Developing device with microfields formed on developer carrier

Abstract

A developing device for an image forming apparatus and using a one component type developer. The developer is transferred from a developer supply member to a developer carrier which are so rotated as to move in the same direction at a position where they contact each other. This prevents the developer from a toner storing section from directly reaching part of the developer carrier having moved away from the contact position despite the movement of the developer supply member. Conductive portions connected to ground and dielectric portions each having a small area are distributed regularly or irregularly on the surface of the developer carrier. Such a surface of the developer carrier is charged by friction by the developer supply member with the result that a great number of microfields are formed in the vicinity of the developer carrier. The microfields allow only the developer sufficiently charged by friction at the contact position to form multiple layers on the surface of the developer carrier. Consequently, the toner with a desired amount of charge and containing a minimum of uncharged toner can form multiple layers on the developer carrier and is transferred to an image carrier.