Toner unit for photoelectrostatic reproduction

Claim 1

Apparatus for applying toner to an electrostatic image carried by an insulating surface by contacting said surface with a magnetic brush of toner mix comprising toner particles and magnetic carrying particles, said apparatus comprising: A. a first magnetic brush unit having; 1. a moving surface, 2. means mounting said moving surface for advancing in a first direction along a path such that successive transverse portions of said moving surface move through a toner mix pickup region to a mixing zone, and 3. means for continuously successively forming and disrupting a magnetic brush of toner mix on said moving surface throughout substantially the entire path of movement of said moving surface from said toner mix pickup region to said mixing zone; B. means for applying toner mix to said moving surface at said toner mix pickup region; C. a second magnetic brush unit having; 1. a moving surface, 2. means mounting said moving surface of said second unit above the off-running side of a crest of the first magnetic brush unit for permitting successive transverse portions of the moving surface of said second unit to advance through a position closely spaced from the moving surface of said first unit in a second direction counter to said first direction to define said mixing zone in which toner mix is accumulated and circulated, and 3. means for transferring a portion of the toner mix carried by said first unit to said second unit at said mixing zone to form a magnetic brush on the moving surface of said second unit prior to application to said insulating surface.