Xerox 2121L - FaxCentre B/W Laser, Service Manual

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General Procedures and Information
FaxCentre 2121/2121L 11/06 6-59
Figure 7
Development System
• The toner agitating screw conveys toner in the toner cartridge onto the toner supply roller.
• The toner supply roller transports the toner to the sleeve roller.
• The 1st toner blade located above the sleeve roller spreads a thin, even coat of toner over the
sleeve roller.
• A negative charge is applied to the 2nd toner blade, which negatively charges the toner.
• The sleeve roller is negatively charged, which retains the toner there on.
• The toner transfers to the area on the surface of the drum that has been exposed to the laser
beam.
• The Bias Seal on the underside of the sleeve roller separates toner, which has not been
attracted onto the surface of the drum, from the sleeve roller. The same bias as that applied
to the sleeve roller is applied to this Bias Seal, thereby preventing toner from falling.
• The developing bias automatically adjusts the print image density over a range of seven
steps through feedback control. A bias voltage, reversed from the developing bias, is applied
before a print command is issued, before predrive, and during predrive, to prevent toner from
transferring to the surface of the drum.