Patent ID: 8040462

Claim:
A liquid crystal display device comprising: a line shaped light source; and an optical uniformity device comprising: a light deflection lens having a lens shape of a lenticular type, wherein, in planar view, an angle between a direction of a long axis of the light deflection lens and a direction of a long axis of the line shaped light source is equal to or less than 20 degrees; a light propagation layer located at a light outgoing surface side of the light deflection lens, wherein light deflected by the light deflection lens enters into the light propagation layer; and a light diffusion base arranged at the light outgoing surface side of the light propagation layer, wherein the light deflection lens comprises a top part and a slope part, where the slope part is from the top part onto a surface of the light propagation layer on a side of the line shaped light source, the top part comprises an arc or a tip that forms a ridge line of which a curvature radius is smaller than a curvature radius along the slope part, and a thickness T of the light propagation layer satisfies the following formula 1, and wherein n is the refractive index of the light propagation layer, P is the pitch of the light deflection lens, and θ is an angle between a tangential line to the slope part at a junction point to the light propagation layer, and the surface of the light propagation layer on the side of the line shaped light source T > P × tan ⁢ { Sin - 1 ⁡ ( 1 n ⁢ sin ⁢ ⁢ θ ) + Cos - 1 ⁡ ( sin ⁢ ⁢ θ ) } ⁢ ( 10 ⁢ ⁢ µ ⁢ m ≤ P ≤ 300 ⁢ ⁢ µm ) . ( formula ⁢ ⁢ 1 )