Fuser Control - Epson AcuLaser C2800 Service Manual

AcuLaser C2800/C2800D/C3800/C3800D

2.7.5 Fuser Control

2.7.5.1 Fuser Temperature Control
The Fuser Temperature Control sets up the target temperature at all times, and turns on/
off the Heater Lamp so that the surface temperature of the Heat Roll becomes the target
temperature.
The surface temperature of the Heat Roll is detected by the Temp. Sensor (NCS: Non-
contact temp sensor) located at the center of the Heat Roll and the Temp. Sensor (STS:
Soft touch sensor). The Heater Lamp is turned off if the measured temperature is
higher than the target, on the other hand, the Heater Lamp is turned on if the measured
temperature is lower than the target.
If the STS comes off from the Heat Roll, correct temperature detection becomes
impossible. It may cause the FUSER UNIT to melt or take fire during warm-up process
because the printer heats up the FUSER UNIT according to the false temperature
which is lower than the actual one. In order to prevent this, the Heater Lamp is
automatically turned off if the temperature of the FUSER UNIT does not reach a
predetermined level within specified period of time.
The target temperature varies depending on conditions such as during standby,
printing, or executing process control. The target temperature also changes according
to the temperature detected by the SENSOR HUM TEMP (temperature and humidity
sensor), temperature difference between the center and the edges of the Heat Roll, print
mode, and input power voltage.
2.7.5.2 Cool-Down
When the printing is continued for a certain period of time, temperature distribution on
the Heat Roll surface becomes uneven. Cool-down is performed to equalize the surface
temperature of the Heat Roll by not feeding papers for a while. If the temperature of the
Heat Roll edges is high, the printer stops feeding paper until the temperature falls to the
target level.
2.7.5.3 Sensor Warm-up
The Temp.Sensor (NCS: non-contact temp sensor) located at the center of the Heat
Roll cannot detect temperature correctly if the temperature of the sensor itself is minus
5 °C or lower. If the printer detects the condition, it warms up the sensor until the
sensor temperature becomes 0 °C. This is called "sensor warm-up".
OPERATING PRINCIPLES Control
Revision C
65
Confidential