Functional Overview
Image Formation System
Fusing Stage
At the fusing station, the toner is fused into the paper by heat and
pressure to produce a permanent image. The paper passes between
a ceramic heating element protected by a thin, Teflon sleeve and a
soft pressure roller. This melts the toner and presses it into the
paper.
The ceramic heating element comes up to fusing temperature very
quickly, and thus does not require any power while the printer
is on STANDBY. These are the first Hewlett-Packard LaserJet
printers to employ this “instant-on” fusing system. Other laser
printers use a halogen heating lamp and require frequent warming
to maintain a minimum standby temperature. This feature saves
power while virtually eliminating the warm-up period.
The fusing temperature is monitored by the DC Controller PCA,
using a thermistor (TH901). The DC Controller maintains a
temperature of about 180° C during print mode. If the fusing
svstem overheats (about 215° C), a relay o~ens the Dower circuit to
the fusing heater, causing a Fuser Erro~ message. if the fusing
system exceeds 240° C, the thermal fuse will open, cutting off
power to the fuser.
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Fusin
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Toner
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Paper
Pressure
F
Roller
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Figure 5-17
Fusing Film and Pressure Roller
5-32
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