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Technical Overview > Fixing System > Fixing Control Circuit > Protective Function
Technical Overview > Fixing System > Fixing Control Circuit > Protective Function
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Fixing Temperature Control
The Fixing temperature control maintains the temperature of the Fixing Heater at its targeted
temperature.
Block diagram of this control is shown below.
FREQSNS
TH1 TP1
H1: Fixing heater
TP1: Thermoswitch
TH1: Thermistor
FSRD
RLYD
FSRTH
+24V
RL101
Pressure roller
Fixing film unit
Fixing heater
control circuit
Fixing heater
safety circuit
DC controller
Low-voltage power supply
Engine controller
Fixing control circuit
Fixing unit
Relay
control
circuit
Frequency
detection circuit
F-2-25
The DC Controller monitors the FIXING TEMPERATURE (FSRTH) signal and sends the
FIXING HEATER CONTROL (FSRD) signal according to the detected temperature. The
Fixing Heater control circuit controls the Fixing Heater depending on the signal so that the
heater remains at the targeted temperature.
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Protective Function
The protective function detects an abnormal temperature rise in the Fixing Assembly and
interrupts power supply to the Fixing Heater.
The following three protective components prevent an abnormal temperature rise of the
Fixing Heater:
• DC Controller
• Fixing Heater safety circuit
• Thermoswitch
1) DC Controller
The DC Controller monitors the detected temperature of the thermistor.
The DC
Controller
makes the FIXING HEATER CONTROL signal inactive and releases the relay to interrupt
power supply to the Fixing Heater under the following condition:
2) Fixing Heater safety circuit
The Fixing Heater safety circuit monitors the detected temperature of the thermistor.
The Fixing Heater safety circuit releases the relay control circuit to interrupt power
supply
to the Fixing Heater under the following condition:
3) Thermoswitch
The contact of the thermoswitch is broken to interrupt power supply to the Fixing Heater
under the following condition:
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