| 摘要 |
PROBLEM TO BE SOLVED: To provide a back light capable of improving luminance while thinning the thickness of a back light system. SOLUTION: This back light is provided with a prism sheet forming a prism string 10A on one face of a resin sheet and smoothing the other face and a scattering light transmission plate 12 obtained by dispersing a transparent dispersing material into transparent resin. A prism string (a vertical angle is 80 to 140 deg.) is formed on one side of the plate 12 in a direction rectangular to a light source 14 arranged on the side face part of the plate 12, the prism string is opposed to the prism string 10A (a vertical angle is 50 to 60 deg. and an angle formed by a normal from the vertical angle and a light source side prism surface is 10 to 30 deg.) of the sheet 10 and these prism strings are arranged so as to be orthogonally crossed to each other. |
