3. DRUM UNIT
3.1 DRUM CHARGE
This copier uses a single corona wire scorotron system to charge the drum.
The corona wire applies a negative charge to the drum surface. The striped
stainless steel grid plate makes the corona charge uniform and controls the
negative charge on the drum surface to -650 V (standard) by applying a
negative grid bias voltage.
The high voltage supply board –C/G gives a constant corona current (–450
µ
A) to the corona wire, and controls the grid voltage (based on the results of
process control) to maintain proper image density. Grid voltage is controlled
to match changing factors such as a dirty grid plate, dirty charge corona
casing, and OPC chargeability.
The use of the single wire scorotron system has the following advantages.
•
The amount of corrosive gas (O
3
, NO
X
) is reduced due to the decrease
in total current.
• The life time of the drum is increased due to the decrease in the amount
of corosive gas.
• Uneven charge problems are alleviated due to the increase of the
amount of current per meter of the corona wire.
Detailed
Descriptions
SM 2-9 A172/A199
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