| 摘要 |
PURPOSE:To prevent the deterioration in the performance of a photosensitive body and to announce quickly abnormality by measuring the electrifying potential on a photosensitive body, controlling the electrifying potential to attain a prescribed value and generating an error signal when the electrifying potential exceeds a threshold value or fails to attain the prescribed value within the prescribed time. CONSTITUTION:The detection signals for the electrifying potential on a photosensitive drum 26 from surface potential sensors 51-53 are inputted via amplifier circuits 97-99, AD converters 100-102 and I/O port 95 to a CPU96. The output value subjected to the correction occurring in the difference between the input potential and the target valueof the electrifying potential by the CPU96 is fed via DA converters 103-105 to high voltage generating circuits 106-108 by which the electrifying potential is so controlled as to attain the target electrifying potential. An error signal is generated when the electrifying potential inputted to the CPU96 exceeds the threshold value or fails to attain the prescribed value within the prescribed time. The deterioration of the photosensitive body is thus prevented and the abnormality is quickly detected. |
