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

Abstract

To provide an optical member capable of improving visibility of VR goggles.SOLUTION: The method for treating an optical member includes annealing the optical member to reduce the 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 the resin film included in the optical member.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for treating optical elements and a method for manufacturing an optical element set. [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 popular. In image display devices, optical components such as polarizing components and phase difference components are generally used to realize image display and 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. VR goggles are being considered for use in a variety of situations, and improvements in visibility, such as higher resolution, are desired. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-103286 Summary of the Invention [Problem to be solved by the invention]

[0005] In VR goggles, images are viewed through lenses, so there is a need for the development of optical components suitable for lens-based display systems.

[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. [Means for solving the problem]

[0007] 1. A method for treating an optical component according to an embodiment of the present invention includes annealing the optical component to reduce the surface roughness Sa of the optical component, and 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. 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 according to the above 1 or 2, the annealing time may be 30 seconds to 15 minutes. 4. In the method for treating an optical member according to any one of the above items 1 to 3, the optical member may be held so as to suppress shrinkage of the resin film, and annealed. 5. In the method for treating an optical member according to 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. 7. 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. [Effects of the Invention]

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

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a general configuration of an example of a display system for VR goggles. [Figure 2] FIG. 1 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film. DETAILED DESCRIPTION OF THE INVENTION

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

[0011] (Definition of terms and symbols) The definitions of terms and symbols used in this specification are as follows. (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction in which the in-plane refractive index is greatest (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] [Optical components] 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, the optical members used may be required to have high smoothness. 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 member. Specifically, the annealing temperature, where Tg (°C) is the glass transition temperature of the resin film contained in the optical member, may be Tg-30 (°C) to Tg+20 (°C), or Tg-30 (°C) to Tg+10 (°C), or Tg-30 (°C) to Tg (°C). The annealing temperature is, 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, and 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, a long and thin 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 even 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 overall configuration of an example of a display system for VR goggles, illustrating the arrangement and shape of each component of the display system. The display system 10 includes a display element 12, a reflective polarizing element 14, a first lens unit 16, 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 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.

[0024] The first λ / 4 member 20 can convert the first linearly polarized light incident on the first λ / 4 member 20 into 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 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 element 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 element 22. The second linearly polarized light output from the second λ / 4 element 22 is reflected toward the half mirror 18 without passing through the reflective polarizing element 14. At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing element 14 is the same as the reflection axis of the reflective polarizing element 14. Therefore, the second linearly polarized light incident on the reflective polarizing element 14 is reflected by the reflective polarizing element 14.

[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 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 formed 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 formed 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 component 20 is, for example, 100 nm to 190 nm, or alternatively, 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The first λ / 4 component 20 preferably exhibits inverse dispersion wavelength characteristics in which the retardation value increases according to the wavelength of the measurement light. The Re(450) / Re(550) of the first λ / 4 component 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 component 22 is, for example, 100 nm to 190 nm, or alternatively, 110 nm to 180 nm, 130 nm to 160 nm, or 135 nm to 155 nm. The second λ / 4 component 22 preferably exhibits inverse dispersion wavelength characteristics in which the retardation value increases according to the wavelength of the measurement light. The Re(450) / Re(550) of the second λ / 4 component 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 has 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 component set] The optical member set according to an embodiment of the present invention includes a plurality of optical members. Some or all of the plurality of optical members may be integrated. Each of the plurality of optical members can have excellent smoothness. Specifically, each of the plurality of optical members has a surface roughness Sa of, for example, 0.005 μm to 0.090 μm, preferably 0.080 μm or less, more preferably 0.070 μm or less, may be 0.060 μm or less, may be 0.040 μm or less, may be 0.020 μm or less, and may be 0.015 μm or less.

[0036] At least a part of the plurality of optical members included in the optical member set may be subjected to the annealing treatment. For example, the optical member set can 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 the optical members having a surface roughness Sa exceeding a predetermined value among the evaluated optical members.

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

[0038] The second λ / 4 member 22 can show, for example, a refractive index characteristic of nx > ny ≧ nz. Here, "ny = nz" includes not only the case where ny and nz are exactly equal but also the case where they are substantially equal. Therefore, ny < nz may occur. The Nz coefficient of the second λ / 4 member 22 is preferably 0.9 to 3, more preferably 0.9 to 2.5, still 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 resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, and acrylic resins. These resins can be used alone or in combination. Examples of methods for combining resins include blending and copolymerization. When the first λ / 4 member 20 exhibits reverse dispersion wavelength characteristics, a resin film containing a polycarbonate resin or a polyester carbonate resin (hereinafter sometimes simply referred to as a polycarbonate resin) can be suitably used.

[0040] Any suitable polycarbonate-based resin can be used as the polycarbonate-based resin. For example, the polycarbonate-based resin contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, and structural units derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanols, di-, tri-, or polyethylene glycols, and alkylene glycols or spiroglycols. Preferably, the polycarbonate-based resin contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, structural units derived from an alicyclic dimethanol, and / or structural units derived from di-, tri-, or polyethylene glycol; more preferably, it contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, and structural units derived from di-, tri-, or polyethylene glycol. The polycarbonate-based resin may contain structural units derived from other dihydroxy compounds as needed. Details of polycarbonate resins that can be suitably used for 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. Examples of such resin films include cyclic polyolefin-based films. Cyclic polyolefins can be polymers containing an alicyclic structure in the repeating units of their main chains. Examples of cyclic polyolefin-based resins include those described in JP-A-1-240517, JP-A-3-14882, and JP-A-3-122137. 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 their derivatives. Commercially available cyclic polyolefin-based resins include "ZEONOR" and "ZEONEX" manufactured by Zeon Corporation, "ARTON" manufactured by JSR Corporation, "APEL" manufactured by Mitsui Chemicals, 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 layers B that are substantially not birefringent. The total number of layers constituting the multilayer structure may be 50 to 1000. 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 and the refractive index ny in the y-axis direction of layer B are substantially the same, and 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 corresponds 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 member (reflective polarizing film) can be, for example, 0.001% to 3%. The single transmittance (Ts) of the reflective polarizing member (reflective polarizing film) can be, for example, 43% to 49%, preferably 45% to 47%. The polarization degree (P) of the reflective polarizing member (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 fabricating from a single-layer resin film, an absorptive polarizing film can be obtained by dyeing a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film, a partially formalized PVA film, or a partially saponified ethylene-vinyl acetate copolymer film with iodine or a dichroic substance such as a dichroic dye, stretching, etc. Among these, an absorptive polarizing film obtained by dyeing a PVA film with iodine and uniaxially stretching it is preferred.

[0055] 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 dyeing. Alternatively, the stretching may be carried out before dyeing. If necessary, the PVA film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, etc.

[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, or 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 resin substrate 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 and stretching it. Furthermore, the stretching may further include, if necessary, in-air stretching of the laminate at an elevated temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. Additionally, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment by heating 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 in-air auxiliary 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 PVA, even when PVA is coated on a thermoplastic resin substrate, thereby achieving high optical properties. Furthermore, by simultaneously increasing the orientation of PVA in advance, problems such as a decrease in orientation or dissolution of PVA when immersed in water in the subsequent dyeing and 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 orientation of 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 an absorptive polarizing film obtained by immersing the laminate in a liquid through treatment steps 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 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 absorptive polarizing films are described in, for example, JP 2012-73580 A and Japanese Patent No. 6470455 A. 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. 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 luminosity. Polarization degree 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. [Example]

[0061] The present invention will be described in more detail below with reference to 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"), and thicknesses of more than 10 μm were measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). <Phase difference value> The phase difference value at each wavelength at 23°C was measured using a Mueller matrix polarimeter (manufactured by Axometrics, product name "Axoscan"). <Glass transition temperature> The glass transition temperature was determined by measuring in tension mode using a thermomechanical analyzer (TA-instrument, "TMA Q400") under a nitrogen atmosphere (nitrogen gas flow rate: 50 ml / min, relative humidity: 0%) and an applied load of 19.6 mN. Specifically, both longitudinal ends of a strip-shaped measurement sample cut to 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 measured while the temperature was increased from 25°C to 200°C at a rate of 5°C / min, and the glass transition temperature was calculated from the obtained data (TMA curve). <Surface roughness Sa> The surface roughness Sa was measured using a scanning white light interferometer (Zygo, product name "NewView9000") Specifically, the measurement sample (film) was placed on a 10cm x 10cm 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 target within a 12.4mm square field of view.

[0062] (Preparation of reflective polarizing element) 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 lactone ring structure and a thickness of 20 μm 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 lactone ring structure and a thickness of 40 μm 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 with 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 components) A 45 μm thick unstretched film was produced by melt extrusion using pellets of cyclic polyolefin resin (JSR, "ARTON R5000"). Heat-shrinkable biaxially oriented propylene films (Toray, "Torayfan") were attached to both sides of this film via an adhesive to obtain a laminate. This laminate was then stretched longitudinally at a temperature of 150°C and a stretching ratio of 1.3 times, after which the heat-shrinkable films attached 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, and an Nz coefficient of 0.5. The resulting resin film also had 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 was prepared, and each member was annealed for one minute at different annealing temperatures (for the reflective polarizing member, annealing was performed for five 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] [Table 1]

[0070] If the annealing temperature is too high, the surface irregularities may be flattened, but wrinkles may occur, and the Sa value 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. [Industrial Applicability]

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

[0073] 10 Display System 12 Display element 14 Reflective polarizing element 16 First lens part 18 Half Mirror 20 First λ / 4 member 22 Second λ / 4 member 24 Second lens section 28 Absorbing polarizing element

Claims

1. annealing the optical element to reduce the surface roughness Sa of the optical element; 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 the resin film included in the optical member; A method for processing optical components.

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

3. 2. 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 annealed while being held so as to suppress shrinkage of the resin film.

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 member set including a plurality of optical members, comprising: providing the plurality of optical members; Evaluating the surface roughness Sa of each of the plurality of optical members; and performing the method for treating an optical member according to any one of claims 1 to 5 on an optical member having a surface roughness exceeding a predetermined value Sa among the evaluated optical members; A method for manufacturing an optical member set, comprising:

7. The plurality of optical members include: A step of passing light representing an image emitted through the polarizing member and the first λ / 4 member through a half mirror and a first lens unit; a step of passing the light that has passed through the half mirror and the first lens portion through a second λ / 4 member; A step of reflecting the light that has passed through the second λ / 4 member toward the half mirror by a reflective polarizing member; allowing the light reflected by the reflective polarizing member and the half mirror to pass through the reflective polarizing member by the second λ / 4 member; A step of passing the light transmitted through the reflective polarizing member through a second lens portion; used in a display method having disposed on an optical path between the first lens portion and the second lens portion; The method for manufacturing the optical member set according to claim 6 .

Images