LENS SHEET, SURFACE LIGHT SOURCE AND DISPLAY DEVICE

摘要

PURPOSE: To eliminate oblique unnecessary light without decreasing normal luminance by making the angle that two surfaces on the side in contact with the translucent base material of a unit pentagonal prism contain acuter than the angle that two surfaces on the noncontact side of the translucent base material contain. CONSTITUTION: The lens sheet 1 has unit pentagonal prisms 10 formed projecting on a light projection side and the sectional shapes in one or two orthogonal direction are pentagonal. Of each unit pentagonal prism 10, the angleθa that the two surfaces (steeply slanting surface) 12 and 13 on the base side (side in contact with the translucent base material) is acuter than the angleθa ' that the two surfaces (gently slanting surfaces) 14 and 15 on the vertex side (side not in contact with the light-transmissive base material) (θa '>θa ). Here,θ2 <θ1 holds, whereθ1 andθ2 are the angles of the steeply slanting surfaces 12 and 13, and gently slanting surfaces 14 and 15 to a base 11. The steeply slanting surfaces 12 and 13 function to increase the luminance and the gently slanting surfaces 14 and 15 function to suppress a side lobe.