Patent ID: 6839530

Claim:
An image forming apparatus comprising: an image bearing member; a charging roller cooperable with said image bearing member to form a nip therebetween, for charging said charging roller is rotatable for counterdirectional peripheral movement relative to said image bearing member at the nip; developing means for developing with a developer an electrostatic image formed on said image bearing member; wherein a potential of a potential changing portion of said image bearing member changes with respect to a peripheral moving direction of said image bearing member, wherein at tA (sec) after arrival, at an upstream end of said nip, of said potential changing portion, said developing means is supplied with a voltage for collecting particles from said image bearing member to said developing means, where tA (sec) is a sum of a time duration required for a surface of said charging roller to move from the upstream end of said nip to a downstream end of said nip and a time duration required for a surface of said image bearing member to move from the downstream end of said nip to a developing zone of said developing means.