MAGNETIC BRUSH TYPE DEVELOPING APPARATUS

摘要

A developing apparatus for an electrostatic copying machine includes a cylindrical drum having a photosensitive layer provided around the outer peripheral surface thereof, and a magnetic roller mounted within a receptacle, having stationary magnetic poles arranged in a body thereof and a rotating cylindrical sleeve provided on the outer peripheral surface of the body thereof. The receptacle holds a developer capable of forming a magnetic brush and has a window to expose the magnetic brush so that it can contact the drum where the magnetic roller and the drum face each other with a narrow gap left therebetween. The magnetic roller continuously moves the developer in the form of a magnetic brush into 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 member has an extremity downstream of the doctor blade relative to the direction of movement of the brush and because of the magnetic field created between the magnetic poles in the magnetic roller and the magnetic member forms a developer curtain between the magnetic brush and the magnetic member. The curtain serves to prevent developer particles from flying off onto the photosensitive layer on the cylindrical drum and permits the developer particles to be effectively charged through frictional contact with the curtain.