Patent ID: 7866872

Claim:
A light guide plate comprising: a light exit plane being flat and rectangular; two light entrance planes respectively containing two opposite longer sides of said light exit plane and disposed opposite each other; two inclined rear planes being symmetrical and increasingly distanced from said light exit plane from said two light entrance planes toward a center of said light exit plane; a curved portion joining said two inclined rear planes; and scattering particles for scattering light travelling inside said light guide plate contained in said light guide plate, wherein a light guiding length between said two light entrance planes ranges from 480 mm to 500 mm both inclusive, wherein a particle diameter of said scattering particles ranges from 4.0 μm to 12.0 μm both inclusive and a particle density of said scattering particles ranges from 0.02 wt % to 0.22 wt % both inclusive; wherein said particle diameter and said particle density of said scattering particles are within an area determined by six points (4.0,0.02), (4.0,0.085), (7.0,0.03), (7.0,0.12), (12.0,0.06), and (12.0,0.22) in a graph where a horizontal axis indicates said particle diameter [μm] of said scattering particles and a vertical axis indicates said particle density [wt %] of said scattering particles; wherein a light use efficiency indicating a ratio of light emitted through said light exit plane to light admitted through said two light entrance planes is 55% or greater; and wherein a middle-high ratio represented by a brightness distribution at said light exit plane indicating a ratio of brightness of light emitted from an area about a center of said light exit plane to the brightness of light emitted at areas of said light exit plane close to said light entrance planes is above 0% and not greater than 25%.