AC Corona to remove background from the transfer member of a thermomagnetic copier
AssigneeE. I. Du Pont de Nemours and Company
InventorsDonald W. Edwards, Emery J. Gorondy, Arend Van Roggen
Life of this patent
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Abstract
A process for reproducing graphic information wherein a magnetic image is formed in a premagnetized layer of acicular chromium dioxide by heating the chromium dioxide selectively to above its Curie point. Ferromagnetic toner particles are then applied uniformly to the chromium dioxide layer, so as to adhere only in the magnetized areas. The toner particles are electrostatically transferred to a substrate and fused into position. Alternating current coronas or other static neutralizing devices are used to neutralize unwanted charges on toner particles which would otherwise cause fuzzy images and unwanted background markings on the final copies.
Claims7
An apparatus for applying uncharged ferromagnetic toner particles to selected areas of a substrate comprising a movable layer of electrically grounded selectively magnetized ferromagnetic particles, drive means to advance said layer, means for applying nonconductive ferromagnetic toner particles to said layer, means for removing the nonconductive ferromagnetic toner particles from areas of said layer not selectively magnetized, means to bring a substrate into superposed position against said layer, means for applying an electric field to the substrate while it is superposed against the layer, means for removing said substrate from said layer, and a static neutralizing device adapted to neutralize any charges on any particles left adhering to said layer after said substrate has been removed from superposed position thereagainst.
Dependencies are inferred from the claim text.