Lexmark MS81x Service Manual page 618

4063
Development
The toner contained within the PC cartridge has an electrical property that causes it to adhere to the development
roller. The metering blade spreads the toner into a very thin layer on the development roller. Friction between the
development roller and the CM blade development roller generates a small electrical charge that is transferred to the
toner.
The surface of the developer roller is made up of a thin sheet of conductive material. The HVPS supplies the development
roller with two voltages: a DC voltage and an AC voltage. The DC voltage is used to transfer toner from the development
roller to the surface of the drum. The AC voltage agitates the toner on the development roller, making toner transfer
easier.
The development roller maintains a negative DC electrical potential. Negative charged areas of the drum have a lower
electrical potential, or higher relative negative value than the development roller. Discharged areas of the drum have
a higher electrical potential, or lower relative negative value, than the development roller. A discharged point on the
surface of the drum now appears less negative in relation to the negative charge on the development roller.
The toner adhering to the development roller is always in contact with the drum surface. When a less negative point
on the drum (a discharged area) comes in contact with the more negative charged toner on the Magnet roller, toner
transfers from the magnet roller to that point on the drum. There is now a visible toner image— developed image—
on the drum surface.
Appendix C: Theory of operation
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