Patent ID: 8475004

Claim:
A transparent sheet for use with a light emitting body with one of surfaces of the transparent sheet being adjacent to the light emitting body, wherein the other surface of the transparent sheet includes a plurality of minute regions δ, a largest inscribed circle of the minute regions δ having a diameter from 0.2 μm to 8.0 μm, one of the minute regions δ being adjoined by and surrounded by some other ones of the minute regions δ, the plurality of minute regions δ include a plurality of minute regions δ 1 which are randomly selected from the plurality of minute regions δ so as to constitute 40% to 98% of the minute regions δ and a plurality of minute regions δ 2 which constitute the remaining portion of the minute regions δ, the minute regions δ 1 are protruding above the other surface to a height of d/2 relative to a predetermined reference plane parallel to the other surface, the minute regions δ 2 are receding below the other surface to a depth of d/2 relative to the predetermined reference plane, the predetermined reference plane is equidistant from the minute regions δ 1 and the minute regions δ 2 in terms of a direction perpendicular to the other surface, d is from 0.2 μm to 1.4 μm, the plurality of minute regions δ have a shape of a polygon in a plane of the other surface, the plurality of minute regions δ are arranged in the plane of the other surface along a first direction that is parallel to one side of the polygon, and ones of the plurality of minute regions δ adjoining each other along the first direction are at positions which are coincident with each other in terms of a second direction that is perpendicular to the first direction, and a pair of minute regions adjoining each other along the second direction are at positions which are shifted from each other in terms of the first direction.