| 摘要 |
PROBLEM TO BE SOLVED: To vary a frequency for minimizing a reflected wave according to a change while heating food. SOLUTION: Detection circuits 12a-12d for incident or reflected waves attenuate an incident wave power supplied to a heating chamber 5 or reflected wave power returned from the heating chamber 5 to a small signal of a control unit level. The circuits are configured such that in a pre-search term of low power operation, the voltage applied is decreased while decreasing the attenuating effect to the detection circuits 12a-12d, while in a main search term for high power operation to actually heat a heated object 9, the attenuating effect is increased and the voltage applied is reduced to allow the control unit 4 to always control and monitor the incident wave and the reflected wave while heating to avoid breakage of a semiconductor element, and only when the reflected wave is increased, pre-search is performed with a low output. Thus, the frequency of the pre-search term can be decreased. COPYRIGHT: (C)2010,JPO&INPIT
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