Optical film piece and method for manufacturing the same

Abstract

To provide an optical film piece capable of excellently achieving the weight saving of VR goggles while improving visibility.SOLUTION: An optical film piece 1 including a retardation member has first and second main surfaces facing each other. The first main surface 1a includes: a first area 71 where the standard deviation of an in-plane phase difference Re (550) at a wave length of 550 nm from a first part 1c positioned in a central part to a second part 1d positioned on the outside from the first part 1c is 5 nm or less; and a second area 72 where the standard deviation of an in-plane phase difference Re (550) at a wave length of 550 nm from the first part 1c to a third part 1e positioned on the outside from the second part 1d is more than 5 nm. The average value of the in-plane phase difference Re (550) at the wave length of 550 nm in the first area 71 is 135 nm or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical film piece and a method for manufacturing the same.

Background Art

[0002] Image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (for example, organic EL display devices) have been rapidly spreading. In image display devices, in order to realize image display and improve the performance of image display, generally, optical members such as polarizing members and retardation members are used (see, for example, Patent Document 1).

[0003] In recent years, new applications of image display devices have been developed. For example, goggles with a display (VR goggles) for realizing Virtual Reality (VR) have begun to be commercialized. Since VR goggles are being considered for use in various scenarios, weight reduction and improvement of visibility thereof are desired.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The weight reduction of the VR goggles can be achieved, for example, by thinning the lenses used in the VR goggles. On the other hand, the development of an optical member suitable for a display system using thin lenses is also desired.

[0006] In view of the above, a main object of the present invention is to provide an optical film piece that can satisfactorily achieve weight reduction of VR goggles while improving visibility.

Means for Solving the Problems

[0007] 1. An optical film piece according to an embodiment of the present invention includes a retardation member and is an optical film piece having a first main surface and a second main surface facing each other. On the first main surface, from a first portion located at the central portion to a second portion located outside the first portion, there is a first region where the standard deviation of the in-plane retardation Re(550) at a wavelength of 550 nm is 5 nm or less. On the first main surface, from the first portion to a third portion located outside the second portion, there is a second region where the standard deviation of the in-plane retardation Re(550) at a wavelength of 550 nm exceeds 5 nm. The average value of the in-plane retardation Re(550) at a wavelength of 550 nm in the first region is 135 nm or more. 2. In the optical film piece according to 1 above, the absolute value of the difference between the average value of the in-plane retardation Re(550) at a wavelength of 550 nm in the first region and the average value of the in-plane retardation Re(550) at a wavelength of 550 nm in the second region may be 5 nm or less. 3. The optical film piece according to 1 or 2 above may have a substantially circular shape in plan view, and the third portion may be located in a region within 40% of the radius of the first main surface from the edge of the first main surface in the radial direction in plan view.

[0008] 4. A method for manufacturing an optical film piece according to an embodiment of the present invention is a method for manufacturing an optical film piece according to any one of 1 to 3 above, and includes integrating a member including a retardation member with a component having a curved surface portion. The integration includes bringing the tip of a contact member into contact with the member in a deformable state to deform the member to form a protruding portion toward the curved surface portion, and bringing the protruding portion of the member into contact with the curved surface portion. 5. In the method for manufacturing an optical film piece according to 4 above, the curved surface portion of the component may have a concave surface. 6. In the method for manufacturing an optical film piece according to 4 or 5 above, the tip of the contact member may have a curved surface shape. 7. In the method for manufacturing the optical film piece according to the above 5 or 6, the tip of the contact member has a curved surface shape, and the ratio of the radius of curvature of the curved surface shape of the tip of the contact member to the radius of curvature of the curved surface portion of the component may be 0.65 or more. 8. In the method for manufacturing the optical film piece according to any one of the above 4 to 7, a region where the change amount of the in-plane retardation Re(550) at a wavelength of 550 nm of the retardation member due to the integration is 10 nm or less may be formed at the central portion of the optical film piece. 9. In the method for manufacturing the optical film piece according to the above 8, the component may be a lens.

Advantages of the Invention

[0009] According to the optical film piece according to the embodiment of the present invention, it is possible to satisfactorily achieve weight reduction of the VR goggles while improving visibility.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 4E

Figure 5

Figure 6A

Figure 6B

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. For the sake of clearer explanation, in the drawings, the widths, thicknesses, shapes, etc. of each part may be schematically represented compared to the embodiments, but this is merely an example and does not limit the interpretation of the present invention. Also, for the drawings, the same or equivalent elements may be given the same reference numerals, and duplicate explanations may be omitted.

[0012] (Definitions of Terms and Symbols) The definitions of the terms and symbols in this specification are as follows. (1) Refractive Index (nx, ny, nz) “nx” is the refractive index in the direction where the in-plane refractive index is maximum (i.e., the slow axis direction), “ny” is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and “nz” is the refractive index in the thickness direction. (2) In-Plane Phase Difference (Re) “Re(λ)” is the in-plane phase difference measured with light of wavelength λ nm at 23°C. For example, “Re(550)” is the in-plane phase difference measured with light of wavelength 550 nm at 23°C. Re(λ) can be obtained by the formula: Re(λ) = (nx - ny) × d, where d (nm) is the thickness of the layer (film). (3) Phase Difference in the Thickness Direction (Rth) “Rth(λ)” is the phase difference in the thickness direction measured with light of wavelength λ nm at 23°C. For example, “Rth(550)” is the phase difference in the thickness direction measured with light of wavelength 550 nm at 23°C. Rth(λ) can be obtained 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 obtained by Nz = Rth / Re. (5) Angle When referring to an angle in this specification, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Thus, for example, "45°" means ±45°.

[0013] [Optical film piece] The optical film piece according to an embodiment of the present invention typically includes optical members such as a retardation member and a polarizing member. In one embodiment, the optical film piece includes at least a retardation member such as a λ / 4 member, and in addition to the retardation member, may include other optical members. Specifically, the optical film piece can include a polarizing member. Further, the optical film piece can include other members such as a protective member and an adhesive layer for integrating adjacent members. The thickness of the optical film piece varies depending on, for example, the types and numbers of the included members, but is, for example, 50 μm to 400 μm.

[0014] FIG. 1 is a view of an optical film piece according to one embodiment of the present invention as seen from above, FIG. 2 is a schematic partial enlarged cross-sectional view showing the schematic configuration of the optical film piece shown in FIG. 1, and FIG. 3 is a schematic cross-sectional view showing a state in which the optical film piece shown in FIG. 1 is integrated with an optical component. In FIG. 3, for ease of viewing, the cross-sections of the optical component and the optical film piece omit hatching. Also, the details of the optical film piece are omitted.

[0015] The optical film piece 1 includes a retardation member 23 and an adhesive layer 40. The retardation member 23 is typically composed of a λ / 4 member. In this case, the retardation member 23 may have other retardation layers in addition to the λ / 4 member. When the retardation member 23 does not have other retardation layers, the retardation member 23 can be substantially a λ / 4 member.

[0016] The planar shape of the optical film piece 1 is substantially circular, but is not limited thereto. For example, the optical film piece 1 may be substantially elliptical or may be a rounded rectangular shape. The major axis of the optical film piece 1 in plan view is, for example, 10 mm to 100 mm. Here, the major axis in plan view is the distance between the two most separated points on the outer periphery of the optical film piece when viewed from above.

[0017] The optical film piece 1 has a first major surface 1a and a second major surface 1b that face each other. The first major surface 1a and the second major surface 1b of the optical film piece 1 have curved surfaces. In the illustrated example, the optical film piece 1 has a convex curvature on the second major surface 1b side, the first major surface 1a has a concave curved surface, and the second major surface 1b has a convex curved surface. In the example shown in FIG. 3, the optical film piece 1 is bonded to the concave surface of an optical component (for example, a lens) L having a curved surface portion by its adhesive layer 40 (not shown in FIG. 3), and the retardation member 23 has a convex curvature on the adhesive layer 40 side, and the major surface of the retardation member 23 has a curved surface. Different from the illustrated example, the optical film piece 1 may be bonded to the convex surface of the optical component L. The radius of curvature of the major surface of the optical film piece 1 is, for example, 10 mm or more and 150 mm or less, preferably 100 mm or less, and more preferably 90 mm or less. The radius of curvature can be confirmed, for example, using a laser displacement meter.

[0018] The in-plane retardation Re(550) of the above λ / 4 member 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. For example, the λ / 4 member preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light. In this case, Re(450) / Re(550) of the λ / 4 member is, for example, 0.75 or more and less than 1, and may be 0.8 or more and 0.95 or less.

[0019] The above λ / 4 member preferably exhibits 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, within a range that does not impair the effects of the present invention, ny < nz may occur. The Nz coefficient of the λ / 4 member 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.

[0020] The optical film piece 1 may have different retardation values (e.g., in-plane retardation Re) on the main surface. Specifically, the main surface of the optical film piece 1 may have a distribution of retardation values. For example, from the first part (e.g., the center) 1c located at the center of the first main surface 1a of the optical film piece 1 to the second part 1d located outside the first part 1c, it has a first region 71 where the standard deviation of the in-plane retardation Re(550) at a wavelength of 550 nm is 5 nm or less. The first region 71 may be a circular area centered on the first part 1c and having a radius equal to the distance between the first part 1c and the second part 1d in plan view. The standard deviation of the in-plane retardation Re(550) in the first region 71 is preferably 4.5 nm or less, more preferably 4 nm or less, still more preferably 3 nm or less, and particularly preferably 2 nm or less. By having the first region 71 with a small variation in retardation value at the center of the optical film piece 1, for example, a display body with excellent visibility can be obtained.

[0021] On the first major surface 1a of the optical film piece 1, in the third region 1e located outside the second region 1d from the first region 1c, it has a second region 72 where the standard deviation of the in-plane retardation Re(550) at a wavelength of 550 nm exceeds 5 nm. The second region 72 can be a circular area centered on the first region 1c and having a radius equal to the distance between the first region 1c and the third region 1e in plan view. The standard deviation of the in-plane retardation Re(550) in the second region 72 may be 5.5 nm or more, or 6 nm or more, or 7 nm or more, or 8 nm or more. Even if there is a relatively large variation in the retardation values in the second region 72, which includes the first region 71 and is wider than the first region 71, for example, it does not significantly affect the visibility of the resulting display body.

[0022] The average value of the in-plane retardation Re(550) in the first region 71 is, for example, 135 nm or more, preferably 135 nm or more and 155 nm or less, more preferably 135 nm or more and 150 nm or less. The average value of the in-plane retardation Re(550) in the second region 72 is, for example, 135 nm or more, preferably 135 nm or more and 155 nm or less, more preferably 135 nm or more and 150 nm or less. The absolute value of the difference between the average value of the in-plane retardation Re(550) in the first region 71 and the average value of the in-plane retardation Re(550) in the second region 72 is preferably 5 nm or less, more preferably 4 nm or less, still more preferably 3 nm or less, and particularly preferably 2 nm or less.

[0023] For example, in a plan view, the third part 1e is preferably located in a region radially inward from the edge of the first main surface 1a (optical film piece 1) and within 40% or less of the radius of the first main surface 1a, more preferably within 30% or less of the radius of the first main surface 1a, and even more preferably within 20% or less of the radius of the first main surface 1a. Also, for example, the line connecting the point facing the first region 71 of the concave surface of the lens L and the focal point of the lens L preferably forms an angle of 5° or more with respect to the line connecting the center of the lens L and the focal point of the lens L, more preferably 10° or more, and even more preferably 15° or more. By satisfying such an angle, for example, a display body with extremely excellent visibility can be obtained.

[0024] The in-plane retardation Re(550) in the third part 1e may be larger or smaller than the in-plane retardation Re(550) in the first part 1c. In one embodiment, in the peripheral portion of the first main surface 1a of the optical film piece 1, there may be a mixture of a part where the in-plane retardation Re(550) is larger than the in-plane retardation Re(550) in the first part 1c and a part where the in-plane retardation Re(550) is smaller than the in-plane retardation Re(550) in the first part 1c.

[0025] The above λ / 4 member can be, for example, a stretched film of a resin film or an alignment solidified layer of a liquid crystal compound.

[0026] Examples of the resin contained in the 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, acrylic resins, and the like. These resins may be used alone or in combination. Examples of the combination method include blending and copolymerization. When the λ / 4 member 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 preferably used.

[0027] As the polycarbonate resin, any suitable polycarbonate resin can be used. For example, the polycarbonate resin includes 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, di-, tri- or polyethylene glycol, and an alkylene glycol or spiroglycol. Preferably, the polycarbonate resin includes 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 an alicyclic dimethanol and / or a structural unit derived from di-, tri- or polyethylene glycol; More preferably, it includes 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 di-, tri- or polyethylene glycol. The polycarbonate resin may optionally contain a structural unit derived from other dihydroxy compounds. Details of the polycarbonate resin and the method for forming the λ / 4 member that can be suitably used for the λ / 4 member are described, for example, in JP-A Nos. 2014-10291, 2014-26266, 2015-212816, 2015-212817, and 2015-212818, and the descriptions of these publications are incorporated herein by reference.

[0028] The thickness of the λ / 4 member composed of the stretched film of the resin film is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, and more preferably 20 μm to 60 μm.

[0029] The alignment and curing layer of the liquid crystal compound is a layer in which the liquid crystal compound is aligned in a predetermined direction within the layer and its alignment state is fixed. Note that the "alignment and curing layer" is a concept that includes the alignment and curing layer obtained by curing a liquid crystal monomer as described later. In the λ / 4 member, typically, rod-shaped liquid crystal compounds are aligned in the direction of the slow axis of the λ / 4 member (homogeneous alignment). Examples of rod-shaped liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably polymerizable. When the liquid crystal compound is polymerizable, the alignment state of the liquid crystal compound can be fixed by polymerizing the liquid crystal compound after aligning it.

[0030] The alignment and curing layer (liquid crystal alignment and curing layer) of the above liquid crystal compound can be formed by subjecting the surface of a predetermined substrate to an alignment treatment, coating the surface with a coating liquid containing the liquid crystal compound to align the liquid crystal compound in the direction corresponding to the above alignment treatment, and fixing the alignment state. As the alignment treatment, any appropriate alignment treatment can be adopted. 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 evaporation method and photoalignment treatment. The treatment conditions of various alignment treatments can be any appropriate conditions according to the purpose.

[0031] The alignment of the liquid crystal compound is performed by treating it at the temperature at which the liquid crystal phase is exhibited according to the type of the liquid crystal compound. By performing such a temperature treatment, the liquid crystal compound takes a liquid crystal state and the liquid crystal compound aligns according to the alignment treatment direction of the substrate surface.

[0032] In one embodiment, the fixation of the alignment state is performed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is polymerizable or crosslinkable, the fixation of the alignment state is performed by subjecting the liquid crystal compound aligned as described above to a polymerization treatment or a crosslinking treatment.

[0033] 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 a method for producing the liquid crystal alignment curing layer are described in, for example, JP-A-2006-163343, JP-A-2006-178389, and WO 2018 / 123551. The descriptions in these publications are incorporated herein by reference.

[0034] The thickness of the λ / 4 member composed of the liquid crystal alignment curing layer is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and even more preferably 1 μm to 4 μm.

[0035] As described above, the retardation member 23 may have another retardation layer in addition to the λ / 4 member. As the other retardation layer, for example, a layer showing the relationship of nz > nx ≧ ny can be used. The other retardation layer is typically laminated on the λ / 4 member via an adhesive layer.

[0036] The in-plane retardation Rth(550) in the thickness direction of the layer showing the relationship of nz > nx ≧ ny for the refractive index characteristics is preferably -260 nm to -10 nm, more preferably -230 nm to -15 nm, and even more preferably -215 nm to -20 nm. In one embodiment, the other retardation layer is a so-called positive C-plate in which its refractive index shows the relationship of nx = ny. Here, "nx = ny" includes not only the case where nx and ny are exactly equal but also the case where nx and ny are substantially equal. For example, it also includes the case where Re(550) is less than 10 nm. In another embodiment, the other retardation layer has a refractive index relationship of nx > ny. In this case, the in-plane retardation Re(550) of the other retardation layer is preferably 10 nm to 150 nm, more preferably 10 nm to 80 nm.

[0037] A layer showing the refractive index characteristic of nz > nx ≧ ny can be formed of any suitable material. Preferably, it is composed of a film containing a liquid crystal material fixed in a homeotropic orientation. The liquid crystal material (liquid crystal compound) that can be homeotropically oriented may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of such liquid crystal compounds and film forming methods include those described in paragraphs

[0020] to

[0042] of JP-A-2002-333642. In this case, the thickness is preferably 0.1 μm to 5 μm, more preferably 0.5 μm to 4 μm.

[0038] As another preferred specific example, the layer showing the refractive index characteristic of nz > nx ≧ ny may be a retardation film formed of a fumaric acid diester resin described in JP-A-2012-32784. In this case, the thickness is preferably 5 μm to 50 μm, more preferably 10 μm to 35 μm.

[0039] <Manufacturing Method> The optical film piece can be obtained by integrating at least a member including a retardation member with the curved surface portion of an optical component (for example, the lens L shown in FIG. 3). The integration can typically be performed by bonding a member including a retardation member to the curved surface portion of an optical component (for example, the lens L) using an adhesive layer. And the obtained optical film piece may include an adhesive layer (the adhesive layer 40 shown in FIG. 2).

[0040] FIGS. 4A to 4E are diagrams showing an example of a method for manufacturing an optical film piece according to one embodiment of the present invention.

[0041] FIG. 4A shows a state in which an adhesive layer 40 is provided on the retardation member 23 or the laminated part including the retardation member 23 to prepare the workpiece 2, and the workpiece 2 is disposed above the lens L which is an adherend. In FIG. 4, details of the workpiece 2 are omitted. The lens L is, for example, circular in plan view and has a concave shape in cross section. The radius of curvature of the curved surface portion of the lens L is, for example, 10 mm or more and 150 mm or less, preferably 100 mm or less, and more preferably 90 mm or less. The workpiece 2 is disposed at a predetermined interval from the concave surface (upper surface) of the lens L. The lens L is placed on the holding portion 52 on the liftable holding table 51 accommodated in the lower chamber 50. The end portion 2a of the workpiece 2 is sandwiched between the upper chamber 60 and the lower chamber 50.

[0042] FIG. 4B shows a state in which the space where the workpiece 2 is disposed is depressurized and the workpiece 2 is heated. Specifically, after depressurizing the inside of the upper chamber 60 and the lower chamber 50 by a vacuum device (not shown), the workpiece 2 is heated. The shape of the workpiece 2 can be easily deformed by heating. The heating temperature of the workpiece 2 is preferably 50°C or more and 150°C or less.

[0043] When the space where the workpiece 2 is disposed is depressurized and the workpiece 2 is in a state where it is easily deformed, as shown in FIG. 4C, the contact member 61 provided in the upper chamber 60 is lowered, and the tip 61a of the contact member 61 is brought into contact with and pressed against the workpiece 2. By pressing, a part of the workpiece 2 is deformed according to the shape of the tip 61a of the contact member 61, and a protruding portion 2b having a shape toward the lens L is formed. When contacting the workpiece 2, the contact member 61 may or may not be heated.

[0044] The tip 61a of the contact member 61 preferably has a curved surface shape (for example, a part of a sphere). In this case, the radius of curvature of the tip 61a of the contact member 61 is, for example, 10 mm to 150 mm. The ratio of the radius of curvature of the tip 61a of the contact member 61 to the radius of curvature of the curved surface portion (concave surface) of the lens L (radius of curvature of the tip 61a of the contact member 61 / radius of curvature of the curved surface portion of the lens L) is, for example, 0.25 or more and 1 or less, preferably 0.5 or more and 0.99 or less, and more preferably 0.65 or more.

[0045] FIG. 4D shows a state where the bonding of the workpiece 2 has started. With the contact member 61 in contact with (pressed against) a part of the workpiece 2, the holding table 51 is raised to bring the workpiece 2 (the protruding portion 2b) into contact with at least the central portion of the lens L. After the contact, the workpiece 2 can be bonded to the entire surface of the lens L outward from the contact portion between the lens L and the workpiece 2 (for example, radially). For example, after the contact, the air pressure in the upper chamber 60 is gradually increased. The air pressure in the upper chamber 60 becomes higher than the air pressure in the lower chamber 60, and a differential pressure can be generated between the two spaces. Due to this differential pressure, the workpiece 2 is gradually drawn downward, and as shown in FIG. 4E, the workpiece 2 can be bonded to the entire surface of the lens L. When the bonding of the workpiece 2 is performed without using the contact member 61, when the holding table 51 is raised, the peripheral portion of the lens L may come into contact with the workpiece 2, and the workpiece 2 can be bonded from the peripheral portion to the central portion of the lens L. After the bonding, unnecessary portions of the workpiece 2 (for example, portions that do not overlap with the lens L in plan view) are removed, and the optical film piece 1 as shown in FIG. 3 can be obtained.

[0046] When integrating with the curved surface portion, the retardation member (workpiece) can be stretched. Depending on the shape of the curved surface portion and the like, variations can occur in the degree of stretching. Due to stretching, the retardation value of the retardation member can change. And depending on the degree of stretching, the degree of change in the retardation value can be different. As a result, in the in-plane (first main surface 1a) of the obtained optical film piece 1, the retardation value (for example, in-plane retardation Re) can be different. On the other hand, for example, as shown in FIG. 4, in advance, a contact member is brought into contact with the retardation member (workpiece) to deform the retardation member to form a protruding portion toward the curved surface portion, and the retardation member is integrated with the curved surface portion starting from this protruding portion, whereby an optical film piece having the above first region can be manufactured favorably.

[0047] For example, it is preferable that the change in the retardation value of the retardation member, for example, before and after integration into the optical component is small. By the change amount being small, an optical film piece having desired optical characteristics (for example, retardation value) can be easily obtained. Specifically, the change amount of the in-plane retardation Re(550) before and after integration into the optical component is preferably 10 nm or less, more preferably 9 nm or less, and even more preferably 8 nm or less. In one embodiment, facing the central portion of the lens L, the change amount of the in-plane retardation Re(550) at the central portion of the obtained optical film piece 1 is preferably 10 nm or less, more preferably 9 nm or less, and even more preferably 8 nm or less. The line connecting the point facing the central portion of the concave surface of the lens L that can satisfy the above change amount and the focal point of the lens L preferably forms an angle of 5° or more with respect to the line connecting the center of the lens L and the focal point of the lens L, more preferably 10° or more, and even more preferably 15° or more.

[0048] The change amount of the retardation value can be, for example, the difference between the average value of the retardation value in a predetermined region and the average value of the retardation value of the entire retardation member before integration.

[0049] The optical film piece according to an embodiment of the present invention can include any suitable other optical member in addition to the retardation member. And the optical film piece can be used for any suitable display body. The optical film piece can be suitably used for, for example, a VR goggles.

[0050] [Display system] FIG. 5 is a schematic diagram showing a schematic configuration of an example of a display system of a VR goggles, schematically illustrating 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, a half mirror 18, a first λ / 4 member 20, a second λ / 4 member 22, and a second lens unit 24. The reflective polarizing member 14 is disposed in front of the display surface 12a side of the display element 12 and can reflect the 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 λ / 4 member 20 is disposed on the optical path between the display element 12 and the half mirror 18, and the second λ / 4 member 22 is disposed on the optical path between the half mirror 18 and the reflective polarizing member 14.

[0051] The half mirror, or the components disposed forward from the first lens unit (in the illustrated example, the half mirror 18, the first lens unit 16, the second λ / 4 member 22, the reflective polarizing member 14, and the second lens unit 24) may be collectively referred to as a lens unit (lens unit 4).

[0052] 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 included in the display element 12 and is emitted as a first linearly polarized light.

[0053] The first λ / 4 member 20 can convert the first linearly polarized light incident on the first λ / 4 member 20 into a first circularly polarized light. The first λ / 4 member 20 may be provided integrally with the display element 12.

[0054] 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 unit 16.

[0055] 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 unit 16.

[0056] The first circularly polarized light emitted from the first λ / 4 member 20 passes through the half mirror 18 and the first lens unit 16 and is converted into second linearly polarized light by the second λ / 4 member 22. The second linearly polarized light emitted from the second λ / 4 member 22 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.

[0057] The second linearly polarized light reflected by the reflective polarizing member 14 is converted into second circularly polarized light by the second λ / 4 member 22, and the second circularly polarized light emitted from the second λ / 4 member 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 member 22. 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.

[0058] The light that has passed through the reflective polarizing member 14 passes through the second lens unit 24 (the absorption-type polarizing member 28 and the second lens unit 24 described later) and enters the user's eye 26.

[0059] The absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 14 may be arranged substantially parallel to each other or substantially perpendicular to each other. The angle formed by 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°, may be 42° to 48°, or may be about 45°. The angle formed by 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°, may be 42° to 48°, or may be about 45°.

[0060] Regarding the optical properties (in-plane retardation Re(550) and Re(450) / Re(550)) of the first λ / 4 member 20 and the second λ / 4 member 22, they are as described above, respectively.

[0061] The display system 10 may include an absorption-type polarizing member 28. The absorption-type polarizing member 28 can be arranged in front of the reflective polarizing member 14. The reflection axis of the reflective polarizing member 14 and the absorption axis of the absorption-type polarizing member 28 can be arranged substantially parallel to each other, and the transmission axis of the reflective polarizing member 14 and the transmission axis of the absorption-type polarizing member 28 can be arranged substantially parallel to each other. The reflective polarizing member 14 and the absorption-type polarizing member 28 may be integrated. The absorption-type polarizing member 28 can be used, for example, from the viewpoint of improving visibility in the above display system.

[0062] In the display system 10, a space may be formed between the first lens unit 16 and the second lens unit 24. In this case, the member arranged between the first lens unit 16 and the second lens unit 24 is preferably provided integrally with either the first lens unit 16 or the second lens unit 24. For example, the member arranged between the first lens unit 16 and the second lens unit 24 is integrated with either the first lens unit 16 or the second lens unit 24 via an adhesive layer. According to such a form, for example, the handleability of each member can be excellent. The adhesive layer may be formed of an adhesive or a pressure-sensitive adhesive. Specifically, the adhesive layer may be an adhesive layer or a pressure-sensitive adhesive layer. The thickness of the adhesive layer is, for example, 0.01 μm to 60 μm.

[0063] The optical film piece according to an embodiment of the present invention can include, for example, a member provided in the above display system. For example, the optical film piece according to an embodiment of the present invention can include a second λ / 4 member 22. Specifically, the retardation member 23 of the optical film piece 1 in the illustrated example can correspond to the second λ / 4 member 22. Further, the optical film piece 1 may include a reflective polarizing member 14 in addition to the retardation member 23 (second λ / 4 member 22). Furthermore, the optical film piece 1 may include an absorptive polarizing member 28. The optical film piece can include other members such as an adhesive layer for integrating adjacent members.

[0064] The optical film piece 1 can be integrated, for example, with the first lens portion 16 or the second lens portion 24. Typically, it can be bonded to the first lens portion 16 or the second lens portion 24, which are adherends, via an adhesive layer. For example, the first lens portion 16 shown in FIG. 5 has a curved surface portion and can correspond to the above optical component (lens L). By positioning the first region 71 of the optical film piece 1 at the central portion of the lens L (first lens portion 16), for example, a display body with excellent visibility can be obtained.

Example

[0065] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. Note that the thickness is a value measured by the following measurement method. <Thickness> For a thickness of 10 μm or less, it was measured using a scanning electron microscope (manufactured by JEOL Ltd., product name "JSM-7100F"). For a thickness exceeding 10 μm, it was measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C").

[0066] [Example 1] (Production of λ / 4 member) 55 parts of the compound represented by formula (I), 25 parts of the compound represented by formula (II), and 20 parts of the compound represented by formula (III) were added to 400 parts of cyclopentanone (CPN). After that, the mixture was heated to 60 °C and stirred until dissolved. After dissolution was confirmed, the mixture was returned to room temperature, and 3 parts of Irgacure 907 (manufactured by BASF Japan Ltd.), 0.2 part of Megafac F-554 (manufactured by DIC Corporation), and 0.1 part of p-methoxyphenol (MEHQ) were added, followed by further stirring to obtain a solution. The solution was transparent and homogeneous. The obtained solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. The polyimide solution for the alignment film was applied to a glass substrate with a thickness of 0.7 mm by spin coating. After drying at 100 °C for 10 minutes, a coating film was obtained by 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. The polymerizable composition obtained above was applied to the alignment film (substrate) by spin coating and dried at 100 °C for 2 minutes. After the obtained coating film was cooled to room temperature, it was irradiated with ultraviolet rays at an intensity of 30 mW / cm 2 for 30 seconds using a high-pressure mercury lamp to obtain a liquid crystal alignment cured layer with a thickness of 3 μm. The obtained liquid crystal alignment cured layer had an in-plane retardation Re(550) of 141 nm, Re(450) / Re(550) of 0.851, and showed an inverse dispersion wavelength characteristic. The value of the in-plane retardation above is the average value (unit: nm) obtained by cutting out the obtained liquid crystal alignment cured layer into a size of 100 mm × 100 mm and performing area analysis on the entire cut measurement sample using a two-dimensional birefringence evaluation device (manufactured by Photonic Lattice, product name "WPA-200").

[0067]

Chemical formula

Chemical formula

[0068] (Fabrication of the workpiece) The acrylic adhesive composition was coated on the λ / 4 member side and dried to form an adhesive layer with a thickness of 40 μm, thereby obtaining a workpiece.

[0069] (Production of optical film piece) As shown in FIGS. 4A to 4E, the obtained workpiece was bonded to the curved surface (concave surface) of a lens having a diameter (major axis) of 50 mm and a radius of curvature of 40 mm. When bonding, a contact member with a tip having a curved surface shape (radius of curvature of 12.5 mm) was used. After bonding, the portions that did not overlap with the lens in plan view were removed to obtain an optical film piece.

[0070] [Example 2] An optical film piece was obtained in the same manner as in Example 1, except that a contact member having a curved surface shape with a radius of curvature of 25 mm at the tip was used when bonding.

[0071] [Example 3] An optical film piece was obtained in the same manner as in Example 1, except that a contact member having a curved surface shape with a radius of curvature of 35 mm at the tip was used when bonding.

[0072] [Example 4] An optical film piece was obtained in the same manner as in Example 1, except that a contact member having a curved surface shape with a radius of curvature of 38 mm at the tip was used when bonding.

[0073] [Comparative Example 1] An optical film piece was obtained in the same manner as in Example 1, except that no contact member was used when bonding.

[0074] The distribution of the retardation values of the optical film pieces in each example and comparative example was evaluated by the following method. The evaluation results are summarized in Table 1.

[0075] <Evaluation> The in-plane retardation distribution of the optical film pieces obtained in the examples and comparative examples was evaluated using a two-dimensional birefringence evaluation apparatus (manufactured by Photonic Lattice, product name "WPA-200"). Specifically, at a measurement wavelength of 550 nm, the in-plane retardation Re(550) of the optical film pieces while attached to the lens was subjected to area analysis in each of areas A to D, and the average value (unit: nm) and standard deviation σ in each area were determined. The "difference" in Table 1 indicates the difference between the average value and the value before bonding. Here, as shown in FIG. 6A, "area A" means an area within a circle with a radius of 6.53 mm centered on the portion facing the point through which the optical axis of the lens passes in plan view, "area B" means an area within a circle with a radius of 13.06 mm centered on the portion facing the point through which the optical axis of the lens passes in plan view, "area C" means an area within a circle with a radius of 18.69 mm centered on the portion facing the point through which the optical axis of the lens passes in plan view, and "area D" means an area within a circle with a radius of 24.06 mm centered on the portion facing the point through which the optical axis of the lens passes in plan view. The focal length of the lens used was 80 mm. As shown in FIG. 6B, the line connecting the point located within area A and the focus of the lens forms an angle of 5° or less with the line connecting the center of the lens and the focus of the lens, the line connecting the point located within area B and the focus of the lens forms an angle of 10° or less with the line connecting the center of the lens and the focus of the lens, the line connecting the point located within area C and the focus of the lens forms an angle of 15° or less with the line connecting the center of the lens and the focus of the lens, and the line connecting the point located within area D and the focus of the lens forms an angle of 18° or less with the line connecting the center of the lens and the focus of the lens.

[0076]

Table 1

[0077] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, it can be replaced with a configuration that is substantially the same as the configuration shown in the above-described embodiments, a configuration that exhibits the same operational effects, or a configuration that can achieve the same purpose.

Industrial Applicability

[0078] The optical film piece according to the embodiment of the present invention can be used, for example, for a display such as a VR goggle.

Explanation of Signs

[0079] 1 Optical film piece 2 Workpiece 1a First main surface 1b Second main surface 1c First part 1d Second part 1e Third part 10 Display system 12 Display element 14 Reflective polarizing member 16 First lens part 18 Half mirror 20 First λ / 4 member 22 Second λ / 4 member 23 Phase difference member 24 Second lens part 40 Adhesive layer 61 Contact member 71 First region 72 Second region L Lens

Claims

1. An optical film piece including a retardation member and having a first main surface and a second main surface facing each other, on the first main surface, from a first portion located at the center to a second portion located outside the first portion, having a first region where the standard deviation of the in-plane retardation Re(550) at a wavelength of 550 nm is 5 nm or less, on the first main surface, from the first portion to a third portion located outside the second portion, having a second region where the standard deviation of the in-plane retardation Re(550) at a wavelength of 550 nm exceeds 5 nm, wherein the average value of the in-plane retardation Re(550) at a wavelength of 550 nm in the first region is 135 nm or more, Optical film piece.

2. The optical film piece according to claim 1, wherein the absolute value of the difference between the average value of the in-plane retardation Re(550) at a wavelength of 550 nm in the first region and the average value of the in-plane retardation Re(550) at a wavelength of 550 nm in the second region is 5 nm or less.

3. The planar shape is substantially circular, wherein the third portion is located in a region within 40% of the radius of the first main surface from the edge of the first main surface in a plan view, the optical film piece according to claim 1.

4. A method for manufacturing the optical film piece according to claim 1, comprising integrating a member including a retardation member with a component having a curved surface portion, wherein the integration includes bringing the tip of a contact member into contact with the member in a deformable state to deform the member to form a protruding portion toward the curved surface portion, and bringing the protruding portion of the member into contact with the curved surface portion, A method for manufacturing an optical film piece.

5. The manufacturing method according to claim 4, wherein the curved surface portion of the component has a concave surface.

6. The manufacturing method according to claim 4, wherein the tip of the contact member has a curved surface shape.

7. The manufacturing method according to claim 5, wherein the tip of the contact member has a curved surface shape, and the ratio of the radius of curvature of the curved surface shape of the tip of the contact member to the radius of curvature of the curved surface portion of the component is 0.65 or more.

8. The manufacturing method according to claim 4, wherein a region where the change amount of the in-plane retardation Re(550) at a wavelength of 550 nm of the retardation member due to the integration is 10 nm or less is formed at the center of the optical film piece.

9. The manufacturing method according to claim 8, wherein the component is a lens.

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