Microwave heating system and microwave heating method

Abstract

The frequency f of the microwaves irradiated onto the object to be heated (20) inside the cylindrical cavity resonator (320) is the intermediate frequency fm. The intermediate frequency fm is higher than the lower frequency fb and lower than the upper frequency ft. The lower frequency fb is the frequency within the cylindrical cavity resonator (320) where the object to be heated (20) is located. 0n0 The frequency at which the mode's standing wave is formed is the upper frequency ft within the cylindrical cavity resonator (320) where the object being heated (20) is located. 0n1 This is the frequency at which the mode forms a standing wave. n is a natural number greater than or equal to 1.

Description

Technical Field

[0001] The present invention relates to a microwave heating system and a microwave heating method.

Background Art

[0002] In a microwave heating device, an object to be heated is heated by microwaves. In the microwave heating device described in Patent Document 1, the object to be heated is heated by forming a standing wave in a cylindrical cavity resonator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention provides a technique suitable for uniformly heating an object to be heated.

Means for Solving the Problems

[0005] The present invention includes a cylindrical cavity resonator, in the cylindrical cavity resonator, the object to be heated is irradiated with microwaves, the frequency of the microwaves is an intermediate frequency, the intermediate frequency is a frequency higher than a lower frequency and lower than an upper frequency, the lower frequency is a frequency at which a standing wave of the TM 0n0 mode is formed in the cylindrical cavity resonator where the object to be heated exists, the upper frequency is a frequency at which a standing wave of the TM 0n1 mode is formed in the cylindrical cavity resonator where the object to be heated exists, n is a natural number of 1 or more, We provide microwave heating systems. [Effects of the Invention]

[0006] The technology according to the present invention is suitable for uniformly heating an object to be heated. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a diagram showing the configuration of a microwave heating system according to an embodiment. [Figure 2A] Figure 2A is a top view illustrating the first and second objects to be heated. [Figure 2B] Figure 2B is a cross-sectional view illustrating the second object being heated. [Figure 3A] Figure 3A is a schematic cross-sectional view of a microwave heating apparatus. [Figure 3B] Figure 3B is a schematic diagram of a waveguide and cavity. [Figure 4] Figure 4 is a top view of the M-sized cylindrical cavity resonator. [Figure 5] Figure 5 is a contour map showing the distribution of electric field intensity in the cavity containing the object being heated, for the first, second, and third examples. [Figure 6] Figure 6 is a graph showing the distribution of electric field intensity along the central axis of the cavity containing the object being heated, for the first, second, and third examples. [Figure 7] Figure 7 is a contour plot showing the change in the distribution of electric field intensity in the cavity containing the object being heated when the frequency is varied. [Figure 8] Figure 8 is a graph illustrating the accuracy of the simulation. [Figure 9A] Figure 9A is a contour plot showing the electric field intensity distribution for Example X1, Comparative Example Y1, and Comparative Example Z1. [Figure 9B] Figure 9B is a graph showing the relationship between the position in the second direction and the electric field intensity for Example X1, Comparative Example Y1, and Comparative Example Z1. [Figure 10A]Figure 10A is a contour plot showing the electric field intensity distribution for Example X2 and Comparative Example Y2. [Figure 10B] Figure 10B is a graph showing the relationship between the position in the second direction and the electric field intensity for Example X2 and Comparative Example Y2. [Figure 11A] Figure 11A is a contour plot showing the electric field intensity distribution for Example X3 and Comparative Example Y3. [Figure 11B] Figure 11B is a graph showing the relationship between the position in the second direction and the electric field intensity for Example X3 and Comparative Example Y3. [Figure 12A] Figure 12A is a contour plot showing the electric field intensity distribution for Example X4, Comparative Example Y4, and Comparative Example Z4. [Figure 12B] Figure 12B is a graph showing the relationship between the position in the second direction and the electric field intensity for Example X4, Comparative Example Y4, and Comparative Example Z4. [Figure 13A] Figure 13A is a contour plot showing the electric field intensity distribution for Example X5, Comparative Example Y5, and Comparative Example Z5. [Figure 13B] Figure 13B is a graph showing the relationship between the position in the second direction and the electric field intensity for Example X5, Comparative Example Y5, and Comparative Example Z5. [Figure 14A] Figure 14A is a contour plot showing the electric field intensity distribution for Example X6, Comparative Example Y6, and Comparative Example Z6. [Figure 14B] Figure 14B is a graph showing the relationship between the position in the second direction and the electric field intensity for Example X6, Comparative Example Y6, and Comparative Example Z6.

[0008] The embodiments of the present invention will be described below with reference to the attached drawings, but the following are merely illustrative examples of embodiments of the present invention and are not intended to limit the present invention.

[0009] [Embodiment] Figure 1 is a diagram showing the configuration of the microwave heating system 1A according to an embodiment.

[0010] In Figure 1, the first direction D1, the second direction D2, and the third direction D3 are shown. In this embodiment, the first direction D1 is the MD (Machine Direction). The second direction D2 is the TD (Transverse Direction). The third direction D3 is the VD (Vertical Direction). The first direction D1, the second direction D2, and the third direction D3 are mutually orthogonal directions.

[0011] As shown in Figure 1, the microwave heating system 1A includes a conveying device 70, a coating device 200, and a microwave heating device group 600. The conveying device 70 includes a feed roller 100 and a winding roller 400. In the microwave heating system 1A, a conveying path 50 is configured in which the feed roller 100, coating device 200, microwave heating device group 600, and winding roller 400 appear in this order.

[0012] The dispensing roller 100 dispenses the object to be heated S from the roll of the object to be heated. The coating device 200 coats the object to be heated S. The microwave heating device group 600 heats the object to be heated S. The winding roller 400 winds the object to be heated S to form a roll of the wound object to be heated S. In this embodiment, the object to be heated S is conveyed along the conveying path 50 in a roll-to-roll manner, and coating and heating are performed on the object to be heated S in this order while it is being conveyed.

[0013] In this embodiment, when the object to be heated S is coated in the coating apparatus 200 and heated in the microwave heating apparatus group 600, its transport direction is parallel to the first direction D1, its longitudinal direction is parallel to the first direction D1, its short direction is parallel to the second direction D2, and its thickness direction is parallel to the third direction D3.

[0014] The following describes in detail the object to be heated S, the conveying device 70, the coating device 200, and the microwave heating device group 600.

[0015] <1. Heated object S> The object to be heated S has a first configuration upstream of the coating device 200 in the transport path 50. The object to be heated S has a second configuration downstream of the coating device 200 in the transport path 50. The first configuration is the configuration of the object to be heated S before coating by the coating device 200. The second configuration is the configuration of the object to be heated S after coating by the coating device 200.

[0016] Hereinafter, an object to be heated S having the first configuration will be referred to as the first object to be heated 10. An object to be heated S having the second configuration will be referred to as the second object to be heated 20.

[0017] Figure 2A is a top view illustrating the first object to be heated 10 and the second object to be heated 20. Figure 2B is a cross-sectional view illustrating the second object to be heated 20.

[0018] The first object to be heated 10 is a single layer of the base material 11.

[0019] The second object to be heated 20 is a laminate. The second object to be heated 20 includes a base material 11 and a film 21. The film 21 is located on the base material 11.

[0020] In this embodiment, the base material 11 is a resin film. Specifically, the base material 11 is a polyethylene terephthalate (PET) film. Alternatively, the base material may be a nonwoven fabric.

[0021] The film 21 is an adhesive film. Specifically, the adhesive is an acrylic adhesive. Here, an acrylic adhesive is an adhesive containing acrylic resin. The adhesive is also called a pressure-sensitive adhesive layer. The adhesive can stably maintain a wet state.

[0022] In this embodiment, the dimensions of the base material 11 with respect to the second direction D2 (hereinafter referred to as width W11) are 200 mm or more and 2000 mm or less. Specifically, the width W11 is 250 mm or more and 1400 mm or less.

[0023] In this embodiment, the dimensions of the substrate 11 with respect to the third direction D3 (hereinafter referred to as thickness T11) are 10 μm or more and 300 μm or less. Specifically, the thickness T11 is 15 μm or more and 100 μm or less.

[0024] Typically, the dimension of the film 21 with respect to the second direction D2 (hereinafter referred to as width W21) is smaller than the width W11. In this embodiment, the width W21 is between 195 mm and 1995 mm. Specifically, the width W21 is between 245 mm and 1395 mm.

[0025] In this embodiment, the dimensions (hereinafter referred to as thickness T21) of the film 21 immediately after coating by the coating apparatus 200 in the third direction D3 are 1 μm or more and 300 μm or less. Specifically, thickness T21 is 10 μm or more and 250 μm or less. More specifically, thickness T21 is 10 μm or more and 120 μm or less. Even more specifically, thickness T21 is 10 μm or more and 100 μm or less. Thickness T21 is also called the initial coating thickness.

[0026] In this embodiment, the dimensions of the first object to be heated 10 with respect to the second direction D2 are 200 mm or more and 2000 mm or less, specifically 250 mm or more and 1400 mm or less. The dimensions of the first object to be heated 10 with respect to the third direction D3 are 10 μm or more and 300 μm or less, specifically 15 μm or more and 100 μm or less.

[0027] In this embodiment, the dimensions of the second object to be heated 20 with respect to the second direction D2 are 200 mm or more and 2000 mm or less, specifically 250 mm or more and 1400 mm or less. There is a period in which the dimensions of the second object to be heated 20 with respect to the third direction D3 are 11 μm or more and 600 μm or less, specifically 25 μm or more and 350 μm or less.

[0028] In this embodiment, the object to be heated S, the first object to be heated 10, and the second object to be heated 20 are long sheets. Here, a long sheet is a sheet whose length in the transport direction is longer than the cylindrical cavity resonator 320 described later. However, the forms of the objects to be heated S, the first object to be heated 10, and the second object to be heated 20 are not particularly limited. Another example of the objects to be heated S, the first object to be heated 10, and the second object to be heated 20 is a single sheet. A single sheet may have a length in the transport direction that is less than the cylindrical cavity resonator 320 described later.

[0029] <2. Conveying device 70> The conveying device 70 conveys the object to be heated S. Specifically, the conveying device 70 conveys the object to be heated S to the cavity 370 in the cylindrical cavity resonator 320, which will be described later. The feed roller 100 feeds out the object to be heated S so that it is conveyed along the conveying path 50. The winding roller 400 winds up the object to be heated S so that it is conveyed along the conveying path 50.

[0030] The conveying device 70 specifies the speed (hereinafter referred to as the conveying speed) of the object to be heated S being conveyed along the conveying path 50. The conveying speed is, for example, 0.1 m / min or more and 200 m / min or less.

[0031] The conveying device 70 specifies the tension applied to the object to be heated S as it is conveyed along the conveying path 50. The tension applied to the object to be heated S per unit width (hereinafter referred to as the conveying tension) as it is conveyed along the conveying path 50 is, for example, 10 N / m or more and 200 N / m or less. In this context, "unit width of the object to be heated S" is the unit length of the object to be heated S in a direction perpendicular to the conveying direction and the thickness direction of the object to be heated S.

[0032] <Coating machine 200> The coating apparatus 200 forms the second object to be heated 20 from the first object to be heated 10. Specifically, the coating apparatus 200 forms a film 21 on the substrate 11 by applying a coating liquid to the substrate 11. In other words, the film 21 is a coating film. Hereafter, the film 21, which is a coating film, may be referred to as the coating film 21.

[0033] In this embodiment, the coating liquid contains water as a solvent or dispersion medium. The coating liquid does not contain an organic compound as a solvent or dispersion medium. The coating liquid contains a resin as a solute or dispersed phase. Specifically, the resin is an acrylic resin. Specifically, in this embodiment, the coating liquid contains water as a dispersion medium, does not contain an organic compound as a dispersion medium, and contains a resin (specifically an acrylic resin) as a dispersed phase. The film 21 is a film of emulsion adhesive.

[0034] The solid content concentration in the coating solution is determined so that a film 21 can be formed. In this embodiment, the solid content concentration is 10% by weight or more and 80% by weight or less. Specifically, the solid content concentration is 10% by weight or more and 60% by weight or less.

[0035] <3. Microwave heating equipment group 600> The microwave heating device group 600 includes multiple microwave heating devices 300. Figure 3A is a schematic cross-sectional view of the microwave heating device 300.

[0036] The microwave heating apparatus 300 includes a microwave source 305, a waveguide 310, a cylindrical cavity resonator 320, a microwave detector 380, and a control device 385. The waveguide 310 is coupled to the cylindrical cavity resonator 320. The cylindrical cavity resonator 320 may also include a microwave coupler.

[0037] In this embodiment, the expression "cylindrical cavity resonator" refers to a resonator that operates based on the principle of a cylindrical cavity resonator. The expression "cylindrical cavity resonator" is not intended to require that the shape of the resonator be strictly cylindrical. Similarly, the expression "cylindrical cavity 370" described later is not intended to require that the shape of the cavity 370 be strictly cylindrical. The same applies to the "cylindrical surface" described later.

[0038] Waveguide 310 has a waveguide 311 inside it. Cylindrical cavity resonator 320 has an inlet opening 343. The inlet opening 343 is also called an iris. Furthermore, cylindrical cavity resonator 320 has a cavity 370 inside it that communicates with the inlet opening 343. The second object to be heated 20 is heated in the cavity 370. In this embodiment, waveguide 310 is a rectangular waveguide, and waveguide 311 is a rectangular waveguide. Cavity 370 has a cylindrical shape. Figure 3B is a schematic diagram of waveguide 311 and cavity 370.

[0039] As shown in Figure 3A, the second object to be heated 20 passes through the cavity 370. Microwaves are introduced into the cavity 370 from the waveguide 311 through the introduction aperture 343. In this way, microwaves are irradiated onto the second object to be heated 20 in the cavity 370 within the cylindrical cavity resonator 320, and the second object to be heated 20 is heated.

[0040] Specifically, in the cavity 370 within the cylindrical cavity resonator 320, microwaves are irradiated onto the second object to be heated 20, causing dielectric heating of the dielectric material contained in the second object to be heated 20. The relative permittivity of the dielectric material at 2.45 GHz is, in one example, between 1 and 85, and in one specific example, between 2 and 85.

[0041] Specifically, the second object to be heated 20 contains water as a dielectric. The water is the water in the coating solution. When microwaves are irradiated onto the second object to be heated 20, the water is heated, the water evaporates, and the second object to be heated 20 is dried. Thus, the microwave heating according to this embodiment is for the purpose of drying.

[0042] Microwaves can efficiently evaporate water. This can reduce the energy required to dry the second object to be heated 20 and contribute to reducing the amount of carbon dioxide produced during the drying of the second object to be heated 20.

[0043] In this embodiment, microwaves are irradiated onto the second object to be heated 20 while it is being transported by the transport device 70 inside the cylindrical cavity resonator 320. This improves the productivity of the product obtained after heating the second object to be heated 20. However, in cases where the second object to be heated 20 is a single sheet, the transport of the second object to be heated 20 by the transport device 70 may be temporarily stopped when the second object to be heated 20 is transported inside the cylindrical cavity resonator 320, and microwaves may be irradiated onto the second object to be heated 20 during this stop.

[0044] The microwave source 305, waveguide 310, cylindrical cavity resonator 320, microwave detector 380, and control device 385 will be described further below.

[0045] <3-1. Microwave source 305 and waveguide 310> In this embodiment, the waveguide 310 is connected to the microwave source 305. The waveguide 310 has an input port 313. Microwaves are introduced into the waveguide 311 from the microwave source 305 via the input port 313.

[0046] Hereinafter, the microwave power supplied to the waveguide 311 within the waveguide 310 will be denoted as microwave power Pi. Microwave power Pi is, for example, between 1W and 10kW. In one numerical example, microwave power Pi is 200W. In another numerical example, microwave power Pi is 3kW.

[0047] Hereinafter, the frequency of the microwaves introduced into the waveguide 311 within the waveguide 310 will be denoted as frequency f. Frequency f is, for example, between 13 MHz and 6 GHz. In this embodiment, frequency f is between 2.4 GHz and 2.5 GHz. In another example, frequency f is between 902 MHz and 928 MHz.

[0048] In this embodiment, the power of the microwaves output from the microwave source 305 is the microwave power Pi plus the losses in the microwave path from the microwave source 305 to the waveguide 311. In this embodiment, the frequency of the microwaves output from the microwave source 305 is the same as frequency f. Also, the frequency of the microwaves irradiated onto the object to be heated 20 is the same as frequency f.

[0049] The microwave source 305 may output microwaves of a constant power or microwaves of a variable power. In this embodiment, the microwave source 305 is capable of outputting microwaves of a variable frequency. However, the microwave source 305 may also output microwaves of a constant frequency.

[0050] In this embodiment, the microwave source 305 includes a semiconductor solid-state element. The microwave source may also include a magnetron. The microwave source 305 may include a VCO (Voltage-Controlled oscillator), a VCXO (Voltage-Controlled Crystal Oscillator), or a PLL (Phase-Locked Loop) oscillator. The microwave source 305 may also include an amplifier.

[0051] The waveguide 311 is partitioned by the inner surface 315 of the waveguide 310. In this embodiment, when A partitions B, it means that A partitions B by itself, or that A partitions B in cooperation with one or more other elements.

[0052] <3-2. Cylindrical cavity resonator 320> As shown in Figure 3A, the cylindrical cavity resonator 320 includes walls 330. The walls 330 function as side walls surrounding the cavity 370.

[0053] The wall 330 has an inner circumferential surface 335. The cavity 370 is partitioned by the inner circumferential surface 335. Hereafter, the term "central axis 390 of the inner circumferential surface 335" may be used. The central axis 390 of the inner circumferential surface 335 is a hypothetical central axis for explanatory purposes and does not necessarily have to exist in reality. In this embodiment, the central axis 390 does not actually exist.

[0054] Furthermore, the expression "axial Da of the inner circumferential surface 335" may be used below. The axial Da is the direction in which the central axis 390 extends. In this embodiment, the axial Da is equal to the second direction D2.

[0055] Microwaves are introduced into the cylindrical cavity resonator 320 from inside the waveguide 310 via the introduction aperture 343. Specifically, microwaves are introduced into the cavity 370 from the waveguide 311 via the introduction aperture 343.

[0056] In this embodiment, the diameter of the cylindrical cavity 370 is between 80 mm and 300 mm. Specifically, this diameter is between 85 mm and 260 mm.

[0057] In this embodiment, the axial dimension Da of the cavity 370 is between 250 mm and 2050 mm. Specifically, this dimension is between 300 mm and 1500 mm.

[0058] The material of wall 330 is preferably a material with good electrical conductivity.

[0059] In one example, the wall 330 is made of metal. The metal may be, for example, aluminum, copper, iron, magnesium, brass, stainless steel, or an alloy thereof. Preferably, the metal is aluminum, copper, magnesium, brass, or an alloy thereof. In another example, the wall 330 may be made of resin, ceramic, metal, etc., and its inner surface 335 is coated. Materials containing silver, copper, gold, tin, or rhodium can be used for the coating.

[0060] As shown in Figure 3A, the wall 330 is provided with a first through-hole 351 and a second through-hole 361. The first through-hole 351 and the second through-hole 361 penetrate the wall 330. Thus, the wall 330 is provided with a pair of through-holes 351 and 361.

[0061] The transport path 50 (see Figure 1) passes through the cylindrical cavity resonator 320. Specifically, the transport path 50 passes through the first through-hole 351, the cavity 370, and the second through-hole 361 in the cylindrical cavity resonator 320 in that order. In the cylindrical cavity resonator 320, the first through-hole 351, the cavity 370, and the second through-hole 361 are in communication in this order.

[0062] As can be understood from the above explanation, the second object to be heated 20 is supplied into the cylindrical cavity resonator 320. Inside the cylindrical cavity resonator 320, the second object to be heated 20 is heated by microwaves.

[0063] In this embodiment, the second object to be heated 20 is transported along the transport path 50 by the transport device 70 so that it passes through the first through-hole 351, the cavity 370, and the second through-hole 361 in the cylindrical cavity resonator 320 in that order. While this transport is taking place, the second object to be heated 20 is irradiated by microwaves in the cavity 370 of the cylindrical cavity resonator 320, with one or more portions of the second object to be heated protruding from the cylindrical cavity resonator 320. As a result, the second object to be heated 20 is heated. Thus, in this embodiment, it is possible to heat the second object to be heated 20, which is longer than the cavity 370. Specifically, while the above-described transport is taking place, the second object to be heated 20 has multiple portions that protrude from the cylindrical cavity resonator 320, and the second object to be heated 20 is irradiated with microwaves in the cavity 370 within the cylindrical cavity resonator 320. The multiple portions include the portion upstream of the microwave heating device 300 in the transport path 50 and the portion downstream of the microwave heating device 300 in the transport path 50.

[0064] In this embodiment, the second object to be heated 20 is suspended in the first through-hole 351, the cavity 370, and the second through-hole 361 within the cylindrical cavity resonator 320. Specifically, tension is applied to the second object to be heated 20 so that it is separated from the wall 330, and the second object to be heated 20 is suspended in this state, while the second object to be heated 20 is irradiated with microwaves in the cavity 370 within the cylindrical cavity resonator 320. Here, the phrase "the second object to be heated 20 is suspended in the air" is intended to encompass both the state in which the second object to be heated 20 is bent due to gravity and the state in which the second object to be heated 20 is taut and straight.

[0065] As described above, tension can be applied by the conveying device 70. Supports may be provided upstream and / or downstream of the cylindrical cavity resonator 320 in the conveying path 50, and the second object to be heated 20 may be supported by the supports while tension is applied to the second object to be heated 20 to suspend it in mid-air. With this configuration, it is easier to make the electric field inside the cylindrical cavity resonator 320 uniform compared to a configuration in which the support is inside the cylindrical cavity resonator 320. However, the support may also be provided inside the cylindrical cavity resonator 320. The support, together with the feed roller 100 and the winding roller 400, constitutes the conveying device 70. The support is, for example, a support roll, a support belt, etc.

[0066] Hereinafter, the circumferential direction of the inner surface 335 will be referred to as the fourth direction D4. In this embodiment, with respect to the fourth direction D4, the introduction opening 343 is located in the central part of the region when the area between the pair of through holes 351 and 361 is divided into five parts. Specifically, with respect to the fourth direction D4, the introduction opening 343 is located at a position that divides the area between the pair of through holes 351 and 361 into two equal parts.

[0067] <3-3. Microwave detector 380 and control device 385> An insertion hole (not shown) is provided in the wall 330 of the cylindrical cavity resonator 320. A microwave detector 380 is inserted into the cavity 370 through the insertion hole. The microwave detector 380 detects microwaves at the location of the microwave detector 380 in the cavity 370. In this embodiment, the microwave detector 380 is an antenna.

[0068] In the example shown in Figure 3B, an insertion hole is provided in the region of one of the end divisions when the cavity 370 is divided into three sections along the axial direction Da, and the microwave detector 380 is inserted into this insertion hole. Inserting the microwave detector 380 at the end of the cavity 370 along the axial direction Da is advantageous from the viewpoint of suppressing disturbances in the electric field within the cavity 370 caused by the microwave detector 380. However, the insertion hole may also be provided in the region of the central division when the cavity 370 is divided into three sections along the axial direction Da, and the microwave detector 380 may be inserted into this insertion hole.

[0069] The control device 385 determines the microwave power Ps at the location of the microwave detector 380 in the cavity 370 based on the detection results of the microwave detector 380. The control device 385 also controls the frequency f of the microwaves introduced into the waveguide 311 within the waveguide 310 based on the detection results of the microwave detector 380. Details of the microwave frequency control will be described later.

[0070] <3-4. Microwave heating equipment group 600> As described above, in this embodiment, a microwave heating device group 600 is configured using multiple microwave heating devices 300. Each microwave heating device 300 in the microwave heating device group 600 heats the object to be heated S, specifically the second object to be heated 20.

[0071] In this embodiment, the microwave heating device group 600 includes M microwave heating devices 300. The microwave heating device group 600 also includes M cylindrical cavity resonators 320. In this embodiment, the M cylindrical cavity resonators 320 have the same shape and dimensions, and their axial Da are aligned. M is a natural number of 2 or more. In one example, M is between 2 and 40.

[0072] Figure 4 is a top view of the M-sized cylindrical cavity resonators 320. The M-sized cylindrical cavity resonators 320 are arranged at intervals i. In one example, the interval i is between 100 mm and 500 mm.

[0073] In the microwave heating system 1A, a transport path 50 is configured that penetrates the walls 330 of the M-sized cylindrical cavity resonators 320 and passes through the inside of the M-sized cylindrical cavity resonators 320. The transport device 70 sequentially transports the second object to be heated 20 into the M-sized cylindrical cavity resonators 320 along the transport path 50. Inside the M-sized cylindrical cavity resonators 320, the second object to be heated 20 is heated by microwaves introduced from the introduction opening 343.

[0074] Specifically, in each of the M cylindrical cavity resonators 320, microwaves are introduced into the cavity 370 inside the cylindrical cavity resonator 320 from the introduction opening 343. The walls 330 of each of the M cylindrical cavity resonators 320 are provided with an inner circumferential surface 335 that partitions the cavity 370, and a pair of through holes 351 and 361. In the transport path 50, the arrangement of the first through hole 351, cavity 370, and second through hole 361, which communicate with each other, is arranged in series for the M units. The transport device 70 transports the second object to be heated 20 along the transport path 50. In this way, the transport device 70 sequentially transports the second object to be heated 20 into the cavity 370 of the M cylindrical cavity resonators 320 by passing the second object to be heated 20 through the pair of through holes 351 and 361 of the M cylindrical cavity resonators 320.

[0075] <4. Microwave frequency> As described above, within the cylindrical cavity resonator 320, the object to be heated 20 is irradiated with microwaves of frequency f. In this embodiment, frequency f is the intermediate frequency fm. The intermediate frequency fm is higher than the lower frequency fb and lower than the upper frequency ft. The lower frequency fb is within the cylindrical cavity resonator 320 where the object to be heated 20 is located TM 0n0 This is the frequency at which the mode's standing wave is formed. The upper frequency ft is the frequency within the cylindrical cavity resonator 320 where the object being heated 20 is located.0n1 It is the frequency that forms the standing wave of the mode. n is a natural number of 1 or more. This configuration is suitable for uniformly heating the object to be heated 20. Hereinafter, the reason will be described while referring to FIGS. 5 to 7.

[0076] In the following description, the electric field strength En is the strength of the electric field E. The unit of the electric field strength En is V / m. Specifically, the electric field strength En is given by the following formula 1 using the component E1 in the first direction D1 of the electric field E, the component E2 in the second direction D2 of the electric field E, and the component E3 in the third direction D3 of the electric field E. Formula 1: En = (E1 2 + E2 2 + E3 2 ) 1 / 2

[0077] Also, in the following description of the embodiment, the transmission intensity S21 represents the transmission of microwaves from the input port 313 in the waveguide 310 to the position of the microwave detector 380 in the cavity 370. Specifically, the transmission intensity S21 is given by the following formula 2. As described above, the microwave power Pi is the power of the microwaves input into the waveguide 311 in the waveguide 310. The power Ps is the power of the microwaves at the position of the microwave detector 380 in the cavity 370. Formula 2: Transmission intensity S21 = 10 * log 10 (Ps / Pi)

[0078] FIG. 5 is a contour diagram showing the distribution of the electric field strength En in the cavity 370 where the object to be heated exists according to the first example, the second example, and the third example. FIG. 6 is a graph showing the distribution of the electric field strength En on the central axis 390 of the cavity 370 where the object to be heated exists according to the first example, the second example, and the third example. In the graph of FIG. 6, the electric field strength En is normalized by the value at the center in the axial direction Da.

[0079] The first example, the second example, and the third example are TM in the cavity 370 0n0They are similar in that standing waves of the modes are formed. However, the objects to be heated placed in the cavity 370 differ in the first, second, and third examples.

[0080] In the first example shown in Figure 5(A), an object to be heated 10 is placed in the cavity 370 instead of the object to be heated 20. The object to be heated 10 does not include the film 21. In the first example, the uniformity of the electric field strength En in the cavity 370 with respect to the axial direction Da is high.

[0081] In the second example shown in Figure 5(B), the object to be heated 20 is placed in the cavity 370. The film 21 on the object to be heated 20 is a thin film containing a dielectric. Specifically, the dielectric is water. In the second example, the uniformity of the electric field strength En in the cavity 370 with respect to the axial direction Da is lower than in the first example.

[0082] In the third example shown in Figure 5(C), the object to be heated 20 is placed in the cavity 370. The film 21 of the object to be heated 20 is a thick film containing a dielectric. Specifically, the dielectric is water. In the third example, the water content of the film 21 is higher than in the second example. In the third example, the uniformity of the electric field strength En in the cavity 370 with respect to the axial direction Da is lower than in the second example.

[0083] As can be seen from Figures 5 and 6, in cavity 370 TM 0n0 When a mode standing wave is formed, the dielectric in the film 21 may worsen the uniformity of the electric field strength En in the cavity 370 with respect to the axial Da. When uniformity worsens, regions with excessive electric field strength En and regions with insufficient electric field strength En may occur. If the dielectric is water, foaming of the film 21 may occur in regions with excessive electric field strength En, and insufficient drying of the film 21 may occur in regions with insufficient electric field strength En.

[0084] Figure 7 is a contour plot showing the change in the distribution of electric field strength En in the cavity 370 containing the object being heated 20 when the frequency f is varied. The film 21 of the object being heated 20 contains a dielectric. Specifically, the dielectric is water.

[0085] In Figure 7(A), the frequency f is relatively low, and TM occurs in cavity 370. 0n0 The standing waves of the mode are shown. In Figure 7(C), the frequency f is relatively high, and TM is present in cavity 370. 0n1 The standing wave of the mode is shown. In Figure 7(B), the frequency f is between the cases of (A) and (B), and TM is present in cavity 370. 0n0 Mode and TM 0n1 This shows how a hybrid electric field is formed with modes.

[0086] In cavity 370 TM 0n0 By forming a mode standing wave, the transmission intensity S21 can be increased. However, as can be seen from Figure 7, when the dielectric is present in the cavity 370, TM 0n0 In mode, the electric field strength En in cavity 370 is greater near the center of the axial direction Da. On the other hand, TM 0n1 In this mode, the electric field strength En in cavity 370 is greater at both ends of the axial direction Da. TM 0n0 Mode and TM 0n1 By forming an electric field where modes are mixed, it is possible to make the electric field intensity En in the cavity 370 uniform with respect to the axial Da.

[0087] In this embodiment, the microwave detector 380 detects microwaves within the cylindrical cavity resonator 320. The control device 385 identifies the lower frequency fb and upper frequency ft based on the detection results of the microwave detector 380. The control device 385 identifies the intermediate frequency fm based on the identified lower frequency fb and upper frequency ft. In this way, it is possible to change the intermediate frequency fm according to the amount of water contained in the object to be heated 20, for example. For example, the lower frequency fb and upper frequency ft can be determined by connecting an analyzer to the microwave detector 380 and using the analyzer to obtain TM 0n0 Mode resonant frequency and TM 0n1The resonant frequencies of the modes can be identified by searching for them. The analyzer is, for example, a network analyzer. The analyzer may be included in the control unit 385. The lower frequency fb and upper frequency ft can also be identified before operating the microwave heating system 1A by simulating the cylindrical cavity resonator 320 in an electromagnetic wave simulation tool.

[0088] In this embodiment, n is 1. However, n may be 2, or 3 or more.

[0089] In this embodiment, the microwave source 305 includes a semiconductor solid-state element. A microwave source based on a semiconductor solid-state element is advantageous compared to a microwave source based on a magnetron or the like in terms of being able to finely control the frequency of microwaves output from the microwave source.

[0090] In this embodiment, the M-unit microwave heating apparatus 300 includes a first microwave heating apparatus 300A and a second microwave heating apparatus 300B. The cylindrical cavity resonator 320 of the first microwave heating device 300A will be referred to as the first cylindrical cavity resonator 320A. The frequency of the microwaves irradiated onto the object to be heated 20 in the first cylindrical cavity resonator 320A is referred to as the first microwave. The frequency f of the first microwave is denoted as frequency f1. The cylindrical cavity resonator 320 of the second microwave heating device 300B will be referred to as the second cylindrical cavity resonator 320B. The microwaves irradiated onto the object to be heated 20 in the second cylindrical cavity resonator 320B are referred to as the second microwaves. The frequency f of the second microwave is denoted as frequency f2.

[0091] In this embodiment, in the M-unit microwave heating apparatus 300, the first microwave heating apparatus 300A and the second microwave heating apparatus 300B are adjacent to each other. In the transport path 50, the second microwave heating apparatus 300B is located downstream of the first microwave heating apparatus 300A. In this embodiment, the inner diameter of the first cylindrical cavity resonator 320A (i.e., the diameter of the cavity 370 of the first cylindrical cavity resonator 320A) φ1 and the inner diameter of the second cylindrical cavity resonator 320B (i.e., the diameter of the cavity 370 of the second cylindrical cavity resonator 320B) φ2 are equal. Specifically, as described above, the shape and dimensions of the first cylindrical cavity resonator 320A and the shape and dimensions of the second cylindrical cavity resonator 320B are identical. However, the inner diameter φ1 of the first cylindrical cavity resonator 320A and the inner diameter φ2 of the second cylindrical cavity resonator 320B may be different. The shape of the first cylindrical cavity resonator 320A and the shape of the second cylindrical cavity resonator 320B may be different, and the dimensions of the first cylindrical cavity resonator 320A and the dimensions of the second cylindrical cavity resonator 320B may be different.

[0092] In this embodiment, the frequency f1 of the first microwave is the first intermediate frequency fm1. The first intermediate frequency fm1 is a frequency that is higher than the first lower frequency fb1 and lower than the first upper frequency ft1. The first lower frequency fb1 is TM within the first cylindrical cavity resonator 320A 0n0 This is the frequency at which the mode's standing wave is formed. The first upper frequency ft1 is within the first cylindrical cavity resonator 320A. 0n1 This is the frequency at which the mode's standing wave is formed.

[0093] In this embodiment, the frequency f2 of the second microwave is the second intermediate frequency fm2. The second intermediate frequency fm2 is a frequency that is higher than the second lower frequency fb2 and lower than the second upper frequency ft2. The second lower frequency fb2 is TM within the second cylindrical cavity resonator 320B 0n0 This is the frequency at which the mode's standing wave is formed. The second upper frequency ft2 is within the second cylindrical cavity resonator 320B. 0n1 This is the frequency at which the mode's standing wave is formed.

[0094] In this embodiment, the first intermediate frequency fm1 and the second intermediate frequency fm2 are controlled independently of each other. In this way, when the amount of dielectric material (e.g., the amount of water) contained in the object to be heated 20 differs depending on whether the object to be heated 20 is located inside the first cylindrical cavity resonator 320A or the second cylindrical cavity resonator 320B, the electric field strength En can be made uniform with respect to the axial direction Da in both the first cylindrical cavity resonator 320A and the second cylindrical cavity resonator 320B.

[0095] The second intermediate frequency fm2 may be different from the first intermediate frequency fm1. Specifically, the second intermediate frequency fm2 may be higher than the first intermediate frequency fm1, or lower than the first intermediate frequency fm1.

[0096] Specifically, in this embodiment, the water contained in the object to be heated 20 is evaporated by the first microwave in the first cylindrical cavity resonator 320A. The water contained in the object to be heated 20 is further evaporated by the second microwave in the second cylindrical cavity resonator 320B. Taking into account the difference in the degree of evaporation, in this embodiment, the second intermediate frequency fm2 is made higher than the first intermediate frequency fm1. This makes it possible to make the electric field strength En uniform with respect to the axial direction Da in both the first cylindrical cavity resonator 320A and the second cylindrical cavity resonator 320B. The reason for this can be explained based on the first and second actions described below.

[0097] In other words, as can be understood from the above explanation, the optimal frequency f for making the electric field strength En uniform with respect to the axial Da is TM 0n0 This is a frequency shifted to the higher frequency side from the resonant frequency of the mode. The first effect is that the amount of this shift decreases as drying progresses (i.e., as the amount of dielectric decreases). On the other hand, as drying progresses, M 0n0 Mode resonant frequency and TM 0n1A second effect exists, which is that the resonant frequency of the mode increases. In this embodiment, the drying of the object to be heated 20 proceeds such that the effect of the increase in resonant frequency due to the second effect is stronger than the effect of the decrease in the amount of shift due to the first effect, between the first cylindrical cavity resonator 320A and the second cylindrical cavity resonator 320B. Therefore, by setting fm2 > fm1, the electric field strength En can be made uniform with respect to the axial Da in both the cylindrical cavity resonators 320A and 320B. For example, when the inner diameters of the first cylindrical cavity resonator 320A and the second cylindrical cavity resonator 320B are the same, the electric field strength En can be made uniform with respect to the axial Da in both the cylindrical cavity resonators 320A and 320B by setting fm2 > fm1.

[0098] As described above, in this embodiment, the water contained in the object to be heated 20 is evaporated by the first microwave in the first cylindrical cavity resonator 320A. The water contained in the object to be heated 20 is further evaporated by the second microwave in the second cylindrical cavity resonator 320B. The inner diameter φ2 of the second cylindrical cavity resonator 320B may be larger than the inner diameter φ1 of the first cylindrical cavity resonator 320A. In this way, the electric field strength En can be made uniform with respect to the axial direction Da in both the cylindrical cavity resonators 320A and 320B. This is because TM 0n0 Mode resonant frequency and TM 0n1 This is because, including the resonant frequencies of the modes, the larger the inner diameter of the cylindrical cavity resonator 320, the lower the resonant frequencies of each resonant mode become.

[0099] By appropriately setting the relative magnitudes of the first intermediate frequency fm1 and the second intermediate frequency fm2, as well as the relative magnitudes of the inner diameters φ1 and φ2, taking into consideration the drying process of the object 20 to be heated in the first cylindrical cavity resonator 320A and the second cylindrical cavity resonator 320B, it is possible to make the electric field strength En uniform with respect to the axial direction Da in both the cylindrical cavity resonators 320A and 320B. In this context, the relative magnitudes of the first and second elements are intended to encompass not only cases where there is a difference in the size of the first and second elements, but also cases where the size of the first and second elements are equal.

[0100] Hereinafter, the technology according to the present disclosure will be further described with reference to examples.

Example

[0101] Simulations were performed using the simulation software COMSOL Multiphysics (registered trademark) manufactured by COMSOL. Specifically, the accuracy of the simulations was confirmed, and examples and comparative examples were executed by simulation.

[0102] The following Table 1 shows the simulation conditions.

Table 1

[0103] <A. Simulation model for accuracy verification> A simulation model M0 for accuracy verification corresponding to a structure (hereinafter, the target structure) including a waveguide 310 and a cylindrical cavity resonator 320 of the embodiment shown in FIG. 3A was constructed. The simulation model M0 includes a waveguide model and a cylindrical cavity resonator model. The waveguide model includes an input port model. The waveguide model simulates the waveguide 310. The input port model simulates the input port 313. The cylindrical cavity resonator model simulates the cylindrical cavity resonator 320. In the simulation model M0, the waveguide model and the cylindrical cavity resonator model were represented by assigning the common material specifications shown in Table 1 to a plurality of continuous elements (regions) in the finite element method.

[0104] <B-1. Accuracy of simulation> Actually, the target structure was fabricated. In the fabricated target structure, the diameter of the cavity 370 of the cylindrical cavity resonator 320 is 92 mm. In the target structure, a predetermined microwave power Px was input into the waveguide 310 through the input port 313. The microwave power Py at a plurality of locations near the first through-hole 351 of the cylindrical cavity resonator 320 was detected using a loop antenna. The transmission intensity S21 (unit: dB) from the input port 313 to each of the above locations was calculated by the following Equation 3. Hereinafter, the transmission intensity S21 calculated based on the detection using the loop antenna at each of the above locations may be referred to as the measured value of the transmission intensity S21. Equation 3: S21 = 10 * log 10 was calculated as (Py / Px).

[0105] Also, the transmission intensity S21 (unit: dB) from the input port 313 to each of the above locations was calculated by electromagnetic field simulation using the simulation model M0 for accuracy verification described in A above. Specifically, in the simulation model M0, the cylindrical cavity resonator model simulated a cylindrical cavity resonator 320 having a cavity 370 with a diameter of 92 mm. In the electromagnetic field simulation, an electric field was forcibly applied to the input port model. The microwave power Px was calculated from the forcibly applied electric field. Also, in the simulation model M0, based on the electric field at each of the above locations, the respective power Py at each of the above locations was calculated. Based on these calculated values and Equation 3 above, the transmission intensity S21 (unit: dB) from the input port 313 to each of the above locations was calculated. Hereinafter, the transmission intensity S21 calculated based on the electromagnetic field simulation may be referred to as the simulation value of the transmission intensity S21.

[0106] The difference between the simulation value of the transmission intensity S21 and the measured value of the transmission intensity S21 at each of the above locations was 3 dB or less. From this, it can be understood that the accuracy of the electromagnetic field simulation is high.

[0107] <B-2. Accuracy of Simulation> In practice, the object to be heated 20 was transported at a constant speed using a roll-to-roll method so that it passed through the cavity 370 of the cylindrical cavity resonator 320 in the target structure described in B-1 above. Specifically, with respect to the second direction D2, the object to be heated 20 was transported so that its center position coincided with the center position of the cavity 370. Six experimental irradiation tests were conducted in which microwaves were irradiated into the cavity 370 of the object to be heated 20 during transport. In each experimental irradiation test, the microwave frequency f was changed. In each experimental irradiation test, the object to be heated 20 was a PET film with a coating 21 applied to it. The coating 21 is an acrylic adhesive containing water. Before the experimental irradiation test, the thickness of the coating 21 was uniform. The "σ / ave" of the thickness of the coating 21 was calculated after each experimental irradiation test. The "σ / ave" of the thickness of the coating 21 is explained as follows. Specifically, with respect to "σ / ave", the evaluation range is the range over which the coating 21 extends on the central axis 390 of the cavity 370. The thickness of the coating 21 at each position in the second direction D2 of the evaluation range is measured. Specifically, these positions are five positions arranged at equal intervals in the second direction D2. At the time of measurement, the coating 21 was in a semi-dry state after heating. "ave" is the arithmetic mean of the thickness of the coating 21 at the above five positions. "σ" is the standard deviation of the thickness of the coating 21 at the above five positions. "σ / ave" is the ratio (rate of change) of "σ" to "ave". Figure 8 is a graph to explain the accuracy of the simulation. In Figure 8, the six plots indicated by block arrows are the "σ / ave" of the thickness of the coating 21 after each of the six actual irradiation experiments. In other words, these six plots show the relationship between frequency f and the "σ / ave" of the thickness of the coating 21.

[0108] Furthermore, a coating model was added to the cavity of the cylindrical cavity resonator model of the simulation model M0 used for accuracy verification, as described in A above. An electromagnetic field simulation was performed using this simulation model with the coating model added. In this electromagnetic field simulation, an electric field was forcibly applied to the input port model, thereby simulating the situation in which microwaves are irradiated onto the coating model. The coating model simulates the coating 21 from the measured irradiation experiment described above, with the coating 21 extending to the area up to the first through hole 351 and the second through hole 361. Also, following the coating 21 from the measured irradiation experiment described above, the position of the coating model in the second direction D2 was set so as to simulate a state in which the center position of the object to be heated 20 coincides with the center position of the cavity 370. Specifically, the coating model was represented by assigning the simulation parameters shown in Table 1. The electric field strength En "σ / ave" was calculated by the electromagnetic field simulation. The electric field strength En "σ / ave" is explained as follows. Specifically, with respect to "σ / ave," the evaluation range is the area where the coating 21 extends along the central axis 390 of the cavity 370. The electric field strength En at each position in the second direction D2 of the evaluation range is calculated. "ave" is the arithmetic mean of the electric field strength En at those positions. "σ" is the standard deviation of the electric field strength En at those positions. "σ / ave" is the ratio (rate of change) of "σ" to "ave." In the electromagnetic field simulation, "σ / ave" was calculated for each case where the microwave frequency f was varied. Figure 8 shows the "σ / ave" of the electric field strength En at each frequency f. In other words, Figure 8 shows a curve that illustrates the relationship between frequency f and the "σ / ave" of the electric field strength En, calculated by the electromagnetic field simulation.

[0109] As shown in Figure 8, the six plots showing the relationship between frequency f and the thickness of the coating film 21 ("σ / ave") obtained from six actual irradiation experiments are distributed along a downward-convex curve, and this downward-convex curve takes a minimum value near 2480 MHz. The curve showing the relationship between frequency f and the electric field strength En ("σ / ave") calculated by electromagnetic field simulation also includes a region of a downward-convex curve, and this downward-convex curve also takes a minimum value near 2480 MHz. There is a similarity in the shape of these downward-convex curves. Furthermore, the difference in the frequencies at which these downward-convex curves exhibit minimum values ​​is about 2 MHz. Figure 8 also demonstrates the high accuracy of the electromagnetic field simulation.

[0110] (C. Experiment using simulation) The experiments for Examples X1 to X6, Comparative Examples Y1 to Y6, Comparative Example Z1, and Comparative Examples Z4 to Z6 were conducted using electromagnetic field simulations. Simulation model M1 was used for the electromagnetic field simulations related to these experiments.

[0111] Simulation model M1, like the simulation model used for accuracy verification described in A above, includes a waveguide model and a cylindrical cavity resonator model. The waveguide model includes an input port model. The waveguide model simulates the waveguide 310. The input port model simulates the input port 313. The cylindrical cavity resonator model simulates the cylindrical cavity resonator 320. Furthermore, simulation model M1 includes a coating model. The coating model simulates the coating 21 that extends to the region from the first through hole 351 to the second through hole 361.

[0112] Experiments for Examples X1, X3, X4, X6, Comparative Examples Y1, Y3, Y4, Y6, Z1, Z4, and Z6 (experiments with a cavity width of 500 mm) were conducted using electromagnetic field simulations with the simulation parameters shown in Table 1. Experiments for Examples X2, X5, Y2, Y5, and Z5 (experiments with a cavity width of 1400 mm) were conducted using electromagnetic field simulations with the simulation parameters showing the number of elements and contacts in Table 1 changed as follows. Number of elements: 552400 Number of nodes: 144,500

[0113] In the following explanation, "n=1" means TM 010 Mode and / or TM 011 This refers to the mode. "n=2" means TM 020 Mode and / or TM 021 This refers to the mode. The moisture content concentration is the water concentration (wt%) in the coating film 21. The coating film thickness is the thickness of the coating film 21. The coating film width is the width W21 of the coating film 21. The cavity diameter is the diameter of the cavity 370. The cavity width is the dimension of the cavity 370 in terms of the axial direction Da.

[0114] (C-1. Example X1, Comparative Example Y1, and Comparative Example Z1) In Example X1, Comparative Example Y1, and Comparative Example Z1, • The moisture content concentration is 75 wt%, • The coating thickness is 20 μm. The coating width is 400 mm. The cavity diameter is 92 mm. The cavity width is 500 mm. n=1, We simulated the situation.

[0115] In comparative example Y1, TM was performed using microwaves with a frequency of f=2447MHz. 010 The situation in which a mode standing wave is formed in cavity 370 was simulated. In comparative example Z1, a microwave with frequency f=2474MHz was used to TM 011The situation in which a mode standing wave is formed in cavity 370 was simulated. In Example X1, a microwave with frequency f = 2450 MHz was used to TM 010 Mode and TM 011 This simulates a situation where a mixed electric field of modes is formed in cavity 370.

[0116] (C-2. Example X2 and Comparative Example Y2) In Example X2 and Comparative Example Y2, • The moisture content concentration is 75 wt%, • The coating thickness is 20 μm. The coating width is 1310 mm. The cavity diameter is 92 mm. The cavity width is 1400 mm, n=1, We simulated the situation.

[0117] In comparative example Y2, TM was performed using microwaves with a frequency of f=2445MHz. 010 The situation in which a mode standing wave is formed in cavity 370 was simulated. In Example X2, a microwave with frequency f=2449MHz was used to TM 010 Mode and TM 011 This simulates a situation where a mixed electric field of modes is formed in cavity 370.

[0118] (C-3. ​​Example X3 and Comparative Example Y3) In Example X3 and Comparative Example Y3, • The moisture content concentration is 75 wt%, The coating thickness is 200 μm. The coating width is 400 mm. The cavity diameter is 81 mm. The cavity width is 500 mm. n=1, We simulated the situation.

[0119] In comparative example Y3, TM was performed using microwaves with a frequency of f=2422MHz. 010The situation in which a mode standing wave is formed in cavity 370 was simulated. In Example X3, a microwave with frequency f=2459MHz was used to TM 010 Mode and TM 011 This simulates a situation where a mixed electric field of modes is formed in cavity 370.

[0120] (C-4. Example X4, Comparative Example Y4, and Comparative Example Z4) In Example X4, Comparative Example Y4, and Comparative Example Z4, • The moisture content concentration is 75 wt%, • The coating thickness is 20 μm. The coating width is 400 mm. The cavity diameter is 211.5 mm. The cavity width is 500 mm. n=2, We simulated the situation.

[0121] In comparative example Y4, TM was performed using microwaves with a frequency of f=2471MHz. 020 The situation in which a mode standing wave is formed in cavity 370 was simulated. In comparative example Z4, a microwave with frequency f=2480MHz was used to TM 021 The situation in which a mode standing wave is formed in cavity 370 was simulated. In Example X4, a microwave with frequency f=2472MHz was used to TM 020 Mode and TM 021 This simulates a situation where a mixed electric field of modes is formed in cavity 370.

[0122] (C-5. Example X5, Comparative Example Y5, and Comparative Example Z5) In Example X5, Comparative Example Y5, and Comparative Example Z5, • The moisture content concentration is 75 wt%, • The coating thickness is 20 μm. The coating width is 1310 mm. The cavity diameter is 211.5 mm. The cavity width is 1400 mm, n=2, We simulated the situation.

[0123] In comparative example Y5, TM was performed using microwaves with a frequency of f = 2470 MHz. 020 The situation in which a mode standing wave is formed in cavity 370 was simulated. In comparative example Z5, a microwave with frequency f=2474MHz was used to TM 021 The situation in which a mode standing wave is formed in cavity 370 was simulated. In Example X5, a microwave with frequency f = 2472 MHz was used to TM 020 Mode and TM 021 This simulates a situation where a mixed electric field of modes is formed in cavity 370.

[0124] (C-6. Example X6, Comparative Example Y6, and Comparative Example Z6) In Example X6, Comparative Example Y6, and Comparative Example Z6, • The moisture content concentration is 75 wt%, The coating thickness is 200 μm. The coating width is 400 mm. The cavity diameter is 202 mm. The cavity width is 500 mm. n=2, We simulated the situation.

[0125] In comparative example Y6, TM was performed using microwaves with a frequency of f=2423MHz. 020 The situation in which a mode standing wave is formed in cavity 370 was simulated. In comparative example Z6, a microwave with frequency f=2458MHz was used to TM 021 The situation in which a mode standing wave is formed in cavity 370 was simulated. In Example X6, a microwave with frequency f=2430MHz was used to TM 020 Mode and TM 021 This simulates a situation where a mixed electric field of modes is formed in cavity 370.

[0126] Figure 9A is a contour plot showing the distribution of electric field strength En in the cavity 370, calculated from electromagnetic field simulations for Example X1, Comparative Example Y1, and Comparative Example Z1. Figure 9B is a graph showing the relationship between the position in the second direction D2 on the central axis 390 of the cavity 370 and the electric field strength En, calculated from electromagnetic field simulations for Example X1, Comparative Example Y1, and Comparative Example Z1. In Figure 9B, the horizontal axis position = 0 mm refers to the center position of the introduction opening 343 with respect to the second direction D2. This point is also true for Figures 10B, 11B, 12B, 13B, and 14B, which will be described later.

[0127] Figure 10A is a contour plot showing the distribution of electric field strength En in the cavity 370, calculated from electromagnetic field simulations for Example X2 and Comparative Example Y2. Figure 10B is a graph showing the relationship between the position in the second direction D2 on the central axis 390 of the cavity 370 and the electric field strength En, calculated from electromagnetic field simulations for Example X2 and Comparative Example Y2.

[0128] Figure 11A is a contour plot showing the distribution of electric field strength En in the cavity 370, calculated from electromagnetic field simulations for Example X3 and Comparative Example Y3. Figure 11B is a graph showing the relationship between the position in the second direction D2 on the central axis 390 of the cavity 370 and the electric field strength En, calculated from electromagnetic field simulations for Example X3 and Comparative Example Y3.

[0129] Figure 12A is a contour plot showing the distribution of electric field strength En in the cavity 370, calculated from electromagnetic field simulations for Example X4, Comparative Example Y4, and Comparative Example Z4. Figure 12B is a graph showing the relationship between the position in the second direction D2 on the central axis 390 of the cavity 370 and the electric field strength En, calculated from electromagnetic field simulations for Example X4, Comparative Example Y4, and Comparative Example Z4.

[0130] Figure 13A is a contour plot showing the distribution of electric field strength En in the cavity 370, calculated from electromagnetic field simulations for Example X5, Comparative Example Y5, and Comparative Example Z5. Figure 13B is a graph showing the relationship between the position in the second direction D2 on the central axis 390 of the cavity 370 and the electric field strength En, calculated from electromagnetic field simulations for Example X5, Comparative Example Y5, and Comparative Example Z5.

[0131] Figure 14A is a contour plot showing the distribution of electric field strength En in the cavity 370, calculated from electromagnetic field simulations for Example X6, Comparative Example Y6, and Comparative Example Z6. Figure 14B is a graph showing the relationship between the position in the second direction D2 on the central axis 390 of the cavity 370 and the electric field strength En, calculated from electromagnetic field simulations for Example X6, Comparative Example Y6, and Comparative Example Z6.

[0132] Table 2 shows the experimental results for Examples X1 to X6, Comparative Examples Y1 to Y6, Comparative Example Z1, and Comparative Examples Z4 to Z6. In Table 2, "σ / ave" is explained as follows: With respect to "σ / ave", the evaluation range is the range over which the coating 21 extends on the central axis 390 of the cavity 370. In the electromagnetic field simulation, the electric field strength En at each position in the second direction D2 of the evaluation range is calculated. "ave" is the arithmetic mean of the electric field strength En at those positions. "σ" is the standard deviation of the electric field strength En at those positions. "σ / ave" is the ratio (rate of change) of "σ" to "ave". [Table 2]

[0133] (Technologies applicable to the embodiments) The following describes technologies applicable to the embodiments described above.

[0134] The control devices 385 in multiple microwave heating devices 300 may be different devices from each other. One control device may serve as the control device 385 for multiple microwave heating devices 300.

[0135] In the above-described embodiment, the microwave heating system 1A includes a plurality of microwave heating devices 300. In the above-described embodiment, the microwave heating system 1A also includes a plurality of cylindrical cavity resonators 320. However, the number of microwave heating devices 300 included in the microwave heating system 1A may be one. Similarly, the number of cylindrical cavity resonators 320 included in the microwave heating system 1A may be one.

[0136] The second object to be heated 20 may not contain a coating film but may contain a substrate. In this case, the substrate may have a dielectric material such as water. For example, the substrate can be dried by heating it.

[0137] In the embodiments described above, both the substrate 11 and the film 21 are objects to be heated by microwaves. However, this is not essential. For example, the substrate 11 does not have to be an object to be heated by microwaves.

[0138] The dielectric material of the second object to be heated 20 may contain alcohol along with water, or in place of water. In this case, heating the second object to be heated 20 will evaporate the alcohol and dry the second object to be heated 20.

[0139] The purpose of microwave heating may also be annealing.

[0140] (Note) This disclosure provides for the following technologies:

[0141] (Technology 1) Equipped with a cylindrical cavity resonator, In the cylindrical cavity resonator, microwaves are irradiated onto the object to be heated. The frequency of the microwave is an intermediate frequency. The aforementioned intermediate frequency is a frequency that is higher than the lower frequency and lower than the upper frequency. The aforementioned lower frequency occurs within the cylindrical cavity resonator where the object to be heated is located TM 0n0This is the frequency at which the mode forms a standing wave. The aforementioned upper frequency is within the cylindrical cavity resonator where the object to be heated is located TM 0n1 This is the frequency at which the mode forms a standing wave. n is a natural number greater than or equal to 1. Microwave heating system.

[0142] (Technology 2) A microwave detector for detecting the microwaves in the cylindrical cavity resonator, The system includes a control device that identifies the lower frequency and the upper frequency based on the detection results of the microwave detector, and identifies the intermediate frequency based on the identified lower frequency and the upper frequency. The microwave heating system described in Technology 1.

[0143] (Technology 3) The device includes a control device that changes the intermediate frequency according to the amount of water contained in the object to be heated. A microwave heating system as described in Technology 1 or 2.

[0144] (Technology 4) The cylindrical cavity resonator is equipped with a conveying device for transporting the object to be heated. A microwave heating system as described in any one of the three technical specifications.

[0145] (Technology 5) The cylindrical cavity resonator includes a wall having an inner circumferential surface, On the aforementioned wall, The cavity partitioned by the aforementioned inner circumferential surface, The cavity includes an introduction opening for introducing the microwaves, A first through-hole penetrating the aforementioned wall, A second through-hole penetrating the aforementioned wall is provided, The conveying device conveys the object to be heated in the order of the first through hole, the cavity, and the second through hole. The microwave heating system described in Technology 4.

[0146] (Technology 6) In the cylindrical cavity resonator, the object to be heated, which is being transported by the transport device, is irradiated with microwaves. A microwave heating system as described in Technology 4 or 5.

[0147] (Technology 7) The aforementioned cylindrical cavity resonator will be referred to as the first cylindrical cavity resonator. The aforementioned microwave will be referred to as the first microwave, The aforementioned intermediate frequency will be referred to as the first intermediate frequency. The aforementioned lower frequency will be referred to as the first lower frequency. When the aforementioned upper frequency is denoted as the first upper frequency, Equipped with a second cylindrical cavity resonator, The conveying device sequentially conveys the object to be heated through the first cylindrical cavity resonator and then through the second cylindrical cavity resonator. In the second cylindrical cavity resonator, the object to be heated is irradiated with a second microwave. The frequency of the second microwave is the second intermediate frequency, The second intermediate frequency is a frequency that is higher than the second lower frequency and lower than the second upper frequency. The second lower frequency is TM within the second cylindrical cavity resonator. 0n0 This is the frequency at which the mode forms a standing wave. The second upper frequency is TM within the second cylindrical cavity resonator. 0n1 This is the frequency at which the mode forms a standing wave. The first intermediate frequency and the second intermediate frequency are controlled independently of each other. A microwave heating system as described in any one of the technical descriptions 4 to 6.

[0148] (Technology 8) The aforementioned cylindrical cavity resonator will be referred to as the first cylindrical cavity resonator. The aforementioned microwave will be referred to as the first microwave, The aforementioned intermediate frequency will be referred to as the first intermediate frequency. The aforementioned lower frequency will be referred to as the first lower frequency. When the aforementioned upper frequency is denoted as the first upper frequency, Equipped with a second cylindrical cavity resonator, The conveying device sequentially conveys the object to be heated through the first cylindrical cavity resonator and then through the second cylindrical cavity resonator. In the second cylindrical cavity resonator, the object to be heated is irradiated with a second microwave. The frequency of the second microwave is the second intermediate frequency, The second intermediate frequency is a frequency that is higher than the second lower frequency and lower than the second upper frequency. The second lower frequency is TM within the second cylindrical cavity resonator. 0n0 This is the frequency at which the mode forms a standing wave. The second upper frequency is TM within the second cylindrical cavity resonator. 0n1 This is the frequency at which the mode forms a standing wave. The second intermediate frequency is higher than the first intermediate frequency. A microwave heating system as described in any one of the technical items 4 to 7.

[0149] (Technology 9) The aforementioned cylindrical cavity resonator will be referred to as the first cylindrical cavity resonator. The aforementioned microwave will be referred to as the first microwave, The aforementioned intermediate frequency will be referred to as the first intermediate frequency. The aforementioned lower frequency will be referred to as the first lower frequency. When the aforementioned upper frequency is denoted as the first upper frequency, Equipped with a second cylindrical cavity resonator, The conveying device sequentially conveys the object to be heated through the first cylindrical cavity resonator and then through the second cylindrical cavity resonator. In the second cylindrical cavity resonator, the object to be heated is irradiated with a second microwave. The frequency of the second microwave is the second intermediate frequency, The second intermediate frequency is a frequency that is higher than the second lower frequency and lower than the second upper frequency. The second lower frequency is TM within the second cylindrical cavity resonator. 0n0This is the frequency at which the mode forms a standing wave. The second upper frequency is TM within the second cylindrical cavity resonator. 0n1 This is the frequency at which the mode forms a standing wave. The inner diameter of the second cylindrical cavity resonator is greater than or equal to the inner diameter of the first cylindrical cavity resonator. A microwave heating system as described in any one of the technical specifications 4 to 8.

[0150] (Technology 10) The inner diameter of the second cylindrical cavity resonator is larger than the inner diameter of the first cylindrical cavity resonator. The microwave heating system described in Technical 9.

[0151] (Technology 11) The system includes irradiating the object to be heated with microwaves inside a cylindrical cavity resonator. The frequency of the microwave is an intermediate frequency. The aforementioned intermediate frequency is a frequency that is higher than the lower frequency and lower than the upper frequency. The aforementioned lower frequency occurs within the cylindrical cavity resonator where the object to be heated is located TM 0n0 This is the frequency at which the mode forms a standing wave. The aforementioned upper frequency is within the cylindrical cavity resonator where the object to be heated is located TM 0n1 This is the frequency at which the mode forms a standing wave. n is a natural number greater than or equal to 1. Microwave heating method.

[0152] (Technology 12) To detect the microwaves in the cylindrical cavity resonator, Based on the results of the above detection, the lower frequency and the upper frequency are identified, The process includes determining the intermediate frequency based on the identified lower frequency and upper frequency, The microwave heating method described in Technical 11.

[0153] (Technology 13) The intermediate frequency is changed according to the amount of water contained in the object to be heated. The microwave heating method described in Technical Reference 11 or 12.

[0154] (Technology 14) The cylindrical cavity resonator is equipped with a mechanism for irradiating the object to be heated during transport with microwaves. A microwave heating method as described in any one of the technical specifications 11 to 13.

[0155] (Technology 15) The aforementioned cylindrical cavity resonator will be referred to as the first cylindrical cavity resonator. The aforementioned microwave will be referred to as the first microwave, The aforementioned intermediate frequency will be referred to as the first intermediate frequency. The aforementioned lower frequency will be referred to as the first lower frequency. When the aforementioned upper frequency is denoted as the first upper frequency, The object to be heated is sequentially transported through the first cylindrical cavity resonator and then through the second cylindrical cavity resonator, The method comprises irradiating the object to be heated with a second microwave within the second cylindrical cavity resonator, The frequency of the second microwave is the second intermediate frequency, The second intermediate frequency is a frequency that is higher than the second lower frequency and lower than the second upper frequency. The second lower frequency is TM within the second cylindrical cavity resonator. 0n0 This is the frequency at which the mode forms a standing wave. The second upper frequency is TM within the second cylindrical cavity resonator. 0n1 This is the frequency at which the mode forms a standing wave. The first intermediate frequency and the second intermediate frequency are controlled independently of each other. A microwave heating method as described in any one of Technical Articles 11 to 14.

[0156] (Technology 16) The aforementioned cylindrical cavity resonator will be referred to as the first cylindrical cavity resonator. The aforementioned microwave will be referred to as the first microwave, The aforementioned intermediate frequency will be referred to as the first intermediate frequency. The aforementioned lower frequency will be referred to as the first lower frequency. When the aforementioned upper frequency is denoted as the first upper frequency, The object to be heated is sequentially transported through the first cylindrical cavity resonator and then through the second cylindrical cavity resonator, In the first cylindrical cavity resonator, the water contained in the object to be heated is evaporated by the first microwave, The method comprises evaporating the water contained in the object to be heated by a second microwave within the second cylindrical cavity resonator, The frequency of the second microwave is the second intermediate frequency, The second intermediate frequency is a frequency that is higher than the second lower frequency and lower than the second upper frequency. The second lower frequency is TM within the second cylindrical cavity resonator. 0n0 This is the frequency at which the mode forms a standing wave. The second upper frequency is TM within the second cylindrical cavity resonator. 0n1 This is the frequency at which the mode forms a standing wave. The second intermediate frequency is higher than the first intermediate frequency. A microwave heating method as described in any one of Technical Articles 11 to 15.

[0157] (Technology 17) The aforementioned cylindrical cavity resonator will be referred to as the first cylindrical cavity resonator. The aforementioned microwave will be referred to as the first microwave, The aforementioned intermediate frequency will be referred to as the first intermediate frequency. The aforementioned lower frequency will be referred to as the first lower frequency. When the aforementioned upper frequency is denoted as the first upper frequency, The object to be heated is sequentially transported through the first cylindrical cavity resonator and then through the second cylindrical cavity resonator, In the first cylindrical cavity resonator, the water contained in the object to be heated is evaporated by the first microwave, The method comprises evaporating the water contained in the object to be heated by a second microwave within the second cylindrical cavity resonator, The frequency of the second microwave is the second intermediate frequency, The second intermediate frequency is a frequency that is higher than the second lower frequency and lower than the second upper frequency. The second lower frequency is TM within the second cylindrical cavity resonator. 0n0 This is the frequency at which the mode forms a standing wave. The second upper frequency is TM within the second cylindrical cavity resonator. 0n1 This is the frequency at which the mode forms a standing wave. The inner diameter of the second cylindrical cavity resonator is greater than or equal to the inner diameter of the first cylindrical cavity resonator. A microwave heating method as described in any one of the technical specifications 11 to 16.

[0158] (Technology 18) The inner diameter of the second cylindrical cavity resonator is larger than the inner diameter of the first cylindrical cavity resonator. The microwave heating method described in Technical 17. [Industrial applicability]

[0159] The technology according to the present invention can be applied, for example, to microwave drying.

[0160] For example, a film may be formed using a coating solution diluted with a solvent, and the film may be dried. From the viewpoint of improving environmental performance, one might consider changing the solvent from an organic solvent to a water-containing solvent. In this case, the energy required for the evaporation of the solvent may increase. In this respect, microwave drying technology can efficiently evaporate water-containing solvents compared to drying technologies such as hot air. Therefore, even considering the energy required for the evaporation of water, it is easier to improve environmental performance. Moreover, according to the above embodiment, the film can be dried uniformly, foaming of the film is less likely to occur, and insufficient drying of the film is less likely to occur.

Claims

1. Equipped with a cylindrical cavity resonator, In the cylindrical cavity resonator, microwaves are irradiated onto the object to be heated. The frequency of the microwave is an intermediate frequency. The aforementioned intermediate frequency is a frequency that is higher than the lower frequency and lower than the upper frequency. The aforementioned lower frequency is TM within the cylindrical cavity resonator where the object to be heated is located. 0n0 This is the frequency at which the mode forms a standing wave. The aforementioned upper frequency is TM within the cylindrical cavity resonator where the object to be heated is present. 0n1 This is the frequency at which the mode forms a standing wave. n is a natural number greater than or equal to 1. Microwave heating system.

2. A microwave detector for detecting the microwaves in the cylindrical cavity resonator, The system includes a control device that identifies the lower frequency and the upper frequency based on the detection results of the microwave detector, and identifies the intermediate frequency based on the identified lower frequency and the upper frequency. The microwave heating system according to claim 1.

3. The device includes a control device that changes the intermediate frequency according to the amount of water contained in the object to be heated. The microwave heating system according to claim 1.

4. The cylindrical cavity resonator is equipped with a conveying device for transporting the object to be heated. The microwave heating system according to claim 1.

5. The cylindrical cavity resonator includes a wall having an inner circumferential surface, On the aforementioned wall, The cavity partitioned by the aforementioned inner circumferential surface, The cavity includes an introduction opening for introducing the microwaves, A first through-hole penetrating the aforementioned wall, A second through-hole is provided that penetrates the aforementioned wall, The conveying device conveys the object to be heated in the order of the first through hole, the cavity, and the second through hole. The microwave heating system according to claim 4.

6. In the cylindrical cavity resonator, the object to be heated, which is being transported by the transport device, is irradiated with microwaves. The microwave heating system according to claim 4.

7. The aforementioned cylindrical cavity resonator will be referred to as the first cylindrical cavity resonator. The aforementioned microwave will be referred to as the first microwave, The aforementioned intermediate frequency will be referred to as the first intermediate frequency. The aforementioned lower frequency will be referred to as the first lower frequency. When the aforementioned upper frequency is denoted as the first upper frequency, Equipped with a second cylindrical cavity resonator, The conveying device sequentially conveys the object to be heated through the first cylindrical cavity resonator and then through the second cylindrical cavity resonator. In the second cylindrical cavity resonator, the object to be heated is irradiated with a second microwave. The frequency of the second microwave is the second intermediate frequency, The second intermediate frequency is a frequency that is higher than the second lower frequency and lower than the second upper frequency. The second lower frequency is TM in the second cylindrical cavity resonator. 0n0 This is the frequency at which the mode forms a standing wave. The second upper frequency is TM within the second cylindrical cavity resonator. 0n1 This is the frequency at which the mode forms a standing wave. The first intermediate frequency and the second intermediate frequency are controlled independently of each other. The microwave heating system according to claim 4.

8. The aforementioned cylindrical cavity resonator will be referred to as the first cylindrical cavity resonator. The aforementioned microwave will be referred to as the first microwave, The aforementioned intermediate frequency will be referred to as the first intermediate frequency. The aforementioned lower frequency will be referred to as the first lower frequency. When the aforementioned upper frequency is denoted as the first upper frequency, Equipped with a second cylindrical cavity resonator, The conveying device sequentially conveys the object to be heated through the first cylindrical cavity resonator and then through the second cylindrical cavity resonator. In the second cylindrical cavity resonator, the object to be heated is irradiated with a second microwave. The frequency of the second microwave is the second intermediate frequency, The second intermediate frequency is a frequency that is higher than the second lower frequency and lower than the second upper frequency. The second lower frequency is TM in the second cylindrical cavity resonator. 0n0 This is the frequency at which the mode forms a standing wave. The second upper frequency is TM within the second cylindrical cavity resonator. 0n1 This is the frequency at which the mode forms a standing wave. The second intermediate frequency is higher than the first intermediate frequency. The microwave heating system according to claim 4.

9. The aforementioned cylindrical cavity resonator will be referred to as the first cylindrical cavity resonator. The aforementioned microwave will be referred to as the first microwave, The aforementioned intermediate frequency will be referred to as the first intermediate frequency. The aforementioned lower frequency will be referred to as the first lower frequency. When the aforementioned upper frequency is denoted as the first upper frequency, Equipped with a second cylindrical cavity resonator, The conveying device sequentially conveys the object to be heated through the first cylindrical cavity resonator and then through the second cylindrical cavity resonator. In the second cylindrical cavity resonator, the object to be heated is irradiated with a second microwave. The frequency of the second microwave is the second intermediate frequency, The second intermediate frequency is a frequency that is higher than the second lower frequency and lower than the second upper frequency. The second lower frequency is TM in the second cylindrical cavity resonator. 0n0 This is the frequency at which the mode forms a standing wave. The second upper frequency is TM within the second cylindrical cavity resonator. 0n1 This is the frequency at which the mode forms a standing wave. The inner diameter of the second cylindrical cavity resonator is greater than or equal to the inner diameter of the first cylindrical cavity resonator. The microwave heating system according to claim 4.

10. The inner diameter of the second cylindrical cavity resonator is larger than the inner diameter of the first cylindrical cavity resonator. The microwave heating system according to claim 9.

11. The system includes irradiating the object to be heated with microwaves inside a cylindrical cavity resonator. The frequency of the microwave is an intermediate frequency. The aforementioned intermediate frequency is a frequency that is higher than the lower frequency and lower than the upper frequency. The lower frequency is the frequency at which a standing wave of the TM 0n0 mode is formed in the cylindrical cavity resonator in which the object to be heated is present, The aforementioned upper frequency is TM within the cylindrical cavity resonator where the object to be heated is present. 0n1 This is the frequency at which the mode forms a standing wave. n is a natural number greater than or equal to 1. Microwave heating method.

12. To detect the microwaves in the cylindrical cavity resonator, Based on the results of the above detection, the lower frequency and the upper frequency are identified, The process includes determining the intermediate frequency based on the identified lower frequency and upper frequency, The microwave heating method according to claim 11.

13. The intermediate frequency is changed according to the amount of water contained in the object to be heated. The microwave heating method according to claim 11.

14. The cylindrical cavity resonator is equipped with a mechanism for irradiating the object to be heated during transport with microwaves. The microwave heating method according to claim 11.

15. The aforementioned cylindrical cavity resonator will be referred to as the first cylindrical cavity resonator. The aforementioned microwave will be referred to as the first microwave, The aforementioned intermediate frequency will be referred to as the first intermediate frequency. The aforementioned lower frequency will be referred to as the first lower frequency. When the aforementioned upper frequency is denoted as the first upper frequency, The object to be heated is sequentially transported through the first cylindrical cavity resonator and then through the second cylindrical cavity resonator, The method comprises irradiating the object to be heated with a second microwave within the second cylindrical cavity resonator, The frequency of the second microwave is the second intermediate frequency, The second intermediate frequency is a frequency that is higher than the second lower frequency and lower than the second upper frequency. The second lower frequency is TM in the second cylindrical cavity resonator. 0n0 This is the frequency at which the mode forms a standing wave. The second upper frequency is TM within the second cylindrical cavity resonator. 0n1 This is the frequency at which the mode forms a standing wave. The first intermediate frequency and the second intermediate frequency are controlled independently of each other. The microwave heating method according to claim 11.

16. The aforementioned cylindrical cavity resonator will be referred to as the first cylindrical cavity resonator. The aforementioned microwave will be referred to as the first microwave, The aforementioned intermediate frequency will be referred to as the first intermediate frequency. The aforementioned lower frequency will be referred to as the first lower frequency. When the aforementioned upper frequency is denoted as the first upper frequency, The object to be heated is sequentially transported through the first cylindrical cavity resonator and then through the second cylindrical cavity resonator, In the first cylindrical cavity resonator, the water contained in the object to be heated is evaporated by the first microwave, The method comprises evaporating the water contained in the object to be heated by a second microwave within the second cylindrical cavity resonator, The frequency of the second microwave is the second intermediate frequency, The second intermediate frequency is a frequency that is higher than the second lower frequency and lower than the second upper frequency. The second lower frequency is TM in the second cylindrical cavity resonator. 0n0 This is the frequency at which the mode forms a standing wave. The second upper frequency is TM within the second cylindrical cavity resonator. 0n1 This is the frequency at which the mode forms a standing wave. The second intermediate frequency is higher than the first intermediate frequency. The microwave heating method according to claim 11.

17. The aforementioned cylindrical cavity resonator will be referred to as the first cylindrical cavity resonator. The aforementioned microwave will be referred to as the first microwave, The aforementioned intermediate frequency will be referred to as the first intermediate frequency. The aforementioned lower frequency will be referred to as the first lower frequency. When the aforementioned upper frequency is denoted as the first upper frequency, The object to be heated is sequentially transported through the first cylindrical cavity resonator and then through the second cylindrical cavity resonator, In the first cylindrical cavity resonator, the water contained in the object to be heated is evaporated by the first microwave, The method comprises evaporating the water contained in the object to be heated by a second microwave within the second cylindrical cavity resonator, The frequency of the second microwave is the second intermediate frequency, The second intermediate frequency is a frequency that is higher than the second lower frequency and lower than the second upper frequency. The second lower frequency is TM in the second cylindrical cavity resonator. 0n0 This is the frequency at which the mode forms a standing wave. The second upper frequency is TM within the second cylindrical cavity resonator. 0n1 This is the frequency at which the mode forms a standing wave. The inner diameter of the second cylindrical cavity resonator is greater than or equal to the inner diameter of the first cylindrical cavity resonator. The microwave heating method according to claim 11.

18. The inner diameter of the second cylindrical cavity resonator is larger than the inner diameter of the first cylindrical cavity resonator. The microwave heating method according to claim 17.

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