Introduction - Ricoh FT7770 Service Manual

FUSING

1. Introduction

The toner powder image is fused onto the copy paper by the hot roller and
pressure roller.
w).
Both lamps turn on during initial warm-up, and as necessary to keep
the hot roller at the operating temperature (185°C).
maximum power consumption, the 550 watt lamp does not operate during the
copy cycle. The CPU monitors the hot roller temperature through a thermis-
tor. A thermofuse (169°C) protects the unit against overheating.
The oil supply pad applies silicone oil to the hot roller, while the metering
blade spreads oil evenly and removes excessive oil. Silicone oil has several
purposes: it keeps the rollers clean by reducing the amount of toner trans-
ferred to them, it reduces adhesion between paper and the hot roller, and it
reduces paper curl.
The hot roller is cleaned by a rubber cleaning blade and the oil supply pad.
The pressure roller is cleaned by a steel cleaning roller Toner adheres to
steel more readily than to silicone rubber.
The hot roller has two internal fusing lamps (550 W/1,100
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30 April, '89
However, to limit the