Abstract: Method and means is disclosed for treating carrier particles in order to change the charge to mass ratio and the resistivity of a development powder encompassing such particles. The carrier particles are first coated with a polymer capable of providing reactive sites and then an additional treatment is carried out with a material that will react to the reactive sites. Another advantage of the treatment is that the carrier particles are protected from oxidation following such treatment.

Abstract: A top-of-stack sheet feeder includes a stack lifting apparatus which provides uniform stack pressure at the feeder as well as stack replenishment without interruption of feeder operation. The stack lifting apparatus includes a comblike feeding platform which incrementally elevates a feed stack to a feed roller which removes successive top sheets. Platform elevation control is responsive to requirement signals generated by a top sheet height sensor. When the stack is depleted to a predetermined reserve, a pair of opposed comblike feeding decks interfit between spaces in the feeding platform and assume the stack elevation function after which the platform descends to a loading station to receive a new stack and lift same to the decks. Upon introduction of the new stack, the decks disengage the reserve and index to a lower dwell station ready to again resume stack lifting when the combined stack reaches the reserve level.