is a schematic cross-sectional view illustrating the alignment state of liquid crystal molecules in the VA mode. As shown in FIG. 2A, when no voltage is applied, the liquid crystal molecules are aligned substantially perpendicular (normal direction) to the surfaces of the substrates 31 and 31 '. Here, “substantially perpendicular” includes the case where the alignment vector of the liquid crystal molecules is tilted with respect to the normal direction, that is, the case where the liquid crystal molecules have a tilt angle. The tilt angle (angle from the normal line) is preferably 10 ° or less, more preferably 5 ° or less, and particularly preferably 1 ° or less. By having a tilt angle in such a range, the contrast can be excellent. In addition, moving image display characteristics can be improved. Such substantially vertical alignment can be realized, for example, by arranging a nematic liquid crystal having negative dielectric anisotropy between substrates on which a vertical alignment film (not shown) is formed. When light is incident from the surface of one substrate 31 ′ in such a state, the linearly polarized light that has passed through the second polarizer 60 and entered the liquid crystal layer 32 is liquid crystal molecules that are substantially vertically aligned. Proceed along the direction of the long axis. Since substantially no birefringence occurs in the major axis direction of the liquid crystal molecules, the incident light travels without changing the polarization direction and is absorbed by the first polarizer 10 having a polarization axis orthogonal to the second polarizer 60. The This provides a dark display when no voltage is applied (normally black mode). As shown in FIG. 2B, when a voltage is applied between the electrodes, the major axis of the liquid crystal molecules is aligned parallel to the substrate surface. The liquid crystal molecules in this state exhibit birefringence with respect to linearly polarized light that has entered the liquid crystal layer 32 through the second polarizer 60, and the polarization state of the incident light changes according to the inclination of the liquid crystal molecules. To do. Light that passes through the liquid crystal layer when a predetermined maximum voltage is applied becomes, for example, linearly polarized light whose polarization direction is rotated by 90 °, and therefore, the light is transmitted through the first polarizer 10 to obtain a bright display. When the voltage is not applied again, the display can be returned to the dark state by the orientation regulating force. Further, gradation display can be performed by changing the intensity of transmitted light from the first polarizer 10 by changing the applied voltage to control the inclination of the liquid crystal molecules.

Retardation wavelength dispersion of the liquid crystal _cell, the _{Re cell [450] / Re cell} [550] when the alpha _cell, preferably show a relationship between the alpha _cell = 0.9 to 1.02, more preferably alpha _cell = 0.92 to 1.02. By using the liquid crystal cell having such retardation wavelength dispersion and the first optical compensation layer and the second optical compensation layer functioning as the λ / 4 plate in combination, light in an oblique direction in the circular polarization mode is used. A liquid crystal panel and a liquid crystal display device in which leakage is suppressed and the viewing angle is accurately compensated can be obtained. The retardation wavelength dispersion of the liquid crystal cell can be adjusted, for example, by adjusting the cell gap by changing the type of liquid crystal molecules used and the thickness of the RGB color filter.

F. Polarizer Any appropriate polarizer may be adopted as the first polarizer 10 and the second polarizer 60 depending on the purpose. For example, dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product. Among these, a polarizer obtained by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol film and uniaxially stretching is particularly preferable because of its high polarization dichroic ratio. The thickness of these polarizers is not particularly limited, but is generally about 1 to 80 μm.

  A polarizer uniaxially stretched by adsorbing iodine to a polyvinyl alcohol film can be produced by, for example, dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. . If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, or may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing.

  By washing the polyvinyl alcohol film with water, not only can the surface of the polyvinyl alcohol film be cleaned and the anti-blocking agent can be washed, but also the effect of preventing unevenness such as uneven dyeing can be obtained by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

G. Protective layer The protective layer is formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of the material as the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based materials. And transparent resins such as polystyrene, polynorbornene, polyolefin, (meth) acryl, and acetate. Further, thermosetting resins such as (meth) acrylic, urethane-based, (meth) acrylurethane-based, epoxy-based, and silicone-based or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Moreover, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the resin composition.

  When a protective layer is provided on the liquid crystal cell side of the polarizer, the protective layer (inner protective layer) is preferably optically isotropic. Specifically, the thickness direction retardation Rth [550] of the inner protective layer is preferably −20 nm to +20 nm, more preferably −10 nm to +10 nm, particularly preferably −6 nm to +6 nm, and most preferably −3 nm to +3 nm. It is. The in-plane retardation Re [550] of the inner protective layer is preferably 0 nm to 10 nm, more preferably 0 nm to 6 nm, particularly preferably 0 nm to 3 nm. Details of the film that can form such an optically isotropic protective layer are described in Japanese Patent Application Laid-Open No. 2008-180961, and the description thereof is incorporated herein by reference.

H. Manufacturing method of a liquid crystal panel The liquid crystal panel of this invention is obtained by laminating | stacking said each layer (film). Any appropriate method can be adopted as the lamination method. Specifically, it is laminated via any appropriate pressure-sensitive adhesive layer or adhesive layer. As the said adhesive layer, an acrylic adhesive layer is mentioned typically. The thickness of the acrylic pressure-sensitive adhesive layer is preferably 1 to 30 μm, more preferably 3 to 25 μm. Examples of the adhesive layer include a polyester-based adhesive layer, a polyurethane-based adhesive layer, a polyvinyl alcohol-based adhesive layer, and an epoxy-based adhesive layer. The thickness of the adhesive layer is preferably 0.1 to 10 μm, more preferably 0.2 to 8 μm.

  As described above, when the first optical compensation layer 20 or the third optical compensation layer 50 can function as a protective layer of the first polarizer 10 or the second polarizer 60, these polarizers and optical compensation are used. The layer can be laminated via any suitable pressure-sensitive adhesive layer or adhesive layer. Examples of the adhesive used for laminating the polarizer and the optical compensation layer include an adhesive containing a polyvinyl alcohol-based resin, a cross-linking agent, and a metal compound colloid from the viewpoint of suppressing the occurrence of nicks. Such an adhesive is described in Japanese Patent Application Laid-Open No. 2008-180961, and the description thereof is incorporated herein by reference.

I. Liquid crystal display device The liquid crystal display device of this invention has the said liquid crystal panel. In the liquid crystal display device of the present invention, the liquid crystal panel is arranged by any appropriate method.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.

[Example 1-6, Comparative Example 1-4]
Using the optical characteristic parameters of each optical compensation layer actually fabricated and measured, it was adhered from a liquid crystal panel having the configuration shown in Table 1 (the axis angle is displayed with the first polarizer on the viewing side as a reference (0 °)). A simulation was carried out using the model excluding the agent layer and the protective layer as a simulation model, and the contrast in the oblique direction was calculated. The retardation value and chromatic dispersion value of each member were measured at 23 ° C. using a product name “Axoscan” manufactured by Axometric.

  For the simulation, a simulator for liquid crystal display “LCD MASTER Ver. 6.084” manufactured by Shintech Co., Ltd. was used. Calculated in quadrant multi-domain using the extended function of LCD Master, and the average value of 4 orientation values of polar angle 60 °, azimuth angle 45 °, 135 °, 225 °, and 315 ° by 2 × 2 calculation Was calculated as contrast. The voltage applied to the liquid crystal cell during white display was 6.0 V, the voltage applied during black display was 0.0 V, and the cell gap was 3.5 μm. Table 2 shows the characteristics of the liquid crystal cell, the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer in each example and comparative example. Table 3 shows the simulation results.

  As shown in Table 3, the relationship between the retardation wavelength dispersion of the liquid crystal cell and the retardation wavelength dispersion of the first and second optical compensation layers functioning as λ / 4 plates is appropriately adjusted. In the liquid crystal panel No. 6, the contrast in the oblique direction is high, which indicates that the light leakage in the oblique direction is suppressed and the viewing angle is accurately compensated. On the other hand, in the liquid crystal panel of the comparative example, the contrast in the oblique direction is lower than that in the liquid crystal panel of the example, and it is understood that the viewing angle compensation in the oblique direction is insufficient.

  The liquid crystal panel and the liquid crystal display device of the present invention can be suitably applied to a liquid crystal television or the like.

100 Liquid crystal panel 10 First polarizer 20 First optical compensation layer 30 Liquid crystal cell 40 Second optical compensation layer 50 Third optical compensation layer 60 Second polarizer

Claims (4)

A first polarizer, a first optical compensation layer that functions as a λ / 4 plate, a VA mode liquid crystal cell, a second optical compensation layer that functions as a λ / 4 plate, and nz>nx> ny Having a third optical compensation layer having a refractive index relationship and a second polarizer in this order from the viewing side;
Let α _cell be the retardation wavelength dispersion value (Re _cell [450] / Re _cell [550]) of the liquid crystal cell, and the average retardation wavelength dispersion value (Re of the first optical compensation layer and the second optical compensation layer). _{λ / 4 [450] / Re} λ / 4 the [550]) when the _{α λ / 4, α λ /} 4 / α cell is Ri der 0.95 to 1.02,
Nz coefficients of the first optical compensation layer and the second optical compensation layer satisfy a relationship of 1.6 <Nz ≦ 2.4,
Re ₃ [550] of the _third optical compensation layer is 30 to 200 nm , Rth ₃ [550] is −300 to −10 nm, and the Nz coefficient satisfies the relationship of −2 ≦ Nz ≦ −0.1. ,
An angle formed by the absorption axis of the first polarizer and the slow axis of the first optical compensation layer is substantially 45 degrees,
The slow axis of the first optical compensation layer and the slow axis of the second optical compensation layer are substantially orthogonal;
The absorption axis of the second polarizer and the slow axis of the third optical compensation layer are substantially parallel;
A liquid crystal panel , wherein an absorption axis of the first polarizer and an absorption axis of the second polarizer are substantially orthogonal . The liquid crystal panel according to claim 1, wherein the α _{λ / 4} is 0.9 to 1.05. The liquid crystal panel according to claim 1, wherein the α _cell is 0.9 to 1.02. Having a liquid crystal panel according to any one of claims 1 to 3, a liquid crystal display device.

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