Canon LBP-860, Руководство по обслуживанию

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2. Control of laser beam intensity (APC
control]
The CPU performs power control
of the laser diode to make the laser
diode
constant
light. This control can
be classified two types: initial APC and
between-page APC.
a. Initial
APC is performed to increase the
intensity of laser beam from zero to
value during initial rotation.
The CPU sets FORCIBLE LASER
ON signal Lo and at the
same time the CPU changes the APCOR
signal (coarse adjustment) and lets the
signal gradually rise from the
l o w v a l u e . A s laser
increases. the laser diode begins
emitting light.
intensity of laser diode
is detected by the
After amplification, the output
voltage is fed back Lo the CPU as the
POWER CONTROL INPUT
signal
continues coarse
of
t h e
A P C I N
signal reaches of the value
in
Lhe
CPU. The CPU then does
adjustment with the signal,
and the initial APC when the
value of the APCIN signal has
become almost equal Lo the
b.
Between-page APC is performed
APC, and when is not
being performed while waiting for the
page proceed to the printing
area, Lo variations in the
of he laser printing.
is also performed
during the unblinking period, described
Lo prevent the laser beam from
writing on the image area of the
photosensitive drum.
The CPU sets the UNBLANKING
signal used by and not
CHAPTER 2
output externally) to “H” and sets the
FORCIBLE LASER ON signal to
The CPU then changes the APCOS
signal (fine adjustment]. compares the
input value of the APCIN signal with
the target value. and optimizes the
of the laser beam.
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