Matsushita Electric Industrial Co., Ltd.

Nobuo Ikeda

Hirofumi Yoshimura

Junzo Tanaka

A microwave oven with a rotary antenna for feeding electromagnetic waves to a heating chamber. The antenna has a first antenna portion and a second antenna portion which extend in mutually opposite directions and substantially at right angles to a rotary shaft portion, the length of the first antenna portion being greater than that of the second antenna by approximately one quarter of the wavelength of the electromagnetic waves used and the free end of the first antenna portion being bent substantially at right angles thereto for a length not exceeding one quarter of the wavelength to thereby ensure a uniform electric field distribution within the heating chamber. A dielectric seal plate supporting the rotating shaft of the rotary antenna has a tapered cross-sectional configuration projecting into a waveguide to prevent a sharp change of impedance in the waveguide, whereby spark discharge due to a high frequency electric field is effectively prevented even in the absence of a heating load in the heating chamber.

Microwave oven with rotary antenna

A microwave leakage-preventive device for use with a high frequency heating appliance for dielectric heating of an object by high frequency energy has a choke attenuator installed in a door for attenuation of microwaves, the choke attenuator being of the type adapted to enter an oven cavity when the door is closed. A portion of the choke attenuator is received in a recess formed within the door body, so that the choke attenuator entering the oven cavity is made smaller by an amount corresponding to the dimension thereof received in the door body. The width of the recess formed within the door body is made larger than the width of the choke attenuator entering the oven cavity, thereby providing a small-thickness door which is superior in microwave leakage prevention.

Door seal construction for high frequency heating appliance

A high frequency heating appliance which includes a magnetron, which is used as a high frequency oscillator, and which is directly mounted in a heating chamber and which further includes a stirrer fan for ensuring a uniform electric field distribution of high frequency electromagnetic radiation in the chamber; the fan is mounted coaxially with an antenna for the magnetron; the stirrer fan is provided with a vertical metallic segment for high frequency impedance matching and the vertical metallic segment has a horizontal metallic subsegment located on its end which is oriented so as to be substantially at right angles with the vertical metallic segment for providing a sufficient capacitive coupling between the wall of the heating chamber and the horizontal metallic subsegment with an adequate gap being secured from the heating chamber wall supporting the magnetron. The above-noted construction ensures an improved efficiency and improved distribution of the high frequency output of the magnetron.

High frequency heating appliance with an antenna and stirrer assembly

A microwave heating apparatus has a heating chamber in which an object is to be heated both dielectrically by microwave and by radiant energy. A microwave generator for generating microwaves is disposed above the heating chamber, and a radiant energy heater is located within the heating chamber. A rectangular wave guide extends between the generator and an opening in the chamber for guiding the microwaves generated by the generator into the heating chamber from above, the wave guide being bent generally in the shape of the letter Z and the portion of the wave guide other than the portion adjacent the opening into said heating chamber being spaced from the walls of the heating chamber. Thermal insulation is provided between the chamber and the portion of the wave guide spaced from the walls of the chamber.

Microwave heating apparatus

An improved choke seal arrangement, in a microwave oven, in which a slit structure is provided to prevent leakage of microwave energy around the periphery of the door. The slit structure, which has been provided in one of the walls defining the choke cavity in the prior art choke seal arrangement, is provided in a door wall portion spaced apart from the choke cavity so as to facilitate mechanical formation of the choke cavity and also to prevent deformation of the choke cavity wall during use. The choke seal arrangement permits the gap between the wall of the choke cavity and the confronting inner wall of the heating chamber to be smaller than hitherto, and the microwave seal performance further improved.

Microwave seal structure in microwave oven

There is disclosed an energy feeding device for installation in a high frequency heating appliance which includes a heating chamber, a high frequency oscillator for supplying a high frequency energy to the heating chamber, a waveguide for transmitting the high frequency electromagnetic wave generated from the high frequency oscillator, and a rotary antenna for radiating the high frequency electromagnetic wave so transmitted by the waveguide into the heating chamber. The rotary antenna has a revolving drive shaft, made of a material with a low dielectric loss and is connected to a drive source, a metal pipe which is connected to the revolving drive shaft at its socket end. The socket end of the metal pipe is expanded and rounded off, thereby substantially preventing sparking under light load.

High frequency energy supply in a high frequency heating appliance

The present invention is a microwave oven having a rotary antenna with a substantially tubular L-shaped configuration from which microwaves are radiated into a heating cavity. This antenna is constituted by a first antenna portion, which extends from and is perpendicularly to a wall of the heating cavity in the microwave oven and has a length substantially equal to a quarter of the wavelength, and a second antenna portion which extends parallel to the wall and has a length substantially equal to half the wavelength so as to distribute the microwaves evenly inside the heating cavity.

Microwave oven having a tubular L-shaped antenna

A microwave heating apparatus with a heating chamber, a high frequency oscillator, and a wave guide between the oscillator and the chamber has a rotatable antenna coupling the wave guide with the heating chamber for distributing high frequency radiation in the chamber. The rotatable antenna has an inner end extending into the wave guide and which is rotatably mounted therein, a first magnet is provided in the inner end of the rotatable antenna, and an antenna drive motor located outside the wave guide has a second magnet in spaced opposed relation to the first magnet and forming a magnetic coupling therewith.

Microwave heating apparatus having magnetic coupling for driving the

A microwave heating apparatus has a body with a front wall, and a heating chamber within the body for holding an object to be heated. A microwave source is provided for generating microwaves, and a wave guide is connected between the microwave source and a microwave inlet for guiding the microwaves from the microwave source to the heating chamber. A radiant energy heater is disposed within the heating chamber for heating the object to be heated by radiant energy, and a power box is positioned above the chamber and housing the microwave source and the high voltage circuit components therefor. A microwave source cooling fan is provided in the power box, and thermal insulation covers the walls of the heating chamber, the upper surface of the thermal insulation on the top of the chamber and the bottom surface of the power box being spaced to provide a cooling conduit. The front wall of the body has an air suction inlet therein opening into one end of the cooling conduit, and a power box cooling fan is provided at the other end of the cooling conduit. The power box has a suction port therein opening into the cooling conduit upstream of the power box cooling fan for admitting air from the cooling conduit into the power box, the microwave source cooling fan and the power box cooling fan being in parallel flow relation.

Microwave heating apparatus with cooling conduit

A heating appliance such as a stove which has a high frequency and resistance heater therein. A high frequency oscillator supplies frequency radiation energy through a waveguide extending to a energy feeding port in the heating chamber, and a rotary antenna extends through the energy feeding port for directing the high frequency energy into the heating chamber. A motor rotates the antenna, a heater of a type other than a high frequency heater, such as a resistance heater, is in the heating chamber substantially parallel with the wall of the heating chamber in which the energy feeding port is positioned. The rotary antenna has substantially an L shape with a longitudinal section extending from the waveguide into the heating chamber through the energy feeding port, the portions of the longitudinal section within the heating chamber from the wall in which the energy feeding port is positioned to the inner end thereof having a length substantially equal to one quarter the wavelength of the high frequency energy, and a lateral section connected to the longitudinal section at a point intermediate the length thereof within the heating chamber at a point between the wall of the heating chamber and the resistance heater.

Growing community of inventors

Nara, Japan

Nobuo Ikeda