Types and Number of Sensors

NC Sensors

Sensor Type	NC Sensor (Fusing Temperature Sensor)
Type	Infra-red, non-contact sensor
Function	The machine controls the rotation of the fusing unit rollers at standby by reading the temperature of the fusing belt. The end and center of the fusing belt by are monitored by sensors to ensure that fusing unit temperature is always within a safe range. This sensor monitors the temperature of the pressure roller and controls the operation of the pressure roller lamp.
Location, Function	Heating Roller	Two Fusing Temperature Sensor (Heating Roller End) Fusing Temperature Sensor (Heating Roller Center)
	Hot roller	One: Fusing Temperature NC Sensor (Hot Roller Center)
	Pressure Roller	One: Fusing Temperature Sensor (Pressure Roller Center)

Thermistors

Sensor Type	Thermistors
Type	Contact sensor. A variation in temperature changes resistance which can be measured.
Function	Monitors the temperature of the heating roller and pressure roller. These thermistors are also a safety device.
Location, Function	Heating Roller	One: Fusing Heat Roller Thermistor (Rear)
	Hot roller	None
	Pressure Roller	One: Pressure Roller Thermistor

Thermostats

Sensor Type	Thermostats
Type	Two strips of metal of different conductivities are joined, heat warps the shape due to these differences and breaks the circuit.
Function	These are provided as safety devices. If a high temperature trips either or both thermostats, power supply to the fusing lamps is shut down. This thermostat is also a safety device that monitors the temperature around the pressure roller.
Location, Function	Heating Roller	Two: Heating Roller Thermostat (Center) Heating Roller Thermostat (End)
	Hot roller	None
	Pressure Roller	One: Pressure Roller Thermostat

Thermopiles

Sensor Type	Thermopiles (in main machine above fusing unit)
Type	Infra-red, non-contact sensor
Function	These thermopiles are inside the main machine located above and to the right of the fusing unit. These are also safety devices.
Number/Name	Fusing Unit	Three: Thermopile: Heating Roller Center Thermopile: Heating Roller Front Thermopile: Extended

The NC sensors in the fusing unit, and the thermopile attached to the main machine on the right side of the fusing unit, both employ infra-red.
The thermopile, extremely sensitive to temperature change, resides apart from the fusing unit. The NC sensors, slightly less sensitive to temperature than the thermopile, are located inside the fusing unit to control the fusing temperature.