Method for processing optical member and method for manufacturing optical member set

Abstract

Provided is an optical member capable of improving visibility of VR goggles. This method for processing an optical member includes annealing an optical member to reduce surface roughness Sa of the optical member, and the annealing temperature is set within a range of Tg - 30 (°C) to Tg + 20 (°C) with respect to the glass transition temperature Tg (°C) of a resin film included in the optical member.

Description

Method for treating optical members and method for manufacturing optical member sets

[0001] The present invention relates to a method for treating optical elements and a method for manufacturing an optical element set.

[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. The use of VR goggles in various situations is being considered, and improvements in visibility, such as higher definition, are desired.

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

[0005] In VR goggles, images are viewed through lenses, so there is a demand for the development of optical components suitable for display systems that use lenses.

[0006] In view of the above, a main object of the present invention is to provide an optical member that can improve the visibility of VR goggles.

[0007] 1. A method for treating an optical member according to an embodiment of the present invention includes annealing an optical member to reduce the surface roughness Sa of the optical member, wherein the annealing temperature is set within a range of Tg - 30 (°C) to Tg + 20 (°C), where Tg (°C) is the glass transition temperature of a resin film included in the optical member. 2. In the method for treating an optical member described in 1 above, the annealing temperature may be 90°C to 140°C. 3. In the method for treating an optical member described in 1 or 2 above, the annealing time may be 30 seconds to 15 minutes. 4. In the method for treating an optical member described in any one of 1 to 3 above, the optical member may be annealed while being held so as to suppress shrinkage of the resin film. 5. In the method for treating an optical member described in any one of 1 to 3 above, the optical member may be annealed while being transported using a roll. 6. A method for manufacturing an optical element set according to an embodiment of the present invention is a method for manufacturing an optical element set including a plurality of optical elements, and includes preparing the plurality of optical elements, evaluating the surface roughness Sa of each of the plurality of optical elements, and subjecting the optical element processing method described in any one of 1 to 5 above to optical elements having a surface roughness Sa exceeding a predetermined value among the evaluated optical elements. In the manufacturing method described in 6 above, the plurality of optical elements may be used in a display method having the steps of: passing light representing an image emitted through a polarizing element and a first λ / 4 element through a half mirror and a first lens unit; passing the light that has passed through the half mirror and the first lens unit through a second λ / 4 element; reflecting the light that has passed through the second λ / 4 element toward the half mirror with a reflective polarizing element; making the light reflected by the reflective polarizing element and the half mirror transmittant through the reflective polarizing element with the second λ / 4 element; and passing the light that has transmitted through the reflective polarizing element through a second lens unit, and may be arranged on the optical path between the first lens unit and the second lens unit.

[0008] The optical member according to the embodiment of the present invention can improve the visibility of VR goggles.

[0009] 1 is a schematic diagram illustrating a general configuration of an example of a display system for VR goggles. FIG. 2 is a schematic perspective view illustrating an example of a multilayer structure included in a reflective polarizing 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 duplicate 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] [Optical Member] Specific examples of optical members according to embodiments of the present invention include polarizing members, retardation members, and protective members for these members. Optical members can be typically applied to image display devices. In image display devices, high smoothness is sometimes required for the optical members used. The surface roughness Sa of the optical member is, for example, 0.005 μm to 0.090 μm, preferably 0.080 μm or less, more preferably 0.070 μm or less, and may be 0.060 μm or less, 0.040 μm or less, 0.020 μm or less, or 0.015 μm or less.

[0013] The optical member may be a single layer or a laminate having two or more layers, but may include at least a resin film. The thickness of the resin film that may be included in the optical member is, for example, 1 μm to 100 μm. When the optical member is a laminate, the optical member may include an adhesive layer for integrating adjacent layers. The adhesive layer may be formed of an adhesive or a pressure-sensitive adhesive. The thickness of the adhesive layer is, for example, 0.05 μm to 30 μm, preferably 3 μm to 20 μm, and more preferably 5 μm to 15 μm.

[0014] An optical member with excellent smoothness can be achieved by annealing, which may be performed by placing the optical member in a predetermined temperature environment (e.g., in an oven or autoclave) or by using a heater (e.g., an IR heater).

[0015] The annealing conditions can be set to any appropriate conditions. For example, the annealing temperature can be set depending on the resin film contained in the optical component. Specifically, the annealing temperature may be Tg-30 (°C) to Tg+20 (°C), Tg-30 (°C) to Tg+10 (°C), or Tg-30 (°C) to Tg (°C), where Tg (°C) is the glass transition temperature of the resin film contained in the optical component. The annealing temperature may be, for example, 80°C to 160°C, 85°C to 150°C, or 90°C to 140°C. The annealing time is, for example, 10 seconds to 30 minutes, preferably 30 seconds to 15 minutes.

[0016] The surface roughness Sa of the optical member before annealing is, for example, 0.010 μm to 0.1 μm, and may be greater than 0.090 μm, greater than 0.080 μm, greater than 0.070 μm, greater than 0.060 μm, greater than 0.040 μm, greater than 0.020 μm, or greater than 0.015 μm.

[0017] When the annealing treatment is performed, the optical member may have any suitable shape. Specifically, the optical member may be in a sheet shape or a long shape. Here, "long" refers to an elongated shape in which the length is sufficiently longer than the width, for example, an elongated shape in which the length is 10 times or more, preferably 20 times or more, the width. A long optical member can be wound into a roll.

[0018] When the optical member is in a sheet form, it is preferable to hold the optical member so as to suppress shrinkage of the resin film and to perform the annealing treatment on the optical member. Specifically, it is preferable to perform the annealing treatment on the optical member while chucking the opposing ends of the optical member at a predetermined chuck distance.

[0019] When the optical member is long, the annealing treatment is typically performed on the optical member while the optical member is being transported using rolls, for example, by transporting the optical member using rolls in an environment set at a predetermined annealing temperature.

[0020] The annealing treatment can reduce the surface roughness Sa of the optical member by approximately 0.001 μm to 0.030 μm. Specifically, the difference in surface roughness Sa of the optical member before and after the annealing treatment is, for example, 0.001 μm to 0.030 μm, and may be 0.005 μm or more, or 0.010 μm or more. The annealing treatment may reduce the surface roughness Sa of the optical member to 0.090 μm or less, 0.080 μm or less, 0.070 μm or less, 0.060 μm or less, 0.040 μm or less, 0.020 μm or less, or 0.015 μm or less.

[0021] The optical member according to the embodiment of the present invention can be suitably used in, for example, VR goggles.

[0022] FIG. 1 is a schematic diagram showing the general configuration of an example of a display system for VR goggles, and schematically illustrates 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, a half mirror 18, a first λ / 4 element 20, a second λ / 4 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 λ / 4 element 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second λ / 4 element 22 is disposed on the optical path between the half mirror 18 and the reflective polarizing element 14.

[0023] 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.

[0024] The first λ / 4 member 20 can convert the first linearly polarized light incident on the first λ / 4 member 20 into the first circularly polarized light. The first λ / 4 member 20 may be provided integrally with the display element 12.

[0025] 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.

[0026] The second λ / 4 member 22 can transmit the light reflected by the reflective polarizing member 14 and the half mirror 18 through the reflective polarizing member 14. The second λ / 4 member 22 may be provided integrally with the first lens portion 16.

[0027] The first circularly polarized light output from the first λ / 4 member 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 member 22. The second linearly polarized light output from the second λ / 4 member 22 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.

[0028] 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 22, and the second circularly polarized light emitted from the second λ / 4 element 22 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 22. 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.

[0029] The light transmitted through the reflective polarizing member 14 passes through the second lens portion 24 (the absorptive polarizing member 28 and the second lens portion 24 ) and enters the eye 26 of the user.

[0030] 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 20 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 22 is, for example, 40° to 50°, or may be 42° to 48°, or may be approximately 45°.

[0031] The in-plane retardation Re(550) of the first λ / 4 member 20 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 member 20 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 20 may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

[0032] The in-plane retardation Re(550) of the second λ / 4 member 22 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 member 22 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 22 may be, for example, 0.75 or more and less than 1, or 0.8 or more and 0.95 or less.

[0033] The display system 10 may include an absorptive polarizing element 28. The absorptive polarizing element 28 may be disposed in front of the reflective polarizing element 14. The reflection axis of the reflective polarizing element 14 and the absorption axis of the absorptive polarizing element 28 may be disposed approximately parallel to each other, and the transmission axis of the reflective polarizing element 14 and the transmission axis of the absorptive polarizing element 28 may be disposed approximately parallel to each other. The reflective polarizing element 14 and the absorptive polarizing element 28 may be integrated together. The absorptive polarizing element 28 may be used in the above-described display system, for example, from the viewpoint of improving visibility.

[0034] Optical members according to embodiments of the present invention can be suitably used, for example, as members included in the display system. Specifically, the optical member can be a polarizing member such as a reflective polarizing member or an absorptive polarizing member. The optical member can also be a retardation member such as a λ / 4 member. Furthermore, the optical member can also be a protective member such as a polarizing member or a retardation member. Since the optical member according to embodiments of the present invention can have excellent smoothness, it can achieve excellent visibility in the display system. For example, it can achieve clear images without distortion. In particular, when the optical member according to embodiments of the present invention is disposed on the optical path between the first lens portion 16 and the second lens portion 24, it can achieve significantly excellent visibility.

[0035] [Optical Element Set] An optical element set according to an embodiment of the present invention includes a plurality of optical elements. The plurality of optical elements may be partially or entirely integrated. Each of the plurality of optical elements may have excellent smoothness. Specifically, the surface roughness Sa of each of the plurality of optical elements is, for example, 0.005 μm to 0.090 μm, preferably 0.080 μm or less, more preferably 0.070 μm or less, and may be 0.060 μm or less, 0.040 μm or less, 0.020 μm or less, or 0.015 μm or less.

[0036] At least some of the optical members included in the optical member set may be subjected to the annealing treatment. For example, the optical member set may be manufactured by a method including: preparing a plurality of optical members, evaluating the surface roughness Sa of each of the plurality of optical members, and performing the annealing treatment on optical members having a surface roughness Sa exceeding a predetermined value among the evaluated optical members.

[0037] In one embodiment, the method for manufacturing the optical member set is a method for manufacturing an optical member set having a plurality of optical members arranged on the optical path between the first lens portion 16 and the second lens portion 24. For example, it is a method for manufacturing an optical member set including a second λ / 4 member 22, a reflective polarizing member 14, an absorptive polarizing member 28, and a protective member.

[0038] The second λ / 4 member 22 may have, for example, a refractive index characteristic that satisfies the relationship nx>ny≧nz. Here, "ny=nz" does not only mean that ny and nz are completely equal, but also includes cases where they are substantially equal. Therefore, there may be cases where ny<nz. The Nz coefficient of the second λ / 4 member 22 is preferably 0.9 to 3, more preferably 0.9 to 2.5, even more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

[0039] A λ / 4 member that can satisfy the above characteristics can be, for example, a stretched resin film. Examples of resins contained in this resin film include polycarbonate-based resins, polyester carbonate-based resins, polyester-based resins, polyvinyl acetal-based resins, polyarylate-based resins, cyclic olefin-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 can be used alone or in combination. Examples of combination methods include blending and copolymerization. When the first λ / 4 member 20 exhibits 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.

[0040] Any suitable polycarbonate resin can be used as the polycarbonate resin. For example, the polycarbonate 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 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 resin may contain structural units derived from other dihydroxy compounds as needed. Details of polycarbonate-based resins that can be suitably used for the first λ / 4 member 20 and methods for forming the first λ / 4 member 20 are described, for example, in JP 2014-10291 A, JP 2014-26266 A, JP 2015-212816 A, JP 2015-212817 A, and JP 2015-212818 A, and the descriptions in these publications are incorporated herein by reference.

[0041] The thickness of the stretched resin film is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, and more preferably 20 μm to 60 μm.

[0042] The second λ / 4 member 22 may also have refractive index characteristics that satisfy the relationship nx>nz>ny. The second λ / 4 member 22 may be configured as a so-called Z-plate. The Nz coefficient of the second λ / 4 member 22 (Z-plate) is preferably 0.2 to 0.9, more preferably 0.3 to 0.8, and even more preferably 0.4 to 0.7.

[0043] A λ / 4 member (Z-plate) that can satisfy the above characteristics can be, for example, a resin film. For example, a cyclic polyolefin film can be used as this resin film. The cyclic polyolefin can be a polymer containing an alicyclic structure in the repeating unit of the main chain. Examples of cyclic polyolefin resins include resins described in JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, etc. Specific examples include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers (typically random copolymers) of cyclic olefins with α-olefins such as ethylene and propylene, and graft polymers and hydrogenated products of these modified with unsaturated carboxylic acids or derivatives thereof. Commercially available cyclic polyolefin resins include "ZEONOR" and "ZEONEX" manufactured by Nippon Zeon Co., Ltd., "ARTON" manufactured by JSR Corporation, "APEL" manufactured by Mitsui Chemicals, Inc., and "TOPAS" manufactured by TOPAS ADVANCED POLYMERS.

[0044] The cyclic polyolefin film preferably contains 50% by weight or more of a cyclic polyolefin resin, more preferably 70% by weight or more, even more preferably 80% by weight or more, and may even be 90% by weight or more or 95% by weight or more.

[0045] In one embodiment, the Z-plate can be obtained by laminating a heat-shrinkable film on at least one surface of a polymer film obtained by a known method such as solution casting or melt extrusion, stretching the film in one direction, and then shrinking the film in a direction perpendicular to the stretching direction using the shrinkage force of the heat-shrinkable film. The heat-shrinkable film is not particularly limited as long as it heat-shrinks in a direction perpendicular to the stretching direction when attached to the polymer film and stretched. The heat-shrinkable film may have an anisotropic shrinkage rate. The material constituting the heat-shrinkable film is not particularly limited, but is preferably one that heat-shrinks near the stretching temperature of the polymer film. When the polymer film is a cyclic polyolefin film, polyolefins such as polyethylene and polypropylene, or polyesters are preferably used as the material for the heat-shrinkable film because they are highly versatile and inexpensive.

[0046] The thickness of the Z-plate is, for example, 30 μm to 60 μm, preferably 30 μm to 50 μm, and more preferably 35 μm to 45 μm.

[0047] The reflective polarizing element 14 transmits light polarized parallel to its transmission axis (typically, linearly polarized light) while maintaining its polarization state, and can reflect light polarized in other states (typically, light polarized perpendicular to its transmission axis). The reflective polarizing element is typically made of a film having a multilayer structure (sometimes referred to as a reflective polarizing film). In this case, the thickness of the reflective polarizing element is preferably 20 μm to 100 μm, and more preferably 30 μm to 60 μm.

[0048] FIG. 2 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film. The multilayer structure 14a has alternating birefringent layers A and substantially non-birefringent layers B. The total number of layers constituting the multilayer structure may be 50 to 1,000. For example, the refractive index nx in the x-axis direction of layer A is larger than the refractive index ny in the y-axis direction, and the refractive index nx in the x-axis direction of layer B and the refractive index ny in the y-axis direction are substantially the same. The refractive index difference between layer A and layer B is large in the x-axis direction and substantially zero in the y-axis direction. As a result, the x-axis direction can be the reflection axis, and the y-axis direction can be the transmission axis. The refractive index difference between layer A and layer B in the x-axis direction is preferably 0.2 to 0.3.

[0049] The A layer is typically made of a material that exhibits birefringence upon stretching. Examples of such materials include naphthalenedicarboxylic acid polyesters (e.g., polyethylene naphthalate), polycarbonates, and acrylic resins (e.g., polymethyl methacrylate). The B layer is typically made of a material that does not substantially exhibit birefringence upon stretching. Examples of such materials include copolyesters of naphthalenedicarboxylic acid and terephthalic acid. The multilayer structure can be formed by a combination of coextrusion and stretching. For example, the materials constituting the A layer and the B layer are extruded and then multilayered (e.g., using a multiplier). The resulting multilayer laminate is then stretched. The x-axis direction in the illustrated example may correspond to the stretching direction.

[0050] Commercially available reflective polarizing films include, for example, "DBEF" and "APF" manufactured by 3M, and "APCF" manufactured by Nitto Denko Corporation.

[0051] The crossed transmittance (Tc) of the reflective polarizing element (reflective polarizing film) can be, for example, 0.001% to 3%. The single transmittance (Ts) of the reflective polarizing element (reflective polarizing film) can be, for example, 43% to 49%, preferably 45% to 47%. The polarization degree (P) of the reflective polarizing element (reflective polarizing film) can be, for example, 92% to 99.99%.

[0052] The absorptive polarizing member 28 may include, for example, 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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 optionally 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. 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 substrate, 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.

[0057] 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.

[0058] 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

[0059] The protective member may include any appropriate resin film. Examples of materials that form the main component of the resin film constituting the protective member 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. Among these, (meth)acrylic resins and cycloolefin-based resins are preferably used.

[0060] The thickness of the resin film constituting the protective member is preferably 5 μm to 80 μm, more preferably 10 μm to 50 μm, and even more preferably 15 μm to 40 μm.

[0061] The present invention will be described in detail below using examples, but the present invention is not limited to these examples. The thickness, retardation value, glass transition temperature, and surface roughness Sa 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 Value> Retardation values ​​at each wavelength at 23°C were measured using a Mueller matrix polarimeter (manufactured by Axometrics, product name "Axoscan"). <Glass transition temperature> Using a thermomechanical analyzer (manufactured by TA-instrument, "TMA Q400"), measurements were performed in tension mode under conditions of a nitrogen atmosphere (nitrogen gas flow rate: 50 ml / min, relative humidity: 0%) and an applied load of 19.6 mN, and the glass transition temperature was determined. Specifically, both longitudinal ends of a strip-shaped measurement sample cut into a size of 4 mm wide and 30 mm long were set on the probe of the measurement device with a 16 mm gap between them. The dimensional change of the measurement sample was then measured while increasing the temperature from 25°C to 200°C at a heating rate of 5°C / min, and the glass transition temperature was determined from the obtained data (TMA curve). <Surface roughness Sa> The surface roughness Sa was measured using a scanning white light interferometer (manufactured by Zygo, product name "NewView9000"). Specifically, the measurement sample (film) was placed on a 10 cm x 10 cm measurement table with an anti-vibration table, interference fringes were generated using a single white LED light, and an interference objective lens (1.4x magnification) with a reference surface was scanned in the Z direction (thickness direction) to selectively obtain the surface roughness Sa of the outermost surface of the measurement object within a 12.4 mm square field of view.

[0062] (Preparation of Reflective Polarizing Member) A reflective polarizing film ("APCF" manufactured by Nitto Denko Corporation) was prepared. The thickness of this film was 35 μm, the glass transition temperature was 110° C., and the surface roughness Sa was 0.029 μm.

[0063] (Preparation of Protective Member 1) An acrylic film having a thickness of 20 μm and a lactone ring structure was prepared. The glass transition temperature of this film was 125° C. and the surface roughness Sa was 0.025 μm.

[0064] (Preparation of Protective Member 2) An acrylic film having a thickness of 40 μm and a lactone ring structure was prepared. The glass transition temperature of this film was 120° C. and the surface roughness Sa was 0.012 μm.

[0065] (Preparation of Protective Member 3) A TAC film having a thickness of 20 μm was prepared. The glass transition temperature of this film was 150° C., and the surface roughness Sa was 0.017 μm.

[0066] (Preparation of λ / 4 member) Using pellets of cyclic polyolefin resin ("ARTON R5000" manufactured by JSR), an unstretched film with a thickness of 45 μm was produced by melt extrusion. A heat-shrinkable biaxially stretched propylene film ("TORAYFAN" manufactured by Toray) was bonded to both sides of this film via an adhesive to obtain a laminate. This laminate was then longitudinally stretched at a temperature of 150 ° C. and a stretching ratio of 1.3 times, and the heat-shrinkable films bonded to both sides were peeled off to obtain a resin film.

[0067] The resulting resin film had a thickness of 39 μm, an Re(550) of 140 nm, an Nz coefficient of 0.5, a glass transition temperature of 150° C., and a surface roughness Sa of 0.090 μm.

[0068] (Annealing Treatment) A plurality of each of the above members were prepared, and each member was annealed for 1 minute at various annealing temperatures (for the reflective polarizing member, annealing was performed for 5 minutes at annealing temperatures of 90° C. and 100° C.). The surface roughness Sa before and after the annealing treatment is summarized in Table 1.

[0069]

[0070] If the annealing temperature is too high, the surface irregularities may be flattened, but wrinkles may occur, and the value of Sa may become larger than the initial value.

[0071] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the configurations shown in the above-described embodiment can be replaced with configurations that are substantially the same as those shown in the above-described embodiment, that have the same effects, or that can achieve the same purpose.

[0072] The optical film according to the embodiment of the present invention can be used in an image display device, and can be suitably used in, for example, VR goggles.

[0073] 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 28 Absorptive polarizing member

Claims

1. A method for treating an optical component, comprising annealing the optical component to reduce the surface roughness Sa of the optical component, wherein the annealing temperature is set within a range of Tg-30 (°C) to Tg+20 (°C), where Tg (°C) is the glass transition temperature of a resin film contained in the optical component.

2. The method for treating an optical member according to claim 1, wherein the annealing temperature is 90°C to 140°C.

3. The method for treating an optical member according to claim 1, wherein the annealing time is 30 seconds to 15 minutes.

4. The method for treating an optical member according to claim 1, wherein the optical member is held so as to suppress shrinkage of the resin film, and the optical member is annealed.

5. The method for treating an optical member according to claim 1, wherein the optical member is annealed while being transported using a roll.

6. A method for manufacturing an optical element set including a plurality of optical elements, comprising: preparing the plurality of optical elements; evaluating the surface roughness Sa of each of the plurality of optical elements; and performing the optical element processing method described in any one of claims 1 to 5 on optical elements among the evaluated optical elements that exceed a predetermined surface roughness Sa.

7. The method for manufacturing an optical element set according to claim 6, wherein the plurality of optical elements are used in a display method comprising the steps of: passing light representing an image emitted through a polarizing element and a first λ / 4 element through a half mirror and a first lens unit; passing the light that has passed through the half mirror and the first lens unit through a second λ / 4 element; reflecting the light that has passed through the second λ / 4 element towards the half mirror with a reflective polarizing element; making the light reflected by the reflective polarizing element and the half mirror transmittant through the reflective polarizing element with the second λ / 4 element; and passing the light that has transmitted through the reflective polarizing element through a second lens unit.

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