IMAGE FUSING AND PAPER EXIT
SM 6-49 B044/B045/B046
Detailed
Descriptions
6.16.6 FUSING TEMPERATURE CONTROL
Overview
[A]: Thermistor
[B]: Thermoswitch
[C]: Thermofuse
The CPU checks the thermistor
[A] output once per second, and calculates the power-on ratio for the next second
based on (a) current temperature, (b) the temperature 1 second earlier, and (c)
the target temperature.
The target fusing temperature drops somewhat over time, as the machine's
overall state changes with continued use. For normal copying, the target starts at
180°C, then drops to 170°C after one minute.
Fusing Temperature Control for Thick Paper
Target temperature goes up 10°C if the user selects thick-paper mode.
6.16.7 OVERHEAT PROTECTION
Primary protection is provided by the thermistor and CPU, with backup by a
thermoswitch and secondary backup by a thermofuse. (See illustration above.)
Protection 1: If the CPU determines from the thermistor that the hot roller has
stayed above 230°C for more than 1 second, it cuts the power to
the fusing lamp and issues SC543.
Protection 2: The thermoswitch (connected in series with the fusing lamp's
common ground) opens if it reaches 190°C, cutting power to the
lamp. If you restart the machine without correcting the problem, the
machine will issue SC541.
Protection 3: The thermofuse (which is farther from the lamp than the
thermoswitch) opens at 131°C, cutting power to the lamp.
B046D502.WMF
[A]
[B]
[C]
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