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