Retardation film, set of retardation films, and manufacturing method for lens part or display system

Abstract

The present invention provides a retardation film whereby it is possible to satisfactorily reduce the weight of VR goggles while improving visibility, a set of retardation films, and a manufacturing method for a lens part or a display system. Provided is a manufacturing method for a display system for displaying an image to a user, the manufacturing method including integrating, with a lens part, a retardation film which includes two or more retardation layers and in which the absolute value of the total of retardation change values RS of the retardation layers is 3.0 or less (here, the retardation change value RS is the inclination of an approximate straight line of the in-plane retardation Re(550) of the retardation layer measured in a state in which 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg of tension are applied) as a λ / 4 member.

Description

Method for manufacturing retardation film, retardation film set, lens part, or display system

[0001] The present invention relates to a method for manufacturing a retardation film, a retardation film set, or a lens portion or a display system.

[0002] Image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices), are rapidly becoming popular. In image display devices, optical components such as polarizing components and phase difference components are generally used to realize image display and improve image display performance (see, for example, Patent Document 1).

[0003] In recent years, new applications of image display devices have been developed. For example, goggles with displays (VR goggles) for realizing virtual reality (VR) have begun to be commercialized. Since the use of VR goggles in various situations is being considered, there is a demand for lighter weight, improved visibility, and the like.

[0004] Japanese Patent Application Laid-Open No. 2021-103286

[0005] While the weight reduction of the VR goggles can be achieved by, for example, thinning the lenses used in the VR goggles, there is also a need for the development of optical components suitable for display systems using thin lenses.

[0006] In view of the above, the main object of the present invention is to provide a retardation film, a retardation film set, or a method for manufacturing a lens portion or a display system that can effectively achieve weight reduction of VR goggles while improving visibility.

[0007] [1] A manufacturing method according to an embodiment of the present invention is a manufacturing method of a display system that displays an image to a user, the display system including: a display element having a display surface that emits light representing an image forward via a polarizing element; a reflective polarizing element that is disposed in front of the display element and reflects the light emitted from the display element; a first lens unit that is disposed on an optical path between the display element and the reflective polarizing element and has a curved main surface; a half mirror that is disposed between the display element and the first lens unit and transmits the light emitted from the display element and reflects the light reflected by the reflective polarizing element toward the reflective polarizing element; and a second retardation member disposed on an optical path between the half mirror and the reflective polarizing member and including a second λ / 4 member, the second retardation member including two or more retardation layers including a retardation layer having an in-plane retardation Re(550) of 100 nm to 190 nm, and the absolute value of the sum of the retardation change values ​​RS of the retardation layers is 3.0 or less (wherein the retardation change value RS is the slope of an approximation line of the in-plane retardation Re(550) of the retardation layer measured in a state where tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg are applied). [2] The manufacturing method described in [1] above may include preparing two of the retardation films, integrating one of the retardation films with the display element as the first retardation member, and integrating the other of the retardation films with the first lens portion as the second retardation member.[3] A manufacturing method according to an embodiment of the present invention is a manufacturing method of a lens unit used in a display system that displays an image to a user, the lens unit including: a reflective polarizing element that reflects light that is emitted forward from a display surface of a display element that displays an image and that has passed through a polarizing element and a first λ / 4 element; a first lens unit that is disposed on an optical path between the display element and the reflective polarizing element and has a curved main surface; a half mirror that is disposed between the display element and the first lens unit and transmits light that is emitted from the display element and reflects light reflected by the reflective polarizing element toward the reflective polarizing element; and a second retardation member that is disposed on an optical path between the half mirror and the reflective polarizing member and that includes a second λ / 4 member, and that includes two or more retardation layers including a retardation layer having an in-plane retardation Re(550) of 100 nm to 190 nm, and the absolute value of the sum of the retardation change values ​​RS of the retardation layers is 3.0 or less (here, the retardation change value RS is the slope of an approximation line of the in-plane retardation Re(550) of the retardation layer measured in a state where tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg are applied). The retardation film is integrated with the first lens unit as the second retardation member. [4] A retardation film according to an embodiment of the present invention includes two or more retardation layers, wherein the absolute value of the sum of the retardation change values ​​RS of the retardation layers is 3.0 or less, and the retardation change value RS is the slope of an approximate line of the in-plane retardation Re(550) of the retardation layers measured under tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg. [5] The retardation film described in [4] above may include a retardation layer A formed from a resin having negative birefringence and having a refractive index characteristic exhibiting the relationship nz > nx = ny. [6] The retardation film described in [4] or [5] above may further include another retardation layer, wherein the ratio of the thickness of the another retardation layer to the thickness of the retardation layer A (another retardation layer / retardation layer A) may be 10 or less. [7] In the retardation film described in any of [4] to [6] above, the retardation layer A may have a breaking elongation at 23°C of 1% or more.[8] The retardation film according to any one of [4] to [7] above may further include another retardation layer, and the in-plane retardation Re(550) of the another retardation layer may be 100 nm to 160 nm. [9] The retardation film according to any one of [4] to [8] above may have a surface smoothness of 0.4 arcmin or less.

[10] The retardation film according to any one of [4] to [9] above may be integrated with a member having a curved surface.

[11] In the retardation film according to

[10] above, the radius of curvature of the curved surface of the member having a curved surface may be 20 mm or more.

[12] The retardation film according to any one of [4] to

[11] above may be used as the second retardation member integrated with the first lens unit in a display system including: a display element having a display surface that emits light representing an image forward via a polarizing member; a reflective polarizing member that is arranged in front of the display element and reflects the light emitted from the display element; a first lens unit that is arranged on an optical path between the display element and the reflective polarizing member and has a curved main surface; a half mirror that is arranged between the display element and the first lens unit and transmits the light emitted from the display element and reflects the light reflected by the reflective polarizing member toward the reflective polarizing member; a first retardation member that is arranged on the optical path between the display element and the half mirror and includes a first λ / 4 member; and a second retardation member that is arranged on the optical path between the half mirror and the reflective polarizing member and includes a second λ / 4 member.

[13] A retardation film set according to an embodiment of the present invention includes a display element having a display surface that emits light representing an image forward via a polarizing member; a reflective polarizing member that is arranged in front of the display element and reflects the light emitted from the display element; a first lens unit that is arranged on an optical path between the display element and the reflective polarizing member and has a curved main surface; a half mirror that is arranged between the display element and the first lens unit and transmits the light emitted from the display element and reflects the light reflected by the reflective polarizing member toward the reflective polarizing member; a first retardation member that is arranged on the optical path between the display element and the half mirror and includes a first λ / 4 member; and a second retardation member that is arranged on the optical path between the half mirror and the reflective polarizing member and includes a second λ / 4 member. and a two-phase difference member, wherein the second phase difference member and the first lens portion are integrated. In the display system, a set of a first phase difference film for constituting the first phase difference member and a second phase difference film for constituting the second phase difference member is provided, wherein the first phase difference film and the second phase difference film each include two or more phase difference layers including a phase difference layer having an in-plane phase difference Re(550) of 100 nm to 190 nm, and the absolute value of the sum of the phase difference change values ​​RS of the phase difference layers is 3.0 or less (here, the phase difference change value RS is the slope of an approximation line of the in-plane phase difference Re(550) of the phase difference layer measured in states where tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg are applied).

[0008] According to the retardation film, retardation film set, or lens portion or display system manufacturing method according to the embodiment of the present invention, it is possible to effectively achieve a reduction in the weight of VR goggles while improving visibility.

[0009] FIG. 1 is a schematic diagram illustrating an example of a method for integrating a retardation film with a member having a curved surface. FIG. 2 is a schematic cross-sectional view of a retardation film according to an embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a general configuration of an example of a display system for VR goggles. FIG. 4 is a schematic cross-sectional view illustrating a configuration of an example of an integrated product of a retardation film with a member having a curved surface and a partially enlarged cross-sectional view thereof. FIG. 5 is a schematic cross-sectional view illustrating a configuration of an example of an optical laminate including a retardation film.

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In order to clarify the description, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the embodiments, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, in the drawings, the same or equivalent elements are given the same reference numerals, and redundant explanations may be omitted.

[0011] (Definition of Terms and Symbols) The definitions of terms and symbols used in this specification are as follows. (1) Refractive Index (nx, ny, nz) "nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), "ny" is the refractive index in the in-plane direction perpendicular to the slow axis (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-Plane Retardation (Re) "Re(λ)" is the in-plane retardation measured with light having a wavelength of λ nm at 23°C. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23°C. Re(λ) is calculated by the formula: Re(λ) = (nx - ny) × d, where d (nm) is the thickness of the layer (film). (3) Thickness Direction Retardation (Rth) "Rth(λ)" is the retardation in the thickness direction measured with light having a wavelength of λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction measured with light having a wavelength of 550 nm at 23°C. Rth(λ) is calculated by the formula: Rth(λ) = (nx - nz) x d, where d (nm) is the thickness of the layer (film). (4) Nz coefficient The Nz coefficient is calculated by Nz = Rth / Re. (5) Angle When an angle is mentioned in this specification, the angle includes both clockwise and counterclockwise angles relative to the reference direction. Therefore, for example, "45°" means ±45°.

[0012] A. Retardation Film A retardation film according to an embodiment of the present invention includes two or more (preferably two) retardation layers. The retardation film is provided in which the absolute value of the sum of the retardation change values ​​RS of the respective retardation layers is 3.0 or less. In one embodiment, the retardation film includes a retardation layer having an in-plane retardation Re(550) of 100 nm to 190 nm. The retardation film can be suitably used in a state integrated with a member having a curved surface. The retardation change value "RS" is the slope of the approximation line of the in-plane retardation Re(550) of the retardation layer measured under tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg, and can be an index of the degree of change in the in-plane retardation when tension is applied to the retardation film (and consequently, the retardation layer). Specifically, a small RS means that the in-plane retardation is less likely to change when tension is applied to the retardation layer. When the retardation film is integrated with a curved member, tension is applied to the retardation film, which may result in a change in the retardation of the retardation layer. However, if the absolute value of the sum of the retardation change values ​​RS of the retardation layers is within the above range, the change in the retardation can be reduced. Furthermore, the dimensional change and the change in the retardation caused by heating can also be reduced.

[0013] The absolute value of the sum of the retardation change values ​​RS of each retardation layer is preferably 2.5 or less, more preferably 2.0 or less, even more preferably 1.5 or less, and particularly preferably 1.0 or less. Within this range, the above-mentioned effect becomes significant. The smaller the absolute value of the sum of the retardation change values ​​RS of each retardation layer, the more preferable it is, and the lower limit thereof is, for example, 0.5 (preferably 0.1).

[0014] The surface smoothness of the retardation film is preferably 0.4 arcmin or less, more preferably 0.35 arcmin or less. Within this range, the occurrence of retardation unevenness when integrated with a curved surface can be suppressed. The surface smoothness can be measured by focusing irradiated light on the surface of the object. Details will be described later.

[0015] The ISC value of the retardation film is, for example, 50 or less, preferably 40 or less, more preferably 30 or less, and even more preferably 20 or less. The ISC value can be an index of smoothness or unevenness. If the ISC value is within this range, the occurrence of unevenness in retardation when the film is integrated with a member having a curved surface can be suppressed.

[0016] The thickness variation of the retardation film 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 thickness variation, for example, the ISC value can be satisfactorily achieved. Here, the thickness variation can be determined by measuring the thickness of a first portion located in the plane of the retardation film and the thickness at a position spaced a predetermined distance (e.g., 5 mm to 15 mm) from the first portion in any direction (e.g., upward, downward, leftward, and rightward) from the first portion.

[0017] The ISC value per unit thickness of the retardation film is preferably not more than 1, more preferably not more than 0.7, and even more preferably not more than 0.5. The ISC value per unit thickness can be determined, for example, by dividing the ISC value by the thickness (unit: μm).

[0018] As described above, the retardation film can be used in a state where it is integrated with a member having a curved surface. More specifically, the retardation film can be used in a state where it is integrated with the curved surface of a member having a curved surface. The curved surface may be a concave surface or a convex surface. The radius of curvature of the curved surface is, for example, 20 mm or more, for example, 25 mm or more, or for example, 30 mm or more, and for example, 150 mm or less, preferably 125 mm or less, more preferably 110 mm or less, and may be 90 mm or less. The diameter (major axis) of the member having a curved surface can be, for example, 20 mm to 80 mm, or for example, 30 mm to 70 mm. A preferred example of a member having a curved surface is a lens having a concave surface.

[0019] The retardation film and the member having a curved surface can be integrated by any appropriate method. FIG. 1 is a schematic diagram illustrating an example of a method for integrating a retardation film and a member having a curved surface. In FIG. 1( a), a retardation film 100 is placed on a member L, which is an adherend, in the form of a pressure-sensitive adhesive layer-attached retardation film 3 having a pressure-sensitive adhesive layer 2 provided on one side thereof. The member L is circular in plan view and has a concave shape upward in cross-sectional view. The pressure-sensitive adhesive layer-attached retardation film 3 can be placed in a predetermined position by chucking its end into a fixing jig (not shown). The pressure-sensitive adhesive layer-attached retardation film 3 is placed in a position where the pressure-sensitive adhesive layer 2 contacts the edge of the concave surface of the member L, and is pressed into the concave surface using a jig or the like in a heated and softened state, thereby bonding the entire concave surface of the member L as shown in FIG. 1( b). Thereafter, as shown in FIG. 1( c), unnecessary portions of the pressure-sensitive adhesive layer-attached retardation film 3 (for example, portions protruding from the member L in plan view) are removed to obtain an integrated product.

[0020] When integrating with the curved surface, the retardation film may typically be stretched. For example, the retardation film may be stretched from a planar shape corresponding to the planar shape of the member L to a curved shape that conforms to the curved shape of the member L. In this way, when integrating with the curved surface, tension may be applied to the retardation film, and the retardation change caused by the application of tension may be suppressed with the retardation film.

[0021] As shown in FIG. 1, when the retardation film 100 is integrated with a member L having a circular shape with a radius of 32.5 mm when viewed from the concave side and a concave curvature radius of 75 mm, the maximum absolute value of the difference between the Re (550) at the center 1c of the retardation film 100 and the Re (550) at other portions (outer portions) can be, for example, less than 15 nm, 10 nm or less, or 8 nm or less, and can also be, for example, 2 nm or more. When stretched during integration with the member L, variations in the in-plane retardation can occur within the plane (curved surface) of the retardation film. For example, in a curved retardation film after integration, the Re (550) of a portion spaced a large distance from the center may be significantly different from the Re (550) at the center. According to the retardation film, even when stretched during integration with the member L, variations in the in-plane retardation within the plane can be reduced.

[0022] Typically, the retardation film 100 includes a retardation layer A whose refractive index characteristics satisfy the relationship nz>nx=ny. The retardation layer A is a so-called positive C plate.

[0023] The retardation Rth(550) in the thickness direction of the retardation layer A is preferably −20 nm to −200 nm, more preferably −30 nm to −180 nm, even more preferably −40 nm to −160 nm, and particularly preferably −50 nm to −140 nm. 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 retardation Re(550) of the retardation layer A is, for example, less than 10 nm.

[0024] The retardation layer A is formed of any appropriate material that can satisfy the above characteristics. The retardation layer A can be formed, for example, from a resin film or an oriented and solidified layer of a liquid crystal compound. A retardation film formed from a resin film has the advantage of being excellent in mechanical properties (e.g., breaking elongation) and being less likely to crack even when applied to a curved surface.

[0025] In one embodiment, the retardation layer A may be formed from a resin having negative birefringence. A resin having negative birefringence is a resin that exhibits the property that, when uniaxially stretched, the refractive index in the direction perpendicular to the stretching direction is maximized. Examples of resins having negative birefringence include resins in which a chemical bond or functional group with large polarization anisotropy, such as an aromatic ring or a carbonyl group, is introduced into the side chain. Specific examples of resins having negative birefringence include acrylic resins, styrene resins, maleimide resins, modified polyolefin resins, fumarate ester resins, and the like. Specific examples of resins having negative birefringence and methods for manufacturing positive C-plates using such resins can be found in JP 2023-73125 A, JP 2021-76759 A, JP 2008-544304 A, JP 2008-544317 A, and the like. The above resin materials may be used alone or in combination of two or more.

[0026] When tension is applied to the retardation layer A formed from a resin having negative birefringence, a retardation occurs in the direction perpendicular to the direction of tension. Therefore, by combining the retardation layer A with a retardation layer formed from a material having positive birefringence, when the retardation layer A is stretched on a curved surface, the changes in the in-plane retardation of both retardation layers are offset, thereby suppressing the change in retardation in the entire retardation film, and as a result, it is possible to prevent retardation unevenness. Such an effect becomes more pronounced by combining the retardation layer A with a λ / 4 member as another retardation layer, as described later.

[0027] In another embodiment, the retardation layer A is preferably composed of a film containing a liquid crystal material fixed in homeotropic alignment. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of such liquid crystal compounds and methods for forming a positive C plate include the liquid crystal compounds and methods for forming the retardation layer described in paragraphs

[0020] to

[0028] of JP-A-2002-333642.

[0028] The retardation change value RS of the retardation layer A is preferably −4.0 to 0, more preferably −3.5 to −0.3 or less, even more preferably −3.0 to −0.5 or less, particularly preferably −2.5 to −0.8 or less, and most preferably −2.3 to −1 or less. Within such a range, the above-mentioned effect becomes remarkable.

[0029] The rupture elongation of the retardation layer A at 23 ° C is preferably 1% or more, more preferably 1.5% or more, and even more preferably 2.0% or more. Within this range, a retardation film that is less likely to crack even when applied to a curved surface can be obtained. The upper limit of the rupture elongation of the retardation layer A at 23 ° C is, for example, 5.0%. The method for measuring the rupture elongation will be described later.

[0030] When the retardation layer A is formed of a resin film, the thickness of the retardation layer A is preferably 0.5 μm to 40 μm, more preferably 1 μm to 40 μm, even more preferably 3 μm to 35 μm, and particularly preferably 5 μm to 30 μm. When the retardation layer A is formed of a liquid crystal alignment solidified layer, the thickness of the retardation layer A 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.

[0031] The retardation film may further include another retardation layer. FIG. 2 is a schematic cross-sectional view of a retardation film according to an embodiment of the present invention. In one embodiment, the retardation film 100 includes a retardation layer A and another retardation layer B. The another retardation layer B (sometimes referred to as retardation layer B) may be, for example, a λ / 4 member. The another retardation layer may be formed from a stretched resin film or an oriented and solidified layer of a liquid crystal compound. In one embodiment, the retardation layer A and the retardation layer B are laminated via an adhesive layer (adhesive layer, pressure-sensitive adhesive layer, etc.).

[0032] The in-plane retardation Re(550) of the another retardation layer is, for example, 100 nm to 190 nm, or may be 110 nm to 180 nm, 130 nm to 160 nm, or may be 135 nm to 155 nm. The another retardation layer preferably exhibits inverse dispersion wavelength characteristics in which the retardation value increases according to the wavelength of the measuring light. The Re(450) / Re(550) of the another retardation layer may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

[0033] The retardation change value RS of the other retardation layer is preferably −2.5 to 10, more preferably −2 to 5, and particularly preferably −1 to 4. In one embodiment, the retardation change value RS of the other retardation layer is 0 to 10, more preferably 0 to 5, and even more preferably 0 to 4. In another embodiment, the retardation change value RS of the other retardation layer is preferably −2.5 to 0, more preferably −2 to 0, and particularly preferably −1 to 0.

[0034] The ratio of the thickness of the another retardation layer to the thickness of the retardation layer A (another retardation layer / retardation layer A) is preferably 10 or less, more preferably 8 or less, even more preferably 5 or less, and particularly preferably 3 or less. Within such a range, a retardation film that is unlikely to cause retardation unevenness even when applied to a curved surface can be obtained. The lower limit of the ratio of the thickness of the another retardation layer to the thickness of the retardation layer A (another retardation layer / retardation layer A) is, for example, 0.3.

[0035] The value calculated by (the absolute value of the sum of the retardation change values ​​RS of each retardation layer in the retardation film) / (the ratio of the thickness of another retardation layer to the thickness of the retardation layer A) is preferably 0.3 or more, more preferably 0.5 or more, even more preferably 0.9 or more, and particularly preferably 10 or more. Within such a range, a retardation film that is less likely to cause retardation unevenness even when applied to a curved surface can be obtained. The upper limit of the value calculated by (the absolute value of the sum of the retardation change values ​​RS of each retardation layer in the retardation film) / (the ratio of the thickness of another retardation layer to the thickness of the retardation layer A) is, for example, 20.

[0036] Examples of the resin contained in the resin film constituting the other retardation layer include polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cycloolefin resins, cellulose resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, and acrylic resins. These resins may be used alone or in combination (for example, blends or copolymers). When the retardation film exhibits reverse dispersion wavelength characteristics, a resin film containing a polycarbonate resin or a polyester carbonate resin (hereinafter sometimes simply referred to as a polycarbonate resin) can be suitably used.

[0037] As the polycarbonate-based resin, any suitable polycarbonate-based resin can be used as long as the effects of the present invention can be obtained. For example, the polycarbonate-based resin contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, and structural units derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanols, di-, tri-, or polyethylene glycols, and alkylene glycols or spiroglycols. Preferably, the polycarbonate-based resin contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, structural units derived from an alicyclic dimethanol and / or structural units derived from di-, tri-, or polyethylene glycol; more preferably, it contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, and structural units derived from di-, tri-, or polyethylene glycol. The polycarbonate-based resin may contain structural units derived from other dihydroxy compounds as needed. Details of polycarbonate resins that can be suitably used for retardation films and methods for forming retardation films are described in, for example, JP-A-2014-10291, JP-A-2014-26266, JP-A-2015-212816, JP-A-2015-212817, and JP-A-2015-212818, the disclosures of which are incorporated herein by reference.

[0038] When the retardation film constituting the other retardation layer is a stretched resin film, its thickness is, for example, 20 μm to 150 μm, preferably 30 μm to 100 μm, more preferably 35 μm to 80 μm, and still more preferably 40 μm to 70 μm.

[0039] The liquid crystal compound alignment layer constituting another retardation layer is a layer in which the liquid crystal compound is aligned in a predetermined direction within the layer and the alignment state is fixed. The "alignment layer" is a concept that encompasses an alignment-hardened layer obtained by hardening a liquid crystal monomer, as described below. Typically, rod-shaped liquid crystal compounds are aligned in the slow axis direction of the retardation film (homogeneous alignment). Examples of rod-shaped liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably polymerizable. If the liquid crystal compound is polymerizable, the alignment state of the liquid crystal compound can be fixed by aligning the liquid crystal compound and then polymerizing it.

[0040] The alignment and solidification layer of the liquid crystal compound (liquid crystal alignment and solidification layer) can be formed by performing an alignment treatment on the surface of a predetermined substrate, applying a coating liquid containing a liquid crystal compound to the surface to align the liquid crystal compound in a direction corresponding to the alignment treatment, and fixing the alignment state. Any appropriate alignment treatment can be used as the alignment treatment. Specific examples include mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment. Specific examples of mechanical alignment treatment include rubbing 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 oblique vapor deposition and photoalignment treatment. Any appropriate treatment conditions can be used for the various alignment treatments depending on the purpose.

[0041] The alignment of liquid crystal compounds is achieved by treating them at a temperature at which they exhibit a liquid crystal phase depending on the type of liquid crystal compound. By performing such temperature treatment, the liquid crystal compounds assume a liquid crystal state and are aligned in accordance with the alignment treatment direction on the substrate surface.

[0042] In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is polymerizable or crosslinkable, the alignment state is fixed by subjecting the liquid crystal compound aligned as described above to a polymerization treatment or a crosslinking treatment.

[0043] Any suitable liquid crystal polymer and / or liquid crystal monomer can be used as the liquid crystal compound. The liquid crystal polymer and the liquid crystal monomer can be used alone or in combination. Specific examples of liquid crystal compounds and methods for producing a liquid crystal alignment solidified layer are described in, for example, JP 2006-163343 A, JP 2006-178389 A, and WO 2018 / 123551 A. The descriptions in these publications are incorporated herein by reference.

[0044] When the other retardation layer is a layer of solidified alignment of a liquid crystal compound, its thickness is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and still more preferably 1 μm to 4 μm.

[0045] In the manufacture of the above-mentioned retardation film, by changing the forming material of each retardation layer, manufacturing conditions, etc., it is possible to change the RS of the obtained retardation layer.For example, in a retardation film that includes a retardation layer that is a stretched film of a resin film, RS tends to be small by increasing the film thickness of the retardation layer, reducing the stretching ratio, etc.In addition, in the case of a resin film that includes a polycarbonate-based resin, RS tends to be small by increasing the content ratio of the structural unit derived from a fluorene-based dihydroxy compound.On the other hand, a retardation film that is a liquid crystal alignment solidification layer can have a very small RS.

[0046] The protective member typically includes a substrate. The substrate may be composed of any appropriate film. Examples of materials that form the main component of the film constituting the substrate include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, cycloolefin-based resins such as polynorbornene, polyolefin-based, (meth)acrylic, and acetate-based resins. The thickness of the substrate is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and even more preferably 15 μm to 35 μm.

[0047] B. Display System FIG. 3 is a schematic diagram showing the overall configuration of a display system according to one embodiment of the present invention, illustrating the arrangement and shape of each component of the display system. The display system 10 includes a display element 12, a reflective polarizing element 14, a first lens unit 16 having a curved main surface, a half mirror 18, a first phase difference element 20, a second phase difference element 22, and a second lens unit 24. The reflective polarizing element 14 is disposed in front of the display surface 12a of the display element 12 and can reflect light emitted from the display element 12. The first lens unit 16 is disposed on the optical path between the display element 12 and the reflective polarizing element 14, and the half mirror 18 is disposed between the display element 12 and the first lens unit 16. The first phase difference element 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second phase difference element 22 is disposed on the optical path between the half mirror 18 and the reflective polarizing element 14. Although not shown, from the viewpoint of improving visibility, the display system 10 may further include an absorptive polarizing member. The absorptive polarizing member may be disposed in front of the reflective polarizing member 14 such that the reflection axis of the reflective polarizing member 14 and the absorption axis of the absorptive polarizing member are approximately parallel to each other.

[0048] The half mirror or the components arranged forward from the first lens unit (in the illustrated example, the half mirror 18, first lens unit 16, second λ / 4 member 22, reflective polarizing member 14, and second lens unit 24) may be collectively referred to as the lens unit (lens unit 4).

[0049] The display element 12 is, for example, a liquid crystal display or an organic EL display, and has a display surface 12 a for displaying an image. The light emitted from the display surface 12 a passes through, for example, a polarizing member that may be included in the display element 12, and is converted into first linearly polarized light.

[0050] The first phase difference member 20 includes a first λ / 4 member that can convert first linearly polarized light incident on the first phase difference member 20 into first circularly polarized light. The first phase difference member 20 may be provided integrally with the display element 12.

[0051] The half mirror 18 transmits the light emitted from the display element 12 and reflects the light reflected by the reflective polarizing member 14 back toward the reflective polarizing member 14. The half mirror 18 is provided integrally with the first lens portion 16.

[0052] The second phase difference member 22 includes a second λ / 4 member that can transmit light reflected by the reflective polarizing member 14 and the half mirror 18 through the reflective polarizing member 14. When the second phase difference member does not include any member other than the second λ / 4 member, the second phase difference member may correspond to the second λ / 4 member. The second phase difference member 22 is provided integrally with the first lens portion 16.

[0053] The first circularly polarized light emitted from the first λ / 4 element included in the first phase difference element 20 passes through the half mirror 18 and the first lens portion 16, and is converted into the second linearly polarized light by the second λ / 4 element included in the second phase difference element 22. The second linearly polarized light emitted from the second λ / 4 element is reflected toward the half mirror 18 without passing through the reflective polarizing element 14. At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing element 14 is the same as the reflection axis of the reflective polarizing element 14. Therefore, the second linearly polarized light incident on the reflective polarizing element 14 is reflected by the reflective polarizing element 14.

[0054] The second linearly polarized light reflected by the reflective polarizing element 14 is converted into second circularly polarized light by the second λ / 4 element included in the second phase difference element 22, and the second circularly polarized light output from the second λ / 4 element passes through the first lens unit 16 and is reflected by the half mirror 18. The second circularly polarized light reflected by the half mirror 18 passes through the first lens unit 16 and is converted into third linearly polarized light by the second λ / 4 element. The third linearly polarized light is transmitted through the reflective polarizing element 14. At this time, the polarization direction of the third linearly polarized light incident on the reflective polarizing element 14 is the same direction as the transmission axis of the reflective polarizing element 14. Therefore, the third linearly polarized light incident on the reflective polarizing element 14 is transmitted through the reflective polarizing element 14.

[0055] The light transmitted through the reflective polarizing member 14 passes through the second lens portion 24 (the absorptive polarizing member and the second lens portion 24 ) and enters the eye 26 of the user.

[0056] The absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 14 may be arranged substantially parallel to each other or substantially perpendicular to each other. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the first λ / 4 member is, for example, 40° to 50°, or may be 42° to 48°, or may be approximately 45°. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the second λ / 4 member is, for example, 40° to 50°, or may be 42° to 48°, or may be approximately 45°.

[0057] The in-plane retardation Re(550) of the first λ / 4 component is, for example, 100 nm to 190 nm, or may be 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The first λ / 4 component preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light. The Re(450) / Re(550) of the first λ / 4 component may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

[0058] The in-plane retardation Re(550) of the second λ / 4 component is, for example, 100 nm to 190 nm, or may be 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The second λ / 4 component preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases with the wavelength of the measurement light. The Re(450) / Re(550) of the second λ / 4 component may be, for example, 0.75 or greater but less than 1, or 0.8 or greater but less than 0.95. Unless otherwise specified, the in-plane retardation of the second λ / 4 component is the in-plane retardation measured at a portion corresponding to the center of the first lens component. The center of the first lens component may be a portion that is generally recognized as the center. For example, the center of the first lens component may be the center of a circumscribed circle of its planar shape.

[0059] The absolute value of the difference between the in-plane retardation Re(550) of the first λ / 4 member and the in-plane retardation Re(550) of the second λ / 4 member is, for example, 3.5 nm or less, preferably 3.0 nm or less, more preferably 2.5 nm or less, even more preferably 2.0 nm or less, particularly preferably 1.5 nm or less, and most preferably 1.0 nm or less.

[0060] The in-plane retardation Re(550) of the first λ / 4 member and the in-plane retardation Re(550) of the second λ / 4 member 22 preferably satisfy the following formula (I) (in formula (I), (a) is the in-plane retardation Re(550) of the first λ / 4 member, and (b) is the in-plane retardation Re(550) of the second λ / 4 member): ((a)-(b)) / ((a)+(b) / 2)≦0.02... (I), more preferably ((a)-(b)) / ((a)+(b) / 2)≦0.015, and even more preferably ((a)-(b)) / ((a)+(b) / 2)≦0.01.

[0061] In the display system 10, the second retardation member 22 is composed of the retardation film described in Section A (specifically, a retardation film including a retardation layer A that is a positive C plate and a retardation layer B that is a λ / 4 member), and is integrated with the first lens unit 16 having a curved surface. The integration of the second retardation member 22 and the first lens unit 16 can be achieved by integrating the above-mentioned retardation film as the second retardation member 22 with the first lens unit. The second retardation member (the retardation film described in Section A) 22 can be integrated with the first lens unit 16 as an optical laminate that optionally further includes other optical members and has an adhesive layer (e.g., a pressure-sensitive adhesive layer) as the outermost layer, for example.

[0062] The radius of curvature of the curved surface of the first lens portion 16 is, for example, 20 mm or more, for example, 25 mm or more, or for example, 30 mm or more, and is, for example, 150 mm or less, preferably 125 mm or less, more preferably 110 mm or less, and may be 90 mm or less. The diameter (major axis) of the first lens portion 16 may be, for example, 20 mm to 80 mm, or for example, 30 mm to 70 mm. In the illustrated example, the second retardation member 22 is integrated with the concave surface of the first lens portion 16, but it may also be integrated with the convex surface. The method for integrating the second retardation member or the optical laminate with the first lens portion is not particularly limited, and for example, the same method as the method for integrating the retardation film with a member having a curved surface described in Section A can be used.

[0063] FIG. 4 is a schematic cross-sectional view and an enlarged view of a main portion illustrating an example of the configuration of an integrated product 200 in which an optical laminate 70 including a second phase difference member 22 (100) and a first lens portion 16 are integrated. In the optical laminate 70, the second phase difference member 22 (100) is arranged so that the phase difference layer B (second λ / 4 member) is located forward of the phase difference layer A (positive C plate). The optical laminate 70 further includes a second protective member 74 arranged on the phase difference layer B side of the second phase difference member 22 (100). The second phase difference member 22 (100) and the second protective member 74 are typically laminated via an adhesive layer (adhesive layer, pressure-sensitive adhesive layer, etc.). The optical laminate 70 further includes a second pressure-sensitive adhesive layer 76 on the phase difference layer A side of the second phase difference member 22 (100). The optical laminate 70 can be bonded to the first lens portion 16 by the second adhesive layer 76 so as to conform to the concave surface 16 a of the first lens portion 16 .

[0064] The second protective member typically includes a substrate. The substrate may be composed of any appropriate film. Examples of materials that form the main component of the film constituting the substrate include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, cycloolefin-based resins such as polynorbornene, polyolefin-based, (meth)acrylic, and acetate-based resins. The thickness of the substrate is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and even more preferably 15 μm to 35 μm.

[0065] The second protective member preferably has a substrate and a surface treatment layer formed on the substrate. The second protective member having the surface treatment layer can be disposed so that the surface treatment layer is located on the front side. The surface treatment layer can have any appropriate function. For example, from the viewpoint of improving visibility, the surface treatment layer preferably has an anti-reflection function. The surface treatment layer may also include a hard coat layer. The thickness of the surface treatment layer is preferably 1 μm to 20 μm, more preferably 2 μm to 15 μm, and even more preferably 3 μm to 10 μm.

[0066] The adhesive constituting the second adhesive layer typically contains a (meth)acrylic polymer, a urethane polymer, a silicone polymer, or a rubber polymer as a base polymer. Preferably, the adhesive is a (meth)acrylic adhesive containing a (meth)acrylic polymer as a main component. The thickness of the second adhesive layer is, for example, 12 μm or more, preferably 15 μm or more, and, for example, 100 μm or less, preferably 80 μm or less.

[0067] In the display system 10, the first retardation member 20 may also be composed of the retardation film described in Section A. In this case, the first λ / 4 member (the retardation film described in Section A) 20 (100) may be integrated with the display surface 12a of the display element 12. The display surface of the display element may be flat. As described above, the retardation film described in Section A can suppress the occurrence of retardation unevenness associated with integration with a curved member. Therefore, when the retardation film described in Section A is integrated as the first λ / 4 member and the second λ / 4 member along the flat display surface of the display element and the curved surface of the first lens portion, respectively, a display system with a small difference in in-plane retardation between the two can be preferably obtained. In such a display system, the difference between the in-plane retardation Re(550) at the center of the retardation film integrated with the display element and the in-plane retardation Re(550) at the center of the retardation film integrated with the first lens portion is, for example, 6 nm or less, preferably 5 nm or less, more preferably 4 nm or less, and even more preferably 3.5 nm or less, and may be, for example, 3.0 nm or less, 2.5 nm or less, 2.0 nm or less, 1.5 nm or less, or 1.0 nm or less.

[0068] The first λ / 4 member 20 may be integrated with the display element 12 as an optical laminate that further includes any other appropriate optical members and has an adhesive layer (for example, a pressure-sensitive adhesive layer) as the outermost layer.

[0069] FIG. 5 is a schematic cross-sectional view illustrating an example of the configuration of an optical laminate 80 including a first retardation member (a retardation film described in Section A) 20 (100). In the optical laminate 80, the first retardation member 20 (100) is disposed such that the retardation layer A (positive C plate) is located in front of the retardation layer B (second λ / 4 member). The optical laminate includes a polarizing member 82 disposed on the retardation layer B (second λ / 4 member) side of the first retardation member, and a protective member disposed on the retardation layer A (positive C plate). The polarizing member 82 is a polarizing member that can be included in the display element 12. The optical laminate 80 further includes a pressure-sensitive adhesive layer 88 on the side of the polarizing member 82 opposite to the side on which the first retardation member is disposed. The optical laminate 80 can be attached to the front side of a display element by the pressure-sensitive adhesive layer 88.

[0070] The polarizing member is typically an absorptive polarizing member and may include a resin film containing a dichroic material (sometimes referred to as an absorptive polarizing film). The thickness of the absorptive polarizing film is, for example, 1 μm or more and 20 μm or less, or may be 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.

[0071] The absorptive polarizing film may be made from a single layer of resin film or may be made from a laminate of two or more layers.

[0072] When the absorptive polarizing film is produced from a single-layer resin film, for example, an absorptive polarizing film can be obtained by subjecting a hydrophilic polymer film such as a polyvinyl alcohol (PVA)-based film, a partially formalized PVA-based film, or a partially saponified ethylene-vinyl acetate copolymer-based film to a dyeing treatment with iodine or a dichroic substance such as a dichroic dye, a stretching treatment, etc. Among these, an absorptive polarizing film obtained by dyeing a PVA-based film with iodine and uniaxially stretching it is preferred.

[0073] The dyeing with iodine is carried out, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment or while dyeing. Alternatively, the PVA-based film may be dyed after stretching. If necessary, the PVA-based film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like.

[0074] Examples of laminates produced using the two or more layer laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, and a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. An absorptive polarizing film obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the solution to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer, and then stretching and dyeing the laminate to convert the PVA-based resin layer into an absorptive polarizing film. In this embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. The stretching typically involves immersing the laminate in an aqueous boric acid solution to stretch it. Furthermore, the stretching may further include in-air stretching of the laminate at a high temperature (e.g., 95°C or higher) before stretching in the boric acid aqueous solution, as necessary. In addition, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which the laminate is heated while being transported in the longitudinal direction, thereby shrinking the laminate by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an auxiliary in-air stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment, in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of the PVA, even when the PVA is coated on a thermoplastic resin, thereby achieving high optical properties. Furthermore, by simultaneously increasing the orientation of the PVA in advance, problems such as a decrease in orientation or dissolution of the PVA when immersed in water in the subsequent dyeing or stretching steps can be prevented, thereby achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disordering of the polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of the absorptive polarizing film obtained through treatment steps in which the laminate is immersed in a liquid, such as a dyeing treatment and an underwater stretching treatment.Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through a drying shrinkage treatment.The obtained resin substrate / absorptive polarizing film laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the absorptive polarizing film), or any suitable protective layer may be laminated depending on the purpose on the surface obtained by peeling the resin substrate from the resin substrate / absorptive polarizing film laminate or on the surface opposite to the peeled surface. Details of such methods for producing an absorptive polarizing film are described in, for example, JP-A-2012-73580 and Japanese Patent No. 6,470,455. The entire disclosures of these publications are incorporated herein by reference.

[0075] The crossed transmittance (Tc) of the absorptive polarizing element (absorptive polarizing film) is preferably 0.5% or less, more preferably 0.1% or less, and even more preferably 0.05% or less. The single transmittance (Ts) of the absorptive polarizing element (absorptive polarizing film) is, for example, 41.0% to 45.0%, and preferably 42.0% or more. The polarization degree (P) of the absorptive polarizing element (absorptive polarizing film) is, for example, 99.0% to 99.997%, and preferably 99.9% or more.

[0076] The crossed transmittance, single transmittance, and degree of polarization can be measured, for example, using an ultraviolet-visible spectrophotometer. The degree of polarization P can be calculated from the obtained Tp and Tc by measuring the single transmittance Ts, parallel transmittance Tp, and crossed transmittance Tc using an ultraviolet-visible spectrophotometer, using the following formula: Ts, Tp, and Tc are Y values ​​measured using a 2-degree visual field (C light source) according to JIS Z 8701 and corrected for visibility. Degree of polarization P (%) = {(Tp - Tc) / (Tp + Tc)} １／２ ×100

[0077] The same explanations as for the second protective member and the second pressure-sensitive adhesive layer can be applied to the first protective member and the first pressure-sensitive adhesive layer, respectively.

[0078] C. Retardation Film Set According to another aspect of the present invention, there is provided a set of two retardation films, each of which independently includes two or more retardation layers, including a retardation layer B having an in-plane retardation Re(550) of 100 nm to 190 nm, and the absolute value of the sum of the retardation change values ​​RS of the retardation layers is 3.0 or less. The difference in the in-plane retardation Re(550) of the retardation layer B in the two retardation films included in the set is, for example, 10 nm or less, preferably 5 nm or less, more preferably 0 nm to 3 nm. Each of the two retardation films included in the set is preferably the retardation film described in Section A.

[0079] 4, the display system may include a planar first retardation member and a curved second retardation member. In such a display system, by using one of the retardation films in the set to form the first retardation member and the other to form the second retardation member, even when the second retardation member deforms to follow the curved surface of the first lens unit, changes and unevenness in the in-plane retardation of the second λ / 4 member are reduced. As a result, the difference in the in-plane retardation between the first λ / 4 member and the second λ / 4 member can be reduced (for example, the absolute value of the difference in in-plane retardation Re(550) is ≦3.5 nm), and as a result, a display system with excellent visibility can be preferably obtained.

[0080] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The thickness and retardation are values ​​measured by the following measurement methods. <Thickness> Thicknesses of 10 μm or less were measured using a scanning electron microscope (manufactured by JEOL Ltd., product name "JSM-7100F"). Thicknesses of more than 10 μm were measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). <Retardation> In-plane retardation at 23°C was measured using a birefringence mapping measurement device (manufactured by Photoron Co., Ltd., product name "KAMAKIRI X stage".

[0081] [Production Example 1] Production of Positive C Plate (I) A liquid crystal coating solution was prepared by dissolving 20 parts by mass of a side-chain liquid crystal polymer represented by the following chemical formula (1) (in the formula, the numbers 65 and 35 indicate the mole percentages of the monomer units, and are conveniently represented as a block polymer; weight-average molecular weight 5000), 80 parts by mass of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name Paliocolor LC242), and 5 parts by mass of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name Irgacure 907) in 200 parts by mass of cyclopentanone. The coating liquid was then applied to a substrate film (norbornene-based resin film: manufactured by Zeon Corporation, trade name "Zeonex") using a bar coater, and the liquid crystal was aligned by heating and drying at 80°C for 4 minutes. The liquid crystal layer was irradiated with ultraviolet light to harden it, forming a 4 μm-thick retardation member on the substrate. The retardation member thus obtained had a refractive index of nz > nx = ny. The retardation Rth(590) of the retardation member (positive C plate) in the thickness direction was 83 nm.

[0082] [Production Example 2] Production of Positive C Plate (II) 48 parts by weight of hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: Metrose 60SH-50), 15,601 parts by weight of distilled water, 8,161 parts by weight of diisopropyl fumarate, 240 parts by weight of 3-ethyl-3-oxetanylmethyl acrylate, and 45 parts by weight of the polymerization initiator t-butyl peroxypivalate were placed in an autoclave equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a thermometer. Nitrogen bubbling was performed for 1 hour, and then the mixture was stirred at 49°C for 24 hours to carry out radical suspension polymerization. The mixture was then cooled to room temperature, and the suspension containing the resulting polymer particles was centrifuged. The resulting polymer was washed twice with distilled water and twice with methanol and then dried under reduced pressure. The resulting fumarate ester-based resin was dissolved in a toluene-methyl ethyl ketone mixed solution (toluene / methyl ethyl ketone 50% by weight / 50% by weight) to prepare a 20% solution. Furthermore, 5 parts by weight of tributyl trimellitate as a plasticizer was added to 100 parts by weight of the fumaric acid ester resin to prepare a dope. A biaxially stretched polyester (polyethylene terephthalate / isophthalate copolymer) film (thickness: 75 μm) was used as the support film. The prepared dope was applied to the support film so that the film thickness after drying would be 20 μm, and then dried at 140°C. The coating film (positive C plate) after drying had an Re(550) of 0 nm and an Rth(550) of -83 nm.

[0083] [Production Example 3] Production of λ / 4 member (I) A batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled to 100°C was charged with 29.60 parts by weight (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by weight (0.200 mol) of isosorbide (ISB), 42.28 parts by weight (0.139 mol) of spiroglycol (SPG), 63.77 parts by weight (0.298 mol) of diphenyl carbonate (DPC), and 1.19 × 10 mol of calcium acetate monohydrate as a catalyst. －２ Parts by weight (6.78 x 10 －５mol) was charged. After purging the reactor with nitrogen under reduced pressure, heating was performed with a heat medium, and stirring was initiated when the internal temperature reached 100°C. 40 minutes after the start of the temperature increase, the internal temperature reached 220°C, and while controlling to maintain this temperature, pressure reduction was initiated. 90 minutes after reaching 220°C, the pressure was reduced to 13.3 kPa. Phenol vapor by-produced during the polymerization reaction was introduced into a reflux condenser at 100°C, and a small amount of monomer components contained in the phenol vapor were returned to the reactor, while uncondensed phenol vapor was introduced into a condenser at 45°C and recovered. Nitrogen was introduced into the first reactor, and the pressure was temporarily restored to atmospheric pressure. The oligomerized reaction liquid in the first reactor was then transferred to the second reactor. Next, heating and pressure reduction in the second reactor were initiated, and the internal temperature reached 240°C and the pressure reached 0.2 kPa in 50 minutes. Polymerization was then allowed to proceed until the predetermined stirring power was achieved. When the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, and the resulting polyester carbonate resin was extruded into water and cut into strands to obtain pellets. The resulting polyester carbonate resin (pellets) was vacuum-dried at 80 ° C for 5 hours, and then a film-forming device equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250 ° C), a T-die (width 200 mm, setting temperature: 250 ° C), a chill roll (setting temperature: 120-130 ° C), and a winder was used to produce a long resin film with a thickness of 130 μm. The obtained long resin film was stretched in the width direction at a stretching temperature of 140 ° C and a stretch ratio of 2.7 times, and wound into a roll. This resulted in a λ / 4 member with a thickness of 47 μm, an Re (590) of 140 nm, and an Nz coefficient of 1.2. The retardation layer had an Re(450) / Re(550) of 0.859, which indicated an inverse dispersion wavelength characteristic.

[0084] [Production Example 4] Production of λ / 4 Member (II) 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), then heated to 60°C and stirred to dissolve. The solution of the above compounds was then returned to room temperature, and 3 parts by weight of Irgacure 907 (manufactured by BASF Japan), 0.2 parts by weight of Megafac F-554 (manufactured by DIC), and 0.1 parts by weight of p-methoxyphenol (MEHQ) were added to the solution and further stirred. The solution after stirring was transparent and homogeneous. The resulting solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. The polyimide solution for the alignment film was also spin-coated onto a 0.7 mm thick glass substrate, dried at 100°C for 10 minutes, and then baked at 200°C for 60 minutes to obtain a coating film. The resulting coating film was subjected to rubbing treatment using a commercially available rubbing device to form an alignment film. Next, the polymerizable composition obtained above was applied to a substrate (substantially an alignment film) by spin coating, and dried at 100°C for 2 minutes. After cooling the resulting coating film to room temperature, it was irradiated with 30 mW / cm using a high-pressure mercury lamp. ２ The film was irradiated with ultraviolet light at an intensity of 1000 nm for 30 seconds to obtain a retardation layer (thickness: 3 μm) that was an alignment and solidification layer of the liquid crystal compound. The in-plane retardation Re(590) of the retardation layer was 140 nm. The Re(450) / Re(550) of the retardation layer was 0.851, showing reverse dispersion wavelength characteristics. This retardation layer can function as a λ / 4 component.

[0085]

[0086] [Example 1] The λ / 4 member (I) obtained in Production Example 3 and the positive C plate (II) obtained in Production Example 2 were laminated together via an acrylic adhesive (thickness 5 μm) to obtain a retardation film.

[0087] [Example 2] The λ / 4 member (II) obtained in Production Example 4 and the positive C plate (I) obtained in Production Example 1 were laminated together via an acrylic adhesive (thickness 5 μm) to obtain a retardation film.

[0088] [Example 3] The λ / 4 member (II) obtained in Production Example 4 and the positive C plate (II) obtained in Production Example 2 were laminated together via an acrylic adhesive (thickness 5 μm) to obtain a retardation film.

[0089] Comparative Example 1 In the same manner as in Production Example 3, a retardation film (λ / 4 member (I)) was obtained.

[0090] [Comparative Example 2] The λ / 4 member (I) obtained in Production Example 3 and the positive C plate (I) obtained in Production Example 1 were laminated together via an acrylic adhesive (thickness 5 μm) to obtain a retardation film.

[0091] <Retardation Change Value RS> The retardation change value RS of each retardation layer constituting the retardation film of the Examples and Comparative Examples was measured by the following method. The retardation layer was attached to an acrylic film (Re(550)≒0 nm) via an acrylic pressure-sensitive adhesive layer (thickness 5 μm) to obtain a laminate. The obtained laminate was cut into a length of 150 mm and a width of 15 mm so that the slow axis direction of the retardation film was the longitudinal direction, to obtain a sample. The acrylic film is a film that causes almost no retardation change when tensioned as described below is applied. A tension meter (manufactured by MYCARBON, product name "Digital Luggage Scale") was used to apply tension to the obtained sample in the longitudinal direction. The in-plane retardation (Re(550)) was measured using a retardation measurement device (manufactured by Axometrics, product name: Axo Scan) at tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg. The Re(550) values ​​measured at each tension were plotted to create an approximate line, with tension as the x-axis and Re(550) as the y-axis, and the slope of the approximate line was taken as the retardation change value RS.

[0092] <Elongation at Break> The elongation at break of the positive C plate (strip-shaped, 4 mm wide) constituting the retardation film of each of Examples and Comparative Examples was measured by measuring an SS curve using a thermomechanical analyzer (TMA, product name "TMA Q400", manufactured by TA Instruments) under conditions of a measurement temperature of 23°C, a chuck distance of 8 mm, and a tensile speed of 0.1 strain / min, and the elongation at the time when the evaluation sample broke was taken as the elongation at break.

[0093] <Preparation and Evaluation of Curved Surface Integrated Product> 1-1. Preparation of Lens with Retardation Film An acrylic adhesive layer (15 μm thick) was provided on the surface of the retardation film obtained in the Examples and Comparative Examples (on the retardation layer A (positive C plate) side of the retardation film in Example and Comparative Example 2), and the film was bonded to the concave surface of a lens having a circular shape with a diameter of 65 mm in plan view and a curvature radius of 75 mm, via the adhesive layer. Specifically, as shown in FIG. 1, the retardation film with the adhesive layer was set so that the surface of the adhesive layer was in contact with the edge of the concave side of the lens, and in a softened state by heating to 120°C, it was pressed into the concave side to be bonded to the concave surface of the lens. This resulted in a lens with a retardation film, which was an integrated product of the retardation film and the lens. 1-2. Measurement of Retardation Irregularity The in-plane retardation Re (543) was measured over the entire surface of the retardation film for the lenses with retardation film obtained in the Examples and Comparative Examples. In the in-plane retardation distribution thus obtained, the difference in in-plane retardation Re(543) between the center and the other portions (outer portions) was detected, and the maximum value was taken as the in-plane retardation unevenness. Note that the in-plane retardation unevenness (|Re(543) center portion - Re(543) outer portion|) can be evaluated as "poor (x)" if it exceeds 15 nm, "fair (△)" if it exceeds 10 nm and is 15 nm or less, and "good (◯)" if it is 10 nm or less. 2-1. Preparation of Lens with Retardation Film An acrylic pressure-sensitive adhesive layer (thickness 15 μm) was provided on one side of the retardation film obtained in the Examples and Comparative Examples, and the film was bonded via the pressure-sensitive adhesive layer to the concave surface of a lens having a circular shape in plan view with a diameter of 50 mm and a concave surface with a radius of curvature of 40 mm. Specifically, as shown in Figure 1, a retardation film with an adhesive layer was set so that the surface of the adhesive layer was in contact with the edge of the concave side of the lens, and in a softened state by heating to 120°C, it was pressed into the concave side to be bonded to the concave surface of the lens. In this way, a lens with a retardation film, which is an integrated product of the retardation film and the lens, was obtained. 2-2. Crack Evaluation The obtained lens with a retardation film was visually inspected to determine whether or not there were cracks.

[0094] <Smoothness> The smoothness of the retardation film was measured using a phase-shifting laser interferometer (manufactured by Zygo, product name "DynaFiz"). Specifically, the retardation film was laminated on a microslide glass (manufactured by Matsunami Glass Industry Co., Ltd., product name "S200200") to prevent the intrusion of foreign matter, bubbles, and deformation streaks. Next, in order to remove the influence of minute bubbles, degassing was performed using a pressurized degassing device (autoclave). The degassing conditions were 50 ° C, 0.5 MPa, and 30 minutes. After degassing, the sample was allowed to cool at room temperature for 30 minutes or more to obtain a measurement sample. The measurement sample was placed on a measurement table with a vibration-isolating table, and a single-wavelength (633 nm) laser was used to interfere with a standard whose flatness was guaranteed, and the relative displacement within a predetermined area (a circle of 30 mmφ) was measured. For the analysis, the smoothness of the retardation film (unit: arcmin) was defined as doubling the angle index "Slope magnitude RMS" obtained by extracting frequency values ​​of 0.1 / mm to 1 / mm (corresponding to 2σ).

[0095] The results are shown in Table 1.

[0096] The retardation film according to the embodiment of the present invention can be used in a display such as VR goggles, for example.

[0097] REFERENCE SIGNS LIST 10 Display system 12 Display element 14 Reflective polarizing member 16 First lens portion 18 Half mirror 20 First λ / 4 member 22 Second λ / 4 member 24 Second lens portion 100 Retardation film A Retardation layer A B Retardation layer B

Claims

1. A method for manufacturing a display system for displaying an image to a user, the display system comprising: a display element having a display surface that emits light representing an image forward via a polarizing member; a reflective polarizing member arranged in front of the display element and reflecting the light emitted from the display element; a first lens portion arranged on an optical path between the display element and the reflective polarizing member and having a curved main surface; a half mirror arranged between the display element and the first lens portion, transmitting the light emitted from the display element and reflecting the light reflected by the reflective polarizing member towards the reflective polarizing member; a first phase difference member arranged on the optical path between the display element and the half mirror and including a first λ / 4 member; and a second phase difference member arranged on the optical path between the half mirror and the reflective polarizing member and including a second λ / 4 member, a retardation film including two or more retardation layers including a retardation layer having an in-plane retardation Re(550) of 100 nm to 190 nm, and an absolute value of a sum of retardation change values ​​RS of the retardation layers being 3.0 or less (wherein the retardation change value RS is a slope of an approximation line of the in-plane retardation Re(550) of the retardation layers measured under conditions of applying tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg) to the first lens portion as the second retardation member, the manufacturing method comprising the steps of: integrating the retardation film with the first lens portion as the second retardation member; 2. The manufacturing method according to claim 1, comprising: preparing two of the retardation films; integrating one of the retardation films with the display element as the first retardation member; and integrating the other of the retardation films with the first lens portion as the second retardation member.

3. A method for manufacturing a lens unit used in a display system that displays an image to a user, the lens unit comprising: a reflective polarizing element that reflects light that is emitted forward from a display surface of a display element that displays an image and that has passed through a polarizing element and a first λ / 4 element; a first lens unit that is disposed on an optical path between the display element and the reflective polarizing element and has a curved main surface; a half mirror that is disposed between the display element and the first lens unit and transmits the light emitted from the display element and reflects the light reflected by the reflective polarizing element toward the reflective polarizing element; and a second phase difference element that is disposed on the optical path between the half mirror and the reflective polarizing element and includes a second λ / 4 element, a retardation film including two or more retardation layers including a retardation layer having an in-plane retardation Re(550) of 100 nm to 190 nm, and an absolute value of a sum of retardation change values ​​RS of the retardation layers being 3.0 or less (wherein the retardation change value RS is a slope of an approximation line of the in-plane retardation Re(550) of the retardation layers measured under conditions of applying tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg) to the first lens portion as the second retardation member, the manufacturing method comprising the steps of: integrating the retardation film with the first lens portion as the second retardation member; 4. A retardation film comprising two or more retardation layers, the total absolute value of retardation change values ​​RS of the retardation layers being 3.0 or less, and the retardation change value RS being the slope of an approximation line of the in-plane retardation Re(550) of the retardation layers measured under tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg.

5. The retardation film according to claim 4, comprising a retardation layer A formed from a resin having negative birefringence and having refractive index characteristics that satisfy the relationship nz>nx=ny.

6. The retardation film according to claim 5, further comprising another retardation layer, wherein the ratio of the thickness of the another retardation layer to the thickness of the retardation layer A (another retardation layer / retardation layer A) is 10 or less.

7. The retardation film according to claim 5, wherein the retardation layer A has a breaking elongation of 1% or more at 23° C.

8. The retardation film according to claim 4, further comprising another retardation layer, wherein the in-plane retardation Re(550) of the another retardation layer is 100 nm to 160 nm.

9. The retardation film according to claim 4, having a surface smoothness of 0.4 arcmin or less.

10. The retardation film according to claim 4, which is integrated with a member having a curved surface.

11. The retardation film according to claim 10, wherein the radius of curvature of the curved surface of the member having the curved surface is 20 mm or more.

12. A display system comprising: a display element having a display surface that emits light representing an image forward via a polarizing member; a reflective polarizing member arranged in front of the display element and reflecting the light emitted from the display element; a first lens section arranged on an optical path between the display element and the reflective polarizing member and having a curved main surface; a half mirror arranged between the display element and the first lens section, transmitting the light emitted from the display element and reflecting the light reflected by the reflective polarizing member toward the reflective polarizing member; a first phase difference member arranged on the optical path between the display element and the half mirror and including a first λ / 4 member; and a second phase difference member arranged on the optical path between the half mirror and the reflective polarizing member and including a second λ / 4 member, the retardation film according to claim 4 being used integrally with the first lens section as the second phase difference member.

13. A display system comprising: a display element having a display surface that emits light representing an image forward via a polarizing member; a reflective polarizing member arranged in front of the display element and reflecting the light emitted from the display element; a first lens section arranged on an optical path between the display element and the reflective polarizing member and having a curved main surface; a half mirror arranged between the display element and the first lens section, transmitting the light emitted from the display element and reflecting the light reflected by the reflective polarizing member toward the reflective polarizing member; a first phase difference member arranged on the optical path between the display element and the half mirror and including a first λ / 4 member; and a second phase difference member arranged on the optical path between the half mirror and the reflective polarizing member and including a second λ / 4 member, wherein the second phase difference member and the first lens section are integrated, comprising a set of a first phase difference film for constituting the first phase difference member and a second phase difference film for constituting the second phase difference member, The retardation film set includes a retardation film in which the first retardation film and the second retardation film each include two or more retardation layers including a retardation layer having an in-plane retardation Re(550) of 100 nm to 190 nm, and the absolute value of the sum of the retardation change values ​​RS of the retardation layers is 3.0 or less (wherein the retardation change value RS is the slope of an approximation line of the in-plane retardation Re(550) of the retardation layer measured under conditions of applying tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg).

Images