Ricoh FT5034, Service Manual

Page: 76 / 139

4.10 DRUM CLEANING
1. Overview
Drum cleaning is accomplished by the
pre-cleaning corona (PCC), cleaning brush,
and cleaning blade.
As the region of the drum with toner still
attached enters the cleaning unit, the PCC
applies a positive charge, and the charge on
the toner changes from negative to positive. As
a result, the toner is held to the drum only by
adhesion and can be removed easily.
The cleaning brush and drum move in opposite
directions at their point of contact. The
cleaning brush removes paper dust and toner
from the drum surface. It brushes off nearly
half of the toner on the drum to reduce the
cleaning load placed on the blade.
Next, the cleaning blade removes the remaining toner. The falling toner catches in
the fibers of the cleaning brush and is carried inside the cleaning unit. As the brush
turns inside the cleaning unit, it rubs against a beater ridge, which dislodges the
toner particles. The toner particles fall onto the toner collection coil.
The toner collection coil transports the used toner to the front of the machine where it
falls into the used toner bottle.
2. Pre-Cleaning Corona
After image transfer and paper separation, the
drum surface still has a positive charge and the
remaining toner on the drum has a negative
charge. The attraction between the toner and
the drum is reduced by the cleaning brush due
to its conductivity (the brush is grounded to the
machine frame). However, the remaining
attraction makes cleaning difficult. Toner will
tend to pile up in front of the cleaning blade and
cause poor cleaning or even block the cleaning
mechanism.
Cleaning Blade
Cleaning
Brush
Point of Contact
Projecting Ridge
Cleaning Seal
PCC Wire
Pick-off
Pawls
Blade
Scraper
Toner
Collection
Coil
PCC Wire
Power Pack - T/S/PCC
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