Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Panasonic Intellectual Property Management Co., Ltd.

Izuo Hirota

Takahiro Miyauchi

Akira Kataoka

Yuji Fujii

Atsushi Fujita

Hiroshi Tominaga

Katsuyuki Aihara

Tomoya Fujinami

Nobuyoshi Makio

Kenji Watanabe

Keiko Isoda

Naoaki Ishimaru

Koji Niiyama

Fumitaka Ogasawara

Masafumi Sadahira

Hideki Sadakata

Takayuki Urata

Yoshiaki Ishio

Toshihiro Keishima

Sadatoshi Tabuchi

Kouji Niiyama

Hideki Omori

Hirofumi Nakakura

Takeshi Kitaizumi

Shintaro Noguchi

Kiyoyoshi Takada

Hirofumi Inui

Manabu Takahashi

Mitsuhiro Sano

Akihiro Umeda

Disclosed is an induction cooking device that is not likely to be affected by induction heating and wherein boiling-over can be detected. An induction cooking device has: a top plate on which a cooking container is placed; a heating coil that generates an induction magnetic field for heating the cooking container; a heating control unit that controls the heating power of the cooking container by controlling the high-frequency current supplied to the heating coil; electrodes disposed in a lower surface of the top plate; and an electrostatic capacity detector that detects changes in electrostatic capacity occurring in the electrodes when articles to be cooked contact with the top plate. When the electrostatic capacity detector senses changes in the electrostatic capacity of the electrodes, the heating control unit decreases or stops the heating power of the cooking container, and the electrodes are disposed outside of the outer circumference the heating coil.

Inductive heating apparatus

There is provided a heating/cooking equipment capable of accurately determining boiling over. The heating/cooking equipment includes: a top plate () connected to a reference potential; a heating unit () configured to heat an object to be heated placed on the top plate; an electrode () arranged under the top plate; a capacitance detecting unit () configured to detect the electrostatic capacitance of the electrode; a boiling over detecting unit () configured to detect whether or not a material to be cooked in the object to be heated has boiled over on the top plate, based on a value of the electrostatic capacitance detected by the capacitance detecting unit; and a control unit () configured to control the heating operation of the heating unit based on a boiling over detection result from the boiling over detecting unit. The capacitance detecting unit () detects a change in the electrostatic capacitance of the electrode by exploiting capacitive coupling between the electrode and the reference potential which is enhanced by increase in a boiled over amount of the material to be cooked with moisture contained in the material to be cooked functioning as a dielectric when the material to be cooked boils over on the top plate.

Heating/cooking equipment

An induction heating device includes the following elements: a resonance circuit; a power factor improvement circuit for boosting rectified output, supplying the output to an inverter, and improving the power factor of a commercial alternating current; and a load material detector for detecting the material of the load. The inverter includes switching elements forming a full-bridge circuit. The drive frequency of the switching elements is switched between a frequency substantially equal to a resonance frequency of the resonance circuit and a frequency substantially 1/n time (n being an integer equal to or larger than two) thereof, according to a detection result of the load material.

Induction heating apparatus

An induction cooking device includes a heating coil performing induction heating of a cooking container placed on a top plate, an inverter circuit supplying high frequency current to the heating coil, an infrared sensor detecting an amount of infrared light radiated from the cooking container and outputting a detection signal based on the detected amount, a temperature sensor detecting a temperature of the cooking container by thermal conduction through the top plate, and a control unit controlling an output of the inverter circuit so that the outputs of the infrared and temperature sensors do not exceed the respective control temperature. The control unit judges whether or not the infrared sensor is normally detecting the temperature of the cooking container, and when it is judged that the infrared sensor is normally detecting the temperature of the cooking container, the control unit raises the control temperature of the temperature sensor.

Induction cooking device

An induction heating apparatus is capable of stop heating without excessively boosting output voltages of a booster circuit and a power factor correction circuit. The induction heating apparatus includes a boosting function unit, an inverter circuit, and a booster circuit controller. The boosting function unit includes a power factor correction circuit and a booster circuit, and boosts an input direct-current power to a direct-current voltage having a peak value larger than the peak value of the input direct-current power by turning on/off a switching element. The inverter circuit includes a heating coil, and inputs the direct-current voltage output by the boosting function unit to generate a high frequency current in the heating coil by turning on or off a different switching element. The booster circuit controller stops a boosting operation of the boosting function unit without a prescribed delay from the stop of an operation of the inverter circuit.

An induction heating device has an accurate sensing of the temperature of a to-be-heated object and is user-friendly. The induction heating device includes a sensor for sensing the temperature of the to-be-heated object and can carry out a heating operation only when it is determined that the to-be-heated object exists above the sensor. A display having a circular design and characters, for example, that shows the position of this sensor is provided on a top plate of the induction heating device.

Induction heating device

An induction heating device includes a top plate, a thermo-sensitive device, a temperature detector, a coil, a controller, and a light-emitting section. The top plate places thereon a cooking utensil containing material to be cooked. The thermo-sensitive device changes its electrical characteristics with the temperature of the cooking utensil. The temperature detector detects the temperature of the cooking utensil based on the electrical characteristics of the thermo-sensitive device. The coil heats the cooking utensil. The controller controls the coil based on the temperature information of the temperature detector, thereby controlling an amount of the electric heating power to be supplied to the cooking utensil. The light-emitting section emits visible light to the area over the thermo-sensitive device. The light from the light-emitting section illuminates the area over the thermo-sensitive device through the top plate.

An induction heating cooker includes a cooking container heating coil, an inverter circuit to supply high-frequency current to the heating coil, an infrared ray sensor to detect radiation from the container, an electric power integrating section to integrate heating electric power from the inverter circuit, and a heating control section to control an inverter circuit output. If the power integrating section has less than a predetermined value when an increase in the output of the infrared ray sensor has a first value after start of heating, the cooker shifts to a first heating control mode and, if equal to or more than the predetermined value, shifts to a second heating control mode. The power, in the first heating control mode, is reduced to a second amount of power lower than the first amount and, in the second heating control mode, is a third amount larger than the second amount.

Induction heating cooker

An infrared sensor includes an infrared detection element which is provided on a lower side of a top plate to detect an amount of infrared light radiated from a heated object and an amplifier to amplify a signal detected by the infrared detection element. The infrared sensor outputs an initial detection value having a substantially constant magnitude with respect to the temperature of the heated object when the temperature of the heated object is lower than a detection lower limit temperature, and outputs a detection signal having a magnitude and a rate of increase which become larger as the temperature of the heated object becomes higher in the vicinity of a control temperature range in which the control unit controls the output of the induction heating coils to perform temperature control of the heated object. The control unit includes a storage unit to measure and store the initial detection value, and reduces the output of the induction heating coils or stops the heating when an increased amount of the output value of the infrared sensor with respect to the initial detection value stored in the storage unit becomes greater than or equal to a predetermined value.

The present invention provides an induction heating apparatus that can detect that a power factor correction circuit is in operation or in non-operation. The induction heating apparatus includes a power factor correction circuit that corrects a power factor of an inputted direct-current power supply by turning on and off a switching element connected to a choke coil, a booster circuit that boosts an output voltage of the power factor correction circuit by turning on and off a switching element connected to a choke coil, an inverter circuit that inputs the output voltage of the booster circuit to generate a high-frequency current in a heating coil by turning on and off a switching element, and an inverter circuit drive control unit that, in driving the power factor correction circuit, controls output of the inverter circuit such that an input current reaches a target value and detects the voltage in the booster circuit. The inverter circuit drive control unit stops the output of the inverter circuit when it is detected that the power factor correction circuit is in non-operation.

An induction heating apparatus wherein an electrostatic shield and the low-potential portion of an inverter circuit are electrically connected securely is provided. The induction heating apparatus in accordance with the present invention comprises a top plateon which a matterto be heated is placed, an induction heating coilfor induction heating the matterto be heated, driving meansfor driving the induction heating coil, and a stationary plateand a cover for stationary plateprovided between the matterto be heated and the induction heating coil, wherein connection portionseach integrated with a connection terminalare electrically connected to the electrostatic shieldprovided on the stationary plateusing a conductive adhesive, and the connection parts are held between the stationary plateand the cover for stationary plate. With this configuration, the connection parts can be held securely and stably.

An induction heating apparatus with high safety is provided in which leakage current is prevented from flowing to the human body and there is no possibility of an electric shock even when an electrostatic shielding member does not sufficiently perform its function. The driving apparatus of the present invention is an induction heating apparatus in which the electrostatic shielding member is provided between an object to be heated and an induction heating coil where sensing portion for sensing the conduction condition of the electrostatic shielding member is provided, and driving portion for driving the induction heating coil is controlled through sensing by the sensing portion.

Induction heating apparatus having electrostatic shielding member

A detector is operable to detect a displacement of a load by an ascending force based on a period of time from a time a heating output of an inverter drops from a predetermined level to a first level, to a time the heating output returns back to a second level larger than first level. Thereby, the detector distinguishes an intentional removal of the load from the displacement of the load by the ascending force. An induction heater including the detector reduces the displacement of the load by the ascending force and stops the heating of the load when the load is removed intentionally.

Induction heater with controlled current to heating coil

In an induction heating apparatus, in order to decrease the buoyancy exerted on an object to be heated which is made of a material having high electrical conductivity and low magnetic permeability, such as aluminum, an electrical conductor is provided between a heating coil and the object to be heated, thereby increasing the equivalent series resistance of the heating coil. Hence, the current of the heating coil, which is required for obtaining a desired heating output, is decreased, whereby the buoyancy of the object to be heated can be decreased. In addition, the electrical conductor is divided into two halves, and they are arranged in a circular arc form with a clearance provided therebetween and made close contact with the bottom face of a plate, whereby the temperature rise of the electrical conductor can be restricted. Furthermore, the heat of the electrical conductor is transferred and dissipated to the object to be heated, whereby the heating coil and the like are not damaged even if the electrical conductor is heated. An electrical conductor temperature sensor for detecting the temperature of the electrical conductor is provided; when the detection temperature becomes a predetermined temperature, the heating output of a drive circuit is decreased, whereby the heat generation of the electrical conductor is decreased and the heating coil and the like are not damaged by heat.

An electric conductor provided for decreasing a lifting force exerted on an object being heated has an aperture of a small diameter in the center thereof, which leaves a large surface area to enhance reduction of the lifting force. The electric conductor is also provided with a comb section around the aperture for preventing a circling current induced in the electric conductor from flowing into an area around the aperture. This structure can thus alleviate excessive heating around the aperture, and allow the heating coil to produce a high output power for a long duration of time even when an inwardly concaved pan is used.

Growing community of inventors

Hyogo, Japan

Izuo Hirota