| 摘要 |
PURPOSE:To provide a copying machine capable of obtaining a proper image density even if a developer is deteriorated. CONSTITUTION:The set value of a developing potential at the time of forming a reference image for detecting a P-sensor is switched based on the result of the comparison of target value Vref of a T-sensor 93 with its threshold. The developing potential can be switched when the target value Vref consecutively becomes the threshold or above several times or after the number of copies from the point of time that the target value Vref becomes the threshold or above exceeds a prescribed number. Further, the threshold can be changed over whenever the number of copies is increased by a prescribed number, or the threshold can be set when the developing potential can not be or can be switched by a prescribed umber of times. Moreover, control for correcting the voltage of an exposing lamp 3 and the conditions of the electrification and developing bias of an electrifier 8 can be changed over every time the developing potential is switched over. |
