Drum Charge - Ricoh Robin Service Manual

24 June 1994

DRUM CHARGE

2. DRUM CHARGE
2.1 OVERVIEW
[C]
[A]
[B]
[D]
[D]
[A]
This copier uses a double wire scorotron and a highly sensitive OPC drum
[A]. The corona wires [B] generate a corona of negative ions when the
CC/Grid/Bias power pack [C] applies a high voltage. The CC/Grid/Bias power
pack also applies a negative high voltage to a stainless steel grid plate [D].
This insures that the drum coating receives a uniform negative charge as it
rotates past the corona unit.
The exhaust fan, located above the copy exit, causes a flow of air from the
upper area of the development unit through the charge corona unit. This
prevents an uneven build-up of negative ions that can cause uneven image
density. The exhaust fan runs at half speed when in the stand-by condition
and at full speed while copying.
The exhaust fan has an ozone filter (active carbon) which adsorbs ozone (O )
3
generated by the charge corona. The ozone filter decreases in efficiency over
time as it adsorbs ozone. The ozone filter should be replaced at every 80K
copies.
The flow of air around the charge corona wires may deposit paper dust or
toner particles on the corona wire. These particles may interfere with
charging and cause low density bands on copies. The wire cleaner cleans
the corona wire when the operator slides the corona unit out and in.
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