Patent ID: 6742921
Filing Date: 2004-06-01
Classification: G02B,G02F

Abstract:
A light pipe comprising:a plate-like member including light output means formed in an upper surface of said plate-like member so that light incident on an incidence side surface of said plate-like member is exited from a lower surface of said plate-like member through said light output means; an adhesive layer having a refractive index lower than that of said plate-like member; and an anti-reflection layer made of a circular polarizer and bonded to a lower surface of said plate-like member through said adhesive layer, wherein said light output means formed in said upper surface of said plate-like member is formed by a repetitive structure of prismatic structures each having an optical path changing face and a lone side face and arranged at intervals of a pitch of from 50 &mgr;m to 1.5 mm; each of said optical path changing faces is formed of a slope inclined downward from said incidence side surface to a counter end surface opposite thereto at an inclination angle in a range of from 35 to 48 degrees with respect to a reference plane of said lower surface of said plate-like member; each of said long side faces is made of a slope inclined at an angle in a range of from 0 to 10 degrees with respect to said reference plane; a difference between inclination angles of any two lone side faces is not larger than 5 degrees over a surface of said plate-like member; a difference between said inclination angles of adjacent ones of said long side faces is not larger than 1 degree; and a projected area of said lone side faces on said reference plane is not smaller than 5 times as large as that of said optical path changing faces on said reference plane.