Patent ID: 8639167

Claim:
A two-component developing device which is capable of forming a toner image by developing an electrostatic latent image formed on an electrostatic latent image carrier with a developer containing toner and magnetic carrier particles, the two-component developing device comprising a development housing for containing the developer, a developing roller which is provided on the development housing and can be rotationally driven, a magnetic field generator mounted inside the developing roller and having a plurality of magnetic poles for attracting the developer used for development in the development housing onto a surface of the developing roller and meanwhile for providing a low-magnetic force area where the developer returned into the development housing without being used in development in a state of being left attracted on the developing roller is separated from the developing roller, a developer restricting member which restricts an amount of the developer attracted onto the surface of the developing roller by the magnetic force of the magnetic field generator and transferred to an electrostatic latent image development area by rotation of the developing roller, the developer restricting member opposing the developing roller across a developer amount restricting clearance, the two-component developing device comprising a developer guide member disposed between the developing roller and an inner face of the development housing in an area upstream of the developer restricting member in a direction of rotation of the developing roller, the guide member providing a developer guide path for guiding the developer to a developer amount restricting clearance between itself and the developing roller, providing a developer circulation path for circulating the developer to an upstream end of the guide member in the direction of rotation of the developing roller between itself and the inner face of the development housing, and providing a communication path for bringing the developer guide path into communication with the developer circulation path at a downstream end portion of the guide member in the direction of rotation of the developing roller, and the upstream end of the guide member in the direction of rotation of the developing roller being positioned above a peak of a magnetic flux density of the magnetic pole of the magnetic field generator which is closest to the low-magnetic force area downstream of the low-magnetic force area or positioned upstream of such a position and downstream of the low-magnetic force area, the developer restricting member having a wall surface that extends along the direction of rotation of the developing roller in an area downstream of the communication path and upstream of the developer amount restricting area in a direction of rotation of the developing roller.