PRISM SHEET HAVING PRISM PEAK WITH LONGITUDINAL WAVE PATTERN IMPROVED IN FRONT LUMINANCE, BACKLIGHT UNIT ADOPTING THE SAME, AND LIQUID CRYSTAL DISPLAY DEVICE HAVING SAID BACKLIGHT UNIT

摘要

PROBLEM TO BE SOLVED: To provide a prism sheet having a prism peak with a longitudinal wave pattern, a backlight unit adopting the same, and a liquid crystal display device having the backlight unit.SOLUTION: The prism sheet comprises a transparent substrate 25a and prism peaks 25b of longitudinal wave pattern which is disposed on the transparent substrate 25a. The longitudinal wave pattern is shaped such that the height of the prism peaks 25b varies continuously or discontinuously in the longitudinal direction. The repetition cycle of the longitudinal wave pattern in the longitudinal direction is 50-100 times the average height of the prism peaks 25b. A prism peak 25b and its neighboring prism peaks have the same phase and repetition cycle.