TW202122840A - Image display device - Google Patents

Abstract

An object of the present invention is to provide an image display device capable of further suppressing an oblique color difference.

As a solution, the image display device according to one embodiment includes a light-reflecting image display layer, a retardation film, and a polarizing film, wherein the angle between the absorption axis of the polarizing film and the in-plane slow phase axis of the retardation film is 45 degrees ± 5 degrees. When the in-plane retardation of the retardation film is R0, the plane orthogonal to the direction having an inclination angle θ with respect to the thickness direction of the retardation film is the projection plane, assuming that the in-plane advance phase axis and the in-plane slow phase axis of the retardation film are the rotation axes, the in-plane retardations of the retardation film on the projection plane are R(θ)_fast and R(θ)_slow, and the in-plane retardation of the light-reflecting image display layer on the projection plane is R(θ)M, the following equations (i) to (iv) are satisfied.

α=R0-{R(θ)_fast+R(θ)M}‧‧‧(i)

β=R0-{R(θ)_slow-R(θ)M}‧‧‧(ii)

｜α(θ)｜+｜β(θ)｜<10nm‧‧‧(iii)

｜R(θ)M｜>0nm‧‧‧(iv)

Description

Image display device

The present invention relates to an image display device.

For the optical compensation of the display device, an optical laminate in which a retardation film and a polarizing film are laminated is installed in the flat display device. For example, among flat-panel display devices, organic electroluminescence (EL) image display devices are incident light from the outside, in order to reflect light toward the viewing side by incorporating the light reflective image display layer inside. The internal reflected light is reduced, and such an optical laminate is laminated on the viewing side of the light-reflective image display layer and used. Such an optical laminated system is described in, for example, the elliptically polarizing plate of Patent Document 1.

[Prior Technical Literature]

[Patent Literature]

[Patent Document 1] JP 2015-163940 A

Among the flat-panel display devices, for example, the organic EL image display device is the case of viewing the screen from the front direction and the case of viewing the screen from the oblique direction. The reflective image display layer from the inside is slightly reflected to reach the viewing angle. The reflected color of the internal reflected light on the side is different, and furthermore, the reflected color corresponding to the in-plane angle is generated in the oblique direction. The maximum value of the chromatic aberration of the reflected color corresponding to the in-plane angle in the oblique direction is called oblique chromatic aberration. On the image display surface of the display device, an optical laminate as described in Patent Document 1 is arranged to suppress oblique chromatic aberration. However, in recent years, it is required to further suppress the oblique chromatic aberration.

Therefore, the object of the present invention is to provide an image display device capable of suppressing oblique chromatic aberration more.

An image display device according to one aspect of the present invention includes a light-reflective image display layer, and a retardation film and a polarizing film provided on the image display surface of the light-reflective image display layer. The angle formed by the absorption axis of the polarizing film and the in-plane slow axis of the retardation film is 45 degrees ± 5 degrees, and the in-plane retardation of the retardation film is set to R0, and the sum of the retardation film is relative to the thickness direction The plane orthogonal to the direction of the tilt angle θ is set as the projection plane, and when the in-plane fast axis of the retardation film is assumed to be the rotation axis, the in-plane retardation of the retardation film on the projection plane is R( θ ) _fast , when the in-plane slow axis of the retardation film is assumed to be the axis of rotation, the in-plane retardation of the retardation film on the projection surface is set to R( θ ) _slow , and the above-mentioned When the in-plane retardation of the light-reflective image display layer is set to R( θ )M, the following equations (i) to (iv) are satisfied.

α=R0-{R( θ ) _fast +R( θ )M)‧‧‧(i)

β=R0-{R(θ) _slow -R( θ )M}‧‧‧(ii)

｜α( θ )｜+｜β( θ )｜<10nm‧‧‧(iii)

｜R( θ )M｜>0nm‧‧‧(iv)

The above configuration takes into consideration the in-plane retardation of the retardation film and the in-plane retardation of the light-reflective image display layer. Therefore, by providing the retardation film and the polarizing film on the light reflection image display layer, oblique chromatic aberration can be sufficiently suppressed.

The R0, the R( θ ) _fast , the R( θ ) _slow, and the R( θ )M system may be retardation at a wavelength of 550 nm, for example.

The above-mentioned inclination angle θ may be 50 degrees.

An image display device according to another aspect of the present invention includes a light-reflective image display layer, a retardation film and a polarizing film provided on the image display surface of the light-reflective image display layer, and the polarized light The angle formed by the absorption axis of the film and the in-plane slow axis of the retardation film is 45 degrees ± 5 degrees, the in-plane retardation of the retardation film is set to R0, and the retardation in the thickness direction of the retardation film is set to Rth, the surface of the retardation film perpendicular to the direction at an inclination angle of 50 degrees with respect to the thickness direction is defined as a projection surface, and the in-plane retardation of the light reflective image display layer on the projection surface is defined as R (50) M, when Nz and ρ are expressed by formulas (v) and (vi), Nz and ρ satisfy formula (vii), formula (viii) and formula (ix), or satisfy formula ( vii), formula (x) and formula (xi), the above-mentioned R0, the above-mentioned Rth, and the above-mentioned R(50)M are retardation to the wavelength of 550nm.

Nz=(Rth/R0)+0.5‧‧‧(v)

ρ =R(50)M/R0‧‧‧(vi)

3.5ρ+0.39<Nz<3.5ρ+0.65‧‧‧(vii)

ρ >0‧‧‧(viii)

0.5<Nz≦1.5‧‧‧(ix)

ρ <0‧‧‧(x)

-1.5<Nz<0.5‧‧‧(xi)

In the above configuration, the in-plane retardation of the light-reflective image display layer is also considered. Therefore, by providing the retardation film and the polarizing film on the light reflection image display layer, oblique chromatic aberration can be sufficiently suppressed.

The above-mentioned retardation film system may have an A plate and a C plate.

The above-mentioned retardation film and the above-mentioned polarizing film system may constitute a circular polarizing plate.

According to the present invention, it is possible to provide an image display device capable of suppressing oblique chromatic aberration.

2: Image display device

4: Image display layer (light reflective image display layer)

12: retardation film

12a: Slow axis (in-plane slow axis)

12b: fast axis (in-plane fast axis)

14: Polarizing film

14a: Absorption axis

18: A board

20: C board

22: projection surface

FIG. 1 is a schematic diagram showing a schematic configuration of an embodiment of an image display device.

Fig. 2 is a diagram showing the relationship between the slow axis, the fast axis, and the absorption axis of the polarizing film.

Figure 3 is a diagram for explaining the projection surface.

Fig. 4 is a diagram for explaining the phase difference of the oblique field of view.

Fig. 5 is a graph showing the results shown in Table 5 to Table 7 plotted on the ρ- Nz coordinate system.

Hereinafter, the embodiments of the present invention will be described with reference to the drawings. The same elements are given the same symbols, and repeated descriptions are omitted. The size ratio of the drawings may not be consistent with the description.

FIG. 1 is a schematic diagram showing a schematic configuration of an image display device 2 of an implementation type. The image display device 2 has an image display layer (light reflective image display layer) 4 and an optical laminate 6. The image display layer 4 and the optical laminate 6 are joined together. In the form shown in Figure 1, the image display layer 4 and the light The laminated body 6 is joined by an adhesive (pressure-sensitive adhesive, also called pressure-sensitive adhesive) layer 8a.

The image display layer 4 forms an image inside, and displays the image on the image display surface 4a. The image display layer 4 includes an element structure for forming an image and the like. Therefore, the electrodes contained in the above-mentioned element structure, wiring between the element structures, etc., function as a reflection portion that reflects light. Therefore, the image display layer 4 has light reflectivity for reflecting light incident on the image display device 2 from the optical laminate 6 side. The thickness of the image display layer 4 is, for example, 0.2 mm to 1.0 mm.

The image display layer 4 may be configured to form an image on the image display surface 4a, and the layer configuration, material, and the like are not limited. The image display layer 4 may be, for example, gold, silver, copper, iron, nickel, chromium, molybdenum, titanium, aluminum, indium, and other metals, and a portion formed from electrodes and wirings using alloys and oxides of them, etc. (Or layer), a multi-layered body such as a dielectric part such as a resin film, a partition wall material, a light-emitting element, and other layers.

The image display layer 4 is, for example, a flat display device. Examples of flat display devices include thin (or panel-shaped) organic electroluminescent display devices (hereinafter, also referred to as "OLED display devices"), and inorganic electroluminescent devices with independent light-emitting pixels (hereinafter, also referred to as "Micro LED display device"). The display device exemplified as the image display layer 4 is on the image display surface and does not include a device for optical compensation.

When the image display layer 4 is an OLED display device, generally the electrode provided in the OLED display device is the above-mentioned reflecting part. The OLED display device has a thin-film structure sandwiching an organic light-emitting material layer between a pair of electrodes facing each other. In the organic light-emitting material layer, electrons are injected from one electrode, and at the same time, holes are injected from the other electrode, whereby the electrons and holes in the organic light-emitting material layer are combined to emit light by themselves. Among the two electrodes sandwiching the organic light-emitting material layer, the electrode on the image display surface 4a side has a The light from the organic light-emitting material layer has the function of penetrating. On the other hand, the other electrode has the function of reflecting the light from the organic light-emitting material layer toward the image display surface 4a. Therefore, the above-mentioned other electrode generally functions as a reflection part in an OLED display device.

Compared with liquid crystal display devices, etc., which must have a backlight, OLED display devices have the advantages of better visibility, thinner profile, and low-voltage direct current driving.

When the image display layer 4 is a micro LED display device, the light-emitting portion and the pixel connection portion and the electrode portion formed of a compound semiconductor reflect external light. Therefore, in the micro LED display device, the light-emitting part, the pixel connection part, and the electrode part correspond to the reflection part.

[Adhesive layer]

The adhesive layer 8a can be composed of, for example, (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resins as the main component of an adhesive composition. Among them, an adhesive composition using a (meth)acrylic resin excellent in transparency, weather resistance, heat resistance, etc., as a base polymer is suitable. The adhesive composition system can be an active energy ray hardening type or a heat hardening type. The thickness of the adhesive layer 8b is usually 3 μm to 30 μm, preferably 3 μm to 25 μm.

The (meth)acrylic resin (base polymer) used in the adhesive composition, for example, can be suitably used such as butyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylic acid. One or two or more of isooctyl ester and 2-ethylhexyl (meth)acrylate (meth)acrylate are polymers or copolymers of monomers. The base polymer preferably copolymerizes polar monomers. Examples of polar single systems include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, (meth)acrylic acid N, A monomer having a carboxyl group, a hydroxyl group, an amino group, an amino group, an epoxy group, etc., of N-dimethylamino ethyl ester and glycidyl (meth)acrylate.

The adhesive composition may contain only the above-mentioned base polymer, but usually contains a crosslinking agent. Examples of crosslinking agents are those that are metal ions having a valence of two or more and form metal carboxylic acid salts with the carboxyl group; those that are polyamine compounds and form an amide bond with the carboxyl group; are polyepoxy compounds or It is a polyol and forms an ester bond with a carboxyl group; it is a polyisocyanate compound and forms an amide bond with a carboxyl group. Among them, polyisocyanate compounds are preferred.

[Optical Laminate]

The optical layered body 6 has a polarizing plate 10 and a retardation film 12. The optical laminate 6 is an optical element for compensating the image displayed on the image display surface 4a. The polarizing plate 10 and the retardation film 12 are joined together. The polarizing plate 10 and the retardation film 12 are shown in FIG. 1 and can be joined by an adhesive layer 8b. The example of the adhesive layer 8b is the same as the case of the adhesive layer 8a.

[Polarizer]

The polarizing plate 10 has a polarizing film 14. The polarizing plate 10 may further have two protective films 16. The polarizing plate 10 will be described based on the form illustrated in FIG. 1.

The polarizing film 14 has linear polarization characteristics. An example of the polarizing film 14 is a film in which a dichroic dye is adsorbed and oriented on a uniaxially stretched resin film. The polarizing film 14 is not particularly limited as long as it is a resin film having linear polarization characteristics, and it may be used for a conventional polarizing plate.

Examples of the resin film possessed by the polarizing film 14 include polyvinyl alcohol (hereinafter, sometimes referred to as "PVA") resin film, polyvinyl acetate resin film, ethylene/vinyl acetate resin film, and polyamide resin film. And polyester resin film. Generally, from the viewpoint of the adsorbability and orientation of the dichroic dye, a PVA-based resin film can be used, and a PVA film can be used in particular.

The two protective films 16 sandwich the polarizing film 14 and protect the polarizing film 14. Each of the two protective films 16 is, for example, a resin film (for example, triacetyl cellulose (hereinafter, also referred to as "TAC") film) ,glass Glass cover or glass film. The materials of the two protective films 16 may be the same or different. The number of the protective film 16 may be one. For example, the polarizing plate 10 may not have the protective film 16 on the side of the retardation film 12.

The polarizing plate 10 is prepared by preparing a long member, and after each member is laminated on a roll-to-roll basis, it can be cut into a predetermined shape to be manufactured, or each member can be cut into a predetermined shape by making it Manufactured by fitting.

[Retardation film]

The retardation film 12 has a function of generating a certain retardation for incident light. The retardation film 12 is shown in FIG. 2 and has a slow axis (in-plane slow axis) 12a and a fast axis (in-plane fast axis) 12b in the film plane. The angle between the slow axis 12a and the fast axis 12b is approximately 90 degrees. The so-called about 90 degrees means 90 degrees ± 5 degrees.

In the retardation film 12, the slow axis 12a is arranged so as to be approximately 45 degrees with respect to the absorption axis 14a of the polarizing film 14 shown by a broken line in FIG. 2. The so-called about 45 degrees means 45±5 degrees.

Returning to FIG. 1, the retardation film 12 will be further described. The retardation film 12 is joined to the polarizing plate 10. In the form illustrated in FIG. 1, the retardation film 12 is bonded to the polarizing plate 10 through the adhesive layer 8 b. The example of the adhesive layer 8b is the same as the case of the adhesive layer 8a.

The retardation film 12 has an A plate (phase difference film layer) 18 and a C plate (phase difference film layer) 20. The A plate 18 and the C plate 20 are joined. In the form shown in FIG. 1, the A plate 18 and the C plate 20 are joined by the adhesive layer 8c. In this embodiment, the slow axis 12 a and the fast axis 12 b of the retardation film 12 are the slow axis and the fast axis in the plane of the A plate 18. In addition, the phase difference of the C plate 20 in the plane is substantially 0 (zero), and there is no slow axis and fast axis in the plane. Hereinafter, unless otherwise stated, when describing the refractive index anisotropy of the A plate 18 and the C plate 20, the slow axis 12a and the fast axis 12b shown in FIG. 2 are used.

[A board]

The A plate 18 preferably has the characteristics shown in the following formulas (1) to (3). The A plate 18 may be a positive A plate, and may be a λ/4 plate. In addition, the A plate 18 preferably exhibits reverse wavelength dispersion. With such A plate 18, the coloring of reflected light can be suppressed. In this embodiment, the slow axis (slow axis 12a) of the A plate 18 is arranged to be approximately 45 degrees with respect to the absorption axis of the polarizing film 14. The meaning of about 45 degrees is as mentioned above.

nx>ny≒nz...(1)

0.80<R0A(450)/R0A(550)<0.93...(2)

130nm<R0A(550)<150nm...(3)

In equations (1) to (3), nx represents the refractive index in the direction of the slow axis 12a, ny represents the refractive index in the direction of the fast axis 12b, and nz represents the thickness direction of the A plate 18 (and the slow axis 12a and fast axis 12a). The direction perpendicular to the axis 12b). R0A(λ) represents the retardation of the wavelength λ nm of the A plate 18. Therefore, ROA (450) and ROA (550) in equations (2) and (3) represent the retardation at the wavelength of 450 nm and the wavelength of 550 nm.

ny≒nz is not only the case where ny and nz are completely equal, but also the case where ny and nz are substantially equal. Specifically, if the difference between ny and nz is within 0.01, it can be said that ny and nz are substantially equal.

R0A(λ) can be calculated from the refractive index n(λ) of the wavelength λ nm and the thickness d1 of the A plate 18 according to the following formula.

R0A(λ)=[nx(λ)-ny(λ)]×d1

R0A(450)/R0A(550) represents the wavelength dispersion of the A plate 18, and is preferably 0.92 or less.

For the retardation R0A(λ) of the A plate 18 with a wavelength of λ nm, R0A(450) is preferably 100nm or more and 135nm or less, R0A(550) is preferably 137nm or more and 145nm or less, and R0A(650) is 137 The above 165 is preferable. R0A (650) represents the retardation at a wavelength of 650nm.

[C plate]

The C plate 20 preferably has the characteristics shown in the following formula (4).

The C-plate 20 series can be a positive C-plate. With such a C plate 20, the coloration of reflected light can be suppressed.

nx≒ny<nz...(4)

In formula (4), nx represents the refractive index in the direction of the slow axis 12a, ny represents the refractive index in the direction of the fast axis 12b, and nz represents the thickness direction of the C plate 20 (positive to the slow axis 12a and the fast axis 12b). Direction) refractive index.

In addition to the case where nx and ny are completely equal, nx≒ny also includes the case where nx and ny are substantially equal. Specifically, if the difference between nx and ny is within 0.01, it can be said that nx and ny are substantially equal.

Although it depends on the reflection characteristics of the image display layer 4, specifically, the retardation in the thickness direction of the C plate 20 is at a wavelength of 550 nm, preferably -120 nm or more and 0 nm or less, and more preferably -110 nm or more and -10 nm or less. It is more preferably above -90nm and below -20nm.

When the thickness direction retardation of the C plate 20 to the light of wavelength λ [nm] is set to RthC(λ), RthC(λ) can be based on the refractive index n(λ) of the wavelength λ nm and the thickness d2 of the C plate 20 Calculated by the following formula.

RthC(λ)={[nx(λ)+ny(λ)]/2-nz(λ)}×d2

RthC(450)/RthC(550) represents the wavelength dispersion of the C plate 20, and is preferably 1.5 or less, more preferably 1.1 or less. RthC (450) and RthC (550) are the retardation of the C plate 20 in the thickness direction with a wavelength of 450 nm and a wavelength of 550 nm, respectively.

In this embodiment, the thickness of the A plate 18 and the C plate 20 can be set to 0.1 μm or more and 5 μm or less. If the thickness of the A plate 18 and the C plate 20 is within this range, sufficient durability can be obtained, which can be It contributes to the thinning of the optical laminate 6. Of course, the thickness of the A plate 18 and the C plate 20 is such that the desired retardation of the layer imparting a phase difference of λ/4, the layer imparting a phase difference of λ/2, the positive A plate, or the positive C plate, etc., can be obtained. And the delay in the thickness direction.

[Adhesive layer]

The adhesive layer 8c should just be formed with the adhesive used for the conventional retardation film. Examples of the adhesive system include water-based adhesives and active energy ray-curable adhesives. Instead of the adhesive layer 8c, the same adhesive layer as the adhesive layer 8b may be used.

[Method of forming retardation film]

The A plate 18 and the C plate 20 included in the retardation film 12 can be formed of a composition containing a thermoplastic resin or a polymerizable liquid crystal compound described later. The A plate 18 and the C plate 20 are preferably formed of a composition containing a polymerizable liquid crystal compound. Examples of the layer formed of the composition containing the polymerizable liquid crystal compound include a cured layer of the polymerizable liquid crystal compound.

The relationship between formula (1) to formula (3) satisfied by the A plate 18 and the formula (4) satisfied by the C plate 20 are, for example, by adjusting the thermoplastic resin or polymerizable liquid crystal compound that forms the A plate 18 and the C plate 20 The type and the ratio of blending, or adjust the thickness of the A plate 18 and the C plate 20 to control.

The cured layer of the polymerizable liquid crystal compound is, for example, formed on an alignment film (also called an alignment film) provided on a substrate. The substrate has the function of supporting the oriented film, and can be a long substrate. The substrate can function as a release support and support the retardation film 12 for transfer. Furthermore, it is preferable to have an adhesive force to the extent that the surface can be peeled off. As the base material, a resin film is exemplified as a material of the above-mentioned protective film.

The thickness of the substrate is not particularly limited, but it is preferably set to a range of 20 μm or more and 200 μm or less, for example. If the thickness of the substrate is 20 μm or more, strength can be imparted. On the other hand, if thick With a degree of 200μm or less, when cutting the processed base material as the base material of the blade, it can suppress the increase of processing chips and the loss of the cutting knife.

The base material can be subjected to various anti-caking treatments. Examples of the anti-caking treatment system include easy bonding treatment, treatment of mixing fillers, etc., embossing (Knurling treatment), and the like. By applying such anti-caking treatment to the substrate, the adhesion between the substrates when the substrate is wound, so-called agglomeration, can be effectively prevented, and the optical film can be manufactured with high productivity.

The cured layer of the polymerizable liquid crystal compound is formed on the substrate via the alignment film. That is, the substrate and the oriented film are laminated in the order, and the hardened layer of the polymerizable liquid crystal compound is laminated on the aforementioned oriented film.

The alignment film is not limited to the vertical alignment film, and may be an alignment film that aligns the molecular axis of the polymerizable liquid crystal compound horizontally, or may be an alignment film that aligns the molecular axis of the polymerizable liquid crystal compound obliquely. When the A plate 18 is produced, a horizontally oriented film can be used, and when the C plate 20 is produced, a vertical oriented film can be used. The alignment film has insoluble solvent resistance by coating or the like of a composition containing a polymerizable liquid crystal compound described later, and preferably has heat resistance for solvent removal or heat treatment for the alignment liquid crystal compound. Examples of the oriented film system include oriented films containing oriented polymers, and grooved oriented films in which concave-convex patterns or plural grooves are formed on the light-oriented film and the surface and oriented. The thickness of the alignment film is usually in the range of 10 nm to 10000 nm, preferably in the range of 10 nm to 1000 nm, more preferably in the range of 500 nm or less, and more preferably in the range of 10 nm to 200 nm.

The resin used for the oriented film is not particularly limited as long as it is the resin used as the material of the conventional oriented film. A conventionally known monofunctional or polyfunctional (meth)acrylate monomer can be used. The body is cured under the polymerization initiator, etc. Specifically, the (meth)acrylate-based single system can be exemplified as: 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono-2- Ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate, lauryl acrylate, lauryl methacrylate, isoacrylate Camphenyl ester, isobornyl methacrylate, 2-phenoxyethyl acrylate, methyl tetrahydrofuran acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, methyl tetrahydrofuran methacrylate, 2-hydroxyethyl methacrylate Ester, benzyl methacrylate, cyclohexyl methacrylate, methacrylic acid, urethane acrylate, etc. In addition, the resin system may be one type of these, or a mixture of two or more types.

The light alignment film is formed by a composition containing a polymer or monomer having a photoreactive group and a solvent. The so-called photoreactive group is a group that generates the orientation energy of liquid crystal by light irradiation. Specifically, it can be exemplified by the orientation induction of molecules generated by light irradiation or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photolysis reaction, etc., which participate in the photoreaction base that forms the origin of the orientation energy of the liquid crystal. Among them, a group that participates in a dimerization reaction or a photocrosslinking reaction is preferable in terms of excellent orientation. As far as photoreactive groups are concerned, unsaturated bonds, especially groups with double bonds are preferred, and groups with carbon-carbon double bonds (C=C bonds) and carbon-nitrogen double bonds (C=N bonds) are preferred. , Nitrogen-nitrogen double bond (N=N bond) and carbon-oxygen double bond (C=O bond) at least one group is particularly preferred.

(formazan)、及具有氧偶氮(azoxy)苯構造之基等。具有C=O鍵之光反應性基係可列舉二苯甲酮基、香豆素基、蒽醌基及馬來醯亞胺基等。此等基係可具有烷基、烷氧基、芳基、烯丙氧基、氰基、烷氧基羰基、羥基、磺酸基、鹵烷基等取代基。 The photoreactive group with C=C bond includes vinyl group, polyalkenyl group, stilbazole group, 4-(2-styrene) pyridine (Stilbazole) group, 4-(2-styrene) pyridinium group , Chalcone base and cinnamon base etc. Examples of the photoreactive group system having a C=N bond include groups having structures such as an aromatic Schiff base (Schiff base) and an aromatic hydrazone (hydrazone). The photoreactive groups with N=N bond are azophenyl, azonaphthyl, aromatic heterocyclic azo, bisazo, methyl

(formazan), and a base with azoxy benzene structure, etc. Examples of the photoreactive group system having a C=O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and haloalkyl groups.

Among them, the photoreactive group participating in the photodimerization reaction is preferred. From the viewpoint of easily obtaining a light alignment film that requires less polarized light irradiation and excellent thermal stability or stability over time, Cinnamyl and chalcone groups are preferred. The polymer having a photoreactive group is particularly preferably one having a cinnamic acid structure at the end of the polymer side chain.

The type of polymerizable liquid crystal compound used in this embodiment is not particularly limited, but from its shape, it can be classified into rod-shaped (rod-shaped liquid crystal compound) and disc-shaped (disc-shaped liquid crystal compound, disc-shaped liquid crystal compound). Liquid crystal compound). Furthermore, there are low-molecular type and high-molecular type. In addition, the so-called polymer generally refers to those with a degree of polymerization of 100 or more (refer to "Polymer Physics-Phase Transfer Dynamics, by Masao Doi, page 2, Iwanami Shoten, 1992").

Any polymerizable liquid crystal compound can also be used in this embodiment. Furthermore, two or more rod-shaped liquid crystal compounds, or two or more discotic liquid crystal compounds, or a mixture of rod-shaped liquid crystal compounds and discotic liquid crystal compounds can be used.

Examples of rod-shaped liquid crystal compounds include those described in Claim 1 of Japanese Patent Application Publication No. 11-513019, or paragraphs [0026] to [0098] of Japanese Patent Application Publication No. 2005-289980, which can be suitably used. For the discotic liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP 2007-108732 A, or paragraphs [0013] to [0108] of JP 2010-244038 A can be suitably used. .

Two or more types of polymerizable liquid crystal compounds can be used in combination. At this time, at least one type has two or more polymerizable groups in the molecule. In other words, the cured layer of the polymerizable liquid crystal compound is preferably a layer formed by fixing the liquid crystal compound having a polymerizable group by polymerization. At this time, it is no longer necessary to display liquid crystallinity after becoming a layer.

The polymerizable liquid crystal compound has a polymerizable group capable of undergoing a polymerization reaction. The polymerizable group is preferably, for example, a functional group capable of addition polymerization reaction such as a polymerizable ethylenic unsaturated group or a cyclic polymerizable group.

More specifically, the polymerizable group system includes, for example, (meth)acryloyl group, vinyl group, styryl group, and allyl group. Among them, a (meth)acryloyl group is preferred. In addition, the so-called (meth)acryloyl group includes both concepts of a methacryloyl group and an acrylic group.

The cured layer of the polymerizable liquid crystal compound is described later, and a composition containing the polymerizable liquid crystal compound can be formed, for example, by coating on an alignment film. The aforementioned composition system may contain components other than the aforementioned polymerizable liquid crystal compound. For example, the aforementioned composition system preferably contains a polymerization initiator. The polymerization initiator used is based on the form of the polymerization reaction, for example, a thermal polymerization initiator or a photopolymerization initiator is selected. For example, the photopolymerization initiator system may include a combination of α-carbonyl compound, acyloin ether, α-hydrocarbon substituted aromatic acyloin compound, polynuclear quinone compound, triarylimidazole dimer and p-aminophenyl ketone Wait. Relative to the total solid content in the aforementioned coating liquid, the amount of the polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass.

In addition, from the viewpoint of uniformity of the coating film and strength of the film, the aforementioned composition system may include a polymerizable monomer. Examples of the polymerizable single system include radically polymerizable or cationically polymerizable compounds. Among them, polyfunctional radical polymerizable monomers are preferred.

The polymerizable monomer is preferably one that can be copolymerized with the above-mentioned polymerizable liquid crystal compound. Specific polymerizable single systems include, for example, those described in paragraphs [0018] to [0020] in Japanese Patent Application Laid-Open No. 2002-296423. Relative to the total mass of the polymerizable liquid crystal compound, the usage amount of the polymerizable monomer is preferably 1 to 50% by mass, and more preferably 2 to 30% by mass.

From the point of the uniformity of the coating film and the strength of the film, the aforementioned composition system may include a surfactant. The surfactant system can be exemplified by conventionally known compounds. Among them, fluorine-based compounds are particularly preferred. Specific surfactant systems include, for example, the compounds described in paragraphs [0028] to [0056] in Japanese Patent Application Publication No. 2001-330725, and paragraphs [0069] to [0126] in Japanese Patent Application Publication No. 2005-62673. Recorded compound.

In addition, the aforementioned composition system may contain a solvent, and it is preferable to use an organic solvent. Examples of organic solvents include amides (e.g., N,N-dimethylformamide), sulfenite (e.g., dimethyl sulfenite), heterocyclic compounds (e.g., pyridine), and hydrocarbons (e.g., benzene). , Hexane), haloalkanes (e.g. chloroform, dichloromethane), esters (e.g. methyl acetate, ethyl acetate, butyl acetate), ketones (e.g. acetone, methyl ethyl ketone), ethers (e.g. tetrahydrofuran, 1 ,2-Dimethoxyethane). Among them, haloalkanes and ketones are preferred. In addition, two or more types of organic solvents can be used in combination.

In addition, the aforementioned composition system may include vertical alignment promoters such as a vertical alignment agent on the polarizing film interface side and a vertical alignment agent on the air interface side, and horizontal alignment promoters such as a horizontal alignment agent on the interface side of the polarizing film and a horizontal alignment agent on the air interface side. Of various directing agents. Furthermore, the aforementioned composition may contain an adhesion improver, a plasticizer, a polymer, etc. in addition to the aforementioned components.

When the retardation film 12 is composed of two or more layers of polymerizable liquid crystal compound cured layers as the A plate 18 and the C plate 20, a cured layer of the polymerizable liquid crystal compound can be formed on the alignment film, and the two are separated by, for example, Then, the agent layer 8c is laminated, whereby the retardation film 12 is manufactured. After the two layers are laminated, the base material and the orientation film can be peeled off. The thickness of the retardation film 12 is preferably 3 to 30 μm, and more preferably 5 to 25 μm.

The retardation film 12 is prepared by preparing a long member, and after each member is laminated on a roll-to-roll basis, it can be cut into a predetermined shape to be manufactured, or the respective member can be cut into a predetermined shape and then laminated. The C plate 20 can be obtained by directly forming the C plate 20 on the A plate 18. That is, the adhesive layer 8c can be omitted.

[Modifications of retardation film]

In addition to the A plate 18 and the C plate 20, the retardation film 12 may be provided with one or more other layers having a retardation (hereinafter, sometimes referred to as "other retardation film layer"). Other retardation film layers include, for example, a touch sensor provided for the image display layer 4, a sealing layer for sealing the image display layer 4, a base film for the image display layer 4, and the like. In addition, the other retardation film layer may be a protective film bonded to the polarizing film 14. The other retardation film layer is arranged between the polarizing film 14 and the image display layer 4, preferably arranged between the image display layer 4 and the A plate 18 or the C plate 20 that is closest to the image display layer 4. between.

The other retardation film layer can be A plate, but usually can be C plate. Other retardation film layers may have the characteristics shown in the following formula (5). That is, the other retardation film layers may be negative C plates.

nx≒ny>nz...(5)

In formula (5), nx represents the refractive index in the direction of the slow axis 12a, ny represents the refractive index in the direction of the fast axis 12b, and nz represents the refractive index in the thickness direction of other retardation film layers.

In formula (5), nx≒ny is not only the case where nx and ny are completely equal, but also the case where nx and ny are substantially equal. Specifically, if the difference between nx and ny is within 0.01, it can be said that nx and ny are substantially equal.

In addition, the retardation film 12 may also include the above-mentioned substrate or orientation film, and may also include a combination other than the A plate and the C plate. Specifically, it can be a combination of two or more A plates.

The image display device 2 may further include at least one of a front panel and a bezel. Explain the front panel and shading pattern separately.

<Front Panel>

The front panel can be arranged on the viewing side of the polarizer 10. The front panel can be laminated on the polarizing plate 10 via an adhesive layer. Examples of the adhesive layer system include the aforementioned adhesive layer 8b or adhesive layer 8c.

Examples of the front panel include those containing a hard coat layer on at least one surface of glass and a resin film. For the glass system, for example, high-penetration glass or strengthened glass can be used. In particular, when a thin transparent surface material is used, chemically strengthened glass is preferred. The thickness of the glass can be set to, for example, 100 μm to 5 mm.

Before the resin film contains a hard coating on at least one side, the panel is not as rigid as known glass, but can have flexibility. The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 to 100 μm.

The resin film system can be a cycloolefin derivative, cellulose (diethyl cellulose, triacetyl cellulose, ethyl cellulose, etc.) having monomer units of cycloolefins containing norbornene or polycyclic norbornene monomers. Cellulose Butyrate, Isobutyl Cellulose, Acrylonyl Cellulose, Butyl Cellulose, Acetyl Acetyl Cellulose) Ethylene-Vinyl Acetate Copolymer, Polycyclic Olefin, Polyester, Polystyrene , Polyamide, polyetherimide, polyacrylic acid, polyimide, polyimide, polyether, poly, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, poly Vinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether ether, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate Films formed by polymers such as esters, polyethylene naphthalate, polycarbonate, polyurethane, and epoxy. Unstretched, uniaxially or biaxially stretched films can be used for the resin film system. These polymer systems can be used individually or in mixture of two or more types. The resin film is preferably a polyamide imide film or polyimide film, uniaxial or biaxially stretched polyester film with excellent transparency and heat resistance, excellent transparency and heat resistance, and can correspond to the large size of the film. Modified cycloolefin derivative film, polymethyl methacrylate film and triacetyl cellulose and isobutyl cellulose film with transparency and non-optical anisotropy. The thickness of the resin film is 5 to 200 μm, preferably 20 to 100 μm.

<Shading pattern>

The bezel can be formed on the image display layer 4 side of the front panel. The shading pattern can hide the wiring of the image display device 2 so as not to be seen by the user. The color and/or material of the light-shielding pattern is not particularly limited, and it can be formed by resin materials with various colors such as black, white, and gold. In one embodiment, the thickness of the light-shielding pattern may be 2 μm to 50 μm, preferably 4 μm to 30 μm, and more preferably 6 μm to 15 μm. In addition, in order to prevent bubbles from mixing in and the boundary part from being seen due to the step difference between the light-shielding pattern and the display portion, a shape can be given to the light-shielding pattern.

[Method of manufacturing optical laminate]

The optical layered body 6 is manufactured by laminating the polarizing plate 10 and the retardation film 12 with the adhesive layer 8b interposed therebetween. For example, after the polarizing plate 10 is manufactured, on the protective film 16 opposed to the retardation film 12, the adhesive layer 8b formed on the release film is laminated. The peeling film on the adhesive layer 8b is peeled off, and the polarizing plate 10 and the separately manufactured retardation film 12 are bonded via the exposed adhesive layer 8b. The optical laminate 6 obtained in this way can function as a circular polarizing plate.

[Method of Manufacturing Image Display Device]

The retardation film 12 included in the optical layered body 6 is bonded to the image display layer 4 via the adhesive layer 8a, thereby obtaining the image display device 2. Usually, as shown in FIG. 1, the optical laminate 6 is bonded to the image display layer 4 so that the C plate 20 is located on the image display layer 4 side.

The conditions satisfied by the image display device 2 are described as the first embodiment and the second embodiment.

(First implementation type)

As shown in FIG. 3, the surface of the image display device 2 orthogonal to the direction at the inclination angle θ with respect to the thickness direction (the lamination direction of the image display layer 4 and the optical laminate 6) is referred to as the projection surface 22. The above-mentioned thickness direction corresponds to a direction orthogonal to the slow axis 12a and the fast axis 12b. When the fast axis 12b of the retardation film 12 is assumed to be the rotation axis (tilt axis), the retardation of the retardation film 12 on the projection surface 22 is taken as R( θ ) _fast , and the slow axis 12a of the retardation film 12 is assumed to be the rotation axis At this time, the retardation of the retardation film 12 on the projection surface 22 is regarded as R( θ ) _slow , and the retardation of the image display layer 4 on the projection surface 22 is regarded as R( θ )M. The assumption that the slow axis 12a (or the fast axis 12b) is a rotation axis means that the retardation film 12 is tilted about the slow axis 12a (or the fast axis 12b). In this specification, the retardation of the retardation film or image display layer on the projection surface 22 refers to the retardation of the retardation film or image display layer projected on the projection surface 22.

The image display device 2 is R( θ ) _fast , R( θ ) _slow and R( θ )M satisfying the following formulas (i) to (iv).

α=R0-{R( θ ) _fast +R( θ )M)‧‧‧(i)

β=R0-{R( θ ) _slow -R( θ )M}‧‧‧(ii)

｜α( θ )｜+｜β( θ )｜<10nm‧‧‧(iii)

｜R( θ )M｜>0nm‧‧‧(iv)

As a result, when the screen of the image display device 2 is viewed from the front direction and when viewed from the oblique angle θ , the reflection color is different, and the reflection color corresponding to the in-plane angle is generated in the oblique direction. The maximum value of the chromatic aberration of the reflected color corresponding to the in-plane angle in the oblique direction is called the oblique chromatic aberration. Furthermore, when the oblique chromatic aberration is the smallest, the chromatic aberration is the smallest when viewed from the front direction and when viewed from the direction of the oblique angle θ. Therefore, even if the image displayed on the image display device 2 is viewed from various angles, the same image as viewed from the front direction (the above-mentioned thickness direction) can be observed.

Explain this further. As described above, the image display layer 4 is a light-reflective display layer that reflects light incident on the image display device 2 from the optical laminate 6 side. Therefore, in the following description, The image display layer 4 is referred to as a light reflection layer RL based on the above-mentioned reflection characteristics (refer to FIG. 1). In the following description, the optical layered body 6 is a circularly polarizing plate, but the optical layered body 6 is not limited to a circularly polarizing plate.

[Phase Difference of Optical Field]

The optical electric field vibrates on a plane perpendicular to the transmission direction and can be decomposed into S-polarized light and P-polarized light. At this time, the difference in the angular oscillation number of the shift of the electric field oscillation period of the S-polarized light and the P-polarized light is the phase difference. The difference between the incident light phase difference δ i and the reflected light phase difference δ r to the light reflection layer RL when it is not perpendicularly incident △ δ = δ r- δ i (hereinafter sometimes referred to as "the reflection phase difference of the light reflection layer RL △ δ ".) can be calculated from the Stokes spectrum S=(S0, S1, S2, S3) measured using ellipsometry or Stokes s polarimeter.

The polarization azimuth angle ψ, ellipticity angle ε, phase difference δ , and ellipticity χ of the photoelectric field are based on Stokes spectroscopy, as shown in the following formulas (6) to (9) (refer to "Spectroscopic Ellipsometer, Works by Hiroshi Fujiwara , Published by Maruzen, pages 68 to 78, 2011").

χ=tan ε…(9)

The incident light is linearly polarized light with polarization azimuth ψ=45° and ellipticity χ=0, when Stokes spectrum Si=(Si0,Si1,Si2,Si3)=(1,0,1,0), by In the above equations (6) to (8), the phase difference δ i becomes zero.

Similarly, the light reflection layer RL reflects the aforementioned incident light, and the reflected light is elliptically polarized light with polarization azimuth ψ=45° and ellipticity χ=0.4, Stokes spectrum Sr=(Sr0, Sr1, Sr2, Sr3)= At the time of (1, 1, 0.7, 0.7), from the above equations (6) to (8), the phase difference δ r becomes π/4. At this time, the light reflected by the reflective layer RL △ δ is expressed as the phase difference π / 4. Furthermore, the present specification, with respect to the polarization azimuth angle ψ = 45 ° and linearly polarized light of the incident light, the reflected light RL of the layer of the phase difference △ δ negative, the ellipse ratio angle ε> 0 of the case is positive, Set the ellipticity angle ε<0 as negative.

The phase difference Δ δ uses the corresponding wavelength λ (nm), which can be converted into the retardation R (nm) by the following formula (10).

[Angle dependence of light reflection layer]

The reflection phase difference Δ δ of the light reflection layer RL varies according to the incident angle θ r of the light to the light reflection layer RL. Represents the formula that is deformed by setting the boundary conditions of the refractive index of the medium in the Marxwell equation in the following formula (11) (refer to "Applied Engineering I, by Tsuruta Masao, Maruzen Publishing, pages 28 to 45, 1990"). The following formula (11) indicates that when the dielectric body is incident obliquely from the dielectric side to the metal side, the refractive index of the dielectric body is n=n ₁ , and the refractive index of the metal is set to n=-ik using the complex refractive index.

With normal incidence, the reflection phase difference Δ δ becomes 0, which increases as the incident angle θ r increases.

When the light reflection layer RL is, for example, an OLED display device or a micro LED display device, the light reflection layer RL is a multi-layered body of electrodes and wiring, light-emitting pixels, partition materials, plastic films, and the like. In the actual measurement system, the Stokes spectrum is measured for each incident angle θ r, and the reflection phase difference Δ δ of the light reflection layer RL at each incident angle θ r is calculated and provided to the theoretical calculation.

The reflected light RL layer is generated based on the phase difference △ δ crystallization of the metal reflecting surface having a free charge carriers like electrons are not generated in the reflecting surface resin film having no charge carriers and the like of the dielectric.

For example, the light reflective layer RL when the OLED display device or micro LED display device, which reflects the phase difference △ δ lines to follow the formation density, shape, electrodes and wiring metal seed layer RL of the reflected light obtained by various values. Therefore, there is a limited reflection phase difference Δ δ . In many cases, the absolute value of the reflection retardation Δ δ (50) on the projection surface 22 with a tilt angle of 50 degrees is 0.01rad or more at a wavelength of 550nm, and the absolute value of the reflection delay R(50)M is the same at a wavelength of 550nm The value is 1.0 nm or more.

The retardation system of the oblique field of view when observing the retardation film 12 tilted with the slow axis 12a as the rotation axis can be calculated according to the following procedure.

，從相位差膜12射出而在空氣中進行傳遞之光電場向量與z軸構成的角設為

yz，而應用史奈爾之法則，則獲得下式(12)。

yz係對應於以慢軸12a作為旋轉軸時之傾斜角θ。 As shown in Fig. 4, in the Cartesian coordinate system with the front direction as the z-axis, if the refractive index of the retardation film 12, the component parallel to the slow axis 12a (the x-axis in Fig. 4) is taken as nx, the component parallel to the fast axis 12b is taken as ny, the component parallel to the front direction is taken as nz, and the angle formed by the optical field vector transmitted in the retardation film 12 and the z-axis is taken as

, The angle formed by the photoelectric field vector emitted from the retardation film 12 and transmitted in the air and the z-axis is set as

yz, and applying Snell's law, the following formula (12) is obtained.

yz corresponds to the tilt angle θ when the slow axis 12a is used as the rotation axis.

The phase difference of the oblique field of view with the slow axis 12a as the rotation axis is the following formula (13), which can be projected from ny and nz on the projection plane (a plane perpendicular to the line connecting the retardation film 12 and the observer) 22. Find the refractive index Nyz and nx. In the formula (13), d is the thickness of the retardation film 12.

R( θ ) _slow =(nx-Nyz)×d/cos φ _yz …(13)

At this time, the effective refractive index Nyz of the projection surface 22 can be obtained by the following formula (14) using a refractive index ellipsoid (refer to "Forefront of Refractive Index Control Technology of Optical Materials, Supervised by Toshiyuki Watanabe and Yoshihiro Uozu, CMC Publishing, Page 14-16, 2009").

xz係對應於以快軸12b作為旋轉軸時之傾斜角θ。式(15)中之d係與式(13)之情形相同。 The phase difference of the oblique field of view with the fast axis 12b as the rotation axis is also the same as the equation (13), as shown in the following equation (15). Of the following formula

xz corresponds to the tilt angle θ when the fast axis 12b is used as the rotation axis. The d in equation (15) is the same as that in equation (13).

R( θ ) _fast =(ny-Nxz)×d/cosφ _xz …(15)

Measure the transmittance in the direction of the transmission axis of the polarizing film 14 (the direction orthogonal to the absorption axis 14a) and the transmittance in the direction of the absorption axis 14a, and the three-dimensional refractive index of the A plate 18 and the C plate 20 of the retardation film 12 , The parameters of the optical elements such as the reflection phase difference of the light reflection layer RL, the adhesive or the transmittance of the front panel, etc., are substituted into the Mueller Matrix, and the optical elements can be accurately calculated to make these optical elements penetrate or reflect The state of the optical field at time.

For example, when passing through the optical laminate 6 (circular polarizing plate) and reflecting on the light reflection layer RL, penetrating the optical laminate 6 (circular polarizing plate) and calculating the observed optical field, the Stokes spectrum of the _{reflected light S out} It is obtained as the solution of the following equation (16).

S _out =P‧A‧C‧M‧C‧A‧P‧S _in ... (16)

In formula (16), P, A, M, and S _in are as follows.

P: Muller matrix of polarizing film 14

A: A plate 18 Mueller matrix

C: Muller matrix of C board 20

M: Muller matrix of light reflection layer RL

S _in : Stokes spectrum of incident light

The Mueller matrix of optical elements is a 4×4 matrix. For example, the polarizing film 14 and the retardation film 12 are shown in the following formulas (17) to (18) (refer to "Basics and Applications of Polarized Light Transmission Analysis, by Hiroshi Ono, Uchida Old Crane Garden, pages 57 to 61, 2015").

In the formula (17), T ₁ is the transmittance in the direction of the transmission axis _{of the polarizing film 14, and T 2} is the transmittance in the direction of the absorption axis 14 a of the polarizing film 14. In the formula (17), Δ δ (rad) is the retardation of the retardation film 12.

In the light reflection layer RL, similar to the C plate 20, a retardation plate with an increased retardation in proportion to the tilt angle θ can be obtained. Therefore, the phase difference film element and the amplitude reflection element can be separated and defined. The retardation film element system of the light reflection layer RL defines the Muller matrix in the same manner as the retardation film 12.

When calculating the actual circular polarizing plate composition, the optical axis of the optical element must be reflected in the Muller matrix. For example, in the case where the slow axis (slow axis 12a) in the plane of the A plate 18 of the retardation film 12 of the formula (18) is defined only by the rotation angle ξ (rad), as shown in the formula (19), from Muller The two sides of the matrix make the rotation matrix Z(ξ) act.

The reflectance spectrum of the light seen through the optical laminate 6 (circular polarizing plate) is reflected by the light reflection layer RL, and then the reflectance spectrum of the light seen through the optical laminate 6 (circular polarizing plate) is calculated from the above formula (16) for each wavelength The S0 component of the Stokes spectrum is obtained. This system corresponds to the reflectance of the component reaching the inside of the optical layered body 6 (circularly polarizing plate) without being reflected at the interface between the air and the optical layered body 6 (circularly polarizing plate). On the other hand, the reflectance Rfo of the interface between the air and the optical layered body 6 (circular polarizing plate) changes in proportion to the tilt angle θ and the refractive index ns, as shown in the following formula (20).

Furthermore, the interface system between the optical layered body 6 (circularly polarizing plate) and air, for example, when the surface of the polarizing plate 10 is in contact with the air layer, the optical layered body 6 is the interface between the polarizing plate 10 and the air. The optical laminate 6 is further equipped with a front panel on the viewing side of the polarizing plate 10. In addition, when the polarizing plate 10 is closely laminated and laminated with the polarizing plate 10 interposed between the adhesive layer, the optical laminate 6 (circular polarizing plate) and the air The interface is the interface between the viewing side of the front panel and the air layer.

From the above, the surface reflectance of the interface with the air of the optical laminate 6 (circular polarizing plate) and the reflection by the light reflection layer RL through the optical laminate 6 (circular polarizing plate) are seen through the optical laminate 6 The total reflectance Rf of the internal reflectance obtained is obtained according to the following formula (21). In addition, the interface reflection and multiple reflections between the layers constituting the optical laminate 6 (circular polarizing plate) are not considered.

Rf=Rfo+(1-Rfo)×S0=Rfo+S0-Rfo×S0‧‧‧(21)

In addition, the optical layered body 6 (circular polarizing plate) may be provided with an anti-reflection film at the interface with the air.

The anti-reflection film can be a single-layer structure consisting of only a low refractive index layer with a low refractive index, or a low refractive index layer with a low refractive index and a high refractive index layer with a high refractive index layered in sequence. Multi-layer structure. When an anti-reflection film is provided, and the surface reflectance is, for example, 2% or less, and even more 1% or less, the light reflection layer RL is reflected by the optical laminate 6 (circular polarizer), and then passes through the optical laminate 6 (circular polarizer). It is easier to see the chromatic aberration of the internal reflected light that is seen by the polarizing plate), so the structure of the present invention is easy to effectively exert its effect.

Standard illuminant W (λ) tristimulus values X _W , Y _W , Z _W and reflected light illuminant Rf (λ) × W (λ) tristimulus values X _Rf , Y _Rf , Z _Rf are used The color matching functions x(λ), y(λ), z(λ) of the tristimulus values (Recommended by the International Commission on Illumination (CIE), 1931) are calculated from the following formulas (22A) to (22B) (refer to ``Color Engineering Introduction to Science, co-authored by Hiroyuki Shinoda and Ichiro Fujieda, published by Morihoku, pages 106 to 107, 2007"). D65 light source (ISO 10526:1999/CIE S005/E-1998) is used in the standard luminous material system.

L ^* a ^* b ^* color system, the reflected light hue value a ^*, b ^* and chroma C ^* value based using standard illuminant W (λ) of the tristimulus values X _W, Y _W, Z _W reflected light glitter The tristimulus values of Rf(λ)×W(λ) X _Rf , Y _Rf , Z _Rf are calculated from equations (23) to (25) (refer to "Introduction to Color Engineering, Hiroyuki Shinoda and Ichiro Fujieda, Morikita Published, 122 pages, 2007").

When the slow axis 12a of the A plate 18 is parallel to the x axis, and the fast axis 12b and the y axis are respectively parallel, when viewing the image display device 2 from the z-axis tilted only by θ (the tilt angle θ direction) (in Figure 2 from the blank When viewed in the direction of the arrow, it is called "oblique angle θ observation" (refer to Figure 2).

At this time, with the change of the angle ξ in the xy plane, the chroma C ^* _{obtains the two extremums C f} ^* and C _s ^* due to the double symmetry of the A plate 18, and the coordinates in ^{the a *} b ^{* plane.} As C _f ^* (a _f ^* , b _f ^* ), C _s ^* (a _s ^* , b _s ^* ). ^{The distance ΔC*} between the two points is expressed as the oblique chromatic aberration observed at an oblique angle θ and expressed by the following formula (26).

When the oblique chromatic aberration observed at the oblique angle θ is the smallest, when the image display device 2 is viewed from all angles, the color change and intensity change of the reflected color become the smallest, and the best image display performance can be obtained.

In order to keep the characteristics of the polarizing film 14 unchanged, the characteristics of the retardation film 12 and the light reflection layer RL are adjusted to achieve the smallest oblique chromatic aberration, as long as the following formula (27) is satisfied.

RthA+RthC+RthM=0‧‧‧(27)

In formula (27), RthA is the retardation in the thickness direction of the A plate 18, RthC is the retardation in the thickness direction of the C plate 20, and RthM is the retardation in the thickness direction of the light reflection layer RL.

Among the in-plane delays of the A plate 18, the delay of the projection surface 22 when the fast axis 12b is the rotation axis is set to R( θ )A _fast , and the delay of the projection surface when the slow axis 12a is the rotation axis is set to R( θ )A _slow . Similarly, the in-plane retardation of the C plate 20 on the projection surface 22 is R( θ )C, and the in-plane retardation of the light reflection layer RL on the projection surface 22 is R( θ )M.

If the delay of the A plate 18 when viewed from the front (when the tilt angle θ =0) is set to R(0)A, the following formula (28) can be used to describe the optimal optical design of the image display device 2.

The following formula (28) is satisfied when the above formula (27) is satisfied. At this time, the oblique chromatic aberration ΔC ^* observed at the inclination angle θ of the formula (26) is the most suitable.

R( θ )A _fast +(R( θ )C+R( θ )M)=R( θ )A _slow -(R( θ )C+R( θ )M)=R0A‧‧‧(28)

In addition, if the A plate 18 and the C plate 20 are regarded as one retardation film layer, the in-plane delay R( θ ) _fast and R( θ ) _slow in the projection surface 22 observed at an oblique angle θ are given by the following equations (29), (30) Shown.

R( θ ) _fast =R( θ )A _fast +R( θ )C‧‧‧(29)

R( θ ) _slow =R( θ )A _slow -R( θ )C‧‧‧(30)

If formulas (29) and (30) are used to rewrite formula (28), the following formulas (31) and (32) can be obtained.

α=R0-{R( θ ) _fast +R( θ )M)‧‧‧(31)

β=R0-{R( θ ) _slow -R( θ )M}‧‧‧(32)

Furthermore, since the light reflection layer RL of this embodiment has a reflection phase difference, the following equation (33) will hold.

｜R( θ )M｜>0nm‧‧‧(33)

The formulas (31) to (33) correspond to the aforementioned formulas (i), (ii), (iv). Furthermore, the image display device 2 also satisfies the formula (iii). Equations (i) and (ii) (or equations (31) and (32)) are as described above, and are equations that consider the reflection phase difference of the light reflection layer RL.

For example, the design of the optical compensation member of the circular polarizing plate did not reflect the reflection phase difference of the light reflection layer in the past. However, in fact, due to the influence of the reflection phase difference of the light reflection layer, the oblique chromatic aberration cannot be sufficiently suppressed (or as designed).

In contrast, the image display device 2 satisfies the equations (i) to (iv) in consideration of the reflection phase difference of the light reflection layer RL. Therefore, the image display device 2 has an optimal design in order to minimize the oblique chromatic aberration. As a result, the oblique chromatic aberration can be sufficiently suppressed (or as designed or desired state).

The image display device 2 is manufactured in a manner that satisfies the formula (i) to the formula (iv), for example, as long as the type or formulation of the thermoplastic resin or polymerizable liquid crystal compound forming the A plate 18 and the C plate 20 of the retardation film 12 is adjusted Ratio, or adjust the thickness of A plate 18 and C plate 20.

Examples of the image display layer 4 include OLED display devices and micro LED display devices. However, other examples of the image display layer 4 may include: liquid crystal display devices, electron emission display devices (such as field emission display devices (FED), surface field emission display devices (SED), electronic paper (electronic printing ink or using electrophoresis) Component display device), plasma display device, projection display device (such as grating light valve (also called GLV) display device, display device with digital micromirror device (also called DMD), piezoelectric ceramic display, etc. The liquid crystal display device also includes any of a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device, etc. The laminated system of this embodiment can be particularly effectively used in an organic EL display device or an inorganic EL display device.

In particular, the image display device 2 having an organic EL display device or an inorganic EL display device as the light reflection layer RL can suppress changes in the intensity of reflected light from external light, and when viewed from an oblique direction, it also shows stability unchanged from the front direction. The black display ability.

(Second implementation type)

Regarding the second embodiment, the conditions that the image display device 2 satisfies will be described from a different point of view from the first embodiment. In the second embodiment, as shown in FIG. 3, the image display device 2 is orthogonal to the direction at the inclination angle θ with respect to the thickness direction (the lamination direction of the image display layer 4 and the optical laminate 6). The surface is called the projection surface 22. In the second embodiment, the projection surface 22 is a surface when θ=50 degrees. Therefore, the delay of the image display layer 4 on the projection surface 22 is taken as R(50)M. The delay described in the second embodiment is the delay for the wavelength of 550nm unless otherwise stated.

Let the in-plane retardation of the retardation film 12 be R0, and let the retardation of the retardation film 12 in the thickness direction be Rth. R0 is the total in-plane retardation of each layer constituting the retardation film 12. Rth is the total of retardation in the thickness direction of each layer constituting the retardation film 12. As shown in Figure 1, when the retardation film 12 has an A plate and a C plate, R0 is the total of the in-plane retardation of the A plate and the C plate, and the Rth is the total of the thickness direction retardation of the A plate and the C plate. .

The Nz coefficient of the retardation film 12 is expressed by formula (v). In addition, the ratio of the in-plane retardation R0 of the retardation film to the in-plane retardation R(50)M of the image display layer 4 on the projection surface 22 is represented by the formula (vi) as the ρ coefficient.

Nz=(Rth/R0)+0.5‧‧‧(v)

ρ =R(50)M/R0‧‧‧(vi)

The image display device 2 all satisfies the following formula (vii), formula (viii), and formula (ix), or satisfies formula (vii), formula (x), and formula (xi).

3.5ρ+0.39<Nz<3.5 ρ +0.65‧‧‧(vii)

ρ >0‧‧‧(viii)

0.5<Nz≦1.5‧‧‧(ix)

ρ <0‧‧‧(x)

-1.5<Nz<0.5‧‧‧(xi)

In other words, the image display device 2 is a device including a retardation film 12 and an image display layer 4. The retardation film 12 is in the ρ- Nz coordinate system (Cartesian coordinate system), and the region shown in formula (vii) Among them, all areas satisfying formula (vii), formula (viii), and formula (ix), or the group of ρ contained in the area satisfying formula (vii), formula (x), and formula (xi) and satisfying Nz. In addition, formula (viii-1) may be substituted for formula (viii). The formula (ix-1) can be substituted for the formula (ix). The formula (x-1) may be substituted for the formula (x). The formula (xi-1) may be substituted for the formula (xi).

0< ρ <0.12‧‧‧(viii-1)

0.5<Nz≦1.0‧‧‧(ix-1)

-0.06< ρ <0‧‧‧(x-1)

0.2<Nz<0.5‧‧‧(xi-1)

When ρ is greater than 0 (when the above formula (viii) is satisfied), it is preferable to satisfy the following formula (xii), formula (xiii), and formula (xiv).

0.06≦ ρ ≦0.11‧‧‧(xii)

Nz≧3.5 ρ +0.405‧‧‧(xiii)

Nz≦3.5 ρ +0.61‧‧‧(xiv)

When ρ is less than 0 (when the above-mentioned formula (x) is satisfied), it is preferable to satisfy the range of the following formula (xv), formula (xvi) and formula (xvii).

-0.07≦ ρ ≦-0.04‧‧‧(xv)

Nz≧3.5 ρ +0.42‧‧‧(xvi)

Nz≦3.5 ρ +0.59‧‧‧(xvii)

The image display device 2 of the second embodiment is, for example, by adjusting the type or mixing ratio of the thermoplastic resin or polymerizable liquid crystal compound that forms the A plate 18 and the C plate 20 of the retardation film 12, or the A plate 18 and C plate 20 thickness.

In the second embodiment, the image display device 2 satisfies the above-mentioned condition considering the reflection phase difference of the image display layer 4. Therefore, the image display device 2 has an optimal design in order to minimize the oblique chromatic aberration. As a result, the oblique chromatic aberration (or, as designed or desired state) can be sufficiently suppressed.

The various embodiments of the present invention are described above, but the present invention is not limited by the above embodiments. A circularly polarizing plate is given as an example of the optical layered body 6, but the optical layered body 6 is not limited to a circularly polarizing plate.

[Example]

Hereinafter, examples and comparative examples are given to more specifically explain the content of the present invention. In addition, the present invention is not limited to the following examples. In addition, the "%" and "parts" in the examples mean mass% and parts by mass unless otherwise stated. The circularly polarizing plate described below is an optical laminate corresponding to the description of the above embodiments, and the light reflection layer corresponds to the image display layer.

[test methods]

<Measuring method of film thickness>

The thickness of the film was measured using a contact film thickness meter (MH-15M manufactured by Nikon Co., Ltd., counter TC101, MS-5C).

<Delay measurement method>

The thickness direction retardation or in-plane retardation of the A plate and the C plate was measured using a birefringence evaluation device (KOBRA-WPR manufactured by Oji Measuring Instruments Co., Ltd.).

The retardation of each incident angle of the light reflection layer was measured using a spectroscopic ellipsometer (M-2000 manufactured by J.A. Woollam).

<The oblique chromatic aberration △C when oblique at an oblique angle of 50 degrees ^* >

^{The oblique chromatic aberration △C*} observed at an oblique angle of 50 degrees was measured with the display evaluation system DMS803 manufactured by Instrument Systems GmbH.

[Preparation of light reflection layer]

The following 7 types of light reflection layers are used.

Light reflection layer A: M560 made of brass plate made by Kubo Metal Manufacturing Co., Ltd.

Light reflection layer B: The OLED display device manufactured by Apple Inc., which is commercially available, is disassembled and equipped with a smartphone iPhone (registered trademark) X, and the cover glass and circular polarizer are removed and used.

Light reflection layer C: The glossy surface of My Foil thick 50, which belongs to aluminum foil manufactured by UACJ Co., Ltd., is used.

Light reflection layer D: It is obtained by applying hard chromium plating (industrial chromium plating JIS H8615) to a copper plate.

Light reflection layer E: Eagle XG made by Corning, which is an alkali-free glass plate, is used.

Light reflection layer F: Use MIRO5 5011GP made by Alanod with high reflection coating vapor-deposited aluminum reflection plate as high reflection rate reflection plate.

Light reflection layer G: Disassemble the tablet PC Galaxy tab S 8.4 equipped with a commercially available OLED display device made by Samsung Electronics, remove the cover glass and the circular polarizer and use it.

The reflection retardation Δ δ 50 (550) and the reflection delay R50M (550) at the wavelength of 550 nm at the inclination angle of each light reflection layer of 50 degrees are shown in Table 1. In order to measure these under conditions that simulate an actual OLED display device, an unstretched cycloolefin polymer is attached to each of the light reflection layers A to G and measured. The in-plane retardation of the cycloolefin polymer does not reach 0.1 even at any of the wavelengths of 450 nm, 550 nm, and 630 nm.

[Table 1]

[Making of Circular Polarizing Plate]

[Preparation of composition for formation of horizontal oriented film]

Mix 5 parts (weight average molecular weight: 30000) of light directing material with the following structure and 95 parts of cyclopentanone (solvent). By stirring the obtained mixture at 80°C for 1 hour, a composition for forming a horizontally oriented film was obtained.

[Preparation of composition for forming vertical alignment film]

Use SUN-EVER SE610 manufactured by Nissan Chemical Industry Co., Ltd.

[Preparation of a composition for forming a horizontally oriented liquid crystal cured film]

In order to form a horizontally oriented liquid crystal cured film (A plate), the following polymerizable liquid crystal compound A and polymerizable liquid crystal compound B are used. The polymerizable liquid crystal compound A is described in JP 2010-31223 A Method of manufacturing. In addition, the polymerizable liquid crystal compound B is produced in accordance with the method described in JP 2009-173893 A. The molecular structure of each is shown below.

[Polymerizable Liquid Crystal Compound A]

[Polymerizable Liquid Crystal Compound B]

The polymerizable liquid crystal compound A and the polymerizable liquid crystal compound B were mixed in a mass ratio of 87:13. With respect to 100 parts of the obtained mixture, 1.0 part of a leveling agent (F-556; manufactured by DIC Co., Ltd.) and 2-dimethylamino-2-benzyl-1-( 6 parts of 4-morpholinophenyl)butan-1-one (IRGACURE369, manufactured by BASF JAPAN Co., Ltd.). Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration might become 13%, and it stirred at 80 degreeC for 1 hour, thereby obtaining the composition for horizontally oriented liquid crystal cured film formation.

[Adjustment of the composition for forming a cured film of a vertically oriented liquid crystal]

In order to form a vertically aligned liquid crystal cured film (C plate), the composition was prepared in the following order. With respect to 100 parts of Paliocolor LC242 (registered trademark of BASF Corporation) which is a polymerizable liquid crystal compound, 0.1 part of F-556 as a leveling agent and 3 parts of IRGACURE 369 as a polymerization initiator are added. Cyclopentanone was added so that the solid content concentration might become 13%, and a composition for forming a vertically aligned liquid crystal cured film was obtained.

[Making of Polarizing Plate]

Prepare a polyvinyl alcohol (PVA) film with an average degree of polymerization of about 2,400, a degree of saponification of 99.9 mol% or more, and a thickness of 75 μm. After immersing the PVA film in pure water at 30°C, it is immersed in an aqueous solution with a mass ratio of iodine/potassium iodide/water of 0.02/2/100 at 30°C and iodine dyeing is performed (iodine dyeing step). The PVA film after the iodine dyeing step is immersed in an aqueous solution with a mass ratio of potassium iodide/boric acid/water of 12/5/100 at 56.5° C. for boric acid treatment (boric acid treatment step). The PVA film that has undergone the boric acid treatment step is washed with pure water at 8°C and dried at 65°C to obtain a polarizing film with iodine adsorbed and oriented to polyvinyl alcohol. The extension of the PVA film is carried out in the iodine dyeing step and the boric acid treatment step. The total stretching ratio of the PVA film is 5.3 times. The thickness of the obtained polarizing film was 10 μm.

The polarizing film and the saponified triacetyl cellulose (TAC) film (Knoica Minolta Co., Ltd. product KC4UYTAC thickness 40 μm) were bonded with a kneading roller via a water-based adhesive. While maintaining the tension of the obtained laminate at 430 N/m, it was dried at 60° C. for 2 minutes to obtain a polarizing plate having a TAC film as a protective film on one side. In addition, the water-based adhesive system adds 3 parts of carboxy modified polyvinyl alcohol (manufactured by KURARAY Co., Ltd., "KurarayPoval KL318") to 100 parts of water, and water-soluble polyamide epoxy resin (manufactured by Taoka Chemical Industry Co., Ltd.) , "Sumirezs Resin 650", 30% solid content aqueous solution) 1.5 parts.

The optical characteristics of the obtained polarizing plate were measured. The measurement was performed with a spectrophotometer ("V7100", manufactured by JASCO Corporation) with the polarizing film surface of the polarizing plate obtained above as the incident surface. The absorption axis of the polarizer is consistent with the extension direction of the polyvinyl alcohol. The obtained polarizer has a sensitivity correction monomer transmittance of 42.3%, a sensitivity correction polarization degree of 99.996%, and a monomer hue a of -1.0. The monomer hue b is 2.7.

[Production of horizontally oriented liquid crystal hardened film (A plate)]

Corona treatment was performed on a cyclic olefin resin (COP) film (ZF-14-50) made by Japan's ZEON Co., Ltd. The corona treatment was performed using TEC-4AX manufactured by USHIO Electric Co., Ltd. The corona treatment is performed once under the conditions of an output of 0.78kW and a treatment speed of 10m/min. The composition for forming a horizontal orientation film was applied to the COP film with a rod coater, and dried at 80°C for 1 minute. Use a polarized UV irradiation device ("SPOT CURE SP-9", manufactured by USHIO Electric Co., Ltd.) for the coating film, and perform polarized UV exposure at an axis angle of 45° so that ^{the cumulative light with a wavelength of 313nm becomes 100mJ/cm 2} . The film thickness of the obtained horizontal alignment film was 100 nm.

Then, the composition for forming a horizontally oriented liquid crystal cured film was applied to the horizontally oriented film with a rod coater, and dried at 120°C for 1 minute. A high-pressure mercury lamp ("Unicure VB-15201BY-A", manufactured by USHIO Electric Co., Ltd.) is used for the coating film, and the horizontal orientation is formed ^{by irradiating ultraviolet light (in a nitrogen environment, the cumulative amount of light at a wavelength of 365nm: 500mJ/cm 2)} Liquid crystal hardened film. The film thickness of the horizontally oriented liquid crystal cured film is about 1.9μm.

Laminate an adhesive layer on the horizontally oriented liquid crystal cured film. A film composed of a COP film, an oriented film, and a horizontally oriented liquid crystal cured film is bonded to the glass through the adhesive layer. The COP film was peeled off to obtain a sample for measuring the delay.

The retardation R0A (λ) of each wavelength was measured. As a result, as follows, the horizontally oriented liquid crystal cured film showed reverse wavelength dispersion.

R0A(450)=124nm

R0A(550)=142nm

R0A(650)=146nm

R0A(450)/R0A(550)=0.87

R0A(650)/R0A(550)=1.03

The horizontally oriented liquid crystal cured film is a positive A plate that satisfies the relationship of nx>ny≒nz. In addition, the delay RthA(λ) at each wavelength was measured, and the results are as follows.

RthA(450)=64nm

RthA(550)=71nm

RthA(650)=73nm

[Production of vertical oriented liquid crystal hardened film (C plate)]

Perform corona treatment on the COP film. The conditions of corona treatment are the same as above. On the COP film, the composition for forming a vertical alignment film was coated with a rod coater, and dried at 80° C. for 1 minute to obtain a vertical alignment film. The thickness of the obtained vertical alignment film was 50 nm.

The vertical oriented liquid crystal cured film formation composition was coated on the vertical oriented film using a rod coater, and dried at 90°C for 120 seconds. A high-pressure mercury lamp ("Unicure VB-15201BY-A", manufactured by USHIO Electric Co., Ltd.) is used for the coating film, and the vertical orientation is formed ^{by irradiating ultraviolet rays (in a nitrogen environment, the cumulative amount of light at a wavelength of 365nm: 500mJ/cm 2)} Liquid crystal hardened film. In this way, a film composed of a COP film, a vertical alignment film, and a vertical alignment liquid crystal cured film is obtained. The film thickness of the vertically aligned liquid crystal cured film is 0.2 μm.

An adhesive layer is laminated on the vertical alignment liquid crystal cured film. A film composed of a COP film, an oriented film, and a vertically oriented liquid crystal cured film is bonded to the glass through the adhesive layer. The COP film was peeled off to obtain a sample for measuring the delay. The delay RthC1 (550) at a wavelength of 550 nm was measured, and the results are as follows.

RthC(550)=-20nm.

Vertically oriented liquid crystal cured film is a positive C plate that satisfies the relationship of nx≒ny<nz.

The vertical alignment film and the vertical alignment liquid crystal hardened film (C plate) formed on the COP film are horizontally aligned with the horizontal alignment film and the horizontal alignment liquid crystal hardened film (A plate) formed on the COP film. The surface of the oriented liquid crystal cured film is adhered with an adhesive interposed therebetween, and then the COP film on the A plate side is peeled off to obtain a film in which the COP film, the C plate, and the A plate are laminated in this order.

Among the films, corona treatment is applied to the horizontally oriented liquid crystal cured film (A plate). The conditions of corona treatment are the same as above. The polarizing film 14 and the horizontally oriented liquid crystal cured film (A plate) of the polarizing plate 10 are in contact with each other, and the two are laminated via an adhesive layer. At this time, the angle formed by the absorption axis of the polarizing film and the slow axis of the horizontally oriented liquid crystal cured film is 45°. In this way, a circular polarizing plate (1) in which a retardation film and a polarizing plate are laminated via an adhesive layer is obtained. The circular polarizing plate (1) is composed of a TAC film, a polarizing film, an adhesive layer, a horizontally oriented liquid crystal hardened film (A plate), an adhesive layer, and a vertically oriented liquid crystal hardened film (C plate).

[Making of Circular Polarizing Plate (2)]

Except that the film thickness of the vertically-oriented liquid crystal cured film is 0.3μm and RthC(550)=-30nm, the rest is the same as the circular polarizer (1) to produce the circular polarizer (2).

[Making of Circular Polarizing Plate (3)]

Except that the thickness of the vertically oriented liquid crystal cured film is 0.4μm and RthC(550)=-40nm, the rest is the same as the circular polarizer (1) to produce the circular polarizer (3).

[Making of Circular Polarizing Plate (4)]

Except that the film thickness of the vertically oriented liquid crystal cured film is 0.5μm and RthC(550)=-50nm, the rest is the same as the circular polarizing plate (1) to produce the circular polarizing plate (4).

[Making of Circular Polarizing Plate (5)]

Except for the method that the thickness of the vertically oriented liquid crystal cured film is 0.6 μm and RthC (550) = -60 nm, the rest is the same as the circular polarizing plate (1) to produce the circular polarizing plate (5).

[Making of Circular Polarizing Plate (6)]

Except that the film thickness of the vertically-oriented liquid crystal cured film is 0.7μm and RthC(550)=-70nm, the rest is the same as the circular polarizer (1) to produce the circular polarizer (6).

[Making of Circular Polarizing Plate (7)]

Except that the film thickness of the vertically oriented liquid crystal cured film is 0.8μm and RthC(550)=-80nm, the rest is the same as the circular polarizing plate (1) to produce the circular polarizing plate (7).

[Making of Circular Polarizing Plate (8)]

Except that the film thickness of the vertically oriented liquid crystal cured film is 0.9 μm and the RthC (550) = -90 nm, the rest is the same as the circular polarizing plate (1) to produce the circular polarizing plate (8).

[Making of Circular Polarizing Plate (9)]

Except that the film thickness of the vertically oriented liquid crystal cured film is 1.0 μm and RthC(550)=-100nm, the rest is the same as the circular polarizing plate (1) to produce the circular polarizing plate (9).

[Making of Circular Polarizing Plate (10)]

Except that the C plate 20 is not provided, a circular polarizing plate (10) is produced in the same manner as the circular polarizing plate (1).

<Example 1>

In the circular polarizing plate (1), the COP film is peeled off and an adhesive layer is laminated on the exposed surface. The circular polarizing plate (1) and the light reflection layer A were laminated via the adhesive layer to obtain a laminated body.

For the obtained laminate, respectively measure: the in-plane retardation R0A (550) of the A plate of the circularly polarizing plate (1), and the in-plane retardation of the projection surface when the oblique angle is 50 degrees, assuming that the rotation axis is fast The axis time delay R50A _fast (550), the delay when the rotation axis is the slow axis R50A _slow (550), the thickness direction delay of the C plate RthC(550), the surface on the projection surface when the oblique angle of 50 degrees is observed The internal retardation is R50C (550), and the value of the reflection retardation R50M (550) on the projection surface when the inclination angle of the light reflection layer is 50 degrees.

For the obtained laminate, the oblique chromatic aberration was measured.

For the resulting laminate, the transmittance T1 in the direction of the transmission axis of the polarizing plate 10, the transmittance T2 in the direction of the absorption axis, and the three-dimensional refractive index of the A plate nAx, nAy, nAz, and within the plane of the wavelength 550nm The three-dimensional refractive index nAx, nAy, nAz of the retardation R0A and C plate 20, the retardation RthC in the thickness direction with a wavelength of 550nm, and the reflection retardation of the light reflection layer R50M are based on the above-mentioned measurement data in the range of wavelength 380nm to wavelength 780mm. Use equations (6) to (26) to calculate the oblique chromatic aberration at an oblique angle of 50 degrees.

With regard to the obtained laminated body, the recognizability of the pattern drawn on the surface of the light reflection layer was evaluated by visual inspection. The more difficult it is to recognize the pattern, the smaller the change in reflected color and the better display characteristics that are independent of angle. The graphic is a Landolt ring with a diameter of 3mm and an opening of 0.5mm, painted in light blue by Hugh McKee made by ZEBRA, a blue-green oil-based pen. The opening direction is arbitrary. The observation is performed by changing the relationship between the optical axis of the horizontally oriented liquid crystal cured film and the position of the observer.

Specifically, it was observed visually from an elevation angle (tilt angle) of around 50 degrees at an in-plane angle parallel to the fast axis of the A plate. The hue of the reflected light in this direction is blue-green, which is similar to the color of the pattern drawn on the surface of the light reflection layer, so it is relatively difficult to recognize. On the other hand, at an in-plane angle parallel to the slow axis of the A plate, the hue of the reflected light when viewed visually from an elevation angle of approximately 50 degrees becomes red, which is different from the color of the pattern drawn on the surface of the light reflection layer, so the pattern The identification is relatively easy. When viewing the overall visibility of the opening direction of the figure from the slow axis direction and the fast axis direction, the result is clearly judged based on the following criteria 1 to 4.

"1": Cannot see the direction of the opening.

"2": If you stare, you can see the direction of the opening.

"3": The direction of the opening can be seen.

"4": The direction of the opening can be clearly seen.

As a result, it can be seen that in the laminated system obtained in Example 1, the color of the reflected light is uniform when viewed from any direction, and a good black display can be displayed at a wide viewing angle.

[Examples 2 to 19, Comparative Examples 1 to 30, and Reference Examples 1 to 10]

Except that the combination of the circularly polarizing plates (1) to (10) and the light reflection layers A to G was changed as shown in Tables 2 to 4, the laminated body was produced in the same manner as in Example 1. With respect to the obtained laminate, the oblique chromatic aberration was measured in the same manner as in Example 1. Also, for the obtained laminate, as in Example 1, when the relationship between the optical axis of the horizontally oriented liquid crystal cured film and the position of the observer was changed visually, the visibility of the pattern drawn on the surface of the light reflection layer was evaluated.

However, in Comparative Example 9 using the light-reflecting layer B, a commercially available OLED display device manufactured by Apple Inc. was disassembled and equipped with a smartphone iPhone (registered trademark) X. Only the cover glass was removed and the oblique chromatic aberration △C ^* was measured and Recognition evaluation of graphics.

Also, in Comparative Example 23 using the light reflection layer G, the tablet PC Galaxy tab S 8.4 equipped with an OLED display device manufactured by Samsung Electronics was disassembled, and only the cover glass was removed, and the oblique chromatic aberration △C ^* was measured and the pattern was recognizable. Evaluation.

The light reflection layer E is as shown in Table 1. Since the reflection phase difference is 0, the combination of the light reflection layer E and the circular polarizer (1) to (10) is achieved by using formulas (6) to (26) The simulation is to calculate the oblique chromatic aberration at an oblique angle of 50 degrees. Therefore, the case of using the light reflection layer E is referred to as Reference Examples 1 to 10.

The results of the above Examples 1 to 19, Comparative Examples 1 to 30, and Reference Examples 1 to 10 are summarized from the viewpoint of the first embodiment. Tables 2 to 4 are tables showing the results of Examples, Reference Examples, and Comparative Examples based on the viewpoint of the first embodiment.

In Table 2 to Table 4, the meaning of each item name is as follows.

I: The light reflection layer used

II: Polarizing plate used

III: Results of visual assessment

△C ^* : The measurement result of oblique color difference

R0: Measurement result of the retardation in the thickness direction of the circular polarizer

R50 _fast : Observe the in-plane delay of the circular polarizer on the projection surface when the tilt angle is 50 degrees, and the measurement result of the delay when the rotation axis is assumed to be the fast axis

R50 _slow : Observe the in-plane delay of the circular polarizer on the projection surface when the tilt angle is 50 degrees, and the measurement result of the delay when the rotation axis is assumed to be the slow axis

R50M: In-plane delay of the light reflection layer on the projection surface

α: The calculation result when R0, R( θ ) _fast and R( θ )M of formula (i) are set to R0, R50 _{fast and R50M}

β: The calculation result when R0, R( θ ), R( θ ) _slow and R( θ )M of formula (ii) are set to R0, R50 _{slow and R50M}

｜α｜+｜β｜: According to the calculation results of α and β in Table 2 to Table 4

_{R0, R50 fast} , R50 _slow and R50M in Table 2 to Table 4 are delays at a wavelength of 550nm.

In addition, in Tables 2 to 4, reference examples 1 to 10 are simulation results, so the column of item name III (the result of visual evaluation) is set to an empty column.

As shown in Tables 2 to 4, Comparative Examples 1 to 30 and Reference Examples 1 to 10 did not satisfy any of the above formulas (i) to (iv). The visual evaluation system in Comparative Examples 1 to 30 is 3 or higher.

On the other hand, Examples 1 to 19 satisfy the aforementioned formulas (i) to (iv). The visual assessment at this time is 1 or 2. Therefore, it can be understood that Examples 1 to 19 can sufficiently suppress oblique chromatic aberration.

The results of Examples 1 to 19, Comparative Examples 1 to 30, and Reference Examples 1 to 10 are summarized from the viewpoint of the second embodiment. Tables 5 to 7 are graphs showing the results of Examples, Reference Examples, and Comparative Examples based on the viewpoint of the second embodiment.

In Table 5 to Table 7, the meaning of each item name is as follows. The item names "I", "II", "III", "△C ^* " and "M50M" are the same as those in Table 2 to Table 4.

R0A: Measurement result of the in-plane retardation of the horizontally oriented liquid crystal cured film (A plate) of the circular polarizing plate

RthA: Measurement result of the retardation in the thickness direction of the horizontally oriented liquid crystal cured film (A plate) of the circular polarizing plate

RthC: Measurement result of the retardation in the thickness direction of the vertically oriented liquid crystal cured film (C plate) of the circular polarizing plate

Nz: The calculation result when Rth and R0 in formula (v) are set to (RthA+RthC) and R0A (Nz coefficient)

ρ : The calculation result of the case where R(50)M and R0 in formula (vi) are set to R50M and R0 ( ρ coefficient)

R0, R0A, RthA, RthC, and R50M in Table 5 to Table 7 are 550nm wavelength delays.

In addition, in Tables 5 to 7 and Fig. 5, the reference example is also the simulation result, so the column of item name III (the result of visual evaluation) is set to an empty column.

[Table 2]

[table 3]

[Table 4]

[table 5]

[Table 6]

[Table 7]

Fig. 5 is a diagram showing Examples 1 to 19 and Comparative Examples 1 to 30 described in Tables 5 to 7 on the ρ- Nz plane. The horizontal axis of Fig. 5 represents ρ , and the vertical axis represents Nz. The line L1 and the line L2 in FIG. 5 are lines shown in the following equations, respectively.

L1: Nz=3.5 ρ +0.65

L2: Nz=3.5 ρ +0.39

Among ρ > 0 in Fig. 5, the hatched area is the area satisfying formula (vi), formula (viii), and formula (ix). In Fig. 5 ρ <0, the hatched area is the area satisfying formula (vi), formula (x) and formula (xi).

As shown in FIG. 5, all the examples are included in the hatched area, and the comparative examples are not included in the hatched area. Furthermore, from Table 5 to Table 7, the visual evaluation in Comparative Examples 1 to 30 is 3 or more. On the other hand, the visual evaluation of Examples 1 to 19 was 1 or 2. Therefore, it can be understood that all areas satisfying formula (vi), formula (viii), and formula (ix) or satisfying formula (vi), formula (x) and formula (xi) include the implementation Examples 1 to 19 can sufficiently suppress the oblique chromatic aberration.

In FIG. 5, the area 24 surrounded by the two-dot chain line is in the range where ρ is greater than 0, which is the range that satisfies the aforementioned formula (xii), formula (xiii), and formula (xiv). It can be understood that since the region 24 includes embodiments, the range of ρ greater than 0 is better to satisfy formula (xii), formula (xiii), and formula (xiv).

In FIG. 5, the area 26 surrounded by the two-dot chain line is in a range where ρ is less than 0, which is a range that satisfies the ranges of the aforementioned formula (xv), formula (xvi), and formula (xvii). It can be understood that since the region 26 includes embodiments, it is better to satisfy the range of formula (xv), formula (xvi) and formula (xvii) in the range where ρ is less than 0.

12: retardation film

12a: Slow axis (in-plane slow axis)

12b: fast axis (in-plane fast axis)

14a: Absorption axis

Claims (6)

An image display device comprising: a light-reflective image display layer, a retardation film and a polarizing film provided on the image display surface of the light-reflective image display layer, The angle formed by the absorption axis of the aforementioned polarizing film and the in-plane slow axis of the aforementioned retardation film is 45°±5°, Set the in-plane retardation of the aforementioned retardation film as R0, Let the surface of the aforementioned retardation film orthogonal to the direction of the inclination angle θ with respect to the thickness direction be the projection surface, When the in-plane fast axis of the retardation film is assumed to be the axis of rotation, the in-plane retardation of the retardation film on the projection plane is set to R( θ ) _fast , When the in-plane slow axis of the retardation film is assumed to be the axis of rotation, the in-plane retardation of the retardation film on the projection surface is set to R( θ ) _slow , When the in-plane retardation of the light-reflective image display layer on the projection surface is R( θ )M, Satisfy the following formula (i) to formula (iv), α=R0-{R( θ ) _fast +R( θ )M)‧‧‧(i) β=R0-{R( θ ) _slow -R( θ )M}‧‧‧(ii) ｜α( θ )｜+｜β( θ )｜<10nm‧‧‧(iii) ｜R( θ )M｜>0nm‧‧‧(iv). The image display device according to claim 1, wherein said R0, said R( θ ) _fast , said R( θ ) _slow, and said R( θ )M are delays at a wavelength of 550 nm. The image display device according to claim 1 or 2, wherein the inclination angle θ is 50 degrees. An image display device comprising: a light-reflective image display layer, a retardation film and a polarizing film provided on the image display surface of the light-reflective image display layer, The angle formed by the absorption axis of the aforementioned polarizing film and the in-plane slow axis of the aforementioned retardation film is 45°±5°, Set the in-plane retardation of the aforementioned retardation film as R0, Let the retardation in the thickness direction of the aforementioned retardation film be Rth, Let the surface orthogonal to the direction of the inclination angle of 50 degrees with respect to the thickness direction of the aforementioned retardation film be a projection surface, Let the in-plane retardation of the light-reflective image display layer on the projection surface be R(50)M, When Nz and ρ are expressed by formula (v) and formula (vi), the aforementioned Nz and the aforementioned ρ satisfy formula (vii), formula (viii) and formula (ix), or satisfy formula (vii), formula (x) and Formula (xi), The aforementioned R0, the aforementioned Rth, and the aforementioned R(50)M are delays to the wavelength of 550nm, Nz=(Rth/R0)+0.5‧‧‧(v) ρ =R(50)M/R0‧‧‧(vi) 3.5ρ+0.39<Nz<3.5 ρ +0.65‧‧‧(vii) ρ>0‧‧‧(viii) 0.5<Nz≦1.5‧‧‧(ix) ρ<0‧‧‧(x) -1.5<Nz<0.5‧‧‧(xi). The image display device according to any one of claims 1 to 4, wherein the phase difference film has an A plate and a C plate. The image display device according to any one of claims 1 to 5, wherein the retardation film and the polarizing film constitute a circular polarizing plate.

Images