| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that nonuniformity of brightness occurs when strong force is applied on the tip parts of crests forming the lenses of a prism sheet to cause the crushing of the tip parts and change in the refraction because the crest portions rise steeply, and thereby, to realize a prism sheet having high front brightness and high mechanical strength. SOLUTION: In order to solve the problem, the pitch P with a prism shape is set to be 60 μm or less, and the valley side shape is made to have a triangular shape. The apical angle θT of the valley side is 45 to 110 deg., and the crest side shape is made to have a trapezoidal shape having a plane shape nearly parallel to the surface of a liquid crystal display body. When the height of the trapezoidal top side from the bottom of the valley is Ha and the height of the virtual intersection of the slopes of sides forming adjacent valleys from the bottom of the valley is represented by Hb, the Ha is set to satisfy Ha=1/2×Hb or larger. Thereby, the prism sheet which is excellent in durability and has high front brilliance is realized. |
