Patent ID: 7883254

Claim:
A light guide plate for an edge-light surface illuminant device, comprising: an emission plane; a bottom plane facing the emission plane; and an incident end face which enters light emitted from a primary light source provided at least in one side face, wherein the emission plane comprises a pattern having convex portions and concave portions formed at predetermined pitches; the bottom plane comprises the pattern having the convex portions and/or the concave portions formed at predetermined pitches; the pattern formed on the emission plane is orthogonal to the incident end face and the pattern formed on the bottom plane is parallel to the incident end face; in the emission plane, in order to increase a viewing angle without reducing brightness in a vertical direction, each of the convex portions comprises a trapezoidal shape and each of the concave portions comprises a trapezoidal shape, and each of the convex portions having the trapezoidal shape and each of the concave portions having the trapezoidal shape are alternately arranged; an inclined angle between an inclined face of the trapezoidal convex portion and the trapezoidal concave portion and the emission plane is within a range of 30°-60°; and the incident end face is provided in one side face or in opposing side faces.