| 摘要 |
PURPOSE:To make it possible to obtain high efficiency of electric power consumption to brightness conversion and high brightness by arranging a sheet consisting of a light transmissive material having a shape satisfying specific conditions on the light exit surface side of the back light. CONSTITUTION:A light directional sheet 7 consisting of the light transmissive material has many straight peak ridges 8 or projecting peak ridges parallel with each other in parallel state at fine intervals on the same surface and is so arranged on the light exit surface side of the light transmission plate 1 that the peak ridge surfaces exists on an outer side (the side opposite to the surface facing the light transmission plate 1). This sheet is arranged on the light exit surface side of the light transmission plate 1 by forming an air layer via a light diffusion plate 2 or spacer element of a sheet consisting of a light transmissive material having a rough surface on the surface facing the light transmission plate 1. The directivity of the light emitted from the light exit surface of the back light is changed by arranging the sheet 7 having the peak ridges in such a manner, by which the directivity near the normal direction down to the light exit surface and the range where the contrast of the liquid crystal display device is good is made higher. |
