Phaser 6500/WorkCentre 6505 Service Manual Xerox Internal Use Only 2-7Theory of OperationDevelopmentToner is electrically attached to the invisible electrostatic latent image on the drumsurface to form the visible toner image on the drum.The toner in the Toner Cartridge is agitated by the built-in agitator and fed intothe developer. The augers are driven by the toner motors and the developer motorin the Main Drive Assembly. The toner is consumed according to the print countand fed into the developer. This process, called toner dispensation, is controlled bytwo processes: pixel count dispense control (PCDC) and automatic density control(ADC).The toner fed into the developer is agitated by the auger, and supplied to themagnet roller. The toner and carrier are charged by friction due to agitation (tonerin negative, carrier in positive), and they are attracted electrically. A uniform layeris formed by the trimmer bar as the carrier is attracted to the magnetic roller.The magnet roller is covered by a thin semi-conductive sleeve. A developing biasvoltage is supplied to the sleeve from the High Voltage Power Supply (HVPS). Thedeveloping bias voltage is negative DC voltage combined with AC voltage. The DCvoltage holds the magnet roller at a constant negative voltage against thephotoreceptor layer of the drum. Therefore, at the area where the negative electriccharge on the drum surface does not decrease, the potential is lower than that ofthe magnet roller, while the potential is higher than that of the magnet roller atthe area where the negative charge on the drum surface decreases.The AC voltage waveform releases the developer on the magnet roll so that thetoner moves to the drum. Thus, only the portions of the drum surface where thenegative charge has decreased below that of the magnet roll (electrostatic latentimage) attract toner to form an image on the drum.Once the toner is deposited on the drum, the potential and the toner-attractingforce of the corresponding portion decreases because the increase of negativecharge lowers the potential at that portion.s6500-023HVPS: Negative Electric Charge: Positive Electric Charge: Toner: CarrierTrimmer RodPaddleToner CartridgeAugerAugerMagnet RollerAgitatorDrum
