Drum Charge - Ricoh 5510L Service Manual

14 June, 2002 PRINTER

Drum Charge

[A]
[B]
[E]
[C]
[D]
H310D924.WMF
This machine uses a drum charge roller system instead of a scorotron corona wire
system to charge the drum. The drum charge roller [A] always contacts the surface
of the drum [E] because of the charge roller pressure springs [C], and gives a
negative charge to the drum surface. While the drum is rotating, the drum charge
roller also turns because of friction between the roller and the drum.
The drum charge roller system generates less ozone than a scorotron corona wire
charge system. Due to this, there is no ozone filter in the machine.
The high voltage supply board applies voltage to the drum charge roller through the
charge roller terminal [B], charge roller pressure spring [C], and the charge roller
bushing [D]. Both ac and dc are applied.
Before the laser starts to write to the drum, the charge roller receives –600Vdc and
1.05 kV peak-to-peak 1 kHz ac from the high voltage supply board. This gives the
drum surface a uniform negative charge of –600 V.
The dc and ac are continually supplied during the printing job. This gives the drum
surface a uniform –600 V charge wherever it passes the charge roller.
At the end of the job, the dc is set to 0 V, but the ac stays on. While the drum
rotates past the charge roller, the ac brings the charge on the drum surface to a
uniform 0 V.
The toner cartridge has no cleaning pad, temperature control, or contact
mechanism for the drum charge roller (the material of the drum charge roller allows
a simple mechanism). The drum charge roller is part of the toner cartridge, so
when the toner runs out, the drum charge roller is changed at the same time. This
happens before the drum charge roller gets dirty.
To discharge the OPC drum surface, the LD is switched on after every 10 sheets
printed (if the 10-page interval expired during a job, the machine waits until the end
of the job). There is no quenching lamp in this machine.
6-15