Fixing System; Fixing Control Circuit; Outline; Fixing Temperature Control - Canon imageCLASS LBP6780dn Service Manual

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Technology > Fixing System > Fixing control circuit > Fixing temperature control

Fixing System

Fixing control circuit

■ Outline

The fixing control circuit controls the temperature in the fixing unit. The printer uses an on-
demand fixing method.
The Figure below shows the configuration of the fixing control circuit.
H1
TP1
TH2
TH1
FIXING HEATER CONTROL signal
Fixing heater control
DC controller
Engine controller
• Fixing heater (H1): Heats the fixing film
• Thermistor (TH1, TH2): Detects fixing temperature (Contact type)
• Main thermistor (TH2): Controls temperature in the fixing unit (Contact type)
• Sub thermistor (TH1): Detects one-sided temperature rise of the fixing unit Controls
temperature in the fixing unit (Contact type)
• Thermoswitch (TP1): Prevents an abnormal temperature rise of the fixing heater (Contact
type)
These temperature controls in the fixing unit are performed by the fixing heater control circuit
and the fixing heater safety circuit according to the commands from the DC controller.
2 Technology > Fixing System > Fixing control circuit > Fixing temperature control
Fixing film
Pressure roller
FIXING TEMPERATURE signal
Fixing heater safety
circuit
circuit
Fixing control circuit
F-2-13

■ Fixing temperature control

The fixing temperature control maintains the temperature of the fixing heater temperature.
The Figure below shows the block diagram of the fixing temperature control.
RL1001
RL1002
Fixing heater
control circuit
Fixing film
TH2
TP1 TH1
H1
Pressure roller
Fixing unit
The DC controller monitors the FIXING TEMPERATURE (FSRTH1, FSRTH2) signals 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.
Engine controller
Fixing control circuit
DC controller
ZEROX
Frequency
detection circuit
RLYD
Relay control
circuit
Fixing heater
safety circuit
FSRTH1
FSRTH2
FSRD
H1: Fixing heater
TP1: Thermoswitch
TH2: Main thermistor
TH1: Sub thermistor
F-2-14
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