| 摘要 |
PURPOSE:To shorten the rising time of a heater while a magnetron is cold, by performing control so that one of the outputs from a current sensing part and from a voltage sensing part which is the greatest will become a specified value by the use of an inverter circuit. CONSTITUTION:This arrangement includes an input current sensing part 8 to sense the current from commercial mains 1 and an output voltage sensing part 112 to sense the voltage of a high voltage power supply. An inverter circuit 24 controls so that one of the outputs from this current sensing part 8 and from voltage sensing part 12 which is the greatest will become a specified value. That is, the output voltage is controlled so that the output voltage will become specified value in the period until a magnetron 7 begins oscillating, while the input current is controlled so that the input current will become specified value when magnetron begins oscillating. Accordingly the input current from the commercial mains attains the specified value in the shortest time regardless of whether the magnetron is cold or warm, so that it requires no wasteful time nor excessive voltage/current is applied to the magnetron under the process, which does not shorten the life of service.
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