Patent ID: 8430539

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 an 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 1.5 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 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 a remaining portion of the minute regions δ, the minute regions δ 1 include a raised portion protruding above the other surface, the raised portion having a height of d/2 relative to a predetermined reference plane parallel to the other surface, the minute regions δ 2 include a recessed portion receding below the other surface, the recessed portion having 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, and at least part of the raised portions and the recessed portions has a micro periodic structure that is formed by indentations and projections.