| 摘要 |
PURPOSE:To enable to have effective surge absorbing function, to reduce the cost and to protect a CdS photoconductive cell from a lighting surge voltage by forming a CdS photoconductive layer on the surface of an insulating substrate and a pair of electrodes which energize the CdS photoconductive layer, forming a pair of discharging electrodes for energizing the electrodes on the back surface, and forming a discharging gap between the pair of discharging electrodes. CONSTITUTION:A pair of electrodes 6 and a CdS photoconductive layer 7 are formed on the surface of an insulator 9 such as a ceramic. A discharging gap 12 is formed between a pair of discharging electrodes 11 formed on the back surface of the insulator 9. A terminal 13 for energizing the electrodes 6, the layer 7 and the electrodes 11, a CdS photoconductive cell 14 formed of the electrodes 6 and the layer 7, and a discharger 15 formed of the electrodes 11 and the gap 12 are provided. When a lightning surge voltage is applied to the CdS photoconductive cell, the discharger is previously discharged from the CdS photoconductive cell 14, thereby protecting the cell 14. |
