KR102565008B1 - Liquid crystal display - Google Patents

Abstract

An object of the present invention is to provide a liquid crystal display device having excellent color reproducibility, excellent visibility when viewed through an optical member having a polarizing action, and suppressing color unevenness. A liquid crystal display device 500 of the present invention includes a liquid crystal cell 10, a first polarizer 20 disposed on a viewing side of the liquid crystal cell 10, and a second polarizer 30 disposed on a rear side of the liquid crystal cell 10. (100); a retardation layer 200 disposed on a viewing side of the liquid crystal panel 100; and a backlight source 300 for illuminating the liquid crystal panel from the rear side. The in-plane retardation Re(550) of the retardation layer 200 is 100 nm to 180 nm, and also satisfies the relationship Re(450)<Re(550)<Re(650). An angle between the slow axis of the retardation layer 200 and the long side of the liquid crystal panel 100 is 35° to 55°. The backlight light source 300 has a discontinuous emission spectrum.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY}

The present invention relates to a liquid crystal display device.

Recently, opportunities for liquid crystal display devices to be used under strong external light, such as mobile phones, smart phones, tablet personal computers (PCs), car navigation systems, digital signage, and window displays, are increasing. In this way, when the liquid crystal display device is used outdoors, when a viewer wears polarized sunglasses and looks at the liquid crystal display device, the direction of the transmission axis of the polarized sunglasses and the emission side of the liquid crystal display device depend on the viewer's viewing angle. The transmission axis direction becomes a cross nicol state, and as a result, the screen may become black and the display image may not be visible. In order to solve this problem, a technique of arranging a λ/4 plate or an ultra-high phase difference film on the viewing side of the liquid crystal display has been proposed.

On the other hand, in order to improve the color reproducibility of the liquid crystal display, attempts have been made to approximate the characteristics of a red (R), green (G), and blue (B) light source for a backlight source. However, in this attempt, as a countermeasure against polarized sunglasses, there is a problem such as coloring and/or color unevenness even if a λ/4 plate or an ultra-high retardation film is simply disposed on the viewing side of the liquid crystal display device.

Japanese Unexamined Patent Publication No. 2005-352068 Japanese Unexamined Patent Publication No. 2011-107198

The present invention has been made to solve the above conventional problems, and its object is to have excellent color reproducibility, excellent visibility when viewed through an optical member having a polarizing action, and a liquid crystal in which color unevenness is suppressed. To provide a display device.

A liquid crystal display device of the present invention includes a liquid crystal panel including a liquid crystal cell, a first polarizer disposed on a viewing side of the liquid crystal cell, and a second polarizer disposed on a rear side of the liquid crystal cell; a retardation layer disposed on a viewing side of the liquid crystal panel; and a backlight source for illuminating the liquid crystal panel from the rear side. The in-plane retardation Re(550) of the retardation layer is 100 nm to 180 nm, and also satisfies the relationship Re(450)<Re(550)<Re(650). An angle between a slow axis of the retardation layer and a long side of the liquid crystal panel is 35° to 55°. The backlight source has a discontinuous emission spectrum.

In one embodiment, the emission spectrum of the backlight source has a peak P1 in a wavelength range of 430 nm to 470 nm, a peak P2 in a wavelength range of 530 nm to 570 nm, and a peak P3 in a wavelength range of 630 nm to 670 nm. The wavelength of peak P1 is λ1, the height is hP1 and the half-width is Δλ1, the wavelength of peak P2 is λ2, the height is hP2 and the half-width is Δλ2, the wavelength of peak P3 is λ3, the height is hP3 and the half-width is Δλ3, peak P1 and peak P2 When the height of the valley between peaks is hB1 and the height of the valley between peaks P2 and P3 is hB2, they satisfy the following relational expressions g(1) to (3):

(λ2-λ1)/(Δλ2+Δλ1)>1...(1)

(λ3-λ2)/(Δλ3+Δλ2)>1...(2)

0.8≤{hP2-(hB2+hB1)/2}/hP2≤1...(3)

In one embodiment, the refractive index ellipsoid of the retardation layer shows the relationship nx>nz>ny, and the Nz coefficient is 0.2 to 0.8.

In one embodiment, the liquid crystal display device further includes another retardation layer in which a refractive index ellipsoid exhibits a relationship of nz>nx≥ny between the liquid crystal panel and the retardation layer.

In one embodiment, the backlight source includes a red-emitting LED, a green-emitting LED, and a blue-emitting LED, and the phosphor of the red-emitting LED is activated by tetravalent manganese ions. In another embodiment, the backlight source includes a blue LED and a wavelength conversion layer including quantum dots.

In one embodiment, the absorption axis of the first polarizer is substantially orthogonal or parallel to the long side of the liquid crystal panel, and the absorption axis of the second polarizer is substantially orthogonal or parallel to the long side of the liquid crystal panel, An absorption axis of the first polarizer and an absorption axis of the second polarizer are substantially orthogonal.

According to an embodiment of the present invention, color reproducibility is excellent by using a backlight light source having a specific emission spectrum and arranging a retardation layer having a so-called reverse dispersion wavelength dependence and having a predetermined in-plane retardation at a specific axis angle on the viewing side, , It is also possible to realize a liquid crystal display device having excellent visibility when viewed through an optical member having a polarizing action and suppressing color unevenness.

1 is a schematic cross-sectional view of a liquid crystal display according to an embodiment of the present invention.
2 is a diagram schematically showing an example of an emission spectrum of a backlight light source that can be used in a liquid crystal display device according to an embodiment of the present invention.
3 is a diagram schematically showing an example of an emission spectrum of a conventional backlight light source.

Hereinafter, representative embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

(Definition of Terms and Symbols)

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 maximized (ie, the slow axis direction), and "ny" is the refractive index in the direction orthogonal to the slow axis in the plane (ie, the fast axis direction), "nz" is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

“Re(λ)” is the in-plane retardation of the film measured with light having a wavelength of λ nm at 23°C. For example, “Re(450)” is the in-plane retardation of the film measured with light of a wavelength of 450 nm at 23°C. Re(λ) can be obtained by the formula: Re(λ)=(nx-ny)×d when the thickness of the film is d(nm).

(3) Phase difference in thickness direction (Rth)

“Rth(λ)” is the phase difference in the thickness direction of the film measured at 23° C. with light having a wavelength of 550 nm. For example, "Rth (450)" is the phase difference in the thickness direction of the film measured at 23 DEG C with light having a wavelength of 450 nm. Rth(λ) can be obtained by the formula: Rth(λ)=(nx-nz)×d when the thickness of the film is d(nm).

(4) Nz factor

The Nz coefficient can be obtained as Nz=Rth/Re.

(5) nx=ny, nx=nz, ny=nz

nx = ny includes not only a case where nx and ny are completely equal, but also a case where nx and ny are substantially equal. The relationship of nx=nz and ny=nz is also the same.

(6) substantially orthogonal or parallel

The expressions "substantially orthogonal" and "approximately orthogonal" include the case where the angle formed by the two directions is 90°±10°, preferably 90°±7°, and more preferably 90°±5°. am. The expressions "substantially parallel" and "approximately parallel" include the case where the angle formed by the two directions is 0°±10°, preferably 0°±7°, and more preferably 0°±5°. am. In addition, when simply referring to "orthogonal" or "parallel", it is assumed that a substantially orthogonal or substantially parallel state may be included.

(7) angle

When referring to an angle in this specification, unless otherwise specified, the angle includes angles in both clockwise and counterclockwise directions.

A. Overall composition of the liquid crystal display

1 is a schematic cross-sectional view of a liquid crystal display according to an embodiment of the present invention. In the drawing, for ease of viewing, the ratio of the thickness of each layer and each optical member is different from the actual one. The liquid crystal display device 500 of the present embodiment includes a liquid crystal panel 100, a retardation layer 200 disposed on the viewing side of the liquid crystal panel 100, and a backlight source for illuminating the liquid crystal panel 100 from the rear side ( 300) is provided. In the illustrated example, another retardation layer 400 may be additionally disposed between the liquid crystal panel 100 and the retardation layer 200 . Other retardation layers may be omitted depending on the purpose, configuration, desired characteristics, and the like. For convenience, the retardation layer 200 is sometimes referred to as a first retardation layer and the other retardation layer 400 is referred to as a second retardation layer. In the embodiment of the present invention, the in-plane retardation Re (550) of the first retardation layer 200 is 100 nm to 180 nm, preferably 110 nm to 170 nm, more preferably 120 nm to 160 nm, and particularly preferably 135 nm. -155 nm. Also, the first retardation layer 200 satisfies the relationship of Re(450)<Re(550)<Re(650). In addition, in the embodiment of the present invention, the backlight light source 300 has a discontinuous emission spectrum.

The liquid crystal panel 100 includes a liquid crystal cell 10, a first polarizer 20 disposed on the viewing side of the liquid crystal cell 10, and a second polarizer 30 disposed on the rear side of the liquid crystal cell 10. . The absorption axis of the first polarizer 20 is substantially orthogonal or parallel to the long side of the liquid crystal panel 100 (liquid crystal cell 10). The absorption axis of the second polarizer 30 is also substantially orthogonal or parallel to the long side of the liquid crystal panel 100 (liquid crystal cell 10). Further, the long side of the liquid crystal panel may be in the left-right direction or in the vertical direction of the display screen. The absorption axis of the first polarizer 20 and the absorption axis of the second polarizer 30 are substantially orthogonal. A protective film (not shown) may be disposed on one side or both sides of the first polarizer 20 . Similarly, a protective film (not shown) may be disposed on one side or both sides of the second polarizer 30 .

The angle formed by the slow axis of the first retardation layer 200 and the long side of the liquid crystal panel 100 is 35 ° to 55 °, preferably 38 ° to 52 °, more preferably 40 ° to 50 °, More preferably, it is 42° to 48°, particularly preferably 44° to 46°, and among them, preferably about 45°. Therefore, the angle between the slow axis of the first retardation layer 200 and the absorption axis of the first polarizer 20 is preferably 35° to 55°, more preferably 38° to 52°, and still more preferably is 40° to 50°, particularly preferably 42° to 48°, particularly preferably 44° to 46°, and most preferably about 45°.

In one embodiment, a conductive layer (not shown) may be provided between the first polarizer 20 and the liquid crystal cell 10 . By providing such a conductive layer, the liquid crystal display device can function as a so-called inner touch panel type input display device in which a touch sensor is incorporated between a display cell (liquid crystal cell) and a polarizer.

If necessary, any suitable optical compensation layer (additionally another retardation layer) may be formed between the first polarizer 20 and the liquid crystal cell 10 and/or between the second polarizer 30 and the liquid crystal cell 10. may be placed. The number, combination, arrangement position, arrangement order, optical properties (e.g., refractive index ellipsoid, in-plane retardation, thickness direction retardation, Nz coefficient), mechanical properties, etc. of these optical compensation layers are the purpose, configuration and desired characteristics of the liquid crystal display device. can be set appropriately according to

Hereinafter, components (optical films and optical members) of the liquid crystal display device will be described.

B. liquid crystal panel

B-1. liquid crystal cell

The liquid crystal cell 10 has a pair of substrates 11 and 12 and a liquid crystal layer 13 as a display medium sandwiched between the substrates. In a general configuration, a color filter and a black matrix are provided on one substrate 11, and on the other substrate 12, a switching element for controlling the electro-optical characteristics of liquid crystal, and a scanning line providing a gate signal to the switching element. and a signal line providing a source signal, a pixel electrode, and a counter electrode. The spacing (cell gap) between the substrates 11 and 12 can be controlled with a spacer or the like. On the side of the substrates 11 and 12 in contact with the liquid crystal layer 13, for example, an alignment film made of polyimide or the like may be provided.

In one embodiment, the liquid crystal layer 13 includes liquid crystal molecules aligned in a homogeneous arrangement in the absence of an electric field. In such a liquid crystal layer (result, a liquid crystal cell), the refractive index ellipsoid typically exhibits a relationship of nx>ny=nz. Representative examples of driving modes using a liquid crystal layer exhibiting such a three-dimensional refractive index include an in-plane switching (IPS) mode and a fringe field switching (FFS) mode. The IPS mode includes a super-in-plane switching (S-IPS) mode or an advanced super-in-plane switching (AS-IPS) mode employing V-shaped electrodes or zigzag electrodes. The FFS mode includes an advanced fringe field switching (A-FFS) mode employing V-shaped electrodes or zigzag electrodes, or an ultra fringe field switching (U-FFS) mode. In a driving mode (e.g., IPS mode, FFS mode) using liquid crystal molecules aligned in a homogeneous arrangement in the absence of such an electric field, there is no oblique gradation inversion and the oblique viewing angle is wide, resulting in high visibility from an oblique angle. It has the advantage of being excellent.

In another embodiment, the liquid crystal layer 13 includes liquid crystal molecules aligned in a homeotropic arrangement in the absence of an electric field. As a driving mode using liquid crystal molecules aligned in a homeotropic arrangement in the absence of an electric field, a vertical alignment (VA) mode is exemplified. VA mode includes multi-domain VA (MVA) mode. In a drive mode (e.g., VA mode) using liquid crystal molecules aligned in a homeotropic arrangement in the absence of such an electric field, since the transmittance of midtones in the oblique direction is higher than that of the midtone in the front direction, the transmittance of midtones in the front direction is The advantage is that the mid-tone is bright and there is little blocked up shadow.

B-2. Polarizer

As the first polarizer 20 and the second polarizer 30, any suitable polarizer may be employed. The material, thickness, optical characteristics, etc. of the first polarizer 20 and the second polarizer 30 may be the same or different. Hereinafter, both the first polarizer 20 and the second polarizer 30 are sometimes referred to as polarizers.

The resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

Specific examples of the polarizer composed of a single-layer resin film include polyvinyl alcohol (PVA)-based films, partially formylated PVA-based films, hydrophilic polymer films such as ethylene-vinyl acetate copolymer-based partially saponified films, iodine, dichroic dyes, etc. polyene-based oriented films such as those subjected to dyeing treatment and stretching treatment with a dichroic substance, dehydrated PVA products and dehydrochlorinated polyvinyl chloride products, and the like. Preferably, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching is used because it has excellent optical properties.

Dyeing with iodine is performed, for example, by immersing a PVA-based film in an aqueous solution of iodine. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after dyeing treatment, or may be performed while dyeing. Moreover, you may dye after extending|stretching. Swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. are applied to the PVA-based film as necessary. For example, by immersing and washing the PVA-based film in water before dyeing, stains and anti-blocking agents on the surface of the PVA-based film can be cleaned, and staining and the like can be prevented by swelling the PVA-based film.

Specific examples of the polarizer obtained using the laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and a PVA-based resin layer applied and formed on the resin substrate. A polarizer obtained using a layered product is mentioned. A polarizer obtained by using a laminate of a resin substrate and a PVA-based resin layer coated and formed on the resin substrate, for example, by applying a PVA-based resin solution to the resin substrate, drying it, forming a PVA-based resin layer on the resin substrate, and forming a resin resin. Obtaining a laminated body of a substrate and a PVA-based resin layer; It can be produced by: stretching and dyeing the layered product to make the PVA-based resin layer a polarizer. In this embodiment, extending|stretching typically includes extending|stretching by immersing a layered product in boric acid aqueous solution. Further, the stretching may further include air stretching the laminate at a high temperature (eg, 95° C. or higher) before stretching in a boric acid aqueous solution, if necessary. The obtained laminate of the resin substrate/polarizer may be used as it is (that is, the resin substrate may be used as a protective layer for the polarizer), and the resin substrate is peeled from the laminate of the resin substrate/polarizer, and the peel surface is used for the purpose. According to the above, any suitable protective layer may be laminated and used. The details of the manufacturing method of such a polarizer are described in Unexamined-Japanese-Patent No. 2012-73580, for example. This publication is incorporated herein by reference in its entirety.

The thickness of the polarizer is preferably 15 μm or less, more preferably 1 μm to 12 μm, still more preferably 3 μm to 10 μm, and particularly preferably 3 μm to 8 μm. When the thickness of the polarizer is within this range, curl during heating can be suppressed satisfactorily, and good appearance durability during heating can be obtained. Moreover, it can contribute to thickness reduction of a liquid crystal display device as the thickness of a polarizer is such a range.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizer is preferably 43.0% to 46.0%, more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, still more preferably 99.9% or more.

As described above, a protective film may be disposed on one side or both sides of the first polarizer 20 , and a protective film may be disposed on one side or both sides of the second polarizer 30 . That is, a polarizer may be a component of a liquid crystal display device independently, and may serve as a component of a liquid crystal display device as a polarizing plate containing a polarizer and a protective film. Furthermore, a polarizer and a protective film may be laminated separately (that is, a polarizer and a protective film are respectively) and may become a component of a liquid crystal display device.

The protective film is formed of any suitable film. Specific examples of the material used as the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and transparent resins such as polysulfone, polystyrene, polynorbornene, polyolefin, (meth)acrylic, and acetate resins. Further, thermosetting resins such as (meth)acrylic, urethane-based, (meth)acrylurethane-based, epoxy-based, and silicone-based resins or ultraviolet curable resins may be used. In addition, glassy type polymers, such as a siloxane type polymer, are also mentioned, for example. Moreover, the polymer film of Unexamined-Japanese-Patent No. 2001-343529 (WO01/37007) can also be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group on its side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group on its side chain can be used. For example, isobutene and N - A resin composition comprising an alternating copolymer composed of methyl maleimide and an acrylonitrile/styrene copolymer. The polymer film may be, for example, an extrusion molding of the resin composition.

The thickness of the protective film is preferably 20 μm to 200 μm, more preferably 30 μm to 100 μm, still more preferably 35 μm to 95 μm.

When a protective film (inner protective film) is disposed on the side of the liquid crystal cell 10 of the first polarizer 20 and/or the second polarizer 30, the inner protective film is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is -10 nm to +10 nm.

C. The first retardation layer

As described above, the in-plane retardation Re (550) of the first retardation layer 200 is 100 nm to 180 nm, preferably 110 nm to 170 nm, more preferably 120 nm to 160 nm, and particularly preferably 135 nm to 155 nm. That is, the first retardation layer can function as a so-called λ/4 plate. Accordingly, the first retardation layer has a function of converting linearly polarized light emitted from the polarizer to the viewing side into elliptically polarized light or circularly polarized light. In this way, by arranging the first retardation layer, which can function as a λ/4 plate, on the viewer side rather than the viewer side polarizer (first polarizer 20) in the specific axial relationship as described above, an optical member having a polarizing action (e.g. , polarized sunglasses) can realize excellent visibility even when viewing the display screen. Therefore, the liquid crystal display device of the present invention can be suitably used outdoors.

Also, the first retardation layer satisfies the relationship of Re(450)<Re(550)<Re(650) as described above. That is, the first retardation layer exhibits the wavelength dependence of reverse dispersion in which the retardation value increases with the wavelength of the measurement light. Re(450)/Re(550) of the first retardation layer is preferably 0.8 or more and less than 1.0, more preferably 0.8 to 0.95. Re(550)/Re(650) is preferably 0.8 or more and less than 1.0, more preferably 0.8 to 0.97.

The first retardation layer typically has a refractive index characteristic of nx>ny and has a slow axis. As described above, the angle between the slow axis of the first retardation layer 200 and the absorption axis of the first polarizer 20 is preferably 35° to 55°, more preferably 38° to 52°, and It is preferably 40° to 50°, particularly preferably 42° to 48°, especially preferably 44° to 46°, and most preferably about 45°. If the angle is within this range, an optical member having a polarizing effect (e.g., polarized sunglasses) by using a λ/4 plate as the first retardation layer and arranging the first retardation layer on the viewer side rather than the first polarizer (viewer side polarizer). Even when the display screen is visually recognized through, excellent visibility can be realized. Therefore, the liquid crystal display device of the present invention can be suitably used outdoors as well.

The first retardation layer represents any appropriate refractive index ellipsoid as long as it has a relationship of nx>ny. Preferably, the refractive index ellipsoid of the first retardation layer exhibits a relationship of nx>nz>ny. The Nz coefficient of the first retardation layer is preferably 0.2 to 0.8, more preferably 0.3 to 0.7, still more preferably 0.4 to 0.6, and particularly preferably about 0.5. Satisfying this relationship has an advantage that coloration when viewed from an oblique direction through an optical member having a polarizing action (e.g., polarized sunglasses) is suppressed.

The absolute value of the photoelastic coefficient of the first retardation layer is preferably 2×10 ^-11 m ² /N or less, more preferably 2.0×10 ^-13 m ² /N to 1.5× ^{10 -11} m ² /N, More preferably, it contains a resin of 1.0×10 ^-12 m ² /N to 1.2× ^{10 -11} m ² /N. If the absolute value of the photoelastic coefficient is within this range, phase difference change is unlikely to occur when shrinkage stress occurs during heating. As a result, heat unevenness of the liquid crystal display device can be favorably prevented.

The thickness of the first retardation layer may be set to function most appropriately as a λ/4 plate. In other words, the thickness can be set such that a desired in-plane retardation is obtained. Specifically, the thickness is preferably 1 μm to 80 μm, more preferably 10 μm to 80 μm, still more preferably 10 μm to 60 μm, and particularly preferably 30 μm to 50 μm.

The first retardation layer is formed of any suitable resin that can satisfy the above characteristics. Examples of the resin forming the first retardation layer include polycarbonate resin, polyvinyl acetal resin, cycloolefin resin, acrylic resin, and cellulose ester resin. Preferably it is a polycarbonate resin.

As the polycarbonate resin, any appropriate polycarbonate resin can be used as long as the effects of the present invention are obtained. Preferably, the polycarbonate resin comprises a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and an alicyclic diol, alicyclic dimethanol, di, tri, or polyethylene It includes a structural unit derived from glycol and at least one dihydroxy compound selected from the group consisting of alkylene glycol and spiroglycol. Preferably, the polycarbonate resin comprises a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from alicyclic dimethanol, and/or contains structural units derived from di, tri or polyethylene glycol; More preferably, a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di, tri, or polyethylene glycol are included. The polycarbonate resin may also contain structural units derived from other dihydroxy compounds as needed. Further, details of polycarbonate resins that can be suitably used in the present invention are described in, for example, Japanese Patent Application Laid-open No. 2014-10291 and Japanese Unexamined Patent Publication No. 2014-26266, and the description is incorporated herein by reference.

The glass transition temperature of the polycarbonate resin is preferably 110°C or higher and 250°C or lower, more preferably 120°C or higher and 230°C or lower. When the glass transition temperature is excessively low, heat resistance tends to deteriorate, dimensional change may occur after film forming, and image quality of the obtained liquid crystal display device may be lowered in some cases. If the glass transition temperature is excessively high, the molding stability at the time of forming the film may be deteriorated, and the transparency of the film may be impaired in some cases. In addition, glass transition temperature can be calculated according to JIS K 7121 (1987).

The molecular weight of the polycarbonate resin can be expressed as a reduced viscosity. The reduced viscosity was measured using an ubbelohde viscometer at a temperature of 20.0°C ± 0.1°C after precisely preparing the polycarbonate concentration to 0.6 g/dL using methylene chloride as a solvent. The lower limit of the reduced viscosity is usually preferably 0.30 dL/g, more preferably 0.35 dL/g or more. The upper limit of the reduced viscosity is usually preferably 1.20 dL/g, more preferably 1.00 dL/g, still more preferably 0.80 dL/g. When the reduced viscosity is less than the lower limit, a problem in which the mechanical strength of the molded article is reduced may occur. On the other hand, if the reduced viscosity is greater than the above upper limit, the flowability during molding may decrease, resulting in a decrease in productivity or moldability.

The retardation film constituting the first retardation layer is obtained, for example, by stretching a film formed of the polycarbonate-based resin. As a method of forming a film from a polycarbonate-based resin, any suitable molding processing method can be employed. Specific examples include compression molding method, transfer molding method, injection molding method, extrusion molding method, blow molding method, powder molding method, FRP molding method, cast coating method (casting method), calender molding method, hot press method and the like. An extrusion molding method or a cast coating method is preferred. It is because the smoothness of the obtained film can be improved and favorable optical uniformity can be obtained. Molding conditions may be appropriately set according to the composition or type of resin used, characteristics required of the retardation film, and the like.

The thickness of the resin film (unstretched film) can be set to any suitable value depending on the desired thickness of the obtained retardation film, desired optical properties, stretching conditions described later, and the like. Preferably they are 50 micrometers - 300 micrometers.

Any suitable stretching method and stretching conditions (eg, stretching temperature, stretching ratio, stretching direction) may be employed for the stretching. Specifically, various stretching methods such as free end stretching, fixed end stretching, free end contraction, and fixed end contraction may be used alone, simultaneously or sequentially. As for the stretching direction, it can be carried out in various directions or dimensions, such as the longitudinal direction, the width direction, the thickness direction, and the oblique direction.

By appropriately selecting the stretching method and stretching conditions, a retardation film having the desired optical properties (eg, refractive index characteristics, in-plane retardation, Nz coefficient) can be obtained.

In one embodiment, the retardation film is produced by uniaxial stretching or fixed single uniaxial stretching of a resin film. As a specific example of fixed-end uniaxial stretching, a method of stretching a resin film in the width direction (transverse direction) while running it in the longitudinal direction may be mentioned. The draw ratio is preferably 1.1 to 3.5 times.

In another embodiment, the retardation film can be produced by continuously obliquely stretching a long resin film in a predetermined angular direction with respect to the longitudinal direction. By employing oblique stretching, a long stretched film having a predetermined angular orientation angle (slow axis in the predetermined angular direction) with respect to the longitudinal direction of the film is obtained, and for example, roll-to-roll is possible in lamination with a polarizer. , the manufacturing process can be simplified. Also, the predetermined angle may be an angle between an absorption axis of the first polarizer and a slow axis of the first retardation layer in the liquid crystal display device. The angle is as described above, preferably 35 ° to 55 °, more preferably 38 ° to 52 °, even more preferably 40 ° to 50 °, particularly preferably 42 ° to 48 °, Among them, it is preferably 44° to 46°, and most preferably about 45°.

Stretching machines used for oblique stretching include, for example, tenter-type stretching machines capable of applying feed force, tensile force, or pulling force at different speeds left and right in the transverse and/or longitudinal directions. A tenter-type stretching machine includes a transverse-uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine may be used as long as it can continuously obliquely stretch a long resin film.

By appropriately controlling the left and right speeds in the stretching machine, a retardation film having the desired in-plane retardation and having a slow axis in the desired direction (substantially a long retardation film) can be obtained.

As a method of oblique stretching, for example, Japanese Unexamined Patent Publication No. 50-83482, Japanese Unexamined Patent Publication No. 2-113920, Japanese Unexamined Patent Publication No. 3-182701, Japanese Unexamined Patent Publication No. 2000-9912, Japanese Unexamined Patent Publication No. 2002-86554 The method described in gazette, Japanese Unexamined-Japanese-Patent No. 2002-22944, etc. is mentioned.

The retardation film (that is, the retardation film having an Nz coefficient of less than 1.0) that can be suitably used in the embodiment of the present invention forms a laminate by bonding a heat-shrinkable film to one or both surfaces of a resin film, for example, via an acrylic pressure-sensitive adhesive. And, it can be produced by subjecting the layered product to the above stretching. A retardation film having a desired Nz coefficient can be obtained by adjusting the configuration (eg, shrinkage force) and stretching conditions (eg, stretching temperature) of the heat-shrinkable film.

The stretching temperature of the film may vary depending on the desired in-plane retardation value and thickness of the retardation film, the type of resin used, the thickness of the film used, and the stretching ratio. Specifically, the stretching temperature is preferably Tg-30°C to Tg+30°C, more preferably Tg-15°C to Tg+15°C, and most preferably Tg-10°C to Tg+10°C. By stretching at such a temperature, a retardation film having suitable properties in the present invention can be obtained. In addition, Tg is the glass transition temperature of the constituent material of a film.

A commercially available polycarbonate-based resin film may be used. Specific examples of commercially available products include "Pure Ace WR-S", "Pure Ace WR-W" and "Pure Ace WR-M" manufactured by Teijin, and "NRF" manufactured by Nitto Denko. A commercially available film may be used as it is, or a commercially available film may be used after secondary processing (eg, stretching treatment, surface treatment) depending on the purpose.

D. Back light source

The backlight source 300 is included in a backlight unit (not shown). The backlight unit typically includes a light guide plate, a diffusion sheet, a prism sheet, and the like along with a light source. The backlight light source has a discontinuous emission spectrum as described above. "Having a discontinuous emission spectrum" means that clear peaks exist in each of the wavelength regions of red (R), green (G) and blue (B), and the respective peaks are clearly distinguished. 2 is a diagram schematically showing an example of a discontinuous emission spectrum. As shown in Fig. 2, the emission spectrum of the backlight source preferably has a peak P1 in the wavelength range (blue wavelength range) of 430 nm to 470 nm, more preferably 440 nm to 460 nm, preferably 530 nm to 570 nm, and more It preferably has a peak P2 in a wavelength range of 540 nm to 560 nm (green wavelength range), and a peak P3 in a wavelength range of preferably 630 nm to 670 nm, more preferably 640 nm to 660 nm (red wavelength range). Preferably, the wavelength λ1 of the peak P1, the height hP1 and the half-width Δλ1, the wavelength λ2 of the peak P2, the height hP2 and the half-maximum width Δλ2, the wavelength λ3 of the peak P3, the height hP3 and the half-width Δλ3, and the height hB1 of the valley between the peak P1 and the peak P2 , and, height hB2 of the trough between peaks P2 and P3 satisfies the following relational expressions (1) to (3):

(λ2-λ1)/(Δλ2+Δλ1)>1...(1)

(λ3-λ2)/(Δλ3+Δλ2)>1...(2)

0.8≤{hP2-(hB2+hB1)/2}/hP2≤1...(3)

(λ2-λ1)/(Δλ2+Δλ1) in formula (1) is more preferably from 1.01 to 2.00, still more preferably from 1.10 to 1.50. (λ3-λ2)/(Δλ3+Δλ2) in formula (2) is more preferably from 1.01 to 2.00, still more preferably from 1.10 to 1.50. {hP2-(hB2+hB1)/2} in formula (3) is more preferably from 0.85 to 1, still more preferably from 0.9 to 1. Equation (1) means that the relationship between blue light and green light is independent without mixing as light sources. Equation (2) means that the relationship between green light and red light is independent as a light source without color mixing. Equation (3) means that the valleys between the peaks P1, P2, and P3 are low, and peaks of blue light, green light, and red light are clearly distinguished. By defining the equations (1) to (3), there is an advantage that color reproducibility is improved. An optical member having excellent color reproducibility and polarizing action due to the synergistic effect of the backlight light source 300 having an emission spectrum satisfying Expressions (1) to (3) and the first retardation layer 200 described above. It is possible to realize a liquid crystal display device having excellent visibility when viewed through the display and suppressing color unevenness. For example, compared to a conventional backlight source having an emission spectrum as shown in FIG. 3 (a white light source in which LEDs emitting red, green, and blue light are simply combined), when viewed through an optical member having color reproducibility and polarization, Both visibility and color unevenness can be remarkably improved.

The backlight light source is any suitable configuration capable of realizing the above emission spectrum. In one embodiment, the backlight light source includes a red-emitting LED, a green-emitting LED, and a blue-emitting LED, and phosphors of the red-emitting LED are activated by tetravalent manganese ions. By activating the phosphor of the LED that emits red color, the overlapping of red light and green light in the light emission spectrum shown in FIG. 3 can be reduced, and the light emission spectrum shown in FIG. 2 can be realized. Preferable specific examples of the red phosphor activated by tetravalent manganese ions are exemplified in William M. Yen and Marvin J. Weber's CRC publication "INORGANIC PHOSPHORS" p.212 (SECTION 4: 4.10 Miscellaneous Oxides of PHOSPHOR DATA) Mn ⁴⁺ activated Mg fluorogermanate phosphor (2.5MgO MgF ₂ :Mn ⁴⁺ ) and M ¹ ₂ exemplified in Journal of the Electrochemical Society: SOLID-STATE SCIENCE AND TECHNOLOGY, July 1973, p942. M ² F ₆ :Mn ⁴⁺ (M ¹ =Li, Na, K, Rb, Cs; M ² =Si, Ge, Sn, Ti, Zr) phosphors. A backlight source using such a red phosphor is described, for example, in Japanese Unexamined Patent Publication No. 2015-52648. Further, a backlight light source having a general configuration including a red-emitting LED, a green-emitting LED, and a blue-emitting LED is described in, for example, Japanese Unexamined Patent Publication No. 2012-256014. Descriptions of these publications are incorporated herein by reference.

In another embodiment, the backlight light source includes a blue-emitting LED and a wavelength conversion layer including quantum dots. With this configuration, part of the blue light emitted from the LED is converted into red light and green light by the wavelength conversion layer, and part of the blue light is emitted as blue light as it is. As a result, white light can be realized. In addition, by properly configuring the wavelength conversion layer, it is possible to realize an emission spectrum (emission spectrum as shown in FIG. 2) with clear peaks of red light, green light, and blue light and small overlapping of each color light.

The wavelength conversion layer typically includes a matrix and quantum dots dispersed within the matrix. Any suitable material can be used as a material constituting the matrix (hereinafter also referred to as a matrix material). Examples of such materials include resins, organic oxides, and inorganic oxides. The matrix material preferably has low oxygen permeability and moisture permeability, high light stability and chemical stability, a certain refractive index, good transparency, and/or good dispersibility to quantum dots. Considering these comprehensively, the matrix material is preferably a resin. The resin may be a thermoplastic resin, a thermosetting resin, or an active energy ray curable resin (for example, an electron beam curable resin, an ultraviolet curable resin, or a visible ray curable resin). A thermosetting resin or an ultraviolet curable resin is preferable, and a thermosetting resin is more preferable. Resins may be used alone or may be used in combination (for example, mixing or copolymerization).

The quantum dots can control the wavelength conversion characteristics of the wavelength conversion layer. Specifically, a wavelength conversion layer realizing light having a desired emission center wavelength can be formed by using quantum dots having different light emission central wavelengths in appropriate combination. The emission central wavelength of the quantum dot can be adjusted by the material and/or composition of the quantum dot, particle size, shape, and the like. Quantum dots include, for example, quantum dots having a central wavelength of light emission in a wavelength range of 600 nm to 680 nm (hereinafter, quantum dots (A)), quantum dots having a central wavelength of light emission in a wavelength range of 500 nm to 600 nm (hereinafter, quantum dots (hereinafter, quantum dots)). A dot (B)), and a quantum dot (hereinafter referred to as quantum dot (C)) having an emission center wavelength in a wavelength range of 400 nm to 500 nm is known. Quantum dot A is excited by excitation light (light from a backlight source in the present invention) to emit red light, quantum dot B emits green light, and quantum dot C emits blue light. By appropriately combining these, when light of a predetermined wavelength (light from a backlight source) is incident and passed through the wavelength conversion layer, light having a central wavelength of emission in a desired wavelength band can be realized.

Quantum dots can be made of any suitable material. The quantum dot may be preferably composed of an inorganic material, more preferably an inorganic conductor material or an inorganic semiconductor material. Semiconductor materials include, for example, group II-VI, group III-V, group IV-VI, and group IV semiconductors. Specific examples include Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP , InAs, InSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdSeZn, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO , PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si ₃ N ₄ , Ge ₃ N ₄ , Al ₂ O ₃ (Al, Ga, In) ₂ (S, Se, Te) ₃ , Al ₂ CO can be heard These may be used independently or may be used in combination of 2 or more types. A quantum dot may contain a p-type dopant or an n-type dopant.

Any appropriate size may be employed as the size of the quantum dots depending on the desired emission wavelength. The size of the quantum dots is preferably 1 nm to 10 nm, more preferably 2 nm to 8 nm. When the size of the quantum dots is within this range, each of green and red emits sharp light emission, and high color rendering can be realized. For example, green light may emit light with a quantum dot size of about 7 nm, and red light may emit light with a quantum dot size of about 3 nm. The size of a quantum dot is the average particle diameter when the quantum dot is spherical, for example, and is the dimension along the minimum axis in the shape other than that. In addition, as the shape of the quantum dot, any suitable shape may be employed depending on the purpose. Specific examples include spherical shape, scale shape, plate shape, elliptical sphere shape, and irregular shape.

Quantum dots may be blended in a ratio of preferably 1 part by weight to 50 parts by weight, more preferably 2 parts by weight to 30 parts by weight, based on 100 parts by weight of the matrix material. When the compounding amount of the quantum dots is within this range, a liquid crystal display device having excellent balance of all RGB colors can be realized.

Details of quantum dots are, for example, Japanese Patent Laid-Open No. 2012-169271, Japanese Patent Laid-Open No. 2015-102857, Japanese Patent Laid-Open No. 2015-65158, Japanese Patent Publication No. 2013-544018, Japanese Patent Publication No. 2013-544018, Japanese Patent Publication It describes in gazette 2010-533976, and description of these gazettes is integrated in this specification as a reference. A commercial item may be used for the quantum dot.

The thickness of the wavelength conversion layer is preferably 1 μm to 500 μm, more preferably 100 μm to 400 μm. When the thickness of the wavelength conversion layer is within this range, conversion efficiency and durability may be excellent.

The wavelength conversion layer is disposed on the emission side of the LED (light source) as a film in the backlight unit.

E. Second retardation layer

As described above, the second retardation layer 400 has a refractive index characteristic of nz > nx > ny. The phase difference Rth (550) of the second retardation layer in the thickness direction is preferably -260 nm to -10 nm, more preferably -230 nm to -15 nm, still more preferably -215 nm to -20 nm. By installing the second retardation layer having such optical characteristics, coloring when viewed in an oblique direction through an optical member having a polarizing action (eg, polarized sunglasses) is remarkably improved, resulting in a liquid crystal display having excellent viewing angle characteristics. You can get it.

In one embodiment, the refractive index of the second retardation layer exhibits a relation of nx = ny. In another embodiment, the refractive index of the second retardation layer exhibits a relationship where nx>ny. Therefore, the second retardation layer may have a slow axis. In this case, the slow axis of the second retardation layer is substantially orthogonal or parallel to the absorption axis of the first polarizer 20 . In addition, the in-plane retardation Re (550) of the second retardation layer is preferably 10 nm to 150 nm, more preferably 10 nm to 80 nm.

The second retardation layer may be formed of any suitable material. Preferably, it is a liquid crystal layer fixed in homeotropic alignment. The liquid crystal material (liquid crystal compound) capable of homeotropic alignment may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the liquid crystal layer include the liquid crystal compound and formation method described in [0020] to [0042] of Japanese Unexamined Patent Publication No. 2002-333642. In this case, the thickness is preferably 0.1 μm to 5 μm, more preferably 0.2 μm to 3 μm.

As another preferred specific example, the second retardation layer may be a retardation film formed of a fumaric acid diester-based resin described in Japanese Unexamined Patent Publication No. 2012-32784. In this case, the thickness is preferably 5 μm to 80 μm, more preferably 10 μm to 50 μm.

F. Conductive layer

The conductive layer (not shown) is typically transparent (ie, the conductive layer is a transparent conductive layer). By forming a conductive layer between the first polarizer 20 and the liquid crystal cell 10, the liquid crystal display device can function as a so-called inner touch panel type input display device.

The conductive layer may be a component layer of the liquid crystal display device independently, or may be provided to the liquid crystal display device as a laminate with a base material (conductive layer with a base material). In the case where the conductive layer is constituted alone, the conductive layer may be transferred from the substrate on which the conductive layer is formed to a predetermined position of the liquid crystal display device.

The conductive layer can be patterned as needed. A conductive portion and an insulating portion may be formed by patterning. As a result, electrodes can be formed. The electrode may function as a touch sensor electrode that detects contact with the touch panel. The shape of the pattern is preferably a pattern that works well as a touch panel (eg, a capacitive touch panel). Specific examples include patterns described in Japanese Patent Application Publication No. 2011-511357, Japanese Patent Application Publication No. 2010-164938, Japanese Patent Application Publication No. 2008-310550, Japanese Patent Publication No. 2003-511799, and Japanese Patent Application Publication No. 2010-541109. there is.

The total light transmittance of the conductive layer is preferably 80% or more, more preferably 85% or more, still more preferably 90% or more. For example, if a conductive nanowire described later is used, a transparent conductive layer having openings can be formed, and a transparent conductive layer with high light transmittance can be obtained.

The density of the conductive layer is preferably 1.0 g/cm ³ to 10.5 g/cm ³ , more preferably 1.3 g/cm ³ to 3.0 g/cm ³ .

The surface resistance of the conductive layer is preferably 0.1 Ω/□ to 1000 Ω/□, more preferably 0.5 Ω/□ to 500 Ω/□, still more preferably 1 Ω/□ to 250 Ω/□.

Representative examples of the conductive layer include a conductive layer containing metal oxide, a conductive layer containing conductive nanowires, and a conductive layer containing metal mesh. Preferably, it is a conductive layer containing conductive nanowires or a conductive layer containing metal mesh. This is because it is excellent in bending resistance and hardly loses conductivity even when bent, so that a conductive layer that can be bent well can be formed. As a result, the liquid crystal display device can be configured to be bendable.

The conductive layer containing the metal oxide can be formed by forming a metal oxide film on any suitable substrate by any suitable film formation method (e.g., vacuum deposition method, sputtering method, CVD method, ion plating method, spray method, etc.) there is. Examples of the metal oxide include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Among them, indium-tin composite oxide (ITO) is preferred.

The conductive layer including the conductive nanowires may be formed by applying a dispersion (conductive nanowire dispersion) in which conductive nanowires are dispersed in a solvent onto any suitable substrate, and then drying the applied layer. As the conductive nanowire, any appropriate conductive nanowire may be used as long as the effect of the present invention can be obtained. The conductive nanowire refers to a conductive material having a needle-like or thread-like shape and a nanometer size in diameter. The conductive nanowires may be linear or curved. A conductive layer containing conductive nanowires is excellent in bending resistance as described above. In addition, the conductive layer containing the conductive nanowires forms gaps between the conductive nanowires to form a network, so that a good electrical conduction path can be formed even with a small amount of conductive nanowires, and a conductive layer with low electrical resistance can be obtained. there is. In addition, by forming the conductive nanowires into a network shape, openings can be formed in gaps between the networks to obtain a conductive layer with high light transmittance. Examples of the conductive nanowires include metal nanowires made of metal and conductive nanowires made of carbon nanotubes.

The ratio of the thickness (d) to the length (L) of the conductive nanowire (aspect ratio: L/d) is preferably 10 to 100,000, more preferably 50 to 100,000, still more preferably 100 to 10,000. In this way, when a conductive nanowire having a high aspect ratio is used, the conductive nanowires cross well, and high conductivity can be expressed with a small amount of the conductive nanowire. As a result, a conductive layer having high light transmittance can be obtained. In the present specification, "thickness of the conductive nanowire" means the diameter when the cross section of the conductive nanowire is circular, means the shortest diameter when the cross section is elliptical, and the longest diagonal when the cross section is polygonal means The thickness and length of the conductive nanowires can be confirmed using a scanning electron microscope or a transmission electron microscope.

The thickness of the conductive nanowire is preferably less than 500 nm, more preferably less than 200 nm, still more preferably 1 nm to 100 nm, and particularly preferably 1 nm to 50 nm. Within this range, a conductive layer having high light transmittance can be formed. The length of the conductive nanowire is preferably 2.5 μm to 1000 μm, more preferably 10 μm to 500 μm, still more preferably 20 μm to 100 μm. A conductive layer with high conductivity can be obtained in such a range.

Any appropriate metal may be used as the metal constituting the conductive nanowire (metal nanowire), as long as it is a highly conductive metal. The metal nanowire is preferably composed of one or more metals selected from the group consisting of gold, platinum, silver, and copper. Among these, silver, copper, or gold is preferred from the viewpoint of conductivity, and silver is more preferred. Alternatively, a material obtained by plating the above metal (for example, gold plating) may be used.

As the carbon nanotube, any suitable carbon nanotube may be used. For example, so-called multi-walled carbon nanotubes, double-walled carbon nanotubes, single-walled carbon nanotubes and the like are used. Among them, single-walled carbon nanotubes are preferably used because of their high conductivity.

As the metal mesh, any appropriate metal mesh may be used as long as the effect of the present invention can be obtained. For example, a metal wiring layer provided on a film substrate may be patterned in a network pattern.

Details of conductive nanowires and metal meshes are described in, for example, Japanese Patent Application Publication No. 2014-113705 and Japanese Patent Application Publication No. 2014-219667. The disclosure of this publication is incorporated herein by reference.

The thickness of the conductive layer is preferably 0.01 μm to 10 μm, more preferably 0.05 μm to 3 μm, still more preferably 0.1 μm to 1 μm. Within this range, a conductive layer having excellent conductivity and light transmittance can be obtained. In addition, when the conductive layer contains a metal oxide, the thickness of the conductive layer is preferably 0.01 μm to 0.05 μm.

G. Adhesive layer or adhesive layer

Any suitable pressure-sensitive adhesive layer or adhesive layer is used for laminating each layer and optical member constituting the liquid crystal display device of the present invention. The pressure-sensitive adhesive layer is typically formed of an acrylic pressure-sensitive adhesive. The adhesive layer is typically formed of a polyvinyl alcohol-based adhesive.

[Example]

Hereinafter, the present invention will be specifically described by examples, but the present invention is not limited by these examples. In addition, the measurement method of each characteristic is as follows. In addition, "part" and "%" in the examples are based on weight unless otherwise specified.

(1) Thickness

It was measured using a dial gauge (manufactured by PEACOCK, product name "DG-205", dial gauge stand (product name "pds-2")).

(2) phase difference

A sample of 50 mm × 50 mm was cut out from each retardation film and the liquid crystal solidified layer to be a measurement sample, and the measurement was performed using Axoscan manufactured by Axometrics. The measurement wavelengths were 450 nm and 550 nm, and the measurement temperature was 23°C.

In addition, the average refractive index was measured using an Abbe refractometer manufactured by Atago, and the refractive indices nx, ny, and nz were calculated from the obtained retardation values.

(3) Absorption rate

It was measured based on "Test method for water absorption and boiling water absorption of plastics" described in JIS K 7209. The size of the test piece was a square with a side of 50 mm, and was obtained by immersing the test piece in water at a water temperature of 25° C. for 24 hours and measuring the weight change before and after immersion. Unit is %.

(4) Backlight spectrum measurement

A white image was displayed on the liquid crystal display device obtained in each Example and each Comparative Example, and the emission spectrum was measured using SR-UL1R manufactured by Topcon. Regarding the obtained emission spectrum, the following formula ( 4), (5) and (6) were obtained. In addition, since the spectrum of display light when a white image is displayed on the liquid crystal display device is substantially the same as the emission spectrum of the backlight source, the spectrum of display light when a white image is displayed is taken as the emission spectrum of the backlight source.

(λ2-λ1)/(Δλ2+Δλ1)...(4)

(λ3-λ2)/(Δλ3+Δλ2)...(5)

{hP2-(hB2+hB1)/2}/hP2...(6)

(5) Visibility evaluation

A white image was displayed on the liquid crystal display device obtained in each Example and each Comparative Example, and visibility when the image was observed through polarized sunglasses was evaluated according to the following criteria.

Good...coloring and rainbow staining did not occur.

Defect...coloration occurred.

<Example 1>

(Production of retardation film (A) constituting the first retardation layer)

Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100°C. Molar 9,9-[4-(2-hydroxyethoxy)phenyl]fluorene (BHEPF), isosorbide (ISB), diethylene glycol (DEG), diphenylcarbonate (DPC) and magnesium acetate tetrahydrate The ratio of BHEPF/ISB/DEG/DPC/magnesium acetate=0.348/0.490/0.162/1.005/1.00×10 ^-5 was added. After sufficiently substituting the inside of the reactor with nitrogen (oxygen concentration of 0.0005 to 0.001 vol%), heating was performed with a heat medium, and stirring was started when the internal temperature reached 100°C. The internal temperature reached 220°C 40 minutes after the start of the temperature increase, and while controlling to maintain this temperature, the pressure reduction was started, and after reaching 220°C, it was set to 13.3 kPa in 90 minutes. Phenol vapor by-produced with the polymerization reaction was led to a reflux condenser at 100°C, monomer components contained in a slight amount in the phenol vapor were returned to the reactor, and uncondensed phenol vapor was led to a condenser at 45°C for recovery.

After nitrogen was introduced into the first reactor to once restore the pressure to atmospheric pressure, the oligomerized reaction solution in the first reactor was transferred to the second reactor. Subsequently, the temperature increase and pressure reduction in the second reactor were started, and the internal temperature was 240°C and the pressure was 0.2 kPa in 50 minutes. Thereafter, polymerization was allowed to proceed until a predetermined agitation power was reached. When the predetermined power is reached, nitrogen is introduced into the reactor to restore pressure, and the reaction solution is extracted in the form of strands and pelletized with a rotary cutter, resulting in a copolymerization composition of BHEPF / ISB / DEG = 34.8 / 49.0 / 16.2 [mol%] of polycarbonate resin was obtained. This polycarbonate resin had a reduced viscosity of 0.430 dL/g and a glass transition temperature of 128°C. After vacuum drying the obtained polycarbonate resin at 80 ° C. for 5 hours, a single screw extruder (manufactured by Isuzu Chemical Industry Co., Ltd., screw diameter 25 mm, cylinder set temperature: 220 ° C), T-die (width 900 mm, set temperature: 220 ° C), chilled roll A polycarbonate resin film having a thickness of 70 μm was produced using a film forming apparatus equipped with a chilled roll (set temperature: 125° C.) and a winding machine. The water absorption of the obtained polycarbonate resin film was 1.2%. Retardation film (A) (50 micrometers in thickness) was obtained by uniaxially stretching the obtained polycarbonate resin film 2.0 times at 133 degreeC. Re (550) of the obtained retardation film (A) was 140 nm, Rth (550) was 140 nm, and Re (450)/Re (550) was 0.89.

(Production of polarizer)

A-PET (amorphous-polyethylene terephthalate) film (manufactured by Mitsubishi Resins Co., Ltd., trade name: NovaClear SH046 200 μm) was prepared as a substrate, and corona treatment (58 W/m ² /min) was performed on the surface. On the other hand, PVA (polymerization degree 4200, degree of polymerization 4200, Saponification degree of 99.2%) was prepared, applied on a substrate so that the film thickness after drying was 12 μm, and dried for 10 minutes by hot air drying in an atmosphere of 60 ° C. to prepare a laminate in which a layer of PVA resin was provided on the substrate. did

Then, this laminate was first stretched 2.0 times in the MD direction at 130 DEG C in air to produce a stretched laminate. Next, the process of insolubilizing the PVA layer in which the PVA molecules contained in the stretched laminate were oriented was performed by immersing the stretched laminate in a boric acid insolubilizing aqueous solution at a liquid temperature of 30°C for 30 seconds. The boric acid aqueous solution for insolubilization in this step contained 3 parts by weight of boric acid with respect to 100 parts by weight of water. A colored laminate was produced by dyeing this stretched laminate that had passed through the insolubilization step. In this colored laminate, iodine is adsorbed to the PVA layer included in the stretch laminate by immersing the stretch laminate in a dye solution. The dye solution contains iodine and potassium iodide, the liquid temperature of the dye solution is 30 ℃, the iodine concentration is in the range of 0.08 to 0.25% by weight using water as a solvent, and the potassium iodide concentration is in the range of 0.56 to 1.75% by weight was in the range of The concentration ratio of iodine and potassium iodide was 1 to 7. As dyeing conditions, iodine concentration and immersion time were set so that the single transmittance of the PVA-based resin layer constituting the polarizer would be 40.9%.

Next, the step of crosslinking the PVA molecules of the PVA layer adsorbed with iodine was performed by immersing the colored layered product in a 30°C aqueous solution of boric acid for crosslinking for 60 seconds. An aqueous solution of boric acid for crosslinking used in this crosslinking step contains 3 parts by weight of boric acid with respect to 100 parts by weight of water and 3 parts by weight of potassium iodide with respect to 100 parts by weight of water. Further, the obtained colored laminate is stretched in an aqueous solution of boric acid at a stretching temperature of 70 ° C. by stretching 2.7 times in the same direction as the previous stretching in air, so that the final stretch ratio is 5.4 times, for test An optical film layered product containing a polarizer was obtained. The boric acid aqueous solution used in this stretching step contains 4.0 parts by weight of boric acid based on 100 parts by weight of water and 5 parts by weight of potassium iodide based on 100 parts by weight of water. The resulting optical film laminate was taken out of the boric acid aqueous solution, and the boric acid adhering to the surface of the PVA layer was washed with an aqueous solution containing 4 parts by weight of potassium iodide per 100 parts by weight of water. The washed optical film layered body was dried in a drying step by warm air at 60°C, and a polarizer having a thickness of 5 µm laminated on a PET film was obtained.

(Manufacture of polarizing plate with retardation layer)

In the polarizer manufactured as described above, for a polarizer having a thickness of 5 μm laminated on a PET film, the retardation film (A) is applied to the surface opposite to the PET through a UV curable adhesive, at an angle between the slow axis and the absorption axis of the polarizer. were bonded so that they were substantially 45°. Furthermore, the PET film was peeled from this layered product to obtain a polarizing plate with a retardation layer.

(Production of liquid crystal display device)

Take out the liquid crystal panel from the liquid crystal display device of the smartphone (Xperia Z4 manufactured by Sony Corporation: the emission spectrum of the backlight is discontinuous) equipped with the liquid crystal display device of the IPS system, and remove the polarizing plate placed on the viewing side of the liquid crystal cell, The glass surface of the liquid crystal cell was washed. Next, the surface of the polarizer side of the polarizing plate with the retardation plate is placed on the surface of the liquid crystal cell on the viewer side so that the absorption axis of the polarizer is orthogonal to the initial orientation direction of the liquid crystal cell (the slow axis of the first retardation layer and the liquid crystal). It was laminated with an acrylic adhesive (thickness of 20 μm) so that the angle formed by the long side of the panel was 45° and the angle formed by the absorption axis of the polarizer and the long side of the liquid crystal panel was 0°, to obtain a liquid crystal panel. The backlight unit of the smart phone was attached to the liquid crystal panel on which the polarizing plate with the retardation plate was laminated, and the liquid crystal display device of this embodiment was obtained. A white image was displayed on the liquid crystal display device, and visibility through polarized sunglasses was evaluated for the state of the white image. Table 1 shows the evaluation results.

<Example 2>

(Production of retardation film (B) constituting the first retardation layer)

A material for forming a birefringent layer was prepared by dissolving the polycarbonate resin (10 kg) obtained in the same manner as in Example 1 in methylene chloride (73 kg). Subsequently, the material for forming the birefringence layer was directly coated on a shrinkable film (machine-direction-uniaxially stretched polypropylene film, manufactured by Tokyo Ink Co., Ltd., trade name “Noblen”), and the coated film was dried at a drying temperature of 30° C. for 5 minutes at 80° C. It was dried at °C for 5 minutes to form a laminate of shrinkable film/birefringent layer. The obtained laminate was stretched using a simultaneous biaxial stretching machine at a stretching temperature of 155° C. at a shrinkage ratio of 0.80 in the MD direction and 1.3 times in the TD direction to form a phase difference film (B) on the shrinkable film. Then, the retardation film (B) was peeled off from the shrinkable film.

As described above, a retardation film (B) (thickness: 60 μm) was obtained. Re(550) of the obtained retardation film (B) was 140 nm, Rth(550) was 70 nm, and Re(450)/Re(550) was 0.89. The direction of the slow axis of the retardation film (B) was 90° with respect to the longitudinal direction.

(Production of polarizing plate with phase difference layer and liquid crystal display device)

A polarizing plate with a retardation layer was prepared in the same manner as in Example 1 except that the retardation film (B) was used instead of the retardation film (A), and a liquid crystal display was carried out in the same manner as in Example 1 except that the polarizing plate with a retardation layer was used. device was fabricated. A white image was displayed on the liquid crystal display device, and visibility through polarized sunglasses was evaluated for the state of the white image. Table 1 shows the evaluation results.

<Example 3>

(Preparation of liquid crystal solidified layer constituting second retardation layer)

20 parts by weight of a side chain type liquid crystal polymer represented by the following formula I (numbers 65 and 35 in the formula represent mole% of monomer units, and block polymers for convenience: weight average molecular weight 5000), representing a nematic liquid crystal phase 80 parts by weight of a polymerizable liquid crystal (manufactured by BASF: trade name Paliocolor LC242) and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name Irgacure 907) were dissolved in 200 parts by weight of cyclopentanone to prepare a liquid crystal coating solution. . Then, after applying the coating liquid to a base film (norbornene-based resin film: manufactured by Nippon Zeon Co., Ltd., trade name “Zeonex”) with a bar coater, the liquid crystal was aligned by heating and drying at 80° C. for 4 minutes. By irradiating the liquid crystal layer with ultraviolet rays to cure the liquid crystal layer, a liquid crystal solidified layer (thickness: 1.10 μm) serving as the second retardation layer was formed on the base film. Re (550) of this liquid crystal solidified layer was 0 nm, Rth (550) was -100 nm, and exhibited refractive index characteristics of nz > nx = ny.

[Formula I]

(Manufacture of polarizing plate with retardation layer)

With respect to the laminate of the PET film and the polarizer obtained in the same manner as in Example 1, the liquid crystal solidified layer was removed through the UV curable adhesive on the side opposite to the PET film, and the peeling direction and polarizer of the base film when the base film was removed were bonded so that the absorption axes of were substantially parallel. In addition, the angle of the slow axis and the absorption axis of the polarizer is substantially They were bonded together at an angle of 45°. Furthermore, after peeling the PET film from this layered product, an acrylic protective film or a retardation layer was bonded together as needed through a UV curable adhesive to prepare a polarizing plate with a retardation layer.

(Production of liquid crystal display device)

A liquid crystal display device was produced in the same manner as in Example 1 except that the polarizing plate with the retardation layer was used and a smartphone provided with a different backlight was used. A white image was displayed on the liquid crystal display device, and visibility through polarized sunglasses was evaluated for the state of the white image. Table 1 shows the evaluation results.

<Example 4>

(Manufacture of retardation film (C) constituting first retardation layer)

After vacuum drying the polycarbonate resin obtained in the same manner as in Example 1 at 80 ° C. for 5 hours, a single screw extruder (manufactured by Isuzu Chemical Co., Ltd., screw diameter 25 mm, cylinder setting temperature: 220 ° C.), T-die (width 900 mm, setting A polycarbonate resin film having a thickness of 130 μm was produced using a film forming apparatus equipped with a temperature: 220° C.), a chilled roll (set temperature: 125° C.), and a winder. The water absorption of the obtained polycarbonate resin film was 1.2%.

The polycarbonate resin film was obliquely stretched by a method according to Example 1 of Japanese Unexamined Patent Publication No. 2014-194483 to obtain a phase difference film (C).

The specific manufacturing process of the retardation film (C) is as follows: A polycarbonate resin film (thickness of 130 μm, width of 765 mm) was preheated to 142° C. in a preheating zone of a stretching device. In the warm-up zone, the clip pitch of the left and right clips was 125mm. Next, as soon as the film entered the first oblique drawing zone C1, the increase in the clip pitch of the right clip was started and increased from 125 mm to 177.5 mm in the first oblique drawing zone C1. The clip pitch change rate was 1.42. For the clip pitch of the left clip in the first oblique drawing zone C1, the clip pitch was started to decrease and decreased from 125 mm to 90 mm in the first oblique drawing zone C1. The clip pitch change rate was 0.72. In addition, as soon as the film entered the second oblique stretching zone C2, the clip pitch of the left clip started to increase, and was increased from 90 mm to 177.5 mm in the second oblique stretching zone C2. Meanwhile, the clip pitch of the right clip was maintained at 177.5 mm in the second oblique drawing zone (C2). In addition, at the same time as the oblique stretching, stretching was performed in the width direction by 1.9 times. In addition, the oblique stretching was performed at 135°C. Next, in the shrinkage zone, MD shrinkage treatment was performed. Specifically, the clip pitches of both the left and right clips were reduced from 177.5mm to 165mm. The shrinkage rate in the MD shrinkage treatment was 7.0%.

As described above, a retardation film (C) (thickness: 40 µm) was obtained. Re(550) of the obtained retardation film (C) was 140 nm, Rth(550) was 168 nm, and Re(450)/Re(550) was 0.89. The direction of the slow axis of the retardation film (C) was 45° with respect to the longitudinal direction.

(Production of polarizing plate with phase difference layer and liquid crystal display device)

A polarizing plate with a retardation layer was prepared in the same manner as in Example 1 except that the retardation film (C) was used instead of the retardation film (A), and a liquid crystal display was carried out in the same manner as in Example 1 except that the polarizing plate with a retardation layer was used. device was fabricated. A white image was displayed on the liquid crystal display device, and visibility through polarized sunglasses was evaluated for the state of the white image. Table 1 shows the evaluation results.

<Comparative Example 1>

(Manufacture of retardation film (D) constituting first retardation layer)

A biaxially oriented polypropylene film (manufactured by Toray, trade name "Trepan" (thickness: 60 μm)) is bonded to both sides of a commercially available Aton film (manufactured by JSR Co., Ltd., thickness 70 μm) with an acrylic pressure-sensitive adhesive layer (thickness 15 μm) interposed therebetween. did Thereafter, the longitudinal direction of the film was maintained in a roll stretching machine, and the film was stretched 1.45 times in an air circulation constant temperature oven at 147° C. to obtain a retardation film (D). Re(550) of the obtained retardation film (D) was 140 nm, Rth(550) was 70 nm, and Re(450)/Re(550) was 1.00.

(Production of polarizing plate with phase difference layer and liquid crystal display device)

A polarizing plate with a retardation layer was produced in the same manner as in Example 1 except that the retardation film (D) was used instead of the retardation film (A), and a liquid crystal display was carried out in the same manner as in Example 1 except for using the polarizing plate with a retardation layer. device was fabricated. A white image was displayed on the liquid crystal display device, and visibility through polarized sunglasses was evaluated for the state of the white image. Table 1 shows the evaluation results.

<Comparative Example 2>

(Production of retardation film (E) constituting the first retardation layer)

A commercially available Aton film (manufactured by JSR, thickness 100 μm) was stretched 1.8 times in an air circulation constant temperature oven at 147 ° C while maintaining the longitudinal direction of the film in a roll stretching machine to obtain a phase difference film (E). Re (550) of the obtained retardation film (E) was 140 nm, Rth (550) was 140 nm, and Re (450)/Re (550) was 1.00.

(Manufacture of polarizing plate with retardation layer)

A polarizing plate with a retardation layer was produced in the same manner as in Example 1 except for using the retardation film (E).

(Production of liquid crystal display device)

A liquid crystal panel is taken out from a liquid crystal display device of a smartphone (iphone 5 manufactured by Apple Inc., the emission spectrum of the backlight is continuous) having an IPS type liquid crystal display device, and the polarizing plate disposed on the viewing side of the liquid crystal cell is removed, and the corresponding The glass surface of the liquid crystal cell was washed. Subsequently, the polarizer-side surface of the polarizing plate with a retardation plate was laminated on the surface of the liquid crystal cell on the visual side so that the absorption axis of the polarizer was orthogonal to the initial orientation direction of the liquid crystal cell, with an acrylic pressure-sensitive adhesive (thickness: 20 µm) interposed therebetween. Thus, a liquid crystal panel was obtained. The liquid crystal panel on which the polarizing plate with the retardation plate was laminated was attached to the smart phone to obtain a liquid crystal display device of this embodiment. A white image was displayed on the liquid crystal display device, and visibility through polarized sunglasses was evaluated for the state of the white image. Table 1 shows the evaluation results.

<Comparative Example 3>

(Manufacture of retardation film (F) constituting first retardation layer)

Phosgene as carbonate precursor, (A) 2,2-bis(4-hydroxyphenyl)propane and (B) 1,1-bis(4-hydroxyphenyl)-3,3,5 as aromatic dihydric phenol component -Polycarbonate comprising repeating units of the following formulas II and formula III having a weight average molecular weight (Mw) of 60,000 at a weight ratio of (A):(B) of 4:6 according to a conventional method using trimethylcyclohexane A system resin [number average molecular weight (Mn) = 33,000, Mw/Mn = 1.78] was obtained. 70 parts by weight of the polycarbonate-based resin and 30 parts by weight of a styrenic resin having a weight average molecular weight (Mw) of 1,300 [number average molecular weight (Mn) = 716, Mw / Mn = 1.78] (Sanyo Kasei, Hymer SB75) 30 parts by weight of dichloromethane 300 It was added by weight and stirred and mixed at room temperature for 4 hours to obtain a transparent solution. This solution was cast on a glass plate, left at room temperature for 15 minutes, then peeled from the glass plate and dried in an oven at 80°C for 10 minutes and at 120°C for 20 minutes to obtain a thickness of 40 µm and a glass transition temperature (Tg) of 140°C. A polymer film was obtained. The light transmittance at a wavelength of 590 nm of the obtained polymer film was 93%. In addition, the in-plane retardation value: Re (590) of the polymer film was 5.0 nm, and the retardation value in the thickness direction: Rth (590) was 12.0 nm. The average refractive index was 1.576.

The obtained polymer film was uniaxially stretched 1.5 times in an air circulation constant temperature oven at 150°C to obtain a phase difference film (F). Re (550) of the obtained retardation film (F) was 140 nm, Rth (550) was 140 nm, and Re (450)/Re (550) was 1.06.

[Formula II]

[Formula III]

(Production of polarizing plate with phase difference layer and liquid crystal display device)

A polarizing plate with a retardation layer was prepared in the same manner as in Example 1 except that the retardation film (F) was used instead of the retardation film (A), and a liquid crystal display was carried out in the same manner as in Example 1 except for using the polarizing plate with a retardation layer. device was fabricated. A white image was displayed on the liquid crystal display device, and visibility through polarized sunglasses was evaluated for the state of the white image. Table 1 shows the evaluation results.

[Table 1]

The liquid crystal display device of the present invention is suitable for portable devices such as personal digital assistants (PDAs), mobile phones, watches, digital cameras, and portable game machines, OA devices such as computer monitors, notebooks, copy machines, video cameras, liquid crystal TVs, and microwave ovens. Household electrical equipment, bag monitors, monitors for car navigation systems, automobile equipment such as car audio, display equipment such as information monitors for commercial stores, security equipment such as monitoring monitors, nursing care monitors, medical monitors, etc. It can use suitably for various uses, such as an apparatus.

10: liquid crystal cell
11: Substrate
12: substrate
13: liquid crystal layer
20: first polarizer
30: second polarizer
100: liquid crystal panel
200: phase difference layer (first phase difference layer)
300: back light source
400: another retardation layer (second retardation layer)
500: liquid crystal display

Claims (6)

a liquid crystal panel including a liquid crystal cell, a first polarizer disposed on a viewing side of the liquid crystal cell, and a second polarizer disposed on a rear side of the liquid crystal cell;
a retardation layer disposed on a viewing side of the liquid crystal panel; and
A backlight source for illuminating from the rear side of the liquid crystal panel,
The in-plane retardation Re (550) of the retardation layer is 100 nm to 180 nm, and the relationship of Re (450) < Re (550) < Re (650) is satisfied,
An angle between a slow axis of the retardation layer and a long side of the liquid crystal panel is 35° to 55°,
The backlight light source has a discontinuous emission spectrum,
The emission spectrum of the backlight source has a peak P1 in the wavelength range of 430 nm to 470 nm, a peak P2 in the wavelength range of 530 nm to 570 nm, and a peak P3 in the wavelength range of 630 nm to 670 nm,
The wavelength of peak P1 is λ1, the height is hP1 and the full width at half maximum is Δλ1, the wavelength of peak P2 is λ2, the height is hP2 and the full width at half maximum is Δλ2, the wavelength of peak P3 is λ3, the height is hP3 and the full width at half maximum is Δλ3, peak P1 and peak P2 A liquid crystal display device that satisfies the following relational expressions (1) to (3), when hB1 is the height of the valley between peaks and hB2 is the height of the valley between peaks P2 and P3:
(λ2-λ1 )/(Δλ2+Δλ1)>1...(1)
(λ3-λ2)/(Δλ3+Δλ2)>1...(2)
0.8≤{hP2-(hB2+hB1)/2}/hP2≤1...(3) According to claim 1,
The liquid crystal display device in which the refractive index ellipsoid of the retardation layer represents a relationship of nx>nz>ny, and the Nz coefficient is 0.2 to 0.8. According to claim 1,
A liquid crystal display device further comprising another retardation layer in which a refractive index ellipsoid exhibits a relationship of nz > nx ≥ ny, between the liquid crystal panel and the retardation layer. According to claim 1,
The liquid crystal display device according to claim 1 , wherein the backlight source includes a red-emitting LED, a green-emitting LED, and a blue-emitting LED, and phosphors of the red-emitting LED are activated by tetravalent manganese ions. According to claim 1,
The liquid crystal display device wherein the backlight source includes a wavelength conversion layer including an LED emitting blue color and a quantum dot. According to claim 1,
An absorption axis of the first polarizer is substantially orthogonal or parallel to a long side of the liquid crystal panel, an absorption axis of the second polarizer is substantially orthogonal or parallel to a long side of the liquid crystal panel, and A liquid crystal display device in which an absorption axis of and an absorption axis of the second polarizer are substantially orthogonal.