Matsushita Electric Industrial Co., Ltd.

Takashi Niwa

Kazuho Sakamoto

Takahiro Matsumoto

Naoyoshi Maehara

Haruo Suenaga

Daisuke Bessyo

Shigeru Kusunoki

Takao Shitaya

Kimiaki Yamaguchi

Masao Maki

Ryuji Suzuki

Shunichi Nagamoto

Haruo Matsushima

Gas sensor

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 high voltage power source device which comprises an electric power source; a low voltage circuit constituted by an inverter circuit including a semiconductor switching element and a capacitor for converting an electric power from the electric power source into a high frequency electric power; a magnetron; a high voltage transformer for converting the high frequency electric power into a high voltage and supplying the high voltage to the magnetron; and a printed circuit board having an electric wiring system formed thereon for connection with and support thereon of the inverter circuit and a high voltage circuit for the voltage boosted by the high voltage transformer. The printed circuit board has separate areas defined therein, and the low and high voltage circuits are formed respectively on the separate areas of the printed circuit board. The printed circuit board includes a patterned grounding conductor formed at the boundary between the separate areas and also has either a plurality of openings defined therein so as to extend completely through a thickness of the printed circuit in alignment with the patterned grounding conductor, or a plurality of generally elongated electroconductive pieces each having opposite ends connected with the patterned grounding conductor.

High voltage power source device

A high-frequency heating apparatus comprises a semiconductor power converter which is supplied with electric power from a commercial power supply, a radio wave radiation section which is energized by the semiconductor power converter, a control section which controls the operation of a semiconductor element of the semiconductor power converter, and a start control section which controls the operation of the control section at the start time of the high-frequency heating apparatus. The start control section controls the operation of the control section so that the radio wave output power from the radio wave radiation section at the start time of the high-frequency heating apparatus becomes greater than that in the steady operation state thereof, whereby optimization of the performance and price of the heating apparatus can be realized.

High-frequency heating apparatus having start control device for

A magnetron feeding apparatus includes an inverter circuit for converting DC power into high-frequency power; a high-tension transformer for converting the high-frequency power into high-tension power to be supplied to the magnetron; an output voltage detector for detecting the output voltage of the high-tension transformer; an input current detector for detecting the input current into the inverter circuit; a power controller for controlling the operation of the inverter circuit in response to the output voltage detected by the output voltage detector and the input current detected by the input current detector.

Magnetron feeding apparatus and method of controlling the same

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

Control circuit for a humidity sensor

A turntable drive mechanism for a microwave oven having an oven-defining structure having a bottom wall and a hingedly supported door for selectively closing and opening an access opening leading into the interior of the oven-defining structure. The turntable drive mechanism has a turntable assembly removably positioned on the bottom wall for rotation about its own center through a plurality of rollers situated between the turntable assembly and the bottom wall, and a plurality of magnets. Cooperating with these magnets carried by the turntable assembly are magnets carried by a rotary carriage driven by a drive unit in one direction and situated below the bottom wall and externally of the oven-defining structure. Rotation of the turntable assembly is induced by rotation of the rotary carriage by the effect of magnetic forces of attraction developed through the bottom wall between the magnets on the turntable assembly and the magnets on the rotary carriage.

Growing community of inventors

Nara, Japan

Takashi Niwa