| 摘要 |
PURPOSE:To correct the surface potential of a photosensitive body with high precision and to obtain stable images continuously by controlling the quantity of electrostatic charging on the basis of the quantity of variation in the surface potential of the photosensitive body calculated from the histories of the total amount of passing charges of the photosensitive body and a no-charge passing time. CONSTITUTION:When the photosensitive body 1 is not powered on, a timer counter 20 counts the charge fatigue recovery time T2 of the photosensitive body 1. Then, CS 7 turns on when electric power is supplied to load data on the time T2 and an electrostatic capacity value stored in an NRAM 19 to a CPU 16, thereby calculating the amount of passing charges of the photosensitive body 1, the electrostatic capacity of the photosensitive body 1 in copying operation, and the quantity DELTAV of variation in the surface potential of the photosensitive body 1. The quantity DELTAIc of variation by which a current Ic flowing to the photosensitive body 1 is varied is calculated by the CPU 16 so as to correct said quantity DELTAV of variation, and a signal for varying the current Ic is sent to the CS 7, which varies the output to an electrostatic charger 2 according to the sent signal. Consequently, the surface potential of the photosensitive body 1 is corrected with high precision to obtain stable images continuously. |
