Light source device and crystal display device

摘要

A light source comprising sidelight type backlight light guide plate (L), wherein a transmittance angle dependent layer (T1) which transmits normally incident light and reflects obliquely incident light is disposed on one surface of the sidelight type backlight light guide plate (L), and a reflection plate (R) having a repetitive slope structure is disposed on the other surface of the sidelight type backlight light guide plate (L). The invention light source is less in absorption loss due to repetition of light reflection and the like.