Matsushita Electric Industrial Co., Ltd.

Panasonic Intellectual Property Management Co., Ltd.

Panasonic Corporation

Hisashi Morikawa

Haruo Suenaga

Shinichi Sakai

Hideaki Moriya

Nobuo Shirokawa

Makoto Mihara

Toyotsugu Matsukura

Manabu Kinoshita

Kenji Yasui

Kazuho Sakamoto

Yasuhiro Umekage

Hideki Omori

Yoshiaki Ishio

Takeshi Kitaizumi

Masato Matsuda

Emiko Ishizaki

Yoshiaki Watanabe

Keiichi Satou

Yoshitaka Oda

Takeshi Irii

Toyotsubu Matsukura

Since a protruding portion preventing a rotation during screw fastening of a connection member is disposed to engage with a printed circuit board, and a protruded length of the protruding portion is smaller than a thickness of the printed circuit board, a configuration can be achieved such that the protruding portion does not interfere with an earth member, a bracket, etc., disposed on the back side of the printed circuit board, and the earth member and the bracket can freely be designed.

Grounding structure for circuit board

Since a protruding portion preventing a rotation during screw fastening of a connection member is disposed to engage with an end surface of a printed circuit board, a configuration can be achieved such that the protruding portion does not interfere with an earth member, a bracket, etc. disposed on the back side of the printed circuit board, and the earth member and the bracket can freely be designed.

A resonance type high frequency heating apparatus comprising; a direct current power supply; a series connection circuit consisting of a pair of semiconductor switching elements connected in parallel to the direct current power supply; another series connection circuit having a primary coil of a leakage transformer and a capacitor connected to both ends of one of the pair of semiconductor switching elements; and a drive means for driving each of the pair of semiconductor switching elements; wherein a variable dead time preparation circuit is provided in the drive means, and the variable dead time preparation circuit enables dead time to remain constant at below a predetermined frequency and causes the dead time to increase sharply at a point above a predetermined frequency.

High-frequency heating apparatus

An object of the present invention is to provide an inverter circuit in which soft start can be implemented by a simple circuit added thereto. In high-frequency heating apparatus for driving a magnetron, a DC power supply is chopped by two semiconductor switching devices, and this is output as an AC current through a resonance circuit. The high-frequency heating apparatus includes a dead time generation circuit for turning off the semiconductor switching devices concurrently. In the high-frequency heating apparatus, a drive unit for driving the aforementioned semiconductor switching devices has a function of limiting the lowest frequency of a frequency with which the semiconductor switching devices are driven. The aforementioned lowest frequency is set to be high at the beginning of operation of the high-frequency heating apparatus, and the aforementioned lowest frequency is set to be lower gradually thereafter.

High-frequency heating device

A purpose of the present invention is to provide an inverter circuit capable of suppressing an overshooting phenomenon of an input current at an instantaneous time when an initiating operation of the inverter circuit is switched to the normal operation thereof, and thus, capable of preventing damages of IGBTs and a magnetron. In a high frequency heating apparatus comprising: a control signal forming circuit for forming a control signal from a difference between an input current of an AC power supply and a reference current; a frequency modulated signal forming circuit for correcting rectified voltage/rectified current which are obtained by rectifying the AC voltage/current of the AC power supply based upon the control signal of the control signal forming circuit; and a dead time forming circuit for receiving the output of the frequency modulated signal forming circuit, a control signal converting circuit having a function capable of further lowering the value of the control signal is provided between the control signal forming circuit and the frequency modulated signal forming circuit.

There is constructed a constitution such that a shunt resistoris interposed in series with a portion capable of measuring an output current of a unidirectional power source portionof a high frequency heating apparatus and a voltage generated at the shunt resistoris outputted by a buffer. Further, an operational amplifierhaving a high input impedance is used for the buffer. Further, a diode bridgeand a semiconductor switching elementare fixed to a common heat radiating plate, the heat radiating plateis formed with a notched portionto thereby ensure insulating distances to the diode bridgeand the semiconductor switching element, and the shunt resistoris arranged on a straight line the same as that between the diode bridgeand the semiconductor switching element

High frequency heating apparatus

A purpose of the present invention is to provide an inverter circuit capable of firmly turning ON IGBTs under limited condition, while a heat loss and noise can be hardly produced in semiconductor switching elements. In a resonant type high frequency heating apparatus which is arranged by employing a DC power supply; a series connection circuit constructed of two semiconductor switching elements which are connected to the DC power supply; another series connection circuit constituted by a capacitor and a primary winding of a leakage transformer connected to both the terminals of one of the two semiconductor switching elements; and a driving means for driving the respective semiconductor switching elements respectively, a variable dead time forming circuit is provided in the driving means, while the variable dead time forming circuit makes a dead time constant at a switching frequency lower than, or equal to a predetermined switching frequency, and also, rapidly increases a dead time at a switching frequency higher than, or equal to the predetermined switching frequency. Furthermore, when the switching frequency becomes high, a limitation is provided by which the dead time is not further widened.

It is an object to decrease an occupied space in a printed board to carry out space saving and to reduce the size of a unit without sacrificing the performance of a transformer and increasing a cost. A transformeris constituted by a bobbinhaving at least a primary windingand a secondary windingwound therearound and a coreand the side surface of the bobbinis provided with a component holding section for holding high-voltage components such as a capacitorand a diodewhich constitute a voltage doubler rectifying circuit for rectifying a high voltage having a high frequency from the secondary winding

Transformer and transformer unit having the same

Since the exposed collector part of one semiconductor switching element is attached to the heat radiating fin by coating and filling a thermal conducting filler therebetween via spacers and and the exposed collector part of another semiconductor switching element is directly attached to the same heat radiating fin by coating the thermal conducting filler thereto without any spacer, heat resulting from switching losses can be effectively transmitted to the heat radiating fin and can be radiated therefrom. To effectively transmit heat, which results from switching losses, to a heat radiating fin and to radiate the same even if two semiconductor switching elements are connected in series, a collector part is exposed on the rear side thereof, and the two semiconductor switching elements are attached to a single heat radiating fin.

Power source unit for driving magnetron and heatsink to be mounted on printed circuit board thereof

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.

Magnetron drive power supply

High-voltage diodes ( ) and ( ) and high-voltage capacitors ( ) and ( ) making up a high-voltage circuit are connected and are molded of a resin ( ) except that terminals ( ) and ( ) are drawn out as a small-sized high-voltage module ( ) in one piece.

In a microwave heating device, a propeller fan is mounted on a drive shaft of a motor that in vertically positioned parts of a high frequency power supply unit are arranged in the order of a power control semiconductor device and a high-voltage transformer along the direction of revolution of the propeller fan. The motor is secured to a support member formed by a motor cover attached to the casing of the propeller fan. The fan and high frequency power supply unit are mounted to a first frame and a second frame, both of which are bent and connected at a connecting portion and fixed in an approximately 'L' shape, while an airflow path is defined by a first guide wall and a second guide wall to cool the parts of the high frequency power supply unit. An airflow path is formed by a plurality of guide walls provided on the two frames, and a communicating hole is provided in proximity to the connecting portion of the two frames. The propeller fan is so arranged as to revolve at a low r.p.m. after stopping the microwave heating.

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Nara, Japan

Hisashi Morikawa