Image display device

Abstract

The present invention addresses the problem of providing an image display device having a small hue difference. This image display device has a polarizer, a phase difference layer, and an image display element in the stated order, the angle formed by the absorption axis of the polarizer and the in-plane slow axis of the phase difference layer being 45±5°, and the image display device satisfying a predetermined relationship.

Description

Image display device

[0001] The present invention relates to an image display device.

[0002] In many cases, a flat panel display device such as an organic electroluminescence (EL) image display device is provided with a retardation layer and a polarizer for optical compensation of the image display device. As an example of the image display device, Patent Document 1 discloses an image display device having specific optical characteristics.

[0003] Japanese Patent Application Laid-Open No. 2021-076826

[0004] When an image display device displays black, it is required that the color difference between the color viewed from the front of the image display device and the color viewed from an oblique direction of the image display device (hereinafter simply referred to as "color difference") be small. The present inventors have studied the image display device described in Patent Document 1 and found that there is room for improvement in the color difference.

[0005] Therefore, an object of the present invention is to provide an image display device with small color difference.

[0006] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by the following configuration.

[0007] (1) An image display device having a polarizer, a retardation layer, and an image display element in this order, wherein the angle formed between the absorption axis of the polarizer and the in-plane slow axis of the retardation layer is 45±5°, and the image display device satisfies the relationships of the formulas (1) to (9) described below. ４５０ (45) M and Rs ４５０ (45) M is -25 to -5 nm, and Rf ５５０ (45) M and Rs ５５０ (45) M is -15 to 5 nm, and Rf ６５０ (45) M and Rs ６５０(45) The image display device according to (1), wherein M is −10 to 10 nm. (3) The image display device according to (1) or (2), further satisfying the relationship of formula (3-1), the relationship of formula (6-1), and the relationship of formula (9-1) described later. (4) The image display device according to any one of (1) to (3), wherein the retardation layer has an A plate and a C plate.

[0008] According to the present invention, an image display device with small color difference can be provided.

[0009] 1 is a cross-sectional schematic diagram of an embodiment of an image display device of the present invention. 2 is a schematic diagram showing the relationship between the absorption axis AA of a polarizer 20 and the in-plane slow axis SA of a retardation layer 30 in an image display device 10. 3 is a schematic diagram for explaining color differences. 4 is a schematic diagram showing the relationship between the terms in formulas (1) to (3). ４５０ (45) A schematic diagram for explaining the positive and negative values ​​of M. A schematic diagram when observed from the direction of the black arrow in Figure 5. A schematic diagram when observed from the direction of the white arrow in Figures 5 and 6.

[0010] The present invention will be described in detail below. The following description of the components may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0011] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the lower and upper limits. In this specification, "visible light" means light with a wavelength in the range of 380 to 780 nm. Unless otherwise specified, the measurement wavelength is 550 nm. In this specification, "in-plane slow axis" means the direction in which the refractive index is maximum in the plane. "In-plane fast axis" means the direction in which the refractive index is minimum in the plane.

[0012] In this specification, Re(λ) and Rth(λ) represent the in-plane retardation and the thickness direction retardation, respectively, at a wavelength λ. Unless otherwise specified, the wavelength λ is 550 nm. Re(λ) and Rth(λ) are values ​​measured at a wavelength λ using an AxoScan manufactured by Axometrics. By inputting the average refractive index ((nx + ny + nz) / 3) and film thickness (d (μm)) into AxoScan, the following slow axis direction (°) is calculated: Re(λ) = R0(λ) Rth(λ) = ((nx + ny) / 2 - nz) × d. Note that R0(λ) is displayed as a numerical value calculated by AxoScan, but it means Re(λ).

[0013] In this specification, the refractive indices nx, ny, and nz are measured using an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.) with a sodium lamp (λ = 589 nm) as a light source. When measuring wavelength dependency, measurements can be made using a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) in combination with an interference filter. Values ​​from the Polymer Handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can also be used. Examples of average refractive index values ​​for major optical films are listed below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).

[0014] In this specification, A plates and C plates are defined as follows. There are two types of A plates: positive A plates (positive A plates) and negative A plates (negative A plates). When the refractive index in the in-plane slow axis direction (the direction in which the in-plane refractive index is maximum) of the film is nx, the refractive index in the in-plane direction perpendicular to the in-plane slow axis is ny, and the refractive index in the thickness direction is nz, the positive A plates satisfy the relationship of formula (A1), and the negative A plates satisfy the relationship of formula (A2). Note that the positive A plates have a positive Rth, and the negative A plates have a negative Rth. Formula (A1) nx>ny≒nz Formula (A2) ny<nx≒nz Note that the above "≒" includes not only the case where the two are completely identical, but also the case where the two are substantially identical. "Substantially the same" means, for example, that "ny ≒ nz" also includes cases where (ny - nz) x d (where d is the film thickness) is -10 to 10 nm, preferably -5 to 5 nm, and "nx ≒ nz" also includes cases where (nx - nz) x d is -10 to 10 nm, preferably -5 to 5 nm. There are two types of C plates: positive C plates (positive C plates) and negative C plates (negative C plates). Positive C plates satisfy the relationship of formula (C1), while negative C plates satisfy the relationship of formula (C2). Note that positive C plates have a negative Rth value, and negative C plates have a positive Rth value. Formula (C1) nz > nx ≒ ny Formula (C2) nz < nx ≒ ny Note that the above "≒" includes not only cases where the two are completely identical, but also cases where the two are substantially identical. The term "substantially the same" includes, for example, the case where (nx-ny) x d (where d is the thickness of the film) is 0 to 10 nm, preferably 0 to 5 nm, in "nx≈ny".

[0015] In this specification, the "fixed" state refers to a state in which the alignment of the liquid crystal compound is maintained. Specifically, it is preferable that the layer has no fluidity and the alignment state is not changed by an external field or external force, usually in a temperature range of 0 to 50°C, or under more severe conditions, in a temperature range of -30 to 70°C, and that the fixed alignment state can be stably maintained.

[0016] [Image Display Device] An embodiment of the image display device of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross-sectional view of an embodiment of the image display device of the present invention. Note that the drawings in this invention are schematic diagrams, and the thickness and positional relationships of the layers do not necessarily correspond to the actual ones. The same applies to the following drawings. The image display device 10 has, from the viewing side (upper side in the drawing, in the z-axis direction), a polarizer 20, a retardation layer 30, and an image display element 40, in this order.

[0017] A feature of the image display device of the present invention is that it satisfies all of the relationships of formulas (1) to (9) described below. By satisfying all of the relationships of formulas (1) to (9) above, the color difference is reduced.

[0018] FIG. 2 also shows the relationship between the absorption axis AA of the polarizer 20 and the in-plane slow axis SA of the retardation layer 30 in the image display device 10. In FIG. 2, the in-plane slow axis SA of the retardation layer 30 is parallel to the x-axis, and the angle between the absorption axis AA of the polarizer 20 and the in-plane slow axis SA of the retardation layer 30 is 45°. In FIG. 2, the absorption axis AA of the polarizer 20 is positioned at a position rotated 45° counterclockwise with respect to the in-plane slow axis SA of the retardation layer 30, but the present invention is not limited to this embodiment, and the absorption axis AA of the polarizer 20 may also be positioned at a position rotated 45° clockwise with respect to the in-plane slow axis SA of the retardation layer 30. FIG. 3 also shows a diagram for explaining the color difference. As described above, the image display device 10 of the present invention has small color difference. Specifically, this means that there is a small difference in color between the color when the image display device 10 is set to black display and viewed under bright light from the direction of the white arrow in Fig. 3 which is parallel to the z-axis of the image display device 10, and the color when viewed from the direction of the black arrow in Fig. 3 which is a polar angle of 45° (diagonal direction of the image display device 10). Note that the line obtained by projecting the direction of the black arrow onto the image display element 10 is preferably parallel to the in-plane slow axis SA or the in-plane fast axis FA of the retardation layer 30.

[0019] <Polarizer> The image display device 10 has a polarizer 20. The polarizer 20 is a component that converts natural light (unpolarized light) into specific linearly polarized light. Examples of the polarizer 20 include absorption-type polarizers such as iodine-based polarizers, dye-based polarizers using a dichroic material, and polyene-based polarizers. Iodine-based polarizers and dye-based polarizers are produced, for example, by adsorbing iodine or a dichroic material into polyvinyl alcohol and stretching the resulting material. In addition, a protective film may be disposed on one or both sides of the polarizer 20.

[0020] The thickness of the polarizer 20 is not particularly limited, but is preferably 35 μm or less, and more preferably 1 to 25 μm, in terms of excellent handleability and optical properties. The thickness of the polarizer 20 refers to the average thickness of the polarizer 20. The average thickness is determined by measuring the thickness at any five or more points on the polarizer 20 and calculating the arithmetic average. Hereinafter, when a specific value of the thickness of a layer is indicated, it refers to the arithmetic average of the thickness measured at any five or more points on a certain layer, as described above.

[0021] <Retardation Layer> The image display device 10 has a retardation layer 30. The angle between the absorption axis AA of the polarizer 20 and the in-plane slow axis SA of the retardation layer 30 is 45°, but is not limited to this. In the image display device, the angle is 45±5° (in the range of 40 to 50°), preferably 45±3° (in the range of 42 to 48°), and more preferably 45°.

[0022] The retardation layer 30 preferably has a λ / 4 plate. The retardation layer 30 more preferably has a λ / 4 plate and an optically anisotropic layer, and even more preferably has a λ / 4 plate and an optically anisotropic layer in this order from the viewing side. That is, it is more preferable to have a λ / 4 plate and an optically anisotropic layer in this order from the tip of the z-axis arrow in FIG. 1 toward the origin. The optically anisotropic layer is preferably an optically anisotropic layer other than the λ / 4 plate described below (e.g., a positive C plate). The retardation layer 30 preferably has an A plate and a C plate, and more preferably has a positive A plate and a positive C plate in this order. The λ / 4 plate may also be a broadband λ / 4 plate, which is a laminate of a λ / 2 plate and a λ / 4 plate. The λ / 4 plate is a plate that has the function of converting linearly polarized light of a certain wavelength into circularly polarized light (or circularly polarized light into linearly polarized light), and has an Re(λ) that satisfies λ / 4. The λ / 4 plate is preferably an A plate, more preferably a positive A plate. The angle formed by the in-plane slow axis of the λ / 4 plate and the absorption axis AA of the polarizer 20 is preferably 45±5°, more preferably 45±3°, and even more preferably 45°.

[0023] The Re(450) of the λ / 4 plate is preferably 90 to 135 nm, more preferably 90 to 125 nm, and even more preferably 100 to 120 nm. The Re(550) of the λ / 4 plate is preferably 110 to 160 nm, more preferably 110 to 150 nm, and even more preferably 130 to 150 nm. The Re(650) of the λ / 4 plate is preferably 130 to 190 nm, more preferably 130 to 180 nm, and even more preferably 140 to 160 nm. The λ / 4 plate may have either normal wavelength dispersion or reverse wavelength dispersion, with reverse wavelength dispersion being preferred. Note that reverse wavelength dispersion is preferably exhibited in the visible light region. In this specification, "reverse wavelength dispersion" refers to a state in which, when the Re value of the retardation layer is measured in the visible light range, the Re value remains the same or increases as the measured wavelength increases.

[0024] The thickness of the λ / 4 plate is preferably 1.0 to 10.0 μm, and more preferably 1.0 to 5.0 μm.

[0025] Examples of methods for producing a λ / 4 plate include a method of horizontally aligning a rod-shaped polymerizable liquid crystal compound. Examples include the methods for producing positive A plates described in JP-A-2008-225281 and JP-A-2008-026730. Examples of methods for producing a λ / 4 plate with reverse wavelength dispersion include a method of horizontally aligning a liquid crystal compound with reverse wavelength dispersion. Examples of liquid crystal compounds with reverse wavelength dispersion include compounds represented by general formula (I) described in JP-A-2008-297210 (particularly, the compounds described in paragraphs

[0034] to

[0039] ), compounds represented by general formula (1) described in JP-A-2010-084032 (particularly, the compounds described in paragraphs

[0067] to

[0073] ), and compounds represented by general formula (1) described in JP-A-2016-081035 (particularly, the compounds described in paragraphs

[0043] to

[0055] ).

[0026] The retardation layer 30 preferably has an optically anisotropic layer other than the above-mentioned λ / 4 plate. The optically anisotropic layer is preferably an optically anisotropic layer having a retardation in the thickness direction, more preferably a C plate, and further preferably a positive C plate.

[0027] The Rth(450) of the optically anisotropic layer is preferably -140 to -40 nm, more preferably -120 to -60 nm, and even more preferably -120 to -70 nm. The Rth(550) of the optically anisotropic layer is preferably -120 to -20 nm, more preferably -110 to -40 nm, and even more preferably -100 to -50 nm. The Rth(650) of the optically anisotropic layer is preferably -110 to -10 nm, more preferably -100 to -30 nm, and even more preferably -90 to -60 nm. The optically anisotropic layer may have either forward or reverse wavelength dispersion, with forward wavelength dispersion being preferred.

[0028] The thickness of the optically anisotropic layer is preferably 10.0 μm or less, more preferably 0.1 to 5.0 μm, and even more preferably 0.3 to 2.0 μm.

[0029] Examples of methods for producing an optically anisotropic layer include methods for vertically aligning a rod-shaped polymerizable liquid crystal compound, such as the methods for producing a positive C plate described in JP-A-2017-187732, JP-A-2016-053709, and JP-A-2015-200861.

[0030] <Image Display Element> The image display device 10 includes an image display element 40. The image display element 40 is a display element having a pair of electrodes and a light-emitting layer sandwiched therebetween. The reflection retardation of the image display element 40 may be either forward wavelength dispersion or reverse wavelength dispersion, with reverse wavelength dispersion being preferred. Examples of the image display element 40 include an organic EL display element, a micro LED display element, and a plasma display element, with an organic EL display element or a micro LED display element being preferred. Between the electrodes of the image display element 40, layers such as a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and a protective layer may be provided in addition to the light-emitting layer, and each of these layers may have other functions. Various materials can be used to form each layer. The image display element 40 is also an element that does not include an optical compensation member on the image display surface. The image display element 40 may function as a C-plate. As described above, examples of the C-plate include a positive C-plate and a negative C-plate. In addition, the optical characteristics of the image display element 40 may change depending on the wavelength, and for example, may exhibit the characteristics of a negative C-plate on the short wavelength side (e.g., wavelengths of 450 nm and 550 nm) and the characteristics of a positive C-plate on the long wavelength side (e.g., wavelength of 650 nm).

[0031] <Other Components> The image display device may have other components in addition to the components described above. Examples of such other components include an adhesion layer and an alignment film. The image display device preferably has an adhesion layer between each component. Examples of the adhesion layer include a known pressure-sensitive adhesive layer and a known adhesive layer. A known alignment film can be used as the alignment film. The image display element may include a touch panel layer, or if the touch panel layer is not built into the image display element, a touch panel layer may be additionally laminated on the image display element. Furthermore, the image display device may have a cover glass on the outermost surface closer to the viewer than the polarizer.

[0032] [Relationships] The image display device of the present invention satisfies the relationships of the formulas (1) to (9).

[0033] 4 is a diagram showing the relationship between the terms in formulas (1) to (3). In FIG. 4, the retardation layer 30 has an in-plane slow axis SA parallel to the x-axis and an in-plane fast axis FA parallel to the y-axis. R ４５０ (0) is the in-plane retardation of the retardation layer 30 at a wavelength of 450 nm, that is, the in-plane retardation (Re(450)) of the retardation layer 30 in the direction of the white arrow in FIG. 4 (direction parallel to the z-axis direction), which corresponds to the normal direction to the surface of the retardation layer 30. That is, it is the in-plane retardation (Re(450)) of the retardation layer 30 measured from the normal direction to the surface of the retardation layer 30. ４５０ (45) is the retardation of the retardation layer 30 at a wavelength of 450 nm, measured from a first direction (see black dashed line in FIG. 4 ) which is a direction tilted by a polar angle φf (φf=45°) as shown by a black arrow with respect to the normal direction to the surface of the retardation layer 30 (the direction of the white arrow in FIG. 4 ) with the in-plane fast axis FA of the retardation layer 30 as the rotation axis. ４５０ (45) is the retardation of the retardation layer 30 at a wavelength of 450 nm, measured from a third direction (see the black dot-dashed line in FIG. 4 ), which is a direction tilted at a polar angle φs (φs=45°) with respect to the normal direction to the surface of the retardation layer 30 (the direction of the white arrow in FIG. 4 ), as indicated by the black arrow, with the in-plane slow axis SA of the retardation layer 30 as the axis of rotation. Note that, although the relationships between the terms in formulas (1) to (3) will be described in detail later, the relationships between the terms in formulas (4) to (9) are the same as the relationships between the terms described above, except that the measurement wavelengths are different.

[0034] <Relationship between formulas (1) to (3)> Formula (1) α ４５０ =R ４５０ (0)-{Rf ４５０ (45) + (Rf ４５０ (45)M / 2)} α in Equation (1) ４５０ is the retardation (Rf ４５０ (45)), and the phase difference (Rf ４５０ (45) M) and the in-plane retardation of the retardation layer (R ４５０(0)), that is, α ４５０ The smaller the value of , the smaller the difference in color between the color in the front direction of the image display device and the color in the first direction of the image display device.

[0035] R ４５０ (0) represents the in-plane retardation of the retardation layer at a wavelength of 450 nm. ４５０ (0) is the in-plane retardation (Re(450)) of the retardation layer at a wavelength of 450 nm, measured from the normal direction to the surface of the retardation layer (thickness direction of the retardation layer). ４５０ (0) is preferably 90 to 135 nm, more preferably 90 to 125 nm, and even more preferably 100 to 120 nm. ４５０ (0) can be measured, for example, using AxoScan (manufactured by Axometrics).

[0036] Rf ４５０ (45) represents the retardation of the retardation layer at a wavelength of 450 nm, measured from a first direction, which is a direction tilted at a polar angle of 45° with respect to the normal direction of the retardation layer, with the in-plane fast axis of the retardation layer as the rotation axis. ４５０ (45) is the retardation of the retardation layer measured from the first direction at a wavelength of 450 nm, and is preferably the sum of the retardation values ​​of the layers constituting the retardation layer at a wavelength of 450 nm measured from the first direction. For example, when the retardation layer is composed of a first layer, a second layer, a third layer, and an n-th layer, Rf ４５０ (45) is preferably the sum of the retardation of the first layer at a wavelength of 450 nm, the retardation of the second layer at a wavelength of 450 nm, the retardation of the third layer at a wavelength of 450 nm, and the retardation of the n-th layer at a wavelength of 450 nm. Specifically, when the retardation layer in the image display device has a λ / 4 plate and an optically anisotropic layer, Rf ４５０ (45) is determined from the retardation of the λ / 4 plate measured from the first direction and the retardation of the optically anisotropic layer measured from the first direction. ４５０ (45) is preferably 90 to 180 nm, more preferably 100 to 160 nm, and even more preferably 110 to 140 nm. ４５０(45) can be measured, for example, using AxoScan (manufactured by Axometrics).

[0037] Rf ４５０ (45) M represents a phase difference at a wavelength of 450 nm calculated from a change in the polarization state between the measurement light and the reflected light when measurement light is incident on an image display element from a first direction and reflected light reflected by the image display element is received, where, when the phase difference at a wavelength of 450 nm is measured, a plane including the first direction and the normal direction to the surface of the image display element is defined as a first plane, a direction tilted at a polar angle of 45° with respect to the normal direction to the surface of the image display element at an azimuth angle shifted by 180° from the azimuth angle of the first direction is defined as a second direction, and a plane having the second direction as its normal direction is defined as a second plane, and when the second plane shows a slow axis in a direction parallel to the first plane, Rf ４５０ (45) The value of the retardation represented by M is expressed as a positive value, and when the slow axis is shown in the direction perpendicular to the first surface on the second surface, Rf ４５０ (45) The phase difference value represented by M is expressed as a negative value. ４５０ (45) Half of M is the phase difference corresponding to one of the forward and backward paths when reflected by the image display element at a wavelength of 450 nm. Here, it is assumed that the phase difference on the forward path and the phase difference on the backward path are the same value. Also, Rf ４５０ (45) The measurement object when measuring M is not particularly limited and may be an image display element alone. When the measurement object is an image display element alone, the first direction in which measurement light is incident on the image display element is a direction corresponding to the first direction of the retardation layer of an image display device imagined when an image display device is manufactured using the image display element and the above-mentioned retardation layer, etc. In other words, the measurement light for the image display element alone is a direction corresponding to the first direction of the retardation layer in an image display device having the image display element, and is incident from a direction corresponding to the first direction on an image display element alone obtained from the image display device without changing the positional relationship with the retardation layer. Furthermore, the method for obtaining the image display element alone is not particularly limited and may be a method of manufacturing an image display element alone or a method of removing the image display element from the image display device.

[0038] "Rf" in formula (1)４５０ (45) The "1 / 2" in "M / 2" will be explained. ４５０ (45) The phase difference (reflection phase difference) of M is measured by irradiating measurement light onto the image display element from a first direction and receiving the reflected light reflected by the image display element, as described below. It is assumed that most of the measurement light is reflected by the electrode portion inside the image display element (between the incident surface and the opposite surface of the image display element). In this case, the received light essentially passes through the image display element twice in total, once on the forward path before reflection and once on the return path after reflection. Therefore, the measured phase difference is also affected twice by the phase difference of the image display element. Even if the reflection occurs on the surface of the display element, this can be considered to be the case where the film thickness of the reflective layer on the surface and inside is extremely thin, and the same can be considered. Therefore, the phase difference measured by the above measurement method corresponds to twice the phase difference corresponding to the forward or backward reflection of the image display element. When using the formulas (1) to (9), in order to match with the optically anisotropic layer assuming one-degree transmission, the phase difference of the image display element is half the measured value, that is, "Rf ４５０ (45) M / 2" is used. The same applies to the other equations described below.

[0039] FIG. ４５０ (45) A diagram for explaining the positive and negative values ​​of M. ４５０ (45) As described above, the positive and negative values ​​of M are determined by the slow axis on a specific surface when the phase difference at a wavelength of 450 nm is measured. In Fig. 5, a surface of the image display element 40 including a first direction 50 (polar angle 45°) and a normal direction to the surface of the image display element is defined as a first surface (not shown), a direction tilted at a polar angle of 45° with respect to the normal direction to the surface of the image display element at an azimuth angle shifted by 180° from the azimuth angle of the first direction 50 is defined as a second direction 51, as shown by a black dashed line, and a surface having the second direction 51 as its normal direction is defined as a second surface 60. When the second surface 60 shows a slow axis in a direction parallel to the first surface, Rf ４５０The value of (45)M is positive, and when the slow axis of the second surface 60 is in a direction perpendicular to the first surface, the value of Rf450(45)M is negative. Note that Fig. 6 shows a view observed from the direction of the solid arrow in Fig. 5, and Fig. 7 shows a view observed from the direction of the hollow arrow in Fig. 5.

[0040] FIG. 6 is a view observed from the direction of the black arrow in FIG. 5 . In FIG. 6 , the angle between the first direction 50 and the second direction 51 is 90°, and a second surface 60 is shown with the second direction 51 as its normal direction. The first direction 50, the second direction 51, and the normal direction shown in FIG. 6 are included in the same surface (first surface), and the direction of the black arrow in FIG. 5 is parallel to the normal direction of the first surface. In other words, within the first surface including the first direction 50 and the normal direction to the surface of the image display element 40, the direction that forms a 90° angle with the first direction 50 corresponds to the second direction 51. Next, FIG. 7 shows a view observed from the direction of the white arrow in FIGS. 5 and 6 . In FIG. 7 , the second direction 51 is illustrated as being positioned at the center of the second surface 60. Here, Rf ４５０ (45) When measuring the phase difference represented by M, if the second surface 60 shows a slow axis in a direction parallel to the first surface (corresponding to the a-axis direction in FIG. 7) (shows the highest refractive index), Rf ４５０ (45) The value of M is expressed as a positive value. On the other hand, Rf ４５０ (45) When measuring the phase difference represented by M, if the second surface 60 shows a slow axis in a direction perpendicular to the first surface (corresponding to the b-axis direction in FIG. 7) (if it shows the highest refractive index), Rf ４５０ (45) The value of M is expressed as a negative value. For example, when measuring the phase difference of an image display element at a wavelength of 450 nm according to the above procedure, if the magnitude (absolute value) of the phase difference is 20 nm and the slow axis is in a direction parallel to the first surface (corresponding to the a-axis direction in Figure 7), the phase difference is taken to be +20 nm. The direction of the slow axis on the second surface can be determined from the results of analysis using a reflective spectroscopic ellipsometer, which will be described later. Note that when performing analysis using a reflective spectroscopic ellipsometer, it is preferable to place a photodetector in the second direction. Rf ４５０ (45) M is preferably −50 to 50 nm, more preferably −30 to 20 nm, and even more preferably −25 to −5 nm.

[0041] Rf ４５０ (45) M can be measured, for example, using a reflective spectroscopic ellipsometer. ４５０ (45) When measuring M, an isotropic refractive index layer may be provided on the surface of the image display element. In this case, the surface of the isotropic refractive index layer is preferably smooth. When the smooth isotropic refractive index layer is provided, Rf ４５０ (45) It is easy to measure M with high accuracy. Examples of the isotropic refractive index layer include synthetic quartz and fused quartz. The isotropic refractive index layer is preferably laminated on the surface of the image display element via an adjustment layer such as index matching oil and adhesive. In addition, in order to reduce the influence of reflection at the interface between the surface of the isotropic refractive index layer and air, or at the interface between the adjustment layer and another layer in contact therewith (e.g., the image display element and fused quartz), the thickness of the isotropic refractive index layer may be increased, or, within a measurable range, the image display element may be tilted by 0.5° or more, or the light source or light receiver may be shifted by 0.5° or more in the polar angle direction, or the light source or light receiver may be shifted by 0.5° or more in the azimuthal angle direction.

[0042] Formula (2) β ４５０ =R ４５０ (0)-{Rs ４５０ (45)-(Rs ４５０ (45)M / 2)} β in Eq. (2) ４５０ means the difference between the total retardation of the retardation layer measured from the third direction at a wavelength of 450 nm and half the retardation of the image display element at a wavelength of 450 nm, and the in-plane retardation of the retardation layer, i.e., β ４５０ The smaller the value of , the smaller the difference in color between the color in the front direction of the image display device and the color in the third direction of the image display device.

[0043] R in formula (2) ４５０ (0) is R in formula (1) ４５０ It has the same meaning as (0) and the preferred embodiments are also the same.

[0044] Rs ４５０(45) represents the retardation of the retardation layer at a wavelength of 450 nm, measured from a third direction, which is a direction tilted at a polar angle of 45° with respect to the normal direction of the retardation layer, with the in-plane slow axis of the retardation layer as the rotation axis. ４５０ (45) is the retardation of the retardation layer at a wavelength of 450 nm measured from the third direction, and is preferably the sum of the retardation at a wavelength of 450 nm of each layer constituting the retardation layer measured from the third direction. For example, when the retardation layer is composed of a first layer, a second layer, a third layer, and an nth layer, Rs ４５０ (45) is preferably the sum of the retardation of the first layer at a wavelength of 450 nm, the retardation of the second layer at a wavelength of 450 nm, the retardation of the third layer at a wavelength of 450 nm, and the retardation of the n-th layer at a wavelength of 450 nm. Specifically, when the retardation layer in the image display device has a λ / 4 plate and an optically anisotropic layer, Rs ４５０ (45) is determined from the retardation of the λ / 4 plate measured from the third direction and the retardation of the optically anisotropic layer measured from the third direction. ４５０ (45) is preferably 80 to 140 nm, more preferably 90 to 130 nm, and even more preferably 100 to 120 nm. ４５０ (45) can be measured, for example, using AxoScan (manufactured by Axometrics).

[0045] Rs ４５０ (45) M represents a phase difference at a wavelength of 450 nm calculated from a change in the polarization state between the measurement light and the reflected light when measurement light is incident on the image display element from a third direction and reflected light reflected by the image display element is received, where, when the phase difference at a wavelength of 450 nm is measured, a plane including the third direction and the normal direction to the surface of the image display element is defined as the third plane, a direction tilted at a polar angle of 45° with respect to the normal direction to the surface of the image display element at an azimuth angle shifted by 180° from the third direction is defined as the fourth direction, and a plane having the fourth direction as its normal direction is defined as the fourth plane, and when the fourth plane shows a slow axis in a direction parallel to the third plane, Rs ４５０ (45) The value of the retardation represented by M is expressed as a positive value, and when the slow axis is shown in the direction perpendicular to the third surface on the fourth surface, Rs ４５０(45) The phase difference value represented by M is expressed as a negative value. ４５０ (45) M is preferably −50 to 50 nm, more preferably −30 to 20 nm, and even more preferably −25 to −5 nm. ４５０ (45) The positive and negative values ​​of the phase difference represented by M are determined by Rf ４５０ (45) It is determined in the same manner as the positive or negative value of the phase difference represented by M. ４５０ (45) The method for measuring M is Rf ４５０ (45) In the measurement method for M, the measurement can be performed in the same manner except that the first direction is changed to the third direction and the second direction is changed to the fourth direction.

[0046] Formula (3) |α ４５０ |+|β ４５０ |≦4.0 nm The left side of the formula (3) is α ４５０ The absolute value of and β ４５０ When the total value is 4.0 nm or less, the color difference becomes small. ４５０ is preferably 0 to 4.0 nm, more preferably 0 to 3.0 nm, and even more preferably 0 to 2.5 nm. ４５０ is preferably 0 to 4.0 nm, more preferably 0 to 3.0 nm, and even more preferably 0 to 2.0 nm. In particular, it is preferable to satisfy the relationship of formula (3-1), and it is more preferable to satisfy the relationship of formula (3-2). Formula (3-1) 0 nm≦|α ４５０ |+|β ４５０ |≦3.5nm Formula (3-2) 0nm≦|α ４５０ |+|β ４５０ |≦3.0 nm

[0047] α ４５０ and β ４５０ The value of can be adjusted, for example, by adjusting the refractive index anisotropy (Δn) or d (d=film thickness of the liquid crystal layer) in the optically anisotropic layer described below.

[0048] <Relationship between equations (4) to (6)> Equation (4) α ５５０ =R ５５０ (0)-{Rf ５５０ (45) + (Rf ５５０ (45)M / 2)} α in Equation (4) ５５０Each term in α is the same as above except that the measurement wavelength was changed to 550 nm. ４５０ The meanings and measurement methods are the same as those in the above.

[0049] R ５５０ (0) is preferably 100 to 180 nm, more preferably 120 to 160 nm, and even more preferably 130 to 150 nm.

[0050] Rf ５５０ (45) When the retardation layer in the image display device has a λ / 4 plate and an optically anisotropic layer, Rf ５５０ (45) is determined from the retardation of the λ / 4 plate measured from the first direction and the retardation of the optically anisotropic layer measured from the first direction. ５５０ (45) is preferably 90 to 180 nm, more preferably 100 to 170 nm, and even more preferably 130 to 160 nm.

[0051] Rf ５５０ (45) M is preferably −50 to 50 nm, more preferably −30 to 20 nm, and even more preferably −15 to 5 nm.

[0052] Formula (5) β ５５０ =R ５５０ (0)-{Rs ５５０ (45)-(Rs ５５０ (45)M / 2)} β in Equation (5) ５５０ Each term in β is the same as above, except that the measurement wavelength was changed to 550 nm. ４５０ The meanings and measurement methods are the same as those in the above.

[0053] R in formula (5) ５５０ (0) is R in formula (4) ５５０ It has the same meaning as (0) and the preferred embodiments are also the same.

[0054] Rs ５５０ (45) When the retardation layer in the image display device has a λ / 4 plate and an optically anisotropic layer, Rs ５５０ (45) is determined from the retardation of the λ / 4 plate measured from the third direction and the retardation of the optically anisotropic layer measured from the third direction. ５５０(45) is preferably 110 to 170 nm, more preferably 120 to 160 nm, and even more preferably 130 to 150 nm.

[0055] Rs ５５０ (45) M is preferably −50 to 50 nm, more preferably −30 to 20 nm, and even more preferably −15 to 5 nm.

[0056] Formula (6) |α ５５０ |+|β ５５０ |≦4.1 nm The left side of the equation (6) is α ５５０ The absolute value of and β ５５０ When the sum is 4.1 nm or less, the color difference is small. ５５０ is preferably 0 to 4.1 nm, more preferably 0 to 3.0 nm, even more preferably 0 to 2.5 nm, and particularly preferably 0 to 1.0 nm. ５５０ is preferably 0 to 4.1 nm, more preferably 0 to 3.0 nm, even more preferably 0 to 2.0 nm, and particularly preferably 0 to 1.0 nm. In particular, it is preferable to satisfy the relationship of formula (6-1), more preferably the relationship of formula (6-2), and even more preferably the relationship of formula (6-3). Formula (6-1) 0 nm≦|α ５５０ |+|β ５５０ |≦3.5nm Formula (6-2) 0nm≦|α ５５０ |+|β ５５０ |≦3.0nm Formula (6-3) 0nm≦|α ５５０ |+|β ５５０ |≦1.0 nm

[0057] α ５５０ and β ５５０ The value of can be adjusted, for example, by adjusting the refractive index anisotropy (Δn) or d (d=film thickness of the liquid crystal layer) in the optically anisotropic layer described below.

[0058] <Relationship between equations (7) to (9)> Equation (7) α ６５０ =R ６５０ (0)-{Rf ６５０ (45) + (Rf ６５０ (45)M / 2)} α in Equation (7) ６５０Each term in α is the same as above except that the measurement wavelength was changed to 650 nm. ４５０ The meanings and measurement methods are the same as those in the above.

[0059] R ６５０ (0) is preferably 100 to 190 nm, more preferably 120 to 180 nm, and even more preferably 130 to 170 nm.

[0060] Rf ６５０ (45) When the retardation layer in the image display device has a λ / 4 plate and an optically anisotropic layer, Rf ６５０ (45) is determined from the retardation of the λ / 4 plate measured from the first direction and the retardation of the optically anisotropic layer measured from the first direction. ６５０ (45) is preferably 90 to 180 nm, more preferably 100 to 170 nm, and even more preferably 130 to 160 nm.

[0061] Rf ６５０ (45) M is preferably −50 to 50 nm, more preferably −30 to 20 nm, and even more preferably −10 to 10 nm.

[0062] Formula (8) β ６５０ =R ６５０ (0)-{Rs ６５０ (45)-(Rs ６５０ (45)M / 2)} β in Equation (8) ６５０ Each term in β is β except that the measurement wavelength was changed to 650 nm. ４５０ The meanings and measurement methods are the same as those in the above.

[0063] R in formula (8) ６５０ (0) is R in formula (7) ６５０ It has the same meaning as (0) and the preferred embodiments are also the same.

[0064] Rs ６５０ (45) When the retardation layer in the image display device has a λ / 4 plate and an optically anisotropic layer, Rs ６５０ (45) is determined from the retardation of the λ / 4 plate measured from the third direction and the retardation of the optically anisotropic layer measured from the third direction. ６５０(45) is preferably 140 to 180 nm, more preferably 150 to 170 nm, and even more preferably 140 to 160 nm.

[0065] Rs ６５０ (45) M is preferably −50 to 50 nm, more preferably −30 to 20 nm, and even more preferably −10 to 10 nm.

[0066] Formula (9) |α ６５０ |+|β ６５０ |≦4.0 nm The left side of the formula (9) is α ６５０ The absolute value of and β ６５０ When the total value is 4.0 nm or less, the color difference becomes small. ６５０ is preferably 0 to 4.0 nm, more preferably 0 to 3.0 nm, even more preferably 0 to 2.5 nm, and particularly preferably 0 to 1.5 nm. ６５０ is preferably 0 to 4.0 nm, more preferably 0 to 3.0 nm, even more preferably 0 to 2.0 nm, and particularly preferably 0 to 1.5 nm. In particular, it is preferable to satisfy the relationship of formula (9-1), and it is more preferable to satisfy the relationship of formula (9-2). Formula (9-1) 0 nm≦|α ６５０ |+|β ６５０ |≦3.5nm Formula (9-2) 0nm≦|α ６５０ |+|β ６５０ |≦3.0 nm

[0067] α ６５０ and β ６５０ The value of can be adjusted, for example, by adjusting the refractive index anisotropy (Δn) or d (d=film thickness of the liquid crystal layer) in the optically anisotropic layer described below.

[0068] The image display device preferably includes a polarizer, an A plate, a C plate, and an image display element in this order. ４５０ (45) M and Rs ４５０ (45) M is -25 to -5 nm, and Rf ５５０ (45) M and Rs ５５０ (45) M is -15 to 5 nm, and Rf ６５０ (45) M and Rs６５０ (45) It is preferable that M is −10 to 10 nm. In another preferable embodiment of the image display device, it is preferable that the relationship of formula (3-1), the relationship of formula (6-1), and the relationship of formula (9-1) are further satisfied.

[0069] [Method for manufacturing an image display device] The method for manufacturing an image display device is not particularly limited, and a known method can be used. For example, a method can be used in which a retardation layer-forming composition containing a predetermined liquid crystal compound is applied to a predetermined substrate to form a coating film, the coating film is subjected to an alignment treatment, and then a curing treatment is performed to form a predetermined retardation layer, the formed retardation layer and a polarizer are laminated via an adhesive layer to obtain a laminate, and the laminate and an image display element are further attached via the adhesive layer. In addition, the retardation layer is preferably a layer formed using a retardation layer-forming composition containing a polymerizable liquid crystal compound.

[0070] The liquid crystal compound is preferably a liquid crystal compound having a polymerizable group (hereinafter also referred to as a "polymerizable liquid crystal compound"). The polymerizable liquid crystal compound is appropriately selected from the most suitable polymerizable liquid crystal compounds according to the formation of each retardation layer.

[0071] Examples of the polymerizable group contained in the polymerizable liquid crystal compound include a (meth)acryloyl group, a vinyl group, a styryl group, and an allyl group, and a (meth)acryloyl group is preferred.

[0072] Liquid crystal compounds can be classified into rod-shaped and discotic types. Each type can further be divided into low-molecular-weight and high-molecular-weight types. High-molecular-weight compounds refer to compounds with a degree of polymerization of 100 or more (see "Polymer Physics: Phase Transition Dynamics," by Masao Doi, p. 2, Iwanami Shoten, 1992). Rod-shaped or discotic liquid crystal compounds (discotic liquid crystal compounds) are preferred. The liquid crystal compound may be a mixture of two or more rod-shaped liquid crystal compounds, two or more discotic liquid crystal compounds, or a mixture of rod-shaped and discotic liquid crystal compounds. Examples of rod-shaped liquid crystal compounds include those described in claim 1 of JP-A-11-513019 and paragraphs

[0026] to

[0098] of JP-A-2005-289980. Examples of the discotic liquid crystal compound include the liquid crystal compounds described in paragraphs

[0020] to

[0067] of JP-A No. 2007-108732 and paragraphs

[0013] to

[0108] of JP-A No. 2010-244038.

[0073] The liquid crystal compound is preferably a rod-shaped liquid crystal compound. Examples of the rod-shaped liquid crystal compound include azo compounds having an azo group such as azomethines and azoxy compounds, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles. Among these, the rod-shaped liquid crystal compound preferably includes at least one selected from the group consisting of azo compounds and tolanes.

[0074] Examples of methods for adjusting the retardation layer (e.g., optically anisotropic layer) so as to satisfy the relationships of formulas (1) to (9) include adjusting the refractive index anisotropy (Δn) or d (d = film thickness of the liquid crystal layer) in the retardation layer (e.g., optically anisotropic layer). Generally, the greater the refractive index anisotropy, the greater the forward wavelength dispersion (Liquid Crystal Handbook (edited by the Liquid Crystal Handbook Editorial Committee, Maruzen Co., Ltd.)). Therefore, it is preferable to use a polymerizable liquid crystal compound with a large refractive index anisotropy or forward wavelength dispersion. Specifically, it is preferable to use a polymerizable liquid crystal compound having a plurality of aromatic rings, a polymerizable liquid crystal compound having a heteroaromatic ring, a polymerizable liquid crystal compound having a cyclohexane ring, a polymerizable liquid crystal compound having a multiple bond, or a polymerizable liquid crystal compound having a fluorine atom.

[0075] The content of the polymerizable liquid crystal compound in the composition for forming a retardation layer is preferably 60 to 99 mass %, more preferably 70 to 98 mass %, based on the total solid content of the composition for forming a retardation layer. Note that the solid content means a component capable of forming a retardation layer from which the solvent has been removed, and is considered to be a solid content even if the component is in a liquid state.

[0076] The retardation layer-forming composition may contain other components in addition to the polymerizable liquid crystal compound, such as a chiral agent, a polymerization initiator, a polyfunctional monomer, an alignment control agent (vertical alignment agent and horizontal alignment agent), a surfactant, an adhesion improver, a plasticizer, a solvent, and a photoalignable polymer.

[0077] The polymerization initiator is selected depending on the type of polymerization reaction, and examples thereof include a thermal polymerization initiator and a photopolymerization initiator. The content of the polymerization initiator in the retardation layer-forming composition is preferably 0.01 to 20 mass %, more preferably 0.5 to 10 mass %, based on the total solid content of the retardation layer-forming composition.

[0078] Examples of methods for applying the composition for forming a retardation layer include curtain coating, dip coating, spin coating, print coating, spray coating, slot coating, roll coating, slide coating, blade coating, gravure coating, and wire bar coating.

[0079] The alignment treatment can be carried out by drying the coating film at room temperature or by heating the coating film. In the case of a thermotropic liquid crystal compound, the liquid crystal phase formed by the alignment treatment can generally be transitioned by a change in temperature or pressure. In the case of a lyotropic liquid crystal compound, the transition can also be achieved by adjusting the composition ratio, such as the amount of solvent. The conditions for heating the coating film are not particularly limited, but the heating temperature is preferably 50 to 250°C, more preferably 50 to 150°C, and the heating time is preferably 10 seconds to 10 minutes. After heating the coating film, the coating film may be cooled, if necessary, before the curing treatment (light irradiation treatment) described below.

[0080] The method of curing the coating film in which the polymerizable liquid crystal compound is oriented is not particularly limited, and examples thereof include light irradiation and heat treatment. Among these, from the viewpoint of manufacturability, light irradiation is preferred, and ultraviolet irradiation is more preferred. The irradiation conditions for the light irradiation are not particularly limited, but are preferably 50 to 1000 mJ / cm. ２ The irradiation amount is preferably 1000 . The atmosphere during the light irradiation treatment is not particularly limited, but a nitrogen atmosphere is preferred. Note that the "light" during the light irradiation treatment refers to actinic rays or radiation, such as the bright line spectrum of a mercury lamp, far ultraviolet rays represented by excimer lasers, extreme ultraviolet rays (EUV light: Extreme Ultraviolet), X-rays, ultraviolet rays, and electron beams (EB). Among these, ultraviolet rays are preferred.

[0081] When another retardation layer is directly formed on the retardation layer, for example, a photo-alignable polymer may be unevenly distributed on the surface of the retardation layer, and the photo-alignable polymer on the surface of the retardation layer may be aligned by light irradiation, thereby imparting an alignment control force.

[0082] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment details, and treatment procedures shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0083] Comparative Example 1 Preparation of Image Display Element A commercially available smartphone (HUAWE P40 Pro) was disassembled, the cover glass and the polarizing plate were removed, and the organic EL substrate was taken out. The organic EL substrate was used as an image display element. The results shown in the table below confirmed that the image display element exhibited reverse wavelength dispersion.

[0084] <Preparation of Optically Anisotropic Layer C1> First, a first temporary support was prepared by the following procedure. The following various components were placed in a mixing tank, stirred, and heated at 90°C for 10 minutes. The resulting mixture was then filtered through filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm to prepare a cellulose acylate dope. The solid content concentration of the cellulose acylate dope was 23.5% by mass.

[0085] ------------------------------------------------ Cellulose acylate dope -------------------------------------------------- Cellulose acylate (acetyl substitution degree 2.86, viscosity average degree of polymerization 310) 100 parts by mass Sugar ester compound 1 (shown in the following formula (S4)) 6.0 parts by mass Sugar ester compound 2 (shown in the following formula (S5)) 2.0 parts by mass Silica particle dispersion (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 0.1 part by mass Solvent (methylene chloride / methanol / butanol) = 81 / 18 / 1 (mass ratio) --------------------------------------------------

[0086]

[0087] The cellulose acylate dope was cast using a drum film-forming machine. The dope was cast from a die onto a metal support cooled to 0°C, and then the resulting web (film) was peeled off. The drum was made of SUS.

[0088] The web obtained by casting was peeled from the drum and dried for 20 minutes in a tenter apparatus, which clipped both ends of the web with clips while transporting the film at 30 to 40°C. The web was then post-dried by zone heating while being transported with rolls. The resulting web was knurled and then wound up to obtain a first temporary support (cellulose acylate film). The film thickness of the first temporary support was 40 μm.

[0089] The following liquid crystal composition 1 was applied onto the first temporary support using a Giesser coater to form a composition layer. The first temporary support on which the composition layer had been formed was heated with hot air at 60°C for 1 minute, and then irradiated with ultraviolet light (irradiation dose 120 mJ / cm) while purging with nitrogen so that the atmosphere had an oxygen concentration of 100 ppm by volume or less. ２ , using an ultra-high pressure mercury lamp) to fix the alignment of the rod-shaped liquid crystal compound L-1, thereby forming an optically anisotropic layer C1, which is a positive C plate, and producing a transfer film 1 having a first temporary support and the optically anisotropic layer C1 disposed adjacent to the first temporary support. The thickness of the optically anisotropic layer C1 was 0.6 μm, and the polymer derived from the rod-shaped liquid crystal compound L-1 was oriented perpendicular to the surface of the transfer film 1, with the average tilt angle of the long axis direction of the rod-shaped liquid crystal compound L-1 to the surface of the transfer film 1 being 90°.

[0090] ------------------------------------------------ Liquid Crystal Composition 1 -------------------------------------------------- Rod-shaped liquid crystal compound L-1 shown below: 100 parts by mass Polyfunctional monomer M-1 shown below (UA-306I, urethane acrylate monomer, manufactured by Kyoeisha Chemical Co., Ltd.) 5.0 parts by mass Polymerization initiator (IrgacureOXE01, manufactured by BASF Corporation) 4.0 parts by mass Polymer X-1 shown below: 1.2 parts by mass Onium salt compound shown below: 1.14 parts by mass Fluorine-containing compound (fluorine-containing polymer) F-1 shown below: 0.4 parts by mass Methyl ethyl ketone 43.3 parts by mass Ethyl propionate 95.0 parts by mass Methyl isobutyl ketone 494.9 parts by mass

[0091] Rod-shaped liquid crystal compound L-1

[0092]

[0093] Multifunctional monomer M-1

[0094]

[0095] Polymer X-1 (The numerical values ​​in the following formula indicate the content (% by mass) of each repeating unit relative to all repeating units in the polymer. The weight-average molecular weight was 57,000.)

[0096]

[0097] Onium salt compounds

[0098]

[0099] Fluorine-containing polymer F-1 (the numerical values ​​in the following formula indicate the content (% by mass) of each repeating unit relative to all repeating units in the polymer. The weight-average molecular weight was 15,000.)

[0100]

[0101] <Preparation of Optically Anisotropic Layer A1> A coating solution E1 for forming a photo-alignment film having the following composition was continuously applied onto the first temporary support using a wire bar. The first temporary support on which the coating film was formed was dried with hot air at 134°C for 75 seconds, and then the coating film was irradiated with polarized ultraviolet light (8 mJ / cm ２ , using an ultra-high pressure mercury lamp) to form a photo-alignment film 1. The film thickness of the photo-alignment film 1 was 0.5 μm.

[0102] -------------------------------------------------- Coating liquid E1 for forming photoalignment film -------------------------------------------------- Polymer PA-1 (shown below) 100.00 parts by mass Acid generator PAG-1 (shown below) 6.00 parts by mass DIPEA 0.60 parts by mass Butyl acetate 625.4 parts by mass Methyl ethyl ketone 156.3 parts by mass --------------------------------------------------

[0103] Polymer PA-1 (In the formula below, the numerical value for each repeating unit represents the content (% by mass) of each repeating unit relative to all repeating units; weight average molecular weight: 45,000)

[0104]

[0105] Acid generator PAG-1

[0106]

[0107] DIPEA

[0108]

[0109] Next, the following composition F1 was applied onto the photo-alignment film 1 using a bar coater. The coating film formed on the photo-alignment film 1 was heated to 125°C with hot air, then cooled to 60°C, and then irradiated with 200 mJ / cm at a wavelength of 365 nm using a high-pressure mercury lamp in a nitrogen atmosphere. ２ The coating film was irradiated with ultraviolet light of 200 mJ / cm 2 while being heated to 120°C.２ The coating film was irradiated with ultraviolet light of 1000 kJ / cm 2 to fix the alignment of the liquid crystal compound, thereby preparing an optically anisotropic layer A1, which was a positive A plate. The thickness of the optically anisotropic layer A1 was 2.8 μm.

[0110] - 45.36 parts by mass of polymerizable liquid crystal compound LA-1 described below - 21.84 parts by mass of polymerizable liquid crystal compound LA-2 described below - 20.00 parts by mass of polymerizable liquid crystal compound LA-3 described below - 5.00 parts by mass of polymerizable liquid crystal compound LA-4 described below - 7.80 parts by mass of mixture of polymerizable liquid crystal compounds LA-5 described below - 0.50 parts by mass of polymerization initiator PI-1 described below - 0.09 parts by mass of leveling agent T-1 described below - 180.73 parts by mass of cyclopentanone - 53.98 parts by mass of methyl ethyl ketone

[0111] Polymerizable liquid crystal compound LA-1 (tBu represents a tert-butyl group)

[0112]

[0113] Polymerizable liquid crystal compound LA-2

[0114]

[0115] Polymerizable liquid crystal compound LA-3

[0116]

[0117] Polymerizable liquid crystal compound LA-4 (Me represents a methyl group)

[0118]

[0119] Polymerizable liquid crystal compound mixture LA-5 (a mixture of the following liquid crystal compounds (RA), (RB), and (RC) in a mass ratio of 84:14:2)

[0120]

[0121] Polymerization initiator PI-1

[0122]

[0123] Leveling agent T-1 (in the formula below, the numerical value for each repeating unit represents the content (mass %) of each repeating unit relative to all repeating units; weight average molecular weight: 25,000)

[0124]

[0125] <Polarizer> Next, a polyvinyl alcohol film having a thickness of 80 μm was dyed by immersing it in an aqueous iodine solution having an iodine concentration of 0.05% by mass for 60 seconds at 30° C. Next, the obtained film was immersed in an aqueous boric acid solution having a boric acid concentration of 4% by mass for 60 seconds, while being longitudinally stretched to 5 times its original length, and then dried at 50° C. for 4 minutes to obtain a polarizer having a thickness of 20 μm.

[0126] <Production of Image Display Device> A pressure-sensitive adhesive (SK-2057, manufactured by Soken Chemical & Engineering Co., Ltd.) was applied to the side of the optically anisotropic layer A1 obtained above opposite to the first temporary support side to form a pressure-sensitive adhesive layer. Next, the exposed surface of the optically anisotropic layer C1 in the transfer film 1 obtained above was bonded to the pressure-sensitive adhesive layer so that it was in close contact with the exposed surface, and then the first temporary support 1 and the photoalignment film 1 were peeled off to obtain a laminate. Next, a pressure-sensitive adhesive (SK-2057, manufactured by Soken Chemical & Engineering Co., Ltd.) was applied to one surface of the obtained polarizer to form a pressure-sensitive adhesive layer, and the laminate was then bonded to the polarizer so that the in-plane slow axis of the optically anisotropic layer A1 and the absorption axis of the polarizer formed a 45° angle with each other, with the optically anisotropic layer A1 and the polarizer in the laminate in close contact with each other. Furthermore, Corning Eagle XG glass was attached to the optically anisotropic layer C1 side of the laminate using an adhesive (SK-2057, manufactured by Soken Chemical & Engineering Co., Ltd.) to obtain an optical laminate 1. Furthermore, an image display element was laminated on the side of the glass in the optical laminate 1 opposite the optically anisotropic layer C1 side using an adhesive (SK-2057, manufactured by Soken Chemical & Engineering Co., Ltd.) to obtain an image display device 1. The image display device 1 had, from the viewing side, a polarizer, an optically anisotropic layer A1, an optically anisotropic layer C1, glass, and an image display element, in this order. It was confirmed that the glass did not affect the values ​​in the formulas (1) to (9).

[0127] [Comparative Examples 2 to 4] Each image display device was obtained in the same manner as in Comparative Example 1, except that the thickness of the optically anisotropic layer C1 in Comparative Example 1 was changed to the following values. The thickness of the optically anisotropic layer C2 was 0.70 μm. The thickness of the optically anisotropic layer C3 was 0.87 μm. The thickness of the optically anisotropic layer C4 was 0.90 μm.

[0128] Comparative Example 5 An optically anisotropic layer C5 was produced in the same manner as in Comparative Example 1, except that the rod-shaped liquid crystal compound L-1 (100 parts by mass) was replaced with the rod-shaped liquid crystal compound L-2 (100 parts by mass), thereby obtaining an image display device of Comparative Example 5.

[0129] Rod-shaped liquid crystal compound L-2

[0130]

[0131] [Comparative Example 6] The circular polarizer used in Comparative Example 30 of JP 2021-076826 A was prepared, and Corning Eagle XG glass was attached to the C-plate side of the circular polarizer using an adhesive (SK-2057, manufactured by Soken Chemical & Engineering Co., Ltd.) to obtain an optical laminate. Furthermore, an image display element was laminated on the side of the obtained optical laminate opposite the C-plate side of the glass using matching oil to obtain the image display device of Comparative Example 6.

[0132] [Comparative Example 7] The circular polarizer used in Example 17 of JP-A-2021-076826 was used instead of the circular polarizer used in Comparative Example 30 of JP-A-2021-076826. The image display device of Comparative Example 7 was obtained following the same procedure as in Comparative Example 6.

[0133] [Comparative Example 8] The circular polarizer used in Example 18 of JP-A-2021-076826 was used instead of the circular polarizer used in Comparative Example 30 of JP-A-2021-076826. The image display device of Comparative Example 8 was obtained according to the same procedure as in Comparative Example 6.

[0134] [Comparative Example 9] The circular polarizer used in Example 19 of JP-A-2021-076826 was used instead of the circular polarizer used in Comparative Example 30 of JP-A-2021-076826. The image display device of Comparative Example 9 was obtained according to the same procedure as in Comparative Example 6, except that the circular polarizer used in Example 19 of JP-A-2021-076826 was used instead.

[0135] Example 1 An optically anisotropic layer C10 was produced in the same manner as in Comparative Example 1, except that a mixture L-3 (100 parts by mass) of rod-shaped liquid crystal compounds was used instead of the rod-shaped liquid crystal compound L-1 (100 parts by mass) and the film thickness of the optically anisotropic layer was adjusted so as to obtain the retardation shown in Table 1 below. Thus, an image display device of Example 1 was obtained.

[0136] Rod-shaped liquid crystal compound mixture L-3

[0137]

[0138] Example 2 An optically anisotropic layer C11 was produced in the same manner as in Comparative Example 1, except that the rod-shaped liquid crystal compound L-1 (100 parts by mass) was replaced with the rod-shaped liquid crystal compound L-4 (100 parts by mass) and the film thickness of the optically anisotropic layer was adjusted so as to obtain the retardation shown in Table 1 below, thereby obtaining an image display element of Example 2.

[0139] Rod-shaped liquid crystal compound L-4

[0140]

[0141] Example 3 An optically anisotropic layer C12 was produced in the same manner as in Comparative Example 1, except that the rod-shaped liquid crystal compound L-1 (100 parts by mass) was replaced with the rod-shaped liquid crystal compound L-5 (100 parts by mass) and the film thickness of the optically anisotropic layer was adjusted so as to obtain the retardation shown in Table 1 below. Thus, an image display device of Example 3 was obtained.

[0142] Rod-shaped liquid crystal compound L-5

[0143]

[0144] Example 4 An optically anisotropic layer C13 was produced in the same manner as in Comparative Example 1, except that the rod-shaped liquid crystal compound L-1 (100 parts by mass) was replaced with the rod-shaped liquid crystal compound L-5 (100 parts by mass) and the film thickness of the optically anisotropic layer was adjusted so as to obtain the retardation shown in Table 1 below, thereby obtaining an image display device of Example 4.

[0145] Example 5 An optically anisotropic layer C14 was produced in the same manner as in Comparative Example 1, except that the rod-shaped liquid crystal compound L-1 (100 parts by mass) was replaced with the rod-shaped liquid crystal compound L-5 (100 parts by mass) and the film thickness of the optically anisotropic layer was adjusted so as to obtain the retardation shown in Table 1 below, thereby obtaining an image display device of Example 5.

[0146] Example 6 An optically anisotropic layer C15 was produced in the same manner as in Comparative Example 1, except that the rod-shaped liquid crystal compound L-1 (100 parts by mass) was replaced with the rod-shaped liquid crystal compound L-6 (100 parts by mass), and the film thickness of the optically anisotropic layer was adjusted so as to obtain the retardation shown in Table 1 below. Thus, an image display device of Example 6 was obtained.

[0147] Rod-shaped liquid crystal compound L-6

[0148]

[0149] [Measurement] <Values ​​Related to Retardation Layer> Using an Axoscan from Axometrics, the values ​​related to the retardation layer, A plate, and C plate shown in the table below were measured by the above-mentioned measurement method.

[0150] <Values ​​related to image display element> Fused quartz was laminated on the surface of the image display element via index matching oil to obtain a measurement sample. Note that the first direction or third direction in measuring the values ​​related to the image display element was the direction corresponding to the first direction or third direction of the retardation layer when each image display device was produced using the image display element to be measured. Using a reflective spectroscopic ellipsometer RC2 (manufactured by J.A. Woollam Co.), the values ​​related to the image display element shown in the following table were measured for the measurement sample.

[0151] [Color Difference] The color difference of each of the produced image display devices was evaluated under bright light. The display of the image display device was turned off (black state), and the reflected light when a fluorescent lamp was projected was observed from three directions: the front (viewing side), a direction parallel to the in-plane fast axis of the retardation layer at a polar angle of 45°, and a direction parallel to the in-plane slow axis of the retardation layer at a polar angle of 45°. Compared to the front, the display quality at a polar angle of 45° was evaluated according to the following criteria: "A": No color difference was visible. "B": Very slight color difference was visible. "C": Color difference was visible, but no problem in use. "D": Color difference was visible and unacceptable.

[0152] [Reflection Intensity] In [Color Difference], the reflected light was observed from each direction at a polar angle of 45°, and the intensity of the reflected light was evaluated according to the following criteria: "A": The reflected light was weak and acceptable. "B": The reflected light was strong and unacceptable.

[0153]

[0154]

[0155]

[0156] It was confirmed from the evaluation results shown in Table 3 that the present invention provides a small difference in color. From a comparison of Examples 1 to 6, it was confirmed that the effect of the present invention is more excellent when the image display device satisfies the relationship of formula (3-1), the relationship of formula (6-1), and the relationship of formula (9-1).

[0157] Examples 7 to 9 An optically anisotropic layer C18 was prepared in the same manner as in Comparative Example 1, except that rod-shaped liquid crystal compound L-7 (100 parts by mass) was used instead of rod-shaped liquid crystal compound L-1 (100 parts by mass), the film thickness of the optically anisotropic layer was adjusted so as to obtain the retardation shown in Table 4 below, and glass was laminated on the non-glossy side of commercially available aluminum foil instead of the image display element, thereby obtaining an image display device of Example 7. The image display element of Example 7 had, from the viewing side, a polarizer, an optically anisotropic layer A1, an optically anisotropic layer C1, glass, and aluminum foil, in this order. Note that the non-glossy surface of the aluminum foil was used as the measurement surface, and the Rf ４５０(45) M etc. were measured.

[0158] Rod-shaped liquid crystal compound L-7

[0159]

[0160]

[0161]

[0162]

[0163] As shown in Table 6, it was confirmed that the desired effects were also obtained in Examples 7 to 9. Although aluminum foil was used in these Examples, the same effects as described above can be obtained even when an image display element that exhibits reflectivity similar to that of aluminum foil is used.

[0164] 10 Image display device 20 Polarizer 30 Retardation layer 40 Image display element AA Absorption axis of polarizer SA In-plane slow axis of retardation layer FA In-plane fast axis of retardation layer 50 First direction 51 Second direction 60 Second or fourth surface

Claims

1. An image display device having a polarizer, a retardation layer, and an image display element in this order, wherein the angle between the absorption axis of the polarizer and the in-plane slow axis of the retardation layer is 45±5°, and the relationship of formulas (1) to (9) is satisfied. Formula (1) α ４５０ = R ４５０ (0)-{Rf ４５０ (45) + (Rf ４５０ (45)M / 2)} Formula (2) β ４５０ = R ４５０ (0) - {Rs ４５０ (45)-(Rs ４５０ (45)M / 2)} Formula (3) |α ４５０ |+|β ４５０ |≦4.0nm Formula (4) α ５５０ = R ５５０ (0)-{Rf ５５０ (45) + (Rf ５５０ (45)M / 2)} Formula (5) β ５５０ = R ５５０ (0) - {Rs ５５０ (45)-(Rs ５５０ (45)M / 2)} Formula (6) |α ５５０ |+|β ５５０ |≦4.1nm Formula (7) α ６５０ = R ６５０ (0)-{Rf ６５０ (45) + (Rf ６５０ (45)M / 2)} Formula (8) β ６５０ = R ６５０ (0) - {Rs ６５０ (45)-(Rs ６５０ (45)M / 2)} Formula (9) |α ６５０ |+|β ６５０ |≦4.0 nm R ４５０ (0) represents the in-plane retardation of the retardation layer at a wavelength of 450 nm. ４５０ (45) represents the retardation of the retardation layer at a wavelength of 450 nm, measured from a first direction, which is a direction inclined at a polar angle of 45° with respect to the normal direction to the surface of the retardation layer, with the in-plane fast axis of the retardation layer as the rotation axis. ４５０ (45) M represents a phase difference at a wavelength of 450 nm, which is calculated from a change in the polarization state between the measurement light and the reflected light by irradiating a measurement light on the image display element from the first direction and receiving the reflected light reflected by the image display element. However, when the phase difference at a wavelength of 450 nm is measured, when a surface including the first direction and a normal direction to the surface of the image display element is defined as a first surface, a direction tilted at a polar angle of 45° with respect to the normal direction to the surface of the image display element at an azimuth angle shifted by 180° from the azimuth angle of the first direction is defined as a second direction, and a surface having the second direction as a normal direction is defined as a second surface, in the case where the second surface shows a slow axis in a direction parallel to the first surface, Rf ４５０ (45) The value of the retardation represented by M is expressed as a positive value, and in the case where the second surface has a slow axis in a direction perpendicular to the first surface, Rf ４５０ (45) The phase difference represented by M is expressed as a negative value. ４５０ (45) represents the retardation of the retardation layer at a wavelength of 450 nm, measured from a third direction, which is a direction tilted at a polar angle of 45° with respect to the normal direction to the surface of the retardation layer, with the in-plane slow axis of the retardation layer as the rotation axis. ４５０ (45) M represents a phase difference at a wavelength of 450 nm, which is calculated from a change in the polarization state between the measurement light and the reflected light by irradiating a measurement light on the image display element from the third direction and receiving the reflected light reflected by the image display element, provided that, when the phase difference at a wavelength of 450 nm is measured, a third surface is a surface including the third direction and a normal direction to the surface of the image display element, a fourth direction is a direction inclined at a polar angle of 45° with respect to the normal direction to the surface of the image display element at an azimuth angle shifted by 180° from the third direction, and a fourth surface is a surface having the fourth direction as a normal direction, and when the fourth surface shows a slow axis in a direction parallel to the third surface, Rs ４５０ (45) The value of the retardation represented by M is expressed as a positive value, and in the fourth surface, when a slow axis is shown in a direction perpendicular to the third surface, Rs ４５０ (45) The value of the phase difference represented by M is expressed as a negative value. ５５０ (0) represents the in-plane retardation of the retardation layer at a wavelength of 550 nm. ５５０ (45) represents the retardation of the retardation layer at a wavelength of 550 nm measured from the first direction. ５５０ (45) represents the retardation of the retardation layer at a wavelength of 550 nm measured from the third direction. ５５０ (45) M represents a phase difference at a wavelength of 550 nm, which is calculated from a change in the polarization state between the measurement light and the reflected light by irradiating the measurement light on the image display element from the first direction and receiving the reflected light from the image display element. However, when the phase difference at the wavelength of 550 nm is measured, if the second surface shows a slow axis in a direction parallel to the first surface, Rf ５５０ (45) The value of the retardation represented by M is expressed as a positive value, and in the case where the second surface has a slow axis in a direction perpendicular to the first surface, Rf ５５０ (45) The phase difference represented by M is expressed as a negative value. ５５０ (45) M represents a phase difference at a wavelength of 550 nm, which is calculated from a change in the polarization state between the measurement light and the reflected light by irradiating the measurement light on the image display element from the third direction and receiving the reflected light from the image display element. However, when the phase difference at the wavelength of 550 nm is measured, in the fourth surface, a slow axis is shown in a direction parallel to the third surface, Rs ５５０ (45) The value of the retardation represented by M is expressed as a positive value, and in the fourth surface, when a slow axis is shown in a direction perpendicular to the third surface, Rs ５５０ (45) The value of the phase difference represented by M is expressed as a negative value. ６５０ (0) represents the in-plane retardation of the retardation layer at a wavelength of 650 nm. ６５０ (45) represents the retardation of the retardation layer at a wavelength of 650 nm measured from the first direction. ６５０ (45) represents the retardation of the retardation layer at a wavelength of 650 nm measured from the third direction. ６５０ (45) M represents a phase difference at a wavelength of 650 nm, which is calculated from a change in the polarization state between the measurement light and the reflected light by irradiating the measurement light on the image display element from the first direction and receiving the reflected light from the image display element. However, when the phase difference at the wavelength of 650 nm is measured, if the second surface shows a slow axis in a direction parallel to the first surface, Rf ６５０ (45) The value of the retardation represented by M is expressed as a positive value, and in the case where the second surface has a slow axis in a direction perpendicular to the first surface, Rf ６５０ (45) The phase difference represented by M is expressed as a negative value. ６５０ (45) M represents a phase difference at a wavelength of 650 nm, which is calculated from a change in the polarization state between the measurement light and the reflected light by irradiating the measurement light on the image display element from the third direction and receiving the reflected light from the image display element. However, when the phase difference at the wavelength of 650 nm is measured, in the fourth surface, a slow axis is shown in a direction parallel to the third surface, Rs ６５０ (45) The value of the retardation represented by M is expressed as a positive value, and in the fourth surface, when a slow axis is shown in a direction perpendicular to the third surface, Rs ６５０ (45) The value of the phase difference represented by M is expressed as a negative value.

2. RF ４５０ (45) M and Rs ４５０ (45) M is -25 to -5 nm, Rf ５５０ (45) M and Rs ５５０ (45) M is −15 to 5 nm, Rf ６５０ (45) M and Rs ６５０ (45) The image display device according to claim 1, wherein M is −10 to 10 nm.

3. The image display device according to claim 1 or 2, further satisfying the relationship of formula (3-1), the relationship of formula (6-1), and the relationship of formula (9-1). Formula (3-1) 0 nm≦|α ４５０ |+|β ４５０ |≦3.5nm Formula (6-1) 0nm≦|α ５５０ |+|β ５５０ |≦3.5nm Formula (9-1) 0nm≦|α ６５０ |+|β ６５０ |≦3.5 nm 4. The image display device according to claim 1, wherein the retardation layer has an A plate and a C plate.

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