| 摘要 |
An object of the present invention is to provide an inexpensive planar light source device which is based on a novel, simply constructed illumination system that is superior in its efficiency of utilization of illumination light beams, uses a light reflection sheet that is a novel light guide pipe and novel light control member to thereby achieve effective utilization of light, and also, has a structure that is simple and superior in easiness of assembly; and the planar light source device is characterized in that: the device is chiefly composed of a light guide pipe 11 formed as a sheet made of transparent synthetic resin, and a light source 13 arranged in the vicinity of at least one side edge portion 12 of the light guide pipe 11; and when one surface of the light guide pipe 11 serves as a light radiation surface 15, with a structure of a light reflection sheet 18 arranged to an opposite surface 16 side from the light reflection sheet 15, a control is made such that a peak of a distribution of radiation angles in a right angle direction to the surface of the side edge portion 12 of the light guide pipe 11 to which the light source 13 is arranged is within a predetermined angle to a normal line (perpendicular line) 17 of the light radiation surface 15 and that a half-width of the distribution of radiation angles is within a predetermined angle, as regards light beams radiated out from the light radiation surface 15 of the light guide pipe 11 at the time when the light source 13 is lit up. <IMAGE> |
