| 摘要 |
PURPOSE:To obtain the titled panel which does not develop color under transmitted light and develops color under untransmitted direct light by sticking a color developing meterial which develops color under ultraviolet rays to one side or both sides of a (colored) transparent plastic plate absorbing ultraviolet rays. CONSTITUTION:A light transmiting material (e.g., polyvinylpyrrolidone) 4, 5 contg. a dispersed material (e.g., a stilbene fluorescent agent) which develops color under ultraviolet rays is applied to one side or both sides 2, 3 of a (colored) transparent plastic plate (e.g., a polycarbonate resin plate) 1 having 0.5-10mm. thickness and avsorbing ultraviolet rays having shorter wavelengths than 370nm. When one side of the plastic plate is irradiated with light contg. ultraviolet rays, only a developed color image of the color developing material stuck to the side can be observed from both sides, and when both sides are irradiated with light, colored images of the color developing material stuck to both sides can be observed. |
