PROBLEM TO BE SOLVED: To precisely detect the life span of a photoreceptor drum in a process cartridge for which an AC voltage and a DC voltage are together used as charging means and for which contact charging at a plurality of operation speeds under a plurality of charging conditions is employed during image formation. ;SOLUTION: Based on the operation speed Vm (m≥2) and under bias voltage application conditions n (n≥1), the period tmn during which voltage is applied to a primary charging apparatus is detected, the damage index D of an image carrier is calculated from the detected time tmn and the coefficient kmn based on the following equation: D=k11×t11+k21×t21...kmn, the damage index D of the image carrier is integrated, the integrated value S is compared with a prescribed life information R, and the termination of the image carrier is alarmed or displayed to a user in the case that the integrated value S calculated by integration of image carrier damage is higher than the prescribed life information R of the image carrier based on the result of the comparison.;COPYRIGHT: (C)1999,JPO
展开▼
