ELECTROMAGNETIC WAVE HEATING DEVICE

To heat an object locally by automatically recognizing a shape of the object and emitting an electromagnetic wave based on the shape without enlarging a device size. An electromagnetic wave heating system comprises a heat chamber having a wall surface, in which an object is placed to be heated, a flat antenna arranged on the wall surface of the heat chamber and configured to emit the electromagnetic wave so as to heat the object inside the heat chamber, and a controller configured to control a movement of the flat antenna. The flat antenna comprises a plurality of antennas arranged in an array manner, and the controller detects a shape or a temperature distribution of the object based on a reflected power that is generated when the electromagnetic wave is emitted from the plurality of antennas, and determines a size of microwave supplied into each of the plurality of antennas based on a detection result thereof.

TECHNICAL FIELD

The present invention relates to an electromagnetic wave heating system such as a microwave oven, specifically an electromagnetic wave heating system that heats food by using a plurality of array antennas for emitting an electromagnetic wave such as microwave, automatically recognizes a shape of an object, emits an electromagnetic wave based on the shape of the object, and thereby, heats the object.

BACKGROUND ART

The electromagnetic wave heater is already known, which heats in suitable for the shape of an object and etc. by automatically recognizing the shape or the temperature distribution of the object such as food and, based on the result, controlling a directivity of the microwave irradiation antenna. For example, the microwave heater that calculates the temperature distribution of the object by the infrared sensor provided on the top part of heating room and, based on the result, emits the microwave having directivity into the object by using two rotation type antennas provided at the bottom surface side of the heating room, is disclosed in Patent Document 1.

PRIOR ART DOCUMENTS

Patent Document 1: Unexamined Japanese patent application publication No. 2008-292088

SUMMARY OF INVENTION

Problem to be Solved by Invention

According to the microwave heater in Patent Document 1, it is difficult to measure the temperature distribution, for example, at the bottom and the side surfaces of the object, since the infrared sensor is arranged at the wall surface on the top surface side of the heating room. Accordingly, the temperature distribution measurement result cannot be utilized for controlling the electromagnetic wave irradiation from antennas arranged at the bottom and the side surfaces of the object.

Moreover, the directivity is given to the microwave emitted into the object by use of two rotation type antennas. However, there is a limitation for control of the irradiation-microwave-directivity only by two rotation type antennas.

Means for Solving the Above Problems

The present invention is made from the above viewpoints.

Effect of Invention

An electromagnetic wave heating system of the present invention comprises a heat chamber having a wall surface, in which an object is placed to be heated, a flat antenna arranged on the wall surface of the heat chamber and configured to emit an electromagnetic wave so as to heat the object inside the heat chamber, and a controller configured to control a movement of the flat antenna. The flat antenna comprises a plurality of antennas arranged in an array manner, and the controller detects a shape or a temperature distribution of the object based on a reflected power that is generated when the electromagnetic way is emitted from the plurality of antennas, and determines a size of microwave supplied into each of the plurality of antennas based on a detection result thereof.

Effect of Invention

According to the present invention, an object can be heated locally by automatically recognizing a shape of the object and emitting an electromagnetic wave based on the shape thereof. Furthermore, a size reduction of an electromagnetic wave heating system can be achieved since a recognition of the object shape and heating can be performed not by using a plurality of elements such as an infrared sensor and a rotation antenna but by using one element, an array antenna.

EMBODIMENTS FOR IMPLEMENTING THE INVENTION

In below, embodiments of the present invention are described in details based on figures. Note that, following embodiments are essentially preferable examples, and the scope of the present invention, the application, or the use is not intended to be limited.

First Embodiment

Referring toFIG. 1, a microwave oven10, one example of an electromagnetic wave heating system of the present invention, comprises a heat chamber2configured to store an object, flat antennas1A to1D arranged on top, bottom, left, and right wall surfaces of the heat chamber, an oscillator3configured to generate a microwave, a switcher4A configured to switch a supply destination of microwave inputted from the oscillator3, a switcher4B configured to switch a supply destination of microwave inputted from the switcher4A, a controller5configured to control the oscillator3and the switcher4(the switcher4A and the switcher4B), and a coaxial line6that connects each switcher4with each flat antenna1. The switcher4A selects one of the switcher4B, the flat antennas1B,1C,1D or multiple of them as a microwave output destination. Moreover, as described below, the respective flat antennas1are formed to be arranged of a plurality of small sized antennas11in an array manner. Then, the switcher4B selects small sized antenna11inside the flat antennas1A as the microwave output destination.

Each flat antenna1A to1D is arranged to a corresponding wall surface made of metal via an insulator such as ceramics having heat resistance characteristic. Moreover, a mount table on which an object is put, is also formed by an insulator such as ceramics having the heat resistance characteristic, and provided on the flat antenna1A that is provided at the bottom wall surface side.

Moreover, the controller5detects a shape or a temperature distribution of the object (food) put on the mount table by use of a reflected power that is generated when the microwave is emitted from each of small sized antennas11of the flat antenna1A, and based on the detection result, defines a size of microwave supplied into each of small sized antennas11.

Referring toFIG. 2, regarding each flat antenna1, sixteen small sized antennas11A to11P are arranged by four column×four row in an array manner. With regard to the flat antenna1A, microwave is series-supplied from the switcher4B in every line or row. For example, a first output terminal of the switcher4B is connected to four small sized antennas11A to11D arranged at the first row of the flat antenna1A, and a second output terminal of the switcher4B is connected to four small sized antennas11E to11H arranged at the second row of the flat antenna1A. In other word, a distance from each antenna11existed in the same row to the switcher is different from each other. Since a length from the oscillator3to each antenna11is different from each other, an appropriate operational frequency is different from each other. By seeing the above from the counter side viewpoint, a microwave frequency provided to the flat antenna1is changed, and the small sized antenna11to be “ON” inside the flat antenna1can be switched.

When an object, i.e., food is put on the mount table of the flat antenna1A, the microwave emitted from respective antennas11of the flat antenna1A is partially reversed to the flat antenna1A by reflection at the object and etc. Accordingly, the shape of the object can also be recognized automatically by monitoring the reflected power size by the controller5.

Referring toFIG. 3, with regard to the flat antenna1, sixteen metal patterns in spiral manner are formed on the surface of a substrate12with insulation characteristics such as ceramics. Each of metal patterns forms one small sized antenna11.

Four power feed points configured to receive microwave from the switcher4B are formed at a second substrate on the back surface side (not illustrated). Further, referring toFIG. 2, a metal pattern is formed on the surface so as to deliver the microwave from four power feed points to each small sized antenna11in every row of the flat antenna1.

Each small sized antenna11is formed spirally at the center of a power receiving end11ainputted of the microwave, and formed such that a distance from the power receiving end11ato an opening end11bbecomes approximately ¼ wavelength of microwave. Moreover, a through hole is formed at a position of the power receiving end11aof each small sized antenna11of the substrate12. A via is filled with at the through hole, and the metal pattern of the first substrate12is connected to the metal pattern of the second substrate13through the via.

Referring toFIG. 4, the switcher4comprises an input terminal41(an input part), a plurality of output terminals42(output parts), and a plurality of branch transmission lines45(transmission parts). The microwave outputted from the oscillator3is inputted into the input terminal41. The microwave outputted from the respective output terminals42is connected to the power feed points14of each flat antenna1. The branch transmission line45is provided in correspondence to the output terminal42. The input terminal41is grounded via a ground line43at the input side.

Each branch transmission line45comprises a switching means46for switching an “ON” state that allows for microwave passage and an “OFF” state that do not allow for microwave passage. Each switching means46includes a transmission-side diode63and a ground-side diode65that are constituted of, for example, PIN diode. Each branch transmission line45is provided with a capacitor51and a capacitor52in this order, seen from the input terminal41side.

In the transmission-side diode63, a “cathode” is connected to the input terminal41side, and an “anode” is connected to a first strip line71. A bias-line64is provided with at the “anode” side of the transmission side diode63(at the first strip line71), and the other end of the bias-line64is connected to a signal input part81. The capacitor51is connected at the output terminal42side of the first strip line71. A second strip line72is connected at the output terminal42side of the capacitor51.

The “cathode” is grounded at the ground-side diode65, and the “anode” is connected to the second strip line72. A bias-line66is provided at the “anode” side of the ground-side diode65(at the second strip line72), and the other end of the bias-line66is connected to a signal input part82.

An inductor67is provided at the bias-line64at the transmission side, and both ends of the inductor67are grounded through capacitors68and69. An inductor77is provided at the bias-line66at the ground side, and both ends of the inductor77are grounded through capacitors78and79.

An input side ground line43is branched into a plurality of branch ground lines. An electrical length up to the oscillator3can be adjusted by selecting the branch ground line43to be eliminated off. Accordingly, an adjustment with respect to circuit impedance variation caused by an assembly tolerance and parts variability during manufacturing can be performed at also final stage of manufacturing.

With respect to the branch transmission line45ain correspondence to the output terminal42for outputting the microwave, a positive bias voltage is applied to the signal input part81of the bias-line64at the transmission side, while, a negative bias voltage is outputted to the signal input part82of the bias-line66at the ground side. Thereby, the transmission side diode63to which forward-bias is applied, is conducted through at the output side transmission line45a, and the ground side diode65to which reverse-bias is applied, is blocked.

With respect to the branch transmission line45bin correspondence to the output terminal42from which the microwave is not outputted, the negative bias voltage is applied to the signal input part81of the bias line64at the transmission side, while, the positive bias voltage is outputted to the signal input part82of the bias line66at the ground side. Thereby, the transmission side diode63to which reverse-bias is applied, is blocked at non-output side transmission line45b, and the ground side diode65to which forward-bias is applied, is conducted through.

From these above results, since the output side transmission line45ais conducted through and the non-output side transmission line45bbecomes blocked when seen from the input terminal41, the microwave inputted into the input terminal41is outputted from the output terminal42via the output side transmission line45a.

INDUSTRIAL APPLICABILITY

As illustrated as above, the present invention is effective to an electromagnetic wave heating system such as a microwave oven.

NUMERAL SYMBOLS EXPLANATION