Heating system and heating method

Abstract

Provided are a heating system and a heating method capable of facilitating the discovery of foreign matter when the foreign matter is mixed into an object to be heated. This heating system (100) comprises a rectangular waveguide (11), a supply unit (12), and a heating unit (X1). The rectangular waveguide (11) guides microwaves for performing magnetic field heating when an object to be heated, which includes a dielectric, passes through a prescribed location in an internal space. The supply unit (12) supplies microwaves to the rectangular waveguide (11) such that the magnetic field strength of the microwaves is locally maximized or maximized at the prescribed location. The heating unit (X1) heats the dielectric of the object to be heated, which has been subjected to the magnetic field heating, by a method different from the magnetic field heating.

Description

Heating System and Heating Method

[0001] The present disclosure generally relates to a heating system and a heating method. More specifically, the present disclosure relates to a heating system and a heating method including a heating unit that heats an object to be heated.

[0002] Patent Document 1 discloses a drying device that forms a resin or ceramic coated on the upper surface of a long base material with a predetermined thickness while running the base material forward on the base material.

[0003] By the way, in a heating system that heats an object to be heated using microwaves, when foreign matter is mixed in the object to be heated, an electric field may concentrate near the foreign matter and discharge (spark) may occur. Therefore, in the above heating system, it is required to easily detect foreign matter mixed in the object to be heated.

[0004] Japanese Patent Laid-Open No. 10-337520

[0005] An object of the present disclosure is to provide a heating system and a heating method capable of easily detecting the above foreign matter when foreign matter is mixed in an object to be heated.

[0006] A heating system according to an aspect of the present disclosure includes a rectangular waveguide, a supply unit, and a heating unit. The rectangular waveguide guides microwaves that perform magnetic field heating when an object to be heated containing a dielectric passes through a predetermined position in the internal space. The supply unit supplies the microwaves to the rectangular waveguide so that the magnetic field intensity of the microwaves becomes maximum or maximum at the predetermined position. The heating unit heats the dielectric of the object to be heated that has undergone the magnetic field heating by a method different from the magnetic field heating.

[0007] A heating method according to one aspect of the present disclosure is a heating method in which the heating system heats an object to be heated, and includes a first heating step and a second heating step. In the first heating step, the magnetic field heating is performed using microwaves as the object to be heated passes through a predetermined position. In the second heating step, the dielectric of the object to be heated, which was subjected to the magnetic field heating in the first heating step, is heated in a manner different from the magnetic field heating. In the first heating step, microwaves are supplied to the rectangular waveguide such that the magnetic field strength of the microwaves is maximized or at its maximum at the predetermined position.

[0008] Figure 1 is a block diagram showing the schematic configuration of a heating system according to Embodiment 1. Figure 2 is a perspective view of the first and second heating devices of the heating system. Figure 3 is a cross-sectional view showing electric field lines generated in the internal space of the first heating device of the heating system when the waveguide mode of the first microwave is the TE20 mode. Figure 4 is a cross-sectional view showing electric field lines generated in the internal space of the first heating device of the heating system when the waveguide mode of the second microwave is the TE10 mode. Figure 5 is a flowchart showing the heating method by which the heating system heats an object to be heated. Figure 6 is a cross-sectional view showing electric field lines generated in the internal space of the first heating device of the heating system according to a first modification of Embodiment 1 when the waveguide mode of the first microwave is the TE02 mode. Figure 7 is a cross-sectional view showing electric field lines generated in the internal space of the second heating device of the heating system according to a first modification of Embodiment 1 when the waveguide mode of the second microwave is the TE01 mode. Figure 8 is a perspective view of the first and second heating devices of the heating system according to a second modification of Embodiment 1. Figure 9 is a perspective view of the first and second heating devices of a heating system according to a third modification of Embodiment 1. Figure 10 is a perspective view of the first and second heating devices of a heating system according to Embodiment 2. Figure 11 is an explanatory diagram illustrating the simulation of the magnetic field distribution at the center position in the Z-axis direction of the first rectangular waveguide in the same heating system. Figure 12 is an explanatory diagram illustrating the simulation of the electric field distribution at the center position in the Z-axis direction of the first rectangular waveguide in the same heating system. Figure 13 is an explanatory diagram illustrating the simulation of the magnetic field distribution at the center position in the Z-axis direction of the second rectangular waveguide in the same heating system. Figure 14 is an explanatory diagram illustrating the simulation of the electric field distribution at the center position in the Z-axis direction of the second rectangular waveguide in the same heating system. Figure 15 is an explanatory diagram illustrating the simulation of the electric field distribution at the center position in the Z-axis direction when a foreign object F1 is present in a comparative example rectangular waveguide. Figure 16 is a perspective view of the first and second heating devices of a heating system according to a first modification of Embodiment 2. Figure 17 is a cross-sectional view of the second heating device of the heating system according to a second modification of Embodiment 2.Figure 18 is a cross-sectional view of the second heating device of the heating system according to a second modification of Embodiment 2, in which two second slots are formed. Figure 19 is a cross-sectional view of the second heating device of the heating system according to a third modification of Embodiment 2.

[0009] 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.

[0010] (1) Embodiment 1 (1-1) Overview Below, an overview of the heating system 100 according to Embodiment 1 will be described with reference to Figures 1 and 2.

[0011] Towards achieving carbon neutrality (a decarbonized society), the use of heating systems that utilize high-frequency induction heating using electromagnetic waves in the 3 kHz to 3 MHz frequency band, high-frequency dielectric heating using electromagnetic waves in the 3 MHz to 300 MHz frequency band, or microwave heating using electromagnetic waves in the 300 MHz to 300 GHz frequency band (microwave band) is being widely promoted in the manufacturing processes of industrial products involving heating (including drying, hardening, firing, sintering, polymerization, and decomposition).

[0012] The heating system 100 of Embodiment 1 heats the object to be heated SH1 using microwaves. As shown in Figure 1, the heating system 100 of Embodiment 1 comprises a first rectangular waveguide 11, a first supply unit 12, and a heating unit X1. The first rectangular waveguide 11 corresponds to the rectangular waveguide of the present disclosure, and the first supply unit 12 corresponds to the supply unit of the present disclosure.

[0013] The first rectangular waveguide 11 guides a first microwave that performs magnetic field heating as the object to be heated SH1 passes through a predetermined position PO1. The first supply unit 12 supplies the first microwave to the first rectangular waveguide 11 so that the magnetic field strength of the first microwave is at its maximum or maximum value at the predetermined position PO1. The heating unit X1 heats the dielectric of the object to be heated SH1, which has been magnetically heated by the first rectangular waveguide 11, by a method different from magnetic field heating (i.e., by drying or hardening it). The first microwave corresponds to the microwave in this disclosure. Furthermore, "the magnetic field strength is at its maximum or maximum value" as used in this disclosure is not limited to the magnetic field strength being exactly at its maximum or maximum value, but includes the position where the magnetic field strength is at its maximum or maximum value, or is near the maximum or maximum value; in other words, an error is permissible. The permissible range of error is, for example, about ±10% from the maximum or maximum value.

[0014] In the heating system 100 of Embodiment 1, the object to be heated SH1 is heated by a first rectangular waveguide 11 in a magnetic field before being heated by the heating unit X1 in a method different from magnetic field heating. If foreign matter (e.g., conductive material, magnetic material, semiconductor, etc.) is mixed in with the object to be heated SH1, the magnetic field heating of the object to be heated SH1 by the first rectangular waveguide 11 does not generate heat in the dielectric material contained in the object to be heated SH1, but it does generate heat in the foreign matter. Therefore, the magnetic field heating of the object to be heated SH1 by the first rectangular waveguide 11 can oxidize the foreign matter or carbonize the dielectric material surrounding the foreign matter. As a result, the heating system of Embodiment 1 has the advantage that foreign matter can be easily detected when it is mixed in with the object to be heated SH1.

[0015] (1-2) Detailed Configuration (1-2-1) Overall The detailed configuration of the heating system 100 of Embodiment 1 will be described below with reference to Figures 1 to 4.

[0016] In the following example, we define three mutually orthogonal axes: the X, Y, and Z axes. The axes parallel to the surface of the object to be heated SH1 (see Figure 2) are defined as the "X axis" and "Y axis," while the axis parallel to the thickness direction of the object to be heated SH1 is defined as the "Z axis." Furthermore, one of the two directions along the Y axis is 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 for illustrative purposes only and do not represent actual axes. Also, these directions are not intended to limit the direction in which the heating system 100 can be used.

[0017] The heating system 100 is used when heating an object to be heated SH1 (see Figure 2) that contains a dielectric. For example, the heating system 100 is used when heating an object to be heated SH1 that contains a solvent, with the aim of drying the object SH1.

[0018] The object to be heated SH1 in the heating system 100 of Embodiment 1 is in the form of a sheet. More specifically, the object to be heated SH1 is a film material containing a solvent. As a specific example, the object to be heated SH1 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 SH1 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 SH1 may also be used as a green sheet for electronic devices, varistors, or ceramic capacitors, and then heated and dried.

[0019] As shown in Figure 1, the heating system 100 includes a first heating device 1, a second heating device 2, a foreign object inspection device 3, and a conveying device 4.

[0020] The conveying device 4 conveys the object to be heated SH1 along the conveying direction A1 (see Figure 2) in a roll-to-roll manner. In Embodiment 1, the conveying direction A1 is the Y-axis direction. The conveying device 4 sequentially passes the object to be heated through the first slot 111 of the first rectangular waveguide 11 of the first heating device 1 (described later) and the second slot 211 of the second rectangular waveguide 21 of the second heating device 2 (described later).

[0021] (1-2-2) First heating device The first heating device 1 is a magnetic field heating furnace that uses a first microwave to heat the object to be heated SH1 in a magnetic field. In this disclosure, "magnetic field heating" refers to microwave heating, which heats the object to be heated SH1 using a magnetic field component using microwaves, or induction heating using high frequency. As an example, the first microwave mentioned above is a microwave with a frequency of 2.45 GHz.

[0022] As shown in Figure 1, the first heating device 1 includes a first rectangular waveguide 11, a first supply unit 12, a control unit 13, a variable shorting plate 14, a temperature monitor 15, and a movable mechanism 16. The first heating device 1 may also have a non-reflection terminator (dummy load) instead of the variable shorting plate 14.

[0023] (First Rectangular Waveguide) The first rectangular waveguide 11 guides (transmits) first microwaves that perform magnetic field heating on the object to be heated SH1 as the object to be heated SH1 passes through a first predetermined position PO1 in the internal space 110. The first rectangular waveguide 11 of Embodiment 1 is a rectangular waveguide with a rectangular cross-sectional shape, as shown in Figure 2. That is, the first rectangular waveguide 11 is rectangular when viewed from the Z-axis direction. As shown in Figure 2, the dimension of the first rectangular waveguide 11 in the X-axis direction is larger than the dimensions in the Y-axis direction and the Z-axis direction, respectively. Also, as shown in Figure 3, the dimension of the first rectangular waveguide 11 in the Z-axis direction is larger than the dimension in the Y-axis direction.

[0024] The first rectangular waveguide 11 is a hollow tube having an internal space (cavity) 110. The first rectangular waveguide 11 guides the first microwave within the internal space 110. The direction in which the first rectangular waveguide 11 guides the first microwave is the longitudinal direction of the first rectangular waveguide 11, that is, the X-axis direction. The internal space 110 is a rectangular box-shaped space. The first rectangular waveguide 11 is made of a conductive material, such as a metal such as copper, iron, or aluminum.

[0025] A variable shorting plate 14 (or a non-reflection terminator) is attached to one of the two ends in the X-axis direction of the internal space 110 of the first rectangular waveguide 11. The variable shorting plate 14 and the non-reflection terminator are rectangular plates. The dimensions in the Y-axis direction and the Z-axis direction of the variable shorting plate 14 and the non-reflection terminator are the same as the dimensions in the Y-axis direction and the Z-axis direction of the internal space 110. In this disclosure, "same" is not limited to being exactly the same, and errors are permitted. The range of permitted errors is, for example, about ±10%. The variable shorting plate 14 and the non-reflection terminator are made of a conductive material, such as a metal such as copper, iron, or aluminum.

[0026] The variable shorting plate 14 in Embodiment 1 is configured to be movable along the X-axis direction by a movable mechanism 16. As the variable shorting plate 14 moves along the X-axis direction, the length in the X-axis direction of the internal space 110 of the first rectangular waveguide 11 changes.

[0027] As shown in Figures 2 and 3, the first rectangular waveguide 11 has a first slot 111 into which the object to be heated SH1 is inserted and which passes through to a first predetermined position PO1 in the internal space 110. In other words, the first heating device 1 is a single-mode slot waveguide type heating furnace. The first slot 111 is an opening that penetrates the first rectangular waveguide 11 along the transport direction A1 (i.e., the Y-axis direction) in which the object to be heated SH1 is transported. The first slot 111 is connected to the internal space 110. The first slot 111 is a rectangular opening when viewed from the Y-axis direction. The dimensions of the first slot 111 in the X-axis direction and the Z-axis direction are larger than or the same as the dimensions of the object to be heated SH1 in the X-axis direction and the Z-axis direction.

[0028] As shown in Figure 3, the object to be heated SH1 passes through the internal space 110 of the first rectangular waveguide 11 along the transport direction A1 (i.e., the Y-axis direction). Also, the dimension of the first rectangular waveguide 11 in the Z-axis direction is larger than the dimension in the Y-axis direction.

[0029] Assume that a reflectionless terminator is attached to one of the two ends in the X-axis direction of the internal space 110 of the first rectangular waveguide 11. In this case, as shown in Figure 3, the waveguide mode of the first microwave transmitted through the internal space 110 of the first rectangular waveguide 11 is the TEX0 mode (where X is an integer satisfying X≧1) such that the magnetic field strength of the first microwave is maximum or maximal at a first predetermined position PO1 through which the object to be heated SH1 passes. That is, the electric field lines of the first microwave transmitted through the internal space 110 of the first rectangular waveguide 11 are parallel to the short side direction of the first rectangular waveguide 11 when viewed from the X-axis direction. Figure 3 illustrates the case where the waveguide mode of the first microwave is the TE20 mode (i.e., X=2) as an example. In this disclosure, "waveguide mode" is also called a transmission mode or waveguide mode.

[0030] Next, consider the case where a variable shorting plate 14 is mounted on one of the two ends of the internal space 110 of the first rectangular waveguide 11 so as to be movable along the X-axis. In this case, as the variable shorting plate 14 moves along the X-axis, the length of the internal space 110 of the first rectangular waveguide 11 in the X-axis direction changes. Depending on the position of the variable shorting plate 14 in the internal space 110 in the X-axis direction, the first microwave transmitted through the internal space 110 of the first rectangular waveguide 11 forms a standing wave and resonates in the direction in which the first rectangular waveguide 11 guides the first microwave (the longitudinal direction of the first rectangular waveguide 11, i.e., the X-axis direction). In other words, the first rectangular waveguide 11 operates as a cavity resonator. For example, in the internal space 110, if the distance in the X-axis direction from the end of the two ends in the X-axis direction to the variable shorting plate 14, where the variable shorting plate 14 is not attached, is an integer multiple of the half wavelength of the first microwave inside the tube, the first microwave resonates in the X-axis direction. When the first microwave resonates in the above waveguide direction, the waveguide mode of the first microwave transmitted through the internal space 110 of the first rectangular waveguide 11 is the TEX0Z mode (where X is an integer satisfying X≧1 and Z is an integer satisfying Z≧1).

[0031] When L1 is the dimension of the internal space 110 of the first rectangular waveguide 11 in the normal direction (Z-axis direction) of the E-plane P1 of the first rectangular waveguide 11, the first slot 111 is formed such that the distance D1 from the E-plane P1 in the normal direction is n × L1 / X (where n is an integer satisfying 0 ≤ n ≤ X) and it is parallel to the E-plane P1. As shown in Figure 3, when the waveguide mode of the first microwave is the TE20 mode (i.e., X = 2), the first slot 111 is formed such that the distance D1 from the E-plane P1 in the normal direction is L1 / 2 (n = 1) and it is parallel to the E-plane P1. With this configuration, the first rectangular waveguide 11 can efficiently perform magnetic field heating on the object to be heated SH1. As a result, when foreign matter is mixed in with the object to be heated SH1, the first rectangular waveguide 11 efficiently oxidizes the foreign matter or carbonizes the dielectric material surrounding the foreign matter by magnetically heating the object to be heated SH1. As a result, the heating system 100 of Embodiment 1 has the advantage that it is easier to detect foreign matter when it is mixed in with the object to be heated SH1. In this disclosure, "E-surface P1 of the first rectangular waveguide 11" refers to either the top surface or the bottom surface in the internal space 110 of the first rectangular waveguide 11.

[0032] (First supply unit) The first supply unit 12 supplies the first microwave to the first rectangular waveguide 11 such that the magnetic field strength of the first microwave is maximized or at its maximum at a first predetermined position PO1 through which the object to be heated SH1 passes in the internal space 110 of the first rectangular waveguide 11. Furthermore, the first supply unit 12 of Embodiment 1 supplies the first microwave to the first rectangular waveguide 11 such that the electric field strength of the first microwave is minimized or at its minimum at the first predetermined position PO1. In other words, the first supply unit 12 of Embodiment 1 supplies the first microwave to the first rectangular waveguide 11 such that the magnetic field strength of the first microwave is maximized or at its maximum, and the electric field strength is minimized or at its minimum at the first predetermined position PO1. With this configuration, when the first rectangular waveguide 11 heats the object to be heated SH1 using a magnetic field, if foreign matter is mixed in the object to be heated SH1, it is possible to more reliably generate heat only in the foreign matter, without generating heat in the dielectric material contained in the object to be heated SH1. This configuration has the advantage of suppressing the occurrence of discharge due to foreign matter contamination in the object to be heated SH1, while improving the accuracy of detecting foreign matter mixed in the object to be heated SH1. In this disclosure, "the magnetic field strength becomes minimum or lowest" is not limited to the magnetic field strength being exactly minimum or lowest, but includes being near minimum or lowest; in other words, error is acceptable. The acceptable range of error is, for example, about ±10% from minimum or lowest.

[0033] As shown in Figure 1, the first supply unit 12 includes an oscillator 121, an isolator 122, a power monitor 123, and a matching unit 124.

[0034] The oscillator 121 generates a first microwave to be supplied to the first rectangular waveguide 11. In Embodiment 1, the oscillator 121 can change the frequency of the first microwave within a predetermined frequency band. The oscillator 121 is, for example, a microwave generator such as a magnetron. Alternatively, the oscillator 121 may be a microwave generator using semiconductor solid elements.

[0035] The isolator 122 suppresses the effects of reflected waves generated in the internal space 110 of the first rectangular waveguide 11. More specifically, the isolator 122 allows the first microwaves oscillated by the oscillator 121 to propagate directly into the first rectangular waveguide 11, while absorbing the reflected waves so that they do not return to the oscillator 121. As a result, the isolator 122 protects the oscillator 121.

[0036] The power monitor 123 monitors the first microwave and reflected wave guided in the internal space 110 of the first rectangular waveguide 11. For example, the power monitor 123 constantly monitors the first microwave and reflected wave and notifies the supply control unit 131 of the occurrence of an abnormality if they fall outside the specified tolerance range.

[0037] The matching unit 124 matches the impedance of the oscillator 121 and the isolator 122 with the impedance of the internal space 110 of the first rectangular waveguide 11.

[0038] (Control Unit) As shown in Figure 1, the control unit 13 includes a supply control unit 131 and a short-circuit control unit 134.

[0039] The supply control unit 131 controls the first supply unit 12. More specifically, the supply control unit 131 includes an oscillation control unit 132 that controls the oscillation unit 121 and a matching control unit 133 that controls the matching circuit 124. The oscillation control unit 132 of Embodiment 1 controls the oscillation unit 121 according to the monitoring status of at least one of the power monitor 123 and the temperature monitor 15. Similarly, the matching control unit 133 of Embodiment 1 controls the matching circuit 124 according to the monitoring status of at least one of the power monitor 123 and the temperature monitor 15.

[0040] Furthermore, when the first microwave resonates in the guiding direction in which the first rectangular waveguide 11 guides the first microwave, the oscillation control unit 132 causes the oscillation unit 121 to perform a frequency sweep in a predetermined frequency band, thereby moving the positions of the antinodes and nodes of the standing waves formed in the internal space 110 of the first rectangular waveguide 11 in the guiding direction. In the guiding direction, the portion of the object to be heated SH1 corresponding to the position of the antinode of the standing wave formed in the internal space 110 of the first rectangular waveguide 11 is heated more strongly by the magnetic field compared to other portions. With the above configuration, it is possible to move the portion of the object to be heated SH1 that is heated more strongly by the magnetic field compared to other portions in the guiding direction. In other words, the first rectangular waveguide 11 can uniformly heat the object to be heated SH1 by the magnetic field. For this reason, there is an advantage in that the accuracy of detecting foreign matter can be improved when foreign matter is mixed in with the object to be heated SH1. In this disclosure, "moving the positions of the antinodes and nodes of the standing wave" means, more specifically, changing the positions where the antinodes and nodes of the standing wave are formed by changing the spacing (wavelength) of the standing wave formed in the internal space 110 of the first rectangular waveguide 11 in the above-mentioned waveguide direction.

[0041] The short-circuit control unit 134 controls a movable mechanism 16 that moves the variable short-circuit plate 14 along the X-axis direction in the internal space 110 of the first rectangular waveguide 11. That is, the short-circuit control unit 134 controls the position of the variable short-circuit plate 14 in the X-axis direction in the internal space 110 of the first rectangular waveguide 11. By controlling the position of the variable short-circuit plate 14 in the X-axis direction, the short-circuit control unit 134 controls the frequency at which the first microwave transmitted in the internal space 110 of the first rectangular waveguide 11 resonates in the above-mentioned waveguide direction. That is, by controlling the position of the variable short-circuit plate 14 in the X-axis direction, the short-circuit control unit 134 moves the positions of the antinodes and nodes of the standing wave formed in the internal space 110 of the first rectangular waveguide 11 in the above-mentioned waveguide direction. By changing the antinodes and nodes of the standing wave by about 1 / 4 of the wavelength inside the tube, uneven heating can be suppressed, and uniform heating can be enabled.

[0042] The control unit 13 preferably includes a computer system. In the computer system, some or all of the functions of the control unit 13 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 LSI is manufactured, 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.

[0043] (Temperature Monitor) The temperature monitor 15 monitors the temperature of the object to be heated SH1 as it passes through the first predetermined position PO1 in the internal space 110 of the first rectangular waveguide 11. For example, the temperature monitor 15 constantly monitors the temperature of the object to be heated SH1 and notifies the supply control unit 131 of the occurrence of a temperature abnormality if the temperature falls outside the specified temperature range.

[0044] (1-2-3) Foreign Object Inspection Device The foreign object inspection device 3 detects foreign objects contained in the heated object SH1 when magnetic field heating is performed by the first heating device 1 (the first rectangular waveguide 11). That is, when foreign objects are mixed in the heated object SH1, the foreign object inspection device 3 detects foreign objects contained in the heated object SH1 that has passed through the first predetermined position PO1 in the internal space 110 of the first rectangular waveguide 11. The foreign objects in the present disclosure are, for example, conductive materials, magnetic materials, semiconductors, and the like. That is, the foreign object inspection device 3 detects a detected material that is at least one of a conductive material, a magnetic material, and a semiconductor contained in the heated object SH1 that has undergone magnetic field heating. The foreign object inspection device 3 is at least one of a visible light camera, an infrared sensor, a temperature sensor, and a radio wave sensor.

[0045] Specifically, the color of the oxidized foreign object or the foreign object present near the carbonized dielectric is different from that of the non-carbonized dielectric. Therefore, as an example, when the foreign object inspection device 3 is a visible light camera, the foreign object inspection device 3 is preset based on the color of the non-carbonized dielectric, and detects a portion having a color different from the reference in the heated object SH1 to detect the foreign object.

[0046] The foreign object inspection device 3 is disposed between the first heating device 1 and the second heating device 2. More specifically, the foreign object inspection device 3 is disposed such that the entire X-axis direction of the heated object SH1 that has passed through the first rectangular waveguide 11 is included in the detection range of the foreign object inspection device 3.

[0047] (1-2-4) Second Heating Device The second heating device 2 is an electric field heating furnace that uses a second microwave different from the first microwave described above to perform electric field heating on the dielectric of the heated object SH1 that has been subjected to magnetic field heating by the first heating device 1. Note that the "electric field heating" in the present disclosure is so-called microwave heating that heats the heated object SH1 by an electric field (electric field) component or dielectric heating by a high frequency. Further, as an example, the second microwave described above has the same frequency (for example, 2.45 GHz) as the first microwave described above. Note that the second microwave described above may have a frequency different from the first microwave.

[0048] As shown in FIG. 1, the second heating device 2 includes a second rectangular waveguide 21, a second supply unit 22, a control unit 23, a variable short - circuit plate 24, a temperature monitor 25, and a movable mechanism 26. Note that the second heating device 2 may have a non - reflective terminator instead of the variable short - circuit plate 24. Since the temperature monitor 25 of the second heating device 2 is the same as the temperature monitor 15 of the first heating device 1, a detailed description thereof is omitted.

[0049] (Second rectangular waveguide) When the object to be heated SH1 passes through the second predetermined position PO2 in the internal space 210 of the second rectangular waveguide 21, the second rectangular waveguide 21 guides (transmits) a second microwave that performs electric - field heating on the object to be heated SH1. The heating unit X1 of Embodiment 1 is the second rectangular waveguide 21, which is a rectangular waveguide different from the first rectangular waveguide 11 of the first heating device 1. That is, the heating unit X1 of Embodiment 1 is the second rectangular waveguide 21 that performs electric - field heating on the dielectric of the object to be heated SH1 after magnetic - field heating is performed by the first rectangular waveguide 11. The second microwave guided by the second rectangular waveguide 21 is a microwave different from the first microwave guided by the first rectangular waveguide 11.

[0050] As shown in FIG. 2, the second rectangular waveguide 21 of Embodiment 1 is a rectangular waveguide with a rectangular cross - sectional shape. That is, when viewed from the Z - axis direction, the second rectangular waveguide 21 is rectangular. As shown in FIG. 2, the dimension of the second rectangular waveguide 21 in the X - axis direction is larger than each of the dimensions in the Y - axis direction and the Z - axis direction. Also, as shown in FIG. 4, the dimension of the second rectangular waveguide 21 in the Z - axis direction is larger than the dimension in the Y - axis direction.

[0051] The second rectangular waveguide 21 is a hollow tube having an internal space (cavity) 210. The second rectangular waveguide 21 guides the second microwave in the internal space 210. The guiding direction of the second microwave guided by the second rectangular waveguide 21 is the longitudinal direction of the second rectangular waveguide 21, that is, the X - axis direction. The internal space 210 is a rectangular - box - shaped space. The second rectangular waveguide 21 is formed of a conductive material, for example, made of a metal such as copper, iron, or aluminum.

[0052] A variable shorting plate 24 (or a reflectionless terminator) is attached to one of the two ends in the X-axis direction of the internal space 210 of the second rectangular waveguide 21. The variable shorting plate 24 and the reflectionless terminator are rectangular plates. The dimensions in the Y-axis direction and the Z-axis direction of the variable shorting plate 14 and the reflectionless terminator are the same as the dimensions in the Y-axis direction and the Z-axis direction of the internal space 210.

[0053] The variable shorting plate 24 in Embodiment 1 is configured to be movable along the X-axis direction by a movable mechanism 26. As the variable shorting plate 24 moves along the X-axis direction, the length in the X-axis direction of the internal space 210 of the second rectangular waveguide 21 changes.

[0054] As shown in Figures 2 and 4, the second rectangular waveguide 21 has a second slot 211 into which the object to be heated SH1 is inserted and which passes through to a second predetermined position PO2 in the internal space 210. In other words, the second heating device 2 is a single-mode slot waveguide type heating furnace. The second slot 211 is an opening that penetrates the second rectangular waveguide 21 along the transport direction A1 (i.e., the Y-axis direction) in which the object to be heated SH1 is transported. The second slot 211 is connected to the internal space 210. The second slot 211 is a rectangular opening when viewed from the Y-axis direction. The dimensions of the second slot 211 in the X-axis direction and the Z-axis direction are larger than or the same as the dimensions of the object to be heated SH1 in the X-axis direction and the Z-axis direction.

[0055] As shown in Figure 4, the object to be heated SH1 passes through the internal space 210 of the second rectangular waveguide 21 along the transport direction A1 (i.e., the Y-axis direction). Also, the dimension of the second rectangular waveguide 21 in the Z-axis direction is larger than the dimension in the Y-axis direction.

[0056] Assume that a reflectionless terminator is attached to one of the two ends in the X-axis direction of the internal space 210 of the second rectangular waveguide 21. In this case, as shown in Figure 4, the waveguide mode of the second microwave transmitted through the internal space 210 of the second rectangular waveguide 21 is the TEX0 mode (where X is an integer satisfying X≧1) so that the electric field strength of the second microwave is maximum or maximal at the second predetermined position PO2 through which the object to be heated SH1 passes. That is, the electric field lines of the second microwave transmitted through the internal space 210 of the second rectangular waveguide 21 are parallel to the short side direction of the first rectangular waveguide 11 when viewed from the X-axis direction. Figure 4 illustrates the case where the waveguide mode of the second microwave is the TE10 mode (i.e., X=1) as an example.

[0057] Next, consider the case where a variable shorting plate 24 is mounted on one of the two ends of the internal space 210 of the second rectangular waveguide 21 so as to be movable along the X-axis. In this case, as the variable shorting plate 24 moves along the X-axis, the length of the internal space 210 of the second rectangular waveguide 21 in the X-axis direction changes. Depending on the position of the variable shorting plate 24 in the internal space 210 in the X-axis direction, the second microwave transmitted through the internal space 210 of the second rectangular waveguide 21 forms a standing wave and resonates in the direction in which the second rectangular waveguide 21 guides the second microwave (the longitudinal direction of the second rectangular waveguide 21, i.e., the X-axis direction). In other words, the second rectangular waveguide 21 operates as a cavity resonator. For example, in the internal space 210, if the distance in the X-axis direction from the end of the two ends in the X-axis direction to the variable shorting plate 24, where the variable shorting plate 24 is not attached, is an integer multiple of the half wavelength of the second microwave inside the tube, the second microwave resonates in the X-axis direction. When the second microwave resonates in the above waveguide direction, the waveguide mode of the second microwave transmitted through the internal space 210 of the second rectangular waveguide 21 is the TEX0Z mode (where X is an integer satisfying X≧1 and Z is an integer satisfying Z≧1).

[0058] When the dimension of the internal space 210 of the second rectangular waveguide 21 in the normal direction (Z-axis direction) of the E-plane P2 of the second rectangular waveguide 21 is L2, the second slot 211 is formed such that the distance D2 from the E-plane P2 in the normal direction is (2m-1) × L2 / 2X (where m is an integer satisfying 1 ≤ m ≤ X) and it is parallel to the E-plane P2. As shown in Figure 4, when the waveguide mode of the second microwave is the TE10 mode (i.e., X=1), the second slot 211 is formed such that the distance D2 from the E-plane P2 in the normal direction is L2 / 2 (m=1) and it is parallel to the E-plane P2. This configuration has the advantage that the second rectangular waveguide 21 can efficiently perform electric field heating on the object SH1 to be heated. In this disclosure, "the E-plane P2 of the second rectangular waveguide 21" refers to either the top surface or the bottom surface in the internal space 210 of the second rectangular waveguide 21.

[0059] (Second supply unit) The second supply unit 22 supplies the second microwave to the second rectangular waveguide 21 such that the electric field strength of the second microwave is maximized or at its maximum at a second predetermined position PO2 through which the object to be heated SH1 passes in the internal space 210 of the second rectangular waveguide 21. Furthermore, the second supply unit 22 of Embodiment 1 supplies the second microwave to the second rectangular waveguide 21 such that the magnetic field strength of the second microwave is minimized or at its minimum at the second predetermined position PO2. In other words, the second supply unit 22 of Embodiment 1 supplies the second microwave to the second rectangular waveguide 21 such that the electric field strength of the second microwave is maximized or at its maximum, and the magnetic field strength is minimized or at its minimum at the second predetermined position PO2. With this configuration, the dielectric of the object to be heated SH1 can be heated more efficiently by electric field heating. Furthermore, the phrase "electric field strength reaches a local maximum or maximum value" as used in this disclosure is not limited to the electric field strength reaching an exact local maximum or maximum value, but also includes the electric field strength reaching an approximate value of the local maximum or maximum value; in other words, errors are permissible. The permissible range of errors is, for example, about ±10% from the local maximum or maximum value. Similarly, the phrase "electric field strength reaches a local minimum or minimum value" as used in this disclosure is not limited to the electric field strength reaching an exact local minimum or minimum value, but also includes the electric field strength reaching an approximate value of the local minimum or minimum value; in other words, errors are permissible. The permissible range of errors is, for example, about ±10% from the local minimum or minimum value.

[0060] As shown in Figure 1, the second supply unit 22 includes an oscillator 221, an isolator 222, a power monitor 223, and a matching unit 224.

[0061] The oscillator 221 generates a second microwave to be supplied to the second rectangular waveguide 21. In Embodiment 1, the oscillator 221 can change the frequency of the second microwave within a predetermined frequency band. The oscillator 221 is, for example, a microwave generator such as a magnetron. Alternatively, the oscillator 221 may be a microwave generator using semiconductor solid elements.

[0062] The isolator 222 suppresses the effects of reflected waves generated in the internal space 210 of the second rectangular waveguide 21. More specifically, the isolator 222 allows the second microwaves oscillated by the oscillator 221 to propagate directly into the second rectangular waveguide 21, while absorbing the reflected waves so that they do not return to the oscillator 221. As a result, the isolator 222 protects the oscillator 221.

[0063] The power monitor 223 monitors the second microwave and reflected wave guided in the internal space 210 of the second rectangular waveguide 21. For example, the power monitor 223 constantly monitors the second microwave and reflected wave and notifies the supply control unit 231 of the occurrence of an abnormality if they fall outside the specified tolerance range.

[0064] The matching unit 224 matches the impedance of the oscillator 221 and the isolator 222 with the impedance of the internal space 210 of the second rectangular waveguide 21.

[0065] (Control Unit) As shown in Figure 1, the control unit 23 includes a supply control unit 231 and a short-circuit control unit 234.

[0066] The supply control unit 231 controls the second supply unit 22. More specifically, the supply control unit 231 includes an oscillation control unit 232 that controls the oscillation unit 221 and a matching control unit 233 that controls the matching circuit 224. The oscillation control unit 232 in Embodiment 1 controls the oscillation unit 221 according to the monitoring status of at least one of the power monitor 223 and the temperature monitor 25. Similarly, the matching control unit 233 in Embodiment 1 controls the matching circuit 224 according to the monitoring status of at least one of the power monitor 223 and the temperature monitor 25.

[0067] Furthermore, when the second microwave resonates in the guiding direction in which the second rectangular waveguide 21 guides the second microwave, the oscillation control unit 232 causes the oscillation unit 221 to perform a frequency sweep in a predetermined frequency band, thereby moving the positions of the antinodes and nodes of the standing waves formed in the internal space 210 of the second rectangular waveguide 21 in the aforementioned guiding direction. In the aforementioned guiding direction, the portion of the object to be heated SH1 corresponding to the position of the antinode of the standing wave formed in the internal space 210 of the second rectangular waveguide 21 is electric-heated more strongly than other portions. With the above configuration, it is possible to move the portion of the object to be heated SH1 that is electric-heated more strongly than other portions in the aforementioned guiding direction. In other words, there is an advantage that the second rectangular waveguide 21 can electric-heat the object to be heated SH1 uniformly.

[0068] Furthermore, when the foreign object inspection device 3 detects a material to be detected, the oscillation control unit 232 controls the second supply unit 22 to temporarily stop supplying the second microwave when the material to be detected passes through the second predetermined position PO2 in the internal space 210 of the second rectangular waveguide 21. This configuration has the effect of suppressing the electric field heating of foreign objects when foreign objects are mixed in with the object to be heated SH1. As a result, there is the advantage that the concentration of the electric field on the foreign object can be further suppressed. In other words, the generation of discharge when foreign objects are mixed in can be suppressed.

[0069] The short-circuit control unit 234 controls a movable mechanism 16 that moves the variable short-circuit plate 24 along the X-axis direction in the internal space 210 of the second rectangular waveguide 21. That is, the short-circuit control unit 234 controls the position of the variable short-circuit plate 24 in the X-axis direction in the internal space 210 of the second rectangular waveguide 21. By controlling the position of the variable short-circuit plate 24 in the X-axis direction, the short-circuit control unit 234 controls the frequency at which the second microwave transmitted in the internal space 210 of the second rectangular waveguide 21 resonates in the above-mentioned waveguide direction. That is, by controlling the position of the variable short-circuit plate 24 in the X-axis direction, the short-circuit control unit 234 moves the positions of the antinodes and nodes of the standing wave formed in the internal space 210 of the second rectangular waveguide 21 in the above-mentioned waveguide direction. By changing the antinodes and nodes of the standing wave by about 1 / 4 of a wavelength inside the tube, uneven heating can be suppressed, and uniform heating can be enabled.

[0070] The control unit 23 preferably includes a computer system. In the computer system, some or all of the functions of the control unit 23 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 or LSI. 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, or ULSIs. Field-programmable gate arrays, which 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 aggregated in a single device or provided in multiple devices.

[0071] (1-3) Heating Method Next, a heating method in which the heating system 100 of Embodiment 1 heats the object to be heated SH1 using microwaves will be described with reference to Figure 5.

[0072] The heating method of Embodiment 1 includes a first heating step ST1, a detection step ST2, and a second heating step ST3, as shown in Figure 5.

[0073] In the first heating step ST1, the first heating device 1 uses the first microwave supplied by the first supply unit 12 to perform magnetic field heating on the object to be heated SH1 as it passes through a first predetermined position PO1 in the internal space 110 of the first rectangular waveguide 11. More specifically, in the first heating step ST1, the first rectangular waveguide 11 guides (transmits) the first microwave that performs magnetic field heating on the object to be heated SH1 as it is inserted into the first slot 111 and passes through the first predetermined position PO1 in the internal space 110 of the first rectangular waveguide 11. That is, in the first heating step ST1, the object to be heated SH1 is inserted into the first slot 111 of the first rectangular waveguide 11 which is guiding the first microwave, and is heated by the magnetic field as it passes through the first predetermined position PO1 in the internal space 110 of the first rectangular waveguide 11.

[0074] In the first heating step ST1, the first supply unit 12 supplies the first microwave to the first rectangular waveguide 11 such that the magnetic field strength of the first microwave is maximized or at its maximum at a first predetermined position PO1 through which the object to be heated SH1 passes in the internal space 110 of the first rectangular waveguide 11. In the first heating step ST1 of Embodiment 1, the first supply unit 12 supplies the first microwave to the first rectangular waveguide 11 such that the electric field strength of the first microwave is minimized or at its minimum at the first predetermined position PO1. That is, in the first heating step ST1 of Embodiment 1, the first supply unit 12 supplies the first microwave to the first rectangular waveguide 11 such that the magnetic field strength of the first microwave is maximized or at its maximum, and the electric field strength is minimized or at its minimum at the first predetermined position PO1.

[0075] In detection step ST2, if foreign matter is present in the object to be heated SH1, the foreign matter inspection device 3 detects the foreign matter contained in the object to be heated SH1 that has been magnetically heated by the first heating device 1 (first rectangular waveguide 11) in the first heating step ST1. That is, in detection step ST2, if foreign matter is present in the object to be heated SH1, the foreign matter inspection device 3 detects the foreign matter contained in the object to be heated SH1 that has passed through the first predetermined position PO1 in the internal space 110 of the first rectangular waveguide 11 in the first heating step ST1. The foreign matter in this disclosure is, for example, conductive material, magnetic material, and semiconductor. In other words, in detection step ST2, the foreign matter inspection device 3 detects the material to be detected, which is at least one of the conductive material, magnetic material, and semiconductor contained in the object to be heated SH1 that has been magnetically heated.

[0076] In the second heating step ST3, the second heating device 2 heats the dielectric of the object to be heated SH1, which was heated by magnetic field heating in the first heating step ST1, using a method different from magnetic field heating. In the heating method of Embodiment 1, the second heating step ST3 is performed after the detection step ST2.

[0077] In the second heating step ST3 of Embodiment 1, the second heating device 2 uses the second microwave supplied by the second supply unit 22 to perform electric field heating on the object to be heated SH1 as it passes through the second predetermined position PO2 in the internal space 210. More specifically, in the second heating step ST3, the second rectangular waveguide 21 guides (transmits) the second microwave that performs electric field heating on the object to be heated SH1 as it is inserted into the second slot 211 and passes through the second predetermined position PO2 in the internal space 210 of the second rectangular waveguide 21. That is, in the second heating step ST3, the object to be heated SH1 is inserted into the second slot 211 of the second rectangular waveguide 21 which is guiding the second microwave, and is electric field heated as it passes through the second predetermined position PO2 in the internal space 210 of the second rectangular waveguide 21.

[0078] In the second heating step ST3, the second supply unit 22 supplies the second microwave to the second rectangular waveguide 21 such that the electric field strength of the second microwave is maximized or at its maximum at a second predetermined position PO2 through which the object to be heated SH1 passes in the internal space 210 of the second rectangular waveguide 21. Furthermore, in the second heating step ST3 of Embodiment 1, the second supply unit 22 supplies the second microwave to the second rectangular waveguide 21 such that the magnetic field strength of the second microwave is minimized or at its minimum at the second predetermined position PO2. That is, in the second heating step ST3 of Embodiment 1, the second supply unit 22 supplies the second microwave to the second rectangular waveguide 21 such that the electric field strength of the second microwave is maximized or at its maximum, and the magnetic field strength is minimized or at its minimum at the second predetermined position PO2.

[0079] In the second heating step ST3 of Embodiment 1, the oscillation control unit 232 controls the second supply unit 22 to temporarily stop supplying the second microwave when the material to be detected is detected by the foreign matter inspection device 3 in the detection step ST2, as the material to be detected passes through the second predetermined position PO2 in the internal space 210 of the second rectangular waveguide 21. This configuration has the effect of suppressing the electric field heating of foreign matter when foreign matter is mixed in with the object to be heated SH1. As a result, there is the advantage that the concentration of the electric field on the foreign matter can be further suppressed. In other words, the generation of discharge when foreign matter is mixed in can be suppressed.

[0080] (1-4) Advantages The heating system 100 of Embodiment 1 comprises a first rectangular waveguide 11, a first supply unit 12, and a heating unit X1. The first rectangular waveguide 11 guides first microwaves that perform magnetic field heating as the object to be heated SH1 passes through a first predetermined position PO1. The first supply unit 12 supplies first microwaves to the first rectangular waveguide 11 so that the magnetic field strength of the first microwaves is maximum or at its maximum at the first predetermined position PO1. The heating unit X1 heats the dielectric of the object to be heated SH1, which has been magnetically heated by the first rectangular waveguide 11, in a manner different from magnetic field heating.

[0081] With the above configuration, in the heating system 100 of Embodiment 1, the object to be heated SH1 is heated by the first rectangular waveguide 11 in a magnetic field before being heated by the heating unit X1 in a method different from magnetic field heating. If foreign matter (for example, conductive material, magnetic material, semiconductor, etc.) is mixed in with the object to be heated SH1, the magnetic field heating of the object to be heated SH1 by the first rectangular waveguide 11 does not generate heat in the dielectric material contained in the object to be heated SH1, but it does generate heat in the foreign matter. Therefore, the magnetic field heating of the object to be heated SH1 by the first rectangular waveguide 11 can oxidize the foreign matter or carbonize the dielectric material surrounding the foreign matter. As a result, the heating system of Embodiment 1 has the advantage that foreign matter can be easily detected when it is mixed in with the object to be heated SH1.

[0082] In the heating system 100 of Embodiment 1, the first supply unit 12 supplies the first microwave to the first rectangular waveguide 11 such that the magnetic field strength of the first microwave is maximum or extremely high and the electric field strength is minimum or extremely low at the first predetermined position PO1.

[0083] With the above configuration, the heating system 100 of Embodiment 1 can suppress the concentration of the electric field strength in the internal space 210 of the second rectangular waveguide 21D on the foreign matter when the object to be heated SH1 is microwave-heated by the heating unit X1. As a result, the heating system 100 of Embodiment 1 has the advantage of suppressing the occurrence of discharge in the internal space 210 of the second rectangular waveguide 21 when the object to be heated SH1 is microwave-heated by the heating unit X1.

[0084] In the heating system 100 of Embodiment 1, the object to be heated SH1 is in the form of a sheet. The object to be heated SH1 is inserted into the first rectangular waveguide 11, and a first slot 111 is formed in which the object to be heated SH1 passes to a first predetermined position PO1 in the internal space 110. The waveguide mode of the first microwave transmitted in the internal space 110 of the first rectangular waveguide 11 is the TEX0 mode (where X is an integer satisfying X≧1). When the dimension of the internal space 110 of the first rectangular waveguide 11 in the normal direction (Z-axis direction) of the E-plane P1 of the first rectangular waveguide 11 is L1, the first slot 111 is formed such that the distance D1 from the E-plane P1 in the normal direction is n×L1 / X (where n is an integer satisfying 0≦n≦X), and it is parallel to the E-plane P1.

[0085] With the above configuration, when foreign matter is mixed in with the object to be heated SH1, the first rectangular waveguide 11 heats the object to be heated SH1 in a magnetic field, thereby efficiently oxidizing the foreign matter or carbonizing the dielectric material surrounding the foreign matter. As a result, the heating system 100 of Embodiment 1 has the advantage that when foreign matter is mixed in with the object to be heated SH1, it is easier to detect the foreign matter.

[0086] In the heating system 100 of Embodiment 1, the object to be heated SH1 is in the form of a sheet. The object to be heated SH1 is inserted into the first rectangular waveguide 11, and a first slot 111 is formed in which the object to be heated SH1 passes to a first predetermined position PO1 in the internal space 110. The waveguide mode of the first microwave transmitted in the internal space 110 of the first rectangular waveguide 11 is the TEX0Z mode (where X is an integer satisfying X≧1 and Z is an integer satisfying Z≧1). When the dimension of the internal space 110 of the first rectangular waveguide 11 in the normal direction (z-axis direction) of the E-plane P1 of the first rectangular waveguide 11 is L1, the first slot 111 is formed such that the distance D1 from the E-plane P1 in the normal direction is n×L1 / X (where n is an integer satisfying 0≦n≦X) and is parallel to the E-plane P1.

[0087] With the above configuration, when foreign matter is mixed in with the object to be heated SH1, the first rectangular waveguide 11 heats the object to be heated SH1 in a magnetic field, thereby efficiently oxidizing the foreign matter or carbonizing the dielectric material surrounding the foreign matter. As a result, the heating system 100 of Embodiment 1 has the advantage that when foreign matter is mixed in with the object to be heated SH1, it is easier to detect the foreign matter.

[0088] In the heating system 100 of Embodiment 1, the first supply unit 12 has an oscillation unit 121 that oscillates a first microwave supplied to the first rectangular waveguide 11 and can change the frequency of the first microwave within a predetermined frequency band. The heating system 100 of Embodiment 1 further includes an oscillation control unit 132 that controls the oscillation unit 121. When the first microwave resonates in the guiding direction in which the first rectangular waveguide 11 guides the first microwave, the oscillation control unit 132 causes the oscillation unit 121 to perform a frequency sweep within a predetermined frequency band, thereby moving the positions of the antinodes and nodes of the standing waves formed in the internal space 110 of the first rectangular waveguide 11 in the guiding direction.

[0089] With the above configuration, the first rectangular waveguide 11 can move the portion of the object SH1 that is heated more strongly by the magnetic field in the direction in which it guides the first microwave. In other words, the first rectangular waveguide 11 can uniformly heat the object SH1 by the magnetic field. Therefore, there is an advantage in that the accuracy of detecting foreign matter when it is mixed in with the object SH1 is improved.

[0090] The heating system 100 of Embodiment 1 further includes at least one of a visible light camera, an infrared sensor, a temperature sensor, and a radio wave sensor for detecting a material to be detected, which is at least one of a conductive material, a magnetic material, and a semiconductor contained in the object to be heated SH1 that has been subjected to magnetic field heating.

[0091] The above configuration has the advantage of being able to detect foreign matter with high accuracy when it is mixed in with the heated object SH1.

[0092] In the heating system 100 of Embodiment 1, the heating unit X1 is a second rectangular waveguide 21, which is a rectangular waveguide different from the first rectangular waveguide 11 of the first heating device 1. The second rectangular waveguide 21 guides a second microwave, which is different from the first microwave guided by the first rectangular waveguide 11, and performs electric field heating when the object to be heated SH1 passes through a second predetermined position PO2 in the internal space 210. The heating system 100 of Embodiment 1 further comprises a second supply unit 22. The second supply unit 22 supplies the second microwave to the second rectangular waveguide 21 such that the electric field strength of the second microwave is maximized or at its maximum at the second predetermined position PO2 through which the object to be heated SH1 passes in the internal space 210 of the second rectangular waveguide 21.

[0093] The above configuration has the advantage that the dielectric of the object to be heated SH1 can be heated by electric field. Furthermore, the heating system 100 of Embodiment 1 has the advantage that, because the first rectangular waveguide 11 heats the object to be heated SH1 in a magnetic field, the foreign matter is in an oxidized state, or the dielectric surrounding the foreign matter is carbonized, so when the object to be heated SH1 is heated by electric field, the occurrence of discharge in the internal space 210 of the second rectangular waveguide 21 can be suppressed. As a result, even when foreign matter is mixed in the object to be heated SH1, the dielectric of the object to be heated SH1 can be heated while suppressing the occurrence of discharge.

[0094] In the heating system 100 of Embodiment 1, the second supply unit 22 supplies the second microwave to the second rectangular waveguide 21 such that the magnetic field strength of the second microwave is minimized or reduced to the minimum at a second predetermined position PO2 through which the object to be heated SH1 passes in the internal space 210 of the second rectangular waveguide 21.

[0095] The above configuration has the advantage of allowing the dielectric material of the object to be heated SH1 to be heated more efficiently by electric field heating.

[0096] In the heating system 100 of Embodiment 1, the object to be heated SH1 is in the form of a sheet. The object to be heated SH1 is inserted into the second rectangular waveguide 21, and a second slot 211 is formed in the second rectangular waveguide 21 to allow the object to be heated SH1 to pass through to a second predetermined position PO2 in the internal space 210. The waveguide mode of the second microwave transmitted in the internal space 210 of the second rectangular waveguide 21 is the TEX0 mode (where X is an integer satisfying X≧1). When the dimension of the internal space 210 of the second rectangular waveguide 21 in the normal direction (Z-axis direction) of the E-plane P2 of the second rectangular waveguide 21 is L2, the second slot 211 is formed such that the distance D2 from the E-plane P2 in the normal direction is (2m-1) × L2 / 2X (where m is an integer satisfying 1≦m≦X), and it is parallel to the E-plane P2.

[0097] The above configuration has the advantage that the second rectangular waveguide 21 can efficiently perform electric field heating on the object SH1 to be heated.

[0098] In the heating system 100 of Embodiment 1, the object to be heated SH1 is in the form of a sheet. The object to be heated SH1 is inserted into the second rectangular waveguide 21, and a second slot 211 is formed in the second rectangular waveguide 210 that allows the object to be heated SH1 to pass through to a second predetermined position PO2 in the internal space 210. The waveguide mode of the second microwave transmitted in the internal space 210 of the second rectangular waveguide 21 is the TEX0Z mode (where X is an integer satisfying X≧1 and Z is an integer satisfying Z≧1). When the dimension of the internal space 110 of the second rectangular waveguide 21 in the direction normal to the E-plane P2 of the second rectangular waveguide 21 (in the Z-axis direction) is L2, the second slot 211 is formed such that the distance D2 from the E-plane P2 in the normal direction is (2m-1) × L2 / 2X (where m is an integer satisfying 1≦m≦X) and is parallel to the E-plane P2.

[0099] The above configuration has the advantage that the second rectangular waveguide 21 can efficiently perform electric field heating on the object SH1 to be heated.

[0100] In the heating system 100 of Embodiment 1, the second supply unit 22 has an oscillation unit 221 that oscillates a second microwave supplied to the second rectangular waveguide 21 and can change the frequency of the second microwave within a predetermined frequency band. The heating system 100 of Embodiment 1 further includes an oscillation control unit 232 that controls the oscillation unit 221. When the second microwave resonates in the guiding direction in which the second rectangular waveguide 21 guides the second microwave, the oscillation control unit 232 causes the oscillation unit 221 to perform a frequency sweep within a predetermined frequency band, thereby moving the positions of the antinodes and nodes of the standing waves formed in the internal space 210 of the second rectangular waveguide 21 in the guiding direction.

[0101] With the above configuration, the second rectangular waveguide 21 can move the portion of the object SH1 that is strongly electric-heated compared to other parts in the direction in which it guides the second microwave. In other words, the second rectangular waveguide 21 has the advantage of being able to uniformly electric-heat the object SH1.

[0102] The heating system 100 of Embodiment 1 further includes at least one of a visible light camera, an infrared sensor, a temperature sensor, and a radio wave sensor for detecting a material to be detected, which is at least one of a conductive material, a magnetic material, and a semiconductor contained in the object to be heated SH1 that has been subjected to magnetic field heating. The heating system 100 further includes a supply control unit 231 that controls the second supply unit 22. When the material to be detected is detected by the foreign object inspection device 3, the supply control unit 231 controls the second supply unit 22 to temporarily stop the supply of the second microwave when the material to be detected passes through a second predetermined position PO2 in the internal space 210 of the second rectangular waveguide 21.

[0103] The above configuration has the effect of suppressing the electric field heating of foreign matter when it is mixed in with the object to be heated SH1. As a result, there is the advantage that the concentration of the electric field on the foreign matter can be further suppressed. In other words, discharge generation can be suppressed when foreign matter is mixed in with the object to be heated SH1.

[0104] In the heating system 100 of Embodiment 1, the object to be heated SH1 is in the form of a sheet. The object to be heated SH1 is inserted into the first rectangular waveguide 11, and a first slot 111 is formed therein that allows the object to be heated SH1 to pass through to a first predetermined position PO1 in the internal space 110. The object to be heated SH1 is inserted into the second rectangular waveguide 21, and a second slot 211 is formed therein that allows the object to be heated SH1 to pass through to a second predetermined position PO2 in the internal space 210. The heating system 100 of Embodiment 1 includes a conveying device 4 that conveys the object to be heated SH1 in a roll-to-roll manner and sequentially passes the object to be heated through the first slot 111 and the second slot 211, respectively.

[0105] With the above configuration, the material to be heated SH1 is continuously supplied to each of the first rectangular waveguide 11 and the second rectangular waveguide 21. This has the advantage that if foreign matter is mixed in with the material to be heated SH1, the foreign matter can be continuously detected.

[0106] (1-5) 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 descriptions are omitted.

[0107] (1-5-1) First Modification of Embodiment 1 In the first rectangular waveguide 11 of the first heating device 1 of the heating system 100 in Embodiment 1 described above, the dimension in the Z-axis direction is larger than the dimension in the Y-axis direction. However, in the first rectangular waveguide 11A of the first heating device 1A of the heating system 100A in the first modification shown in Figure 6, the dimension in the Z-axis direction may be smaller than the dimension in the Y-axis direction. The object to be heated SH1 passes through the internal space 110 of the first rectangular waveguide 11A along the transport direction A1 (i.e., the Y-axis direction).

[0108] Assume that a reflectionless terminator is attached to one of the two ends in the X-axis direction of the internal space 110 of the first rectangular waveguide 11. In this case, as shown in Figure 6, the waveguide mode of the first microwave transmitted through the internal space 110 of the first rectangular waveguide 11A is the TE0X mode (where X is an integer satisfying X≧1) so that the magnetic field strength of the first microwave is maximum or maximal at the first predetermined position PO1 through which the object to be heated SH1 passes. That is, the electric field lines of the first microwave transmitted through the internal space 110 of the first rectangular waveguide 11A are parallel to the longitudinal direction of the first rectangular waveguide 11A when viewed from the X-axis direction. Figure 6 illustrates the case where the waveguide mode of the first microwave is the TE02 mode (i.e., X=2) as an example.

[0109] Next, consider the case where a variable shorting plate 14 is movably attached along the X-axis direction to one of the two ends in the X-axis direction of the internal space 110 of the first rectangular waveguide 11. In this case, depending on the position of the variable shorting plate 14 in the X-axis direction within the internal space 110, the first microwave transmitted through the internal space 110 of the first rectangular waveguide 11A forms a standing wave and resonates in the direction in which the first rectangular waveguide 11A guides the first microwave (the longitudinal direction of the first rectangular waveguide 11A, i.e., the X-axis direction). As an example, in the internal space 110, if the distance in the X-axis direction from the end of the two ends in the X-axis direction to the variable shorting plate 14 is an integer multiple of the half wavelength of the first microwave within the waveguide, the first microwave resonates in the X-axis direction. When the first microwave resonates in the above-mentioned waveguide direction, the waveguide mode of the first microwave is the TE0XZ mode (where X is an integer satisfying X≧1 and Z is an integer satisfying Z≧1).

[0110] When L1 is the dimension of the internal space 110 of the first rectangular waveguide 11A in the direction normal to the E-plane P1 of the first rectangular waveguide 11A (in the z-axis direction), the first slot 111 is formed such that the distance D3 from the E-plane P1 in the normal direction is n × L1 / X (where n is an integer satisfying 0 ≤ n ≤ X) and it is parallel to the E-plane P1. As shown in Figure 6, when the waveguide mode of the first microwave is the TE02 mode (i.e., X = 2), the first slot 111 is formed such that the distance D3 from the E-plane P1 in the normal direction is L1 / 2 (n = 1) and it is parallel to the E-plane P1. With this configuration, the first rectangular waveguide 11A can efficiently perform magnetic field heating on the object SH1 to be heated. As a result, when foreign matter is mixed in with the object to be heated SH1, the first rectangular waveguide 11A efficiently oxidizes the foreign matter or carbonizes the dielectric material surrounding the foreign matter by magnetically heating the object to be heated SH1. As a result, the heating system 100 of Embodiment 1 has the advantage that it is easier to detect foreign matter when it is mixed in with the object to be heated SH1.

[0111] Similarly, in the second rectangular waveguide 21 of the second heating device 2 of the heating system 100 in the embodiment 1 described above, the dimension in the Z-axis direction is larger than the dimension in the Y-axis direction. However, as shown in Figure 7, in the second rectangular waveguide 21A of the second heating device 2A of the heating system 100A in the first modified example, the dimension in the Z-axis direction may be smaller than the dimension in the Y-axis direction. The object to be heated SH1 passes through the internal space 210 of the second rectangular waveguide 21A along the transport direction A1 (i.e., the Y-axis direction).

[0112] Let's assume that a reflectionless terminator is attached to one of the two ends in the X-axis direction of the internal space 210 of the second rectangular waveguide 21. In this case, as shown in Figure 7, the waveguide mode of the second microwave transmitted through the internal space 210 of the second rectangular waveguide 21A is the TE0X mode (where X is an integer satisfying X≧1) so that the electric field strength of the second microwave is maximum or maximal at the second predetermined position PO2 through which the object to be heated SH1 passes. That is, the electric field lines of the second microwave transmitted through the internal space 210 of the second rectangular waveguide 21A are parallel to the longitudinal direction of the second rectangular waveguide 21A when viewed from the X-axis direction. Figure 7 illustrates the case where the waveguide mode of the second microwave is the TE01 mode (i.e., when X=1) as an example.

[0113] Next, consider the case where a variable shorting plate 24 is movably mounted along the X-axis direction at one of the two ends of the internal space 210 of the second rectangular waveguide 21. In this case, depending on the position of the variable shorting plate 24 in the X-axis direction within the internal space 210, the second microwave transmitted through the internal space 210 of the second rectangular waveguide 21A forms a standing wave and resonates in the direction in which the second rectangular waveguide 21A guides the second microwave (the longitudinal direction of the second rectangular waveguide 21A, i.e., the X-axis direction). As an example, in the internal space 210, if the distance in the X-axis direction from the end of the two ends in the X-axis direction to the variable shorting plate 24 is an integer multiple of the half wavelength of the second microwave within the waveguide, the second microwave resonates in the X-axis direction. When the second microwave resonates in the above waveguide direction, the waveguide mode of the second microwave is the TE0XZ mode (where X is an integer satisfying X≧1 and Z is an integer satisfying Z≧1).

[0114] When the dimension of the internal space 210 of the second rectangular waveguide 21A in the normal direction (Z-axis direction) of the E-plane P2 of the second rectangular waveguide 21A is L2, the second slot 211 is formed such that the distance D4 from the E-plane P2 in the normal direction is (2m-1) × L2 / 2X (where m is an integer satisfying 1 ≤ m ≤ X) and it is parallel to the E-plane P2. As shown in Figure 7, when the waveguide mode of the second microwave is the TE01 mode (i.e., X=1), the second slot 211 is formed such that the distance D4 from the E-plane P2 in the normal direction is L2 / 2 (m=1) and it is parallel to the E-plane P2. This configuration has the advantage that the second rectangular waveguide 21A can efficiently perform electric field heating on the object SH1 to be heated.

[0115] (1-5-2) Second Modified Example of Embodiment 1 In the heating system 100B in the second modified example shown in Figure 8, the first rectangular waveguide 11B of the first heating device 1B has a first choke structure 19 that suppresses leakage of first microwaves from the first slot 111. Similarly, the second rectangular waveguide 21B of the second heating device 2B has a second choke structure 29 that suppresses leakage of second microwaves from the second slot 211. With this configuration, the amount of first microwaves guided through the internal space 110 of the first rectangular waveguide 11B increases, and the amount of second microwaves guided through the internal space 210 of the second rectangular waveguide 21B increases. As a result, the first rectangular waveguide 11B can efficiently perform magnetic field heating on the object to be heated SH1, and the second rectangular waveguide 21B can efficiently perform electric field heating on the object to be heated SH1, which is an advantage.

[0116] More specifically, the first rectangular waveguide 11B has two first choke structures 19. The two first choke structures 19 are attached to the first slot 111. More specifically, one of the two first choke structures 19 is attached to the side (front side) in the first slot 111 where the object to be heated SH1 is inserted, and the other first choke structure 19 is attached to the side (rear side) in the first slot 111 from which the object to be heated SH1 is removed.

[0117] Similarly, the second rectangular waveguide 21B has two second choke structures 29. The two second choke structures 29 are attached to the second slot 211. More specifically, one of the two second choke structures 29 is attached to the inlet (front side) of the second slot 211, and the other second choke structure 29 is attached to the outlet (rear side) of the second slot 211.

[0118] Each of the two first choke structures 19 and the two second choke structures 29 is a so-called λ / 4 choke structure. Note that each of the two first choke structures 19 and the two second 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 first choke structures 19 may have radio wave absorbing material provided at the inlet and outlet of the first slot 111. Similarly, the two second choke structures 29 may have radio wave absorbing material provided at the inlet and outlet of the second slot 211.

[0119] (1-5-3) Third Modification of Embodiment 1 In the heating system 100 in Embodiment 1 described above, the first heating device 1 has one first rectangular waveguide 11, and the second heating device 2 has one second rectangular waveguide 21. However, in the heating system 100C in the third modification shown in Figure 9, the first heating device 1C has a plurality (three in the figure) of first rectangular waveguides 11C, and the second heating device 2C has a plurality (three in the figure) of second rectangular waveguides 21C.

[0120] In the heating system 100C of the third modified example, one first supply unit 12 supplies first microwaves to each of the plurality of first rectangular waveguides 11C. The first heating device 1C may have a plurality of first supply units 12. In this case, the plurality of first supply units 12 may correspond one-to-one with the plurality of first rectangular waveguides 11C, and supply first microwaves to the corresponding first rectangular waveguide 11 among the plurality of first rectangular waveguides 11C.

[0121] Similarly, in the heating system 100C of the third modified example, one second supply unit 22 supplies the second microwave to each of the multiple second rectangular waveguides 21C. The second heating device 2C may have multiple second supply units 22. In this case, the multiple second supply units 22 may correspond one-to-one with the multiple second rectangular waveguides 21C, and the second microwave may be supplied to the corresponding second rectangular waveguide 21 among the multiple second rectangular waveguides 21C.

[0122] (1-5-4) Other Modifications of Embodiment 1 The following lists other modifications of the above-described embodiment.

[0123] In the above-described embodiment 1, the heating unit X1 is a second rectangular waveguide 21 that electric-field heats the dielectric of the object to be heated SH1, which has been magnetically heated by the first rectangular waveguide 11. However, the heating unit X1 may also be a heating device that heats the dielectric of the object to be heated SH1, which has been magnetically heated by the first rectangular waveguide 11, by a method different from magnetic field heating and electric field heating.

[0124] When microwaves of the same frequency are used as the first microwave transmitted through the first rectangular waveguide 11 and the second microwave transmitted through the second rectangular waveguide 21, the first supply unit 12 and the second supply unit 22 may be the same supply unit. That is, in the above case, the first supply unit 12 may also function as the second supply unit 22 and supply the second microwave to the second rectangular waveguide 21.

[0125] (2) Embodiment 2 (2-1) Overview Below, an overview of the heating system 100D according to Embodiment 2 will be described with reference to Figure 10. Components similar to those in Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted.

[0126] In the heating system 100 of Embodiment 1, the first rectangular waveguide 11 of the first heating device 1 is rectangular when viewed from the Z-axis direction. On the other hand, as shown in Figure 10, in the heating system 100D of Embodiment 2, the first rectangular waveguide 11D of the first heating device 1D is bent in a zigzag pattern when viewed from the Z-axis direction.

[0127] Similarly, in the heating system 100 of Embodiment 1, the second rectangular waveguide 21 of the second heating device 2 is rectangular when viewed from the Z-axis direction. On the other hand, as shown in Figure 10, in the heating system 100D of Embodiment 2, the second rectangular waveguide 21D of the second heating device 2D is bent in a zigzag pattern when viewed from the Z-axis direction.

[0128] In short, the first rectangular waveguide 11D and the second rectangular waveguide 21D in the heating system 100D of Embodiment 2 differ from the first rectangular waveguide 11 and the second rectangular waveguide 21 in the heating system 100 of Embodiment 1 in that each of them is bent in a zigzag pattern when viewed from the Z-axis direction.

[0129] (2-2) Detailed Configuration (2-2-1) Overall The detailed configuration of the heating system 100D of Embodiment 2 will be described below with reference to Figures 10 to 15.

[0130] The heating system 100D of Embodiment 2, as shown in Figure 10, comprises a first heating device 1D, a second heating device 2D, a foreign object inspection device 3 (see Figure 1), and a conveying device 4 (see Figure 1). Note that the foreign object inspection device 3 and conveying device 4 of Embodiment 2 have the same configuration as those of Embodiment 1, so a detailed explanation is omitted.

[0131] (2-2-2) First Heating Device The first heating device 1D is a magnetic field heating furnace that uses first microwaves to heat the object to be heated SH1 in a magnetic field. As shown in Figure 10, the first heating device 1D includes a first rectangular waveguide 11D, a first supply unit 12 (see Figure 1), a control unit 13 (see Figure 1), a variable shorting plate 14 (see Figure 1), and a temperature monitor 15 (see Figure 1). The first heating device 1D may have a non-reflection terminator instead of the variable shorting plate 14. Furthermore, the first supply unit 12, control unit 13, variable shorting plate 14, temperature monitor 15, and non-reflection terminator in Embodiment 2 have the same configuration as the first supply unit 12, control unit 13, variable shorting plate 14, temperature monitor 15, and non-reflection terminator in Embodiment 1, so a detailed explanation is omitted.

[0132] (First Rectangular Waveguide) The first rectangular waveguide 11D guides (transmits) first microwaves that perform magnetic field heating as the object to be heated SH1 passes through the first predetermined position PO1 in the internal space 110. The first rectangular waveguide 11D in Embodiment 1 is a rectangular waveguide with a rectangular cross-sectional shape. In the following description, the same configuration as the first rectangular waveguide 11 in Embodiment 1 will be omitted as appropriate.

[0133] As shown in Figure 10, the first rectangular waveguide 11D is bent in a zigzag pattern in multiple stages (five stages) when viewed from the Z-axis direction. In this disclosure, "zigzag pattern" means that multiple straight sections are aligned along the Y-axis direction, and focusing on the first, second, and third straight sections which are aligned consecutively, 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.

[0134] As shown in Figure 11, in the simulation of the magnetic field distribution at the center position in the Z-axis direction of the first rectangular waveguide 11D, a first magnetic field region RM1 where the magnetic field strength is near its maximum value and a second magnetic field region RM2 where the magnetic field strength is near its minimum value appear alternately along the guiding direction in which the first rectangular waveguide 11D guides the first microwave (i.e., the longitudinal direction of the first rectangular waveguide 11D). In other words, in the first rectangular waveguide 11D, there is a first magnetic field region RM1 where the magnetic field strength is near its maximum value at the center position in the Z-axis direction, i.e., at the first predetermined position PO1 through which the object to be heated SH1 passes.

[0135] On the other hand, as shown in Figure 12, in the simulation of the electric field distribution at the center position in the Z-axis direction of the first rectangular waveguide 11D, a second electric field region RE2, where the electric field strength is near a minimum or minimum value, appears continuously along the waveguide direction in which the first rectangular waveguide 11D guides the first microwave. That is, in the first rectangular waveguide 11D, the electric field strength is near a minimum or minimum value at the center position in the Z-axis direction, i.e., at the first predetermined position PO1 through which the object to be heated SH1 passes.

[0136] (Second Rectangular Waveguide) The second rectangular waveguide 21D guides (transmits) a first microwave that performs magnetic field heating as the object to be heated SH1 passes through a first predetermined position PO1 in the internal space 210. The heating section X1 of Embodiment 2 is the second rectangular waveguide 21D, which is a rectangular waveguide different from the first rectangular waveguide 11D of the first heating device 1D. That is, the heating section X1 of Embodiment 2 is the second rectangular waveguide 21D that performs electric field heating of the dielectric of the object to be heated SH1 after magnetic field heating has been performed by the first rectangular waveguide 11D. The second microwave guided by the second rectangular waveguide 21D is a different microwave from the first microwave guided by the first rectangular waveguide 11D. The second rectangular waveguide 21D of Embodiment 2 is a rectangular waveguide with a rectangular cross-sectional shape. In the following description, explanations of configurations similar to those of the second rectangular waveguide 21 in Embodiment 1 will be omitted as appropriate.

[0137] As shown in Figure 10, the second rectangular waveguide 21D is bent in a zigzag pattern in multiple stages (5 stages) when viewed from the Z-axis direction.

[0138] As shown in Figure 13, in the simulation of the magnetic field distribution at the center position in the Z-axis direction of the second rectangular waveguide 21D, a second magnetic field region RM2, where the magnetic field strength is near a minimum or minimum value, appears continuously along the waveguide direction in which the second rectangular waveguide 21D guides the first microwave (i.e., the longitudinal direction of the second rectangular waveguide 21D). In other words, in the second rectangular waveguide 21D, the magnetic field strength is near a minimum or minimum value at the center position in the Z-axis direction, i.e., at the second predetermined position PO2 through which the object to be heated SH1 passes.

[0139] On the other hand, as shown in Figure 14, in the simulation of the electric field distribution at the center position in the Z-axis direction of the second rectangular waveguide 21D, a first electric field region RE1 where the electric field strength is near its maximum value and a second electric field region RE2 where the electric field strength is near its minimum value appear alternately along the guidance direction in which the second rectangular waveguide 21D guides the first microwave. That is, in the first rectangular waveguide 11D, there is a first electric field region RE1 where the electric field strength is near its maximum value at the center position in the Z-axis direction, i.e., at the second predetermined position PO2 through which the object to be heated SH1 passes.

[0140] Here, we focus on the simulation of the magnetic field distribution at the center position in the Z-axis direction when a foreign object F1 (see Figure 15) is present in the comparative example rectangular waveguide EX21.

[0141] As shown in Figure 15, in the simulation of the electric field distribution in the comparative example's rectangular waveguide EX21 in the above case, a first electric field region RE1 where the electric field strength is near its maximum value and a second electric field region RE2 where the electric field strength is near its minimum value appear alternately along the guidance direction in which the comparative example's rectangular waveguide EX21 guides the first microwave, up to the location where the foreign object F1 is present. However, beyond the location where the foreign object F1 is present in the above guidance direction, a third electric field region RE3 where the electric field strength is near its minimum value appears continuously. In other words, in the comparative example's rectangular waveguide EX21, the presence of the foreign object F1 causes a large change in the electric field distribution in the internal space of the rectangular waveguide EX21 when the dielectric of the object to be heated SH1 is heated by electric field.

[0142] On the other hand, in the heating system 100D of Embodiment 2, the second rectangular waveguide 21D heats the dielectric of the object to be heated SH1 after it has been heated by the magnetic field of the first rectangular waveguide 11D using an electric field. That is, the second rectangular waveguide 21D heats the dielectric of the object to be heated SH1 after the foreign matter has been oxidized by the magnetic field heating of the object to be heated SH1 by the first rectangular waveguide 11 using an electric field. Therefore, in the heating system 100D of Embodiment 2, when the second rectangular waveguide 21D heats the dielectric of the object to be heated SH1 using an electric field, it is possible to suppress a large change in the electric field distribution in the internal space 210 of the second rectangular waveguide 21D.

[0143] (2-3) Modifications of Embodiment 2 Embodiment 2 described above is merely 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 in combination as appropriate. Furthermore, the following modifications may be implemented in combination with Embodiment 1 described above, or a modification of Embodiment 1 described above. Components similar to those in Embodiment 2 described above are denoted by the same reference numerals and their description is omitted.

[0144] (2-3-1) First Modification of Embodiment 2 In the heating system 100D of Embodiment 2 described above, the first rectangular waveguide 11D of the first heating device 1D and the second rectangular waveguide 21D of the second heating device 2D are each bent in a zigzag pattern when viewed from the Z-axis direction. On the other hand, in the heating system 100E of the first modification of Embodiment 2 shown in Figure 16, the first rectangular waveguide 11E of the first heating device 1E is rectangular when viewed from the Z-axis direction, and the second rectangular waveguide 21E of the second heating device 2E is bent in a zigzag pattern when viewed from the Z-axis direction.

[0145] Furthermore, in the first modified heating system 100E of Embodiment 2, the first rectangular waveguide 11E of the first heating device 1E is bent in a zigzag pattern when viewed from the Z-axis direction, and the second rectangular waveguide 21E of the second heating device 2E may be rectangular when viewed from the Z-axis direction.

[0146] (2-3-2) Second Modification of Embodiment 2 In the heating system 100 in Embodiment 1 described above, and the heating system 100D in Embodiment 2 described above, the second slot 211 is formed such that the distance D2 from the E-plane P2 in the normal direction is (2m-1) × L2 / 2X (where m is an integer satisfying 1 ≤ m ≤ X), and it is parallel to the E-plane P2. Figure 4 illustrates, as an example, the case in which the waveguide mode of the second microwave is the TE10 mode (i.e., X=1), and the second slot 211 is formed such that the distance D2 from the E-plane P2 in the normal direction is L2 / 2 (m=1), and it is parallel to the E-plane P2. On the other hand, in the heating system 100F in the second modification of Embodiment 2 shown in Figure 17, the second slot 211 of the second rectangular waveguide 21F of the second heating device 2F is formed at a position where the distance D5 from the E-plane P2 in the normal direction is different from L2 / 2 (m=1).

[0147] More specifically, as shown in Figure 17, when the waveguide mode of the second microwave is the TE20 mode (i.e., X = 2), the second slot 211 is formed such that the distance D5 from the E-plane P2 in the normal direction is 3 × L² / 4 (m = 2) and it is parallel to the E-plane P2.

[0148] Furthermore, as shown in the heating system 100G in Figure 18, the second rectangular waveguide 21G of the second heating device 2G may be provided with two second slots 211a and 211b. When the waveguide mode of the second microwave is the TE20 mode (i.e., X = 2), one of the two second slots 211a and 211b, the second slot 211a, is formed such that the distance D5 from the E-plane P2 in the normal direction is 3 × L2 / 4 (m = 2) and it is parallel to the E-plane P2. On the other hand, the remaining second slot 211b is formed such that the distance D6 from the E-plane P2 in the normal direction is L2 / 4 (m = 1) and it is parallel to the E-plane P2.

[0149] In other words, there may be multiple second slots 211. Similarly, the first rectangular waveguide 11 of the first heating device 1 may be provided with two first slots 111. In other words, there may be multiple first slots 111. Note that either the first slot 111 or the second slot 211 may be multiple, or both the first slot 111 and the second slot 211 may be multiple. That is, at least one of the first slot 111 and the second slot 211 may be multiple. This configuration has the effect of simultaneously heating multiple objects SH1 in at least one of the first heating device 1 and the second heating device 2. As a result, there is the advantage of reducing the space required to install the heating system 100G and efficiently heating the objects SH1.

[0150] (2-3-3) Third Modification of Embodiment 2 In the heating system 100H in the third modification of Embodiment 2 shown in Figure 19, when the waveguide mode of the second microwave is the TE20 mode (i.e., X = 2), the second rectangular waveguide 21H of the second heating device 2H is provided with three second slots 211a, 211b, and 211c.

[0151] The second slot 211a is formed such that its distance D5 from the E-plane P2 in the normal direction is 3 × L² / 4 (m = 2) and it is parallel to the E-plane P2. On the other hand, the remaining second slot 211b is formed such that its distance D6 from the E-plane P2 in the normal direction is L² / 4 (m = 1) and it is parallel to the E-plane P2. Therefore, when using the second rectangular waveguide 21H to heat the object to be heated SH1 with an electric field, the object to be heated SH1 is passed through either the second slot 211a or the second slot 211b.

[0152] On the other hand, the second slot 211c is formed such that the distance D7 from the E-plane P2 in the normal direction is L2 / 2 (m=1) and it is parallel to the E-plane P2. Therefore, when the second rectangular waveguide 21H is used to heat the object to be heated SH1 by changing the waveguide mode of the second microwave to TE10 mode, the object to be heated SH1 is passed through the second slot 211c.

[0153] Furthermore, when the waveguide mode of the second microwave is the TE20 mode, the object to be heated SH1 can be heated by magnetic field heating by passing it through the second slot 211c. In other words, when heating the object to be heated SH1 with a magnetic field, the second rectangular waveguide 21H can be repurposed without changing its shape.

[0154] (Summary) The heating system of the first embodiment (100, 100A to 100H) comprises a rectangular waveguide (11, 11A to 11E), a supply unit (12), and a heating unit (X1). The rectangular waveguide (11, 11A to 11E) guides microwaves that perform magnetic field heating as the object to be heated (SH1) containing a dielectric passes through a predetermined position (PO1) in the internal space (110). The supply unit (12) supplies microwaves to the rectangular waveguide (11, 11A to 11E) so that the magnetic field strength of the microwaves is maximum or at its maximum at the predetermined position (PO1). The heating unit (X1) heats the dielectric of the object to be heated (SH1) that has been magnetically heated by a method different from magnetic field heating.

[0155] This embodiment has the advantage that, if foreign matter is mixed into the object to be heated (SH1), the foreign matter can be easily detected.

[0156] In the heating system of the second embodiment (100, 100A to 100H), in the first embodiment, the supply unit (12) supplies microwaves to the rectangular waveguides (11, 11A to 11E) such that the microwave field strength at a predetermined position (PO1) is minimal or zero.

[0157] This embodiment has the advantage that it can suppress the occurrence of discharge in the internal space (210) of the second rectangular waveguide (21) when the object to be heated (SH1) is microwave-heated by the heating unit (X1).

[0158] In the third embodiment of the heating system (100, 100A to 100H), the object to be heated (SH1) is in the form of a sheet, as in the first or second embodiment. The object to be heated (SH1) is inserted into the rectangular waveguide (11, 11A to 11E), and a slot (111) is formed in which the object to be heated (SH1) passes to a predetermined position (PO1). The waveguide mode of the microwaves transmitted in the internal space (110) of the rectangular waveguide (11, 11A to 11E) is the TEX0 mode or the TE0X mode (where X is an integer satisfying X≧1). When L is the dimension of the internal space (110) of the rectangular waveguide (11, 11A to 11E) in the direction normal to the E-plane (P1) of the rectangular waveguide (11, 11A to 11E), the slot (111) is formed such that its distance (D1, D3, D7) from the E-plane (P1) in the normal direction is n × L / X (where n is an integer satisfying 0 ≤ n ≤ X) and it is parallel to the E-plane (P1).

[0159] This embodiment has the advantage that, if foreign matter is mixed into the object being heated (SH1), it can be detected more easily.

[0160] In the fourth embodiment of the heating system (100, 100A to 100H), the object to be heated (SH1) is in the form of a sheet, as in the first or second embodiment. The object to be heated (SH1) is inserted into the rectangular waveguide (11, 11A to 11E), and a slot (111) is formed in which the object to be heated (SH1) passes to a predetermined position (PO1). The waveguide mode of the microwaves transmitted in the internal space (110) of the rectangular waveguide (11, 11A to 11E) is the TEX0Z mode or the TE0XZ mode (where X is an integer satisfying X≧1 and Z is an integer satisfying Z≧1). When L is the dimension of the internal space (110) of the rectangular waveguide (11, 11A to 11E) in the direction normal to the E-plane (P1) of the rectangular waveguide (11, 11A to 11E), the slot (111) is formed such that its distance (D1, D3, D7) from the E-plane (P1) in the normal direction is n × L / X (where n is an integer satisfying 0 ≤ n ≤ X) and it is parallel to the E-plane (P1).

[0161] This embodiment has the advantage that, if foreign matter is mixed into the object being heated (SH1), it can be detected more easily.

[0162] In the fifth embodiment of the heating system (100, 100A to 100H), in the fourth embodiment, the supply unit (12) has an oscillator (121) that oscillates microwaves and can change the frequency of the microwaves within a predetermined frequency band. The fifth embodiment of the heating system (100, 100A to 100H) further comprises an oscillator control unit (132) that controls the oscillator (121). The oscillator control unit (132) causes the oscillator (121) to perform a frequency sweep within a predetermined frequency band, thereby moving the positions of the antinodes and nodes of the standing waves formed in the internal space (110) of the rectangular waveguides (11, 11A to 11E) in the guiding direction in which the rectangular waveguides (11, 11A to 11E) guide microwaves.

[0163] This embodiment has the advantage of being able to improve the accuracy of detecting foreign matter when it is mixed in with the heated object (SH1).

[0164] The sixth heating system (100, 100A to 100H) further comprises, in any one of the first to fifth embodiments, at least one of a visible light camera, an infrared sensor, a temperature sensor, and a radio wave sensor for detecting a material to be detected, which is at least one of a conductive material, a magnetic material, and a semiconductor contained in the object to be heated (SH1) that has been subjected to magnetic field heating.

[0165] This embodiment has the advantage of being able to improve the accuracy of detecting foreign matter when it is mixed in with the heated object (SH1).

[0166] In the seventh embodiment of the heating system (100, 100A to 100H), in any one of the first to sixth embodiments, the heating section (X1) is a second rectangular waveguide (21, 21A to 21H) that is different from the first rectangular waveguide (11, 11A to 11E), which is a rectangular waveguide (11, 11A to 11E). The predetermined position (PO1) of the first rectangular waveguide (11, 11A to 11E) is the first predetermined position (PO1). The second rectangular waveguide (21, 21A to 21H) guides a second microwave that is different from the first microwave, which is a microwave, and performs electric field heating when the object to be heated (SH1) passes through the second predetermined position (PO2), which is a predetermined position in the internal space (210) of the second rectangular waveguide (21, 21A to 21H). The heating system (100, 100A to 100H) of the seventh embodiment further comprises a second supply unit (22), which is different from the first supply unit (12) and supplies the second microwave to the second rectangular waveguide (21, 21A to 21H) such that the electric field strength of the second microwave is maximized or at its maximum at a second predetermined position (PO2).

[0167] This embodiment has the advantage that the dielectric of the object to be heated (SH1) can be heated by electric field.

[0168] In the heating system of the eighth embodiment (100, 100A to 100H), in the seventh embodiment, the second supply unit (22) supplies the second microwave to the second rectangular waveguide (21, 21A to 21H) such that the magnetic field strength of the second microwave is minimal or at least minimal at the second predetermined position (PO2).

[0169] This embodiment has the advantage of enabling more efficient electric field heating of the dielectric material of the object to be heated (SH1).

[0170] In the heating system of the ninth embodiment (100, 100A to 100H), the object to be heated (SH1) is in the form of a sheet, as in the seventh or eighth embodiment. The object to be heated (SH1) is inserted into the second rectangular waveguide (21, 21A to 21H), and a slot (211) is formed in which the object to be heated (SH1) passes to a second predetermined position (PO2). The waveguide mode of the second microwave transmitted in the internal space (210) of the second rectangular waveguide (21, 21A to 21H) is the TEX0 mode or the TE0X mode (where X is an integer satisfying X≧1). When L is the dimension of the internal space (210) of the second rectangular waveguide (21, 21A to 21H) in the direction normal to the E-plane (P2) of the second rectangular waveguide (21, 21A to 21H), the slot (211) is formed such that its distance (D2, D4-D6) from the E-plane (P2) in the normal direction is (2m-1) × L / 2X (where m is an integer satisfying 1 ≤ m ≤ X), and it is parallel to the E-plane (P2).

[0171] This embodiment has the advantage of enabling more efficient electric field heating of the dielectric material of the object to be heated (SH1).

[0172] In the heating system of the tenth embodiment (100, 100A to 100H), the object to be heated (SH1) is in the form of a sheet, as in the seventh or eighth embodiment. The object to be heated (SH1) is inserted into the second rectangular waveguide (21, 21A to 21H), and a slot (211) is formed in which the object to be heated (SH1) passes to a second predetermined position (PO2). The waveguide mode of the second microwave transmitted inside the second rectangular waveguide (21, 21A to 21H) is the TEX0Z mode or the TE0XZ mode (where X is an integer satisfying X≧1 and Z is an integer satisfying Z≧1). When L is the dimension of the internal space (210) of the second rectangular waveguide (21, 21A to 21H) in the direction normal to the E-plane (P2) of the second rectangular waveguide (21, 21A to 21H), the slot (211) is formed such that its distance (D2, D4-D6) from the E-plane (P2) in the normal direction is (2m-1) × L / 2X (where m is an integer satisfying 1 ≤ m ≤ X), and it is parallel to the E-plane (P2).

[0173] This embodiment has the advantage that the second rectangular waveguide (21, 21A to 21H) can efficiently perform electric field heating on the object to be heated (SH1).

[0174] In the eleventh embodiment of the heating system (100, 100A to 100H), as in the tenth embodiment, the second supply unit (22) has an oscillator (221) that oscillates a second microwave and can change the frequency of the second microwave within a predetermined frequency band. The eleventh embodiment of the heating system (100, 100A to 100H) further comprises an oscillator control unit (232) that controls the oscillator (221). The oscillator control unit (232) causes the oscillator (221) to perform a frequency sweep within a predetermined frequency band, thereby moving the positions of the antinodes and nodes of the standing waves formed in the internal space (210) of the second rectangular waveguide (21, 21A to 21H) in the guiding direction in which the second microwave is guided by the second rectangular waveguide (21, 21A to 21H).

[0175] This embodiment has the advantage that the second rectangular waveguide (21, 21A-21H) can uniformly heat the object to be heated (SH1) using an electric field.

[0176] A heating system according to the twelfth embodiment (100, 100A to 100H) further comprises, in any one of the seventh to eleventh embodiments, at least one of a visible light camera, an infrared sensor, a temperature sensor, and a radio wave sensor, and a supply control unit. At least one of the visible light camera, infrared sensor, temperature sensor, and radio wave sensor detects a material to be detected, which is at least one of a conductive material, a magnetic material, and a semiconductor, contained in the object to be heated (SH1) that has been subjected to magnetic field heating. The supply control unit controls a second supply unit (22).

[0177] According to this embodiment, there is an advantage in that when foreign matter is mixed in with the object to be heated (SH1), the concentration of the electric field on the foreign matter can be further suppressed.

[0178] In the heating system of the 13th embodiment (100, 100A to 100H), in any one embodiment of the 7th to 12th, the object to be heated (SH1) is in the form of a sheet. The object to be heated (SH1) is inserted into the first rectangular waveguide (11, 11A to 11E), and a first slot (111) is formed in which the object to be heated (SH1) passes to a first predetermined position (PO1). The object to be heated (SH1) is inserted into the second rectangular waveguide (21, 21A to 21H), and a second slot (211) is formed in which the object to be heated (SH1) passes to a second predetermined position (PO2). The heating system of the 13th embodiment (100, 100A to 100H) further comprises a conveying device that conveys the object to be heated (SH1) in a roll-to-roll manner and passes the object to be heated (SH1) sequentially through the first slot (111) and the second slot (211), respectively.

[0179] This embodiment has the advantage that, if foreign matter is mixed into the object being heated (SH1), it can be continuously detected.

[0180] In the heating system (100B) of the 14th embodiment, in the 13th embodiment, the first rectangular waveguide (11B) has a first choke structure (19) that suppresses leakage of first microwaves from the first slot (111). The second rectangular waveguide (21B) has a second choke structure (29) that suppresses leakage of second microwaves from the second slot (211).

[0181] This embodiment has the advantage that the first rectangular waveguide (11B) can efficiently perform magnetic field heating on the object to be heated (SH1), and the second rectangular waveguide (21B) can efficiently perform electric field heating on the object to be heated (SH1).

[0182] In the heating system (100G) of the 15th embodiment, in the 13th or 14th embodiment, at least one of the first slot (111) and the second slot (211) is multiple.

[0183] This embodiment has the advantage of reducing the space required to install the heating system (100G) and efficiently heating the object to be heated (SH1).

[0184] The heating method of the 16th embodiment is a heating method in which a heating system (100, 100A to 100H) according to any one of the first to 15 embodiments heats an object to be heated (SH1), and includes a first heating step (ST1) and a second heating step (ST3). In the first heating step (ST1), magnetic field heating is performed using microwaves as the object to be heated (SH1) passes through a predetermined position (110). In the second heating step (ST3), the dielectric of the object to be heated (SH1) that was magnetically heated in the first heating step (ST1) is heated by a method different from magnetic field heating. In the first heating step (ST1), microwaves are supplied to the rectangular waveguide (11, 11A to 11E) such that the magnetic field strength of the microwaves is maximum or at its maximum at the predetermined position (110).

[0185] 100, 100A-100H Heating system 11, 11A-11E First rectangular waveguide (rectangular waveguide) 110 Internal space 111 First slot (slot) 12 First supply unit (supply unit) 121 Oscillation unit 131 Supply control unit 132 Oscillation control unit 19 First choke structure 21 Second rectangular waveguide 21A-21H Second rectangular waveguide 210 Internal space 211, 211a-211c Second slot (slot) 22 Second supply unit 221 Oscillation unit 231 Supply control unit 232 Oscillation control unit 29 Second choke structure 4 Conveying device D1-D7 Distance P1, P2 E surface PO1 First predetermined position (predetermined position) PO2 Second predetermined position SH1 Object to be heated ST1 First heating step ST3 Second heating step X1 Heating section

Claims

1. A heating system comprising: a rectangular waveguide that guides microwaves to perform magnetic field heating as an object to be heated, including a dielectric, passes through a predetermined position in its internal space; a supply unit that supplies microwaves to the rectangular waveguide such that the magnetic field strength of the microwaves is maximum or extremely high at the predetermined position; and a heating unit that heats the dielectric of the object to be heated, which has been subjected to magnetic field heating, by a method different from that of magnetic field heating.

2. The heating system according to claim 1, wherein the supply unit supplies microwaves to the rectangular waveguide such that the electric field strength of the microwaves at the predetermined position is minimal or zero.

3. The heating system according to claim 1, wherein the object to be heated is in the form of a sheet, the rectangular waveguide has a slot formed in it into which the object to be heated is inserted and through which the object to be heated passes to the predetermined position, the waveguide mode of the microwaves transmitted through the internal space of the rectangular waveguide is the TEX0 mode or the TE0X mode (where X is an integer satisfying X≧1), and when L is the dimension of the internal space of the rectangular waveguide in the direction normal to the E-plane of the rectangular waveguide, the slot is formed such that its distance from the E-plane in the normal direction is n×L / X (where n is an integer satisfying 0≦n≦X) and it is parallel to the E-plane.

4. The heating system according to claim 1, wherein the object to be heated is in the form of a sheet, the rectangular waveguide has a slot formed in it into which the object to be heated is inserted and through which the object to be heated passes to the predetermined position, the waveguide mode of the microwaves transmitted through the internal space of the rectangular waveguide is the TEX0Z mode or the TE0XZ mode (where X is an integer satisfying X≧1 and Z is an integer satisfying Z≧1), and when L is the dimension of the internal space of the rectangular waveguide in the direction normal to the E-plane of the rectangular waveguide, the slot is formed such that its distance from the E-plane in the normal direction is n×L / X (where n is an integer satisfying 0≦n≦X) and it is parallel to the E-plane.

5. The heating system according to claim 4, wherein the supply unit has an oscillation unit that oscillates microwaves and can change the frequency of the microwaves within a predetermined frequency band, and further comprises an oscillation control unit that controls the oscillation unit, the oscillation control unit causes the oscillation unit to perform a frequency sweep within the predetermined frequency band, thereby moving the positions of the antinodes and nodes of the standing waves formed in the internal space of the rectangular waveguide in the guiding direction in which the rectangular waveguide guides the microwaves.

6. The heating system according to any one of claims 1 to 5, further comprising a visible light camera, an infrared sensor, a temperature sensor, and at least one radio wave sensor for detecting a material to be detected, which is at least one of a conductive material, a magnetic material, and a semiconductor contained in the object to be heated by the magnetic field heating.

7. The heating unit is a second rectangular waveguide different from the first rectangular waveguide, which is the first rectangular waveguide; the predetermined position of the first rectangular waveguide is the first predetermined position; the second rectangular waveguide guides a second microwave, which is a microwave different from the first microwave, which is the microwave, and performs electric field heating when the object to be heated passes through the second predetermined position, which is a predetermined position in the internal space of the second rectangular waveguide; and the heating system according to claim 1 further comprises a second supply unit, which is a supply unit different from the first supply unit, and supplies the second microwave to the second rectangular waveguide such that the electric field strength of the second microwave is maximized or at its maximum at the second predetermined position.

8. The heating system according to claim 7, wherein the second supply unit supplies the second microwave to the second rectangular waveguide such that the magnetic field strength of the second microwave is minimal or zero at the second predetermined position.

9. The heating system according to claim 7, wherein the object to be heated is in the form of a sheet, the second rectangular waveguide has a slot formed in it into which the object to be heated is inserted and through which the object to be heated passes to the second predetermined position, the waveguide mode of the second microwave transmitted through the internal space of the second rectangular waveguide is the TEX0 mode or the TE0X mode (where X is an integer satisfying X≧1), and when L is the dimension of the internal space of the second rectangular waveguide in the direction normal to the E plane of the second rectangular waveguide, the slot is formed such that the distance from the E plane in the normal direction is (2m-1)×L / 2X (where m is an integer satisfying 1≦m≦X) and is parallel to the E plane.

10. The heating system according to claim 7, wherein the object to be heated is in the form of a sheet, the second rectangular waveguide has a slot formed in it into which the object to be heated is inserted and through which the object to be heated passes to the second predetermined position, the waveguide mode of the second microwave transmitted inside the second rectangular waveguide is the TEX0Z mode or the TE0XZ mode (where X is an integer satisfying X≧1 and Z is an integer satisfying Z≧1), and when L is the dimension of the internal space of the second rectangular waveguide in the direction normal to the E plane of the second rectangular waveguide, the slot is formed such that the distance from the E plane in the normal direction is (2m-1)×L / 2X (where m is an integer satisfying 1≦m≦X) and is parallel to the E plane.

11. The heating system according to claim 10, wherein the second supply unit has an oscillation unit that oscillates the second microwave and can change the frequency of the second microwave within a predetermined frequency band, and further comprises an oscillation control unit that controls the oscillation unit, the oscillation control unit causes the oscillation unit to perform a frequency sweep within the predetermined frequency band, thereby moving the positions of antinodes and nodes of standing waves formed in the internal space of the second rectangular waveguide in the guiding direction in which the second rectangular waveguide guides the second microwave.

12. The heating system according to any one of claims 7 to 11, further comprising: a visible light camera, an infrared sensor, a temperature sensor, and at least one of a radio wave sensor for detecting a material to be detected, which is at least one of a conductive material, a magnetic material, and a semiconductor contained in the object to be heated by magnetic field heating; and a supply control unit for controlling the second supply unit, wherein when the material to be detected is detected, the supply control unit controls the second supply unit to temporarily stop supplying the second microwave when the material to be detected passes the second predetermined position.

13. The heating system according to claim 12, wherein the object to be heated is in the form of a sheet, the first rectangular waveguide has a first slot formed therein into which the object to be heated is inserted and through which the object to be heated passes to a first predetermined position, the second rectangular waveguide has a second slot formed therein into which the object to be heated is inserted and through which the object to be heated passes to a second predetermined position, and the system further comprises a conveying device that conveys the object to be heated in a roll-to-roll manner and sequentially passes the object to be heated through the first slot and the second slot, respectively.

14. The heating system according to claim 13, wherein the first rectangular waveguide has a first choke structure for suppressing leakage of the first microwave from the first slot, and the second rectangular waveguide has a second choke structure for suppressing leakage of the second microwave from the second slot.

15. The heating system according to claim 13, wherein at least one of the first slot and the second slot is a plurality.

16. A heating method for heating an object to be heated according to claim 1, comprising: a first heating step of performing magnetic field heating using microwaves as the object to be heated passes through a predetermined position; and a second heating step of heating the dielectric of the object to be heated, which has been magnetically heated in the first heating step, in a manner different from the magnetic field heating, wherein in the first heating step, microwaves are supplied to the rectangular waveguide such that the magnetic field strength of the microwaves is maximized or at its maximum at the predetermined position.

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