| 摘要 |
PURPOSE:To obtain an overheat preventing device for a copying machine which operates securely and correctly, by turning off a lamp for exposure in a prescribed time by the electromotive force of a solar battery which receives light from the lamp for exposure. CONSTITUTION:A breaking circuit 15 is connected in series to the connection circuit of a halogen lamp 9 and a power source 14. This breaking circuit 15 consists of a keep relay RA. Said power source 14 is controlled by a control circuit to drive and turn on the halogen lamp 9 during exposure through the normally closed contact RA-1 of the keep relay RA. If the halogen lamp 9 turns on abnormally owing to a fault, etc., of the control circuit, the solar battery 12 is irradiated with light from the light source 4 for exposure to generate electromotive force. The electromotive force of the solar battery 12 sets the keep relay RA, whose contact RA-1 is opened to turn off the halogen lamp 9. Therefore, an abnormal rise in the temperature of the platen glass is prevented and then the breaking of the platen glass and the burning of a platen cover are prevented. For resetting, a switch RA-2 is closed and the keep relay RA is only reset by a semiconductor controlling power source. |
