Transfer Unit; Drive; Fusing Unit; Thermostat - Ricoh BP20 Service Manual

6.3.2 TRANSFER UNIT

A PTL (Pre-transfer Lamp) and a transfer roller migrate toner from the OPC drum
onto the paper. The PTL shines additional light onto the OPC, which reduces the
electrical charge on the surface of the OPC drum and improves the transfer
efficiency. The transfer roller then migrates the toner from the OPC drum to the
paper.

6.3.3 DRIVE

The main board supplies power to the paper drive assembly. The main motor
supplies power to the following:
• Paper feed unit
• Toner cartridge

• Fusing unit

• Pick-up, feed and exit rollers
6.3.4 FUSING UNIT
The fusing unit consists of the following:
• Fusing lamp
• Hot roller
• Pressure roller
• Thermistor and thermostat.
The fusing unit uses pressure and heat to melt and bond toner into the paper.

Thermostat

The thermostat cuts off the power to the fusing lamp, which prevents machine
overheating. Power to the fusing lamp is cut when the thermostat temperature
reaches 160 C.

Thermistor

The thermistor detects the surface temperature of the hot roller. This information
goes to the main processor, which uses this information to regulate the
temperature of the hot roller.
Hot Roller
The fusing lamp heats the surface of the hot roller. Toner is melted and adheres to
the surface of the paper as the paper passes between the hot roller and pressure
roller. The surface of the hot roller is coated with Teflon to ensure that toner does
not remain on the roller surface.
Pressure Roller
The pressure roller is mounted under the hot roller. The roller itself is made of a
silicon resin, while the surface of the roller is coated with Teflon. This ensures that
toner does not remain on the roller surface.
SM 6-9
SYSTEM LAYOUT
G144/G145