JP7380221B2 - microwave processing equipment - Google Patents

Description

The present disclosure relates to microwave processing devices.

A microwave oven, which is a typical example of microwave processing equipment, supplies microwaves emitted by a magnetron into a processing chamber surrounded by metal walls, and dielectrically heats food or other objects placed inside the processing chamber. .

Microwaves are repeatedly reflected on the walls of the processing chamber. The phase of the reflected wave reflected by the metal wall surface changes by 180 degrees with respect to the incident wave on the metal wall surface. When a line perpendicular to the metal wall surface is taken as a reference line, the angle of incidence, which is the angle between the reference line and the incident wave, is the same as the angle of reflection, which is the angle between the reflected wave and the reference line.

The size of the processing chamber is usually much larger than the microwave wavelength (about 120 mm). Therefore, a standing wave is generated in the processing chamber due to the behavior of the incident wave and the reflected wave generated on the metal wall surface. A standing wave has antinodes that always appear in places where the electric field is strong and nodes that always appear in places where the electric field is weak.

When an object to be heated is placed at a place where an antinode of a standing wave appears, the object to be heated is heated strongly, and when an object to be heated is placed at a place where a node of a standing wave appears, the object to be heated is heated. It doesn't get heated much. This is the main cause of uneven heating in microwave ovens.

Methods for suppressing uneven heating due to such standing waves and promoting uniform heating include a turntable method in which the table is rotated to rotate the object to be heated, and a rotation method in which the antenna that emits microwaves is rotated. There is an antenna method.

There is also a technique that actively attempts to utilize local heating, which is the opposite of uniform heating (see, for example, Non-Patent Document 1). The apparatus described in Non-Patent Document 1 includes a plurality of microwave generators made of GaN semiconductor elements, and supplies the output of the microwave generators to a processing chamber from various locations. By providing a phase difference between the two supplied microwaves, the microwaves can be concentrated on the object to be heated to achieve local heating.

New Energy and Industrial Technology Development Organization and others “Development of industrial microwave heating device using GaN amplifier module as heating source” January 25, 2016

However, in the conventional microwave processing apparatus described above, it is necessary to supply microwaves to the processing chamber from a plurality of locations, which makes the apparatus complicated and large.

When heating multiple objects at the same time, even if you try to concentrate the microwaves on one object, that object will not absorb all the microwaves. The microwaves that are not absorbed by the object to be heated are incident on the other object to be heated. For this reason, it is difficult to locally heat multiple objects to be heated as desired.

An object of the present disclosure is to provide a microwave processing apparatus that can heat each of a plurality of objects to be heated as desired by controlling the standing wave distribution in a processing chamber.

A microwave processing apparatus according to an embodiment of the present disclosure includes a processing chamber that accommodates an object to be heated, a microwave supply section that supplies microwaves to the processing chamber, and a resonant section that has a resonant frequency in a microwave frequency band. Be prepared. The resonator has a plurality of patch resonators arranged so that at least three patch resonators are lined up along the direction of a plane of polarization generated on a metal wall surface constituting the processing chamber.

The microwave processing apparatus of this embodiment can control the standing wave distribution in the processing chamber, that is, the microwave energy distribution. As a result, the microwave processing apparatus of this embodiment can adjust the microwave energy absorbed by each of the objects to be heated, for example, when simultaneously heating a plurality of objects to be heated.

FIG. 1 is a perspective view showing the configuration of a microwave processing apparatus according to Embodiment 1 of the present disclosure. FIG. 2 is a plan view showing the configuration of the resonator in the first embodiment. FIG. 3A is a diagram showing the frequency characteristics of the reflection phase generated by the resonator. FIG. 3B is a diagram showing the frequency characteristics of the reflection phase generated by the resonant section. FIG. 4A is a perspective view of a waveguide for explaining the electric field generated in the waveguide. FIG. 4B is a cross-sectional view of the waveguide for explaining the electric field generated in the waveguide. FIG. 4C is a perspective view of the waveguide for explaining the electric field radiated from the waveguide opening. FIG. 5 is a diagram showing the characteristics of the electric field in the processing chamber and the current vector on the patch surface. FIG. 6A is a diagram for explaining the reason for arranging three rectangular patch resonators. FIG. 6B is a diagram for explaining the reason for arranging three rectangular patch resonators. FIG. 6C is a diagram for explaining the reason for arranging three rectangular patch resonators. FIG. 7 is a sectional view of the microwave processing apparatus of the first embodiment in a state where two objects to be heated are accommodated. FIG. 8A is a diagram showing the electric field distribution inside the processing chamber when no resonator is provided. FIG. 8B is a diagram showing the electric field distribution inside the processing chamber when a resonator is provided. FIG. 9 is a plan view showing the configuration of a resonance section according to Embodiment 2 of the present disclosure. FIG. 10A is a diagram illustrating an example of the arrangement of a resonant section and a power feeding section on a metal wall surface of a processing chamber. FIG. 10B is a diagram illustrating another example of the arrangement of the resonance section and the power supply section on the metal wall surface of the processing chamber. FIG. 11 is a plan view showing the configuration of a resonance section according to Embodiment 3 of the present disclosure. FIG. 12A is a cross-sectional view showing the configuration of a microwave processing apparatus according to Embodiment 3. FIG. 12B is a cross-sectional view taken along line 12B-12B in FIG. 12A. FIG. 13A is a longitudinal cross-sectional view showing another configuration of the microwave processing apparatus according to the third embodiment. FIG. 13B is a cross-sectional view taken along line 13B-13B in FIG. 13A. FIG. 14 is a perspective view showing the configuration of a microwave processing apparatus according to Embodiment 4 of the present disclosure. FIG. 15 is a diagram showing the characteristics of the resonant section shown in FIG. 14. FIG. 16 is a cross-sectional view showing the configuration of a microwave processing device according to Embodiment 5 of the present disclosure.

A microwave processing apparatus according to a first aspect of the present disclosure includes a processing chamber that accommodates an object to be heated, a microwave supply section that supplies microwaves to the processing chamber, and a resonant section that has a resonant frequency in a microwave frequency band. Equipped with. The resonator has a plurality of patch resonators arranged so that at least three patch resonators are lined up along the direction of a plane of polarization generated on a metal wall surface constituting the processing chamber.

In the microwave processing device according to the second aspect of the present disclosure, in addition to the first aspect, the plurality of patch resonators are arranged such that at least three patch resonators are lined up in each of the vertical and horizontal directions. be done.

In the microwave processing device of the third aspect of the present disclosure, in addition to the second aspect, the plurality of patch resonators includes at least five square patch resonators arranged in a cross shape.

In the microwave processing device according to the fourth aspect of the present disclosure, in addition to the first aspect, the plurality of patch resonators include at least three patch resonators in each of the vertical direction, the horizontal direction, and the diagonal direction. are arranged radially.

In the microwave processing device of the fifth aspect of the present disclosure, in addition to the fourth aspect, the patch resonator is a circular patch resonator.

In the microwave processing device according to the sixth aspect of the present disclosure, the microwave supply section includes a microwave generation section and a control section that controls an oscillation frequency of the microwave generation section. The resonant section includes a plurality of resonant sections having different resonant frequencies. The control section switches the resonant section that resonates among the plurality of resonant sections by controlling the oscillation frequency.

In the microwave processing device according to the seventh aspect of the present disclosure, in addition to the sixth aspect, the resonator has a plurality of resonators. Each of the plurality of resonance parts is provided in each of the plurality of divided regions on one metal wall surface that constitutes the processing chamber. The plurality of resonance parts have mutually different resonance frequencies.

In the microwave processing device according to the eighth aspect of the present disclosure, in addition to the sixth aspect, each of the plurality of resonant parts has a resonant frequency according to the order of arrangement of the plurality of resonant parts.

In the microwave processing device according to the ninth aspect of the present disclosure, in addition to the eighth aspect, each of the plurality of resonant parts has a conductor with a length corresponding to the order of arrangement of the plurality of resonant parts.

Hereinafter, preferred embodiments of the microwave processing apparatus of the present disclosure will be described with reference to the accompanying drawings. The microwave processing apparatus of this embodiment is a microwave oven. However, the microwave processing apparatus of the present disclosure is not limited to a microwave oven, but includes a heat processing apparatus using dielectric heating, a chemical reaction processing apparatus, a semiconductor manufacturing apparatus, and the like.

(Embodiment 1)
Embodiment 1 of the present disclosure will be described with reference to FIGS. 1 to 8B. FIG. 1 is a perspective view of a microwave processing apparatus 100 according to the present embodiment.

As shown in FIG. 1, the microwave processing apparatus 100 includes a processing chamber 101 surrounded by a metal wall surface and a microwave supply section 160 that supplies microwaves to the processing chamber 101. Microwave supply section 160 includes a waveguide 102 , a power supply section 103 , a microwave generation section 104 , and a control section 105 .

The waveguide 102 has a rectangular cross section and transmits microwaves in TE10 mode. The power feeding section 103 is a waveguide opening formed at a connecting portion between the waveguide 102 and the processing chamber 101 . The center of the waveguide opening is located at the intersection of the center line L1 in the left-right direction and the center line L2 in the front-back direction of the processing chamber 101 in FIG. The waveguide opening has a rectangular shape with two sides parallel to the center lines L1 and L2.

The control unit 105 receives information regarding the heat treatment, and controls the microwave generation unit 104 to generate power with an output and frequency according to the information.

In the processing chamber 101 , a resonator 106 is arranged on a ceiling surface facing the power supply section 103 . FIG. 2 is a plan view showing the configuration of the resonator 106. As shown in FIG. 2, the resonator 106 includes three square patch resonators 106a arranged in a 3×1 matrix.

Square patch resonator 106a has a dielectric 106b and a square conductor 106c. The square patch resonator 106a has a resonant frequency between 2.4 GHz and 2.5 GHz, which is the frequency band of microwaves generated from the microwave generator 104.

FIGS. 3A and 3B are diagrams showing frequency characteristics of a reflected phase generated by a square patch resonator. The vertical axis in FIG. 3A represents the reflection phase, and the vertical axis in FIG. 3B represents the absolute value of the reflection phase.

As shown in FIG. 3A, the phase of the reflection coefficient when viewed from the side of the rectangular conductor 106c of the rectangular patch resonator 106a (hereinafter referred to as reflection phase) is approximately +180 in the frequency band of 2.4 GHz to 2.5 GHz. degree to almost -180 degrees. In the characteristics shown in FIG. 3A, the resonant frequency of the square patch resonator 106a is set to 2.45 GHz.

FIG. 3B shows the vertical axis of FIG. 3A as an absolute value. As shown in FIG. 3B, the reflection phase is 180 degrees at most frequencies, but the reflection phase drops to 0 degrees near 2.45 GHz. When the length of the rectangular conductor 106c is set to about half the wavelength of the current flowing through the rectangular conductor 106c, resonance occurs.

For example, the wavelength of a 2.45 GHz microwave used in a typical microwave oven is approximately 120 mm in air with a dielectric constant of 1. For this reason, when the dielectric material 106b is, for example, foamed polystyrene having a dielectric constant close to 1, the length of the rectangular conductor 106c may be set to about 60 mm. Even if the length of the rectangular conductor 106c is, for example, 53 mm, resonance occurs.

If a general-purpose substrate material or resin material is selected for the dielectric 106b, the dielectric constant will be larger than 1 (about 2 to 5), and the higher the dielectric constant, the shorter the wavelength of the microwave tends to be. Therefore, the rectangular conductor 106c can be shortened.

Note that the surface of the resonator 106 opposite to the patch surface having the rectangular conductor 106c has the same potential as the metal wall surface of the processing chamber 101.

Here, the direction of the electric field of the microwave radiated from the power feeding unit 103 will be explained with reference to FIGS. 4A to 4C.

FIGS. 4A to 4C are diagrams for explaining the electric field generated in the waveguide. FIG. 4A is a perspective view of the waveguide. FIG. 4B is a cross-sectional view of the waveguide seen from the front of the aperture. FIG. 4C is a diagram for explaining the electric field radiated from the waveguide opening.

The microwave is transmitted by the waveguide 102 in the positive direction of the Z-axis shown in FIG. 4A, and is radiated from the power feeding section 103. The width a of the waveguide 102 is set between 1/2 of the microwave wavelength λ and the microwave wavelength λ, and the height b of the waveguide 102 is set to 1/2 of the microwave wavelength λ. When set, waveguide 102 transmits microwaves in TE10 mode.

As shown in FIG. 4B, in the TE10 mode, an electric field indicated by arrow E1 is generated in the height direction, and a magnetic field indicated by arrow H1 is generated in the width direction. The electric field is maximum at the center in the width direction within the waveguide 102 and becomes 0 at both ends within the waveguide 102. Therefore, the electric field strength distribution is shown as a broken line E2.

As shown in FIG. 4C, in the TE10 mode, an electric field is radiated from the power feeding unit 103 in the positive direction of the Z-axis. The vector component of this electric field oscillates only in the Y direction (that is, the height direction of the waveguide) like the arrow E1, and is transmitted in the Z direction over time. Therefore, the electric field is transmitted as shown by the broken line E3.

Even after being radiated from the waveguide 102, the electric field vector mainly vibrates only in the Y direction. The direction of vibration of this electric field vector is called a polarized wave, and the plane formed by the vibration direction and the transmission direction (in this case, the YZ plane) is called a polarized wave plane.

Generally, in a waveguide that transmits in the TE10 mode, the plane of polarization is a plane (YZ plane) formed by the height direction (Y direction) of the waveguide and the transmission direction (Z direction). Similarly, in FIG. 1, the microwaves radiated from the waveguide 102 to the processing chamber 101 via the power feeding section 103 are transmitted in the vibration direction (the direction of the dashed line L1 in FIG. 1) and the transmission direction (in the upward direction in FIG. 1). ) and has a polarization plane shown by a broken line E4.

Inside the processing chamber 101, the microwave is absorbed by the object to be heated inside the processing chamber 101 while being repeatedly reflected on the metal wall surface. The electric field component within the processing chamber 101 mainly occurs in a direction parallel to the plane of polarization, and hardly occurs in other directions (for example, the L2 direction component in FIG. 1).

In this embodiment, as shown in FIG. 1, the resonator 106 is arranged such that three rectangular patch resonators 106a are lined up along the plane of polarization indicated by the broken line E4.

FIG. 5 is a diagram showing the characteristics of the electric field in the processing chamber 101 and the current vector on the patch surface of the rectangular patch resonators 106a when the number and position of the rectangular patch resonators 106a are changed. FIG. 5 shows, from top to bottom, an analytical model, an electric field on the observation surface O1, an electric field on the observation surface O2, and a current vector on the patch surface of the rectangular patch resonator 106a.

The analytical model shown in the upper part of FIG. 5 has a configuration in which a waveguide 102 is connected to a processing chamber 101 in the same way as in FIG. However, this analytical model is upside down compared to the case in FIG.

The observation plane O1 is a cross section at the center of the processing chamber 101 in the front-rear direction, that is, a cross section along the dashed line L2 in FIG. 1, and is orthogonal to the plane of polarization shown by the broken line E4 in FIG. The observation plane O2 is located on the left side of the processing chamber 101, is orthogonal to the observation plane O1, and is parallel to the dashed line L1 in FIG. 1 and the plane of polarization indicated by the broken line E4.

In the second row in the middle of FIG. 5, the electric field on the observation plane O1 and the electric field on the observation plane O2 are shown as equal electric field strength diagrams. At the bottom of FIG. 5, a current vector on the patch surface of the rectangular patch resonator 106a is shown. Since the position of the square patch resonator 106a differs depending on the analytical model, the current vector on the patch surface is written at a position (back, center, front) corresponding to the arrangement of the square patch resonator 106a. The isosceles triangle in the figure indicates the direction of the current vector.

As shown in FIG. 5, four types of analysis were performed. In analysis A, square patch resonator 106a is not used. In analysis B, one rectangular patch resonator 106a is placed at the center in the front-rear direction. In analysis C, two rectangular patch resonators 106a are placed, one at the back and one at the front. In analysis D, three rectangular patch resonators 106a are arranged at the back, center, and front.

Here, a description will be given of how far to the left the observation plane O2 should be placed. First, with reference to the electric field distribution on the observation surface O1 in analysis A, a position where an antinode of a standing wave occurs on the lower surface of the processing chamber 101 of the analysis model is selected. In FIG. 5, location 111 is selected.

A plane passing through position 111 on observation plane O1 and perpendicular to observation plane O1 is set as observation plane O2. Referring to the electric field distribution on the observation plane O2 at this time, an antinode of the standing wave is generated at a position 112 where the observation plane O1 and the observation plane O2 intersect.

Next, focusing on the electric field on the observation plane O1 and the electric field on the observation plane O2, the effect of the rectangular patch resonator 106a will be considered by examining changes from analysis A in analyzes B, C, and D.

In analysis A, the electric field distributions are symmetrical on both the observation plane O1 and the observation plane O2. The electric field at position 111 is strong, the electric field at positions 113 and 114 is weak, and the electric field at position 112 is about halfway between the electric fields at positions 111 and 113.

In analysis B, the electric fields at positions 111 and 112 are weak. In particular, nodes of standing waves occur at position 112 on observation surface O2. The left-right symmetry of the electric field on the observation plane O1 is broken.

In analysis B, one rectangular patch resonator 106a is placed at the center of the observation plane O2 in the front-rear direction. That is, in analysis B, one square patch resonator 106a is placed at the antinode of the standing wave in analysis A. The results of analysis B show that the rectangular patch resonator 106a placed at the antinode of the standing wave changes the antinode of the standing wave into a node.

According to the characteristics shown in FIGS. 3A and 3B, the reflection phase of the square patch resonator 106a with respect to the frequency of 2.45 GHz is approximately 0 degrees. This means that the phase difference between the incident wave on the patch surface and the reflected wave from the patch surface is approximately 0 degrees. Considering that the phase difference between an incident wave and a reflected wave on a normal metal wall surface is 180 degrees, it can be seen that an unusual standing wave distribution was formed in the vicinity of the resonant section 106.

If the reflection phase is approximately 0 degrees, the impedance will be infinite. Therefore, the high frequency current flowing through the patch surface is suppressed, and the microwave moves away from the resonant section 106. This is the cause of the weakening of the electric field near the resonant section 106. It is estimated that this influence destroys the left-right symmetry of the observation plane O1. This effect is called the first effect.

In analysis C, as in analysis A, the electric fields at positions 111 and 112 are strong. At positions 113 and 114 where the square patch resonators 106a are located, the electric field is weak. In analysis A, standing wave nodes occur at positions 113 and 114. That is, the result of analysis C shows that the square patch resonator 106a placed at a node of a standing wave where the electric field is weak does not significantly affect the standing wave distribution.

In analysis D, the electric fields at positions 111 and 112 are weak, and a strong electric field is generated in region 115. The left-right symmetry of the observation plane O1 is broken. The results of analysis D seem to indicate that the effects of analysis B and analysis C were combined. However, in addition to this, a strong electric field is generated in the region 115. This is a unique effect of arranging the three rectangular patch resonators 106a.

As a hint for consideration, consider the current vector on the patch surface shown in the bottom row of FIG. 5 in analysis D. Comparing the three current vectors, the current vector 116 and the current vector 117 have many downward vectors in FIG. 5, while the current vector 118 has many upward vectors in FIG. With reference to this, a hypothesis regarding the effect of the arrangement of the three rectangular patch resonators 106a will be explained with reference to FIGS. 6A to 6C.

6A to 6C are diagrams for explaining the reason for arranging three rectangular patch resonators 106a. FIG. 6A is a diagram for explaining an electric field when two rectangular patch resonators are spaced apart and placed in a strong electric field. FIG. 6B is a diagram for explaining electric fields in opposite directions that occur when three rectangular patch resonators are arranged. FIG. 6C is a diagram for explaining that the strong electric field in FIG. 6B becomes a weak electric field.

The two square patch resonators 106a in FIG. 6A correspond to the two square patch resonators 106a shown in analysis B in FIG. As shown in FIG. 6A, the strong electric field 119 causes current vectors 116, 117 in the same direction, and electric fields 120, 121 in opposite directions are generated between the two square patch resonators 106a.

As shown in FIG. 6B, when another square patch resonator 106a is placed between the two square patch resonators 106a in FIG. 6A, an induced electric field 122 in the same direction as the electric field 120 and an electric field 121 An induced electric field 123 in the same direction as the current is excited.

As shown in FIG. 6C, the induced electric fields 122, 123 generate a current vector 118 in the opposite direction in the centrally located square patch resonator 106a. This creates an opposite electric field 124 that cancels out the strong electric field 119. As a result, the strong electric field can be weakened by the electric fields in opposite directions generated by the three rectangular patch resonators 106a.

In this way, in the above hypothesis, the current vector 118 generated in the square patch resonator 106a placed in the center is in the opposite direction to the current vectors 116 and 117 generated in the square patch resonators 106a placed in the back and front, respectively. It is. This result is consistent with analysis D in FIG. This effect is called the second effect. The second effect is considered to be an effect different from the first effect described above due to the arrangement of the three rectangular patch resonators 106a.

Therefore, analysis B in FIG. 5 shows only the first effect of weakening the electric field by one square patch resonator 106a placed at the antinode of the standing wave. Analysis D of FIG. 5 shows that the second effect of the three square patch resonators 106a weakening the electric field adds to the first effect.

Therefore, analysis D exhibits the effect of further weakening the electric field in the vicinity of the rectangular patch resonator 106a compared to analysis B. As a result, it is considered that the electric field at a location away from the rectangular patch resonator 106a is relatively strengthened, and a strong electric field is generated in the region 115.

The second effect is that when the square patch resonator 106a is placed at the antinode position of the standing wave, the electric field weakens, but even when the square patch resonator 106a is placed at the node position of the standing wave, the standing wave is that it does not change.

This is because when the square patch resonators 106a are placed at the nodes of the standing wave, currents flow in opposite directions to the rear and front square patch resonators 106a, and the current flows between the two square patch resonators 106a. This is because an electric field in the same direction is generated at both ends, and even if the central resonant section is placed, no induced electric field or current in the opposite direction as described above will occur.

A case in which two objects to be heated are accommodated in the processing chamber 101 will be described below. FIG. 7 is a cross-sectional view of the microwave processing apparatus 100 in a state where two objects to be heated are accommodated.

As shown in FIG. 7, the processing chamber 101 includes a mounting plate 107 arranged above the power supply section 103. The mounting plate 107 is made of a low dielectric loss material. Objects to be heated 108 and 109 are placed on the mounting plate 107 . In this state, the microwave generator 104 supplies the microwave 110.

8A and 8B are diagrams showing the electric field distribution inside the processing chamber 101 shown in FIG. 7. FIG. 8A shows the electric field distribution when the resonant part 106 is not provided, and FIG. 8B shows the electric field distribution when the resonant part 106 is provided on the right ceiling surface of the processing chamber 101.

As shown in FIG. 8A, when the resonator 106 is not provided, a substantially symmetrical electric field distribution occurs in the processing chamber 101, and a more uniform standing wave distribution appears.

On the other hand, as shown in FIG. 8B, when the resonator 106 is provided on the ceiling surface on the right side of the processing chamber 101, a weak electric field is generated on the right side of the processing chamber 101, and a strong electric field is generated on the left side of the processing chamber 101. Wave distribution appears. In this case, the electric power absorbed by the heated object 108 was approximately 2.7 times greater than that of the heated object 109.

As described above, the microwave processing apparatus 100 of the present embodiment has a processing chamber 101 surrounded by a metal wall surface, a microwave supply unit 160 that supplies microwaves to the processing chamber 101, and a microwave processing device 100 in a microwave frequency band. and a resonant section 106 having a resonant frequency. The resonator 106 includes three patch resonators (square patch resonators 106a) arranged along the direction of the plane of polarization generated on the metal wall surface constituting the processing chamber 101.

In this configuration, when microwaves having a frequency near the resonant frequency are supplied to the processing chamber 101, the microwaves are reflected at the surface of the resonant section 106 with a phase difference of approximately 0 degrees. On the other hand, on the metal wall surface of the processing chamber 101, the microwave is reflected with a phase difference of 180 degrees. This reverses the direction of the electric field. As a result, some change occurs in the standing wave distribution appearing within the processing chamber 101.

In particular, when the three rectangular patch resonators 106a are arranged along the direction of the polarization plane, it becomes clearer what kind of change occurs in the standing wave distribution appearing in the processing chamber 101.

First, when three rectangular patch resonators 106a are placed at the antinode of a standing wave, electric fields and currents in the same direction are generated in the rectangular patch resonators 106a at both ends. An electric field and current are generated in the central square patch resonator 106a in the opposite direction to those in the square patch resonators 106a at both ends. This opposite electric field acts to cancel out the strong electric field, and the antinodes of the standing waves change into nodes.

Second, when the three square patch resonators 106a are placed at the nodes of the standing wave, the standing wave does not change. That is, when the three square patch resonators 106a are arranged along the direction of the polarization plane, the place where the square patch resonators 106a are arranged is the position of the antinode of the standing wave or the position of the node. Regardless of the location, a standing wave node will always occur at that location.

This effect makes it possible to control the standing wave distribution within the processing chamber 101, that is, the microwave energy distribution. Therefore, for example, when a plurality of objects to be heated are heated simultaneously, each object to be heated can absorb desired microwave energy.

For example, by controlling so that nodes of standing waves occur where one heated object is placed, one heated object can be prevented from absorbing more microwave energy than the other heated object. can be controlled.

In this embodiment, the resonator 106 includes a flat rectangular patch resonator 106a. Thereby, the resonator 106 can be arranged without substantially impairing the effective volume inside the processing chamber 101.

The rectangular patch resonator 106a is arranged such that the patch surface faces inside the processing chamber 101 and the surface opposite to the patch surface has the same potential as the metal wall surface of the processing chamber 101. With this configuration, a sufficient internal effective volume of the processing chamber 101 can be ensured.

Three rectangular patch resonators 106a are arranged on one of the metal walls that make up the processing chamber 101. Thereby, changes in the standing wave distribution due to the resonant section 106 can be easily predicted. As a result, the object to be heated can be heated as desired.

In this embodiment, the resonator 106 is arranged on a metal wall surface of the processing chamber 101 that faces the metal wall surface of the processing chamber 101 in which the power supply section 103 is arranged. Thereby, the microwave energy distribution can be concentrated near the power feeding section 103. As a result, the object to be heated can be efficiently heated together with the microwave energy from the power supply section 103.

The microwave supply section 160 includes a microwave generation section 104 and a control section 105 that controls the oscillation frequency and output of the microwave generation section 104. Thereby, a plurality of objects to be heated can be heated simultaneously.

The resonator 106 may include four or more square patch resonators 106a. In this case, the center position of the combination differs depending on the combination of three adjacent patch resonators among the four or more patch resonators. This corresponds to the existence of multiple combinations of three patch resonators.

Therefore, even if the position of the antinode of the standing wave deviates from the expected position, for example, a combination of three patch resonators different from the expected combination of three patch resonators may be 106 may function similarly.

(Embodiment 2)
Embodiment 2 of the present disclosure will be described with reference to FIGS. 9 to 10B. Microwave processing device 100 according to this embodiment basically has the same configuration as Embodiment 1 except for resonance section 106.

FIG. 9 is a diagram showing the configuration of the resonance section 106 in this embodiment. As shown in FIG. 9, the resonator 106 has a square conductor 106c. Considering that the rectangular conductor 106c has nine regions divided into a 3×3 matrix, the dielectric 106b is provided in each of the five regions included in the center row and center column.

That is, three rectangular patch resonators 106a are arranged horizontally in the center row, and three rectangular patch resonators 106a are arranged vertically in the center column. The resonator 106 of this embodiment includes five rectangular patch resonators 106a arranged in a cross shape.

10A and 10B are diagrams illustrating an example of the arrangement of the resonant section 106 and the power feeding section 103 on one metal wall surface (for example, the ceiling surface) of the processing chamber 101.

In the configuration shown in FIG. 10A, the power feeding section 103 has a horizontally elongated waveguide opening. Therefore, the vibration direction of the electric field E1 is the vertical direction (the vertical direction in FIG. 10A), and the plane of polarization is the vertical direction.

Therefore, in this configuration, among the five rectangular patch resonators 106a arranged in a cross shape, the three rectangular patch resonators 106a arranged in the vertical direction are similar to the resonating section 106 in the first embodiment. functions.

In the configuration shown in FIG. 10B, the power feeding section 103 has a vertically elongated waveguide opening. Therefore, the vibration direction of the electric field E1 is the horizontal direction (left-right direction in FIG. 10A), and the plane of polarization is the horizontal direction.

Therefore, in this configuration, among the five rectangular patch resonators 106a arranged in a cross shape, the three rectangular patch resonators 106a arranged laterally are similar to the resonating section 106 in the first embodiment. functions. In this embodiment, the vertical direction and the horizontal direction correspond to the front-rear direction and left-right direction of the processing chamber 101 in FIG. 1, respectively.

In the case of a microwave oven, generally, as shown in FIGS. 10A and 10B, the processing chamber 101 has a horizontally long rectangular parallelepiped shape, and the power supply section 103 is arranged parallel to the outer shape of the processing chamber 101. However, which of the configuration shown in FIG. 10A and the configuration shown in FIG. 10B is selected depends on the design. Therefore, if the resonant section 106 has the configuration shown in FIG. 9, the resonant section 106 functions similarly to the resonant section 106 in the first embodiment in both the configuration shown in FIG. 10A and the configuration shown in FIG. 10B. .

As described above, in this embodiment, the resonator 106 includes five patch resonators (square patch resonators 106a) arranged in a cross shape. With this configuration, the antinode of the standing wave can be changed into a node for both the vertical polarization plane and the horizontal polarization plane. According to this embodiment, the standing wave distribution in the processing chamber 101, that is, the microwave energy distribution can be controlled.

In this embodiment, the resonator 106 includes five square patch resonators 106a arranged in a cross shape. That is, the resonator 106 has a total of five patch resonators, with three patch resonators arranged in a row in the vertical and horizontal directions. With this configuration, the number of required rectangular patch resonators 106a can be reduced compared to the case where one resonator section 106 is provided in the vertical direction and one in the horizontal direction in the first embodiment.

In the resonator 106, four or more rectangular patch resonators 106a may be arranged in the vertical and horizontal directions. In this case, the center position of the combination differs depending on the combination of three adjacent patch resonators among the four or more patch resonators. This corresponds to the existence of multiple combinations of three patch resonators.

Therefore, even if, for example, the position of the antinode of the standing wave deviates from the expected position, other combinations of three patch resonators different from the expected combination of three patch resonators may be different from the one in Embodiment 1. There is a possibility that it functions similarly to the resonant section 106 in .

(Embodiment 3)
Embodiment 3 of the present disclosure will be described with reference to FIGS. 11 to 13B. FIG. 11 is a plan view showing the configuration of the resonator 130 according to this embodiment.

As shown in FIG. 11, the resonator 130 has nine circular conductors 130c arranged on a circular dielectric 130b. Among the nine circular conductors 130c, one circular conductor 130c is arranged at the center, and the eight circular conductors 130c are arranged at equal intervals on the circumference around the central circular conductor 130c. That is, in this configuration, three circular patch resonators 130a are lined up in any of the vertical, horizontal, and diagonal directions.

In this embodiment, the vertical direction and the horizontal direction correspond to the front-back direction and the left-right direction of the processing chamber 101 in FIG. 1, respectively. The diagonal direction is a direction that makes 45 degrees to both the vertical direction and the horizontal direction.

Resonance can be generated by setting the diameter of the circular conductor 130c to approximately half the wavelength of the current flowing on the circular conductor 130c. The wavelength of a 2.45 GHz microwave is approximately 120 mm in air with a dielectric constant of 1. For this reason, if the dielectric material 130b has a dielectric constant close to 1, for example, foamed polystyrene, the diameter of the circular conductor 130c may be set to about 60 mm.

In this embodiment, a substrate with a dielectric constant of 3.5, tan δ of 0.004, and a thickness of about 0.6 mm is used as the dielectric 130b, and the circular conductor 130c is formed by a pattern of copper foil on the substrate. . With this configuration, the diameter of the resonant section 130 could be reduced to 38 mm.

FIG. 12A is a longitudinal cross-sectional view showing the configuration of microwave processing apparatus 100 according to this embodiment. FIG. 12B is a cross-sectional view taken along line 12B-12B in FIG. 12A.

In this embodiment, the microwaves are not directly radiated from the waveguide 102 to the processing chamber 101 but are radiated to the processing chamber 101 via the radiation antenna 131.

As shown in FIGS. 12A and 12B, the radiation antenna 131 has a coupling axis 132 coupled to the waveguide 102 and a radiation section 133. The radiation section 133 has three wall surfaces (wall surfaces 134a, 134b, and 134c), a flange 135 provided around the wall surfaces, a ceiling surface 136, and a front opening 137.

The radiation antenna 131 has a waveguide structure formed by wall surfaces 134a, 134b, and 134c and a ceiling surface 136, and radiates microwaves from a front opening 137 in the direction of an arrow 138. As a result, the microwave processing device 100 of this embodiment has a polarization plane that includes the arrow line 138 and is perpendicular to the paper plane of FIG. 12B.

The motor 139 engages with the coupling shaft 132 and rotates the coupling shaft 132 according to instructions from the control section 105. When the radiation section 133 rotates with the rotation of the coupling shaft 132, the direction and polarization plane of the microwave radiated from the front opening 137 also rotate.

In this way, in the configuration including the rotating radiation antenna 131, the plane of polarization has various directions in addition to the vertical and horizontal directions. Therefore, the resonator 130 having the configuration shown in FIG. 11 can exhibit an effect on the plane of polarization that occurs in the configurations shown in FIGS. 12A and 12B.

FIG. 13A is a longitudinal cross-sectional view showing another configuration of the microwave processing apparatus 100 according to this embodiment. FIG. 13B is a cross-sectional view taken along line 13B-13B in FIG. 13A.

As shown in FIG. 13B, in this configuration, the radiation antenna 131 has an X-shaped circularly polarized aperture 140 provided on the ceiling surface 136, and extends upward from the circularly polarized aperture 140 in FIG. 13A. Emit circularly polarized microwaves.

In the first and second embodiments, the microwaves emitted from the waveguide opening generate an electric field having a single vibration direction. Since the microwave transmission direction is also single, a single plane of polarization occurs in this case. Such microwaves are called linearly polarized microwaves.

On the other hand, in the case of circularly polarized microwaves, the electric field itself rotates around the intersection of the X-shaped circularly polarized apertures 140. Therefore, the plane of polarization has various directions as well as the vertical and horizontal directions. The resonator 130 having the configuration shown in FIG. 11 can exhibit an effect on the plane of polarization generated in the configurations shown in FIGS. 13A and 13B.

As described above, in the present embodiment, the resonating section 130 includes one circular patch resonator 130a arranged at the center and equidistant intervals on the circumference around the one circular patch resonator 130a. and eight circular patch resonators 130a arranged in the same direction. In this configuration, three patch resonators are lined up in any of the vertical, horizontal, and diagonal directions.

With this configuration, the resonator 130 functions in the same manner as the resonator 106 in the first embodiment in any of the vertical, horizontal, and diagonal directions.

In this embodiment, the resonator 130 is constituted by a circular patch resonator 130a including a circular conductor 130c. In a patch resonator, the length of the conductor determines whether resonance occurs. A circular conductor has the same length in any of the vertical, horizontal, and diagonal directions.

Therefore, by using the resonator 130, resonance can be generated for any plane of polarization, such as vertical, horizontal, or diagonal. According to this embodiment, the standing wave distribution in the processing chamber 101, that is, the microwave energy distribution can be controlled.

The resonator 130 of this embodiment is not limited to the above configuration. For example, the resonator 130 may include nine patch resonators arranged in a 3×3 matrix. That is, in the present embodiment, the resonator 130 includes a total of nine patch resonators, three patch resonators arranged radially in each of the vertical, horizontal, and diagonal directions. has.

In the resonator 130, four or more circular patch resonators 130a may be arranged in each of the vertical, horizontal, and diagonal directions. In this case, the center position of the combination differs depending on the combination of three adjacent patch resonators among the four or more patch resonators. This corresponds to the existence of multiple combinations of three patch resonators.

Therefore, even if, for example, the position of the antinode of the standing wave deviates from the expected position, other combinations of three patch resonators different from the expected combination of three patch resonators may be different from the one in Embodiment 1. There is a possibility that it functions similarly to the resonant section 106 in .

(Embodiment 4)
Embodiment 4 of the present disclosure will be described with reference to FIGS. 14 and 15. FIG. 14 is a perspective view showing the configuration of microwave processing apparatus 100 according to this embodiment. FIG. 15 is a diagram showing the characteristics of the resonant section shown in FIG. 14.

As shown in FIG. 14, the microwave processing apparatus 100 of this embodiment has nine resonant parts (resonant parts 141, 142, 143) arranged in a 3×3 matrix on the ceiling surface of the processing chamber 101. , 144, 145, 146, 147, 148, 149).

Each of the resonant parts 141 to 149 has nine circular conductors arranged in a 3×3 matrix on a rectangular dielectric. With this configuration, nine patch resonators are configured in each of the resonating sections 141 to 149.

Resonant parts 141 to 149 have dielectrics of the same size. However, the diameter of the circular conductor included in the circular patch resonator of each resonant section increases little by little in the order from the resonant section 141 to the resonant section 149. With this configuration, the resonant frequency of each resonant section decreases by 10 MHz in the order from the resonant section 141 to the resonant section 149.

Specifically, as shown in FIG. 15, the resonance frequencies of the resonance sections 141 to 149 are 2.49GHz, 2.48GHz, 2.47GHz, 2.46GHz, 2.45GHz, 2.44GHz, and 2.43GHz, respectively. , 2.42GHz, and 2.41GHz. The absolute value of the reflection phase is 0 degrees at these resonance frequencies.

According to this embodiment, by controlling the frequency of the supplied microwave, it is possible to switch the resonant section where resonance occurs. For example, when microwaves with a frequency of 2.49 GHz are supplied, only the resonant section 141 resonates. Thereby, the antinode of the standing wave can be changed into a node in the vicinity of the far left region where the resonator 141 is arranged. As a result, the electric field near the back left region can be weakened.

When microwaves with a frequency of 2.45 GHz are supplied, the antinode of the standing wave can be changed into a node near the central region where the resonator 145 is arranged. As a result, the electric field in the central region can be weakened.

When microwaves of 2.49 GHz, 2.46 GHz, and 2.43 GHz are supplied sequentially in a time-division manner, the antinodes of the standing waves change to nodes near the left region where the resonators 141, 144, and 147 are arranged. can be done. This allows the electric field in the left region to be weakened. In this case, the electric field in the right region becomes stronger, and as a result, the object to be heated 109 placed on the right side can be strongly heated.

In this embodiment, the resonators 141 to 149 have circular patch resonators. However, the resonators 141-149 may also include square patch resonators. The resonating sections 141 to 149 may be the resonating section 130 in the third embodiment.

According to this embodiment, by controlling the frequency of the supplied microwave, it is possible to switch the resonant section where resonance occurs. Thereby, the antinode of the standing wave can be changed into a node near the resonance part where resonance occurs. As a result, it is possible to weaken the electric field near the resonant portion where resonance occurs.

(Embodiment 5)
Embodiment 5 of the present disclosure will be described with reference to FIG. 16. FIG. 16 is a cross-sectional view showing the configuration of microwave processing apparatus 100 according to this embodiment.

As shown in FIG. 16, the microwave processing apparatus 100 of this embodiment includes a resonator 150 arranged on the ceiling surface of the processing chamber 101. The resonator 150 has five conductors arranged at a pitch P on a dielectric arranged on the ceiling of the processing chamber 101. With this configuration, the resonator 150 includes five patch resonators (patch resonators 151, 152, 153, 154, and 155).

The conductors of the five patch resonators have different lengths. The conductor of patch resonator 151 has length a1, the conductor of patch resonator 152 has length a2, the conductor of patch resonator 153 has length a3, the conductor of patch resonator 154 has length a4, and the conductor of patch resonator 155 has length a4. has length a5. The lengths a1 to a5 have the relationship a1>a2>a3>a4>a5.

That is, each of the patch resonators 151 to 155 has a conductor with a length corresponding to the order in which the patch resonators 151 to 155 are arranged. As a result, each of the patch resonators 151-155 has a resonant frequency depending on the order in which the patch resonators 151-155 are arranged.

The combinations of three adjacent patch resonators among these five patch resonators include a combination 161 at the left end, a combination 162 at the center, and a combination 163 at the right end. Combination 161 consists of patch resonators 151, 152, 153. Combination 162 consists of patch resonators 152, 153, 154. Combination 163 consists of patch resonators 153, 154, 155.

The average length of the conductors of the patch resonators included in these combinations becomes shorter from combination 161 to combination 163. Therefore, the three patch resonators included in combination 161 resonate at frequency f1, the three patch resonators included in combination 162 resonate at frequency f2, and the three patch resonators included in combination 163 resonate at frequency f2. When the resonator resonates at frequency f3, the frequencies f1 to f3 increase in this order.

Specifically, the length of the conductor of the patch resonator 153 is set to approximately 1/2 the wavelength (effective length) of a microwave used in a general microwave oven. Thereby, the frequency f2 can be set to 2.45 GHz, which is the frequency of this microwave.

The length of the conductor of patch resonator 152 is slightly longer than that of patch resonator 153, and the length of the conductor of patch resonator 151 is slightly longer than that of patch resonator 152. The length of the conductor of patch resonator 154 is slightly shorter than that of patch resonator 153, and the length of the conductor of patch resonator 155 is slightly shorter than that of patch resonator 154.

That is, in this embodiment, the conductors of all patch resonators have approximately 1/2 the wavelength (effective length) of the microwave. However, depending on the location of the arrangement, the length of the conductor in each patch resonator varies slightly.

In this embodiment, the patch resonators located at the ends of the central combination 162 are shared with the combinations 161 and 163 adjacent to the combination 162. With this configuration, three combinations of three patch resonators can be configured using five patch resonators instead of using nine patch resonators.

According to this embodiment, by setting the frequency of the supplied microwave to one of the frequencies f1 to f3, it is possible to switch the combination of patch resonators in which resonance occurs. Thereby, the antinode of the standing wave can be changed into a node near the combination of patch resonators where resonance occurs. As a result, it is possible to weaken the electric field near the patch resonator combination where resonance occurs.

In this embodiment, each of three combinations of three patch resonators may be considered to correspond to one resonator. That is, the resonance section 150 of this embodiment may be considered to include three resonance sections.

As shown in FIG. 16, the patch surfaces of the five patch resonators are comprised of copper foil applied to one side of one substrate material. The surface of the substrate material opposite the patch surface contacts the ceiling surface of the processing chamber 101. In this way, patch resonators 151, 152, 153, 154, and 155 can be arranged on the same single-sided substrate.

It is also possible to configure the patch resonators 151, 152, 153, 154, and 155 with double-sided substrates. When a patch surface is arranged on one surface of a double-sided substrate and the surface of the substrate material opposite to the patch surface is brought into contact with the ceiling surface of the processing chamber 101, the opposite surface is brought to the same potential as the metal surface of the processing chamber 101. can do.

According to this embodiment, by controlling the frequency of the supplied microwave, it is possible to switch the combination of patch resonators in which resonance occurs. Thereby, the antinode of the standing wave can be changed into a node near the combination of patch resonators where resonance occurs. As a result, it is possible to weaken the electric field near the patch resonator combination where resonance occurs.

In this embodiment, the resonator 150 is arranged only on the ceiling surface of the processing chamber 101. However, the resonator 150 may be arranged on the side surface of the processing chamber 101. For example, when the resonator 150 is placed on the right side of the processing chamber 101, a uneven standing wave distribution is generated in which a strong electric field is generated on the left side of the processing chamber 101. As a result, the object to be heated placed on the left side of the processing chamber 101 is heated more strongly.

If two resonant parts 150 are arranged one each on the ceiling surface and the right side surface, there is a possibility that a synergistic effect of the two resonant parts 150 will provide a greater effect than in the case of FIG. 8B.

If a substrate is used as the dielectric of the resonant part, the resonant part can be made smaller. However, when the energy of the output microwave increases, loss occurs and heat is generated, and sparks occur between adjacent patches. Therefore, a dielectric substrate may be used for devices that require small energy microwaves, such as for chemical reaction processing, and for devices that require large energy microwaves, such as for heating food. If so, you can use another method.

The second effect explained using FIGS. 6A to 6C is that the center patch resonator out of the three patch resonators is floating from the ground, and the strong electric field generated because its potential is uncertain. , by the opposite electric fields generated by the three patch resonators.

In addition to the configurations shown in FIGS. 6A to 6C, a configuration in which a switch is disposed between the central patch resonator and the ground plane to perform switching control is also conceivable. In this case, when the switch is turned off, the second effect occurs because the patch resonator is floating above ground. However, when the switch is turned on, the central patch resonator is grounded and the second effect does not occur.

Furthermore, in order to make effective use of the switches, a configuration in which all patch resonators are provided with switches is also conceivable. In this case, all switches are normally turned on to ground the patch resonator and prevent the second effect from occurring.

When the switches for at least three patch resonators are turned off and the patch resonators are lifted above ground, a second effect occurs, which can transform the antinode of the standing wave in its vicinity into a node.

According to this method, the standing wave distribution can be arbitrarily controlled only by on/off control of a switch, even without controlling the frequency or using all resonant parts of the same size.

The present disclosure can be applied to a microwave processing apparatus that performs heat treatment, chemical reaction treatment, etc. of foods and the like.

100 Microwave processing device 101 Processing chamber 102 Waveguide 103 Power supply section 104 Microwave generation section 105 Control section 106, 130, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150 Resonance section 106a Square Patch resonator 106b, 130b dielectric 106c rectangular conductor 107 mounting plate 108, 109 object to be heated 110 microwave 130a circular patch resonator 130c circular conductor 151, 152, 153, 154, 155 patch resonator 160 microwave supply section

Claims (9)

a processing chamber that accommodates an object to be heated;
a microwave supply unit that supplies microwaves to the processing chamber;
A plurality of patch resonators having a resonant frequency in the microwave frequency band and arranged so that at least three patch resonators are lined up along the direction of a polarization plane generated on a metal wall surface constituting the processing chamber. a resonant section having;
The at least three patch resonators include patch resonators at both ends and a central patch resonator, and the current vector that is opposite to the current vector generated in the patch resonators at both ends resonates with the central patch resonator. The microwave processing device , wherein the central patch resonator is disposed between the end patch resonators so as to occur in a microwave oven . The microwave processing device according to claim 1, wherein the plurality of patch resonators are arranged such that the at least three patch resonators are lined up in each of a vertical direction and a horizontal direction. The microwave processing apparatus according to claim 2, wherein the plurality of patch resonators includes at least five square patch resonators arranged in a cross shape. The microwave processing device according to claim 1, wherein the plurality of patch resonators are arranged such that the at least three patch resonators are arranged radially in each of a vertical direction, a horizontal direction, and an oblique direction. . The microwave processing device according to claim 4, wherein the patch resonator is a circular patch resonator. a processing chamber that accommodates an object to be heated;
a microwave supply unit that supplies microwaves to the processing chamber;
A plurality of patch resonators having a resonant frequency in the frequency band of the microwave and arranged so that at least three patch resonators are lined up along the direction of a plane of polarization generated on a metal wall surface constituting the processing chamber. A microwave processing device comprising: a resonating section having
The microwave supply unit includes a microwave generation unit and a control unit that controls an oscillation frequency of the microwave generation unit,
The resonant part has a plurality of resonant parts having different resonant frequencies,
The microwave processing device, wherein the control section switches the resonant section that resonates among the plurality of resonant sections by controlling the oscillation frequency. The resonant section has a plurality of resonant sections, each of the plurality of resonant sections is provided in each of a plurality of divided regions on one of the metal wall surfaces constituting the processing chamber, and the plurality of resonant sections 7. The microwave processing apparatus according to claim 6, wherein the microwave processing apparatus has mutually different resonance frequencies. The microwave processing device according to claim 6, wherein each of the plurality of resonance parts has a resonance frequency according to the order in which the plurality of resonance parts are arranged. 9. The microwave processing device according to claim 8, wherein each of the plurality of resonance parts has a conductor having a length corresponding to the order in which the plurality of resonance parts are arranged.

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