Copying machine with electromechanical scavenger assembly and process

Claim 1

In an electrostatic copying apparatus comprising a continuous photoresponsive master, means for moving said master through a copying cycle comprising a charging station in which the photoresponsive surface of the master is provided with an electrostatic charge, an exposure station in which the charged surface is exposed to the light image of an imaged original sheet being copied, whereby the electrostatic charge is removed from said surface except in latent image areas exposed to the imaged areas of said original, a development station in which said latent image areas are developed by means of toner powder present in a two-component composition comprising said toner powder and magnetic carrier particles, and an image-transfer station in which said developed images are transferred to a copy sheet and fused thereon, the improvement which comprises a non-magnetic shield having a collection surface which is positioned parallel to and across the path of the master and uniformly closely-spaced from the toner-imaged surface of said master, said shield being located beyond said development station and in advance of said transfer station, a magnet assembly pivotally attached to the apparatus and comprising a magnet which is movable between working and retracted positions, means for pivoting said magnet assembly to move said magnet into working position behind said shield to create a sufficient magnetic field through said shield to attract any magnetic carrier particles which may be present on the surface of said photoresponsive master from said master to the adjacent collection surface of said shield, and means for pivoting said magnet assembly into retracted position to move said magnet away from said shield to remove said magnetic field from said shield sufficiently to cause said magnetic particles to be released from the collection surface of the shield.