Fusing I - Epson AcuLaser C8500 Service Manual

EPSON AcuLaser C8500

2.5.10 Fusing I

FUSER ASSY
Along with fixing unfixed toner transferred to paper with heat and pressure, the
FUSER ASSY transports the paper before and after fixing. The FUSER ASSY
consists of the MAIN FUSER ASSY and FUSER ASSY.
MAIN FUSER ASSY
The MAIN FUSER ASSY consists of the HEAT ROLL, PRESSURE ROLL,
H/R HEATER, P/R HEATER and TEMP. SENSOR ASSY.
The HEAT ROLL is a hollow metal roll whose surface is coated with a
layer of rubber that adds heat for fixing toner on paper.
The PRESSURE ROLL is a hollow metal roll whose surface is coated
with a layer of rubber that adds heat and pressure for fixing toner on
paper.
The H/R HEATER is a halogen lamp with a sealed heating coil that
serves as the source of heat for the HEAT ROLL. The H/R HEATER is
contained in the hollow inside of the HEAT ROLL, and raises the
temperature of the HEAT ROLL to a temperature where fixing is
possible.
The P/R HEATER is a halogen lamp with a sealed heating coil that
serves as the source of heat for the PRESSURE ROLL. The P/R
HEATER is contained in the hollow inside of the PRESSURE ROLL,
and raises the temperature of the PRESSURE ROLL to a temperature
at which fixing is possible.
The TEMP. SENSOR ASSY is sensor for detecting temperature that
uses a thermistor (device for which resistance changes according to
temperature). Making constant contact with the HEAT ROLL, the
TEMP. SENSOR ASSY detects the surface temperature of the HEAT
ROLL. The TEMP. SENSOR ASSY turns the H/R HEATER and P/R
HEATER ON/OFF (lamp on/off control) and prevents primary
overheating based on the detected temperature.
The Thermostat is directly connected to the power supply circuit for the
H/R HEATER and P/R HEATER. If the TEMP. SENSOR ASSY device
for preventing primary overheating fails to operate, the heat causes the
Operating Principles
contact inside the Thermostat to open, forcibly interrupting the power
supply to the H/R HEATER and P/R HEATER, thus preventing
secondary overheating.
The Thermal Fuse is directly connected to the power supply circuit for
the H/R HEATER and P/R HEATER. If the TEMP. SENSOR ASSY
device for preventing primary overheating by fails to operate, the
Thermal Fuse is melted by heating, forcibly interrupting the power
supply to the H/R HEATER and P/R HEATER, and thereby preventing
tertiary overheating.
The FUSER EXIT SENSOR detects passage of paper by change in
position of the FUSER EXIT ACTUATOR.
The H/R FINGER prevents paper from wrapping around the HEAT
ROLL.
The P/R FINGER prevents paper from wrapping around the
PRESSURE ROLL.
Figure 2-42. Fusing I
Revision C
2-37