Chapter 6 Fixing System; Outline Of Operation; Outline - Canon NP7160 Service Manual

I. OUTLINE OF OPERATION
A. Outline
The upper roller and the lower roller of the fixing assembly and the delivery roller of the
delivery assembly are operated by the drive from the main motor (M1) coming through gears.
The upper roller has a built-in heater which is kept on during WMUP after power-on at 1000
W (120 V)/1050 W (230 V). Other than WMUP, the heater is subjected to phase control, and is
turned on at 805 w (120/230 V) or off.
The fixing temperature is detected with reference to the surface temperature of the upper
roller rear end detected by the main thermistor (TH1) and the sub thermistor (TH2), and is
communicated to the microprocessor on the DC controller PCB.
Based on the thermistor signal (TH1, TH2), the DC controller PCB turns on/off the fixing
heater drive signal (HEAT_DR) to turn on/off the fixing heater (H1), thereby keeping it at the
target temperature. To cut off AC power to the heater in the event of overheating, a thermal
switch (TSW1) is mounted at the front of the fixing upper roller.
The copier is designed to remove toner adhering to the upper or the lower roller; for this
reason, its heat discharge roller is kept in firm contact with the lower roller.
Delivery
roller
Pressure
roller
Reference:
Fixing heater:
Thermal switch:
COPYRIGHT © 1998 CANON INC.
Fixing sub thermistor signal (TH2)
+24V GND
RL1
TSW1
TH1
TH2
H1
Fixing upper
roller
Heat discharge
roller
Figure 6-101
1000 W for the 120 V model, 1050 W for the 230 V model.
230 ±10°C.
CANON NP7161/NP7160 REV.0 AUG. 1998 PRINTED IN JAPAN (IMPRIME AU JAPON)

CHAPTER 6 FIXING SYSTEM

Power
supply
PCB
Fixing main thermistor signal (TH1)
M1
HEAT _ DR
DC
HEAT _ ERR
controller
PCB
6–1