Patent ID: 8899814

Claim:
An optical sheet comprising: a sheet-like body portion; and unit prisms arranged on one surface of the body portion in an arrangement direction and each extending linearly in a direction intersecting the arrangement direction; wherein each unit prism, when viewed in a direction parallel to the arrangement direction of the unit prisms, has an uneven polygonal-line-shaped contour, and wherein with reference to raised portions defined by the polygonal-line-shaped contour of each unit prism, a distance between a top of each raised portion, a farthest point from the body portion in the raised portion, and the body portion in a normal direction of the body portion is not constant; wherein the unit prisms include unit prism groups, wherein each unit prism group has at least two unit prisms arranged side by side in the arrangement direction, and wherein each of the unit prisms in each unit prism group have a different construction with respect to one another; wherein the unit prism groups are arranged side by side in the arrangement direction of the unit prisms and have the same construction; and wherein a cross-sectional shape of the at least two unit prisms forming one unit prism group, in a main cross-section parallel to both the normal direction of the body portion and the arrangement direction of the unit prisms and at one position in a longitudinal direction of the unit prisms, is identical to the cross-sectional shape of unit prisms the number of which is the same as the at least two unit prisms and which are arranged side by side in an area spanning the one unit prism group and an adjacent unit prism group, in the main cross-section and at a certain position at a distance from the one position in the longitudinal direction of the unit prisms.