High-frequency dielectric heating device

Abstract

This high-frequency dielectric heating device is configured so as to be provided with: electrodes (11, 12) to which a high-frequency voltage is applied; and a radio wave absorber (13) disposed so as to contain the electrodes (11, 12).

Description

High-frequency dielectric heating device

[0001] The present disclosure relates to a high-frequency dielectric heating device.

[0002] There is a high-frequency dielectric heating device including a first electrode plate to which a high-frequency voltage is applied and a second electrode plate arranged to face the first electrode plate, and heating an object to be heated arranged between the first electrode plate and the second electrode plate by a high-frequency electric field generated between the first electrode plate and the second electrode plate. As such a high-frequency dielectric heating device, for example, Patent Document 1 discloses a high-frequency dielectric heating device provided with a metal housing that houses the first electrode plate and the second electrode plate so that the high-frequency electric field generated between the first electrode plate and the second electrode plate does not leak to the outside.

[0003] Japanese Unexamined Patent Application Publication No. 2023-046708

[0004] In the high-frequency dielectric heating device disclosed in Patent Document 1, in addition to a high-frequency electric field being generated between the first electrode plate and the second electrode plate, a high-frequency electric field may be generated between the first electrode plate and the metal housing. Since the high-frequency electric field generated between the first electrode plate and the metal housing is an electric field that does not contribute to heating the object to be heated, there has been a problem that the heating efficiency of the high-frequency dielectric heating device decreases.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to obtain a high-frequency dielectric heating device capable of suppressing the generation of an electric field that does not contribute to heating the object to be heated.

[0006] The high-frequency dielectric heating device according to the present disclosure includes an electrode to which a high-frequency voltage is applied and a radio wave absorber arranged so as to include the electrode.

[0007] According to the present disclosure, the generation of an electric field that does not contribute to heating the object to be heated can be suppressed.

[0008] This is a perspective view showing a high-frequency dielectric heating device according to Embodiment 1. This is a perspective view showing a high-frequency dielectric heating device according to Embodiment 1. This is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 1. This is a perspective view showing another high-frequency dielectric heating device according to Embodiment 1. This is a cross-sectional view showing another high-frequency dielectric heating device according to Embodiment 1. This is a perspective view showing another high-frequency dielectric heating device according to Embodiment 1. This is a cross-sectional view showing another high-frequency dielectric heating device according to Embodiment 1. This is a perspective view showing a high-frequency dielectric heating device according to Embodiment 2. This is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 2. This is a perspective view showing a high-frequency dielectric heating device according to Embodiment 3. This is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 3. This is a perspective view showing a high-frequency dielectric heating device according to Embodiment 4. This is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 4. This is a perspective view showing a high-frequency dielectric heating device according to Embodiment 5. This is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 5. This is a perspective view showing a high-frequency dielectric heating device according to Embodiment 6. This is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 6. This is a perspective view showing a high-frequency dielectric heating device according to Embodiment 7. This is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 7. This is a perspective view showing a high-frequency dielectric heating device according to Embodiment 8. This is a cross-sectional view showing a high-frequency dielectric heating apparatus according to Embodiment 8.

[0009] To provide a more detailed explanation of this disclosure, the forms for implementing this disclosure will be described below with reference to the attached drawings.

[0010] Embodiment 1. Figure 1 is a perspective view showing a high-frequency dielectric heating device according to Embodiment 1. Figure 2 is a perspective view showing a high-frequency dielectric heating device according to Embodiment 1. Figure 3 is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 1. The high-frequency dielectric heating device shown in Figures 1 to 3 includes a first electrode plate 1 and a second electrode plate 2 as electrodes. The high-frequency dielectric heating device shown in Figures 1 to 3 also includes a radio wave absorber 3.

[0011] In the high-frequency dielectric heating apparatus shown in Figures 1 to 3, a first electrode plate 1 is provided as the upper electrode plate. The first electrode plate 1 is connected to a high-frequency power supply (not shown) located externally via wires (not shown). A high-frequency voltage is applied to the first electrode plate 1 by the high-frequency power supply.

[0012] In the high-frequency dielectric heating apparatus shown in Figures 1 to 3, a second electrode plate 2 is provided as the lower electrode plate. The second electrode plate 2 is connected to a ground (not shown). The second electrode plate 2 is positioned opposite the first electrode plate 1. When a high-frequency voltage is applied to the first electrode plate 1 by a high-frequency power supply, a high-frequency electric field is generated between the first electrode plate 1 and the second electrode plate 2.

[0013] The radio wave absorber 3 is positioned to enclose the first electrode plate 1 and the second electrode plate 2. The radio wave absorber 3 acts to absorb or shield the high-frequency electric field so that the high-frequency electric field generated between the first electrode plate 1 and the second electrode plate 2 does not leak to the outside. The concept of the radio wave absorber 3 enclosing the first electrode plate 1 and the second electrode plate 2 includes not only the embodiment of completely surrounding the first electrode plate 1 and the second electrode plate 2, but also the embodiment of surrounding a part of the first electrode plate 1 and the second electrode plate 2.

[0014] Examples of radio wave absorbers 3 include resistive radio wave absorbers, dielectric radio wave absorbers, and magnetic radio wave absorbers. A resistive radio wave absorber has a conductor containing resistance, and absorbs the energy of radio waves by consuming the induced current generated when radio waves are incident on the conductor through the resistance contained in the conductor. A dielectric radio wave absorber is made of a dielectric material such as foamed polyethylene or rubber mixed with carbon particles, and absorbs the energy of radio waves by consuming the current generated when the impedance of the capacitive component of the carbon particles decreases upon the incidence of radio waves through the resistance component of the carbon particles. A magnetic radio wave absorber is made of a magnetic material such as ferrite, and absorbs the energy of incident radio waves through the magnetic loss of the magnetic material.

[0015] Next, the operation of the high-frequency dielectric heating apparatus shown in Figures 1 to 3 will be explained. The object to be heated is placed between the first electrode plate 1 and the second electrode plate 2. In Figure 3, the object to be heated is depicted as being in close contact with both the first electrode plate 1 and the second electrode plate 2, but the object to be heated only needs to be placed between the first electrode plate 1 and the second electrode plate 2; it does not need to be in close contact with both the first electrode plate 1 and the second electrode plate 2. With the object to be heated placed between the first electrode plate 1 and the second electrode plate 2, a high-frequency voltage is applied to the first electrode plate 1 by a high-frequency power supply (not shown). For example, a frequency in the tens of MHz band is used for the high-frequency voltage. At this time, the potential of the second electrode plate 2 is the ground potential. When a high-frequency voltage is applied to the first electrode plate 1, a high-frequency electric field is generated between the first electrode plate 1 and the second electrode plate 2. Since the object to be heated is placed in the high-frequency electric field, dielectric loss occurs within the object to be heated. The object being heated is heated due to dielectric loss.

[0016] The high-frequency dielectric heating device shown in Figure 1, etc., includes a radio wave absorber 3 arranged to enclose a first electrode plate 1 and a second electrode plate 2. The radio wave absorber 3 acts to absorb or shield the high-frequency electric field so that the high-frequency electric field generated between the first electrode plate 1 and the second electrode plate 2 does not leak to the outside. Therefore, the radio wave absorber 3 acts as a shielding member, similar to a metal casing. However, since the radio wave absorber 3 is not a metal casing, a high-frequency electric field is not directly generated between the first electrode plate 1 and the radio wave absorber 3. As a result, the high-frequency electric field can be concentrated between the first electrode plate 1 and the second electrode plate 2, thereby increasing the heating efficiency of the high-frequency dielectric heating device. Since a high-frequency electric field is not directly generated between the first electrode plate 1 and the radio wave absorber 3, the heating efficiency of the high-frequency dielectric heating device does not decrease even if the distance between the first electrode plate 1 and the radio wave absorber 3 is shortened. Therefore, the high-frequency dielectric heating device can be miniaturized.

[0017] In the above embodiment 1, the high-frequency dielectric heating device is configured to include a first electrode plate 1 to which a high-frequency voltage is applied, a second electrode plate 2 arranged to face the first electrode plate 1, and a radio wave absorber 3 arranged to encompass the first electrode plate 1 and the second electrode plate 2. Therefore, the high-frequency dielectric heating device can suppress the generation of high-frequency electric fields other than between the first electrode plate 1 and the second electrode plate 2.

[0018] The high-frequency dielectric heating device shown in Figure 1, etc., comprises a plate-shaped first electrode plate 1 and a plate-shaped second electrode plate 2. However, this is merely one example, and the high-frequency dielectric heating device may also include electrodes that are not plate-shaped. In this case, the radio wave absorber 13 only needs to be arranged to enclose the non-plate-shaped electrodes 11 and 12, as shown in Figures 4 and 5. Figure 4 is a perspective view showing another high-frequency dielectric heating device according to Embodiment 1. Figure 5 is a cross-sectional view showing another high-frequency dielectric heating device according to Embodiment 1. The high-frequency dielectric heating device shown in Figures 4 and 5 comprises electrodes 11, electrode plates 12, and a radio wave absorber 13.

[0019] The electrode 11 is connected to an externally located high-frequency power supply (not shown) via wires (not shown). A high-frequency voltage is applied to the electrode 11 by the high-frequency power supply. In the example shown in Figure 4, the electrode 11 is a round rod. However, this is just one example, and the electrode 11 can be any shape.

[0020] Electrode 12 is connected to a ground (not shown). In the example in Figure 4, electrode 12 is cylindrical in shape, with electrode 11 positioned inside electrode 12. A high-frequency voltage is applied to electrode plate 11 by a high-frequency power supply, generating a high-frequency electric field between electrode 11 and electrode plate 12. The object to be heated is placed between electrode 11 and electrode plate 12.

[0021] The radio wave absorber 13 is positioned to enclose the electrode 11 and the electrode plate 12. The radio wave absorber 13 acts to absorb or shield the high-frequency electric field so that the high-frequency electric field generated between the electrode 11 and the electrode 12 does not leak to the outside. The concept of the radio wave absorber 13 enclosing the electrode 11 and the electrode 12 includes not only the embodiment of completely surrounding the electrode 11 and the electrode 12, but also the embodiment of surrounding a part of the electrode 11 and the electrode 12. Examples of radio wave absorbers 13 include resistive type radio wave absorbers, dielectric type radio wave absorbers, and magnetic type radio wave absorbers.

[0022] The high-frequency dielectric heating device shown in Figure 1, etc., comprises two electrodes: a first electrode plate 1 and a second electrode plate 2. The first electrode plate 1 and the second electrode plate 2 are arranged opposite each other. However, this is merely one example, and a high-frequency dielectric heating device may also have three or more electrodes, as shown in Figures 6 and 7. Figure 6 is a perspective view showing another high-frequency dielectric heating device according to Embodiment 1. Figure 7 is a cross-sectional view showing another high-frequency dielectric heating device according to Embodiment 1. The high-frequency dielectric heating device shown in Figures 6 and 7 comprises a first electrode plate 21, a second electrode plate 22, a third electrode plate 23, a fourth electrode plate 24, a fifth electrode plate 25, and a radio wave absorber 26.

[0023] In the high-frequency dielectric heating apparatus shown in Figures 6 and 7, the first electrode plate 21 is provided as the lower electrode plate. The first electrode plate 21 is connected to a high-frequency power supply (not shown) located externally via wires (not shown). A high-frequency voltage is applied to the first electrode plate 21 by the high-frequency power supply. In the high-frequency dielectric heating apparatus shown in Figures 6 and 7, the second electrode plate 22, the third electrode plate 23, the fourth electrode plate 24, and the fifth electrode plate 25 are each provided as side electrode plates. The second electrode plate 22, the third electrode plate 23, the fourth electrode plate 24, and the fifth electrode plate 25 are each connected to a ground (not shown). In the high-frequency dielectric heating apparatus shown in Figures 6 and 7, the first electrode plate 21 and the second electrode plate 22, the third electrode plate 23, the fourth electrode plate 24, and the fifth electrode plate 25 are not arranged facing each other. In the high-frequency dielectric heating apparatus shown in Figures 6 and 7, the first electrode plate 21, the second electrode plate 22, the third electrode plate 23, the fourth electrode plate 24, and the fifth electrode plate 25 are all plate-shaped. However, this is merely an example, and the shapes of the first electrode plate 21, the second electrode plate 22, the third electrode plate 23, the fourth electrode plate 24, and the fifth electrode plate 25 can be any shape.

[0024] The radio wave absorber 26 is arranged to encompass each of the first electrode plate 21, the second electrode plate 22, the third electrode plate 23, the fourth electrode plate 24, and the fifth electrode plate 25. The radio wave absorber 26 acts to absorb or shield high-frequency electric fields so that the high-frequency electric fields generated between the first electrode plate 21 and the second electrode plate 22, between the first electrode plate 21 and the third electrode plate 23, between the first electrode plate 21 and the fourth electrode plate 24, and between the first electrode plate 21 and the fifth electrode plate 25 do not leak to the outside. The inclusion of the first electrode plate 21, the second electrode plate 22, the third electrode plate 23, the fourth electrode plate 24, and the fifth electrode plate 25 by the radio wave absorber 26 is a concept that includes not only an embodiment in which the first electrode plate 21, the second electrode plate 22, the third electrode plate 23, the fourth electrode plate 24, and the fifth electrode plate 25 are completely surrounded, but also an embodiment in which parts of the first electrode plate 21, the second electrode plate 22, the third electrode plate 23, the fourth electrode plate 24, and the fifth electrode plate 25 are surrounded. Examples of the radio wave absorber 26 include a resistive type radio wave absorber, a dielectric type radio wave absorber, or a magnetic type radio wave absorber.

[0025] Embodiment 2. Embodiment 2 describes a high-frequency dielectric heating device in which the thickness of the portion of the first electrode plate 1 and the second electrode plate 2 parallel to their respective surfaces is thinner than the thickness of the portion of the first electrode plate 1 and the second electrode plate 2 perpendicular to their respective surfaces.

[0026] Figure 8 is a perspective view showing a high-frequency dielectric heating device according to Embodiment 2. Figure 9 is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 2. The high-frequency dielectric heating device shown in Figures 8 and 9 comprises a first electrode plate 1, a second electrode plate 2, and a radio wave absorber 3. In Figures 8 and 9, the same reference numerals as in Figures 1 to 3 indicate the same or corresponding parts, so a detailed explanation is omitted. However, the thickness of the radio wave absorber 3 according to Embodiment 2 differs from the thickness of the radio wave absorber 3 according to Embodiment 1.

[0027] A high-frequency electric field is generated between the first electrode plate 1 and the second electrode plate 2, but no high-frequency electric field is generated on the side of the first electrode plate 1 opposite to the object being heated (the upper side of the first electrode plate 1 in Figure 9). Similarly, no high-frequency electric field is generated on the side of the second electrode plate 2 opposite to the object being heated (the lower side of the second electrode plate 2 in Figure 9). Therefore, radio wave leakage is less likely to occur on the surfaces of the first electrode plate 1 and the second electrode plate 2 that are parallel to each other (labeled "top surface" or "bottom surface" in Figure 9) compared to the surfaces of the first electrode plate 1 and the second electrode plate 2 that are perpendicular to each other (labeled "side surface" in Figure 9). In other words, radio wave leakage is more likely to occur on the side surface compared to the top surface and the bottom surface. For this reason, the side surface of the radio wave absorber 3 needs to be made thicker to prevent radio wave leakage.

[0028] The thickness of the top surface and bottom surface of the radio wave absorber 3 can be made thinner than the thickness of the sides of the radio wave absorber 3, and radio wave leakage is unlikely to occur. In other words, the thickness of the top surface and bottom surface of the radio wave absorber 3 can be made thinner than the thickness of the sides of the radio wave absorber 3. For this reason, in the high-frequency dielectric heating apparatus shown in Figures 8 and 9, the thickness of the top surface and bottom surface of the radio wave absorber 3 is made as thin as possible, for example, to the extent that radio wave leakage is below a standard value.

[0029] In the above embodiment 2, the high-frequency dielectric heating device shown in Figures 8 and 9 is configured such that the thickness of the portion of the radio wave absorber 3 parallel to the respective surfaces of the first electrode plate 1 and the second electrode plate 2 is thinner than the thickness of the portion of the radio wave absorber 3 perpendicular to the respective surfaces of the first electrode plate 1 and the second electrode plate 2. Therefore, the high-frequency dielectric heating device shown in Figure 8, etc., can suppress the generation of high-frequency electric fields other than between the first electrode plate 1 and the second electrode plate 2, and can reduce the amount of radio wave absorber 3 required compared to the high-frequency dielectric heating device shown in Figures 1 to 3, thereby reducing costs.

[0030] Embodiment 3. Embodiment 3 describes a high-frequency dielectric heating device in which the radio wave absorber 3 is positioned at least perpendicular to the planes of the first electrode plate 1 and the second electrode plate 2, either parallel to the planes of the first electrode plate 1 and the second electrode plate 2, or perpendicular to the planes of the first electrode plate 1 and the second electrode plate 2.

[0031] Figure 10 is a perspective view showing a high-frequency dielectric heating device according to Embodiment 3. Figure 11 is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 3. The high-frequency dielectric heating device shown in Figures 10 and 11 comprises a first electrode plate 1, a second electrode plate 2, and a radio wave absorber 3. In Figures 10 and 11, the same reference numerals as in Figures 1 to 3 indicate the same or corresponding parts, so a detailed explanation is omitted. However, in Embodiment 3, the radio wave absorber 3 is positioned above the first electrode plate 1 and to the side of the first electrode plate 1, but not below the second electrode plate 2.

[0032] The high-frequency electric field is generated in the vertical direction between the first electrode plate 1 and the second electrode plate 2, and no high-frequency electric field is generated on the side of the first electrode plate 1 opposite to the object being heated (the upper side of the first electrode plate 1 in Figure 11). Also, no high-frequency electric field is generated on the side of the second electrode plate 2 opposite to the object being heated (the lower side of the second electrode plate 2 in Figure 11). Therefore, even if radio wave absorbers 3 are not placed on the upper side of the first electrode plate 1 and the lower side of the second electrode plate 2, radio wave leakage is unlikely to occur.

[0033] Therefore, in the high-frequency dielectric heating apparatus shown in Figures 10 and 11, although the radio wave absorber 3 is placed on the side of the first electrode plate 1, the radio wave absorber 3 is not placed on the lower side of the second electrode plate 2. In the high-frequency dielectric heating apparatus shown in Figures 10 and 11, although the radio wave absorber 3 is also placed on the upper side of the first electrode plate 1, radio wave leakage can be almost completely prevented if the radio wave absorber 3 is placed on the side of the first electrode plate 1, so it is not necessary for the radio wave absorber 3 to be placed on the upper side of the first electrode plate 1.

[0034] In the above embodiment 3, the high-frequency dielectric heating device shown in Figures 10 and 11 is configured such that the radio wave absorber 3 is positioned at least perpendicular to the respective surfaces of the first electrode plate 1 and the second electrode plate 2, either parallel to the surfaces of the first electrode plate 1 and the second electrode plate 2, or perpendicular to the respective surfaces of the first electrode plate 1 and the second electrode plate 2. Therefore, the high-frequency dielectric heating device shown in Figure 10, etc., can suppress the generation of high-frequency electric fields other than between the first electrode plate 1 and the second electrode plate 2, and can reduce the amount of radio wave absorber 3 required compared to the high-frequency dielectric heating devices shown in Figures 1 to 3, thereby reducing costs.

[0035] Embodiment 4. Embodiment 4 describes a high-frequency dielectric heating device in which a heat insulating material is mixed into the radio wave absorber 4.

[0036] Figure 12 is a perspective view showing a high-frequency dielectric heating device according to Embodiment 4. Figure 13 is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 4. The high-frequency dielectric heating device shown in Figures 12 and 13 comprises a first electrode plate 1, a second electrode plate 2, and a radio wave absorber 4. In Figures 12 and 13, the same reference numerals as in Figures 1 to 3 indicate the same or corresponding parts, so a detailed explanation is omitted.

[0037] The radio wave absorber 4 is positioned to enclose the first electrode plate 1 and the second electrode plate 2. The radio wave absorber 4 acts to absorb or shield the high-frequency electric field generated between the first electrode plate 1 and the second electrode plate 2 so that the high-frequency electric field does not leak to the outside. The radio wave absorber 4 contains a heat insulating material. Therefore, the radio wave absorber 4 has a heat insulating effect.

[0038] The radio wave absorber 4 shown in Figures 12 and 13 corresponds to a radio wave absorber 3 in the high-frequency dielectric heating device according to Embodiment 1, with a heat insulating material mixed in. However, this is merely one example, and the radio wave absorber 4 in the high-frequency dielectric heating device according to Embodiment 4 may be a radio wave absorber 3 in the high-frequency dielectric heating device according to Embodiments 2 and 3, with a heat insulating material mixed in.

[0039] Next, the operation of the high-frequency dielectric heating apparatus shown in Figures 12 and 13 will be described. With the object to be heated placed between the first electrode plate 1 and the second electrode plate 2, a high-frequency voltage is applied to the first electrode plate 1 by a high-frequency power supply (not shown). For example, a frequency in the tens of MHz range is used for the high-frequency voltage. At this time, the potential of the second electrode plate 2 is the ground potential. When a high-frequency voltage is applied to the first electrode plate 1, a high-frequency electric field is generated between the first electrode plate 1 and the second electrode plate 2. Since the object to be heated is placed in the high-frequency electric field, dielectric loss occurs within the object to be heated. The object to be heated is heated by the occurrence of dielectric loss.

[0040] The high-frequency dielectric heating device shown in Figure 12, etc., includes a radio wave absorber 4 arranged to enclose a first electrode plate 1 and a second electrode plate 2. The radio wave absorber 4 acts to absorb or shield the high-frequency electric field so that the high-frequency electric field generated between the first electrode plate 1 and the second electrode plate 2 does not leak to the outside. Therefore, the radio wave absorber 4 acts as a shielding member, similar to a metal casing. However, since the radio wave absorber 4 is not a metal casing, a high-frequency electric field is not directly generated between the first electrode plate 1 and the radio wave absorber 4. As a result, the high-frequency electric field can be concentrated between the first electrode plate 1 and the second electrode plate 2, thereby increasing the heating efficiency of the high-frequency dielectric heating device. Since a high-frequency electric field is not directly generated between the first electrode plate 1 and the radio wave absorber 4, the heating efficiency of the high-frequency dielectric heating device does not decrease even if the distance between the first electrode plate 1 and the radio wave absorber 4 is shortened. Therefore, the high-frequency dielectric heating device can be miniaturized.

[0041] Furthermore, the radio wave absorber 4 contains an insulating material. This suppresses the transfer of thermal energy between the inside and outside of the high-frequency dielectric heating device. As a result, if the outside of the high-frequency dielectric heating device is, for example, the inside of a refrigerator or freezer, it is possible to reduce situations in which the object heated by the high-frequency dielectric heating device is cooled again, or in which the temperature inside the refrigerator or other area rises.

[0042] As the radio wave absorber 4 in which the heat insulating material is mixed, for example, the heat insulating material may be inserted inside the radio wave absorber 4, or one or more surfaces of the outer surface or the inner surface of the radio wave absorber 4 may be attached with the heat insulating material. The heat insulating material itself may or may not have a radio wave absorption effect.

[0043] In the above Embodiment 4, the high-frequency dielectric heating device is configured such that the heat insulating material is mixed in the radio wave absorber 4. Therefore, the high-frequency dielectric heating device can suppress the generation of a high-frequency electric field other than between the first electrode plate 1 and the second electrode plate 2, and can also suppress the transfer of thermal energy between the inside and the outside of the high-frequency dielectric heating device.

[0044] Embodiment 5. In Embodiment 5, a high-frequency dielectric heating device in which holes 5a are provided in a radio wave absorber 5 will be described.

[0045] FIG. 14 is a perspective view showing the high-frequency dielectric heating device according to Embodiment 5. FIG. 15 is a cross-sectional view showing the high-frequency dielectric heating device according to Embodiment 5. The high-frequency dielectric heating device shown in FIGS. 14 and 15 includes a first electrode plate 1, a second electrode plate 2, and a radio wave absorber 5. In FIGS. 14 and 15, the same reference numerals as those in FIGS. 1 to 3 denote the same or corresponding parts, and thus detailed description thereof will be omitted.

[0046] The radio wave absorber 5 is arranged so as to include the first electrode plate 1 and the second electrode plate 2. The radio wave absorber 5 acts to absorb or shield the high-frequency electric field so that the high-frequency electric field generated between the first electrode plate 1 and the second electrode plate 2 does not leak to the outside. The radio wave absorber 5 is provided with holes 5a. The diameter of the holes 5a is, for example, not more than half the wavelength of the frequency of the high-frequency voltage applied to the first electrode plate 1.

[0047] The radio wave absorber 5 shown in FIGS. 14 and 15 corresponds to the radio wave absorber 3 provided in the high-frequency dielectric heating device according to the first embodiment, but with holes. However, this is only an example, and the radio wave absorber 5 provided in the high-frequency dielectric heating device according to the fifth embodiment may be the radio wave absorber 3 provided in the high-frequency dielectric heating device according to the second or third embodiment, or the radio wave absorber 4 provided in the high-frequency dielectric heating device according to the fourth embodiment, with holes.

[0048] Next, the operation of the high-frequency dielectric heating device shown in FIGS. 14 and 15 will be described. With an object to be heated placed between the first electrode plate 1 and the second electrode plate 2, a high-frequency voltage is applied to the first electrode plate 1 by a high-frequency power supply not shown. As the frequency of the high-frequency voltage, for example, a frequency band in the dozens of MHz is used. At this time, the potential of the second electrode plate 2 is the ground potential. When a high-frequency voltage is applied to the first electrode plate 1, a high-frequency electric field is generated between the first electrode plate 1 and the second electrode plate 2. Since the object to be heated is placed in the high-frequency electric field, dielectric loss occurs in the object to be heated. The object to be heated is heated due to the occurrence of dielectric loss.

[0049] The high-frequency dielectric heating device shown in FIG. 14 etc. includes a radio wave absorber 5 arranged to encompass the first electrode plate 1 and the second electrode plate 2. The radio wave absorber 5 acts to absorb or shield the high-frequency electric field so that the high-frequency electric field generated between the first electrode plate 1 and the second electrode plate 2 does not leak to the outside. Therefore, the radio wave absorber 5 acts as a shielding member, similar to a metal housing. However, since the radio wave absorber 5 is not a metal housing, a high-frequency electric field does not directly occur between the first electrode plate 1 and the radio wave absorber 5. As a result, the high-frequency electric field can be concentrated between the first electrode plate 1 and the second electrode plate 2, thereby increasing the heating efficiency of the high-frequency dielectric heating device. Since a high-frequency electric field does not directly occur between the first electrode plate 1 and the radio wave absorber 5, even if the distance between the first electrode plate 1 and the radio wave absorber 5 is shortened, the heating efficiency of the high-frequency dielectric heating device does not decrease. Therefore, the high-frequency dielectric heating device can be miniaturized.

[0050] Furthermore, the radio wave absorber 5 is provided with holes 5a. The diameter of the holes 5a is less than half a wavelength of the frequency of the high-frequency voltage applied to the first electrode plate 1. Therefore, radio wave leakage through the holes 5a is almost nonexistent. A cable can be inserted into the holes 5a in the radio wave absorber 5. Therefore, the inside of the high-frequency dielectric heating device and the outside of the high-frequency dielectric heating device can be connected by a cable.

[0051] For example, the sensor part of a thermometer can be placed inside the high-frequency dielectric heating device, and the monitor part of the thermometer can be placed outside the high-frequency dielectric heating device. Then, by connecting the sensor part to one end of the cable inserted into hole 5a and the monitor part to the other end of the cable, the temperature inside the high-frequency dielectric heating device can be checked from outside the high-frequency dielectric heating device. For example, a thermal camera can be placed inside the high-frequency dielectric heating device, and the monitor part of the thermal camera can be placed outside the high-frequency dielectric heating device. Then, by connecting the thermal camera to one end of the cable inserted into hole 5a and the monitor part to the other end of the cable, the degree of heating of the object being heated can be checked from outside the high-frequency dielectric heating device.

[0052] For example, a high-frequency power supply for applying a high-frequency voltage to the first electrode plate 1 is placed outside the high-frequency dielectric heating device. Then, by connecting the first electrode plate 1 to one end of the cable inserted into the hole 5a and the high-frequency power supply to the other end of the cable, the high-frequency power supply located outside the high-frequency dielectric heating device can apply a high-frequency voltage to the first electrode plate 1. Because the radio wave absorber 5 has a hole 5a, there is some transfer of thermal energy between the inside and outside of the high-frequency dielectric heating device. For this reason, if it is more convenient to have some transfer of thermal energy between the inside and outside of the high-frequency dielectric heating device rather than completely suppressing the transfer of thermal energy, the high-frequency dielectric heating device shown in Figure 14, etc., is suitable.

[0053] In the above embodiment 5, the high-frequency dielectric heating device is configured such that the radio wave absorber 5 has holes 5a. Therefore, the high-frequency dielectric heating device can suppress the generation of high-frequency electric fields other than between the first electrode plate 1 and the second electrode plate 2, and can also monitor the internal state of the high-frequency dielectric heating device.

[0054] Embodiment 6. Embodiment 6 describes a high-frequency dielectric heating device in which the number of holes 6a in the radio wave absorber 6, or the size of the holes 6a, can be adjusted.

[0055] Figure 16 is a perspective view showing a high-frequency dielectric heating device according to Embodiment 6. Figure 17 is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 6. The high-frequency dielectric heating device shown in Figures 16 and 17 comprises a first electrode plate 1, a second electrode plate 2, and a radio wave absorber 6. In Figures 16 and 17, the same reference numerals as in Figures 1 to 3 indicate the same or corresponding parts, so a detailed explanation is omitted.

[0056] The radio wave absorber 6 is positioned to enclose the first electrode plate 1 and the second electrode plate 2. The radio wave absorber 6 acts to absorb or shield the high-frequency electric field generated between the first electrode plate 1 and the second electrode plate 2 so that the high-frequency electric field does not leak to the outside. The radio wave absorber 6 has a plurality of holes 6a. The diameter of the holes 6a is, for example, less than half a wavelength of the frequency of the high-frequency voltage applied to the first electrode plate 1. In addition, among the plurality of holes 6a, there are two or more holes with different diameters. Each hole 6a can be blocked with the radio wave absorber when not in use.

[0057] The radio wave absorber 6 shown in Figures 16 and 17 corresponds to a radio wave absorber 3 with holes provided in the high-frequency dielectric heating device according to Embodiment 1. However, this is merely one example, and the radio wave absorber 6 in the high-frequency dielectric heating device according to Embodiment 6 may be a radio wave absorber 3 in the high-frequency dielectric heating device according to Embodiments 2 and 3, or a radio wave absorber 4 in the high-frequency dielectric heating device according to Embodiment 4 with holes provided.

[0058] Next, the operation of the high-frequency dielectric heating apparatus shown in Figures 16 and 17 will be described. With the object to be heated placed between the first electrode plate 1 and the second electrode plate 2, a high-frequency voltage is applied to the first electrode plate 1 by a high-frequency power supply (not shown). For example, a frequency in the tens of MHz range is used for the high-frequency voltage. At this time, the potential of the second electrode plate 2 is the ground potential. When a high-frequency voltage is applied to the first electrode plate 1, a high-frequency electric field is generated between the first electrode plate 1 and the second electrode plate 2. Since the object to be heated is placed in the high-frequency electric field, dielectric loss occurs within the object to be heated. The object to be heated is heated by the occurrence of dielectric loss.

[0059] The high-frequency dielectric heating device shown in Figure 16, etc., includes a radio wave absorber 6 arranged to enclose a first electrode plate 1 and a second electrode plate 2. The radio wave absorber 6 acts to absorb or shield the high-frequency electric field so that the high-frequency electric field generated between the first electrode plate 1 and the second electrode plate 2 does not leak to the outside. Therefore, the radio wave absorber 6 acts as a shielding member, similar to a metal casing. However, since the radio wave absorber 6 is not a metal casing, a high-frequency electric field is not directly generated between the first electrode plate 1 and the radio wave absorber 6. As a result, the high-frequency electric field can be concentrated between the first electrode plate 1 and the second electrode plate 2, thereby increasing the heating efficiency of the high-frequency dielectric heating device. Since a high-frequency electric field is not directly generated between the first electrode plate 1 and the radio wave absorber 6, the heating efficiency of the high-frequency dielectric heating device does not decrease even if the distance between the first electrode plate 1 and the radio wave absorber 6 is shortened. For this reason, the high-frequency dielectric heating device can be miniaturized.

[0060] Furthermore, the radio wave absorber 6 is provided with multiple holes 6a. The diameter of each hole 6a is less than or equal to half a wavelength of the frequency of the high-frequency voltage applied to the first electrode plate 1. Therefore, radio wave leakage through each hole 6a is almost nonexistent. Cables can be inserted into the holes 6a in the radio wave absorber 6. Therefore, the inside of the high-frequency dielectric heating device and the outside of the high-frequency dielectric heating device can be connected by cables.

[0061] Furthermore, among the multiple holes 6a, there are two or more holes with different diameters. Each hole 6a can be sealed using an electromagnetic wave absorber when not in use. The airtightness of the high-frequency dielectric heating device can be adjusted by selecting the number of holes 6a to be sealed or by selecting which holes 6a to seal.

[0062] In the above embodiment 6, the high-frequency dielectric heating device is configured such that the number of holes 6a in the radio wave absorber 6, or the size of the holes 6a, can be adjusted. Therefore, the high-frequency dielectric heating device can suppress the generation of high-frequency electric fields other than between the first electrode plate 1 and the second electrode plate 2, and the airtightness of the high-frequency dielectric heating device can be adjusted.

[0063] Embodiment 7. Embodiment 7 describes a high-frequency dielectric heating device in which the holes 7a in the radio wave absorber 7 are holes for introducing gas into the inside of the device.

[0064] Figure 18 is a perspective view showing a high-frequency dielectric heating device according to Embodiment 7. Figure 19 is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 7. The high-frequency dielectric heating device shown in Figures 18 and 19 comprises a first electrode plate 1, a second electrode plate 2, and a radio wave absorber 7. In Figures 18 and 19, the same reference numerals as in Figures 1 to 3 indicate the same or corresponding parts, so a detailed explanation is omitted.

[0065] The radio wave absorber 7 is positioned to enclose the first electrode plate 1 and the second electrode plate 2. The radio wave absorber 7 acts to absorb or shield the high-frequency electric field so that the high-frequency electric field generated between the first electrode plate 1 and the second electrode plate 2 does not leak to the outside. The radio wave absorber 7 has one or more holes 7a. The diameter of the holes 7a is, for example, less than or equal to half a wavelength of the frequency of the high-frequency voltage applied to the first electrode plate 1. In addition, among the multiple holes 7a, there may be two or more holes with different diameters, or all of the multiple holes 7a may have the same diameter. Also, when not in use, each hole 7a may be able to be blocked with a radio wave absorber, similar to the holes 6a. A tube 8 is inserted into one of the one or more holes 7a. The tube 8 is inserted into one of the holes 7a and is a tube for introducing gas into the inside of the device.

[0066] Next, the operation of the high-frequency dielectric heating apparatus shown in Figures 18 and 19 will be described. With the object to be heated placed between the first electrode plate 1 and the second electrode plate 2, a high-frequency voltage is applied to the first electrode plate 1 by a high-frequency power supply (not shown). For example, a frequency in the tens of MHz range is used for the high-frequency voltage. At this time, the potential of the second electrode plate 2 is the ground potential. When a high-frequency voltage is applied to the first electrode plate 1, a high-frequency electric field is generated between the first electrode plate 1 and the second electrode plate 2. Since the object to be heated is placed in the high-frequency electric field, dielectric loss occurs within the object to be heated. The object to be heated is heated by the occurrence of dielectric loss.

[0067] The high-frequency dielectric heating device shown in Figure 18, etc., includes a radio wave absorber 7 arranged to enclose a first electrode plate 1 and a second electrode plate 2. The radio wave absorber 7 acts to absorb or shield the high-frequency electric field so that the high-frequency electric field generated between the first electrode plate 1 and the second electrode plate 2 does not leak to the outside. Therefore, the radio wave absorber 7 acts as a shielding member, similar to a metal casing. However, since the radio wave absorber 7 is not a metal casing, a high-frequency electric field is not directly generated between the first electrode plate 1 and the radio wave absorber 7. As a result, the high-frequency electric field can be concentrated between the first electrode plate 1 and the second electrode plate 2, thereby increasing the heating efficiency of the high-frequency dielectric heating device. Since a high-frequency electric field is not directly generated between the first electrode plate 1 and the radio wave absorber 7, the heating efficiency of the high-frequency dielectric heating device does not decrease even if the distance between the first electrode plate 1 and the radio wave absorber 7 is shortened. For this reason, the high-frequency dielectric heating device can be miniaturized.

[0068] Furthermore, the radio wave absorber 7 is provided with multiple holes 7a. The diameter of each hole 7a is less than or equal to half a wavelength of the frequency of the high-frequency voltage applied to the first electrode plate 1. Therefore, radio wave leakage through each hole 7a is almost nonexistent. Cables can be inserted into the holes 7a in the radio wave absorber 7. Therefore, the inside of the high-frequency dielectric heating device and the outside of the high-frequency dielectric heating device can be connected by cables. In addition, a tube 8 can be inserted into the holes 7a in the radio wave absorber 7. Therefore, gas can be introduced into the inside of the high-frequency dielectric heating device. If gas colder than the internal temperature of the high-frequency dielectric heating device is introduced into the inside of the high-frequency dielectric heating device, the internal temperature of the high-frequency dielectric heating device can be lowered. If gas warmer than the internal temperature of the high-frequency dielectric heating device is introduced into the inside of the high-frequency dielectric heating device, the internal temperature of the high-frequency dielectric heating device can be raised. If the humidity inside the high-frequency dielectric heating device is low, the humidity inside the high-frequency dielectric heating device can be increased by introducing water vapor into the inside of the high-frequency dielectric heating device. If the humidity inside a high-frequency dielectric heating device is high, the humidity inside the device can be reduced by introducing dry air into the device.

[0069] The high-frequency dielectric heating apparatus shown in Figure 18, etc., is shown in which a tube 8 is inserted into one or more of the holes 7a. However, this is only one example, and gas may be blown into the inside of the apparatus through any of the holes 7a without inserting a tube 8 into any of the holes 7a.

[0070] In the above embodiment 7, the high-frequency dielectric heating device is configured such that the holes 7a in the radio wave absorber 7 are holes for introducing gas into the inside of the device. Therefore, the high-frequency dielectric heating device can suppress the generation of high-frequency electric fields other than between the first electrode plate 1 and the second electrode plate 2, and can also adjust the temperature of the high-frequency dielectric heating device or the humidity of the high-frequency dielectric heating device.

[0071] Embodiment 8. Embodiment 8 describes a high-frequency dielectric heating device in which the holes 7a in the radio wave absorber 7 are holes for introducing gas into the device or holes for releasing gas from the device.

[0072] Figure 20 is a perspective view showing a high-frequency dielectric heating device according to Embodiment 8. Figure 21 is a cross-sectional view showing a high-frequency dielectric heating device according to Embodiment 8. The high-frequency dielectric heating device shown in Figures 20 and 21 comprises a first electrode plate 1, a second electrode plate 2, and a radio wave absorber 7. In Figures 20 and 21, the same reference numerals as in Figures 18 and 19 indicate the same or corresponding parts, so a detailed explanation is omitted. The tube 9 is inserted into one of the holes 7a and is a tube for releasing gas from inside the device.

[0073] A tube 8 can be inserted into the hole 7a provided in the radio wave absorber 7. This allows gas to be introduced into the high-frequency dielectric heating device. Introducing gas colder than the internal temperature of the high-frequency dielectric heating device can lower the internal temperature. Introducing gas warmer than the internal temperature of the high-frequency dielectric heating device can raise the internal temperature. If the humidity inside the high-frequency dielectric heating device is low, introducing water vapor can increase the humidity inside the device. If the humidity inside the high-frequency dielectric heating device is high, introducing dry air can lower the humidity inside the device.

[0074] Furthermore, a tube 9 can be inserted into the hole 7a in the radio wave absorber 7. This allows gas to flow out from inside the high-frequency dielectric heating device. By not only introducing gas into the high-frequency dielectric heating device but also releasing gas from inside the device, the gas flow can be controlled. This allows for efficient gas flow and control of the area to which the gas is applied.

[0075] In the above embodiment 8, the high-frequency dielectric heating device is configured such that the holes 7a in the radio wave absorber 7 are holes for introducing gas into the device or holes for releasing gas from the device. Therefore, the high-frequency dielectric heating device can suppress the generation of high-frequency electric fields other than between the first electrode plate 1 and the second electrode plate 2, and can also easily adjust the temperature or humidity of the high-frequency dielectric heating device.

[0076] Furthermore, this disclosure allows for free combination of each embodiment, modification of any component in each embodiment, or omission of any component in each embodiment.

[0077] The high-frequency dielectric heating device according to this invention comprises an electrode to which a high-frequency voltage is applied and a radio wave absorber arranged to enclose the electrode, and can suppress the generation of an electric field that does not contribute to heating the object to be heated, making it suitable for high-frequency dielectric heating devices.

[0078] 1 First electrode plate, 2 Second electrode plate, 3 Radio wave absorber, 4 Radio wave absorber, 5 Radio wave absorber, 5a hole, 6 Radio wave absorber, 6a hole, 7 Radio wave absorber, 7a hole, 8 Tube, 9 Tube. 11 Electrode, 12 Electrode plate, 13 Radio wave absorber, 21 First electrode plate, 22 Second electrode plate, 23 Third electrode plate, 24 Fourth electrode plate, 25 Fifth electrode plate, 26 Radio wave absorber.

Claims

1. A high-frequency dielectric heating device comprising an electrode to which a high-frequency voltage is applied, and a radio wave absorber arranged to enclose the electrode.

2. The high-frequency dielectric heating apparatus according to claim 1, characterized in that the thickness of the portion of the radio wave absorber parallel to the surface of the electrode is thinner than the thickness of the portion perpendicular to the surface of the electrode.

3. The high-frequency dielectric heating apparatus according to claim 1, characterized in that the radio wave absorber is positioned at least at the position perpendicular to the surface of the electrode, which is either parallel to the surface of the electrode or perpendicular to the surface of the electrode.

4. A high-frequency dielectric heating device comprising: a first electrode plate to which a high-frequency voltage is applied; a second electrode plate arranged to face the first electrode plate; and a radio wave absorber arranged to encompass the first electrode plate and the second electrode plate.

5. The high-frequency dielectric heating apparatus according to claim 4, characterized in that, in the radio wave absorber, the thickness of the portion of the first electrode plate and the second electrode plate parallel to their respective surfaces is thinner than the thickness of the portion of the first electrode plate and the second electrode plate perpendicular to their respective surfaces.

6. The high-frequency dielectric heating apparatus according to claim 4, characterized in that the radio wave absorber is positioned at least at the position perpendicular to the respective surfaces of the first electrode plate and the second electrode plate, or at the position perpendicular to the respective surfaces of the first electrode plate and the second electrode plate.

7. The high-frequency dielectric heating apparatus according to any one of claims 1 to 6, characterized in that the radio wave absorber contains an insulating material.

8. The high-frequency dielectric heating apparatus according to any one of claims 1 to 7, characterized in that the radio wave absorber is provided with holes.

9. The high-frequency dielectric heating apparatus according to claim 8, characterized in that the number of holes in the radio wave absorber, or the size of the holes, is adjustable.

10. The high-frequency dielectric heating apparatus according to claim 8 or 9, characterized in that the holes provided in the radio wave absorber are for introducing gas into the inside of the apparatus.

11. The high-frequency dielectric heating apparatus according to claim 8 or 9, characterized in that the holes provided in the radio wave absorber are holes for introducing gas into the apparatus or holes for releasing gas from the apparatus.

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