Drum Charge; Overview - Gestetner A193 Service Manual

PCU (PHOTOCONDUCTOR UNIT)

4.4 DRUM CHARGE

4.4.1 Overview

This copier uses a drum charge roller system instead of a corona wire
scorotron system to charge the drum. For the copy image area or during
roller cleaning, the drum charge roller [A] contacts the surface of the drum [B]
to give it a negative charge.
The drum charge roller system has the following advantages over the corona
wire scorotron charge system.
•
The amount of ozone generated during drum charging is less than about
1/10 of that for a corona wire scorotron system.
•
The applied voltage is 1/2 ~ 1/3 that of a corona wire scorotron system.
•
The efficiency of drum charge is high.
Due to these advantages, no ozone filter is required in this copier.
The high voltage supply board [C] povides a negative dc voltage to the drum
charge roller through the charge roller terminal [D], rear pressure spring [E],
and the rear roller bushing [F]. The charge roller will provide the drum surface
with a negative charge of –900 V.
(A193)
[E]
[A]
[B]
[F]
2-26
[C]
[D]
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