Patent ID: 8622602

Claim:
A light guide plate comprising: a rectangular light exit surface; at least one light incidence surface which is provided on at least one end side of said light exit surface and through which light enters; a rear surface on an opposite side from said light exit surface; and scattering particles dispersed in said light guide plate, wherein said light guide plate includes two or more layers superposed on each other in a direction substantially perpendicular to said light exit surface and containing said scattering particles at different particle concentrations, wherein said two or more layers include a first layer disposed on a side closer to said light exit surface and a second layer disposed on a side closer to said rear surface than said first layer and Npo and Npr satisfy a relationship expressed by Npr>Npo where Npo represents a particle concentration of said first layer and Npr represents a particle concentration of said second layer, wherein thicknesses of said first and second layers in the direction substantially perpendicular to said light exit surface change so that a combined particle concentration of said light guide plate has, in a direction perpendicular to said at least one light incidence surface, a first local maximum value on at least one side closer to said at least one light incidence surface and a second local maximum value located at a position farther from said at least one light incidence surface than at least one position of said first local maximum value and being larger than said first local maximum value, whereupon the thickness of said second layer continuously changes so that the second layer increases in thickness with increasing distance from said at least one light incidence surface, then decreases in thickness and subsequently increases in thickness again, and wherein an interface between said first layer and said second layer in a region corresponding to an area from the at least one position of said first local maximum value to a position of said second local maximum value includes at least one curved surface concave toward said light exit surface on at least one side on which the combined particle concentration takes said first local maximum value, and a curved surface smoothly connected to said at least one concave curved surface and convex toward said light exit surface on a side on which the combined particle concentration takes said second local maximum value such that said combined particle concentration smoothly changes from the at least one position of said first local maximum value to the position of said second local maximum value.