Patent ID: 9690226
Date: 2017-06-27
CPC Classifications: G03G

Claim:
1. An image forming apparatus comprising: a rotatable image bearing member; a charging member disposed proximate or in contact with the image bearing member, the charging member charging the image bearing member by applying a voltage having superimposed an AC voltage and a DC voltage as a charging voltage during an image forming operation of forming an image on the image bearing member; an image forming unit configured to form an image on the image bearing member being charged by the charging member; a direct current detection unit configured to detect a direct current flowing from the charging member to the image bearing member when the charging voltage is applied to the charging member; and a control unit configured to selectively execute a first mode of setting a voltage having superimposed a first AC voltage and the predetermined DC voltage as the charging voltage during the image forming operation, the first AC voltage being set by applying a plurality of test AC voltages to the charging member during execution of the first mode, and a second mode of setting a voltage having superimposed a second AC voltage higher than the first AC voltage and the predetermined DC voltage as the charging voltage during the image forming operation, the second AC voltage being set by applying a plurality of test AC voltages to the charging member during execution of the second mode, the control unit applying the voltage having superimposed the first AC voltage and the predetermined DC voltage to the charging member, and detecting a direct current flowing from the charging member to the image bearing member via the direct current detection unit during execution of the first mode, and if an absolute value of the detected direct current is lower than a predetermined value, switching the first mode to the second mode and executing the second mode.