JP2022183636A - electromagnetic wave heating device - Google Patents

Abstract

To enable an oscillation frequency to fast follow a resonant frequency regarding an electromagnetic wave heating device where resonance is generated by an electromagnetic wave in a radiation antenna.SOLUTION: An electromagnetic wave heating device 10 comprises a radiation antenna 22 having a resonance structure in which resonance is generated by an electromagnetic wave. The electromagnetic wave heating device 10 further comprises: a signal extraction unit 76 for extracting reflection wave information representing the waveform of a reflection wave; a phase difference information generation unit 77 for generating phase difference information representing the phase difference between an incident wave and the reflection wave through arithmetic processing using incident wave information representing the waveform of the incident wave and the reflection wave information; and a control unit 78 for repeatedly performing control processing of detecting an adjustment direction of an oscillation frequency in which the difference between a resonant frequency in the radiation antenna 22 and the oscillation frequency of an oscillator 21 is reduced based on reference information in a state where the phase of the incident wave is equal to the phase of the reflection wave and the phase difference information, and controlling the oscillation frequency based on the detected adjustment direction.SELECTED DRAWING: Figure 7

Description

TECHNICAL FIELD The present invention relates to an electromagnetic wave heating device and the like used for heating an object to be heated.

2. Description of the Related Art Conventionally, dielectric heating type electromagnetic wave heating apparatuses have been used for various purposes such as heating food. In this type of electromagnetic wave heating apparatus, electromagnetic waves are applied to the dielectric contained in the object to be heated. Then, due to the action of the electric field of the electromagnetic wave, the dipole at the molecular level in the dielectric vibrates, and the dielectric loss associated with the vibration generates heat, thereby heating the object to be heated. In addition, as another type of electromagnetic wave heating device, if the object to be heated contains a conductive component or an ionic substance, it can be heated by the conduction (Joule) loss caused by the current, and if the object to be heated contains a magnetic component, by the magnetic loss. There is a device that heats things.

Japanese Patent Application Laid-Open No. 2002-201002 describes a dielectric heating unit that heats and melts a toner image to dielectrically heat a fixing member that fixes the toner image on a recording medium. The dielectric heating unit has at least a pair of rod-shaped electrodes that form a high-frequency electric field around the dielectric of the fixing member so as to face the outer peripheral surface and/or the inner peripheral surface of the fixing member. The rod-shaped electrodes are arranged to have different polarities from adjacent rod-shaped electrodes, and are supplied with high-frequency power from a power supply.

Further, Patent Literature 2 describes a high-frequency power supply that performs frequency control for impedance matching of the high-frequency power supply by two-step control of phase control and reflected power control.

Japanese Patent Application Laid-Open No. 2008-292606 Japanese Patent No. 6157036

By the way, Patent Literature 1 describes experimental results using a high frequency of 40 MHz. In this case, the wavelength of the high frequency is approximately 7.5 m. From this, it is considered that in the prior art described in Patent Document 1, the electric field in the longitudinal direction is substantially uniform in each rod-like electrode. On the other hand, the inventor of the present application believes that the stronger the electric field, the more easily the electromagnetic wave is absorbed by the object to be heated, and the object to be heated can be efficiently heated. We considered an electromagnetic wave heating device that causes resonance due to electromagnetic waves.

However, in such an electromagnetic wave heating device, the resonance frequency of the radiation antenna may change sequentially depending on the object to be heated, etc. In this case, it has been difficult to maintain an efficient heating state. Therefore, the inventors of the present application considered application of frequency control for controlling the oscillation frequency of the oscillator with respect to the resonance frequency.

Here, in conventional frequency control, phase control and reflected power control are performed in order. However, since it takes time to detect the reflected power in the reflected power control, the conventional frequency control cannot make the oscillation frequency follow the resonance frequency at high speed.

The present invention has been made in view of such circumstances, and provides an electromagnetic wave heating apparatus in which resonance due to electromagnetic waves occurs in a radiating antenna, which is configured so that the oscillation frequency can follow the resonance frequency at high speed. aim.

In order to solve the above-described problems, a first invention includes an oscillator that outputs electromagnetic waves, and a radiation antenna having a resonant structure in which resonance is caused by electromagnetic waves in a frequency band transmitted from the oscillator, and is formed of a resonant structure. An electromagnetic wave heating device for heating an object to be heated in a strong electric field region of electromagnetic waves, which is provided on a transmission line extending from an oscillator to a radiation antenna, and is a signal extractor for extracting reflected wave information representing the waveform of the reflected wave returning from the radiation antenna. Phase difference information for generating phase difference information representing the phase difference between the incident wave and the reflected wave by arithmetic processing using the section, incident wave information representing the waveform of the incident wave transmitted from the oscillator to the radiating antenna, and reflected wave information. An oscillation frequency that reduces the difference between the resonance frequency of the radiating antenna and the oscillation frequency of the oscillator based on the generation unit, the reference information in a state where the phase of the incident wave and the phase of the reflected wave are equal, and the phase difference information. A control unit that detects the adjustment direction and repeatedly performs control processing for controlling the oscillation frequency based on the detected adjustment direction.

In a second aspect based on the first aspect, the control unit detects a deviation direction of the oscillation frequency from the resonance frequency using the reference information and the phase difference information, and averages the detection results. detects the adjustment direction of the oscillation frequency.

In a third aspect based on the second aspect, the object to be heated is conveyed so as to pass through the strong electric field region, and the control unit samples the detection results used for the averaging process based on the conveying speed of the object to be heated. adjust the number.

In a fourth aspect of the invention, in any one of the first to third aspects, the oscillator further comprises an orthogonal demodulator that outputs an orthogonally modulated electromagnetic wave to the radiation antenna and orthogonally demodulates the reflected wave information; Phase difference information is generated by arithmetic processing using first I component information and first Q component information forming information and second I component information and second Q component information forming reflected wave information.

In a fifth aspect based on the fourth aspect, the signal extractor extracts incident wave information from the transmission line, and the quadrature demodulator includes one quadrature demodulator, and the signal extractor transmits the incident wave information to the quadrature demodulator. a selector switch for switching between a first period during which the wave information is input and a second period during which the reflected wave information is input; Switching of the second period is performed.

In a sixth aspect based on any one of the first to fifth aspects, the signal extractor extracts incident wave information from the transmission line and transmits the incident wave information from the signal extractor to the phase difference information generator. The line is provided with a delay line or delay element for correcting the phase shift between the incident wave information and the reflected wave information.

In a seventh aspect based on any one of the first to fourth aspects, the control unit is configured to generate phase difference information using phase incident wave information at the output timing of the electromagnetic wave from the oscillator. , before the arithmetic processing, the incident wave information is corrected for the phase shift from the reflected wave information.

In an eighth invention, in any one of the first to seventh inventions, the control unit estimates the amount of electromagnetic wave energy absorbed by the object to be heated based on the phase difference information, and based on the estimation result Controls oscillator output.

In a ninth aspect based on any one of the first to eighth aspects, the reference information is a threshold range having a predetermined width, and the controller controls the heating target state of the object to be heated. is estimated, and the width of the threshold range is adjusted based on the estimated result.

In a tenth aspect, in any one of the first to ninth inventions, a plurality of objects to be heated are conveyed at intervals so as to pass through the strong electric field region in order, and the controller controls one object to be heated. During the period in which frequency control is performed to repeat the control process while the object to be heated passes through the strong electric field region, control history information of the frequency control is recorded, and the object to be heated that passes through the strong electric field region after the recording is heated, Frequency control is performed using the control history information.

In an eleventh invention, in any one of the first to tenth inventions, a plurality of objects to be heated are conveyed at intervals so as to sequentially pass through the strong electric field region, and the objects to be heated are the printing apparatus. The control unit uses information on the print pattern of the object to be heated to adjust the control parameters of the control process.

In a twelfth invention, in any one of the first to eleventh inventions, the internal space in which the radiation antenna is arranged is shielded from the outside, and an introduction part and an extraction part for the conveyed object including the object to be heated are formed. , the inner space further includes a shielding portion for conveying the object to be heated from the introduction portion toward the outlet portion so that the object to be heated passes through the area facing the radiation antenna.

In the present invention, a phase difference signal representing the phase difference between the incident wave and the reflected wave is generated by arithmetic processing using the incident wave information and the reflected wave information. Then, the direction of adjustment of the oscillation frequency is detected based on the phase difference signal and the reference information, and control processing for controlling the oscillation frequency based on the detection result is repeatedly performed, so that the oscillation frequency follows the resonance frequency. do. Here, arithmetic processing using incident wave information and reflected wave information can be performed at high speed. That is, phase difference information can be generated at high speed. Moreover, since the reference information can be prepared in advance, the adjustment direction of the oscillation frequency can also be detected at high speed. According to the present invention, it is possible to cause the oscillation frequency to follow the resonance frequency at high speed.

FIG. 1 is a perspective view of the electromagnetic wave heating device according to the first embodiment, with the cover removed, as viewed obliquely from above. FIG. 2 is a perspective view of the electromagnetic wave heating device according to the first embodiment, viewed obliquely from above. 3 is a cross-sectional view taken along line AA of FIG. 2. FIG. FIG. 4 is a cross-sectional view taken along line BB of FIG. 2, showing a state in which the substrate is being conveyed. FIG. 5 is a cross-sectional view of the electromagnetic wave heating device according to the first embodiment. FIG. 6 is a schematic circuit diagram of the electromagnetic wave heating device according to the first embodiment. FIG. 7 is a flowchart of processing performed by the control unit of the electromagnetic wave heating device according to the first embodiment. FIG. 8 is a table including graphs and the like showing the relationship between the resonance frequency and the phase difference voltage. FIGS. 9A to 9F are charts for explaining how the oscillation frequency follows the resonance frequency. FIG. 10 is a chart for explaining averaging processing according to the first modification of the first embodiment. FIG. 11 is a schematic circuit diagram of an electromagnetic wave heating device according to the second embodiment. FIG. 12 is a flow chart of processing performed by the controller of the electromagnetic wave heating device according to the second embodiment. FIG. 13 is a diagram (Smith chart) for explaining how the oscillation frequency follows the resonance frequency. FIG. 14 is a schematic circuit diagram of an electromagnetic wave heating device according to a first modified example of the second embodiment. FIG. 15 is a schematic circuit diagram of an electromagnetic wave heating device according to a second modification of the second embodiment. FIG. 16 is a schematic circuit diagram of an electromagnetic wave heating device according to the third embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail, referring drawings. It should be noted that the following embodiments and modifications are examples of the present invention, and are not intended to limit the scope of the present invention, its applications, or its uses.

<First embodiment>
This embodiment is an electromagnetic wave heating device 10 that heats an object 20 to be heated using electromagnetic waves such as high frequencies. The electromagnetic wave heating device 10 is a dielectric heating type heating device. The electromagnetic waves used in the electromagnetic wave heating device 10 are high frequencies (eg, microwaves) of 800 MHz or higher.

An object 20 to be heated by the electromagnetic wave heating device 10 includes a substance (liquid, solid, etc.) that absorbs high frequencies. The object to be heated 20 is a thin object with a small thickness and has a sheet shape or a film shape. The object to be heated 20 is, for example, an adhesive. The object to be heated 20 is applied or placed on the surface of a sheet-like long base material (transported object) 11 . The object 20 to be heated is conveyed in a predetermined direction (the direction of the arrow shown in FIG. 1) together with the base material 11, and passes through a high-frequency strong electric field region. At that time, the object to be heated 20 is heated by absorbing the high frequency. Note that the object to be heated 20 may not be sheet-like or film-like, and may have a certain amount of thickness. Moreover, in the case where the object to be heated 20 is an adhesive applied to a sheet such as an envelope, the object to be heated 20 may be conveyed together with the sheet and the base material 11 .

The electromagnetic wave heating device 10 includes an upstream device (for example, an adhesive coating device, not shown) that applies or arranges the object 20 to be heated on the surface of the base material 11, and at least the electromagnetic wave heating device 10 from the inlet of the upstream device. Together with the transport mechanism 12 that transports the substrate 11 in the processing section up to the exit, a transport-type processing system is configured. The transport mechanism 12 transports the substrate 11 and the object to be heated 20 using a plurality of pairs of rollers 13 (see FIG. 4). Hereinafter, the direction in which the substrate 11 is conveyed will be referred to as the "first direction", and the direction perpendicular to the first direction will be referred to as the "second direction" (see FIG. 1, etc.). In addition, in the electromagnetic wave heating device 10, the cover 50 side is called "front side", and the substrate 23 side is called "back side" (see FIG. 2, etc.).

[Configuration of electromagnetic wave heating device]
As shown in FIGS. 1 and 2, the electromagnetic wave heating device 10 is provided with an oscillator 21 that oscillates high frequencies, a radiation antenna 22 that radiates high frequencies for heating an object 20 to be heated, and a radiation antenna 22 on one side. , a cover 50 covering the substrate 23 on the side of the radiation antenna 22 , and a controller 75 for controlling the oscillator 21 . Details of the control device 75 will be described later.

A semiconductor oscillator, for example, is used for the oscillator 21 . The substrate 23 and the cover 50 are made of metal. The substrate 23 is grounded. The substrate 23 and the cover 50 constitute a shielding portion 60 that shields the internal space 40 (see FIG. 3) in which the radiation antenna 22 is arranged from the outside. The cover 50 constitutes a first partition section that partitions the inner space 40 of the shielding section 60 from one side (upper side). The substrate 23 constitutes a second partition section that partitions the internal space 40 from the opposite side (lower side) of the first partition section. Between the substrate 23 and the cover 50, a continuous gap 70 is formed that continues in the circumferential direction at the outer peripheral portion of the shielding portion 60 in plan view.

The radiation antenna 22 is composed of an interdigital circuit. The radiation antenna 22 includes a first comb-teeth electrode 31 and a second comb-teeth electrode 32 that meshes with the first comb-teeth electrode 31 with a gap therebetween. The first comb-teeth electrode 31 is formed in a comb shape with a plurality of teeth 31a. The second comb-teeth electrode 32 is formed in a comb shape with a plurality of teeth 32a.

The first comb-teeth electrode 31 includes a base line 31b extending straight and a plurality of teeth 31a having roots connected to the base line 31b. The plurality of tooth portions 31a are provided parallel to each other. Each tooth 31a extends obliquely from the base line 31b. The plurality of tooth portions 31a are arranged at regular intervals in the first direction.

The second comb-teeth electrode 32 includes a base line 32b extending straight and a plurality of teeth 32a having roots connected to the base line 32b. The base line 32 b is parallel to the base line 31 b of the first comb tooth-shaped electrode 31 . The plurality of tooth portions 32a are provided parallel to each other. The teeth 32 a of the second comb-teeth electrode 32 are parallel to the teeth 31 a of the first comb-teeth electrode 31 . Each tooth 32a extends obliquely from the base track 32b. The plurality of tooth portions 32a are arranged at regular intervals in the first direction.

In the radiation antenna 22, a plurality of tooth portions 31a and 32a are arranged with a gap in a predetermined direction (first direction) in the same plane. A region in which the plurality of tooth portions 31a and 32a are arranged (hereinafter referred to as an "arranged region") is a strip-shaped region in plan view. The total number of tooth portions (conductor lines) 31a and 32a arranged in the first direction may be 3 or more, and may be 10 or more as in the present embodiment.

The radiation antenna 22 has a first connection that connects the first comb-shaped electrode 31 and the second comb-shaped electrode 32 on one end side of the arrangement region in the first direction in addition to the first comb-shaped electrode 31 and the second comb-shaped electrode 32 . It has a line 41 and a second connection line 42 that connects the first comb-teeth electrode 31 and the second comb-teeth electrode 32 on the other end side of the arrangement region. The radiating antenna 22 is a closed circuit. An input section 30 to which a high frequency signal from the oscillator 21 is input is connected to the first connection line 41 . The input section 30 is, for example, a coaxial connector, and is connected to the oscillator 21 via a coaxial line. The input section 30 is provided on the back side of the board 23 . A strong electric field region for heating the object 20 to be heated is formed in the area facing the radiation antenna 22 (the area above the arrangement area) during the input period in which the high frequency is input to the input unit 30 . The strong electric field region is formed in the vicinity of the front side of the radiating antenna 22 in the facing region, and is a parallel and thin region.

The radiation antenna 22 is configured to generate high-frequency resonance in the high-frequency frequency band in which the oscillator 21 oscillates during the input period described above. In the radiation antenna 22, high-frequency resonance occurs simultaneously in the teeth 31a and 32a. The length L1 of the tooth portion 31a and the length L2 of the tooth portion 32a are designed using Equations 1 and 2, where λ is the wavelength (electrical length) of the transmitted high frequency (n ₁ , _n2 is a natural number). The total length of adjacent teeth 31a and teeth 32a is represented by 2m×λ/4 (m is a natural number). In this embodiment, the lengths L1 and L2 of the tooth portions 31a and 32a are both λ/4. The tooth portions 31a of the first comb-teeth electrode 31 and the tooth portions 32a of the second comb-teeth electrode 32 have the same length, but they may have different lengths.
Formula 1: L1=λ×(2n ₁ −1)/4
Equation 2: L2=λ×(2n ₂ −1)/4

The radiation antenna 22 is configured such that relatively strong electric field coupling is generated between the tooth portions 31a and 32a adjacent in the first direction during the above-described input period. Specifically, in the radiation antenna 22, a plurality of teeth 31a and 32a are arranged at equal intervals in the first direction, and the distance (gap dimension) between the teeth 31a and 32a adjacent to each other in the first direction is equal to the tooth 31a. , 32a is five times or less. This distance may be three times or less the line width of the tooth portions 31a and 32a, or may be one time or less. Although the tooth portions 31a of the first comb-teeth electrode 31 and the tooth portions 32a of the second comb-teeth electrode 32 have the same line width, they may have different line widths.

The substrate 23 is configured using, for example, a metal plate. The planar shape of the substrate 23 is substantially rectangular. The longitudinal direction of the substrate 23 matches the first direction. A concave portion 24 having a substantially rectangular planar shape is formed on the front side of the substrate 23 . The longitudinal direction of the concave portion 24 also coincides with the first direction. A radiation antenna 22 is housed in the recess 24 . In the concave portion 24, the radiating antenna 22 is supported in a floating state by, for example, a dielectric (not shown) provided on the bottom surface. Radiation antenna 22 is electrically insulated from the metal portion of substrate 23 . The area of the surface of the substrate 23 other than the concave portion 24 is a flat area 27 surrounding the radiation antenna 22 . The height position of the flat area 27 is, for example, approximately the same as, slightly above, or below the upper surface of the radiating antenna 22 .

In this embodiment, the substrate 23 is composed of a frame-shaped front metal plate 23a and a rectangular back metal plate 23b superimposed on the back surface of the front metal plate 23a. It may be composed of a single metal plate in which the concave portion 24 is formed. Also, the surface of the flat region 27 and/or the upper surface of the radiation antenna 22 may be coated with a coating that absorbs high frequencies (for example, a dielectric coating) in order to suppress the occurrence of discharge due to a strong electric field.

The cover 50 is a metal housing. As shown in FIGS. 2 and 3, the cover 50 includes a main body portion 51 that covers the radiation antenna 22 from the front side, an outer peripheral portion 52 that is integrated with the main body portion 51 so as to surround the entire circumference of the main body portion 51, and a main body portion. and a duct portion 53 connected to the upper surface of the portion 51 . An air blower 35 for supplying air to the object to be heated 20 conveyed in the internal space 40 is attached to the outer end of the duct portion 53 .

The body portion 51 has a substantially rectangular shape in a plan view, and has, for example, approximately the same planar dimension as the recess 24 . The body portion 51 is positioned directly above the recess 24 . The body portion 51 is formed in a box shape with an open bottom. As shown in FIG. 4 , the internal space of the body portion 51 and the internal space of the duct portion 53 are connected to each other to form an air passage 45 through which air flows from the blower 35 toward the object 20 to be heated.

The outer peripheral portion 52 is a portion outside the main body portion 51 and has a substantially rectangular frame shape in plan view. The outer peripheral portion 52 faces the flat region 27 of the substrate 23 via a continuous gap 70 in the circumferential direction. A shield structure 55 for preventing high-frequency leakage through the continuous gap 70 is provided all around the outer peripheral portion 52 . The shield structure 55 is composed of a choke structure 55, for example. The structure and shape of the choke structure are not particularly limited, but a short-circuit type λ/4 resonant choke can be adopted. The choke structure 55 is composed of a spiral (or ring-shaped) cavity in a cross-sectional view, and opens at a position near the radiation antenna 22 . As for the dimensions of the choke structure 55, for example, the circumference in cross section is "λ/2×a (a is a natural number)" and the depth is "λ/4×b (b is a natural number)". λ is the high frequency electrical length in the choke structure 55 .

The duct portion 53 is arranged on the upstream side (introduction portion 71 side) in the conveying direction (first direction) of the base material 11 . The duct portion 53 is inclined downward toward the downstream side in the first direction. The blowing direction of the blower 35 faces the downstream side in the first direction. A plurality of wind direction adjusting plates 68 are provided on the inner surface of the body portion 51 . Each wind direction adjusting plate 68 is, for example, a louver, and directs the wind toward the downstream side in the first direction. With these configurations, the air blown from the blower 35 flows toward the downstream side in the first direction, is mainly discharged to the outside from the lead-out portion 72 of the continuous gap 70, and is partially discharged from the side gaps 73 and 74. discharged from In FIGS. 4 and 5 , white arrows represent the wind direction of the air supplied from the blower 35 to the object 20 to be heated. In FIG. 5, the portion of the cover 50 above the shield member 46 is omitted. Note that the wind direction adjusting plate 68 may be omitted.

In the ventilation passage 45, there is a metal shield member 46 formed with a through hole 46a that shields the blower 35 from high frequencies radiated from the radiating antenna 22 and passes air from the blower 35 toward the object 20 to be heated. is provided. The shield member 46 is formed in a plate shape. The shield member 46 is attached to the main body 51 so as to partition the air passage 45 into upstream and downstream sides (divide it vertically). A plurality of through holes 46 a are formed in the shield member 46 . Each through-hole 46a is formed in a size that prevents the high frequency radiated from the radiating antenna 22 from passing through.

[Configuration of Shielding Part]
The configuration of the shielding portion 60 will be described with reference to FIGS. 3 and 4 and the like.

The shielding part 60 is a housing that accommodates the radiation antenna 22 in the internal space 40 and is composed of the substrate 23 and the cover 50 . The shielding portion 60 is configured to allow passage of the base material 11 by providing an introduction portion 71 and a lead-out portion 72 and the like so that the internal space 40 serves as a shielding space. In the internal space 40 , the substrate 11 is conveyed from the lead-in portion 71 toward the lead-out portion 72 so that the object 20 to be heated passes through the facing area of the radiation antenna 22 .

The shielding portion 60 is provided with a continuous gap 70 extending along the entire circumference of the side portion of the shielding portion 60 as a gap that communicates the internal space 40 with the outside. For example, in the shielding part 60 , the cover 50 is supported by a supporting member (not shown) so as to be floating with respect to the substrate 23 .

The continuous gap 70 is formed by the upper surface of the flat region 27 of the substrate 23 and the lower surface of the outer peripheral portion 52 of the cover 50 in a cross-sectional view. A gap dimension of the continuous gap 70 in a cross-sectional view (a distance between the flat region 27 and the outer peripheral portion 52) is constant over the entire circumference of the shielding portion 60, for example. The lower limit value of the gap dimension of the continuous gap 70 may be any dimension that allows the substrate (conveyed object) 11 to pass through. The upper limit of the gap dimension of the continuous gap 70 is only required to substantially prevent high-frequency leakage to the outside, and is, for example, 30 mm or less, preferably 10 mm or less, and more preferably 5 mm or less.

The continuous gap 70 includes an introduction portion 71 into which the substrate 11 including the object 20 to be heated is introduced, an extraction portion 72 into which the substrate 11 is extracted, and a pair of continuous gaps 70 extending in the conveying direction of the substrate 11 on both sides of the facing area. , and side gaps 73 and 74. The continuous gap 70 is formed on four sides, ie, the upstream side in the first direction, the downstream side in the first direction, and both sides in the second direction when viewed from the facing area of the radiating antenna 22 in plan view. In addition, in this specification, the "side" of the facing area means a direction perpendicular to the transport direction.

Specifically, each of the lead-in portion 71 and the lead-out portion 72 is constituted by a gap formed between the short side portion of the flat region 27 of the substrate 23 and the outer peripheral portion 52 facing the short side portion. . Each of the side gaps 73 and 74 is formed by a gap formed between the long side portion of the flat region 27 of the substrate 23 and the outer peripheral portion 52 facing the long side portion. The lateral gaps 73 and 74 are connected to the introduction portion 71 and the lead-out portion 72, respectively.

[Processing system operation]
The operation of the processing system including the electromagnetic wave heating device 10 will be described. When the power of the processing system is turned on, the power of each of the electromagnetic wave heating device 10 and the transport mechanism 12 is turned on. As a result, the substrate 11 is transported by the transport mechanism 12 and the oscillator 21 oscillates a high frequency. The operation of the control device 75 that controls the oscillator 21 will be described later. The substrate 11 is conveyed in the vicinity of the front side of the radiation antenna 22 with the object 20 to be heated facing the front side (upper side in FIG. 1). In addition, the base material 11 may be conveyed with the object to be heated 20 facing the back side.

In the electromagnetic wave heating device 10 , the high frequency waves output from the oscillator 21 are supplied to the teeth 31 a of the first comb-teeth electrode 31 and the teeth 32 a of the second comb-teeth electrode 32 . The teeth 31a and 32a of the comb electrodes 31 and 32 generate resonance due to the high frequency, and the tips of the teeth 31a and 32a become the antinodes of the standing waves due to the high frequency. In the radiating antenna 22, the abdomens of the standing wave at the plurality of teeth 31a of the first comb-teeth electrode 31 are arranged in a row in the first direction, and the abdomens of the standing wave at the plurality of teeth 32a of the second comb-teeth electrode 32 are aligned. are aligned in the first direction.

Also, a relatively strong electric field coupling occurs between the tooth portions 31a and 32a adjacent to each other in the first direction. As a result, a strong electric field region is formed in the area facing the radiation antenna 22 so as to include the transport path of the substrate 11 and the object to be heated 20 . The object to be heated 20 passing through the strong electric field region is heated by the high frequency due to dielectric components, conductive components, and the like. As a result, the object to be heated 20 undergoes a temperature rise and undergoes desired physical/chemical changes (polymerization, annealing, drying, hardening, etc.). In addition, in the base material 11 , a plurality of objects to be heated 20 are arranged at intervals in the conveying direction of the base material 11 . A plurality of objects 20 to be heated are conveyed at intervals so as to sequentially pass through the strong electric field region.

In this embodiment, high-frequency resonance occurs in the tooth portions 31a and 32a of the radiation antenna 22, and the electric field strength in the strong electric field region becomes relatively high. Therefore, the power supplied to the oscillator 21 can be suppressed as compared with the case where resonance does not occur. In addition, in the present embodiment, since the continuous gap 70 is formed in the shielding portion 60, it is possible to suppress high-frequency leakage to the outside while allowing the base material 11 to pass through. Further, by providing the shield member 46, high frequency leakage through the entrance of the blowing passage 45 can be suppressed. In addition, since the air blower 35 is provided, when the object 20 to be heated is dried by heating, the organic solvent and moisture evaporated from the object 20 to be heated can be discharged to the outside of the shielding part 60. can be dried efficiently.

[Configuration and operation of control device]
Controller 75 is configured to control the oscillation frequency of oscillator 21 . The controller 75 includes a directional coupler 76, a phase difference information generator 77, and a controller 78, as shown in FIG. Before describing the control device 75, the configuration of the oscillator 21 will be described below. The directional coupler 76 is provided in the transmission line 16 extending from the oscillator 21 to the radiating antenna 22 and corresponds to an information extractor for extracting reflected wave information.

The oscillator 21 includes a voltage variable oscillator (VCO) 21a whose oscillation frequency is changed by a control voltage, an amplifier 21b provided after the voltage variable oscillator 21a, and provided between the voltage variable oscillator 21a and the DC power supply 15. and a voltage adjustment circuit 21c. The voltage adjustment circuit 21c is configured to be able to change the control voltage applied to the voltage variable oscillator 21a by turning ON/OFF the switches SW1 and SW2.

For example, the voltage adjustment circuit 21c includes an inductor L and a capacitor C in addition to the first switch SW1 and the second switch SW2. In the voltage adjustment circuit 21c, the first terminal of the inductor L is connected to the positive side of the DC power supply 15, the first terminal of the capacitor C is connected to the negative side of the DC power supply 15, and the second terminal of the inductor L and the second terminal of the capacitor C are connected. are connected to each other and connected to the voltage variable oscillator 21a. The first switch SW1 is connected between the first terminal of the inductor L and the positive side of the DC power supply 15 . The second switch SW2 is connected between a wiring connecting the first terminal of the inductor L and the positive side of the DC power supply 15 and a wiring connecting the first terminal of the capacitor C and the negative side of the DC power supply 15. .

In the first state in which only the first switch SW1 of the first switch SW1 and the second switch SW2 is set to ON, the capacitor C is charged. In the first state, the control voltage gradually increases, and the oscillation frequency gradually increases along with the increase. Further, in the second state in which only the second switch SW2 of the first switch SW1 and the second switch SW2 is set to ON, the capacitor C is discharged. In the second state, the control voltage gradually decreases, and the oscillation frequency gradually decreases as the control voltage decreases. In the third state in which both the first switch SW1 and the second switch SW2 are turned off, the potential difference between the first terminal and the second terminal of the capacitor C and the control voltage are constant. In the third state, the oscillation frequency of voltage variable oscillator 21a does not change. Note that the configuration of the voltage adjustment circuit 21c is not limited to this embodiment.

Each element of the control device 75 will be described. A directional coupler 76 is connected to the transmission line 16 . The directional coupler 76 receives an incident wave signal representing the waveform of the high frequency (incident wave) directed from the transmission line 16 toward the radiation antenna 22 and a reflected wave signal representing the waveform of the high frequency (reflected wave) returning from the radiation antenna 22. and are configured to extract, respectively. The directional coupler 76 has a first output terminal and a second output terminal connected to the phase difference information generating section 77, outputs the incident wave signal from the first output terminal to the phase difference information generating section 77, and outputs the incident wave signal to the phase difference information generating section 77. The incident wave signal is output to the phase difference information generating section 77 from the second output terminal.

A line for transmitting the incident wave signal from the directional coupler 76 to the phase difference information generating unit 77 is provided with a phase correction unit 99 for correcting the phase shift between the incident wave signal and the reflected wave signal. A delay line (cable) is provided to delay the signal. A delay element for delaying a signal by a predetermined phase may be provided instead of the delay line.

［式４］

式３において、ＮＰＡは入射波信号（Ａｓｉｎ（ωｔ＋θ１））を表し、ＮＰＢは反射波信号（Ｂｓｉｎ（ωｔ＋θ２））を表す。θ１は入射波信号ＮＰＡの位相、θ２は反射波信号ＮＰＢの位相を表す。 The phase difference information generating section 77 is a device that generates a phase difference signal representing the phase difference (θ1−θ2) between the incident wave and the reflected wave by arithmetic processing for calculating the incident wave signal and the reflected wave signal. The phase difference signal corresponds to phase difference information. A phase detector or an amplitude/phase detector can be used for the phase difference information generator 77 . For example, after performing the multiplication shown in Equation 3, the phase difference information generating unit 77 generates a component (double harmonic component (cos(2ωt+θ1+θ2))) containing an angular frequency ω corresponding to the oscillation frequency f and a time function t. A phase difference signal PDS shown in Equation 4 is generated and output by performing filter processing for removal. According to the filtering process, the DC phase difference signal PDS remains. Generation and output of the phase difference signal PDS in the phase difference information generator 77 are performed continuously.
[Formula 3]

[Formula 4]

In Equation 3, NPA represents the incident wave signal (Asin(ωt+θ1)) and NPB represents the reflected wave signal (Bsin(ωt+θ2)). θ1 represents the phase of the incident wave signal NPA, and θ2 represents the phase of the reflected wave signal NPB.

6 includes a first log amp 81 to which an incident wave signal is input, a second log amp 82 to which a reflected wave signal is input, and an incident wave signal output from the first log amp 81 . A multiplier 83 that adds the wave signal and the reflected wave signal output from the second log amp 82 (that is, a multiplier that outputs the result of multiplying the signal before conversion by adding the logarithmically converted signal); A filter section 84 for performing the filtering process described above on the output signal of the multiplier 83 is provided. The multiplier 83 adds the logarithmically transformed incident wave signal and the logarithmically transformed reflected wave signal (that is, multiplies the incident wave signal and the reflected wave signal). The filter section 84 removes the double frequency component from the multiplication result. A low-pass filter can be used for the filter unit 84 . Note that the filter unit 84 may be a digital filter, and in this case, it is provided after the AD converter.

Based on the phase difference signal, the control unit 78 performs a direction detection operation for detecting the adjustment direction of the oscillation frequency in which the difference between the resonance frequency of the radiation antenna 22 and the oscillation frequency of the oscillator 21 becomes small, and the detection result of the direction detection operation. A control process is repeatedly performed to perform a frequency adjustment operation for adjusting the oscillation frequency based on the frequency. The control unit 78 includes a detection unit 78a that performs a direction detection operation, and a first command unit 78b and a second command unit 78c that perform frequency adjustment operations.

The control unit 78 can be configured by, for example, a microcomputer. In this case, a control program is installed in the control unit 78 . The control unit 78 has a detection unit 78a, a first command unit 78b, and a second command unit 78c as functional blocks implemented by the CPU executing and interpreting the control program. Note that the control unit 78 may be configured by an analog circuit.

The control processing of the control unit 78 will be described with reference to the flowchart of FIG. In the flowchart, steps ST1 to ST3 correspond to the direction detection operation, and steps ST4 to ST6 correspond to the frequency adjustment operation. Further, the control unit 78 repeats the control process of the flowchart at a predetermined control cycle S. The control period S is set to 50 ms or less.

A phase difference signal is continuously input to the detector 78a via an AD converter. In step ST1, the detection unit 78a detects the voltage value of the phase difference signal as the phase difference voltage V at a sampling period equal to the control period S, for example, by performing normalization processing or the like on the digitally converted phase difference signal. do. In step ST2, the detection unit 78a performs a first comparison operation for comparing a threshold range (-Vc to Vc) including a threshold (voltage = 0) with the phase difference voltage V, where the phase difference voltage V is the lower limit of the threshold range. It is determined whether or not it is below the value -Vc. The threshold range corresponds to reference information in a state where the phase of the incident wave and the phase of the reflected wave are equal.

Here, in FIG. 8, a first graph G1 representing changes in the phase difference voltage V with respect to frequency and a second graph G2 representing changes in reflected wave intensity with respect to frequency are superimposed. In the first graph G1, the phase difference voltage V is less than zero in the lower frequency range fb where the oscillation frequency is lower than the resonance frequency _f0 , and the phase difference voltage V is less than zero in the upper frequency range fe where the oscillation frequency is higher than the resonance frequency _f0 . The phase difference voltage V becomes zero at the frequency at which the phase difference voltage V is greater than zero and the oscillation frequency is equal to the resonance frequency _f0 (that is, the frequency at which impedance matching is achieved in the radiation antenna 22). .

When the phase difference voltage V is below the lower limit value -Vc of the threshold range in step ST2, the oscillation frequency is in the lower frequency range fb which is lower than the resonance frequency _f0 . In this case, the process proceeds to step ST4, and the first command section 78b, which has received a command from the detection section 78a, outputs an ON signal to the first switch SW1 as a frequency adjustment operation. At this time, if the second switch SW2 is ON, the detection section 78a causes the second command section 78c to switch the second switch SW2 to OFF. As a result, the voltage adjustment circuit 21c switches to the first state, and the control voltage to the voltage variable oscillator 21a gradually increases. As a result, the oscillation frequency of the oscillator 21 gradually increases and approaches the resonance frequency _f0 . After executing step ST4, the process returns to step ST1.

On the other hand, if the phase difference voltage V does not fall below the lower limit value −Vc of the threshold range in step ST2, the process proceeds to step ST3, and the detection unit 78a performs the second comparison operation so that the phase difference voltage V is the upper limit value of the threshold range. It is determined whether or not Vc is exceeded. When the phase difference voltage V exceeds the upper limit value Vc of the threshold range in step ST3, the oscillation frequency is in the upper frequency range fe, which is higher than the resonance frequency _f0 . In this case, the process proceeds to step ST5, and the second command section 78c, which has received a command from the detection section 78a, outputs an ON signal to the second switch SW2 as a frequency adjustment operation. At this time, if the first switch SW1 is ON, the detection section 78a causes the first command section 78b to switch the first switch SW1 to OFF. As a result, the voltage adjustment circuit 21c switches to the second state, and the control voltage to the voltage variable oscillator 21a gradually decreases. As a result, the oscillation frequency of the oscillator 21 gradually decreases and approaches the resonance frequency _f0 . After executing step ST5, the process returns to step ST1.

If the phase difference voltage V does not exceed the upper limit value Vc of the threshold range in step ST3, the phase difference voltage V is within the threshold range. In this case, the process proceeds to step ST6, and if the first switch SW1 is ON, the detection unit 78a causes the first command unit 78b to switch the first switch SW1 to OFF and the second switch SW2 to ON. If so, it causes the second command section 78c to turn off the second switch SW2. As a result, the voltage adjustment circuit 21c switches to the third state, and the control voltage becomes constant. As a result, the oscillation frequency of the voltage variable oscillator 21a is held at the value at that time. After executing step ST6, the process returns to step ST1.

With reference to FIG. 9, how the oscillation frequency follows the resonance frequency _f0 will be described. In addition, hereinafter, the process starting from step ST1 and returning to the first step ST1 is regarded as one unit, and is expressed as "n-th process".

Assume that the value of the oscillation frequency is f _A at the time of the first processing (see FIG. 9A). When the first process is performed in this state, the phase difference voltage becomes the value on the vertical axis of the detection point A, and it is detected that the phase difference voltage is below the lower limit value -Vc. Therefore, the voltage adjustment circuit 21c is switched to the first state (only the first switch SW1 is ON), and the oscillation frequency gradually increases and approaches the resonance frequency _f0 .

Assume that the value of the oscillation frequency is f _B at the time of the second processing (see FIG. 9B). When the second process is performed in this state, it is detected that the phase difference voltage is still below the lower limit value -Vc. The voltage adjustment circuit 21c is maintained in the first state, and the oscillation frequency further approaches the resonance frequency _f0 . Assume that the value of the oscillation frequency is f _C at the time of the third processing (see FIG. 9(c)). When the third process is performed in this state, it is detected that the phase difference voltage is between the upper limit value Vc and the lower limit value −Vc. In this case, the voltage adjustment circuit 21c is switched to the third state (both switches SW1 and SW2 are OFF), and the oscillation frequency is held.

From this state, as shown in FIG. 9(d), it is assumed that the resonance frequency _f0 becomes smaller due to the influence of the object 20 to be heated (graphs G1 and G2 move to the left). The value of the oscillation frequency remains _fC . When the fourth process is performed in this state, the phase difference voltage becomes the value on the vertical axis of the detection point C', and it is detected that the phase difference voltage exceeds the upper limit value Vc. Therefore, the voltage adjustment circuit 21c is switched to the second state (only the second switch SW2 is ON), and the oscillation frequency gradually decreases and approaches the resonance frequency _f0 .

Assume that the value of the oscillation frequency is f _D at the time of the fifth processing (see FIG. 9(e)). When the fifth process is performed in this state, it is detected that the phase difference voltage continues to exceed the upper limit value Vc. The voltage adjustment circuit 21c is maintained in the second state, and the oscillation frequency further approaches the resonance frequency _f0 . Assume that the value of the oscillation frequency is f _E at the time of the sixth processing (see FIG. 9(f)). When the sixth process is performed in this state, the voltage adjustment circuit 21c is switched to the third state and the oscillation frequency is held as in the third process. Thus, in the control process, the oscillation frequency is adjusted so as to follow the resonance frequency _f0 .

[Effects of the first embodiment, etc.]
In this embodiment, phase difference information representing the phase difference between the incident wave and the reflected wave is generated by arithmetic processing using the incident wave signal and the reflected wave signal. Then, the adjustment direction of the oscillation frequency is detected based on the phase difference information and the reference information (threshold range), and the control process for controlling the oscillation frequency based on the detection result is repeatedly performed, thereby reducing the resonance frequency _f0 . the oscillation frequency follows. Here, the above arithmetic processing can be performed at high speed. That is, phase difference information can be generated at high speed. Further, since the numerical data of the reference information can be prepared in advance, the adjustment direction of the oscillation frequency can also be detected at high speed. According to this embodiment, it is possible to cause the oscillation frequency to follow the resonance frequency at high speed.

By the way, in the processing system of the present embodiment, the object to be heated 20 is heated in the transportation route while the object to be heated 20 is being transported. In this case, the resonance frequency _f0 changes successively depending on the presence or absence of the object 20 to be heated, changes in the amount of moisture in the object 20 to be heated over time, steam generated by heating, and the like. Specifically, the object to be heated 20 has a small amount and a light load, and even in an environment in which the specific resonance mode in the internal space 40 is maintained, the resonance frequency _f0 changes sequentially within the resonance mode. For example, a high frequency is applied to the object 20 to be heated, and the dielectric constant decreases as the temperature of the object 20 to be heated rises and dries, so that the resonance frequency _f0 transitions.

Here, when the resonance frequency is _f0 , the rate of high-frequency energy absorbed by the object to be heated 20 (hereinafter referred to as "high-frequency energy absorption rate") is maximized. However, when the resonance frequency _f0 changes successively, the conventional technology cannot make the oscillation frequency follow the resonance frequency _f0 at high speed, and it is difficult to maintain the high frequency energy absorption rate at a high value. In addition, high frequencies tend to leak into the open space.

On the other hand, in the present embodiment, the oscillation frequency can follow the resonance frequency _f0 at high speed. value can be maintained, and high-frequency leakage can also be suppressed.

The inventors of the present application have found that (i) when the oscillation frequency is fixed, the high-frequency energy absorption rate particularly decreases immediately after the electromagnetic wave heating device 10 is turned on, and (ii) the electromagnetic wave heating device 10 An experiment with a control cycle of 30 ms has confirmed that the high-frequency energy absorption rate is greatly improved from the time the power is turned on by performing the above-described frequency control from the time the power is turned on.

[First Modification of First Embodiment]
In this modification, the control unit 78 uses the reference information and the phase difference information to detect the deviation direction (shift direction) of the oscillation frequency with respect to the resonance frequency, and averages the detection results. , to detect the tuning direction of the oscillation frequency. Averaging processing is performed on the result of the comparison operation that compares the threshold range (−Vc to Vc) and the phase difference voltage V. FIG. The following description will focus on points that differ from the embodiment, with reference to FIG. 10 .

In this modification, when the phase difference voltage V falls below the lower limit value −Vc of the threshold range in the first comparison operation, the detection unit 78a determines that the deviation is in the negative direction and records the determination result (−X). Further, when the phase difference voltage V exceeds the upper limit value Vc of the threshold range in the second comparison operation, it is determined that the shift is in the positive direction, and the determination result (+X) is recorded. Further, when the phase difference voltage V does not exceed the upper limit value Vc of the threshold range in the second comparison operation, it is determined that there is no phase shift, and the determination result (±0) is recorded.

The detection unit 78a performs an averaging process of averaging the determination results of the comparison operations arranged in time series with a predetermined number of comparison result samples n. Formula 5 is an example of a formula used for averaging the (m+n−1)-th determination result D(m+n−1) from the m-th determination result D(m). Y represents the calculated value of the averaging process.
[Formula 5]

When the calculated value Y of the averaging process is negative, the detection section 78a causes the first command section 78b to output an ON signal to the first switch SW1. When the calculated value Y is positive, the detection unit 78a causes the second command unit 78c to output an ON signal to the second switch SW2. In FIG. 10, a graph G3 representing a time-series change in the phase difference voltage V, a graph G4 representing a time-series change in the determination result of the comparison operation, and a graph G5 representing a time-series change in the calculated value Y are superimposed. is described. According to this modified example, noise can be removed by the averaging process, so that the tracking accuracy of the oscillation frequency is improved. Therefore, the high-frequency energy absorption rate increases, and the electric power required for heating can be reduced.

In addition, in this modified example, the comparison target of the calculated value Y of the averaging process may be the threshold range. The detection unit 78a outputs an ON signal to the first switch SW1 when the calculated value Y is below the lower limit value −Vc of the threshold range, and outputs an ON signal to the second switch SW2 when the calculated value Y exceeds the upper limit value Vc of the threshold range. Output an ON signal. In this case, compared to the case where the calculated value Y is compared with the threshold value (V=0), noise can be removed, so the power required for heating can be reduced.

Further, the control unit 78 may adjust the number of samples n of detection results used for the averaging process based on the conveying speed of the object 20 to be heated. When the conveying speed is fast, the resonance frequency _f0 fluctuates finely. Therefore, the faster the conveying speed, the smaller the number of samples n, and fine follow-up control is performed. The control cycle S may be adjusted based on the transport speed, and the control cycle S may be lengthened as the transport speed increases in order to eliminate noise.

[Second Modification of First Embodiment]
In this modification, the control unit 78 detects the oscillation frequency adjustment amount (or deviation amount) in addition to the oscillation frequency adjustment direction based on the reference information and the phase difference information. In this case, the adjustment amount of the oscillation frequency can be detected based on the magnitude of the phase difference voltage V (the difference between the phase difference information and the reference information). For example, the larger the difference between the phase difference voltage V and zero, the smaller the adjustment amount of the oscillation frequency. In this modification, the control unit 78 adjusts the oscillation frequency in the adjustment direction according to the amount of adjustment, so that the oscillation frequency can follow the resonance frequency _f0 at a higher speed.

<Second embodiment>
This embodiment differs from the first embodiment in the configuration of the control device 75 . In the following, the present embodiment will be described, focusing on points different from the first embodiment.

As shown in FIG. 11, the oscillator 21 includes a voltage variable oscillator 21a, a synthesizer 21d provided after the voltage variable oscillator 21a, a quadrature modulator 21e provided after the synthesizer 21d, and a quadrature modulator 21e. It is provided with an amplifier 21b and a voltage adjustment circuit 21c provided in the latter stage. In this embodiment, the voltage adjustment circuit 21c is composed of a DA converter.

When the high frequency fvco is input from the voltage variable oscillator 21a, the synthesizer 21d outputs a high frequency with a frequency f (f=fvco+R) obtained by adding the register value R to the high frequency fvco. The synthesizer 21d is provided with a register (not shown) for recording and updating the register value R. FIG. In this embodiment, the oscillation frequency of the oscillator 21 is the frequency of the high frequency output from the synthesizer 21d.

The quadrature modulator 21e also modulates the high frequency output from the synthesizer 21d into a first I component signal and a first Q component signal, and outputs the first I component signal and the first Q component signal to the amplifier 21b. The oscillator 21 oscillates a quadrature-modulated high frequency.

The control device 75 includes a directional coupler 76 , a first quadrature demodulator 91 , a second quadrature demodulator 92 , and a controller 78 . The first quadrature demodulator 91 and the second quadrature demodulator 92 constitute a quadrature demodulator.

The first quadrature demodulator 91 demodulates the incident wave signal into a first I component signal and a first Q component signal. The second quadrature demodulator 92 demodulates the reflected wave signal into a second I component signal and a second Q component signal. A synchronizing signal for synchronizing with the quadrature modulator 21e is input from the synthesizer 21d to each of the quadrature demodulators 91 and 92 .

Based on the demodulated incident wave signal (the first I component signal and the first Q component signal) and the demodulated reflected wave signal (the second I component signal and the second Q component signal), the control unit 78 controls the incident wave and the reflected wave. An information generation operation for generating phase difference information representing a phase difference between waves, and an adjustment direction of the oscillation frequency that reduces the difference between the resonance frequency _f0 of the radiation antenna 22 and the oscillation frequency of the oscillator 21 is detected based on the phase difference information. and a frequency adjustment operation for adjusting the oscillation frequency based on the detection result of the direction detection operation. The control unit 78 can be configured by, for example, a microcomputer. A control program is installed in the control unit 78 . The control unit 78 has a detection unit 87 and a command unit 88 as functional blocks implemented by the CPU executing and interpreting the control program.

The detection unit 87 performs an information generation operation and a direction detection operation. The detector 87 also serves as a phase information generator. The detection unit 87 calculates the phase difference (θ1−θ2) between the incident wave and the reflected wave by arithmetic processing using the first I component signal, the first Q component signal, and the second I component signal and the second Q component signal. A value PDC is calculated as the phase difference information. Then, the adjustment direction of the oscillation frequency is detected based on the phase difference calculation value PDC.

For example, the detection unit 87 calculates the incident wave information NPA and the reflected wave information NPB by performing the arithmetic processing shown in Equations 6 and 7, and then performs the calculation shown in Equation 8 (complex division (complex conjugate multiplication)). , the phase difference calculation value PDC is calculated as a value obtained by dividing the reflected wave information NPB by the incident wave information NPA.

［式７］

［式８］

In equations 6 and 7, the first I component signal is represented by Acos(ωt+θ1), the first Q component signal is represented by Aisin(ωt+θ1), the second I component signal is represented by Bcos(ωt+θ2), and the second Q component signal is represented by Acos(ωt+θ1). A component signal is represented by Bisin(ωt+θ2). Let α=ωt+θ1 and β=ωt+θ2.
[Formula 6]

[Formula 7]

[Formula 8]

The operation of the control unit 78 will be described with reference to the flowchart of FIG. In this embodiment, before the object to be heated 20 is started to be conveyed, the intensity of the reflected wave reaches a predetermined judgment level k After performing search control for searching for a lower band, frequency control is performed.

[Search control]
FIG. 12(a) is a flowchart of search control. In the search control, in step ST11, the control unit 78 sets the initial frequency fi (for example, the lower limit of the oscillation-possible band) to the oscillator 21 and causes the oscillator 21 to start high-frequency oscillation. Next, in step ST12, the controller 78 causes the oscillator 21 to sweep the frequency. The bandwidth (fi to fi+Δf) over which the frequency sweep is performed is equal to the initial value of the resist value R.

Here, during the period in which the high frequency is oscillated from the oscillator 21, the first I component signal and the first Q component signal demodulated by the first quadrature demodulator 91 and the second I component signal demodulated by the second quadrature demodulator 92 The component signal and the second Q component signal are input to the detector 87 as continuous signals. The detector 87 digitally converts each I component signal and each Q component signal.

In step ST13, the detection unit 87 calculates the phase difference calculation value PDC at a predetermined calculation cycle during the frequency sweep period by the calculations of Equations 6 to 8. The phase difference calculation value PDC represents coordinate values on the complex plane of the Smith chart shown in FIG. Step ST14 is performed after the frequency sweep is finished. In step ST14, the detection unit 87 adds the phase θ1 is equal to the phase θ2 of the reflected wave (coordinate value on the center line P passing through the center point _P0 in the Smith chart). In FIG. 13, the region above the center line P is 0 to π/2, and the region below the center line P is -π/2 to 0.

If there is no coordinate value at which the phase θ1 and the phase θ2 are equal in step ST14, there is no resonance frequency _f0 in the band in which the frequency sweep is performed. After the addition, the process returns to step ST12. The resist value R is Δf×2. In step ST12, the control unit 78 causes the oscillator 21 to sweep the frequency in the upper band (fi+Δf to fi+Δf×2) adjacent to the band in which the frequency was swept immediately before.

On the other hand, if there is a coordinate value at which the phase θ1 and the phase θ2 are equal to each other in step ST14, the resonant frequency _f0 exists in the frequency sweep band. It is determined whether or not the reflection coefficient B/A at the equal resonance frequency _f0 is below the determination level k. The determination level k is pre-stored in the control section 78 .

If the reflection coefficient B/A does not fall below the judgment level k in step ST16, the reflected wave intensity is not small at the resonance frequency _f0 in the frequency swept band. After that, the process returns to step ST12. On the other hand, when the reflection coefficient B/A is lower than the judgment level k in step _ST16 , a band in which the reflected wave intensity is small is found at the resonance frequency _f0 . After detection, search control is ended and frequency control is started.

[Frequency control]
FIG. 12(b) is a flow chart of control processing constituting frequency control. In the flowchart, step ST23 corresponds to the information generation operation, ST26 to ST27 correspond to the direction detection operation, and steps ST28 to ST29 correspond to the frequency adjustment operation.

In the frequency control, in step ST21, the power of the transport mechanism 12 is switched to ON, and transport of the object 20 to be heated is started. Next, in step ST22, the control unit 78 sets the oscillation frequency _f of the oscillator 21 to the resonance frequency f0 detected in step ST17. In step ST23, the detection unit 87 uses the first I component signal, the first Q component signal, the second I component signal, and the second Q component signal at that point in time to calculate the phase difference calculation value PDC by calculating Equations 6 to 8. calculate.

Next, in step ST24, the detection unit 87 determines whether or not the reflection coefficient B/A is below the determination level k. If the reflection coefficient B/A does not fall below the determination level k in step ST24, after adding a predetermined value Δf to the registration value R in step ST25, the process returns to step ST22. As a result, when it is no longer a band in which the intensity of the reflected wave is low due to fluctuations in the resonance frequency _f0 , it is possible to move to another band.

On the other hand, if the reflection coefficient B/A is below the determination level k in step ST24, the detection unit 87 detects the calculated coordinate value represented by the phase difference calculated value PDC and the center line P of the Smith chart in step ST26. As the first comparison operation for comparing with the reference information, it is determined whether or not the calculated coordinate value is in positive phase (that is, whether or not θ1>θ2).

If the condition θ1>θ2 is satisfied in step ST26, the calculated coordinate value (for example, position A in FIG. 13) is between 0 and π/2. In this case, the process proceeds to step ST28, and the command section 88 increases the oscillation frequency by a predetermined addition frequency p (for example, p=1 MHz) via the voltage adjustment circuit 21c. As a result, the oscillation frequency of the oscillator 21 approaches the resonance frequency _f0 . Phase calculation value A moves in the direction of the arrow. After executing step ST28, the process returns to step ST23.

On the other hand, if the condition of θ1>θ2 is not satisfied in step ST26, the process proceeds to step ST27, and the detection unit 87 performs a second comparison operation to determine whether the calculated coordinate value is between -π/2 and 0 (that is, , θ1<θ2). If the condition of θ1<θ2 is satisfied in step ST27, the calculated coordinate value (for example, position B in FIG. 13) is between -π/2 and 0. In this case, the process proceeds to step ST29, and the command section 88 decreases the oscillation frequency by a predetermined subtraction frequency q (eg, q=1 MHz) via the voltage adjustment circuit 21c. As a result, the oscillation frequency of the oscillator 21 approaches the resonance frequency _f0 . Phase calculation value B moves in the direction of the arrow. After executing step ST29, the process returns to step ST23.

If the condition θ1<θ2 is not satisfied in step ST27, the coordinate values are on the center line P. In this case, the process returns to step ST23. The oscillation frequency remains unchanged.

[Effects of the second embodiment, etc.]
In this embodiment, phase difference information representing the phase difference between the incident wave and the reflected wave is generated by digital arithmetic processing using the incident wave signal and the reflected wave signal. Then, the adjustment direction of the oscillation frequency is detected based on the phase difference information and the reference information (information on the center line P), and the control process for controlling the oscillation frequency based on the detection result is repeatedly performed to obtain the resonance frequency f The oscillation frequency follows ₀ . Here, the above arithmetic processing can be performed at high speed. Further, since the numerical data of the reference information can be prepared in advance, the adjustment direction of the oscillation frequency can also be detected at high speed. According to this embodiment, it is possible to cause the oscillation frequency to follow the resonance frequency at high speed.

[First Modification of Second Embodiment]
In this modification, as shown in FIG. 14, the quadrature demodulator includes one quadrature demodulator 91, a first period in which the incident wave signal is input from the directional coupler 76 to the quadrature demodulator 91, A selector switch SW3 is provided for switching between the second period and the second period in which the reflected wave signal is input. The switch SW3 is switched by the control unit 78 at a predetermined switching cycle. For example, the switching cycle is half or less of the phase difference information generation cycle.

In this modification, the first half of step ST23 described above is the first period when the switch SW3 is switched to the contact on the incident wave signal side. The quadrature demodulator 91 demodulates the incident wave signal into a first I component signal and a first Q component signal. In the second half of step ST23, the changeover switch SW3 is switched to the contact on the reflected wave signal side, and the second period is set. The quadrature demodulator 91 demodulates the reflected wave signal into a second I component signal and a second Q component signal. Then, the detection unit 87 calculates the phase difference calculation value PDC by the arithmetic processing of Equations 6 to 8. According to this modification, the configuration of the quadrature demodulator can be simplified.

[Second Modification of Second Embodiment]
In this modification, as shown in FIG. 15, a coupler 93 is provided to extract the incident wave signal from the transmission line 16, and an isolator 94 is provided to extract the reflected wave signal from the transmission line 16. A circulator type isolator is used for the isolator 94 .

The incident wave signal extracted by the coupler 93 is input to the controller 78 without being demodulated. Based on the incident wave signal, the controller 78 detects the intensity A of the incident wave signal amplified by the amplifier 21b. Information on the intensity A is used to calculate the above-described reflection coefficient B/A.

A reflected wave signal extracted by the isolator 94 is input to the quadrature demodulator 91 via the attenuator 95 . In this modified example, the quadrature demodulator is composed of one quadrature demodulator 91 . The quadrature demodulator 91 demodulates the reflected wave signal into a second I component signal and a second Q component signal. The second I component signal and the second Q component signal demodulated by the quadrature demodulator 91 are input to the controller 78 .

In this modification, the control unit 78 is configured to generate phase difference information using phase incident wave information (incident wave information derived from oscillation information) at the high frequency output timing of the oscillator 21 . Specifically, the control unit 78 uses the first I component information and the first Q component information of the incident wave information derived from the oscillation information and the second I component information and the second Q component information demodulated by the quadrature demodulator 91 to Arithmetic processing of Equations 6 to 8 is performed to calculate the phase difference calculation value PDC. In this arithmetic processing, the control unit 78 corrects the phase shift between the incident wave information and the reflected wave information before the arithmetic processing. This correction corrects the phase shift between the incident wave output from the oscillator 21 and the reflected wave signal extracted by the isolator 94 .

[Third Modification of Second Embodiment]
In this modification, the control unit 78 performs the above-described frequency control during the initial heating period in which the object to be heated 20 first passes through the strong electric field region, and the adjustment history of the oscillation frequency as the control history information of the frequency control. (Adjustment direction in each control process) is sequentially recorded in the memory, and frequency control is performed using the control history information recorded in the memory during the period in which the heated object 20 passing through the strong electric field region is heated after the recording.

As the control history information, the history of the resonance frequency _f0 calculated from the phase difference information and the oscillation frequency, or the history of the oscillation frequency of the oscillator 21 (voltage information representing the frequency, etc.) may be recorded. In frequency control using the control history information, the oscillation frequency of the history information may be applied as it is. The corrected frequency may be given to the oscillator 21 .

In addition, an object detection sensor (for example, a light receiving element, an imaging element) that detects the presence or absence of the object to be heated 20 is provided in the internal space 40, and the heating start time of the object to be heated 20 (for example, at a position on the upstream side of the radiation antenna 22) The control history information may be recorded together with the time elapsed information from the arrival time of the object 20 to be heated. In frequency control using control history information, the object detection sensor detects the next heating start timing of the object to be heated 20, and frequency control is started from the detection timing.

[Fourth Modification of Second Embodiment]
In this modification, in order to correct the phase shift due to the stray reactance that occurs in the radiation antenna 22, in the setting stage of the electromagnetic wave heating device 10, the frequency at which the reflection coefficient (reflected wave power) exhibits the minimum value and the phase angle of 0° The high frequency oscillated from the oscillator 21 may be phase-modulated by the correction phase angle for correcting the difference from the frequency. As a result, the electromagnetic wave heating device 10 can be shipped in a state in which the minimum value of the resonance impedance in the reflected wave signal demodulated by the demodulator is matched with the phase angle of 0°.

[Fifth Modification of Second Embodiment]
In this modification, each object to be heated 20 is ink printed on the base material 11, and the control unit 78, for example, uses the measurement value of a light receiving sensor using a light receiving element to measure the temperature of each object to be heated 20 Detect the amount of ink. The amount of ink can be detected, for example, by an integrated value (integrated value of light amount) of the measurement values of the light receiving sensor during the passage of the object 20 to be heated.

The control unit 78 also controls the output of the oscillator 21 based on the detected value VI of the ink amount. Here, by using the phase difference information, it is possible to estimate the high-frequency energy amount P absorbed by the object 20 to be heated per unit time. The control unit 78 estimates the high-frequency energy amount Pt absorbed by the object 20 to be heated by integrating the phase difference information based on the elapsed time from the start of heating the object 20 to be heated. Then, the output of the oscillator 21 is increased or decreased by comparing the detected value VI of the ink amount and the amount of high-frequency energy Pt.

For example, the output of the oscillator 21 can be stopped at the timing when the calculated value T of Equation 9 exceeds a predetermined dryness threshold. It is also possible to moderate the output of the oscillator 21 so that the value T is the drying threshold. Note that K in Equation 9 is a drying coefficient set according to the object 20 to be heated.
[Formula 9]
Equation 9: T = (Pt x K/VI)

Note that the measured value of a humidity sensor that detects the humidity of the air in the internal space 40 or the air discharged from the internal space 40 may be used to control the output of the oscillator 21 . When the humidity measured by the humidity sensor is higher than the predetermined value, the controller 78 determines that the object to be heated 20 is drying early, reduces the output of the oscillator 21, and reduces the humidity measured by the humidity sensor to the predetermined value. If it is lower than the value, it is determined that drying of the object 20 to be heated is delayed, and the output of the oscillator 21 is increased.

<Third Embodiment>
This embodiment is an electromagnetic wave heating device 10 that heats and defrosts an object to be heated 20 such as food using electromagnetic waves such as high frequency waves. As shown in FIG. 16, the electromagnetic wave heating apparatus 10 includes a box-shaped member 101 forming a thawing chamber 100, an oscillator 21 that oscillates high frequencies, and a high frequency wave for heating the object 20 in the thawing chamber 100. and a control device 75 for controlling the oscillator 21 . The box-shaped member 101 is provided with an air inlet, an air outlet, and a fan for sending air from the inlet to the outlet. The thawing chamber 100 is provided with a mounting table 102 on which an object to be heated (object to be thawed) 20 is placed. The radiation antenna 22 may have a resonance structure that causes resonance due to high frequencies in the frequency band transmitted from the oscillator 21, and the same antenna as in the first embodiment can be used. Moreover, although the control device 75 of the first embodiment is used in this embodiment, the control device 75 of the second embodiment may be used.

Here, in the thawing of the object 20 to be heated, the frequency at which the high frequency is likely to be absorbed differs greatly depending on the solid phase or the liquid phase. Therefore, the resonance frequency _f0 changes successively with the phase change of the object 20 to be heated. Therefore, by performing frequency control by the control device 75 so that the oscillation frequency follows the resonance frequency _f0 at high speed, the object 20 to be heated can be efficiently heated and thawed.

Further, when the electromagnetic wave heating device 10 is used as a thawing device, the resonance mode may change with the phase change of the object 20 to be heated. different. Therefore, the control device 75 selects a plurality of resonance modes that transition according to the phase change of the object 20 from the start to the end of thawing for each condition of the object 20 to be heated, such as the type and weight of the object 20 to be heated. For each, the time-series change in the resonance frequency _f0 may be recorded in advance as a pattern of the resonance frequency _f0 , and the recorded pattern may be used for frequency control. For example, the control cycle S is determined in advance for each resonance mode, and the control device 75 selects one of the plurality of resonance patterns recorded in advance based on the change in the heating time of the object to be heated 20 and the change in the resonance frequency _f0 . It is also possible to detect which resonance pattern it is, and perform frequency control at a control cycle S corresponding to the detected resonance pattern. Further, the oscillation output of the oscillator 21 is determined in advance for each resonance mode, and the control device 75 controls a plurality of previously recorded resonance patterns based on the transition of the heating time of the object to be heated 20 and the change in the resonance frequency _f0 . The oscillator 21 may be controlled to produce an oscillation output corresponding to the detected resonance pattern by detecting which resonance pattern it is.

[Other Modifications]
In the above-described embodiment, the control unit 78 estimates the degree of heating progress of the object 20 to be heated with respect to the target state of heating the object 20, and based on the estimation result, the width of the threshold range (-Vc to Vc) adjust the In this case, the degree of progress of heating of the object to be heated 20 is an estimated value using the integrated value of the measured values of the humidity sensor, the amount of high-frequency energy Pt absorbed by the object to be heated 20, the detected amount of ink VI, and the like. can be calculated as The heating target state of the object 20 to be heated can be prepared in advance as a threshold value. Further, when the estimated value of the degree of progress of heating of the object 20 to be heated is small, it may be determined that the band is not a band in which the intensity of the reflected wave is low, and the band may be moved to another band.

In the above-described embodiment, when the object to be heated 20 is ink printed by a printing device, the control unit 78 adjusts the control parameters of the control process using information on the printed pattern of the object to be heated 20. good too. For example, the control period S, the width of the threshold range (-Vc to Vc), or the number of samples n for averaging processing can be increased or decreased according to the resolution of the print pattern. When the resolution is high, the resonance frequency _f0 may fluctuate minutely. Therefore, the higher the resolution, the shorter the control cycle S, the narrower the width of the threshold range, and the smaller the number of samples n.

In the above-described embodiment, the teeth 31a and 32a of the comb electrodes 31 and 32 are provided obliquely with respect to the base lines 31b and 32b. 32b may be provided perpendicularly.

INDUSTRIAL APPLICABILITY The present invention is applicable to an electromagnetic wave heating device or the like used for heating an object to be heated.

REFERENCE SIGNS LIST 10 electromagnetic wave heating device 16 transmission line 20 object to be heated 21 oscillator 22 radiation antenna 76 directional coupler (signal extractor)
77 phase difference information generator 78 controller

Claims (12)

an oscillator that outputs electromagnetic waves;
a radiating antenna having a resonance structure that causes resonance due to electromagnetic waves in a frequency band transmitted from the oscillator;
An electromagnetic wave heating device that heats the object to be heated in a strong electric field region of electromagnetic waves formed by the resonance structure,
a signal extraction unit provided on a transmission line extending from the oscillator to the radiation antenna for extracting reflected wave information representing a waveform of a reflected wave returning from the radiation antenna;
Phase difference information representing a phase difference between the incident wave and the reflected wave is generated by arithmetic processing using the incident wave information representing the waveform of the incident wave transmitted from the oscillator to the radiation antenna and the reflected wave information. a phase difference information generator;
The oscillation in which the difference between the resonance frequency of the radiating antenna and the oscillation frequency of the oscillator is reduced based on the reference information of a state in which the phase of the incident wave and the phase of the reflected wave are equal and the phase difference information. an electromagnetic wave heating apparatus, further comprising a control unit that detects a frequency adjustment direction and repeatedly performs a control process for controlling the oscillation frequency based on the detected adjustment direction. The control unit uses the reference information and the phase difference information to detect the direction of deviation of the oscillation frequency from the resonance frequency, and adjusts the oscillation frequency by averaging the detection results. The electromagnetic wave heating device according to claim 1, which detects direction. The object to be heated is conveyed so as to pass through the strong electric field region,
3. The electromagnetic wave heating device according to claim 2, wherein said control unit adjusts the number of samples of detection results used in said averaging process based on the conveying speed of said object to be heated. The oscillator outputs a quadrature-modulated electromagnetic wave to the radiation antenna,
further comprising an orthogonal demodulation unit that orthogonally demodulates the reflected wave information,
generating the phase difference information by arithmetic processing using first I component information and first Q component information forming the incident wave information and second I component information and second Q component information forming the reflected wave information; Item 4. The electromagnetic wave heating device according to any one of Items 1 to 3. The signal extraction unit extracts the incident wave information from the transmission line,
The quadrature demodulator,
one quadrature demodulator;
a changeover switch for switching between a first period in which the incident wave information is input from the signal extraction unit to the quadrature demodulator and a second period in which the reflected wave information is input;
5. The electromagnetic wave heating device according to claim 4, wherein said changeover switch switches between said first period and said second period at a period shorter than a period of generation of said phase difference information. The signal extraction unit extracts the incident wave information from the transmission line,
A line that transmits the incident wave information from the signal extraction unit to the phase difference information generation unit is provided with a delay line or a delay element that corrects a phase shift between the incident wave information and the reflected wave information. The electromagnetic wave heating device according to any one of claims 1 to 5. The control unit is configured to generate the phase difference information using the incident wave information of the phase at the output timing of the electromagnetic wave from the oscillator, and performs the 5. The electromagnetic wave heating device according to any one of claims 1 to 4, wherein a phase shift with reflected wave information is corrected. 8. The controller according to any one of claims 1 to 7, wherein the controller estimates the amount of electromagnetic wave energy absorbed by the object to be heated based on the phase difference information, and controls the output of the oscillator based on the estimated result. 1. An electromagnetic wave heating device according to one. The reference information is a threshold range with a predetermined width,
9. The controller according to any one of claims 1 to 8, wherein the control unit estimates a degree of progress of heating of the object to be heated with respect to a heating target state of the object, and adjusts the width of the threshold range based on the estimated result. 1. An electromagnetic wave heating device according to one. A plurality of objects to be heated are conveyed at intervals so as to pass through the strong electric field region in order,
The control unit performs frequency control to repeat the control process during a period in which one object to be heated passes through the strong electric field region, records control history information of the frequency control, and after the recording, controls the strong electric field region. The electromagnetic wave heating apparatus according to any one of claims 1 to 9, wherein said control history information is used to perform said frequency control during a period of heating a passing object to be heated. A plurality of objects to be heated are conveyed at intervals so as to pass through the strong electric field region in order,
The object to be heated is ink printed by a printing device,
The electromagnetic wave heating device according to any one of claims 1 to 10, wherein the control unit uses information on the print pattern of the object to be heated for adjusting the control parameters of the control process. The internal space in which the radiation antenna is arranged is shielded from the outside, and an introduction portion and an extraction portion for a conveyed object including the object to be heated are formed, and in the internal space, the object to be heated is a region facing the radiation antenna. The electromagnetic wave heating device according to any one of claims 1 to 11, further comprising a shielding portion for conveying the conveyed object from the introduction portion toward the outlet portion so as to pass through.

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