Xerox Phaser 6180, Service Manual, Page: 109 / 616

Phaser 6180 Color Laser Printer Service Manual 2-55
Theory of Operation
Fuser Control
Fuser Temperature Control
After the target temperature is set, the Heat Roll surface temperature is
controlled so at that it can be the target temperature by turning the Heater
Lamp On/Off.
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. When the temperature is detected higher than the target, the
Heater Lamp will turn Off. When the temperature is lower than the target, the
Heater Lamp will turn 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 Humidity Sensor, the difference of
the temperature between the center and edge areas of the Heat Roll, Printing
Mode, or the Input Power Voltage.
Cool Down
As printing continues, the distribution of temperature in the Heat Roll
becomes uneven in both the paper feed and non-paper feed areas. Cooling
Down process is to provide a certain period of time without feeding paper so
that the Heat Roll temperature can be distributed evenly.
When the edge of Heat Roll temperature is high, cooling down is performed to
lower the temperature to the target temperature.
Sensor Warm-Up
The Fuser Non-Contact Sensor at the center of the Heat Roll will lose its
accuracy of detecting 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 process is called Sensor Warm-Up.