C. Controlling the Fixing TemperatureThe surface temperature of the machine's upper fixing roller is monitored by the mainthermistor (TH1); measurements are taken and communicated to the microprocessor onthe DC controller PCB.The DC controller PCB uses these measurements to vary the main heater drivesignal (MHRD) and the sub heater drive signal (SHRD).The sub thermistor (TH2) is mounted at the rear of the upper fixing roller to check foran abnormal increase in temperature.Figure 6-102Upper fixing rollerFixinglowerrollerPS47Fixing assembly outlet paper detection signal (FXDEL)Fixing assembly inlet paper detection signal (FXCJS)Cleaning belt length detection signal (CBOP)Main thermistor signal (TH1)Main heater drive signal (MHRD)Sub heater drive signal (SHRD)Main thermistor (TH1)AC power supplyTPICleaning beltguide plateThermalswitchSSRAC driver PCBPS11PS52Sub thermistor signal (TH2)DC controller PCBSub thermistor(TH2)COPYRIGHT © 1997 CANON INC. CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)CHAPTER 6 FIXING SYSTEM6-5
