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3.
Controlling the Power Supply to the
Fixing Heater
The temperature of the fixing heater is
controlled by controlling the power supplied
to the fixing heater.
The power to the fixing heater is con-
trolled by controlling its phase.
The microprocessor on the DC controller
PCB controls the output timing of the fixing
heater driver signal (HTRD) so that power
suited to the target temperature of the fixing
heater may be supplied; this is to control the
phase of the power supplied to the fixing
heater.
HTRD
| S|)
'
H
'
\
'
H
t
\
H
{
t
}
'
t
}
Supply power|__
| i"
¢ _
| \
to the heater
rs
Vf
Figure 3-410
3-54
COPYRIGHT © 1995 CANON INC.
4.
Correcting the Variation in the
Resistance of the Fixing Heater
The plane-shaped heater used as the
fixing heater has production variations in its
resistance that would hinder proper execu-
tion of thermal control of the fixing heater.
To correct possible problems, the copier
compensates for the variations in terms of
seven settings of the resistance, whose val
ues are read by a microprocessor.
The resistance of the fixing heater is
decided based on the combination of
the jumper wires connected to the con-
nector of the thermistor (TH1); see
Figure 3-411.
:
The resistance is checked and appro-
priate settings are made at the factory
when the fixing assembly is assem-
bled; do not rearrange the jumper
wires,
:
;
Figure 3-411
CANON NP6012/NPGOT2F /NPG2I2 REV.1 SEPT. 1905 PRINTED
IN JAPAN (IMPRIME
AU JAPON)
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