◦
TH1: 230° C (446° F) or higher
◦
TH2: 285° C (545° F) or higher
◦
TH3: 285° C (545° F) or higher
●
Fuser-heater safety circuit: The fuser heater safety circuit monitors the detected temperature of the
sub thermistors. The fuser heater safety circuit releases the relay to interrupt power supply to the fuser
heater under the following conditions:
◦
TH2: 290° C (554° F) or higher
◦
TH3: 290° C (554° F) or higher
●
Current-detection protection circuit: The current detection circuit monitors the current flowing
through the fuser heater control circuit. The current detection circuit deactivates the fuser heater
control circuit to interrupt power supply to the fuser heater when it detects the current higher than a
specified value.
●
Thermoswitch: If the temperature in the heaters is abnormally high, and the temperature in the
thermoswitches exceeds a specified value, the contact to the thermoswitch breaks. Following are the
thresholds for each thermoswitch:
◦
TP1: 270° C (518° F) or higher
NOTE: When the thermoswitches reach this temperature, the temperature on the fuser rollers is about
320° C (608° F).
Failure detection
The DC controller determines a fuser unit failure, deactivates the FIXING HEATER CONTROL signal, releases
the relay to interrupt power supply to the fuser heater, and notifies the formatter of a failure status when it
encounters any of following conditions:
●
Abnormally high temperatures: Temperatures are too high for any of the following components, at
any time:
◦
TH1: 230° C (446° F) or higher
◦
TH2: 285° C (545° F) or higher
◦
TH3: 285° C (545° F) or higher
●
Abnormally low temperatures: Temperatures are too low at any of the following components after the
product has initialized.
◦
TH1: 120° C (248° F) or lower
◦
TP2 or TP3: 100° C (212° F) or lower
●
Abnormal temperature rise: The DC controller determines an abnormal temperature rise if the
detected temperature of TH1 does not rise 2° C within a specified time after the fuser motor is turned on
or if the detected temperature of the thermistors does not rise to a specified temperature for a
specified time after the fuser motor is turned on.
●
Thermistor open: The DC controller determines a thermistor open if:
ENWW Engine-control system 21
To Next Page
Loading...