US Patent 7313335 Image forming apparatus with variably controlled bias condition

An image forming apparatus having an image bearing member rotatable and bearing a toner image thereon, a transferring apparatus for electrostatically transferring the toner image borne on the image bearing member to a recording material, a cleaning apparatus for electrostatically removing any toner not transferred to the recording material by the transferring apparatus but residual on the image bearing member from the image bearing member, a bias applying apparatus for applying a bias to the cleaning apparatus, and a controlling apparatus for variably controlling the bias condition of the bias applied to the cleaning apparatus by the bias applying apparatus, in accordance with the type of the recording material.