Fusing; Thermostat; Thermistor; Heat Roller - Ricoh B173 Service Documentation

6.2.4 FUSING

The fusing unit contains a heat lamp, heat roller, pressure roller, thermistor, and
thermostat. With pressure and heat, the fusing unit fuses (melts) the toner onto the
paper. This completes the printing job.

Thermostat

The thermostat cuts power if the heat lamp or the heat coil of the heat roller gets
too hot.

Thermistor

The thermistor checks the surface temperature of the heat roller, and regulates the
temperature of the heat roller.

Heat Roller

The heat roller gets heat from the heat lamp. Then it heats the surface of the
paper. The heat roller is coated with Teflon to prevent the melted toner from
sticking to the heat roller.

Pressure roller

The pressure roller, located below the heat roller, is made of silicon resin, and the
surface of the roller is coated with Teflon. The toner is fused onto the paper when
the sheet of paper passes between the heat roller and the pressure roller.

Safety Features

There are 3 procedures to prevent the machine from overheating.
• 1st: Hardware cuts power when the machine gets to an overheat condition.
• 2nd: Software cuts power when the machine gets to an overheat condition.
• 3rd: Thermostat power.
Safety device
• Power is removed from the fusing unit when the front cover is open.
• Overheat safety device for customer.
• Keeps the surface temperature of the fuser cover less than 80°C. A customer
caution label is adhered inside of the rear cover.
SM 6-3
SYSTEM LAYOUT
B173