| 摘要 |
PURPOSE: To lower an interference sound by eliminating the sound of interference due to a difference among oscillation frequencies resulting from the mutual interference of magnetic fields from a plurality of heating coils at the time of the concurrent operation thereof. CONSTITUTION: The oscillation frequency of the second inverter 3a is detected with the second frequency detection means 13a. Also, a frequency recognition signal generation means 14 is provided for outputting a frequency recognition signal showing the oscillation frequency of the second inverter 3a at discrete N steps, on the basis of the result of the detection. Furthermore, a frequency correction means 15 raises the frequency of the inverter having a low frequency, so as to keep an oscillation frequency difference between the inverters 3a and 3b within 1kHz, upon receipt of the frequency recognition signal and a signal from the first frequency detection means 13b for detecting the frequency of the first inverter 3b. |
