Daylighting device, molding die, and method of manufacturing daylighting film

A daylighting device comprising

• at least a daylighting film that includes a base having optical transparency and a plurality of daylighting portions having optical transparency and provided on a first surface of the base, wherein
• each of the daylighting portions has a reflective surface by which light incident on the daylighting portion is reflected and the light reflected by the reflective surface and output from a second surface of the base has a characteristic that the light travels toward a space on a side where the light is incident on the reflective surface, the space being one of two spaces divided by a virtual plane as a boundary which is vertical to the second surface of the base and parallel to a direction of the daylighting portion extending,
• intervals s between adjacent daylighting portions are set to a plurality of values,
• a small structure that has optical transparency or light absorbability exists between the plurality of daylighting portions,
• each of the daylighting portions has at least one pair of inclined surfaces that are inclined in directions different from each other relative to one surface of the base and that face each other in a direction of the daylighting portions being arranged, and
• a shape of the small structure is similar to a shape of a part of the daylighting portion, the part having the at least one pair of inclined surfaces.

A molding die for a daylighting film, the daylighting film including a base having optical transparency and a plurality of daylighting portions having optical transparency and provided on a first surface of the base, in which each of the daylighting portions has a reflective surface by which light incident on the daylighting portion is reflected and the light reflected by the reflective surface and output from a second surface of the base has a characteristic that the light travels toward a space on a side where the light is incident on the reflective surface, the space being one of two spaces divided by a virtual plane as a boundary which is vertical to the second surface of the base and parallel to a direction of the daylighting portion extending, and intervals s between adjacent daylighting portions are set to a plurality of values, the molding die comprising:

• a main portion made of metal;
• and
• a plurality of first recessed portions provided on a surface of one side of the main portion and corresponding to the plurality of daylighting portions, wherein
• intervals u between adjacent first recessed portions are set to a plurality of values corresponding to the plurality of values of the intervals s, and
• at least a set of the intervals u between the plurality of first recessed portions in the main portion satisfies a following condition
• u
• ⁢
• ⁢
• 1
• -
• u
• ⁢
• ⁢
• 2
• W
• ⁢
• ⁢
• 2
• ≥
• 0.015
• [
• Math
• .
• ⁢
• 2
• ]
• where u1 and u2 are two of the intervals u with small values among the intervals u between the plurality of first recessed portions in the main portion, and u2 represents a minimum value and u1 represents a value larger than u2.