The optical convergence sheet, to be provided in

摘要

PPROBLEM TO BE SOLVED: To provide a light convergence sheet and a surface light source device capable of performing uniform lighting without unevenness irrespective of the position of observing a screen. PSOLUTION: A low refractive index layer having a refractive index lower than that of a high refractive index layer 144 is formed on an emission side of a unit lens 141. The thickness (t) of the low refractive index layer 142 satisfies 1/3×P≤t≤2×P, where P is the lens pitch of the unit lens 141. The refractive index of the low refractive index layer 142 is within a range of 0.95 to 0.99 times the refractive index of the high refractive index layer 144. PCOPYRIGHT: (C)2007,JPO&INPIT