Field effect toning method

• Main Author: CHRISTY; ORRIN D
• Format: Patent
• Language: English
• Published: 28.04.1998
• Edition: 6
• Subjects: CINEMATOGRAPHY; CORRECTION OF TYPOGRAPHICAL ERRORS; ELECTROGRAPHY; ELECTROPHOTOGRAPHY; HOLOGRAPHY; i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; LINING MACHINES; MAGNETOGRAPHY; PERFORMING OPERATIONS; PHOTOGRAPHY; PHYSICS; PRINTING; SELECTIVE PRINTING MECHANISMS; STAMPS; TRANSPORTING; TYPEWRITERS

A method and apparatus are provided for "field effect imaging" of moving substrates, such as webs of paper. Non-conductive, non-magnetic toner having approximately a 5-20 micron mean particle size is electrically charged to a level of at least about 8 micro Coulombs/gram and then a first roller with a conductive surface is brought into operative association with the electrically charged toner so that toner particles adhere to the surface. The toner particles are preferably maintained in an electrostatic fluidized bed, and charged by a corona element in the bed. An array of pin or stylus primary electrodes are selectively energized or de-energized to provide no-write or write condition, respectively using a computer to switch the electrodes into or out of operative connection to a source of electrical potential. The toner particles are transferred from the first roller to a substrate either directly (after passing past the primary electrodes), or they are first transferred to a second roller which then brings the toner particles into contact with the substrate. If a second roller is utilized, the primary electrodes can be in association with the first roller, or between the first and second rollers for transferring only "write" toner to the second roller.