Optical film, lens, and virtual reality display device

Abstract

The present invention addresses the problem of providing an optical film having a curved surface and being capable of suppressing occurrence of light leakage when applied to a virtual reality display device, a lens using the optical film, and a virtual reality display device using the lens. The curvature of the curved surface of the optical film is within a predetermined curvature range, and the thickness distribution on the curved surface is greater than a predetermined value, thereby solving the problem.

Description

Optical film, lens, and virtual reality display device

[0001] The present invention relates to an optical film having a curved surface, a lens using the optical film, and a virtual reality display device using the lens.

[0002] A virtual reality display device is a display device that allows a user to feel as if they are immersed in a virtual world by wearing a dedicated headset and viewing images displayed through a compound lens. While a known virtual reality display device includes an image display device and a Fresnel lens, the distance from the image display device to the Fresnel lens is large, resulting in a thick headset and poor wearability. To address this issue, as described in Patent Documents 1 and 2, a compound lens configuration called a pancake lens has been proposed, which includes an image display device, a half mirror, a retardation layer, and a reflective polarizer, and which extends the optical path and reduces the overall thickness of the headset by guiding light emitted from the image display device back and forth between the half mirror and the reflective polarizer.

[0003] Here, a reflective polarizer is a polarizer that has the function of reflecting one polarized light of incident light and transmitting the other polarized light. For example, when the polarized light incident on a reflective polarizer is linearly polarized, the reflected light and the transmitted light are linearly polarized light that are orthogonal to each other. When the polarized light incident on a reflective polarizer is circularly polarized, the reflected light and the transmitted light are circularly polarized light that have opposite rotation directions.

[0004] Known examples of reflective linear polarizers that convert transmitted and reflected light into linearly polarized light include a film obtained by stretching a dielectric multilayer film and a wire grid polarizer. Also, known examples of reflective circular polarizers that convert transmitted and reflected light into circularly polarized light include a cholesteric liquid crystal layer having a light-reflecting layer in which a cholesteric liquid crystal phase is fixed.

[0005] JP 2020-519964 A U.S. Patent No. 10,394,040

[0006] Patent Document 1 discloses a method for laminating a laminated optical body onto a spherical or aspherical curved surface of an optical lens to obtain a wide field of view, low chromatic aberration, low distortion, and an excellent MTF (modulation transfer function). However, in order to laminate a laminated optical body including an optically anisotropic layer onto a curved surface, the laminated optical body must be molded into a three-dimensional shape including a curved surface. In this process, there is a problem that the optically anisotropic layer may develop a retardation or change in the retardation possessed by the optically anisotropic layer due to stretching. Another problem with molding into a three-dimensional shape including a curved surface is that the amount of retardation developed and the amount of change vary depending on the stretching state. When the optically anisotropic layer is a retardation layer such as a λ / 4 retardation layer, the development of an undesirable retardation may result in an unintended retardation of the optically anisotropic layer. Furthermore, the optical axis of the optically anisotropic layer may change to an unintended orientation.

[0007] Also, as an optically anisotropic layer, a layer that does not normally have a retardation, such as a cholesteric liquid crystal layer, is known. When such an optically anisotropic layer that does not normally have a retardation is molded into a three-dimensional shape including a curved surface, a retardation may be newly exhibited by stretching the optically anisotropic layer. For example, when a cholesteric liquid crystal layer exhibits a retardation, problems may occur, such as the reflected polarized light becoming elliptically polarized instead of the intended circularly polarized light.

[0008] According to the inventors' investigations, it was found that the occurrence of such undesirable phase difference and change in phase difference disrupts the polarization of the light beam emitted from the image display device in a virtual reality display device using a pancake lens, causing some of the light beam to leak, leading to double images and reduced contrast.

[0009] Furthermore, the above-mentioned Patent Document 1 discloses a virtual reality display device that uses a reflective linear polarizer as a reflective polarizer, an image display panel, and a compound lens with a pancake lens configuration including a reflective linear polarizer and a half mirror. In this case, the image display panel, the reflective linear polarizer, and the half mirror are arranged in this order. When the image display panel, the reflective linear polarizer, and the half mirror are included in this order, the reflective linear polarizer needs to act like a concave mirror with respect to light rays incident from the half mirror side. Accordingly, a configuration has been proposed in which the reflective linear polarizer is molded into a curved shape to impart the reflective linear polarizer with the action of a concave mirror. Meanwhile, Patent Document 2 also discloses a virtual reality display device that similarly uses a reflective linear polarizer as a reflective polarizer, and includes an image display panel and a compound lens with a pancake lens configuration including a reflective linear polarizer and a half mirror. In Patent Document 2, the image display panel, the half mirror, and the reflective linear polarizer are arranged in this order. Here, Patent Document 2 proposes a configuration in which both the half mirror and the reflective linear polarizer are curved to improve the field curvature. In this case, the reflective linear polarizer needs to have the function of a convex mirror.

[0010] In such a composite lens, it is preferable to provide a retardation film between the reflective linear polarizer and the half mirror, which converts circularly polarized light into linearly polarized light. In this case, it is preferable to treat the reflective linear polarizer and the retardation film as a laminated optical body in which both are stacked. However, according to the inventors' studies, when a laminated optical body in which a reflective linear polarizer and a retardation film are stacked is molded into a curved shape, the phase difference of the retardation film changes. As a result, it was found that the incident linearly polarized light cannot be appropriately reflected and transmitted, resulting in increased light leakage. In virtual reality display devices, increased light leakage can cause ghosts to be visible.

[0011] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an optical film that suppresses the generation of leaked light when applied to a pancake lens-type virtual reality display device. Another object of the present invention is to provide a virtual reality display device using the optical film.

[0012] The present inventors have conducted extensive research into the above-mentioned problems and have found that the above-mentioned problems can be solved by the following configuration.

[0013] [1] An optical film having a curved surface, wherein the average radius of curvature on the curved surface is 30 to 1000 mm, and wherein, where t_max is the maximum thickness of the optical film on the curved surface and t_min is the minimum thickness, the optical film satisfies (t_max-t_min) / t_min > R-1, where R is the ratio of the surface area of ​​the curved surface to the projected area of ​​the curved surface projected onto a plane perpendicular to the optical axis. [2] The optical film according to [1], wherein the optical film includes at least a retardation layer, and the retardation layer includes at least a first optically anisotropic layer and a second optically anisotropic layer, and wherein, where t1(x) is the thickness of the first optically anisotropic layer and t2(x) is the thickness of the second optically anisotropic layer at a point X on the curved surface, the variation of t1(x) / t2(x) on the curved surface is less than 5%. [3] The optical film according to [2], wherein the variation in the slow axes of the first optically anisotropic layer and the second optically anisotropic layer is less than 2°. [4] The optical film according to [2] or [3], wherein the in-plane retardation of the first optically anisotropic layer at a wavelength of 550 nm is 120 to 160 nm, and the in-plane retardation of the second optically anisotropic layer is 200 to 320 nm. [5] The optical film according to any one of [2] to [4], wherein the first optically anisotropic layer and the second optically anisotropic layer are layers containing at least a liquid crystalline compound fixed therein. [6] The optical film according to any one of [2] to [5], wherein the first optically anisotropic layer is a layer containing at least a liquid crystalline compound fixed therein and is a positive A plate, and the second optically anisotropic layer is a layer containing at least a liquid crystalline compound fixed therein that is twisted and aligned with the helical axis in the thickness direction. [7] The optical film according to any one of [2] to [6], wherein the alignment direction of the liquid crystalline compound contained in the first optically anisotropic layer and the alignment direction of the liquid crystalline compound contained in the second optically anisotropic layer are continuous at the interface between the first optically anisotropic layer and the second optically anisotropic layer. [8] The optical film according to any one of [2] to [7], wherein the first optically anisotropic layer is a layer formed by fixing a liquid crystalline compound that is twisted and aligned with a helical axis in the thickness direction, and the second optically anisotropic layer is a layer formed by fixing a liquid crystalline compound that is twisted and aligned with a helical axis in the thickness direction, and the helical pitch of the first optically anisotropic layer is different from the helical pitch of the second optically anisotropic layer.[9] The optical film according to any one of [2] to [8], wherein the alignment direction of the liquid crystalline compound contained in the first optically anisotropic layer and the alignment direction of the liquid crystalline compound contained in the second optically anisotropic layer are continuous at the interface between the first optically anisotropic layer and the second optically anisotropic layer.

[10] The optical film according to any one of [2] to [9], wherein either the first optically anisotropic layer or the second optically anisotropic layer has reverse wavelength dispersion.

[11] The optical film according to any one of [2] to

[10] , wherein both the first optically anisotropic layer and the second optically anisotropic layer have reverse wavelength dispersion.

[12] The optical film according to any one of [1] to

[11] , wherein the optical film includes at least an absorptive polarizer, and when the absorption axis orientation of the absorptive polarizer in a curved plane is projected onto a flat surface, the variation in the projected absorption axis orientation is less than 2°.

[13] The optical film according to any one of [1] to

[12] , wherein the optical film includes at least a reflective linear polarizer, and when the orientation of the reflection axis of the reflective linear polarizer in a curved plane is projected onto a flat surface, the variation in the orientation of the projected reflection axis is less than 2°.

[14] The optical film according to any one of [1] to

[12] , wherein the optical film includes at least a reflective circular polarizer.

[15] The optical film according to

[14] , wherein the reflective circular polarizer includes a cholesteric liquid crystal layer.

[16] A lens having the optical film according to any one of [1] to

[15] .

[17] A virtual reality display device having the lens according to

[16] .

[0014] According to the present invention, an optical film can be provided that, when applied to a virtual reality display device using a pancake lens, suppresses the occurrence of light leakage. Also, according to the present invention, a virtual reality display device using the optical film can be provided.

[0015] FIG. 1 is a cross-sectional view conceptually showing an example of an optical film of the present invention. FIG. 2 is a cross-sectional view conceptually showing another example of an optical film of the present invention. FIG. 3 is a diagram for explaining an example of a method for molding an optical film of the present invention. FIG. 4 is a top view of a planar optical film used in the molding method shown in FIG. 3. FIG. 5 is an example of a pattern drawn on an optical film to investigate in-plane variations in the optical properties of the optical film. FIG. 6 is a diagram for explaining another example of a method for molding an optical film of the present invention. FIG. 7 is a diagram conceptually showing an example of a virtual reality display device of the present invention. FIG. 8 is a diagram conceptually showing another example of a virtual reality display device of the present invention.

[0016] 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.

[0017] In this specification, the liquid crystal composition and liquid crystalline compound conceptually include those that no longer exhibit liquid crystallinity due to curing or the like.

[0018] The present invention will be described in detail below with reference to the drawings. The following description of the components will be based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

[0019] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, "orthogonal" does not mean strictly 90°, but means 90°±10°, preferably 90°±5°. Furthermore, "parallel" does not mean strictly 0°, but means 0°±10°, preferably 0°±5°. Furthermore, "45°" does not mean strictly 45°, but means 45°±10°, preferably 45°±5°.

[0020] In this specification, "absorption axis" refers to the polarization direction in which absorbance is maximized in a plane when linearly polarized light is incident. "Reflection axis" refers to the polarization direction in which reflectance is maximized in a plane when linearly polarized light is incident. "Transmission axis" refers to the direction perpendicular to the absorption axis or reflection axis in a plane. "Slow axis" refers to the direction in which refractive index is maximized in a plane.

[0021] In this specification, unless otherwise specified, phase difference refers to in-plane retardation, and is referred to as Re(λ). Here, Re(λ) represents the in-plane retardation at wavelength λ, and unless otherwise specified, wavelength λ is 550 nm. Furthermore, in this specification, retardation in the thickness direction at wavelength λ is referred to as Rth(λ). Unless otherwise specified, wavelength λ is 550 nm. Re(λ) and Rth(λ) can be values ​​measured at wavelength λ using, for example, an AxoScan OPMF-1 (manufactured by OptoScience). By inputting the average refractive index ((nx + ny + nz) / 3) and film thickness (d (μm)) into AxoScan, the slow axis direction (°) Re(λ) = R0(λ) Rth(λ) = ((nx + ny) / 2 - nz) × d can be calculated.

[0022] In this specification, the terms "effective retardation" and "effective slow axis" refer to the effective in-plane retardation value calculated from the change in polarization state for a predetermined polarized light, for example, in an optical film having multiple optical films stacked together, and the effective slow axis azimuth calculated in a similar manner. Specifically, they can be determined as follows. Using a KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments), linearly polarized light with a wavelength of λ nm is incident on the optical film in the normal direction, and the transmitted light intensity of the light transmitted through the optical film is measured through an analyzer (a linear polarizer arranged at a predetermined angle). The effective in-plane retardation and effective slow axis azimuth of the optical film are obtained by simulating the transmitted light intensity measured by varying the relative angles of the optical film and the analyzer with respect to the azimuth of the incident linearly polarized light. The measurement wavelength λ nm can be selected by manually changing the wavelength selection filter or by converting the measured value using a program or the like. Unless otherwise specified, the measurement wavelength is λ = 550 nm. This also applies to other optical characteristics. This measurement method can measure the effective in-plane retardation value and effective slow axis azimuth at each position in the plane of a composite retardation plate whose optical retardation effect changes depending on the polarization of incident light. The effective retardation value can also be determined using an AxsoScan. Specifically, using an AxsoScan, light with a wavelength of λ nm is incident on the optical film from the normal direction, and the Mueller matrix of the optical film is obtained. Furthermore, from the obtained Mueller matrix, the polarization state of the exiting light when light of various polarization states is incident on the optical film can be determined. From the change in the polarization state, the in-plane retardation value of each optically anisotropic layer and the azimuth angle of the slow axis of each optically anisotropic layer can be determined. From these values, the effective retardation value of the optical film can be determined.

[0023] <Optical Film> The optical film of the present invention has a curved surface. A curved surface refers to a shape having a curvature greater than zero, and includes a developable curved surface shape and a three-dimensional curved surface shape. A developable surface is a surface that can be developed into a plane without expanding or contracting any part of the surface. Examples of developable curved surface shapes include surfaces corresponding to the peripheral surfaces of a cylinder, an elliptical cylinder, a cone, and an elliptical cone, and may be either a convex or concave curved surface. A three-dimensional curved surface refers to a curved surface that cannot be formed by deformation of a plane, i.e., a curved surface that is not developable. Examples of three-dimensional curved surfaces include surfaces corresponding to the surfaces of a sphere and a spheroid, as well as surfaces corresponding to curved surfaces whose cross sections form a parabola, hyperbola, etc. (e.g., a paraboloid of revolution). Furthermore, a three-dimensional curved surface may be either a convex or concave curved surface.

[0024] The curved surface is preferably lenticular. Examples of lenticular curved surfaces include spherical and spheroidal surfaces, and may be either convex or concave lenticular.

[0025] Preferred examples of the shape of the curved surface of the optical film of the present invention include a spherical shape, a spheroidal shape, and a paraboloidal shape.

[0026] The optical film of the present invention has a curved surface shape and exhibits a predetermined radius of curvature. That is, the curved portion of the optical film exhibits a predetermined radius of curvature. The curved portion is a non-planar portion, preferably a curved portion. In the optical film of the present invention, the average radius of curvature of the curved surface is 30 to 1,000 mm. If the average radius of curvature of the curved surface of the optical film is less than 30 mm, when the optical film is applied to a virtual reality display device, the lens size becomes small, resulting in inconveniences such as a poor wearing comfort. Conversely, if the average radius of curvature of the curved surface of the optical film exceeds 1,000 mm, when the optical film is made to function as a concave mirror, the focal length becomes long, resulting in an increase in the thickness of the virtual reality display device and insufficient improvement in field curvature. The average radius of curvature of the curved surface of the optical film is preferably 30 to 100 mm, since light leakage is further suppressed when the optical film of the present invention is applied to a pancake lens-type virtual reality display device. The radius of curvature may be constant or may vary at any position on the optical film. In the following description, the "point that the occurrence of leakage light is further suppressed when the optical film is applied to a pancake lens type virtual reality display device" is also simply referred to as the "point that the effect of the present invention is superior."

[0027] In the optical film of the present invention, when the maximum thickness of the curved surface is t_max and the minimum thickness is t_min, t_max and t_min satisfy the following formula (1): (t_max-t_min) / t_min>R-1 Formula (1) In formula (1), R is the ratio of the surface area of ​​the curved surface to the projected area of ​​the curved surface projected onto a plane perpendicular to the optical axis. Specifically, R is defined by the following formula (2): R=surface area of ​​the curved surface / projected area of ​​the curved surface projected onto a plane perpendicular to the optical axis In the following description, the "projected area of ​​the curved surface projected onto a plane perpendicular to the optical axis" will also be referred to as the "projected area of ​​the curved surface." Here, in the optical film of the present invention having a curved surface, the projected area of ​​the curved surface is, in other words, the projected area of ​​the curved surface when the curved surface is projected onto a plane perpendicular to the normal to the curved surface at the bottom (i.e., the top) of the curved surface. In the optical film of the present invention having a curved surface, the optical axis is the normal to the curved surface at the bottom of the curved surface. Therefore, when the optical film of the present invention is attached (adhered) to an optical element having an optical axis such as a lens, the optical axis of the optical element and the optical axis of the optical film of the present invention usually coincide. Note that when the optical film of the present invention having a curved surface has an optically clear optical axis as an optical element such as a lens, this optical axis is defined as the optical axis of the optical film of the present invention.

[0028] As shown in formula (1), the optical film of the present invention has a curved surface, and the curved surface has a film thickness distribution. As an example, the optical film of the present invention has a film thickness distribution in which the curved surface is thickest at the edges and gradually becomes thinner toward the bottom, with the bottom being the thinnest, as in optical film 10 conceptually shown in FIG. 1 . Alternatively, as another example, the optical film of the present invention has a film thickness distribution in which the curved surface is thinnest at the edges and gradually becomes thicker toward the bottom, with the bottom being the thickest, as in optical film 12 conceptually shown in FIG. 2 . Note that FIGS. 1 and 2 are conceptual diagrams showing a cross section of an example of the optical film of the present invention, cut along a line passing through the bottom of the curved surface, i.e., the optical axis. According to the inventors' studies, it has been found that when an optical film having a curved surface satisfies formula (1), the variation in optical performance of the curved surface of the optical film can be reduced.

[0029] As described above, when a retardation film, a cholesteric liquid crystal layer, or the like is molded into a curved surface, various inconveniences occur, such as fluctuations in retardation and changes in the optical axis orientation in the case of a retardation film, and elliptically polarized reflected circularly polarized light in the case of a cholesteric liquid crystal layer. As a result of investigations, the present inventors have found that one of the causes of these inconveniences is that the stretching during molding onto a curved surface is not isotropic, resulting in variations in the stretching ratio depending on the direction. That is, anisotropic stretching causes inconveniences such as changes in the orientation of the optical axis and fluctuations in retardation in the case of a retardation film. Furthermore, a cholesteric liquid crystal layer develops a retardation that is not inherently present, causing reflected circularly polarized light to become elliptically polarized.

[0030] In contrast, the optical film of the present invention has a maximum thickness on a curved surface that is t_max and a minimum thickness on the curved surface that is t_min, where t_max and t_min satisfy the following formula (1): (t_max-t_min) / t_min>R-1. That is, the optical film of the present invention has a relatively large film thickness distribution on a curved surface, and the larger R, calculated by dividing the surface area of ​​the curved surface by the projected area of ​​the curved surface, i.e., the larger the curvature of the curved surface, the larger the film thickness distribution. The optical film of the present invention having such a film thickness distribution is isotropically stretched during molding into a curved shape, and thus can reduce variation in optical performance on the curved surface despite having a curved surface. Therefore, when used in, for example, a pancake lens-type virtual reality display device, the optical film of the present invention can suppress light leakage and display virtual reality images with fewer ghosts.

[0031] In the optical film of the present invention, the maximum thickness t_max and minimum thickness t_min of the curved surface are measured as follows. In the projected image used to measure the projected area of ​​the curved surface described above, three equally spaced concentric circles are set around the optical axis (bottom) between the optical axis and the edge of the curved surface, as conceptually shown in FIG. 5 . If the contour of the projected image of the curved surface is not circular, the largest circle inscribed in the contour of the projected image is set, and this circle is considered to be the contour of the curved surface, and three equally spaced concentric circles are set. Next, four straight lines passing through the optical axis (bottom) are set at 45° intervals in the azimuthal direction. The thickness of the curved surface (optical film) is then measured at a total of 33 points (4 × 8 = 32 points) corresponding to the intersections of the optical axis, the concentric circles, and the contour of the curved surface with the four straight lines passing through the optical axis. The thickness of the curved surface is measured in the normal direction of the curved surface at the measurement points. The thickness of the optical film can be measured, for example, by cutting the optical film vertically (in the normal direction to the curved surface) and observing the cross section with an optical microscope, a scanning electron microscope (SEM), or the like. From the thickness measurement results at the 33 measurement points thus measured, the maximum thickness can be determined as the maximum thickness on the curved surface t_max, and the minimum thickness can be determined as the minimum thickness on the curved surface t_min.

[0032] In the optical film of the present invention, if (t_max-t_min) / t_min is R-1 or less, the film thickness distribution will be insufficient, and when the optical film of the present invention is used in a virtual image display device, for example, problems such as insufficient suppression of light leakage, the occurrence of double images, and reduced contrast will occur. (t_max-t_min) / t_min is preferably 1.5×(R-1) or more, and more preferably 2.0×(R-1) or more. There is no upper limit to (t_max-t_min) / t_min, but it is usually 5.0×(R-1) or less.

[0033] Such an optical film of the present invention can be used for various optical members such as a retardation film, an absorptive polarizer, a reflective linear polarizer, and a reflective circular polarizer.

[0034] <Retardation Film> In the following description, the "retardation film" may also be referred to as a "retardation layer." The optical film of the present invention may be a retardation layer. The retardation layer preferably includes at least a first optically anisotropic layer and a second optically anisotropic layer. In this case, when the thickness of the first optically anisotropic layer at an arbitrary point X on the curved surface is t1(x) and the thickness of the second optically anisotropic layer is t2(x), the variation of t1(x) / t2(x) on the curved surface is preferably less than 5%, more preferably less than 3%. A variation of t1(x) / t2(x) on the curved surface within the above range is preferable because it can reduce the variation in the effective in-plane retardation of the retardation layer. The variation in the effective in-plane retardation is preferably less than 5%, more preferably less than 3%, from the viewpoint of reducing light leakage in a virtual reality display device. Furthermore, when the variation of t1(x) / t2(x) on the curved surface is within the above range, when the orientation of the effective slow axis of the retardation layer is projected onto a plane perpendicular to the optical axis of the curved surface, the variation of the orientation of the projected slow axis can be reduced, which is preferable.

[0035] When the optical film of the present invention is used as a retardation layer, the variation in the slow axis orientation is preferably small. Specifically, from the viewpoint of reducing light leakage from a virtual reality display device, the variation in the slow axis orientation is preferably less than 2°, more preferably less than 1°. Furthermore, the variation in the slow axes of the first optically anisotropic layer and the second optically anisotropic layer is preferably less than 2°, more preferably less than 1°.

[0036] When the retardation layer has a first retardation layer and a second retardation layer, it is also preferable that the laminate film has an effective in-plane retardation of the first optically anisotropic layer in the range of 120 nm to 160 nm at a wavelength of 550 nm, and an effective in-plane retardation of the second optically anisotropic layer in the range of 200 to 320 nm. In this case, it is preferable that the angle between the slow axis direction of the first optically anisotropic layer and the slow axis direction of the second optically anisotropic layer is 60°±10°. When the in-plane retardation of each optically anisotropic layer is within the above range, the retardation layer can achieve an effective in-plane retardation of λ / 4 over a wide wavelength range of visible light, and can convert linearly polarized light into circularly polarized light over the same wavelength range. Similarly, circularly polarized light can be converted into linearly polarized light.

[0037] In addition, when the retardation layer has a first retardation layer and a second retardation layer, it is preferable that either the first optically anisotropic layer or the second optically anisotropic layer has reverse wavelength dispersion, and it is more preferable that both the first optically anisotropic layer and the second optically anisotropic layer have reverse wavelength dispersion. In this case, the effective in-plane retardation can be made more precisely λ / 4 retardation over a wide wavelength range of visible light, which is preferable. Reverse wavelength dispersion refers to the fact that, when the in-plane retardation (Re) value is measured at a specific wavelength (visible light range), the Re value increases as the measured wavelength increases. It is preferable that Re(450) / Re(550)<1.00 and Re(650) / Re(550)>1.00 are satisfied. An optically anisotropic layer having reverse wavelength dispersion can be produced by uniaxially stretching a polymer film such as a modified polycarbonate resin film having reverse wavelength dispersion, for example, with reference to JP-A-2017-049574, etc. Alternatively, an optically anisotropic layer having reverse wavelength dispersion can be produced by orienting and fixing a rod-shaped liquid crystal compound having reverse wavelength dispersion, for example, with reference to JP-A-2020-084070, etc.

[0038] When the retardation layer has a first retardation layer and a second retardation layer, it is also preferable that at least one of the first optically anisotropic layer and the second optically anisotropic layer is a layer in which a liquid crystal compound is fixed in a twisted orientation with the thickness direction as a helical axis.By adopting this configuration, the retardation layer can make the effective in-plane retardation be λ / 4 retardation over a wide wavelength range of visible light, and can convert linearly polarized light into circularly polarized light over a wide wavelength range of visible light.Similarly, it can convert circularly polarized light into linearly polarized light.

[0039] When the retardation layer has a first retardation layer and a second retardation layer, the first optically anisotropic layer and the second optically anisotropic layer are preferably layers in which at least a liquid crystalline compound is fixed. The liquid crystalline compound can be aligned in any direction using an alignment film or the like, thereby simplifying the manufacturing process of the retardation layer. It is also preferable that the alignment direction of the liquid crystalline compound contained in the first optically anisotropic layer and the alignment direction of the liquid crystalline compound contained in the second optically anisotropic layer are continuous at the interface between the first optically anisotropic layer and the second optically anisotropic layer. With this configuration, the refractive index difference at the interface between the first optically anisotropic layer and the second optically anisotropic layer can be reduced, and interfacial reflection can be suppressed, thereby suppressing the disturbance of the polarization state due to interfacial reflection and further reducing ghost images. In this specification, the alignment direction of the liquid crystal compound being continuous at the interface means that the in-plane slow axis of the first optically anisotropic layer at the surface facing the second optically anisotropic layer is parallel to the in-plane slow axis of the second optically anisotropic layer at the surface facing the first optically anisotropic layer. In other words, when the alignment direction of the liquid crystal compound is continuous at the interface, the angle formed by the in-plane slow axis of the first optically anisotropic layer at the surface facing the second optically anisotropic layer and the in-plane slow axis of the second optically anisotropic layer at the surface facing the first optically anisotropic layer is within 10° (0 to 10°).

[0040] When the retardation layer has a first retardation layer and a second retardation layer, it is also preferable that the first optically anisotropic layer is a positive A plate, and the second optically anisotropic layer is a layer formed by fixing a liquid crystal compound that is twisted and aligned with the thickness direction as the helical axis. Here, a positive A plate is a retardation layer having a certain Re and an Rth that is substantially half the value of Re. A positive A plate can be obtained, for example, by horizontally aligning a rod-shaped liquid crystal compound. In this case, it is also preferable that the alignment direction of the liquid crystal compound contained in the first optically anisotropic layer and the alignment direction of the liquid crystal compound contained in the second optically anisotropic layer are continuous at the interface between the first optically anisotropic layer and the second optically anisotropic layer. It is preferable that the product of the refractive index anisotropy Δn1 and the thickness d1 at a wavelength of 550 nm of the first optically anisotropic layer satisfies the following formula (3): Formula (3) 140 nm ≦ Δn1d1 ≦ 220 nm Furthermore, it is preferable that the product of the refractive index anisotropy Δn2 and the thickness d2 at a wavelength of 550 nm of the second optically anisotropic layer satisfies the following formula (4). Formula (4) 150 nm ≦ Δn2d2 ≦ 230 nm Furthermore, it is preferable that the second optically anisotropic layer is a layer formed by fixing a liquid crystal compound that is twisted and aligned with the thickness direction as the helical axis, and the twist angle is preferably 85 ± 20 °. When the first optically anisotropic layer and the second optically anisotropic layer have the above configuration, the retardation layer can be a λ / 4 retardation layer over a wider wavelength range. For example, the retardation layer described above can be referenced to those disclosed in International Publication No. 2021 / 261435.

[0041] When the retardation layer has a first retardation layer and a second retardation layer, it is also preferable that the first optically anisotropic layer and the second optically anisotropic layer are layers in which a liquid crystal compound is fixed and twisted with the thickness direction as the helical axis.In this case, it is preferable that the helical pitch of the first optically anisotropic layer is different from the helical pitch of the second optically anisotropic layer.Furthermore, it is also preferable that the alignment direction of the liquid crystal compound contained in the first optically anisotropic layer and the alignment direction of the liquid crystal compound contained in the second optically anisotropic layer are continuous at the interface between the first optically anisotropic layer and the second optically anisotropic layer.In this case, it is preferable that the product of the refractive index anisotropy Δn1 and the thickness d1 at a wavelength of 550 nm of the first optically anisotropic layer satisfies the following formula (5): 252 nm≦Δn1d1≦312 nm (5) The first optically anisotropic layer is preferably a layer formed by fixing a liquid crystal compound that is twisted and aligned with the thickness direction as the helical axis, and the twist angle is preferably 26.5±10°. Furthermore, the second optically anisotropic layer preferably has a product of the refractive index anisotropy Δn2 at a wavelength of 550 nm and the thickness d2 that satisfies the following formula (6): 110 nm≦Δn2d2≦170 nm (6) The second optically anisotropic layer is preferably a layer formed by fixing a liquid crystal compound that is twisted and aligned with the thickness direction as the helical axis, and the twist angle is preferably 78.6±10°. When the first optically anisotropic layer and the second optically anisotropic layer have the above configuration, the retardation layer can be a λ / 4 retardation layer over a wider wavelength range. The retardation layer as described above can be, for example, that disclosed in International Publication No. 2021 / 261435. Also preferred is an embodiment in which both the first optically anisotropic layer and the second optically anisotropic layer are positive A plates.

[0042] [Method of Adhesion of Each Layer] When the retardation layer has a first retardation layer and a second retardation layer, the first optically anisotropic layer and the second optically anisotropic layer may be manufactured in separate processes and then laminated together. The lamination can be performed using an adhesive such as an adhesive or a pressure-sensitive adhesive. From the viewpoint of suppressing interfacial reflection, it is preferable that the adhesive layer between each layer has a refractive index matching with the first optically anisotropic layer and the second optically anisotropic layer. The thickness of the adhesive layer can also be set to an appropriate thickness so as to suppress interfacial reflection with the first optically anisotropic layer and the second optically anisotropic layer.

[0043] Furthermore, from the viewpoint of suppressing interfacial reflection, it is also preferable that the adhesive layer between each layer has a thickness of 100 nm or less. When the adhesive layer has a thickness of 100 nm or less, light in the visible range does not sense a difference in refractive index, and unnecessary reflection can be suppressed. The thickness of the adhesive layer is more preferably 50 nm or less. A method for forming an adhesive layer having a thickness of 100 nm or less can be, for example, a method in which a ceramic adhesive such as a silicon oxide (SiOx layer) is vapor-deposited on the adhesive surface. Before bonding, the adhesive surface may be subjected to a surface modification treatment such as plasma treatment, corona treatment, or saponification treatment, and a primer layer may be applied. Furthermore, when there are multiple adhesive surfaces, the type and thickness of the adhesive layer can be adjusted for each adhesive surface.

[0044] Specifically, an adhesive layer having a thickness of 100 nm or less can be provided by, for example, the following steps (1) to (3): (1) The layer to be laminated is attached to a temporary support made of a glass substrate. (2) A SiOx layer having a thickness of 100 nm or less is formed on both the surface of the layer to be laminated and the surface of the layer to be laminated by vapor deposition or the like. Vapor deposition can be performed using, for example, a vapor deposition device (model number ULEYES) manufactured by ULVAC, Inc., using SiOx powder as the vapor deposition source. It is also preferable to subject the surface of the formed SiOx layer to plasma treatment. (3) After the formed SiOx layers are attached to each other, the temporary support is peeled off. The bonding is preferably performed at a temperature of, for example, 120°C.

[0045] The application of adhesives and pressure-sensitive adhesives to each layer, the formation of adhesive layers such as SiOx layers, and bonding may be performed by roll-to-roll or sheet-to-sheet. The roll-to-roll method is preferable in terms of improving productivity and reducing axial misalignment of layers. On the other hand, the sheet-to-sheet method is preferable in terms of being suitable for small-lot, high-mix production, and being able to select a special bonding method such as one with an adhesive layer thickness of 100 nm or less.

[0046] When the retardation layer has a first retardation layer and a second retardation layer, examples of a method for applying the adhesive and pressure-sensitive adhesive to the adherend include known methods such as roll coating, gravure printing, spin coating, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, die coating, spraying, and inkjet printing.

[0047] [Direct Coating of Each Layer] When the retardation layer has a first retardation layer and a second retardation layer, it is also preferable that there is no adhesive layer between the first optically anisotropic layer and the second optically anisotropic layer. When forming a layer, the adhesive layer can be eliminated by directly coating the composition on an adjacent layer that has already been formed. For example, when forming a second optically anisotropic layer on a first optically anisotropic layer, the adhesive layer can be eliminated by directly coating the composition that will become the second optically anisotropic layer on the already formed first optically anisotropic layer. Furthermore, when one or both of the adjacent layers contain a liquid crystal compound, it is preferable that the alignment direction of the liquid crystal compound continuously changes at the interface in order to reduce the refractive index difference in all directions in the plane. For example, a composition for forming a second optically anisotropic layer containing a liquid crystal compound can be directly coated on the first optically anisotropic layer containing a liquid crystal compound, and the alignment direction of the liquid crystal compound in the second optically anisotropic layer can be continuously aligned at the interface due to the alignment regulating force of the liquid crystal compound in the first optically anisotropic layer.

[0048] [One-component two-layer coating of each layer] In addition, when the retardation layer has a first retardation layer and a second retardation layer, the first optically anisotropic layer and the second optically anisotropic layer can be formed by coating the same forming composition, and then separating them into two layers by various methods, and each layer can be formed into the first optically anisotropic layer and the second optically anisotropic layer. Such a retardation layer can be produced, for example, by the following steps 1 to 5. Step 1: A polymerizable liquid crystal composition containing a chiral agent containing at least a photosensitive chiral agent whose helical twisting force changes upon irradiation with light, and a liquid crystalline compound having a reverse wavelength dispersion having a polymerizable group is applied to a support to form a composition layer. (Note: In the description of steps 2 to 5 below, the "liquid crystalline compound having a reverse wavelength dispersion having a polymerizable group" is also simply referred to as the "liquid crystalline compound.") Step 2: A step of subjecting the composition layer to a heat treatment to align the liquid crystalline compound in the composition layer. Step 3: After step 2, a step of irradiating the composition layer with light under conditions of an oxygen concentration of 1% by volume or more. Step 4: After step 3, a step of subjecting the composition layer to a heat treatment. Step 5: After step 4, a curing treatment is performed on the composition layer to fix the alignment state of the liquid crystalline compound, forming a first optically anisotropic layer and a second optically anisotropic layer. The preparation process of the retardation layer as described above can be, for example, referred to the steps disclosed in International Publication No. WO 2021 / 261435.

[0049] It is also preferable that the retardation layer includes an optically anisotropic layer in addition to the first optically anisotropic layer and the second optically anisotropic layer. When the retardation layer includes three or more optically anisotropic layers, the degree of freedom in designing the retardation layer increases, and it becomes easier to make the effective in-plane retardation a λ / 4 retardation over a wide wavelength range of visible light, which is preferable.

[0050] <Absorptive Polarizer> The optical film of the present invention may be an absorptive polarizer. An absorptive polarizer absorbs linearly polarized light in the absorption axis direction of incident light and transmits linearly polarized light in the transmission axis direction. When the absorption axis direction of the absorptive polarizer in the curved plane is projected onto a flat surface, the variation in the projected absorption axis direction is preferably less than 2°, more preferably less than 1°. A general polarizer can be used as the absorptive polarizer. For example, a polarizer obtained by dyeing a dichroic substance onto polyvinyl alcohol or other polymer resin and stretching the polymer resin to orient the dichroic substance may be used, or a polarizer obtained by utilizing the orientation of a liquid crystal compound to orient the dichroic substance may be used. From the viewpoints of availability and increasing the polarization degree, a polarizer obtained by dyeing polyvinyl alcohol with iodine and stretching the polymer resin is preferred.

[0051] The thickness of the absorptive polarizer is preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less. A thin linear polarizer can prevent cracking and breakage of the film when the laminated optical body is stretched or molded. The single-plate transmittance of the absorptive polarizer is preferably 40% or more, more preferably 42% or more. The degree of polarization is preferably 90% or more, more preferably 95% or more, and even more preferably 99% or more. In this specification, the single-plate transmittance and degree of polarization of the absorptive polarizer are measured using an automatic polarizing film measuring device: VAP-7070 (manufactured by JASCO Corporation). The direction of the transmission axis of the absorptive polarizer preferably coincides with the direction of the polarization axis of light converted into linearly polarized light by the retardation layer. For example, when the retardation layer is a layer having a quarter-wave retardation, the angle between the transmission axis of the absorptive polarizer and the slow axis of the retardation layer is preferably approximately 45°.

[0052] The absorptive polarizer is also preferably a light-absorbing anisotropic layer containing a liquid crystal compound and a dichroic substance. Absorptive polarizers containing a liquid crystal compound and a dichroic substance are preferred because they can be thinned and are less likely to crack or break even when stretched or molded. The thickness of the light-absorbing anisotropic layer is not particularly limited, but from the viewpoint of thinning, it is preferably 0.1 to 8 μm, more preferably 0.3 to 5 μm. Absorptive polarizers containing a liquid crystal compound and a dichroic substance can be produced, for example, with reference to JP 2020-023153 A. From the viewpoint of improving the polarization degree of the absorptive polarizer, the light-absorbing anisotropic layer preferably has a degree of orientation of the dichroic substance of 0.95 or more, more preferably 0.97 or more.

[0053] Furthermore, in order to minimize the influence on various sensors that use near-infrared light as a light source, such as those for eye tracking, facial expression recognition, and iris authentication, which are incorporated into optical systems such as virtual reality display devices and electronic viewfinders, the absorptive polarizer is preferably transparent to near-infrared light.

[0054] <Reflective Linear Polarizer> The optical film of the present invention may be a reflective linear polarizer. When the orientation of the reflection axis in the curved surface of the reflective linear polarizer is projected onto a flat surface, the variation in the orientation of the projected reflection axis is preferably less than 2°, more preferably less than 1°. Examples of the reflective linear polarizer that can be used include a film obtained by stretching a dielectric multilayer film and a wire grid polarizer.

[0055] <Reflective Circular Polarizer> The optical film of the present invention may be a reflective circular polarizer. As the reflective circular polarizer, for example, a cholesteric liquid crystal layer can be used.

[0056] [Cholesteric Liquid Crystal Layer] A cholesteric liquid crystal layer is an optical element that separates incident light into right-handed circularly polarized light and left-handed circularly polarized light, specularly reflecting one circularly polarized light and transmitting the other circularly polarized light. For example, a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase can be used, as described in JP 2020-060627 A. Films formed by fixing a cholesteric liquid crystal phase are preferred because they have a high degree of polarization of transmitted light despite being thin. Cholesteric liquid crystal layers are preferred as films used for curved surface molding, because they suppress a decrease in polarization degree and / or distortion of the polarization axis when stretched or molded into a three-dimensional shape. Furthermore, a decrease in polarization degree due to distortion of the polarization axis is less likely to occur.

[0057] The cholesteric liquid crystal layer preferably has a blue light-reflecting layer having a reflectance of 40% or more for light with a wavelength of 460 nm, a green light-reflecting layer having a reflectance of 40% or more for light with a wavelength of 550 nm, a yellow light-reflecting layer having a reflectance of 40% or more for light with a wavelength of 600 nm, and a red light-reflecting layer having a reflectance of 40% or more for light with a wavelength of 650 nm. This configuration is preferable because it can exhibit high reflective properties over a wide wavelength range in the visible range. Note that the above-mentioned reflectance is the reflectance when unpolarized light is incident on the cholesteric liquid crystal layer at each wavelength. Furthermore, the blue light-reflecting layer, green light-reflecting layer, yellow light-reflecting layer, and red light-reflecting layer, which are formed by fixing a cholesteric liquid crystal phase, may have a pitch gradient layer in which the helical pitch of the cholesteric liquid crystal phase is continuously changed in the thickness direction. For example, referring to JP 2020-060627 A, etc., the green light-reflecting layer and the yellow light-reflecting layer can be continuously produced.

[0058] It is also preferable that the cholesteric liquid crystal layer has a light-reflecting layer formed by fixing a cholesteric liquid crystal phase containing a rod-shaped liquid crystal compound, and a light-reflecting layer formed by fixing a cholesteric liquid crystal phase containing a discotic liquid crystal compound. With such a configuration, the cholesteric liquid crystal phase containing the rod-shaped liquid crystal compound has a positive Rth, whereas the cholesteric liquid crystal phase containing the discotic liquid crystal compound has a negative Rth, so that the Rths cancel each other out, thereby suppressing the occurrence of ghosts even with respect to light incident from an oblique direction, which is preferable.

[0059] The manner in which Rth is cancelled out can be expressed by the following formula. In an optical laminate film having n light-reflecting layers, when the light-reflecting layers are named L1, L2, L3, ..., Ln in order from the light source side, the sum of the Rth of each layer from light-reflecting layer L1 to light-reflecting layer Li is SRthi. Specifically, it is expressed by the following formula: SRth1=Rth1 SRth2=Rth1+Rth2... SRthi=Rth1+Rth2... +Rthi... SRthn=Rth1+Rth2... +Rthi... +Rthn The absolute values ​​of all these SRthi (SRth1 to SRthn) are preferably 0.3 μm or less, more preferably 0.2 μm or less, and even more preferably 0.1 μm or less. The Rthi of each layer in the above formula is determined by the above-mentioned formula for calculating Rth.

[0060] The thickness of the cholesteric liquid crystal layer is not particularly limited, but from the viewpoint of thinning, it is preferably 30 μm or less, and more preferably 15 μm or less.

[0061] Furthermore, when the cholesteric liquid crystal layer is stretched, molded, or the like, the reflection wavelength range of the cholesteric liquid crystal layer may shift, so it is preferable to select the reflection wavelength range in advance, taking into account this wavelength shift. For example, when an optical film formed by fixing a cholesteric liquid crystal phase is used as the cholesteric liquid crystal layer, the film may be stretched by stretching or molding, which may result in a smaller helical pitch of the cholesteric liquid crystal phase. Therefore, it is preferable to set the helical pitch of the cholesteric liquid crystal phase to a large value in advance. Furthermore, in consideration of a short-wave shift in the reflection wavelength range due to stretching or molding, it is also preferable that the cholesteric liquid crystal layer has an infrared light-reflecting layer with a reflectance of 40% or more at a wavelength of 800 nm. Furthermore, when the stretching ratio during stretching and molding is not uniform in the plane, an appropriate reflection wavelength range may be selected at each location in the plane according to the wavelength shift due to stretching. That is, there may be regions in the plane where the reflection wavelength range differs. Furthermore, in consideration of the fact that the stretching ratio will differ in each location in the plane, it is also preferable to set the reflection wavelength range in advance to be wider than the required wavelength range.

[0062] (Method for Producing a Cholesteric Liquid Crystal Layer) A cholesteric liquid crystal layer can be formed by coating a liquid crystal composition, which is prepared by dissolving a liquid crystal compound, a chiral agent, a polymerization initiator, and optionally a surfactant, in a solvent, on a support or on an underlayer formed on a support, drying the coating to obtain a coating film, orienting the liquid crystal compound in the coating film, and irradiating the coating film with actinic rays to harden the liquid crystal composition. This allows the formation of a cholesteric liquid crystal layer having a cholesteric liquid crystal structure with fixed cholesteric regularity.

[0063] [Coating Method] Examples of the method for coating the liquid crystal composition include known methods such as roll coating, gravure printing, spin coating, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, die coating, spraying, and inkjet printing.

[0064] [Method of imparting in-plane distribution to helical pitch] As a method of imparting in-plane distribution to the helical pitch of a cholesteric liquid crystal layer, for example, there is a method of using a chiral agent whose helical twisting power (HTP) changes upon photoisomerization.

[0065] This will be explained in detail below. A cholesteric liquid crystal layer is aligned by applying (and optionally subsequently heating) a liquid crystal composition containing a chiral agent whose HTP changes upon photoisomerization, and then irradiating the layer with light corresponding to the photoisomerization. This changes the HTP of the chiral agent, which in turn changes the helical pitch of the cholesteric liquid crystal layer, thereby changing the reflection wavelength. By utilizing this property, the aligned cholesteric liquid crystal layer is irradiated with light in a pattern using an exposure mask or the like to cause photoisomerization, resulting in a pattern in which the reflection wavelength is changed only in the irradiated region. After obtaining the pattern, the entire cholesteric liquid crystal layer is exposed to light to harden the liquid crystal composition, polymerizing the liquid crystal composition, ultimately resulting in a cholesteric liquid crystal layer with an in-plane distribution of helical pitch (patterned cholesteric liquid crystal layer). After hardening, the patterned cholesteric liquid crystal layer no longer undergoes photoisomerization and has stable properties.

[0066] To effectively form this pattern, it is preferable to be able to separate the light irradiation for photoisomerization from the light irradiation for curing. In other words, to effectively form this pattern, it is preferable that when one of photoisomerization and curing is progressing, the other is not progressing as much as possible. Measures for separating the two include, for example, separating them based on oxygen concentration and on exposure wavelength.

[0067] First, regarding oxygen concentration, photoisomerization is less affected by oxygen concentration, but the higher the oxygen concentration, the more difficult curing occurs. The fact that the higher the oxygen concentration, the more difficult curing occurs also depends on the initiator used. Therefore, it is preferable to perform photoisomerization under conditions of high oxygen concentration, for example, in the atmosphere, and to perform curing under conditions of low oxygen concentration, for example, using a nitrogen atmosphere with an oxygen concentration of 300 volume ppm or less. This makes it easier to distinguish between photoisomerization and curing.

[0068] Regarding the exposure wavelength, photoisomerization of the chiral agent occurs at the absorption wavelength of the chiral agent, and curing occurs at the absorption wavelength of the photopolymerization initiator. Therefore, if the chiral agent and the photopolymerization initiator are selected so that their absorption wavelengths differ, it becomes possible to distinguish between photoisomerization and curing depending on the exposure wavelength.

[0069] If necessary, one or both of the photoisomerization and curing may be carried out under heating, preferably at a temperature of 25 to 140°C, more preferably at 30 to 100°C.

[0070] As an alternative to the method using a chiral agent whose HTP changes upon photoisomerization, there is also a method in which the agent is first cured in a pattern and then isomerized in the uncured regions. That is, the aligned cholesteric liquid crystal phase is first irradiated with light for curing in a pattern using an exposure mask or the like. Here, the previously cured regions can no longer undergo pitch change due to photoisomerization. Therefore, by subsequently irradiating the entire surface with light for photoisomerization, a pitch change due to photoisomerization occurs only in the previously uncured regions, resulting in a change in the reflection wavelength. In this case, after obtaining a pattern, the entire cholesteric liquid crystal layer is exposed to light for curing the liquid crystal composition, and the liquid crystal composition is polymerized, thereby obtaining the final patterned cholesteric liquid crystal layer.

[0071] <Laminated Optical Body> The optical film of the present invention may be a laminated optical body formed by laminating multiple functional layers. The laminated optical body as the optical film of the present invention may have at least one functional layer that is the optical film of the present invention, but the more optical films of the present invention, the better, and all of the functional layers may be the optical films of the present invention. Examples of functional layers include a retardation layer, a reflective linear polarizer, a reflective circular polarizer, and an absorptive polarizer. By laminating these, various optical functions required in a virtual reality display device can be integrated. This allows the process of attaching the laminated optical body to an image display device, a lens, etc. to be performed only once, thereby reducing manufacturing costs.

[0072] The laminated optical body may further include different functional layers for the purpose of further improving the optical effect, such as a positive C plate, an anti-reflection layer, an ultraviolet absorbing layer, and a hard coat layer.

[0073] <Positive C Plate> A positive C plate is a retardation layer having an Re of substantially zero and an Rth of a negative value. A positive C plate can be obtained, for example, by vertically aligning a rod-shaped liquid crystal compound. Details of the manufacturing method of a positive C plate can be found in, for example, JP 2017-187732 A, JP 2016-053709 A, and JP 2015-200861 A. The positive C plate functions as an optical compensation layer for increasing the degree of polarization of transmitted light with respect to obliquely incident light. The positive C plate can be disposed at any position in the laminated optical body, and multiple positive C plates may be disposed.

[0074] The positive C plate may be disposed adjacent to or within the retardation layer. For example, when a layer formed by immobilizing a rod-shaped liquid crystal compound is used as the retardation layer, the retardation layer has a positive retardation Rth (thickness retardation). In this case, when light is incident on the retardation layer from an oblique direction, the retardation Rth may change the polarization state of the transmitted light, resulting in a decrease in the degree of polarization of the transmitted light. Having a positive C plate within or near the retardation layer is preferable because it can suppress changes in the polarization state of obliquely incident light and reduce the decrease in the degree of polarization of the transmitted light. The positive C plate is preferably disposed on the side of the retardation layer opposite the linear polarizer, but may be disposed elsewhere. In this case, the in-plane retardation Re of the positive C plate is preferably approximately 10 nm or less, and the retardation Rth is preferably −120 nm to −20 nm, more preferably −90 nm to −40 nm.

[0075] <Support> The laminated optical body may further have a support. The support can be installed in any location. For example, when the retardation layer is a film to be transferred from a temporary support, the support can be used as the transfer destination. The type of support is not particularly limited, but it is preferably transparent. For example, films such as cellulose acylate, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate, cyclic polyolefin, polyolefin, polyamide, polystyrene, and polyester can be used. Among these, cellulose acylate film, cyclic polyolefin film, polyacrylate film, and polymethacrylate film are preferred. Commercially available cellulose acetate films (for example, "TD80U" and "Z-TAC" manufactured by Fujifilm Corporation) can also be used. In addition, it is preferable that the support has a small retardation from the viewpoint of suppressing adverse effects on the polarization degree of transmitted light and from the viewpoint of facilitating optical inspection of the laminated optical body. Specifically, the support preferably has an in-plane retardation Re of 10 nm or less, and an absolute value of retardation Rth of 50 nm or less.

[0076] When the laminated optical body is to be stretched or molded, the support preferably has a tan δ peak temperature of 170° C. or less. From the viewpoint of enabling molding at low temperatures, the tan δ peak temperature is preferably 150° C. or less, and more preferably 130° C. or less.

[0077] Here, the method for measuring tan δ will be described. Using a dynamic viscoelasticity measuring device, E" (loss modulus) and E' (storage modulus) are measured for a film sample that has been previously conditioned for at least 2 hours in an atmosphere at a temperature of 25°C and a humidity of 60% Rh under the following conditions, and tan δ (= E" / E') is determined as the value. An example of a dynamic viscoelasticity measuring device is the DVA-200 manufactured by IT Measurement Control Co., Ltd. Device: DVA-200 manufactured by IT Measurement Control Co., Ltd. Sample: 5 mm, length 50 mm (gap 20 mm) Measurement conditions: tension mode Measurement temperature: -150°C to 220°C Heating conditions: 5°C / min Frequency: 1 Hz In general, in optical applications, resin substrates that have been subjected to a stretching treatment are often used, and the peak temperature of tan δ often becomes high due to the stretching treatment. For example, the peak temperature of tan δ for a TAC (triacetyl cellulose) substrate is 180°C or higher. An example of the TAC substrate is TG40 manufactured by Fujifilm Corporation.

[0078] As the support having a tan δ peak temperature of 170°C or less, various resin substrates can be used without any particular limitation. Examples of such supports include polyolefins such as polyethylene, polypropylene, and norbornene-based polymers; cyclic olefin-based resins; polyvinyl alcohol; polyethylene terephthalate; acrylic resins such as polymethacrylic acid esters and polyacrylic acid esters; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyether ketone; polyphenylene sulfide, and polyphenylene oxide. Among these, cyclic olefin-based resins, polyethylene terephthalate, and acrylic resins are preferred, and cyclic olefin-based resins and polymethacrylic acid esters are particularly preferred, in terms of ease of commercial availability and excellent transparency.

[0079] Commercially available resin substrates include Technolloy S001G, Technolloy S014G, Technolloy S000, Technolloy C001, and Technolloy C000 (Sumika Acrylic Sales Co., Ltd.), Lumirror U Type, Lumirror FX10, and Lumirror SF20 (Toray Industries, Inc.), HK-53A (Higashiyama Films Co., Ltd.), Teflex FT3 (Teijin DuPont Films Co., Ltd.), S-Cina" and SCA40 (Sekisui Chemical Co., Ltd.), Zeonor Film (Optes Co., Ltd.), and Arton Film (JSR Corporation).

[0080] The thickness of the support is not particularly limited, but is preferably from 5 to 300 μm, more preferably from 5 to 100 μm, and even more preferably from 5 to 30 μm.

[0081] <Molding method> The method for manufacturing the optical film having the curved surface described above is not particularly limited. In particular, the molding method for the optical film of the present invention preferably includes a step of heating an optical film having a planar shape, a step of pressing the heated optical film against a mold to deform it according to the shape of the mold, and a step of cutting the optical film. Each step will be described in detail below.

[0082] (Step of heating an optical film having a planar shape) The optical film used in this step is an optical film having a planar shape, as described below, to which a predetermined shape is transferred using a mold (forming die), thereby obtaining the optical film of the present invention having the above-mentioned curved surface. The optical film having a planar shape includes various components that can be included in the optical film having the above-mentioned curved surface, such as a retardation film. However, the various components included in the optical film having a planar shape have a planar shape.

[0083] Methods for heating an optical film having a planar shape include heating by contact with a heated solid, heating by contact with a heated liquid, heating by contact with a heated gas, heating by infrared radiation, heating by microwave radiation, etc. In particular, heating by infrared radiation is preferred, which allows heating to be performed remotely immediately before molding the optical film.

[0084] The wavelength of the infrared rays used for heating is preferably 1.0 to 30.0 μm, more preferably 1.5 to 5 μm. Examples of IR light sources that can be used include near-infrared lamp heaters with a tungsten filament sealed in a quartz tube and wavelength-controlled heaters with multiple quartz tubes and a mechanism for cooling a portion of the space between the quartz tubes with air. Furthermore, by creating a distribution of infrared radiation on the optical film, the physical properties during molding can be controlled according to the purpose. Methods for creating an intensity distribution include varying the density of IR light sources and placing a filter with a patterned infrared transmittance between the IR light source and the optical film. Examples of filters with a patterned transmittance include filters made of glass with a metal vapor deposition, filters that convert the reflection band of a cholesteric liquid crystal layer to infrared, filters that convert the reflection band of a dielectric multilayer film to infrared, and filters coated with infrared-absorbing ink. The temperature of the optical film is controlled by the intensity of infrared radiation. Specifically, the temperature of the optical film is controlled by the infrared irradiation time and / or the irradiance of the infrared radiation. By monitoring the temperature of the optical film using a non-contact radiation thermometer, a thermocouple, or the like, it is possible to mold the optical film at a desired temperature.

[0085] (Step of Pressing the Optical Film Against the Mold and Deforming it to Fit the Shape of the Mold) The heated optical film can be pressed against the mold and deformed to fit the shape of the mold by reducing the pressure and / or increasing the pressure in the molding space. Alternatively, a mold pressing method can be used.

[0086] One form of molding apparatus used in this process comprises a box 1 having an opening at the top and a box 2 having an opening at the bottom. The openings of box 1 and box 2 are aligned directly or via a jig to form a sealed molding space. A mold having a shape corresponding to the shape (curved surface) of the optical film after molding and the film to be molded are placed in the molding space. In this case, the mold may be an adherend, such as a lens, to which the optical film of the present invention is attached (adhered). The film to be molded acts as a partition, dividing the molding space consisting of box 1 and box 2 into two spaces. The mold is placed on the box 1 side, below the film to be molded. Furthermore, the molding apparatus is equipped with a plurality of heating elements for heating the film to be molded. The heating elements may be placed inside the molding space, or they may be placed outside the molding space and heat the film to be molded through a transparent window.

[0087] (Step of Cutting Optical Film) Examples of a method for cutting the molded optical film into a desired shape include methods using a cutter, scissors, a cutting plotter, a laser cutter, and the like.

[0088] <Concept of molding method for forming a predetermined film thickness distribution> The optical film of the present invention has a curved surface, and the film thickness of the optical film on the curved surface has a film thickness distribution that satisfies the above-mentioned formula (1). As described above, such an optical film of the present invention has small variation in optical properties on the curved surface. Preferably, the optical film of the present invention has an in-plane variation in optical properties of less than 5%. An example of a molding method for forming an optical film having such a film thickness distribution on a curved surface will be described in detail.

[0089] This molding method allows molding to be performed so that the planar optical film is isotropically stretched in-plane. Specifically, when a circular film is curved, the planar optical film is molded so that the ratio of the stretching ratio in the diameter direction to the stretching ratio in the circumferential direction is in the range of 0.95 to 1.05. This allows for a large film thickness distribution in the molded optical film. Furthermore, by having such a large film thickness distribution, when the optical film has a retardation (effective retardation) and a slow axis (effective slow axis), the variation in the orientation of the slow axis after molding can be reduced. Furthermore, when the optical film includes a first optically anisotropic layer and a second optically anisotropic layer, the variation in the effective in-plane retardation after molding can be reduced. The ratio of the stretching ratio in the diameter direction to the stretching ratio in the circumferential direction is more preferably in the range of 0.98 to 1.02.

[0090] A specific example of the molding method is the above-mentioned optical film molding method, which includes the steps of heating an optical film having a planar shape, pressing the heated optical film against a mold (adherend) to deform it according to the shape of the mold, and cutting the deformed optical film, wherein the heating step is a step of irradiating the optical film with infrared rays, and the amount of infrared radiation has an in-plane distribution of the optical film. In particular, in this molding method, it is preferable that the mold is substantially concave spherical, and when an in-plane position of the optical film is projected onto the mold from the normal direction of the surface of the optical film, the amount of infrared radiation irradiated onto the optical film located at the apex (bottom (optical axis)) of the concave sphere is greater than the amount of infrared radiation irradiated onto the optical film located at the end of the concave sphere. That is, in this molding method, it is preferable that the mold is substantially concave spherical, and when an in-plane position of the optical film is projected onto the mold from the normal direction of the surface of the optical film, the temperature of the optical film located at the apex of the concave sphere is higher than the temperature of the optical film located at the end of the concave sphere. This allows the film to have a molding characteristic in which the stretching ratio in the diameter direction decreases with increasing distance from the center (the apex of the concave sphere), thereby increasing the distribution of film thickness on the curved surface.

[0091] A preferred embodiment of this molding method will be described in more detail below. When a molding die having a concave molding surface is used, the ratio of the stretching ratio in the diameter direction to the stretching ratio in the circumferential direction at the peripheral portion is likely to be distorted. That is, when an optical film is pressed against the concave surface of a mold having a concavely curved surface to mold the optical film into a curved surface, the optical film is usually fixed to the peripheral portion (edge) of the curved surface of the mold and molded by applying pressure or vacuum to press the optical film against the curved surface of the mold. Therefore, in this molding method, for example, if the shape (planar shape) of the optical film in the direction perpendicular to the normal (optical axis) of the bottom is a circular curved surface, since the peripheral portion is fixed, the peripheral portion of the optical film is stretched in the diameter direction but is hardly stretched in the circumferential direction. In contrast, the optical film has a higher degree of freedom of stretching as it approaches the bottom of the concave surface, so it is stretched in both the diameter direction and the circumferential direction. That is, in this molding method, the optical film is stretched uniaxially at the peripheral edge portion, but is isotropically stretched at positions away from the peripheral edge portion.

[0092] Therefore, in the above-described molding method, for example, as conceptually shown in Figures 3 and 4, for a circular, planar optical film 242 placed on a molding die 240 (mold 240) having a concave molding surface, the heating temperature of central portion 242C by infrared irradiation is set higher than the heating temperature of peripheral portion 242R by infrared irradiation. This makes central portion 242C more likely to stretch when optical film 242 is deformed along the molding surface (concave surface) of molding die 240. By changing the heating conditions for the central portion and the peripheral portion, it is possible to make the central portion more likely to stretch and the peripheral portion less likely to stretch.

[0093] This allows for the production of an optical film that satisfies the above-described formula (1), (t_max-t_min) / t_min > R-1, such as optical film 10 shown in Figure 1, in which the peripheral portion is thickest and the film thickness gradually decreases toward the bottom portion, with the bottom portion being the thinnest. An optical film that satisfies formula (1) is an optical film in which isotropically stretched over the entire curved surface of the optical film, with minimal in-plane variation in optical properties, achieved by lowering the stretch ratio of the peripheral portion that is uniaxially stretched and increasing the stretch ratio of the bottom (central) region that is isotropically stretched. Therefore, for example, when this optical film is used in a pancake lens-type virtual reality display device, it is possible to reduce light leakage and display virtual reality images with minimal ghosting.

[0094] The method for producing the optical film of the present invention is not limited to the method using a molding die 240 having a concave surface as shown in Fig. 3. That is, the optical film of the present invention can also be produced using a molding die 250 (mold 250) having a curved convex surface as conceptually shown in Fig. 6. In this case, unlike the case where a molding die 240 having a concave surface is used, the optical film 252 is usually fixed to the top of the convex surface of the molding die 250 and pressure is applied, thereby pressing the optical film against the curved convex surface of the mold to perform molding.

[0095] In this manufacturing method, for example, when optical film 252 has a circular planar shape as in the previous case, central portion 252C (the apex of the convex surface) that contacts the center of molding die 250 is stretched isotropically, and peripheral portion 252R is stretched uniaxially along the diameter direction of molding die 250. In this manufacturing method, for example, by gripping the peripheral portion of optical film 252 and stretching optical film 252 so as to increase its area at the same time as molding, the peripheral portion of optical film 252 is also stretched in the circumferential direction, making it possible to approach isotropic stretching.

[0096] This allows for the production of an optical film that is thickest in the center, gradually thinner toward the periphery, and thinnest in the peripheral region, satisfying the above-described formula (1) (t_max-t_min) / t_min > R-1, as in optical film 12 shown in Figure 2. As before, an optical film that satisfies formula (1) is an optical film in which isotropically stretched over the entire curved surface of the optical film by lowering the stretch ratio of the apex (apex) that is uniaxially stretched and increasing the stretch ratio of the peripheral region that is isotropically stretched, resulting in minimal in-plane variation in optical properties. Therefore, for example, when this optical film is used in a pancake lens-type virtual reality display device, it is possible to reduce light leakage and display virtual reality images with minimal ghosting.

[0097] <Method of Installing the Mold> The method of installing the mold (forming die) in the molding apparatus is not particularly limited. For example, a movable stage with a horizontal top plate can be installed in the box 1 below the above-mentioned molding apparatus, and the mold can be installed on the stage. In this case, after evacuating the inside of the molding apparatus, the movable stage can be raised to press the mold against the film to be molded. Furthermore, one or more molds may be installed on the stage. From the viewpoint of improving productivity, it is also possible to use a film to be molded having an area larger than the area of ​​the mold, install multiple molds, and simultaneously produce multiple molded bodies.

[0098] <Jig for Gripping the Mold> It is also preferable to grip the mold using a jig having a recess into which the mold can be fitted to prevent the mold from moving on the stage. This allows the mold to be fixed so that it does not move on the stage. It is also preferable that the jig for gripping the mold covers the surfaces of the mold other than the molding surface (the surface to which the molded film is attached). If the molded film attempts to cover not only the molding surface but also the edge surface of the mold, the molded film will be significantly stretched, which may result in significant non-uniformity in the film thickness and optical properties, etc. Therefore, it is preferable to use a jig that covers the surfaces of the mold other than the molding surface to prevent the molded film from contacting the surfaces other than the molding surface. It is also preferable that the jig has a surface that is approximately the same height as the molding surface of the mold and is horizontal in the area where the mold is not present. This makes it possible to prevent the molded film from being stretched in areas other than the molding surface of the mold, thereby improving the uniformity of the film thickness and optical properties, etc. Furthermore, when forming the film to be formed into the mold, it is preferable to raise the movable stage on which the jig and mold are placed so that the position of the forming surface of the mold is approximately equal to the position of the film to be formed. This prevents the film to be formed from contacting the edge of the jig and being significantly stretched. The jig may be integrated with the stage.

[0099] <Method of laminating optical film to adherend> The method of laminating an optical film to an adherend such as a lens is not particularly limited. For example, the optical film may be formed into a curved shape by any of the methods described above, and then adhered to an adherend such as a lens using an adhesive or the like. From the viewpoint of simplifying the process, it is preferable to previously laminate a pressure-sensitive adhesive sheet on the surface of the optical film that comes into contact with the mold, and then laminate the optical film to the curved surface of the mold while shaping the optical film into a curved shape using the mold. That is, in this case, the adherend such as a lens serves as the mold (molding die).

[0100] <Lens> The lens of the present invention is a composite lens including the optical film of the present invention. The lens may have a lens substrate made of glass or a transparent resin. The lens substrate preferably does not change the polarization state of light and preferably has a phase difference (Re and Rth) of zero. The lens may also include a half mirror, an anti-reflection layer, an ultraviolet absorbing layer, a hard coat layer, and the like, in addition to the optical film of the present invention. The shape of the lens is not particularly limited, but it is preferable that at least one surface be curved. A curved lens can correct aberrations in a displayed image in a virtual reality display device, resulting in a higher-quality display. The curved surface may be a part of a spherical surface or may be aspherical. Examples of lens substrates that can be used include convex lenses, concave lenses, and meniscus lenses. Examples of convex lenses include biconvex lenses, plano-convex lenses, and convex meniscus lenses. Examples of concave lenses include biconcave lenses, plano-concave lenses, and concave meniscus lenses.

[0101] <Virtual reality display device> The virtual reality display device of the present invention preferably includes an image display device and a lens including the optical film of the present invention. This allows the virtual reality display device to suppress light leakage. The image display device may include a display panel such as a liquid crystal display panel, an organic EL display panel, or a micro LED display panel. The image display device may also include an absorptive polarizer, a retardation layer, an antireflection layer, an ultraviolet absorbing layer, and a hard coat layer. The virtual reality display device may also include additional optical components such as an aberration correction lens and a diopter adjustment lens. The virtual reality display device may also be equipped with various sensors that use near-infrared light as a light source, such as for eye tracking, facial expression recognition, and iris authentication.

[0102] <Image Display Device> The virtual reality display device of the present invention has an image display device. The image display device can have an image display panel such as a liquid crystal display panel, an organic EL display panel, or a micro LED display panel. The image display device has an absorptive polarizer on the surface of the image display panel, and preferably includes a retardation layer on the outer side, i.e., the surface from which light is emitted. This allows the image display device to emit ideal circularly polarized light. Furthermore, the image display device may include an anti-reflection layer, an ultraviolet absorbing layer, a hard coat layer, etc. in addition to the retardation layer.

[0103] The virtual reality display device of the present invention can be used as a headset in the form of glasses, goggles, etc. The virtual reality display device of the present invention can also be suitably used as an electronic viewfinder for a digital camera, an imager for an in-vehicle display, etc.

[0104] FIG. 7 conceptually illustrates an example of a virtual reality display device of the present invention. This example is a virtual reality display device that uses a reflective linear polarizer. The virtual reality display device 20 shown in FIG. 7 includes an image display device and a pancake lens. The image display device includes an image display panel 24, a λ / 4 wavelength plate 26, an absorptive linear polarizer 28, and a λ / 4 wavelength plate 30, in this order. On the other hand, the pancake lens includes a half mirror 32, a lens substrate 34, a λ / 4 wavelength plate 36, a reflective linear polarizer 38, and an absorptive linear polarizer 40, in this order. Here, the pancake lens is a lens of the present invention. Therefore, in the pancake lens, at least one of the λ / 4 wavelength plate 36, the reflective linear polarizer 38, and the absorptive linear polarizer 40 is an optical film of the present invention, preferably two of them, and more preferably all of them are optical films of the present invention. Furthermore, when two or more adjacent functional layers include optical films, the optical film of the present invention may be the laminated optical body described above.

[0105] In the virtual reality display device 20 shown in FIG. 7 , an image (virtual reality image) output by the image display panel 24 is converted into linearly polarized light by the λ / 4 wave plate 26, passes through the absorptive linear polarizer 28 to become linearly polarized in a predetermined direction, is converted into circularly polarized light by the λ / 4 wave plate 30, and is output from the image display device. In this example, as an example, the image display device outputs right-handed circularly polarized light R. Half of the right-handed circularly polarized light R output from the image display device passes through the half mirror 32 and the lens substrate 34, and is converted by the λ / 4 wave plate 36 into linearly polarized light in the direction reflected by the reflective linear polarizer 38. This linearly polarized light is then reflected by the reflective linear polarizer 38, converted back into right-handed circularly polarized light R by the λ / 4 wave plate 36, passes through the lens substrate 34, and enters the half mirror 32, where half of it is reflected. During this reflection, the right-handed circularly polarized light R is converted into left-handed circularly polarized light L. The left-handed circularly polarized light L reflected by the half mirror 32 passes through the lens substrate 34 and is converted into linearly polarized light by the λ / 4 wave plate 36. Here, as described above, the λ / 4 wave plate 36 converts the right-handed circularly polarized light R into linearly polarized light in the direction reflected by the reflective linear polarizer 38. In other words, the λ / 4 wave plate 36 converts the left-handed circularly polarized light L into linearly polarized light in the direction transmitted through the λ / 4 wave plate 36. Therefore, this linearly polarized light, i.e., the virtual image, passes through the reflective linear polarizer 38 and the absorbing linear polarizer 40 and is observed by the user E.

[0106] In this virtual reality display device 20, when linearly polarized light first enters the reflective linear polarizer 38, the light unnecessarily transmitted through the reflective linear polarizer 38, indicated by the dashed line, becomes leaked light and is observed by the user E as a ghost. In contrast, in the virtual reality display device 20, the pancake lens is a lens of the present invention that uses the optical film of the present invention. That is, in this pancake lens, one or more, preferably all, of the λ / 4 wave plate 36, the reflective linear polarizer 38, and the absorbing linear polarizer 40 are the optical films of the present invention described above. As described above, the optical film of the present invention has little in-plane variation in optical properties and properly exhibits the desired optical properties. That is, the λ / 4 wave plate 36 converts the incident circularly polarized light into the desired linearly polarized light, the reflective linear polarizer 38 properly reflects and transmits the desired linearly polarized light, and the absorbing linear polarizer 40 properly absorbs and transmits the desired linearly polarized light. Therefore, the virtual reality display device 20 of the present invention can reduce the leakage light that unnecessarily passes through the reflective linear polarizer 38, thereby reducing the ghosts observed by the user E.

[0107] FIG. 8 conceptually illustrates an example of a virtual reality display device of the present invention. This example is a virtual reality display device that uses a reflective circular polarizer. The virtual reality display device 50 shown in FIG. 8 uses many of the same components as the virtual reality display device 20 shown in FIG. 7 , so the same components are denoted by the same reference numerals, and the following description will focus mainly on the differences. The virtual reality display device 50 shown in FIG. 8 includes an image display device and a pancake lens. The image display device is the same as the virtual reality display device 20 described above. Meanwhile, the pancake lens includes a half mirror 32, a lens substrate 34, a reflective circular polarizer 52, a λ / 4 wavelength plate 36, and an absorptive linear polarizer 40, in that order. Here, the pancake lens is a lens of the present invention. Therefore, in the pancake lens, at least one of the reflective circular polarizer 52, the λ / 4 wavelength plate 36, and the absorptive linear polarizer 40 is an optical film of the present invention, preferably two of them, and more preferably all of them. In addition, when two or more adjacent functional layers have an optical film, the optical film of the present invention may be the above-mentioned laminated optical body.

[0108] As in the previous example, in the virtual reality display device 50 shown in FIG. 8 , the image display device, as an example, emits right-handed circularly polarized light R. Half of the right-handed circularly polarized light R emitted by the image display device is transmitted through the half mirror 32, transmitted through the lens substrate 34, and incident on the reflective circular polarizer 52. In this example, the reflective circular polarizer 52 reflects the right-handed circularly polarized light R. Therefore, the right-handed circularly polarized light R is reflected by the reflective circular polarizer 52, transmitted through the lens substrate 34, and incident on the half mirror 32, where half of it is reflected by the half mirror 32. During this reflection, the right-handed circularly polarized light R is converted into left-handed circularly polarized light L. The left-handed circularly polarized light L reflected by the half mirror 32 is transmitted through the lens substrate 34 and again incident on the reflective circular polarizer 52. As described above, the reflective circular polarizer 52 reflects the right-handed circularly polarized light R, and therefore the left-handed circularly polarized light L is transmitted through the reflective circular polarizer 52. The left-handed circularly polarized light that passes through the reflective circular polarizer 52 is converted by the λ / 4 wave plate 36 into linearly polarized light in a direction that passes through the absorbing linear polarizer 40, and then passes through the absorbing linear polarizer 40 to be observed by the user E.

[0109] In this virtual reality display device 50, when right-handed circularly polarized light R is first incident on the reflective circular polarizer 52, the light unnecessarily transmitted through the reflective linear polarizer 38, indicated by the dashed line, becomes leaked light and is observed by user E as a ghost. In contrast, in the virtual reality display device 50, the pancake lens is a lens of the present invention that uses the optical film of the present invention. That is, in this pancake lens, one or more, preferably all, of the reflective circular polarizer 52, the λ / 4 wave plate 36, and the absorptive linear polarizer 40 are optical films of the present invention. Therefore, by achieving the same effect as the virtual reality image display device shown in FIG. 7 described above, the virtual reality display device 50 shown in FIG. 8 can also reduce leaked light unnecessarily transmitted through the reflective circular polarizer 52, thereby reducing the ghost observed by user E.

[0110] The features of the present invention will be explained in more detail below with reference to examples. Note that the materials, amounts used, ratios, processing details, processing procedures, etc. shown below can be changed as appropriate without departing from the spirit of the present invention. Furthermore, configurations other than those shown below can also be used without departing from the spirit of the present invention.

[0111] [Preparation of Cellulose Acylate Film A1] (Preparation of Core Layer Cellulose Acylate Dope) The following composition was charged into a mixing tank and stirred to dissolve each component, thereby preparing a cellulose acetate solution to be used as the core layer cellulose acylate dope. ------------------------------------------------ Core Layer Cellulose Acylate Dope------------------------------------------------ - Cellulose acetate having an acetyl substitution degree of 2.88: 100 parts by mass - Polyester compound B described in the examples of JP-A No. 2015-227955: 12 parts by mass - Compound F below: 2 parts by mass - Methylene chloride (first solvent): 430 parts by mass - Methanol (second solvent): 64 parts by mass

[0112] Compound F

[0113] (Preparation of Outer Layer Cellulose Acylate Dope) 10 parts by weight of the following matting agent solution was added to 90 parts by weight of the above core layer cellulose acylate dope to prepare a cellulose acetate solution to be used as the outer layer cellulose acylate dope.

[0114] Matting agent solution - Silica particles with an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 2 parts by mass - Methylene chloride (first solvent) 76 parts by mass - Methanol (second solvent) 11 parts by mass - The above-mentioned cellulose acylate dope for the core layer 1 part by mass -

[0115] (Preparation of Cellulose Acylate Film A1) The core layer cellulose acylate dope and the outer layer cellulose acylate dope were filtered through a filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm. Then, the core layer cellulose acylate dope and the outer layer cellulose acylate dope on both sides were simultaneously cast onto a drum at 20°C from a casting nozzle (band caster). The film was then peeled off while the solvent content was approximately 20% by mass, and both ends of the film in the width direction were fixed with tenter clips and stretched transversely at a stretch ratio of 1.1 times while being dried. The film was then transported between the rolls of a heat treatment device and further dried to produce an optical film with a thickness of 40 μm, which was designated as Cellulose Acylate Film A1. The in-plane retardation of the resulting cellulose acylate film 1 was 0 nm.

[0116] [Preparation of Retardation Film 1 Having a Positive A Plate] A coating solution E1 for forming a photo-alignment film having the following composition was continuously applied onto the above-mentioned cellulose acylate film A1 using a wire bar. The support on which the coating film was formed was dried with hot air at 140°C for 120 seconds. Subsequently, the coating film was irradiated with polarized ultraviolet light (10 mJ / cm 2 , using an ultra-high pressure mercury lamp) to form a photo-alignment film E1 with a thickness of 0.2 μm, thereby obtaining a TAC film with a photo-alignment film.

[0117] -------------------------------------------------- Coating liquid E1 for forming photoalignment film -------------------------------------------------- Polymer PA-2 (shown below) 100.00 parts by mass Acid generator PAG-1 (shown below) 5.00 parts by mass Acid generator CPI-110TF (shown below) 0.005 parts by mass Isopropyl alcohol 16.50 parts by mass Butyl acetate 1072.00 parts by mass Methyl ethyl ketone 268.00 parts by mass --------------------------------------------------

[0118] Acid generator CPI-110TF

[0119] Polymer PA-2

[0120] Acid generator PAG-1

[0121] Composition F1 having the following composition was applied onto the photo-alignment film E1 using a bar coater. The coating film formed on the photo-alignment film E1 was heated to 120°C with hot air. After cooling to 60°C, a high-pressure mercury lamp was used in a nitrogen atmosphere to apply 100 mJ / cm at a wavelength of 365 nm. 2 The coating film was then irradiated with ultraviolet light of 500 mJ / cm while being heated to 120°C. 2 The coating film was irradiated with ultraviolet light of 1000 nm, thereby fixing the alignment of the liquid crystal compound, and a retardation film 1 having a positive A plate F1 was produced. The thickness of the positive A plate F1 was 2.5 μm, and the Re(550) was 141 nm. The positive A plate also satisfied the relationship Re(450)≦Re(550)≦Re(650), and had reverse wavelength dispersion. The Re(450) / Re(550) was 0.82.

[0122] ------------------------------------------------ Composition F1------------------------------------------------ 43.50 parts by mass of polymerizable liquid crystal compound LA-1 described below 43.50 parts by mass of polymerizable liquid crystal compound LA-2 described below 8.00 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 0.55 parts by mass of polymerization initiator PI-1 described below 0.20 parts by mass of leveling agent T-1 described below 235.00 parts by mass of cyclopentanone ------------------------------------------------

[0123] Polymerizable liquid crystal compound LA-1 (tBu represents a tertiary butyl group)

[0124] Polymerizable liquid crystal compound LA-2

[0125] Polymerizable liquid crystal compound LA-3

[0126] Polymerizable liquid crystal compound LA-4 (Me represents a methyl group)

[0127] Polymerization initiator PI-1

[0128] Leveling agent T-1

[0129] [Preparation of Retardation Film 2]

[0130] An optically anisotropic layer coating solution (A) having the following composition was applied to the photo-alignment film E1 using a bar coater and heated at 80°C for 60 seconds. The film on which the coating was formed was then irradiated with light from a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at an exposure dose of 500 mJ at 80°C under a nitrogen atmosphere to fix the alignment state of the liquid crystalline compound, thereby producing a second optically anisotropic layer A2. The product Δnd of Δn and d at a wavelength of 550 nm of the second optically anisotropic layer A2 was 194 nm, and the twist angle was 85°. The molecular axis of the liquid crystalline compound was parallel to the surface of the cellulose acylate film (or the surface of the optically anisotropic layer).

[0131] Composition of coating solution (A) for optically anisotropic layer ------------------------------------------------ 40 parts by mass of rod-shaped liquid crystal compound (A) shown below 40 parts by mass of rod-shaped liquid crystal compound (B) shown below 20 parts by mass of rod-shaped liquid crystal compound (C) shown below 4 parts by mass of ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 3 parts by mass of photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan KK) 0.46 parts by mass of chiral agent (A) shown below 0.5 parts by mass of polymerizable polymer (X) shown below 0.1 part by mass of polymer (A) shown below 325 parts by mass of methyl isobutyl ketone ------------------------------------------------

[0132] Rod-shaped liquid crystal compound (A)

[0133] Rod-shaped liquid crystal compound (B)

[0134] Rod-like liquid crystal compound (C) (hereinafter referred to as a mixture of liquid crystal compounds)

[0135] Chiral Agent (A)

[0136] Polymerizable polymer (X)

[0137] Polymer (A)

[0138] Next, a coating solution obtained by removing the chiral agent (A) from the optically anisotropic layer coating solution (A) was applied onto the second optically anisotropic layer A2 using a bar coater and heated at 80°C for 60 seconds. Thereafter, under a nitrogen atmosphere, the film on which the coating film was formed was irradiated with light from a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at an exposure dose of 500 mJ at 80°C to fix the alignment state of the liquid crystalline compound, thereby producing a first optically anisotropic layer A1. The first optically anisotropic layer A1 was a positive A plate having a product Δnd of 205 nm of Δn and d at a wavelength of 550 nm, and its slow axis orientation was the same as that of the uppermost layer of the second optically anisotropic layer A2. In this way, a retardation film 2 was produced. The effective in-plane retardation of the retardation film 2 was in the range of λ / 4±5% at least in the wavelength λ range of 450 nm to 650 nm.

[0139] [Preparation of Retardation Film 3] Retardation film 3 was prepared in the same manner as retardation film 2, except that the film thickness of the optically anisotropic layer and the amount of chiral agent (A) contained in the optically anisotropic layer were adjusted. The product Δnd of Δn and d of the second optically anisotropic layer in retardation film 3 at a wavelength of 550 nm was 157 nm, and the twist angle was 81°. The product Δnd of Δn and d of the first optically anisotropic layer at a wavelength of 550 nm was 310 nm, and the twist angle was 24°. The effective in-plane retardation of retardation film 3 was a value in the range of λ / 4±5%, at least in the wavelength λ range of 450 nm to 650 nm.

[0140] [Preparation of Positive C Plate] The above-described cellulose acylate film A1 was used as a temporary support. The cellulose acylate film A1 was passed through a dielectric heating roll at a temperature of 60°C to raise the surface temperature of the film to 40°C. Thereafter, an alkaline solution having the composition shown below was applied to one side of the film using a bar coater in an amount of 14 ml / m. 2 The film was heated to 110°C and transported for 10 seconds under a steam-type far-infrared heater manufactured by Noritake Co., Ltd. Next, pure water was applied to the film at a rate of 3 ml / m using the same bar coater. 2Next, after repeating washing with water using a fountain coater and draining with an air knife three times, the film was transported to a drying zone at 70° C. for 10 seconds and dried to prepare an alkali-saponified cellulose acylate film A1.

[0141] ---------------------------------------------------------------- (Alkaline solution) ---------------------------------------------------------------- Potassium hydroxide 4.7 parts by mass Water 15.8 parts by mass Isopropanol 63.7 parts by mass Fluorine-containing surfactant SF-1 (C 14 H 29 O(CHCHO) 20 H) 1.0 part by mass Propylene glycol 14.8 parts by mass

[0142] An alignment film-forming coating solution G1 having the following composition was continuously applied onto the above-mentioned alkali-saponified cellulose acylate film A1 using a #8 wire bar, and the resulting film was dried with hot air at 60°C for 60 seconds and then with hot air at 100°C for 120 seconds to form an alignment film G1.

[0143] ------------------------------------------------------------------ Coating liquid G1 for forming alignment film -------------------------------------------------- Polyvinyl alcohol (PVA103, manufactured by Kuraray) 2.4 parts by mass Isopropyl alcohol 1.6 parts by mass Methanol 36 parts by mass Water 60 parts by mass ------------------------------------------------------------------

[0144] A coating solution H1 for forming a positive C plate having the following composition was applied onto the alignment film G1, and the resulting coating film was aged at 60° C. for 60 seconds, and then irradiated with 70 mW / cm 2 2An air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) was used, and the light output was 1000 mJ / cm 2 The alignment state was fixed by irradiating the liquid crystal compound with ultraviolet light of 1000 nm to vertically align the liquid crystal compound, thereby producing a positive C plate having a thickness of 0.8 μm. The Rth(550) of the obtained positive C plate was −80 nm.

[0145] -------------------------------- Coating liquid H1 for forming positive C-plate -------------------------------- 80 parts by mass of liquid crystal compound LC-1 shown below 20 parts by mass of liquid crystal compound LC-2 shown below 1 part by mass of vertical alignment agent S01 shown below 8 parts by mass of ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 3 parts by mass of Irgacure 907 (manufactured by BASF) 1 part by mass of Kayacure DETX (manufactured by Nippon Kayaku Co., Ltd.) 0.4 parts by mass of compound B03 shown below 170 parts by mass of methyl ethyl ketone 30 parts by mass of cyclohexanone --------------------------------

[0146] Liquid crystal compound LC-1

[0147] Liquid crystal compound LC-2

[0148] Vertical alignment agent S01

[0149] Compound B03

[0150] [Preparation of Absorptive Linear Polarizer] <Formation of Photo-Alignment Layer PA1> The above-described cellulose acylate film A1 was used as a temporary support. The below-described alignment layer-forming coating liquid S-PA-1 was continuously applied onto the above-described cellulose acylate film A1 using a wire bar. The support on which the coating film was formed was dried with hot air at 140°C for 120 seconds, and then the coating film was irradiated with polarized ultraviolet light (10 mJ / cm 2 A photo-alignment layer PA1 was formed by irradiating the substrate with light (using an ultra-high pressure mercury lamp). The film thickness was 0.3 μm.

[0151] -------------------------------------------------- (Coating liquid for forming alignment layer S-PA-1) -------------------------------------------------- Polymer M-PA-1 shown below: 100.00 parts by mass Acid generator PAG-1 shown below: 5.00 parts by mass Acid generator CPI-110TF shown below: 0.005 parts by mass Xylene: 1220.00 parts by mass Methyl isobutyl ketone: 122.00 parts by mass

[0152] Polymer M-PA-1

[0153] Acid generator PAG-1

[0154] Acid generator CPI-110F

[0155] <Formation of Optically Absorbent Anisotropic Layer> The following coating solution SP-1 for forming an optically absorbent anisotropic layer was continuously applied onto the obtained alignment layer PA1 using a wire bar. The coating layer P1 was then heated at 140°C for 30 seconds and cooled to room temperature (23°C). It was then heated at 90°C for 60 seconds and cooled again to room temperature. Thereafter, an LED lamp (center wavelength 365 nm) was used to apply the coating solution SP-1 continuously onto the obtained alignment layer PA1 using a wire bar. The coating layer P1 was then heated at 140°C for 30 seconds and cooled to room temperature again. The coating layer P1 was then heated at 90°C for 60 seconds and cooled again to room temperature. Thereafter, the coating layer P1 was heated at an illuminance of 200 mW / cm 2 An optically absorptive anisotropic layer was formed on the alignment layer PA1 by irradiating the layer for 2 seconds under the irradiation conditions of 1.6 μm. The film thickness was 1.6 μm. In this way, an absorptive linear polarizer P1 was produced.

[0156] 0.25 parts by mass of dichroic substance D-1 below 0.36 parts by mass of dichroic substance D-2 below 0.59 parts by mass of dichroic substance D-3 below 2.21 parts by mass of polymer liquid crystal compound M-P-1 below 1.36 parts by mass of low molecular weight liquid crystal compound M-1 below 0.200 parts by mass of polymerization initiator IRGACURE OXE-02 (manufactured by BASF) 0.026 parts by mass of surfactant F-1 below 46.00 parts by mass of cyclopentanone 46.00 parts by mass of tetrahydrofuran 46.00 parts by mass of benzyl alcohol ----------------------------------------------------------------------------------

[0157] Dichroic substance D-1

[0158] Dichroic substance D-2

[0159] Dichroic substance D-3

[0160] Polymer liquid crystal compound M-P-1

[0161] Low molecular liquid crystal compound M-1

[0162] Surfactant F-1

[0163] [Preparation of Retardation Film 4] Retardation film 4 was prepared in the same manner as for retardation film 2, except that the optically anisotropic layer coating solution (A) was changed to the following optically anisotropic layer coating solution (B).

[0164] Composition of coating solution (B) for optically anisotropic layer ------------------------------------------------ 70 parts by mass of liquid crystal compound L-1 shown below 30 parts by mass of liquid crystal compound L-2 shown below 0.6 parts by mass of polymerization initiator S-1 shown below 4 parts by mass of ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 3 parts by mass of photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan KK) 0.46 parts by mass of the chiral agent (A) shown above 0.5 parts by mass of the polymerizable polymer (X) shown above 0.1 parts by mass of the polymer (A) shown above 200 parts by mass of methyl ethyl ketone 200 parts by mass of cyclopentanone ------------------------------------------------

[0165] Liquid crystal compound L-1

[0166] Liquid crystal compound L-2

[0167] Polymerization initiator S-1

[0168] In the prepared retardation film 4, the first optically anisotropic layer was a positive A plate having a product Δnd of 203 nm at a wavelength of 550 nm, and the slow axis orientation was the same as that of the uppermost layer of the second optically anisotropic layer. The second optically anisotropic layer had a product Δnd of 196 nm at a wavelength of 550 nm, and a twist angle of 85°. The effective in-plane retardation of the retardation film 4 was in the range of λ / 4±5% at least in the wavelength λ range of 450 nm to 650 nm.

[0169] [Fabrication of Reflective Circular Polarizer 1] [Preparation of Coating Solution for Reflective Layer] <Coating Solution R-1 for Reflective Layer> The composition shown below was stirred and dissolved in a container kept at 70° C. to prepare Coating Solution R-1 for Reflective Layer, where R represents a coating solution using a rod-like liquid crystal compound.

[0170] -------------------------------------------------- Coating liquid R-1 for reflective layer -------------------------------------------------- Methyl ethyl ketone 120.9 parts by mass Cyclohexanone 21.3 parts by mass Mixture X of the following rod-shaped liquid crystal compounds 100.0 parts by mass Photopolymerization initiator B 1.00 part by mass Chiral agent A 4.18 parts by mass Surfactant F1 0.1 part by mass -------------------------------------------------- Mixture X of rod-shaped liquid crystal compounds

[0171] In the above mixture X, the numerical values ​​are in mass %. R is a group bonded via an oxygen atom. Furthermore, the average molar absorption coefficient of the above rod-shaped liquid crystal compound in the wavelength range of 300 to 400 nm was 140 / mol cm.

[0172] Chiral agent A

[0173] Surfactant F1

[0174] Photopolymerization initiator B

[0175] The chiral agent A is a chiral agent whose helical twisting power (HTP) is reduced by light.

[0176] <Reflective Layer Coating Solution R-2> This was prepared in the same manner as Reflective Layer Coating Solution R-1, except that the amount of chiral agent A added was changed as shown in Table 1 below.

[0177]

[0178] <Reflective Layer Coating Solution D-1> The composition shown below was stirred and dissolved in a container kept at 50° C. to prepare Reflective Layer Coating Solution D-1, where D represents a coating solution using a discotic liquid crystal compound.

[0179] -------------------------------------------------- Coating liquid D-1 for reflective layer -------------------------------------------------- 80 parts by mass of discotic liquid crystal compound (A) below 20 parts by mass of discotic liquid crystal compound (B) below 10 parts by mass of polymerizable monomer E1 below 0.3 parts by mass of surfactant F2 below 3 parts by mass of photopolymerization initiator (Irgacure 907, manufactured by BASF) 5.45 parts by mass of the chiral agent A above Methyl ethyl ketone 290 parts by mass Cyclohexanone 50 parts by mass --------------------------------------------------

[0180] Discotic Liquid Crystal Compound (A)

[0181] Discotic Liquid Crystal Compound (B)

[0182] Polymerizable Monomer E1

[0183] Surfactant F2

[0184] <Reflective Layer Coating Solutions D-2 and D-3> These were prepared in the same manner as Reflective Layer Coating Solution D-1, except that the amount of chiral agent A added was changed as shown in Table 2 below.

[0185]

[0186] <<Preparation of Reflective Circular Polarizer 1>> A 100 μm thick PET film (A4265, manufactured by Toyobo Co., Ltd.) was prepared as a temporary support, and the PET surface on which the easy-adhesive layer was not formed was subjected to a rubbing treatment. The reflective layer coating solution R-1 prepared above was applied using a wire bar coater, and then dried at 110°C for 72 seconds. Thereafter, the reflective circular polarizer was subjected to a rubbing treatment at 100°C under a low-oxygen atmosphere (100 ppm or less) with an illuminance of 80 mW / cm. 2 , irradiation amount 500mJ / cm 2 The coating was then cured by irradiating it with light from a metal halide lamp at a discharge rate of 150 W min / m to form a first blue light reflective layer (first cholesteric liquid crystal layer) made of a cholesteric liquid crystal layer. The light was irradiated from the cholesteric liquid crystal layer side. The coating thickness was adjusted so that the film thickness of the first blue light reflective layer after curing would be 2.6 μm. Next, the surface of the first blue light reflective layer was irradiated with light from a metal halide lamp at a discharge rate of 150 W min / m. 2 After the corona treatment, the reflective layer coating liquid D-1 was applied onto the corona treated surface using a wire bar coater.

[0187] Subsequently, the coating film was dried at 70°C for 2 minutes, and after the solvent was evaporated, it was heat-aged at 115°C for 3 minutes to obtain a uniformly oriented state. Thereafter, the coating film was kept at 45°C and irradiated with ultraviolet light (300 mJ / cm) using a metal halide lamp in a nitrogen atmosphere. 2 ) and cured to form a second blue light reflective layer (second cholesteric liquid crystal layer) on the first blue light reflective layer. Light was irradiated from the cholesteric liquid crystal layer side. At this time, the coating thickness was adjusted so that the film thickness of the second blue light reflective layer after curing was 2.0 μm.

[0188] Next, the reflective layer coating solution D-2 was applied onto the second blue light reflective layer using a wire bar coater. Subsequently, the coating film was dried at 70°C for 2 minutes, and after the solvent was evaporated, it was heat-aged at 115°C for 3 minutes to obtain a uniformly oriented state. Thereafter, this coating film was kept at 45°C and irradiated with ultraviolet light (300 mJ / cm) using a metal halide lamp under a nitrogen atmosphere. 2) and cured to form a green light reflective layer (third cholesteric liquid crystal layer) on the second blue light reflective layer. Light was irradiated from the cholesteric liquid crystal layer side. At this time, the coating thickness was adjusted so that the film thickness of the cured green light reflective layer would be 2.7 μm.

[0189] Next, the reflective layer coating solution R-2 was applied onto the green light reflective layer using a wire bar coater, and then dried at 110°C for 72 seconds. Thereafter, the coating solution was dried in a low-oxygen atmosphere (100 ppm or less) at 100°C with an illuminance of 80 mW and an irradiation dose of 500 mJ / cm. 2 The coating was cured by irradiating it with light from a metal halide lamp (1000 W / m²), thereby forming a red light reflective layer (fourth cholesteric liquid crystal layer) on the green light reflective layer. The light was irradiated from the cholesteric liquid crystal layer side. The coating thickness was adjusted so that the red light reflective layer after curing had a thickness of 3.4 μm.

[0190] Next, the red light reflecting layer surface was subjected to a discharge of 150 W·min / m 2 After corona treatment at 70°C, the reflective layer coating solution D-3 was applied to the corona-treated surface using a wire bar coater. Subsequently, the coating film was dried at 70°C for 2 minutes, and after the solvent was evaporated, it was heat-aged at 115°C for 3 minutes to obtain a uniform alignment state. Thereafter, this coating film was kept at 45°C and irradiated with ultraviolet light (300 mJ / cm) using a metal halide lamp under a nitrogen atmosphere. 2 ) and cured to form a yellow light reflective layer (fifth cholesteric liquid crystal layer) on the red light reflective layer. Light was irradiated from the cholesteric liquid crystal layer side. At this time, the coating thickness was adjusted so that the film thickness of the yellow light reflective layer after curing was 3.4 μm.

[0191] By the above procedure, a reflective circular polarizer 1 having the first to fifth cholesteric liquid crystal layers in this order was obtained.

[0192] The central reflection wavelength and film thickness of each cholesteric liquid crystal layer of the produced reflective circular polarizer 1 are shown in Table 3. Here, the central reflection wavelength shown in Table 3 corresponds to the central wavelength of the reflected light of the above-mentioned cholesteric liquid crystal layer. The central reflection wavelength (central wavelength of the reflected light) was confirmed by creating a film in which each cholesteric liquid crystal layer was coated in a single layer. The film thickness was confirmed using an SEM.

[0193]

[0194] Furthermore, the temporary support of the obtained reflective circular polarizer 1 was peeled off, and SHG measurement of the surface of the first cholesteric liquid crystal layer was performed, and the degree of orientation of the liquid crystal compound was 0.65. Furthermore, within the effective area when incorporated into a virtual image display device, the variation in the director orientation of the liquid crystal compound was 3.2°. Furthermore, SHG measurement of the surface of the reflective circular polarizer 1 on the side of the fifth cholesteric liquid crystal layer was performed, and the degree of orientation of the liquid crystal compound was 0.62. Furthermore, within the effective area when incorporated into a virtual image display device, the variation in the director orientation of the liquid crystal compound was 85°.

[0195] [Preparation of Laminated Optical Body 1] The liquid crystal display of an Apple tablet computer "iPad (registered trademark)" was removed, and a linearly polarized reflective polarizer (3M trademark APF) made of a wideband dielectric multilayer film was peeled off from the polarizing plate attached to the back of the liquid crystal display. Next, a retardation film 1 was attached to one side of the peeled APF using a Lintec adhesive sheet "NCF-D692 (5)", and the temporary support of the retardation film 1 was peeled off. At this time, the reflection axis orientation of the APF and the slow axis orientation of the retardation film 1 were adjusted to be 75 ° with respect to each other. Next, a second retardation film 1 was attached to the first retardation film 1 so that the slow axis orientation coincided, and the temporary support was peeled off. Next, a third retardation film 1 was attached to the second retardation film 1 so that the slow axis orientations were 60 ° with respect to each other, and the temporary support was peeled off. At this time, the reflection axis orientation of the APF and the slow axis orientation of the three retardation films 1 were 15° to each other. The positive C plate was then bonded to the third retardation film 1, and the temporary support was peeled off. An absorbing linear polarizer P1 was then bonded to the opposite surface of the APF, and the temporary support was peeled off. The reflection axis orientation of the APF and the absorption axis orientation of the absorbing linear polarizer P1 were adjusted to coincide. Thus, a laminated optical body 1 was obtained. Of the three laminated retardation films 1, the first retardation film 1 and the second retardation film 1 have the same slow axis orientation, so they can be collectively regarded as a first optically anisotropic layer. The third retardation film 1 can be regarded as a second optically anisotropic layer. In this case, the first optically anisotropic layer has an in-plane retardation of 282 nm, and the second optically anisotropic layer has an in-plane retardation of 141 nm. Both the first optically anisotropic layer and the second optically anisotropic layer have reverse wavelength dispersion.

[0196] [Preparation of Laminated Optical Body 2] The liquid crystal display of an Apple tablet computer "iPad (registered trademark)" was removed, and a linearly polarized reflective polarizer (3M trademark APF) made of a wideband dielectric multilayer film was peeled off from the polarizing plate attached to the back of the liquid crystal display. Next, a retardation film 1 was attached to one side of the peeled APF using a Lintec adhesive sheet "NCF-D692 (5)", and the temporary support of the retardation film 1 was peeled off. At this time, the reflection axis orientation of the APF and the slow axis orientation of the retardation film 1 were adjusted to be 45° to each other. Furthermore, an absorbing linear polarizer P1 was attached to the opposite side of the APF, and the temporary support was peeled off. At this time, the reflection axis orientation of the APF and the absorption axis orientation of the absorbing linear polarizer P1 were adjusted to coincide. In this way, a laminated optical body 2 was obtained.

[0197] [Preparation of Laminated Optical Body 3] Laminated optical body 3 was prepared in the same manner as laminated optical body 2, except that retardation film 1 was changed to retardation film 2.

[0198] [Preparation of Laminated Optical Body 4] Laminated optical body 4 was prepared in the same manner as laminated optical body 2, except that retardation film 1 was changed to retardation film 3.

[0199] [Preparation of Laminated Optical Body 5] Laminated optical body 5 was prepared in the same manner as laminated optical body 2, except that retardation film 1 was changed to retardation film 4.

[0200] [Preparation of Laminated Optical Body 6] An absorbing linear polarizer P1 was bonded to a PMMA film "Technoloy S001G" manufactured by Sumika Acrylic Sales Co., Ltd. using an adhesive sheet "NCF-D692 (5)" manufactured by Lintec Corporation, and the temporary support was peeled off. Next, a retardation film 1 was bonded to the surface of the absorbing linear polarizer P1 using an adhesive sheet "NCF-D692 (5)" manufactured by Lintec Corporation, and the temporary support was peeled off. At this time, the absorption axis orientation of the absorbing linear polarizer P1 and the slow axis orientation of the retardation film 1 were adjusted to be 45° to each other. Next, a reflective circular polarizer 1 was bonded to the surface of the retardation film 1 using an adhesive sheet "NCF-D692 (5)" manufactured by Lintec Corporation, and the temporary support was peeled off. In this way, a laminated optical body 6 was obtained.

[0201] [Preparation of Optical Film 1] <Molding Method 1> Laminated optical body 1 was set in a molding device. The molding space in the molding device consisted of box 1 and box 2, separated by laminated optical body 1. A convex meniscus lens LE1076-A (diameter 2 inches, focal length 100 mm, radius of curvature on the concave side 65 mm) manufactured by Thorlab, with aluminum vapor deposition on the convex side, was placed in box 1 below laminated optical body 1, with the concave side facing up. A transparent window was installed on the top of box 2 above laminated optical body 1, and an IR light source for heating laminated optical body 1 was installed outside this window. A circular patterned infrared reflective filter was placed between the IR light source and laminated optical body 1, obtained by cutting a cholesteric liquid crystal layer that reflects infrared light with a wavelength of 2.2 μm to 3.0 μm with a reflectance of approximately 50%, into a circular shape with a diameter of 1 inch. In this case, the patterned infrared reflective filter was positioned so that the center of the filter was at the center of the mold when viewed from directly above. Next, a vacuum pump was used to evacuate the inside of box 1 and box 2 to a pressure of 0.1 atmospheres or less. Next, as a step of heating the laminated optical body 1, infrared rays were irradiated and the laminated optical body 1 was heated until the center reached 108°C and the edges reached 99°C. Since the glass transition temperature Tg of the PMMA film used as the support was 105°C, the aim was to make the center easily stretchable and the edges less stretchable during molding. Next, as a step of pressing the laminated optical body 1 against the mold and deforming it according to the shape of the mold, gas was flowed into box 2 from a gas cylinder to pressurize it to 300 kPa, and the laminated optical body 1 was pressure-bonded to the mold. Finally, the laminated optical body 1 was removed from the lens mold. In this way, an optical film 1 was obtained.

[0202] Optical Film 1 had a curved surface with a curvature radius of 65 mm. The surface area of ​​the curved surface was measured using a Fizeau interferometer (manufactured by Fujifilm Corporation) and found to be 2111 mm 2 On the other hand, the projected area of ​​the curved surface, that is, the projected area of ​​the curved surface projected onto a plane perpendicular to the optical axis, was 2027 mm 2Therefore, the ratio R1 of the surface area of ​​the curved surface to the projected area of ​​the curved surface was 1.041. Therefore, R1-1 was 0.041. The thickness of the optical film on the curved surface was measured at a total of 33 points using the method described above with reference to FIG. 5 . As a result, the maximum thickness t_max1 was located at the end of the curved surface and was 53 μm, and the minimum thickness t_min1 was located at the optical axis (bottom) and was 49 μm. Therefore, (t_max1-t_min1) / t_min1=0.082, which satisfied (t_max-t_min) / t_min>R-1.

[0203] In the obtained optical film 1, the ratio t11 / t21 of the thickness t11 of the first optically anisotropic layer to the thickness t21 of the second optically anisotropic layer had a maximum in-plane variation of 3%. As a result, the variation in the effective in-plane retardation of the optical film 1 was 4%. Furthermore, the variation in the slow axis orientation of the first optically anisotropic layer projected onto a plane perpendicular to the curved surface was a maximum of 1.1° in-plane. Furthermore, the variation in the slow axis orientation of the second optically anisotropic layer projected onto a plane perpendicular to the curved surface was a maximum of 1.2° in-plane. As a result, the variation in the effective slow axis orientation of the optical film 1 projected onto a plane perpendicular to the curved surface was 1.3°. The positions where the in-plane variation was measured were positions corresponding to the intersections of the pattern as shown in Figure 5, and a total of 17 points were measured: the center point, circles spaced at equal intervals of 10 mm radius in the diameter direction, and intersections of lines spaced at equal intervals of 45 degrees in the azimuth angle direction. The in-plane variation was calculated from the average, maximum, and minimum values ​​of these 17 points. The same applies to the following examples.

[0204] [Preparation of Optical Film 2] Laminated optical body 1 was replaced with laminated optical body 2, and molding was carried out in the same manner as for optical film 1. In this manner, optical film 2 was obtained. Optical film 2 had a curved surface with a curvature radius of 65 mm. When measured in the same manner as for optical film 1, the surface area of ​​the curved surface of optical film 2 was found to be 2111 mm 2 The projected area of ​​the curved surface was 2027 mm 2Therefore, the ratio R2 of the surface area of ​​the curved surface to the projected area of ​​the curved surface was 1.041. Therefore, R2-1 was 0.041. When the thickness of the curved surface of Optical Film 2 was measured in the same manner as for Optical Film 1, the maximum thickness t_max2 was located at the edge of the curved surface and was 32 μm, and the minimum thickness t_min2 was located at the optical axis and was 29.6 μm. Therefore, (t_max2 - t_min2) / t_min2 = 0.081, which satisfied (t_max - t_min) / t_min > R-1.

[0205] [Preparation of Optical Film 3] Laminated optical body 1 was replaced with laminated optical body 3, and molding was carried out in the same manner as for optical film 1. In this manner, optical film 3 was obtained. Optical film 3 had a curved surface with a curvature radius of 65 mm. When measured in the same manner as optical film 1, the surface area of ​​the curved surface of optical film 3 was found to be 2111 mm 2 The projected area of ​​the curved surface was 2027 mm 2 t_max3-t_min3) / t_min3=0.083, which satisfied (t_max-t_min) / t_min>R-1. In the obtained optical film 3, the ratio t13 / t23 of the thickness t23 of the second optically anisotropic layer to the thickness t13 of the first optically anisotropic layer had a maximum in-plane variation of 2%. As a result, the variation in the effective in-plane retardation of the optical film 3 was 3%. The variation in the effective slow axis direction of the optical film 3 projected onto a plane perpendicular to the curved surface was 1.2°.

[0206] [Preparation of Optical Film 4] Laminated optical body 1 was replaced with laminated optical body 4, and molding was carried out in the same manner as for optical film 1. In this way, optical film 4 was obtained. Optical film 4 had a curved surface with a curvature radius of 65 mm. When measured in the same manner as optical film 1, the surface area of ​​the curved surface of optical film 4 was 2111 mm 2 The projected area of ​​the curved surface was 2027 mm 2 Therefore, the ratio R4 of the surface area of ​​the curved surface to the projected area of ​​the curved surface was 1.041. Therefore, R4-1 was 0.041. When the thickness of the curved surface of Optical Film 2 was measured in the same manner as for Optical Film 1, the maximum thickness t_max4 was 34 μm, located at the edge of the curved surface, and the minimum thickness t_min4 was 31.4 μm at the position of the optical axis. Therefore, (t_max4 - t_min4) / t_min4 = 0.083, which satisfied (t_max - t_min) / t_min > R-1. In the obtained Optical Film 4, the ratio t14 / t24 of the thickness t24 of the second optically anisotropic layer to the thickness t14 of the first optically anisotropic layer had a maximum in-plane variation of 2.6%. As a result, the variation in the effective in-plane retardation of Optical Film 4 was 4%. The variation in the effective slow axis direction of the optical film 4 projected onto a plane perpendicular to the curved surface was 1.6°.

[0207] [Preparation of Optical Film 5] <Molding Method 2> The laminated optical body 1 was set in a molding device. The molding space in the molding device consisted of boxes 1 and 2 separated by the laminated optical body 1. In box 1 below the laminated optical body 1, a Thorlab convex meniscus lens LE1076-A (diameter 2 inches, focal length 100 mm, radius of curvature on the concave side 65 mm) with aluminum vapor deposition on the convex side was placed with the concave side facing up. In addition, a transparent window was installed on the top of box 2 above the laminated optical body 1, and an IR light source for heating the laminated optical body 1 was installed outside this window. Next, a vacuum pump was used to evacuate box 1 and box 2 to a pressure of 0.1 atmospheres or less. Next, as a step of heating the laminated optical body 1, infrared rays were irradiated and the laminated optical body 1 was heated uniformly to 108 ° C. The glass transition temperature Tg of the PMMA film used as the support was 105°C, so the aim was to make the entire film easily stretchable during molding. Next, as a process for pressing the laminated optical body 1 against the mold and deforming it to conform to the shape of the mold, gas was flowed into box 2 from a gas cylinder to pressurize it to 300 kPa, and the laminated optical body 1 was pressure-bonded to the mold. Finally, the laminated optical body 1 was removed from the lens, which was the mold. In this way, optical film 5 was obtained.

[0208] Optical Film 5 had a curved surface with a radius of curvature of 65 mm. When measured in the same manner as Optical Film 1, the surface area of ​​the curved surface of Optical Film 5 was found to be 2111 mm 2 The projected area of ​​the curved surface was 2027 mm 2t_max5-t_min5) / t_min5=0.037, which does not satisfy (t_max-t_min) / t_min>R-1. In the obtained optical film 5, the ratio t15 / t25 of the thickness t25 of the second optically anisotropic layer to the thickness t15 of the first optically anisotropic layer had a maximum in-plane variation of 12%. As a result, the effective in-plane retardation variation of optical film 5 was 15%. Furthermore, the maximum in-plane variation of the slow axis orientation of the first optically anisotropic layer projected onto a plane perpendicular to the curved surface was 2.9°. Furthermore, the maximum in-plane variation of the slow axis orientation of the second optically anisotropic layer projected onto a plane perpendicular to the curved surface was 3.3°. As a result, the effective slow axis orientation variation of the optical film 5 projected onto a plane perpendicular to the curved surface was 3.1°.

[0209] [Preparation of Optical Film 6] The laminated optical body 1 was replaced with the laminated optical body 5, and molding was carried out in the same manner as for Optical Film 1. In this way, Optical Film 6 was obtained. Optical Film 6 had a curved surface with a curvature radius of 65 mm. When measured in the same manner as for Optical Film 1, the surface area of ​​the curved surface of Optical Film 6 was found to be 2111 mm 2 The projected area of ​​the curved surface was 2027 mm 2 Therefore, the ratio R6 of the surface area of ​​the curved surface to the projected area of ​​the curved surface was 1.041. Therefore, R6-1 was 0.041. When the thickness of the curved surface of Optical Film 6 was measured in the same manner as for Optical Film 1, the maximum thickness t_max6 was located at the edge of the curved surface and was 34 μm, and the minimum thickness t_min6 was located at the position of the optical axis and was 31.4 μm. Therefore, (t_max6 - t_min6) / t_min6 = 0.083, which satisfied (t_max - t_min) / t_min > R-1.

[0210] [Preparation of Optical Film 7] The laminated optical body 1 was replaced with the laminated optical body 6, and molding was carried out in the same manner as for the optical film 1. In this way, the optical film 7 was obtained. The optical film 7 had a curved surface with a curvature radius of 65 mm. When measured in the same manner as the optical film 1, the surface area of ​​the curved surface of the optical film 7 was found to be 2111 mm 2 The projected area of ​​the curved surface was 2027 mm 2 Therefore, the ratio R7 of the surface area of ​​the curved surface to the projected area of ​​the curved surface was 1.041. Therefore, R7-1 was 0.041. When the thickness of the curved surface of Optical Film 7 was measured in the same manner as for Optical Film 1, the maximum thickness t_max7 was located at the edge of the curved surface and was 28 μm, and the minimum thickness t_min7 was located at the position of the optical axis and was 25.9 μm. Therefore, (t_max7 - t_min7) / t_min7 = 0.081, which satisfied (t_max - t_min) / t_min > R-1.

[0211] [Preparation of Optical Film 8] The laminated optical body 1 was replaced with the laminated optical body 6, and molding was carried out in the same manner as for the optical film 5. In this way, the optical film 8 was obtained. The optical film 8 had a curved surface with a curvature radius of 65 mm. When measured in the same manner as for the optical film 1, the surface area of ​​the curved surface of the optical film 7 was 2111 mm 2 The projected area of ​​the curved surface was 2027 mm 2 Therefore, the ratio R8 of the surface area of ​​the curved surface to the projected area of ​​the curved surface was 1.041. Therefore, R8-1 was 0.041. When the thickness of the curved surface of Optical Film 8 was measured in the same manner as for Optical Film 1, the maximum thickness t_max8 was located at the edge of the curved surface and was 28 μm, and the minimum thickness t_min8 was located at the position of the optical axis and was 27.3 μm. Therefore, (t_max8 - t_min8) / t_min8 = 0.026, and (t_max - t_min) / t_min > R-1 was not satisfied.

[0212] [Preparation of Lens 1] When molding the optical film 1, an adhesive sheet "NCF-D692(15)" manufactured by Lintec Corporation was attached to the surface of the laminated optical body 1 that would come into contact with the mold, and was attached to the lens at the same time as molding. In this way, the lens 1 was obtained.

[0213] [Preparation of Lens 2] When molding the optical film 2, an adhesive sheet "NCF-D692(15)" manufactured by Lintec Corporation was attached to the surface of the laminated optical body 2 that would come into contact with the mold, and was attached to the lens at the same time as molding. In this way, the lens 2 was obtained.

[0214] [Preparation of Lens 3] When molding the optical film 3, an adhesive sheet "NCF-D692(15)" manufactured by Lintec Corporation was attached to the surface of the laminated optical body 3 that would come into contact with the mold, and was attached to the lens at the same time as molding. In this way, the lens 3 was obtained.

[0215] [Preparation of Lens 4] When molding the optical film 4, an adhesive sheet "NCF-D692(15)" manufactured by Lintec Corporation was attached to the surface of the laminated optical body 4 that would come into contact with the mold, and was attached to the lens at the same time as molding. In this way, the lens 4 was obtained.

[0216] [Preparation of Lens 5] When molding the optical film 5, an adhesive sheet "NCF-D692(15)" manufactured by Lintec Corporation was attached to the surface of the laminated optical body 1 that would come into contact with the mold, and was attached to the lens at the same time as molding. In this way, the lens 5 was obtained.

[0217] [Production of Lens 6] When molding the optical film 6, an adhesive sheet "NCF-D692(15)" manufactured by Lintec Corporation was attached to the surface of the laminated optical body 5 that would come into contact with the mold, and was attached to the lens at the same time as molding. In this way, the lens 6 was obtained.

[0218] [Preparation of Lens 7] When molding the optical film 7, an adhesive sheet "NCF-D692(15)" manufactured by Lintec Corporation was attached to the surface of the laminated optical body 6 that would come into contact with the mold, and was attached to the lens at the same time as molding. In this way, the lens 7 was obtained.

[0219] [Preparation of Lens 8] When molding the optical film 8, an adhesive sheet "NCF-D692(15)" manufactured by Lintec Corporation was attached to the surface of the laminated optical body 6 that would come into contact with the mold, and was attached to the lens at the same time as molding. In this way, the lens 8 was obtained.

[0220] [Evaluation of the prepared retardation films] The obtained optical films 1 to 6 all had an effective retardation Re of 141 nm before molding. The in-plane variation of the effective retardation of the optical films after molding and the in-plane variation of the effective slow axis direction projected onto a plane perpendicular to the optical axis of the curved surface are shown in Table 4 below.

[0221] [Fabrication of the Virtual Reality Display Device of Example 1] A virtual reality display device "Huawei VR Glass" manufactured by Huawei, which is a virtual reality display device that uses a pancake lens, was disassembled, and all of the compound lenses were removed. Lens 1 described above was incorporated into the main body instead, and the virtual reality display device of Example 1 was fabricated.

[0222] [Fabrication of Virtual Reality Display Devices of Examples 2 to 6] Virtual reality display devices of Examples 2 to 6 were fabricated in the same manner as in Example 1, except that Lens 1 was replaced with Lenses 2 to 4, Lens 6, and Lens 7 described above.

[0223] [Fabrication of the virtual reality display device of Comparative Example 1] The virtual reality display device of Comparative Example 1 was fabricated in the same manner as in Example 1, except that Lens 1 was replaced with the above-mentioned Lens 5. [Fabrication of the virtual reality display device of Comparative Example 2] The virtual reality display device of Comparative Example 2 was fabricated in the same manner as in Example 1, except that Lens 1 was replaced with the above-mentioned Lens 8.

[0224] <Evaluation of Ghosts> In the prepared virtual reality display devices, a black and white checkered pattern was displayed on the image display panel, and the ghost visibility was visually evaluated using the following four-point scale. A: Slightly visible, but not bothersome. B: Weak ghosts are visible. C: Slightly strong ghosts are visible. D: Strong ghosts are visible. Table 4 shows the molding methods and types of optical films used in each example and comparative example. Table 5 also shows the evaluation results. As shown in Table 5, the virtual reality display devices of Examples 1 to 6 had good ghosts across the entire viewing area.

[0225] Table 4. Molding methods and types of optical films used in Examples and Comparative Examples

[0226] Table 5. Evaluation results of Examples and Comparative Examples

[0227] The present invention can be suitably used in various optical devices such as virtual reality display devices.

[0228] 10, 12 Optical film 20, 50 Virtual reality display device 24 Image display panel 26, 30, 36 λ / 4 wave plate 28, 40 Absorptive linear polarizer 32 Half mirror 34 Lens substrate 36 λ / 4 wave plate 38 Reflective linear polarizer 52 Reflective circular polarizer 240, 250 Mold 242, 252 Optical film 242C, 252C Central portion of optical film 242R, 252R Peripheral portion of optical film

Claims

1. An optical film having a curved surface, The average radius of curvature of the curved surface is 30 to 1000 mm. When the maximum thickness of the optical film on the curved surface is t_max and the minimum thickness is t_min, (t_max-t_min) / t_min > R-1 An optical film that satisfies the requirements. Here, R is the ratio of the surface area of ​​the curved surface to the projected area obtained by projecting the curved surface onto a plane perpendicular to the optical axis.

2. The optical film includes at least a phase difference layer, and the phase difference layer includes at least a first optical anisotropy layer and a second optical anisotropy layer. The optical film according to claim 1, wherein, at point X on the curved surface, the thickness of the first optical anisotropy layer is t1(x) and the thickness of the second optical anisotropy layer is t2(x), and the variation of t1(x) / t2(x) on the curved surface is less than 5%.

3. The optical film according to claim 2, wherein the variation in the slow axis of the first optical anisotropy layer and the second optical anisotropy layer is less than 2°.

4. The optical film according to claim 3, wherein the in-plane phase difference of the first optical anisotropy layer at a wavelength of 550 nm is in the range of 120 to 160 nm, and the in-plane phase difference value of the second optical anisotropy layer is in the range of 200 to 320 nm.

5. The optical film according to claim 4, wherein the first optical anisotropy layer and the second optical anisotropy layer are layers on which at least a liquid crystalline compound is fixed.

6. The optical film according to claim 2, wherein the first optically anisotropic layer is a layer on which at least a liquid crystalline compound is fixed and is a positive A plate, and the second optically anisotropic layer is a layer on which a liquid crystalline compound that is twisted in orientation with the thickness direction as the helical axis is fixed.

7. The optical film according to claim 6, wherein the orientation direction of the liquid crystalline compound contained in the first optical anisotropic layer and the orientation direction of the liquid crystalline compound contained in the second optical anisotropic layer are continuous at the interface between the first optical anisotropic layer and the second optical anisotropic layer.

8. The optical film according to claim 2, wherein the first optical anisotropic layer is a layer in which a liquid crystalline compound is fixed in a torsion orientation with the thickness direction as the helical axis, the second optical anisotropic layer is a layer in which a liquid crystalline compound is fixed in a torsion orientation with the thickness direction as the helical axis, and the helical pitch of the first optical anisotropic layer is different from the helical pitch of the second optical anisotropic layer.

9. The optical film according to claim 8, wherein the orientation direction of the liquid crystalline compound contained in the first optical anisotropic layer and the orientation direction of the liquid crystalline compound contained in the second optical anisotropic layer are continuous at the interface between the first optical anisotropic layer and the second optical anisotropic layer.

10. The optical film according to claim 2, wherein either the first optical anisotropy layer or the second optical anisotropy layer has reverse wavelength dispersion properties.

11. The optical film according to claim 10, wherein both the first optical anisotropy layer and the second optical anisotropy layer have reverse wavelength dispersion properties.

12. The optical film according to claim 1, wherein the optical film includes at least an absorbing polarizer, and when the orientation of the absorption axis within the curved surface of the absorbing polarizer is projected onto a plane, the variation in the orientation of the projected absorption axis is less than 2°.

13. The optical film according to claim 1, wherein the optical film includes at least a reflective linear polarizer, and when the orientation of the reflection axis of the reflective linear polarizer within the curved surface is projected onto a plane, the variation in the orientation of the projected reflection axis is less than 2°.

14. The optical film according to claim 1, wherein the optical film includes at least a circular polarizer.

15. The optical film according to claim 14, wherein the reflective circular polarizer includes a cholesteric liquid crystal layer.

16. The optical film according to claim 1, wherein the thickness of the optical film gradually decreases from the edge of the curved surface toward the bottom of the curved surface.

17. The optical film according to claim 1, wherein the thickness of the optical film gradually increases from the edge of the curved surface toward the bottom of the curved surface.

18. A lens having the optical film described in any one of claims 1 to 17.

19. A virtual reality display device having a lens as described in claim 18.