Patent ID: 7237930

Claim:
A light diffusion plate comprising: a light control member having two approximately parallel principal planes, one of the principal planes is an incident plane receiving light and the other of the principal planes is an exit plane emitting light; a plurality of convex structures periodically formed on the incident plane of the light control member such that a border line including a top of the convex structures and cut by a plane perpendicular to the incident plane in a predetermined direction has two straight lines which cross at an acute angle θ 1 ′ more than an angle (Π/9) (radian) on the top or an incident side of the top; and the light control member having a total light transmittance of more than 50% when light is incident at a predetermined angle α from a direction normal to the incident plane and achieves 1.05–3 times more total light transmittance than when the light is from the direction normal to the incident plane.