US Patent 7684118 Diffusion plate and diffusion plate assembly

A diffusion plate assembly includes a diffusion plate made from transparent material. Pluralities of bar-type patterns are disposed on the emission surface of the diffusion plate. The outline of these patterns has a first curve and a second curve. The protruding direction of the first curve and the second curve are inversed. The second curve is an arc whose radius curvature is between 0.05 mm and 0.3 mm.