Toshiba 4511, 3511 manual PC4/AN4

(6) Temperature detection configuration

Thermistor is a device whose resistance decreases as it detects a higher temperature. Thus its input voltage to CPU changes and then CPU judges whether this change is normal or abnormal. If one of the fuser belt thermistors is broken, the control circuit judges that the fuser belt temperature is ex- tremely low and keeps turning the IH coil ON. As a result, the fuser belt temperature rises, and possibly activates the thermostat which is a safety protection device. To prevent this in advance, CPU works to detect whether each thermistor is broken or not.

Also, the thermistors constantly check the temperature of IH coil to prevent it from excessive heating by IH circuit abnormality, LGC circuit abnormality or thermistor abnormality. The thermistors auto- matically turn OFF the power when the temperature of IH coil exceeds the specified temperature.

+5

Sub thermistor

CPU

137

+5

Main thermistor

PC4/AN4

Front edge thermistor

138

+5

139

Fig. 16-406

PC5/AN5

PC6/AN6

16

November 2003 © TOSHIBA TEC 16 - 11 e-STUDIO3511/4511 FUSER UNIT/PAPER EXIT SECTION