Matsushita Electric Industrial Co., Ltd.

Naoyoshi Maehara

Takahiro Matsumoto

Daisuke Bessyo

Shigeru Kusunoki

Kazuho Sakamoto

Yuji Nakabayashi

Takashi Niwa

Haruo Suenaga

Takao Shitaya

Makoto Shibuya

Makoto Mihara

Kazushi Yamamoto

Kimiaki Yamaguchi

Takashi Uno

Shinichi Nakane

Hiroshi Fujieda

Yoshifumi Moriya

Tatsuo Saka

Noriyuki Yoneno

Kenkichi Hashido

Yoshitomo Fujitani

Miki Moriguchi

Susumu Kiritoshi

Shiro Takeshita

Naoko Yanagida

Hiroshi Hirata

An oven with a humidity conditioner is capable of cooking food by appropriately humidifying or dehumidifying it while the amount of steam contained in an oven cavity is being regulated. The oven includes a heater or magnetron for heating the food accommodated in the oven cavity, a humidity regulator for regulating the humidity inside the oven cavity, a cooking method selector for selecting a cooking method, and a controller for controlling the humidity regulator in response to a signal from the cooking method selector to selectively humidify and dehumidify the interior of the oven cavity.

Electric combination oven with humidity conditioner

High-frequency heating apparatus mounted on a motor vehicle

High-frequency heating device employing switching type magnetron power

A high frequency heating arrangement includes a power converting unit with one or more semiconductor devices which dissipates a slight heat loss. A magnetron receives an output from the power converting unit and supplies electromagnetic waves to a heating chamber. The magnetron dissipates a heat loss that is relatively larger than that of the power converting unit. A cooling fan has a motor which dissipates a heat loss which is relatively smaller than that of the power converting unit. The cooling fan is for cooling the power converting unit and the magnetron. A case is provided in which at least the power converting unit and the magnetron are housed and which is made of an electricity-conductive material. A cooling air passage, along which the motor and the case are arranged, and through which air flows from said cooling fan is provided. Air sent from the cooling fan first cools the motor, then cools at least a portion of the power converting unit, and finally cools the magnetron.

High frequency heating apparatus utilizing an inverter power supply

A high frequency heating apparatus includes a unitary structure including a magnetron for generating a microwaves, an inverter power supply for supplying a high voltage electric power to the magnetron, and a cooling unit for cooling the magnetron and the inverter power supply, all of which are accommodated within a common metallic casing. The unitary structure is provided at least one of a detector for detecting an operating condition of the cooling unit and a safety device including a detector for detecting a mounting of the metallic casing to a cabinet. For avoiding an electric shock, the unitary structure is divided into high and low voltage portions and the magnetron and the inverter power supply are electrically connected directly to each other without relying on the unitary structure so as to thereby accomplish a structure effective to minimize noise and to improve the reliability and the safety factor.

High frequency heating apparatus utilizing inverter power supply

An electric cooking apparatus includes a single power converter section for converting power supplied from an external AC power source. A heating-energy radiator section receives the converted power from the power converter section and radiates heating energy to a heating chamber. A battery is also provided for supplying power to the power converter section such that a sum of the power from the external AC power source and the battery is converted by the power converting section when an instantaneous voltage of the external AC power source is smaller than a predetermined voltage level, which predetermined voltage level is smaller than a maximum instantaneous voltage of the external AC power source.

Electric cooking apparatus adapted for generating high power output

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-frequency heating apparatus comprises a power supply including a commercial power supply or a battery, a frequency converter for converting the power of the power supply into high-frequency power, a boosting transformer for increasing the voltage of the output of the frequency converter, and a magnetron for receiving the output from the boosting transformer. The apparatus further comprises a shield member made of a non-magnetic conductive material and forming a substantially electrical open loop in the winding direction of the primary winding between the primary and secondary windings of the boosting transformer. The shield member is connected to the core or the housing of the boosting transformer thereby substantially containing a high-voltage circuit in the shield space. High safety of the high-frequency heating apparatus is thus assured without grounding the housing.

High-frequency heating apparatus using frequency-converter-type power

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

In a high-frequency heating device for driving a magnetron at a high frequency between 20 and 50 KHz, the magnetron is provided with a plurality of choke coils, each of which consists of a magnetic core having a sectional area between 40 to 70 mm.sup.2 and an electric wire around the magnetic core and having a diameter between 1.2 and 1.6 mm. In such a construction, the magnetron can be driven, using the high frequency with reduced thermal loss of the choke coil and restrained heat generation.

High-frequency heating device

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 power feed apparatus in which a means for by-passing the current reversely biasing the load is used for the normally used rectification means when the power converted by the transformer is fed to the reversely blocking characteristics like magnetron, whereby the price is lower and the shape is more compact without the use of the rectifier, because of the combination construction of the reverse bias current by-pass means and the inductance element provided in the load current path with respect to the non-linear load like the magnetron.

Power feed apparatus for load having reverse blocking characteristics

In an exhaust passage (37) of a heating apparatus, a piezoelectric device sensor (26) is provided for detecting the heating condition of a heated object (32), such as food in a microwave open heating chamber (31). A piezoelectric device of the sensor may be contained within a metal casing (53) and be hermetically sealed. An output signal from the piezoelectric device sensor is processed by circuitry including an amplifier (27) having a predetermined frequency response so that only particular frequency components lower than that of a conventional a.c. supply are amplified and then compared with a threshold to detect whether a sufficient amount of moisture of hot steam is emitted from the object in the heating chamber of the heating apparatus. The invention may be applied to prevent overheating of food in a microwave oven, temperature control of chemical processes, or the like, to control heating time.

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Nara, Japan

Naoyoshi Maehara