| 摘要 |
PROBLEM TO BE SOLVED: To precisely check the presence or the absence of paper winding and thermistor separation by increasing an error detection temperature gradient from a normal one and determining the appropriateness of the temperature gradient while a fixation heater is turned ON after the release of a jam. SOLUTION: A fixation device 1 is heated by a heater 4. A thermistor 5 is arranged to contact with a fixation roller 3 to detect the temperature on the surface of the roller 3. Supply of the power to the heater 4 is controlled by a temperature circuit in accordance with the detected temperature of the thermistor 5 so that the surface temperature of the roller 3 is adjusted to a prescribed heat fixation temperature. In the above, the temperature gradient of the surface temperature of the roller 3 is detected while the heater 4 is turned ON. If the detected gradient is less than the error detection temperature gradient, the heater 4 is forcibly turned OFF. Furthermore, in order to recognize the generation of a jam, the error detection temperature gradient is made steeper than a normal gradient and the appropriateness of the temperature gradient is discriminated while the heater 4 is turned ON after the release of a jam.
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