Microwave heating system and microwave heating method

Abstract

A microwave heating system (1A) includes two or more cylindrical cavity resonators (320) and a conveyance device (70). The conveyance device (70) sequentially conveys an object (20) to be heated into the two or more cylindrical cavity resonators (320). Each of the two or more cylindrical cavity resonators (320) has an introduction opening through which microwaves are introduced into the cylindrical cavity resonator (320). The object (20) to be heated is heated by microwaves in the two or more cylindrical cavity resonators (320).

Description

Microwave heating system and microwave heating method

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

[0002] Microwave heating has been studied. An example of microwave heating is described in Patent Document 1. Specifically, Patent Document 1 describes heating a magnetic material by microwave heating.

[0003] Japanese Patent Application Laid-Open No. 2019-140103

[0004] In a system in which microwave heating of an object to be heated is performed using a single cylindrical cavity resonator, if there is an upper limit on the microwave power supplied to the cylindrical cavity resonator due to a microwave source, etc., there is a possibility that the object to be heated may be insufficiently heated. The present invention provides a technology suitable for avoiding insufficient heating of the object to be heated.

[0005] The present invention provides a microwave heating system comprising: two or more cylindrical cavity resonators; and a transport device that sequentially transports an object to be heated into the two or more cylindrical cavity resonators, each of the two or more cylindrical cavity resonators having an introduction opening for introducing microwaves into the cylindrical cavity resonator, and the object to be heated is heated by the microwaves in the two or more cylindrical cavity resonators.

[0006] The technology according to the present invention is suitable for avoiding insufficient heating of an object to be heated.

[0007] FIG. 1 is a configuration diagram of a microwave heating system according to an embodiment. FIG. 2A is a top view illustrating a first object to be heated and a second object to be heated. FIG. 2B is a cross-sectional view illustrating a second object to be heated. FIG. 3A is a schematic cross-sectional view of a microwave heating device. FIG. 3B is a schematic view of a waveguide and a cavity. FIG. 4 is a top view of M cylindrical cavity resonators. FIG. 5A is an explanatory diagram of a group of microwave heating devices according to a first example. FIG. 5B is an explanatory diagram of a group of microwave heating devices according to a second example. FIG. 5C is an explanatory diagram of a reference embodiment. FIG. 6A is an explanatory diagram of an exposure electric field intensity distribution according to the first example. FIG. 6B is an explanatory diagram of an exposure electric field intensity distribution according to the second example. FIG. 6C is an explanatory diagram of an exposure electric field intensity distribution according to the reference embodiment.

[0008] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the following is merely an example of an embodiment of the present invention and is not intended to limit the present invention.

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

[0010] 1 shows a first direction D1, a second direction D2, and a third direction D3. In this embodiment, the first direction D1 is the machine direction (MD). The second direction D2 is the transverse direction (TD). The third direction D3 is the vertical direction (VD). The first direction D1, the second direction D2, and the third direction D3 are perpendicular to each other.

[0011] 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 payout roller 100 and a take-up roller 400. In the microwave heating system 1A, a conveying path 50 is configured in which the payout roller 100, the coating device 200, the microwave heating device group 600, and the take-up roller 400 appear in this order.

[0012] The payout roller 100 pays out the object to be heated S from the roll of the object to be heated S. 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 take-up roller 400 winds up the object to be heated S, thereby forming a roll of the wound object to be heated S. In this way, in this embodiment, the object to be heated S is transported along the transport path 50 in a roll-to-roll manner, and coating and heating are performed in this order on the object to be heated S during transport.

[0013] In this embodiment, when the object to be heated S is coated in the coating device 200 and heated in the microwave heating device group 600, its conveying 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 object to be heated S, the conveying device 70, the coating device 200, and the group of microwave heating devices 600 will be described in detail below.

[0015] 1. Object to be heated S> The object to be heated S has a first configuration upstream of the coating device 200 on the conveying path 50. The object to be heated S has a second configuration downstream of the coating device 200 on the conveying 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, the object to be heated S having the first configuration will be referred to as a first object to be heated 10. The object to be heated S having the second configuration will be referred to as a second object to be heated 20.

[0017] Fig. 2A is a top view illustrating the first object to be heated 10 and the second object to be heated 20. Fig. 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 body of a substrate 11 .

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

[0020] In this embodiment, the substrate 11 is a resin film. Specifically, the substrate 11 is a polyethylene terephthalate (PET) film. The substrate is also a nonwoven fabric.

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

[0022] Hereinafter, the dimension of the substrate 11 in the second direction D2 will be referred to as a width W11. In this embodiment, the width W11 is 200 mm or more and 2000 mm or less. Specifically, the width W11 is 250 mm or more and 1300 mm or less.

[0023] Hereinafter, the dimension of the substrate 11 in the third direction D3 will be referred to as a thickness T11. In this embodiment, the thickness T11 is 10 μm or more and 300 μm or less. Specifically, the thickness T11 is 15 μm or more and 100 μm or less.

[0024] Hereinafter, the dimension of the membrane 21 in the second direction D2 will be referred to as the width W21. Typically, the width W21 is smaller than the width W11. In this embodiment, the width W21 is 195 mm or more and 1995 mm or less. Specifically, the width W21 is 245 mm or more and 1295 mm or less.

[0025] Hereinafter, the dimension of the film 21 in the third direction D3 immediately after coating by the coating device 200 will be referred to as thickness T21. In this embodiment, the thickness T21 is 1 μm or more and 200 μm or less. Specifically, the thickness T21 is 10 μm or more and 120 μm or less. More specifically, the thickness T21 is 10 μm or more and 100 μm or less. The thickness T21 is also referred to as the initial coating thickness.

[0026] In this embodiment, the dimension of the first heated object 10 in the second direction D2 is 200 mm to 2000 mm, specifically 250 mm to 1300 mm, and the dimension of the first heated object 10 in the third direction D3 is 10 μm to 300 μm, specifically 15 μm to 100 μm.

[0027] In this embodiment, the dimension of the second heated object 20 in the second direction D2 is 200 mm to 2000 mm, specifically 250 mm to 1300 mm. There is a period in which the dimension of the second heated object 20 in the third direction D3 is 11 μm to 500 μm, specifically 25 μm to 200 μm.

[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 conveying direction is longer than the cylindrical cavity resonator 320 described below. However, the shapes of the object 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 object to be heated S, the first object to be heated 10, and the second object to be heated 20 is a sheet.

[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 a cavity 370 in a cylindrical cavity resonator 320, which will be described later. The payout roller 100 pays out the object to be heated S so that the object to be heated S is conveyed along the conveying path 50. The take-up roller 400 takes up the object to be heated S so that the object to be heated S is conveyed along the conveying path 50.

[0030] The conveying device 70 determines the speed (hereinafter referred to as the conveying speed) of the object S to be heated conveyed along the conveying path 50. The conveying speed is, for example, not less than 0.1 m / min and not more than 100 m / min.

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

[0032] <Coating device 200> The coating device 200 forms the second object to be heated 20 from the first object to be heated 10. Specifically, the coating device 200 applies a coating liquid onto the substrate 11 to form a film 21 on the substrate 11. In other words, the film 21 is a coating film. Hereinafter, the film 21 that 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. Specifically, in this embodiment, the coating liquid contains water as a dispersion medium, but does not contain an organic compound as a dispersion medium. The film 21 is a film of an emulsion pressure-sensitive adhesive.

[0034] In this embodiment, the coating liquid contains a resin as a solute or a dispersoid. Specifically, the resin is an acrylic resin. Specifically, in this embodiment, the coating liquid contains a resin (specifically, an acrylic resin) as a dispersoid.

[0035] The solid content concentration in the coating liquid is determined so as to be able to form the film 21. In this embodiment, the solid content concentration is 20% by weight or more and 80% by weight or less. Specifically, the solid content concentration is 20% by weight or more and 60% by weight or less.

[0036] 3. Microwave Heating Device Group 600 The microwave heating device group 600 includes a plurality of microwave heating devices 300. FIG.

[0037] The microwave heating device 300 includes a waveguide 310 and a cylindrical cavity resonator 320. The waveguide 310 is coupled to the cylindrical cavity resonator 320. Note that the cylindrical cavity resonator 320 may include a microwave coupler.

[0038] 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" does not imply that the shape of the resonator is required to be cylindrical in the strict sense. Similarly, the expression "cylindrical cavity 370" described below does not imply that the shape of the cavity 370 is required to be cylindrical in the strict sense. The same applies to the "cylindrical surface" described below.

[0039] The waveguide 310 has a waveguide 311 therein. The cylindrical cavity resonator 320 has an introduction opening 343. The introduction opening 343 is also called an iris. The cylindrical cavity resonator 320 also has a cavity 370 therein that communicates with the introduction opening 343. The second object to be heated 20 is heated in the cavity 370. In this embodiment, the waveguide 310 is a rectangular waveguide, and the waveguide 311 is a rectangular waveguide. The cavity 370 has a cylindrical shape. FIG. 3B is a schematic diagram of the waveguide 311 and the cavity 370.

[0040] 3A , the second object to be heated 20 passes through the cavity 370. Microwaves are introduced into the cavity 370 from the waveguide 311 via the introduction opening 343. In this manner, the 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.

[0041] Specifically, in the cavity 370 within the cylindrical cavity resonator 320, microwaves are irradiated onto the second object to be heated 20, thereby dielectrically heating the dielectric contained in the second object to be heated 20. The relative dielectric constant of the dielectric is, for example, not less than 1 and not more than 85. The relative dielectric constant of the dielectric may be not less than 2 and not more than 85.

[0042] Specifically, the dielectric includes water. The water is the water in the coating liquid. When microwaves are applied to the second object to be heated 20, the water is heated, the water evaporates, and the second object to be heated 20 is dried. In this way, the microwave heating according to this embodiment can be intended for drying.

[0043] Microwaves can efficiently evaporate water, which can contribute to reducing the energy required to dry the second object to be heated 20 and reducing the carbon dioxide generated during the drying of the second object to be heated 20.

[0044] In this embodiment, microwaves are irradiated onto the second object to be heated 20 while the second object to be heated 20 is being transported. This improves the productivity of products obtained through heating the second object to be heated 20. However, as another embodiment, when the second object to be heated 20 is a sheet, the transport device 70 may be temporarily stopped once the second object to be heated 20 is transported into the cylindrical cavity resonator 320, and microwaves may be irradiated onto the second object to be heated 20.

[0045] The microwave source, the waveguide 310 and the cylindrical cavity resonator 320 will now be described in detail.

[0046] <3-1. Microwave Source and Waveguide 310> In this embodiment, the waveguide 310 is connected to a microwave source (not shown). The waveguide 310 has an input port (not shown). Microwaves are introduced from the microwave source to the waveguide 311 via the input port.

[0047] Hereinafter, the power of the microwave input to the waveguide 311 in the waveguide 310 will be referred to as microwave power Pi. The microwave power Pi is, for example, 1 W or more and 10 kW or less. In one numerical example, the microwave power Pi is 200 W. In another numerical example, the microwave power Pi is 3 kW.

[0048] Hereinafter, the frequency of the microwaves input to the waveguide 311 in the waveguide 310 will be referred to as microwave frequency f. The microwave frequency f is, for example, 13 MHz or more and 6 GHz or less. In this embodiment, the microwave frequency f is 2.4 GHz or more and 2.5 GHz or less. In one numerical example, the microwave frequency f is 2.45 GHz. In another numerical example, the microwave frequency f is 915 MHz.

[0049] In this embodiment, the power of the microwave output from the microwave source is the microwave power Pi plus the loss in the microwave path from the microwave source to the waveguide 311. The frequency of the microwave output from the microwave source is the same as the microwave frequency f.

[0050] The microwave source may be one that outputs microwaves of a constant power or one that outputs microwaves of a variable power.The microwave source may be one that outputs microwaves of a constant frequency or one that outputs microwaves of a variable frequency.

[0051] The microwave source may be, for example, a magnetron, a semiconductor solid-state device, etc. The microwave source may be a voltage-controlled oscillator (VCO), a voltage-controlled Xtal oscillator (VCXO), or a phase-locked loop (PLL) oscillator. The microwave source may include an amplifier.

[0052] 3B , a waveguide 311 is defined by an inner surface 315 of a waveguide 310. In this embodiment, the expression "B is defined by A" means that A defines B by itself, or A defines B in cooperation with one or more other elements.

[0053] <3-2. Cylindrical Cavity Resonator 320> An example of the resonant frequency of the cavity 370 is the microwave frequency f described above.

[0054] 3A, the cylindrical cavity resonator 320 includes a wall 330. The wall 330 serves as a sidewall surrounding a cavity 370.

[0055] The wall 330 has an inner peripheral surface 335. The inner peripheral surface 335 defines a cavity 370. Hereinafter, the term "central axis 390 of the inner peripheral surface 335" may be used. The central axis 390 of the inner peripheral surface 335 is a virtual central axis for the purpose of explanation and does not necessarily exist in reality. In this embodiment, the central axis 390 does not actually exist.

[0056] In the following description, the expression "axial direction Da of inner circumferential surface 335" may be used. The axial direction Da is the direction in which central axis 390 extends. In the present embodiment, the axial direction Da is equal to the second direction D2.

[0057] Microwaves are introduced into the cylindrical cavity resonator 320 from the inside of the waveguide 310 through the introduction opening 343. Specifically, microwaves are introduced into the cavity 370 from the waveguide 311 through the introduction opening 343.

[0058] In this embodiment, the diameter of the cylindrical shape of the cavity 370 is 80 mm or more and 300 mm or less. Specifically, this diameter is 85 mm or more and 260 mm or less.

[0059] In this embodiment, the dimension of the cavity 370 in the axial direction Da is 250 mm or more and 2050 mm or less. Specifically, this dimension is 300 mm or more and 1500 mm or less.

[0060] The use of the cylindrical cavity resonator 320 is advantageous from the viewpoint of forming a uniform electric field in the internal cavity 370. This is advantageous from the viewpoint of uniformly heating the second object 20 to be heated.

[0061] Uniform heating can improve the quality of the second object to be heated 20. For example, uneven drying, foaming, etc. in the second object to be heated 20 can be suppressed.

[0062] In this embodiment, microwaves are irradiated into the cavity 370 in the cylindrical cavity resonator 320, thereby 0n0 A standing wave of the mode is formed, where n is a natural number equal to or greater than 1. 0n0 Forming a standing wave of the mode is advantageous from the viewpoint of uniformly heating the second object to be heated 20 .

[0063] In this embodiment, n is 1. However, n may be 2, or 3 or more.

[0064] The material of the wall 330 is preferably a material that has good electrical conductivity.

[0065] In one example, the wall 330 is made of metal. Examples of the metal include aluminum, copper, iron, magnesium, brass, stainless steel, and alloys thereof. The metal is preferably aluminum, copper, magnesium, brass, or alloys thereof. In another example, the wall 330 is made of resin, ceramic, metal, or the like, and the inner circumferential surface 335 is coated. Materials including silver, copper, gold, tin, and rhodium can be used for the coating.

[0066] 3A , a first communication hole 351 and a second communication hole 361 are provided in the wall 330. The first communication hole 351 and the second communication hole 361 are through-holes that penetrate the wall 330. In this manner, the wall 330 is provided with a pair of through-holes 351 and 361.

[0067] The transfer path 50 (see FIG. 1 ) passes through the cylindrical cavity resonator 320. Specifically, the transfer path 50 passes through a first communication hole 351 in the cylindrical cavity resonator 320, a cavity 370 in the cylindrical cavity resonator 320, and a second communication hole 361 in the cylindrical cavity resonator 320, in this order. In the cylindrical cavity resonator 320, the first communication hole 351, the cavity 370, and the second communication hole 361 are communicated with each other in this order.

[0068] As can be understood from the above description, the second object to be heated 20 is supplied into the cylindrical cavity resonator 320. In the cylindrical cavity resonator 320, the second object to be heated 20 is heated by microwaves.

[0069] In this embodiment, the conveying device 70 conveys the second object to be heated 20 along the conveying path 50 so that the second object to be heated 20 passes through the first communication hole 351 in the cylindrical cavity resonator 320, the cavity 370 in the cylindrical cavity resonator 320, and the second communication hole 361 in the cylindrical cavity resonator 320 in this order. During this conveying, the second object to be heated 20 is irradiated with microwaves in the cavity 370 in the cylindrical cavity resonator 320, while the second object to be heated 20 has one or more portions protruding from the cylindrical cavity resonator 320. This heats the second object to be heated 20. In this way, 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 second object to be heated 20 is being transported as described above, the second object to be heated 20 has a plurality of portions protruding 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 plurality of portions include a portion on the transport path 50 upstream of the microwave heating device 300 and a portion on the transport path 50 downstream of the microwave heating device 300.

[0070] In this embodiment, the second object to be heated 20 is suspended in the first communication hole 351, the cavity 370, and the second communication hole 361 in the cylindrical cavity resonator 320. Specifically, tension is applied to the second object to be heated 20 so as to separate the second object to be heated 20 from the wall 330, and the second object to be heated 20 is suspended in the air. In this state, the second object to be heated 20 is irradiated with microwaves in the cavity 370 in the cylindrical cavity resonator 320.

[0071] As described above, the tension can be applied by the conveying device 70. A support may be provided upstream and / or downstream of the cylindrical cavity resonator 320 on the conveying path 50, and the second object to be heated 20 may be supported by the support while tension is applied to the second object to be heated 20 to suspend the second object to be heated 20 in mid-air. This configuration makes it easier to homogenize the electric field within the cylindrical cavity resonator 320 compared to a configuration in which a support is provided within the cylindrical cavity resonator 320. However, in another embodiment, a support may be provided within the cylindrical cavity resonator 320. The support, together with the payout roller 100 and the take-up roller 400, constitutes the conveying device 70. The support may be, for example, a support roll, a support belt, or the like.

[0072] Hereinafter, the circumferential direction of the inner circumferential surface 335 will be referred to as a fourth direction D4. In this embodiment, the introduction opening 343 is located in a central area when the area between the pair of through holes 351 and 361 is divided into five parts with respect to the fourth direction D4. Specifically, 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 with respect to the fourth direction D4.

[0073] As described above, in this embodiment, the microwave heating device group 600 is configured using a plurality of microwave heating devices 300. Advantages and the like based on the number of microwave heating devices 300 being a plurality will be further described below.

[0074] Each microwave heating device 300 in the microwave heating device group 600 heats the object S to be heated, specifically the second object 20 to be heated.

[0075] In this embodiment, the microwave heating device group 600 includes M microwave heating devices 300. The microwave heating device group 600 includes M cylindrical cavity resonators 320. M is a natural number equal to or greater than 2. In one example, M is equal to or greater than 2 and equal to or less than 40.

[0076] 4 is a top view of M cylindrical cavity resonators 320. The M cylindrical cavity resonators 320 are arranged at intervals i in an arrangement direction 610. In one example, the interval i is equal to or greater than 100 mm and equal to or less than 500 mm. The arrangement direction 610 will be described later.

[0077] In the microwave heating system 1A, a transfer path 50 is configured that penetrates the walls 330 of the M cylindrical cavity resonators 320 and passes through the M cylindrical cavity resonators 320. A transfer device 70 sequentially transfers the second object 20 to be heated along the transfer path 50 into the M cylindrical cavity resonators 320. Within the M cylindrical cavity resonators 320, the second object 20 is heated by microwaves introduced through the introduction openings 343. Assume that microwave heating of the object to be heated is performed using a single cylindrical cavity resonator. In this case, if there is an upper limit on the microwave power supplied to the cylindrical cavity resonator due to a microwave source or the like, insufficient heating of the object to be heated may occur. In contrast, this configuration allows microwave heating of the second object 20 to be performed using multiple cylindrical cavity resonators 320. This is advantageous from the perspective of avoiding insufficient heating of the second object to be heated 20. It should be noted that there may or may not be an upper limit on the power of the microwaves supplied to the cylindrical cavity resonator 320 .

[0078] Specifically, in each of the M cylindrical cavity resonators 320, microwaves are introduced into a cavity 370 within the cylindrical cavity resonator 320 through an introduction opening 343. An inner circumferential surface 335 defining the cavity 370 and a pair of through holes 351 and 361 are provided in the wall 330 of each of the M cylindrical cavity resonators 320. One of the pair of through holes 351 and 361 is a first communication hole 351, and the other is a second communication hole 361. On the transfer path 50, M rows of the first communication holes 351, the cavity 370, and the second communication holes 361 that communicate with each other are arranged in series. The transfer device 70 transfers the second object to be heated 20 along the transfer path 50. In this way, the conveying device 70 sequentially conveys the second heated objects 20 to the cavities 370 of the M cylindrical cavity resonators 320 by passing the second heated objects 20 through a pair of through holes 351 and 361 of the M cylindrical cavity resonators 320.

[0079] In the present embodiment, while the second object to be heated 20 is transported along the transport path 50 by the transport device 70, microwaves are irradiated onto the second object to be heated 20 in each of the cavities 370 of the M cylindrical cavity resonators 320. This heats the second object to be heated 20.

[0080] In this embodiment, the second object to be heated 20 is transported by the transport device 70 along the transport path 50 so that the second object to be heated 20 sequentially passes through the cavities 370 inside the M cylindrical cavity resonators 320. During this transport, the second object to be heated 20 is irradiated with microwaves in the cavities 370 of the M cylindrical cavity resonators 320, while the second object to be heated 20 has one or more portions located outside the M cylindrical cavity resonators 320. This heats the second object to be heated 20. In this embodiment, it is possible to heat a long second object to be heated 20 having a length spanning the cavities 370 of the M cylindrical cavity resonators 320. Specifically, during the above transport, the second object to be heated 20 is irradiated with microwaves in the cavities 370 of the M cylindrical cavity resonators 320, while the second object to be heated 20 has multiple portions located outside the M cylindrical cavity resonators 320. The multiple portions include portions on the transport path 50 upstream of each of the M cylindrical cavity resonators 320 and portions on the transport path 50 downstream of each of the M cylindrical cavity resonators 320 .

[0081] In this embodiment, the second object to be heated 20 is suspended in the first communication hole 351, the cavity 370, and the second communication hole 361 inside each of the M cylindrical cavity resonators 320. Specifically, with tension applied to the second object to be heated 20 to suspend the second object to be heated 20 in mid-air, the second object to be heated 20 is irradiated with microwaves in the cavity 370 inside each of the M cylindrical cavity resonators 320. In the suspended state, the second object to be heated 20 is spaced apart from the walls 330 of each of the M cylindrical cavity resonators 320.

[0082] As described above, the tension can be applied by the conveying device 70. Supports may be provided upstream and / or downstream of each cylindrical cavity resonator 320 on 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 the second object to be heated 20 in mid-air. This configuration makes it easier to homogenize the electric field within the cylindrical cavity resonator 320 compared to a configuration in which supports are provided within the cylindrical cavity resonator 320. However, in another embodiment, supports may be provided within the cylindrical cavity resonator 320. The supports, together with the unwinding roller 100 and the winding roller 400, form the conveying device 70. The supports may be, for example, support rolls, support belts, etc.

[0083] In this embodiment, the M microwave heating devices 300 include a first microwave heating device 300A and a second microwave heating device 300B. In this embodiment, the cylindrical cavity resonator 320 of the first microwave heating device 300A is referred to as a first cylindrical cavity resonator 320A, the introduction opening 343 provided in the first cylindrical cavity resonator 320A is referred to as a first introduction opening 343A, the cylindrical cavity resonator 320 of the second microwave heating device 300B is referred to as a second cylindrical cavity resonator 320B, and the introduction opening 343 provided in the second cylindrical cavity resonator 320B is referred to as a second introduction opening 343B.

[0084] In this embodiment, among the M microwave heating devices 300, the first microwave heating device 300A and the second microwave heating device 300B are adjacent to each other. In the transport path 50, the second microwave heating device 300B is located downstream of the first microwave heating device 300A.

[0085] In the following, the expressions "arrangement direction 610," "specific direction 620," and "incident direction 630" may be used.

[0086] The arrangement direction 610 is the direction in which the cavities 370 of the M cylindrical cavity resonators 320 are arranged. In this embodiment, the arrangement direction 610 is equal to the first direction D1.

[0087] The incident direction 630 is the direction from the waveguide 310 toward the introduction opening 343. In this embodiment, the incident direction 630 is equal to the third direction D3.

[0088] The specific direction 620 is a direction perpendicular to the arrangement direction 610, and more specifically, a direction perpendicular to the arrangement direction 610 and the incident direction 630. In this embodiment, the specific direction 620 is equal to the second direction D2.

[0089] In this embodiment, the axial directions Da of the M cylindrical cavity resonators 320 are aligned. The specific direction 620 is equal to these axial directions Da.

[0090] Fig. 5A is an explanatory diagram of a microwave heating device group 600 according to a first example of this embodiment. In Fig. 5A, the waveguide 310 and the like are omitted from the illustration. This also applies to Figs. 5B and 5C.

[0091] For convenience of explanation, Fig. 5A shows the case where M = 2. In the first example, M may be 3 or more. The same applies to Fig. 6A.

[0092] In the first example, the first cylindrical cavity resonator 320A and the second cylindrical cavity resonator 320B are arranged so that at least a part of the first introduction opening 343A and at least a part of the second introduction opening 343B are positioned at the same position as each other with respect to the specific direction 620. Specifically, the first cylindrical cavity resonator 320A and the second cylindrical cavity resonator 320B are arranged so that the entire first introduction opening 343A and the entire second introduction opening 343B are positioned at the same position as each other with respect to the specific direction 620.

[0093] 6A is an explanatory diagram of the exposure electric field intensity distribution of a first example of this embodiment. The exposure electric field intensity distribution of the first example is a distribution in a specific direction 620 of the cumulative value of the electric field intensity E to which the second object to be heated 20 is exposed in the microwave heating device group 600 according to the first example.

[0094] Here, the electric field strength En will be described. 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 a component E1 of the electric field E in the first direction D1, a component E2 of the electric field E in the second direction D2, and a component E3 of the electric field E in the third direction D3. Formula 1: En=(E1 2 +E2 2 +E3 2) 1 / 2

[0095] 6A, the horizontal axis represents the position in a specific direction 620. The vertical axis represents the electric field strength E n . These points also apply to FIGS. 6B and 6C.

[0096] 6A , a graph 711 represents the distribution of values ​​originating from the first cylindrical cavity resonator 320A among the distribution of cumulative values ​​of the electric field intensity En to which the second object to be heated 20 is exposed. A graph 712 represents the distribution of values ​​originating from the second cylindrical cavity resonator 320B among the distribution of cumulative values ​​of the electric field intensity En to which the second object to be heated 20 is exposed. Since these values ​​are the same, the graphs 711 and 712 overlap. A graph 713 represents the distribution of cumulative values ​​of the electric field intensity En to which the second object to be heated 20 is exposed, which are originating from both the first cylindrical cavity resonator 320A and the second cylindrical cavity resonator 320B.

[0097] FIG. 5B is an explanatory diagram of a microwave heating device group 600 according to a second example of this embodiment.

[0098] For convenience of explanation, Fig. 5B shows the case where M = 2. In a second example, M may be 3 or more. The same applies to Fig. 6B.

[0099] In the second example, the first cylindrical cavity resonator 320A and the second cylindrical cavity resonator 320B are arranged so that at least a portion of the first introduction opening 343A and at least a portion of the second introduction opening 343B are located at different positions with respect to the specific direction 620. Specifically, the first cylindrical cavity resonator 320A and the second cylindrical cavity resonator 320B are arranged so that the entire first introduction opening 343A and the entire second introduction opening 343B are located at different positions with respect to the specific direction 620. More specifically, the first cylindrical cavity resonator 320A and the second cylindrical cavity resonator 320B are arranged so that the first introduction opening 343A and the second introduction opening 343B are located at positions separated from each other with respect to the specific direction 620.

[0100] 6B is an explanatory diagram of the exposure electric field intensity distribution of a second example of this embodiment. The exposure electric field intensity distribution of the second example is a distribution in a specific direction 620 of the cumulative value of the electric field intensity E to which the second object to be heated 20 is exposed in the microwave heating device group 600 according to the second example.

[0101] 6B , a graph 811 represents the distribution of values ​​originating from the first cylindrical cavity resonator 320A among the distribution of cumulative values ​​of the electric field intensity En to which the second object to be heated 20 is exposed. A graph 812 represents the distribution of values ​​originating from the second cylindrical cavity resonator 320B among the distribution of cumulative values ​​of the electric field intensity En to which the second object to be heated 20 is exposed. A graph 813 represents the distribution of cumulative values ​​of the electric field intensity En to which the second object to be heated 20 is exposed, which are originated from both the first cylindrical cavity resonator 320A and the second cylindrical cavity resonator 320B.

[0102] FIG. 5C is an explanatory diagram of a reference embodiment.

[0103] In the reference embodiment, the first example is modified so that the number of cylindrical cavity resonators 320 is reduced from M to one.

[0104] 6C is an explanatory diagram of the exposure electric field intensity distribution of the reference embodiment. The exposure electric field intensity distribution of the reference embodiment is a distribution in the axial direction Da of the cumulative value of the electric field intensity En to which the second object to be heated 20 is exposed in the cylindrical cavity resonator 320 according to the reference embodiment.

[0105] Compared to the reference embodiment, the first and second examples have a larger number of cylindrical cavity resonators 320. Therefore, even if there is an upper limit due to the microwave source or the like on the power of microwaves supplied from the microwave source to one cylindrical cavity resonator 320, the heat given to the second object to be heated 20 is unlikely to be insufficient. This is advantageous, for example, from the viewpoint of avoiding insufficient heating of the second object to be heated 20.

[0106] Unlike the reference embodiment, in the first and second examples, the heating of the second object to be heated 20 can be shared by multiple cylindrical cavity resonators 320. Therefore, the second object to be heated 20 can be heated without excessively increasing the temporal energy density applied to the second object to be heated 20. This is advantageous from the viewpoint of, for example, avoiding the generation of bubbles in the second object to be heated 20.

[0107] Consider the distribution of the electric field strength En in the axial direction Da in the cavity 370 of one cylindrical cavity resonator 320. In this distribution, the electric field strength En decreases with increasing distance from the introduction opening 343. Therefore, the graph 911 in FIG. 6C has a shape in which the electric field strength En decreases with increasing distance from the introduction opening 343.

[0108] In contrast, in the second example, the first introduction opening 343A and the second introduction opening 343B are misaligned in the specific direction 620. This is advantageous from the viewpoint of equalizing the distribution in the specific direction 620 of the cumulative value of the electric field intensity En to which the second object to be heated 20 is exposed in the microwave heating device group 600. This can be understood from the fact that the shape of the graph 813 in Fig. 6B is flatter than that of the graph 911 in Fig. 6C.

[0109] Hereinafter, the distribution of the electric field strength on the central axis 390 for each of the cavities 370 of the M cylindrical cavity resonators 320 is referred to as the unit electric field distribution, the value obtained by dividing the standard deviation of the unit electric field distribution by the average value of the unit electric field distribution is referred to as the unit electric field fluctuation rate, the unit electric field fluctuation rate of the first cylindrical cavity resonator 320A is referred to as the first electric field fluctuation rate, the distribution obtained by adding up the unit electric field distributions of the M cylindrical cavity resonators 320 is referred to as the total electric field distribution, and the value obtained by dividing the standard deviation of the total electric field distribution by the average value of the total electric field distribution is referred to as the total electric field fluctuation rate.

[0110] In the second example, the total electric field fluctuation rate is smaller than the first electric field fluctuation rate. Specifically, the total electric field fluctuation rate is smaller than the unit electric field fluctuation rate of any of the M cylindrical cavity resonators 320. In this way, in the second example, the distribution of the electric field intensity E in the specific direction 620 can be made uniform.

[0111] In a second example, the overall electric field fluctuation rate is 15% or less. Specifically, the overall electric field fluctuation rate is 1% or more and 9% or less.

[0112] The standard deviation of the unit electric field distribution will now be described. This standard deviation is based on the values ​​at J locations in the distribution that are equally spaced along the axial direction Da. J is a natural number equal to or greater than 5. The same applies to the average value of the unit electric field distribution, the standard deviation of the total electric field distribution, the average value of the total electric field distribution, the unit electric field fluctuation rate, and the total electric field fluctuation rate.

[0113] As shown in Fig. 4, the second object to be heated 20 has a linear region 20r. The linear region 20r crosses the second object to be heated 20 in a transverse direction 640. The transverse direction 640 is a direction perpendicular to the thickness direction of the second object to be heated 20 and the direction in which the second object to be heated 20 is transported. In this embodiment, the transverse direction 640 is the width direction of the object to be heated S. Furthermore, when the object to be heated S is heated by M microwave heating devices 300, the transverse direction 640 is parallel to the second direction D2.

[0114] Hereinafter, the energy distribution on the linear region 20r given by microwave irradiation in each of the M cylindrical cavity resonators 320 will be referred to as a unit energy distribution, the value obtained by dividing the standard deviation of the unit energy distribution by the average value of the unit energy distribution will be referred to as a unit energy fluctuation rate, the unit energy fluctuation rate of the first cylindrical cavity resonator 320A will be referred to as a first energy fluctuation rate, the distribution obtained by adding up the unit energy distributions of the M cylindrical cavity resonators 320 will be referred to as a total energy distribution, and the value obtained by dividing the standard deviation of the total energy distribution by the average value of the total energy distribution will be referred to as a total energy fluctuation rate.

[0115] In the second example, the total energy fluctuation rate is smaller than the first energy fluctuation rate. Specifically, the total energy fluctuation rate is smaller than the unit energy fluctuation rate of any of the M cylindrical cavity resonators 320. In this way, in the second example, the distribution of energy imparted to the linear region 20r in the specific direction 620 can be made uniform.

[0116] In a second example, the total energy fluctuation rate is 20% or less. Specifically, the total electric field fluctuation rate is 1% or more and 16% or less.

[0117] The standard deviation of the unit energy distribution will now be described. These standard deviations are based on values ​​at K locations in the distribution that are equally spaced along the transverse direction 640, where K is a natural number equal to or greater than 5. The same applies to the mean value of the unit energy distribution, the standard deviation of the total energy distribution, the mean value of the unit energy distribution, the unit energy fluctuation rate, and the total energy fluctuation rate.

[0118] (Technologies Applicable to the Embodiments) Hereinafter, technologies applicable to the above-described embodiments will be described.

[0119] The second object to be heated 20 may include a substrate without a coating. In this case, the substrate may contain a dielectric such as water. For example, the substrate can be dried by heating it.

[0120] In the above-described embodiment, 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. The "first object to be heated 10" may be read as the "transported object 10."

[0121] The dielectric of the second object to be heated 20 may contain alcohol in addition to or instead of water. In this case, by heating the second object to be heated 20, the alcohol can be evaporated and the second object to be heated 20 can be dried.

[0122] The purpose of microwave heating may be annealing.

[0123] (Additional Note) The present disclosure discloses the following techniques.

[0124] (Technology 1) A microwave heating system comprising: two or more cylindrical cavity resonators; and a transport device that sequentially transports an object to be heated into the two or more cylindrical cavity resonators, wherein each of the two or more cylindrical cavity resonators has an introduction opening that introduces microwaves into the cylindrical cavity resonator, and the object to be heated is heated by the microwaves in the two or more cylindrical cavity resonators.

[0125] (Technology 2) The microwave is irradiated into each of the two or more cylindrical cavity resonators, thereby generating a TM 0n0 A microwave heating system according to claim 1, wherein a standing wave of a mode is formed, and n is a natural number equal to or greater than 1.

[0126] (Technology 3) The microwave heating system according to Technology 1 or 2, wherein in each of the two or more cylindrical cavity resonators, the microwave is introduced into a cavity in the cylindrical cavity resonator from the introduction opening, and a wall of the cylindrical cavity resonator is provided with an inner circumferential surface and a pair of through holes that define the cavity, and the transport device sequentially transports the object to be heated to the cavity of the two or more cylindrical cavity resonators by making the object to be heated pass through the pair of through holes of the two or more cylindrical cavity resonators.

[0127] (Technology 4) The microwave heating system according to Technology 3, wherein the two or more cylindrical cavity resonators include a first cylindrical cavity resonator and a second cylindrical cavity resonator, and at least a part of the introduction opening of the first cylindrical cavity resonator and at least a part of the introduction opening of the second cylindrical cavity resonator are located at different positions in a direction perpendicular to a direction in which the two or more cylindrical cavity resonators are arranged.

[0128] (Technology 5) The microwave heating system according to Technology 4, wherein the introduction opening of the first cylindrical cavity resonator and the introduction opening of the second cylindrical cavity resonator are positioned apart from each other in the direction orthogonal to the direction in which the two or more cylindrical cavity resonators are arranged.

[0129] (Technology 6) The microwave heating system according to any one of Technologies 3 to 5, wherein the two or more cylindrical cavity resonators include a first cylindrical cavity resonator, and a distribution of electric field strength on a central axis of the inner circumferential surface for each of the cavities of the two or more cylindrical cavity resonators is expressed as a unit electric field distribution, a value obtained by dividing the standard deviation of the unit electric field distribution by the average value of the unit electric field distribution is expressed as a unit electric field fluctuation rate, the unit electric field fluctuation rate of the first cylindrical cavity resonator is expressed as a first electric field fluctuation rate, a distribution obtained by summing the unit electric field distributions of the two or more cylindrical cavity resonators is expressed as a total electric field distribution, and a value obtained by dividing the standard deviation of the total electric field distribution by the average value of the total electric field distribution is expressed as a total electric field fluctuation rate, wherein the total electric field fluctuation rate is smaller than the first electric field fluctuation rate.

[0130] (Technology 7) A microwave heating method using the microwave heating system according to any one of Technologies 1 to 6, comprising irradiating the object to be heated with the microwaves in each of the two or more cylindrical cavity resonators while transporting the object to be heated by the transport device.

[0131] (Technology 8) The microwave heating method according to Technology 7, further comprising: dielectrically heating a dielectric material contained in the object to be heated by the microwaves in each of the two or more cylindrical cavity resonators.

[0132] (Technology 9) The microwave heating method according to Technology 8, wherein the dielectric contains water.

[0133] (Technology 10) The microwave heating method according to any one of Techniques 7 to 9, comprising: irradiating the object to be heated with the microwaves in each of the two or more cylindrical cavity resonators while transporting the object to be heated so that the object passes through the interiors of the two or more cylindrical cavity resonators, in a state in which the object to be heated has a part located outside the two or more cylindrical cavity resonators.

[0134] (Technology 11) The microwave heating method according to any one of Techniques 7 to 10, further comprising suspending the object to be heated in each of the two or more cylindrical cavity resonators.

[0135] (Technology 12) The microwave heating method according to any one of Techniques 7 to 11, wherein the object to be heated has a linear region that crosses the object to be heated in a direction perpendicular to a thickness direction of the object to be heated and a direction in which the object to be heated is transported, and the two or more cylindrical cavity resonators include a first cylindrical cavity resonator, and in each of the two or more cylindrical cavity resonators, a distribution of energy on the linear region provided by irradiation of the microwaves is referred to as a unit energy distribution, and a value obtained by dividing a standard deviation of the unit energy distribution by an average value of the unit energy distribution is referred to as a unit energy fluctuation rate, and the unit energy fluctuation rate of the first cylindrical cavity resonator is referred to as a first energy fluctuation rate, and a distribution obtained by summing the unit energy distributions of the two or more cylindrical cavity resonators is referred to as a total energy distribution, and when a value obtained by dividing the standard deviation of the total energy distribution by the average value of the total energy distribution is referred to as a total energy fluctuation rate, the total energy fluctuation rate is smaller than the first energy fluctuation rate.

[0136] The technology according to the present invention can be applied to, for example, microwave drying.

[0137] For example, a film may be formed using a coating liquid diluted with a solvent or dispersion medium, and the film may then be dried. From the viewpoint of improving environmental friendliness, it may be considered to change the solvent or dispersion medium from one containing an organic compound to one containing water. In this case, the energy required to evaporate the solvent or dispersion medium may increase. In this regard, microwave drying technology can efficiently evaporate a solvent or dispersion medium containing water, compared to drying technology using hot air or the like. Therefore, it is easy to improve environmental friendliness, even when the energy required to evaporate water is taken into account.

Claims

1. A microwave heating system comprising: two or more cylindrical cavity resonators; and a transport device that sequentially transports an object to be heated into the two or more cylindrical cavity resonators, each of the two or more cylindrical cavity resonators having an introduction opening for introducing microwaves into the cylindrical cavity resonator; and the object to be heated is heated by the microwaves in the two or more cylindrical cavity resonators.

2. The microwave is irradiated into each of the two or more cylindrical cavity resonators, thereby generating a TM. 0n0 The microwave heating system according to claim 1 , wherein a standing wave of a mode is formed, and n is a natural number equal to or greater than 1.

3. The microwave heating system according to claim 1, wherein in each of the two or more cylindrical cavity resonators, the microwaves are introduced into a cavity within the cylindrical cavity resonator from the introduction opening, and a wall of the cylindrical cavity resonator is provided with an inner circumferential surface and a pair of through holes that define the cavity, and the transport device sequentially transports the object to be heated to the cavity of the two or more cylindrical cavity resonators by passing the object to be heated through the pair of through holes of the two or more cylindrical cavity resonators.

4. The microwave heating system according to claim 3, wherein the two or more cylindrical cavity resonators include a first cylindrical cavity resonator and a second cylindrical cavity resonator, and at least a part of the introduction opening of the first cylindrical cavity resonator and at least a part of the introduction opening of the second cylindrical cavity resonator are located at different positions in a direction perpendicular to a direction in which the two or more cylindrical cavity resonators are arranged.

5. The microwave heating system according to claim 4, wherein the introduction opening of the first cylindrical cavity resonator and the introduction opening of the second cylindrical cavity resonator are positioned apart from each other in the direction perpendicular to the direction in which the two or more cylindrical cavity resonators are arranged.

6. The microwave heating system according to claim 3, wherein the two or more cylindrical cavity resonators include a first cylindrical cavity resonator, and wherein a distribution of electric field strength on a central axis of the inner circumferential surface for each of the cavities of the two or more cylindrical cavity resonators is expressed as a unit electric field distribution, a value obtained by dividing the standard deviation of the unit electric field distribution by the average value of the unit electric field distribution is expressed as a unit electric field fluctuation rate, the unit electric field fluctuation rate of the first cylindrical cavity resonator is expressed as a first electric field fluctuation rate, a distribution obtained by summing the unit electric field distributions of the two or more cylindrical cavity resonators is expressed as a total electric field distribution, and a value obtained by dividing the standard deviation of the total electric field distribution by the average value of the total electric field distribution is expressed as a total electric field fluctuation rate, wherein the total electric field fluctuation rate is smaller than the first electric field fluctuation rate.

7. A microwave heating method using the microwave heating system according to any one of claims 1 to 6, comprising irradiating the object to be heated with the microwaves in each of the two or more cylindrical cavity resonators while transporting the object to be heated by the transport device.

8. The microwave heating method according to claim 7, further comprising dielectrically heating a dielectric material contained in the object to be heated by the microwaves in each of the two or more cylindrical cavity resonators.

9. The microwave heating method of claim 8, wherein the dielectric material comprises water.

10. The microwave heating method according to claim 7, comprising irradiating the object to be heated with the microwaves in each of the two or more cylindrical cavity resonators while transporting the object to be heated so that the object passes through the interiors of the two or more cylindrical cavity resonators, with the object to be heated having a portion located outside the two or more cylindrical cavity resonators.

11. The microwave heating method according to claim 7, further comprising suspending the object to be heated in each of the two or more cylindrical cavity resonators.

12. The microwave heating method according to claim 7, wherein the object to be heated has a linear region that crosses the object to be heated in a direction perpendicular to a thickness direction of the object to be heated and a direction in which the object to be heated is transported, the two or more cylindrical cavity resonators include a first cylindrical cavity resonator, in each of the two or more cylindrical cavity resonators, a distribution of energy on the linear region provided by irradiation of the microwaves is expressed as a unit energy distribution, a value obtained by dividing the standard deviation of the unit energy distribution by the average value of the unit energy distribution is expressed as a unit energy fluctuation rate, the unit energy fluctuation rate of the first cylindrical cavity resonator is expressed as a first energy fluctuation rate, a distribution obtained by adding up the unit energy distributions of the two or more cylindrical cavity resonators is expressed as a total energy distribution, and when a value obtained by dividing the standard deviation of the total energy distribution by the average value of the total energy distribution is expressed as a total energy fluctuation rate, the total energy fluctuation rate is smaller than the first energy fluctuation rate.

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