Pre-Cleaning Corona And Bias Roller - Ricoh FT5540 Service Manual

31 August 1989

8.2 PRE-CLEANING CORONA AND BIAS ROLLER

The pre-cleaning corona [A] applies a negative charge to the drum and any toner remaining
on the drum's surface using an ac voltage with a negative dc bias. A negative bias is used
because toner more readily accepts a negative charge, and a negative charge is more stable
than a positive charge.
The cleaning brush [B] is conductive and contacts both the drum and the bias roller [C] within
the cleaning unit. The bias roller has a positive dc voltage (300 volts) applied to it. This enables
the cleaning brush to remove toner from the drum efficiently and deposit it in the cleaning unit.
2-56