Image forming apparatus with changeable toner returning electric field application period

摘要

An image forming apparatus includes an image bearing member; a charger for electrically charging the image bearing member; an electrostatic image forming device for forming an electrostatic image by selectively discharging a surface of the charged image bearing member; a developer for developing the electrostatic image formed on the image bearing member into a toner image; a transfer device for transferring the toner image from the image bearing member onto a transfer material; wherein the charger is capable of collecting residual toner from the image bearing member after an image transfer operation; an electric field forming device forms an electric field between the charger and the image bearing member to transfer the toner in the charger to the image bearing member; and a controller controls a length of time during which the electric field forming device forms the electric field, wherein the controller controls the length of time substantially in accordance with wear of a surface of the image bearing member.