BACK LIGHT UNIT AND BACK LIGHT, AND MANUFACTURING DEVICE FOR LIGHT GUIDE PLATE

摘要

PROBLEM TO BE SOLVED: To provide a back light unit which has uniform luminance on its light emission surface and the back light. SOLUTION: A light guide plate 1 is wedgelike in a section crossing a guide-in surface 11 and tapered in end areas 1b and 1b in the width direction of the light guide plate 1 by slanting a reflecting surface 13 so that the thickness is gradually thinner than in a center area 1a. Illumination light from a linear light source is guided in from the guide-in surface 11 and travels in the light guide plate 1 while reflected by a reflecting surface 13 and a reflecting plate 21 to exit from a light emission surface 13. The thickness of the end areas 1b and 1b is less on the side of the light guide surface 11 of the light guide plate 1 than in the center area 1a, so the emissivity of light becomes larger than in the center area 1a to prevent unevenness in luminance due to the size error between the linear light source and guide-in surface 11.