Abstract: The present invention relates to an apparatus and method for controlling output power of a combination hood and microwave oven, and more particularly, to an apparatus and method for controlling power of a combination hood and microwave oven, wherein an output level of a high voltage transformer for generating a high voltage can be adjusted. According to the combination hood and microwave oven of the present invention, the electric power supplied to the high voltage transformer can be increased by temporarily turning off the parts (limited to the components which can be controlled separately from the microwave oven function), such as the vent fan or the electric indicator lamp, having large power consumption. Thus, the output power level thereof can be increased. Therefore, there are advantages in that the quick cooking can be made and cooking performance can be improved due to the high output of the transformer, when the user intends to make the quick cooking with the high output power.

Abstract: At least two blowers are controlled with baffles to create circulating zones of airflow which circulate in a substantially horizontal plane within a convection oven cavity. This airflow minimizes the potential for airflow paths to be broken up or blocked by the configuration of objects placed in the oven. The substantially horizontal airflow reduces the non-uniformity of air temperature distribution within the oven cavity. The blowers may be controlled to rotate either simultaneously or alternately, depending on the selected mode of operation. The blowers and associated heating elements are controlled to operate in various cooking modes by the controller in response to a mode selector input.

Abstract: A high-frequency dielectric heating power control method comprises: detecting the input current of an inverter circuit for rectifying the voltage of an AC power source to convert the rectified voltage into an AC voltage of a predetermined frequency; rectifying the detected current to determine an input current waveform; shaping the waveform to determine a reference waveform; determining the difference between the input current waveform and the reference waveform; and mixing the differential information and the current control output by a mix circuit to convert the mixed one into the drive output of a switching transistor of the inverter circuit.

Abstract: A variable-frequency inverter microwave oven and a method for controlling the same. The inverter microwave oven comprises a magnetron for generating electromagnetic waves, a direct current (DC) voltage generator for rectifying and smoothing a commercial alternating current (AC) voltage, which is an inverter drive voltage, to generate a DC voltage, and a switching device for performing a switching operation based on the DC voltage from the DC voltage generator to generate an AC voltage for the driving of the magnetron. The switching device includes a plurality of switches turned on/off in response to the DC voltage from the DC voltage generator.

Abstract: Disclosed is a circuit and a method for driving a DC microwave oven. The circuit for driving a DC microwave oven according to the present invention includes: an inverting means to convert DC into AC by a driving pulse; a high voltage transformer to transform the AC from the inverting means, and supply the transformed AC to a magnetron; a pulse driving means to generate the driving pulse; and an over-current detecting means to detect an electric current which is supplied to the inverting means from a DC power source, and output an over-current detect signal if the detected current is determined as an over-current, so as to avoid the generation of the driving pulse by the pulse driving means. According to the present invention, the driving of the magnetron could be stopped when a malfunction of an interlock switch caused by an error or the over-current from the DC power source is detected, and circuit elements can be advantageously prevented from being damaged by the over-current.

Abstract: A microwave oven with an electric device is provided in which the microwave oven includes an electric device control button and a control unit. The electric device control button drives the electric device by manipulation of a user and generates a power amount control signal to control power supplied to the electric device. The control unit controls the amount of power supplied to the electric device in response to the power amount control signal. The power amount control signal is a single pulse signal that is generated whenever the electric device control button is manipulated; and the amount of power supplied to the electric device is determined depending upon a number of occurrences of the single pulse signal.

Abstract: A control system for a an oven having at least one cooking element and a surface warmer includes a microprocessor, a memory, and a user input interface for user entry of cooking recipes including a cooking mode, an oven temperature, and a cooking time. Up to five favorite recipes can be stored in system memory for selection by a user, and two recipes can be combined for automatic sequential execution. The surface warmer is operable upon manipulation of two input selectors within a pre-determined time, and a preheat algorithm preheats the surface warmer by applying a 100% duty cycle to the surface warmer until an oven thermal limiter input switch reaches a predetermined temperature.

Abstract: A part of a body of a high-voltage condenser (28) is arranged between a lower plate (23) constituting a heating chamber (21), and a bottom plate (27) thereby to reduce attachment dimension of the high-voltage condenser (28), whereby size-reduction and space-reduction of the high-frequency heating apparatus becomes possible, and an insulation distance between the high-voltage condenser (28) and metal-made parts constituting the high-frequency heating apparatus can be secured easily, so that the number of the parts can be reduced. Therefore, it is possible to provide the high-frequency heating apparatus which is advantageous also in resources-reduction, assembly efficiency, and price.

Abstract: In a power-supply unit for a microwave tube, voltage between a helix power supply terminal and a cathode power supply terminal is divided into voltage slightly lower than the voltage of a collector power supply terminal. Uni-directional conductive means is provided between a voltage dividing point and the collector power supply terminal, and when the voltage of the collector power supply terminal is about to be lower than voltage at the voltage dividing point while the voltage approximates the voltage of the cathode power supply terminal, the uni-directional conductive means conducts and clamps the voltage of the collector power supply terminal so that the voltage is substantially equal to the voltage at the voltage dividing point.

Abstract: A microwave oven using DC power which can endure strong vibrations and eliminate noise according to noise standards. The microwave oven includes at least one second choke coil which is arranged outside a magnetron filter box and connected in series to at least one first choke coil installed in the magnetron filter box. Each choke coil and a feed-through condenser constitute a low pass filter. The size of each of the first choke coil is reduced and the size of each of the second choke coil is increased, so as to endure the strong vibrations and eliminate the noise generated by a driving of a magnetron.

Abstract: A low-power microwave oven for use in a vehicle has top entry to the heating chamber (120), is powered from the vehicle's cigarette lighter or accessory socket, and has the controls and display (60) and the cooling vents (80 and 110) also on the top surface of the oven. The oven is arranged to be secured to the seat by tits seat belt in such a manner that the oven will operate while so secured. There is also a spill container (141) in the heating chamber. Materials may be used that make the oven cabinet transparent or translucent.

Abstract: A microwave oven includes a direct current (DC) power supply unit which supplies DC power to a magnetron so as to suppress noise induced in a high voltage line. The DC power supply unit includes at least one rectifying diode and a choke coil. The rectifying diode rectifies high frequency alternating current (AC) power generated by a heater coil into the DC power to suppress noise induced in the high voltage line of a high voltage transformer. The choke coil forms ripples in the DC power and effectively prevents a moding of the magnetron, which is generated where a constant DC voltage is supplied.

Abstract: A microwave oven equipped with a toaster and a method of controlling the same. Particularly, the microwave oven equipped with the toaster is provided with a plurality of heaters and a plurality of buttons each corresponding to one or more heaters to selectively operate the heaters provided in the toaster, thereby minimizing a power consumption resulting from an unnecessary operation of the heaters. Further, the microwave oven equipped with the toaster and the method of controlling the same limits a consumption current by preventing the toaster and the magnetron from simultaneously operating, thereby being applicable to, for example, the wall mounted microwave oven having a limited consumption current.

Abstract: A microwave oven and a method of controlling the microwave oven recognize a power supply frequency correctly at a time power is supplied by eliminating the influence of noise. A blocking period is set in which generation of interrupts is deferred until a timer count reaches a predetermined set value, and interrupts are generated if the blocking period elapses. Accordingly, the microwave oven and method of the controlling the microwave oven recognize a power supply frequency without the influence of noise at the time of the power supply, thereby improving reliability of the microwave oven.

Abstract: A high-power control circuit of a microwave oven which is capable of making a voltage and current of a high-voltage transformer in the microwave oven to be in phase to improve a power-factor in the high-voltage transformer, thereby raising output power of the oven to a high level. The high-power control circuit comprises a power-factor compensator compensating a degradation in power-factor resulting from a voltage/current phase difference in the high-voltage transformer. The output power of the microwave oven is raised to a high level by improving the power-factor based on the voltage/current phase difference in the high-voltage transformer.

Abstract: A control method for a microwave oven equipped with a tray installed in a cooking chamber to rotate a popcorn bag while having a popcorn cooking mode to cook popcorn. During cooking, rotation of the tray is temporarily stopped near the point of time when the popcorn bag is increased in size to a maximum size. Accordingly, problems caused by the fact that the popcorn bag comes into contact with the inner wall surface of the cooking chamber so that it cannot rotate are solved. The popcorn cooking mode is an operation mode to cook a popcorn product with corn grains packed in the popcorn bag in a state in which it is folded at least one time. The rotation of the tray is temporarily stopped near the point of time when the popcorn bag is estimated to achieve its maximum length as a folded portion of the popcorn bag is unfolded.

Abstract: A power supply apparatus of a lighting system using microwave includes: a high voltage transformer for transforming a general AC power to an AC power of high voltage and outputting the high voltage AC power; and a voltage doubler unit for transforming the high voltage AC power into a high voltage DC power, increasing the frequency of the current of the DC power, and outputting the DC power having the increased frequency. Since the frequency of the power applied to the magnetron is increased to remove the flicker phenomenon, a stable light can be radiated to an external space.

Abstract: Disclosed are a key input apparatus in an electronic oven and a control method thereof enabling to reduce a size of a circuit as well as provide a simple design of the key input control part. A key input apparatus in an electronic oven includes a signal level producing part receiving input signals having a uniform level and producing signals having various levels, and a control part receiving the signals having the various levels through one input port and carrying out operations corresponding the signals having the various levels.

Abstract: A high frequency heating apparatus equipped with the oven hood comprises a heating chamber, a power supply apparatus for controlling high frequency output power by way of a semiconductor element, ventilation, and illumination for illuminating an object to be heated by another heat-cooking apparatus. Since the high frequency output power is controlled in such a manner that an optimum heating output power is applied in a linear manner for a proper time period, the heating output power can be controlled in the linear manner and the high frequency heating apparatus can be largely reduced in weight. As a result, the highest-speed heat-cooking operation by receiving the maximum high frequency output power can be realized, and the optimum cooking performance can be realized. Both the installation performance of the appliance to the mounting wall plane and the safety performance achieved by stably fixing the appliance can also be largely improved.

Abstract: An apparatus and method for controlling an output of a magnetron of a microwave oven is provided. The method includes setting an initial input current to generate an output higher than rated output. Thereafter, the magnetron is driven using initial input current of the setting. The output of the magnetron is varied within a preset time to prevent overheating caused by driving of the magnetron.

Abstract: A microwave oven with an electric device is provided in which the microwave oven includes an electric device control button and a control unit. The electric device control button drives the electric device by manipulation of a user and generates a power amount control signal to control power supplied to the electric device. The control unit controls the amount of power supplied to the electric device in response to the power amount control signal. The power amount control signal is a single pulse signal that is generated whenever the electric device control button is manipulated; and the amount of power supplied to the electric device is determined depending upon a number of occurrences of the single pulse signal.

Abstract: Circuit for operating a microwave oven including a DC voltage source, a switching part having at least two switching devices electrically connected to the DC voltage source for switching a voltage from the DC voltage source, controlling part for controlling the switching part, a magnetron for generating a microwave and a converting part for converting the voltage from the DC voltage source to a voltage for operating the magnetron by switching of the switching part, thereby permitting operation of the microwave oven by using a car battery.

Abstract: A microwave device includes a cooking space disposed in a housing, at least one microwave source, and at least one further radiation source, as an alternative to the microwave source, which may be protected from microwaves by a protective device. The protective device has a control unit by which it is possible to establish a protective state for the alternative radiation source.

Abstract: It is provided a magnetron drive power supply wherein a series connection body of first and second semiconductor switch elements that can be brought into reverse conduction and a series connection body of first and second diodes are connected in parallel, first and second capacitors are connected in parallel to the first and second diodes, a series circuit of a commercial power supply and a primary winding of a high-voltage transformer is connected between a connection point of the first and second semiconductor switch elements that can be brought into reverse conduction and a connection point of the first and second diodes, and output of a secondary winding of the high-voltage transformer energizes a magnetron through a high-voltage rectification circuit.

Abstract: A microwave oven accumulatively counts a cooking time by decreasing the cooking time where an actual cooking operation is not carried out, and various electrical parts, including a high voltage transformer, are cooled. The microwave oven increases the cooking time where a power relay of the microwave oven is actually driven and the cooking operation is carried out. Accordingly, the microwave oven counts the cooking time in consideration of cooking conditions. Additionally, the microwave oven decreases an output power level where the counted cooking time has reached a preset overheating prevention time, and compulsorily recovers the output power level to perform the remaining cooking operation where a cooling period has elapsed.

Abstract: A microwave oven includes a pair of terminal members for connecting between a power source and a high voltage transformer, respectively. The terminal members are isolated electrically from each other by means of remote-locating, respectively. A conducting member is installed in the door, and both ends thereof are revealed on the one side of the door. The pair of terminal members contact with ends of the conducting member when the door is closed. Then, the supply of current supplied from electrical power to the high voltage transformer is controlled. Accordingly, the structure of the microwave oven is simplified. The AC/DC type microwave oven is capable of being prevented from encountering faulty switching operations according to large amounts of direct current when the DC input power source is used.

Abstract: Timing of zero voltage in zero-voltage detector for detecting zero voltage of a commercial power supply 1 is predicted and input from the zero-voltage detector 6 is received only for a given time before and after the predicted timing, whereby overvoltage and overcurrent caused by a zero point shift can be prevented. Thus, it is provided a magnetron drive power supply which is excellent in stability for change in the power supply environment such as noise or instantaneous power interruption.

Abstract: Disclosed is a microwave oven including a magnetron, a power supply part supplying an AC power and a high voltage transformer generating a high voltage with the AC power from the power supply part, comprising a power controller part interrupting the power supply to the magnetron where it is determined that the voltage of the power supplied from the power supply part is lower than a predetermined allowable lower limit voltage. With this configuration, application of the voltage lower than the allowable lower limit voltage can be prevented, and in addition, the stability of the circuit can be enhanced.

Abstract: A method for controlling a microwave oven including a power supply part supplying an AC power, a high voltage transformer generating a high voltage with the AC power generated from the power supply part, a magnetron generating electromagnetic waves with the high voltage generated from the high voltage transformer, and a control signal generator part supplying a control signal to the magnetron, the method including the steps of: setting up a reference oscillation time; measuring the time when the magnetron starts being oscillated according to the control signal; comparing the reference oscillation time with the oscillation start time; and adjusting a pulse width of the control signal where the reference oscillation time is longer than the oscillation start time. With this configuration, the temporary surge operation and the noise generation can be lowered in the hot state, thereby serving to enhance a stability of the circuit.

Abstract: This invention provides a high-frequency heating apparatus for heating by using magnetron including an inverter power supply as a magnetron-driving power supply, a cooling fan, and an air guide. The cooling fan is inclined against the vertical direction of the power supply and fitted to the air guide. This structure increases the cooling effect of the power supply. Additionally, the power supply includes temperature sensors provided on semiconductor elements and control means for controlling the power supply and an operation of the heating apparatus according to the result of sensors. These sensors avoid breaking down of the power supply caused of overheating.

Abstract: A mobile, low powered microwave oven is disclosed. The oven has top entry to the heating chamber, it is powered from the cigarette lighter, has the controls and display and the cooling vents also on the top surface of the oven. The oven is arranged to be secured to the seat by the seat belts in such a manner that the oven will operate while so secured. There is also a spill container in the heating chamber. Materials may be used that make the oven cabinet transparent.

Abstract: An AC/DC microwave oven includes a selecting switch selecting AC or DC input power; a supplier supplying power using a common driving load driven by the DC power, and supplying the AC input power or DC/AC converted power selected by the selecting switch; and a microwave oscillator driven by AC power supplied by the supplier. The AC/DC type microwave oven includes a rectifier rectifying the AC input power into DC power; driving load driven by rectified DC power or DC input power; rotatable inverter including a motor driven by the DC input power, and commutator producing AC power according to the DC input power inputted to one direction which is outputting in two directions by means of input/output brushes contacted with four directions of the commutator and rotated by a motor; and microwave oscillating part driven by the AC power converted by the rotatable inverter or the AC input power.

Abstract: A microwave oven comprising a magnetron for generating a high frequency in response to a high voltage, a transformer having primary and secondary coils, the transformer generating the high voltage in a turn ratio of the primary and secondary coils and supplying it to the magnetron, and high-power output switching means for controlling the level of a voltage applied to the primary coil of the transformer. The microwave oven with the high-power output switching means can control its maximum power output level on the basis of an allowable amount of current supplied to a distribution board.

Abstract: A transformer for a microwave oven capable of preventing quality deterioration thereof due to damaged insulating paper, includes a first core having a coil inserting section having one open side; a plurality of coils sequentially inserted into the coil inserting section in an inter-electrically insulated state; a second core coupled,to the first core, and for covering the open side of the coil inserting section; and a resin molding section formed to cover the whole area of the plurality of coils.

Abstract: Disclosed is a parts arrangement structure for a DC microwave oven which is formed by a combination of an upper panel, a lower panel and a rear panel, a space inside the DC microwave oven being divided into a device chamber in which a magnetron and an air guide are placed and a cooking chamber in which a rotating motor for rotating rollers and a turntable is placed, the DC microwave oven having a control panel which closes a front end of the device chamber. The parts arrangement structure comprises a high voltage transformer and an inverter circuit board mounted to the lower panel inside the device chamber; and at least one high voltage capacitor mounted to the lower panel below the cooking chamber.

Abstract: Disclosed is a microwave oven including a magnetron, a power supply part supplying an AC power and a high voltage transformer generating a high voltage with the AC power from the power supply part, comprising a power controller part interrupting the power supply to the magnetron where it is determined that the voltage of the power supplied from the power supply part is lower than a predetermined allowable lower limit voltage. With this configuration, application of the voltage lower than the allowable lower limit voltage can be prevented, and in addition, the stability of the circuit can be enhanced.

Abstract: Disclosed is a method for controlling a microwave oven including a power supply part supplying an AC power, a high voltage transformer generating a high voltage with the AC power generated from the power supply part, a magnetron generating electromagnetic waves with the high voltage generated from the high voltage transformer, and a control signal generator part supplying a control signal to the magnetron, the method comprising the steps of setting up a reference oscillation time; measuring the time when the magnetron starts being oscillated according to the control signal; comparing the reference oscillation time with the oscillation start time; and adjusting a pulse width of the control signal where the reference oscillation time is longer than the oscillation start time.

Abstract: A wall-mounted microwave oven and a method for controlling the same, wherein the microwave oven and a hood unit are prevented from being operated at maximum power at the same time in the initial operation state. The microwave oven comprises a hood unit driver for controlling an operation of the hood unit, power output switching means for controlling the level of a voltage to be supplied to a transformer, and a controller for controlling the hood unit driver and power output switching means to prevent the hood unit and a magnetron from being operated at the maximum power at the same time in the initial operation state. In the initial operation state, the hood motor and microwave oven are prevented from being operated at the maximum power at the same time for a certain period of time. Then, the hood motor and microwave oven are normally operated at the maximum power after the lapse of the certain time period.

Abstract: A high frequency heating apparatus including a circuit for driving a magnetron. A circuit comprises a leakage transformer, a second capacitor connected in series to primary coil of said leakage transformer, a second switching device connected in parallel with a series circuit of said primary coil and second capacitor, a first capacitor connected in parallel with said second switching device, and a first switching device connected in series to said second switching device. Under a structure of the present invention, the switching device and the leakage transformer, both being the key components of the circuit, may respectively be used in common either on a circuit of 200V-240V commercial power supply or on a circuit of 100V-120V commercial power supply. This enables volume production of the key components, which leads to a benefit of reduced cost of the components as well as the cost of heating apparatus.

Abstract: A power supply apparatus including: a power supply unit receiving a common AC power and generating a DC power; a constant voltage generator receiving the DC power and outputting a pre-set rated DC voltage; a controller receiving the rated DC voltage and outputting a control signal; and an outputting unit receiving the DC power to the rated DC voltage and being operated according to the control signal. As the single DC power converted from the common AC power is supplied to the peripheral circuit units of a microwave oven, the peripheral circuit units are controlled accordingly. And, since the single power is used, the power supply circuit is simple, contributing to lower down a product cost.

Abstract: A microwave heating apparatus operates in either a first mode or a second mode, that allow different amounts of electric power to be supplied to a load and a control circuit for driving and controlling the load. The voltage applied to a primary coil of a transformer is lower in the second mode than in the first mode. In another apparatus, no electric power is supplied to a control circuit for driving and controlling a heating member and other circuits when the apparatus is in a standby state. However, when the user operates an operation member for opening the door of a heating chamber, electric power is supplied.

Abstract: A new and improved microwave oven is disclosed which would be transportable and possess alternate power means other than a standard household alternating current connection. The present invention would be analogous to a standard microwave oven but would be approximately the size of a small to medium-sized toaster oven. In addition, the present invention could use one of several possible power sources, including a cigarette lighter adapter, a 12 volt battery, or a rechargeable battery. The present invention would be very convenient for a driver or passengers of a vehicle, and would also be convenient for outdoor use in a wide variety of situations.

Abstract: A microwave oven having a body casing forming a cooking chamber, an outer casing enclosing the body casing, and a magnetron for supplying the cooking chamber with microwaves is provided. The microwave oven includes a plurality of high-voltage transformers installed in series between the top of the body casing and the outer casing, each high-voltage transformer supplying the high voltage to the magnetron. With this configuration, the height for installing the high-voltage transformer is lowered, so the cooking chamber can be extended to a rear area of the control panel to thereby increase the size of the cooking chamber. The heat generated from the component chamber can be effectively discharged outside, and turns of a winding for the high-voltage transformer can be decreased, thereby reducing the cost of production.

Abstract: A microwave control unit that includes an external memory storage for storing, for example, control parameters, cooking parameters, and feature data is described. In one embodiment, the control unit includes a pre-programmed microprocessor coupled to a key panel and a display. The controller also is coupled, for example, to a power supply, sensors, and power switches. The control microprocessor, as is known in the art, includes an on-board memory unit, e.g., a read only memory, for storing the control program as well as control parameters, cooking parameters, and feature data. Under the control of the control program, the microprocessor is configured to control, for example, energy output levels and cooking time based on the operator inputs. The control unit also includes an external model configuration read only memory (EMCR) coupled to the control microprocessor via an external bus. The EMCR also has control parameters, cooking parameters, and feature data stored therein.

Abstract: A non-directional frequency generator inputs direct current power and outputs alternating current power. A high voltage transformer inputs the alternating current power, and either induces a higher voltage for driving the magnetron, or induces and outputs a commonly used alternating current power. A button inputting section includes a microwave oven operating button for driving the magnetron, and a voltage supplying button for supplying the commonly used alternating current power. A microcomputer applies the higher voltage of the high voltage transformer to the magnetron when there is a button input through the microwave oven operating button, while outputting the commonly used alternating current power when there is a button input through the voltage supplying button. Further, a socket outlet is formed on the body of the microwave oven, through which the commonly used alternating power generated at the microwave oven is supplied.

Abstract: A microwave oven comprises a main casing with a cooking chamber, a door for opening and closing the cooking chamber, and a magnetron in the main casing, for heating food within the cooking chamber. The microwave oven further comprises a power supply part; a plurality of contact parts provided to the main casing to be spaced from each other, being electrically connected to the power supply part; and a conductive part provided at the door, being electrically connected to the contact parts. With this configuration, the necessary components are decreased in number and the circuit is simplified in structure, thereby saving the cost of production and further improving the stability of the circuit.

Abstract: Disclosed is a parts arrangement structure for a DC microwave oven which is formed by a combination of an upper panel, a lower panel and a rear panel, a space inside the DC microwave oven being divided into a device chamber in which a magnetron and an air guide are placed and a cooking chamber in which a rotating motor for rotating rollers and a turntable is placed, the DC microwave oven having a control panel which closes a front end of the device chamber. The parts arrangement structure comprises a high voltage transformer and an inverter circuit board mounted to the lower panel inside the device chamber; and at least one high voltage capacitor mounted to the lower panel below the cooking chamber.

Abstract: A method for compensating cooking time of a microwave oven which sets an exact reference voltage and automatically controls cooking time in accordance with variation of an input voltage, includes the steps of: setting the reference voltage based on the input voltage regulated to a rated voltage in a state that power is applied or a load is driven and storing the reference voltage in a memory; checking a level of a currently input voltage; and calculating compensating time in accordance with a difference value between the currently input voltage and the reference voltage. Thus, it is possible to minimize dissatisfaction of a user due to voltage variation.

Abstract: Method and apparatus for preferential heating of a material are based on exposing the material to high intensity, pulsed, non-ionizing electromagnetic radiation. The method can destroy microorganisms, sterilize packaging, or sterilize moist food. An embodiment uses microwave radiation with pulse duration of less than 0.1 second with an average power of at least 1 kW to sterilize open-ended metal can prior to packaging.

Abstract: A magnetron driving circuit has a DC/AC conversion section, a transformer, and a capacitor. The DC/AC conversion section converts a direct current inputted from a direct current power source into an alternating current, and outputs the alternating current. The transformer has a primary coil and a secondary coil. The transformer raises a voltage of the alternating current outputted from the DC/AC conversion section and then induces the raised voltage from the primary coil to the secondary coil. The capacitor forms an inductance/capacitance resonance circuit by being connected in parallel with the secondary coil. Thus, in the magnetron driving circuit driven by the direct current power source, since the capacitor with a small capacitance is connected in parallel with the secondary coil of the transformer, the reverse surge voltage induced at the primary coil of the transformer is decreased sharply.