Drum Cleaning; Operation - Ricoh FT5540 Service Manual

8. DRUM CLEANING

8.1 OPERATION

Drum cleaning is accomplished by the pre-cleaning corona (PCC) [A], cleaning brush [B], and
cleaning blade [C].
As the surface of the drum enters the cleaning unit, the PCC applies an ac charge. This
loosens the toner on the drum.
In earlier models, the cleaning blade removed most of the toner, but in this model the cleaning
brush removes the bulk of the toner (about 90%). This is because the brush uses electric
potential as well as mechanical action to remove the toner. The cleaning brush has a positive
charge that attracts the negative toner.
After picking up the toner, the cleaning brush turns inside the cleaning unit. Just inside the
unit, it brushes against a beater bar [D]. The beater bar dislodges paper dust but is not
effective in removing the negatively charged toner.
Next the cleaning brush brushes against the bias roller [E]. The bias roller, which has a charge
of +300 volts, attracts the toner from the cleaning brush. The bias roller blade [F] scrapes the
toner from the bias roller and the toner drops on the toner collection coil [G]. The cleaning
blade removes the remaining toner (about 10%). The toner collection coil transports the used
toner to the rear of the machine where it falls into the used toner bottle.
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31 August 1989