| 摘要 |
PROBLEM TO BE SOLVED: To execute image forming by which proper density is obtained even in the case that endurance is deteriorated due to a long service. SOLUTION: The predicted characteristics of the Vd of each developing unit (a relation between a laser beam emitted light quantity set value and photoreceptive drum surface potential) is calculated (S1). A difference ΔVcont between a developing unit whose operation is set for Vcont and the other developing unit is obtained for each color (S2), and also dark decay increase δVcont is obtained for each color (S3). The laser beam emitted light quantity set value satisfying the difference (ΔVcont+δVcont) between the setting Vcont and the dark decay increase is obtained from the predicted characteristics obtained by S1 (S4). A maximum laser beam emitted light quantity set value (PWM width set value) to attain the setting Vcont of each color is calculated (S5). Thus, stabilized density is always outputted though a dark decay quantity due to endurance fluctuation is increased. |
