Photocopying – Contact printing – Light boxes
Patent
1991-12-30
1994-01-18
Picard, Leo P.
Photocopying
Contact printing
Light boxes
118658, 355253, 430122, G03G 1509
Patent
active
052803236
ABSTRACT:
An electrophotographic printing machine in which an electrostatic latent image is recorded on a photoconductive surface by charging the appropriate areas of the surface to predetermined polarities. The latent image is a developed with toners of a preselected color and predetermined polarity by a developer unit. The developer unit includes a bead removal device which magnetically attracts carrier beads off the photoconductive surface and deposits these beads in a sump or reservoir of developer. The bead removal device includes a magnet and magnetic field shapers to enhance the magnetic fields which attract the beads in the zone between the surface and the bead removal device and attenuates the magnetic fields in the zone between the bead removal device and the sump or reservoir to reduce the attraction between the beads and the bead removal device in this zone. The invention also provides magnetic brush rollers for the delivery of toner to the photoconductive surface which have magnetic field shapers which attenuate the magnetic fields to encourage bead release from the roller and reduce attraction of beads to the roller in reverse rotation of the roller.
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Alvarez Jorge A.
Denton Gary A.
McGuire Peter J.
Zirilli Francisco
Horgan Christopher
Picard Leo P.
Xerox Corporation
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