Patent ID: 8099011

Claim:
An image forming apparatus comprising: an image bearing member arranged to bear an electrostatic latent image; a charging member contacting the image bearing member to charge a surface of the image bearing member with application of a DC voltage to the charging member; a current detection unit arranged to detect a DC current flowing in the charging member; and a control unit configured to control the voltage applied to the charging member, wherein a plurality of different voltages are applied during a period of no image formation until a difference in absolute value between a first amount and a second amount becomes not larger than a predetermined value, where In, In+1 and In+2 are DC currents detected by the current detection unit when a plurality of different voltages are applied to the charging member, the first amount is an amount of change in a current with respect to change in a voltage obtained from In and In+1, and the second amount is an amount of change in current with respect to change in voltage obtained from In+2 and In+1, and the control unit controls a DC voltage applied to the charging member during a period of image formation based on a result detected by the current detection unit during a period of no image formation.