Charging device and image forming apparatus having same

摘要

A charging device includes a contact member contactable to a member to be charged; and a voltage applying device for applying to the contact member a voltage having a level which periodically changes, to charge the member to be charged; wherein the voltage applying device constant-voltage-controls the contact member in a first period and constant-current-controls the contact member in a second period, wherein a voltage level in the first period is determined in the second period.