Canon PC400 Service Manual - Page 101

Controlling the Fixing Heater Temperature, Controlling the Supply Power to the Fixing Heater

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CHAPTER 6 FIXING SYSTEM 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 zerocross 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. Reference voltage VPEAK sensor circuit Zero-cross signal generator ZXDP circuit Microprocessor DC controller/DC power supply PCB Figure 6-101C COPYRIGHT © 1998 CANON INC. CANON PC400/420/430,FC200/220 REV.0 JAN.1998 PRINTED IN JAPAN (IMPRIME AU JAPON) 6-3

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COPYRIGHT © 1998 CANON INC.
CANON PC400/420/430,FC200/220 REV.0 JAN.1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 6 FIXING SYSTEM
6-3
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.
Microprocessor
VPEAK
Zero-cross
signal generator
circuit
ZXDP
Reference
voltage
sensor circuit
DC controller/DC power supply PCB
Figure 6-101C