Introduction - Ricoh FT7770 Service Manual

CLEANING

1. Introduction

The first step in the drum cleaning process is the application of the pre-
cleaning corona (PCC).
ponents. The ac component makes drum cleaning more efficient by reducing
the drum's potential and weakening the electrical attraction between toner
and the drum.
charge to the toner particles. (The toner particles do not all have the same
amount of negative charge after the transfer and separation process. )
Next, the drum rotates past the cleaning brush. The brush moves in the op-
posite direction to the drum at the contact point. The brush removes the
toner from the drum by both physical rubbing action and electrical attrac-
tion. The bias roller keeps the cleaning brush clean. Its charge of +300
volts attracts the negatively charged toner from the brush. The bias roller
blade scrapes off the toner from the bias roller.
Finally, the cleaning blade scrapes off any toner, paper dust, or other for-
eign material remaining on the drum.
The toner collection coil transports the toner to the rear end of the clean-
ing unit, From there, a collection mechanism returns the toner to the toner
cartridge.
Related Service Call Condition: See FIELD MANUAL for details,
SC 14: PCC Current Leakage
The pre-cleaning corona has both ac and dc com-
The dc component of the corona gives a uniform negative
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30 April, '89