COPYRIGHT © 1999 CANON INC. CANON imageRUNNER 400/330 REV.0 JAN. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
6-11
CHAPTER 6 IMAGE FORMATION SYSTEM
5. Controlling the Output Mode
a. Types of Modes
The transfer charging output takes the following output modes, each with a different output and
switched based on the combination of transfer output mode signals from the image processor PCB.
See Figure 6-107 for the timing of application.
n
Image Transfer Bias
This bias is used to transfer toner form the photosensitive drum to copy paper, and is positive in
polarity.
n
Cleaning Bias
This bias is applied at the following timing to return the toner adhering to the transfer charging
roller for some reason back to the photosensitive drum, and is negative in polarity.
During initial rotation after the Copy Start key is pressed
During last rotation
During initial rotation after error correction made in response to jam removal
During roller cleaning operation in user mode ("adjust/clean"; this is accompanied by
cleaning of the primary charging roller)
n
Reference Bias
This bias is used to correct the application voltage level (ATVC control). It is applied each time
the Copy Start key is pressed, thereby correcting the voltage level.
n
Sheet-to-Sheet Bias
This bias has a low level so as to prevent adhesion of toner to the transfer charging roller in
non-image areas in continuous copying mode.
SLEEP
STBY
INTR
SCFW
SCFW
LSTR
SCRV
STBY
Main motor (M1)
SCRV
Main power
switch ON
Control power
switch ON
Copy Start key ON
Image transfer bias
Cleaning bias
Reference bias
Sheet-to-sheet bias
Figure 6-106
b. Turning On and Off the Cleaning Bias
When the cleaning bias output signal of the composite power supply PCB goes '1', the output
from the main transformer is applied to the transfer charging roller.