Fuser Control - Xerox phaser 6250 Service Manual

Fuser Control

Fuser Temperature Control
During fuser temperature control the printer's target temperature is set. The heat roller
surface temperature is controlled to match the target temperature by turning the heater
lamp on/off.
The heat roller surface temperature is detected by two sensors. A non-contact sensor
in the middle of the roller is checked for 60ms and the Temperature Sensor at the edge
of the roller is checked for 20ms to maintain an even temperature across the roller. If
the results of the 80ms cycle show the temperature is higher than the target, the heater
lamp is turned off. If the detection result is low, the heater lamp is turned on.
For the target temperature, different temperatures are set for standby, printing, and
process control. The target temperature is also changed according to the inside
temperature detected with the temperature/humidity sensor, print count, print mode,
input power supply voltage and paper type.
Cool Down
During printing, the temperature distribution of the heat roller becomes uneven
between paper and non-paper. To make the heat roller temperature as even as
possible, a wait time is provided and the heater lamp is kept off. This is called the cool
down.
A cool down is executed according to the number of sheets continuously printed when
a set, printing with a certain type and size of print media is completed, and when the
print media type or size is changed. The cool down, which results in a pause, occurs
evenly in the middle of several hundred sheets of continuous printing.
Theory of Operation
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