| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a planar lighting system of a thin shape with a high light utilization factor, capable of irradiating light with little luminance unevenness and capable of obtaining a high-at-middle, or bell-shaped luminance distribution where a part of the screen near the center is brighter than a peripheral part as is required with a large-screen thin liquid crystal TV. <P>SOLUTION: Two symmetrical slanted rear faces in which distances from a light-irradiating face get farther toward a center of the light-irradiating face from two light-incident faces, and a curved part jointing the two slanted rear faces are provided, inside which, scattered particles scattering light propagated are included. A length between the two light-incident faces, a thickness of the light-incident face, a thickness of the center of the curved part, and a curvature radius of the curved part as well as a taper of the slanted faces satisfy a given range, and a particle size and a density of the scattered particles satisfy a given range, with a light-utilization factor of 55% or more, and a degree of height at middle of luminance distribution of the light-irradiating face of more than 0% and 25% or less. <P>COPYRIGHT: (C)2009,JPO&INPIT |
