Ricoh infotec 3671F Service Manual page 25

July 30th, 1996 DETAILED SECTION DESCRIPTIONS
PRINTING
2.2.2. OPC Drum
[C]
[D]
[A]
[B]
H528D506.wmf
This machine uses an organic photoconductor drum [A]. The diameter of the
drum is 30 mm. It is driven by the main motor [B] through a gear train [C]. The
charge brush roller [D] is also driven by the main motor.
The drum cartridge is replaceable by the user.
2.2.3. Charge
[A]
[B]
[C]
H528D517.wmf
The charge brush roller [A] is located in the drum unit. It applies the
charge bias in direct contact with the drum [B]. The high voltage power
supply applies a high voltage of -350 V to -1350 V, switched at 30 Hz,
through plate [C].
Since the machine uses a charge brush roller, the ozone production is greatly
reduced and the charge bias applied to a roller is relatively low compared to
that for a corona wire.
The charge brush roller rotates faster than the drum. (The speed ratio is
about 4 : 1.)
There is no cleaning mechanism. Also, toner is transferred back to the drum
by the transfer roller in cleaning mode. The charge brush roller picks up some
of this toner. In extreme cases, this may lead to vertical black lines on copies
in areas corresponding to places on the brush that have excessive toner.
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