| 摘要 |
PURPOSE:To improve the safety by means of a no-load detector adapted to shut off the power supply to the heating coil by accurately detecting whether the load to the heating coil is zero or close to the zero. CONSTITUTION:This induction heating apparatus is equipped with a heating coil, a switching circuit 2 for feeding power to the coil 1, and a detecting coil 3 for detecting a resonance frequency F in a resonance circuit including the coil 1. A resonance frequency F, which varies with change in the load to the heating coil, detected with the detecting coil 3 is fed to the switching control circuit 4 while converted to a pulse signal with a waveform shaping circuit 5, and then, sent to a comparator 6 and a voltage converter 7. The comparator 6 detects whether the load to the heating coil is zero or close to zero and works to shut off the power supply to the coil 1. |
