Matsushita Electric Industrial Co., Ltd.

Takao Shitaya

Kazuho Sakamoto

Shigeru Kusunoki

Daisuke Bessyo

Naoyoshi Maehara

Takahiro Matsumoto

Takashi Niwa

Haruo Suenaga

Makoto Mihara

Takeshi Nagai

Hiroshi Fukuda

Masahiko Itoh

A high-frequency heating apparatus comprises an inverter including a semiconductor switch and a resonance capacitor, a boosting transformer for a supplying high-voltage power and heater to a magnetron an inductance device inserted in the heater circuit of the magnetron, and an inverter control unit for controlling the semiconductor switch. The inverter control unit is controlled by a start control at the start time of the inverter so that the conduction time of the semiconductor switch becomes shorter than that under a normal operating condition and the non-conduction time thereof becomes longer than that under a normal operating condition and so that the switching period of the semiconductor switch becomes substantially an integral multiple of a resonance period of the resonance circuit formed by the resonance capacitor, whereby the operating frequency of the inverter at the time of starting thereof becomes substantially equal to its normal operating frequency.

High frequency heating apparatus using inverter-type power supply

A self-cleaning type cooking oven with a cooking chamber which has a function to pyrolytically eliminate food soils accumulated on walls of the cooking chamber. The cooking oven includes a heater for supplying heat into the cooking chamber so as to allow to pyrolytically degrade the food soils and an exhausting passage coupled to the cooking chamber to exhaust gases generated due to the pyrolytical degradation to an ambient atmosphere. In the exhausting passage is provided an oxidizing catalyst which oxidizes the gases introduced thereinto for exhausting and also provided a gas sensor to detect a gas component therearound. Also included in the cooking oven is a heat control unit electrically connected to the heater for controlling heat supply into the cooking chamber, the heat control unit being responsive to a gas signal therefrom to determine a heating time period for chamber cleaning. With the temperature of the cooking chamber being kept at a predetermined cleaning temperature, the heat control unit samples the gas signal at a given time interval to detect a variation of amount of the gas component and detect an inflection point from decreasing to increasing or vice versa in the gas-component variation to determine the heating time period in conjunction with the inflection point, the food soils being substantially degraded by heating during the heating time period.

Cooking oven having function to automatically clean soils attached to

A power supply for a magnetron includes a rectifying circuit, a switching circuit, and a transformer. The rectifying circuit converts an ac-power source signal into a dc-power source signal. The switching circuit converts the dc-power source signal output from the rectifying circuit into a high-frequency signal in accordance with a driving circuit. A transformer connected to the switching circuit converts the high-frequency signal into a high-voltage high-frequency signal for driving the magnetron. The transformer includes a primary winding connected to the switching circuit, a secondary winding connected to the magnetron, a tertiary winding connected to a cathode heater of said magnetron, and a fourth winding connected to the driving circuit. The coupling coefficient between the fourth winding and the second winding is larger than the coupling coefficient between the fourth winding and the primary winding.

Power supply for a magnetron having a rectifying circuit, switching

A power feeding apparatus which is used in a high-frequency heater or the like, is further power-converted by a transformer after the power provided by the power supply such as commercial power supply or the like has been converted into the high-frequency power by a transducer including a semiconductor, feeds the converted power into the load having the unidirectional electrical current characteristics of magnetron or the like. The generating voltage is dropped so that the stable power may be fed without the corona discharge and the acr discharge to be caused, the insulating withstand voltage between the windings of the transformer, the pulling of the wirings, and the insulating withstand voltage may be reduced.

Power feeding apparatus

A heating oven has a weighing apparatus, and a weight of a food material placed on a tray in a heating cavity is conveyed by Roberval mechanism. The conveyed weight is measured by the weighing apparatus, and the heating oven controls heating time, heating power and the like responding to the measured weight of the food stuff.

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Yamato Kouriyama, Japan

Takao Shitaya