Method for manufacturing louver film

Abstract

This method involves manufacturing a louver film (1) equipped with an optical functional layer (2) in which light transmission parts (4) and louvers (3) are alternately arranged, through a first step (S1), a second step (S2), and a third step (S3). In the second step (S2), a first member (10) and a second member (20) that are formed in the first step (S1) are laminated such that first protrusion parts (11) protruding from a first light transmission layer (5) of the first member (10) and second protrusion parts (21) protruding from a second light transmission layer (6) of the second member (20) face each other, and a molding material (30) is fed between both members to bring the second protrusion parts (21) into contact with the first protrusion parts (11). Accordingly, gaps (40), which result from the difference in shape between the first protrusion parts (11) and the second protrusion parts (21), are formed between the first light transmission layer (5) and the second light transmission layer (6) at a predetermined arrangement pitch, and the molding material (30) fills the gaps (40). In the third step (S3), the molding material (30) is hardened to form louvers (3).

Description

Louver film manufacturing method

[0001] The present invention relates to a method for manufacturing a louver film having an optical functional layer in which light-transmitting portions and louvers are arranged alternately.

[0002] Louver films have been used in the past, which have an optical functional layer in which louvers that absorb or reflect light and light-transmitting portions are arranged alternately. This type of louver film is used for a variety of purposes. For example, by attaching it to the display screen of a mobile device or the like, it is used for preventing peeping, preventing reflections, and preventing light leakage. It is also used on screens that project images to block unnecessary light (external light) and transmit necessary light (projected light). It is also used in goggles, sunglasses, building materials, etc.

[0003] Patent Documents 1 and 2 describe this type of louver film. The louver film in Patent Document 1 includes a louver layer in which light-absorbing portions (louvers) and light-transmitting portions are alternately arranged, and is bonded to the surface of a liquid crystal panel via an adhesive layer. The light-absorbing portions and light-transmitting portions extend linearly in a direction perpendicular to the arrangement direction. The light-absorbing portions have, for example, a trapezoidal cross-sectional shape.

[0004] The louver film of Patent Document 1 is manufactured by the following method. First, a resin material is supplied to a mold having an inverted shape of the light-transmitting portions, cured, and then demolded. This produces a film with grooves formed between the light-transmitting portions arranged at a fixed pitch. Next, the material that constitutes the light-absorbing portions, such as a UV-curable resin, is filled into the grooves, and any resin that protrudes from the grooves is removed, after which the material is irradiated with UV light and cured. This forms the light-absorbing portions (louvers).

[0005] Patent Document 2 describes a louver element arranged in the optical path of a head-mounted display. The louver element in Patent Document 2 has a structure in which a light-transmitting resin member (first member) having triangular prism-shaped convex portions arranged in a sawtooth pattern and a light-transmitting resin member (second member) having a similar structure, with a light-shielding layer arranged at a constant pitch sandwiched between them. The first member and the second member have surfaces that form the hypotenuses of the prism shapes in contact with each other, and the light-shielding layer is sandwiched between the side surfaces that form the short sides of the prism shapes.

[0006] The louver element of Patent Document 2 is manufactured by the following method. First, a resin material is applied to a mold to form a first member with prism-shaped convex portions arranged in a sawtooth pattern, and the mold is then released. Next, a paint or the like is applied to the side surfaces that form the short sides of the prism shapes, and the paint is heated and cured to form a light-blocking layer. Next, a resin material is applied over the light-blocking layer, filling the grooves between adjacent prism shapes with the resin material, and then the resin is cured. This forms a second member with the light-blocking layer sandwiched between it and the first member.

[0007] JP 2018-45052 A JP 2023-60578 A

[0008] The manufacturing method of Patent Document 1 requires that the grooves between the light-transmitting portions, which are formed first, be the inverted shape of the light-absorbing portions (louvers). However, in order to increase the inclination angle of the louvers, the inclination angle of the grooves must also be increased. In this case, the manufacturing process may become more difficult, and depending on the inclination angle, manufacturing may even be difficult. Furthermore, it is difficult to form the grooves into an undercut shape.

[0009] On the other hand, the manufacturing method of Patent Document 2 involves applying paint, which is the material for the light-blocking layer (louvers), to the surface of the prism, so the degree of freedom in the inclination of the louvers is higher than that of the method of Patent Document 1. However, because the light-blocking layer is formed by heating and curing the coating, it is difficult to increase the thickness of the louvers, and it is also difficult to create a shape in which the thickness changes midway. Therefore, the degree of freedom in the shape of the louvers is low.

[0010] In view of the above problems, the object of the present invention is to propose a method for manufacturing a louver film that allows for greater freedom in the shape and inclination angle of the louvers while avoiding an increase in the difficulty of manufacturing.

[0011] In order to solve the above-mentioned problems, one aspect of the present invention is a method for manufacturing a louver film having an optical functional layer in which light-transmitting portions and louvers are arranged alternately, the method comprising the steps of: a first step of manufacturing a first member having a first light-transmitting layer and a plurality of first convex portions protruding from the first light-transmitting layer; and a second member having a second light-transmitting layer and a plurality of second convex portions protruding from the second light-transmitting layer and arranged at the same arrangement pitch as the first convex portions; a second step of supplying a molding material between the first member and the second member and bonding them together, thereby abutting the second convex portions against each of the plurality of first convex portions to form a plurality of the light-transmitting portions arranged at the arrangement pitch and forming gaps filled with the molding material between adjacent light-transmitting portions; and a third step of hardening the molding material to form the louvers between the first light-transmitting layer and the second light-transmitting layer, the louvers having a shape that matches the gaps.

[0012] In this manufacturing method, the louvers are formed by utilizing the gaps formed between the first convex portions on the first member and the second convex portions on the second member. This makes it possible to form gaps with undercut shapes or gaps with large inclination angles without increasing the manufacturing difficulty of the first and second members. This allows for greater freedom in the shape and inclination of the louvers, while also avoiding increased manufacturing difficulty.

[0013] Furthermore, with this manufacturing method, the shape precision of the louver is comparable to that of the first and second convex portions, so the shape precision of the louver can be improved compared to methods of forming louvers using a coating film. Furthermore, it is easy to accommodate larger first and second members, and it is easy to accommodate larger louver films. In addition, after the louver is formed, the first light-transmitting layer and the second light-transmitting layer can be used as protective layers that cover the optical functional layer. Therefore, the process of separately providing a protective layer can be omitted.

[0014] In the above aspect, the arrangement pitch is preferably 5 μm or more and 500 μm or less, which allows louvers of various sizes to be formed, thereby forming an optical functional layer that can be used for a variety of purposes.

[0015] In the above aspect, the first step preferably includes supplying a UV-curable resin to a first mold surface on which the inverted shapes of the first convex portions are arranged, curing the resin while applying pressure through a first substrate layer, and then releasing the resin from the first mold surface to form the first light-transmitting layer having a two-layer structure in which the first substrate layer is bonded to a first base layer formed integrally with the first convex portions. The second step preferably includes supplying a UV-curable resin to a second mold surface on which the inverted shapes of the second convex portions are arranged, curing the resin while applying pressure through a second substrate layer, and then releasing the resin from the second mold surface to form the second light-transmitting layer having a two-layer structure in which the second substrate layer is bonded to a second base layer formed integrally with the second convex portions. This manufacturing method allows all of the first convex portions and second convex portions to be formed on the surfaces of large first and second members at once. This facilitates large-scale manufacturing.

[0016] In the above aspect, it is preferable that the thickness of the first base layer and the thickness of the second base layer are both 100 μm or less. By setting the thickness of the base layer, which does not affect the optical properties, to 100 μm or less, the entire louver film can be made thinner.

[0017] In the above-described embodiment, the molding material is preferably a UV-curable ink having adhesive or tackiness. Such a molding material is easy to fill gaps. Furthermore, the molding material can be cured by irradiating UV light from above the first base layer and the second base layer.

[0018] In the above aspect, it is preferable that at least a portion of the louver has a thickness of 3 μm or more, thereby ensuring a thickness that provides a light control function.

[0019] In the above aspect, it is preferable that the first convex portion is a first prism having a triangular cross-sectional shape including a first surface and a second surface intersecting the first surface, the second convex portion is a second prism having a triangular cross-sectional shape including a third surface and a fourth surface intersecting the third surface, the inclination angle of the first surface with respect to the first light-transmitting layer is the same as the inclination angle of the third surface with respect to the second light-transmitting layer, and the second step is to abut the first surface with the third surface and form the gap between the second surface and the fourth surface. In this way, by appropriately setting the inclination of the slope of the prism and the height of the prism, it is possible to form louvers with various inclination angles, thicknesses, and shapes without increasing the difficulty of manufacturing.

[0020] In the above aspect, it is preferable that the inclination angle of the second surface relative to the first light-transmitting layer is different from the inclination angle of the fourth surface relative to the second light-transmitting layer, and that in the second step, the gap is formed to have a wedge-shaped cross section surrounded by the second surface and the fourth surface. By forming the cross section of the louver in a wedge shape, a light control effect different from that of a louver with a constant thickness can be obtained. For example, the amount of light transmitted gradually changes with changes in the incident angle, resulting in a light control effect of gradually darkening or brightening. Furthermore, compared to a louver with a constant thickness, the longer perimeter and smaller volume allow UV light and the like to be transmitted more efficiently. This reduces the risk of uncured molding material remaining.

[0021] In the above aspect, it is preferable that the second surface is perpendicular to the first light-transmitting layer, and the fourth surface is perpendicular to the second light-transmitting layer, and in the second step, the gap having a constant width perpendicular to the first base material layer and the second base material layer is formed between the second surface and the fourth surface. In this way, it is possible to form a plate-shaped louver that is completely perpendicular to the incident surface of the optical function layer and has a uniform thickness.

[0022] In the above aspect, it is preferable that the apex angles of the first prism and the second prism are both greater than 10°. This avoids an increase in the difficulty of manufacturing the prisms. Furthermore, since the tips of the prisms are less likely to deform, a decrease in the shape precision of the louver can be suppressed.

[0023] In the above aspect, the first convex portion is a first prism having a trapezoidal cross-sectional shape including a first upper base surface, a first slope connected to one end of the first upper base surface, and a second slope connected to the other end of the first upper base surface, and the second convex portion is a second prism having a trapezoidal cross-sectional shape including a second upper base surface having the same length as the first upper base surface, a third slope connected to one end of the second upper base surface, and a fourth slope connected to the other end of the second upper base surface, and in the second step, the second upper base surface of the second prism is preferably abutted against the first upper base surfaces of each of the plurality of first prisms to form the gap surrounded by the opposing first and third slopes, and the opposing second and fourth slopes. In this way, by forming the prisms into a trapezoidal shape, it is possible to ensure the width of the light-transmitting portion between the louvers even when the inclination angle of the louvers is increased.

[0024] In the above-described aspect, it is preferable that the first prism and the second prism have the same shape. This reduces the number of types of components and management costs. Furthermore, the number of types of mold components used in manufacturing can be reduced, thereby reducing manufacturing costs.

[0025] In the above aspect, it is preferable that the angle between the first slope and the second slope, and the angle between the third slope and the fourth slope are both 60° to 120°. This allows the angle of the corners of the louver to be in a range close to 90° (60° to 120°). This allows the cross-sectional shape of the louver to be close to a rectangle.

[0026] In the above aspect, it is preferable that the angle between the first slope and the second slope and the angle between the third slope and the fourth slope are both 90°, and that the length of the second slope when the length of the first slope is 1 and the length of the fourth slope when the length of the third slope is 1 are 2 to 5. When the angle of the corners of the louver is 90°, the cross-sectional shape of the louver becomes rectangular. This causes the amount of light transmission to change rapidly at a specific incident angle, resulting in a dimming effect that switches light on and off at a specific incident angle. Furthermore, the dimensional ratio between the short side and the long side of the louver is large, allowing for a large change in the amount of light transmission during dimming.

[0027] In the above aspect, it is preferable that the length of the first upper base surface and the length of the second upper base surface are both 1 μm or more and 100 μm or less, which allows light-transmitting portions of various widths to be formed, thereby forming an optical functional layer that can be used for various purposes.

[0028] According to the present invention, the degree of freedom in the shape and inclination of the louvers can be increased, and further, an increase in the difficulty of manufacturing can be avoided.

[0029] FIG. 1 is a perspective view schematically showing the configuration of the louver film of embodiment 1 as seen from the end surface side. FIG. 2 is an explanatory diagram of a usage state of the louver film. FIG. 3 is a flowchart of a method for manufacturing a louver film. FIG. 4 is an explanatory diagram of a method for manufacturing a louver film of embodiment 1 (first step). FIG. 5 is an explanatory diagram of a method for manufacturing a louver film of embodiment 1 (second step). FIG. 6 is an explanatory diagram of a method for manufacturing a louver film of embodiment 1 (third step). FIG. 7 is an explanatory diagram of a louver film manufactured using a first member and a second member manufactured by extrusion molding. FIG. 8 is a cross-sectional view of a louver film of modified example 1. FIG. 9 is a cross-sectional view of a louver film of embodiment 2. FIG. 10 is a cross-sectional view of a louver film of modified example 2. FIG. 11 is a cross-sectional view of a louver film of embodiment 3, a partially enlarged cross-sectional view of a first member, and a partially enlarged cross-sectional view of a second member. FIG. 12 is a cross-sectional view of louver films of modified examples 3 and 4.

[0030] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0031] (Embodiment 1) Fig. 1 is a perspective view schematically illustrating the configuration of a louver film 1 of embodiment 1, as viewed from the edge side. As shown in Fig. 1, the louver film 1 includes an optical functional layer 2. The optical functional layer 2 includes a plurality of louvers 3 and a plurality of light-transmitting portions 4 arranged alternately in a constant arrangement direction X. The louvers 3 and the light-transmitting portions 4 each extend linearly in the Y direction, which is perpendicular to the arrangement direction X. The optical functional layer 2 is parallel to the XY plane and has a constant thickness in the Z direction, which is perpendicular to the XY plane. In this specification, the "film" in "louver film" includes what is generally called a "sheet," which is distinguished from "film" based on its thickness. It also includes both flexible and rigid films.

[0032] The louver film 1 includes a first light-transmitting layer 5 overlapping one side of the optical functional layer 2 in the thickness direction (the Z1 direction shown in FIG. 1 ), and a second light-transmitting layer 6 overlapping the other side of the optical functional layer 2 in the thickness direction (the Z2 direction shown in FIG. 1 ). In the example shown in FIG. 1 , the first light-transmitting layer 5 and the second light-transmitting layer 6 each consist of multiple layers. The first light-transmitting layer 5 includes a first base layer 51 formed integrally with a portion of the light-transmitting section 4, and a first substrate layer 52 bonded to the first base layer 51. The second light-transmitting layer 6 includes a second base layer 61 formed integrally with a portion of the light-transmitting section 4, and a second substrate layer 62 bonded to the second base layer 61.

[0033] The light-transmitting portion 4, the first base layer 51, and the second base layer 61 are made of light-transmitting materials with the same refractive index. In this embodiment, the light-transmitting portion 4, the first base layer 51, and the second base layer 61 are made of the same material. More specifically, the light-transmitting portion 4, the first base layer 51, and the second base layer 61 are made of UV-curable resin. The thickness T of the optical function layer 2 will be described later. The thickness t1 of the first base layer 51 and the thickness t2 of the second base layer 61 will be described later.

[0034] The first substrate layer 52 and the second substrate layer 62 are made of a light-transmitting resin such as PET (polyethylene terephthalate), polycarbonate, or PMMA (polymethyl methacrylate). The first substrate layer 52 and the second substrate layer 62 may be made of a resin other than these. The thickness T1 of the first substrate layer 52 and the thickness T2 of the second substrate layer 62 are preferably 38 μm to 250 μm when PET is used, and are preferably 100 μm to 500 μm when polycarbonate is used.

[0035] The louvers 3 have different optical properties from the light-transmitting portions 4. In this embodiment, the louvers 3 are made of a light-absorbing material, and the optical function layer 2 changes its light transmission state depending on the direction of incidence. In this embodiment, the louvers 3 are manufactured by curing a UV-curable molding material. More specifically, a molding material is used in which UV-curable ink with adhesive or cohesive functions is colored with a dye or pigment to give it light-absorbing functions. The dye or pigment used for coloring contains, for example, fine particles of carbon, iron, titanium, chromium, aluminum, etc.

[0036] Using the manufacturing method described below, the louver film 1 can be manufactured in a planar size that can be attached to large screens, monitors, windows, etc. For example, a planar size of 120 inches (diagonal dimension 3048 mm) can be manufactured. Note that while the perspective view shown schematically in FIG. 1 shows a small planar size of the louver film 1, the actual planar size can be increased as described above.

[0037] FIG. 2 is an explanatory diagram of a usage state of the louver film 1. FIG. 2(a) shows a state in which the louver film 1 is bonded via an adhesive layer 9 to a display surface 8 that emits image light in a display device 7 (e.g., a liquid crystal panel of a mobile terminal) that displays images, etc. Note that in FIG. 2(a), the thicknesses of the louver film 1 and the adhesive layer 9 are exaggerated to make the structure easier to understand. The adhesive layer 9 is preferably made of a transparent material that does not impair the visibility or optical properties of the display surface 8. For example, a silicone-based PSA (Pressure-Sensitive Adhesive), an acrylic-based PSA, or the like can be used as the adhesive layer 9.

[0038] The louver film 1 may consist only of the first light-transmitting layer 5, optical functional layer 2, and second light-transmitting layer 6 shown in FIG. 1 , but it is preferable to handle the louver film 1 as a product in which an adhesive layer 9 is laminated on the Z1-side surface of the first light-transmitting layer 5 or the Z2-side surface of the second light-transmitting layer 6, and a release film (not shown) is laminated on the surface of the adhesive layer 9. The release film may be, for example, a PET film with a thickness of about 50 μm. Furthermore, other functional layers or protective layers may be laminated on the surface opposite to the adhesive layer 9.

[0039] 2(b) and 2(c) are partial enlarged views of region A in FIG. 2(a). As shown in FIG. 2(b), when a user views the display surface 8 from an angle within the viewing angle range R, which is determined by the shape, arrangement pitch, and tilt angle of the louvers 3, light passes through the gaps in the louvers 3 and reaches the user. Therefore, the user can see the image displayed on the display surface 8. In this case, when the user views the display surface 8 from a direction that matches the tilt angle of the louvers 3, the aperture ratio, which indicates the ratio of the area through which light passes, is the largest, and the amount of light transmitted is the greatest. Therefore, the display surface 8 appears the brightest. On the other hand, as shown in FIG. 2(c), when a user views the display surface 8 from an angle outside the viewing angle range R, light cannot pass through the gaps in the louvers 3 and is entirely absorbed by the louvers 3. Therefore, the user cannot see the image displayed on the display surface 8. In other words, in the usage situation shown in FIG. 2, the louver film 1 functions as a viewing angle control film or an anti-peeping film.

[0040] The louver film 1 is a light control film whose transmittance of incident light changes depending on the angle of incidence, and can be used in a variety of applications. For example, in addition to the above-mentioned viewing angle control film or anti-peeping film, it can also be used as an anti-glare film. For example, it can be attached to windows of buildings, windows of vehicles such as cars, sunglasses, goggles, etc. Alternatively, it can be attached to a screen that projects image light. It can also be used as an optical filter.

[0041] (Method of Manufacturing Louver Film) Fig. 3 is a flowchart of a method of manufacturing the louver film 1. Figs. 4, 5, and 6 are explanatory diagrams of a method of manufacturing the louver film 1. As shown in Fig. 3, the method of manufacturing the louver film 1 includes a first step S1, a second step S2, and a third step S3. Fig. 4 is an explanatory diagram of the first step S1. Fig. 5 is an explanatory diagram of the second step S2. Fig. 6 is an explanatory diagram of the third step S3.

[0042] (First Step) In the first step S1, the first member 10 and the second member 20 are manufactured using a light-transmitting resin material. In this embodiment, the louver film 1 is manufactured by bonding the film-like first member 10 and the film-like second member 20 together. Since the manufacturing methods for the first member 10 and the second member 20 are the same, FIG. 4 shows the manufacturing method for the first member 10 as a representative example.

[0043] When manufacturing the first member 10 and the second member 20, their shapes are set as follows. As shown in FIGS. 4( c) and 5(a), the first member 10 includes a first light-transmitting layer 5 and a plurality of first convex portions 11 that protrude from the surface of the first light-transmitting layer 5 and are aligned in the X direction along the surface of the first light-transmitting layer 5. In this embodiment, the first light-transmitting layer 5 has a two-layer structure in which a first base layer 51 and a first substrate layer 52 are bonded together. The first convex portions 11 are formed integrally with the first base layer 51. The plurality of first convex portions 11 have the same shape, and are arranged at a uniform pitch D. Each of the plurality of first convex portions 11 extends linearly in a direction perpendicular to the plane of FIG. 4 (a direction perpendicular to the X direction and perpendicular to the Z direction).

[0044] As shown in FIG. 5A , the second member 20 includes a second light-transmitting layer 6 and a plurality of second convex portions 21 that protrude from the surface of the second light-transmitting layer 6 in the Z1 direction and are aligned in the X direction along the surface of the second base layer at the same arrangement pitch as the first convex portions 11. Similar to the first member 10, the second light-transmitting layer 6 has a two-layer structure in which a second base layer 61 and a second base layer 62 are bonded together. The second convex portions 21 are integrally formed with the second base layer 61. In the second member 20, the second convex portions 21 have the same shape and are aligned at a uniform pitch D. Each of the second convex portions 21 extends linearly in a direction perpendicular to the plane of the paper in FIG. 4 (a direction perpendicular to the X direction and perpendicular to the Z direction).

[0045] The first convex portion 11 is a first prism having a triangular cross section. The width of the base of the first prism is the same as the arrangement pitch of the first prisms (i.e., the uniform pitch D). Therefore, a plurality of first prisms are arranged in a sawtooth pattern on the surface of the first member 10. The first prism has a first surface 12 and a second surface 13 that intersect in a direction forming an apex angle θ1 at its vertex P1.

[0046] The second convex portion 21 is a second prism having a triangular cross section. The width of the base of the second prism is the same as the arrangement pitch of the second prisms (i.e., the uniform pitch D). Therefore, a plurality of second prisms are arranged in a sawtooth pattern on the surface of the second member 20. The second prism has a third surface 22 and a fourth surface 23 that intersect in a direction forming an apex angle θ2 at its vertex P2.

[0047] The second prism has the same base width as the first prism, but the protruding height H2 of the second prism is lower than the protruding height H1 of the first prism. Therefore, the apex angle θ2 of the second prism is larger than the apex angle θ1 of the first prism. It is suitable for the first and second prisms to have apex angles θ1 and θ2 greater than 10°. Increasing the apex angles θ1 and θ2 to greater than 10° avoids increasing the difficulty of manufacturing the prisms. Furthermore, there is little risk of deformation of the prism tips. Therefore, there is little risk of a decrease in the shape precision of the louver 3.

[0048] The protrusion height H1 of the first prism and the protrusion height H2 of the second prism are both suitably set to 1 μm or more and 500 μm or less. In this embodiment, the protrusion height H1 of the first prism and the thickness T of the optical function layer 2 (see FIG. 1) are the same. Therefore, the thickness T of the optical function layer 2 is 1 μm or more and 500 μm or less. Furthermore, the arrangement pitch of the first convex portions 11 and the arrangement pitch of the second convex portions 21 (i.e., dimension D) are suitably set to 5 μm or more and 500 μm or less. This makes it possible to form an optical function layer 2 that can be used for a variety of applications.

[0049] In the first step S1, the first member 10 and the second member 20 are manufactured by 2P molding. FIG. 4( a) is an explanatory diagram of a process of supplying uncured resin 72 to a first mold surface 70. FIG. 4( b) is an explanatory diagram of a process of curing the uncured resin 72 while applying pressure via a substrate film 73. FIG. 4( c) is an explanatory diagram of the first member 10 after being released from the mold. As shown in FIG. 4( a), the mold used to manufacture the first member 10 includes a first mold surface 70 having recesses 71 arranged at a constant pitch. The shape of the recesses 71 is an inverted shape of the first protrusions 11. The arrangement pitch of the recesses 71 is a uniform pitch D. First, as shown in FIG. 4( a), the uncured resin 72 is supplied to the first mold surface 70. For example, the uncured resin 72 is applied to the first mold surface 70. Next, as shown in FIG. 4( b), the uncured resin 72 is cured while applying pressure via a substrate film 73. The base film 73 is made of, for example, PET, polycarbonate, or PMMA. A UV-curable resin is used as the uncured resin 72. Therefore, UV light is irradiated onto the UV-transparent base film 73 to cure the uncured resin 72. Thereafter, as shown in FIG. 4( c), the first member 10 is released from the mold.

[0050] 4(c), the completed first member 10 is a composite member in which the first convex portions 11 are transferred onto the surface of the first base layer 51, which is made of cured UV-curable resin, and the first base layer 51 is joined to the substrate film 73. The substrate film 73 constitutes the first substrate layer 52. Similarly, the second member 20 can be manufactured using a mold having a second mold surface on which the inverted shape of the second convex portions 21, rather than the first convex portions 11, is provided.

[0051] In the first step S1, it is preferable to set the thickness t1 of the first base layer 51 and the thickness t2 of the second base layer 61 to 100 μm or less. By reducing the thicknesses t1 and t2 of the first base layer 51 and the second base layer 61, which do not affect the optical properties, it is possible to reduce the overall thickness of the louver film 1. In this embodiment, the thicknesses t1 and t2 are the same, but they may be different.

[0052] In the first step S1, the amount of uncured resin 72 supplied can be reduced so that the first base layer 51 is not formed. In this case, the first light-transmitting layer 5 is made of only the first base layer 52. The second member 20 can also have a similar configuration. However, providing the first base layer 51 and the second base layer 61 improves the appearance of the louver film 1.

[0053] (Second Step) FIG. 5 is an explanatory diagram of the second step S2. In the second step S2, as shown in the upper diagram of FIG. 5 , the first member 10 and the second member 20 are bonded together with the first convex portion 11 (first prism) and the second convex portion 21 (second prism) facing each other. At this time, a molding material 30 is supplied between the first convex portion 11 and the second convex portion 21 before bonding them together. For example, a molding material (UV-curable ink in this embodiment) is applied to the first convex portion 11 or the second convex portion 21. Then, as shown in the lower diagram of FIG. 5 , the tip of the second convex portion 21 is inserted into the valley between adjacent first convex portions 11. The first prism and the second prism have the same inclination angle R1 of the first surface 12 with respect to the first light-transmitting layer 5 and the same inclination angle R3 of the third surface 22 with respect to the second light-transmitting layer 6. Therefore, in the second step S2, the third surfaces 22 of the second convex portions 21 can be brought into contact with the first surfaces 12 of the respective first convex portions 11. The first convex portions 11 and the second convex portions 21, in which the first surfaces 12 and the third surfaces 22 are in close contact with each other, become the light-transmitting portions 4.

[0054] Meanwhile, the inclination angle R2 of the second surface 13 of the first prism relative to the first light-transmitting layer 5 and the inclination angle R4 of the fourth surface 23 relative to the second light-transmitting layer 6 are different from each other, and the second surface 13 and the fourth surface 23 are inclined in a direction forming an acute angle. Therefore, as shown in the lower diagram of Figure 5, when the apex P1 of the first prism abuts against the valley of the second prism, a wedge-shaped gap 40 is formed between the second surface 13 and the fourth surface 23. At the same time, the molding material 30 is filled into the gap 40. In this way, in the second step S2, a plurality of light-transmitting portions 4 arranged at equal pitches D are formed, and at the same time, gaps 40 filled with the molding material 30 are formed between adjacent light-transmitting portions 4.

[0055] (Third Step) Fig. 6 is an explanatory diagram of the third step S3. Subsequently, in the third step S3, the molding material 30 filled in each gap 40 is cured to form louvers 3 having a shape that matches the gaps 40 (in this embodiment, a wedge shape). Because the first member 10 and the second member 20 are light-transmitting, as shown in Fig. 5, UV light can be irradiated from the outside to cure the molding material 30 filled in the gaps 40. By curing the molding material 30, an optical function layer 2 is formed in which the louvers 3 and the light-transmitting portions 4 are alternately arranged in the X direction.

[0056] In the second step S2 and the third step S3, various materials having different optical properties from the resin constituting the light-transmitting portion 4 can be used as the molding material 30 for forming the louvers 3. For example, a light-reflective molding material may be used instead of a light-absorbing one. In this case, a louver film 1 having light-reflective louvers 3 can be manufactured. Alternatively, a molding material capable of forming light-transmitting louvers 3 having a refractive index different from that of the light-transmitting portion 4 can be used as the molding material 30 for forming the louvers 3. For example, the molding material 30 is selected so that light incident on the light-transmitting portion 4 can be totally reflected at the interface between the light-transmitting portion 4 and the louvers 3 due to the refractive index difference. More specifically, the molding material 30 is selected so that the refractive index difference between the light-transmitting portion 4 and the louvers 3 is 0.1 or more (the refractive index n3 of the louvers 3 is 0.1 lower than the refractive index n4 of the light-transmitting portion 4). This allows the formation of an optical function layer 2 that can control the direction of light by utilizing total reflection due to the refractive index difference.

[0057] Instead of UV-curable ink, the molding material 30 may be a colored OCR (optical clear resin) obtained by coloring a UV-curable OCR with a dye or pigment. Alternatively, as described above, when total reflection is achieved at the interface between the light-transmitting portion 4 and the louver 3 due to a refractive index difference, an optically transparent low-refractive-index UV-curable OCR having a refractive index lower than that of the resin constituting the light-transmitting portion 4 may be used. Alternatively, a thermosetting molding material may be used instead of a UV-curable molding material. For example, a thermosetting OCR may be used instead of a UV-curable OCR. In this case, a heating process may be performed instead of UV light irradiation in the third step S3. Alternatively, a two-component mixed curing molding material may be used. In this case, for example, in the second step S2, two components, such as a base agent and a curing agent, may be mixed and quickly applied to the first convex portion 11 or the second convex portion 21, and in the third step S3, the mixed liquid may be reacted and cured under predetermined reaction conditions.

[0058] (Effects) As described above, in this embodiment, the louver film 1 including the optical functional layer 2 in which the light-transmitting portions 4 and the light-absorbing louvers 3 are alternately arranged is manufactured by performing the first step S1, the second step S2, and the third step S3. In this manner, when the first member 10 and the second member 20 are bonded together, the louver 3 is formed by utilizing the gaps 40 formed between the first convex portions 11 and the second convex portions 21, thereby increasing the degree of freedom in the shape and inclination angle of the louvers 3. For example, it is possible to form gaps 40 with an undercut shape or gaps 40 with a large inclination angle relative to the thickness direction of the optical functional layer 2, without increasing the difficulty of manufacturing the first member 10 and the second member 20. Therefore, the degree of freedom in the shape and inclination of the louvers 3 can be increased while avoiding an increase in the difficulty of manufacturing.

[0059] Furthermore, with this manufacturing method, the shape precision of the louver 3 is approximately the same as that of the first convex portions 11 and the second convex portions 21. Therefore, the shape precision of the louver 3 can be improved compared to a manufacturing method in which a light-absorbing coating film is formed and then resin is filled on top of the coating film. Furthermore, it is easy to increase the size of the louver film 1. In addition, after the louver 3 is formed, the first light-transmitting layer 5 and the second light-transmitting layer 6 can be used as they are as protective layers that cover the optical function layer 2. Therefore, the step of separately providing a protective layer that covers the optical function layer 2 can be omitted.

[0060] In this embodiment, the plurality of first convex portions 11 have the same shape, and the plurality of second convex portions 21 also have the same shape, and further, the arrangement pitch of the first convex portions 11 and the second convex portions 21 is a uniform pitch D. This makes it possible to form an optical function layer 2 in which louvers 3 of the same shape are arranged at the uniform pitch D.

[0061] In this embodiment, the first convex portion 11 is a first prism having a triangular cross-sectional shape and including a first surface 12 and a second surface 13. The second convex portion 21 is a second prism having a triangular cross-sectional shape and including a third surface 22 and a fourth surface 23. The two prisms have the same inclination angle R1 of the first surface 12 relative to the first light-transmitting layer 5 and the same inclination angle R3 of the third surface 22 relative to the second light-transmitting layer 6. On the other hand, the inclination angle R2 of the second surface 13 relative to the first light-transmitting layer 5 and the inclination angle R4 of the fourth surface 23 relative to the second light-transmitting layer 6 are different. By setting the shape in this way, gaps 40 having a wedge-shaped cross-sectional shape are formed, thereby forming a louver 3 having a wedge-shaped cross-sectional shape.

[0062] In this embodiment, the cross-sectional shape of the louvers 3 is wedge-shaped, which provides a different dimming effect from that of louvers 3 with a constant thickness. For example, rather than a dimming effect in which the amount of light transmitted changes suddenly around a specific incident angle, the amount of light transmitted gradually changes as the incident angle changes, providing a dimming effect in which the light gradually becomes darker or brighter. Furthermore, compared to louvers 3 with a constant thickness, the outer periphery is longer and the volume is smaller, so UV light and the like can be transmitted more efficiently. This reduces the risk of uncured molding material 30 remaining in the gaps 40.

[0063] In the manufacturing method of this embodiment, the shape, inclination angle, thickness, etc. of the louvers 3 can be made to various angles and dimensions by appropriately setting the inclination angle and protrusion height of each face of the first prism and the second prism. Therefore, there is a high degree of freedom in the shape and inclination of the louvers 3. For example, the cross-sectional shape of the louvers 3 does not have to be wedge-shaped, and can be a plate-like shape with a constant thickness, or a rectangular or diamond-shaped shape, as will be described later. In addition, the arrangement pitch of the louvers 3 can also be changed appropriately.

[0064] Furthermore, at least some of the multiple first convex portions 11 can be made to have different shapes, and at least some of the multiple second convex portions 21 can be made to have different shapes. This makes it possible to form an optical function layer 2 that includes louvers 3 with different shapes or different inclination angles. It is also possible to form an optical function layer 2 in which the arrangement pitch of the multiple louvers 3 is uneven. According to the manufacturing method of this embodiment, the difficulty of manufacturing does not change even when louvers 3 with different shapes, inclination angles, or different arrangement pitches are included.

[0065] Furthermore, the shapes of the first convex portions 11 and the second convex portions 21 are not limited to triangular prism shapes in cross section. The first convex portions 11 and the second convex portions 21 may have any shape as long as a portion of the surface of the second convex portion 21 abuts a portion of the surface of the first convex portion 11 when the second convex portion 21 is inserted into the valley between adjacent first convex portions 11. The light-transmitting portion 4 can be formed by abutting the first convex portions 11 and the second convex portions 21 at their surfaces. For example, as described below, the cross-sectional shapes of the first convex portions 11 and the second convex portions 21 may be trapezoidal or other polygonal. Furthermore, the first convex portions 11 and the second convex portions 21 may have a shape that includes a curved surface.

[0066] (Change in manufacturing method of first member and second member) Figure 7 is an explanatory diagram of a louver film 1M manufactured using a first member 10M and a second member 20M manufactured by extrusion molding. The louver film 1M shown in Figure 7 comprises a first light-transmitting layer 5M, an optical function layer 2, and a second light-transmitting layer 6M. The first light-transmitting layer 5M is a single layer consisting of only a first base layer 51 formed integrally with a portion of the light-transmitting section 4. The second light-transmitting layer 6M is a single layer consisting of only a second base layer 61 formed integrally with a portion of the light-transmitting section 4.

[0067] The first member 10M and the second member 20M can be manufactured by extrusion molding. For example, extrusion molding can be performed using a mold member having grooves formed on the surface at a uniform pitch D, which are the inverse shape of the first convex portions 11 or the second convex portions 21. When a pressure roll is used as the mold member, a heated and melted resin material such as PC (polycarbonate), PMMA (polymethyl methacrylate), or MS (methyl methacrylate-styrene copolymer) is continuously extruded into a film. The extruded film is sandwiched between a pressure roll having grooves formed on its surface and a support roll facing the pressure roll, and the film passes between the rolls by rotating the pressure roll. This transfers the shape of the first convex portions 11 or the second convex portions 21 to the film surface.

[0068] In this manufacturing method, the first member 10M and the second member 20M are each formed from a single resin such as PC, PMMA, or MS. Therefore, in the second step S2, the first member 10M and the second member 20M, which are formed from a single resin, are bonded together. The completed louver film 1M is formed entirely from a single resin such as PC, PMMA, or MS, except for the louver 3 portion. Note that a protective layer or other functional layer may be bonded to each of the first base layer 51 and the second base layer 61 in a subsequent step after extrusion molding.

[0069] (Modification of the Shape and Arrangement of the Louvers) The shape and arrangement of the louvers 3 that can be manufactured by the manufacturing method of this embodiment are not limited to the shape and arrangement shown in Fig. 1. Various modified examples with different louver shapes and arrangements will be described below. Note that, for ease of explanation, in Figs. 8 to 11, the first light-transmitting layer 5 and the second light-transmitting layer 6 are not shown as being separated into a base layer and a substrate layer, but when 2P molding is used as the manufacturing method, a two-layer structure similar to that shown in Fig. 1 will be obtained.

[0070] (Variation 1) Figure 8 is a cross-sectional view of a louver film 1A of Variation 1. The louver film 1A includes an optical function layer 2A. The optical function layer 2A includes wedge-shaped louvers 31, 32, 33, 34, and 35 arranged in the X direction. The multiple louvers 31, 32, 33, 34, and 35 have different cross-sectional shapes and inclination angles relative to the light incident surface. More specifically, the inclination angle and length of the multiple louvers 31, 32, 33, 34, and 35 increase from one side of the arrangement direction (the X1 direction in Figure 8) to the other side (the X2 direction in Figure 8). Therefore, the light control effect of the louver film 1A changes depending on the incident position in the X direction.

[0071] The manufacturing method of the louvered film 1A is the same as that of embodiment 1, except for the shapes of the first member 10A and the second member 20A. The first member 10A has multiple first convex portions 111, 112, 113, 114, and 115, each having a different shape. The first convex portions 111, 112, 113, 114, and 115 have the same inclination angle of the slope in the X1 direction, and the inclination angle of the slope in the X2 direction increases toward the X2 direction. The second member 20A has multiple second convex portions 211, 212, 213, 214, and 215, each having a different shape. The second convex portions 211, 212, 213, 214, and 215 have the same inclination angle of the slope in the X2 direction, and the inclination angle of the slope in the X1 direction increases toward the X2 direction. As a result, in the second process S2, wedge-shaped gaps are formed whose inclination angle gradually increases toward the X2 direction.

[0072] The first member 10A and the second member 20A can be manufactured using, for example, a mold member in which grooves of different shapes are formed side by side in a certain direction.

[0073] (Embodiment 2) Figure 9 is a cross-sectional view of a louver film 1B of embodiment 2. The louver film 1B includes an optical function layer 2B in which louvers 3B and light-transmitting portions 4B are alternately arranged in the X direction. The multiple louvers 3B have the same shape and are arranged at an equal pitch D. The cross-sectional shape of each louver 3B is not wedge-shaped, but is a plate-like shape with a constant thickness. Each louver 3B is perpendicular to the optical function layer 2B and perpendicular to the light incidence plane. The thickness t of each louver 3B is suitably 3 µm or more. When a colored OCR is used, the required dimming function can be obtained by setting the thickness t to 3 µm.

[0074] Even when the louvers have a wedge-shaped cross section, as in embodiment 1 and the above-mentioned variant 1, if a colored OCR is used, it is appropriate to make the thickness of at least a portion of each louver 3 μm or more in order to ensure the dimming function.

[0075] The manufacturing method of the louvered film 1B is the same as that of embodiment 1, except for the shapes of the first member 10B and the second member 20B. The first member 10B has a plurality of first convex portions 11B protruding from the first light-transmitting layer 5. The first convex portions 11B are first prisms with a right-angled triangular cross-section. The first convex portions 11B (first prisms) have a first surface 12B and a second surface 13B. The second surface 13B is perpendicular to the first light-transmitting layer 5. Similarly, the second member 20B has a plurality of second convex portions 21B protruding from the second light-transmitting layer 6. The second convex portions 21B are second prisms with a right-angled triangular cross-section. The second convex portions 21B (second prisms) have a third surface 22B and a fourth surface 23B. The fourth surface 23B is perpendicular to the second light-transmitting layer 6.

[0076] The first convex portions 11B and the second convex portions 21B are similar in shape but different in size, and the inclination angle θ of the first surface 12B relative to the first light transmitting layer 5 is the same as the inclination angle θ of the third surface 22B relative to the second light transmitting layer 6. The first convex portions 11B and the second convex portions 21B are arranged at the same pitch, but the width W2 of the base of the second convex portions 21B is narrower than the width W1 of the base of the first convex portions 11B. Therefore, a fifth surface 24B is formed between adjacent second convex portions 21B and extends along the arrangement direction X of the second convex portions 21B. The fifth surface 24B constitutes the surface of the second light transmitting layer 6.

[0077] In embodiment 2, in the second step S2, when the second convex portion 21B is inserted into the valley between adjacent first convex portions 11B and the first surface 12B and the third surface 22B are brought into contact with each other, a gap 40B of a certain width t perpendicular to the first light transmitting layer 5 and the second light transmitting layer 6 is formed between the second surface 13B and the fourth surface 23B.

[0078] In the second embodiment, the louvers 3B can be formed with a uniform thickness, thereby achieving a dimming effect in which the amount of light transmitted changes rapidly around a specific angle of incidence. Furthermore, the louvers 3B can be formed perpendicular to the first light transmitting layer 5 and the second light transmitting layer 6, thereby forming an optical function layer 2B having louvers 3 that are completely perpendicular to the light incident surface.

[0079] (Variation 2) Figure 10 is a cross-sectional view of a louver film 1C of Variation 2. The louver film 1C includes an optical function layer 2C. The optical function layer 2C includes plate-shaped louvers 31C, 32C, 33C, 34C, and 35C arranged in the X direction. As in Variation 1, the inclination angle and length of the multiple louvers 31C, 32C, 33C, 34C, and 35C increase from one side of the arrangement direction (the X1 direction in Figure 10) to the other side (the X2 direction in Figure 10). Therefore, the light control effect of the louver film 1C changes depending on the incident position in the X direction.

[0080] The manufacturing method of the louvered film 1C is the same as that of Embodiments 1 and 2, except for the shapes of the first member 10C and the second member 20C. The first member 10C includes multiple first convex portions 111C, 112C, 113C, 114C, and 115C, each having a different shape. The first convex portions 111C, 112C, 113C, 114C, and 115C have the same inclination angle of the slope in the X2 direction, and the inclination angle of the slope in the X1 direction increases toward the X2 direction. The second member 20C includes multiple second convex portions 211C, 212C, 213C, 214C, and 215C, each having a different shape. The second convex portions 211C, 212C, 213C, 214C, and 215C have the same inclination angle of the slope in the X1 direction, and the inclination angle of the slope in the X2 direction increases toward the X2 direction. As a result, in the second step S2, a gap of a constant width is formed whose inclination angle gradually increases in the X2 direction.

[0081] As in the second modification, the first member 10C and the second member 20C can be manufactured using a mold member in which grooves of different shapes are formed side by side in a fixed direction.

[0082] (Embodiment 3) Figure 11(a) is a cross-sectional view of a louver film 1D of embodiment 3. The louver film 1D includes an optical function layer 2D in which louvers 3D and light-transmitting portions 4D are alternately arranged in the X direction. The multiple louvers 3D have the same shape and are arranged at an equal pitch D. The cross-sectional shape of each louver 3D is rectangular. The length (thickness) t of the short side of each louver 3D is preferably 3 µm or more. As already explained, this dimension is a dimension for providing the necessary dimming function to the louver 3D made of colored OCR.

[0083] Figure 11(b) is a partially enlarged cross-sectional view of the first member 10D. Figure 11(c) is a partially enlarged cross-sectional view of the second member 20D. The manufacturing method of the louvered film 1D is the same as that of Embodiments 1 and 2, except for the shapes of the first member 10D and the second member 20D. The first member 10D includes a first light-transmitting layer 5 and a plurality of first convex portions 11D protruding from the first light-transmitting layer 5. The first convex portions 11D are first prisms having a trapezoidal cross-sectional shape. The first convex portions 11 (first prisms) include a first upper base surface 15D parallel to the first light-transmitting layer 5, a first inclined surface 12D extending from one end of the first upper base surface 15D to the first light-transmitting layer 5, and a second inclined surface 13D extending from the other end of the first upper base surface 15D to the first light-transmitting layer 5.

[0084] In the first convex portion 11 (first prism), the inclination angle of the first inclined surface 12D with respect to the first light transmitting layer 5 is different from the inclination angle of the second inclined surface 13D with respect to the first light transmitting layer 5. Therefore, the length L1 of the first inclined surface 12D is different from the length L2 of the second inclined surface 13D. Regarding the shape of the first convex portion 11D, it is suitable that the length L2 of the second inclined surface 13D is between 2 and 5, where L1 of the first inclined surface 12D is 1. Furthermore, it is suitable that the angle θd between the first inclined surface 12D and the second inclined surface 13D is 90° (a right angle).

[0085] The second member 20D has the same shape as the first member 10D and is used in the reverse orientation. The second member 20D includes a second light-transmitting layer 6 having the same thickness as the first light-transmitting layer 5 and multiple second convex portions 21D protruding from the second light-transmitting layer 6. The second convex portions 21D are second prisms with a trapezoidal cross-sectional shape. The second convex portions 21D (second prisms) have the same shape as the first convex portion 11. That is, the second convex portions 21D include a second upper base surface 25D having the same length as the first upper base surface 15D, a third inclined surface 22D connected to one end of the second upper base surface 25D, and a fourth inclined surface 23D connected to the other end of the second upper base surface 25D. The length L3 of the third inclined surface 22D is the same as the length L1 of the first inclined surface 12D of the first member 10D. The length L4 of the fourth inclined surface 23D is the same as the length L2 of the second inclined surface 13D of the first member 10D. The angle between the third inclined surface 22D and the fourth inclined surface 23D is the same as the angle θd between the first inclined surface 12D and the second inclined surface 13D, which is 90° (a right angle).

[0086] In the third embodiment, in the second step S2, the second upper bottom surface 25D of the second convex portion 21D is brought into contact with the first upper bottom surface 15D of each of the plurality of first convex portions 11D. This allows the first convex portions 11D and the second convex portions 21D to form the light-transmitting portions 4D, and simultaneously allows gaps 40D with a rectangular cross-sectional shape to be formed between adjacent light-transmitting portions 4D, surrounded by the opposing first inclined surface 12D and third inclined surface 22D, and the opposing second inclined surface 13D and fourth inclined surface 23D. This allows the louver 3D to have a rectangular cross-sectional shape and a constant thickness all the way to the ends, resulting in a rapid change in the amount of light transmission around a specific incident angle, achieving a dimming effect similar to switching the light incidence on and off.

[0087] In the third embodiment, the cross-sectional shapes of the first convex portion 11D and the second convex portion 21D are trapezoidal, so that the width of the light-transmitting portion 4D between adjacent louvers 3D can be increased. The lengths of the first upper base surface 15D and the second upper base surface 25D are suitably set to be 1 μm or more and 100 μm or less. This allows the formation of light-transmitting portions 4D of various widths, making it possible to form an optical function layer 2D that can be used for a variety of purposes.

[0088] In the third embodiment, the first convex portion 11D and the second convex portion 21D have the same shape, and the first member 10D and the second member 20D are members of the same shape. This reduces the number of types of members to be manufactured, thereby reducing management costs. Furthermore, this reduces the number of types of molds used in manufacturing, thereby reducing manufacturing costs.

[0089] In the third embodiment, the shapes of the first convex portions 11D and the second convex portions 21D are set so that the dimensional ratio of the short side to the long side of the louver 3D (the dimensional ratio L1:L2 between the first inclined surface 12D and the second inclined surface 13D, and the dimensional ratio L3:L4 between the third inclined surface 22D and the fourth inclined surface 23D) is in the range of 1:2 to 5. By setting the dimensional ratio of the short side to the long side to this level, the thickness of the louver 3D can be ensured and the change in the amount of light transmission during dimming can be increased.

[0090] (Modifications 3 and 4) Fig. 12(a) is a cross-sectional view of a louver film 1E of Modification 3. Fig. 12(b) is a cross-sectional view of a louver film 1F of Modification 4. In embodiment 3, the cross-sectional shape of the louver 3D is rectangular, and all corners are at 90°, but this angle is not limited to 90° and may be in the range of 60° to 120°.

[0091] 12(a), in the louver film 1E, the angle θe between the first inclined surface 12E and the second inclined surface 13E of the first convex portion 11E and the angle θe between the third inclined surface 22E and the fourth inclined surface 23E of the second convex portion 21E are acute angles of 60° or more. In this case, the other two corners are obtuse angles of 120° or less. Therefore, the cross-sectional shape of the louver 3E is rhombic.

[0092] 12(b), in the louver film 1F, the angle θf between the first inclined surface 12F and the second inclined surface 13F of the first convex portion 11F and the angle θf between the third inclined surface 22F and the fourth inclined surface 23F of the second convex portion 21F are obtuse angles of 120° or less. In this case, the other two corners are acute angles of 60° or more. Therefore, in this case as well, the cross-sectional shape of the louver 3F is a rhombus.

[0093] The corner angles of the louvers 3E and 3F are close to 90° (60° to 120°). Therefore, even if the louvers are rhombic, an optical function layer can be formed that can rapidly change the amount of light transmitted at a specific incident angle.

[0094] (Other Embodiments) In the above embodiments and their modifications, the first convex portions and the second convex portions extend linearly in a direction perpendicular to the arrangement direction, but the planar shapes of the first convex portions and the second convex portions may be circular or curved rather than linear. This makes it possible to form an optical function layer in which the louvers have a circular or curved planar shape. For example, it is possible to form an optical function layer in which circular louvers are arranged concentrically.

Claims

1. A method for manufacturing a louver film having an optical function layer in which light-transmitting portions and louvers are arranged alternately, comprising the steps of: a first step of manufacturing a first member having a first light-transmitting layer and a plurality of first convex portions protruding from the first light-transmitting layer; and a second member having a second light-transmitting layer and a plurality of second convex portions protruding from the second light-transmitting layer and arranged at the same arrangement pitch as the first convex portions; a second step of supplying a molding material between the first member and the second member and bonding them together, thereby abutting the second convex portions against each of the plurality of first convex portions, thereby forming a plurality of the light-transmitting portions arranged at the arrangement pitch and forming gaps filled with the molding material between adjacent light-transmitting portions; and a third step of hardening the molding material to form the louvers between the first light-transmitting layer and the second light-transmitting layer, the louvers having a shape that matches the gaps.

2. The method for manufacturing a louver film according to claim 1, wherein the arrangement pitch is 5 μm or more and 500 μm or less.

3. The method for manufacturing a louver film described in claim 1, characterized in that in the first step, a UV-curable resin is supplied to a first mold surface on which the inverted shapes of the first convex portions are arranged, and is cured while applying pressure via a first substrate layer, and then the resin is released from the first mold surface, thereby forming the first light-transmitting layer of a two-layer structure in which the first substrate layer is bonded to a first base layer formed integrally with the first convex portions; and a UV-curable resin is supplied to a second mold surface on which the inverted shapes of the second convex portions are arranged, and is cured while applying pressure via a second substrate layer, and then the resin is released from the second mold surface, thereby forming the second light-transmitting layer of a two-layer structure in which the second substrate layer is bonded to a second base layer formed integrally with the second convex portions.

4. The method for manufacturing a louver film according to claim 3, wherein the thickness of the first base layer and the thickness of the second base layer are both 100 μm or less.

5. The method for manufacturing a louver film according to claim 1, wherein the molding material is a UV-curable ink having an adhesive or pressure-sensitive adhesive function.

6. The method for manufacturing a louvered film according to claim 1, wherein the thickness of at least a portion of the louver is 3 μm or more.

7. The method for manufacturing a louvered film described in claim 1, characterized in that: the first convex portion is a first prism having a triangular cross-sectional shape with a first surface and a second surface intersecting the first surface; the second convex portion is a second prism having a triangular cross-sectional shape with a third surface and a fourth surface intersecting the third surface; the inclination angle of the first surface with respect to the first light-transmitting layer is the same as the inclination angle of the third surface with respect to the second light-transmitting layer; and in the second step, the first surface and the third surface are abutted together to form the gap between the second surface and the fourth surface.

8. A method for manufacturing a louver film as described in claim 7, characterized in that the inclination angle of the second surface relative to the first light-transmitting layer is different from the inclination angle of the fourth surface relative to the second light-transmitting layer, and in the second step, the gap is formed to have a wedge-shaped cross-sectional shape surrounded by the second surface and the fourth surface.

9. A method for manufacturing a louver film as described in claim 7, characterized in that the second surface is perpendicular to the first light-transmitting layer and the fourth surface is perpendicular to the second light-transmitting layer, and in the second step, a gap of a certain width perpendicular to the first light-transmitting layer and the second light-transmitting layer is formed between the second surface and the fourth surface.

10. A method for manufacturing a louver film according to any one of claims 7 to 9, characterized in that the apex angle of the first prism and the apex angle of the second prism are both greater than 10°.

11. The method for manufacturing a louvered film described in claim 1, characterized in that the first convex portion is a first prism having a trapezoidal cross-sectional shape with a first upper base surface, a first inclined surface connected to one end of the first upper base surface, and a second inclined surface connected to the other end of the first upper base surface; the second convex portion is a second prism having a trapezoidal cross-sectional shape with a second upper base surface of the same length as the first upper base surface, a third inclined surface connected to one end of the second upper base surface, and a fourth inclined surface connected to the other end of the second upper base surface; and in the second step, the second upper base surface of the second prism is abutted against the first upper base surfaces of each of the plurality of first prisms, thereby forming the gap surrounded by the opposing first and third inclined surfaces, and the opposing second and fourth inclined surfaces.

12. The method for manufacturing a louver film according to claim 11, wherein the first prism and the second prism have the same shape.

13. A method for manufacturing a louvered film as described in claim 11, characterized in that the angle between the first inclined surface and the second inclined surface, and the angle between the third inclined surface and the fourth inclined surface are both greater than or equal to 60° and less than or equal to 120°.

14. A method for manufacturing a louvered film as described in claim 11, characterized in that the angle between the first inclined surface and the second inclined surface, and the angle between the third inclined surface and the fourth inclined surface are all 90°, and the length of the second inclined surface when the length of the first inclined surface is 1, and the length of the fourth inclined surface when the length of the third inclined surface is 1, are 2 or more and 5 or less.

15. The method for manufacturing a louver film according to claim 11, wherein the length of the first upper base surface and the length of the second upper base surface are both 1 μm or more and 100 μm or less.

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