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PTM 2-40 B070/B071
2.5.4 DRUM CHARGE
Overview
This copier uses a double corona wire Scorotron system to charge the drum. Because
of the high speed of this copier, two corona wires are needed to give a sufficient,
uniform negative charge to the drum surface. The stainless steel grid plate makes the
corona charge uniform and controls the amount of negative charge on the drum
surface by applying a negative voltage to the grid.
The CBG (Charge, Bias, Grid) power pack [A] supplies a constant corona current to
the corona wires, –1600
µ
A for Photo mode and –1400
µ
A for all other modes (Text,
Text/Photo, Pale, Generation Copy).
The voltage to the grid plate is automatically controlled to maintain the correct image
density in response to changes in drum potential caused by dirt on the grid plate and
charge corona casing. This is described in Process Control section in more detail.
B070D203.WMF
[A]