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

Abstract

To provide a retardation film capable of favorably achieving weight saving of a VR goggle while improving visibility, a retardation film set, or a manufacturing method of a lens part or a display system.SOLUTION: A manufacturing method of a display system is configured to display an image to a user. The manufacturing method includes integrating a retardation film, as a λ / 4 member, with a lens part. The retardation film includes two or more retardation layers. An absolute value of a total of phase difference change values RS of the retardation layer is 3.0 or less (in which the phase difference change values RS is an inclination of an approximation straight line of an in-plane phase difference Re(550) of the retardation film measured in a state applied with a tensile force of 0 kg, 0.5 kg, 1 kg, 1.5, kg and 2 kg).SELECTED DRAWING: Figure 4

Description

[Technical field]

[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. [Background technology]

[0002] Image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices), are rapidly becoming widespread. In image display devices, optical members such as polarizing members and phase difference members are generally used to realize image display and to improve the performance of the image display (see, for example, 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. Since VR goggles are being considered for use in various situations, there is a demand for them to be lightweight and have improved visibility. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-103286 A Summary of the Invention [Problem to be solved by the invention]

[0005] The weight of the VR goggles can be reduced by, for example, thinning the lenses used in the VR goggles. On the other hand, there is a demand for the development of optical members 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 manufacturing method for a lens portion or a display system that can effectively achieve weight reduction of VR goggles while improving visibility. [Means for solving the problem]

[0007] [1] A manufacturing method according to an embodiment of the present invention is a manufacturing method for 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 member; a reflective polarizing member arranged in front of the display element and reflecting the light emitted from the display element; a first lens unit 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 unit, transmitting the light emitted from the display element and reflecting the light reflected by the reflective polarizing member toward the reflective polarizing member; and a second retardation member arranged 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 a first retardation member arranged on an optical path between the half mirror and the reflective polarizing member and including a first λ / 4 member, the second retardation member including a first ... layer arranged 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 a first retardation layer arranged on an optical path between the half mirror and the reflective polarizing member and including a first λ / 4 member, the second retardation layer including a first retardation layer arranged on an optical path between the half mirror and the reflective polarizing member and including a first λ / 4 member, the second retardation layer including a first retardation layer arranged on an optical path between the half mirror and the reflective polarizing member and including a second λ / 4 member, the second retardation layer including a first retardation layer arranged on an optical path between the half mirror and the reflective polarizing member and including a first λ / 4 member, [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 member 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 member and a first λ / 4 member; a first lens unit that is disposed on an optical path between the display element and the reflective polarizing member and has a curved main surface; a half mirror that is disposed between the display element and the first lens unit, that transmits light emitted from the display element and reflects light reflected by the reflective polarizing member toward the reflective polarizing member; and and a second retardation member including a second λ / 4 member, the second retardation member being disposed on an optical path between the half mirror and the reflective polarizing member, the second retardation member including a second λ / 4 member, the second retardation member including a retardation layer having an in-plane retardation Re(550) of 100 nm to 190 nm, the 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, the absolute value of the sum of the retardation change values ​​RS of the retardation layers being 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) being 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, and 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 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 the above item [4] may include 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 the above [4] or [5] may further include another retardation layer, and a ratio of a thickness of the another retardation layer to a thickness of the retardation layer A (another retardation layer / retardation layer A) may be 10 or less. [7] In the retardation film according to any one of the above [4] to [6], 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 the above [4] to [7] 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 the above [4] to [8] may have a surface smoothness of 0.4 arcmin or less.

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

[11] In the retardation film according to the above

[10] , the curved surface of the member having the curved surface may have a radius of curvature of 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 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 arranged in front of the display element and reflecting the light emitted from the display element; a first lens unit having a curved main surface arranged on an optical path between the display element and the reflective polarizing member; a half mirror arranged between the display element and the first lens unit, 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 retardation member arranged on the optical path between the display element and the half mirror and including a first λ / 4 member; and a second retardation member arranged on the optical path between the half mirror and the reflective polarizing member and including a second λ / 4 member.

[13] A set of retardation films 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. A display system includes 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, 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 under conditions of applying tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg). Effect of the Invention

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

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

[0010] Hereinafter, the 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 be schematic in terms of the width, thickness, shape, etc. of each part compared to the embodiment, but they are merely examples and do not limit the interpretation of the present invention. In addition, in the drawings, the same or equivalent elements are given the same reference numerals, and duplicate descriptions 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 direction perpendicular to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane retardation measured with light of wavelength λ nm at 23° C. For example, "Re(550)" is the in-plane retardation measured with light of wavelength 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) Retardation in the thickness direction (Rth) "Rth(λ)" is the retardation in the thickness direction measured with light of wavelength λ nm at 23° C. For example, "Rth(550)" is the retardation in the thickness direction measured with light of wavelength 550 nm at 23° C. Rth(λ) is calculated by the formula: Rth(λ)=(nx-nz)×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 angles are referred to herein, the angles include both clockwise and counterclockwise angles relative to a reference direction, so for example, "45°" means ±45°.

[0012] A. Retardation film The retardation film according to the embodiment of the present invention includes two or more retardation layers (preferably two layers). The retardation film is provided in which the absolute value of the sum of the retardation change values ​​RS of the 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 where it is integrated with a member having a curved surface. 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, and can be an index of the degree of change in the in-plane retardation when tension is applied to the retardation film (as a result, the retardation layer). Specifically, a small RS means that the in-plane retardation is unlikely to change when tension is applied to the retardation layer. When integrated with a curved member, tension is applied to the retardation film, and as a result, the retardation of the retardation layer may change, but if the absolute value of the sum of the retardation change values ​​RS of each retardation layer is within the above range, the retardation change can be reduced.In addition, the dimensional change and retardation change 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. If it is within this range, the above-mentioned effect becomes prominent. The smaller the absolute value of the sum of the retardation change values ​​RS of each retardation layer, the more preferable, and the lower limit 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. In this range, the occurrence of retardation unevenness when integrated with a curved member can be suppressed. The surface smoothness can be measured by focusing the 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 further preferably 20 or less. The ISC value can be an index of smoothness or unevenness. If it is within such a range, the occurrence of retardation unevenness when 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, further 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 obtained by measuring the thickness of a first portion located in the plane of the retardation film and the thickness of a position spaced a predetermined distance (for example, 5 mm to 15 mm) from the first portion in any direction (for example, 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 further 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 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 member having a curved surface can be, for example, 20 mm to 80 mm, or for example, 30 mm to 70 mm. A preferable example of the 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 for explaining an example of a method for integrating a retardation film and a member having a curved surface. In FIG. 1(a), the retardation film 100 is arranged on the member L, which is an adherend, in the state of the retardation film 3 with the adhesive layer 2 provided on one side thereof. The member L is circular in plan view and has a concave shape on the top in cross-sectional view. The retardation film 3 with the adhesive layer can be arranged at a predetermined position by chucking its end to a fixing jig (not shown). The retardation film 3 with the adhesive layer is arranged at a position where the adhesive layer 2 contacts the edge of the concave surface of the member L, and is pressed into the concave surface side using a jig or the like in a state softened by heating, so that the film is bonded over the entire concave surface of the member L as shown in FIG. 1(b). Thereafter, as shown in FIG. 1(c), unnecessary parts of the retardation film 3 with the adhesive layer (for example, parts protruding from the member L in plan view) are removed to obtain an integrated product.

[0020] In the integration with the curved surface, typically, the retardation film may be stretched. For example, the retardation film is stretched from a planar shape corresponding to the planar shape of the member L to a curved shape along the curved shape of the member L. In this way, tension may be applied to the retardation film in the integration with the curved surface, and the retardation film may suppress a change in retardation due to the application of tension.

[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 Re(550) at the center 1c of the retardation film 100 and Re(550) at the other portion (outer portion) may be, for example, less than 15 nm, 10 nm or less, or 8 nm or less, and may be, for example, 2 nm or more. When stretched during integration with the member L, the in-plane retardation may vary within the plane (curved surface) of the retardation film. For example, in the curved retardation film after integration, the Re(550) of the portion far from the center may have a large difference from the Re(550) of the center. According to the retardation film, even when stretched during integration with the member L, the variation in the in-plane retardation within the plane can be reduced.

[0022] Typically, the retardation film A 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, further 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 suitable material that can satisfy the above characteristics. The retardation layer A can be formed, for example, from a resin film or an oriented solidified layer of a liquid crystal compound. A retardation film formed of a resin film has the advantage that it has excellent mechanical properties (e.g., breaking elongation) and is unlikely 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 a property that the refractive index in the direction perpendicular to the stretching direction is maximized when uniaxially stretched. 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, fumaric acid ester resins, and the like. Specific examples of resins having negative birefringence and methods for manufacturing positive C plates using the resins can be referred to the resins having negative birefringence and the methods for manufacturing positive C plates described in JP-A-2023-73125, JP-A-2021-76759, JP-T-2008-544304, JP-T-2008-544317, and the like. The above resin materials may be used alone or in combination of two or more kinds.

[0026] When tension is applied to the retardation layer A formed from a resin having negative birefringence, a retardation is generated in a 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, suppressing the change in retardation in the entire retardation film, and as a result, retardation unevenness can be prevented. This 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 a 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 a method for forming a positive C plate are described in

[0020] to

[0023] of JP2002-333642A.

[0028] and a method for forming the retardation layer.

[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, still 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 effects become prominent.

[0029] The retardation layer A has a breaking elongation at 23°C of 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 unlikely to crack even when applied to a curved surface can be obtained. The upper limit of the breaking elongation of the retardation layer A at 23°C is, for example, 5.0%. The method for measuring the breaking elongation will be described later.

[0030] When the retardation layer A is made 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 made 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 other retardation layer B (sometimes referred to as retardation layer B) may be, for example, a λ / 4 member. The other retardation layer may be formed from a stretched film of a resin film or an oriented 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 other retardation layer is, for example, 100 nm to 190 nm, may be 110 nm to 180 nm, may be 130 nm to 160 nm, or may be 135 nm to 155 nm. The other retardation layer 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 other 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 further 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 other 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 other 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 (absolute value of the sum of the retardation change values ​​RS of each retardation layer in the retardation film) / (ratio of the thickness of another retardation layer to the thickness of 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 unlikely to cause retardation unevenness even when applied to a curved surface can be obtained. The upper limit of the value calculated by (absolute value of the sum of the retardation change values ​​RS of each retardation layer in the retardation film) / (ratio of the thickness of another retardation layer to the thickness of retardation layer A) is, for example, 20.

[0036] Examples of the resin contained in the resin film constituting the other retardation layer include polycarbonate-based resins, polyester carbonate-based resins, polyester-based resins, polyvinyl acetal-based resins, polyarylate-based resins, cycloolefin-based resins, cellulose-based resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyether-based resins, polystyrene-based resins, and acrylic-based resins. These resins may be used alone or in combination (for example, blends, copolymerizations). When the retardation film shows reverse dispersion wavelength characteristics, a resin film containing a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter, sometimes simply referred to as a polycarbonate-based 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 a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from at least one dihydroxy compound selected from the group consisting of an alicyclic diol, an alicyclic dimethanol, a di-, tri- or polyethylene glycol, and an alkylene glycol or a spiro glycol. Preferably, the polycarbonate-based resin contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from an alicyclic dimethanol, and / or a structural unit derived from a di-, tri- or polyethylene glycol; more preferably, it contains a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from a di-, tri- or polyethylene glycol. The polycarbonate-based resin may contain a structural unit derived from another dihydroxy compound as necessary. Details of polycarbonate-based 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, and the descriptions in these publications are incorporated herein by reference.

[0038] When the retardation film constituting the separate 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 further preferably 40 μm to 70 μm.

[0039] The liquid crystal compound alignment solidified 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 solidified layer" is a concept that includes an alignment solidified layer obtained by hardening a liquid crystal monomer as described later. 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 solidified layer of the liquid crystal compound (liquid crystal alignment solidified 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 adopted as the alignment treatment. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be mentioned. 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 deposition method and photoalignment treatment. As the treatment conditions of various alignment treatments, any appropriate conditions can be adopted depending on the purpose.

[0041] The alignment of the liquid crystal compound is performed by treating the liquid crystal compound at a temperature at which the liquid crystal compound exhibits a liquid crystal phase according to the type of liquid crystal compound. By performing such temperature treatment, the liquid crystal compound takes on a liquid crystal state and is aligned according to the alignment treatment direction of 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 crosslinking treatment.

[0043] As the liquid crystal compound, any suitable liquid crystal polymer and / or liquid crystal monomer is used. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination. Specific examples of the liquid crystal compound and the method for producing the 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 another retardation layer is a layer in which a liquid crystal compound is aligned and fixed, the thickness is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and further preferably 1 μm to 4 μm.

[0045] In the manufacture of the retardation film, the RS of the obtained retardation layer can be changed by changing the forming material of each retardation layer, the manufacturing conditions, etc. For example, in a retardation film including a retardation layer which is a stretched film of a resin film, the RS tends to be small by increasing the film thickness of the retardation layer, decreasing the stretching ratio, etc. In addition, in the case of a resin film including a polycarbonate-based resin, the 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 which 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 made of any appropriate film. Examples of materials that are the main components of the film that constitutes 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 such as polynorbornene, polyolefin-based, (meth)acrylic, acetate-based, and other 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 an outline of the configuration of a display system according to one embodiment of the present invention, and shows the arrangement and shape of each component of the display system. The display system 10 includes a display element 12, a reflective polarizing member 14, a first lens unit 16 having a curved main surface, a half mirror 18, a first phase difference member 20, a second phase difference member 22, and a second lens unit 24. The reflective polarizing member 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 member 14, and the half mirror 18 is disposed between the display element 12 and the first lens unit 16. The first phase difference member 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second phase difference member 22 is disposed on the optical path between the half mirror 18 and the reflective polarizing member 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 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 portion (in the illustrated example, the half mirror 18, the first lens portion 16, the second λ / 4 member 22, the reflective polarizing member 14, and the second lens portion 24) may be collectively referred to as the lens portion (lens portion 4).

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

[0050] The first phase difference member 20 includes a first λ / 4 member that can convert a first linearly polarized light incident on the first phase difference member 20 into a 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 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 output from the first λ / 4 member included in the first phase difference member 20 passes through the half mirror 18 and the first lens unit 16, and is converted into the second linearly polarized light by the second λ / 4 member included in the second phase difference member 22. The second linearly polarized light output from the second λ / 4 member is reflected toward the half mirror 18 without passing through the reflective polarizing member 14. At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing member 14 is the same as the reflection axis of the reflective polarizing member 14. Therefore, the second linearly polarized light incident on the reflective polarizing member 14 is reflected by the reflective polarizing member 14.

[0054] The second linearly polarized light reflected by the reflective polarizing member 14 is converted into the second circularly polarized light by the second λ / 4 member included in the second phase difference member 22, and the second circularly polarized light emitted from the second λ / 4 member 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 the third linearly polarized light by the second λ / 4 member. The third linearly polarized light passes through the reflective polarizing member 14. At this time, the polarization direction of the third linearly polarized light incident on the reflective polarizing member 14 is the same as the transmission axis of the reflective polarizing member 14. Therefore, the third linearly polarized light incident on the reflective polarizing member 14 passes through the reflective polarizing member 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 disposed approximately parallel to each other or approximately 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°, may be 42° to 48°, or may be about 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°, may be 42° to 48°, or may be about 45°.

[0057] The in-plane retardation Re(550) of the first λ / 4 member is, for example, 100 nm to 190 nm, and may be 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The first λ / 4 member 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 member 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 member is, for example, 100 nm to 190 nm, and may be 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The second λ / 4 member 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 second λ / 4 member may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less. The in-plane retardation of the second λ / 4 member is, unless otherwise specified, the in-plane retardation measured at a portion corresponding to the center of the first lens portion. The center of the first lens portion may be a portion that is generally recognized as the center. For example, the center of the first lens portion may be the center of a circumscribing circle of its planar shape.

[0059] The absolute value of the difference between the in-plane retardation Re(550) of the first λ / 4 component and the in-plane retardation Re(550) of the second λ / 4 component 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] It is preferable that 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 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 phase difference member 22 is composed of the phase difference film described in Section A (specifically, a phase difference film including a phase difference layer A which is a positive C plate and a phase difference layer B which is a λ / 4 member), and is integrated with the first lens unit 16 having a curved surface. The integration of the second phase difference member 22 and the first lens unit 16 can be performed by integrating the phase difference film as the second phase difference member 22 with the first lens unit. The second phase difference member (phase difference film described in Section A) 22 can be integrated with the first lens unit 16 as an optical laminate which further includes other optical members as desired and has an adhesive layer (for example, a pressure-sensitive adhesive layer) on 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 nm or more, and may be, for example, 150 mm or less, preferably 125 mm or less, more preferably 110 mm or less, or 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 phase difference member 22 is integrated with the concave surface of the first lens portion 16, but may be integrated with the convex surface. The method of integrating the second phase difference member or the optical laminate with the first lens portion is not particularly limited, and for example, the same method as the method of integrating the phase difference film with the 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 part 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 in front 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 attached to the first lens portion 16 by a 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 made of any appropriate film. Examples of materials that are the main components of the film that constitutes 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 such as polynorbornene, polyolefin-based, (meth)acrylic-based, acetate-based, and other 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 may be disposed so that the surface treatment layer is located on the front side. The surface treatment layer may 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 further 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 due to integration with a member having a curved surface. 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 display surface of the display element, which is flat, and the curved surface of the first lens portion, which has a curved surface, respectively, a display system in which the difference between the in-plane retardation of both is small can be suitably 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 further include any other appropriate optical members, and may be integrated with the display element 12 as an optical laminate having an adhesive layer (eg, a pressure-sensitive adhesive layer) on the outermost layer, for example.

[0069] FIG. 5 is a schematic cross-sectional view for explaining 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 so that the retardation layer A (positive C plate) is 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 an 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 the display element by the 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, and 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 prepared from a single layer of resin film, or may be prepared using a laminate of two or more layers.

[0072] When preparing 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 an ethylene-vinyl acetate copolymer-based partially saponified film to a dyeing treatment with a dichroic substance such as iodine or a dichroic dye, a stretching treatment, etc. Among them, an absorptive polarizing film obtained by dyeing a PVA-based film with iodine and uniaxially stretching it is preferable.

[0073] The dyeing with iodine is 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. The stretching may be carried out after the dyeing treatment or while the dyeing is being carried out. Alternatively, the stretching may be followed by dyeing. If necessary, the PVA film is subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like.

[0074] Examples of the laminate produced using the laminate of two or more layers include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. The 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 coating a PVA-based resin solution on the resin substrate and drying the resin substrate to form a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; and stretching and dyeing the laminate to make the PVA-based resin layer into an absorptive polarizing film. In this embodiment, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. The stretching typically includes immersing the laminate in an aqueous boric acid solution to stretch it. Furthermore, the stretching may further include, as necessary, stretching the laminate in air at a high temperature (for example, 95° C. or higher) before stretching in the aqueous boric acid solution. 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 air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment in this order. By introducing the auxiliary stretching, even when PVA is applied onto a thermoplastic resin, it is possible to increase the crystallinity of PVA, and to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, problems such as a decrease in the orientation or dissolution of PVA when immersed in water in the subsequent dyeing and stretching steps can be prevented, and high optical properties can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in the 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 drying shrinkage treatment.The obtained laminate of resin substrate / absorptive polarizing film may be used as it 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 on the peeled surface of the resin substrate / absorptive polarizing film laminate after peeling the resin substrate from the laminate, or on the surface opposite to the peeled surface, depending on the purpose. Details of the method for producing such an absorptive polarizing film are described in, for example, JP2012-73580A and JP6470455A. The entire disclosures of these publications are incorporated herein by reference.

[0075] The crossed transmittance (Tc) of the absorptive polarizing member (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 member (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 member (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. Note that 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. Polarization degree 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. Setting the retardation film According to another aspect of the present invention, there is provided a set of two retardation films each independently including 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 respective 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] As shown in Fig. 4, the display system may include a planar first retardation member and a curved second retardation member. In such a display system, by forming the first retardation member using one of the retardation films and forming the second retardation member using the other, even when the second retardation member is deformed to follow the curved surface of the first lens unit, the change and unevenness of the in-plane retardation of the second λ / 4 member are reduced, and 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 the in-plane retardation Re(550)≦3.5 nm), and as a result, a display system with excellent visibility can be preferably obtained. EXAMPLES

[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, orientation function, single transmittance and polarization degree are values ​​measured by the following measurement methods. <Thickness> The thickness of 10 μm or less was measured using a scanning electron microscope (manufactured by JEOL, product name "JSM-7100F"), and the thickness of more than 10 μm was measured using a digital micrometer (manufactured by Anritsu, product name "KC-351C"). <Phase difference> The in-plane retardation at 23° C. was measured using a birefringence mapping measurement device (manufactured by Photoron, 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 (the numbers 65 and 35 in the formula 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: product name Paliocolor LC242), and 5 parts by mass of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: product name Irgacure 907) in 200 parts by mass of cyclopentanone. [ka] The coating liquid was then applied to a substrate film (norbornene-based resin film: manufactured by Zeon Corporation, product 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 the liquid crystal layer, thereby forming a retardation member having a thickness of 4 μm on the substrate. The retardation member thus obtained had a refractive index of nz>nx=ny. The retardation Rth(590) in the thickness direction of the retardation member (positive C plate) was 83 nm.

[0082] [Production Example 2] Production of positive C plate (II) In an autoclave equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a thermometer, 48 parts by weight of hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical, trade name: Metolose 60SH-50), 15601 parts by weight of distilled water, 8161 parts by weight of diisopropyl fumarate, 240 parts by weight of 3-ethyl-3-oxetanylmethyl acrylate, and 45 parts by weight of t-butyl peroxypivalate as a polymerization initiator were placed, and after nitrogen bubbling for 1 hour, the mixture was stirred and held 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 produced polymer particles was centrifuged. The obtained polymer was washed twice with distilled water and twice with methanol, and then dried under reduced pressure. The obtained fumarate ester 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 was added as a plasticizer to 100 parts by weight of the fumaric acid ester resin to prepare a dope. A biaxially stretched film (thickness 75 μm) of polyester (polyethylene terephthalate / isophthalate copolymer) was used as the support film. The prepared dope was applied to the support film so that the film thickness after drying was 20 μm, and dried at 140° C. The coating film (positive C plate) after drying had Re(550)0 nm and Rth(550)=-83 nm.

[0083] [Manufacturing Example 3] Manufacturing of λ / 4 component (I) Into a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled at 100°C, 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 x 10 calcium acetate monohydrate as a catalyst were added. -2 Weight part (6.78×10 -5mol) was charged. After the inside of the reactor was purged with nitrogen under reduced pressure, heating was performed with a heat medium, and stirring was started when the inside temperature reached 100 ° C. 40 minutes after the start of the temperature increase, the inside temperature was reached 220 ° C., and while controlling to maintain this temperature, the pressure was reduced and 90 minutes after reaching 220 ° C., the pressure was reduced to 13.3 kPa. Phenol vapor by-produced with the polymerization reaction was led to a reflux condenser at 100 ° C., a small amount of monomer components contained in the phenol vapor were returned to the reactor, and the uncondensed phenol vapor was led to a condenser at 45 ° C. and recovered. Nitrogen was introduced into the first reactor to restore the pressure to atmospheric pressure, and the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, the temperature increase and pressure reduction in the second reactor were started, and the inside temperature was set to 240 ° C. and the pressure to 0.2 kPa in 50 minutes. Thereafter, polymerization was allowed to proceed until the specified stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, and the polyester carbonate resin produced was extruded into water, and the strands were cut to obtain pellets. The obtained polyester carbonate resin (pellets) was vacuum-dried at 80°C for 5 hours, and then a long resin film with a thickness of 130 μm was produced using 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 to 130°C) and a winder. 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 up in a roll. As a result, a λ / 4 member with a thickness of 47 μm, Re(590) of 140 nm, and Nz coefficient of 1.2 was obtained. Moreover, the retardation layer had a Re(450) / Re(550) of 0.859, and exhibited inverse dispersion wavelength characteristics.

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

[0085] [ka] [ka]

[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 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 with 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 with an acrylic adhesive (thickness: 5 μm) to obtain a retardation film.

[0089] [Comparative Example 1] 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 with an acrylic adhesive (thickness 5 μm) to obtain a retardation film.

[0091] <Phase difference change value RS> The retardation change value RS of each of the retardation layers constituting the retardation films 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 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 above acrylic film is a film that hardly changes the retardation when the following tension is applied. A tension meter (manufactured by MYCARBON, product name "Digital Luggage Scale") was used to apply tension in the length direction of the obtained sample. At tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg, the in-plane retardation (Re(550)) was measured using a retardation measuring device (manufactured by Axometrics, product name: Axo Scan). With tension as the x-axis and Re(550) as the y-axis, the Re(550) values ​​measured at each tension were plotted to create an approximate straight line, and the slope of the approximate straight line was taken as the retardation change value RS.

[0092] <Breaking elongation> The breaking elongation of the positive C plate (rectangle, width 4 mm) constituting the retardation film of the examples and comparative examples was measured by measuring the 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 breaking elongation.

[0093] <Production and evaluation of curved surface integrated products> 1-1. Preparation of a lens with a phase difference film An acrylic adhesive layer (thickness 15 μm) was provided on the surface of the retardation film obtained in the examples and comparative examples (in the examples and comparative example 2, the retardation film on the side of the retardation layer A (positive C plate)), and the film was attached 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 surface side of the lens, and in a softened state by heating to 120° C., it was pressed into the concave surface side and attached 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. 1-2.Measurement of phase difference unevenness For the lenses with retardation films obtained in the examples and comparative examples, the in-plane retardation Re(543) was measured over the entire surface of the retardation film. In the in-plane retardation distribution obtained in this way, the difference in in-plane retardation Re(543) between the center and the other parts (outer parts) was detected, and the maximum value was taken as the in-plane retardation unevenness. Note that the in-plane retardation unevenness (|Re(543) center-Re(543) outer parts|) 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 a lens with a phase difference film An acrylic adhesive layer (thickness 15 μm) was provided on one side of the retardation film obtained in the examples and comparative examples, and the retardation film was attached to the concave surface of a lens having a circular shape with a diameter of 50 mm in plan view and a curvature radius of 40 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 and attached 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 the 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 onto a microslide glass (manufactured by Matsunami Glass Industry, product name "S200200") so as to prevent the inclusion of foreign matter, air bubbles, or deformation lines. Next, degassing was performed using a pressurized degassing device (autoclave) to remove the effects of minute air bubbles. 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 sample was placed on a vibration-proof measuring table, and a single-wavelength (633 nm) laser was used to interfere with a standard with guaranteed flatness, and the relative displacement within a specified area (a circle of 30 mm diameter) was measured. For the analysis, the smoothness of the retardation film (unit: arcmin) was defined as double the "slope magnitude RMS" (equivalent to 2σ), which is an index of the angle obtained by extracting the frequency values ​​from 0.1 / mm to 1 / mm.

[0095] The results are shown in Table 1. [Table 1] [Industrial Applicability]

[0096] The retardation film according to the embodiment of the present invention can be used in a display such as a VR goggle. [Explanation of symbols]

[0097] 10 Display System 12 Display element 14 Reflective polarizing element 16 First lens section 18 Half Mirror 20 First λ / 4 member 22 Second λ / 4 member 24 Second lens section 100 Phase contrast film A Retardation layer A B Retardation layer B

Claims

1. 1. A method for manufacturing a display system for displaying an image to a user, comprising the steps of: The display system comprises: a display element having a display surface that emits light representing an image forward via a polarizing member; a reflective polarizing member disposed in front of the display element and configured to reflect light emitted from the display element; a first lens portion disposed on an optical path between the display element and the reflective polarizing member, the first lens portion having a curved main surface; a half mirror disposed between the display element and the first lens portion, the half mirror transmitting light emitted from the display element and reflecting light reflected by the reflective polarizing member toward the reflective polarizing member; a first phase difference member disposed on an optical path between the display element and the half mirror, the first phase difference member including a first λ / 4 member; a second phase difference member including a second λ / 4 member, the second phase difference member being disposed on an optical path between the half mirror and the reflective polarizing member; Equipped with 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. Preparing two of the retardation films; One of the retardation films is integrated with the display element as the first retardation member; and The other retardation film is integrated with the first lens portion as the second retardation member; The method of claim 1 , comprising:

3. A method for manufacturing a lens portion used in a display system that displays an image to a user, comprising the steps of: The lens portion is a reflective polarizing member that reflects light that is emitted forward from a display surface of a display element that displays an image and that has passed through the polarizing member and the first λ / 4 member; a first lens portion disposed on an optical path between the display element and the reflective polarizing member, the first lens portion having a curved main surface; a half mirror disposed between the display element and the first lens portion, the half mirror transmitting light emitted from the display element and reflecting light reflected by the reflective polarizing member toward the reflective polarizing member; a second phase difference member including a second λ / 4 member, the second phase difference member being disposed on an optical path between the half mirror and the reflective polarizing 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;

4. Two or more retardation layers are included, the absolute value of the sum of the retardation change values ​​RS of the retardation layers is 3.0 or less, The retardation change value RS is a slope of an 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. Phase contrast film.

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

7. The retardation film according to claim 4 , wherein the retardation layer A has a breaking elongation at 23° C. of 1% or more.

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

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 curved surface of the member having the curved surface has a radius of curvature of 20 mm or more.

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

13. a display element having a display surface that emits light representing an image forward via a polarizing member; a reflective polarizing member disposed in front of the display element and configured to reflect light emitted from the display element; a first lens portion disposed on an optical path between the display element and the reflective polarizing member, the first lens portion having a curved main surface; a half mirror disposed between the display element and the first lens portion, the half mirror transmitting light emitted from the display element and reflecting light reflected by the reflective polarizing member toward the reflective polarizing member; a first phase difference member disposed on an optical path between the display element and the half mirror, the first phase difference member including a first λ / 4 member; a second phase difference member including a second λ / 4 member, the second phase difference member being disposed on an optical path between the half mirror and the reflective polarizing member; Equipped with In a display system in which the second phase difference member and the first lens portion are integrated, 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 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 tensions of 0 kg, 0.5 kg, 1 kg, 1.5 kg, and 2 kg). A set of phase contrast films.

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