Light pipe, surface light source device and reflection type liquid-crystal display device

摘要

A light pipe in which light incident on an incident side surface (13) is outputted from a lower surface (12) through a light output means formed on an upper surface (11), the direction of the largest intensity of the light outputted from the lower surface is within an angle of 30 degrees to a normal line with respect to a reference plane of the lower surface, the largest intensity of light leaking from the upper surface in the direction within the angle of 30 degrees is not higher than 1/5 as high as the largest intensity at the lower surface, and the light pipe has a hard coat layer-on the upper surface so that light incident on the lower surface is transmitted from the upper surface; a surface light source device having a light source disposed on the incident side surface of the light pipe; and a reflection type liquid-crystal display device having a liquid-crystal cell provided with a reflection layer disposed on the lower surface side of the surface light source.