Electrophotographic cleaning apparatus

Claim 1

A magnetic brush apparatus for cleaning the photoreceptor in an electrostatographic copying machine comprising a magnetic brush roll positioned at an elevated location from the area of the photoreceptor to be cleaned by the brush, a plurality of magnet means located inside said magnetic brush roll, a reservoir for carrier particles, pickoff means for removing a part of the carrier particles from said magnetic brush roll into said reservoir during rotation of said magnetic brush roll, and exit means at the lower end of said reservoir, whereby said reservoir, said pickoff means, said exit means and said magnet means cooperate during the operation of the apparatus to circulate the carrier particles between the magnetic brush roll and the reservoir so that a portion of the magnetic brush on the roll is continuously removed and reformed, said magnetic brush roll comprises an inner stationary support and an outer roll mounted for rotation, said magnet means being fixedly mounted on said inner support and said outer roll being concentric to said inner support so that magnetic brush formed of carrier particles is supported on the exterior cylindrical surface of the outer roll, said magnet means includes a first magnet means positioned near said pickoff means to assist in the partial removal of the magnetic brush during the operation of the apparatus, a second magnet means positioned near said exit means to assist in the reformation of the magnetic brush during the operation of the apparatus, and a third magnet means positioned between said first and second magnet means, said second and third magnet means include magnetic field shunting means to prevent the magnetic fields from said second and third magnet means for interfering with the flow of the carrier particles in said reservoir.