ILLUMINATOR, LIQUID CRYSTAL DISPLAY DEVICE USING THE ILLUMINATOR, PORTABLE TERMINAL EQUIPMENT, ON BOARD EQUIPMENT AND OPTICAL RECOGNITION DEVICE

摘要

PROBLEM TO BE SOLVED: To make a surface light source device thin in thickness and to improve optical coupling efficiency by consecutively forming a light source part in which a light emitting element is sealed and a light transmitting part of transparent resin material. SOLUTION: A light transmission plate 22 made of the transparent resin material such as methacrylic resin is constituted of the light source part 24 in which one or two or more light emitting elements 23 such as a light emitting diode are sealed, and the light transmitting part 26 in which light R outgoing from the light source part 24 is shut and which emits the light R from the light emitting surface 25 being an upper surface. A diffusing plate 30 disposed above the light transmission plate 22 is a sheet or a film made of synthetic resin, whose surface is worked to be finely rugged. The light emitted from the upper surface of the light transmitting surface 25 is diffused by the diffusing plate 30 so as to obtain nearly uniform luminance all over the light transmitting part 26. Since all the light emitted from the light emitting element 23 is emitted into the light transmission plate 22, the optical coupling efficiency and light utilization efficiency are enhanced.