Optical laminate and display system

Abstract

Provided is an optical laminate that can contribute to improving the display characteristics of VR goggles. A display system according to an embodiment of the present invention is provided with: a display element having a display surface through which light for displaying an image is emitted forward via a polarizing member; a reflection unit that is disposed in front of the display element, includes a reflective polarization member, and reflects light emitted from the display element; a first lens section disposed on an optical path between the display element and the reflection section; a half mirror that is disposed between the display element and the first lens unit, transmits light emitted from the display element, and reflects the light reflected by the reflection unit toward the reflection unit; a first phase difference member disposed on an optical path between the display element and the half mirror; and a second phase difference member disposed on an optical path between the half mirror and the reflection unit, in which the polarization member and the first phase difference member constitute an optical laminate, and the optical laminate is provided with the polarization member, a layer functioning as a lambda / 2 wave plate, and a layer functioning as a lambda / 4 wave plate in this order.

Description

Technical Field

[0001] This invention relates to optical laminates and display systems. Background Technology

[0002] Image display devices, represented by liquid crystal displays and electroluminescent (EL) displays (e.g., organic EL displays), are rapidly gaining popularity. In image display devices, optical components such as polarizing members and phase difference members are generally used to achieve image display and improve image display performance (e.g., see Patent Document 1).

[0003] In recent years, new applications for image display devices have been developed. For example, goggles with displays (VR goggles) for realizing Virtual Reality (VR) have begun to be commercialized.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-103286 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In view of the above background, the main objective of the present invention is to provide an optical laminate that can help improve the display characteristics of VR goggles.

[0009] Problem Solving Methods

[0010] 1. The display system according to an embodiment of the present invention is a display system for displaying images to a user. The display system includes: a display element having a display surface from which light for displaying an image is emitted forward via a polarizing member; a reflective portion disposed in front of the display element, comprising a reflective polarizing member, and reflecting light emitted from the display element; a first transmissive portion disposed in the optical path between the display element and the reflective portion; a semi-reflective mirror disposed between the display element and the first lens portion, allowing light emitted from the display element to pass through and reflecting light reflected by the reflective portion toward the reflective portion; a first phase difference member disposed in the optical path between the display element and the semi-reflective mirror; and a second phase difference member disposed in the optical path between the semi-reflective mirror and the reflective portion, wherein the polarizing member and the first phase difference member constitute an optical laminate, and the optical laminate sequentially includes a polarizing member, a layer functioning as a λ / 2 waveplate, and a layer functioning as a λ / 4 waveplate.

[0011] 2. The optical laminate of the embodiment of the present invention is used in the display system described in 1 above, and it sequentially includes a polarizing member, a layer that functions as a λ / 2 waveplate, and a layer that functions as a λ / 4 waveplate.

[0012] 3. The in-plane phase difference Re(550) of the layer that functions as a λ / 2 waveplate in the optical laminate described in 2 above can be 230nm~330nm.

[0013] 4. The in-plane phase difference Re(550) of the layer that functions as a λ / 4 waveplate in the optical laminate described in 2 or 3 above can be 100nm~200nm.

[0014] 5. The angle between the slow axis of the layer that functions as a λ / 2 waveplate in the optical laminate described in any one of 2 to 4 above and the absorption axis of the polarizing member can be 5° to 35°.

[0015] 6. In any one of the optical laminates described above, the angle between the slow axis of the layer that functions as a λ / 4 waveplate and the absorption axis of the polarizing member can be 55° to 85°.

[0016] 7. The layer of the optical laminate described in any one of 2 to 6 above, which functions as a λ / 2 waveplate, can exhibit inverse dispersive wavelength characteristics.

[0017] 8. The layer of the optical laminate described in any one of 2 to 7 above, which functions as a λ / 4 waveplate, can exhibit inverse dispersion wavelength characteristics.

[0018] 9. The optical laminate described in any one of 2 to 8 above may further include a component whose refractive index characteristics show the relationship nz > nx = ny, and the component whose refractive index characteristics show the relationship nz > nx = ny is disposed on the opposite side of the layer that functions as a λ / 4 waveplate and the layer that functions as a λ / 2 waveplate.

[0019] 10. The optical laminate described in any one of 2 to 9 further comprises an anti-reflection protection member, wherein the anti-reflection protection member is disposed on the outermost side opposite to the polarizing member.

[0020] 11. For any one of the optical laminates described in any of 2 to 10 above, the value (1-DI) obtained by subtracting the depolarization index (DI) of the transmitted light at a wavelength of 550 nm measured at a polar angle of 0° from 1 can be 99.5% or higher.

[0021] 12. For any one of the optical laminates described in any of 2 to 11 above, the value (1-DI) obtained by subtracting the depolarization index (DI) of transmitted light with a wavelength of 550 nm measured at an polar angle of 30° and an azimuth angle of 0° to 360° can be 99.4% or higher.

[0022] 13. The optical laminate described in any one of 2 to 12 above can be used as a first phase difference member in a display method, the display method comprising: a step of allowing light of a display image emitted via a polarizing member to pass through the first phase difference member; a step of allowing light passing through the first phase difference member to pass through a half-reflector and a first lens portion; a step of allowing light passing through the half-reflector and the first lens portion to pass through a second phase difference member; a step of allowing light passing through the second phase difference member to be reflected by a reflective polarizing member toward the half-reflector; and a step of allowing light reflected by the reflective polarizing member and the half-reflector to pass through the second phase difference member and be transmitted through the reflective polarizing member.

[0023] The effects of the invention

[0024] According to the present invention, an optical laminate that can help improve the display characteristics of VR goggles can be provided. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating a simplified configuration of a display system according to one embodiment of the present invention.

[0026] Figure 2 This is a simplified cross-sectional view of an optical laminate according to one embodiment of the present invention.

[0027] Symbol Explanation

[0028] 2 Display System

[0029] 10 Polarizing components

[0030] 12 display elements

[0031] 14. Reflector

[0032] 16 First Lens Section

[0033] 18 Semi-reflective mirrors

[0034] 20 First phase difference component

[0035] 22 Second phase difference component

[0036] 24 Second Lens Section

[0037] 200 optical laminates Detailed Implementation

[0038] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to these embodiments. For clarity, the drawings sometimes schematically show the width, thickness, shape, etc., of various parts compared to the embodiments, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, regarding the drawings, the same or equivalent elements are sometimes labeled with the same symbols, and repeated descriptions are sometimes omitted.

[0039] (Definitions of terms and symbols)

[0040] The terms and symbols used in this manual are defined as follows.

[0041] (1) Refractive index (nx, ny, nz)

[0042] “nx” is the refractive index in the direction where the refractive index reaches its maximum in the plane (i.e., the slow axis direction), “ny” is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and “nz” is the refractive index in the thickness direction.

[0043] (2) In-plane phase difference (Re)

[0044] “Re(λ)” is the in-plane phase difference measured at 23°C with light of wavelength λnm. For example, “Re(550)” is the in-plane phase difference measured at 23°C with light of wavelength 550nm. When the thickness of the layer (film) is set as d (nm), Re(λ) can be obtained by the formula: Re(λ)=(nx-ny)×d.

[0045] (3) Phase difference (Rth) in the thickness direction

[0046] “Rth(λ)” is the phase difference in the thickness direction measured at 23°C using light with a wavelength of λnm. For example, “Rth(550)” is the phase difference in the thickness direction measured at 23°C using light with a wavelength of 550nm. When the thickness of the layer (film) is set as d (nm), Rth(λ) can be obtained using the formula: Rth(λ)=(nx-nz)×d.

[0047] (4) Nz coefficient

[0048] The coefficient of Nz can be obtained by Nz = Rth / Re.

[0049] (5) Angle

[0050] In this specification, when referring to an angle, unless otherwise specified, the angle includes both clockwise and counterclockwise directions relative to a reference direction. Therefore, for example, "45°" means ±45°. Furthermore, in this specification, "generally parallel" includes a range of 0°±10°, preferably 0°±5°, more preferably 0°±3°, and even more preferably 0°±1°. "Generally orthogonal" includes a range of 90°±10°, preferably 90°±5°, more preferably 90°±3°, and even more preferably 90°±1°.

[0051] A. Display System

[0052] Figure 1 This is a schematic diagram illustrating a simplified configuration of a display system according to one embodiment of the present invention. Figure 1 The diagram schematically illustrates the arrangement and shape of the various components of the display system 2. The display system 2 includes a display element 12, a reflective portion 14 including a reflective polarizing member, a first lens portion 16, a semi-reflective mirror 18, a first phase difference member 20, a second phase difference member 22, and a second lens portion 24. The reflective portion 14 is disposed on the display surface 12a side of the display element 12, i.e., in front, and is capable of reflecting light emitted from the display element 12. The first lens portion 16 is disposed in the optical path between the display element 12 and the reflective portion 14, and the semi-reflective mirror 18 is disposed between the display element 12 and the first lens portion 16. The first phase difference member 20 is disposed in the optical path between the display element 12 and the semi-reflective mirror 18, and the second phase difference member 22 is disposed in the optical path between the semi-reflective mirror 18 and the reflective portion 14. Sometimes, the components disposed in front, starting from the semi-reflective mirror (in the example shown, the semi-reflective mirror 18, the first lens portion 16, the second phase difference member 22, the reflective portion 14, and the second lens portion 24) are collectively referred to as the lens portion (lens portion 4).

[0053] The display element 12 is, for example, a liquid crystal display or an organic EL display, having a display surface 12a for displaying images. Light emitted from the display surface 12a passes through, for example, a polarizing member (typically a polarizing film) that may be included in the display element 12, and becomes first linearly polarized light.

[0054] The first phase difference member 20 can convert the first linearly polarized light incident on the first phase difference member 20 into the first circularly polarized light. For example... Figure 1As shown, the first phase difference member 20 can be integrally disposed on the display element 12. Specifically, the polarization member that may be included in the display element 12 is integrally disposed with the first phase difference member 20, thereby constituting the optical laminate 200 described later. In other words, the laminate 200 described later, which includes layer 20a that functions as a λ / 2 waveplate and layer 20b that functions as a λ / 4 waveplate, can be the first phase difference member 20 in the display system 2.

[0055] The semi-reflective mirror 18 allows light emitted from the display element 12 to pass through and reflects the light that has been reflected by the reflective portion 14 toward the reflective portion 14. The semi-reflective mirror 18 is integrally disposed on the first lens portion 16.

[0056] The second phase difference member 22 is a λ / 4 member (hereinafter, the second phase difference member is sometimes referred to as the second λ / 4 member) that allows light reflected by the reflective part 14 and the half-reflective mirror 18 to pass through the reflective part 14, which includes the reflective polarizing member. It should be noted that the second phase difference member 22 may also be integrally provided in the first lens part 16.

[0057] The first circularly polarized light emitted from the phase difference member (first phase difference member) 20 passes through the half-reflector 18 and the first lens section 16, and is converted into second linearly polarized light by the second λ / 4 member 22. The second linearly polarized light emitted from the second λ / 4 member 22 does not pass through the reflective polarizing member included in the reflecting section 14, but is reflected towards the half-reflector 18. At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing member included in the reflecting section 14 is the same as the reflection axis of the reflective polarizing member. Therefore, the second linearly polarized light incident on the reflecting section 14 is reflected by the reflective polarizing member.

[0058] The second linearly polarized light, after being reflected by the reflector 14, is converted into second circularly polarized light by the second λ / 4 member 22. The second circularly polarized light emitted from the second λ / 4 member 22 is reflected by the half-reflector 18 after passing through the first lens 16. The circularly polarized light, after being reflected by the half-reflector 18, passes through the first lens 16 and is converted into third linearly polarized light by the second λ / 4 member 22. The third linearly polarized light passes through the reflective polarizing member included in the reflector 14. At this time, the polarization direction of the third linearly polarized light incident on the reflective polarizing member included in the reflector 14 is the same as the transmission axis of the reflective polarizing member. Therefore, the third linearly polarized light incident on the reflector 14 passes through the reflective polarizing member.

[0059] Light passing through the reflector 14 passes through the second lens 24 and then enters the user's eye 26.

[0060] For example, the absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member included in the reflective portion 14 can be arranged approximately parallel to each other or approximately orthogonal. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the first phase difference member 20, and the in-plane phase difference of the first phase difference member 20, are set in a manner that enables the conversion of the first linearly polarized light into the first circularly polarized light. The above-mentioned angle and in-plane phase difference will be described in detail in section B. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the second phase difference member 22 is, for example, 40° to 50°, 42° to 48°, or approximately 45°.

[0061] The in-plane phase difference Re(550) of the second phase difference component 22 is, for example, 100nm~190nm, 110nm~180nm, 130nm~160nm, or 135nm~155nm.

[0062] The second phase difference element 22 preferably exhibits an inverse dispersion wavelength characteristic where the phase difference value increases corresponding to the wavelength of the measured light. The Re(450) / Re(550) ratio of the second phase difference element 22 is, for example, less than 1, and can be 0.95 or less, more preferably less than 0.90, and more preferably less than 0.85. The Re(450) / Re(550) ratio of the second phase difference element 22 is, for example, 0.75 or more.

[0063] In one embodiment, the second phase difference member 22 satisfies all of the following: Re(400) / Re(550) < 0.85, Re(650) / Re(550) > 1.03, and Re(750) / Re(550) > 1.05. The second phase difference member 22 preferably satisfies at least one of the following: 0.65 < Re(400) / Re(550) < 0.80 (preferably 0.7 < Re(400) / Re(550) < 0.75), 1.0 < Re(650) / Re(550) < 1.25 (preferably 1.05 < Re(650) / Re(550) < 1.20), and 1.05 < Re(750) / Re(550) < 1.40 (preferably 1.08 < Re(750) / Re(550) < 1.36). More preferably, it satisfies at least two of these conditions, and even more preferably, it satisfies all of them.

[0064] The refractive index characteristics of the second phase difference member 22 preferably exhibit a relationship of nx > ny ≥ nz. Here, "ny = nz" includes not only the case where ny and nz are exactly equal, but also the case where they are substantially equal. Therefore, without impairing the effects of the present invention, the case of ny < nz may be included. The Nz coefficient of the second phase difference member 22 is preferably 0.9 to 3, more preferably 0.9 to 2.5, even more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

[0065] The surface smoothness of the second phase difference member 22 is, for example, 0.50 arcmin or less, preferably 0.40 arcmin or less, more preferably 0.30 arcmin or less, and even more preferably 0.20 arcmin or less. By ensuring that the second phase difference member 22 satisfies such surface smoothness, a display system with excellent visual recognizability can be achieved. For example, by satisfying such surface smoothness, the uniformity of the in-plane phase difference can be improved, and as a result, light leakage in the reflective portion, as described later, can be suppressed. The method for measuring surface smoothness will be described later.

[0066] The thickness deviation of the second phase difference member 22 is preferably 1 μm or less, more preferably 0.8 μm or less, even more preferably 0.6 μm or less, and even more preferably 0.4 μm or less. With such a thickness deviation, for example, the aforementioned surface smoothness can be well achieved.

[0067] The second phase difference member 22 can be formed from any suitable material that satisfies the above-described characteristics. The second phase difference member 22 can be, for example, a stretched film of a resin film or an alignment fixing layer of a liquid crystal compound. For the second phase difference member 22 composed of a stretched film of a resin film or an alignment fixing layer of a liquid crystal compound, the same description as that of the layer constituting the first phase difference member 20, which functions as a λ / 4 waveplate, as described in section B, can be applied. The layer functioning as a λ / 4 waveplate and the second phase difference member 22 can be members with the same structure (forming material, thickness, optical properties, etc.), or they can be members with different structures.

[0068] The thickness of the second phase retardation member 22 is preferably 100 μm or less. Specifically, the thickness of the second phase retardation member 22, which is a stretched film of a resin film, is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, more preferably 10 μm to 60 μm, and even more preferably 20 μm to 50 μm. Furthermore, the thickness of the second phase retardation member 22, which is a liquid crystal alignment fixing layer, is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and even more preferably 1 μm to 4 μm.

[0069] In addition to a reflective polarizing member, the reflective portion 14 may also include an absorptive polarizing member. The absorptive polarizing member may be positioned in front of the reflective polarizing member. The reflection axis of the reflective polarizing member and the absorption axis of the absorptive polarizing member may be arranged approximately parallel to each other, and the transmission axis of the reflective polarizing member and the transmission axis of the absorptive polarizing member may also be arranged approximately parallel to each other. When the reflective portion 14 includes an absorptive polarizing member, the reflective portion 14 may comprise a laminate containing both a reflective polarizing member and an absorptive polarizing member.

[0070] The aforementioned reflective polarizing member allows polarized light parallel to its transmission axis (typically, linearly polarized light) to pass through while maintaining its polarization state, and reflects light with other polarization states (typically, light orthogonal to its transmission axis). The orthogonal transmittance (Tc) of the reflective polarizing member can be, for example, 0.01% to 3%. The unit transmittance (Ts) of the reflective polarizing member is, for example, 43% to 49%, preferably 45% to 47%. The polarization degree (P) of the reflective polarizing member can be, for example, 92% to 99.99%. The reflective polarizing member can typically be composed of a film with a multilayer structure (sometimes called a reflective polarizing film). Commercially available reflective polarizing films include, for example, those manufactured by 3M under the trade names "DBEF" and "APF," and those manufactured by Nitto Denko Corporation under the trade name "APCF."

[0071] The aforementioned absorptive polarizing member may typically include a resin film containing a dichroic substance (i.e., an absorptive polarizing film). As an absorptive polarizing film, the absorptive polarizing film described in section B can be used. The thickness of the absorptive polarizing film may be, for example, 1 μm or more and 20 μm or less, 2 μm or more and 15 μm or less, 12 μm or less, 10 μm or less, 8 μm or less, or 5 μm or less.

[0072] B. Optical laminate

[0073] Figure 2This is a simplified cross-sectional view of an optical laminate according to one embodiment of the present invention. The optical laminate 200 sequentially includes: a polarizing member 10, a layer 20a functioning as a λ / 2 waveplate, and a layer 20b functioning as a λ / 4 waveplate. The optical laminate 200 is preferably used such that the layer 20b functioning as a λ / 4 waveplate is the visual recognition side. In one embodiment, the above-described optical laminate can be used in a display system such as a VR goggle, disposed on the display element side (e.g., between the display element and the lens section). As described above, in the above-described display system, the polarizing member included in the display element and the first phase difference member can constitute an optical laminate. In other words, the laminate including the layer 20a functioning as a λ / 2 waveplate and the layer 20b functioning as a λ / 4 waveplate constitutes the first phase difference member 20.

[0074] By using the optical laminate constructed as described above, a display system with excellent display characteristics can be obtained. For example, in a display system including a lens section, if the optical laminate described above is arranged in the optical path before reaching the lens section, light with high circular polarization can be guided into the lens section of the display system. As a result, the so-called ghosting phenomenon, in which overlapping displayed images are visually perceived, can be reduced. In addition, light leakage can be suppressed, thereby contributing to high resolution. These effects become significant when the optical laminate described above is incorporated into the display system described in item A.

[0075] In the aforementioned optical laminate, the ellipticity of the transmitted light with a wavelength of 550 nm, measured at a polar angle of 30° and an azimuth angle of 0° to 360°, is preferably 0.77 or higher, more preferably 0.78 or higher, even more preferably 0.80 or higher, even more preferably 0.82 or higher, and particularly preferably 0.84 or higher. The aforementioned effect becomes significant when an optical laminate exhibiting such an ellipticity is used. One of the achievements of the aforementioned optical laminate is the improvement in display characteristics achieved by precisely controlling the ellipticity of the transmitted light in all directions. In the optical laminate, a higher ellipticity of the transmitted light with a wavelength of 550 nm, measured at a polar angle of 30° and an azimuth angle of 0° to 360°, is preferred, but its upper limit is, for example, 0.90 (preferably 0.93, more preferably 0.95, and even more preferably 0.99). Ellipticity is the ratio of the minor axis to the major axis of circularly polarized light; for example, the ellipticity is 1 for completely circularly polarized light and 0 for completely linearly polarized light. In addition, in this specification, "ellipticity" refers to the absolute value of the ellipticity.

[0076] In this specification, the ellipticity of transmitted light measured at a polar angle of 30° and an azimuth angle of 0° to 360° refers to the ellipticity of the emitted light at a polar angle of 30°, incident from the polarizing member side, measured at 11.25° per azimuth angle within the range of 0° to 360°. Therefore, "ellipticity of X or higher" measured at an azimuth angle of 0° to 360° means that the minimum of the 32 measured values ​​is X.

[0077] In one embodiment, the ellipticity of the transmitted light at a wavelength of 450 nm, measured at a polar angle of 30° and an azimuth angle of 0° to 360°, is preferably 0.77 or higher, more preferably 0.80 or higher, even more preferably 0.82 or higher, and particularly preferably 0.84 or higher. If it falls within this range, an optical laminate with significant reductions in ghosting, light leakage suppression, and high-resolution effects can be obtained. In the above-described optical laminate, a higher ellipticity of the transmitted light at a wavelength of 450 nm, measured at a polar angle of 30° and an azimuth angle of 0° to 360°, is more preferable, but its upper limit is, for example, 0.90 (preferably 0.93, more preferably 0.95, and even more preferably 0.99).

[0078] In one embodiment, the ellipticity of the transmitted light at a wavelength of 650 nm, measured at a polar angle of 30° and an azimuth angle of 0° to 360°, is preferably 0.77 or higher, more preferably 0.80 or higher, and even more preferably 0.82 or higher. If it falls within this range, an optical laminate with significant reductions in ghosting, light leakage suppression, and high-resolution effects can be obtained. In the aforementioned optical laminate, a higher ellipticity of the transmitted light at a wavelength of 650 nm, measured at a polar angle of 30° and an azimuth angle of 0° to 360°, is more preferable, but its upper limit is, for example, 0.90 (preferably 0.93, more preferably 0.95, and even more preferably 0.99).

[0079] In one embodiment, when the ellipticity of transmitted light at a wavelength of 550 nm is measured at an polar angle of 30° and within an azimuth angle range of 0° to 360° at 11.25° per azimuth angle, the average value of this ellipticity is 0.83 or higher, preferably 0.84 or higher, and more preferably 0.86 or higher. If this range is met, an optical laminate with significant reductions in ghosting, light leakage suppression, and high precision can be obtained. When measuring the ellipticity of transmitted light at a wavelength of 550 nm at an polar angle of 30° and within an azimuth angle range of 0° to 360° at 11.25° per azimuth angle, a higher average value of this ellipticity is preferred, but its upper limit is, for example, 0.90 (preferably 0.95). It should be noted that, in this specification, the average value of the ellipticity refers to the average of 32 measured values ​​obtained by measuring the ellipticity as described above.

[0080] In one embodiment, when the ellipticity of transmitted light at a wavelength of 450 nm is measured in the optical laminate at an polar angle of 30° and within an azimuth angle range of 0° to 360° at 11.25° per azimuth angle, the average value of this ellipticity is 0.80 or higher, preferably 0.84 or higher, and more preferably 0.86 or higher. If this range is met, an optical laminate with significant reductions in ghosting, light leakage suppression, and high-resolution effects can be obtained. In the aforementioned optical laminate, when the ellipticity of transmitted light at a wavelength of 450 nm is measured in the optical laminate at an polar angle of 30° and within an azimuth angle range of 0° to 360° at 11.25° per azimuth angle, a higher average value of this ellipticity is preferred, but its upper limit is, for example, 0.90 (preferably 0.95).

[0081] In one embodiment, when the ellipticity of transmitted light at a wavelength of 650 nm is measured at an polar angle of 30° and within an azimuth angle range of 0° to 360° at 11.25° per azimuth angle, the average value of this ellipticity is 0.80 or higher, preferably 0.84 or higher, and more preferably 0.86 or higher. If this range is met, an optical laminate with significant reductions in ghosting, light leakage suppression, and high-resolution effects can be obtained. In the aforementioned optical laminate, when the ellipticity of transmitted light at a wavelength of 650 nm is measured at an polar angle of 30° and within an azimuth angle range of 0° to 360° at 11.25° per azimuth angle, a higher average value of this ellipticity is preferred, but its upper limit is, for example, 0.90 (preferably 0.95).

[0082] In one embodiment, when measuring the ellipticity of transmitted light at a wavelength of 550 nm in the optical laminate at an polar angle of 30° and an azimuth angle of 0° to 360° at 11.25° per azimuth angle, the number of values ​​with an ellipticity of 0.85 or higher is 10 or more, preferably 15 or more, more preferably 20 or more, even more preferably 25 or more, particularly preferably 30 or more, and most preferably 32. If such a range is achieved, an optical laminate with significant effects in reducing ghosting, suppressing light leakage, and improving image quality can be obtained.

[0083] In one embodiment, when measuring the ellipticity of transmitted light at a wavelength of 450 nm in the optical laminate at an polar angle of 30° and an azimuth angle of 0° to 360° at 11.25° per azimuth angle, the number of values ​​with an ellipticity of 0.85 or higher is 10 or more, preferably 15 or more, more preferably 20 or more, even more preferably 25 or more, particularly preferably 30 or more, and most preferably 32. If such a range is achieved, an optical laminate with significant effects in reducing ghosting, suppressing light leakage, and improving image quality can be obtained.

[0084] In one embodiment, when measuring the ellipticity of transmitted light at a wavelength of 650 nm in the optical laminate at an polar angle of 30° and an azimuth angle of 0° to 360° at 11.25° per azimuth angle, the number of data points with an ellipticity of 0.85 or higher is 10 or more, preferably 15 or more, more preferably 20 or more, further preferably 25 or more, particularly preferably 30 or more, and most preferably 32. If it is within such a range, an optical laminate with significant effects of reducing ghosting, suppressing light leakage, and improving precision can be obtained.

[0085] In one embodiment, the ellipticity of the transmitted light at a wavelength of 550 nm, measured at a polar angle of 0° (frontal direction), is preferably 0.94 or higher, more preferably 0.95 or higher, and even more preferably 0.96 or higher. Within this range, an optical laminate exhibiting significant reductions in ghosting, light leakage suppression, and high-resolution effects can be obtained. A higher ellipticity of the transmitted light at a wavelength of 550 nm, measured at a polar angle of 0° (frontal direction), is preferred, but its upper limit is, for example, 0.99 (preferably 1).

[0086] In one embodiment, the ellipticity of the transmitted light at a wavelength of 450 nm, measured at a polar angle of 0° (frontal direction), is preferably 0.94 or higher, more preferably 0.95 or higher, and even more preferably 0.96 or higher. Within this range, an optical laminate exhibiting significant reductions in ghosting, light leakage suppression, and high-resolution effects can be obtained. A higher ellipticity of the transmitted light at a wavelength of 450 nm, measured at a polar angle of 0° (frontal direction), is preferred, but its upper limit is, for example, 0.99 (preferably 1).

[0087] In one embodiment, the ellipticity of the transmitted light at a wavelength of 650 nm, measured at a polar angle of 0° (frontal direction), is preferably 0.94 or higher, more preferably 0.95 or higher, and even more preferably 0.96 or higher. Within this range, an optical laminate exhibiting significant reductions in ghosting, light leakage suppression, and high-resolution effects can be obtained. A higher ellipticity of the transmitted light at a wavelength of 650 nm, measured at a polar angle of 0° (frontal direction), is preferred, but its upper limit is, for example, 0.99 (preferably 1).

[0088] In the aforementioned optical laminate, the ratio of the average value of the ellipticity (ellipticity B) of the transmitted light at a wavelength of 550 nm, measured at 11.25° per azimuth angle within a range of 0° to 360° at a polar angle of 30°, to the ellipticity of the transmitted light at a wavelength of 550 nm measured at a polar angle of 0° (frontal direction) (ellipticity A) (ellipticity B / ellipticity A) is preferably 0.85 or higher, more preferably 0.88 or higher, and even more preferably 0.9 or higher. Within this range, an optical laminate exhibiting significant reductions in ghosting, light leakage suppression, and high-resolution effects can be obtained. The upper limit of the ellipticity B / ellipticity A ratio is, for example, 0.98 (preferably 0.99, more preferably 1).

[0089] In one embodiment, the value (1-DI) obtained by subtracting the depolarization index (DI) of the optical laminate from 1 is 60% or more. The depolarization index can be determined by measuring the Mueller matrix (hereinafter (1)) representing the polarization effect and by formula (2) below. The Mueller matrix representing the polarization effect can be measured, for example, by using a Mueller matrix polarimeter (manufactured by Axometrics, product name "Axoscan") at 23°C with light of a given wavelength (e.g., 550 nm) incident from the polarizing member side of the optical laminate.

[0090] [Mathematical Expression 1]

[0091]

[0092] The value (1-DI) obtained by subtracting the depolarization index (DI) of the transmitted light with a wavelength of 550 nm measured at an polar angle of 30° and an azimuth angle of 0° to 360° from 1 is preferably 99.4% or more, more preferably 99.5% or more, even more preferably 99.6% or more, and particularly preferably 99.68% or more. If it falls within such a range, the effects of the present invention become significant. In this specification, the depolarization index (DI) of a given wavelength measured at an polar angle of 30° and an azimuth angle of 0° to 360° is the average value of the depolarization index measured at 11.25° per azimuth angle within the range of 0° to 360° for light of a given wavelength incident from the polarization member side of the optical stack at an polar angle of 30°.

[0093] The value (1-DI) obtained by subtracting the depolarization index (DI) of the transmitted light at a wavelength of 450 nm measured at a polar angle of 30° and an azimuth angle of 0° to 360° from 1 is preferably 99.4% or more, more preferably 99.5% or more, and even more preferably 99.6% or more. If it is within such a range, the effect of the present invention becomes significant.

[0094] The value (1-DI) obtained by subtracting the depolarization index (DI) of the transmitted light at a wavelength of 650 nm measured at a polar angle of 30° and an azimuth angle of 0° to 360° from 1 is preferably 99.4% or more, more preferably 99.5%, and even more preferably 99.6% or more. If it is within such a range, the effect of the present invention becomes significant.

[0095] The value (1-DI) obtained by subtracting the depolarization index (DI) of the transmitted light at a wavelength of 550 nm measured at a polar angle of 0° (frontal direction) from 1 is preferably 99.5% or more, more preferably 99.6% or more, even more preferably 99.7% or more, and particularly preferably 99.75% or more. If it is within such a range, the effects of the present invention become significant.

[0096] The value (1-DI) obtained by subtracting the depolarization index (DI) of the transmitted light at a wavelength of 450 nm measured at a polar angle of 0° (frontal direction) from 1 is preferably 99.5% or more, more preferably 99.6% or more, and even more preferably 99.7% or more. If it is within such a range, the effect of the present invention becomes significant.

[0097] The value (1-DI) obtained by subtracting the depolarization index (DI) of the transmitted light at a wavelength of 650 nm measured at a polar angle of 0° (frontal direction) from 1 is preferably 99.4% or more, more preferably 99.5% or more, and even more preferably 99.6% or more. If it is within such a range, the effect of the present invention becomes significant.

[0098] (Phase difference component)

[0099] As described above, the optical laminate, starting from the polarization member side, sequentially includes a layer that functions as a λ / 2 waveplate and a layer that functions as a λ / 4 waveplate as phase difference members.

[0100] The angle between the slow axis of the layer functioning as a λ / 2 waveplate and the absorption axis of the polarizing member is preferably 5° to 35°, more preferably 10° to 20°, even more preferably 12° to 18°, and particularly preferably about 15°. The angle between the slow axis of the layer functioning as a λ / 4 waveplate and the absorption axis of the polarizing member is preferably 55° to 85°, more preferably 70° to 80°, even more preferably 72° to 78°, and particularly preferably about 75°.

[0101] The in-plane phase difference Re(550) of the layer that functions as the λ / 4 waveplate can be, for example, 100nm~200nm, 110nm~180nm, 130nm~160nm, or 135nm~155nm.

[0102] The in-plane phase difference Re(550) of the layer that functions as the λ / 2 waveplate can be, for example, 200nm~330nm, 230nm~330nm, 230nm~290nm, or 250nm~280nm.

[0103] The layer that functions as a λ / 4 waveplate preferably exhibits an inverse dispersion wavelength characteristic where the phase difference value increases with the wavelength of the measurement light. The Re(450) / Re(550) ratio of the layer constituting the phase difference component is, for example, less than 1, and can be 0.95 or less, more preferably less than 0.90, and more preferably less than 0.85. The Re(450) / Re(550) ratio of the layer constituting the phase difference component is, for example, 0.75 or more. The layer that functions as a λ / 2 waveplate preferably exhibits an inverse dispersion wavelength characteristic where the phase difference value increases with the wavelength of the measurement light. The Re(450) / Re(550) ratio of the layer constituting the phase difference component is, for example, less than 1, and can be 0.95 or less, more preferably less than 0.90, and more preferably less than 0.85. The Re(450) / Re(550) ratio of the layer constituting the phase difference component is, for example, 0.75 or more. Hereinafter, layers that function as λ / 4 waveplates and layers that function as λ / 2 waveplates are sometimes collectively referred to as layers constituting phase difference components.

[0104] In one embodiment, the layer constituting the phase difference member satisfies all of the following: Re(400) / Re(550) < 0.85, Re(650) / Re(550) > 1.03, and Re(750) / Re(550) > 1.05. Preferably, the layer constituting the phase difference member satisfies at least one of the following: 0.65 < Re(400) / Re(550) < 0.80 (preferably 0.7 < Re(400) / Re(550) < 0.75), 1.0 < Re(650) / Re(550) < 1.25 (preferably 1.05 < Re(650) / Re(550) < 1.20), and 1.05 < Re(750) / Re(550) < 1.40 (preferably 1.08 < Re(750) / Re(550) < 1.36). More preferably, at least two of these conditions are satisfied, and even more preferably, all of them are satisfied.

[0105] The refractive index characteristics of the layers constituting the phase retardation member in the optical laminate preferably exhibit a relationship of nx > ny ≥ nz. Here, "ny = nz" includes not only the case where ny and nz are exactly equal, but also the case where they are substantially equal. Therefore, cases where ny < nz may be included without impairing the effects of the present invention. The Nz coefficient of the layers constituting the phase retardation member in the optical laminate is preferably 0.9 to 3, more preferably 0.9 to 2.5, even more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

[0106] The surface smoothness of the layer constituting the phase difference member in the optical laminate is, for example, 0.50 arcmin or less, preferably 0.40 arcmin or less, more preferably 0.30 arcmin or less, and even more preferably 0.20 arcmin or less. If it falls within this range, a display system with excellent visual recognizability can be achieved. For example, by satisfying such surface smoothness, the uniformity of the in-plane phase difference can be improved, resulting in a display system with excellent display characteristics.

[0107] The thickness deviation of the layer constituting the phase difference member in the optical laminate is preferably 1 μm or less, more preferably 0.8 μm or less, even more preferably 0.6 μm or less, and even more preferably 0.4 μm or less. With such a thickness deviation, for example, the aforementioned surface smoothness can be well achieved. Here, the thickness deviation can be determined by measuring the thickness of a first portion located within the measurement plane and the thickness at a position spaced apart by a given interval (e.g., 5 mm to 15 mm) in any direction (e.g., upward, downward, leftward, and rightward) from the first portion.

[0108] The layer constituting the phase retardation member in the optical laminate can be formed from any suitable material capable of satisfying the above-mentioned characteristics. This phase retardation member can, for example, be a stretched film of a resin film or an alignment fixing layer of a liquid crystal compound. It should be noted that the stretched film of a resin film is sometimes referred to as a phase retardation film.

[0109] Examples of resins included in the aforementioned resin films include: polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, and acrylic resins. These resins can be used alone or in combination (e.g., blending, copolymerization). When the layer constituting the phase retardation member in the optical laminate exhibits inverse dispersion wavelength characteristics, a resin film containing polycarbonate resins or polyester carbonate resins (hereinafter, sometimes simply referred to as polycarbonate resins) can be suitably used.

[0110] As the aforementioned polycarbonate resin, any suitable polycarbonate resin can be used as long as the effects of the present invention are achieved. For example, the polycarbonate resin comprises structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from at least one dihydroxy compound selected from alicyclic diols, alicyclic diethanols, di-, tri-, or polyethylene glycols, and alkylene diols or spirodiols. Preferably, the polycarbonate resin comprises structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from alicyclic diethanols and / or structural units derived from di-, tri-, or polyethylene glycols; more preferably, it comprises structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from di-, tri-, or polyethylene glycols. The polycarbonate resin may also, as needed, comprise structural units derived from other dihydroxy compounds. It should be noted that details of the polycarbonate resin suitable for constituting the layer of the first phase difference member and the method for forming the layer of the first phase difference member are described, for example, in Japanese Patent Application Publication Nos. 2014-10291, 2014-26266, 2015-212816, 2015-212817, and 2015-212818, and the descriptions in these publications are incorporated herein by reference.

[0111] When the layer formed from the stretched film functions as a λ / 4 waveplate, its thickness is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, more preferably 10 μm to 60 μm, and even more preferably 20 μm to 50 μm. When the layer formed from the stretched film functions as a λ / 2 waveplate, its thickness is, for example, 20 μm to 200 μm, preferably 20 μm to 140 μm, more preferably 20 μm to 120 μm, and even more preferably 40 μm to 100 μm.

[0112] The aforementioned alignment-fixing layer of the liquid crystal compound is a layer in which the liquid crystal compound is aligned in a given direction within the layer, and its alignment state is fixed. It should be noted that "alignment-fixing layer" includes the concept of an alignment-cured layer obtained by curing liquid crystal monomers as described later. Typically, rod-shaped liquid crystal compounds are aligned (homogeneous alignment) in a state where they are aligned along the slow axis direction of layers constituting phase retardation members in an optical laminate (e.g., layers functioning as λ / 4 waveplates, layers functioning as λ / 2 waveplates). Examples of rod-shaped liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably capable of polymerization. If the liquid crystal compound is capable of polymerization, the alignment state of the liquid crystal compound can be fixed by polymerization after alignment.

[0113] The alignment layer (liquid crystal alignment layer) of the aforementioned liquid crystal compound can be formed by the following method: an alignment treatment is performed on the surface of a given substrate; a coating liquid containing the liquid crystal compound is applied to the surface; the liquid crystal compound is aligned along a direction corresponding to the alignment treatment; and the alignment state is fixed. Any suitable alignment treatment can be used. Examples include mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment. Specific examples of mechanical alignment treatment include friction treatment and stretching treatment. Specific examples of physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include tilting vapor deposition and photo-alignment treatment. The processing conditions for each alignment treatment can be any suitable condition depending on the purpose.

[0114] The orientation of a liquid crystal compound can be achieved by processing it at a temperature that displays a liquid crystal phase, depending on the type of liquid crystal compound. Through such temperature processing, the liquid crystal compound is in a liquid crystal state and is oriented in accordance with the orientation processing direction of the substrate surface.

[0115] In one embodiment, the orientation state is fixed by cooling the oriented liquid crystal compound as described above. If the liquid crystal compound is polymerizable or crosslinkable, the orientation state can be fixed by performing a polymerization or crosslinking treatment on the oriented liquid crystal compound as described above.

[0116] As the aforementioned liquid crystal compound, any suitable liquid crystal polymer and / or liquid crystal monomer can be used. The liquid crystal polymer and liquid crystal monomer can be used alone or in combination. Specific examples of liquid crystal compounds and methods for fabricating liquid crystal alignment fixing layers are described, for example, in Japanese Patent Application Publication No. 2006-163343, Japanese Patent Application Publication No. 2006-178389, and International Publication No. 2018 / 123551. The contents of these publications are incorporated herein by reference.

[0117] When the layer formed from the alignment fixing layer of the liquid crystal compound functions as a λ / 4 waveplate, its thickness is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and even more preferably 1 μm to 4 μm. When the layer formed from the alignment fixing layer of the liquid crystal compound functions as a λ / 2 waveplate, its thickness is, for example, 2 μm to 20 μm, preferably 2 μm to 16 μm, more preferably 2 μm to 12 μm, and even more preferably 2 μm to 8 μm.

[0118] (Polarization component)

[0119] Typically, the aforementioned polarizing component may comprise a resin film containing a dichroic substance (sometimes referred to as an absorptive polarizing film). The thickness of the absorptive polarizing film may be, for example, 1 μm or more and 20 μm or less, 2 μm or more and 15 μm or less, 12 μm or less, 10 μm or less, 8 μm or less, or 5 μm or less.

[0120] The aforementioned polarizing component can be made from a single layer of resin film or from a laminate of two or more layers.

[0121] In the case of a single-layer resin film, for example, a polarizing component can be obtained by subjecting hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formaldehyde-treated PVA films, and partially saponified ethylene-vinyl acetate copolymer films to dyeing treatments using dichroic substances such as iodine and dichroic dyes, and stretching treatments. Among these, a polarizing component obtained by dyeing a PVA film with iodine and then uniaxially stretching it is preferred.

[0122] The above-mentioned dyeing using iodine can be carried out, for example, by immersing the PVA film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after dyeing or during dyeing. Alternatively, dyeing can be performed after stretching. Swelling treatment, crosslinking treatment, cleaning treatment, drying treatment, etc., can be applied to the PVA film as needed.

[0123] Examples of laminates made using two or more layers include a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and a PVA-based resin layer coated on the resin substrate. An absorptive polarizing film obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be manufactured by: for example, coating a PVA-based resin solution onto a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, obtaining a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to form an absorptive polarizing film from the PVA-based resin layer. In this embodiment, it is preferable to form a polyvinyl alcohol resin layer comprising a halide and a polyvinyl alcohol resin on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, stretching may, as needed, further include stretching the laminate in a gas atmosphere at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. Furthermore, in this embodiment, it is preferable to subject the laminate to a drying shrinkage treatment, which causes it to shrink by more than 2% in the width direction by heating while being transported along the length direction. Typically, the manufacturing method of this embodiment includes sequentially subjecting the laminate to assisted stretching in a gas atmosphere, dyeing, stretching in an aqueous solution, and drying shrinkage treatment. By introducing assisted stretching, even when PVA is coated on a thermoplastic resin, the crystallinity of PVA can be improved, achieving high optical properties. Additionally, by simultaneously improving the orientation of PVA beforehand, problems such as decreased orientation and dissolution of PVA during subsequent dyeing and stretching processes when immersed in water can be prevented, achieving high optical properties. Furthermore, when the PVA-type resin layer is immersed in a liquid, compared to when the PVA-type resin layer does not contain halides, the orientation disorder of polyvinyl alcohol molecules and the reduction of orientation can be suppressed. Therefore, the optical properties of the absorptive polarizing film obtained by immersing the laminate in a liquid through dyeing and stretching processes in an aqueous solution can be improved. Furthermore, by drying and shrinking the laminate in the width direction, optical properties can be improved. The resulting resin substrate / absorbent polarizing film laminate can be used directly (i.e., the resin substrate can be used as a protective layer for the absorbent polarizing film), or the resin substrate can be peeled off from the resin substrate / absorbent polarizing film laminate, and any suitable protective layer corresponding to the purpose can be laminated on the peeled surface or on the side opposite to the peeled surface. Detailed descriptions of such a method for manufacturing an absorbent polarizing film are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0124] The orthogonal transmittance (Tc) of the absorptive polarizing film is preferably 0.5% or less, more preferably 0.1% or less, and even more preferably 0.05% or less. The monomer transmittance (Ts) of the absorptive polarizing film is, for example, 41.0% to 45.0%, preferably 42.0% or more. The polarization degree (P) of the absorptive polarizing film is, for example, 99.0% to 99.997%, preferably 99.9% or more.

[0125] (Other components)

[0126] The components constituting the aforementioned optical laminate can be stacked via any suitable adhesive layer. By stacking the components via adhesive layers, an optical laminate with excellent smoothness can be obtained. If an optical laminate with excellent smoothness is used to construct, for example, the display system described in item A, then even if the image is magnified by the lens section, image display with excellent display characteristics can be achieved.

[0127] In one embodiment, the phase retardation member in the optical laminate includes any suitable adhesive layer, and the layers constituting the phase retardation member side of the optical laminate can be laminated via the adhesive layer. Additionally, the phase retardation member and the polarization member can be laminated via the adhesive layer. By integrating the phase retardation member and the polarization member using an adhesive layer, an optical laminate that helps prevent ghosting can be obtained.

[0128] The adhesive layer can be formed by an adhesive or a binder. Specifically, the adhesive layer can be an adhesive layer or a binder layer. The thickness of the adhesive layer is, for example, 0.05 μm to 30 μm.

[0129] Specific examples of adhesives include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, quantity, combination, and proportion of monomers in the base resin that forms the adhesive, as well as the amount of crosslinking agent, reaction temperature, and reaction time, adhesives with desired properties corresponding to the purpose can be prepared. The base resin of the adhesive can be used alone or in combination of two or more. Acrylic resins are preferred as base resins.

[0130] An adhesive is an adhesive whose state irreversibly changes from liquid to solid during the formation of an adhesive layer. It possesses the properties of being fluid during application and curing through a curing process (e.g., irradiation by active energy rays, heating). Curing-type adhesives are preferred as adhesives. Specifically, the adhesive layer is preferably a cured resin layer. Ultraviolet-curing adhesives are preferred as curing-type adhesives.

[0131] The aforementioned UV-curable adhesive contains curable monomers such as compounds having a (meth)acryloyl group or compounds having a vinyl group as curable monomers. Compounds having a (meth)acryloyl group are preferred. Here, (meth)acryloyl group refers to acryloyl group and / or methacryloyl group.

[0132] The thickness of the adhesive layer included in the aforementioned phase difference component is, for example, 0.5 μm or more and 3 μm or less, preferably 2 μm or less, more preferably 1.3 μm or less, even more preferably 1.1 μm or less, and particularly preferably 0.9 μm or less. With such a thickness, an optical laminate with extremely excellent smoothness can be obtained.

[0133] The aforementioned optical laminate may optionally further include a component with refractive index characteristics that exhibit the relationship nz > nx = ny (so-called a positive C-plate). The positive C-plate can, for example, be positioned on the opposite side of the phase difference component from the polarization component (i.e., the opposite side of the layer functioning as a λ / 4 waveplate to the layer functioning as a λ / 2 waveplate). By arranging the positive C-plate, the ellipticity of the emitted light is increased, and an optical laminate can be obtained.

[0134] The phase difference Rth(550) along the thickness direction of the positive C-plate is preferably -20nm to -200nm, more preferably -30nm to -180nm, even more preferably -40nm to -160nm, and particularly preferably -50nm to -140nm. Here, "nx = ny" includes not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. The in-plane phase difference Re(550) of the positive C-plate is, for example, less than 10nm.

[0135] The positive C-plate is formed from any suitable material that can satisfy the above characteristics. For example, the positive C-plate can be an alignment fixing layer of a resin film or a liquid crystal compound.

[0136] Representative examples of resin films constituting the positive C-plate include resin materials with negative birefringence. Resins with negative birefringence exhibit the property that the refractive index reaches its maximum in the direction orthogonal to the stretching direction during uniaxial stretching. Examples of resins with negative birefringence include resins with side chains incorporating highly polarimetric chemical bonds or functional groups such as aromatic rings or carbonyl groups. Specific examples of resins with negative birefringence include acrylic resins, styrene resins, maleimide resins, modified polyolefin resins, and fumarate resins. Specific examples can be found in Japanese Patent Application Publication Nos. 2021-076759, 2008-544304, and 2008-544317. The aforementioned resin materials can be used alone or in combination of two or more.

[0137] The resin film constituting the positive C-sheet may further contain any suitable additives as needed. Specific examples of additives include: plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, UV absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, and tackifiers. The type and content of additives can be appropriately set according to the purpose. The content of additives in the resin film is, for example, approximately 3% to 10% by weight.

[0138] In one embodiment, the resin material can be film-formed and used directly as a positive C-plate. Specifically, the film can be used directly as a positive C-plate without stretching it. For example, when a resin solution containing the resin material is coated onto a support (by solution film-forming method), stress is generated due to the volume shrinkage of the resin solution during drying on the support, causing the polymer molecular chains to tend to align in the in-plane direction. If a resin material with high birefringence and negative birefringence is used, a coating with large thickness-direction birefringence can be formed on the support through the shrinkage during drying. Then, the formed coating can be used directly as a positive C-plate.

[0139] The thickness of the positive C-plate made of resin film is, for example, 1 μm to 40 μm, preferably 3 μm to 35 μm, and more preferably 5 μm to 30 μm.

[0140] As the alignment fixing layer of the liquid crystal compound constituting the positive C-plate, an alignment fixing layer of liquid crystal material fixed in a vertical orientation is preferably exemplified. The liquid crystal material (liquid crystal compound) capable of vertical orientation can be a liquid crystal monomer or a liquid crystal polymer. As a specific example of such a liquid crystal compound and a method for forming the positive C-plate, the liquid crystal compound and the method for forming the phase retardation layer described in Japanese Patent Application Publication Nos. 2002-333642

[0020] to

[0028] can be cited.

[0141] The thickness of the positive C-plate, which is composed of an alignment fixing layer of liquid crystal compound, is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, and even more preferably 0.5 μm to 5 μm.

[0142] The aforementioned optical laminate may also include a protective member. The protective member may be positioned on the outermost side opposite to the polarizing member. In one embodiment, this protective member is an anti-reflective protective member.

[0143] The protective member is preferably composed of a laminated film having a substrate and a surface treatment layer formed on the substrate. The thickness of the laminated film is preferably 10 μm to 80 μm, more preferably 15 μm to 60 μm, and even more preferably 20 μm to 45 μm. The thickness of the surface treatment layer is preferably 0.5 μm to 10 μm, more preferably 1 μm to 7 μm, and even more preferably 2 μm to 5 μm.

[0144] Typically, the surface treatment layer comprises a hard coating. Typically, the hard coating is formed by applying a hard coating forming material to a substrate and curing the coating layer. Typically, the hard coating forming material comprises a curable compound as a layer-forming component. Examples of curing mechanisms for the curable compound include thermosetting and photocuring types. Examples of curable compounds include monomers, oligomers, and prepolymers. Multifunctional monomers or oligomers are preferably used as curable compounds. Examples of multifunctional monomers or oligomers include monomers or oligomers having two or more (meth)acryloyl groups, urethane (meth)acrylate or urethane (meth)acrylate oligomers, epoxy monomers or oligomers, and silicone monomers or oligomers.

[0145] The thickness of the hard coating is preferably 0.5μm to 10μm, more preferably 1μm to 7μm, and even more preferably 2μm to 5μm.

[0146] The surface treatment layer preferably includes a functional layer. The functional layer preferably functions as an anti-reflective layer. The protective member having the anti-reflective layer can be the aforementioned anti-reflective protective member. In a preferred embodiment, the surface treatment layer sequentially includes the aforementioned hard coating layer and the anti-reflective layer from the substrate side. The thickness of the functional layer is preferably 0.05 μm to 10 μm, more preferably 0.1 μm to 5 μm, and even more preferably 0.1 μm to 2 μm.

[0147] The protective member with the surface-treated layer can be configured such that the surface-treated layer is located on the front side. Specifically, the surface-treated layer can be located on the outermost surface of the optical laminate. In one embodiment, the maximum value of the 5° unidirectional reflectance spectrum of the surface-treated layer side surface of the protective member in the wavelength range of 420 nm to 680 nm is preferably 2.0% or less, more preferably 1.2% or less, further preferably 1.0% or less, and particularly preferably 0.8% or less. Here, the 5° unidirectional reflectance can be measured as follows: for example, a test sample is prepared by attaching the test object to a black acrylic sheet using an adhesive, and a spectrophotometer (manufactured by Hitachi High-Tech Knowledge Co., Ltd., trade name "U-4100") is used as the measuring device, and the incident angle of light relative to the test sample is set to 5° for measurement.

[0148] Example

[0149] The present invention will now be described in detail through embodiments, but the present invention is not limited to these embodiments in any way. It should be noted that the testing and evaluation methods in the embodiments are as follows. It should also be noted that when a term is used as "parts," it refers to "parts by weight" unless otherwise specified; and when a term is used as "%," it refers to "% by weight" unless otherwise specified.

[0150] (1) Thickness

[0151] Thicknesses below 10 μm were measured using a scanning electron microscope (manufactured by Nippon Electron Ltd., product name "JSM-7100F"). Thicknesses exceeding 10 μm were measured using a digital micrometer (manufactured by Anritsu Ltd., product name "KC-351C").

[0152] (2) In-plane phase difference Re(λ)

[0153] A 50 mm wide and 50 mm long square was cut from the central part and both ends of the phase retardation film along its width direction, with one side parallel to the width direction of the film, to prepare a sample. The in-plane phase difference at various wavelengths at 23 °C was measured using a Mueller matrix polarimeter (manufactured by Axometrics, product name "Axoscan").

[0154] (3) Monomeric transmittance and polarization of the polarizing film

[0155] The monomer transmittance (Ts), parallel transmittance (Tp), and orthogonal transmittance (Tc) of the polarizing film were measured using a spectrophotometer (manufactured by Otsuka Electronics Co., Ltd., "LPF-200"). These Ts, Tp, and Tc values ​​were obtained by measuring the Y values ​​using a 2-degree field of view (C light source) with JIS Z8701 and undergoing visibility correction. Based on the obtained Tp and Tc, the polarization degree of the polarizing film was calculated using the following formula.

[0156] Polarization (%) = {(Tp - Tc) / (Tp + Tc)} 1 / 2 ×100

[0157] (4) Surface smoothness

[0158] The smoothness of the retardation film was measured using a phase-shifting laser interferometer (manufactured by Zygo Corporation, product name "DynaFiz"). Specifically, the retardation film was laminated onto a miniature glass slide (manufactured by Matsunami Glass Industry Co., Ltd., product name "S200200") in a manner that did not introduce foreign matter, bubbles, or deformed stripes. Next, to remove the influence of tiny bubbles, degassing was performed using a pressure degassing device (autoclave). The degassing conditions were set at 50°C, 0.5 MPa, and 30 minutes. After degassing, the sample was allowed to cool naturally at room temperature for at least 30 minutes to obtain the test sample.

[0159] The test sample was placed on a measuring stage equipped with a vibration damping platform. A single-wavelength laser (633 nm) was used to interfere with a reference whose flatness was guaranteed, and the relative displacement within a given region (a circle with a diameter of 30 mm) was measured. Regarding the analysis, the smoothness of the phase retardation film (unit: arcmin) was defined as twice the value of the angle index "Slope magnitude RMS" obtained by selecting a frequency value of 0.1 / mm to 1 / mm (equivalent to 2σ).

[0160] [Manufacturing Example 1-1: Fabrication of Phase Retardation Film 1]

[0161] A batch polymerization unit consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled at 100°C was fed with 29.60 parts by weight (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluorene-9-yl]methane, 29.21 parts by weight (0.200 mol) of isosorbide (ISB), 42.28 parts by weight (0.139 mol) of spirodiol (SPG), 63.77 parts by weight (0.298 mol) of diphenyl carbonate (DPC), and 1.19 × 10⁻⁶ mol of calcium acetate monohydrate as a catalyst. -2 Parts by weight (6.78 × 10) -5(mol). After purging the reactor with nitrogen under reduced pressure, heating was performed using a heat transfer medium. Stirring was initiated when the internal temperature reached 100°C. The internal temperature was raised to 220°C 40 minutes after the start of heating. While maintaining this temperature, the pressure was reduced, reaching 13.3 kPa after 90 minutes. Phenolic vapors produced as a byproduct of the polymerization reaction were introduced into a 100°C reflux condenser, allowing a certain amount of monomer components contained in the phenol vapors to return to the reactor, while the uncondensed phenol vapors were recovered in a 45°C condenser. Nitrogen was introduced into the first reactor to temporarily restore atmospheric pressure, and the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Then, heating and depressurization were initiated in the second reactor, reaching an internal temperature of 240°C and a pressure of 0.2 kPa after 50 minutes. Polymerization was then allowed to proceed until the given stirring power was reached. At the moment when the given power is reached, nitrogen is introduced into the reactor to restore the pressure, the generated polyester carbonate resin is extruded into the water, and the wire is cut to obtain granules.

[0162] The obtained polyester carbonate resin (granules) was vacuum dried at 80°C for 5 hours. Then, a 130μm thick elongated resin film was produced using a film-forming apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250°C), a T-die (200mm wide, set temperature: 250°C), chilled rolls (set temperature: 120~130°C), and a winding machine. The obtained elongated resin film was stretched along its width at a stretching temperature of 140°C and a stretch ratio of 2.7.

[0163] Thus, a phase retardation film 1 (λ / 4 waveplate) with a thickness of 47 μm, a Re(590) of 140 nm, and an Nz coefficient of 1.2 was obtained. The Re(450) / Re(550) of the obtained phase retardation film 1 is 0.856, showing inverse dispersion wavelength characteristics.

[0164] In addition, the surface smoothness of the film is 0.25 arcmin.

[0165] [Manufacturing Example 1-2: Fabrication of Phase Retardation Film 2]

[0166] Polyester carbonate resin (granules) was obtained in the same manner as in Manufacturing Example 1-1.

[0167] The obtained polyester carbonate resin (granules) was vacuum dried at 80°C for 5 hours, and then a strip-shaped resin film with a thickness of 260 μm was produced using a film-forming device equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250°C), a T-die (width 200 mm, set temperature: 250°C), a chilled roll (set temperature: 120~130°C), and a winding machine. The obtained strip-shaped resin film was stretched along its width at a stretching temperature of 140°C and a stretch ratio of 2.7.

[0168] Thus, a phase retardation film 2 (λ / 2 waveplate) with a thickness of 91 μm, a Re(590) of 270 nm, and an Nz coefficient of 1.2 was obtained. The Re(450) / Re(550) of the obtained phase retardation film 2 is 0.859, showing inverse dispersion wavelength characteristics.

[0169] In addition, the surface smoothness of the film is 0.35 arcmin.

[0170] [Manufacturing Example 1-3: Fabrication of Phase Retardation Layer (Orientation Fixing Layer of Liquid Crystal Compound) 3]

[0171] 55 parts by weight of the compound represented by formula (I), 25 parts by weight of the compound represented by formula (II), and 20 parts by weight of the compound represented by formula (III) were added to 400 parts by weight of cyclopentanone (CPN), and the mixture was heated to 60°C and stirred until dissolved. The solution was then brought to room temperature, and 3 parts by weight of Irgacure 907 (manufactured by BASF Japan Co., Ltd.), 0.2 parts by weight of Megafac F-554 (manufactured by DIC Co., Ltd.), and 0.1 parts by weight of p-methoxyphenol (MEHQ) were added to the solution, followed by further stirring. The resulting solution was clear and homogeneous. The polymerizable composition was obtained by filtering the solution through a 0.20 μm membrane filter.

[0172] Alternatively, an alignment film was coated with a polyimide solution onto a 0.7 mm thick glass substrate using a spin-coating method. After drying at 100°C for 10 minutes, it was fired at 200°C for 60 minutes to obtain the coating. The obtained coating was then subjected to friction treatment using a commercially available friction device to form an alignment film.

[0173] Next, the polymeric composition obtained above was coated onto a substrate (essentially an oriented film) using spin coating and dried at 100°C for 2 minutes. After cooling the resulting coated film to room temperature, it was then subjected to a high-pressure mercury lamp at 30 mW / cm². 2Irradiation with ultraviolet light at an intensity of 30 seconds yielded a retardation layer (thickness: 3 μm) serving as the alignment fixation layer for the liquid crystal compound. The in-plane phase difference Re(590) of the retardation layer was 140 nm. Furthermore, the Re(450) / Re(550) ratio of the retardation layer was 0.851, exhibiting inverse dispersion wavelength characteristics. This retardation layer can function as a λ / 4 waveplate.

[0174] In addition, the surface smoothness of this phase difference layer is 0.16 arcmin.

[0175] [Chemical Formula 1]

[0176]

[0177] [Chemical Formula 2]

[0178]

[0179] [Manufacturing Examples 1-4: Fabrication of Phase Retardation Layer (Orientation Fixing Layer of Liquid Crystal Compound) 4]

[0180] Except that the thickness of the retardation layer was set to 6 μm, the retardation layer was obtained in the same manner as in Examples 1-3. The in-plane phase difference Re(590) of this retardation layer is 270 nm. In addition, the Re(450) / Re(550) of this retardation layer is 0.851, showing inverse dispersion wavelength characteristics. This retardation layer can function as a λ / 2 waveplate.

[0181] In addition, the surface smoothness of this phase difference layer is 0.22 arcmin.

[0182] [Manufacturing Examples 1-5: Fabrication of Phase Retardation Film 5]

[0183] By adjusting the stretching ratio and stretching temperature to achieve an in-plane phase difference Re(590) of 140 nm, a strip of norbornene resin film (manufactured by Zeon Corporation, Japan, trade name Zeonor, thickness 40 μm) was longitudinally stretched at its free end, thereby fabricating a 33 μm thick phase retardation film 5 (λ / 4 waveplate). The resulting phase retardation film 5 has a refractive index of nx > ny = nz. Furthermore, the Re(450) / Re(550) ratio of the phase retardation layer is 1.004, exhibiting approximately flat dispersive wavelength characteristics.

[0184] In addition, the surface smoothness of the film is 0.32 arcmin.

[0185] [Manufacturing Examples 1-6: Fabrication of Phase Retardation Film 6]

[0186] By adjusting the stretching ratio and stretching temperature to achieve an in-plane phase difference Re(590) of 270 nm, a strip of norbornene resin film (manufactured by Zeon Corporation, Japan, trade name Zeonor, thickness 50 μm) was longitudinally stretched at its free end, thereby fabricating a 33 μm thick phase retardation film 6 (λ / 2 waveplate). The resulting phase retardation film 6 has a refractive index of nx > ny = nz. In addition, the Re(450) / Re(550) ratio of the phase retardation layer is 1.004, exhibiting approximately flat dispersive wavelength characteristics.

[0187] In addition, the surface smoothness of the film is 0.42 arcmin.

[0188] [Manufacturing Examples 1-7: Fabrication of Phase Retardation Layer (Orientation Fixing Layer of Liquid Crystal Compound) 7]

[0189] A liquid crystal composition (coating solution) was prepared by dissolving 10g of a polymerizable liquid crystal (manufactured by BASF: trade name "Paliocolor LC242") that displays a nematic liquid crystal phase and 3g of a photopolymerization initiator (manufactured by BASF: trade name "Irgacure 907") relative to the polymerizable liquid crystal compound in 40g of toluene.

[0190] Orientation treatment was performed by rubbing the surface of a polyethylene terephthalate (PET) film (38 μm thick) with a rubbing cloth.

[0191] The liquid crystal coating solution described above was applied to the orientation-treated surface by bar coating, and then heated and dried at 90°C for 2 minutes, thereby orienting the liquid crystal compound.

[0192] The liquid crystal layer formed therefrom was irradiated with a metal halide lamp at a concentration of 1 mJ / cm². 2 The liquid crystal layer is cured by light, thereby forming a phase retardation layer on the PET film as a liquid crystal alignment fixing layer.

[0193] The thickness of the phase difference layer is 1.5 μm, and the in-plane phase difference Re(590) is 140 nm.

[0194] Furthermore, the retardation layer exhibits a refractive index characteristic of nx > ny = nz. Additionally, the Re(450) / Re(550) ratio of the retardation layer is 1.089, indicating positive dispersive wavelength characteristics. This retardation layer can function as a λ / 4 waveplate.

[0195] In addition, the surface smoothness of the film is 0.18 arcmin.

[0196] [Manufacturing Examples 1-8: Fabrication of Phase Retardation Layer (Alignment Fixing Layer of Liquid Crystal Compound) 8]

[0197] Except for setting the thickness of the retardation layer to 2.5 μm, a retardation layer with an in-plane phase difference Re(590) of 270 nm was obtained in the same manner as in Examples 1-7. The retardation layer exhibits refractive index characteristics of nx > ny = nz. In addition, the Re(450) / Re(550) of the retardation layer is 1.089, exhibiting positive dispersive wavelength characteristics. This retardation layer can function as a λ / 2 waveplate.

[0198] [Manufacturing Examples 1-9: Fabrication of Phase Retardation Film (Positive C-plate) 9]

[0199] 48 parts by weight of hydroxypropyl methylcellulose (Shin-Etsu Chemical, trade name: Metolose 60SH-50), 1560 parts by weight of distilled water, 8161 parts by weight of diisopropyl fumarate, 240 parts by weight of 3-ethyl-3-oxetanebutyl methyl acrylate, and 45 parts by weight of tert-butyl peroxypentanoate as a polymerization initiator were added to an autoclave equipped with a stirrer, condenser, nitrogen inlet pipe, and thermometer. After bubbling with nitrogen for 1 hour, the autoclave was stirred and kept at 49°C for 24 hours, thereby carrying out free radical suspension polymerization.

[0200] Next, the suspension containing the generated polymer particles was cooled to room temperature and centrifuged. The obtained polymer was washed twice with distilled water and twice with methanol, and then dried under reduced pressure. The resulting fumarate resin was dissolved in a toluene / methyl ethyl ketone mixture (50 wt% / 50 wt% toluene / methyl ethyl ketone) to prepare a 20% solution.

[0201] Furthermore, a dope was prepared by adding 5 parts by weight of tributyl trimellitate as a plasticizer to 100 parts by weight of fumarate resin.

[0202] A biaxially oriented polyester (poly(terephthalate / ethylene isophthalate) copolymer) film (75 μm thick) was used as the support film. The prepared adhesive was applied to the support film to achieve a dried film thickness of 20 μm and dried at 140 °C.

[0203] The dried coating (positive C plate) has Re(590)≈0nm and Rth(590)=-83nm. In addition, the Rth(450) / Rth(550) of the phase difference layer is 1.012, showing positive dispersive wavelength characteristics.

[0204] [Manufacturing Example 2: Fabrication of Polarizing Film]

[0205] As the thermoplastic resin substrate, a strip-shaped amorphous polyethylene terephthalate (PET) copolymer of isophthalic acid with a Tg of approximately 75°C (thickness: 100 μm) was used. One side of the resin substrate was subjected to corona treatment.

[0206] A PVA aqueous solution (coating solution) was prepared by adding 13 parts by weight of potassium iodide to 100 parts by weight of a PVA resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetyl-modified PVA (manufactured by Mitsubishi Chemical Corporation, trade name "Gohsenex Z410") in a 9:1 ratio, and dissolving the resulting mixture in water.

[0207] The above-mentioned PVA aqueous solution was coated on the corona-treated surface of the resin substrate and dried at 60°C, thereby forming a PVA resin layer with a thickness of 13 μm and producing a laminate.

[0208] The resulting laminate was stretched uniaxially along the longitudinal direction (length direction) to 2.4 times in an oven at 130°C (assisted stretching treatment in a gas atmosphere).

[0209] Next, the laminate was immersed in an insoluble bath at 40°C (an aqueous solution of boric acid prepared by mixing 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insoluble treatment).

[0210] Next, the mixture was immersed in a staining bath (an iodine aqueous solution prepared by mixing iodine and potassium iodide in a weight ratio of 1:7 relative to 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration to achieve the desired monomer transmittance (Ts) of the final absorptive polarizing film (staining treatment).

[0211] Next, it was immersed in a crosslinking bath (an aqueous solution of boric acid prepared by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment).

[0212] Then, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4.0 wt%, potassium iodide concentration 5.0 wt%) at a liquid temperature of 70°C, and simultaneously subjected to unidirectional stretching (stretching treatment in aqueous solution) in the longitudinal direction (length direction) between rollers with different circumferential speeds to achieve a total stretch ratio of 5.5.

[0213] Then, the laminate was immersed in a cleaning bath at a liquid temperature of 20°C (an aqueous solution of 100 parts by weight of water and 4 parts by weight of potassium iodide) (cleaning treatment).

[0214] Then, while drying in an oven maintained at approximately 90°C, it is contacted with SUS heated rollers maintained at a surface temperature of approximately 75°C (drying shrinkage treatment). The width-direction shrinkage rate of the laminate based on the drying shrinkage treatment is 5.2%.

[0215] In this way, an absorptive polarizing film with a thickness of about 5 μm is formed on the resin substrate.

[0216] A cyclic olefin resin film (thickness: 25 μm) serving as a protective layer was bonded to the surface of the obtained absorptive polarizing film (the side opposite to the resin substrate) using a UV-curable adhesive. Specifically, the adhesive was applied to achieve a total thickness of approximately 1 μm and then bonded using a roller press. The adhesive was then cured by irradiating the cyclic olefin resin film side with UV light. Finally, the resin substrate was peeled off.

[0217] Thus, a polarizing film composed of a cyclic olefin resin film / absorption polarizing film was obtained. The polarizing film has a monomer transmittance (Ts) of 43.4% and a polarization degree of 99.993%.

[0218] [Example 1]

[0219] An optical laminate was obtained by sequentially stacking the polarizing film, phase retardation film 2 (λ / 2 waveplate), and phase retardation film 1 (λ / 4 waveplate) obtained in manufacturing example 2.

[0220] Adjacent films are laminated using an acrylic adhesive layer (manufactured by Nitto Denko Corporation, 5 μm thick). During lamination, the relationship between the slow axis of each retardation film and the absorption axis of the polarization film is set as follows: with the absorption axis direction of the polarization film as viewed from retardation film 1 (λ / 4 waveplate) as a reference (0°), the angle of the slow axis direction of retardation film 2 (λ / 2 waveplate) is 15°, and the angle of the slow axis direction of retardation film 1 (λ / 4 waveplate) is 75°.

[0221] [Example 2]

[0222] An optical laminate was obtained by stacking the polarizing film, phase retardation layer 4 (λ / 2 waveplate), and phase retardation layer 3 (λ / 4 waveplate) obtained in manufacturing example 2.

[0223] Adjacent elements are superimposed using an acrylic adhesive layer (manufactured by Nitto Denko Corporation, 5 μm thick). During superposition, the relationship between the slow axis of each retardation film and the absorption axis of the polarization film is set as follows: with the absorption axis direction of the polarization film as viewed from retardation layer 3 (λ / 4 waveplate) as a reference (0°), the angle of the slow axis direction of retardation layer 4 (λ / 2 waveplate) is 15°, and the angle of the slow axis direction of retardation layer 3 (λ / 4 waveplate) is 75°.

[0224] [Example 3]

[0225] An optical laminate was obtained by stacking the polarizing film, phase retardation film 2 (λ / 2 waveplate), phase retardation film 1 (λ / 4 waveplate), and phase retardation film 9 obtained in manufacturing example 2.

[0226] Adjacent elements are superimposed using an acrylic adhesive layer (manufactured by Nitto Denko Corporation, 5 μm thick). During superposition, the relationship between the slow axis of each retardation film and the absorption axis of the polarization film is set as follows: with the absorption axis direction of the polarization film as viewed from retardation film 1 (λ / 4 waveplate) as a reference (0°), the angle of the slow axis direction of retardation film 2 (λ / 2 waveplate) is 15°, and the angle of the slow axis direction of retardation film 1 (λ / 4 waveplate) is 75°.

[0227] [Example 4]

[0228] An optical laminate was obtained by stacking the polarizing film, phase retardation layer 4 (λ / 2 waveplate), phase retardation layer 3 (λ / 4 waveplate), and phase retardation film 9 obtained in manufacturing example 2.

[0229] Adjacent elements are superimposed using an acrylic adhesive layer (manufactured by Nitto Denko Corporation, 5 μm thick). During superposition, the relationship between the slow axis of each phase retardation layer and the absorption axis of the polarizing film is set as follows: with the absorption axis direction of the polarizing film as observed from phase retardation layer 3 (λ / 4 waveplate) as a reference (0°), the angle of the slow axis direction of phase retardation layer 4 (λ / 2 waveplate) is 15°, and the angle of the slow axis direction of phase retardation layer 3 (λ / 4 waveplate) is 75°.

[0230] [Experimental Example 1]

[0231] An optical laminate was obtained by stacking the polarizing film, the phase retardation film 6 (λ / 2 waveplate), and the phase retardation film 5 (λ / 4 waveplate) obtained in Manufacturing Example 2.

[0232] Adjacent films are laminated using an acrylic adhesive layer (manufactured by Nitto Denko Corporation, 5 μm thick). During lamination, the relationship between the slow axis of each retardation film and the absorption axis of the polarization film is set as follows: with the absorption axis direction of the polarization film as observed from retardation film 5 (λ / 4 waveplate) as a reference (0°), the angle of the slow axis direction of retardation film 6 (λ / 2 waveplate) is 15°, and the angle of the slow axis direction of retardation film 5 (λ / 4 waveplate) is 75°.

[0233] [Experimental Example 2]

[0234] An optical laminate was obtained by stacking the polarizing film, phase retardation film 6 (λ / 2 waveplate), phase retardation film 5 (λ / 4 waveplate), and phase retardation film 9 obtained in manufacturing example 2.

[0235] Adjacent films are laminated using an acrylic adhesive layer (manufactured by Nitto Denko Corporation, 5 μm thick). During lamination, the relationship between the slow axis of each retardation film and the absorption axis of the polarization film is set as follows: with the absorption axis direction of the polarization film as observed from retardation film 5 (λ / 4 waveplate) as a reference (0°), the angle of the slow axis direction of retardation film 6 (λ / 2 waveplate) is 15°, and the angle of the slow axis direction of retardation film 5 (λ / 4 waveplate) is 75°.

[0236] [Experiment Example 3]

[0237] An optical laminate was obtained by stacking the polarizing film, phase retardation layer 8 (λ / 2 waveplate), and phase retardation layer 7 (λ / 4 waveplate) obtained in manufacturing example 2.

[0238] Adjacent elements are superimposed using an acrylic adhesive layer (manufactured by Nitto Denko Corporation, 5 μm thick). During superposition, the relationship between the slow axis of each retardation film and the absorption axis of the polarization film is set as follows: with the absorption axis direction of the polarization film as observed from the retardation layer 7 (λ / 4 waveplate) as a reference (0°), the angle of the slow axis direction of the retardation layer 8 (λ / 2 waveplate) is 15°, and the angle of the slow axis direction of the retardation layer 7 (λ / 4 waveplate) is 75°.

[0239] [Experiment Example 4]

[0240] An optical laminate was obtained by stacking the polarizing film, phase retardation layer 8 (λ / 2 waveplate), phase retardation layer 7 (λ / 4 waveplate), and phase retardation film 9 obtained in manufacturing example 2.

[0241] Adjacent elements are superimposed using an acrylic adhesive layer (manufactured by Nitto Denko Corporation, 5 μm thick). During superposition, the relationship between the slow axis of each retardation film and the absorption axis of the polarizing film is set as follows: with the absorption axis direction of the polarizing film as observed from retardation layer 7 (λ / 4 waveplate) as a reference (0°), the angle of the slow axis direction of retardation layer 8 (λ / 2 waveplate) is 15°, and the angle of the slow axis direction of retardation layer 7 (λ / 4 waveplate) is 75°.

[0242] <Evaluation>

[0243] The following evaluations were conducted for each embodiment.

[0244] 1. Ellipticity

[0245] Using a Mueller matrix polarimeter (manufactured by Axometrics, product name "Axoscan"), light of a given wavelength (450 nm, 550 nm, 650 nm) was incident from the polarization component side of the optical laminate at 23 °C, and the ellipticity of the light emitted from the phase difference component was measured.

[0246] The incident and exit angles were set to a polar angle of 30°, and the ellipticity was measured at 11.25° per azimuth within the range of 0° to 360°.

[0247] The minimum and average values ​​of the 32 measurements, as well as the number of data points that reached or exceeded 0.85, are shown in Table 1.

[0248] In addition, the ellipticity was measured by setting the incident and exit angles to polar angle 0. The measured values ​​are shown in Table 1.

[0249]

[0250] 2. De-biasing

[0251] Using a Mueller matrix polarimeter (manufactured by Axometrics, product name "Axoscan"), light of a given wavelength (450nm, 550nm, 650nm) was incident from the polarizing element side of the optical laminate at 23°C. The Mueller matrix obtained from this was used to calculate the depolarization index (DI) using the following formula. The depolarization performance was evaluated based on the value (1-DI) obtained by subtracting the depolarization index (DI) from 1.

[0252] [Mathematical Expression 2]

[0253]

[0254] For the depolarization index (DI), the depolarization index (DI) of transmitted light of a given wavelength measured at a polar angle of 30° and an azimuth angle of 0° to 360° was calculated, as well as the depolarization index (DI) of transmitted light of a given wavelength measured at a polar angle of 0° (frontal direction). For the depolarization index (DI) of transmitted light of a given wavelength measured at a polar angle of 30° and an azimuth angle of 0° to 360°, it was set as the average value of the depolarization index measured for the emitted light at a polar angle of 30° within the azimuth angle range of 0° to 360° at 11.25° per azimuth angle.

[0255] The results are shown in Table 2.

[0256]

[0257] Industrial applicability

[0258] The display system of the present invention can be used, for example, in display devices such as VR goggles.

Claims

1. A display system for displaying images to a user, This display system has the following features: A display element having a display surface from which light for displaying an image is emitted forward via a polarizing member; A reflective element, disposed in front of the display element, includes a reflective polarizing member and reflects light emitted from the display element; A first lens portion is disposed in the optical path between the display element and the reflective portion; A semi-reflective mirror is disposed between the display element and the first lens portion, allowing light emitted from the display element to pass through and causing light that has been reflected by the reflective portion to be reflected toward the reflective portion; A first phase difference component is disposed in the optical path between the display element and the semi-reflective mirror; as well as The second phase difference component is disposed in the optical path between the semi-reflective mirror and the reflective part. The polarization component and the first phase difference component form an optical stack. The optical laminate sequentially comprises a polarizing component, a layer that functions as a λ / 2 waveplate, and a layer that functions as a λ / 4 waveplate.

2. An optical laminate for use in the display system of claim 1, wherein the optical laminate comprises, in sequence: Polarizing components As the layer that functions as a λ / 2 waveplate, and This layer functions as a λ / 4 waveplate.

3. The optical laminate according to claim 2, wherein, The in-plane phase difference Re(550) of the layer that functions as a λ / 2 waveplate is 230nm~330nm.

4. The optical laminate according to claim 2, wherein, The in-plane phase difference Re(550) of the layer that functions as a λ / 4 waveplate is 100nm~200nm.

5. The optical laminate according to claim 2, wherein, The angle between the slow axis of the layer that functions as a λ / 2 waveplate and the absorption axis of the polarization member is 5° to 35°.

6. The optical laminate according to claim 2, wherein, The angle between the slow axis of the layer that functions as a λ / 4 waveplate and the absorption axis of the polarizing member is 55°~85°.

7. The optical laminate according to claim 2, wherein, The layer that functions as a λ / 2 waveplate exhibits inverse dispersive wavelength characteristics.

8. The optical laminate according to claim 2, wherein, The layer that functions as a λ / 4 waveplate exhibits inverse dispersive wavelength characteristics.

9. The optical laminate according to claim 2, further comprising a component that displays the refractive index characteristics showing the relationship nz > nx = ny. The component whose refractive index characteristics show the relationship nz>nx=ny is disposed on the opposite side of the layer that functions as a λ / 4 waveplate and the layer that functions as a λ / 2 waveplate.

10. The optical laminate according to claim 2, further comprising an anti-reflective protective component. The anti-reflective protective component is positioned on the outermost side opposite to the polarizing component.

11. The optical laminate according to claim 2, wherein, The value (1-DI) obtained by subtracting the depolarization index (DI) of the transmitted light at a wavelength of 550 nm measured at a polar angle of 0° from 1 is 99.5% or higher.

12. The optical laminate according to claim 2, wherein, The value (1-DI) obtained by subtracting the depolarization index (DI) of the transmitted light at a wavelength of 550 nm measured at an polar angle of 30° and an azimuth angle of 0° to 360° from 1 is 99.4% or higher.

13. The optical laminate according to claim 2, used as a first phase difference component in a display method. The display method includes: The step of causing the light emitted from the polarizing member to display the image to pass through the first phase difference member; The step of allowing light that has passed through the first phase difference member to pass through the half-reflecting mirror and the first lens section; The step of allowing light that has passed through the semi-reflective mirror and the first lens portion to pass through the second phase difference member; The step of causing the light after passing through the second phase difference member to be reflected in the direction of the half-reflecting mirror by the reflective polarizing member; as well as The step of enabling light that has been reflected by the reflective polarizing member and the half-reflector to pass through the second phase difference member and be transmitted through the reflective polarizing member.

Images