Loading patent…
AssigneeOce-van der Grinten N.V.
InventorsMathias J. J. M. Vola, Gerardus A. J. Koeleman, Franciscus M. J. Peeters
Estimating the term…
An improved apparatus is provided for developing an electrostatic charge image on a support being moved through a magnetic brush-forming field between a permanent magnet and a rotating cylinder that transports a powder mixture of toner particles and magnetizable carrier particles into said field from a supply of the mixture held in a tray. A wall of the tray bordering the path of the mixture on the cylinder is formed with an edge over which an excess of powder escapes instead of accumulating objectionably in a region between the support and the cylinder. As toner becomes deficient in the tray it is replenished by fresh powder mixture properly proportioned for use, which mixture is supplied into a shorter part of a trough that also receives the powder returned down the cylinder from the magnetic brush region. Screw conveyor means in this trough move its contents to an off-center opening therein from which mixed toner and carrier particles fall and are guided toward the center of the tray so as to be mixed with the material in the tray by especially formed mixing elements rotating therein. Further intensive mixing is assured by subjecting the mixture passing from the tray to the field of a permanent magnet mounted outside the tray in closely spaced relation to a lower portion of the surface of the cylinder. A central mixing element carries a brush for sweeping a window in the tray bottom through which the toner concentration is optically scanned. The rotary mixing elements have shafts mounted in powder shedding roller bearing bushings fitted into the side walls of the tray.
In apparatus for developing an electrostatic charge image on a support by applying thereto a powder mixture of magnetizable carrier particles and toner particles, comprising a tray for holding a quantity of said mixture, said tray having a bottom wall, two side walls, a front wall and a rear wall, magnetic brush forming means including a cylinder mounted for rotation between said side walls in bearings thereon near said rear wall and a permanent magnet disposed above said cylinder, means for transporting said support over said cylinder through a magnetic field between said cylinder and said magnet, at least two mixing elements mounted for rotation between said side walls in bearings thereon near said bottom wall, and means for replenishing a deficiency of toner particles in the powder mixture in the tray, the improvement which comprises said rear wall having an overflow edge over which an excess of powder approaching the apex of said cylinder will escape at a level between said apex and the axis of the cylinder, and said replenishing means comprising means for supplying a fresh mixture of magnetizable particles and toner particles for admixture with the mixture returning to said tray from said magnetic field and the mixture in said tray.
Dependencies are inferred from the claim text.