MAGNETIC TONER POWDER APPLICATOR

摘要

A device for applying magnetic toner powder from an outer layer of a roller sleeve across a gap to a transfer sheet in response to a discrete external magnetic field pattern provided by a master source document. The device includes a magnetic field source non-rotatively positioned within the roller sleeve for providing a magnetic bias field extending over a sector of the sleeve to interact with the external magnetic field pattern to produce on the transfer sheet a toner powder reproduction of the field pattern, and another magnetic field source for providing a magnetic field for removing excess toner powder from the outer layer of the roller sleeve to enable a uniform distribution of toner powder to remain on the sleeve, the powder distribution when adjacent to background areas of the external field pattern within the sector being less than the distance across the gap.