Ricoh FT6645 Manual page 47

DRUM UNIT 23 April 1993
2.3.3 Charge Wire Cleaning Mechanism
[A]
[A]
[C]
[C]
[B]
The flow of air around the charge corona wire may deposit toner particles on
the corona wires. These particles may interfere with charging and cause low
density bands on copies.
The wire cleaner pads [A] automatically clean the wires to prevent such a
problem.
The wire cleaner is driven by a dc motor [B]. Normally the wire cleaner [C] is
located at the front end position (home position). After 5000 or more copies
are made and fusing temperature is less than 100°C after the main switch is
turned on, the wire cleaner motor turns on to bring the wire cleaner to the
rear end and then back to the home position.
When the wire cleaner moves from the rear to the home position (black arrow
in the illustration), the wire cleaner pads clean the wires.
There are no home position and return position sensors. The CPU monitors
the input voltage (5 V). When the wire cleaner reaches the end, it is stopped
and the motor is locked. At this time, input voltage slightly decreases (to
about 4 V) and the CPU judges to rotate the motor in reverse.
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