| 摘要 |
PURPOSE:To improve the transmission factor of a transparent board while avoiding the cost increase. CONSTITUTION:A heat ray reflecting film 4 provided with a conducting selective transmission reflecting layer 9 made of a thin film of a metal and/or a metal oxide film and having the electric resistance inversely proportional to the transmission factor of the visible light is stuck all over the surface, the portion of the selective transmission reflecting layer 9 having the electric resistance inversely proportional to the transmission factor is used, and a transparent board 2 having a high transmission factor is provided with no cost increase. |
