Controlling The Supply Power To The Fixing Heater; Controlling The Fixing Heater Temperature - Canon FC220 Service Manual

B.

Controlling the Fixing Heater Temperature

The target temperature for the fixing heater is controlled to four settings (155°, 165°,
175°, 185°C) by the microprocessor based on the following conditions:
a. Temperature of the fixing heater at time of power-on (185°C if 90°C or less; 165°C if
otherwise)
b. Temperature of the fixing heater at time of copy-start (185°C if 90°C or less; as
needed to suit the number of copies made if otherwise)
c. Number of copies made:
185°C if copy
175°C if for 2 to 4 copies
165°C if for 5 to 15 copies
185°C if for 16 copies or more
C.

Controlling the Supply Power to the Fixing Heater

The temperature of the fixing heater (H1) is controlled by controlling the power
supplied to the fixing heater.
The power to the fixing heater is controlled by a phase power control method.
The microprocessor on the DC controller/DC power supply circuit takes on the zero-
cross signal (ZXDP) from the zero-cross signal generator circuit as a sync signal to
identify the AC input voltage in relation to the reference voltage signal (VPEAK) from the
reference voltage sensor circuit.
Using the reading, the microprocessor controls the fixing heater drive command
(HTRD) power to attain the specific target temperature for the fixing heater, in other
words exerting phase control on the supply power to the fixing heater.
Further, 'E9' is indicated on the control panel if the zero cross signal (ZXDP) falls
below a specific value because of an error in the frequency of the power supply.
COPYRIGHT © 1998 CANON INC.
Reference
voltage
sensor circuit
Zero-cross
signal generator
circuit
DC controller/DC power supply PCB
Figure 6-101C
CANON PC400/420/430,FC200/220 REV.0 JAN.1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
VPEAK
Microprocessor
ZXDP
CHAPTER 6 FIXING SYSTEM
6-3