Brother HL-4200CN, Руководство по обслуживанию

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7.8 Fuser Control
7.8.1 Fuser temperature control
As for the fuser temperature control, the target temperature is set, then the heat roll
surface temperature is controlled so as to be the target temperature by turning on/off the
heater lamp.
Temperature of individual area of the heat roll is detected by the fuser non-contact
sensor (NCS) in the middle of the heat roll and the temp sensor at the edge of it. The
temp sensor checks for open wire by detecting the temperature every 60ms and
resistance every 20ms alternately. When the temperature detected every 80ms shows
the figure higher than the target, the heater lamp will be turned off. When the result
shows a lower figure, the heater lamp will be turned on.
The target temperature set up varies depending on the time of warm-up, printing, or
process control. The target temperature will be changed based on the interior
temperature detected by the sensor hum temp, the difference of temperature between
the center and edge areas of the heat roll, printing mode, or the input power voltage.
7.8.2 Cool down
As the printing continues, the distribution of temperature in the heat roll becomes uneven
both in the paper feed and non-paper feed areas. Cooling down is to provide a certain
period of time without feeding paper so that the heat roll temperature can be distributed
evenly.
Cooling down is performed for certain period of time after printing was completed.
7.8.3 Sensor Warm-up
The fuser NCS (Non Contact Sensor) at the center of the heat roll does not detect
temperature when the temperature of the sensor itself is below -5°C. Therefore, the
sensor will be warmed up when the temperature is below -5°C. This action is called
sensor warm-up.