Toshiba e-studio 250 - Temperature Detection by the Thermistor

December 2002 TOSHIBA TEC 14 - 9 e-STUDIO160/200/250 FUSER UNIT/EXIT UNIT
14.6.2 Temperature detection by the thermistor
* The detection circuits for heater thermistors 1 and 2 are equal to each other. Here, heater thermistor 1
is described.
Fig. 14-6-2
• The input voltage is obtained by dividing the +5V among R342, Heater thermistor 1 and R337.
• The surface temperature of the heat roller varies.
• The resistance of the heater thermistor 1 changes.
• The input voltage changes.
• The input voltage is converted to digital data by the A/D converter and output to the register of the
system control GA. The CPU reads this value and detects a change in the data to judge if the heat roller
temperature is normal or abnormal.
14-06-02
+5V
R342
Heater
thermistor 1
R337
SG
TH ADCDO
+5V
IC23
A/D
converter
IC34
System
control
GA
IC66
CPU