Canon M3010 Series Service Manual

Contents

Canon M3010 Series Service Manual Manual pdf 36 page image

22 2-212-21Technical Overview > Fixing System > Various Control Mechanisms > Protective FunctionsTechnical Overview > Fixing System > Various Control Mechanisms > Protective Functions2) Protection function by fixing heater safety circuitFixing Heater (H1) safety circuit monitors the Thermistor (TH1) temperature consistently.When Thermistor (TH1) reaches approx 235 deg C, it determines that the Fixing Heater (H1)is overheating and the fixing heater safety circuit turns OFF the relay drive circuit to shutthe power supply to the Fixing Heater (H1).3) Protection function by Temperature Fuse (TP1)When the Fixing Heater (H1) temperature rises abnormally and Temperature Fuse (TP1)temperature reaches approx 226 deg C, Temperature Fuse (TP1) opens to shut the powersupply to the Fixing Heater (H1).● Failure detectionWith this machine, 10 types of failure detection are available.1) Initial startup failure detectionWhen temperature of the Fixing Assembly does not exceed 50 deg C within 1.48 sec afterthe start of temperature control performed at initial rotation, it is judged as initial startupfailure.2) Initial Thermistor open detectionWhen temperature of the Fixing Assembly does not exceed 35 deg C within 1.48 sec afterthe start of temperature control at warm-up rotation temperature control or at cleaningmode, it is judged as Thermistor open failure.3) Short circuit of Thermistor/abnormal high temperature detectionWhen temperature of the Fixing Assembly is 220 deg C or higher for 30 consecutive timesby monitoring the temperature for every 5 msec, it is judged as Thermistor short circuitfailure. In addition, this function also doubles as abnormal high temperature detectionfunction of the Fixing Assembly.4) Abnormal low temperature detectionAfter temperature of the Fixing Assembly exceeds 50 deg C at least once, monitortemperature of the Thermistor (TH1) for every 5 msec. It is judged as heater abnormallow temperature when the following condition is detected 240 consecutive times: thetemperature is 100 deg C or lower while paper is at fixing nip, or it is 55 deg C or lowerduring paper interval temperature control or at cleaning mode.5) Thermistor open detectionAfter temperature of the Fixing Assembly exceeds 50 deg C, monitor temperature of theThermistor (TH1) for every 5 msec. When it is detected that the temperature is lower than20 deg C for 6 consecutive times, it is judged as Thermistor open failure.6) Startup failure detectionIf temperature of the Fixing Assembly is 100 deg C or higher when the machine becomes inpickup enabled state after entering fixing low voltage inlet sequence, it is judged as startupfailure.7) Thermistor high temperature detection 2Temperature of the Thermistor (TH1) is monitored every 200 msec during Fixing Assemblycontrol. If the temperature is equal or higher than "detection temperature of Thermistor hightemperature detection 2", increase the value of "high temperature detection counter" by 1(+1). If not, decrease the value by 1 (-1). When the value of "high temperature detectioncounter" becomes +50, it is judged as a Thermistor high temperature failure. The defaultand minimum value of "high temperature detection counter" is 0.The "detection temperature of the Thermistor high temperature detection 2" is set to 195deg C when the target control temperature is 180 deg C or less. When the target controltemperature is above 180 deg C, it is set to "target control temperature + approx. 15 degC".8) Thermistor low temperature detection 2)Temperature of the Thermistor (TH1) is monitored for every 200 msec when paper is atfixing nip during the Fixing Assembly control. When the temperature is lower than 135 degC (120 deg C), increase the value of low temperature detection counter by 1 (+1). Whenit is 135 deg C (120 deg C) or higher, decrease the value by 1 (-1). When the value of lowtemperature counter becomes +150, it is judged as Thermistor low temperature failure. Thedefault and minimum value of low temperature detection counter is 0.9) Frequency detection circuit error (230V models only)When frequency measurement is not completed within 3255 msec after the completion ofprevious frequency measurement, it is judged as frequency detection circuit error.10) Thermistor high temperature detection 3Temperature of the Thermistor (TH1) is monitored every 5 msec, and if the temperatureis equal or higher than "detection temperature of Thermistor high temperature detection2 + approx. 15 deg C" more than 30 consecutive times, it is judged as a Thermistor hightemperature failure.