EXP Computer C4077-90960 - Manual (Page 100)

Drum Conditioning
After the drum is physically cleaned, it is conditioned by applying a uniform
negative charge across the surface of the drum with the primary charging
roller, located in the toner cartridge. The primary charging roller is coated
with conductive rubber, charged with an AC current which erases any
residual charges, and produces a uniform drum surface potential. The AC
current is centered around a negative DC bias which changes according to
the Print Density setting.
Primary Charging Roller
Figure 5-9
5
Functional Overview
Functional Overview 5-15