Image forming apparatus with precharger

摘要

An image forming apparatus includes a photoreceptor, and a developing unit arranged in the vicinity of the photoreceptor. At an upstream side from the developing unit, a precharger is provided in a manner that the same is brought into contact with a surface of the photoreceptor. A developing bias voltage is applied to a developing sleeve, and a charging voltage is applied to the precharger. After the photoreceptor is charged by the precharger, the surface of the photoreceptor is brought into contact with a magnetic brush formed by a developing agent in which an insulative toner and a semiconductive magnetic carrier is mixed, whereby the photoreceptor is charged again by the developing bias voltage through the semiconductive magnetic carrier.