Ricoh G031, Service Manual

Page: 79 / 345

IMAGE FUSING
SM 2-35 G031/G032
Det
a
iled
De
s
c
ri
ptions
The fusing temperature is controlled using the fusing thermistor [A].
The CPU checks the output from the fusing thermistor once a second. The CPU
compares the current and previous temperature, then decides the power-on ratio
for the next second. To maintain the target temperature, the CPU controls the
fusing lamp power-on ratio as shown in the following table.
Current minus Target
Previous minus Current
Over –3
°
C Within –3
°
C
0
3
°
C Over +3
°
C
Over –3
°
C
100% 60% 60% 60% 0%
Within –3
°
C
100% 60% 60% 40% 0%
0 100% 60% 60% 40% 0%
3
°
C
100% 60% 60% 40% 0%
Over +3
°
C
100% 60% 0% 0% 0%
Ratio (%): The proportion of time that the fusing lamp power is on
2.6.8 OVERHEAT PROTECTION
If the hot roller temperature becomes greater than 230
°
C for more than 1 second,
the CPU cuts off the power to the fusing lamp. At this time, SC543 will be
generated.
Even if the thermistor overheat protection fails, there is a thermofuse in series with
the common ground line of the fusing lamp. If the temperature of the thermofuse
[B] reaches 169
°
C, the thermofuse opens, removing power from the fusing lamp.
At this time, the printer stops operating.
G031D528.WMF
[B]
[A]