Fresnel lens sheet for back face projection video display, has lens portion with concentric circular lenses each having ridge portion with flat surface having predetermined width

摘要

A Fresnel lens portion (13) has concentric circular lenses (11) formed in a same plane. Each lens has a ridge portion (11a) in which flat surface (12) is formed, such that the width of the flat surface decreases from the outer circumference (P) of the Fresnel lens portion to the center (O) of the lens portion. Each flat surface has a width in the range of 0-30 micrometers.