Patent ID: 7860414

Claim:
A heating apparatus comprising: an exciting coil provided in close vicinity of a heated body having a conductive layer; a capacitor connected serially or in parallel with the exciting coil; a switching element that generates a high frequency current by turning a direct current on and off, and that supplies the high frequency current to the exciting coil and the capacitor; a specifying unit that specifies an electric value relating to high frequency current to be supplied to the exciting coil; an output unit that outputs, to the switching element, a driving signal to turn on the switching element for a period determined in correspondence with the electric value specified by the specifying unit; a voltage detection unit that detects a flyback voltage value generated in a resonance circuit including the exciting coil and the capacitor; a reference value output unit that outputs a flyback voltage reference value; and an abnormality detection unit that calculates a voltage change ratio between the detected flyback voltage value and the flyback voltage reference value, and determines that an abnormality in the heated body exists when the voltage change ratio exceeds a predetermined value; wherein the detected flyback voltage value and the flyback voltage reference value correspond to a same electric value specified by the specifying unit.