| 摘要 |
PURPOSE:To prevent a fixing device from being overheated, by providing a fixing roller having heating rollers which have incorporated a heat source in at least one of them, and also, installing a temperature sensor in the vicinity of the heating roller. CONSTITUTION:When a power source switch 5 is turned on, and power conductive is started, a warm-up timer 4 starts its operation, and until the warm-up time elapses, a 'H' signal is outputted to an AND circuit 7. The circuit 7 outputs a 'H' signal so as not to operate an abnormality detecting circuit 9, and inputs it to a temperature control circuit 8. The circuit 8 outputs a 'L' signal. In this case, since a timer is not operating, an OR circuit 11 outputs 'L', and a solid-state relay 13 becomes on, therefore, a heat source 1 becomes on. By this heat source 1, a temperature sensor is heated for a prescribed time, and after this prescribed time, an output value of the temperature sensor is read. In this state, when the output value of the temperature does not reach a value of the time of a fixing temperature, or when the output value of the temperature sensor has been varied from the value of the time of the fixing temperature at the time of controlling temperature, it is decided that said device is disconnected or is defective, and the heat source 1 of the fixing roller is turned off.
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