Fuser temperature control
The fuser temperature control maintains the target surface temperature of the fuser sleeve.
Figure 1-8 Fuser temperature-control circuit
FSRTH3
FSRTH2
FSRTH1
FSRD1
TP1
/RLD
TH3
TH2
TH1
CPU
H1
FSRSAFE1
FSRSAFE2
FSR_CURRMS
/ZEROX
/FSRSNS
/FSRNEW
Fuser sleeve unit
Fuser heater
safety circuit
DC controller
Fuser
Zerocross
circuit
Relay
control
circuit
Fuser control circuit
Pressure
roller
Fuse
Relay
Relay
Fuser heater
control circuit
Current
detection
circuit
Low-voltage power supply
Fuser heater safety circuit
Fuser heater safety circuit
H1: Fuser heater
TP1: Thermoswitch
TH1: Main thermistor
TH2: Sub thermistor 1
TH3: Sub thermistor 2
Fuser sleeve temperature protection
The fuser heater controls the temperature of the fuser sleeve. The DC controller detects the center area
temperature by monitoring the main thermistor. The DC controller controls the FIXING HEATER CONTROL
(FSRD1) signal, so that the fuser sleeve remains at the targeted temperature.
●
Protective function: The protective function detects rising temperatures in the fuser and interrupts
power to the fuser heater. The following four protective components prevent the fuser sleeve and
pressure roller from excessive rising temperature:
◦
DC controller
◦
Fuser heater safety circuit
◦
Current detection circuit
◦
Thermoswitch
●
DC controller: The DC controller monitors the detected temperature of the main thermistor and sub
thermistors. The DC controller deactivates the FIXING HEATER CONTROL signal and releases the relay to
interrupt power supply to the fuser heater under the following conditions:
20 Chapter 1 Theory of operation ENWW
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