Canon LBP-860 Service Manual page 61

CHAPTER 2
When the DEVELOPING BIAS DC ON
signal is sent from the DC controller via
the serial line, a developing DC bias is
applied to the developing cylinder.
When the VERTICAL SYNC signal
controller. the DEVELOPING BIAS AC
O N s i g n a l i s s e n t f r o m t h e D C
controller via the serial line, and the
voltage comprising the developing DC
bias and developing AC bias is applied
to the developing cylinder.
The developing DC bias changes
with the image density data sent from
the DC controller via the serial line,
and the image density can be adjusted.
AC
bias
Figure
T r a n s f e r c h a r g i n g roller v o l t a g e
c.
generation
A negative or between-page or print
bias is applied to the transfer charging
roller according to the print sequence.
A negative bias voltage is applied to
the lransfer
appropriate time to move the toner
attached to the transfer charging roller
to the photosensitive drum, and so
clean the roller.
A print bias voltage is applied to the
transfer charging roller to transfer the
toner on the photosensitive drum to the
paper.
When the /PRNT signal from the
video controller becomes "L", initial
rotation starts and a negative bias is
applied to the transfer charging roller
for a certain time to clean the roller. A
print bias is also applied during the
print sequence to transfer loner to the
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2-30
charging roller during
paper.
After completion of printing, a between-
page and a negative biases are applied
again to clean the transfer charging
roller.
d. Toner sensing/cartridge sensing
The EP-E cartridge has a toner sensor
that detects the toner level and whether
there is a cartridge when the developing
AC bias is applied to the developing
ON signal.
The detection result is sent to the DC
controller via the serial line.