Patent ID: 8628231

Claim:
A display apparatus comprising: a display panel; a plurality of light sources disposed below the display panel to emit light; and a diffusion plate disposed between the display panel and the plurality of light sources to diffuse the light, the diffusion plate comprising a base having a top surface and a bottom surface, and a plurality of parallel convex ridges formed on the top surface of the base, wherein a planar section of each convex ridge perpendicular to the top surface of the base has an elliptically shaped arc segment, wherein a shape of the elliptically arc segment is described by a chord linking both ends of the arc segment, wherein the ellipse satisfies Ax 2 + By 2 + ∑ n = 0 2 ⁢ C n ⁢ x n + D = 0 wherein, A, B and D are coefficients, C 0 is a non-zero constant having a predetermined value, C 1 is zero, and C 2 is C 0 /p 2 wherein p is a length of the chord, wherein concave sections satisfying the above equation are formed on a second roller of a multi-roller apparatus by predicting a compressibility of a polymer resin used to fabricate the diffusion plate, an ideal elliptic equation is adjusted to reflect the compressibility of the polymer resin, and C 0 is determined to represent an actual shape of the planar section of each convex ridge.