JP2019140103A - Microwave-heating device, heating method and chemical reaction method - Google Patents

Abstract

To provide a microwave-heating device which can heat a heating-target object efficiently and uniformly by passing the heating-target object through a location where a magnetic field intensity reaches a maximum in a cavity resonator on condition that a stationary wave is formed in the cavity resonator.SOLUTION: A microwave-heating device 1 comprises: a cavity resonator 11 making a microwave exposure space which is cylindrical or in a polygonal pipe form having two faces opposed to each other around its central axis C and arranged in parallel with each other, other than a pipe form having a rectangular section in a vertical direction to the central axis; and a supplying unit 31 operable to supply a heating-target object 6 of a magnetic material, a material with a magnetic loss or a conductive material, or a heating-target object of a composite material containing a magnetic material, a material with a magnetic loss or a conductive material into a space in the cavity resonator 11, of which the energy distribution of a magnetic field is uniform so that the heating-target object passes through such a magnetic field exposure space of the cavity resonator that a magnetic field intensity is maximum and uniform, thereby heating the heating-target object supplied by the supplying unit in the magnetic field exposure space.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a microwave heating apparatus, a heating method, and a chemical reaction method.

Microwaves are widely used from homes such as microwave ovens, and thereafter, practical development and use as industrial heating systems have been studied. Since the object to be heated generates heat directly by microwave irradiation, it can be heated in a short time, and there is an advantage that temperature unevenness due to heat conduction can be reduced. In addition, there are advantages such that heating can be performed in a non-contact manner, and only those having good microwave absorption can be selectively heated.
In industrial fields such as film formation, semiconductor device manufacturing, printing, electronics wiring, and surface treatment, continuous heat treatment of sheet-like substances or thin films coated on the surface of sheet-like substances can be automated and labor-saving. Leading to improved production costs and quality. Therefore, various methods have been proposed for continuation of the microwave heat treatment method.

As heat treatment by microwave irradiation, microwaves, which are electromagnetic waves, tend to have uneven heating because their energy intensity changes with the wavelength period. For this reason, measures such as uniform heating are often performed by moving the position of the object to be heated over time. As a technique for coping with this problem, for example, Patent Document 1 describes a microwave heating apparatus using a cavity resonator. This technique describes that a standing wave of TM ₁₁₀ mode is generated in a rectangular parallelepiped cavity resonator, and a sheet including a conductive or magnetic thin film is uniformly heated with high efficiency. Further, in Patent Document 2, an object to be heated is arranged at a position where a standing wave magnetic field is maximized by a microwave heating apparatus using a rectangular waveguide (rectangular cavity resonator), and It is described that the heating is efficiently performed by moving the position.
By using a cavity resonator in this way, it is said that a standing wave can be formed inside and the object to be heated can be heated to heating uniformly and with high efficiency.

JP 2006-221958 A JP 2013-101808 A

  In the formation of a standing wave using a cavity resonator, the state of the standing wave in the resonator is monitored to generate a standing wave continuously, and if necessary, the frequency of the microwave supplied into the cavity The resonance frequency is adjusted by adjusting the frequency or inserting a dielectric or metal piece into the cavity. In such a case, when a dielectric or a metal piece is inserted into the cavity, the magnetic field strength distribution of the standing wave formed in the cavity resonator may vary depending on the amount of insertion. As a result, when heating the object to be heated, if the object to be heated is supplied to a constant position in the cavity resonator, it is between the supply position of the object to be heated and the maximum position of the magnetic field strength. Deviation will occur. In order to cope with this, it is conceivable to change the supply position of the object to be heated so as to follow the maximum position of the changed magnetic field strength, but the apparatus becomes large and is not realistic.

  The present invention provides a magnetic material, a magnetic lossy material or a conductive material, a magnetic material, a magnetic lossy material, or a conductive material including a semiconductor by a standing wave formed in the cavity resonator. To provide a microwave heating apparatus that can efficiently heat an object to be heated made of a composite material including the alignment material along a magnetic field intensity distribution with high reproducibility. Is an issue.

The inventors of the present invention have made extensive studies in view of the above problems. As a result, it has been found that by using a cylindrical cavity resonator, it is possible to form a standing wave in which the maximum portion of the magnetic field is always the central axis of the cavity resonator. Then, by supplying a heated object made of a material having a magnetic loss or a composite material containing a magnetic loss material so as to pass through the central axis of the cavity resonator, a heating state of the supplied heated object I found that I can always be constant.
The present invention has been further studied based on these findings and has been completed.

That is, the said subject of this invention is solved by the following means.
[1]
A cavity resonator serving as a microwave irradiation space of a cylindrical tube or a polygonal tube type in which two surfaces facing each other centering on a tube center axis excluding a tube shape having a rectangular cross section perpendicular to the tube center axis;
In a space in which the energy distribution of the magnetic field (magnetic field) in the cavity resonator is uniform, a magnetic material, an object to be heated of a magnetic loss material or a conductive material, or a magnetic material, a material with a magnetic loss Alternatively, a supply unit that supplies an object to be heated of a composite material including a conductive material so as to pass through a magnetic field irradiation space in which the magnetic field strength of the cavity resonator is maximized and uniform,
The microwave heating apparatus which heats the said to-be-heated object supplied by the said supply part in the said magnetic field irradiation space.
[2]
The said heating part is a microwave heating apparatus as described in [1] which lets the said to-be-heated object pass the space where electric field (electric field) intensity becomes the minimum, when the to-be-heated object passes the said microwave irradiation space.
[3]
The standing wave formed inside the microwave irradiation space is TM ₁₁₀ mode,
The microwave heating device according to [1] or [2], wherein the magnetic field irradiation space is a space along a cylinder center axis of the cavity resonator.
[4]
The means for forming the TM ₁₁₀ mode standing wave is a microwave that always maintains a uniform distribution state of the magnetic field along the cylinder center axis in a state where the object to be heated is inserted in the microwave irradiation space. The microwave heating device according to [3], which has a mechanism for controlling the frequency of.
[5]
The mechanism for controlling the frequency of the microwave detects a resonance frequency that matches the standing wave of the TM ₁₁₀ mode that varies according to the insertion state of the object to be heated, and irradiates the microwave that matches the resonance frequency The microwave heating apparatus according to [4].
[6]
The means for detecting the resonant frequency that matches the standing wave of the TM ₁₁₀ mode has a mechanism for measuring the reflected wave from the microwave irradiation space, and the frequency at which the reflected wave is minimized based on the measurement signal. The microwave heating device according to [5], further including a mechanism for controlling a frequency of the microwave for detecting a resonance frequency.
[7]
The means for detecting the resonance frequency that matches the standing wave of the TM ₁₁₀ mode has a mechanism for measuring the energy state in the microwave irradiation space, and the energy in the microwave irradiation space based on the measurement signal. The microwave heating apparatus according to [5], including a mechanism for controlling the frequency of the microwave for detecting a resonance frequency from a frequency at which the density is maximized.
[8]
Any one of [1] to [7], wherein an induction current is generated in the object to be heated by applying a maximum magnetic field on the cylindrical central axis of the cavity resonator, and the object to be heated is heated. The microwave heating apparatus as described.
[9]
The microwave heating device according to any one of [1] to [8], wherein the microwave heating device is a chemical reaction device that heats the object to be heated by microwaves to cause a chemical reaction.
[10]
[1] A heating method using the microwave heating apparatus according to any one of [9].
[11]
A chemical reaction method using the microwave heating apparatus according to any one of [1] to [9], wherein the chemical reaction method includes generating a chemical reaction by heating the object to be heated.

  When the microwave heating apparatus of the present invention forms a standing wave in the cavity resonator, the object to be heated is passed to a position where the magnetic field intensity in the cavity resonator becomes maximum and uniform, It can be heated efficiently and uniformly with high reproducibility.

It is the schematic sectional drawing which showed typically an example of one desirable embodiment of the microwave heating device of the present invention. It is an electric field and magnetic field distribution map which generate | occur | produces in a cylindrical cavity resonator, (A) is an electric field distribution map, (B) is a magnetic field distribution map. The temperature change of the sheet material when the sheet material of the antistatic aluminum vapor deposition bag used in Example 3 is heated while moving in the magnetic field irradiation (reaction) space, the incident wave and the reflected wave of the microwave heating apparatus 1, the resonance It is the figure which showed the change of a frequency. FIG. 4 is a temperature distribution diagram in the width direction of the sheet material measured using a thermal image measuring device when the sheet material of the antistatic aluminum vapor deposition bag used in Example 3 is heated while moving in the magnetic field irradiation (reaction) space. is there. In the figure, the region indicated by the braces represents the width of the sheet material. It is the figure which showed the temperature measurement result of the center part of a sheet | seat using the radiation thermometer, respectively, about the result of having heated microwaves by changing a microwave output. It is the figure which showed the result of having heated the conductive silicon rubber by changing the microwave output, and measuring the temperature of the sheet | seat center part using the radiation thermometer, respectively. The temperature change of the sheet material when the coating material of the conductive paste used in Example 7 was installed in the center of the magnetic field irradiation (reaction) space and heated, and the incident wave and the reflected wave of the microwave heating apparatus 1; It is the figure which showed the change of the resonant frequency. Temperature distribution diagram in the width direction of the sheet material measured using the thermal image measuring device when the sheet material of the conductive paste used in Example 7 is installed and heated in the center of the magnetic field irradiation (reaction) space It is. In the figure, the region indicated by the braces represents the width of the sheet material. It is a drawing substitute photograph which showed the external appearance of the sheet material of the electrically conductive paste used in Example 7, (A) A figure is an observation result before magnetic field heating, (B) A figure is an observation result after magnetic field heating. . The sheet material of the conductive paste used in Comparative Example 8 was installed in the center of the cavity resonator, and the temperature change of the sheet material when dielectric heating was performed by forming a _TM010 mode standing wave, and It is the figure which showed the change of the incident wave of a microwave heating device, a reflected wave, and the resonant frequency. The time change of the substrate surface temperature measured using a radiation thermometer when a silicon substrate, which is one of the semiconductor materials used in Example 9, is installed in the center of the magnetic field irradiation (reaction) space and heated. FIG.

  Preferred embodiments of the microwave heating apparatus of the present invention will be described below with reference to the drawings.

[Microwave heating device]
A preferred embodiment of the microwave heating apparatus of the present invention will be described with reference to FIG. 1, taking a microwave heating apparatus having a cylindrical cavity resonator as an example.
As shown in FIG. 1, the microwave heating apparatus 1 includes a cavity resonator (hereinafter also referred to as a (cylindrical) cavity resonator) 11 having a cylindrical microwave irradiation space. Even if the cavity resonator 11 has a cylindrical shape, two surfaces facing the cylindrical center axis except for a cylindrical shape having a rectangular cross section perpendicular to the cylindrical central axis (hereinafter referred to as a rectangular cylindrical shape) are provided. Even in a parallel polygonal cylinder, a standing wave having a maximum and uniform magnetic field intensity can be formed on the central axis.
The cavity resonator 11 is provided on a body wall 11SA of the cavity resonator 11 facing the cylinder center axis (hereinafter, also referred to as a cylinder center axis or center axis) C of the cavity resonator 11 across the cylinder resonator. It has the supply port 12 and the discharge port 13 provided in trunk | drum wall 11SB which opposes trunk | drum wall 11SA. In addition, in a magnetic field irradiation space in which the magnetic field strength in the cavity resonator 11 is maximized and uniform, an object to be heated of a magnetic loss material, a conductive material, or a composite material including a magnetic loss or a conductive material is provided. A supply unit 31 is provided. “Maximum” means that the surrounding magnetic field strength including the local maximum point includes a portion stronger than other regions. For example, it is a region where the maximum value is 3/4 or more. Further, “a material having magnetic loss or a composite material including a material having magnetic loss” can be said to be “a composite material including a material having magnetism or conductivity or a material having magnetism or conductivity”. Furthermore, an antenna 25 for supplying a microwave that forms a standing wave in the cavity resonator 11 is provided.
Examples of magnetic loss materials include iron, nickel, and cobalt, and alloys including iron group elements and rare earth elements include Fe—Ni, Fe—Co, Fe—Ni—Co—Al, and Fe—Ni—Cr. , MnAl, and SmCo ₅ and SmCo ₅ as compounds. There are also Fe ₃ O _{4 and the} like as oxides. A material having magnetic loss is not only a magnetic material, but also a conductive material such as aluminum, copper, and tin is a material that causes magnetic loss due to eddy current. The conductive material includes a semiconductor material. Examples of the semiconductor material include silicon and germanium. Examples of the compound semiconductor include ZnSe, CdS, ZnO, GaAs, InP, GaN, SiC, and SiGe. These include those in which impurities are implanted into these semiconductor materials to control conductivity. Carriers responsible for conductivity include not only electrons but also holes formed in the semiconductor, and can cause a heating action by microwaves.

For example, in the case of the cylindrical cavity resonator 11 in which a standing wave of TM ₁₁₀ mode is generated, the magnetic field irradiation space has a maximum magnetic field strength at the central axis C, and the magnetic field strength is uniform along the central axis C. Space. The sheet 6 to be heated is preferably arranged so as to pass through the magnetic field irradiation space, that is, pass through the central axis C. The sheet 6 is preferably arranged so as to pass along the plane of symmetry of the cavity resonator. Therefore, it is preferable that the supply port 12 and the discharge port 13 of the sheet 6 are arranged on the body wall 11SA, 11SB of the cylindrical cavity resonator 11 at a position facing each other across the central axis C. In other words, the supply port 12, the central axis C, and the discharge port 13 are preferably arranged at positions including the same plane. The “sheet” is used to include a substrate such as a semiconductor substrate or a wiring substrate having a certain thickness from a thin one such as paper or film.
A microwave generator 21 is disposed in the cavity resonator 11, and microwaves are supplied to the cavity resonator 11. In general, an S band of 2 to 4 GHz is used as the microwave frequency. Alternatively, 900 to 930 MHz or 5.725 to 5.875 GHz may be used. However, other frequencies can be used.

  In the microwave heating apparatus 1 described above, the microwave generated by the microwave generator 21 is supplied to the cavity resonator 11 from the microwave supply port 14 into the cavity resonator 11. The standing wave is formed at the position of the central axis C of 11. As the microwave supply port 14, for example, a coaxial waveguide converter type microwave supply port can be used. The sheet 6 that is the object to be heated is heated at the portion where the magnetic field strength of the standing wave is maximized (the central axis C of the cylindrical resonator 11).

In the microwave heating apparatus 1, the microwave supplied from the microwave generator 21 is supplied with the frequency adjusted. By adjusting the frequency, the magnetic field strength distribution of the standing wave formed in the cavity resonator 11 can be controlled to a desired distribution state, and the strength of the standing wave can be adjusted by the output of the microwave. That is, it becomes possible to control the heating state of the object to be heated.
The frequency of the microwave supplied from the microwave supply port 14 can form a specific single mode standing wave in the cavity resonator 11.
The structure of the microwave heating apparatus 1 of this invention is demonstrated in order.

<Cavity resonator>
A cylindrical cavity resonator (cavity) 11 used for a microwave heating apparatus has a single microwave supply port 14, and a single-mode standing wave is formed when microwaves are supplied. If there is no particular limitation. The cavity resonator used in the present invention is not limited to a cylindrical shape as shown in the drawings. That is, even if it is not a cylindrical type, it may be a polygonal cylindrical cavity resonator in which two faces facing the center axis are parallel except for a cylindrical shape whose cross section perpendicular to the central axis is rectangular. good. For example, the cross section perpendicular to the central axis is opposed to the central axis of a regular hexagonal, regular octagonal, regular dodecagonal, regular hexagonal or other positive or even square cylinder. It may be a polygonal cylindrical shape crushed between two surfaces. In the case of the above-described polygonal cavity resonator, the corners inside the cavity may be rounded. Further, the microwave irradiation space may be a cavity resonator having a space such as a columnar body, an ellipsoid or the like having a larger roundness in addition to the above cylindrical shape.
Even with such a polygon, an action similar to that of the cylindrical shape (that is, a standing wave having a maximal and uniform magnetic field intensity can be formed on the central axis) can be realized.
The size of the cavity resonator 11 can be appropriately designed according to the purpose. The cavity resonator 11 preferably has a low electrical resistivity, and is usually made of metal. For example, aluminum, copper, iron, magnesium, brass, stainless steel, or an alloy thereof can be used. Alternatively, a resin, ceramic, or metal surface may be coated with a substance having a low electrical resistivity by plating, vapor deposition, or the like. For the coating, a material containing silver, copper, gold, tin, or rhodium can be used.

<Supply section>
The supply unit 31 includes a supply-side transport unit 31A and a delivery-side transport unit 31B.
The supply-side transport unit 31A includes a pair of nip rolls 32A and 32B, and one of them is provided with a rotation drive device (not shown) that drives the nip roll. The sheet 6 sandwiched between the nip rolls 32A and 32B is conveyed into the cavity resonator 11 by the rotation of the nip rolls 32A and 32B. The delivery-side transport unit 31B includes a pair of nip rolls 33A and 33B, and one of them is provided with a rotation drive device (not shown) that drives the nip roll. By rotation of the nip rolls 33A and 33B, the sheet 6 sandwiched between the nip rolls 33A and 33B is conveyed outside the cavity resonator 11. It is preferable that the supply-side transport unit 31A and the delivery-side transport unit 31B always transport the sheet 6 at a constant speed. The peripheral speeds of the nip rolls 32A, 32B, 33A, 33B are preferably equal.
As another supply method, a plate having a small magnetic loss can be suspended from the supply port 12 to the discharge port 13 as a support base (not shown), and the object to be heated can be placed thereon. In this case, as a means for moving the object to be heated, the support base may be moved, or the object to be heated can be pushed in or pulled out.
Or the supply part 31, the supply port 12, and the discharge port 13 do not need to be installed. In this case, the object to be heated is placed in advance at a position where the magnetic field in the cavity resonator is maximized, and after processing for an appropriate time, the microwave is stopped, a part of the cavity resonator is opened, and the object to be heated is opened. The object to be heated can be taken out.
Alternatively, the cavity resonator itself can be moved without using a special transport mechanism as the supply unit 31. In this case, the object 6 to be heated is fixed, and the cavity resonator itself is aligned with the object to be heated so that the position where the magnetic field in the cavity resonator becomes maximum is not removed from the object 6 to be heated. It is suitable to move in parallel.
Or the supply port 12 and the discharge port 13 can also be arrange | positioned along the gravity direction. In the case of an object to be heated that is flexible, the object to be heated 6 hangs down according to gravity. Or you may pull out against gravity with the discharge port 13 up.

<Supply of microwave>
The microwave supply is preferably provided with a microwave generator 21, a microwave amplifier 22, an isolator 23, an impedance matching unit 24, and an antenna 25.

A microwave supply port 14 is provided on the wall surface (cylindrical inner surface) parallel to the central axis C of the cavity resonator 11 or in the vicinity thereof. In one embodiment, the microwave supply port 14 has an antenna 25 to which a high frequency can be applied. FIG. 1 shows a microwave supply port 14 using a coaxial waveguide converter. In this case, the antenna 25 is an electric field excitation type monopole antenna. At this time, in order to effectively form a standing wave, an iris (not shown) may be used as an appropriate opening between the microwave supply port 14 and the cavity resonator 11. Further, an antenna may be installed directly in the cavity resonator 11 without using the microwave supply port 14. In this case, a loop antenna (not shown) serving as a time excitation antenna may be installed near the side wall of the cavity resonator. Alternatively, it is possible to install a monopole antenna for electric field excitation on the upper or lower surface of the cavity resonator.
The antenna 25 is supplied with microwaves from the microwave generator 21. Specifically, the microwave amplifier 22, the isolator 23, the matching unit 24, and the antenna 25 are connected to the microwave generator 21 through the cables 26 (26A, 26B, 26C, and 26D) in this order. Yes.
For each cable 26, for example, a coaxial cable is used. In this configuration, the microwaves emitted from the microwave generator 21 are supplied into the cavity resonator 11 from the microwave supply port 14 by the antenna 25 via the cables 26.

[Microwave generator]
As the microwave generator 21 used in the microwave heating apparatus 1 of the present invention, for example, a microwave generator such as a magnetron or a microwave generator using a semiconductor solid element can be used. From the viewpoint that the frequency of the microwave can be finely adjusted, it is preferable to use a VCO (Voltage-Controlled Oscillator), a VCXO (Voltage-controlled Xtal Oscillator), or a PLL (Phase-locked loop) oscillator.

[Microwave amplifier]
The microwave heating apparatus 1 in FIG. 1 includes a microwave amplifier 22. The microwave amplifier 22 has a function of amplifying the microwave output generated by the microwave generator 21. Although there is no restriction | limiting in particular in the structure, For example, it is preferable to use the semiconductor solid element comprised by a high frequency transistor circuit. When a microwave generator having a large oscillation output such as a magnetron is used, the microwave amplifier circuit can be omitted.

[Isolator]
The microwave heating apparatus 1 in FIG. 1 includes an isolator 23. The isolator 23 is used to protect the microwave generator 21 by suppressing the influence of the reflected wave generated in the cavity resonator 11 so that the microwave is supplied in one direction (antenna 25 direction). It is to make. If the microwave amplifier 22 and the microwave generator 21 are not likely to be damaged by the reflected wave, it is not necessary to install an isolator. In this case, there is an advantage that the apparatus can be downsized and the cost can be reduced.

[Matching unit]
The microwave heating apparatus 1 of FIG. The matching unit 24 is for matching (matching) the impedance of the microwave generator 21 to the isolator 23 and the impedance of the antenna 25. If there is no possibility that the microwave amplifier 22 or the microwave generator 21 may be damaged even if a reflected wave due to mismatching occurs, the matching unit need not be installed. Alternatively, the matching unit can be omitted by adjusting the antenna structure, the circuit constant of the microwave amplifier 22 and the cable 26 so that mismatching does not occur in advance. In this case, there is an advantage that the apparatus can be downsized and the cost can be reduced.

[antenna]
As the antenna 25, for example, a monopole antenna, a loop antenna, or a patch antenna can be used. In the case of a monopole antenna, the end of the antenna is exposed in space through an insulator so that the housing of the cavity resonator 11 and the housing of the microwave supply port function as a ground plane (see FIG. Not shown). In the case of a loop antenna, although not shown, the end of the loop antenna is connected to a ground potential such as a cavity wall surface. By applying a microwave (high frequency) to the antenna 25, a magnetic field is excited in the loop, and a standing wave can be formed in the cavity resonator.
For example, when the TM ₁₁₀ single-mode standing wave is formed in the above cylindrical cavity resonator, the magnetic field strength is maximized in the central axis C, and the magnetic field strength is uniform in the direction of the central axis C. Therefore, the object to be heated existing on the upper surface of the sheet 6 or the sheet itself can be microwave-heated uniformly and efficiently.

<Control system>
The microwave heating device 1 is provided with a thermal image measuring device (thermo viewer) 41 or a radiation thermometer (not shown) for measuring the temperature of the sheet 6 to be heated. The cavity resonator 11 is provided with a window 15 for measuring the temperature distribution of the sheet 6 by a thermal image measuring device 41 or a radiation thermometer (not shown). The measurement image of the temperature distribution of the sheet 6 measured by the thermal image measurement device 41 or the temperature information measured by the radiation thermometer is transmitted to the control unit 43 via the cable 42. Further, an electromagnetic wave sensor 44 is disposed on the body wall 11S of the cavity resonator 11. A signal corresponding to the electromagnetic field energy in the cavity resonator 11 detected by the electromagnetic wave sensor 44 is transmitted to the control unit 43 via the cable 45. The control unit 43 can detect the formation state (resonance state) of the standing wave generated in the cavity resonator 11 based on the signal of the electromagnetic wave sensor 44. When a standing wave is formed, that is, resonates, the output of the electromagnetic wave sensor 44 is increased. By adjusting the oscillation frequency of the microwave generator so that the output of the electromagnetic wave sensor 44 is maximized, the microwave frequency can be controlled to coincide with the resonance frequency of the cavity resonator 11. Since the resonance frequency varies depending on the condition of the object to be heated (insertion state, temperature, etc.), it is necessary to perform this control at an appropriate interval. When the change is fast, when the supply speed of the object to be heated is high, and when the supply speed fluctuates, it is desirable to carry out at intervals of 1 millisecond to 1 second. When the change is small, such as when the object to be heated is fixed or when the supply speed does not vary, the interval may be 10 seconds to 1 minute. Alternatively, once the resonance frequency is obtained before heating, it may not be necessary to always control thereafter.

  Based on the detected frequency, the control unit 43 feeds back to the microwave generator 21 via the cable 46 the frequency of the microwave in which a standing wave having a constant frequency appears in the cavity resonator 11. Based on this feedback, the control unit 43 precisely controls the frequency of the microwave supplied from the microwave generator 21. In this way, a standing wave can be stably generated in the cavity resonator 11. Therefore, the sheet 6 to be heated can be efficiently heated by the standing wave with high reproducibility and uniformity. Further, the control unit 43 can be adjusted so that a microwave with a constant output can be supplied to the antenna 25 by instructing the microwave amplifier 22 to output a microwave. Alternatively, the amplification factor of the microwave amplifier 22 is not changed, and the attenuation factor of an attenuator (not shown) installed between the microwave generator 21 and the microwave amplifier 22 may be adjusted by an instruction from the control unit 43. it can. The microwave output may be feedback controlled so that the object to be heated becomes the target temperature based on the indication value of the thermal image measurement device 41 or the radiation thermometer. When a device capable of outputting a large output such as a magnetron is used as the microwave oscillator 21, the control unit 43 may be instructed to adjust the microwave output to the microwave generator 21.

  As a control method not using the electromagnetic wave sensor 44, the magnitude of the reflected wave of the cavity resonator 11 may be measured and the value may be used. The measurement of the reflected wave can use the amount of isolation obtained from the isolator 23. Alternatively, a reflection signal obtained from a directional coupler (not shown) installed between the matching unit 24 (cable 26D connected to the microwave supply port when not installed) and the isolator 23 can be used. By adjusting the frequency of the microwave generator so that the reflected wave signal is minimized, the microwave energy can be efficiently supplied to the cavity resonator 11. At this time, there is a high possibility that the resonant frequency of the cavity resonator 11 and the frequency of the microwave generator match. However, in this method, there is a possibility that the microwave is consumed by the cable 26, the antenna 25, the waveguide 14, and the like, and there is a case where the microwave frequency does not always coincide with the resonance frequency.

<Heating the object to be heated>
In the microwave heating apparatus 1 of the present invention, the object to be heated is a magnetic loss material or a composite material including a magnetic loss material, in other words, a magnetic or conductive material or a magnetic or conductive material. It is a composite material containing the material which has. Such an object to be heated is arranged corresponding to the magnetic field strength inside the cavity resonator 11. In particular, if the magnetic field strength of the standing wave formed in the cavity resonator 11 is disposed along the portion where the magnetic field strength is maximized, more efficient heating is possible. Specifically, the sheet 6 is supplied from the supply port 12 and discharged from the discharge port 13 so as to pass through the central axis C of the cavity resonator 11.
It is desirable that the object to be heated does not pass through a portion where the electric field is maximized. For example, when a conductive material such as metal is disposed in an electric field, spark discharge or the like may occur, and the object to be heated may be damaged. As shown in FIG. 2A, in the electric field distribution of the TM ₁₁₀ mode, the electric field strength is minimal on a horizontal plane (when the microwave supply port 14 is arranged vertically below) passing through the central axis C. If the object to be heated is arranged, supplied, or discharged along this surface, damage to the object to be heated due to the electric field can be suppressed. Note that the region where the electric field strength is minimized is a quarter of the maximum electric field strength in the cavity resonator.

In the microwave heating apparatus 1 shown in FIG. 1, there is no particular limitation on an object to be heated as long as it is a magnetic loss or conductive material, or a composite material containing a magnetic loss or conductive material. Even solids, powders and mixtures thereof can be heated.
When the object to be heated is liquid, solid, or powder, the temperature of the object to be heated can be controlled continuously by arranging and conveying them on the sheet. The microwave heating apparatus 1 of the present invention can selectively heat an object to be heated on a sheet. For example, the solder on the substrate can be selectively heated. Moreover, since the progress of many chemical reactions can be controlled by temperature, the microwave heating apparatus 1 of the present invention is preferably used for controlling chemical reactions.
The object to be heated may itself be capable of maintaining the sheet shape. For example, if the object to be heated is a fibrous solid, it can be conveyed without support of a sheet or the like.
When the object to be heated is a catalyst, the microwave heating apparatus 1 of the present invention can be used to cause a chemical reaction by the action of the catalyst, as will be described later. It is also preferable that the catalyst be supported on a sheet.
Examples of the chemical reaction include transfer reaction, substitution reaction, addition reaction, cyclization reaction, reduction reaction, oxidation reaction, selective catalytic reduction reaction, selective oxidation reaction, racemization reaction, cleavage reaction, catalytic cracking reaction (cracking), etc. However, the present invention is not limited to these, and various chemical reactions may be mentioned.

  In the chemical reaction method of the present invention, the reaction time, reaction temperature, reaction substrate, reaction medium, and other conditions may be appropriately set according to the target chemical reaction. For example, Chemistry Handbook (Edited by Shuichi Suzuki and Mitsuaki Mukaiyama, Asakura Shoten, 2005), Microwave Chemical Process Technology II (supervised by Kazuhiko Takeuchi and Yuji Wada, CM Publishing, 2013), JP 2010-215677, etc. It is possible to refer to the chemical reaction conditions as appropriate.

In the form shown in FIG. 1, the frequency of the standing wave is not particularly limited as long as the standing wave can be formed in the cavity resonator 11. When microwaves are supplied from the microwave supply port 14, the above-described TM ₁₁₀ mode standing wave can be formed in the cavity resonator 11. In addition to the standing wave of the TM ₁₁₀ mode, for example, modes of TM ₂₁₀ , TM ₃₁₀ , and TM ₄₁₀ can be cited. The standing wave of TM ₁₁₀ is most preferable in that the maximum portion of the magnetic field strength can be efficiently formed along the central axis C of the cavity resonator 11. In addition, when the object to be heated is a conductive material, it is not desirable for the object to be heated to pass through a portion where the electric field concentrates, so that the electric field strength is minimized on the surface passing through the maximum portion of the magnetic field strength. The TM ₁₁₀ mode in which the surface can be formed is particularly preferred. In this way, by passing the object to be heated through the surface where the electric field strength is minimized, the object to be heated is not destroyed by the electric field.
When a cube or a rectangular parallelepiped having a cross section perpendicular to the central axis is used as the cavity resonator, TE _10n (n is an integer of 2 or more) similarly forms an electromagnetic wave irradiation space having a maximum magnetic field intensity. Can do.

The means for forming a TM ₁₁₀ mode standing wave is that the object to be heated is inserted into the cavity resonator 11 (microwave irradiation space) and the magnetic field is always uniformly distributed along the center axis C of the cylinder. It is preferable to have a mechanism for controlling the frequency of the microwave to maintain the above. Alternatively, it is preferable to have a mechanism for controlling the shape of the microwave irradiation space.

Specifically, the mechanism for controlling the frequency of the microwave detects a resonance frequency that matches the standing wave of the TM ₁₁₀ mode that varies according to the insertion state of the object to be heated, and detects a resonance frequency that matches the resonance frequency. It irradiates waves.
In the resonance state of the TM ₁₁₀ mode, energy is efficiently supplied into the cavity resonator 11. At this time, the output of the electromagnetic wave sensor 44 installed on the side wall of the cavity resonator outputs a signal proportional to the energy intensity in the cavity resonator 11, so that the microwave is generated so that the signal output amount is maximized. The oscillation frequency of the device 21 may be adjusted. As a method of adjustment, if the oscillation frequency of the microwave generator 21 is swept within a certain range (100 MHz as an example), a spectrum in which a peak occurs in the output of the electromagnetic wave sensor 44 can be obtained where the resonance frequency matches. By comparing this spectrum with the theoretical resonance frequency derived from the shape of the cavity resonator, the TM ₁₁₀ mode resonance frequency can be identified. Once identified, if the oscillation frequency of the microwave generator 21 is periodically swept within a narrow range (for example, 5 MHz) in the vicinity of the resonance frequency, due to changes in the object to be heated (insertion amount, temperature, etc.), Changes in the TM ₁₁₀ mode resonance frequency can be tracked. Therefore, the optimum microwave irradiation conditions can always be maintained. It is desirable to appropriately monitor the interval for tracking the resonance frequency and the sweep width according to the speed and amount of change of the object to be heated (supply speed, temperature change amount, uniformity).

As another method for measuring the energy intensity in the cavity resonator, there is a method using the intensity of the reflected wave from the antenna 25 for microwave irradiation. In this case, it is utilized that the reflected wave becomes small in a state where the energy intensity in the cavity resonator is high. Specifically, the oscillation frequency of the microwave generator is adjusted so that the reflected wave intensity is minimized.
However, in the method using the reflected wave, the signal intensity changes due to superposition due to a plurality of factors such as the antenna 25, the matching unit 24, the microwave irradiation port 14, and the cable 26 in addition to the cavity resonator. When precise control is required, it is preferable to use the electromagnetic wave sensor 44 directly attached to the cavity resonator.

Another method for matching the resonance frequency of the cavity resonator 11 and the oscillation frequency of the microwave generator is to change the shape of the microwave irradiation space and adjust the resonance frequency. Specifically, the resonance frequency can be adjusted by inserting a dielectric or a metal piece into the cavity resonance cavity resonator. For example, when a dielectric material (not shown) such as ceramic or Teflon (registered trademark) with little microwave absorption is inserted into the cavity resonator 11, the resonance frequency changes in a lower direction depending on the dielectric constant and the amount of insertion. To do. When a metal piece such as aluminum or copper is inserted instead of the dielectric, the resonance frequency changes in a higher direction. If a mechanism for automatically adjusting the amount of insertion is used, the resonance frequency and the oscillation frequency of the microwave generator can be matched even when the oscillation frequency of the microwave generator cannot be changed as in a magnetron.
However, the position where the magnetic field is maximized when a dielectric or metal is inserted into the cavity resonator 11 also moves according to the amount and position of insertion. For this reason, it is desirable to manage appropriately the position which supplies a to-be-heated target object.

As described above, a mechanism for controlling the insertion amount of the dielectric or metal in the microwave irradiation space in the cavity resonator 11 or adjusting the resonance frequency corresponding to the standing wave of the TM ₁₁₀ mode. By providing, it is preferable to make the frequency of the microwave irradiated from the microwave generator coincide with the resonance frequency.

  The cavity resonator 11 is preferably designed so that the resonance frequency is within the ISM band. Since the resonance frequency varies depending on the temperature change and composition change of the object to be heated, it is desirable that the resonance frequency be within the ISM band in consideration of the fluctuation range. “ISM” is an abbreviation for Industry Science Medical, and the ISM band is a frequency band allocated for general use in the industrial, scientific, and medical fields. However, electromagnetic leakage countermeasures (installation of electromagnetic wave absorber, opening design considering cut-off frequency, installation of choke structure) are taken in the cavity resonator opening, or cavity resonator is installed in the shield space If the electromagnetic wave radiation to the space is suppressed, such as, the ISM band is not restricted.

In the microwave heating apparatus 1 described above, when a microwave is supplied into the cavity resonator 11 to form a specific standing wave, a magnetic field is generated at the central axis C of the cavity resonator 11 and the magnetic field is generated. The maximum value can be obtained, and the magnetic field can be uniformly distributed in the central axis direction. For this reason, when the sheet 6 having the object to be heated of the material having magnetic loss or the composite material containing the material having magnetic loss is discharged from the discharge port 13 through the central axis C from the supply port 12, the maximum is obtained in the central axis C. The formed magnetic field can be uniformly irradiated in the width direction of the sheet 6. For this reason, a material with magnetic loss generates heat by irradiation with a magnetic field.
In the heating described above, when the sheet 6 is formed of paper and a heated object made of a material having a magnetic loss (conductive material) is disposed on the paper, the heated object is heated, but the sheet of paper 6 is not heated. In general, paper contains moisture even in a dry state, and even when irradiated with a magnetic field, the paper containing moisture does not generate an induced current and is not heated. On the other hand, since an induced current is generated in the object to be heated, it is heated. In this way, the object to be heated can be selectively heated.
The cylindrical central axis C has a minimum electric field strength (see the electric field distribution diagram in FIG. 2A) and a maximum magnetic field strength (see the magnetic field distribution diagram in FIG. 2B).

As described above, the microwave heating apparatus 1 uses the cylindrical cavity resonator 11 that forms a standing wave of TM ₁₁₀ mode, for example, so that the magnetic field is concentrated on the central axis C. It becomes a maximum region, and the magnetic field strength becomes uniform in the central axis direction. For this reason, the temperature controllability (uniformity) of the heated object passing through the central axis C is increased. In addition, by controlling the frequency and output of the microwave that forms the standing wave, a constant standing wave can always be formed, so that the temperature controllability can be further improved and more uniform heating can be realized.

  The electromagnetic wave sensor 44 can accurately detect the frequency of the standing wave. Therefore, the detected frequency of the standing wave is fed back to the microwave generator 21 so that the frequency of the microwave supplied from the microwave generator 21 can be precisely controlled. In this way, a standing wave can be stably generated in the cavity resonator 11. Therefore, the object to be heated can be efficiently and uniformly heated by the standing wave, and the formation state of the standing wave in the cavity resonator can be stably maintained.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention should not be construed as being limited thereto.

[Examples 1 to 3]
In each of Examples 1 to 3, a commercially available resin sheet material having a width of 8 cm with different surface resistivity shown in Table 1 was used as a measurement sample. In Example 1, a transparent conductive sheet (Staclear NCF) in which the base material of the sheet material was polyethylene terephthalate (PET) was used. In Example 2, a conductive bag (carbon black added) in which the base material of the sheet material was polyolefin was used. In Example 3, an antistatic aluminum vapor deposition bag in which the base material of the sheet material is PET was used. Then, using the microwave heating apparatus 1 shown in FIG. 1, each sheet material was fixed in a magnetic field irradiation space having a width of 10 cm of the cylindrical cavity resonator 11, and magnetic field heating and dielectric heating were performed. A TM ₁₁₀ mode standing wave was formed for the magnetic field heating, and a TM ₀₁₀ mode standing wave was formed for the dielectric heating, and each measurement sample was fixed along the central axis. Both the magnetic field heating and the dielectric heating were performed in a microwave frequency range of 2.3 to 2.7 GHz and a microwave output range of 0 to 100 W. The same applies to Examples 4 to 7 and Comparative Examples.

[Comparative Example 1]
On the other hand, as Comparative Example 1, a conductive file in which the base material of the sheet material was polypropylene (PP) was used. The thickness and surface resistivity of each sheet are as described in Table 1.
The heating results of Examples 1 to 3 and Comparative Example 1 are shown in Table 1.

In Table 1, Y is indicated when dielectric heating is possible, and N is indicated when dielectric heating is not possible. In addition, when magnetic field heating is possible, it is indicated by Y, and when magnetic field heating is impossible, it is indicated by N. Note that the cavity resonator used for dielectric heating and the cavity resonator used for magnetic field heating use different cavity resonators, and the cylindrical resonators have different inner diameters.

The resin sheet materials of Examples 1 to 3 having a small surface resistivity (10 ⁸ Ω / □ or less) cannot be heated by generally used dielectric heating. On the other hand, it turned out that it can heat by magnetic field heating. Whether dielectric heating or magnetic field heating is possible is determined by the method described in paragraph [0033] above to determine whether the resonance frequency of TM ₀₁₀ mode (whether dielectric heating is possible) or TM ₁₁₀ mode (whether magnetic field heating is possible) can be detected. Judged by.

[Example 4]
Next, in Example 4, a sheet material having a width of 8 cm of the antistatic aluminum vapor deposition bag used in Example 3 was used as a measurement sample. While the measurement sample was moved into a magnetic field irradiation (reaction) space having a width of 10 cm at a speed of 0.2 cm / s, the temperature change of the sheet material when heated, and the incident wave and reflection of the microwave heating apparatus 1 Changes in waves and resonance frequency were measured with an electromagnetic wave sensor. An electromagnetic wave sensor that can be measured as a DC signal by a rectifier circuit using a diode using a loop antenna was used. For temperature measurement, the temperature at the center of the sheet was measured using a radiation thermometer TMHX-CN0500 manufactured by Japan Sensor. For this magnetic field heating, a TM ₁₁₀ mode cavity resonator was used, a TM ₁₁₀ mode standing wave was formed, and the measurement sample was fixed along the central axis. The results are shown in FIG. The temperature was stable at 80 ± 1 ° C. with respect to the set temperature of 80 ° C. Moreover, as a result of measuring the temperature distribution in the width direction of the sheet material using the thermal image measuring device 41, it was confirmed that the entire sheet was heated uniformly (see FIG. 4).

[Examples 5 to 6]
In Example 5, a commercially available sheet-like conductive glass having a width of 8 cm shown in Table 2 was used as a measurement sample. In Example 6, a commercially available sheet-like conductive silicon rubber (carbon mixture) having a width of 8 cm shown in Table 2 was used as a measurement sample. Then, using the microwave heating apparatus 1 shown in FIG. 1, these measurement samples were fixed in a cavity resonator having a width of 10 cm, and magnetic field heating and dielectric heating were performed. on the other hand. In Comparative Examples 5 and 6, the same samples as in Examples 5 and 6 were used except that the heating method was changed from magnetic field heating to dielectric heating in Examples 5 and 6. For magnetic heating, a TM ₁₁₀ mode cavity resonator is used and a TM ₁₁₀ mode standing wave is formed. For dielectric heating, a TM ₀₁₀ mode cavity resonator is used and TM ₀₁₀ mode is used. A standing wave was formed and each measurement sample was fixed along the central axis.
The heating results are shown in Table 2.

In Table 2, Y is indicated when dielectric heating is possible, and N is indicated when dielectric heating is not possible. When magnetic field heating is possible, it is indicated by Y, and when magnetization heating is impossible, it is indicated by N.

  As a result, it was found that heating cannot be performed by generally used dielectric heating. On the other hand, it turned out that it can heat by magnetic field heating. As in the case of heating the resin sheet material, whether or not dielectric heating and magnetic field heating were possible was confirmed by whether or not a microwave standing wave was formed by this microwave heating apparatus. Further, the results of heating the conductive glass and conductive silicon rubber while changing the microwave output are shown in FIGS. 5 and 6, respectively. As a result of measuring the temperature at the center of the sheet using a radiation thermometer, it was confirmed that the ultimate temperature increased as the microwave output increased.

[Example 7]
The conductive paste was heated.
In Example 7, a conductive silver paste (product name REXALPHA, manufactured by Toyochem Co., Ltd.) was applied to quartz glass in a size of 75 mm × 10 mm and a thickness of 0.05 mm to prepare a measurement sample. Ten minutes after application, magnetic field heating was performed using the microwave heating apparatus 1 shown in FIG. For magnetic field heating, a standing wave of TM ₁₁₀ mode was formed. The measurement sample was placed at the center (including the central axis C) in the magnetic field irradiation space of the microwave heating apparatus 1 and heated for 5 minutes at an ultimate temperature of 130 ° C. by magnetic field heating. FIG. 7 shows changes in the temperature of the paste application part during heating, and changes in the incident wave, reflected wave, and resonance frequency of the microwave heating apparatus. An electromagnetic wave sensor was used for these measurements. A loop antenna was used for the electromagnetic wave sensor. The temperature rose continuously, and the rapid temperature rise due to the spark of the conductive paste, which is a concern in dielectric heating, did not occur in magnetic field heating. As a result of measuring the temperature distribution of the entire paste application part during heating using the thermal image measuring device 41, it was confirmed that the paste was heated uniformly (FIG. 8). Moreover, in the external appearance of each test piece before the magnetic field heating shown in FIG. 9 (see FIG. (A)) and after the heating (see FIG. (B)), no abnormally heated portion due to spark was found.

[Comparative Example 7]
In Comparative Example 7, a measurement sample similar to that in Example 7 was produced. Table 3 shows the results obtained by heating the measurement sample in an electric furnace at 130 ° C. for 5 minutes and 30 minutes and measuring the electrical resistivity at five locations within the paste coating surface.

  The electrical resistivity of the measurement sample subjected to microwave magnetic field heating shows almost the same value at all five locations, and it can be said that the entire coated surface is heated uniformly. Compared with the result of the electric furnace heating, it can be seen that the test piece by magnetic field heating can lower the electrical resistivity (can increase the conductivity) and is excellent in heating efficiency.

[Comparative Example 8]
In Comparative Example 8, a conductive silver paste (product name REXALPHA, manufactured by Toyochem Co., Ltd.) was applied to quartz glass in a size of 15 mm × 4 mm and a thickness of 0.05 mm to obtain a measurement sample. Was placed in the center of the cavity resonator applied after 10 minutes (including the center axis C), it was subjected to dielectric heating to form a standing wave of TM ₀₁₀ mode. FIG. 10 shows changes in the temperature of the paste application part during heating, and changes in the incident wave, reflected wave, and resonance frequency of the microwave heating apparatus. The temperature rose to about 60 ° C., and then gradually decreased, and the resonance frequency increased as the temperature decreased. The electrical resistivity of the test piece after 100 seconds of dielectric heating was 0.13 Ω · cm, and it was confirmed that the conductivity was inferior compared to magnetic field heating. In the dielectric heating of the conductive paste, it is considered that the microwave absorption decreases as the conductivity increases, and heating becomes difficult.

[Example 9-11]
Silicon substrate used as a semiconductor material (Product name: High purity chemical research laboratory product name: Silicon, 10 mm × 10 mm, thickness 1 mm), Gallium nitride substrate (Product name: High purity chemical research laboratory product name: Gallium nitride, 10 mm × 10 mm, thickness) 2 mm) and an aluminum nitride substrate (product name: aluminum nitride (columnar shape), diameter 10 mm, thickness 2 mm, manufactured by High Purity Chemical Laboratory) were heated using the microwave heating apparatus 1 shown in FIG. For the main heating, the supply unit 31 shown in FIG. 1 is not used, and a polyimide film (thickness: 125 μm) for holding the substrate to be heated is installed at the same position as the sheet (heated object) 6. . Note that the polyimide film is neither a magnetic material nor a conductive material, so that heating by microwaves does not occur. The substrate was placed on the polyimide film so as to coincide with the center axis position of the cavity resonator 11, and predetermined microwave power was supplied from the microwave supply port 14 so as to form a TM ₁₁₀ mode standing wave. The implementation conditions and results are shown in Table 4. Moreover, FIG. 11 shows the result of having measured the surface temperature of the board | substrate when microwave power 100W is supplied to a silicon substrate with the radiation thermometer (The Japan sensor, TMHX-CN0500). It was found that after 30 seconds from 30 ° C., heating to 300 ° C. was possible. This indicates that the heating operation of the semiconductor material is appropriate. Similarly, a gallium nitride substrate can be heated to 300 ° C. after 30 seconds from 30 ° C. by irradiation with 100 W microwave, and an aluminum nitride substrate can be heated to 56 ° C. after 30 seconds to 300 seconds by irradiation with 100 W microwave. I was able to.

1 Microwave heating device 6 Sheet (object to be heated)
11 Cavity resonator 12 Supply port 13 Discharge port 14 Microwave supply port (coaxial waveguide converter type microwave supply port)
DESCRIPTION OF SYMBOLS 21 Microwave generator 22 Microwave amplifier 23 Isolator 24 Matching device 25 Antenna 26 Cable 31 Supply part 31A Supply side conveyance part 31B Delivery side conveyance part 41 Thermal image measuring device 42, 45, 46 Cable 42 Controller 44 Electromagnetic wave sensor C Sky Trunk center axis (center axis)

Claims (11)

A cavity resonator serving as a microwave irradiation space of a cylindrical tube or a polygonal tube type in which two surfaces facing each other centering on a tube center axis excluding a tube shape having a rectangular cross section perpendicular to the tube center axis;
In a space where the energy distribution of the magnetic field in the cavity is uniform, the object to be heated of a magnetic substance, a magnetic loss material or a conductive material, or a magnetic substance, a magnetic loss material or a conductivity A supply unit that supplies an object to be heated of a composite material including a certain material through a magnetic field irradiation space in which the magnetic field strength of the cavity resonator is maximized and uniform;
The microwave heating apparatus which heats the said to-be-heated object supplied by the said supply part in the said magnetic field irradiation space.   2. The microwave heating apparatus according to claim 1, wherein when the object to be heated passes through the microwave irradiation space, the supply unit passes the object to be heated through a space having a minimum electric field intensity. The standing wave formed inside the microwave irradiation space is TM ₁₁₀ mode,
The microwave heating apparatus according to claim 1 or 2, wherein the magnetic field irradiation space is a space along a cylinder central axis of the cavity resonator. The means for forming a standing wave of the TM ₁₁₀ mode is configured to maintain a uniform magnetic field distribution state along the central axis of the cylinder in a state where an object to be heated is inserted in the microwave irradiation space. The microwave heating device according to claim 3, further comprising a mechanism for controlling a wave frequency. The mechanism for controlling the frequency of the microwave detects a resonance frequency that matches the standing wave of the TM ₁₁₀ mode that varies according to the insertion state of the object to be heated, and irradiates the microwave that matches the resonance frequency The microwave heating device according to claim 4. The means for detecting the resonant frequency that matches the standing wave of the TM ₁₁₀ mode has a mechanism for measuring the reflected wave from the microwave irradiation space, and the frequency at which the reflected wave is minimized based on the measurement signal. The microwave heating apparatus according to claim 5, further comprising a mechanism for controlling a frequency of the microwave for detecting a resonance frequency. The means for detecting the resonance frequency that matches the standing wave of the TM ₁₁₀ mode has a mechanism for measuring the energy state in the microwave irradiation space, and the energy in the microwave irradiation space based on the measurement signal. The microwave heating apparatus according to claim 5, further comprising a mechanism for controlling a frequency of the microwave for detecting a resonance frequency from a frequency at which the density is maximized.   8. The heating object according to claim 1, wherein an induction current is generated in the object to be heated by applying a maximum magnetic field on the cylindrical center axis of the cavity resonator, and the object to be heated is heated. The microwave heating apparatus as described.   The microwave heating device according to any one of claims 1 to 8, wherein the microwave heating device is a chemical reaction device that heats the object to be heated by microwaves to cause a chemical reaction.   The heating method using the microwave heating device of any one of Claims 1-9.   A chemical reaction method using the microwave heating apparatus according to claim 1, wherein the chemical reaction method includes causing a chemical reaction by heating the object to be heated.