Canon imageRUNNER 2525 Series, Service Manual, Page: 73 / 402

[3]
Environment sensor
Photosensitive drum
Static eliminator
Transfer charging roller
[1]
HVT PCB
[2]
Transfer bias
control circuit
DC Controller PCB
Static eliminator bias
control circuit
No. Part name
[1] Separation static eliminator bias control signal
[2] Transfer bias control signal
[3] Environment sensor detection signal
● Transfer Bias Constant Current Control
The transfer bias control circuit on the DC controller PCB controls the transfer bias applied to the transfer roller to keep the
constant current.
● Transfer bias level control
The transfer bias output varies according to the environment, paper type, paper width, and/or source of paper detected by the
environment sensor (HU1).
● Cleaning Bias Control
To return the toner adhered on the transfer roller to the photosensitive drum, negative voltage is applied at the last rotation.
● Separation Static Eliminator Bias Control
Either of the two types of negative voltage (low bias or high bias) is applied to the static eliminator depending on the print mode
and sequence for reducing electrostatic suction to facilitate separation of paper from the photosensitive drum.
■ Waste Toner Box
Outline
Residual toner adhered on the photosensitive drum without being transferred to a paper is scraped off by the cleaning blade in
contact with the photosensitive drum, then fed into the waste toner box by the waste toner feed screw.
The waste toner box is supported by a spring. If the waste toner box sinks down lower than specified with the weight of collected
toner, the waste toner full sensor (S17) detects the waste toner box full.
2. Technical Explanation
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