Patent ID: 7849022

Claim:
An optical functional sheet, comprising: a base, and prisms arranged in a lattice pattern on at least one surface of the base, wherein each of the prisms has two bottoms L 1 parallel to a first direction, two first inclined surfaces that are inclined so as to face each other, two bottoms L 2 parallel to a second direction that is substantially perpendicular to the first direction, and two second inclined surfaces that are inclined so as to face each other, and the area of one of the second inclined surfaces is more than 0.5 times to 2.5 times or less the sum of the areas of the two first inclined surfaces, and wherein any of the two first inclined surfaces and the two second inclined surfaces are respectively formed in a trapezoidal shape, sharing one upper bottom thereof, and the two inclined surfaces other than those formed in a trapezoidal shape are respectively formed in a triangular shape.