Magnetic brush developer equipped with self-metering controls

Claim 1

In a magnetic brush developing device adapted to have a controlled height of brush formation including a source supply of pulverulent developer mix made up of magnetically attractable carrier particles and toner particles, comprising: a rotatably mounted metering drum partially immersed in said source supply, said metering drum having formed on its outer surface means for attracting and holding thereon a predetermined capacity for carrying measured quantities of said developer mix; magnetic brush developer means comprising a plurality of rotatably mounted tubular structures in parallel axial alignment with one another forming a lower reach and upper reach respectively along the underside and upper surface of said tubular structures, and said tubular structures having magnetic flux generating means disposed therein so as to form a flux field along said lower and upper reaches of said tubular structures establishing a fixed stream path for said developer mix having a starting point and a termination point, said metering drum being positioned adjacent said lower reach defining the starting point of said stream path and said magnetic flux means within said tubular structures effective to move the developer mix along said lower reach from said starting point and along said upper reach and to form a terminating point for said stream path at the end of said upper reach so as to bring said measured quantities of developer mix within the flux field thereby establishing a developer brush of a predetermined height, said developer mix being returned to the source supply at said terminating point.