Reflective circular polarizer, layered optical film, and virtual reality display device

Abstract

Provided are a reflective circular polarizer capable of suppressing a decrease in the contrast of a display image when used in a virtual reality display device or the like, a laminated optical film, and a virtual reality display device using the laminated optical film. This reflective circular polarizer includes a cholesteric liquid crystal layer and satisfies the relationship of formula (1).　Formula (1): I1+I2+I3+I4+I5 < 3.0 where I1 is a value obtained by doubling the transmittance of circularly polarized light in a turning direction opposite to circularly polarized light reflected by the reflective circular polarizer out of transmitted light when the reflected circularly polarized light is incident.　I2 is a value that is one-half of the reflectance of the circularly polarized light in the opposite turning direction out of reflected light reflected when the circularly polarized light reflected by the reflective circular polarizer is incident.　I3 is a value that is one-quarter of the reflectance of reflected light when the circularly polarized light in the opposite turning direction is incident on the reflective circular polarizer.　I4 represents the haze value of the reflective circular polarizer.　I5 represents the value of SCE / SCI×100 at a reflectance measured by an integrating sphere when unpolarized light is incident on the reflective circular polarizer.

Description

Reflective circular polarizer, laminated optical film, and virtual reality display device

[0001] The present invention relates to a reflective circular polarizer, a laminated optical film, and a virtual reality display device.

[0002] In recent years, virtual reality display devices have been put to practical use. For example, a head-mounted display having a display panel and a lens can be cited as an example of a virtual reality display device. When such a head-mounted display is worn on the head of an observer and an image is displayed through the lens, the observer can view a realistic image.

[0003] In such head-mounted displays, lenses using a reflective optical system are sometimes adopted to reduce the thickness. For example, Patent Document 1 discloses a method for generating a virtual image by reflecting light back and forth between a reflective polarizer and a half mirror in order to reduce the size and thickness of a display unit in a virtual reality display device or the like.

[0004] Special Publication No. 2003-504663

[0005] According to the studies of the present inventors, conventional virtual reality display devices sometimes suffer from a decrease in contrast of the displayed image, and there is room for further improvement.

[0006] The present invention has been made in consideration of the above-mentioned problems, and the problem that the present invention aims to solve is to provide a reflective circular polarizer and a laminated optical film that can suppress a decrease in the contrast of a displayed image when used in a virtual reality display device or the like, and a virtual reality display device using the same.

[0007] The present inventors have conducted extensive research into the above-mentioned problems and have found that the above-mentioned problems can be achieved by the following configuration.

[0008] [1] A reflective circular polarizer including a cholesteric liquid crystal layer that satisfies the relationship of the following formula (1): Formula (1): I1 + I2 + I3 + I4 + I5 < 3.0. Here, I1 is the value obtained by doubling the transmittance of circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer when circularly polarized light reflected by the reflective circular polarizer is incident on the reflective circular polarizer, among the transmitted light that passes through the reflective circular polarizer. I2 is the value obtained by halving the reflectance of circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer when circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer is incident on the reflective circular polarizer. I3 is the value obtained by quartering the reflectance of the reflected light reflected by the reflective circular polarizer when circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer is incident on the reflective circular polarizer. I4 represents the haze value of the reflective circular polarizer. I5 represents the value of SCE / SCI×100 in the reflectance measured with an integrating sphere when unpolarized light is incident on the reflective circular polarizer. [2] The reflective circular polarizer according to [1], comprising a cholesteric liquid crystal layer X formed using a rod-shaped liquid crystal compound and a cholesteric liquid crystal layer Y formed using a discotic liquid crystal compound. [3] The reflective circular polarizer according to [1] or [2], comprising a plurality of cholesteric liquid crystal layers having different selective reflection center wavelengths. [4] A laminated optical film comprising a reflective circular polarizer and an absorbing linear polarizer, wherein the laminated optical film satisfies the relationship of the following formula (2). Formula (2): I6 + I7 + I8 + I9 + I 10<3.5 Here, I6 is the value obtained by doubling the transmittance of the laminated optical film when circularly polarized light reflected by the laminated optical film is incident from the reflective circular polarizer side of the laminated optical film. I7 is the value obtained by halving the reflectance of circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer, among the reflected light reflected by the laminated optical film, when circularly polarized light reflected by the laminated optical film is incident from the reflective circular polarizer side of the laminated optical film. I8 is the value obtained by quarting the reflectance of the reflected light reflected by the laminated optical film when circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the laminated optical film is incident from the reflective circular polarizer side of the laminated optical film. I9 represents the haze value when light is incident on the laminated optical film from the reflective circular polarizer side of the laminated optical film. I 10 represents the value of SCE / SCI×100 in the reflectance measured with an integrating sphere when unpolarized light is incident on the laminated optical film from the reflective circular polarizer side of the laminated optical film. [5] The laminated optical film according to [4], wherein the reflective circular polarizer includes a cholesteric liquid crystal layer and has a retardation layer between the reflective circular polarizer and the absorbing linear polarizer. [6] The laminated optical film according to [4], wherein the reflective circular polarizer includes a retardation layer and a reflective linear polarizer. [7] A virtual reality display device having the reflective circular polarizer according to any one of [1] to [3] or the laminated optical film according to any one of [4] to [6]. [8] The virtual reality display device according to [7], further including a half mirror.

[0009] According to the present invention, it is possible to provide a reflective circular polarizer and a laminated optical film that can suppress a decrease in the contrast of a displayed image when used in a virtual reality display device or the like, and a virtual reality display device using the same.

[0010] FIG. 1 is a schematic diagram showing an example of a virtual reality display device having a reflective circular polarizer of the present invention. FIG. 2 is a schematic diagram for explaining the operation of a virtual reality display device having a reflective circular polarizer of the present invention. FIG. 3 is a diagram for explaining a checkered pattern. FIG. 4 is a diagram for explaining the influence of a transmission ghost. FIG. 5 is a diagram for explaining the influence of a reflection ghost. FIG. 6 is a diagram for explaining the influence of haze. FIG. 7 is a diagram for explaining I and I in formula (1). FIG. 8 is a diagram for explaining I in formula (1). FIG. 9 is a schematic diagram showing an example of a virtual reality display device having a laminated optical film of the present invention. FIG. 10 is a schematic diagram for explaining the operation of a virtual reality display device having a laminated optical film of the present invention. FIG. 11 is a diagram for explaining I and I in formula (2). FIG. 12 is a diagram for explaining I in formula (2). FIG. 13 is a conceptual diagram showing another example of a reflective circular polarizer.

[0011] The present invention will be described in detail below. The following description of the components may be based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

[0012] 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.

[0013] In this specification, "orthogonal" does not mean an angle of exactly 90°, but means 90°±10°, preferably 90°±5°. "Parallel" does not mean an angle of exactly 0°, but means 0°±10°, preferably 0°±5°. "45°" does not mean an angle of exactly 45°, but means 45°±10°, preferably 45°±5°.

[0014] 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.

[0015] 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 a wavelength λ, and unless otherwise specified, the wavelength λ is 550 nm. Furthermore, in this specification, the retardation in the thickness direction at a wavelength λ is referred to as Rth(λ), and unless otherwise specified, the wavelength λ is 550 nm. Re(λ) and Rth(λ) can be values ​​measured at a wavelength λ using 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 following slow axis direction (°) can be calculated: Re(λ) = R0(λ) Rth(λ) = ((nx + ny) / 2 - nz) × d.

[0016] [Reflective Circular Polarizer] The reflective circular polarizer of the present invention is a reflective circular polarizer including a cholesteric liquid crystal layer, which reflects circularly polarized light in one rotation direction and transmits circularly polarized light in the other rotation direction.

[0017] Here, the reflective circular polarizer of the present invention satisfies the relationship of the following formula (1): I1 + I2 + I3 + I4 + I5 < 3.0 (1)

[0018] Here, I1 is the value obtained by doubling the transmittance of circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer, among the transmitted light that passes through the reflective circular polarizer when the circularly polarized light reflected by the reflective circular polarizer is incident on the reflective circular polarizer.

[0019] I2 is the value obtained by halving the reflectance of circularly polarized light having a rotation direction opposite to that of the circularly polarized light reflected by the reflective circular polarizer when the circularly polarized light reflected by the reflective circular polarizer is incident on the reflective circular polarizer.

[0020] I3 is the value obtained by multiplying the reflectance of light reflected by a reflective circular polarizer by 1 / 4 when circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer is incident on the reflective circular polarizer.

[0021] I4 represents the haze value of the reflective circular polarizer.

[0022] I5 represents the value of SCE / SCI x 100 in reflectance measured with an integrating sphere when unpolarized light is incident on a reflective circular polarizer.

[0023] [Virtual reality display device A] The virtual reality display device of the present invention is a virtual reality display device having the above-mentioned reflective circular polarizer. Preferably, the virtual reality display device further includes a half mirror.

[0024] FIG. 1 shows a conceptual diagram of an example of a virtual reality display device of the present invention, which includes a reflective circular polarizer of the present invention.

[0025] 1 includes, in this order, an image display panel 102, a λ / 4 plate 104, an absorbing linear polarizer 106, a λ / 4 plate 108, a half mirror 12, a support 14, a reflective circular polarizer 10, a retardation layer 24, and an absorbing linear polarizer 22. The λ / 4 plate 104, the absorbing linear polarizer 106, the λ / 4 plate 108, the support 14, the retardation layer 24, and the absorbing linear polarizer 22 are components that are preferably included in the virtual reality display device of the present invention. The laminate of the reflective circular polarizer 10, the retardation layer 24, and the absorbing linear polarizer 22 corresponds to a laminated optical film 20a of the present invention, which will be described later.

[0026] In the virtual reality display device 100a shown in Fig. 1, a half mirror 12 is disposed on the surface of the support 14 facing the image display panel 102, and a reflective circular polarizer 10 is disposed on the other surface of the support. In the illustrated example, both surfaces of the support 14 are curved convexly toward the image display panel 102, and have a lens effect. In other words, in the example shown in Fig. 1, a lens is used as the support 14. The support 14 is preferably transparent, and for example, a resin film such as cellulose acylate or polycarbonate, or glass, can be used.

[0027] In the virtual reality display device 100a, light that forms an image emitted from the image display panel 102 passes through the λ / 4 plate 104, the absorbing linear polarizer 106, and the λ / 4 plate 108 in this order, is converted into circularly polarized light, and is then incident on the half mirror 12. Hereinafter, as an example, right-handed circularly polarized light I R1 The following description will be given on the assumption that the light beam enters the half mirror 12 as shown in FIG.

[0028] In the example shown in Fig. 1, the light (image) emitted from the image display panel 102 is described as being incident on the half mirror 12 as right-handed circularly polarized light, but in the present invention, the light emitted from the image display panel 102 may be incident on the half mirror 12 as left-handed circularly polarized light. In this case, the polarization state of each light on the optical path is reversed from that in the example shown in Fig. 1. Furthermore, in the example shown in Fig. 1, for the sake of explanation, the optical paths of the light reflected by the half mirror 12 and / or the reflective circular polarizer 10 are shown so as not to overlap, but basically they are specularly reflected. These points are the same in other figures.

[0029] Right-handed circularly polarized light I incident on the half mirror 12 R1 A part of the incident right-handed circularly polarized light I is transmitted through the half mirror 12 and the support 14, and then enters the reflective circular polarizer 10. In the example shown in FIG. 1, the reflective circular polarizer 10 reflects right-handed circularly polarized light and transmits left-handed circularly polarized light. R1 is reflected by the reflective circular polarizer 10 and enters the half mirror 12 again (right-handed circularly polarized light I R2 Right-handed circularly polarized light I incident on the half mirror 12 R2 A part of the circularly polarized light is reflected by the half mirror 12 and travels toward the reflective circular polarizer 10. At this time, the direction of rotation of the circularly polarized light is reversed by the reflection by the half mirror 12, so that the right-handed circularly polarized light I R2 is left-handed circularly polarized light I L1 The left-handed circularly polarized light I incident on the reflective circular polarizer 10 is converted into L1 The light passes through the retardation layer 24 and the absorbing linear polarizer 22, is converted into linearly polarized light, and is then irradiated onto the user U. As a result, the video (image) displayed on the image display panel 102 is viewed by the user U as a virtual image.

[0030] In the virtual reality display device 100a, ideally, light travels along the optical path described above to display an image to the user U. However, stray light I that deviates from this optical path may occur. X It was found that the presence of stray light I reduces the contrast of the displayed image. X It has been found that there are various causes of this phenomenon. This point will be explained using Figs.

[0031] 2 is a schematic diagram illustrating the cause of contrast reduction in a virtual reality display device having a reflective circular polarizer. For ease of explanation, the λ / 4 plate 104, the absorbing linear polarizer 106, the λ / 4 plate 108, the support 14, the retardation layer 24, and the absorbing linear polarizer 22 are not shown in FIG. 2, but these components may also be included in the virtual reality display device shown in FIG. 2.

[0032] Hereinafter, a case will be described in which the image display panel 102 displays an image in which white display areas 202 and black display areas 204 are arranged in a checkered pattern as shown in FIG.

[0033] As shown in FIG. 2, right-handed circularly polarized light I irradiated from the image display panel 102 R1 A part of the light is transmitted through the half mirror 12 and reflected by the reflective circular polarizer 10 to become right-handed circularly polarized light I R2 The light is then incident on the half mirror 12 again as it is, and a part of it is reflected and becomes left-handed circularly polarized light I L1 3 is transmitted through the reflective circular polarizer 10 and displayed to the user U. Hereinafter, the image displayed on this ideal optical path will also be referred to as the main image.

[0034] As shown in FIG. 2, right-handed circularly polarized light I irradiated from the image display panel 102 and transmitted through the half mirror 12 is R1 is incident on the reflective circular polarizer 10, the stray light I X1 This stray light I X1 is displayed as a ghost (hereinafter also referred to as a transmission ghost) superimposed on the main image. X1Since the optical path of the transmitted ghost is shorter than that of the main image and is displayed smaller than the main image, the display positions and sizes of the black and white portions 206 and 208 of the transmitted ghost are different from the display positions and sizes of the black and white portions 202 and 204 of the main image, respectively, as shown in Figure 4. As a result, a portion of the white portion 208 of the transmitted ghost overlaps a portion of the black portion 202 of the main image. In this overlapping portion 209, the luminance increases due to the influence of the white portion 208 of the transmitted ghost, resulting in a gray display. As a result, the luminance ratio between the black and white portions of the checkered pattern actually displayed, i.e., the contrast, decreases.

[0035] Also, in Fig. 2, X2 As shown by the arrows, the stray light I is reflected twice by the half mirror 12 and the reflective circular polarizer 10 and then exits. X2 According to the investigations of the present inventors, the right-handed circularly polarized light I R1 When the light is reflected by the reflective circular polarizer 10, a component is reflected as left-handed circularly polarized light, resulting in stray light I X2 Specifically, a portion of the light reflected by the reflective circular polarizer 10 as left-handed circularly polarized light is reflected by the half mirror 12, and is converted into right-handed circularly polarized light. This right-handed circularly polarized light is reflected by the reflective circular polarizer 10 and enters the half mirror 12, and a portion of it is reflected by the half mirror 12 and converted into left-handed circularly polarized light, which again enters the reflective circular polarizer 10 and passes through the reflective circular polarizer 10, resulting in stray light I X2 2, the stray light indicated by the broken line is indicated by R when it is right-handed circularly polarized light, and by L when it is left-handed circularly polarized light. This also applies to FIG. 10, which will be described later.

[0036] Also, in Fig. 2, X3 As shown by the arrows, the stray light I is reflected three times by the half mirror 12 and the reflective circular polarizer 10 and then exits. X3 According to the investigations of the present inventors, the left circularly polarized light I L1 When the light passes through the reflective circular polarizer 10, a reflected component is generated, resulting in stray light I X3Specifically, left-handed circularly polarized light I reflected by the half mirror 12 L1 When the left-handed circularly polarized light is incident on the reflective circular polarizer 10, a part of it is reflected. This left-handed circularly polarized light is incident on the half mirror 12, a part of it is reflected by the half mirror 12, and at that time, it is converted into right-handed circularly polarized light. This right-handed circularly polarized light is reflected by the reflective circular polarizer 10 and incident on the half mirror 12, a part of it is reflected by the half mirror 12 and converted into left-handed circularly polarized light, which again enters the reflective circular polarizer 10 and passes through the reflective circular polarizer 10, resulting in stray light I X3 is emitted as

[0037] Such stray light I X2 and stray light I X3 is displayed as a ghost (hereinafter also referred to as a reflected ghost) superimposed on the main image. X2 and stray light I X3 The optical path of the reflected ghost is longer than that of the main image and is displayed larger than the main image, so that the display positions and sizes of the black and white portions 210 and 212 of the reflected ghost are different from the display positions and sizes of the black and white portions 202 and 204 of the main image, respectively, as shown in Figure 5. As a result, part of the white portion 212 of the reflected ghost overlaps part of the black portion 202 of the main image. In this overlapping portion 213, the luminance is increased due to the influence of the white portion 212 of the reflected ghost, resulting in a gray display. As a result, the luminance ratio between the black and white portions of the checkered pattern actually displayed, i.e., the contrast, decreases.

[0038] Also, in Fig. 2, X4 As shown in the figure, left-handed circularly polarized light I reflected by the half mirror 12 L1 However, when passing through the reflective circular polarizer 10, a part of the light is scattered and becomes stray light I X4 This stray light I X4 The white part of the main image is diffused and the stray light I is displayed as a blurred image superimposed on the main image. X46, the light is scattered in various directions different from the optical path of the main image, and is superimposed on the entire main image, increasing the brightness of the black display area 202 and resulting in a gray display. As a result, the brightness ratio between the black display area and the white display area of ​​the checkered pattern actually displayed, i.e., the contrast, decreases.

[0039] Also, in Fig. 2, X5 As shown by the arrow, right-handed circularly polarized light I R1 However, when reflected by the reflective circular polarizer 10, a part of the light is scattered and becomes stray light I X5 This stray light I X5 The white part of the main image is diffused and the stray light I is displayed as a blurred image superimposed on the main image. X5 6, the light is scattered in various directions different from the optical path of the main image, and is superimposed on the entire main image, increasing the brightness of the black display area 202 and resulting in a gray display. As a result, the brightness ratio between the black display area and the white display area of ​​the checkered pattern actually displayed, i.e., the contrast, decreases.

[0040] As described above, the present inventors have found that various types of stray light generated in the optical path of the main image cause a decrease in the contrast of the displayed image.

[0041] In contrast, the reflective circular polarizer of the present invention includes a cholesteric liquid crystal layer and satisfies the following formula (1): I1 + I2 + I3 + I4 + I5 < 3.0 (1)

[0042] Here, I1 is the circularly polarized light reflected by the reflective circular polarizer 10 (in the illustrated example, right-handed circularly polarized light I R ) is incident on the reflective circular polarizer 10, the transmitted light passing through the reflective circular polarizer 10 is circularly polarized light I having a rotation direction opposite to that of the circularly polarized light reflected by the reflective circular polarizer 10. 01 (In the illustrated example, left-handed circularly polarized light) 01 Spectral irradiance / I R I1 is the value obtained by averaging the spectral irradiance (of the polarizer) from 450 nm to 650 nm and doubling it. ＡＲ(λ)) was laminated to obtain I1' by the above measurement, and then the reflectance R ＡＲ (λ) is subtracted. Expressed as a formula, I1 = I1' - R ＡＲ (λ).

[0043] Circular Polarization I 01 The transmittance of the circular polarizer 10 can be measured as follows. A spectrophotometer (for example, a UV-visible-near-infrared spectrophotometer V-750 manufactured by JASCO Corporation) was used, and a reflective circular polarizer 10 was set between a light source and a detector to detect light transmitted through the reflective circular polarizer 10. A wideband circular polarizer was set on the light source side so that right-handed circularly polarized light was incident on the reflective circular polarizer 10, and a wideband circular polarizer was set on the detector side so that right-handed circularly polarized light was cut off and only left-handed circularly polarized light was detected. 01 The spectral irradiance of the incident right-handed circularly polarized light I is measured. R From the ratio of the spectral irradiance to the circularly polarized light I 01 The transmittance can be calculated.

[0044] As shown in FIG. 7, I2 is the circularly polarized light reflected by the reflective circular polarizer 10 (in the illustrated example, right-handed circularly polarized light I R When light having a circular rotation direction opposite to that of the circularly polarized light reflected by the reflective circular polarizer 10 is incident on the reflective circular polarizer 10, the light having a circular rotation direction opposite to that of the circularly polarized light reflected by the reflective circular polarizer 10 is 02 (In the illustrated example, left-handed circularly polarized light) 02 Spectral irradiance / I R I2 is the value obtained by averaging the spectral irradiance (of the polarizer) from 450 nm to 650 nm and multiplying it by half. ＡＲ (λ)) is laminated to obtain I2' by the above measurement, and then the reflectance R of the anti-reflection film is ＡＲ (λ) is subtracted. Expressed as a formula, I2 = I2' - R ＡＲ (λ).

[0045] Circular Polarization I 02The reflectance of can be measured as follows. Using a spectrophotometer (for example, a UV-visible-near-infrared spectrophotometer V-750 manufactured by JASCO Corporation), a light source and a detector are set on one side of the reflective circular polarizer 10, and light reflected by the reflective circular polarizer 10 is detected. In this case, a wideband circular polarizer is set on the light source side so that right-handed circularly polarized light is incident on the reflective circular polarizer 10, and a wideband circular polarizer is set on the detector side so that right-handed circularly polarized light is cut out and only left-handed circularly polarized light is detected. 02 The spectral irradiance of the incident right-handed circularly polarized light I is measured. R From the ratio of the spectral irradiance to the circularly polarized light I 02 The reflectance can be calculated.

[0046] As shown in FIG. 8, I3 is circularly polarized light having a rotation direction opposite to that of the circularly polarized light reflected by the reflective circular polarizer 10 (left-handed circularly polarized light I3 in the illustrated example). L ) is incident on the reflective circular polarizer 10, the reflected light I reflected by the reflective circular polarizer 10 03 The reflectance of each wavelength (I 03 Spectral irradiance / I L I3 is the value obtained by averaging the spectral irradiance (spectral irradiance) from 450 nm to 650 nm and multiplying it by 1 / 4. ＡＲ (λ)) is laminated to obtain I3' by the above measurement, and then the reflectance R ＡＲ (λ) is subtracted. Expressed as a formula, I3 = I3' - R ＡＲ (λ).

[0047] Reflected light I 03 The reflectance of can be measured as follows: Using a spectrophotometer (for example, a UV-visible-near-infrared spectrophotometer V-750 manufactured by JASCO Corporation), a light source and a detector are set on one side of the reflective circular polarizer 10, and light reflected by the reflective circular polarizer 10 is detected. At this time, a wideband circular polarizer is set on the light source side so that left-handed circularly polarized light is incident on the reflective circular polarizer 10, and a wideband circular polarizer is set on the detector side so that right-handed circularly polarized light is cut out and only left-handed circularly polarized light is detected. 03 The spectral irradiance of the incident left-handed circularly polarized light I is measured. L From the ratio of the spectral irradiance to the reflected light I03 The reflectance can be calculated.

[0048] I4 represents the haze value of the reflective circular polarizer 10. The haze value may be measured using a haze meter (for example, NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7136.

[0049] I5 represents the value of SCE / SCI×100 in the reflectance measured with an integrating sphere when unpolarized light is incident on the reflective circular polarizer 10.

[0050] SCE and SCI can be measured by installing an integrating sphere unit in a spectrophotometer (for example, a UV-Vis-Near-Infrared Spectrophotometer V-750 manufactured by JASCO Corporation). SCE is the reflectance when specular reflection is removed, obtained by absorbing specular reflection light with a light trap. SCI is the reflectance including specular reflection light, obtained by installing a white plate in the light trap section.

[0051] When the reflective circular polarizer 10 satisfies the above formula (1), the stray light I that becomes the above-mentioned transmission ghost when used in a virtual reality display device can be reduced. X1 , stray light I that becomes a reflected ghost X2 and I X3 , the scattered component of stray light I X4 and I X5 Therefore, it is possible to suppress a decrease in the contrast of the displayed image.

[0052] Here, from the viewpoint of suppressing a decrease in contrast of the displayed image, it is preferable to satisfy 0≦I1+I2+I3+I4+I5<3.0, and it is more preferable to satisfy 0≦I1+I2+I3+I4+I5<2.8.

[0053] Here, the following methods can be used to make a reflective circular polarizer including a cholesteric liquid crystal layer satisfy the above formula (1).

[0054] A method for reducing I1, I2, and I3 mainly caused by transmission ghost and / or reflection ghost is to provide an Rth compensation layer that offsets the thickness direction retardation Rth of the cholesteric liquid crystal layer.

[0055] As is well known, a cholesteric liquid crystal layer has a structure in which liquid crystal compounds are stacked in a spiral shape in the thickness direction. When a rod-shaped liquid crystal compound is used as the liquid crystal compound, the thickness direction retardation Rth is positive. On the other hand, when a discotic liquid crystal compound is used as the liquid crystal compound, the thickness direction retardation Rth is negative. In either case, ghost images tend to occur when light is incident obliquely on the reflective circular polarizer. In response to this, providing an Rth compensation layer to offset the thickness direction retardation Rth can suppress the occurrence of ghost images when light is incident obliquely. Examples of the Rth compensation layer include a C plate. Furthermore, when the reflective circular polarizer has a structure including multiple cholesteric liquid crystal layers, some of the multiple cholesteric liquid crystal layers may be cholesteric liquid crystal layers X formed using a rod-shaped liquid crystal compound and the other parts may be cholesteric liquid crystal layers Y formed using a discotic liquid crystal compound, thereby offsetting the thickness direction retardation Rth. In other words, each cholesteric liquid crystal layer corresponds to an Rth compensation layer.

[0056] For example, as in the example shown in FIG. 13 , when the reflective circular polarizer 10 a has five cholesteric liquid crystal layers 30 to 38, the cholesteric liquid crystal layer 30 may be a cholesteric liquid crystal layer X formed using a rod-shaped liquid crystal compound, the cholesteric liquid crystal layer 32 may be a cholesteric liquid crystal layer Y formed using a discotic liquid crystal compound, the cholesteric liquid crystal layer 34 may be a cholesteric liquid crystal layer X, the cholesteric liquid crystal layer 36 may be a cholesteric liquid crystal layer Y, and the cholesteric liquid crystal layer 38 may be a cholesteric liquid crystal layer X, so that the three cholesteric liquid crystal layers X and the two cholesteric liquid crystal layers Y cancel out the thickness direction retardation Rth of the reflective circular polarizer 10 as a whole.

[0057] In the above description, the cholesteric liquid crystal layer X formed using a rod-shaped liquid crystal compound and the cholesteric liquid crystal layer Y formed using a discotic liquid crystal compound are alternately laminated, but this is not limitative, and the cholesteric liquid crystal layer X may be continuously laminated, or the cholesteric liquid crystal layer Y may be continuously laminated, as long as the thickness direction retardation Rth can be offset.

[0058] In addition, in the example shown in FIG. 13, the structure has five cholesteric liquid crystal layers, but the present invention is not limited to this, and the structure may have two to four cholesteric liquid crystal layers, or six or more cholesteric liquid crystal layers, as long as the thickness direction retardation Rth can be offset.

[0059] Furthermore, when the reflective circular polarizer 10a has a cholesteric liquid crystal layer X formed using a rod-shaped liquid crystal compound and a cholesteric liquid crystal layer Y formed using a discotic liquid crystal compound, the selective reflection center wavelength of the cholesteric liquid crystal layer X and the selective reflection center wavelength of the cholesteric liquid crystal layer Y may be the same or different from each other. Furthermore, when the reflective circular polarizer 10a has a plurality of cholesteric liquid crystal layers X, the selective reflection center wavelengths of the cholesteric liquid crystal layers X may be the same or different from each other. Similarly, when the reflective circular polarizer 10a has a plurality of cholesteric liquid crystal layers Y, the selective reflection center wavelengths of the cholesteric liquid crystal layers Y may be the same or different from each other.

[0060] Another method for reducing I1, I2, and I3, which are primarily caused by transmission ghosts and / or reflection ghosts, is to suppress interfacial reflection. As shown in FIG. 1, when a reflective circular polarizer 10 is used in a virtual reality display device 100a, it is attached to another component (support 14 in the example shown in FIG. 1). In this case, reflection occurs at the interface between the reflective circular polarizer 10 and the other component, or between the reflective circular polarizer 10 and an adhesive layer used to attach the reflective circular polarizer 10 to the other component. When light is reflected at an interface, the rotation direction of the circularly polarized light changes, unlike reflection by the reflective circular polarizer 10 (cholesteric liquid crystal layer). Therefore, the occurrence of ghosts can be suppressed by suppressing interfacial reflection.

[0061] One method for suppressing interface reflection is to provide a light interference layer between the reflective circular polarizer 10 and another member, or between the reflective circular polarizer 10 and an adhesive layer. The refractive index of the light interference layer is preferably between the refractive index of the reflective circular polarizer 10 and the other member, or between the refractive index of the reflective circular polarizer 10 and the adhesive layer, and the film thickness is preferably in the range of 60 to 110 nm or 230 to 330 nm. This allows the phases of light reflected at the interface between the reflective circular polarizer 10 and the light interference layer and light reflected at the interface between the light interference layer and the other member (or adhesive layer) to be suitably shifted, thereby canceling out the reflected light. As a result, the generation of ghost images due to unnecessary light reflection at the interface can be suppressed.

[0062] When the refractive index of the adhesive layer is nA and the refractive index of the reflective circular polarizer 10 is nL, the refractive index nI of the optical interference layer is (nA × nL) １／２ −0.03≦nI≦(nA×nL) １／２ It is preferable to satisfy +0.03, (nA × nL) １／２ −0.02≦nI≦(nA×nL) １／２ It is more preferable to satisfy +0.02, (nA × nL) １／２ −0.01≦nI≦(nA×nL) １／２ It is more preferable that the refractive index of the layer adjacent to the optical interference layer satisfies +0.01. When the reflective circular polarizer 10 has a plurality of layers, the refractive index of the layer adjacent to the optical interference layer may be set to nL. By setting the refractive index of the optical interference layer within this range, the amplitudes of the reflected light at both interfaces of the optical interference layer can be made approximately equal, thereby achieving a greater anti-reflection effect.

[0063] The thickness of the optical interference layer is more preferably in the range of 75 to 100 nm or 245 to 300 nm, and even more preferably in the range of 80 to 95 nm or 260 to 285 nm.

[0064] One method for reducing I4 and I5, which are primarily caused by scattering components, is to suppress the disordered alignment of the liquid crystal compound in the cholesteric liquid crystal layer. As described below, the cholesteric liquid crystal layer is formed by applying a liquid crystal composition containing a liquid crystal compound to the surface (on the alignment film) on which the cholesteric liquid crystal layer is to be formed, then performing an alignment treatment (heating, etc.) to cholesterically align the liquid crystal compound in the coating, and then curing the coating by irradiating ultraviolet (UV) light. In this case, when a rod-shaped liquid crystal compound is used, it is preferable to use a lower UV curing temperature. On the other hand, when a discotic liquid crystal compound is used, it is preferable to use a higher UV curing temperature or to leave the coating at the UV curing temperature for a certain period of time before UV curing. This allows for the formation of a cholesteric liquid crystal layer with less disordered alignment of the liquid crystal compound, thereby reducing the scattering of light when passing through or reflecting from the cholesteric liquid crystal layer. As a result, the occurrence of ghost images due to light scattering can be suppressed.

[0065] Specifically, when a rod-shaped liquid crystal compound is used, the temperature during UV curing is preferably 30 to 60°C, and more preferably 40 to 50°C.

[0066] When a discotic liquid crystal compound is used, the temperature during UV curing is preferably 50 to 100°C, more preferably 60 to 80°C.

[0067] When a discotic liquid crystal compound is used, if the temperature during UV curing is 50° C. or lower, the standing time before UV curing is preferably 3 to 60 minutes, more preferably 5 to 10 minutes.

[0068] Another method for reducing I5 is to suppress the occurrence of disturbances in the helical structure that constitutes the cholesteric liquid crystal layer. Disturbances in the helical structure refer to a state in which, when a surface in which the alignment direction (director) of the liquid crystal material that constitutes the cholesteric liquid crystal layer is the same, the equiphase surface is not flat but has irregularities on part or the entire surface. Causes of irregularities in the equiphase surface include the occurrence of discontinuity in the cholesteric alignment, the occurrence of a wavy structure, and variations in the helical pitch within the liquid crystal layer.

[0069] Disclination can be caused by the inclusion of impurities or the precipitation of liquid crystal material. One way to address this issue is to use a high temperature or long duration heat treatment to promote liquid crystal alignment before UV curing, thereby promoting dissolution and diffusion of the material. Another method is to increase solubility by selecting the right solvent for the solution and adjusting the solid content, thereby suppressing the occurrence of precipitation.

[0070] The wavy structure can occur when the degree of orientation of the underlying alignment film is insufficient, and can be improved by increasing the degree of orientation. It can also occur when unevenness in the alignment film or the underlying liquid crystal layer propagates, and can be improved by reducing the unevenness in the alignment film or the underlying liquid crystal layer. It can also occur when the material at the air interface of the coating film develops a phase separation structure, and can be improved by increasing the temperature of the coating film to eliminate the phase separation.

[0071] Variations in helical pitch within the liquid crystal layer can be caused by uneven cure shrinkage. Uneven cure shrinkage is more likely to occur when the viscosity of the liquid crystal material is high, for example, when a discotic liquid crystal compound is used. Methods to improve this include increasing the temperature of the coating to lower the viscosity, increasing the amount of photopolymerization initiator to increase the number of initiation sites for radical polymerization, and increasing the intensity of UV light for UV curing to increase the number of initiation sites for radical polymerization.

[0072] Furthermore, when the reflective circular polarizer 10 has multiple cholesteric liquid crystal layers with different selective reflection center wavelengths, it is preferable that the cholesteric liquid crystal layer that reflects a wavelength range with high luminosity is the first layer on the light incident side (the half mirror 12 side). That is, it is preferable to arrange the cholesteric liquid crystal layer with a selective reflection center wavelength closest to 550 nm on the half mirror 12 side. This allows light in a wavelength range with high luminosity to be reflected by the first cholesteric liquid crystal layer before passing through the other cholesteric liquid crystal layers, thereby suppressing scattering at interfaces between cholesteric liquid crystal layers, etc.

[0073] [Laminated Optical Film] The laminated optical film of the present invention is a laminated optical film including a reflective circular polarizer and an absorptive linear polarizer, and the laminated optical film satisfies the relationship of the following formula (2): I + I + I + I + I 10 <3.5

[0074] Here, I6 is the value obtained by doubling the transmittance of the laminated optical film when circularly polarized light reflected by the laminated optical film is incident on the reflective circular polarizer side of the laminated optical film.

[0075] I7 is the value obtained by multiplying the reflectance of circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer among the reflected light reflected by the laminated optical film when the circularly polarized light reflected by the laminated optical film is incident on the reflective circular polarizer side of the laminated optical film.

[0076] I8 is the value obtained by multiplying the reflectance of light reflected by a laminated optical film by 1 / 4 when circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the laminated optical film is incident on the reflective circular polarizer side of the laminated optical film.

[0077] I9 represents the haze value when light is incident on the laminated optical film from the reflective circular polarizer side of the laminated optical film.

[0078] I 10 represents the value of SCE / SCI×100 in the reflectance measured with an integrating sphere when unpolarized light is incident on the laminated optical film from the reflective circular polarizer side of the laminated optical film.

[0079] [Virtual reality display device B] The virtual reality display device of the present invention is a virtual reality display device having the laminated optical film described above. Preferably, the virtual reality display device further includes a half mirror.

[0080] FIG. 9 shows a conceptual diagram of another example of the virtual reality display device of the present invention, which includes the laminated optical film of the present invention.

[0081] 9 includes, in this order, an image display panel 102, a λ / 4 plate 104, an absorbing linear polarizer 106, a λ / 4 plate 108, a half mirror 12, a support 14, a retardation layer 18, a reflective linear polarizer 16, and an absorbing linear polarizer 22. The laminate of the retardation layer 18 and the reflective linear polarizer 16 corresponds to the reflective circular polarizer 11, and the laminate of the reflective circular polarizer 11 and the absorbing linear polarizer 22 corresponds to the laminated optical film 20b of the present invention. The λ / 4 plate 104, the absorbing linear polarizer 106, the λ / 4 plate 108, and the support 14 are components that are preferably included in the virtual reality display device of the present invention.

[0082] In the virtual reality display device 100b, light that forms an image emitted by the image display panel 102 passes through the λ / 4 plate 104, the absorbing linear polarizer 106, and the λ / 4 plate 108 in this order, is converted into circularly polarized light, and is then incident on the half mirror 12. Hereinafter, as an example, right-handed circularly polarized light I R1 The following description will be given on the assumption that the light beam enters the half mirror 12 as shown in FIG.

[0083] Right-handed circularly polarized light I incident on the half mirror 12 R1 A part of the right-handed circularly polarized light I is transmitted through the half mirror 12 and the support 14, and is incident on the reflective circular polarizer 11. In the example shown in FIG. 9, the reflective circular polarizer 11 has a retardation layer 18 on the half mirror 12 side, and the right-handed circularly polarized light I R1 This linearly polarized light is incident on the reflective linear polarizer 16. The reflective linear polarizer 16 is arranged such that the direction of its reflection axis is such that it reflects the linearly polarized light converted from right-handed circularly polarized light by the retardation layer 18. The linearly polarized light reflected by the reflective linear polarizer 16 is incident on the retardation layer 18 again and converted into right-handed circularly polarized light I R2 This right-handed circularly polarized light I R2 is incident on the half mirror 12, where a part of it is reflected and travels toward the reflective circular polarizer 11. At this time, the rotation direction of the circularly polarized light is reversed by the reflection from the half mirror 12, so that the right-handed circularly polarized light I R2 is left-handed circularly polarized light I L1 The left-handed circularly polarized light I is incident on the reflective circular polarizer 11. L1is converted into linearly polarized light by the retardation layer 18. The polarization direction of this linearly polarized light is perpendicular to the reflection axis of the reflective linear polarizer 16, so it is transmitted through the reflective linear polarizer 16. This linearly polarized light is incident on the absorbing linear polarizer 22, but the transmission axis of the absorbing linear polarizer 22 is arranged parallel to the transmission axis of the reflective linear polarizer 16, so it passes through the absorbing linear polarizer 22 and is irradiated onto the user U. As a result, the video (image) displayed by the image display panel 102 is viewed by the user U as a virtual image.

[0084] In the virtual reality display device 100b, ideally, light travels along the optical path described above to display an image to the user U. However, stray light I that deviates from this optical path may occur. X It was found that the presence of stray light I reduces the contrast of the displayed image. X It has been found that there are various causes of this phenomenon. This point will be explained with reference to FIG.

[0085] Fig. 10 is a schematic diagram for explaining the cause of contrast reduction in a virtual reality display device having a laminated optical film. For the sake of explanation, the λ / 4 plate 104, the absorbing linear polarizer 106, the λ / 4 plate 108, and the support 14 are not shown in Fig. 10, but these components may also be included in the virtual reality display device shown in Fig. 10.

[0086] The optical path of the main image is as explained in FIG.

[0087] As shown in FIG. 10, right-handed circularly polarized light I irradiated from the image display panel 102 and transmitted through the half mirror 12 R1 However, when the light is incident on the reflective circular polarizer 11, stray light is transmitted without being reflected. Of this stray light, the linearly polarized component parallel to the absorption axis of the absorbing linear polarizer 22 is absorbed, but the linearly polarized component perpendicular to the absorption axis is transmitted, resulting in stray light I X6 This stray light I X6The white portion 208 of the transmission ghost is displayed superimposed on the main image (see FIG. 4). As a result, a part of the white portion 208 of the transmission ghost overlaps with a part of the black display portion 202 of the main image. In this overlapping portion 209, the brightness increases due to the influence of the white portion 208 of the transmission ghost, and the overlapping portion 209 appears gray. As a result, the brightness ratio between the black display portion and the white display portion of the checker pattern actually displayed, i.e., the contrast, decreases.

[0088] Also, in Figure 10, X7 As shown by the arrows, the stray light I is reflected twice by the half mirror 12 and the reflective circular polarizer 11 and then exits. X7 According to the investigations of the present inventors, the right-handed circularly polarized light I R1 When the light is reflected by the reflective circular polarizer 11, a component is reflected as left-handed circularly polarized light, resulting in stray light I X7 Specifically, a part of the light reflected by the reflective circular polarizer 11 as left-handed circularly polarized light is reflected by the half mirror 12, and at that time, is converted into right-handed circularly polarized light. This right-handed circularly polarized light is reflected by the reflective circular polarizer 11 and enters the half mirror 12, and a part of it is reflected by the half mirror 12 and converted into left-handed circularly polarized light, and again enters the reflective circular polarizer 11, and passes through the reflective circular polarizer 11 to produce stray light I X7 is emitted as

[0089] Also, in Figure 10, X8 As shown by the arrows, the stray light I is reflected three times by the half mirror 12 and the reflective circular polarizer 11 and then exits. X8 According to the investigations of the present inventors, in the optical path of the main image, left-handed circularly polarized light I L1 When the light passes through the reflective circular polarizer 11, a reflected component is generated, resulting in stray light I X8 Specifically, left-handed circularly polarized light I reflected by the half mirror 12 L1When the left-handed circularly polarized light is incident on the reflective circular polarizer 11, a part of it is reflected. This left-handed circularly polarized light is incident on the half mirror 12, a part of it is reflected by the half mirror 12, and at that time, it is converted into right-handed circularly polarized light. This right-handed circularly polarized light is reflected by the reflective circular polarizer 11 and incident on the half mirror 12, a part of it is reflected by the half mirror 12 and converted into left-handed circularly polarized light, and again incident on the reflective circular polarizer 11, and passes through the reflective circular polarizer 11 to become stray light I X8 is emitted as

[0090] Such stray light I X7 and stray light I X8 The white portion 212 of the reflected ghost is displayed superimposed on the main image (see FIG. 5). As a result, a part of the white portion 212 of the reflected ghost overlaps with a part of the black portion 202 of the main image. In this overlapping portion 213, the brightness increases due to the influence of the white portion 212 of the reflected ghost, resulting in a gray display. As a result, the brightness ratio between the black and white portions of the checkered pattern actually displayed, i.e., the contrast, decreases.

[0091] Also, in Figure 10, X9 As shown in the figure, left-handed circularly polarized light I reflected by the half mirror 12 L1 However, when passing through the reflective circular polarizer 11, a part of the light is scattered and becomes stray light I X9 This stray light I X9 The white part of the main image is diffused and displayed as a blurred image superimposed on the main image (see FIG. 6). Therefore, as shown in FIG. 6, the black display part 202 is superimposed on the entire main image, increasing the brightness of the black display part 202 and causing a gray display. This reduces the brightness ratio between the black display part and the white display part of the checker pattern actually displayed, i.e., the contrast.

[0092] Also, in Figure 10, X10 As shown by the arrow, right-handed circularly polarized light I R1 However, when reflected by the reflective circular polarizer 11, a part of the light is scattered and becomes stray light I X10 This stray light I X10The white part of the main image is diffused and displayed as a blurred image superimposed on the main image (see FIG. 6). Therefore, as shown in FIG. 6, the black display part 202 is superimposed on the entire main image, increasing the brightness of the black display part 202 and causing a gray display. This reduces the brightness ratio between the black display part and the white display part of the checker pattern actually displayed, i.e., the contrast.

[0093] In contrast, the laminated optical film of the present invention includes a reflective circular polarizer and an absorbing linear polarizer, and the laminated optical film satisfies the relationship of the following formula (2): I + I + I + I + I 10 <3.5

[0094] Here, I6 is the circularly polarized light (right-handed circularly polarized light I6 in the illustrated example) reflected by the laminated optical film 20 as shown in FIG. R ) is incident from the reflective circular polarizer 11 side, the transmitted light I that passes through the laminated optical film 06 (linearly polarized light) transmittance (I 06 Spectral irradiance / I R I6 is the value obtained by averaging the spectral irradiance (reflectance R ＡＲ (λ)) was laminated to obtain I6', and then the reflectance R ＡＲ (λ) is subtracted. Expressed as a formula, I6 = I6' - R ＡＲ (λ).

[0095] Transmitted light I 06 The transmittance of the laminated optical film 20 can be measured as follows. Using a spectrophotometer (for example, a UV-visible-near-infrared spectrophotometer V-750 manufactured by JASCO Corporation), the laminated optical film 20 is set between a light source and a detector to detect light transmitted through the laminated optical film 20. In addition, a wideband circular polarizing plate is set on the light source side so that right-handed circularly polarized light is incident on the reflective circular polarizer 11, and the transmitted light I 06 The spectral irradiance of the incident right-handed circularly polarized light I is measured. R From the ratio of the spectral irradiance to the transmitted light I 06 The transmittance can be calculated.

[0096] As shown in FIG. 11, I7 is circularly polarized light (right-handed circularly polarized light I R When light having a circular rotation direction opposite to that of the circularly polarized light reflected by the reflective circular polarizer 11 is incident on the laminated optical film 20, the light having a circular rotation direction opposite to that of the circularly polarized light reflected by the reflective circular polarizer 11 is 07 (In the illustrated example, left-handed circularly polarized light) 07 Spectral irradiance / I R The spectral irradiance of the light is averaged from 450 nm to 650 nm and multiplied by half. ７ indicates that anti-reflection films (reflectance R ＡＲ (λ)) was laminated and the above measurement was carried out. ７ After obtaining the reflectance R of the anti-reflection film, ＡＲ (λ) is subtracted. ７ =I ７ '-R ＡＲ (λ).

[0097] Circular Polarization I 07 The reflectance of the laminated optical film 20 can be measured as follows. Using a spectrophotometer (for example, a UV-visible-near-infrared spectrophotometer V-750 manufactured by JASCO Corporation), a light source and a detector are set on one side of the laminated optical film 20 to detect light reflected by the laminated optical film 20. At this time, a wideband circular polarizer is set on the light source side so that right-handed circularly polarized light is incident on the reflective circular polarizer, and a wideband circular polarizer is set on the detector side so that right-handed circularly polarized light is cut out and only left-handed circularly polarized light is detected, and the circularly polarized light I is measured. 07 The spectral irradiance of the incident right-handed circularly polarized light I is measured. R From the ratio of the spectral irradiance to the circularly polarized light I 07 The reflectance can be calculated.

[0098] As shown in FIG. 12, I is circularly polarized light having a rotation direction opposite to that of the circularly polarized light reflected by the laminated optical film 20 (left-handed circularly polarized light I L ) is incident from the reflective circular polarizer 11 side, the reflected light I reflected by the laminated optical film 20 08 The reflectance of each wavelength (I 08 Spectral irradiance / I ＬI8 is the value obtained by averaging the spectral irradiance (spectral irradiance) from 450 nm to 650 nm and multiplying it by 1 / 4. ＡＲ (λ)) was laminated to obtain I8' by the above measurement, and then the reflectance R ＡＲ (λ) is subtracted. Expressed as a formula, I8 = I8' - R ＡＲ (λ).

[0099] Reflected light I 08 The reflectance of can be measured as follows. Using a spectrophotometer (for example, a UV-visible-near-infrared spectrophotometer V-750 manufactured by JASCO Corporation), a light source and a detector are set on one side of the laminated optical film 20 to detect light reflected by the laminated optical film 20. At this time, a wideband circular polarizer is set on the light source side so that left-handed circularly polarized light is incident on the laminated optical film 20, and a wideband circular polarizer is set on the detector side so that right-handed circularly polarized light is cut out and only left-handed circularly polarized light is detected. The reflected light I 08 The spectral irradiance of the incident left-handed circularly polarized light I is measured. L From the ratio of the spectral irradiance to the reflected light I 08 The reflectance can be calculated.

[0100] I9 represents the haze value of the laminated optical film 20. The haze value may be measured using a haze meter (for example, NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7136.

[0101] I 10 represents the value of SCE / SCI×100 in the reflectance measured with an integrating sphere when unpolarized light is incident on the laminated optical film 20 .

[0102] SCE and SCI can be measured by installing an integrating sphere unit in a spectrophotometer (for example, a UV-Vis-Near-Infrared Spectrophotometer V-750 manufactured by JASCO Corporation). SCE is the reflectance when specular reflection is removed, obtained by absorbing specular reflection light with a light trap. SCI is the reflectance including specular reflection light, obtained by installing a white plate in the light trap section.

[0103] When the laminated optical film 20 satisfies the above formula (2), the stray light I that becomes the above-mentioned transmission ghost when used in a virtual reality display device can be reduced. X6 , stray light I that becomes a reflected ghost X7 and I X8 , stray light I, which is a scattered component X9 and I X10 Therefore, it is possible to suppress a decrease in the contrast of the displayed image.

[0104] Here, from the viewpoint of suppressing a decrease in contrast of the displayed image, 0≦I6+I7+I8+I9+I 10 <3.5, and 0≦I6 + I7 + I8 + I9 + I 10 It is more preferable that the ratio <3.3 is satisfied.

[0105] Here, the laminated optical film 20b having the reflective circular polarizer 11 including the retardation layer 18 and the reflective linear polarizer 16 can be made to satisfy the above formula (2) by the following method.

[0106] One method for reducing I6 and I7, which are primarily caused by transmission ghosts and / or reflection ghosts, is to suppress interfacial reflection. As shown in FIG. 9, when the laminated optical film 20b is used in the virtual reality display device 100b, it is attached to another member (support 14 in the example shown in FIG. 2). In this case, reflection occurs at the interface between the laminated optical film 20b and the other member, or between the laminated optical film 20b and an adhesive layer for attaching the film to the other member. When light is reflected at the interface, unlike reflection by the reflective circular polarizer 11, the rotation direction of the circularly polarized light changes, and the circularly polarized light with the changed rotation direction can cause ghosts. Therefore, suppressing interfacial reflection can suppress the occurrence of ghosts.

[0107] As a method for suppressing the interfacial reflection, similar to the above-described example, there is a method of providing an optical interference layer between the reflective circular polarizer 11 and another member, or between the reflective circular polarizer 11 and an adhesive layer. For example, the optical interference layer may be disposed on the surface of the retardation layer 18 on the half mirror 12 side.

[0108] A main method for reducing I7 caused by reflection ghosts is to bring the polarization state when the light is incident on the reflective circular polarizer 11 for the second time in the path of the main image (the optical path passing through the reflective circular polarizer 11 ⇒ half mirror 12 ⇒ reflective circular polarizer 11 in that order) closer to ideal linear polarization (parallel to the transmission axis of the reflective linear polarizer 16) across the visible wavelength range. If the polarization state deviates from the ideal linear polarization, the component parallel to the reflection axis of the reflective linear polarizer 16 is reflected when the light is incident on the reflective linear polarizer 16 for the second time, increasing I7.

[0109] In the path of the main image, one method for making the polarization state when the light is incident on the reflective linear polarizer 16 for the second time closer to ideal linear polarization (parallel to the transmission axis of the reflective linear polarizer 16) across the visible wavelength range is to use a broadband λ / 4 plate in the retardation layer 18.

[0110] Furthermore, as a method for reducing I8 mainly caused by reflection ghosts, there is a method for suppressing light reflection in the transmission axis direction of the reflective linear polarizer 16.

[0111] One method for suppressing light reflection in the transmission axis direction of the reflective linear polarizer 16 is to suppress changes in the refractive index of the members constituting the reflective linear polarizer 16 in the transmission axis direction by optimizing the materials and manufacturing process.

[0112] In the above example, the laminated optical film 20b has a configuration in which the reflective circular polarizer 11 includes a retardation layer 18 and a reflective linear polarizer 16, but this is not limiting. The laminated optical film 20 may have a reflective circular polarizer including a cholesteric liquid crystal layer. In this case, the laminated optical film 20a preferably has a retardation layer 24 between the reflective circular polarizer 10 and the absorbing linear polarizer 22 (see FIG. 1 ).

[0113] Even when the laminated optical film 20a has a configuration in which a reflective circular polarizer 10, a retardation layer 24, and an absorbing linear polarizer 22 are arranged in this order, by satisfying the above formula (2), it is possible to suppress a decrease in the contrast of the displayed image when used in a virtual reality display device.

[0114] Here, as a method for making the laminated optical film 20a having a reflective circular polarizer 10 including a cholesteric liquid crystal layer satisfy the above formula (2), there can be mentioned a method similar to the above-mentioned method for making the reflective circular polarizer including a cholesteric liquid crystal layer satisfy the above formula (1).

[0115] Each component will be described below.

[0116] [Reflective Circular Polarizer] A reflective circular polarizer is a polarizer that transmits right-handed or left-handed circularly polarized light and reflects circularly polarized light having the opposite rotation direction to the transmitted circularly polarized light. An example of a reflective circular polarizer is a reflective circular polarizer having a cholesteric liquid crystal layer. In addition, when the reflective circular polarizer has a cholesteric liquid crystal layer, it may have a support and an alignment film for aligning the liquid crystal compound in the cholesteric liquid crystal layer. In addition, as described above, the reflective circular polarizer may have multiple cholesteric liquid crystal layers, and the multiple cholesteric liquid crystal layers may have different selective reflection center wavelengths.

[0117] [Cholesteric Liquid Crystal Layer] A cholesteric liquid crystal layer refers to a liquid crystal layer in which a liquid crystal compound is cholesterically oriented. Note that cholesteric orientation refers to the orientation of a liquid crystal compound in a cholesteric liquid crystal phase, and a cholesteric liquid crystal layer may be any layer in which the cholesteric orientation is maintained. Typically, a polymerizable liquid crystal compound having a polymerizable group is oriented in a cholesteric liquid crystal phase by adding a chiral agent or the like, and then polymerized and cured by ultraviolet irradiation, heating, or the like to form a layer with no fluidity.

[0118] The cholesteric liquid crystal layer is preferably a layer that has been changed to a state in which its orientation does not change due to an external field, external force, etc. In the cholesteric liquid crystal layer, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained within the layer, and the liquid crystal compound in the cholesteric liquid crystal layer may no longer exhibit liquid crystallinity. For example, a polymerizable liquid crystal compound may be polymerized by a curing reaction and no longer have liquid crystallinity.

[0119] The central wavelength λ of the reflected light of the cholesteric liquid crystal layer depends on the helical pitch number P (= helical period) of the helical structure in the cholesteric liquid crystal phase, and is expressed by the relationship λ = n × P, where n is the average refractive index of the cholesteric liquid crystal layer. The central wavelength of the reflected light of the cholesteric liquid crystal layer can be determined as follows. When the transmission spectrum of the cholesteric liquid crystal layer is measured from the normal direction of the cholesteric liquid crystal layer using a spectrophotometer, a spectrum having a peak where the transmittance decreases in a region near the central wavelength of the reflected light is obtained. In other words, a reflection spectrum having a peak where the reflectance increases in a region near the central wavelength of the reflected light is obtained. Of these, the value of the shorter wavelength of the two wavelengths at which the transmittance is half the value of the largest peak is determined as λ. １ (nm), and the wavelength on the long wavelength side is λ ２ (nm), the central wavelength λ of the reflected light is calculated by the following formula: λ = (λ １ +λ ２ ) / 2

[0120] In addition, λ obtained by the above procedure １ When the reflection spectrum of the outermost cholesteric liquid crystal layer is determined in the same manner, λ is the half-value wavelength on the short wavelength side. ２ When the reflection spectrum of the outermost cholesteric liquid crystal layer is determined in the same manner, it becomes λmax, which is the half-value wavelength on the long wavelength side.

[0121] The helical pitch of a cholesteric liquid crystal phase varies depending on the type and concentration of the chiral agent used together with the liquid crystal compound, and a cholesteric liquid crystal phase with the desired pitch can be obtained by adjusting one or more of the above. Regarding the method for measuring the helical direction and helical pitch, the methods described in "Introduction to Liquid Crystal Chemistry Experiments," edited by the Japanese Liquid Crystal Society, published by Sigma Publishing in 2007, page 46, and "Liquid Crystal Handbook," published by the Liquid Crystal Handbook Editorial Committee, Maruzen, page 196, can be used. Specifically, the helical pitch number P is measured using the method described in the examples.

[0122] The thickness of the cholesteric liquid crystal layer may be adjusted appropriately to a thickness that can sufficiently reflect polarized light that should be reflected and can sufficiently transmit polarized light that should be transmitted.

[0123] The liquid crystal compound contained in the cholesteric liquid crystal layer is not particularly limited, but examples thereof include rod-shaped liquid crystal compounds and discotic liquid crystal compounds.

[0124] The rod-shaped liquid crystal compound may be a known rod-shaped liquid crystal compound, and preferably a polymerizable rod-shaped liquid crystal compound having a polymerizable group. Examples of the rod-shaped liquid crystal compound are not particularly limited, but include those described in claim 1 of JP-A-11-513019 or paragraphs

[0026] to

[0098] of JP-A-2005-289980.

[0125] It is also preferable to use a rod-shaped liquid crystal compound having a high refractive index anisotropy Δn (high Δn), where Δn is the difference between the refractive index in the slow axis direction and the refractive index in the fast axis direction.

[0126] When a rod-shaped liquid crystal compound has a high Δn characteristic, a high reflectance can be obtained even if the number of turns of the helical structure of the cholesteric liquid crystal phase is small, and therefore, desired reflection characteristics can be obtained even with a thin film thickness. By reducing the film thickness, the magnitude of the phase difference generated for incident light obliquely inclined from the normal direction of the cholesteric liquid crystal layer can be reduced, and as a result, ghosts can be further reduced.

[0127] The liquid crystal compound having a high refractive index anisotropy Δn is not particularly limited, but the compounds exemplified in paragraphs

[0014] to

[0029] of WO 2019 / 182129 and the compounds represented by the following general formula (I) can be preferably used.

[0128]

[0129] In general formula (I), P １ and P ２ each independently represents a hydrogen atom, —CN, —NCS, or a polymerizable group.

[0130] In general formula (I), Sp １ and Sp ２ each independently represents a single bond or a divalent linking group. １ and Sp ２does not represent a divalent linking group containing at least one group selected from the group consisting of an aromatic hydrocarbon ring group, an aromatic heterocyclic group, and an aliphatic hydrocarbon ring group.

[0131] In general formula (I), Z １ , Z ２ and Z ３ each independently represents a single bond, —O—, —S—, —CHR—, —CHRCHR—, —OCHR—, —CHRO—, —SO—, or —SO ２ -, -COO-, -OCO-, -CO-S-, -S-CO-, -O-CO-O-, -CO-NR-, -NR-CO-, -SCHR-, -CHRS-, -SO-CHR-, -CHR-SO-, -SO ２ -CHR-, -CHR-SO ２ -, -CF ２ O-, -OCF ２ -, -CF ２ S-, -SCF ２ -, -OCHRCHRO-, -SCHRCHRS-, -SO-CHRCHR-SO-, -SO ２ -CHRCHR-SO ２ -, -CH=CH-COO-, -CH=CH-OCO-, -COO-CH=CH-, -OCO-CH=CH-, -COO-CHRCHR-, -OCO-CHRCHR-, -CHRCHR-COO-, -CHRCHR-OCO-, -COO-CHR-, -OCO-CHR-, -CHR-COO-, -CHR-OCO-, -CR=CR-, -CR=N-, -N=CR-, -N=N-, -CR=N-N=CR-, -CF=CF- or C≡C-. R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. When multiple Rs are present, they may be the same or different. Z １ and Z ２ When there are a plurality of Z, they may be the same or different. ３ may be the same or different, provided that Sp ２ Z connected to ３ represents a single bond.

[0132] In general formula (I), １ and X ２Each of X independently represents a single bond or -S-. １ and X ２ may be the same or different. １ and multiple Xs ２ At least one of these represents —S—.

[0133] In formula (I), k represents an integer of 2 to 4.

[0134] In formula (I), m and n each independently represent an integer of 0 to 3. A plurality of m's may be the same or different.

[0135] In general formula (I), A １ , A ２ , A ３ and A ４ each independently represents a group represented by any one of the following general formulae (B-1) to (B-7), or a group formed by linking two to three groups represented by any one of the following general formulae (B-1) to (B-7). ２ and A ３ may be the same or different. １ and A ４ When there are a plurality of each, they may be the same or different.

[0136]

[0137] In general formulas (B-1) to (B-7), W １ ~W １８ are each independently CR １ or N, R １ represents a hydrogen atom or the following substituent L.

[0138] In general formulas (B-1) to (B-7), Y １ ~Y ６ are each independently NR ２ , O or S, R ２ represents a hydrogen atom or the following substituent L.

[0139] In general formulas (B-1) to (B-7), G １ ~G ４ are each independently CR３ R ４ , N.R. ５ , O or S, R ３ ~R ５ each independently represents a hydrogen atom or a substituent L described below.

[0140] In general formulas (B-1) to (B-7), M １ and M ２ are each independently CR ６ or N, R ６ represents a hydrogen atom or the following substituent L.

[0141] In the general formulae (B-1) to (B-7), * represents a bonding position.

[0142] The substituent L is an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkylamino group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an alkanoyl group having 1 to 10 carbon atoms, an alkanoyloxy group having 1 to 10 carbon atoms, an alkanoylamino group having 1 to 10 carbon atoms, an alkanoylthio group having 1 to 10 carbon atoms, an alkyloxycarbonyl group having 2 to 10 carbon atoms, an alkylaminocarbonyl group having 2 to 10 carbon atoms, an alkylthiocarbonyl group having 2 to 10 carbon atoms, a hydroxy group, an amino group, a mercapto group, a carboxy group, a sulfo group, an amido group, a cyano group, a nitro group, a halogen atom, or a polymerizable group, provided that the above groups described as the substituent L are not —CH ２ When the group has -, -CH contained in the above group ２ Groups in which at least one of - is replaced by -O-, -CO-, -CH=CH- or -C≡C- are also included in the substituent L. Furthermore, when the above groups described as the substituent L have a hydrogen atom, groups in which at least one of the hydrogen atoms contained in the above groups is replaced by at least one selected from the group consisting of a fluorine atom and a polymerizable group are also included in the substituent L.

[0143] In order to further reduce ghosting, the refractive index anisotropy Δn of the liquid crystal compound ５５０ The refractive index anisotropy at a wavelength of 550 nm is preferably 0.12 or more, more preferably 0.16 or more, even more preferably 0.20 or more, and most preferably 0.25 or more.５５０ The upper limit of the refractive index anisotropy at a wavelength of 550 nm is preferably 0.90 or less, more preferably 0.70 or less, and most preferably 0.50 or less, from the viewpoint of suppressing interfacial reflection.

[0144] The discotic liquid crystal compound may be a known discotic liquid crystal compound, preferably a polymerizable discotic liquid crystal compound having a polymerizable group. Examples of the discotic liquid crystal compound are not particularly limited, but for example, the discotic liquid crystal compounds described in paragraphs

[0020] to

[0122] of JP-A No. 2007-108732 can be suitably used.

[0145] It is also preferable to use a discotic liquid crystal compound having a high refractive index anisotropy Δn (high Δn), where Δn is the difference between the refractive index in the slow axis direction and the refractive index in the fast axis direction.

[0146] When a discotic liquid crystal compound has a high Δn characteristic, a high reflectance can be obtained even if the number of turns of the helical structure of the cholesteric liquid crystal phase is small, and therefore, desired reflection characteristics can be obtained even with a thin film thickness. Thinning the film can reduce the magnitude of the phase difference that occurs with respect to incident light that is obliquely inclined from the normal direction of the cholesteric liquid crystal layer, thereby further reducing ghosting. As a discotic liquid crystal compound with a high Δn, for example, the discotic liquid crystal compounds described in paragraphs

[0012] to

[0108] of JP-A-2010-244038 can be suitably used.

[0147] In order to further reduce ghosts, the refractive index anisotropy Δn550 (refractive index anisotropy at a wavelength of 550 nm) of the liquid crystal compound is preferably 0.12 or more, more preferably 0.16 or more, even more preferably 0.20 or more, and most preferably 0.25 or more. ５５０ The upper limit of the refractive index anisotropy at a wavelength of 550 nm is preferably 0.90 or less, more preferably 0.70 or less, and most preferably 0.50 or less, from the viewpoint of suppressing interfacial reflection.

[0148] The polymerizable group that the liquid crystal compound may have is not particularly limited, but is preferably a functional group capable of undergoing an addition polymerization reaction, more preferably a polymerizable ethylenically unsaturated group or a ring-polymerizable group, and even more preferably a (meth)acryloyl group, a vinyl group, a styryl group, or an allyl group.

[0149] The number of polymerizable groups that the liquid crystal compound has is not particularly limited, but is preferably 2 or more. The upper limit is not particularly limited, but is often 10 or less.

[0150] The cholesteric liquid crystal layer is preferably a layer formed using a liquid crystal compound having a polymerizable group, and more preferably a layer formed by fixing the alignment state of a liquid crystal compound having a polymerizable group.

[0151] The "fixed" state is a state in which the alignment of the liquid crystal compound is maintained, which is the most typical and preferred embodiment. However, it is not limited thereto, and specifically, it is more preferred that the layer has no fluidity and the alignment state is not changed by an external field or external force, and the fixed alignment state can be stably maintained, usually in a temperature range of 0 to 50°C, or under more severe conditions in a temperature range of −30 to 70°C.

[0152] The pitch of the cholesteric liquid crystal phase may also vary in the film thickness direction. The state in which the pitch varies in the film thickness direction is called a pitch gradient, and a layer in which the pitch varies in the film thickness direction is called a pitch gradient layer. The pitch gradient layer can be produced by a known method, for example, by referring to JP 2020-060627 A. In the pitch gradient layer, the helical pitch varies in the film thickness direction, and therefore light in multiple wavelength ranges can be reflected.

[0153] When forming a cholesteric liquid crystal layer, it is preferable to apply a liquid crystal composition to the surface on which the cholesteric liquid crystal layer is to be formed, align the liquid crystal compound in a cholesteric liquid crystal phase, and then harden the liquid crystal compound to form a cholesteric liquid crystal layer. That is, when forming a cholesteric liquid crystal layer on an alignment film, it is preferable to apply a liquid crystal composition to the alignment film, align the liquid crystal compound in a cholesteric liquid crystal phase, and then harden the liquid crystal compound to form a cholesteric liquid crystal layer with the cholesteric liquid crystal phase fixed.

[0154] The liquid crystal composition can be applied by any known method capable of uniformly applying a liquid to a sheet-like material, such as printing methods such as ink jet printing and scroll printing, as well as spin coating, bar coating and spray coating.

[0155] The applied liquid crystal composition is dried and / or heated as necessary, and then cured to form a cholesteric liquid crystal layer. During this drying and / or heating process, the liquid crystal compounds in the liquid crystal composition may be oriented in a cholesteric liquid crystal phase. When heating is performed, the heating temperature is preferably 200° C. or lower, more preferably 80° C. or higher and 130° C. or lower.

[0156] The aligned liquid crystal compound is further polymerized as needed. The polymerization may be either thermal polymerization or photopolymerization by light irradiation, but photopolymerization is preferred. The light irradiation is preferably performed using ultraviolet light. The irradiation energy is 20 mJ / cm. ２ ~50 J / cm ２ is preferred, and 50 to 1500 mJ / cm ２ In order to promote the photopolymerization reaction, the irradiation may be carried out under heated conditions or in a nitrogen atmosphere. The wavelength of the ultraviolet light to be irradiated is preferably 250 to 430 nm.

[0157] The support used to form the cholesteric liquid crystal layer is not particularly limited, but 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, polyacrylate, and polymethacrylate are preferred. Commercially available cellulose acetate films (e.g., "TD80U" and "Z-TAC" manufactured by Fujifilm Corporation) can also be used.

[0158] When the support is a temporary support, a support having high tear strength is preferred from the viewpoint of preventing breakage during peeling, and for example, polycarbonate and polyester films are preferred.

[0159] In addition, the support preferably has a small retardation from the viewpoint of suppressing adverse effects on the polarization degree of transmitted light and reflected light. Specifically, the magnitude of Re is preferably 10 nm or less, and the absolute value of the magnitude of Rth is preferably 50 nm or less. Furthermore, even if the support is used as the above-mentioned temporary support, it is preferable that the retardation of the temporary support is small in order to perform quality inspection of the reflective circular polarizer and / or the laminated optical film.

[0160] [Half Mirror] The half mirror used in the present invention is a conventionally known half mirror that transmits approximately half of the incident light and reflects the remaining half. The transmittance of the half mirror is preferably 50±30%, more preferably 50±10%, and most preferably 50%. The half mirror has a structure in which a reflective layer made of a metal such as silver or aluminum is formed on a substrate made of a transparent resin such as polyethylene terephthalate (PET), cycloolefin polymer (COP), or polymethyl methacrylate (PMMA), or glass. The reflective layer made of a metal such as silver or aluminum is formed on the surface of the substrate by vapor deposition or the like. The thickness of the reflective layer is preferably 1 to 20 nm, more preferably 2 to 10 nm, and even more preferably 3 to 6 nm. Furthermore, it is preferable that the substrate does not have a phase difference. From this perspective, the substrate of the half mirror is preferably cycloolefin polymer (COP), polymethyl methacrylate (PMMA), or glass.

[0161] [Retardation Layer] The retardation layer used in the present invention is a retardation plate having a function of converting linearly polarized light of a certain wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). More specifically, it is a plate exhibiting an in-plane retardation Re of λ / 4 (or an odd multiple thereof) at a predetermined wavelength λ nm.

[0162] The in-plane retardation (Re(550)) of the retardation layer at a wavelength of 550 nm may have an error of about 25 nm around the ideal value (137.5 nm), and is preferably, for example, 110 to 160 nm, more preferably 120 to 150 nm.

[0163] The retardation layer used in the present invention preferably exhibits the characteristics of a λ / 4 plate at each wavelength across the visible light range, and such a retardation layer is particularly called a broadband λ / 4 plate.The broadband λ / 4 plate preferably has an in-plane retardation (Re(λ)) at a wavelength of λ nm that satisfies the following formulas (A) and (B): Formula (A) Re(450) / Re(550)<1.00 Formula (B) Re(650) / Re(550)≧1.00Re(450) represents the in-plane retardation of the λ / 4 plate at a wavelength of 450 nm, Re(550) represents the in-plane retardation of the λ / 4 plate at a wavelength of 550 nm, and Re(650) represents the in-plane retardation of the λ / 4 plate at a wavelength of 650 nm.

[0164] The retardation layer used in the present invention may be composed of a single retardation layer, or may be composed of two or more retardation layers laminated by lamination, sequential formation, or other methods. The retardation layer referred to here is a layer that exhibits optical anisotropy. Examples of the retardation layer include layers in which at least two of nx, ny, and nz are different. Note that nx represents the refractive index in the direction perpendicular to the thickness direction of the retardation layer (in-plane direction) and in the direction that gives the maximum refractive index. ny represents the refractive index in the in-plane direction of the retardation layer and in the direction perpendicular to the nx direction. nz represents the refractive index in the thickness direction of the retardation layer.

[0165] The material constituting the retardation layer used in the present invention is not particularly limited, and examples thereof include liquid crystal compounds and polymers. A liquid crystal compound can form a retardation layer by orienting a liquid crystal material to exhibit refractive index anisotropy. A polymer can form a retardation layer by exhibiting refractive index anisotropy through stretching a polymer film obtained by casting, coating, or the like. The retardation layer used in the present invention is preferably a layer formed using a liquid crystal compound in terms of thinness, and more preferably a layer formed using a liquid crystal compound having a polymerizable group.

[0166] The type of liquid crystal compound is not particularly limited. Generally, liquid crystal compounds can be classified into rod-shaped (rod-shaped liquid crystal compounds) and discotic (discotic liquid crystal compounds) based on their shape. Liquid crystal compounds can also be classified into low-molecular-weight and high-molecular-weight compounds. High-molecular-weight compounds generally refer to compounds with a degree of polymerization of 100 or more (see "Polymer Physics: Phase Transition Dynamics," by Masao Doi, p. 2, Iwanami Shoten, 1992). In the present invention, any liquid crystal compound can be used, but rod-shaped or discotic liquid crystal compounds are preferred, and rod-shaped liquid crystal compounds are more preferred. Two or more rod-shaped liquid crystal compounds, two or more discotic liquid crystal compounds, or a mixture of rod-shaped and discotic liquid crystal compounds may also be used.

[0167] Examples of the rod-shaped liquid crystal compound include the liquid crystal compounds described in claim 1 of JP-A-11-513019 and paragraphs 0026 to 0098 of JP-A-2005-289980.

[0168] Examples of discotic liquid crystal compounds include the liquid crystal compounds described in paragraphs 0020 to 0067 of JP-A No. 2007-108732 and paragraphs 0013 to 0108 of JP-A No. 2010-244038.

[0169] The liquid crystal compound preferably has a polymerizable group. That is, the liquid crystal compound is preferably a polymerizable liquid crystal compound. When the liquid crystal compound has a polymerizable group, the alignment state of the liquid crystal compound can be easily fixed by a curing treatment described later.

[0170] The type of polymerizable group possessed by the liquid crystal compound is not particularly limited, and is preferably a functional group capable of undergoing an addition polymerization reaction, more preferably a polymerizable ethylenically unsaturated group or a ring-polymerizable group, and even more preferably a (meth)acryloyl group, a vinyl group, a styryl group, or an allyl group.

[0171] The number of polymerizable groups that the liquid crystal compound has is not particularly limited, but is preferably 2 or more. The upper limit is not particularly limited, but is often 10 or less.

[0172] The liquid crystal compound may be a liquid crystal compound that exhibits either normal wavelength dispersion or reverse wavelength dispersion. When a retardation layer that exhibits the characteristics of a wideband λ / 4 plate as a single film is used, a liquid crystal compound that exhibits reverse wavelength dispersion is preferred, and a liquid crystal compound that has two or more polymerizable groups and exhibits reverse wavelength dispersion is more preferred.

[0173] In this specification, the term "liquid crystal compound exhibiting reverse wavelength dispersion" refers to a compound that satisfies the relationship between the above-mentioned formulas (A) and (B) when the in-plane retardation (Re) value at a specific wavelength (visible light range) of an optically anisotropic layer prepared using this compound is measured.

[0174] In addition, in this specification, the term "liquid crystal compound showing forward wavelength dispersion" refers to a compound that satisfies the relationships of the following formulas (C) and (D) when the in-plane retardation (Re) value at a specific wavelength (visible light range) of a retardation layer prepared using this compound is measured. Formula (C) Re(450) / Re(550)≧1.00 Formula (D) Re(650) / Re(550)<1.00

[0175] As described above, the retardation layer is preferably a layer formed using a liquid crystal compound having a polymerizable group, and more preferably a layer formed by fixing the alignment state of a liquid crystal compound having a polymerizable group.

[0176] The orientation state that a liquid crystal compound having a polymerizable group can assume is not particularly limited, and examples thereof include homogeneous orientation, homeotropic orientation, twisted orientation, cholesteric orientation, hybrid orientation (an orientation in which the tilt angle of the liquid crystal compound changes continuously from one surface to the other), and tilted orientation (an orientation in which the tilt angle of the liquid crystal compound is constant from one surface to the other). Twisted orientation refers to an orientation state in which the liquid crystal compound is twisted around the thickness direction as the axis of rotation, and when the liquid crystal compound is twisted and has a predetermined tilt angle (tilt angle greater than 0°), it corresponds to twisted hybrid orientation. In this specification, twisted orientation refers to an embodiment in which the twist angle of the liquid crystal compound is less than 360°, and cholesteric orientation refers to an embodiment in which the twist angle of the liquid crystal compound is 360° or more.

[0177] The "fixed" state is a state in which the alignment of the liquid crystal compound is maintained, which is the most typical and preferred embodiment. However, it is not limited thereto, and specifically, it is more preferred that the layer has no fluidity and the alignment state is not changed by an external field or external force, and the fixed alignment state can be stably maintained, usually in a temperature range of 0 to 50°C, or under more severe conditions in a temperature range of −30 to 70°C.

[0178] The retardation layer formed using a liquid crystal compound may have a plurality of regions in the thickness direction where the liquid crystal compound has different alignment states. For example, the retardation layer may have a region in which the liquid crystal compound is fixed in a homogeneously aligned state and a region in which the liquid crystal compound is fixed in a twisted aligned state, along the thickness direction.

[0179] The thickness of the retardation layer is not particularly limited, but is preferably 0.1 to 10.0 μm, more preferably 0.5 to 5.0 μm.

[0180] Specific examples of the configuration of a wideband λ / 4 plate include those configured with a single-layer retardation layer, such as retardation layers using liquid crystal compounds exhibiting reverse wavelength dispersion as disclosed in International Publication WO2019 / 160016, JP2020-173460, and International Publication WO2021 / 157694, and retardation layers having multiple regions along the thickness direction in which the alignment states of liquid crystal compounds are different as disclosed in International Publication WO2022 / 030308 and JP2022-184691. Examples of a laminate of two or more retardation layers include a configuration that combines a λ / 4 retardation layer and a λ / 2 retardation layer as disclosed in JP-A-2001-108825, JP-A-2001-091741, International Publication WO2013 / 137464, etc., and a configuration that combines a retardation layer having a twisted orientation with another retardation layer as disclosed in JP-A-2001-021720, JP-A-2014-209219, International Publication WO2022 / 255105, etc. In addition, in order to compensate for the phase difference change with respect to obliquely incident light, other retardation layers such as a positive C plate and a negative C plate may be further added.

[0181] The retardation layer may include a support, an alignment layer, etc., and the support and the alignment layer may be temporary supports. As the support for the retardation layer, the same support as the support used when forming the cholesteric liquid crystal layer can be used.

[0182] In addition, 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 retardation layer used in the laminated optical film is preferably transparent to near-infrared light.

[0183] [Absorbing Linear Polarizer] As the absorbing linear polarizer, a known absorbing linear polarizer can be used. For example, it may be a polarizer in which a dichroic substance is dyed onto polyvinyl alcohol or other polymer resin and then oriented by stretching, or a polarizer in which a dichroic substance is oriented by utilizing the orientation of a liquid crystal compound.

[0184] The thickness of the absorbing linear polarizer is preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less. When the absorbing linear polarizer is thin, cracks and breakage of the film can be prevented when the laminated optical film is stretched or molded.

[0185] The single-plate transmittance of the absorptive linear 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 linear polarizer are measured using an automatic polarizing film measuring device: VAP-7070 (manufactured by JASCO Corporation).

[0186] The absorbing linear polarizer is also preferably a light-absorbing anisotropic layer containing a liquid crystal compound and a dichroic substance. A linear polarizer containing a liquid crystal compound and a dichroic substance is preferred because it can be made thin and is less likely to crack or break even when stretched, molded, etc. The thickness of the light-absorbing anisotropic layer is not particularly limited, but is preferably 0.1 to 8 μm, more preferably 0.3 to 5 μm, from the viewpoint of thinning.

[0187] An absorbing linear polarizer containing a liquid crystal compound and a dichroic material can be produced, for example, by referring to JP 2020-023153 A. From the viewpoint of improving the polarization degree of the linear polarizer, the light-absorbing anisotropic layer preferably has a degree of orientation of the dichroic material of 0.95 or more, more preferably 0.97 or more.

[0188] The liquid crystal compound contained in the composition for forming the optically absorptive anisotropic layer is preferably a liquid crystal compound that does not exhibit dichroism in the visible region.

[0189] The liquid crystal compound can be either a low molecular weight liquid crystal compound or a high molecular weight liquid crystal compound. Here, "low molecular weight liquid crystal compound" refers to a liquid crystal compound that does not have a repeating unit in its chemical structure. "High molecular weight liquid crystal compound" refers to a liquid crystal compound that has a repeating unit in its chemical structure.

[0190] Examples of the polymeric liquid crystal compound include the thermotropic liquid crystal polymer described in JP 2011-237513 A. The polymeric liquid crystal compound preferably has a crosslinkable group at its terminal. Examples of the crosslinkable group at the terminal of the polymeric liquid crystal compound include an acryloyl group and a methacryloyl group.

[0191] The liquid crystal compounds may be used alone or in combination of two or more. It is also preferable to use a high molecular weight liquid crystal compound and a low molecular weight liquid crystal compound in combination.

[0192] The content of the liquid crystal compound is preferably 25 to 2,000 parts by mass, more preferably 33 to 1,000 parts by mass, and even more preferably 50 to 500 parts by mass, relative to 100 parts by mass of the content of the dichroic substance in the composition. When the content of the liquid crystal compound is within the above range, the degree of orientation of the polarizer is further improved.

[0193] The dichroic substance contained in the composition for forming an optically absorptive anisotropic layer for forming an optically absorptive anisotropic layer is not particularly limited, and examples thereof include visible light absorbing substances (dichroic dyes), ultraviolet absorbing substances, infrared absorbing substances, nonlinear optical substances, and carbon nanotubes, and any conventionally known dichroic substance (dichroic dye) can be used.

[0194] In the present invention, two or more dichroic substances may be used in combination. For example, from the viewpoint of obtaining a high degree of polarization over a wider wavelength range, it is preferable to use in combination at least one dichroic substance having a maximum absorption wavelength in the wavelength range of 370 to 550 nm and at least one dichroic substance having a maximum absorption wavelength in the wavelength range of 500 to 700 nm.

[0195] When the absorbing linear polarizer has a light-absorbing anisotropic layer containing a liquid crystal compound and a dichroic substance, the absorbing linear polarizer may include a support, an alignment layer, etc., and the support and the alignment layer may be temporary supports.

[0196] When a temporary support is used, the optically absorbing anisotropic layer is transferred to another laminate, and then the temporary support is peeled off and removed, thereby making it possible to thin the laminate (laminated optical film) and further eliminating the adverse effect that the retardation of the temporary support has on the polarization degree of transmitted light, which is preferable.

[0197] The type of support is not particularly limited, but it is preferably transparent to visible light. For example, the same support as that used when forming the cholesteric liquid crystal layer can be used.

[0198] Furthermore, in order to minimize the effects 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 absorbing linear polarizer used in the laminated optical film is preferably transparent to near-infrared light.

[0199] [Reflective Linear Polarizer] A reflective linear polarizer is a linear polarizer that transmits linearly polarized light in a certain direction (transmission axis direction) and reflects linearly polarized light in a direction perpendicular to the linearly polarized light (reflection axis direction). The reflective linear polarizer is preferably one that selectively transmits linearly polarized light in a certain direction in the wavelength range of visible light, and known reflective linear polarizers can be used.

[0200] An example of a reflective linear polarizer is a film obtained by stretching a dielectric multilayer film, as described in JP 2011-053705 A. Commercially available reflective linear polarizers can also be suitably used. An example of a commercially available reflective linear polarizer is a reflective linear polarizer (product name: APF) manufactured by 3M.

[0201] Another example of the reflective linear polarizer is a wire grid polarizer. Known wire grid polarizers can be used, and commercially available products may also be used.

[0202] [Image Display Panel] The image display panel used in the present invention can be a known image display panel. Examples include image display panels in which self-luminous fine light emitters, such as organic electroluminescence display devices, LED (Light Emitting Diode) display devices, and micro-LED display devices, are arranged on a transparent substrate. These self-luminous display devices typically have a (circular) polarizing plate attached to the display surface to prevent reflection on the display surface. Therefore, the emitted light is polarized. Another example of an image display panel is a liquid crystal display device. Liquid crystal display devices also have a polarizing plate on their surface, so the emitted light is polarized. In the following description, organic electroluminescence display devices are also referred to as OLEDs. OLED is an abbreviation for "organic light emitting diode."

[0203] [Other Functional Layers] The reflective circular polarizer, laminated optical film, and virtual reality display device of the present invention may have other functional layers.

[0204] Furthermore, in order to minimize the influence on various sensors that use near-infrared light as a light source, such as eye tracking, facial expression recognition, and iris authentication, which are incorporated into optical systems such as virtual reality display devices and electronic viewfinders, it is preferable that the other functional layers be transparent to near-infrared light.

[0205] [Adhesive Layer] As the adhesive layer for adhering each layer, known adhesives and pressure sensitive adhesives can be used as appropriate.

[0206] Any commercially available adhesive can be used as the adhesive layer, and from the viewpoint of thinning and reducing the surface roughness Ra, the thickness is preferably 25 μm or less, more preferably 15 μm or less, and most preferably 6 μm or less. Furthermore, it is preferable that the adhesive is one that is less likely to outgas. In particular, when stretching and molding are performed, vacuum processes and heating processes may be used, and it is preferable that the adhesive does not outgas even under these conditions.

[0207] Any commercially available adhesive may be used for the adhesive layer, such as an epoxy resin adhesive or an acrylic resin adhesive.

[0208] From the viewpoint of thinning and reducing the surface roughness Ra, the adhesive preferably has a thickness of 25 μm or less, more preferably 5 μm or less, and most preferably 1 μm or less. Furthermore, from the viewpoint of thinning the adhesive layer and applying the adhesive to the adherend in a uniform thickness, the adhesive preferably has a viscosity of 300 cP or less, more preferably 100 cP or less.

[0209] Furthermore, when the adherend has surface irregularities, the pressure-sensitive adhesive and / or adhesive can be selected to have an appropriate viscoelasticity or thickness so as to embed the surface irregularities of the layer to be adhered, from the viewpoint of reducing the surface roughness Ra. From the viewpoint of embedding the surface irregularities, the pressure-sensitive adhesive and / or adhesive preferably has a viscosity of 50 cP or more. Furthermore, the thickness is preferably greater than the height of the surface irregularities.

[0210] One method for adjusting the viscosity of an adhesive is to use an adhesive containing a solvent. In this case, the viscosity of the adhesive can be adjusted by adjusting the ratio of the solvent. Furthermore, by applying the adhesive to an adherend and then drying the solvent, the thickness of the adhesive can be further reduced.

[0211] From the viewpoint of reducing reflection at the interface and suppressing the occurrence of ghosts, it is preferable that the difference in refractive index between the adhesive or the adhesive used to attach each layer and the adjacent layer is small. Specifically, the difference in refractive index between the adjacent layers is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.01 or less. In addition, since the retardation layer has birefringence and therefore has different refractive indices in the fast axis direction and the slow axis direction, the average refractive index n of the liquid crystal layer is determined by adding the refractive indices in the fast axis direction and the slow axis direction and dividing the sum by 2. ａｖｅ When the refractive index of the adjacent adhesive layer or bonding layer is n ａｖｅ The difference between the refractive index and the refractive index of the adhesive or pressure-sensitive adhesive is preferably 0.075 or less, more preferably 0.05 or less, and even more preferably 0.025 or less. The refractive index of the pressure-sensitive adhesive or adhesive can be adjusted by mixing, for example, titanium oxide fine particles and zirconia fine particles.

[0212] In addition, the retardation layer, the linear reflective polarizer, and the linear absorbing polarizer may have anisotropy of the refractive index in the plane, but it is preferable that the difference in refractive index between the adjacent layers is 0.05 or less in all directions in the plane. Therefore, the pressure-sensitive adhesive or adhesive may have anisotropy of the refractive index in the plane.

[0213] 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, the refractive index difference is less noticeable for visible light, suppressing unnecessary reflection. The thickness of the adhesive layer is more preferably 50 nm or less, and even more preferably 30 nm or less. An example of a method for forming an adhesive layer having a thickness of 100 nm or less is vapor deposition of a ceramic adhesive such as silicon oxide (SiOx layer) onto the bonding surface. The bonding surface of the bonding member can be subjected to surface modification treatments such as plasma treatment, corona treatment, and saponification treatment before bonding, and a primer layer can be applied. Furthermore, when there are multiple bonding surfaces, the type and thickness of the adhesive layer can be adjusted for each bonding surface. Specifically, an adhesive layer having a thickness of 100 nm or less can be formed, for example, by the following steps (1) to (3). (1) The layer to be laminated is bonded 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 manufactured by ULVAC (model number ULEYES) 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 bonded together, the temporary support is peeled off. The bonding is preferably performed at a temperature of, for example, 120°C.

[0214] The coating, adhesion or lamination of each layer may be carried out by a roll-to-roll method or a sheet-to-sheet method.

[0215] The roll-to-roll method is preferable from the viewpoints of improving productivity and reducing axial misalignment of each layer.

[0216] On the other hand, the sheet-fed method is preferable in that it is suitable for small-lot, multi-item production and allows the selection of a special adhesive method such as the above-mentioned adhesive layer having a thickness of 100 nm or less.

[0217] Furthermore, examples of methods for applying the adhesive and / or 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.

[0218] [Light Interference Layer] The light interference layer may be formed of a single light interference layer, or may be formed by laminating two or more light interference layers by a method such as laminating or sequentially forming.

[0219] Materials that can be used to form the optical interference layer include a hard coat material crosslinked from a monomer, a photo-alignment film, and a C-plate made of a liquid crystal material. Of these, a photo-alignment film is more preferred because it also plays a role in aligning liquid crystals when a retardation layer is formed thereon using a liquid crystal material. Furthermore, a C-plate is more preferred because it also plays a role in adjusting optical compensation. A positive C-plate is even more preferred. Here, 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, for example, in JP 2017-187732 A, JP 2016-053709 A, and JP 2015-200861 A.

[0220] <Material for Photo-Alignment Film> As the optical interference layer, it is also a preferred embodiment to use a so-called photo-alignment film (photo-alignment layer) obtained by irradiating a photo-alignable material with polarized or non-polarized light to form an alignment layer. It is preferable to impart an alignment control force to the photo-alignment film by a process of irradiating polarized light from a vertical or oblique direction, or a process of irradiating non-polarized light from an oblique direction.

[0221] The use of a photo-alignment film allows specific liquid crystal compounds to be horizontally aligned with excellent symmetry. Therefore, a retardation layer positive A plate formed using a photo-alignment film is useful for optical compensation in liquid crystal displays that do not require a pre-tilt angle of the driving liquid crystal, such as in-place switching (IPS) mode liquid crystal displays.

[0222] Examples of photo-alignment materials used in the photo-alignment film include those described in JP-A-2006-285197, JP-A-2007-076839, JP-A-2007-138138, JP-A-2007-094071, JP-A-2007-121721, JP-A-2007-140465, and JP-A-2007-156439. Azo compounds described in JP-A Nos. 2007-133184, 2009-109831, 3883848, and 4151746, aromatic ester compounds described in JP-A No. 2002-229039, and photo-alignable units described in JP-A Nos. 2002-265541 and 2002-317013 Maleimide and / or alkenyl-substituted nadimide compounds, photocrosslinkable silane derivatives described in Japanese Patent Nos. 4205195 and 4205198, photocrosslinkable polyimides, polyamides, or esters described in JP-T-2003-520878, JP-T-2004-529220, and JP-T-4162850, photodimerizable compounds described in JP-A-9-118717, JP-A-10-506420, JP-A-2003-505561, WO 2010 / 150748, JP-A-2013-177561, and JP-A-2014-012823, in particular cinnamate compounds, chalcone compounds, and coumarin compounds. Particularly preferred examples include azo compounds, photocrosslinkable polyimides, polyamides, esters, cinnamate compounds, and chalcone compounds.

[0223] <Material for interlayer photo-alignment film> The optical interference layer preferably contains a material for an interlayer photo-alignment film. This allows liquid crystal alignment when a liquid crystal material is applied onto the optical interference layer, and a structure in which the optical interference layer and the reflective circular polarizer are adjacent to each other can be formed. As the material for the interlayer photo-alignment film, the photo-alignable polymer described in JP 2021-143336 A can be used.

[0224] The material for the interlayer photo-alignment film is preferably a compound having a cinnamoyl group. The cinnamoyl compound is preferably contained between the optical interference layer (preferably a C-plate) and the reflective circular polarizer. That is, the cinnamoyl compound is preferably contained in a region near the boundary between the optical interference layer (preferably a C-plate) and the reflective circular polarizer.

[0225] [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. For details of a method for producing a positive C plate, see, for example, JP-A-2017-187732, JP-A-2016-053709, and JP-A-2015-200861.

[0226] 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 may be disposed at any position in the laminated optical film, and a plurality of positive C plates may be disposed.

[0227] 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 Rth. In this case, when light is incident on the retardation layer from an oblique direction, the polarization state of the transmitted light may change due to the action of Rth, 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 further suppress changes in the polarization state of obliquely incident light and further suppress a decrease in the degree of polarization of the transmitted light, thereby further suppressing ghosting. According to the inventors' studies, the positive C plate is preferably disposed between the lens (support) and the retardation layer, and may be disposed between the retardation layer and a reflective linear polarizer, or may be disposed elsewhere. In this case, the Re(550) of the positive C plate is preferably approximately 10 nm or less, and the Rth(550) is preferably -90 to -40 nm.

[0228] [Antireflection Layer] The laminated optical film of the present invention preferably has an antireflection layer on its surface. The laminated optical film of the present invention has the function of reflecting specific circularly polarized light and transmitting circularly polarized light of the opposite direction. However, the reflection on the surface of the laminated optical film generally includes the reflection of unintended polarized light, which may reduce the polarization degree of the transmitted light. Therefore, it is preferable that the laminated optical film has an antireflection layer on its surface. The antireflection layer may be provided on only one surface of the laminated optical film, or on both surfaces.

[0229] The type of antireflection layer is not particularly limited, but from the viewpoint of further reducing the reflectance, a moth-eye film or an AR (anti-reflective) film is preferred. Known moth-eye films and AR films can be used.

[0230] Furthermore, when the laminated optical film is stretched or molded, a moth-eye film is preferred because it can maintain high antireflection performance even if the film thickness changes due to stretching. Furthermore, when the antireflection layer includes a support and is stretched, molded, etc., the peak temperature of the glass transition temperature Tg of the support is preferably 170°C or less, more preferably 130°C or less, from the viewpoint of facilitating stretching, molding, etc. Specifically, for example, a PMMA film is preferred.

[0231] [Direct Coating of Each Layer] It is also preferable that there is no adhesive layer between each layer of the laminated optical film of the present invention. When forming a layer, the adhesive layer can be eliminated by directly coating the layer on an adjacent layer that has already been formed. 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 in-plane directions. For example, a retardation layer containing a liquid crystal compound can be directly coated on a linear polarizer containing a liquid crystal compound and a dichroic material, and the liquid crystal compound in the retardation layer can be continuously aligned at the interface due to the alignment regulating force of the liquid crystal compound in the linear polarizer.

[0232] [Lamination Order of Layers] The laminated optical film of the present invention is composed of a large number of layers, but the order of the steps of laminating these layers is not particularly limited and can be selected arbitrarily.

[0233] For example, when transferring a functional layer from a film consisting of a temporary support and a functional layer, wrinkles and cracks during transfer can be prevented by adjusting the stacking order so that the thickness of the film to which the layer is to be transferred is 10 μm or more.

[0234] Furthermore, from the viewpoint of reducing the surface roughness Ra of the laminated optical film, if another layer is laminated on top of a layer with large surface roughness, the surface roughness may be further amplified, so it is preferable to laminate the layers in order from the layer with the smallest surface roughness Ra.

[0235] The order of lamination can also be selected from the viewpoint of improving the production yield of the laminated optical film and reducing costs.

[0236] 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.

[0237] [Preparation of Coating Solution for Reflective Circular Polarizer]

[0238] <Coating Solution R-1 for Reflective Circular Polarizer> The composition shown below was stirred and dissolved in a container kept at 70° C. to prepare Coating Solution R-1 for Reflective Circular Polarizer, where R represents a coating solution using a rod-like liquid crystal compound.

[0239] -------------------------------------------------- Coating liquid R-1 for reflective circular polarizer -------------------------------------------------- Methyl ethyl ketone 120.9 parts by mass Cyclohexanone 21.3 parts by mass Mixture X of rod-like liquid crystal compounds shown below 100.0 parts by mass Photopolymerization initiator B shown below 1.00 part by mass Chiral agent A shown below 4.18 parts by mass Surfactant S1 shown below 0.1 part by mass

[0240] Mixture X of rod-shaped liquid crystal compounds

[0241] 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 in the wavelength range of 300 to 400 nm was 140 / mol cm.

[0242] Chiral agent A

[0243] Surfactant S1

[0244] Photopolymerization initiator B

[0245] Chiral agent A is a chiral agent whose helical twisting power (HTP) is reduced by light.

[0246] <Reflective circular polarizer coating solutions R-2 and R-3> These were prepared in the same manner as for the reflective circular polarizer coating solution R-1, except that the amount of chiral agent A added was changed as shown in Table 1 below.

[0247] Table 1. Amount of chiral agent in coating solution containing rod-shaped liquid crystal compound

[0248]

[0249] <Coating Solution D-1 for Reflective Circular Polarizer> The composition shown below was stirred and dissolved in a container kept at 50° C. to prepare Coating Solution D-1 for Reflective Circular Polarizer, where D represents a coating solution using a discotic liquid crystal compound.

[0250] -------------------------------------------------- Coating liquid D-1 for reflective circular polarizer -------------------------------------------------- 80 parts by mass of the following discotic liquid crystal compound (A) 20 parts by mass of the following discotic liquid crystal compound (B) 10 parts by mass of the following polymerizable monomer E1 0.3 parts by mass of the following surfactant S2 3 parts by mass of photopolymerization initiator (Irgacure 907, manufactured by BASF) 5.45 parts by mass of the above chiral agent A 290 parts by mass of methyl ethyl ketone 50 parts by mass of cyclohexanone --------------------------------------------------

[0251] Discotic Liquid Crystal Compound (A)

[0252] Discotic Liquid Crystal Compound (B)

[0253] Polymerizable Monomer E1

[0254] Surfactant S2

[0255] <Reflective circular polarizer coating solutions D-2 to D-4> These solutions were prepared in the same manner as for the reflective circular polarizer coating solution D-1, except that the amount of chiral agent A added was changed as shown in Table 2 below.

[0256] Table 2. Amount of chiral agent in coating solution containing discotic liquid crystal compound

[0257]

[0258] <Reflective circular polarizer coating solutions D-5 to D-7> These solutions were prepared in the same manner as for reflective circular polarizer coating solution D-1, except that the amounts of chiral agent A and initiator added were changed as shown in Table 2-2 below.

[0259] Table 2-2. Amount of chiral agent and initiator in coating solution containing discotic liquid crystal compound

[0260]

[0261] <Alignment Layer Forming Coating Liquid PA-1> The composition shown below was stirred and dissolved in a container kept at 60° C. to prepare a photo-alignment layer forming coating liquid PA-1.

[0262] ------------------------------------------------------------------ (Coating liquid PA-1 for forming alignment layer) ------------------------------------------------------------------ Polymer M-PA-1 below: 100.00 parts by mass Photopolymerization initiator C below: 5.00 parts by mass n-Butyl acetate 2625.00 parts by mass ------------------------------------------------------------------

[0263] Polymer M-PA-1

[0264] Photopolymerization initiator C

[0265] [Preparation of Reflective Circular Polarizer 1]

[0266] <Formation of Photo-Alignment Layer>

[0267] The alignment layer forming coating solution PA-1 prepared above was continuously coated onto a 100 μm thick PET film (Cosmoshine A4265, manufactured by Toyobo Co., Ltd.) using a wire bar. The support on which the coating film was formed was dried with hot air at 120°C for 60 seconds. Thereafter, the coating was dried in a low-oxygen atmosphere (100 ppm or less) at 70°C with an illuminance of 100 mW / cm. ２ , irradiation amount 100mJ / cm ２The photo-alignment layer was cured by irradiating it with light from a high-pressure mercury lamp while passing it through a long-pass filter having a transmission band of wavelengths of 340 nm or more. The film thickness measured with an interference film thickness meter OPTM (manufactured by Otsuka Electronics, analyzed by the least squares method) was 80 nm.

[0268] Next, the illuminance is 7 mW / cm ２ , irradiation amount 7.9mJ / cm ２ The film was irradiated from the photo-alignment layer side with polarized UV (wavelength 313 nm). The polarized UV with a wavelength of 313 nm was obtained by passing ultraviolet light emitted from a mercury lamp through a bandpass filter having a transmission band at wavelength 313 nm and a wire grid polarizer. The reflective circular polarizer coating solution R-1 prepared above was applied with a wire bar coater, dried at 110°C for 72 seconds, and after evaporating the solvent, heat-aged at 100°C for 1 minute to obtain a uniform alignment state. Thereafter, the coating film was held at 100°C for 1 minute and irradiated at an illuminance of 80 mW / cm in a low-oxygen atmosphere (100 ppm or less). ２ , irradiation amount 500mJ / cm ２ The coating was cured by irradiating it with light from a metal halide lamp (1000 rpm), forming a cholesteric liquid crystal layer containing a rod-shaped liquid crystal compound. Because the selective reflection center wavelength of this cholesteric liquid crystal layer is in the blue light wavelength range, it is hereinafter also referred to as a first blue light reflective layer (first light reflective layer). Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. The coating thickness was adjusted so that the film thickness of the first blue light reflective layer after curing was 2.6 μm.

[0269] Next, the surface of the first blue light reflective layer was subjected to a discharge of 150 W·min / m ２ After performing a corona treatment at 400°C, the reflective circular polarizer coating solution D-1 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, the coating film was heat-aged at 115°C for 3 minutes to obtain a uniformly oriented state. Thereafter, the coating film was held at 45°C for 1 minute and irradiated with ultraviolet light (300 mJ / cm) using a metal halide lamp in a low-oxygen atmosphere (100 ppm or less). ２) and curing to form a cholesteric liquid crystal layer containing a discotic liquid crystal compound. This cholesteric liquid crystal layer has a selective reflection central wavelength in the wavelength range of blue light, and therefore is hereinafter also referred to as a second blue light reflective layer (second light reflective layer). Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the film thickness of the second blue light reflective layer after curing would be 2.0 μm.

[0270] Next, the reflective circular polarizer coating solution D-2 was applied onto the second blue light-reflecting 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 uniform alignment state. Thereafter, this coating film was held at 45°C for 1 minute and irradiated with ultraviolet light (300 mJ / cm) using a metal halide lamp under a nitrogen atmosphere. ２ ) and cured to form a cholesteric liquid crystal layer containing a discotic liquid crystal compound on the second blue light-reflecting layer. This cholesteric liquid crystal layer has a selective reflection center wavelength in the green light wavelength range, and is therefore hereinafter also referred to as a green light-reflecting layer (third light-reflecting layer). Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the film thickness of the cured green light-reflecting layer would be 2.7 μm.

[0271] Next, the reflective circular polarizer 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. After the solvent was evaporated, the coating film was heated and aged at 100°C for 1 minute to obtain a uniformly oriented state. Thereafter, the coating film was held at 100°C for 1 minute and aged in a low-oxygen atmosphere (100 ppm or less) at an illuminance of 80 mW / cm. ２ , irradiation amount 500mJ / cm ２ A cholesteric liquid crystal layer containing a rod-shaped liquid crystal compound was formed on the green light-reflecting layer by irradiating it with light from a metal halide lamp and curing it. This cholesteric liquid crystal layer has a selective reflection center wavelength in the red light wavelength range, so it is also referred to as a red light-reflecting layer (fourth light-reflecting layer) hereinafter. Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the film thickness of the red light-reflecting layer after curing would be 3.4 μm.

[0272] Next, the surface of the red light reflective layer was subjected to a discharge of 150 W·min / m ２ After a corona treatment was performed at 45°C, the reflective circular polarizer coating solution D-3 was applied to the corona-treated surface using a wire bar coater. The coating film was then dried at 70°C for 2 minutes, and after the solvent was evaporated, the coating film was heat-aged at 115°C for 3 minutes to obtain a uniformly oriented state. Thereafter, the coating film was held at 45°C for 1 minute and irradiated with ultraviolet light (300 mJ / cm) using a metal halide lamp under a nitrogen atmosphere. ２ ) and curing to form a cholesteric liquid crystal layer containing a discotic liquid crystal compound on the red light-reflecting layer. This cholesteric liquid crystal layer has a selective reflection center wavelength in the wavelength range of yellow light, and therefore is hereinafter also referred to as a yellow light-reflecting layer (fifth light-reflecting layer). Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the film thickness of the yellow light-reflecting layer after curing was 3.4 μm.

[0273] The central reflection wavelength and film thickness of each reflective layer of the prepared reflective circular polarizer 1 are shown in Table 3-1. Here, the central reflection wavelength is used to define the characteristics of a light-reflective film having a reflection band using cholesteric liquid crystal, and refers to the midpoint of the spectral band reflected by the film. Specifically, it was obtained by calculating the average value of the wavelengths on the short wavelength side and the long wavelength side that show half-value of the peak reflectance. The central reflection wavelength (the central wavelength of reflected light) was confirmed by creating a film coated with only a single layer. The film thickness was confirmed using an SEM.

[0274] Table 3-1. Characteristics of the light-reflecting layer of a reflective circular polarizer

[0275]

[0276] [Preparation of Reflective Circular Polarizer 2] Reflective circular polarizer 2 was prepared by the same method as that for reflective circular polarizer 1, except that the type of coating liquid and the film thickness of each layer using cholesteric liquid crystal were changed as shown in Table 3-2 below, and the temperature during UV irradiation and the time for which the temperature was maintained before UV irradiation were changed as shown in Table 4 below.

[0277] Table 3-2. Characteristics of the light-reflecting layer of reflective circular polarizer 2

[0278]

[0279] [Preparation of Reflective Circular Polarizers 3 to 6] Reflective circular polarizers 3 to 5 were prepared by the same method as reflective circular polarizer 1, except that the temperature during UV irradiation of each layer and the time for which that temperature was maintained before UV irradiation were changed as shown in Table 4 below. Reflective circular polarizer 6 was prepared by the same method as reflective circular polarizer 2, except that the temperature during UV irradiation of each layer and the time for which that temperature was maintained before UV irradiation were changed as shown in Table 4 below. Here, the second, third, and fifth layers were light-reflecting layers using discotic liquid crystals, and the first and fourth layers were light-reflecting layers using rod-shaped liquid crystals.

[0280] [Preparation of Reflective Circular Polarizer 7] Reflective circular polarizer 7 was prepared by the same method as that for reflective circular polarizer 1, except that the type of coating liquid and the film thickness of each layer using cholesteric liquid crystal were changed as shown in Table 3-3 below, and the temperature during UV irradiation and the time for which the temperature was maintained before UV irradiation were changed as shown in Table 4 below.

[0281] Table 3-3. Characteristics of the light-reflecting layer of the reflective circular polarizer 7

[0282]

[0283] Table 4. Fabricated reflective circular polarizers 1 to 7

[0284]

[0285] [Preparation of Laminated Optical Film] A laminated optical film was prepared according to the following procedure.

[0286] <Preparation of Retardation Layer 1> A reverse dispersion retardation layer 1 was prepared with reference to the method described in paragraphs 0151 to 0163 of JP 2020-084070 A. The retardation layer 1 had Re=146 nm and Rth=73 nm.

[0287] <Preparation of Positive C Plate 2> Positive C Plate 1 was prepared by adjusting the film thickness with reference to the method described in paragraphs 0132 to 0134 of JP 2016-053709 A. However, the support was changed from a polyethylene terephthalate film (PET film) to a triacetyl cellulose film (TAC film). Positive C Plate 1 had Re = 0.1 nm and Rth = -80 nm.

[0288] <Preparation of Absorbing Linear Polarizer> An absorbing linear polarizer was prepared by the following procedure.

[0289] (Preparation of Cellulose Acylate Film 1) -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 a core layer cellulose acylate dope.

[0290] 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

[0291] Compound F

[0292] -Preparation of Outer Layer Cellulose Acylate Dope- 10 parts by mass of the following matting agent solution was added to 90 parts by mass of the above core layer cellulose acylate dope to prepare a cellulose acetate solution to be used as the outer layer cellulose acylate dope.

[0293] 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

[0294] - Preparation of Cellulose Acylate Film 1 - The above core layer cellulose acylate dope and the above outer layer cellulose acylate dope were filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm, and then the above core layer cellulose acylate dope and the outer layer cellulose acylate dopes on both sides thereof were simultaneously cast onto a drum at 20°C from a casting nozzle (band casting machine).

[0295] Next, the film was peeled off when the solvent content was about 20% by mass, and both ends in the width direction of the film were fixed with tenter clips, and the film was dried while being stretched in the transverse direction at a stretch ratio of 1.1.

[0296] Thereafter, the film was further dried by transporting it between rolls of a heat treatment device to prepare an optical film having a thickness of 40 μm, which was designated as Cellulose Acylate Film 1. The in-plane retardation of the obtained Cellulose Acylate Film 1 was 0 nm.

[0297] <Formation of Photo-Alignment Layer PA1>

[0298] The following coating solution for forming an alignment layer S-PA-1 was continuously applied onto the above-mentioned cellulose acylate film 1 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.

[0299] ------------------------------------------------------------------ (Coating liquid for forming alignment layer S-PA-1) -------------------------------------------------- Polymer M-PA-1 described below: 100.00 parts by mass Acid generator PAG-1 described below: 5.00 parts by mass Acid generator CPI-110TF described below: 0.005 parts by mass Xylene: 1220.00 parts by mass Methyl isobutyl ketone: 122.00 parts by mass

[0300] Polymer M-PA-1

[0301] Acid generator PAG-1

[0302] Acid generator CPI-110TF

[0303] <Formation of Optically Absorbent Anisotropic Layer P1> 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 (23°C). The coating layer P1 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 90°C for 60 seconds and cooled again to room temperature. The coating layer P1 was then heated at an illuminance of 200 mW / cm ２ The light was irradiated for 2 seconds under the irradiation conditions of 1.6 μm to form an optically absorptive anisotropic layer P1 on the alignment layer PA1.

[0304] 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-3 below Cyclopentanone 46.00 parts by mass Tetrahydrofuran 46.00 parts by mass Benzyl alcohol 3.00 parts by mass ----------------------------------------------------------------------------------

[0305] Dichroic substance D-1

[0306] Dichroic substance D-2

[0307] Dichroic substance D-3

[0308] Polymer liquid crystal compound M-P-1

[0309] Low molecular liquid crystal compound M-1

[0310] Surfactant F-3

[0311] <Transfer for producing laminated optical film> Transfer for producing laminated optical film was performed by the following procedure. (1) UV adhesive Chemiseal U2084B (manufactured by Chemitech Corporation, refractive index after curing n 1.60) was applied to a PMMA substrate to a thickness of 2 μm using a wire bar coater. The optically absorptive anisotropic layer P1 was transferred onto the PMMA substrate. The optically absorptive anisotropic layer P1 was bonded with a laminator so that the side opposite the temporary support of the optically absorptive anisotropic layer P1 was in contact with the UV adhesive. (2) After purging with nitrogen in a purge box until the oxygen concentration was 100 ppm or less, the optically absorptive anisotropic layer P1 was cured by irradiating it with ultraviolet light from a high-pressure mercury lamp from the temporary support side. The illuminance was 25 mW / cm ２ , the irradiation dose is 1000 mJ / cm ２ (3) Finally, the temporary support of the optically absorptive anisotropic layer P1 was peeled off.

[0312] Next, the retardation layer 1 was transferred onto the optically absorptive anisotropic layer P1 by the same transfer procedure as described above, except that the retardation layer 1 and the optically absorptive anisotropic layer P1 were laminated such that the slow axis of the retardation layer 1 and the absorption axis of the optically absorptive anisotropic layer P1 formed an angle of 45°. Next, the positive C plate 2 was transferred onto the retardation layer 1 by the same transfer procedure as described above.

[0313] Finally, the light-reflecting layer 1 was transferred to the positive C plate 2 using the same transfer procedure as described above. In this way, a laminated optical film using the reflective circular polarizer 1 of Example 1 was obtained.

[0314] Regarding the reflective circular polarizers 2 to 7, laminated optical films 2 to 7 were prepared in the same manner.

[0315] [Evaluation of Optical Properties of Reflective Circular Polarizers] The optical properties of the reflective polarizers 1 to 7 were measured by the following method, and the results are shown in Table 5-1.

[0316] I1: When circularly polarized light reflected by a reflective circular polarizer is incident on the reflective circular polarizer, the transmittance of the circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer is doubled. The transmittance was measured using a spectrophotometer (JASCO Corporation, UV-Visible-Near-Infrared Spectrophotometer V-750). A broadband circular polarizer was set on the light source side to emit right-handed circularly polarized light. A broadband circular polarizer was set on the detector side to filter out right-handed circularly polarized light and detect only left-handed circularly polarized light. The broadband circular polarizer was prepared by combining a polarizing film POLAX-15N manufactured by Luceo Co., Ltd. and a wavelength film SB-RETAX-5L-1 / 4λ manufactured by Luceo Co., Ltd. I1 was obtained by doubling the obtained transmittance.

[0317] I2: This is the reflectance of circularly polarized light reflected by a reflective circular polarizer, which is incident on the reflective circular polarizer, with the circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer, multiplied by 1 / 2. The reflectance was measured using a spectrophotometer (JASCO Corporation, UV-Visible-Near-Infrared Spectrophotometer V-750). A broadband circular polarizer was set on the light source side so that right-handed circularly polarized light was emitted. A broadband circular polarizer was set on the detector side so that right-handed circularly polarized light was cut out and only left-handed circularly polarized light was detected. The broadband circular polarizer was prepared by combining a polarizing film POLAX-15N manufactured by Luceo Co., Ltd. and a wavelength film SB-RETAX-5L-1 / 4λ manufactured by Luceo Co., Ltd. I2 was obtained by multiplying the obtained reflectance by 1 / 2.

[0318] I3: This is the reflectance of the light reflected by a reflective circular polarizer when circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer is incident on the reflective circular polarizer, multiplied by 1 / 4. The reflectance was measured using a spectrophotometer (JASCO Corporation, UV-Visible-Near-Infrared Spectrophotometer V-750). A broadband circular polarizer was set on the light source side so that left-handed circularly polarized light was emitted. A broadband circular polarizer was set on the detector side so that right-handed circularly polarized light was cut off and only left-handed circularly polarized light was detected. The broadband circular polarizer was prepared by combining a polarizing film POLAX-15N manufactured by Luceo Co., Ltd. and a wavelength film SB-RETAX-5L-1 / 4λ manufactured by Luceo Co., Ltd. I3 was obtained by multiplying the obtained reflectance by 1 / 4.

[0319] I4: Haze of the reflective circular polarizer. I4 was obtained by measuring the haze value in accordance with JIS K7136 using a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0320] I5 represents the value of SCE / SCI x 100 in the reflectance measured with an integrating sphere when unpolarized light is incident on a reflective circular polarizer. SCE and SCI were measured using an integrating sphere unit attached to a spectrophotometer (JASCO Corporation, UV-Visible-Near-Infrared Spectrophotometer V-750). For SCE, the reflectance when specular reflection was removed was obtained by absorbing specularly reflected light with a light trap. For SCI, the reflectance including specular reflection was obtained by placing a white plate in the light trap. The ratio of these values ​​was calculated and multiplied by 100 to obtain I5.

[0321] [Evaluation of Optical Properties of Laminated Optical Films] The optical properties of Laminated Optical Films 1 to 7 were measured by the following methods, and the results are shown in Table 5-2.

[0322] I6: This is the value obtained by doubling the transmittance of the laminated optical film when circularly polarized light reflected by the laminated optical film is incident on the reflective circular polarizer side of the laminated optical film. The transmittance was measured using a spectrophotometer (UV-Visible-Near-Infrared Spectrophotometer V-750 manufactured by JASCO Corporation). A broadband circular polarizer was set on the light source side so that right-handed circularly polarized light was emitted. Nothing was set on the detector side. The broadband circular polarizer was prepared by combining the polarizing film POLAX-15N manufactured by Luceo Co., Ltd. and the wavelength film SB-RETAX-5L-1 / 4λ manufactured by Luceo Co., Ltd. I6 was obtained by doubling the obtained transmittance.

[0323] I7: When circularly polarized light reflected by a laminated optical film is incident on the reflective circular polarizer side of the laminated optical film, the reflectance of the circularly polarized light reflected by the laminated optical film in the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer is halved. The reflectance was measured using a spectrophotometer (JASCO Corporation, UV-Visible-Near-Infrared Spectrophotometer V-750). A broadband circular polarizer was set on the light source side so that right-handed circularly polarized light was emitted. A broadband circular polarizer was set on the detector side so that right-handed circularly polarized light was cut and only left-handed circularly polarized light was detected. Here, the broadband circular polarizer was prepared by combining a polarizing film POLAX-15N manufactured by Luceo Co., Ltd. and a wavelength film SB-RETAX-5L-1 / 4λ manufactured by Luceo Co., Ltd. I7 was obtained by multiplying the obtained reflectance by 1 / 2.

[0324] I8: This is the reflectance of the reflected light reflected by the laminated optical film when circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the laminated optical film is incident on the reflective circular polarizer side of the laminated optical film, multiplied by 1 / 4. The reflectance was measured using a spectrophotometer (UV-Visible-Near-Infrared Spectrophotometer V-750 manufactured by JASCO Corporation). A broadband circular polarizer was set on the light source side so that left-handed circularly polarized light was emitted. A broadband circular polarizer was set on the detector side so that right-handed circularly polarized light was cut and only left-handed circularly polarized light was detected. The broadband circular polarizer was prepared by combining the polarizing film POLAX-15N manufactured by Luceo Co., Ltd. and the wavelength film SB-RETAX-5L-1 / 4λ manufactured by Luceo Co., Ltd. I8 was obtained by multiplying the obtained reflectance by 1 / 4.

[0325] I9: represents the haze when light is incident on the laminated optical film from the reflective circular polarizer side. I9 was obtained by measuring the haze value according to JIS K7136 using a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0326] I 10 ; represents the value of SCE / SCI x 100 in the reflectance measured with an integrating sphere when unpolarized light is incident on the laminated optical film from the reflective circular polarizer side. SCE was obtained by absorbing specularly reflected light with a light trap, and the reflectance when specular reflection was removed was obtained. SCI was obtained by placing a white plate in the light trap section, and the reflectance including specularly reflected light was obtained. The ratio of these values ​​was calculated and multiplied by 100 to obtain I 10 obtained.

[0327] Table 5-1. Optical properties of reflective circular polarizers

[0328]

[0329] Table 5-2. Optical properties of laminated optical films

[0330]

[0331] [Molding of Laminated Optical Film] The prepared laminated optical film was molded into a curved surface shape as follows.

[0332] The laminated optical film 1 was set in a molding device. The molding space in the molding device consisted of box 1 and box 2, separated by the laminated optical film 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 the laminated optical film 1, with the concave side facing up. The reflective circular polarizer side of the laminated optical film 1 was positioned facing the mold. A transparent window was installed on the top of box 2 above the laminated optical film 1, and an IR light source for heating the laminated optical film 1 was installed outside this window. A patterned infrared reflective filter consisting of a cholesteric liquid crystal layer that reflects infrared light with a wavelength of 2.2 μm to 3.0 μm at a reflectance of approximately 50% was placed between the IR light source and the laminated optical film 1. The pattern of the patterned infrared reflection filter was donut-shaped, and was obtained by hollowing out a 1-inch diameter portion in the center of a circular infrared reflection filter with a diameter of 2 inches. When viewed from directly above, the center of the patterned infrared reflection filter was positioned at the center of the mold. Next, a vacuum pump was used to evacuate the interiors of boxes 1 and 2 to 0.1 atmospheres or less. Next, as a step of heating the laminated optical film 1, infrared rays were irradiated to heat the laminated optical film 1 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 create a state in which the center was easily stretched and the edges were less likely to stretch during molding. Next, as a step of pressing the laminated optical film 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 film 1 was pressure-bonded to the mold. Finally, the laminated optical film 1 was removed from the lens mold. As a result, a laminated optical film 1 formed on a curved surface was obtained.

[0333] Laminated optical films 2 to 7 were also molded into curved surfaces using the same procedure.

[0334] [Contrast Evaluation] [Fabrication of Virtual Reality Display Device] A virtual reality display device "Huawei VR Glass" manufactured by Huawei, which is a virtual reality display device employing a reciprocating optical system, was disassembled, and all of the composite lenses were removed. Instead, a composite lens 1 bonded with a laminated optical film 1 was incorporated into the main body, and the laminated optical body was placed between the composite lens 1 and the eye so that the light-absorbing anisotropic layer P1 side was facing the eye, thereby fabricating a virtual reality display device of Comparative Example 1. In the fabricated virtual reality display device, a black and white checkered pattern was displayed on the image display panel, and the contrast visibility was visually evaluated using the following five-point scale.

[0335] <Contrast evaluation> A: The difference between black and white is noticeable, and the details are clearly distinguished. B: The difference between black and white is clear. C: The difference between black and white is clear, but it lacks some clarity. D: The difference between black and white is insufficient, and the image appears blurred.

[0336] Furthermore, the virtual reality display devices of Comparative Example 2 and Examples 1 to 5 were fabricated in the same manner, and contrast visibility was evaluated. The evaluation results are shown in Table 6.

[0337] As a result, the difference between black and white in the checkered pattern was clearly visible across the entire area of ​​the lens in the virtual reality display devices of Examples 1 to 5. On the other hand, in the virtual reality display devices of Comparative Examples 1 and 2, the difference between black and white in the checkered pattern was insufficient, and the image appeared blurred.

[0338] Table 6. Contrast evaluation results

[0339]

[0340] From the above results, the effects of the present invention are clear.

[0341] REFERENCE SIGNS LIST 10, 10a, 11 Reflective circular polarizer 12 Half mirror 14 Support 16 Reflective linear polarizer 18, 24 Retardation layer 20, 20a, 20b Laminated optical film 22 Absorbing linear polarizer 30, 34, 38 Cholesteric liquid crystal layer X 32, 36 Cholesteric liquid crystal layer Y 100a, 100b Virtual reality display device 102 Image display panel 104, 108 λ / 4 plate 106 Absorbing linear polarizer 202 Black display area 204 White display area 206 Black area of ​​transmission ghost 208 White area of ​​transmission ghost 209, 213 Superposition area 210 Black area of ​​reflection ghost 212 White area of ​​reflection ghost

Claims

1. A reflective circular polarizer including a cholesteric liquid crystal layer that satisfies the relationship of the following formula (1): Formula (1): I1 + I2 + I3 + I4 + I5 < 3.

0. Here, I1 is a value obtained by doubling the transmittance of circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer, among the transmitted light that passes through the reflective circular polarizer when circularly polarized light reflected by the reflective circular polarizer is incident on the reflective circular polarizer. I2 is a value obtained by halving the reflectance of circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer, among the reflected light that is reflected by the reflective circular polarizer when circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer is incident on the reflective circular polarizer. I3 is a value obtained by quartering the reflectance of the reflected light that is reflected by the reflective circular polarizer when circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer is incident on the reflective circular polarizer. I4 represents the haze value of the reflective circular polarizer, and I5 represents the value of SCE / SCI×100 in reflectance measured with an integrating sphere when unpolarized light is incident on the reflective circular polarizer.

2. The reflective circular polarizer according to claim 1, comprising a cholesteric liquid crystal layer X formed using a rod-shaped liquid crystal compound and a cholesteric liquid crystal layer Y formed using a discotic liquid crystal compound.

3. The reflective circular polarizer according to claim 1, comprising a plurality of cholesteric liquid crystal layers having different selective reflection center wavelengths.

4. A laminated optical film including a reflective circular polarizer and an absorbing linear polarizer, wherein the laminated optical film satisfies the relationship of the following formula (2): Formula (2) I6 + I7 + I8 + I9 + I 10 <3.5 Here, I6 is the value obtained by doubling the transmittance of the laminated optical film when circularly polarized light reflected by the laminated optical film is incident from the reflective circular polarizer side of the laminated optical film. I7 is the value obtained by halving the reflectance of circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the reflective circular polarizer, among the reflected light reflected by the laminated optical film, when circularly polarized light reflected by the laminated optical film is incident from the reflective circular polarizer side of the laminated optical film. I8 is the value obtained by quarting the reflectance of the reflected light reflected by the laminated optical film when circularly polarized light having the opposite rotation direction to the circularly polarized light reflected by the laminated optical film is incident from the reflective circular polarizer side of the laminated optical film. I9 represents the haze value when light is incident on the laminated optical film from the reflective circular polarizer side of the laminated optical film. I 10 represents the value of SCE / SCI×100 in the reflectance measured with an integrating sphere when unpolarized light is incident on the laminated optical film from the reflective circular polarizer side of the laminated optical film.

5. The laminated optical film according to claim 4, wherein the reflective circular polarizer comprises a cholesteric liquid crystal layer, and a retardation layer is provided between the reflective circular polarizer and the absorbing linear polarizer.

6. The laminated optical film according to claim 4, wherein the reflective circular polarizer comprises a retardation layer and a reflective linear polarizer.

7. A virtual reality display device comprising the reflective circular polarizer according to any one of claims 1 to 3 or the laminated optical film according to any one of claims 4 to 6.

8. The virtual reality display device according to claim 7, further comprising a half mirror.

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