B. Fixing Control Circuit
1. Fixing temperature control
A plate-shaped fixing heater is installed in the fixing film unit to heat the fixing film.
The fixing heater temperature is detected by the thermistor (TH701) on the fixing heater. As
the temperature of the fixing heater rises, the resistance of TH701 drops, and the voltage of the
FIXING HEATER TEMPERATURE DETECTION signal (FSRTH) decreases.
The CPU (IC201) on the engine controller PCB outputs the FIXING HEATER DRIVE signal
(FSRD) based on the FSRTH signal voltage to bring the fixing heater temperature within the
specified value.
The fixing heater temperature is controlled in three modes:
1) Initial temperature control: The fixing heater temperature is increased to its normal target
temperature value after the pick-up command is input to the engine controller.
2) Normal temperature control: The fixing heater temperature is controlled to be its normal tar-
get temperature value during printing.
3) Between-page temperature control: The fixing heater temperature is controlled at low tem-
perature to prevent the temperature rise at the non-feeding areas between pages on the fix-
ing film.
Figure 2-2-4
CHAPTER 2
2 - 8
Fixing heater
(H701)
IC201
FSRTH
CPU
27
FSRD
38
Pressure roller
(TH701)
Thermistor
Fixing film unit
J102-2
J102-1
+3.3V
+3.3V
+24V
INL101
FU101
IC302
SSR101
/RLYD
Engine controller PCB
Thermal fuse
(FU701)
35
+3.3V
+3.3V
RL101
+24V
J206-1
J206-2
Fixing heater safety circuit
