Fixing Control - Canon LBP-1760 Service Manual

CHAPTER 2
B. Fixing Control
1. Fixing temperature control
The fixing film unit contains a fixing heater of a flat stick shape, which heats the fixing film.
The temperature of the fixing heater is detected by the thermistor (TH901) on the fixing
heater. When the surface temperature rises, the resistance of TH901 drops and the voltage of
the FIXING HEATER TEMPERATURE DETECTION signal (FSRTH) drops.
Based on the voltage of this FSRTH signal, the CPU (IC501) on the engine controller controls
the FIXING HEATER DRIVE signal (FSRDO) so that the fixing heater temperature becomes the
specified value.
This FSRDO signal is generated based on the ZERO-CROSS signal (/ZEROX) output from the
heater control circuit.
Fixing heater control circuit
Fuse (FU2)
Fuse (FU1)
+3.3V
SSR10
Q30
Thermistor Temperature fuse
(TH901)
Fixing heater
(H901)
Fixing film
unit
Pressure roller
M10
Delivery roller Main motor
2 - 10
Engine Controller
Zero-cross
detection circuit
Relay
(RL101) +24V
Q30
TB1 TB11
J31- THR
(FU901)
J31-2
Figure 2-2-6
Fixing heater safety circuit
+3.3V
+3.3V
IC30
8
14 -
9
+
+3.3V
+3.3
+3.3V
IC30
1
13 -
11
+
+3.3V
Q30
FSRD
6
/ZERO
1
IC50
1
RL
6
/PRN
FSRT
2
/HITMP
4