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————
SSS
SSS SS
EE
OF
ATONS AND TIMING Lod
d.
Controlling (automatic) the Primary
Charging roller Bias Application Voltage
Level
and the Scanning
Lamp
ON
Voltage Level (APVC, ALVC control)
Copy images will suffer changes
if
changes occur in their static latent images,
which in turn are caused by the following:
¢ changes in drum sensitivity; and
* changes in the degree of charge by
the primary charging roller.
These symptoms are brought about by
changes in the site environment (tempera-
ture, humidity) deterioration, wear, or dirt on
parts.
The copier's light area potential (VL) and
dark area potential (VD) have a tendency to
increase; to compensate for this tendency,
the copier corrects the primary charging
roller bias application voltage level (APVG
control) and the scanning lamp ON voltage
tevel (ALVC control), thereby ensuring a spe-
cific light area potential (VL) and dark area
potential (VD) at all times.
Study the following for an idea of how
the mechanism
is activated (after power-on,
during initial rotation for 1st copy):
° Flow
A specific voltage of about -1.376 kV is
applied to the primary charging rotler for about
1.3 sec.
——
The current value at this time is detected by
the current detection circuit, and sent to the
microprocessor (Q501).
4
The microprocessor (Q501) in turn sends the
current value to the microprocessor {Q101) on
the DC controller so that the application
voltage for the primary charging roller bias
may be determined based on the value.
COPYRIGHT © 1995 CANON INC.
You must enter the APVC value
recorded on the label attached to the
composite power supply circuit using
service modes No. 34 and No. 35
whenever you have replaced the com-
posite power supply PCB. -
You must enter the APVC correction
voltage value recorded o
he label
attached to the front of the d
user mode 'U7' or service modes No.
32 and No. 33 whenever you have
replaced the drum unit if the model
does not accommodate PGP.
CANON NP6O12 /NPGO12F /NP6212 REV.1 SEPT. 1995 PRINTED
IN JAPAN (MPRINE
AU JAPON)
3-25
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