JP5816820B2 - Microwave heating device - Google Patents

Description

  The present invention relates to a microwave heating apparatus such as a microwave oven that radiates microwaves to an object to be heated and performs dielectric heating.

  A microwave oven of a typical microwave heating apparatus supplies microwave radiated from a magnetron, which is a typical microwave generation means, to the inside of a metal heating chamber through a waveguide, and into the inside of the heating chamber. The object to be heated is dielectrically heated. Therefore, if the microwave electromagnetic field distribution in the heating chamber is not uniform, the object to be heated cannot be heated uniformly.

  Therefore, as a method of uniformly heating the object to be heated, a structure that rotates the object itself by rotating the table, a structure that rotates the antenna that emits microwaves while the object to be heated is fixed, etc. A general method has been to use a drive unit to heat and uniformize the direction of the microwave radiated to the object to be heated.

  On the other hand, in order to simplify the configuration, a method of uniformly heating without a driving unit is expected, and a method using circularly polarized waves in which the polarization plane of an electric field rotates with time is proposed. Originally, since dielectric heating is based on the principle of heating an object to be heated having dielectric loss with a microwave electric field, rotation of the electric field is considered to have an effect on uniformity. For example, as a specific method of generating circularly polarized waves, Patent Document 1 discloses a method using X-shaped circularly polarized apertures 2 intersecting on the waveguide 1 as shown in FIG. 22 shows a method of disposing two rectangular slit-like openings 3 and 4 that are orthogonal to each other on the waveguide 1 as shown in FIG. Thus, a method is described in which a notch 6 is provided in the planar shape of the patch antenna 5 coupled to the waveguide 1.

  Although not related to circular polarization, Patent Document 4 discloses a plurality of rectangular slits 140, 141, 142, and 143 arranged at intervals of 1/4 of the wavelength as shown in FIG. An example of radiating is shown.

U.S. Pat. No. 4,301,347 Japanese Patent No. 3510523 Japanese Patent Laying-Open No. 2005-235772 Japanese Patent Laid-Open No. 10-284246

However, the conventional microwave heating apparatus has a problem that in any case of Patent Documents 1 to 3, the circularly polarized wave is used, but there is no uniform effect that can be achieved without a driving unit. . Both patent documents only describe that the synergistic effect of the circularly polarized wave and the drive unit is more uniform than the conventional drive unit alone. Specifically, Patent Document 1 has a rotating body called a phase shifter 7 at the end of the waveguide as shown in FIG. 21, and Patent Document 2 has a turntable (not shown) for rotating an object to be heated. Patent Document 3 describes a configuration in which the patch antenna 5 is also rotated in addition to the turntable 8 to be used as a stirrer. In any case, it is not described that a circularly polarized wave can be used without a drive unit. This is because if the drive unit is not provided with circular polarization, the uniformity is inferior to a general configuration with a drive unit (for example, a configuration in which a table is rotated or an antenna is rotated).

  The present invention solves the above-described problems, and an object thereof is to provide a microwave heating apparatus that can uniformly heat an object to be heated without using a driving unit.

In order to solve the above-described conventional problems, a microwave heating apparatus of the present invention includes a heating chamber that accommodates an object to be heated, microwave generation means that generates microwaves, a waveguide that transmits microwaves, A plurality of microwave radiating portions for radiating microwaves from the waveguide into the heating chamber, a standing wave is generated in the waveguide, and the plurality of microwave radiating portions are arranged in the waveguide. In the transmission direction, the arrangement is made at intervals exceeding 1/4 of the guide wavelength and less than 1/2, and the standing waves facing the adjacent microwave radiation portions are configured not to have an antiphase relationship , It has standing wave stabilizing means for stabilizing the standing wave position in the waveguide, and there are a plurality of standing wave stabilizing means, arranged in the transmission direction at an interval of about half of the guide wavelength, and transmitted. At least two constants arranged in the direction at an interval of about ½ of the guide wavelength. Wave stabilizing means (first standing wave stabilizing means and second standing wave stabilizing means counted from the end of the waveguide) and at least a distance of about 1/3 of the guide wavelength in the transmission direction Four microwave radiating parts (first microwave radiating part, second microwave radiating part, third microwave radiating part, fourth microwave radiating part counting from the end side of the waveguide) And a second microwave radiating section and a third microwave radiating section are arranged between the first standing wave stabilizing means and the second standing wave stabilizing means .

  With the above configuration, the standing wave in the waveguide generally repeats antinodes (sites that generate the maximum amplitude) and nodes (sites that generate almost no amplitude) every ½ of the wavelength in the transmission direction. When two places separated by a distance of / 2 are compared, there is an anti-phase relationship in which an opposite wave is generated with the same amplitude. However, in the present invention, a plurality of microwave radiating portions exceed 1/4 of the guide wavelength by 1 / By arranging at intervals less than 2, the standing waves facing the adjacent microwave radiation portions do not have an antiphase relationship (interval of odd multiples of approximately ½ of the guide wavelength). The microwaves radiated from the adjacent microwave radiating unit into the heating chamber are not in reverse phase, so that cancellation between so-called interference that weakens the space between the microwave radiating units can be prevented. Just arrange the microwave radiation parts of the drive unit Without using it can be uniformly heat the object to be heated in the heating chamber.

  In the microwave heating apparatus of the present invention, a plurality of microwave radiating portions are disposed at intervals that are less than ½ and less than ¼ of the in-tube wavelength, so that standing waves facing the adjacent microwave radiating portions Does not have an anti-phase relationship (an odd multiple of the half of the in-tube wavelength), and as a result, the microwave radiated from the adjacent microwave radiating unit into the heating chamber does not have an anti-phase. It is possible to prevent cancellation by so-called interference that weakens between the microwave radiation parts of each other, and it is possible to arrange the objects to be heated in the heating chamber without using a drive unit by arranging a plurality of microwave radiation parts. It can be heated uniformly.

The perspective view of the microwave heating apparatus in Embodiment 1 of this invention Sectional drawing (a) plane sectional view (b) front sectional view of microwave heating apparatus in Embodiment 1 of the present invention The perspective view explaining the waveguide applied to the microwave heating device in Embodiment 1 of this invention The simulation result which used the termination | terminus part of the waveguide applied to the microwave heating device in Embodiment 1 of this invention as a radiation boundary (a) Plane image figure of a simulation model (b) Plane sectional drawing of the electric field strength distribution in a warehouse The perspective view explaining the cylindrical standing wave stabilization means applied to the microwave heating apparatus in Embodiment 1 of this invention. Sectional drawing explaining the hemispherical standing wave stabilization means applied to the microwave heating apparatus in Embodiment 1 of this invention Sectional drawing (a) plane sectional view (b) front sectional view of the microwave heating apparatus of another form for comparing with the microwave heating apparatus in Embodiment 1 of this invention Explanatory drawing explaining the difference of the characteristic of Embodiment 1 of this invention and another form (a) Temperature distribution figure when a foodstuff is heated with a form different from this invention (b) Schematic figure of the heating unevenness ( c) Temperature distribution diagram when the food is heated in Embodiment 1 of the present invention (d) Schematic diagram of the heating unevenness Explanatory drawing explaining the characteristic difference by the pitch P between adjacent openings in Embodiment 1 of this invention (a) Model image figure of electromagnetic field analysis (b) Contour figure of analysis result in P = λg / 2 (c) Contour diagram of analysis results at P = λg / 3 Sectional drawing (a) plane sectional view (b) front sectional view of microwave heating apparatus in Embodiment 2 of the present invention Relationship explanatory drawing which shows the microwave radiation | emission part of the microwave heating apparatus in Embodiment 3 of this invention Problem explanatory drawing in the to-be-heated object mounting in the case of not using this Embodiment 3 for demonstrating the problem of the microwave radiation | emission part of the microwave heating apparatus in Embodiment 3 of this invention Explanatory drawing of the relationship when an object to be heated is placed in the heating chamber of the microwave heating apparatus according to Embodiment 3 of the present invention. Relationship explanatory drawing which shows the microwave radiation | emission part of the microwave heating apparatus in Embodiment 4 of this invention The schematic diagram explaining the electric current interruption effective width of the microwave radiation | emission part in Embodiment 4 of this invention Relationship explanatory drawing which shows the microwave radiation | emission part of the microwave heating apparatus in Embodiment 5 of this invention Relational explanatory diagram of the arrangement of the microwave radiation portion of the microwave heating apparatus according to the fifth embodiment of the present invention. Relation explanatory drawing which simplified the microwave radiation | emission part arrangement | positioning of the microwave heating apparatus in Embodiment 5 of this invention Relation explanatory drawing which simplified the microwave radiation | emission part arrangement | positioning of the microwave heating apparatus in Embodiment 5 of this invention Schematic diagram illustrating the opening shape of the microwave heating apparatus according to the sixth embodiment of the present invention. Configuration diagram of a microwave heating device that generates circularly polarized waves with a conventional X-shaped opening Configuration diagram of a conventional microwave heating device that generates circularly polarized waves with two orthogonal rectangular slits Configuration diagram of a microwave heating device that generates circularly polarized waves with a conventional patch antenna Configuration diagram of microwave heating device with conventional waveguide and rectangular slit

A microwave heating apparatus according to a first aspect of the present invention includes a heating chamber that houses an object to be heated, microwave generation means that generates microwaves, a waveguide that transmits microwaves, and the waveguide to the heating chamber. A plurality of microwave radiating portions for radiating microwaves, and standing waves are generated in the waveguide. The plurality of microwave radiating portions have an in-tube wavelength of 1 in the transmission direction of the waveguide. / 4 and less than ½, the standing waves facing the plurality of adjacent microwave radiating portions are configured not to have an antiphase relationship, and the standing waves in the waveguide To stabilize the position
The standing wave stabilizing means includes a plurality of standing wave stabilizing means, arranged in the transmission direction at an interval of approximately ½ of the guide wavelength, and arranged in the transmission direction at an interval of approximately ½ of the guide wavelength. And at least two standing wave stabilizing means (first standing wave stabilizing means and second standing wave stabilizing means counted from the end of the waveguide), and approximately 1/3 of the guide wavelength in the transmission direction. At least four microwave radiating portions arranged at intervals of the first microwave radiating portion, the second microwave radiating portion, the third microwave radiating portion, and the fourth And a second microwave radiating portion and a third microwave radiating portion are disposed between the first standing wave stabilizing means and the second standing wave stabilizing means .

With the above configuration, the standing wave in the waveguide generally repeats antinodes (sites that generate the maximum amplitude) and nodes (sites that generate almost no amplitude) every ½ of the wavelength in the transmission direction. When two places separated by a distance of / 2 are compared, there is an anti-phase relationship in which an opposite wave is generated with the same amplitude. However, in the present invention, a plurality of microwave radiating portions exceed 1/4 of the guide wavelength by 1 / By arranging at intervals less than 2, the standing waves facing the adjacent microwave radiation portions do not have an antiphase relationship (interval of odd multiples of approximately ½ of the guide wavelength). The microwaves radiated from the adjacent microwave radiating unit into the heating chamber are not in reverse phase, so that cancellation between so-called interference that weakens the space between the microwave radiating units can be prevented. Just arrange the microwave radiation parts of the drive unit Without using it can be uniformly heat the object to be heated in the heating chamber.
In general, when the number of microwave radiation parts increases, the microwaves in the waveguide are easily radiated to the outside, and the microwaves are radiated one after another, making it difficult to maintain the standing wave in the waveguide. The state becomes unstable, and as a result, the phase of the microwaves facing each microwave radiation part may shift from the target phase. Wave turbulence can be suppressed, and standing waves can be opposed to multiple microwave radiating sections with the targeted phase, and microwaves with the intended phase can be radiated from the respective microwave radiating sections toward the heating chamber. Therefore, the object to be heated in the heating chamber can be uniformly heated by arranging a plurality of microwave radiating units without using a driving unit.
In general, when an in-tube standing wave is generated, the same amplitude should be repeated every integral multiple of ½ of the in-tube wavelength. By arranging them at integer multiple intervals, it is possible to ensure the periodicity of the standing wave in the tube, suppress the turbulence of the standing wave, and generate the standing wave at the target phase in the multiple microwave radiation parts. Since the microwaves with the intended phase can be radiated from the respective microwave radiating units toward the heating chamber, it is possible to arrange a plurality of microwave radiating units without using a driving unit. An object to be heated in the heating chamber can be heated uniformly.
Furthermore, in the center of the two standing wave stabilizing means (first standing wave stabilizing means and second standing wave stabilizing means) that generate nodes at intervals of approximately half of the guide wavelength, there is one A belly occurs. Further, two microwave radiating sections (second second) having an interval of about 1/3 of the guide wavelength between the same two standing wave stabilizing means (first standing wave stabilizing means and second standing wave stabilizing means). The two microwave radiating parts (second microwave radiating part and third microwave radiating part) are not nodes and antinodes. It will be placed in each, but if anything, it will be closer to the node. This is because two microwave radiating sections (second microwave radiating section and third microwave radiating section) are replaced with two standing wave stabilizing means (first standing wave stabilizing means and second standing wave stabilizing means). Assuming that the distance from the microwave radiation part to the node is ((approx. 1/2 of the guide wavelength)-(approx. 1/3 of the guide wavelength)
) / 2≈ 1/12 of the wavelength inside the tube, and the distance from the microwave radiation part to the antinode is (approximately 1/3 of the wavelength inside the tube) / 2≈ 1/6 of the wavelength inside the tube, and the distance from the antinode to the node Is closer to half the distance. On the other hand, if calculated in the same manner, the first microwave radiating portion and the fourth microwave radiating portion are antinodes having substantially the same phase. This is because, for example, considering the position of the node by the first standing wave stabilizing means as a reference, the distance from the second microwave radiating section to the reference node is 1/12 of the in-tube wavelength, as previously determined. From the microwave radiating part to the first microwave radiating part is 1/3 of the in-tube wavelength, so from the reference node to the first microwave radiating part (approximately 1/3 of the in-tube wavelength) − ( It is approximately 1/12 of the in-tube wavelength.apprxeq.1 / 4 of the in-tube wavelength, and this is a positional relationship that is exactly antinode when viewed from the reference node. Similarly, the fourth microwave radiating portion becomes angry, and in particular, the distance between the first microwave radiating portion and the fourth microwave radiating portion is approximately 1/3 × 3 of the guide wavelength. Therefore, both are in the same phase. As described above, the second microwave radiating part and the third microwave radiating part are both close to the node, and the first microwave radiating part and the fourth microwave radiating part are both in the same phase and close to the belly, When viewed from these centers, the four microwave radiating portions can have a symmetric phase relationship in the transmission direction, and as a result, the possibility of being able to radiate uniformly in the transmission direction can be increased.

In the microwave heating apparatus according to the second aspect of the invention, the plurality of microwave radiating portions are arranged at an interval of approximately 1/3 of the guide wavelength in the transmission direction. Thereby, the effect of the first invention can be obtained with certainty. That is, in the present invention, a plurality of microwave radiating portions are arranged at an interval of approximately 1/3 of the guide wavelength, so that the standing waves facing the adjacent microwave radiating portions have an antiphase relationship (approximately 1 of the guide wavelength). As a result, the microwaves radiated from the adjacent microwave radiating portions into the heating chamber are not in antiphase, and the space between the microwave radiating portions is weak. The so-called cancellation due to so-called interference can be prevented, and the object to be heated in the heating chamber can be uniformly heated by arranging a plurality of microwave radiation portions without using a drive portion. Furthermore, in the first invention, when attention is paid to two separate microwave radiating portions that are not adjacent to each other, there is a risk of an anti-phase relationship, and although the possibility is low because the distance is far away, there is a risk of canceling each other Remains. On the other hand, in the second invention, even if the distance between the microwave radiating portions that are not adjacent to each other is seen, there is no antiphase relationship anywhere, and it is possible to avoid canceling each other. This is because when there are four or more microwave radiation parts, the first and second intervals are λg / 3, the first and third intervals are 2λg / 3, and the first and fourth intervals. This is because the interval is λg, exactly one wavelength, and the fourth phase returns to the same phase as the first one, and thereafter the same phase relationship is repeated. Therefore, no interval that is an odd multiple of approximately ½ of the guide wavelength occurs anywhere.

In the microwave heating apparatus of the third invention, the standing wave stabilizing means is configured to generate a node of the standing wave in the waveguide, and is approximately ½ of the in-tube wavelength in the transmission direction to the terminal end of the waveguide. It is set as the structure arrange | positioned at the distance of integral multiple of. As a result, the end portion of the waveguide originally becomes a standing wave node because the electric field is always 0. In addition, when a standing wave in the tube is generated, from the end portion to every integral multiple of 1/2 of the in-tube wavelength. The node should be repeated, but the standing wave stabilizing means can be reliably formed by placing the standing wave stabilizing means at a distance that is an integral multiple of approximately one half of the guide wavelength from the end of the waveguide. Wave turbulence can be suppressed, and standing waves can be opposed to multiple microwave radiating sections with the targeted phase, and microwaves with the intended phase can be radiated from the respective microwave radiating sections toward the heating chamber. Therefore, the object to be heated in the heating chamber can be uniformly heated by arranging a plurality of microwave radiating units without using a driving unit.

A microwave heating apparatus according to a fourth aspect of the present invention includes third standing wave stabilizing means arranged at an interval of about ½ of the guide wavelength in the transmission direction from the second standing wave stabilizing means, and a waveguide A first microwave radiating portion is disposed between the terminal portion of the first standing wave stabilizing means and the first standing wave stabilizing means, and a fourth microwave is disposed between the second standing wave stabilizing means and the third standing wave stabilizing means. The microwave radiation unit is arranged. Thus, the first microwave radiating portion is more reliably disposed by arranging the first microwave radiating portion between the terminal end portion of the waveguide, which is a node, and the first standing wave stabilizing means. And a fourth microwave radiating section is arranged between the second standing wave stabilizing means and the third standing wave stabilizing means arranged at an interval of about ½ of the guide wavelength in the transmission direction. By doing so, the fourth microwave radiating portion can also be made more reliably, so that the effect of the first invention can be obtained with certainty.

In the microwave heating apparatus of the fifth invention, the first microwave radiating part and the fourth microwave radiating part are arranged substantially at the antinode position of the standing wave in the tube, and the second microwave radiating part and the third microwave radiating part are arranged. The microwave radiating part is arranged at a position where neither the antinode nor the node of the standing wave in the tube is located. As a result, the phases of the four microwave radiation portions can be specified to some extent, so that the effects of the sixth invention and the seventh invention can be obtained more reliably.

In the microwave heating apparatus according to the sixth aspect of the invention, the plurality of microwave radiating portions are configured with openings that do not extend to the center (tube axis) in the width direction of the waveguide, and are arranged on at least one side of the tube axis. Thus, in the width direction of the waveguide, in the most common TE10 mode waveguide, the electric field is maximum at the center (tube axis) in the width direction of the waveguide, and the electric field is zero at both ends. If the opening crosses the tube axis, it will cross the maximum point of the electric field, and there is a risk that a large amount of microwaves will be emitted from one opening, and there will be no remaining portion that should be shared equally by the other opening. In the present invention, since the opening does not reach the tube axis, the amount of radiation from one opening is suppressed, and a plurality of openings can radiate evenly in a balanced manner. Therefore, according to the configuration of the present invention, since an equal amount of microwaves can be radiated from a plurality of openings over a wide range toward the heating chamber, it is possible to arrange a plurality of microwave radiating units and arrange the microwave chambers without using a driving unit. The object to be heated can be heated uniformly.

In the microwave heating apparatus of the seventh invention, the plurality of microwave radiating portions are arranged symmetrically on both sides of the tube axis. Thereby, more openings can be formed as a plurality of arrangements in the width direction. With respect to the width direction of the waveguide, in the most common TE10 mode waveguide, the electric field is maximum at the center (tube axis) in the width direction of the waveguide, and the electric field is zero at both ends. Therefore, if the openings are arranged on both sides of the tube axis, it is easy to radiate the same amount of microwaves. Therefore, according to the configuration of the present invention, a microwave radiating portion that can radiate a large number of equivalent amounts in both the transmission direction and the width direction is provided, and the same amount of microwaves can be radiated in a wide range toward the heating chamber. For this reason, the object to be heated in the heating chamber can be uniformly heated without using a drive unit by arranging a plurality of microwave radiation units.

In the microwave heating apparatus according to the eighth aspect of the invention, the microwave radiating unit radiates circularly polarized waves. As a result, an electric field that rotates in a 360-degree omnidirectional characteristic of circularly polarized waves is generated around the microwave radiation part, and microwaves are radiated from the center so as to vortex, thereby heating the circumferential direction uniformly. Can do. Therefore, by radiating circularly polarized waves from a plurality of microwave radiating sections, microwaves can be radiated evenly to the entire heating chamber, and heating can be performed without using a drive section by simply arranging a plurality of microwave radiating sections. The object to be heated in the room can be heated uniformly.

In the microwave heating apparatus of the ninth invention, the microwave radiating portion that radiates circularly polarized waves has a substantially X-shaped configuration in which two long holes intersect. Thereby, circularly polarized waves can be reliably radiated from the waveguide with a simple configuration.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of a microwave heating apparatus according to the invention will be described with reference to the accompanying drawings. In the microwave heating apparatus of the following embodiment, a microwave oven will be described. However, the microwave oven is an example, and the microwave heating apparatus of the present invention is not limited to the microwave oven, and uses dielectric heating. And a microwave heating device such as a garbage processing machine or a semiconductor manufacturing device. Further, the present invention is not limited to the specific configurations of the following embodiments, and configurations based on similar technical ideas are included in the present invention.

(Embodiment 1)
1 and 2 are explanatory diagrams of the microwave heating apparatus according to Embodiment 1 of the present invention. FIG. 1 is a perspective view showing the overall configuration, FIG. 2A is a sectional view seen from above, and FIG. 2B is a sectional view seen from the front.

A microwave oven 101, which is a typical microwave heating apparatus, includes a heating chamber 102 that can store food (not shown) that is a typical object to be heated, and a typical microwave generation means that generates microwaves. A certain magnetron 103, a waveguide 104 that guides the microwave radiated from the magnetron 103 to the heating chamber 102, and the waveguide 104 as a microwave radiating unit that radiates the microwave in the waveguide 104 into the heating chamber 102. There are eight openings 105a, 105b, 105c, 105d provided on the upper surface of the slab, and a mounting table 107 on which food (not shown) is mounted. The heating chamber 102 is a horizontally long rectangular parallelepiped, and the mounting table 107 is configured to cover the entire bottom surface of the heating chamber 102.
The openings 105a, 105b, 105c, and 105d are closed so that they are not exposed in the cabinet, and the upper surface is flattened so that the user can easily take in and out food (not shown), or can be wiped off when dirty. Yes. Here, the mounting table 107 is made of a material that easily transmits microwaves, such as glass or ceramic, in order to radiate microwaves from the openings 105 into the heating chamber 102. The waveguide 104 and the heating chamber 102 are connected with the microwave transmission direction of the waveguide 104 directed in the width direction of the heating chamber 102. The opening 105 is an opening that can emit circularly polarized waves due to an X-shaped shape that intersects the long holes, and is arranged symmetrically in the width direction so as not to reach the center (tube axis) 108 in the width direction of the waveguide 104. doing. The tube axis 108 is aligned with the center in the front-rear direction of the bottom surface 109 of the heating chamber 102, and the eight openings 105 a, 105 b, 105 c, 105 d are arranged symmetrically with respect to the center 110 in the left-right direction of the bottom surface 109 of the heating chamber 102. As described above, the openings 105a, 105b, 105c, and 105d are arranged symmetrically with respect to the bottom surface 109 of the heating chamber 102 in the front-rear and left-right directions. The openings 105a, 105b, 105c, and 105d are arranged in the transmission direction of the waveguide 104 at an interval of about 1/3 of the guide wavelength λg. An in-tube standing wave is generated in the waveguide 104, which repeats the belly and node every 1/2 of the in-tube wavelength λg determined by the oscillation frequency of the magnetron 103 and the shape of the waveguide 104. The terminal portion 111 of the wave tube 104 is always a node. Here, FIG. 2B shows an image of the standing wave in the waveguide 104. The standing wave stabilizing means 112a, 112b, and 112c are made of a conductive material protruding into the waveguide 104, and have a configuration similar to a stub tuner or the like known as a so-called matching element. That is, a total of three are arranged at intervals of approximately ½ each of the in-tube wavelength λg from the terminal end 111, and counted from the terminal end 111 side, the first standing wave stabilizing means 112a and the second standing wave stabilizing means 112b. , Third standing wave stabilizing means 112c. Similarly, the openings 105a, 105b, 105c, and 105d are counted as the first opening 105a, the second opening 105b, the third opening 105c, and the fourth opening 105d from the terminal end 111 side. At this time, the waveguide 104 is configured so that the first standing wave stabilizing means 112a and the second standing wave stabilizing means 112b are symmetrical with respect to the center 110 in the left-right direction of the bottom surface 109 of the heating chamber 102. As a result, the antinode of the standing wave in the tube is positioned at the center 110 as shown in FIG. The first opening 105a is located at the antinode of the standing wave in the tube between the terminal end portion 111 and the first standing wave stabilizing means 112a, and the fourth opening 105d is the second standing wave stabilizing means 112b and the first standing wave stabilizing means 112b. The second standing wave 105b and the third opening 105c are located at a position where neither the antinode nor the node of the standing wave is located between the third standing wave stabilizing means 112c. become. In addition, as shown in FIG. 1, a door 116 that can be opened and closed is provided, and by closing the door 116, a microwave forms a closed space between the waveguide 104 and the heating chamber 102, and the confined microwave is always defined. It will cause standing waves.

The operation will be described based on the above configuration. The microwave radiated from the magnetron 103 is transmitted through the waveguide 104, and a part thereof is radiated into the heating chamber 102 from the openings 105a, 105b, 105c, and 105d, but the rest is reflected by the terminal end 111. . In addition, since the heating chamber is a closed space, it is considered that a part of the microwave in the heating chamber 102 returns to the waveguide 104 through the openings 105a, 105b, 105c, and 105d. As a result, some standing wave is generated in the waveguide 104 and the heating chamber 102. In particular, with respect to the waveguide 104, it is considered that a standing wave with an in-tube wavelength λg is likely to occur if the reflection at the terminal end 111 is dominant. In particular, under the condition that the object to be heated is easy to absorb a large amount of microwaves, the standing wave is stabilized because the amount of microwaves returning from the heating chamber into the waveguide 104 through the openings 105a, 105b, 105c, and 105d is small. On the other hand, if the number of openings is large as in this embodiment under the condition that the object to be heated is small or difficult to absorb microwaves, the communication between the openings 105a, 105b, 105c, 105d and the heating chamber 102 is established. Will cause the standing wave in the pipe to be disturbed, and it will change depending on the amount of the heated object, the material, and the way it is placed, so the amplitude and phase of the standing wave in the pipe at the opening position cannot be fixed. Therefore, there is a possibility that the amount of radiation from each opening may increase or decrease without control. Therefore, there is a possibility that the entire heating chamber 102 cannot be radiated uniformly. However, in the present embodiment, the standing wave stabilizing means 112a, 112b, and 112c are arranged in the waveguide 104, so that the node position of the in-tube standing wave can be fixed, and as a result, the respective opening positions. The amplitude and phase at can also be fixed. In addition, the microwave is radiated into the heating chamber 102 as a circularly polarized wave by the configuration of the openings 105a, 105b, 105c, and 105d. Circularly polarized waves are radiated while rotating an electric field in the circumferential direction around the openings 105a, 105b, 105c, and 105d, and the openings 105a, 105b, 105c, and 105d are formed in the heating chamber 102 as shown in FIG. Is arranged symmetrically with respect to the bottom surface 109 in both the front-rear direction and the left-right direction, so that the microwaves are radiated equally both in the front-rear direction and in the left-right direction, and are uniformly radiated around.

  Here, circular polarization will be described. Circular polarization is a technology widely used in the fields of mobile communication and satellite communication. Examples of familiar use include an ETC (Electronic Toll Collection System) “non-stop automatic toll collection system” and the like. Circular polarization is a microwave in which the polarization plane of the electric field rotates with respect to the traveling direction, and when the circular polarization is formed, the direction of the electric field continues to change with time, and the magnitude of the electric field strength Has the characteristic of not changing. If this circularly polarized wave is applied to a microwave heating device, it is expected that the object to be heated will be heated evenly, particularly in the circumferential direction of the circularly polarized wave, as compared with the conventional microwave heating by linearly polarized wave. The Note that circularly polarized waves are classified into two types, ie, right-handed polarization (CW: clockwise) and left-handed polarization (CCW: counterclockwise) from the direction of rotation, but there is no particular difference in performance in the field of heating.

  As circularly polarized waves, there are those constituted by the opening of the waveguide wall surface as in Patent Literature 1 and Patent Literature 2, and those constituted by the patch antenna as shown in Patent Literature 3, but this embodiment The openings 105a, 105b, 105c, and 105d are formed on the upper surface (H surface) of the waveguide 104 and emit circularly polarized waves in the same manner as disclosed in Patent Document 1.

  Since circularly polarized waves are primarily used in the field of communications, they are generally discussed in terms of so-called traveling waves that do not return reflected waves because they are intended for radiation into open spaces. On the other hand, the microwave heating apparatus according to the present embodiment emits radiation into a closed space shielded from the outside by the waveguide 104 and the heating chamber 102, and the reflected wave returns and is synthesized in the waveguide. Although the wave is discussed, it is considered that the standing wave is out of balance at the moment when the microwave is radiated from the aperture, and the traveling wave is generated until it returns to the stable standing wave again. Therefore, by making the opening have a circularly polarized radiation shape, it is possible to utilize the above-described features of circularly polarized waves, and the heating distribution in the heating chamber 102 can be made more uniform.

  In order to output circularly polarized waves from the opening provided in the rectangular waveguide 104, two slits having a width are intersected at the center as shown in the example of FIG. A configuration in which a shape inclined by 45 degrees with respect to the waveguide 104 in the microwave transmission direction of the waveguide 104 is desirably disposed at a position that does not pass through the tube axis 108 is desirable.

  Here, the waveguide will be described with reference to FIG. FIG. 3 is a perspective view illustrating a waveguide applied to the microwave heating apparatus according to Embodiment 1 of the present invention. The simplest and most common waveguide is a rectangular waveguide made of a rectangular parallelepiped having a certain rectangular cross section (width a, height b) extended in the transmission direction as shown in FIG. Is selected in the range of the waveguide width a (microwave wavelength λ0> a> λ0 / 2) and height b (<λ0 / 2). Is known to transmit.

  The TE10 mode refers to a transmission mode in an H wave (TE wave; electrical transverse wave) that has only a magnetic field component in the waveguide transmission direction in the waveguide 104 and no electric field component. Point to. Note that transmission modes other than the TE10 mode are rarely applied to the waveguide 104 of the microwave heating apparatus 101.

  Prior to the description of the guide wavelength λg in the waveguide, the free space wavelength λ0 will be described. The wavelength λ0 in free space is known as about 120 mm in the case of a microwave in a general microwave oven. However, to be precise, the wavelength λ0 of the free space is obtained by λ0 = c / f, and c is a speed and constant at the speed of light 3.0 * 10 ^ 8 [m / s], but f is a frequency of 2. There is a width of 4 to 2.5 [GHz] (ISM band). Since the oscillation frequency f of the magnetron changes depending on variations and load conditions, the wavelength λ0 of the free space also changes eventually, from a minimum of 120 [mm] (at 2.5 GHz) to a maximum of 125 [mm] (at 2.4 GHz). Change to.

  Returning to the description of the waveguide, in consideration of the range of the wavelength λ0 in free space, the width a of the waveguide is generally selected to be 80 to 100 mm and the height b is often set to about 15 to 40 mm. At this time, the upper and lower wide surfaces in FIG. 4 are referred to as the H surface 126 in the sense that the magnetic field vortexes in parallel, and the left and right narrow surfaces are referred to as the E surface 127 in the sense that they are parallel to the electric field. Incidentally, the wavelength when the microwave is transmitted through the waveguide is expressed as the waveguide wavelength λg and becomes λg = λ0 / √ (1- (λ0 / (2 × a)) ^ 2), and the width of the waveguide It varies depending on the dimension a, but is determined regardless of the height b. Incidentally, in the TE10 mode, the electric field is zero at both ends (E plane) 127 in the width direction of the waveguide, and the electric field is maximum at the center in the width direction. Therefore, the magnetron 103 is coupled to the center in the width direction of the waveguide (on the tube axis 108 shown in FIG. 2) where the electric field is maximum.

  Incidentally, the openings 105a, 105b, 105c, and 105d in the present embodiment are X-shaped openings with the long holes orthogonal to each other as shown in FIG. It is a shape that can generate circularly polarized waves by being offset from one axis) to one side, and the direction of rotation of the electric field differs depending on which of the H planes is approached, and is divided into right-handed polarized waves or left-handed polarized waves Become.

  Hereinafter, characteristics of the X-shaped opening that radiates circularly polarized waves will be described. FIG. 4 shows the simulation result. Since it is a simulation, unlike the actual case, the wall surface of the heating chamber 128 is all set as a radiation boundary (boundary condition in which microwaves are not reflected), and the end portion 131 of the waveguide 130 is also a radiation boundary with a simple configuration having only one opening 129. (Boundary conditions where microwaves are not reflected). FIG. 4A is a model shape seen from above, and FIG. 4B is a contour diagram of the electric field strength in the heating chamber seen from above, showing the analysis result. As shown in FIG. 4B, the electric field is swirled like circularly polarized waves, and the transmission direction 132 (left and right direction of the paper) of the waveguide 130 around the opening 129 and the width direction 133 of the waveguide (paper surface). It seems that a uniform electric field distribution is generated in the vertical direction).

  Here, there are some differences between the open space communication field and the closed space heating field, so a description will be added. In the communication field, we want to send and receive only the necessary information while avoiding mixing with other microwaves, so the transmitting side is limited to either right-handed polarization or left-handed polarization, and the receiving side also adjusts accordingly. The optimum receiving antenna will be selected. On the other hand, in the field of heating, an object to be heated such as food with no directivity is subjected to microwaves instead of a receiving antenna having directivity, so that it is only important that the microwaves uniformly strike the entire object to be heated. . Therefore, in the field of heating, there is no problem even if right-handed polarization and left-handed polarization are mixed, but conversely, it is necessary to prevent uneven distribution as much as possible depending on the position and shape of the object to be heated. For example, when there is only a single opening 129 as shown in FIG. 4, it is better to place the object to be heated directly above the opening 129. However, if the object to be heated is shifted back and forth or left and right, the part close to the opening 129 is easily heated. , Distant parts are difficult to be heated, resulting in uneven heating. Therefore, it is desirable to have a plurality of circularly polarized apertures. In the present embodiment, as shown in FIG. 2, the eight openings 105a, 105b, 105c, and 105d are arranged symmetrically and in a balanced manner in the heating chamber as described above.

  Here, the standing wave stabilizing means will be described with reference to FIGS.

FIG. 5 shows a structure in which standing wave stabilizing means 134 and 135 are arranged in the waveguide 104 described with reference to FIG. The standing wave stabilizing means 134 and 135 are cylindrical and made of a conductive material such as aluminum or stainless steel, and are connected and fixed to the center in the width direction of the H surface 126 of the waveguide 104 by welding or screwing. . The standing wave stabilizing means 134 and 135 having such a configuration is considered to partially prevent transmission of microwaves as a protruding portion in the waveguide 104, but as a result, the standing wave stabilizing means 134 and 135. It has been found that it is easy to become a standing wave node at a position. Therefore, conversely, by providing the protruding portions such as the standing wave stabilizing means 134 and 135 at the position where the standing wave is desired, there is an effect of stabilizing the standing wave without changing the position. The structures of the standing wave stabilizing means 134 and 135 are similar to those of a stub tuner known as a so-called matching element, and by adjusting the shape (particularly the height) and the position, the node of the standing wave can be adjusted. It seems that it is possible to have two functions that can be matched while confirming. FIG. 5 shows an example in which the standing wave stabilizing means 134 is higher in height than the standing wave stabilizing means 135, but there is no particular limitation and the shape may be optimized as appropriate. In FIG. 5, the distance between the standing wave stabilizing means 134 and 135 is (λg / 2) × n using the in-tube wavelength λg, and n is an integer, so that nodes can be created in two places. In particular, a clean standing wave exists between the standing wave stabilizing means 134 and 135. For example, when n = 1, the standing wave stabilizing means 134 and 135 are nodes and the center of both is antinode, and when n = 2, the standing wave stabilizing means 134 and 135 is a node and the center of both is also a node. Therefore, if n is an integer, a beautiful standing wave can be created between the standing wave stabilizing means 134 and 135.

  FIG. 6 shows an example of another standing wave stabilizing means, not a separate component, but a hemispherical standing wave stabilizing means 136 in which the H surface of the waveguide 104 is squeezed by a press or the like and protruded into the waveguide 104. This is an example of the configuration. In this case, since the standing wave stabilizing means can be formed of the waveguide material itself, there is an effect that a separate component for stabilizing the standing wave is not required as compared with the example of FIG.

  Here, with reference to FIGS. 7 to 9, the effect of preventing cancellation by so-called interference that weakens between adjacent microwave radiation portions by the configuration of the present invention will be described.

  FIG. 7 is a cross-sectional view of another form of microwave heating apparatus (six openings, arranged at λg / 2 pitch) for comparison with the present invention, (a) a plan cross-sectional view, and (b) a front cross-sectional view. is there. The main difference from the present embodiment (FIG. 2, eight openings, arranged at λg / 3 pitch) is that the six openings 137a, 137b, 137c are ½ the guide wavelength λg in the transmission direction of the waveguide. It is that it is arranged in. As an initial speculation, if the apertures are arranged at a distance of ½ of the guide wavelength λg, all the openings are located at the same position of the standing wave in the guide (the direction is inverted every λg / 2), so the same amount of microwaves I thought it would be able to heat the most evenly, but that was not the case.

  FIG. 8 is a diagram for explaining the difference in characteristics between the embodiment of the present invention (eight openings, arranged at λg / 3 pitch) and another form (six openings, arranged at λg / 2 pitch). (A) Temperature distribution diagram when food (frozen pilaf) is heated in a form different from the present invention (six openings, arranged at λg / 2 pitch), (b) Schematic diagram of uneven heating, (c) ) Temperature distribution when food (frozen pilaf) is heated in the embodiment of the present invention (eight openings, arranged at λg / 3 pitch), (d) is a schematic diagram of uneven heating. (A) (c) is a measurement of the surface temperature from the top with a thermoviewer after heating the frozen pilaf for a certain time in each configuration. (A) Another form (six openings, arranged at λg / 2 pitch) However, in the embodiment of the present invention (arranged at eight openings, λg / 3 pitch), the area 138 is more unheated in the vertical direction of the paper (the front-back direction of the pilaf). It is fairly uniform. This is schematically represented as (b) and (d), and clearly the embodiment of the present invention (eight openings, arranged at λg / 3 pitch) is another form (six openings, It can be said that the distribution is better than that at the λg / 2 pitch.

In order to investigate this cause, an electromagnetic field analysis was performed. FIG. 9 shows adjacent openings 139a and 139b.
The difference in the characteristics due to the pitch P between the two is described. (A) Model image diagram of electromagnetic field analysis, (b) Contour diagram of the analysis result at P = λg / 2 (corresponding to another form of FIG. 8) (C) is a contour diagram of the analysis result at P = λg / 3 (corresponding to the embodiment of the present invention in FIG. 8). In (b), it seems that the space between the openings 139a and 139b is weak, and in particular, it seems to diffuse in opposite directions as the distance from the opening increases in the vertical direction of the drawing. On the other hand, in (c), although the pitch of the openings 139a and 139b is as narrow as λg / 3, the interference is not seen as much as in (b), but integrated (as shown in FIG. 9 (c), the openings are connected). It seems to be emitted. Therefore, it is considered that the interference does not occur simply because the distance is short, but is related to the phase of the standing wave in the tube. Considering this reason, when the pitch is λg / 2, the apertures 139a and 139b are positions of the same magnitude of the standing wave in the tube, but the direction is the opposite direction, so that the interference (such as weakening) It is thought that cancellations have occurred. On the other hand, when the pitch is λg / 3, since the openings 139a and 139b are not in opposite positions, it is considered that interference (cancellation) that weakens the gap does not occur.

  Below, the operation and effect of the present embodiment will be described.

  A microwave oven 101 according to this embodiment includes a heating chamber 102 that stores an object to be heated, a magnetron 103 that serves as a microwave generation unit that generates microwaves, a waveguide 104 that transmits microwaves, and a waveguide 104 has openings 105a, 105b, 105c, and 105d as microwave radiating portions that radiate microwaves into the heating chamber 102. A standing wave is generated in the waveguide 104, and a plurality of openings 105a, 105b, 105c and 105d are arranged in the transmission direction of the waveguide 104 at intervals exceeding 1/4 of the in-tube wavelength and less than 1/2. As a result, in general, the standing wave in the waveguide repeats antinodes (sites that generate the maximum amplitude) and nodes (sites that generate little amplitude) every 1/2 of the guide wavelength in the transmission direction. Comparing two places separated by 2 gives the opposite phase relationship in which the amplitude is the same and a reverse wave is generated. However, in the present invention, the plurality of apertures 105a, 105b, 105c, and 105d exceed 1/4 of the guide wavelength. Therefore, the standing wave facing the adjacent aperture does not have an antiphase relationship (an interval that is an odd multiple of approximately ½ of the guide wavelength). The microwaves radiated from the adjacent openings into the heating chamber 102 are not out of phase, so that canceling by so-called interference that weakens between the openings can be prevented. 105b, 105c, 105d Bell can also uniformly heat the object to be heated in the heating chamber 102 without using only the drive unit.

  In addition, the microwave oven 101 according to the present embodiment is configured such that the plurality of openings 105a, 105b, 105c, and 105d are arranged at intervals of about 1/3 of the guide wavelength in the transmission direction. Thereby, the effect of the first invention can be obtained with certainty. That is, in the present invention, the plurality of openings 105a, 105b, 105c, and 105d are arranged at an interval of approximately 1/3 of the guide wavelength, so that the standing wave that faces the adjacent openings has an antiphase relationship (approximate guide wavelength). As a result, the microwaves radiated from the adjacent openings into the heating chamber 102 are not out of phase, and the space between the openings becomes weak. Cancellation due to so-called interference can be prevented, and the object to be heated in the heating chamber 102 can be heated uniformly without using a driving unit by arranging a plurality of openings 105a, 105b, 105c, and 105d. Furthermore, in the first invention, when attention is paid to two distant openings that are not adjacent to each other, there is a risk of an antiphase relationship, and although there is a possibility that the possibility is low because the distance is far away, there remains a risk of canceling each other. On the other hand, in the second invention, no matter what the distance between the openings that are not adjacent to each other is seen, there is no anti-phase relationship anywhere, and it is possible to absolutely cancel each other. This is because when there are four or more openings, the first and second intervals are λg / 3, the first and third intervals are 2λg / 3, and the first and fourth intervals are λg. This is because the interval is exactly one wavelength, and the fourth phase returns to the same phase as the first one, and thereafter the same phase relationship is repeated. Therefore, no interval that is an odd multiple of approximately ½ of the guide wavelength occurs anywhere.

  Further, the microwave oven 101 of the present embodiment is configured to have standing wave stabilizing means 112a, 112b, and 112c for stabilizing the standing wave position in the waveguide 104. As a result, generally, when the number of openings increases, the microwave in the waveguide 104 is easily radiated to the outside, and the standing waves in the waveguide 104 are difficult to maintain due to the microwaves being radiated one after another. The state of the wave becomes unstable, and as a result, the phase of the microwaves facing the respective openings may shift from the target phase. However, the standing wave stabilizing means 112a, 112b, and 112c are provided. Thus, the disturbance of the standing wave can be suppressed, and the standing wave can be opposed to the plurality of openings 105a, 105b, 105c, and 105d with the aimed phase, and each opening 105a, 105b, 105c, and 105d is aimed as intended. Can be radiated toward the inside of the heating chamber 102, so that the plurality of openings 105a, 105b, 105c, and 105d can be simply arranged. Part of it is also possible to uniformly heat an object to be heated in the heating chamber 102 without using.

  Further, in the microwave oven 101 of the present embodiment, the standing wave stabilizing means 112 a, 112 b, and 112 c are configured to generate a standing wave node in the waveguide 104, up to the terminal end 111 of the waveguide 104. It is configured to be arranged at a distance that is an integral multiple of approximately ½ of the guide wavelength λg in the transmission direction. As a result, the end portion 111 of the waveguide 104 originally becomes a node of a standing wave because the electric field is always 0, and in addition, when an in-tube standing wave is generated, an integer of 1/2 of the in-tube wavelength from the end portion 111 is generated. The node should be repeated every time, but the standing wave stabilizing means 112a, 112b, and 112c are reliably disposed at a distance that is an integral multiple of approximately ½ of the guide wavelength λg from the terminal end 111 of the waveguide 104. Knots can be formed, the disturbance of the standing wave can be suppressed, and the standing waves can be opposed to the plurality of openings 105a, 105b, 105c, and 105d in the intended phase. , 105c, 105d can radiate microwaves of the intended phase toward the inside of the heating chamber 102, so that the drive unit can be moved only by arranging a plurality of openings 105a, 105b, 105c, 105d. Or without it can be uniformly heat the object to be heated in the heating chamber 102.

  In addition, the microwave oven 101 according to the present embodiment has a configuration in which a plurality of standing wave stabilizing means 112a, 112b, and 112c are provided and arranged in the transmission direction at intervals of approximately ½ of the guide wavelength λg. As a result, in general, when a standing wave in the tube is generated, the same amplitude should be repeated every integral multiple of ½ of the wavelength λg in the tube. However, a plurality of standing wave stabilizing means 112a, 112b, and 112c are used in the transmission direction. Arranging at intervals of an integer multiple of approximately half of the wavelength can ensure the periodicity of the standing wave in the tube, suppress the disturbance of the standing wave, and provide a plurality of openings 105a, 105b, 105c, Since the standing wave can be opposed to the target phase at 105d, and the microwave with the target phase can be radiated from the respective openings 105a, 105b, 105c, and 105d toward the heating chamber 102, By simply arranging a plurality of openings 105a, 105b, 105c, and 105d, the object to be heated in the heating chamber 102 can be uniformly heated without using a driving unit.

In addition, the microwave oven 101 of the present embodiment has at least two standing wave stabilizing means (first counting from the terminal end side of the waveguide) arranged in the transmission direction at an interval of about ½ of the guide wavelength λg. The standing wave stabilizing means 112a and the second standing wave stabilizing means 112b) and at least four microwave radiating portions (from the end of the waveguide) arranged in the transmission direction at an interval of about 1/3 of the guide wavelength. 1st opening 105a, 2nd opening 105b, 3rd opening 105c, and 4th opening 105d), and it has 1st standing wave stabilization means 112a and 2nd standing wave stabilization means 112b. The second opening 105b and the third opening 105c are arranged between them. As a result, the center of the two standing wave stabilizing means (the first standing wave stabilizing means 112a and the second standing wave stabilizing means 112b) that respectively generate nodes at intervals of approximately ½ of the guide wavelength λg. Produces one belly. The same two standing wave stabilizing means (first standing wave stabilizing means 112a, second standing wave stabilizing means 112b)
Since two microwave radiating portions (second opening 105b, third opening 105c) having an interval of approximately 1/3 of the guide wavelength are disposed between the two microwave radiating portions (second opening 105b, The third openings 105c) are arranged in phases that are neither nodes nor antinodes, but are rather close to nodes. This is because two microwave radiating portions (second opening 105b and third opening 105c) are replaced with two standing wave stabilizing means (first standing wave stabilizing means 112a and second standing wave stabilizing means 112b). As a result, the distance from the opening to the node is ((approximately half of the guide wavelength) − (approximately one third of the guide wavelength)) / 2≈1 of the guide wavelength. / 12, the distance from the opening to the belly is (approximately 1/3 of the wavelength in the tube) / 2≈ 1/6 of the wavelength in the tube, and the distance to the node is closer to half the distance than the distance to the belly . On the other hand, when calculated in the same manner, the first opening 105a and the fourth opening 105d are antinodes having substantially the same phase. This is because, for example, considering the position of the node by the first standing wave stabilizing means 112a as a reference, the distance from the second opening 105b to the reference node is 1/12 of the guide wavelength, as previously determined. Since the aperture 105b to the first aperture 105a is 1/3 of the guide wavelength, the reference node to the first aperture 105a is (approximately 1/3 of the guide wavelength)-(approximately 1/12 of the guide wavelength). ) ≈¼ of the in-tube wavelength, and this is a positional relationship that is exactly antinode when viewed from the reference node. Similarly, the fourth opening 105d becomes antinode, and in particular, the distance between the first opening 105a and the fourth opening 105d is approximately 1/3 × 3 of the in-tube wavelength, so that they are in phase. Become. As described above, the second opening 105b and the third opening 105c are both close to a node, the first opening 105a and the fourth opening 105d are both in the same phase and close to a belly, and the four openings 105a, 105b, and 105c. , 105d viewed from these centers, the phase relationship can be symmetric in the transmission direction, and as a result, the possibility of even radiation in the transmission direction can be increased.

  In addition, the microwave oven 101 of the present embodiment includes third standing wave stabilizing means 112c arranged at intervals of about ½ of the guide wavelength λg in the transmission direction from the second standing wave stabilizing means 112b. The first opening 105a is disposed between the terminal end 111 of the waveguide 104 and the first standing wave stabilizing means 112a, and the second standing wave stabilizing means 112b and the third standing wave stabilizing means are arranged. The fourth opening 105d is arranged between the 112c. As a result, the first opening 105a is more reliably arranged by disposing the first opening 105a between the terminal portion 111 of the waveguide 104, which is a node, and the first standing wave stabilizing means 112a. A fourth opening 105d is arranged between the second standing wave stabilizing means 112b and the third standing wave stabilizing means 112c arranged in the transmission direction at intervals of about ½ of the guide wavelength λg. By doing so, the fourth opening 105d can also be made more reliably, so that the effect of the sixth invention can be obtained with certainty.

  Further, in the microwave oven 101 of the present embodiment, the first opening 105a and the fourth opening 105d are arranged at substantially the antinode position of the standing wave in the pipe, and the second opening 105b and the third opening 105c are arranged in the tube. The arrangement is such that it does not become an antinode or node of the standing wave. As a result, the phases of the four openings 105a, 105b, 105c, and 105d can be specified to some extent, so that the effects of the sixth invention and the seventh invention can be obtained more reliably.

In the microwave oven 101 of the present embodiment, the plurality of openings 105a, 105b, 105c, and 105d are configured with openings that do not cover the center in the width direction of the waveguide 104 (tube axis 108), and at least one side of the tube axis It is set as the structure arrange | positioned in. Thus, in the width direction of the waveguide 104, in the most common TE10 mode waveguide 104, the electric field is maximum at the center (tube axis 108) in the width direction of the waveguide 104, and the electric field is at both ends. 0, and if the aperture crosses the tube axis 108, it will cross the maximum point of the electric field, radiating a large amount of microwaves from one aperture, leaving no portion that would otherwise be shared equally. Although there is a risk, in the present invention, since the openings 105a, 105b, 105c, and 105d do not cover the tube shaft 108, the amount of radiation from one opening is suppressed, and the plurality of openings 105a, 105b, 105c, and 105d are evenly balanced. Can radiate. Therefore, according to the configuration of the present invention, a plurality of openings 105a, 105b, 105c, and 105d can be radiated over a wide range from the openings 105a, 105b, 105c, and 105d toward the heating chamber. The object to be heated in the heating chamber 102 can be uniformly heated without using a driving unit.

  In addition, the microwave oven 101 of the present embodiment is configured such that the plurality of openings 105 a, 105 b, 105 c, and 105 d are arranged symmetrically on both sides of the tube axis 108. Thereby, more openings can be formed as a plurality of arrangements in the width direction. Regarding the width direction of the waveguide 104, in the most common TE10 mode waveguide, the electric field is maximum at the center (tube axis 108) in the width direction of the waveguide 104, and the electric field is zero at both ends. Since it has a symmetrical characteristic with respect to the axis 108, it is easy to radiate an equal amount of microwaves when the openings are arranged on both sides of the tube axis. Therefore, according to the configuration of the present invention, the openings 105 a, 105 b, 105 c, and 105 d that can radiate a large number of the same amount in the transmission direction and the width direction are provided. Therefore, the object to be heated in the heating chamber 102 can be uniformly heated without using a driving unit by arranging a plurality of openings 105a, 105b, 105c, and 105d.

  In the microwave oven 101 of this embodiment, the openings 105a, 105b, 105c, and 105d are configured to radiate circularly polarized waves. This generates an electric field that rotates 360 degrees in all directions unique to circularly polarized waves around the openings 105a, 105b, 105c, and 105d, and microwaves are radiated from the center in a vortex, making the circumferential direction uniform. Can be heated. Therefore, by radiating circularly polarized waves from the plurality of openings 105a, 105b, 105c, and 105d, microwaves can be radiated uniformly to the entire heating chamber 102, and only the plurality of openings 105a, 105b, 105c, and 105d are arranged. Thus, the object to be heated in the heating chamber 102 can be heated uniformly without using a driving unit.

  Furthermore, in the microwave oven 101 of the present embodiment, the openings 105a, 105b, 105c, and 105d that radiate circularly polarized waves have a substantially X-shaped configuration in which two long holes intersect. Thereby, circularly polarized waves can be reliably radiated from the waveguide 104 with a simple configuration.

  Conventional Patent Document 4 shows an example in which a plurality of rectangular slits are arranged at intervals of 1/4 of the wavelength as shown in FIG. According to FIG. 24, the opening 140 and the opening 141 adjacent to each other have a sine wave peak (antinode) and the sine wave 0 (node), respectively, and the opening 142 and the opening 143 adjacent to each other also have a sine wave peak. (Node) and 0 (node) of the sine wave, and even if the opening 141 and the opening 142 are viewed, it is the relationship between 0 (node) of the sine wave and the peak (antinode) of the sine wave, that is, adjacent openings. Are all related to the belly and nodes with different amplitudes. Therefore, interference between adjacent openings does not occur, but there is one point to be noted. It is the opening 140 and the opening 142, and the phases are opposite to each other. In other words, an opposite phase is generated between openings that are not adjacent but are slightly apart. In addition, as is clear from FIG. 24 in Patent Document 4, the openings 140, 141, 142, and 143 are formed of rectangular slits. If the circular polarization is radiated as in the present embodiment, the openings 140, 141, 142, and 143 are rectangular. If the slit is replaced with a substantially X-shaped configuration in which two long holes intersect, the end portions (X-shaped end portions) of the adjacent openings are in contact with each other, so that it cannot be actually configured. As described above, in the configuration based on the conventional patent document 4, interference may still occur and the circular polarization configuration may not be possible. As in the present invention, the frequency exceeds 1/4 of the guide wavelength. It is better to arrange them at intervals less than 2.

In this embodiment, when discussing the interval between the apertures or the standing wave stabilizing means, the expression of approximately half of the guide wavelength λg is used in the transmission direction of the waveguide 104. About 1/2 should be able to tolerate a certain range. Since the microwave in the waveguide has an in-tube wavelength λg, a deviation of about 1/8 of the in-tube wavelength λg is considered to be an allowable range without significant change. This is because when considering a sine wave, if the wavelength is shifted by ¼, the maximum or minimum changes to 0, and 0 changes to the maximum or minimum, which is considered to be a large change. However, if the wavelength is about ８, which corresponds to half of that, there is almost no change in the magnitude relationship, and the same tendency can be maintained. The guide wavelength λg is λg = λ0 / √ (1− (λ0 / (2 × a)) ^ 2), and the free space wavelength λ0 is 120 to 125 mm as described above, and the width of the waveguide of the present embodiment. When a = 100 mm, the guide wavelength λg is changed from 150 mm (2.5 GHz) to 160 mm (2.4 GHz), and 1/8 thereof is 18.75 to 20 mm. Therefore, approximately ½ of the guide wavelength λg in the transmission direction is just up to 1/2 of the guide wavelength λg and ½ of the guide wavelength λg with reference to ½ of the guide wavelength λg (≈75 to 80 mm). Allowable range. Specifically, the allowable range of deviation is 9.375 to 10 mm. Therefore, considering the allowable range of deviation, ½ of the guide wavelength λg is 65 mm to 90 mm.

  In addition, when discussing the distance between the openings in the transmission direction of the waveguide as in the present embodiment, unless otherwise specified, the transmission within the linear distance connecting the centers of the openings along the waveguide wall surface. Only the direction component is considered, and the center position is the center of gravity of the opening.

  In the present embodiment, the openings 105a and 105d at both ends are described as the antinode positions of the in-tube standing wave as shown in FIG. 2, but the present invention is not limited to this. However, since there is a tendency that more microwaves are radiated in the abdominal position, it is easier to emit microwaves with the openings 105a and 105d at the outer ends as compared to the center where the openings are dense. The effect is that the distribution in the entire cabinet tends to be uniform.

(Embodiment 2)
FIG. 10 is an explanatory diagram of the microwave heating apparatus according to Embodiment 2 of the present invention. FIG. 10A is a sectional view seen from above, and FIG. 10B is a sectional view seen from the front. Descriptions of configurations and functions equivalent to those of the above-described embodiment are omitted for those that are not the points of the invention.

  A waveguide 203 bent in an L shape that guides the microwave radiated from the magnetron 201 to the heating chamber 202, and a microwave radiating portion that radiates the microwave in the waveguide 203 into the heating chamber 202 is guided. It has openings 204, 205, 206, and 207 provided on the upper surface of the tube 203, and a mounting table 208 on which food (not shown) is placed. The space 209 has a central portion of the bottom surface 210 of the heating chamber 202 protruding downward in order to ensure a certain distance between the opening 204 and the mounting table 208, and the mounting table 208 is put on the upper portion of the space 209 with putty, packing, etc. The openings 204, 205, 206, and 207 are closed so as not to be exposed. At this time, the mounting table 208 is somewhat smaller than the bottom surface 210. The openings 204, 205, 206, and 207 do not extend from the center (tube axis) 211 in the width direction of the waveguide 203 but are arranged only on one side as viewed from the tube axis 211. Accordingly, the openings 204, 205, 206, and 207 are symmetrically arranged with respect to the bottom surface 210 of the heating chamber 202 and the front-rear direction of the mounting table 208. The openings 204, 205, 206, and 207 are configured so that the pitches are slightly different in the transmission direction, P1 and P3 are slightly larger than the guide wavelength λg / 3, and P2 is slightly less than the guide wavelength λg / 3. The effect of fine pitch adjustment will be described later in the description of another embodiment. Further, in order to stabilize the standing wave in the tube, the standing wave stabilizing means 213 is provided at a position separated from the terminal end portion 212 of the waveguide by about 3/2 of the wavelength in the tube, thereby fixing the node of the standing wave in the tube. The center of the openings 204, 205, 206, and 207 and the center of the waveguide end portion 212 and the standing wave stabilizing means 213 are the center line in the horizontal direction of the bottom surface 210 of the heating chamber 202 and the mounting table 208, respectively. 214 is connected so as to coincide with 214. Accordingly, the openings 204, 205, 206, and 207 are symmetrically arranged with respect to the bottom surface 210 of the heating chamber 202 and the horizontal direction of the mounting table 208.

The openings 204, 205, 206, and 207 are openings that can radiate circularly polarized waves with an X-shaped shape that intersects the long holes, and are arranged so as not to reach the tube axis 211 that is the center of the waveguide 203. Yes.

(Embodiment 3)
FIG. 11 is an explanatory diagram showing a microwave radiating unit of the microwave heating apparatus according to the third embodiment of the present invention, and FIG. 12 is a problem of the microwave radiating unit of the microwave heating apparatus according to the third embodiment of the present invention. FIG. 13 is a diagram for explaining the problem in placing the object to be heated when the third embodiment is not used for explaining the above, and FIG. 13 shows the object to be heated in the heating chamber of the microwave heating apparatus according to the third embodiment of the present invention. FIG.

  The operation and action will be described below. In the drawings, the same reference numerals are given to the portions showing the same operations as those in (Embodiment 1) to (Embodiment 2). The basic operation in (Embodiment 3) is the same as that in (Embodiment 1) to (Embodiment 2).

  In the present embodiment, as shown in FIG. 11C, the opening of the microwave radiating unit 301 is provided at a position that does not intersect the symmetry axis 601 in the horizontal direction of the heating chamber. As apparent from FIG. 11C, the waveguide wall current is most concentrated at the intersection of the symmetry axis 601 and the tube axis 901. On the other hand, in general, in a microwave heating apparatus, it is recommended that an object to be heated be placed at the center of a heating chamber in which the distribution of the microwave in the heating chamber tends to be relatively good. Here, as shown in FIG. 12C, when the microwave radiating portion 301 and the axis of symmetry 601 intersect, the center of the heating chamber in which the waveguide wall current is most concentrated is merely a concentration of heating. Instead, after the microwave transmitted through the waveguide 306 is radiated through the opening, it directly hits the object 302 to be heated at the closest distance from the microwave radiating unit 301. In this situation, when a small block-like object to be heated 302 such as a potato is placed, heating concentrates on the lower part of the object to be heated 302 and overheating is likely to occur.

  In order to avoid this situation, the arrangement of the microwave radiation section shown in FIG. 11C is effective. As shown in FIG. 11C, when the opening of the microwave radiating portion 301 is provided at a position that does not intersect the axis of symmetry 601, a potato-like material is placed in the center of the heating chamber where the waveguide wall current is most concentrated. Even when the small object to be heated 302 is placed, it is possible to avoid the situation where the microwave transmitted through the waveguide 306 is directly radiated to the object to be heated 302 at the closest distance from the microwave radiating unit 301. It is possible to prevent the situation where the heating is concentrated on the lower portion of the heated object 302 and the overheating occurs (FIG. 13).

  As described above, in the present embodiment, by providing the opening that constitutes the microwave radiating unit 301 at a position that does not intersect the symmetry axis 601, a small lump-like object to be heated placed in the center of the heating chamber. Direct radiation of microwaves to the lower part of the object 302 can be prevented.

  In order to stabilize the standing wave in the waveguide 306, the standing wave stabilizing means as described in the first and second embodiments may be disposed in the waveguide 306.

  In addition, the standing wave state in the waveguide 306 is specified by measuring the electric field distribution in the waveguide axis direction of the waveguide 306 in a state where the microwave radiation unit 301 is closed, and the obtained standing wave is obtained. If the symmetry axis 601 is set so as to match the wave position, the symmetry axis 601 can also be set experimentally.

In addition, in the microwave heating apparatus, the object to be heated 302 having a load amount (for example, a heating reference) in the center of the heating chamber (e.g. The standing wave state in the waveguide 306 is specified by measuring the electric field distribution in the waveguide 306 in a state where 1 L of water placed in a cylindrical container having a diameter of 19 cm is placed,
If the symmetry axis 601 is set so as to match the obtained standing wave position, the symmetry axis 601 can be set according to the heating reference load.

  If the recommended placement position of the object to be heated is not the center of the heating chamber due to the uneven structure of the heating chamber or the user's placement convenience, the symmetry axis 601 is set to a position off the center of the heating chamber accordingly. Also good.

(Embodiment 4)
FIG. 14 is a diagram illustrating the relationship between the microwave radiating unit of the microwave heating apparatus according to the fourth embodiment of the present invention, and FIG. 15 illustrates the current cutoff effective width of the microwave radiating unit according to the fourth embodiment of the present invention. It is a schematic diagram to do.

  The operation and action will be described below. In the drawings, the same reference numerals are given to the portions showing the same operations as those in (Embodiment 1) to (Embodiment 3). The basic operation in (Embodiment 4) is the same as that in (Embodiment 1) to (Embodiment 3).

  In the present embodiment, as shown in FIG. 14, the width of the opening of the microwave radiating portion 301 adjacent to the symmetry axis 601 is made larger than the width of the opening of the microwave radiating portion 301 not adjacent to the symmetry axis 601. Is also set larger.

  An electric field 303 is generated when the opening of the microwave radiating unit 301 blocks the tube wall current, and the microwave radiation direction perpendicular to the magnetic field under the opening (the waveguide wall current flows in a direction perpendicular to the magnetic field) Microwaves are radiated through the opening of the microwave radiation unit 301.

  Therefore, when the width of the opening is increased from FIG. 15A to FIG. 15B, the current cutoff effective width b1502 for blocking the tube wall current becomes narrower than the current cutoff effective width a1501. Therefore, the generation of an electric field generated based on blocking the tube wall current is suppressed, and the microwave radiation from the microwave radiation unit 301 is suppressed.

  By applying this principle to the width of the opening of the microwave radiating portion 301 adjacent to the symmetry axis 601 and setting the width larger than the width of the opening of the microwave radiating portion 301 not adjacent to the symmetry axis 601, the microwave It is possible to reduce the amount of microwaves radiated from the radiating unit 301 and to reduce the concentration of microwaves in the lower portion of the small object to be heated 302 such as a potato placed in the center of the heating chamber. Become.

  As described above, in the present embodiment, the width of the opening of the microwave radiating unit 301 adjacent to the symmetry axis 601 is set larger than the width of the opening of the microwave radiating unit 301 not adjacent to the symmetry axis 601. By doing so, the amount of microwaves radiated from the microwave radiating unit 301 is suppressed, and the microwaves are concentrated on the lower part of the small object to be heated 302 such as a potato placed in the center of the heating chamber. Can be relaxed.

  In order to stabilize the standing wave in the waveguide 306, the standing wave stabilizing means as described in the first and second embodiments may be disposed in the waveguide 306.

  In addition, the standing wave state in the waveguide 306 is specified by measuring the electric field distribution in the waveguide axis direction of the waveguide 306 in a state where the microwave radiation unit 301 is closed, and the obtained standing wave is obtained. If the symmetry axis 601 is set so as to match the wave position, the symmetry axis 601 can also be set experimentally.

In addition, in the microwave heating apparatus, the object to be heated 302 having a load amount (for example, a heating reference) in the center of the heating chamber (e.g. The standing wave state in the waveguide 306 was identified and obtained by measuring the electric field distribution in the waveguide 306 in a state where 1 L of water placed in a cylindrical container having a diameter of 19 cm was placed. If the symmetry axis 601 is set so as to match the standing wave position, it is possible to set the symmetry axis 601 according to the heating reference load.

  If the recommended placement position of the object to be heated is not the center of the heating chamber due to the uneven structure of the heating chamber or the user's placement convenience, the symmetry axis 601 is set to a position off the center of the heating chamber accordingly. Also good.

  In addition, in the experiment, the effect of expanding the opening width is increased by about 10%, so that a visible effect can be confirmed as an actual cooking result. Therefore, the width expansion should be 10% or more.

  In addition, by setting the width of the opening of the microwave radiating portion 301 adjacent to the symmetry axis 601 to be larger than the width of the opening of the microwave radiating portion 301 not adjacent to the symmetry axis 601 as described above, The method of suppressing the microwave concentration to the lower part of the object to be heated 302 leads to the enlargement of the opening area near the center of the heating chamber. Therefore, not only the heating concentration to a small load is suppressed, but also the load placed in the center of the heating chamber. Needless to say, there is an effect of increasing the efficiency of the heated object 302 having a large diameter (for example, 1 L of water in a cylindrical container having a diameter of 19 cm).

(Embodiment 5)
FIG. 16 is an explanatory diagram illustrating a microwave radiating unit of the microwave heating apparatus according to the fifth embodiment of the present invention. The operation and action will be described below. In the drawings, the same reference numerals are given to portions showing the same operations as those in (Embodiment 1) to (Embodiment 4). The basic operation in (Embodiment 5) is the same as that in (Embodiment 1) to (Embodiment 4).

  In the present embodiment, as shown in FIG. 16, when the microwave radiating portions 301 are evenly arranged (FIG. 16B), the arrangement interval of the microwave radiating portions 301 adjacent to the symmetry axis 601 is equal to the guide wavelength. When it is larger than a quarter (λg / 4) (FIGS. 16A and 16B), the interval between the microwave radiation portions 301 adjacent to the symmetry axis 601 is set to be narrower than the uniform arrangement interval ( FIG. 16 (c)). Thus, by narrowing the space | interval of the microwave radiation | emission part 301, the to-be-heated object 302 in case the small to-be-heated object 302 like a potato is mounted in the center of a heating chamber like FIG.16 (d). Heating concentration at the bottom can be reduced. The reason for relaxing the heating concentration will be described with reference to FIGS.

  FIG. 17A is the same view as FIG. 16C and shows a state in which the interval between the microwave radiating portions 301 adjacent to the symmetry axis 601 is set narrower than the uniform arrangement interval. The four adjacent microwave radiating portions 301 having the narrow interval can be decomposed into two microwave radiating portions arranged obliquely as shown in FIGS. 17 (b) and 17 (c). And the microwave radiation | emission part arrange | positioned diagonally becomes the arrangement | positioning similar to the opening arrangement | positioning in the directional coupler generally known. Here, the purpose is to explain that the heating concentration at the lower part of the object to be heated 302 can be alleviated. Therefore, in order to simplify the explanation, the principle of the directional coupler is as shown in FIG. A basic concept using a simple configuration in which the first waveguide 1801 and the second waveguide 1802 arranged vertically are connected by the first microwave radiation unit 1803 and the second microwave radiation unit 1804. Will be explained.

In FIG. 18, reference numeral 1801 denotes a first waveguide, 1802 denotes a second waveguide, 1803 denotes a first microwave radiating portion, 1804 denotes a second microwave radiating portion, and 1805 denotes a first waveguide. 1801 is an input unit, 1806 is an output unit of the first waveguide 1802, 1807 and 1808 are output units of the second waveguide, and 1809 is a microwave directly emitted from the first microwave radiation unit 1803. Radiation position, 1810 is the arrival position where the microwave radiated from the second microwave radiation portion 1804 travels toward the output portion 1807 of the second waveguide and reaches the microwave radiation portion 1803, 1811 is the first position The radiation position where the microwave is directly radiated from the second microwave radiation portion 1804, 1810 is the direction where the microwave radiated from the second microwave radiation portion 1804 is directed to the output portion 1808 of the second waveguide. Advanced Te and a reached position to reach the microwave radiation portion 1804.

  Here, FIG. 18A is a microwave waveform at the radiation position 1809, FIG. 18B is a microwave waveform at the arrival position 1810, and FIG. 18C is a combination of FIG. 18A and FIG. The amplitude is 0 in the waveform. This is because the distance (λg / g) from the first microwave radiating unit 1803 to the second microwave radiating unit 1804 until the microwave radiated from the second microwave radiating unit 1804 reaches the arrival position 1810. This is because the phase is shifted by half a wavelength (λg / 2) because of going back and forth in 4). This synthesized waveform represents the output immediately above the first microwave output unit.

  18D shows the microwave waveform at the radiation position 1811, FIG. 18E shows the microwave waveform at the arrival position 1812, and FIG. 18F shows the combined waveform of FIGS. 18D and 18E. Thus, the amplitude is twice that of FIGS. 18 (d) and 18 (e). This is because the moving distance until the microwave radiated from the first microwave radiating unit 1803 reaches the arrival position 1812 is the same and synthesized in the same phase. This combined waveform represents the output immediately above the second microwave output unit.

  18 (c), 18 (f), and 18 (g), the output from the microwave radiating unit is directional with 2 by arranging the microwave radiating unit with directional coupling. It turns out that it radiates | emits toward the outer side of the area | region pinched | interposed into two microwave radiation | emission parts.

  Next, the amplitude in a region sandwiched between the first microwave radiating unit 1803 and the second microwave radiating unit 1804 will be described with reference to FIG. In FIG. 19, reference numeral 1901 denotes a midpoint between the first microwave radiating unit 1803 and the second microwave radiating unit 1804. FIG. 19A shows a microwave waveform when the microwave radiated from the first microwave radiating portion 1803 travels toward the output portion 1808 of the second waveguide 1802 and reaches the midpoint 1901. 19 (b) shows the microwave waveform when the microwave radiated from the second microwave radiating portion 1804 travels toward the output portion 1807 of the second waveguide 1802 and reaches the middle point 1901. FIG. (C) is a composite waveform of FIG. 19 (a) and FIG. 19 (b). The amplitude of the synthesized wave is larger than the single amplitude in FIGS. 19A and 19B and smaller than twice the amplitude after directional coupling.

  Therefore, in the case of the opening arrangement for directional coupling, the radiation direction is expanded outside the region sandwiched between the first microwave radiation unit 1803 and the second microwave radiation unit 1804, and the sandwiched region Since the combined amplitude also becomes slightly weak, when a small massive object to be heated such as a potato is placed between the two microwave radiation portions, it becomes possible to alleviate the microwave concentration in the lower part.

In the actual microwave heating device, the tip radiated from the microwave radiating portion of the first waveguide 1801 is not the second waveguide 1802 but a heating chamber having a wide space. The wavelength of the microwave propagating through the waveguide is not the waveguide wavelength of the waveguide, but the oscillation wavelength of the microwave generating means, so that an ideal directional coupling state can be obtained even when a quarter wavelength is placed. Must not. Further, there may be a case where the interval between the microwave radiating units 301 cannot be reduced to a quarter wavelength due to the size limitation of the microwave radiating unit 301. However, even in such a case, the interval between the microwave radiating portions is set to be as narrow as possible so that the interval between the microwave radiating portions 301 adjacent to the symmetry axis 601 is as close as possible to the quarter wavelength than the uniform arrangement interval. As a result, when a small block-like object 302 such as a potato is placed in the center of the heating chamber as shown in FIG. Confirmed.

  As described above, in the present embodiment, when the microwave radiating portions 301 are evenly arranged, the interval between the microwave radiating portions 301 adjacent to the symmetry axis 601 is less than a quarter of the guide wavelength (λg / 4). In the case of being large, the direction of the microwave radiation from the microwave radiation unit 301 is changed by making the interval between the microwave radiation units 301 adjacent to the symmetry axis 601 narrower than the uniform arrangement interval, and the microwave radiation unit 301 is mounted in the center of the heating chamber. Microwave concentration in the lower portion of the small object to be heated 302 placed can be reduced.

  In order to stabilize the standing wave in the waveguide 306, the standing wave stabilizing means as described in the first and second embodiments may be disposed in the waveguide 306.

  In addition, the standing wave state in the waveguide 306 is specified by measuring the electric field distribution in the waveguide axis direction of the waveguide 306 in a state where the microwave radiation unit 301 is closed, and the obtained standing wave is obtained. If the symmetry axis 601 is set so as to match the wave position, the symmetry axis 601 can also be set experimentally.

  In addition, in the microwave heating apparatus, the object to be heated 302 having a load amount (for example, a heating reference) in the center of the heating chamber (e.g. The standing wave state in the waveguide 306 was identified and obtained by measuring the electric field distribution in the waveguide 306 in a state where 1 L of water placed in a cylindrical container having a diameter of 19 cm was placed. If the symmetry axis 601 is set so as to match the standing wave position, it is possible to set the symmetry axis 601 according to the heating reference load.

  If the recommended placement position of the object to be heated is not the center of the heating chamber due to the uneven structure of the heating chamber or the user's placement convenience, the symmetry axis 601 is set to a position off the center of the heating chamber accordingly. Also good.

  In this way, the microwave radiation direction from the microwave radiation part 301 is changed by making the interval between the microwave radiation parts 301 adjacent to the symmetry axis 601 smaller than the uniform arrangement interval, and the central part of the heating chamber The method of relaxing the microwave concentration in the lower portion of the small object to be heated 302 placed on the heating chamber can make the opening area near the center of the heating chamber the same, and thus not only suppress the heating concentration to a small load. Needless to say, there is also an effect of maintaining the efficiency of the heated object 302 placed in the center of the heating chamber (for example, 1 L of water placed in a cylindrical container having a diameter of 19 cm).

(Embodiment 6)
FIG. 20 is a schematic diagram illustrating the opening shape of the microwave heating apparatus according to the sixth embodiment of the present invention.

  In particular, an aperture configured by at least two slits will be described as the shape of the aperture that radiates circularly polarized waves as the microwave radiation portion. Like the openings 411 to 417, the slits are composed of two or more slits, and the long side of at least one of these slits is inclined with respect to the microwave transmission direction (arrow line 418). Just do it. Therefore, a shape that does not intersect such as the opening 415 and the opening 416 or a shape that includes three slits such as the opening 414 may be used.

  In addition, the following 3 points | pieces are mentioned as conditions of the optimal shape of the opening comprised by two slits.

  The first point is that the length of the long side of each slit is about ¼ or more of the guide wavelength λg in the waveguide 419.

  The second point is that the two slits are orthogonal to each other and the long side of each slit is inclined 45 ° with respect to the transmission direction 418.

  The third point is that the electric field distribution is not axisymmetric when a straight line parallel to the transmission direction 418 of the waveguide 419 and passing through the center of the opening is considered as an axis. For example, in the case of transmitting microwaves in the TE10 mode, the electric field is symmetrically distributed with the tube axis 421 serving as the center line in the width direction 420 of the waveguide 419 being the axis of symmetry, so the shape of the opening is It is the best condition to arrange them so as not to be symmetric with respect to the tube axis 421 (that is, the center of the opening does not come on the tube axis 421).

  In addition, FIG. 20 shows only those in which the long holes are orthogonal, but even when the X holes are crushed by forming the long holes to be inclined rather than orthogonal, they are deformed from a perfect circle. Although it becomes an ellipse, it can radiate circularly polarized waves.

  In addition, by adopting an L-shaped configuration such as the opening 413 and a T-shaped configuration such as the opening 415 in FIG. According to Patent Document 2, as shown in FIG. 22B, it is indicated that the two slits may be inclined as long as they are about 30 degrees, even if they are not orthogonal.

  Moreover, although it is a long hole, it is not limited to a rectangle. It is possible to generate circularly polarized waves by adding an R to the corner of the opening or making it elliptical. As a basic idea of circularly polarized aperture, it is presumed that two long and narrow shapes that are longer in one direction and shorter in the perpendicular direction may be combined.

  As described above, since the microwave heating apparatus of the present invention can uniformly irradiate the object to be heated with microwaves, the microwave heating apparatus can be effectively used for a microwave heating apparatus that performs heating processing or sterilization of food. Can do.

101 Microwave oven (microwave heating device)
102, 128, 202 Heating chamber 103, 201 Magnetron (microwave generating means)
104, 130, 203, 306, 419 Waveguide 105a First aperture (microwave radiation part)
105b Second opening (microwave radiation part)
105c 3rd opening (microwave radiation part)
105d 4th opening (microwave radiation part)
108, 211, 421, 901 Center in the width direction (tube axis)
111, 131, 212 Termination part 112a First standing wave stabilization means 112b Second standing wave stabilization means 112c Third standing wave stabilization means 129, 139a, 139b, 204, 205, 206, 207, 301, 411, 412, 413, 414, 415, 416, 417 opening (microwave radiation part)
134, 135, 136, 213 Standing wave stabilizing means 302 Object to be heated

Claims (9)

A heating chamber for storing an object to be heated;
Microwave generation means for generating microwaves;
A waveguide for transmitting microwaves;
A plurality of microwave radiating portions for radiating microwaves from the waveguide into the heating chamber, a standing wave is generated in the waveguide, and the plurality of microwave radiating portions are arranged in the waveguide. In the transmission direction, the arrangement is made at intervals exceeding 1/4 of the guide wavelength and less than 1/2, and the standing waves facing the adjacent microwave radiation portions are configured not to have an antiphase relationship ,
Standing wave stabilization means for stabilizing the standing wave position in the waveguide;
A plurality of the standing wave stabilizing means are arranged at intervals of about ½ of the guide wavelength in the transmission direction,
At least two standing wave stabilizing means (first standing wave stabilizing means and second standing wave stabilizing counted from the end side of the waveguide) arranged in the transmission direction at intervals of about ½ of the guide wavelength Means) and at least four microwave radiating portions (first microwave radiating portion and second microwave counting from the terminal end side of the waveguide) arranged in the transmission direction at an interval of about ３ of the guide wavelength. Radiation portion, third microwave radiation portion, and fourth microwave radiation portion), and the second microwave radiation portion between the first standing wave stabilization means and the second standing wave stabilization means. And a microwave heating apparatus having a configuration in which a third microwave radiating portion is disposed . The microwave heating device according to claim 1, wherein the plurality of microwave radiating units are arranged in the transmission direction at an interval of about ３ of the guide wavelength. The standing wave stabilizing means is configured to generate a standing wave node in the waveguide, and is configured to be disposed at a distance that is an integral multiple of approximately ½ of the guide wavelength in the transmission direction to the end of the waveguide. The microwave heating device according to claim 1 or 2 . It has third standing wave stabilizing means arranged in the transmission direction from the second standing wave stabilizing means at an interval of about 1/2 of the guide wavelength, and ends the waveguide and the first standing wave stabilization. A first microwave radiating portion is disposed between the second standing wave stabilizing means and a fourth microwave radiating portion is disposed between the second standing wave stabilizing means and the third standing wave stabilizing means. Item 4. The microwave heating apparatus according to any one of Items 1 to 3 . The first microwave radiating part and the fourth microwave radiating part are arranged at a position substantially in the antinode of the standing wave in the tube,
The microwave according to any one of claims 1 to 4, wherein the second microwave radiating portion and the third microwave radiating portion are arranged at positions where neither the antinode nor the node of the standing wave in the tube is located. Heating device. A plurality of microwave radiation unit is constituted by an opening which does not overlap the width direction of the center of the waveguide (tube axis), according to any one of claims 1 was configured to place at least one side of the tube axis 5 Microwave heating device. The microwave heating device according to claim 6, wherein the plurality of microwave radiating portions are arranged symmetrically on both sides of the tube axis. The microwave heating device according to any one of claims 1 to 7 , wherein the microwave radiating unit radiates circularly polarized waves. The microwave heating apparatus according to claim 8 , wherein the microwave radiating portion that radiates circularly polarized waves has a substantially X-shaped configuration in which two long holes intersect.