TWI572911B

PURPOSE: A manufacturing method of light guide plates is provided to reduce the brightness smudge placing around a light incoming unit in which the light is incoming. CONSTITUTION: A light guide plate member(11) has four sides(S31-S34) intersecting in an exit side(S1), a rear side(S2) of an opposite side of the exit side, and the exit side and the rear side. The four sides S31~S34 are figured by orthogonally crossing the exit side and the rear side. In the rear side of the light guide plate member a plurality of light reflection dot(12) is formed. In order to exit the light of a uniform plane shape from the exit side efficiently, the light reflection dot is small in an incoming light unit side close to a light source(3) and gets bigger as the light reflection dot goes further from the light source. The light reflection dot is formed in a virtual grid regularly arranged in two dimension through a front side of the rear side.