JP2012073372A - Optical sheet, surface light source device, display device, and method for manufacturing optical sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical sheet hardly generating peeling of a mat layer.SOLUTION: An optical sheet 10 includes: a base material layer 15; and a mat layer 20 including diffusion particles 21 and binder resin 22 and provided on one side of the base material layer 15. The mat layer 20 includes: an outside surface 20a constituting a surface 10a on one side of the optical sheet 10; an inside surface 20b facing the base material layer 15; and an end face 20c between the inside surface 20b and the outside surface 20a. The end face 20c is located outwardly along a direction orthogonal to a normal direction nd of the optical sheet 10 in an inside end part 20cb crossing the inside surface 20b rather than an outside end part 20ca crossing the outside surface 20a in a cross section along the normal direction nd.

Description

  The present invention relates to an optical sheet having a mat layer containing diffusing particles and a binder resin, and more particularly to an optical sheet in which the mat layer is hardly peeled off, and a surface light source device and a display device including the optical sheet.

  The present invention also relates to a method for manufacturing an optical sheet having a matte layer containing diffusing particles and a binder resin, and more particularly to a method for manufacturing an optical sheet that can effectively prevent the occurrence of defects.

  Hitherto, optical sheets having a matting layer containing diffusing particles (meaning light diffusing particles, hereinafter also simply referred to as diffusing particles) and a binder resin have been widely used in various industrial fields (for example, Patent Document 1). As an example, the optical sheet can be used as a sheet that is bonded to the display surface of a display device and exhibits an antiglare function. As another example, it can be used by being incorporated in a surface light source device that emits light in a planar shape. This surface light source device can be used, for example, as a backlight that illuminates a liquid crystal display panel from the back side.

  An optical sheet having such a mat layer is first formed as a web-like (band-like) sheet material, and is cut out from the sheet material to a desired size. According to such a method, it is possible to reduce the production cost of the optical sheet as compared to the production of a sheet-like optical sheet having a desired size.

JP 2000-338310 A

  By the way, when an optical sheet is cut out (cut out) from a web-like sheet material using a tool such as an end mill, cutting elements or shavings (chips) are generated. When the facet or shavings adhere to the optical sheet, the traveling direction of light incident on the optical sheet is changed by the facet or shavings. For this reason, the optical sheet cannot exhibit the expected optical function.

  In addition, the optical sheets cut out from the sheet material are usually handled such as being conveyed in a stacked state. At this time, the surface of the optical sheet may be damaged by a facet or shavings interposed between the optical sheets. Furthermore, a cutting beam may be formed on the optical sheet cut out from the sheet material, and the cutting beam of one optical sheet may damage the other optical sheet. When the surface of the optical sheet is scratched, the traveling direction of light incident on the optical sheet is changed by the scratch. Accordingly, also in this case, the optical sheet cannot exhibit the expected optical function.

  When cutting (cutting out) an optical sheet from a web-like sheet material using a tool such as an end mill, the above-described problems occur. In order to avoid such problems, it has been studied to extract an optical sheet from a web-like sheet material by punching. However, when the optical sheet is taken out from the sheet material by punching, it has been found that, although cutting and scraping are not generated, problems such as foreign matter adhesion and scratches similar to the case of cutting out the optical sheet may occur.

  The present invention has been made in consideration of such points, and an object thereof is to provide a method of manufacturing an optical sheet that can effectively prevent the occurrence of defects.

  In addition, while the present inventor has earnestly studied the improvement of the manufacturing method of the optical sheet, the inventors have invented an optical sheet in which the mat layer is hardly peeled off. That is, an object of the present invention is to provide an optical sheet in which the mat layer is hardly peeled off, and a surface light source device and a display device including the optical sheet.

The first optical sheet according to the present invention is:
A base material layer;
An optical sheet comprising diffusing particles and a binder resin, and a mat layer provided on one side of the base material layer,
The mat layer includes an outer surface forming a surface on one side of the optical sheet, an inner surface opposite to the outer surface and facing the base material layer, the inner surface, and the outer surface. An end face between and
In the cross section along the normal direction of the optical sheet, the end surface is outward in the direction orthogonal to the normal direction at the inner end intersecting with the inner surface rather than the outer end intersecting with the outer surface. Located in.

  In the first optical sheet according to the present invention, an outer contour of the end surface in a cross section along the normal line direction of the optical sheet is a direction orthogonal to the normal line direction from the outer end part toward the inner end part. However, it may gradually shift outward.

  Further, in the first optical sheet according to the present invention, the outer contour of the outer surface in the cross section along the normal direction of the optical sheet is free of the diffusing particles in the end region in the vicinity of the end surface. In the region, as the end surface approaches the end surface along a direction perpendicular to the normal direction, the end surface may gradually shift toward the base material layer.

The second optical sheet according to the present invention is:
A base material layer;
An optical sheet comprising diffusing particles and a binder resin, and a mat layer provided on one side of the base material layer,
The mat layer includes an outer surface forming a surface on one side of the optical sheet, an inner surface opposite to the outer surface and facing the base material layer, the inner surface, and the outer surface. An end face between and
The outer contour of the outer surface in the cross section along the normal direction of the optical sheet is perpendicular to the normal direction to the end surface in the region where the diffusion particles do not exist in the end region near the end surface. As it approaches along the direction of the movement, it gradually shifts toward the base material layer in the normal direction.

The first or second optical sheet according to the present invention further comprises an optical element layer provided on the other side of the base material layer,
The optical element layer is
A plurality of unit optical elements arranged in one direction, each extending linearly in a direction intersecting the one direction; and
A plurality of unit optical elements arranged two-dimensionally;
You may make it have at least one of these.

  The surface light source device according to the present invention includes any one of the first and second optical sheets according to the present invention described above.

  The display device according to the present invention includes the above-described surface light source device according to the present invention.

  The display device according to the present invention includes any one of the first and second optical sheets according to the present invention described above.

  According to the first optical sheet manufacturing method of the present invention, a punching blade is inserted from a surface of one side into a sheet material having a surface of one side formed by a mat layer containing diffusing particles and a binder resin. And the process of obtaining the optical sheet which consists of a punched sheet material by punching the said sheet material is provided.

  In the first method for producing an optical sheet according to the present invention, the pencil hardness of the surface on the one side measured in accordance with JIS K5600-5-4 (1999) is 3H or less. Also good.

  In the second optical sheet manufacturing method according to the present invention, the pencil hardness measured according to JIS K5600-5-4 (1999), which is formed by a mat layer containing diffusing particles and a binder resin, is B or less. The sheet material punched by inserting a punching blade from the surface on the other side opposite to the one side and punching the sheet material with respect to the sheet material having the surface on one side which is The process of obtaining the optical sheet which consists of these is provided.

  In the first or second optical sheet manufacturing method according to the present invention, the pencil hardness of the surface on the one side measured in accordance with JIS K5600-5-4 (1999) is 3B or more. You may do it.

In the first or second method for producing an optical sheet according to the present invention, the punched sheet material further includes an optical element layer that forms a surface on the other side that is opposite to the one side,
The optical element layer is
A plurality of unit optical elements arranged in one direction, each extending linearly in a direction intersecting the one direction; and
A plurality of unit optical elements arranged two-dimensionally;
You may make it have at least one of these.

  According to the optical sheet of the present invention, the mat layer can be hardly peeled off. In addition, according to the method for manufacturing an optical sheet of the present invention, it is possible to manufacture an optical sheet while effectively preventing the occurrence of defects such as adhesion of foreign matter and scratches.

FIG. 1 is a perspective view showing an example of an optical sheet for explaining an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is a diagram for explaining an embodiment of the present invention, and is a diagram for explaining an example of a method for producing a sheet material. FIG. 4 is a diagram for explaining an embodiment of the present invention, and is a diagram for explaining an example of a method for producing a sheet material. FIG. 5 is a diagram for explaining an embodiment of the present invention, and is a schematic diagram showing an example of a method for manufacturing an optical sheet from a sheet material manufactured by the manufacturing method of FIGS. 4 and 5. . FIG. 6 is a cross-sectional view showing an example of an optical sheet that can be manufactured using the manufacturing method of FIG. FIG. 7 is an enlarged cross-sectional view of a portion surrounded by a dotted line in FIG. FIG. 8 corresponds to FIG. 1 and is a perspective view showing a modification of the optical sheet.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual ones.

  1-7 is a figure for demonstrating one Embodiment by this invention. Among these, FIG. 3 to FIG. 5 are diagrams for explaining an example of the manufacturing method of the optical sheet, and FIG. 1 and FIG. 2 show the optical sheet to be manufactured by the manufacturing method of FIG. FIG. 6 and 7 are enlarged cross-sectional views showing useful configurations of the optical sheet that can also be manufactured by the manufacturing method of FIGS. First, with reference to FIG. 1 and FIG. 2, the optical sheet made into the preparation by the following description is demonstrated, and the manufacturing method of an optical sheet is demonstrated after that.

  The optical sheet 10 shown in FIGS. 1 and 2 has a base material layer 15 and a mat layer 20 provided on one side of the base material layer 15. The base material layer 15 is formed from a resin film such as polyethylene terephthalate and functions as a layer that supports the mat layer 20.

  The mat layer 20 includes diffusion particles 21 and a binder resin 22. The diffusing particles 21 of the mat layer 20 are variously known such as particles made of an organic polymer such as an acrylic resin or a styrene resin, particles made of a metal compound such as alumina or silica, and particles having a porous physical property containing gas. The particles can be used. Further, the diffusing particles 21 do not have to be spherical as in the example shown in FIG. 2, and can have various shapes such as a spheroid shape and a polyhedral shape. In addition, as the resin binder 22, a resin material such as an acrylic resin, a polyester resin, or a urethane resin is used as a resin material system, and as a cured form, a thermosetting type or an ionizing radiation curable type (of these cured forms). The resin is also referred to as thermosetting resin or ionizing radiation curable resin), or various known resin materials having a cured form such as a solvent dry curable type and a heat-melt-cooled solidified type made of a thermoplastic resin are used. obtain.

  The mat layer 20 includes an outer surface 20a that forms a surface on one side of the optical sheet 10, an inner surface 20b that is opposite to the outer surface 20a and faces the base material layer 15, an inner surface 20b, and an outer surface 20b. And an end face 20c between the side face 20a. As shown well in FIG. 2, the outer surface 20 a of the mat layer 20 is configured as an uneven surface in which protrusions are formed corresponding to the positions where the diffusion particles 21 exist. That is, the surface 10a on one side of the optical sheet 10 formed by the outer surface 20a of the mat layer 20 is formed as an uneven surface, and diffuses light incident on the optical sheet 10 and light transmitted through the optical sheet 10. It has a light diffusion function.

  Such an optical sheet 10 can be used as an antiglare film, for example, because the surface 10a on one side formed of an uneven surface exhibits an antiglare function as a so-called mat surface. When used as an antiglare film, the optical sheet 10 is bonded to the display surface of the display device 10 and can prevent reflection on the display surface due to regular reflection of external light. In addition, the optical sheet 10 is used for a surface light source device capable of emitting light in a planar shape for the purpose of causing the surface light source device to exhibit desired optical characteristics such as a wide diffusion angle of emitted light and invisible light source images. It can be used even if incorporated.

  In particular, the optical sheet 10 shown in FIGS. 1 and 2 further includes an optical element layer 30 that can exert a predetermined optical action on the transmitted light on the other side of the base material layer 15 ( The upper surface in FIGS. 1 and 2 can be suitably used for a surface light source device that functions as a backlight for illuminating a liquid crystal display panel (LCD panel) from the back side.

  As shown in FIGS. 1 and 2, the optical element layer 30 forms a surface 10 b on the other side of the optical sheet 10 that is opposite to the surface 10 a on one side of the base material layer 15. The optical element layer 30 includes a sheet-like land portion 31 formed on the base material layer 15 and a large number of unit optical elements 35 arranged on the land portion 31. The land portion 31 is formed due to a manufacturing method to be described later, and is integrally formed of the same resin material as that of the unit optical element 35. The thickness of the land portion 31 is usually about 1 to 10 μm. It is also possible to adopt a configuration in which the land portion 31 is not provided (the land portion has a thickness of 0).

  The unit optical elements 35 are arranged along an arrangement direction parallel to the sheet surface of the optical sheet 10. Each unit optical element 35 extends linearly in a direction intersecting with the arrangement direction. In particular, in the illustrated example, each unit optical element 35 extends linearly along a direction orthogonal to the arrangement direction. Further, each unit optical element 35 is formed in a column shape and has the same cross-sectional shape along the longitudinal direction. In addition, the plurality of unit optical elements 35 are configured identically to each other and are arranged on the land portion 31 with no gap. In such a configuration, the surface 10 b on the other side of the optical sheet 10 is formed by the light exit surface of the unit optical element 35.

  As shown in FIG. 2, in a cross section (also referred to as a main cutting plane) parallel to both the arrangement direction of the unit optical elements 35 (the left-right direction in the figure) and the normal direction nd of the optical sheet 10. Each unit optical element 35 has a triangular shape with one side positioned on the land portion 31. In the cross section shown in FIG. 2, the main cut surface shape of the unit optical element 35 is a right-angled isosceles triangle shape and has symmetry about the normal direction nd. When such an optical sheet 30 is incorporated in a surface light source device, it effectively collects light emitted from a point-like or linear light source and effectively improves the luminance in the normal direction nd. Can be made.

  In the present specification, terms such as “sheet”, “film”, and “plate” are not distinguished from each other only based on the difference in names. Therefore, for example, “sheet” is a concept including parts, members, and the like that can also be called films and plates.

  Further, in this specification, the “sheet surface (film surface, layer surface)” is a plane of a target sheet-like component or member when the target sheet-like member is viewed as a whole and as a whole. A surface that matches the direction. In the present embodiment, the sheet surface of the optical sheet 10 is parallel to the layer surface of the base material layer 15 and the layer surface of the mat layer 20. In the present specification, the “normal direction of the optical sheet” means a normal direction to the sheet surface of the optical sheet 10.

  Furthermore, terms used in the present specification for specifying shapes and geometric conditions, for example, terms such as “triangle”, “parallel”, “orthogonal”, “symmetric”, etc. are not bound to a strict meaning. Therefore, it should be interpreted including an error to the extent that a similar optical function can be expected.

  Further, the “unit optical element” in the present specification refers to an element having a function of changing the traveling direction of the light by applying an optical action such as refraction, reflection or diffraction to the light. Based on only the difference, it is not distinguished from elements such as “unit shape element”, “unit prism” and “unit lens”.

  Next, an example of a method for manufacturing the optical sheet 10 having the above configuration will be described.

  The optical sheet manufacturing method described below includes a step of producing a sheet material 11 and a step of punching out a part of the sheet material to produce an optical sheet composed of the part. In the step of producing the sheet material, the resin film 16 that forms the base material layer 15 and the mat formed on the resin film 16 corresponding to the configuration of the optical sheet 10 to be produced as described above. A sheet material 11 having the layer 20 and the optical element layer 30 is produced. The step of producing the sheet material 11 includes a step of forming the optical element layer 30 on the resin film 16 and a step of forming the mat layer 20 on the resin film 16. Hereinafter, each process will be described together with devices used in each process.

  First, the process of forming the optical element layer 30 on the resin film 16 in the process of producing the sheet material 11 will be described mainly with reference to FIG. In this step, the optical element layer forming apparatus 50 shown in FIG. 3 is used.

  First, the optical element layer forming apparatus 50 will be described. As shown in FIG. 3, the optical element layer forming apparatus 50 has a molding die 52 having a substantially cylindrical outer contour. A cylindrical mold surface (uneven surface) 52 a is formed in a portion corresponding to the outer peripheral surface (side surface) of the column of the molding die 52. The mold 52 having a cylindrical shape has a central axis CA that passes through the center of the outer peripheral surface of the cylinder, in other words, a central axis CA that passes through the center of the cross section of the cylinder. A concave portion (not shown) corresponding to the unit optical element 35 of the optical sheet 10 is formed on the mold surface 52a. That is, the mold 52 is configured as a roll mold that molds the optical element layer 30 while rotating around the central axis CA as a rotation axis (see the arc-shaped arrow in FIG. 3).

  As shown in FIG. 3, the optical element layer forming apparatus 50 supplies the resin material 39 having fluidity between the belt-shaped resin film 16 to be supplied and the mold surface 52 a of the molding die 52. The apparatus 54 further includes a curing device 56 that cures the material 39 between the resin film 16 and the uneven surface 52 a of the molding die 52. The curing device 56 can be appropriately configured according to the curing characteristics of the material 39 to be cured.

  Next, a method for molding the optical element layer 30 using the optical element layer forming apparatus 50 will be described. First, the resin film 16 extending in a band shape is supplied to the optical element layer forming apparatus 50. This resinous film 16 finally forms the base material layer 15 of the optical sheet 10, and as an example, mechanical characteristics (strength etc.), chemical characteristics (stability etc.) and optical characteristics (light Biaxially stretched polyethylene terephthalate film having good permeability and the like and available at low cost can be obtained. As shown in FIG. 3, the supplied resin film 16 is fed into the molding die 52 from the left side so that the molding die 52 and the pair of rollers 58 face the concave and convex surface 52 a of the die 52. Will be held.

  Further, as shown in FIG. 3, with the supply of the resin film 16, a material 39 having fluidity is supplied from the material supply device 54 between the resin film 16 and the mold surface 52 a of the molding die 52. The This material 39 comes to form the unit optical element 35 and the land part 31. Here, “having fluidity” means that the material 39 supplied to the mold surface 52a of the mold 52 has such fluidity that it can enter into a recess (not shown) of the mold surface 52a. means.

  As the material 39 to be supplied, various known materials that can be used for molding can be used. In the following example, an example in which an acrylate ionizing radiation curable resin is supplied from the material supply device 54 will be described. As the ionizing radiation curable resin, for example, a UV curable resin that is cured by being irradiated with ultraviolet rays (UV) or an EB curable resin that is cured by being irradiated with an electron beam (EB) may be selected. it can.

  Thereafter, the resin film 16 as the molding substrate passes through a position facing the curing device 56 in a state where the space between the mold surface 52a of the mold 52 is filled with the ionizing radiation curable resin. At this time, ionizing radiation corresponding to the curing characteristics of the ionizing radiation curable resin 39 is emitted from the curing device 56, and the ionizing radiation is transmitted through the resin film 16 and irradiated onto the ionizing radiation curable resin 39. . When the ionizing radiation curable resin 39 is an ultraviolet curable resin, the curing device 56 is, for example, an ultraviolet irradiation device such as a high-pressure mercury lamp. As a result, the ionizing radiation curable resin 39 filled between the mold surface 52a and the resin film 16 is cured, and is made of the cured ionizing radiation curable resin 39 and includes the unit optical element 35 and the land portion 31. The optical element layer 30 is formed on the resin film 16.

  Thereafter, as shown in FIG. 3, the resin film 16 is separated from the mold 52, and accordingly, the unit optical element 35 molded in the concave portion of the mold surface 52 a is formed between the mold 52 and the resin film 16. Together with the land portion 31 located between them, the roller 58 on the right side in FIG. In such a molding method, the presence of the land portion 31 effectively prevents the molded unit optical element 35 from partially remaining in the recess of the mold 52 at the time of mold release. Can be prevented.

  As described above, while the molding die 52 configured as a roll die is rotated around its central axis CA, the material 39 having fluidity is supplied into the die 52; The step of curing the material 39 supplied in the mold 52 in the mold 52 and the step of removing the cured material 39 from the mold 52 are sequentially performed on the mold surface 52a of the mold 52, and the optical element layer 30 is formed. Molded.

  Next, the step of forming the mat layer 20 on the side opposite to the side on which the optical element layer 30 of the resin film 16 is formed in the step of producing the sheet material 11 will be described with reference mainly to FIG. While explaining.

  In this step, the mat layer forming apparatus 60 shown in FIG. 4 is used. The mat layer forming device 60 includes a coating device 62 that applies the resin material 23 containing the diffusing particles 21 to the resin film 16, and a curing device 64 that cures the resin material 23 applied on the resin film 16. Have. As the coating device 62, a coater of a type that discharges a liquid resin material from a T-die nozzle is used in FIG. 4, but various other known coaters can also be used. Moreover, the curing device 64 can be appropriately configured according to the curing characteristics of the resin material 23 applied from the coating device 62.

  When the resin film 16 on which the optical element layer 30 is formed is supplied from the optical element layer forming apparatus 50 to the mat layer forming apparatus 60, the resin containing the diffusing particles 21 is applied from the coating apparatus 62 of the mat layer forming apparatus 60. The material 23 is applied to the surface of the resin film 16 opposite to the side on which the optical element layer 30 is formed (the upper surface in FIG. 4). The applied resin material 23 extends and spreads on the resin film 16.

  The resin material 23 supplied from the coating device 62 forms the binder resin 22 of the mat layer 21. As this resin material 23, various known resin materials of thermosetting type and ionizing radiation curable type can be used. Further, as described above, the diffusing particles 21 dispersed in the resin material 23 can be made of various known materials and particles having various known shapes. In the example shown below, an example in which ionizing radiation curable resin is supplied from the coating device 62 will be described. As the ionizing radiation curable resin, for example, a UV curable resin that is cured by being irradiated with ultraviolet rays (UV) or an EB curable resin that is cured by being irradiated with an electron beam (EB) may be selected. it can.

  The average particle diameter and concentration of the diffusion particles 21 are formed so that the outer surface 20a of the mat layer 20 to be finally formed forms an uneven surface (mat surface) that can exhibit a sufficient light diffusion function. Etc. are set. For example, the average particle diameter of the diffusing particles 21 (arithmetic average of the particle diameters calculated by the volume equivalent method) can be 1 μm or more and 10 μm or less, and the concentration of the diffusing particles 21 is 0.1 wt% or more and 30 wt%. % Or less.

  The resin film 16 coated with the ionizing radiation curable resin material 23 in which the diffusing particles 21 are dispersed passes through a position facing the curing device 64. At this time, ionizing radiation corresponding to the curing characteristics of the ionizing radiation curable resin material 23 is emitted from the curing device 64. Therefore, the ionizing radiation curable resin material 23 applied on the resin film 16 is irradiated with ionizing radiation and cured. As a result, a mat layer 20 made of the binder resin 22 made of the cured ionizing radiation curable resin material 23 and the diffusion particles 21 dispersed in the ionizing radiation curable resin material 23 is formed on the resin film 16. Is done.

  The sheet having the resin film 16, the mat layer 20 formed on one side of the resin film 16, and the optical element layer 30 formed on the other side of the resin film 16 as described above. Material 11 is produced.

  Next, the process of punching the sheet material 11 to obtain the optical sheet 10 will be described mainly with reference to FIG.

  FIG. 5 shows an example of a punching device 70 that can be used in this process. A punching device 70 shown in FIG. 5 includes a punching head 71 having a punching blade 72, a surface plate 75 disposed opposite the punching head 71, and a sheet material between the punching head 71 and the surface plate 75. 11, a collecting unit 80 that collects the obtained optical sheet 11, and a winding unit 85 that winds up the sheet material 11 after the optical sheet 11 is punched out.

  The punching blade 72 of the punching head 71 has a plan view shape along the outer contour of the optical sheet 11 to be punched. As an example, when a rectangular optical sheet 10 having a predetermined size is manufactured, a circumferential punching blade 72 extending corresponding to the four sides of the rectangular shape is used. The punching head 71 having the punching blade 72 is not shown in the drawing, but can be moved toward and away from the surface plate 75 by a fluid pressure driven piston and cylinder mechanism. . The conveying unit 77 includes two or more guide rollers 78 and an endless (ie, circumferential) belt-like member 79 that is stretched over the guide rollers 78. The guide roller 78 is disposed so that the surface plate 75 is positioned inside the movement path of the belt-like member 79. In the present embodiment, the punching blade 72 is made of carbon steel whose surface is coated with a silicon resin, but other than that, a punch made of a metal such as titanium, ceramics or the like can also be used.

  Next, a method for punching the sheet material 11 using the punching device 70 to obtain the optical sheet 10 will be described. First, the sheet material 11 is fed between the belt-shaped member 79 of the conveying unit 77 and the guide roller 86 disposed above the belt-shaped member 79. Thereafter, the sheet material 11 is moved along with the movement of the belt-shaped member 79 while being placed on the belt-shaped member 79 of the conveying unit 77.

  Here, when the sheet material 11 advances to a position facing the punching head 71 above the surface plate 75, the punching head 71 proceeds in a direction approaching the surface plate 75, and the punching blade 72 of the punching head 71 is moved to the sheet material 11. To come into contact. Further, the punching head 71 advances in a direction approaching the surface plate 75, and the punching blade 72 having a rectangular circumference penetrates the sheet material 11 and comes into contact with the belt-like member 79. As a result, the optical sheet 10 is punched from the sheet material 11, and the optical sheet 10 having a predetermined outer contour corresponding to the shape of the punching blade 72 is obtained.

  During the punching process, the surface plate 75 supports the sheet material 11 to be punched from the side opposite to the punching head 71. However, since the surface plate 75 is hard, when the punching blade 72 penetrating the sheet material 11 comes into contact with the surface plate 75, the punching blade 72 is damaged. Therefore, in the method described here, the belt-shaped member 79 between the sheet material 11 to be punched and the surface plate 75 on the side opposite to the punching head 71 of the sheet material 11 to be punched is punched. At the position where the blade 72 does not penetrate, the movement toward the surface plate side to the punching head 71 stops.

  That is, in this apparatus, the belt-like member 79 of the conveying means 77 is used to prevent the punching blade 72 from cracking and the surface plate 75 from being chipped due to the collision between the punching blade 72 punched from the sheet material 11 and the surface plate 75. It also functions as a cushioning material. From this point of view, the belt-like member 79 is made of a material having a certain degree of elasticity, for example, a relatively inexpensive resin such as polyethylene terephthalate, and is a disposable that is discarded after several uses. It is good.

  Since the punching head 71 is advanced and retracted at a high speed, the sheet material 11 does not necessarily have to be stopped while the punching blade 72 is stuck into the sheet material 11. On the other hand, in order to increase the accuracy of the punching process, the sheet material 11 may be stopped when the punching head 71 moves back and forth. Alternatively, the punching head 71 is configured to be movable in the conveying direction of the sheet material 11 by the conveying means 77, and the punching process is performed in a state where the punching head 71 is moving in synchronization with the sheet material 11. Also good.

  The punching process as described above is continuously performed on the web-shaped sheet material 11, and the sheet-like optical sheet 10 including the punched portion of the sheet material 11 is sequentially obtained. The optical sheet 10 obtained by the punching process does not necessarily have to be a size in the final use state, and may be further processed to an appropriate size according to the use of each optical sheet. Good.

  In the illustrated example, the obtained optical sheets 10 are sequentially collected and stacked by the collecting means 80. And the sheet-like optical sheet 10 receives handling, such as conveyance, in the state piled up many until it reaches the final use aspect. On the other hand, the punched sheet material 12 after the optical sheet is punched is no longer used. The punched sheet material 12 is pulled away from the optical sheet 10 continuously conveyed by the belt-like member 79 by the guide roller 87 (toward the upper right in FIG. 5), and is taken up as waste by the winding means 85. It is wound up.

  As described above, according to the manufacturing method for extracting the optical sheet 10 having a predetermined shape and size from the belt-shaped sheet material 11 by punching, as compared with the case of cutting the optical sheet from the sheet material by cutting or the like. It is preferable in that it does not cause cutting, scraping or cutting. Therefore, according to the manufacturing method of the present embodiment adopting the punching process, a cut piece, a shaving or the like is attached to the produced optical sheet, or the produced optical sheet 10 is a cut piece, a shaving, It is possible to effectively prevent damage due to a cutting beam or the like, and to stably provide the optical characteristics planned for the optical sheet and the apparatus in which the optical sheet is incorporated. In addition, since there is no cutting or shavings, the periphery of the punching device 70 can be kept clean, thereby reducing the number of complicated cleaning operations.

  Further, when an optical sheet is cut out from a sheet material by cutting or the like, it is necessary to advance the tool circumferentially along the outer contour of the optical sheet to be cut out. On the other hand, according to the manufacturing method in which the optical sheet 10 is extracted from the sheet material 11 by punching, the optical sheet 10 can be obtained by the high-speed reciprocation of the punching head 71. That is, according to the manufacturing method of the present embodiment that employs punching, not only in terms of quality but also in terms of production efficiency, the manufacturing cost of the optical sheet can be reduced as a result.

  By the way, according to the manufacturing method in which the optical sheet 10 is extracted from the sheet material 11 by punching, the facet, shaving, and cutting burr are not generated as compared with the case of cutting the optical sheet 10 from the sheet material 11 by cutting or the like. Is as described above. However, as a result of extensive research conducted by the present inventor, even when the optical sheet 10 is extracted from the sheet material 11 by punching, problems such as the occurrence of cutting, scraping, or cutting flash can occur. Was confirmed. That is, even when the optical sheet 10 is extracted from the sheet material 11 by punching, foreign matter adheres to the optical sheet 10 or the optical sheet 10 is damaged by the foreign matter, and as a result, the optical sheet 10 and the optical sheet 10 are concerned. The final product incorporating the can no longer perform its intended optical function.

  The inventor of the present invention has found the following as a result of earnest research on the cause of foreign matter adhesion to the optical sheet 10 obtained by punching and the damage of the optical sheet 10 obtained by punching.

  First, most of the foreign matters adhering to the optical sheet 10 obtained by punching were the binder resin 22 and the light diffusing particles 21 in the mat layer 20. Then, in the edge region formed by the punching process of the optical sheet 10 to which foreign matter is attached or the damaged optical sheet 10, a crack (crack) occurs in the mat layer 20 or the mat layer 20 Peeling from the base material layer 15 occurred. That is, the mat layer 20 is cracked or peeled off during the punching process. As a result, the binder resin 22 in the mat layer 20 collapses to generate resin debris, and the diffusing particles 21 fall off from the mat layer 20. is expected.

  Then, the present inventor continues earnest research based on the above, and when the following conditions 1 and 2 are satisfied, the mat layer 20 is cracked during the punching process by the above-described method. It was confirmed that the mat layer 20 can be prevented from peeling off.

[Condition 1]
The sheet material 11 having the surface 10a on one side formed by the mat layer 20 is punched so that the punching blade 72 starts to contact the sheet material 11 from the surface 10a on the one side. . At this time, the pencil hardness of the surface 10a on one side measured in accordance with JIS K5600-5-4 (1999) is preferably 3B or more, and JIS K5600-5-4. It is preferable that the pencil hardness of the surface 10a on one side measured in accordance with (1999) is 3H or less.

  In the B series, the hardness decreases as the Arabic numeral increases (softer). On the other hand, in the H series, the hardness increases (hardens) as the Arabic numeral increases. Therefore, here, the pencil hardness of 3B or more and 3H or less means that the pencil hardness is harder than 3B and softer than 3H, that is, the pencil hardness in the range of 3B, 2B, B, HB, F, H, 2H, and 3H. It means that either.

[Condition 2]
The sheet material 11 is formed of the mat layer 20 and has a surface 10a on one side whose pencil hardness measured in accordance with JIS K5600-5-4 (1999) is B or less. The punching blade 72 starts to come into contact with the sheet material 11 from the surface 10b on the other side opposite to the surface 10a on the other side, and punching is performed. At this time, it is preferable that the pencil hardness of the surface 10a on one side measured in accordance with JIS K5600-5-4 (1999) is 3B or more.

  Although the reason why the above-described problems can be solved by either of the condition 1 and the condition 2 is not exactly known, it is presumed that the following points contribute to it. However, the present invention is not limited to the following estimation.

  When punching is performed, the punching blade 72 uses both blades whose both surfaces of the punching blade 72 are inclined with respect to the traveling direction of the punching blade 72 during the punching processing, or the traveling direction of the punching blade 72 during the punching processing. On the other hand, the sheet material 11 is deformed (distorted) regardless of which direction the single blade of which only one surface of the punching blade 72 is inclined is used. Then, from the result of microscopic observation of the optical sheet 10 obtained by the punching process, the deformation (distortion) is greater than the surface of the sheet material 11 on the side where the punching blade 72 enters (the side on which contact begins). It appears that the surface on the side from which the punching blade 72 is pulled out is larger. That is, the deformation amount of the sheet material 11 seemed to increase on the side facing the belt-like member 79 and the surface plate 75 that also function as the buffer material 11.

  For this reason, if the sheet material 11 is arranged so that the mat layer 20 is positioned on the punching head 71 side where the deformation amount is reduced as in the condition 1, the deformation amount of the mat layer 20 during the punching process is reduced. obtain. As a result, according to the condition 1, it is estimated that the stress applied to the mat layer 20 is reduced, and the mat layer 20 can be effectively prevented from being cracked or peeled off.

  Even when the punching blade 72 was inserted from the mat layer 20 side, when the pencil hardness of the mat layer 20 was 4H or more, the elasticity of the mat layer 20 was remarkably lowered, and cracking and peeling occurred. On the other hand, if the pencil hardness of the mat layer 20 is 4B or less, the hardness is too low, and the mat layer 20 functions effectively in actual use, particularly in actual use as an optical sheet incorporated in a surface light source device. I can't do that. From these points, in condition 1, it is preferable that the pencil hardness of the surface 10a on one side measured in accordance with JIS K5600-5-4 (1999) is 3B or more and 3H or less.

  On the other hand, according to Condition 2, the mat layer 20 is located on the side of the belt-like member 79 and the surface plate 75 where the amount of deformation increases, but the pencil hardness of the mat layer 20 is B or less. For this reason, although the deformation amount of the mat layer 20 increases, the mat layer 20 effectively prevents cracking of the mat layer 20 and peeling of the mat layer 20 due to the high elasticity. It is speculated that it can be done.

  Similar to the case where the punching blade 72 is inserted from the mat layer 20 side, even when the punching blade 72 is inserted from the side opposite to the mat layer 20, the hardness of the mat layer 20 having a pencil hardness of 4B or less. The mat layer 20 cannot function effectively in actual use, particularly in actual use as an optical sheet incorporated in a surface light source device. From this point, in condition 2, it is preferable that the pencil hardness of the surface 10a on one side measured according to JIS K5600-5-4 (1999) is 3B or more.

  Here, an example of the result of an experiment conducted by the present inventor will be shown. In the experiment described below, using the punching device 70 described above, the sheet material 11 having the above-described configuration, that is, the resin film 16 and the surface 10a on one side laminated on one side of the resin film 16 are provided. A sheet material 11 comprising a mat layer 20 formed and an optical element layer 30 laminated on the other side of the resin film 16 and forming the surface 10b on the other side is punched out, and the above-described sheet material shown in FIGS. The optical sheet 10 was produced.

  Prior to the punching experiment, by adjusting the materials used for the mat layer and the formation conditions of the mat layer, sheet materials according to samples 1 to 9 having different mat layer hardnesses were produced. On the other hand, the resin film and the optical element layer were the same between samples. Specifically, a biaxially stretched polyethylene terephthalate film having a thickness of 188 μm was used as the resin film. The pencil hardness of the resin film surface was HB. The optical element layer has a configuration in which unit optical elements having a cross-sectional shape of a right isosceles triangle shape with a height of 25 μm are arranged at a pitch of 50 μm so that a right angle is projected.

The mat layers of the sheet materials (optical sheets) according to Samples 1 to 9 were formed using, as binder resins, ultraviolet curable resins adjusted with different formulations as shown below. As an ultraviolet irradiation apparatus for curing the ultraviolet curable resin, an ultraviolet ray H valve manufactured by Fusion UV Systems Japan Co., Ltd. was used for each sample. The curing conditions for curing the ultraviolet curable resin were the same between samples 1 to 9, with the irradiation amount being 100 mJ / cm ² . The mat layer of each sample is coated with a coating material containing the materials (resin material, diffusion particles, initiator) of Samples 1 to 9 below using a bar coater so that the film thickness in a solidified state is 3 μm. Formed.

[Sample 1: Pencil hardness of mat layer 3B]
○ Resin material: M-215 manufactured by Toagosei Co., Ltd .: 99 parts by weight ○ Diffusion particles • Spherical cross-linked acrylic resin beads having an average particle size of 5 μm (MX-500H, manufactured by Soken Chemical Co., Ltd.): 1 part by weight ○ Initiator 1-hydroxycyclohexyl phenyl ketone (trade name Irgacure 184) manufactured by Ciba Japan Co., Ltd .: 1 part by mass

[Sample 2: Matte layer pencil hardness 2B]
○ Resin material: M-215 manufactured by Toagosei Co., Ltd .: 66 parts by weight; Opstar JN35 manufactured by JSR Corporation: 33 parts by weight ○ Spherical cross-linked acrylic resin beads having an average particle diameter of 5 μm (manufactured by Soken Chemical Co., Ltd., MX-500H): 1 part by weight ○ Initiator 1-hydroxycyclohexyl phenyl ketone (trade name Irgacure 184) manufactured by Ciba Japan Co., Ltd .: 1 part by weight

[Sample 3: Pencil hardness B of mat layer]
○ Resin material: M-215 manufactured by Toagosei Co., Ltd .: 33 parts by weight, Opstar JN35 manufactured by JSR Corporation: 66 parts by weight ○ Spherical cross-linked acrylic resin beads having an average particle size of 5 μm (manufactured by Soken Chemical Co., Ltd., MX-500H): 1 part by weight ○ Initiator 1-hydroxycyclohexyl phenyl ketone (trade name Irgacure 184) manufactured by Ciba Japan Co., Ltd .: 1 part by weight

[Sample 4: Pencil hardness HB of mat layer]
-Resin material-Opstar JN35 manufactured by JSR Corporation: 99 parts by weight-Diffusion particles-MX-500H manufactured by Soken Chemical Co., Ltd. (spherical crosslinked acrylic resin beads having an average particle diameter of 5 μm): 1% by weight
○ Initiator 1-hydroxycyclohexyl phenyl ketone (trade name Irgacure 184) manufactured by Ciba Japan Co., Ltd .: 1 part by mass

[Sample 5: Pencil hardness F of mat layer]
-Resin material-Pentaerythritol triacrylate manufactured by Nippon Kayaku Co., Ltd .: 49.5 parts by weight-Opstar JN35 manufactured by JSR Corporation: 49.5 parts by weight-Diffusion particles-MX-500H manufactured by Soken Chemical Co., Ltd. (average Spherical cross-linked acrylic resin beads with a particle size of 5 μm): 1% by weight
○ Initiator 1-hydroxycyclohexyl phenyl ketone (trade name Irgacure 184) manufactured by Ciba Japan Co., Ltd .: 1 part by mass

[Sample 6: Pencil hardness H of mat layer]
-Resin material-Pentaerythritol triacrylate manufactured by Nippon Kayaku Co., Ltd .: 99 parts by weight-Diffusion particles-MX-500H manufactured by Soken Chemical Co., Ltd. (spherical crosslinked acrylic resin beads having an average particle diameter of 5 μm): 1% by weight
○ Initiator 1-hydroxycyclohexyl phenyl ketone (trade name Irgacure 184) manufactured by Ciba Japan Co., Ltd .: 1 part by mass

[Sample 7: Pencil hardness of mat layer 2H]
-Resin material-Dipentaerythritol hexaacrylate manufactured by Nippon Kayaku Co., Ltd .: 49.5 parts by weight-Pentaerythritol triacrylate manufactured by Nippon Kayaku Co., Ltd .: 49.5 parts by weight-Diffusion particles-manufactured by Soken Chemical Co., Ltd. MX-500H (spherical crosslinked acrylic resin beads having an average particle diameter of 5 μm): 1% by weight
○ Initiator 1-hydroxycyclohexyl phenyl ketone (trade name Irgacure 184) manufactured by Ciba Japan Co., Ltd .: 1 part by mass

[Sample 8: Pencil hardness of mat layer 3H]
-Resin material-Nippon Kayaku Co., Ltd. dipentaerythritol hexaacrylate: 99 weight part-Diffusion particle-MX-500H made by Soken Chemical Co., Ltd. (spherical cross-linked acrylic resin beads having an average particle size of 5 μm): 1 weight %
○ Initiator 1-hydroxycyclohexyl phenyl ketone (trade name Irgacure 184) manufactured by Ciba Japan Co., Ltd .: 1 part by mass

[Sample 9: Pencil hardness of mat layer 4H]
○ Resin material: Nippon Kayaku Co., Ltd. dipentaerythritol hexaacrylate: 99 parts by weight ○ Diffusion particles (inorganic nanoparticles)
-Aluminum oxide C (aluminum oxide nanoparticles with a particle size of 13 nm) manufactured by Degussa-Huels AG: 1% by weight
○ Initiator 1-hydroxycyclohexyl phenyl ketone (trade name Irgacure 184) manufactured by Ciba Japan Co., Ltd .: 1 part by mass

  About each sheet material 11, a crack, peeling, etc. by the case where it punches from the mat layer 20 side (one surface 10a side) and the case where it punches from the optical element layer 30 side (the other surface 10b side) An investigation was made as to whether or not these defects occurred in the mat layer 11. The presence or absence of defects was confirmed by observing the optical sheet at a magnification of 100 to 300 times with a scanning electron microscope. The confirmation results are shown in Table 1. In Table 1, a sample in which the presence of a defect is confirmed is marked with a circle, and a sample in which the presence of a defect is not confirmed is marked with a cross. In addition, in the column of “Matte layer” in Table 1, the presence or absence of defects when each sheet material is punched from the side of the mat layer is shown. In the column of “Optical element layer” in Table 1, the mat layer is Indicates the presence or absence of defects when each sheet material is punched from the opposite side, that is, the optical element layer side,

As shown in Table 1, when the mat layer is punched from the side of the mat layer 20, the sample having a mat layer hardness of 3H or less measured according to JIS K5600-5-4 (1999) Was not found. On the other hand, when punched from the side opposite to the mat layer 20, that is, the side of the optical element layer 30, a sample having a mat layer hardness of B or less measured according to JIS K5600-5-4 (1999) So no defects were found.

  By the way, the inventor of the present invention peeled off the mat layer 20 from the base material layer 15 during the subsequent handling and use of the obtained optical sheet in the course of conducting research to optimize the processing conditions of the punching process. Thus, the optical sheet 10 that can effectively prevent the occurrence of the problem has been found. Hereinafter, the configuration of the optical sheet 10 will be described mainly with reference to FIGS. 6 and 7. The optical sheet 10 in FIGS. 6 and 7 to be described below can be manufactured by adopting the above-described condition 1 and appropriately adjusting the processing conditions within a normally used range.

  FIG. 6 shows the optical sheet 10 in a cross section along the normal direction nd of the optical sheet 10. As shown in FIG. 6, the outer contour of the outer surface 20a of the mat layer 20 in the cross section along the normal direction nd of the optical sheet 10 does not include the diffusing particles 21 in the end region EZ in the vicinity of the end surface 20c. In the region, as it approaches along the direction perpendicular to the normal direction nd toward the end surface 20c (in other words, the direction pd parallel to the sheet surface of the optical sheet 10), the base material layer gradually increases in the normal direction nd. It is shifted to the 15 side.

  Here, the fact that the outer contour of the outer surface 20a of the mat layer 20 gradually shifts toward the substrate layer 15 means that the outer contour of the outer surface 20a of the mat layer 20 always follows the normal direction nd. This means that the outer contour of the outer surface 20a may be parallel to the sheet surface of the optical sheet 10 in some areas. That is, the outer contour of the outer surface 20a of the mat layer 20 in the cross section along the normal direction nd is in the region where the diffusing particles 21 are not present in the end region EZ with respect to the direction pd orthogonal to the normal direction nd. It is defined as an inclined straight line, a curved line, a combination of a straight line and a curved line with respect to a direction pd orthogonal to the normal direction nd, or a combination of these and a straight line orthogonal to the normal direction nd. .

  Moreover, the edge part area | region EZ here is the area | region which is the vicinity of the end surface 20c, and the surface 10a of the optical sheet 10 has curved with respect to the other area | region. In other words, the end portion region EZ is a region in the vicinity of the end surface 20c where the surface 10a is no longer parallel to the sheet surface of the optical sheet 10.

  According to such an optical sheet 10, even if the optical sheet is rubbed by another member such as another optical sheet 10 stacked on the mat layer 20 of the optical sheet 10, Is not applied to the mat layer 20 in the end region EZ. That is, a force for peeling the mat layer 20 from the base material layer 15 can be applied to the mat layer 20 in the end region EZ that tends to be a starting point of the mat layer 20. As a result, according to such an optical sheet 10, the mat layer 20 can be effectively prevented from being peeled off from the base material layer 15 during handling such as conveyance or during use while being stacked with other members. Can continue to maintain stable quality.

  In particular, in the example shown in FIG. 6, the outer contour of the outer surface 20a of the mat layer 20 in the cross section along the normal direction nd of the optical sheet 10 is in a region where the diffusing particles 21 are not present in the end region EZ. As it approaches along the direction perpendicular to the normal direction nd toward the end surface 20c, the end surface 20c continues to shift toward the base material layer 15 in the normal direction nd. According to such an aspect, rubbing with the above-described other members becomes extremely smooth, the above-described operational effects are more remarkably exhibited, and peeling of the mat layer 20 can be extremely effectively prevented.

  7 shows the mat layer 20 end surface 20c of the optical sheet 10 in a cross section along the normal direction nd of the optical sheet 10. FIG. In particular, FIG. 7 shows an enlarged area surrounded by a dotted line in FIG.

  As shown in FIG. 7, the end surface 20c of the mat layer 20 is, in a cross section along the normal direction nd of the optical sheet 10, at an inner end 20cb that intersects the inner surface 20b rather than an outer end 20ca that intersects the outer surface 20a. , Located outward along the direction pd perpendicular to the normal direction nd. In other words, in the cross section along the normal line direction nd, the end surface 20c is outward in the direction pd parallel to the sheet surface of the optical sheet 10 at the inner end portion 20cb than the outer end portion 20ca, that is, It is located on the side away from the center of the optical sheet 10.

  According to such an aspect, the force that causes the mat layer 20 to peel from the base material layer 15 on the inner end portion 20cb of the mat layer 20 that is likely to be a starting point of the peeling of the mat layer 20 is the end surface 20c of the mat layer 20. Can be added and made difficult. As a result, according to such an optical sheet 10, the mat layer 20 is removed from the base material layer 15 due to being rubbed with other members in the normal direction nd, for example, during handling such as transport or during use. Peeling is effectively prevented and stable quality can be maintained.

  Furthermore, as shown in FIG. 7, the outer contour of the end surface 20c of the mat layer 20 in the cross section along the normal direction nd of the optical sheet 10 is in the normal direction nd as it goes from the outer end 20ca to the inner end 20cb. It gradually shifts outward in the direction orthogonal to the. That is, the outer contour of the end surface 20c in the cross section along the normal direction nd is outward along the direction pd parallel to the sheet surface of the optical sheet 10 from the outer end 20ca toward the inner end 20cb. In other words, the optical sheet 10 is displaced from the center away from the center.

  Note that the outer contour of the end surface 20c of the mat layer 20 is always shifted outwardly in the direction pd perpendicular to the normal direction nd when the outer contour of the end surface 20c of the mat layer 20 is always the legal contour. It does not only mean that it continues to shift outward along the direction pd orthogonal to the line direction nd, but the outer contour of the end face 20c may be parallel to the normal direction nd in some areas. . That is, the outer contour of the end face 20c of the mat layer 20 in the cross section along the normal direction nd is a straight line or a curve inclined with respect to the normal direction nd, or a straight line and a curve inclined with respect to the normal direction nd. Or a combination of these and a straight line parallel to the normal direction nd.

  Even with such an optical sheet 10, the force to peel the mat layer 20 from the base material layer 15 on the inner end 20 cb of the mat layer 20, which is likely to be the starting point of the mat layer 20, is applied to the end surface of the mat layer 20. It can be added through 20c. As a result, according to such an optical sheet 10, the mat layer 20 is removed from the base material layer 15 due to being rubbed with other members in the normal direction nd, for example, during handling such as transport or during use. Peeling is effectively prevented and stable quality can be maintained.

  In particular, in the example shown in FIG. 7, the outer contour of the end surface 20c of the mat layer 20 in the cross section along the normal direction nd of the optical sheet 10 is normal to the inner end 20cb from the outer end 20ca. In the direction pd orthogonal to the direction nd, it continues to shift outward. According to such an aspect, the above-described effects can be exhibited more remarkably, and peeling of the mat layer 20 can be extremely effectively prevented.

  According to the present embodiment as described above, the optical sheet 10 can be manufactured while effectively preventing the occurrence of defects such as adhesion of foreign matter and scratches. Moreover, according to this Embodiment as mentioned above, the mat layer 20 can be made difficult to peel from the optical sheet 10.

  Note that various modifications can be made to the above-described embodiment. Hereinafter, an example of modification will be described with reference to the drawings as appropriate.

  In the embodiment described above, the example in which the optical element layer 30 includes the unit prism having a triangular cross section as the unit optical element 35 has been described. However, the present invention is not limited to this. For example, the optical element layer 30 may include, as a unit optical element, a unit lens in which an outer contour in a cross section is formed by a curved line (for example, corresponding to a part of a circle, an ellipse, a fence line, a hyperbola, a sinusoidal curve, or the like). .

  In the above-described embodiment, the example in which the optical element layer 30 is configured by the linear (linear) unit optical elements 35 arranged linearly (one-dimensionally) has been described. However, the present invention is not limited thereto. . The optical element layer 30 may be constituted by point-like unit optical elements arranged two-dimensionally, that is, in a form called a microlens or a fly-eye lens.

  Furthermore, as shown in FIG. 8, the optical element layer 30 may include a plurality of types of unit optical elements. In the example shown in FIG. 8, the optical element layer 30 includes a plurality of first unit shape elements (dot-like unit shape elements) 35 a that are provided on the land portion 31 and constitute fly eye lenses (microlenses), and the land portion 31. And a plurality of second unit shape elements (linear unit shape elements) 35b provided on the top and extending linearly. The plurality of first unit shape elements 35a are two-dimensionally arranged. The plurality of second unit shape elements 35b are linearly arranged (one-dimensionally arranged) like the unit optical elements in the above-described embodiments. The first unit shape elements 35 a are arranged on the land portion 31 with a gap. The second unit shape element 35 b is disposed in the area between the first unit shape elements 35 a on the land portion 31. By adopting the optical element layer having such a configuration, the light beam emitted from the optical sheet has an inherent reciprocity of increasing the luminance in the front direction (normal direction of the sheet surface of the optical element surface) and increasing the diffusion angle. It has a unique effect that the optical characteristics can be made compatible.

  Note that the modification shown in FIG. 8 is different from the above-described embodiment only in the configuration relating to the unit optical element of the optical element layer 30, and can be configured in the same manner as the above-described embodiment. Therefore, in FIG. 8, the same reference numerals as those used for the corresponding parts in the above-described embodiment are used, and redundant description of the parts that can be configured in the same manner as in the above-described embodiment is omitted.

  In the above-described embodiment, the optical element layer 30 is first formed on the resin film 16 and then the mat layer 20 is formed on the resin film 16. However, the present invention is not limited to this. The mat layer 20 may be formed on the resin film 16 first, and then the optical element layer 30 may be formed on the resin film 16.

  Furthermore, in the above-described embodiment, an example in which the optical element layer 30 is formed on the resin film 16 by molding using an ionizing radiation curable resin has been described, but the present invention is not limited thereto. The base material layer 15 and the optical element layer 30 may be formed of the same resin by melt extrusion molding. In this example, there can be no interface between the base material layer 15 and the optical element layer 30.

  Furthermore, in the above-described embodiment, an example in which the manufacturing method of the optical sheet includes the step of producing the sheet material 11, that is, as if the sheet material 11 is continuously produced and produced. An example is shown in which punching is performed. However, it is not necessary to produce the sheet material 11 each time the sheet material 11 is supplied to the punching process. A necessary amount of sheet material that has been produced together or sheet material that has been produced and conveyed in another location (for example, a sheet material that has been wound up and stored in a roll) is transferred to the punching device 70 by a required amount. You may make it supply.

DESCRIPTION OF SYMBOLS 10 Optical sheet 10a Surface 10b Surface 11 Sheet material 15 Base material layer 16 Resin film 20 Mat layer 20a Outer side surface 20b Inner side surface 20c End surface 20ca Outer end portion 20cb Inner end portion 21 Diffusion particle (diffusion component)
22 Binder resin 23 Resin material 30 Optical element layer 31 Land portion 35 Unit optical element 35a Unit optical element, first unit optical element 35b Unit optical element, second unit optical element 39 Material 50 Optical element layer forming apparatus, shaping apparatus 60 Mat layer forming device 70 Punching device, punching machine 71 Punching head 72 Punching blade 75 Surface plate 77 Conveying means 79 Belt-like member

Claims (13)

A base material layer;
An optical sheet comprising diffusing particles and a binder resin, and a mat layer provided on one side of the base material layer,
The mat layer includes an outer surface forming a surface on one side of the optical sheet, an inner surface opposite to the outer surface and facing the base material layer, the inner surface, and the outer surface. An end face between and
In the cross section along the normal direction of the optical sheet, the end surface is outward in the direction orthogonal to the normal direction at the inner end intersecting with the inner surface rather than the outer end intersecting with the outer surface. Located in the optical sheet.   The outer contour of the end surface in a cross section along the normal line direction of the optical sheet gradually shifts outward in a direction orthogonal to the normal line direction from the outer edge toward the inner edge. The optical sheet according to 1.   The outer contour of the outer surface in the cross section along the normal direction of the optical sheet is perpendicular to the normal direction to the end surface in the region where the diffusion particles do not exist in the end region near the end surface. 3. The optical sheet according to claim 1, wherein the optical sheet gradually shifts toward the base material layer in the normal direction as approaching along the direction to be performed. A base material layer;
An optical sheet comprising diffusing particles and a binder resin, and a mat layer provided on one side of the base material layer,
The mat layer includes an outer surface forming a surface on one side of the optical sheet, an inner surface opposite to the outer surface and facing the base material layer, the inner surface, and the outer surface. An end face between and
The outer contour of the outer surface in the cross section along the normal direction of the optical sheet is perpendicular to the normal direction to the end surface in the region where the diffusion particles do not exist in the end region near the end surface. An optical sheet that gradually shifts toward the base material layer in the normal direction as it approaches along the direction of the substrate. An optical element layer provided on the other side of the base material layer,
The optical element layer is
A plurality of unit optical elements arranged in one direction, each extending linearly in a direction intersecting the one direction; and
A plurality of unit optical elements arranged two-dimensionally;
The optical sheet according to any one of claims 1 to 4, comprising at least one of the following.   A surface light source device comprising the optical sheet according to claim 1.   A display device comprising the surface light source device according to claim 6.   A display device comprising the optical sheet according to claim 1.   A sheet material having a surface on one side formed by a matte layer containing diffusion particles and a binder resin was punched by inserting a punching blade from the surface on the one side and punching the sheet material. The manufacturing method of an optical sheet provided with the process of obtaining the optical sheet which consists of sheet materials.   The method for manufacturing an optical sheet according to claim 9, wherein the pencil hardness of the surface on the one side measured in accordance with JIS K5600-5-4 (1999) is 3H or less.   For a sheet material having a surface on one side, which is formed by a mat layer containing diffusing particles and a binder resin and has a pencil hardness of B or less measured according to JIS K5600-5-4 (1999) An optical sheet comprising a punched sheet material by inserting a punching blade from the surface of the other side opposite to the one side and punching the sheet material, Production method.   The optical sheet according to any one of claims 9 to 11, wherein the pencil hardness of the surface on the one side measured in accordance with JIS K5600-5-4 (1999) is 3B or more. Manufacturing method. The sheet material to be punched further has an optical element layer that forms the surface of the other side opposite to the one side,
The optical element layer is
A plurality of unit optical elements arranged in one direction, each extending linearly in a direction intersecting the one direction; and
A plurality of unit optical elements arranged two-dimensionally;
The manufacturing method of the optical sheet as described in any one of Claims 9-12 which has at least one of these.

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