Service manual

7.4 PAPER TRANSFER
7.4.1 Paper Transfer Bias
The paper transfer corona unit [A] transfers toner on the transfer belt to the
paper [B]. The machine controls the paper transfer bias current by referring
to the readings from the thermo-sensor [C] and humidity sensor [D] on the
I/O control board 1 [E] . The bias also depends on the selected paper mode
such as normal and OHP/Thick paper (see the table on the following page
for some of the settings).
For the first 15 mm at the leading edge of the paper, the paper transfer bias
current is increased to attract the paper to the transfer belt. This prevents
poor transfer at the leading edge of the paper.
For the last 10 mm at the trailing edge of the paper, the paper transfer bias
current is reduced to prevent the paper from discharging to the belt.
To prevent the paper transfer corona unit from attracting toner from the belt
at the wrong time, the machine always applies a negative voltage (–1.7 kV)
to the corona wire and the case except during toner transfer to the paper.
[F]
[B]
[A]
High Voltage
Power Supply
[A]
[E]
[D]
[C]
TRANSFER BELT UNIT
A166/A187/A189 2-108 SM
CÓPIA NÃO CONTROLADA
CÓPIA NÃO CONTROLADA