Microwave heating device

Abstract

The present invention addresses the problem of more uniformly heating an object to be heated by using microwaves. A microwave heating device (100) comprises: an oscillator (1); a first resonator (2); and a second resonator (3). The oscillator (1) generates microwaves for heating an object (TA1) to be heated and changes the frequency of the microwaves within a predetermined frequency band. The microwaves are supplied to an internal space (SP1) of the first resonator (2). The second resonator (3) changes the phase of the microwaves incident from the internal space (SP1) by 90° or more within the predetermined frequency band and reflects the microwaves to the internal space (SP1).

Description

Microwave heating device

[0001] The present disclosure generally relates to a microwave heating device. More specifically, the present disclosure relates to a microwave heating device including an oscillator that generates microwaves.

[0002] Patent Document 1 discloses a microwave drying device including a conveying means, a drying furnace, and a microwave oscillator. The conveying means conveys an object to be heated along a predetermined path. The drying furnace is disposed so as to intersect the conveying means on the predetermined path and heats the object to be heated by microwaves. The microwave oscillator is disposed on one end side of the drying furnace and irradiates microwaves from one end side to the other end side of the drying furnace.

[0003] The microwave drying device (microwave heating device) described in Patent Document 1 includes a movable short-circuit plate that reciprocates along the irradiation direction of microwaves when irradiating the object to be heated with microwaves in order to uniformly heat the object to be heated. However, since microwaves are reflected at the fixed end by the movable short-circuit plate, there is a problem that it is difficult to uniformly heat the object to be heated in the vicinity where the movable short-circuit plate is disposed in the drying furnace.

[0004] Japanese Patent Application Laid-Open No. 2021-125447

[0005] An object of the present disclosure is to provide a microwave heating device capable of more uniformly heating an object to be heated using microwaves.

[0006] A microwave heating device according to an aspect of the present disclosure includes an oscillator, a first resonator, and a second resonator. The oscillator generates microwaves for heating an object to be heated and changes the frequency of the microwaves within a predetermined frequency band. The first resonator has an internal space, a first wall portion, and a second wall portion. The microwaves are supplied to the internal space. The first wall portion and the second wall portion form a standing wave in a predetermined direction by reflecting the microwaves. The second resonator is disposed on the second wall portion. The second resonator changes the phase of the microwaves incident from the internal space by 90° or more within the predetermined frequency band and reflects the microwaves to the internal space.

[0007] Figure 1 is a schematic cross-sectional view of a microwave heating device according to Embodiment 1. Figure 2 is a graph showing multiple standing waves formed in the internal space of the first resonator in a comparative example microwave heating device. Figure 3 is a graph showing multiple standing waves formed in the internal space of the first resonator in a microwave heating device according to Embodiment 1. Figure 4 is a graph showing an index of the amount of heating by microwaves in the internal space of the first resonator in the same microwave heating device. Figure 5 is a graph showing the reflection phase characteristics of the second resonator of the same microwave heating device. Figure 6 is a schematic configuration diagram of the oscillator provided in the same microwave heating device. Figure 7 is a schematic cross-sectional view of a microwave heating device according to a first modified example of Embodiment 1. Figure 8 is a schematic cross-sectional view of a microwave heating device according to a second modified example of Embodiment 1. Figure 9 is a schematic cross-sectional view of a microwave heating device according to a third modified example of Embodiment 1. Figure 10 is a schematic configuration diagram of an oscillator provided in the microwave heating device of Embodiment 1, different from the configuration shown in Figure 6. Figure 11 is a schematic diagram of the oscillator in the microwave heating device of Embodiment 1, which differs from the configuration shown in Figures 6 and 10. Figure 12 is a schematic cross-sectional view of the microwave heating device according to Embodiment 2. Figure 13 is a schematic cross-sectional view of the microwave heating device according to a first modification of Embodiment 2. Figure 14 is a schematic cross-sectional view of the microwave heating device according to a second modification of Embodiment 2. Figure 15 is a schematic cross-sectional view of the microwave heating device according to a third modification of Embodiment 2. Figure 16 is a schematic plan view of the microwave heating device according to Embodiment 3. Figure 17 is a schematic cross-sectional view of the same microwave heating device along the line A1-A1 in Figure 16. Figure 18 is a schematic plan view of the microwave heating device according to a first modification of Embodiment 3. Figure 19 is a schematic plan view of the microwave heating device according to a second modification of Embodiment 3. Figure 20 is a schematic plan view of the microwave heating device according to a third modification of Embodiment 3. Figure 21 is a schematic cross-sectional view of the microwave heating device of Embodiment 3 when the resonator has a choke structure. Figure 22 is a plan view of the microwave heating device according to Embodiment 4. Figure 23 is a schematic plan view of a microwave heating apparatus according to a first modification of Embodiment 4. Figure 24 is a schematic plan view of a microwave heating apparatus according to a second modification of Embodiment 4.Figure 25 is a schematic plan view of a microwave heating apparatus according to a third modification of Embodiment 4. Figure 26 is a schematic plan view of a microwave heating apparatus according to Embodiment 5. Figure 27 is a perspective view of the second resonator in the same microwave heating apparatus.

[0008] The embodiments and modifications described below are merely examples of the present disclosure. This disclosure is not limited to these embodiments and modifications, and various modifications are possible depending on the design, etc., as long as they do not depart from the technical idea of ​​the present disclosure. The figures described in the embodiments and modifications below are schematic diagrams, and the ratios of the size and thickness of each component in the figures do not necessarily reflect the actual dimensional ratios.

[0009] (1) Embodiment 1 (1-1) Overview Below, an overview of the microwave heating apparatus 100 according to Embodiment 1 will be described with reference to Figures 1 to 4.

[0010] The microwave heating apparatus 100 according to Embodiment 1 comprises an oscillator 1, a first resonator 2, and a second resonator 3. The oscillator 1 generates microwaves to heat the object to be heated TA1 and changes the frequency of the microwaves within a predetermined frequency band. The first resonator 2 has an internal space SP1, a first wall portion 211, and a second wall portion 212. Microwaves are supplied to the internal space SP1 from the oscillator 1. The first wall portion 211 and the second wall portion 212 reflect the microwaves, thereby forming (generating) standing waves in a predetermined direction D1 (or waveguide direction). The second resonator 3 is positioned in the second wall portion 212. The second resonator 3 changes the phase of the microwaves incident from the internal space SP1 by 90° or more within a predetermined frequency band and reflects them back to the internal space SP1.

[0011] In the comparative example microwave heating apparatus, which has only a first resonator and no second resonator, multiple standing waves (see graphs EG21 to EG25 in Figure 2) are formed between the second wall and the first wall. Graphs EG21 to EG25 in Figure 2 show the relationship between the position in a predetermined direction D1 and the electric field strength (or the amplitude corresponding to the electric field strength). The horizontal axis of graphs EG21 to EG25 shows the position in the predetermined direction D1, and the vertical axis shows the amplitude. In the multiple standing waves, the positions of the antinodes and nodes differ depending on the frequency of the microwaves generated by the oscillator. The above multiple standing waves are fixed to the same phase in each of the first wall located at position P0 in the predetermined direction D1 and the second wall located at position P2 in the predetermined direction D1.

[0012] Graph EG3 in Figure 2 is a schematic graph that superimposes the absolute values ​​of the amplitudes of multiple standing waves. In other words, graph EG3 is a schematic graph that superimposes the absolute values ​​of the amplitudes of graphs EG21 to EG25. The horizontal axis of graph EG3 indicates the position in a predetermined direction D1, and the vertical axis of graph EG3 indicates the absolute value of the amplitude. Graph EG4 is a graph that shows the values ​​obtained by integrating graph EG3 at predetermined widths along the predetermined direction D1, along the predetermined direction D1. The horizontal axis of graph EG4 indicates the position in the predetermined direction D1, and the vertical axis of graph EG4 indicates an index of the amount of heating by microwaves. The amount of heating by microwaves is proportional to graph EG4. As shown in graph EG4, in the vicinity of the first wall and the second wall, there are peaks and dips in the amount of heating by microwaves, and the variation in the amount of heating by microwaves is large. On the other hand, as shown in graph EG4, the variation in the amount of heating by microwaves is small in the central space of the internal space SP1 in a predetermined direction D1. In the comparative example microwave heating device, the amount of heating by microwaves is not uniform from the first wall to the second wall. Therefore, the comparative example microwave heating device has the problem that it is not possible to uniformly heat the object to be heated using microwaves.

[0013] On the other hand, in the internal space SP1 of the first resonator 2 in the microwave heating device 100 of Embodiment 1, multiple standing waves with different antinode and node positions are formed between the first wall portion 211 and the second wall portion 212, depending on the frequency of the microwaves generated by the oscillator 1, as shown in graphs G21 to G25 of Figure 3. Graphs G21 to G25 of Figure 3 are graphs showing the relationship between the position in a predetermined direction D1 and the electric field strength (or amplitude corresponding to the electric field strength). The horizontal axis of graphs G21 to G25 shows the position in the predetermined direction D1, and the vertical axis of graphs G21 to G25 shows the amplitude. As shown in Figure 3, the above-mentioned multiple standing waves are fixed at different phases in each of the first wall portion 211 (or position P0) and the second wall portion 212 (or position P2).

[0014] Graph G3 in Figure 3 is a schematic graph that displays the absolute values ​​of the amplitudes of multiple standing waves superimposed. The horizontal axis of graph G3 indicates the position in a predetermined direction D1, and the vertical axis of graph G3 indicates the absolute value of the amplitude. Note that displaying the absolute values ​​of the amplitudes for all standing waves shown in graphs G21 to G25 would be cumbersome, so in graph G3, as an example, the absolute values ​​of the amplitudes of the standing waves shown in graphs G21 to G25 are superimposed and displayed in a simplified manner. Graph G4 is a graph that shows the values ​​obtained by integrating graph G3 at predetermined widths along the predetermined direction D1, along the predetermined direction D1. The horizontal axis of graph G4 indicates the position in the predetermined direction D1, and the vertical axis of graph G4 indicates an index of the amount of heating by microwaves. The amount of heating by microwaves in the internal space SP1 is proportional to graph G4. As shown in Graph G4, the occurrence of peaks and dips in the amount of heating by microwaves is suppressed in the vicinity of the first wall portion 211 and the second wall portion 212, respectively, and the variation in the amount of heating by microwaves is reduced. In the microwave heating device 100 of Embodiment 1, as shown in Figure 4, the variation in the amount of heating by microwaves is more uniform from the first wall portion 211 (or position P0) to the second wall portion 212 (or position P2) compared to the microwave heating device of the comparative example. As a result, the microwave heating device 100 of Embodiment 1 has the advantage of being able to heat the object to be heated TA1 more uniformly using microwaves.

[0015] (1-2) Detailed Configuration (1-2-1) Overall Configuration Below, the detailed configuration of the microwave heating apparatus 100 of Embodiment 1 will be described with reference to Figures 1 to 6.

[0016] In the following example, we will define three mutually orthogonal axes: the X, Y, and Z axes. The axis parallel to the thickness direction of the object to be heated TA1 will be defined as the "Y axis." Furthermore, one of the two directions along the Y axis will be defined as the forward direction, and the other as the backward direction. Note that the X, Y, and Z axes are all virtual axes, and the arrows indicating "X," "Y," and "Z" in the drawings are merely illustrative and do not represent actual axes. Also, these directions are not intended to limit the direction in which the microwave heating device 100 can be used.

[0017] The microwave heating device 100 is used to microwave-heat an object to be heated TA1 (see Figure 1) containing a dielectric material. For example, the microwave heating device 100 is used to microwave-heat an object to be heated TA1 that is impregnated with a solvent, or to fire a green sheet that will be used as a raw material for a ceramic device.

[0018] As shown in Figure 1, the microwave heating device 100 includes an oscillator 1, a first resonator 2, a second resonator 3, a third resonator 4, and a control device 9.

[0019] (1-2-2) Oscillator The oscillator 1 generates microwaves to heat the object to be heated TA1 and changes the frequency of the microwaves within a predetermined frequency band. The oscillator 1 performs a frequency sweep within the predetermined frequency band in accordance with the control by the control device 9.

[0020] In Embodiment 1, the oscillator 1 is positioned on the upper wall portion 213 of the first resonator 2 so as to be aligned with the first resonator 2 in a second direction D2 that intersects (in this case, orthogonal to) the first direction D1, which is a predetermined direction D1.

[0021] As shown in Figure 6, the oscillator 1 of Embodiment 1 includes an oscillation unit 11, an isolator 12, and an output unit 13.

[0022] The oscillator 11 oscillates (generates) microwaves to be supplied to the first internal space SP1 of the first resonator 2. The oscillator 11 is, for example, a microwave generator such as a magnetron. Alternatively, the oscillator 11 may be a microwave generator using semiconductor elements.

[0023] The isolator 12 suppresses the effects of reflected waves generated in the first internal space SP1 of the first resonator 2. More specifically, the isolator 12 allows the microwaves oscillated by the oscillator 11 to propagate directly into the first resonator 2, while absorbing the reflected waves so that they do not return to the oscillator 11. As a result, the isolator 12 protects the oscillator 11. This allows the oscillator 1 to stably supply microwaves to the first internal space SP1 of the first resonator 2.

[0024] The isolator 12, for example, includes a main body 121 and a termination resistor 122. The first terminal of the main body 121 is connected to the oscillator 11, and the second terminal of the main body 121 is connected to the output 13. The third terminal of the main body 121 is connected to the termination resistor 122, and the reflected wave is absorbed by the termination resistor 122.

[0025] The output unit 13 supplies (outputs) microwaves propagated through the isolator 12 to the first internal space SP1 of the first resonator 2. In the embodiment 1, the output unit 13 is connected to the opening 22 of the first wall portion 211 of the first resonator 2, which will be described later.

[0026] (1-2-3) First Resonator The first resonator 2 guides (transmits) the microwaves supplied from the oscillator 1. As shown in Figure 1, the first resonator 2 is rectangular in shape. However, the first resonator 2 may be hollow cylindrical, hollow spherical, or other hollow polygonal prism, and its shape is not limited. The first resonator 2 is made of a conductive material, such as copper, iron, or aluminum.

[0027] The hollow first resonator 2 has a first internal space (cavity) SP1. Microwaves are supplied to the first internal space SP1 from the oscillator 1. The first internal space SP1 is a rectangular parallelepiped space. The first internal space SP1 corresponds to the internal space as referred to in this disclosure. Furthermore, the first internal space SP1 may be cylindrical, spherical, or other polygonal prism-shaped space, and the shape of the first internal space SP1 is not limited.

[0028] The first resonator 2 has two wall portions 21 that resonate microwaves in a predetermined direction D1 by reflecting microwaves supplied to the first internal space SP1, thereby forming (generating) standing waves. The microwaves supplied to the first internal space SP1 are reflected by the inner surfaces of the two wall portions 21. The two wall portions 21 are the first wall portion 211 and the second wall portion 212. The predetermined direction D1 is the X-axis direction.

[0029] Microwaves supplied to the first internal space SP1 are reflected by the first wall 211 and the second wall 212, causing them to resonate in a predetermined direction D1 and form a standing wave. For example, in the first internal space SP1, if the distance from the first wall 211 to the second wall 212 in the predetermined direction D1 is an integer multiple of half the wavelength of the microwaves supplied from the oscillator 1, the microwaves resonate in the predetermined direction D1 and form a standing wave.

[0030] In the first resonator 2 of Embodiment 1, an opening 22 is provided in the upper wall portion 213. The first internal space SP1 is connected to the oscillator 1 via the opening 22 in the upper wall portion 213. In short, microwaves generated by the oscillator 1 are supplied to the first internal space SP1 through the opening 22 in the upper wall portion 213. The opening 22 is, for example, rectangular. However, the opening 22 may also be circular, and its shape is not limited.

[0031] In the first resonator 2 of Embodiment 1, an opening 23 is provided in the second wall portion 212. The opening 23 of the second wall portion 212 is connected to an opening 31 of the second resonator 3, which will be described later. The first internal space SP1 is in communication with the second internal space SP2 of the second resonator 3 via the opening 23 of the second wall portion 212 and the opening 31 of the second resonator 3. The opening 23 is, for example, rectangular. However, the opening 23 may also be circular, and its shape is not limited.

[0032] Similarly, in the first resonator 2 of Embodiment 1, an opening 24 is provided in the first wall portion 211. The opening 24 of the first wall portion 211 is connected to an opening 41 of the third resonator 4, which will be described later. The first internal space SP1 is in communication with the third internal space SP3 of the third resonator 4 via the opening 24 of the first wall portion 211 and the opening 41 of the third resonator 4. The opening 24 is, for example, rectangular. However, the opening 24 may also be circular, and its shape is not limited.

[0033] (1-2-4) Second resonator The second resonator 3 guides (transmits) microwaves incident from the first internal space SP1 of the first resonator 2. As shown in Figure 1, the second resonator 3 is rectangular in shape. The second resonator 3 may be hollow cylindrical, hollow spherical, or other hollow polygonal prism shapes, and its shape is not limited. The second resonator 3 is made of a conductive material, such as copper, iron, or aluminum. The second resonator 3 is positioned on the outer surface of the second wall portion 212 of the first resonator 2.

[0034] The second resonator 3 has a second internal space (cavity) SP2. Microwaves are incident on the second internal space SP2 from the first internal space SP1 of the first resonator 2. The second internal space SP2 is a rectangular parallelepiped space. However, the second internal space SP2 may also be cylindrical, spherical, or other polygonal prism-shaped space, and the shape of the second internal space SP2 is not limited.

[0035] In Embodiment 1, the second resonator 3 is formed integrally with the first resonator 2. For example, the X-axis dimension of the second resonator 3 is smaller than the X-axis dimension of the first resonator 2, and the Y-axis and Z-axis dimensions of the second resonator 3 are the same as the Y-axis and Z-axis dimensions of the first resonator 2. In this disclosure, "same" is not limited to strictly identical, and errors are permissible. The permissible range of errors is, for example, about 5%.

[0036] The second resonator 3 has two wall portions 32 that resonate in a predetermined direction D1 and form (generate) a standing wave by reflecting microwaves that are incident from the first internal space SP1 and supplied to the second internal space SP2. The microwaves are reflected from the inner surfaces of the two wall portions 32. The two wall portions 32 are the first wall portion 321 and the second wall portion 322. The first wall portion 321 is formed integrally with the second wall portion 212 of the first resonator 2.

[0037] In the second resonator 3 of Embodiment 1, an opening 31 is provided in the first wall portion 321. The opening 31 of the first wall portion 321 is connected to the opening 23 of the second wall portion 212 of the first resonator 2. The second internal space SP2 is in communication with the first internal space SP1 of the first resonator 2 via the opening 31 of the first wall portion 321 and the opening 23 of the second wall portion 212 of the first resonator 2. The opening 31 is, for example, rectangular. It is desirable that the opening 31 has the same shape as the opening 23 of the second wall portion 212 of the first resonator 2. However, the opening 31 may also be circular, and its shape is not limited.

[0038] Microwaves that enter the second internal space SP2 from the first internal space SP1 through the openings 23 and 31 are guided (transmitted) within the second internal space SP2 along a predetermined direction D1 toward the second wall 322 and reflected by the inner surface of the second wall 322. The microwaves reflected by the inner surface of the second wall 322 are guided within the second internal space SP2 along a predetermined direction D1 toward the first wall 321. At least a portion of the microwaves guided toward the first wall 321 then enters the first internal space SP1 through the openings 31 and 23. In other words, at least a portion of the microwaves guided toward the first wall 321 passes through the openings 31 and 23 and is reflected by the first internal space SP1.

[0039] When microwaves incident from the first internal space SP1 are guided through the second internal space SP2 along a predetermined direction D1, their phase changes according to the frequency of the microwaves. The phase of the microwaves reflected from the first internal space SP1 changes from the phase of the microwaves incident from the first internal space SP1, according to the frequency of the microwaves incident from the first internal space SP1, as shown in graph G1 of Figure 5. The horizontal axis of Figure 5 represents the frequency of the microwaves incident from the first internal space SP1. On the other hand, the vertical axis of Figure 5 represents the phase of the microwaves reflected from the first internal space SP1, with the phase of the microwaves incident from the first internal space SP1 as the reference. In this disclosure, the phase of the microwaves incident from the first internal space SP1 is set to 0°.

[0040] As described above, since the oscillator 1 changes the microwave frequency within a predetermined frequency band, the phase of the microwave reflected by the second resonator 3 to the first internal space SP1 changes by 90° or more over the predetermined frequency band. In other words, the second resonator 3 changes the phase of the microwave incident from the first internal space SP1 by 90° or more within the predetermined frequency band in which the oscillator 1 changes the microwave frequency, and reflects it back to the first internal space SP1. In this disclosure, "the oscillator 1 changes the phase of the microwave by 90° or more within a predetermined frequency band in which it changes the microwave frequency and reflects it back to the first internal space SP1" means that the phase of the microwave incident from the first internal space SP1 changes by 90° or more over the predetermined frequency band, and is reflected back to the first internal space SP1. In short, the oscillator 1 changes the frequency of the microwaves within a predetermined frequency band so that the second resonator 3 reflects the microwaves incident from the first internal space SP1 back into the first internal space SP1 with a phase change of 90° or more over the predetermined frequency band.

[0041] The dimensions of the second resonator 3 in the X-axis direction should preferably be designed to an optimal value using electromagnetic field analysis software or the like, such that the phase of the microwaves reflected by the second resonator 3 to the first internal space SP1 changes by 90° or more over the predetermined frequency band. As an example, the dimensions of the second resonator 3 in the X-axis direction should be designed to be at least half the wavelength of the microwave when the microwave frequency is the center frequency of the predetermined frequency band.

[0042] (1-2-5) Third Resonator The third resonator 4 guides (transmits) microwaves incident from the first internal space SP1 of the first resonator 2. As shown in Figure 1, the third resonator 4 is rectangular in shape. The third resonator 4 may be hollow cylindrical, hollow spherical, or other hollow polygonal prism, and its shape is not limited. The third resonator 4 is made of a conductive material, such as copper, iron, or aluminum. The third resonator 4 is positioned on the outer surface of the first wall portion 211 of the first resonator 2.

[0043] The third resonator 4 has a third internal space (cavity) SP3. Microwaves are incident on the third internal space SP3 from the first internal space SP1 of the first resonator 2. The third internal space SP3 is a rectangular parallelepiped space. Also, the third internal space SP3 may be a cylindrical, spherical, or other polygonal columnar space, and the shape of the third internal space SP3 is not limited.

[0044] In Embodiment 1, the third resonator 4 is formed integrally with the first resonator 2. As an example, the dimension of the third resonator 4 in the X-axis direction is smaller than the dimension of the first resonator 2 in the X-axis direction, and the dimensions of the third resonator 4 in the Y-axis and Z-axis directions are the same as the dimensions of the first resonator 2 in the Y-axis and Z-axis directions.

[0045] The third resonator 4 has two wall portions 42 that reflect the microwaves incident from the first internal space SP1 and supplied to the third internal space SP3, thereby resonating the microwaves in a predetermined direction D1 and forming (generating) a standing wave. The above-mentioned microwaves are reflected by the inner surfaces of the two wall portions 42. The two wall portions 42 are the first wall portion 421 and the second wall portion 422. The first wall portion 421 is formed integrally with the second wall portion 212 of the first resonator 2.

[0046] In the third resonator 4 of Embodiment 1, an opening 41 is provided in the first wall portion 421. The opening 41 in the first wall portion 421 is connected to the opening 23 of the first resonator 2. The third internal space SP3 communicates with the first internal space SP1 of the first resonator 2 through the opening 41 in the first wall portion 421 and the opening 23 in the second wall portion 212 of the first resonator 2. The opening 41 is, as an example, a rectangular opening. It is desirable that the opening 41 has the same shape as the opening 23 in the second wall portion 212 of the first resonator 2. Note that the opening 41 may be a circular opening, and the shape is not limited.

[0047] By changing the frequency of the microwave within a predetermined frequency band by the oscillator 1, the phase of the microwave reflected by the third resonator 4 into the first internal space SP1 changes by 90° or more over the above-described predetermined frequency band. That is, similar to the second resonator 3, the third resonator 4 changes the phase of the microwave incident from the first internal space SP1 by 90° or more within the predetermined frequency band in which the oscillator 1 changes the frequency of the microwave, and reflects it into the first internal space SP1.

[0048] The dimension of the third resonator 4 in the X-axis direction is preferably designed to an optimum value using electromagnetic field analysis software or the like so that the phase of the microwave reflected by the third resonator 4 into the first internal space SP1 changes by 90° or more over the above-described predetermined frequency band. As an example, the dimension of the third resonator 4 in the X-axis direction is designed to be 1 / 2 or more of the wavelength of the microwave when the frequency of the microwave is the center frequency of the predetermined frequency band.

[0049] (1-2-6) Control Device The control device 9 controls the oscillator 1. More specifically, the control device 9 controls the oscillator 1 to perform frequency sweeping within a predetermined frequency band, thereby moving the positions of the antinodes and nodes of the standing wave formed in the first internal space SP1. Note that "moving the positions of the antinodes and nodes of the standing wave" as referred to in the present disclosure means changing the positions where the antinodes and nodes of the standing wave are formed by changing the interval (wavelength) of the standing wave formed in the first internal space SP1 of the first resonator 2 in the wave guiding direction (or a predetermined direction D1).

[0050] The control device 9 preferably includes a computer system. In the computer system, some or all of the functions of the control device 9 are realized by a processor such as a CPU or MPU reading and executing a program stored in memory. The computer system mainly includes a processor that operates according to the program as its hardware configuration. The type of processor is not limited as long as it can realize its functions by executing a program. The processor consists of one or more electronic circuits, including a semiconductor integrated circuit (IC) or an LSI (Large Scale Integration). Here, we refer to them as ICs and LSIs, but the name changes depending on the degree of integration, and they may also be called system LSIs, VLSIs (Very Large Scale Integrations), or ULSIs (Ultra Large Scale Integrations). Field-programmable gate arrays (FPGAs) that are programmed after the manufacture of the LSI, or reconfigurable logic devices that allow for the reconfiguration of junction relationships within the LSI or the setup of circuit compartments within the LSI, can also be used for the same purpose. Multiple electronic circuits may be integrated on a single chip or provided on multiple chips. Multiple chips may be integrated into a single device, or they may be provided in multiple devices.

[0051] (1-3) Advantages The microwave heating device 100 of Embodiment 1 includes a second resonator 3 that changes the phase of microwaves incident from the first internal space SP1 by 90° or more within a predetermined frequency band and reflects them back to the first internal space SP1. As a result, in the first internal space SP1 of the first resonator 2 in the microwave heating device 100 of Embodiment 1, a plurality of standing waves with different antinode and node positions are formed between the first wall portion 211 (position P0 shown in Figures 1 and 3) and the second wall portion 212 (position P2 shown in Figures 1 and 3), depending on the frequency of microwaves generated by the oscillator 1, as shown in graphs G21 to G25 of Figure 3. As shown in Figure 3, the plurality of standing waves are fixed at different phases in each of the first wall portion 211 and the second wall portion 212.

[0052] The amount of heating by microwaves in the first internal space SP1 is proportional to the heating amount index in graph G3. As shown in graph G4, the occurrence of peaks and dips in the amount of heating by microwaves is suppressed in the vicinity of the first wall 211 and the second wall 212, and the variation in the amount of heating by microwaves is reduced. In the microwave heating device 100 of Embodiment 1, as shown in Figure 4, the variation in the amount of heating by microwaves is more uniform across the first wall 211 (or position P0) and the second wall 212 (or position P2) compared to the microwave heating device of the comparative example. As a result, the microwave heating device 100 of Embodiment 1 has the advantage of being able to heat the object to be heated TA1 more uniformly using microwaves.

[0053] The microwave heating device 100 of Embodiment 1 includes, in addition to the second resonator 3, a third resonator 4 that changes the phase of microwaves incident from the first internal space SP1 by 90° or more within a predetermined frequency band and reflects them back to the first internal space SP1. As a result, in the microwave heating device 100 of Embodiment 1, as shown in Figure 4, the variation in the amount of heating by microwaves becomes more reliably uniform across the first wall portion 211 (position P0) and the second wall portion 212 (position P2) compared to the microwave heating device of the comparative example. As a result, the microwave heating device 100 of Embodiment 1 has the advantage of being able to heat the object to be heated TA1 more reliably and uniformly using microwaves.

[0054] (1-4) Modifications of Embodiment 1 Embodiment 1 described above is only one of many embodiments of the present disclosure. Embodiment 1 described above can be modified in various ways depending on the design, etc., as long as the objectives of the present disclosure are achieved. The following modifications may be implemented by combining them as appropriate. Components similar to those in Embodiment 1 described above are denoted by the same reference numerals and their description is omitted.

[0055] (1-4-1) First Modified Example of Embodiment 1 The microwave heating device 100A of the first modified example of Embodiment 1, as shown in Figure 7, comprises an oscillator 1, a first resonator 2, a second resonator 3, a third resonator 4, a control device 9, and a coupling circuit mechanism 5. The coupling circuit mechanism 5 is positioned between the oscillator 1 and the first resonator 2 and adjusts the coupling strength between the oscillator 1 and the first resonator 2. As an example, the coupling circuit mechanism 5 has an opening hole that connects the oscillator 1 (or output unit 13) and the opening 22 of the first resonator 2, and is a mechanism that can arbitrarily adjust the dimensions of the opening hole. The coupling circuit mechanism 5 is connected to both the oscillator 1 (or output unit 13) and the opening 22 of the first resonator 2. The coupling circuit mechanism 5 is a so-called variable iris.

[0056] In the first modified microwave heating device 100A, the transmission efficiency of microwaves from the oscillator 1 to the first resonator 2 is optimized, improving the heating efficiency. Therefore, the first modified microwave heating device 100A has the advantage of being able to heat the object to be heated TA1 more uniformly using microwaves while improving heating efficiency.

[0057] (1-4-2) Second Modification of Embodiment 1 The microwave heating device 100B of the second modification of Embodiment 1, as shown in Figure 8, comprises an oscillator 1, a first resonator 2, a second resonator 3, a third resonator 4, a control device 9, a coupling circuit mechanism 5, and a matching device 6. The coupling circuit mechanism 5 is positioned between the oscillator 1 and the first resonator 2 and adjusts the coupling strength between the oscillator 1 and the first resonator 2. The matching device 6 is positioned between the oscillator 1 and the coupling circuit mechanism 5. The matching device 6 matches the impedance of the oscillator 1 with the impedance of the first resonator 2 and the impedance of the coupling circuit mechanism 5. The "impedance of the first resonator 2" as referred to in this disclosure changes depending on the conditions of the first internal space SP1 of the first resonator 2 (for example, the shape, material, etc., of the object to be heated TA1 placed in the first internal space SP1).

[0058] In the second modified microwave heating device 100B, the transmission efficiency of microwaves from the oscillator 1 to the first resonator 2 is optimized, and the heating efficiency is further improved. Therefore, the second modified microwave heating device 100B has the advantage of being able to heat the object to be heated TA1 more uniformly using microwaves while further improving the heating efficiency.

[0059] (1-4-3) Third Modification of Embodiment 1 The microwave heating device 100C of the third modification of Embodiment 1, as shown in Figure 9, comprises an oscillator 1, a first resonator 2, a second resonator 3, a third resonator 4, a control device 9, and a matching device 6. The matching device 6 matches the impedance of the oscillator 1 with the impedance of the first resonator 2. The matching device 6 is connected to both the oscillator 1 (or output unit 13) and the opening 22 of the first wall portion 211 of the first resonator 2.

[0060] In the third modified microwave heating device 100C, the transmission efficiency of microwaves from the oscillator 1 to the first resonator 2 is optimized, improving the heating efficiency. Therefore, the third modified microwave heating device 100C has the advantage of being able to heat the object to be heated TA1 more uniformly using microwaves while improving heating efficiency.

[0061] (1-4-4) Other Modifications of Embodiment 1 The following lists other modifications of Embodiment 1 described above.

[0062] The oscillator 1 may further include a directional coupler 14, an output detection unit 15, and a termination resistor 16, as shown in Figure 10. The directional coupler 14 monitors the microwaves supplied to the first internal space SP1 of the first resonator 2. The directional coupler 14 is positioned between the isolator 12 and the output unit 13. The output detection unit 15 is connected to the directional coupler 14 and detects the microwaves supplied to the first internal space SP1 of the first resonator 2. The output detection unit 15 is, for example, a power detection circuit. The termination resistor 16 is connected to the directional coupler 14 and absorbs reflected waves generated in the first internal space SP1 of the first resonator 2.

[0063] Furthermore, as shown in Figure 11, the oscillator 1 may have a reflection detection unit 17 instead of a termination resistor 16. In this case, the directional coupler 14 monitors both the microwave supplied to the first internal space SP1 of the oscillator 1 and the reflected waves generated in the first internal space SP1. The reflection detection unit 17 is connected to the directional coupler 14 and detects the reflected waves generated in the first internal space SP1. The reflection detection unit 17 is, for example, a power detection circuit.

[0064] (2) Embodiment 2 (2-1) Overview Next, an overview of the microwave heating apparatus 100D according to Embodiment 2 will be described with reference to Figure 12. Components similar to those in Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted.

[0065] The microwave heating device 100 of Embodiment 1 (see Figure 1) includes both a second resonator 3 and a third resonator 4. On the other hand, the microwave heating device 100D of Embodiment 2 includes only the second resonator 3.

[0066] The microwave heating device 100D of Embodiment 2 differs from the microwave heating device 100 of Embodiment 1 in the above respects.

[0067] (2-2) Detailed Configuration (2-2-1) Overall Configuration Below, the detailed configuration of the microwave heating apparatus 100D of Embodiment 2 will be described with reference to Figure 12.

[0068] As shown in Figure 12, the microwave heating device 100D comprises an oscillator 1, a first resonator 2, a second resonator 3, and a control device 9.

[0069] (2-2-2) Oscillator The oscillator 1 of Embodiment 2 generates microwaves to heat the object to be heated TA1 and changes the frequency of the microwaves within a predetermined frequency band. The oscillator 1 of Embodiment 2 performs a frequency sweep within the predetermined frequency band in response to control by the control device 9. The oscillator 1 of Embodiment 2 is located on the first wall portion 211 of the first resonator 2. A detailed explanation of the configuration of the oscillator 1 of Embodiment 2, which is the same as that of the oscillator 1 of Embodiment 1, will be omitted.

[0070] (2-2-3) First Resonator The first resonator 2 of Embodiment 2 guides (transmits) microwaves supplied from the oscillator 1, similar to the first resonator 2 of Embodiment 1. A detailed explanation of the configuration of the first resonator 2 of Embodiment 2, which is the same as that of the first resonator 2 of Embodiment 1, will be omitted below.

[0071] In the first resonator 2 of the second embodiment, an opening 22 is provided in the first wall portion 211. The first internal space SP1 is connected to the oscillator 1 through the opening 22 of the first wall portion 211. In short, microwaves generated by the oscillator 1 are supplied to the first internal space SP1 through the opening 22 of the first wall portion 211.

[0072] (2-3) Modifications of Embodiment 2 Embodiment 2 described above is only one of many embodiments of the present disclosure. Embodiment 2 described above can be modified in various ways depending on the design, etc., as long as the objectives of the present disclosure can be achieved. The following modifications may be implemented by combining them as appropriate. Components similar to those in Embodiment 2 described above are denoted by the same reference numerals and their descriptions are omitted.

[0073] (2-3-1) First Modification of Embodiment 2 The microwave heating device 100E of the first modification of Embodiment 2 comprises an oscillator 1, a first resonator 2, a second resonator 3, a control device 9, and a coupling circuit mechanism 5, as shown in Figure 13. The coupling circuit mechanism 5 is positioned between the oscillator 1 and the first resonator 2 and adjusts the coupling strength between the oscillator 1 and the first resonator 2. The coupling circuit mechanism 5 of the first modification of Embodiment 2 has the same configuration as the coupling circuit mechanism 5 of the first modification of Embodiment 1, so a detailed explanation is omitted.

[0074] In the first modified microwave heating device 100E, the transmission efficiency of microwaves from the oscillator 1 to the first resonator 2 is optimized, improving the heating efficiency. Therefore, the first modified microwave heating device 100E has the advantage of being able to heat the object to be heated TA1 more uniformly using microwaves while improving heating efficiency.

[0075] (2-3-2) Second Modified Example of Embodiment 2 The microwave heating device 100F of the second modified example of Embodiment 2 comprises an oscillator 1, a first resonator 2, a second resonator 3, a control device 9, a coupling circuit mechanism 5, and a matching device 6, as shown in Figure 14. The coupling circuit mechanism 5 is positioned between the oscillator 1 and the first resonator 2 and adjusts the coupling strength between the oscillator 1 and the first resonator 2. The matching device 6 is positioned between the oscillator 1 and the coupling circuit mechanism 5. The matching device 6 matches the impedance of the oscillator 1 with the impedance of the first resonator 2 and the impedance of the coupling circuit mechanism 5.

[0076] In the second modified microwave heating device 100F, the transmission efficiency of microwaves from the oscillator 1 to the first resonator 2 is optimized, and the heating efficiency is further improved. Therefore, the second modified microwave heating device 100F has the advantage of being able to heat the object to be heated TA1 more uniformly using microwaves while further improving the heating efficiency.

[0077] (2-3-3) Third Modification of Embodiment 2 The microwave heating device 100G of the third modification of Embodiment 2 includes an oscillator 1, a first resonator 2, a second resonator 3, a control device 9, and a matching unit 6, as shown in Figure 15. The matching unit 6 matches the impedance of the oscillator 1 with the impedance of the first resonator 2. The matching unit 6 is connected to both the oscillator 1 (or output unit 13) and the opening 22 of the first wall portion 211 of the first resonator 2.

[0078] In the third modified microwave heating device 100G, the transmission efficiency of microwaves from the oscillator 1 to the first resonator 2 is optimized, improving the heating efficiency. Therefore, the third modified microwave heating device 100G has the advantage of being able to heat the object to be heated TA1 more uniformly using microwaves while improving the heating efficiency.

[0079] (3) Embodiment 3 (3-1) Overview Next, an overview of the microwave heating apparatus 100H according to Embodiment 3 will be described with reference to Figures 16 and 17. Components similar to those in Embodiment 1 are denoted by the same reference numerals and their description is omitted.

[0080] In the microwave heating apparatus 100H of Embodiment 3, as shown in Figures 16 and 17, the object to be heated TA2 is in the form of a sheet, and the first resonator 2A is connected to the first internal space SP1, and a slot 25 into which the object to be heated TA2 is inserted is formed.

[0081] The microwave heating device 100H of Embodiment 3 differs from the microwave heating device 100 of Embodiment 1 in the above respects.

[0082] (3-2) Detailed Configuration (3-2-1) Overall Configuration Below, the detailed configuration of the microwave heating apparatus 100H of Embodiment 3 will be described with reference to Figures 16 and 17.

[0083] As shown in Figure 16, the microwave heating device 100H comprises an oscillator 1, a first resonator 2A, a second resonator 3A, and a control device 9.

[0084] (3-2-2) Oscillator The oscillator 1 of Embodiment 3 generates microwaves to heat the object to be heated TA2 and changes the frequency of the microwaves within a predetermined frequency band. The oscillator 1 of Embodiment 3 performs a frequency sweep within the predetermined frequency band in response to control by the control device 9. The oscillator 1 of Embodiment 3 is located on the outer surface of the first wall portion 211 of the first resonator 2A. A detailed explanation of the configuration of the oscillator 1 of Embodiment 3, which is the same as that of the oscillator 1 of Embodiment 1, will be omitted.

[0085] (3-2-3) First Resonator The first resonator 2A guides (transmits) the microwaves supplied from the oscillator 1. The first resonator 2A is a rectangular waveguide, as shown in Figures 16 and 17. The first resonator 2A is rectangular when viewed from the Y-axis direction. The dimension of the first resonator 2A in the X-axis direction is larger than the dimensions in the Y-axis direction and the Z-axis direction, respectively. The first resonator 2A is made of a conductive material, such as copper, iron, or aluminum. The first resonator 2A may be a hollow cylindrical, hollow spherical, or other hollow polygonal prism waveguide, and the shape of the first resonator 2A is not limited.

[0086] The first resonator 2A is a hollow tube having a first internal space (cavity) SP1. The first resonator 2A guides microwaves in the first internal space SP1. The direction in which the first resonator 2A guides microwaves is the longitudinal direction of the first resonator 2A, that is, the X-axis direction. The first internal space SP1 is a rectangular box-shaped space. However, the first internal space SP1 may also be cylindrical, spherical, or other polygonal space, and the shape of the first internal space SP1 is not limited.

[0087] The first resonator 2A has two wall portions 21 that resonate in a predetermined direction D1 by reflecting microwaves supplied to the first internal space SP1, thereby forming (generating) a standing wave. The microwaves supplied to the first internal space SP1 are reflected by the inner surfaces of the two wall portions 21. The two wall portions 21 are the first wall portion 211 and the second wall portion 212. The predetermined direction D1 is the X-axis direction.

[0088] Microwaves supplied to the first internal space SP1 are reflected by the first wall 211 and the second wall 212, causing them to resonate in a predetermined direction D1 and form a standing wave. For example, in the first internal space SP1, if the distance from the first wall 211 to the second wall 212 in the predetermined direction D1 is an integer multiple of half the wavelength of the microwaves supplied from the oscillator 1, the microwaves resonate in the predetermined direction D1 and form a standing wave.

[0089] In the first resonator 2A of Embodiment 3, an opening 22 is provided in the first wall portion 211. The first internal space SP1 is connected to the oscillator 1 through the opening 22 of the first wall portion 211. In short, microwaves generated by the oscillator 1 are supplied to the first internal space SP1 through the opening 22 of the first wall portion 211. The opening 22 is, for example, rectangular. However, the opening 22 may also be circular, and its shape is not limited.

[0090] In the first resonator 2A of Embodiment 3, an opening 23 is provided in the second wall portion 212. The opening 23 of the second wall portion 212 is connected to an opening 31 of the second resonator 3A, which will be described later. The first internal space SP1 is in communication with the second internal space SP2 of the second resonator 3A via the opening 23 of the second wall portion 212 and the opening 31 of the second resonator 3A. The opening 23 is, for example, rectangular. However, the opening 23 may also be circular, and its shape is not limited.

[0091] In the microwave heating apparatus 100H of Embodiment 3, the object to be heated TA2 is in the form of a sheet. More specifically, the object to be heated TA2 is a film material containing a solvent. As a specific example, the object to be heated TA2 is a film material, so-called a prepreg, manufactured by impregnating a fibrous substrate such as glass cloth with varnish (a coating made by adding a solvent to a resin composition) and drying it. Alternatively, the object to be heated TA2 may be a film material, i.e., a resin-coated film, manufactured by coating a film-like substrate such as a support (PET film, etc.) with a resin composition containing a solvent. The object to be heated TA2 is conveyed to the first resonator 2A by a roll-to-roll method.

[0092] As shown in Figures 16 and 17, the first resonator 2A is connected to the first internal space SP1 and has a slot 25 into which the transported object to be heated TA2 is inserted. The first resonator 2A is a single-mode slot waveguide type heating furnace. As shown in Figure 17, the slot 25 is an opening that penetrates the first resonator 2A along the Z-axis direction. The object to be heated TA2 inserted into the slot 25 passes through the first internal space SP1 of the first resonator 2A along the Z-axis direction. The slot 25 is a rectangular opening when viewed from the Z-axis direction. The dimensions of the slot 25 in the X-axis and Y-axis directions are larger than the dimensions of the object to be heated TA2 in the X-axis and Y-axis directions. Microwaves supplied to the first internal space SP1 and forming standing waves heat the object to be heated TA2 inserted into the slot 25.

[0093] (3-2-4) Second resonator The second resonator 3A guides (transmits) microwaves incident from the first internal space SP1 of the first resonator 2A. The second resonator 3A is rectangular in shape. The second resonator 3A is made of a conductive material, such as copper, iron, or aluminum. The second resonator 3A is positioned on the outer surface of the second wall portion 212 of the first resonator 2A. The second resonator 3A may be a hollow cylindrical, hollow spherical, or other hollow polygonal prism waveguide, and the shape of the second resonator 3A is not limited.

[0094] As shown in Figure 16, the second resonator 3A is a hollow box-shaped structure having a second internal space (cavity) SP2. Microwaves are incident on the second internal space SP2 from the first internal space SP1 of the first resonator 2A. The second internal space SP2 is a rectangular box-shaped space. Furthermore, the second internal space SP2 may be cylindrical, spherical, or other polygonal prism-shaped space, and its shape is not limited.

[0095] In Embodiment 3, the dimension of the second resonator 3A in the X-axis direction is smaller than the dimension of the first resonator 2A in the X-axis direction, and the dimension of the second resonator 3A in the Z-axis direction is larger than the dimension of the first resonator 2A in the Z-axis direction.

[0096] The second resonator 3A has two wall portions 32 that resonate in a predetermined direction D1 and form (generate) a standing wave by reflecting microwaves that are incident from the first internal space SP1 and supplied to the second internal space SP2. The microwaves are reflected by the inner surfaces of the two wall portions 32. The two wall portions 32 are the first wall portion 321 and the second wall portion 322.

[0097] In the second resonator 3A of Embodiment 3, an opening 31 is provided in the first wall portion 321. The opening 31 of the first wall portion 321 is connected to the opening 23 of the first resonator 2A. The second internal space SP2 is in communication with the first internal space SP1 of the first resonator 2A via the opening 31 of the first wall portion 321 and the opening 23 of the second wall portion 212 of the first resonator 2A. The opening 31 is, for example, rectangular. It is desirable that the opening 31 has the same shape as the opening 23 of the second wall portion 212 of the first resonator 2A. However, the opening 31 may also be circular, and its shape is not limited.

[0098] Because the oscillator 1 changes the microwave frequency within a predetermined frequency band, the phase of the microwave reflected by the second resonator 3A of Embodiment 3 to the first internal space SP1 changes by 90° or more over the predetermined frequency band. In other words, the second resonator 3A of Embodiment 3, like the second resonator 3 of Embodiment 1, changes the phase of the microwave incident from the first internal space SP1 by 90° or more within the predetermined frequency band and reflects it to the first internal space SP1. In short, the oscillator 1 changes the microwave frequency within a predetermined frequency band so that the second resonator 3A of Embodiment 3 changes the phase of the microwave incident from the first internal space SP1 by 90° or more over the predetermined frequency band and reflects it to the first internal space SP1.

[0099] (3-3) Modifications of Embodiment 3 Embodiment 3 described above is merely one of many embodiments of the present disclosure. Embodiment 3 described above can be modified in various ways depending on the design, etc., as long as the objectives of the present disclosure can be achieved. The following modifications may be implemented by combining them as appropriate. Components similar to those in Embodiment 3 described above are denoted by the same reference numerals and their descriptions are omitted.

[0100] (3-3-1) First Modification of Embodiment 3 The microwave heating device 100I of the first modification of Embodiment 3 comprises an oscillator 1, a first resonator 2A, a second resonator 3A, a control device 9, and a coupling circuit mechanism 5, as shown in Figure 18. The coupling circuit mechanism 5 is positioned between the oscillator 1 and the first resonator 2A and adjusts the coupling strength between the oscillator 1 and the first resonator 2A. The coupling circuit mechanism 5 of the first modification of Embodiment 3 has the same configuration as the coupling circuit mechanism 5 of the first modification of Embodiment 1, so a detailed explanation is omitted.

[0101] In the first modified microwave heating device 100I, the transmission efficiency of microwaves from the oscillator 1 to the first resonator 2A is optimized, improving the heating efficiency. Therefore, the first modified microwave heating device 100I has the advantage of being able to heat the object to be heated TA2 more uniformly using microwaves while improving the heating efficiency.

[0102] (3-3-2) Second Modified Example of Embodiment 3 The microwave heating device 100J of the second modified example of Embodiment 3, as shown in Figure 19, comprises an oscillator 1, a first resonator 2A, a second resonator 3A, a control device 9, a coupling circuit mechanism 5, and a matching device 6. The coupling circuit mechanism 5 is positioned between the oscillator 1 and the first resonator 2A and adjusts the coupling strength between the oscillator 1 and the first resonator 2A. The matching device 6 is positioned between the oscillator 1 and the coupling circuit mechanism 5. The matching device 6 matches the impedance of the oscillator 1 with the impedance of the first resonator 2A and the impedance of the coupling circuit mechanism 5.

[0103] In the second modified microwave heating device 100J, the transmission efficiency of microwaves from the oscillator 1 to the first resonator 2A is optimized, and the heating efficiency is further improved. Therefore, the second modified microwave heating device 100J has the advantage of being able to heat the object to be heated TA2 more uniformly using microwaves while further improving the heating efficiency.

[0104] (3-3-3) Third Modification of Embodiment 3 The microwave heating device 100K of the third modification of Embodiment 3 includes an oscillator 1, a first resonator 2A, a second resonator 3A, a control device 9, and a matching device 6, as shown in Figure 20. The matching device 6 matches the impedance of the oscillator 1 with the impedance of the first resonator 2A. The matching device 6 is connected to both the oscillator 1 (or output unit 13) and the opening 22 of the first wall portion 211 of the first resonator 2A.

[0105] In the third modified microwave heating device 100K, the transmission efficiency of microwaves from the oscillator 1 to the first resonator 2A is optimized, improving the heating efficiency. Therefore, the third modified microwave heating device 100K has the advantage of being able to heat the object to be heated TA2 more uniformly using microwaves while improving the heating efficiency.

[0106] (3-3-4) Other Modifications of Embodiment 3 The following lists other modifications of Embodiment 3 described above.

[0107] As shown in Figure 21, the first resonator 2B may have a choke structure 29 that suppresses microwave leakage from the slot 25. This configuration increases the amount of microwaves guided through the first internal space SP1 of the first resonator 2B. As a result, the microwave heating device 100H equipped with the first resonator 2B has the advantage of being able to efficiently heat the object to be heated TA2.

[0108] More specifically, the first resonator 2B has two choke structures 29. The two choke structures 29 are attached to the slot 25. More specifically, one of the two choke structures 29 is attached to the side of the slot 25 where the object to be heated TA2 is inserted (front side), and the other choke structure 29 is attached to the side of the slot 25 where the object to be heated TA2 is removed (rear side).

[0109] Each of the two choke structures 29 is a so-called λ / 4 choke structure. Each of the two choke structures 29 may be a multi-stage type with multiple λ / 4 choke structures, or any choke structure known in the field of microwave ovens and other technologies. Furthermore, the two choke structures 29 may have radio wave absorbing material provided at the entrance and exit of the slot 25, respectively.

[0110] In the above-described embodiment 3, the first resonator 2A is rectangular when viewed from the Y-axis direction. However, the first resonator 2A may be folded in a zigzag pattern when viewed from the Y-axis direction. In this disclosure, "zigzag pattern" means a shape in which a plurality of straight sections are aligned along the Z-axis direction, and focusing on the first, second, and third straight sections that are aligned continuously, the first ends of the first and second straight sections are connected by a U-shaped bend, and the second ends of the second and third straight sections are connected by a U-shaped bend.

[0111] Furthermore, the microwave heating apparatus 100H according to Embodiment 3, and the microwave heating apparatus according to each modified example of Embodiment 3, may also be used for firing ceramic devices molded into a green sheet shape, or for curing other plastic devices.

[0112] (4) Embodiment 4 (4-1) Overview Next, an overview of the microwave heating apparatus 100L according to Embodiment 4 will be described with reference to Figure 22. Components similar to those in Embodiment 1, Embodiment 2, and Embodiment 3 are denoted by the same reference numerals and their descriptions are omitted.

[0113] In the microwave heating device 100H of Embodiment 3 (see Figure 16), the oscillator 1 is positioned on the first wall portion 211 of the first resonator 2A. Furthermore, the microwave heating device 100H of Embodiment 3 includes a second resonator 3A but does not include a third resonator 4A. On the other hand, as shown in Figure 22, in the microwave heating device 100L of Embodiment 4, the oscillator 1 is positioned on the side wall of the first resonator 2C so as to be aligned with the first resonator 2C in a second direction D2 that intersects (here, orthogonal to) the first direction D1, which is a predetermined direction D1. Furthermore, the microwave heating device 100L of Embodiment 4 includes both a second resonator 3A and a third resonator 4A.

[0114] The microwave heating device 100L of Embodiment 4 differs from the microwave heating device 100H of Embodiment 3 in the above respect.

[0115] (4-2) Detailed Configuration (4-2-1) Overall Configuration Below, the detailed configuration of the microwave heating apparatus 100L of Embodiment 4 will be described with reference to Figure 22.

[0116] As shown in Figure 22, the microwave heating device 100L comprises an oscillator 1, a first resonator 2C, a second resonator 3A, a third resonator 4A, a control device 9, and a waveguide 8.

[0117] (4-2-2) Oscillator The oscillator 1 generates microwaves to heat the object to be heated TA2 and changes the frequency of the microwaves within a predetermined frequency band. The oscillator 1 performs a frequency sweep within the predetermined frequency band in response to control by the control device 9. A detailed explanation of the same configuration as the oscillator 1 of Embodiment 1 in Embodiment 4 will be omitted below.

[0118] In Embodiment 4, the oscillator 1 is positioned on the side wall of the first resonator 2C via a waveguide 8, so as to be aligned with the first resonator 2C in a second direction D2 that intersects (in this case, orthogonal to) the first direction D1, which is a predetermined direction D1. Alternatively, the oscillator 1 in Embodiment 4 may be positioned on the side wall of the first resonator 2C without the waveguide 8.

[0119] (4-2-3) First Resonator The first resonator 2C guides (transmits) the microwaves supplied from the oscillator 1. The first resonator 2C is a rectangular waveguide with a rectangular cross-sectional shape. The first resonator 2C may be a hollow cylindrical, hollow spherical, or other hollow polygonal prism waveguide, and the shape of the first resonator 2C is not limited. In the following description of the first resonator 2C of Embodiment 4, a detailed explanation of the configuration similar to that of the first resonator 2A of Embodiment 3 will be omitted.

[0120] In the first resonator 2C of Embodiment 4, an opening 22A is provided in the side wall. The first internal space SP1 is connected to the oscillator 1 via the opening 22A and the waveguide 8. In short, microwaves generated by the oscillator 1 are supplied to the first internal space SP1 through the opening 22A and the waveguide 8. The opening 22A is, for example, rectangular. However, the opening 22A may also be circular, and its shape is not limited.

[0121] In the first resonator 2C of Embodiment 4, an opening 24 is provided in the first wall portion 211. The opening 24 of the first wall portion 211 is connected to an opening 41 of the third resonator 4A, which will be described later. The first internal space SP1 is in communication with the third internal space SP3 of the third resonator 4A via the opening 24 of the first wall portion 211 and the opening 41 of the third resonator 4A. The opening 24 is, for example, rectangular. However, the opening 24 may also be circular, and its shape is not limited.

[0122] (4-2-4) Third Resonator The third resonator 4A guides (transmits) microwaves incident from the first internal space SP1 of the first resonator 2C. The third resonator 4A is rectangular in shape. The third resonator 4A is made of a conductive material, such as copper, iron, or aluminum. The third resonator 4A is positioned on the outer surface of the first wall portion 211 of the first resonator 2C. The third resonator 4A may be a hollow cylindrical, hollow spherical, or other hollow polygonal prism waveguide, and the shape of the third resonator 4A is not limited.

[0123] As shown in Figure 22, the third resonator 4A is a hollow box-shaped structure having a third internal space (cavity) SP3. Microwaves are incident on the third internal space SP3 from the first internal space SP1 of the first resonator 2C. The third internal space SP3 is a rectangular parallelepiped space. Furthermore, the third internal space SP3 may be cylindrical, spherical, or other polygonal prism-shaped space, and its shape is not limited.

[0124] In Embodiment 4, the dimension of the third resonator 4A in the X-axis direction is smaller than the dimension of the first resonator 2C in the X-axis direction, and the dimension of the third resonator 4A in the Z-axis direction is larger than the dimension of the first resonator 2C in the Z-axis direction.

[0125] The third resonator 4A has two wall portions 42 that resonate in a predetermined direction D1 and form (generate) a standing wave by reflecting microwaves that are incident from the first internal space SP1 and supplied to the third internal space SP3. The microwaves are reflected from the inner surfaces of the two wall portions 42. The two wall portions 42 are the first wall portion 421 and the second wall portion 422.

[0126] In the third resonator 4A of Embodiment 4, an opening 41 is provided in the first wall portion 421. The opening 41 of the first wall portion 421 is connected to the opening 24 of the first resonator 2C. The third internal space SP3 is in communication with the first internal space SP1 of the first resonator 2C via the opening 41 of the first wall portion 421 and the opening 24 of the first wall portion 211 of the first resonator 2C. The opening 41 is, for example, rectangular. It is desirable that the opening 41 has the same shape as the opening 24 of the first wall portion 211 of the first resonator 2C. However, the opening 41 may also be circular, and its shape is not limited.

[0127] Because the oscillator 1 changes the microwave frequency within a predetermined frequency band, the phase of the microwave reflected by the third resonator 4A of Embodiment 4 to the first internal space SP1 changes by 90° or more over the predetermined frequency band. In other words, the third resonator 4A of Embodiment 4, like the third resonator 4 of Embodiment 1, changes the phase of the microwave incident from the first internal space SP1 by 90° or more within the predetermined frequency band and reflects it to the first internal space SP1. In short, the oscillator 1 changes the microwave frequency within a predetermined frequency band so that the third resonator 4A of Embodiment 4 changes the phase of the microwave incident from the first internal space SP1 by 90° or more over the predetermined frequency band and reflects it to the first internal space SP1.

[0128] (4-3) Modifications of Embodiment 4 Embodiment 4 described above is merely one of many embodiments of the present disclosure. Embodiment 4 described above can be modified in various ways depending on the design, etc., as long as the objectives of the present disclosure can be achieved. The following modifications may be implemented by combining them as appropriate. Components similar to those in Embodiment 4 described above are denoted by the same reference numerals and their descriptions are omitted.

[0129] (4-3-1) First Modification of Embodiment 4 The microwave heating device 100M of the first modification of Embodiment 4 includes, as shown in Figure 23, an oscillator 1, a first resonator 2C, a second resonator 3A, a third resonator 4A, a control device 9, a waveguide 8, and a coupling circuit mechanism 5. The coupling circuit mechanism 5 is positioned between the oscillator 1 and the first resonator 2C and adjusts the coupling strength between the oscillator 1 and the first resonator 2C. The coupling circuit mechanism 5 of the first modification of Embodiment 4 has the same configuration as the coupling circuit mechanism 5 of the first modification of Embodiment 1, so a detailed explanation is omitted.

[0130] In the first modified microwave heating device 100M, the transmission efficiency of microwaves from the oscillator 1 to the first resonator 2C is optimized, improving the heating efficiency. Therefore, the first modified microwave heating device 100M has the advantage of being able to heat the object to be heated TA2 more uniformly using microwaves while improving heating efficiency.

[0131] (4-3-2) Second Modified Example of Embodiment 4 The microwave heating device 100N of the second modified example of Embodiment 4, as shown in Figure 24, comprises an oscillator 1, a first resonator 2C, a second resonator 3A, a third resonator 4A, a control device 9, a waveguide 8, a coupling circuit mechanism 5, and a matching device 6. The coupling circuit mechanism 5 is positioned between the oscillator 1 and the first resonator 2C and adjusts the coupling strength between the oscillator 1 and the first resonator 2C. The matching device 6 is positioned between the oscillator 1 and the coupling circuit mechanism 5. The matching device 6 matches the impedance of the oscillator 1 with the impedance of the first resonator 2C and the impedance of the coupling circuit mechanism 5.

[0132] In the second modified microwave heating device 100N, the transmission efficiency of microwaves from the oscillator 1 to the first resonator 2C is optimized, and the heating efficiency is further improved. Therefore, the second modified microwave heating device 100N has the advantage of being able to heat the object to be heated TA2 more uniformly using microwaves while further improving the heating efficiency.

[0133] (4-3-3) Third Modification of Embodiment 4 The microwave heating device 100P of the third modification of Embodiment 4, as shown in Figure 25, comprises an oscillator 1, a first resonator 2C, a second resonator 3A, a third resonator 4A, a control device 9, a waveguide 8, and a matching device 6. The matching device 6 matches the impedance of the oscillator 1 with the impedance of the first resonator 2C. The matching device 6 is connected to both the oscillator 1 (or output unit 13) and the opening 22A of the first wall portion 211 of the first resonator 2C.

[0134] In the third modified microwave heating device 100P, the transmission efficiency of microwaves from the oscillator 1 to the first resonator 2C is optimized, improving the heating efficiency. Therefore, the third modified microwave heating device 100P has the advantage of being able to heat the object to be heated TA2 more uniformly using microwaves while improving heating efficiency.

[0135] The microwave heating apparatus 100L according to Embodiment 4, and the microwave heating apparatus according to each modified example of Embodiment 4, may also be used for firing ceramic devices molded into a green sheet shape, or for curing other plastic devices.

[0136] (5) Embodiment 5 Next, an overview of the microwave heating apparatus 100Q according to Embodiment 5 will be described with reference to Figure 26. Components similar to those in Embodiments 1, 2, 3, and 4 are denoted by the same reference numerals and their descriptions are omitted.

[0137] In the microwave heating device 100H of Embodiment 3 (see Figure 16), the second resonator 3A has a second internal space SP2 that communicates with the first internal space SP1 of the first resonator 2A. On the other hand, in the microwave heating device 100Q of Embodiment 5, the second resonator 3B does not have the above-mentioned second internal space SP2, but has an insulating substrate 33 and a conductor portion 34.

[0138] The microwave heating device 100Q of Embodiment 5 differs from the microwave heating device 100H of Embodiment 3 in the above respect.

[0139] (5-1) Detailed Configuration (5-1-1) Overall Configuration The detailed configuration of the microwave heating device 100Q of Embodiment 5 will be described below with reference to Figures 26 and 27.

[0140] As shown in Figure 26, the microwave heating device 100Q comprises an oscillator 1, a first resonator 2D, a second resonator 3B, and a control device 9.

[0141] (5-1-2) Oscillator The oscillator 1 of Embodiment 5 generates microwaves to heat the object to be heated TA2 and changes the frequency of the microwaves within a predetermined frequency band. The oscillator 1 of Embodiment 5 performs frequency sweep within the predetermined frequency band in response to control by the control device 9. The oscillator 1 of Embodiment 5 is located on the first wall portion 211 of the first resonator 2D. A detailed explanation of the configuration of the oscillator 1 of Embodiment 5, which is the same as that of the oscillator 1 of Embodiment 1, will be omitted.

[0142] (5-1-3) First Resonator The first resonator 2D guides (transmits) the microwaves supplied from the oscillator 1. The first resonator 2D is a rectangular waveguide. A detailed explanation of the configuration of the first resonator 2D in Embodiment 5, which is the same as that of the first resonator 2A in Embodiment 3, will be omitted.

[0143] In the first resonator 2D of Embodiment 5, there is no opening in the second wall portion 212, and the second resonator 3B is arranged on the inner surface of the second wall portion 212.

[0144] (5-1-4) Second Resonator The second resonator 3B, as shown in Figures 26 and 27, has an insulating substrate 33 and a conductor portion 34. The insulating substrate 33 is a plate member formed of an insulating material. The insulating substrate 33 is, for example, a rectangular plate. The insulating substrate 33 has a first surface and a second surface, and is arranged such that the second surface is in contact with the inner surface of the second wall portion 212. The thickness direction of the insulating substrate 33 is along a predetermined direction D1 (or the X-axis direction). The conductor portion 34 is formed on the first surface of the insulating substrate 33. The conductor portion 34 is made of a conductive material such as metal. The conductor portion 34 is rectangular when viewed from the predetermined direction D1. The conductor portion 34 may also be circular when viewed from the predetermined direction D1, and the shape of the conductor portion 34 is not limited.

[0145] The second resonator 3B resonates with the conductor portion 34 when microwaves guided in the first internal space SP1 are irradiated onto the conductor portion 34, causing resonance between the conductor portion 34 and the inner surface of the second wall portion 212. This changes the phase of the microwaves by 90° or more within a predetermined frequency band and reflects them back into the first internal space SP1. More specifically, when microwaves guided in the first internal space SP1 are irradiated onto the conductor portion 34, a current flows through the conductor portion 34, generating a magnetic field. Furthermore, an electric field is generated between the conductor portion 34 and the inner surface of the second wall portion 212. The magnetic and electric fields cause electromagnetic field resonance, and the second resonator 3B changes the phase of the microwaves by 90° or more within a predetermined frequency band and reflects them back into the first internal space SP1.

[0146] (5-2) Modifications of Embodiment 5 The following are modifications of Embodiment 5 described above. The following modifications may be implemented by combining them as appropriate.

[0147] The microwave heating device 100Q of Embodiment 5 may further include a coupling circuit mechanism 5, similar to the microwave heating device 100I of the first modified example of Embodiment 3 (see Figure 18). In this case, the coupling circuit mechanism 5 is positioned between the oscillator 1 and the first resonator 2D and adjusts the coupling strength between the oscillator 1 and the first resonator 2D.

[0148] Furthermore, the microwave heating device 100Q of Embodiment 5 may further include a coupling circuit mechanism 5 and a matching unit 6, similar to the microwave heating device 100J of the second modification of Embodiment 3 (see Figure 19). In this case, the coupling circuit mechanism 5 is positioned between the oscillator 1 and the first resonator 2D to adjust the coupling strength between the oscillator 1 and the first resonator 2D. The matching unit 6 is positioned between the oscillator 1 and the coupling circuit mechanism 5 to match the impedance of the oscillator 1 with the impedance of the first resonator 2D and the impedance of the coupling circuit mechanism 5.

[0149] Furthermore, the microwave heating device 100Q of Embodiment 5 may also include a matching unit 6, similar to the microwave heating device 100K of the third modification of Embodiment 3 (see Figure 20). In this case, the matching unit 6 is placed between the oscillator 1 and the coupling circuit mechanism 5, and matches the impedance of the oscillator 1 with the impedance of the first resonator 2D and the impedance of the coupling circuit mechanism 5.

[0150] The first resonator 2D may have no openings in its first wall portion 211, and a third resonator having a similar configuration to the second resonator 3B may be arranged on the inner surface of the first wall portion 211. In this case, the oscillator 1 is arranged on the side wall of the first resonator 2D so as to be aligned with the first resonator 2D in a direction intersecting the predetermined direction D1.

[0151] (Summary) The microwave heating device (100, 100A to 100Q) of the first embodiment comprises an oscillator (1), first resonators (2, 2A to 2D), and second resonators (3, 3A, 3B). The oscillator (1) generates microwaves to heat the object to be heated (TA1, TA2) and changes the frequency of the microwaves within a predetermined frequency band. The first resonators (2, 2A to 2D) have an internal space (SP1), a first wall portion (211), and a second wall portion (212). Microwaves are supplied to the internal space (SP1). The first wall portion (211) and the second wall portion (212) reflect microwaves to form standing waves in a predetermined direction (D1). The second resonators (3, 3A, 3B) are arranged in the second wall portion (212). The second resonators (3, 3A, 3B) reflect microwaves incident from the internal space (SP1) back into the internal space (SP1) after changing the phase of those microwaves by 90° or more within a predetermined frequency band.

[0152] This embodiment has the advantage of allowing for more uniform heating using microwaves.

[0153] The microwave heating apparatus (100, 100A to 100C) of the second embodiment further comprises a third resonator (4) in the first embodiment. The third resonator (4) is positioned in the first wall portion (211). The third resonator (4) reflects microwaves incident from the internal space (SP1) back into the internal space (SP1) after changing the phase of the microwaves by 90° or more within a predetermined frequency band. The oscillator (1) is aligned with the resonator in a second direction (D2) that intersects a first direction (D1), which is a predetermined direction (D1).

[0154] This embodiment has the advantage of allowing for more reliable and uniform heating using microwaves.

[0155] In the microwave heating apparatus of the third embodiment (100H to 100Q), the object to be heated (TA2) is in the form of a sheet, as in the first embodiment. The first resonators (2A to 2D) are connected to an internal space (SP1) and have slots (25) into which the object to be heated (TA2) is inserted.

[0156] This embodiment has the advantage that a sheet-like object to be heated (TA2) can be heated more uniformly using microwaves.

[0157] In the microwave heating apparatus of the fourth embodiment (100L to 100Q), in the third embodiment, the oscillator (1) is aligned with the resonator in a second direction (D2) that intersects a first direction (D1), which is a predetermined direction (D1). The microwave heating apparatus of the second embodiment (100L to 100Q) further comprises a third resonator (4A). The third resonator (4A) is arranged in the first wall portion (211). The third resonator (4A) reflects microwaves incident from the internal space (SP1) back into the internal space (SP1) after changing the phase of the microwaves by 90° or more within a predetermined frequency band.

[0158] This embodiment has the advantage of being able to heat more uniformly using microwaves while improving heating efficiency.

[0159] A microwave heating apparatus (100C, 100G, 100K, 100P) of the fifth embodiment further comprises a matching circuit (6) in any one of the first to fourth embodiments. The matching circuit (6) is positioned between the oscillator (1) and the first resonators (2, 2A to 2C) and matches the impedance of the oscillator (1) with the impedance of the first resonators (2, 2A to 2C).

[0160] This embodiment has the advantage of being able to heat more uniformly using microwaves while improving heating efficiency.

[0161] A microwave heating apparatus (100A, 100E, 100I, 100M) of the sixth embodiment further comprises a coupling circuit mechanism (5) in any one of the first to fifth embodiments. The coupling circuit mechanism (5) is positioned between the oscillator (1) and the first resonators (2, 2A to 2C) and adjusts the coupling strength between the oscillator (1) and the first resonators (2, 2A to 2C).

[0162] This embodiment has the advantage of being able to heat more uniformly using microwaves while improving heating efficiency.

[0163] The microwave heating apparatus of the seventh embodiment (100B, 100F, 100J, 100N) further comprises a matching circuit (6) in the sixth embodiment. The matching circuit (6) is positioned between the oscillator (1) and the coupling circuit mechanism (5) and matches the impedance of the oscillator (1) with the impedance of the first resonators (2, 2A to 2C) and the coupling circuit mechanism (5).

[0164] This embodiment has the advantage of being able to heat more uniformly using microwaves while improving heating efficiency.

[0165] A microwave heating apparatus according to any of the first to seventh embodiments may also be used for firing ceramic devices molded into a green sheet shape, or for curing other plastic devices.

[0166] 100, 100A to 100Q Microwave heating device 1 Oscillator 2, 2A to 2D First resonator 211 First wall 212 Second wall 25 Slot 3, 3A, 3B Second resonator 4, 4A Third resonator 5 Coupling circuit mechanism 6 Matching box D1 Predetermined direction (first direction) D2 Second direction SP1 Internal space (first internal space) TA1, TA2 Heated object

Claims

1. A microwave heating device comprising: an oscillator that generates microwaves to heat an object to be heated and changes the frequency of the microwaves within a predetermined frequency band; a first resonator having an internal space to which the microwaves are supplied, and a first wall portion and a second wall portion that form standing waves in a predetermined direction by reflecting the microwaves; and a second resonator disposed in the second wall portion that changes the phase of the microwaves incident from the internal space by 90° or more within the predetermined frequency band and reflects them back into the internal space.

2. The microwave heating apparatus according to claim 1, further comprising a third resonator disposed in the first wall portion, which changes the phase of the microwave incident from the internal space by 90° or more within the predetermined frequency band and reflects it back into the internal space, wherein the oscillator is aligned with the first resonator in a second direction intersecting the first direction which is the predetermined direction.

3. The microwave heating apparatus according to claim 1, wherein the object to be heated is in the form of a sheet, and the first resonator has a slot formed therein that is connected to the internal space into which the object to be heated is inserted.

4. The microwave heating apparatus according to claim 3, wherein the oscillator is arranged in a second direction intersecting the first direction which is the predetermined direction, and further comprises a third resonator positioned in the first wall portion, which changes the phase of the microwave incident from the internal space by 90° or more within the predetermined frequency band and reflects it back into the internal space.

5. The microwave heating apparatus according to any one of claims 1 to 4, further comprising a matching circuit disposed between the oscillator and the first resonator for matching the impedance of the oscillator with the impedance of the first resonator.

6. The microwave heating apparatus according to any one of claims 1 to 5, further comprising a coupling circuit mechanism disposed between the oscillator and the first resonator for adjusting the coupling strength between the oscillator and the first resonator.

7. The microwave heating apparatus according to claim 6, further comprising a matching circuit disposed between the oscillator and the coupling circuit mechanism for matching the impedance of the oscillator with the impedance of the first resonator and the coupling circuit mechanism.

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