| 摘要 |
<p>An electrophotographic printing machine is provided with a photoreceptor drum (1) including a photosensitive layer (1a) formed on a surface of an electrically conductive base (16), a contact charger (9) in contact with the photosensitive layer (1a) for charging the photosensitive layer (1a) by applying thereto a DC voltage, and a voltage drop detecting circuit (40) for outputting a detecting signal when the voltage has dropped below a reference voltage. When a defect exists such as a pin hole on the photosensitive layer (1a), the voltage being applied to the photosensitive layer (1a) of the contact charger (9) drops. In this state, a detecting signal is output to a controller (21) from the voltage drop detecting circuit (40). When the controller (21) receives the detecting signal, the controller (21) signals to stop the operation of the entire device, and signals a display (36) to display a message indicating to exchange the photoreceptor drum (1), i.e. the image forming process will not be continued. Thus, the contact charger can be effectively prevented from breaking down. <IMAGE></p> |
