MAGNETIC BRUSH TYPE DEVELOPING APPARATUS

摘要

A developing apparatus includes a cylindrical drum having a photosensitive layer provided around the outer peripheral surface thereof, and a magnetic roller mounted within a receptacle and having permanent magnets oriented in a body thereof and a rotating cylindrical sleeve provided on the outer peripheral surface of the body thereof. The receptacle holds a developer mixture including powdered iron and toner and it is opened to provide a magnetic brush exposure window where the magnetic roller and cylindrical drum face each other with a gap left therebetween. The magnetic roller continuously supplies the developer mixture in the form of a magnetic brush toward the gap between the magnetic roller and the cylindrical drum. A doctor blade is attached to the lowest edge portion of the exposure window to restrict the thickness of the magnetic brush. A magnetic piece is attached to the outer surface of the doctor blade and attracts the powdered iron in the magnetic brush thereto due to a magnetic field created between the permanent magnet in the magnetic roller and the magnetic piece, thereby providing an iron powder curtain between the magnetic brush and the magnetic piece. The curtain serves to prevent the developer mixture from flying of onto the photosensitive layer on the cylindrical drum and to permit the toner powder in the developer mixture to be effectively charged through a frictional contact with the curtain.