| 摘要 |
PROBLEM TO BE SOLVED: To provide a light-transmitting plate which has neither local luminance unevenness nor luminance unevenness over the entire light emission surface and is uniform, thin, and large in area by arranging a pattern which projects primary light made incident on the light-transmitting plate efficiently from a projection surface and making the pattern fine. SOLUTION: This is a transparent light-transmitting plate 3 which guides light from at least one end surface and many projection patterns in a spot shape, a solid-line shape, or a broken-line shape of 10-200 in sectional width W(μm) in section crossing the axis of a linear light source are arranged on a light projecftion surface with low density nearby the primary light source and with high density at a distance from the light source so that the luminance distribution of projection light from the projection surface becomes nearly uniform. Here, when the section of the projection pattern is in almost in a trapezoidal shape having straight-line parts partially, the ratio H/W of the sectional width W of the projection body and the height H is preferably 0.2-1.0 and when the section of the projection pattern is nearly arcuate and the sectional width of the ratio H/W of the sectional width W of the projection body and the height H is preferably 0.2-0.5. |
