LIGHT TRANSMISSION PLATE COMPOSED OF TRANSPARENT RESIN, METHOD FOR MOLDING THE SAME, BUSHING, METALLIC MOLD ASSEMBLING BODY AND SURFACE LIGHT SOURCE DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a bushing for injection molding of a polycarbonate resin light transmission plate having a prism shaped projecting and recessed part formed on a surface thereof. SOLUTION: The bushing 20 is disposed in metallic molds 10, 11, constitutes a part of a cavity 12 provided in the metallic molds and is constructed with a bushing main body 21 composed of zirconia ceramics or conductive zirconia ceramics and a metal layer 22 formed on a surface of the bushing main body 21 opposite to the cavity 12 with a recessed part 23 arranged thereon for the purpose of forming the recessed part of the light transmission plate.