| 摘要 |
PROBLEM TO BE SOLVED: To enable proper heating by judging whether a material to be heated moves or not based on changes of a frequency detected by a frequency change detection means when the material to be heated is heated by a first output above a specified output selected by an output select means when heating is started, estimating a proper output when it moves, and reducing an output down to a second output below the specified output. SOLUTION: When a heating coil 4 let a high frequency magnetic field act on a material to be heated 6 and the material to be heated 6 is heated due to eddy current loss caused by it, a user selects an output using an output select means 8. Consequently, a phase difference setting means 9 sets a phase difference beyond a required output, and a phase control means 10 controls an inverter drive circuit 7 based on it to execute a first output. Whether the material to be heated 6 moves or not is judged based on changes of a frequency detected by a frequency change detection means 11. When it moves, a proper output is estimated, and an output is reduced down to a second output below a specified output to prevent a travel of a vessel and perform proper heating, even if a weight of the material to be heated 6 differs. |
