Canon imageRunner 2022, Service Manual

Page: 192 / 418

Chapter 6
6-8
The transfer unit consists of a transfer roller [1] and an static eliminator [2].
The transfer roller is driven by the photosensitive drum.
The static eliminator is biased to separate paper from the drum.
F-6-12
6.8.2 Controlling the Transfer Bias
6.8.2.1 Transfer Roller Bias Control
0017-4356
iR2022i / iR2025 / iR2030 / iR2018 / iR2022 / iR2018i
A negative bias, sheet-to-sheet bias, or positive bias is applied to the transfer charging roller according to the type of sequence.
The negative bias is applied at the prescribed timing to moves the toner from the transfer charging roller to the photosensitive drum for cleaning.
The sheet-to-sheet bias is lower than that applied during printing and it is applied at the prescribed timing to prevent the toner remaining on the photosensitive drum
from adhering to the transfer charging roller.
The positive bias is applied to transfer toner images from the photosensitive drum to paper.
F-6-13
6.8.3 Separation Mechanism
6.8.3.1 Static Eliminator Bias Control
0017-4357
iR2022i / iR2025 / iR2030 / iR2018 / iR2022 / iR2018i
Two types of biases, a high-output bias and a low-output bias, are applied to the static eliminator using the static eliminator bias drive signal (/DISDCFOT) and
static eliminator bias output level signal (/DSCPWM) issued from the DC controller PCB according to the type of the print sequence, thus allowing the printing
paper to separate easily from the photosensitive drum.
F-6-14
[1]
[2]
Tr3
TRCRNT
/TRPWM
To transfer
charging roller
Transfer bias circuit
ASIC
CPU
Positive current
detection circuit
Positive voltage
generation circuit
Negative voltage
generation circuit
Comparison
circuit
/TRPFOT
TRCHG
/TRNFOT
Superimposition
Constant current/voltage
switching circuit
High-voltage power supply PCB
DC
controller
PCB
/DSCPWM
/DISDCFOT
To static eliminator
Static eliminator bias circuit
ASIC
CPU
Static eliminator bias
generation circuit
High-voltage power supply PCB DC controller
PCB
JP9/JP10