Patent ID: 9615406
Date: 2017-04-04
CPC Classifications: H05B

Claim:
1. An image forming apparatus for setting different current shut-off thresholds for temperatures of a magnetic material thereof above and below the Curie temperature, comprising: a magnetic flux generating device configured to generate a magnetic flux; a fixing unit configured to generate heat in accordance with the magnetic flux from the magnetic flux generating device, the fixing unit having a heating element including the magnetic material heated by the magnetic flux from the magnetic flux generating device; a power source configured to supply a current to the magnetic flux generating device; a current detection unit configured to detect a value of the current supplied to the magnetic flux generating device; a temperature sensor configured to detect a temperature of the heating element; an output overcurrent detection unit that receives the output of the temperature sensor and the output of the current detection unit, wherein the output overcurrent detection unit generates a first threshold value for comparing to a value representing the current value supplied to the magnetic flux generating device if the heating element is below the Curie temperature, and generates a second threshold value for comparing to a value representing the current value supplied to the magnetic flux generating device if the heating element is above the Curie temperature, wherein the output overcurrent detection unit outputs an abnormal status signal, instructing stopping current supply from the power source to the magnetic flux generating device, i) when the value representing the current value detected by the current detection unit is above the first threshold value and the temperature of the heating element detected by the temperature sensor is below the Curie temperature, and ii) when the value representing the current value detected by the current detection unit is above the second threshold value, and the temperature of the heating element detected by the temperature sensor is above the Curie temperature; and a control unit receiving the abnormal status signal from the output overcurrent detection unit and stopping the supply of the current to the magnetic flux generating device from the power source in response to receiving the abnormal status signal from the output overcurrent detection unit.