Optical body, method for manufacturing optical body, light-emitting apparatus, and display apparatus for amusement equipment

1. An optical body comprising:

a base material; and

a light extraction section, formed on at least one surface of the base material, that extracts internally propagated light incident inside the base material from a side face of the base material to an outside of the base material, wherein

the light extraction section includes a concave-convex structure in which at least one of concavities and convexities has a frustum shape,

each of the convexities includes

a first flat section forming a top edge face of the frustum shape, and being parallel to a planar direction of the base material, and

a tapered section forming a tapered face of the frustum shape,

each of the concavities includes a second flat section being parallel to the planar direction of the base material,

a fill ratio of the concave-convex structure is 15% or greater,

a light transmittance is 50% or greater,

the concave-convex structure is arranged periodically, and

a ratio A/B of an area B of a unit region obtained by interconnecting central axes of minimum structural units of the concave-convex structure and an area A of a portion existing inside the unit region in a tapered section included in the minimum structural unit is 0.68 or less.

2. The optical body according to claim 1 , wherein the fill ratio of the concave-convex structure is 80% or less.

3. The optical body according to claim 1 , wherein

the concave-convex structure is arranged by any one or more modes selected from a group consisting of a lattice arrangement, a staggered arrangement, and a hexagonal close-packed arrangement.

4. The optical body according to claim 1 , wherein the ratio A/B is 0.40 or less and the light transmittance is 65% or greater.

5. The optical body according to claim 1 , wherein

the concave-convex structure includes any one or more types of frustum shapes selected from a group consisting of a circular frustum, an elliptical frustum, a regular polygonal frustum, a polygonal frustum, a semi-circular frustum, a quarter-circular frustum, and a deformed polygonal frustum.

6. The optical body according to claim 1 , wherein

the base material includes any one or more types of materials selected from a group consisting of acrylic resin, polycarbonate, polyethylene terephthalate, and glass.

7. The optical body according to claim 1 , wherein

the concave-convex structure includes a cured ultraviolet-curing resin.

8. A method for manufacturing an optical body that manufactures the optical body according to claim 1 , the method comprising:

producing a transfer mold having an inverse shape of the concave-convex structure;

forming an uncured resin layer on a surface of the base material; and

curing the uncured resin layer while also transferring the concave-convex structure of the transfer mold to the cured resin layer.

9. A light-emitting apparatus comprising:

the optical body according to claim 1 ; and

a light source, provided on a side face of the optical body, that causes light to be incident inside the optical body from the side face of the optical body.

10. A display apparatus for amusement equipment, comprising:

a display on a rear surface of the light-emitting apparatus according to claim 9 , wherein a luminous intensity of the light source is changed to provide a change in visibility of the optical body.