OPTICAL ELEMENT, PLANAR ILLUMINATION APPARATUS AND DISPLAY APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide an optical element having substantially high condensing characteristics. SOLUTION: The optical element is transparent and has a light incident surface 11 and a plurality of projections 13 which are disposed in the opposite side to the light incident surface 11 by rendering the light incident surface 11 as the reference. Each projection 13 is in the form of a regular quadrangular pyramid having the bottom face disposed on a plane almost parallel to the light incident surface. The angle of the inclined face constituting the regular quadrangular pyramid is controlled to be in one of the following ranges (1) to (3) with respect to the normal line of the light entering surface 11. They are: (1) over 35°and not more than 55°; (2) over 40°and not more than 50°; and (3) over 40°and not more than 47.5°. COPYRIGHT: (C)2005,JPO&NCIPI