| 摘要 |
PURPOSE:To hold the quality of printed matter constant and to improve its reliability by setting the permissible output range of a sensor, comparing the set value with the output value of the sensor, and stopping printing operation when the sensor output exceeds the permissible output range. CONSTITUTION:When the photosensitive layer of a photosensitive body 1 is made of selenium alloy, the photosensitive layer is charged positively by a main charger 2. In this invention, the permissible output range of the sensor 13 is set and a monitoring circuit 16 is provided to compare the output value of the sensor with the set value and to generate a command for stopping printing operation when the sensor output exceeds the set permissible output range. Consequently, the quality of printed matter is held constant and its reliability is improved. |
