JP6578804B2 - Microwave heating device - Google Patents

Description

  The present invention relates to a microwave heating apparatus.

  In a microwave heating apparatus such as a microwave oven, microwaves are emitted from a magnetron into a heating chamber, and a heated object to be heated placed in the heating chamber is heated by absorbing the emitted microwaves. At this time, the microwave radiated from the magnetron is absorbed by the heated object while being repeatedly reflected in the heating chamber. In a microwave heating apparatus such as a microwave oven having such a structure, the microwave power radiated to the heating chamber hardly depends on the position of the object to be heated. Heating can also be performed by placing a heating element.

JP-A-10-172750 JP 2004-213976 A

  In the microwave heating apparatus such as the microwave oven described above, the object to be heated is heated by radiating microwaves to the object to be heated placed in the heating chamber. Accordingly, the heating chamber is made relatively large so that heated objects of various sizes can be placed therein. Therefore, the microwave heating apparatus is relatively large. Therefore, there is a demand for a microwave heating apparatus that can heat the object to be heated even if it is small.

  By the way, there is a structure using an antenna as a microwave heating apparatus. In a microwave heating apparatus using an antenna, a microwave is emitted from an antenna toward a heated object, and the emitted microwave is covered. The heating element is heated by absorption.

  In a microwave heating apparatus using an antenna, the object to be heated is placed when the distance between the antenna and the object to be heated is sufficiently long (for example, one wavelength or more away from the emitted microwave). Depending on the position, the power of the microwave radiated from the antenna does not change. This is because when the distance between the antenna and the heated object is sufficiently large, the impedance of the antenna does not change even if the distance between the antenna and the heated object changes. Note that the length of one wavelength in the microwave is, for example, about 12.5 cm in the case of a frequency of 2.4 GHz.

  However, when a microwave heating device using an antenna is downsized, the distance between the antenna that radiates microwaves and the object to be heated is shortened. When the distance between the antenna and the object to be heated becomes shorter as described above, the impedance of the antenna changes depending on the distance between the antenna and the object to be heated, so that the characteristics of the antenna change, and the microwave radiated from the antenna changes. The electric power varies greatly depending on the distance to the object to be heated. Thereby, when a user puts a to-be-heated body in arbitrary positions, the case to which a to-be-heated body is not heated will arise.

  As described above, the microwave heating apparatus using the antenna may not be heated when the size is simply reduced, and the microwave heating apparatus is maintained while maintaining the current configuration of the microwave heating apparatus. It is difficult to reduce the size of the wave heating device. Therefore, there is a demand for a microwave heating device having a new structure that can be miniaturized.

According to one aspect of the present embodiment, the antenna unit includes a plurality of antenna units and a microwave generator connected to the antenna unit, and the antenna unit includes an antenna and a dielectric member that covers the antenna. and comprise a, each of the antenna unit, the surface of the dielectric member being disposed in contact with the body to be heated, wherein the antenna, Ri antenna der for radiating microwaves near field The antenna unit is formed in an annular shape by connecting with an elastic member, and the heated body is put into the annularly formed ring, and the restoring force of the elastic member the heated body, characterized that you have to contact the plurality of antenna units.

  According to the disclosed microwave heating apparatus, the microwave heating apparatus can be reduced in size.

Structure diagram of microwave heating device using antenna Correlation diagram between distance between antenna and heated object and microwave reflection | S11 | Illustration of microwave heating device using antenna Explanatory drawing of the microwave heating apparatus in 1st Embodiment Explanatory drawing of the antenna unit in 1st Embodiment Correlation diagram between the distance between the antenna and the object to be heated in the first embodiment and the reflection of microwave | S11 | Explanatory drawing of the microwave heating device in 2nd Embodiment Explanatory drawing of the antenna unit in 2nd Embodiment Explanatory drawing (1) of the antenna unit in 3rd Embodiment Explanatory drawing (2) of the antenna unit in 3rd Embodiment

  The form for implementing is demonstrated below. In addition, about the same member etc., the same code | symbol is attached | subjected and description is abbreviate | omitted.

[First Embodiment]
First, problems when the microwave heating apparatus using an antenna is reduced in size will be described. In this application, when the wavelength of the microwave radiated from the antenna is λ, a region where the distance D from the antenna is D ≦ λ / 2π, which is close to the antenna, is a near field, A region where D> λ / 2π having a long distance may be referred to as a far field.

  When the microwave heating device using the antenna is downsized, the distance between the antenna and the heated object is short, and as described above, the impedance of the antenna depends on the distance between the antenna and the heated object. The power of the microwave radiated from the antenna changes greatly. In other words, in the near field where the distance between the antenna that radiates microwaves and the heated object is short, the impedance of the antenna changes depending on the distance between the antenna and the heated object. The power of the will also change greatly.

  Therefore, the antenna can be designed in consideration of the distance between the antenna and the heated object so that the heated object placed at a position away from the antenna by a predetermined distance can be heated. However, when such an antenna is used, an object to be heated placed at a position shifted from a predetermined distance may not be heated. This will be specifically described with reference to FIG.

  FIG. 1 shows the structure of a microwave heating apparatus having an antenna. The microwave heating apparatus includes an object to be heated 10, an antenna 20 that radiates microwaves that heat the object to be heated 10, a microwave generator 30, and the like. The antenna 20 and the microwave generator 30 are connected by a cable 40, and the heated object 10 and the antenna 20 are installed in the heating chamber 50. Microwaves generated by the microwave generator 30, for example, microwaves having a frequency of 2.4 GHz, are sent to the antenna 20 through the cable 40 and radiated from the antenna 20.

  In the near field, the impedance changes depending on the distance D between the antenna 20 and the object to be heated 10. Therefore, when the position where the object to be heated 10 is placed is a predetermined position to be heated, the object to be heated 10 is heated, but when the position is deviated from the predetermined position, the microwave is The object 20 is reflected almost without being radiated, and the object to be heated 10 is not heated. That is, when the position where the object to be heated 10 is placed deviates from a predetermined position, the microwave is reflected almost without being radiated from the antenna 20 and returns to the microwave generator 30. Therefore, microwaves are not radiated from the antenna 20 and the heated object 10 is not heated.

  FIG. 2 shows the relationship between the distance D between the object to be heated 10 and the antenna 20 and the reflection | S11 | that returns from the antenna 20 to the microwave generator 30. As shown in FIG. 2, in the near field, there is an optimum distance Dt at which the reflection | S11 | is lowest, and the heated object 10 is installed at a position away from the antenna 20 by the optimum distance Dt. In this case, the heated object 10 is heated most. However, when the heated object 10 is installed at a position deviated from the optimum distance Dt, reflection is increased, so that the heated object 10 is hardly heated.

  For example, as shown in FIG. 3A, when the heated object 10 is placed at a position away from the antenna 20 by the optimum distance Dt, microwaves are radiated from the antenna 20, and the heated object 10 Is heated. However, as shown in FIG. 3B, when the distance D between the antenna 20 and the object to be heated 10 deviates from the optimum distance Dt from the antenna 20, the microwave radiated from the antenna 20 is Since it decreases rapidly, the heated object 10 is not heated. Specifically, when the object to be heated 10 is placed at a position shifted by about 2 mm from the optimum distance Dt, the microwave radiated from the antenna 20 rapidly decreases to 1/10 to 1/100. The heated object 10 is hardly heated.

  In addition, the size of the object to be heated 10 to be heated is not uniform and there are various sizes. For example, the heated object 10 may be a beverage or the like contained in a plastic bottle container, but there are various types of plastic bottles in the world. Therefore, in order to be able to heat beverages and the like contained in various sizes of PET bottles, it is necessary to make the inside of the heating chamber 50 large with a margin. In this case, as shown in FIG. 3C, when the size of the heated object 10 is small, when the user places the heated object 10 in the center of the heating chamber 50, the antenna 20 and the heated object Since the distance D to the body 10 is longer than the optimum distance Dt, the body to be heated 10 is hardly heated.

  Therefore, when the microwave heating apparatus using the antenna as shown in FIG. 1 is miniaturized, the position where the object to be heated 10 is placed, that is, the distance D between the antenna 20 and the object to be heated 10 is determined by the heating. The object to be heated will not be heated unless it is strictly installed at the optimal position. In this case, as a microwave heating apparatus, it is inconvenient and not practical.

(Microwave heating device)
Next, the microwave heating apparatus in this Embodiment is demonstrated based on FIG. 4A is a perspective view of the microwave heating apparatus in the present embodiment, and FIG. 4B is a top view. As shown in FIG. 4, the antenna device in the present embodiment has a plurality of antenna units 110, and the antenna unit 110 and the antenna unit 110 are connected by an elastic member 150 such as a spring or rubber. It is formed in an annular shape. That is, the microwave heating apparatus according to the present embodiment connects the antenna units 110 to the elastic member 150, thereby providing a plurality of antenna units 110 and the elastic member 150 connecting the antenna units 110. It is formed in an annular shape. Each antenna unit 110 is connected to the microwave generator 160 by a cable 170 or the like. In the present embodiment, the object to be heated 100 to be heated is placed in a ring of the microwave heating device in the present embodiment formed in an annular shape, and each antenna unit 110 surrounds the object to be heated 100. Is surrounded.

  As shown in FIG. 5, the antenna unit 110 includes an antenna 120 formed of a material such as metal, and a first dielectric member 131 and a second dielectric member 132 that cover the antenna 120. . In the antenna unit 110, the surface of the first dielectric member 131 in contact with the object to be heated 100 may be referred to as a front surface 110a, and the surface of the second dielectric member 132 opposite to the front surface 110a may be referred to as a back surface 110b. 5A is an exploded perspective view of the antenna unit 110, FIG. 5B is a sectional view in the xy plane, and FIG. 5C is a sectional view in the yz plane.

  The antenna 120 is formed of a material such as metal, and a monopole antenna, a dipole antenna, a patch antenna, or the like can be used. The first dielectric member 131 and the second dielectric member 132 that cover the antenna 120 are formed of a dielectric material such as ceramics or resin that hardly absorbs microwaves. Specifically, the first dielectric member 131 and the second dielectric member 132 are preferably made of quartz, alumina, glass epoxy resin, or the like. In the present embodiment, the first dielectric member 131 and the second dielectric member 132 are the same. The dielectric member 132 is made of alumina.

  The microwave heating apparatus in the present embodiment is installed so that the surface 110 a of the antenna unit 110, that is, the surface of the first dielectric member 131 is in contact with the outside of the heated object 100. Since the antenna unit 110 has the lowest reflection at a predetermined distance, the thickness t of the first dielectric member 131 is a value that takes this predetermined distance into account, for example, approximately 9 mm, which is substantially the same as the predetermined distance. It is formed to become.

  Further, when the first dielectric member 131 and the second dielectric member 132 are formed of a material having a high relative dielectric constant, the effective wavelength is shortened, so that further miniaturization is possible. Examples of such a material having a high relative dielectric constant include a ferroelectric.

  In the microwave heating apparatus according to the present embodiment, the elastic member 150 is stretched, and the object to be heated 100 is placed in a ring of the microwave heating apparatus formed in an annular shape. 100 and the antenna unit 110 are brought into contact with each other. Therefore, the microwave heating apparatus in the present embodiment is installed in the heated object 100 in a state where the surface 110a of the antenna unit 110 connected by the elastic member 150 is in contact with the periphery of the heated object 100. The

  FIG. 6 shows the relationship between the distance D from the antenna 120 and the microwave reflection | S11 | in the microwave heating apparatus according to the present embodiment. The lower the microwave reflection | S11 |, the more microwaves are radiated from the antenna 120. Therefore, the heated object 100 is efficiently heated by installing the heated object 100 at a predetermined distance where the reflection is lowest. can do. As shown in FIG. 6, the reflection | S11 | is lowest when the distance D from the antenna 120 on which the heated object 100 is placed is about 9 mm. FIG. 6 shows a calculation result obtained when the antenna 120 is a patch antenna and the heated object 100 is water.

  The microwave heating apparatus in the present embodiment is formed so that the thickness t of the first dielectric member 131 is substantially equal to a predetermined distance at which reflection is lowest based on FIG. Further, as shown in FIG. 4, the surface of the first dielectric member 131 of the microwave heating apparatus, that is, the surface 110 a of the antenna unit 110 is installed so as to be in contact with the periphery of the heated object 100. Therefore, the distance between the antenna 120 and the object to be heated 100 is kept at a distance at which reflection is lowest, and the impedance of the antenna 120 does not change, so that the object to be heated 100 can be efficiently heated.

  Further, since the microwave heating device in the present embodiment is installed so as to surround the periphery of the object to be heated 100, the microwave heating device can be made smaller, and further, the position where the object to be heated 100 is placed, etc. Can be efficiently heated without considering the above. Further, since the elastic member 150 expands and contracts, the shape and size of the ring of the microwave heating device in the present embodiment formed in an annular shape can be freely changed. Therefore, the heated body 100 can be efficiently heated without depending on the shape and size of the heated body 100.

[Second Embodiment]
Next, the microwave heating apparatus in 2nd Embodiment is demonstrated based on FIG. The microwave heating apparatus in this embodiment has a so-called back short structure in which a ground electrode connected to the ground potential is provided on the back surface of the antenna unit. FIG. 7A is a perspective view of the microwave heating apparatus in the present embodiment, and FIG. 7B is a top view.

  As shown in FIG. 7, the microwave heating apparatus in the present embodiment has a plurality of antenna units 210, and an elastic member 150 such as a spring or rubber is provided between the antenna units 210 and 210. And are formed in an annular shape. That is, the microwave heating apparatus according to the present embodiment connects the antenna units 210 to the elastic member 150, thereby providing a plurality of antenna units 210 and the elastic member 150 connecting the antenna units 210. It is formed in an annular shape. Each antenna unit 210 is connected to the microwave generator 160 by a cable 170 or the like. In the present embodiment, the object to be heated 100 to be heated is put in a ring of the microwave heating device in the present embodiment formed in an annular shape, and each antenna unit 210 surrounds the object to be heated 100. It is installed to be surrounded.

  As shown in FIGS. 7 and 8, the antenna unit 210 includes an antenna 120 formed of a material such as metal, and a first dielectric member 131 and a second dielectric member 132 that cover the antenna 120. is doing. 8A is an exploded perspective view of the antenna unit 210, FIG. 8B is a cross-sectional view in the xy plane, and FIG. 8C is a cross-sectional view in the yz plane.

  In the antenna unit 210, the surface 110a of the antenna unit 210 in contact with the heated body 100 is in contact with the heated body 100, and the back surface 110b of the antenna unit 210 opposite to the front surface 110a, that is, on the surface of the second dielectric member 132. The ground electrode 230 is formed. The ground electrode 230 is connected to the ground potential in the microwave generator 160 by a cable 270. As described above, by forming the ground electrode 230 on the back surface of the antenna unit 210 and connecting the ground electrode 230 to the ground potential, the microwave leaking from the antenna 120 can be blocked. That is, in the microwave heating apparatus according to the present embodiment, the antenna 120 is designed so that microwaves are radiated in the near field, so that almost no microwaves are radiated to the back surface 110 b side of the antenna unit 210. However, even a slight microwave may cause trouble in an electronic device or the like when the microwave is emitted. For this reason, the ground electrode 230 is formed on the back surface 110b of the antenna unit 210, and the ground electrode 230 is connected to the ground potential, thereby improving the shielding property of the microwave radiated from the back surface 110b side of the antenna unit 210.

  The contents other than the above are the same as in the first embodiment.

[Third Embodiment]
Next, the microwave heating apparatus in 3rd Embodiment is demonstrated based on FIG.9 and FIG.10. FIG. 9A is a perspective view of the microwave heating apparatus in the present embodiment, and FIG. 9B is a top view. FIG. 10A is a perspective view of a state in which the microwave heating apparatus according to the present embodiment is attached to an object to be heated, and FIG. 10B is a top view.

  As shown in FIG. 9 and FIG. 10, the antenna device according to the present embodiment includes a plurality of antenna units 110 that are predetermined in order from one end of the surface of the flexible winding member 380 toward the other end. Installed at intervals. At this time, the antenna unit 110 is attached to the winding member 380 on the back surface 110b side of the antenna unit 110 so that the surface of the first dielectric member 131 that becomes the front surface 110a of the antenna unit 110 is exposed. An adhesive member 381 such as Velcro (registered trademark) is provided at the other end of the surface of the winding member 380, and the back surface of the winding member 380 is attached when the adhesive member 381 comes into contact with the surface. Is formed.

  Therefore, the antenna device according to the present embodiment wraps the winding member 380 to which the antenna unit 110 is attached around the heated body 100, and attaches the adhesive member 381 to the back surface of the winding member 380. It is attached to the heating body 100. Therefore, the microwave heating apparatus in the present embodiment is attached in a state of being wound around the object to be heated 100.

  Moreover, since the microwave heating apparatus in this Embodiment is wound around the to-be-heated body 100, a microwave heating apparatus can be made small and the position etc. where the to-be-heated body 100 is placed are considered. The heated object 100 can be efficiently heated. Furthermore, since the microwave heating apparatus in this embodiment is wound around the object 100 to be heated, the object 100 can be efficiently heated without depending on the size of the object 100 to be heated. it can.

  The contents other than the above are the same as in the first embodiment.

  Although the embodiment has been described in detail above, it is not limited to the specific embodiment, and various modifications and changes can be made within the scope described in the claims.

In addition to the above description, the following additional notes are disclosed.
(Appendix 1)
A plurality of antenna units;
A microwave generator connected to the antenna unit;
Have
The antenna unit includes an antenna and a dielectric member that covers the antenna,
Each of the antenna units is installed such that the surface of the dielectric member is in contact with the object to be heated,
The microwave heating apparatus, wherein the antenna is an antenna that radiates microwaves in a near field.
(Appendix 2)
The thickness of the dielectric member between the antenna and the object to be heated is λ / 2π or less, where λ is the wavelength of the microwave generated in the microwave generator. The microwave heating apparatus according to appendix 1.
(Appendix 3)
The thickness of the dielectric member between the antenna and the heated object is formed so that the microwave reflected from the antenna to the microwave generator is the lowest. 2. The microwave heating apparatus according to 2.
(Appendix 4)
It is formed in an annular shape by connecting the antenna units with an elastic member,
Appendices 1 to 3, wherein the object to be heated is placed in the ring formed in an annular shape, and a plurality of the antenna units are in contact with the object to be heated by a restoring force of the elastic member. The microwave heating device according to any one of the above.
(Appendix 5)
The plurality of antenna units are attached to a winding member,
4. The microwave heating apparatus according to any one of appendices 1 to 3, wherein a winding member to which the plurality of antenna units are attached is wound around the object to be heated.
(Appendix 6)
A ground electrode is formed on the back surface opposite to the front surface of the antenna unit,
6. The microwave heating apparatus according to any one of appendices 1 to 5, wherein the ground electrode is grounded.

10 Heated object 20 Antenna 30 Microwave generator 40 Cable 100 Heated object 110 Antenna unit 120 Antenna 131 First dielectric member 132 Second dielectric member 150 Elastic member 160 Microwave generator 170 Cable

Claims (5)

A plurality of antenna units;
A microwave generator connected to the antenna unit;
Have
The antenna unit includes an antenna and a dielectric member that covers the antenna,
Each of the antenna units is installed such that the surface of the dielectric member is in contact with the object to be heated,
The antenna, Ri antenna der for radiating microwaves in the near field,
It is formed in an annular shape by connecting the antenna units with an elastic member,
The put object to be heated in said annular formed wheels, by the restoring force of the elastic member, the the object to be heated, a microwave heating apparatus which is characterized that you have to contact the plurality of antenna units . A plurality of antenna units;
A microwave generator connected to the antenna unit;
Have
The antenna unit includes an antenna and a dielectric member that covers the antenna,
Each of the antenna units is installed such that the surface of the dielectric member is in contact with the object to be heated,
The antenna is an antenna that radiates microwaves in the near field;
The plurality of antenna units are attached to a winding member,
A plurality of said wound member on which the antenna unit is attached, the features and to luma microwave heating apparatus that is wrapped heated body. The thickness of the dielectric member between the antenna and the object to be heated is λ / 2π or less, where λ is the wavelength of the microwave generated in the microwave generator. The microwave heating device according to claim 1 or 2 . The thickness of the dielectric member between the antenna and the object to be heated is formed so that the microwave reflected from the antenna to the microwave generator is the lowest. Item 4. The microwave heating apparatus according to Item 3 . A ground electrode is formed on the back surface opposite to the front surface of the antenna unit,
The ground electrode is a microwave heating apparatus according to any one of claims 1 to 4, characterized in that it is grounded.

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