30 and the second electrode 40 may be deteriorated. On the other hand, since the generation of the electric field that does not contribute to the heating of the object OH to be heated can be prevented by reducing the distance between the one end of the coil 50 and the first electrode 30, the intensity of the electric field generated from the first electrode 30 and the second electrode 40 can be effectively increased. In other embodiments, for example, the first electrode 30 may be formed in a meander shape to cause the first electrode 30 to exhibit the same function as the coil 50.

FIG. 3 is a cross-sectional view of the first electrode 30 taken along a line III-III in FIG. 2. FIG. 4 is a cross-sectional view of the first electrode 30 taken along a line IV-IV in FIG. 2. As shown in FIGS. 2 and 3, the first electrode 30 has an arc shape protruding in the −Z direction when viewed along the X direction. Similarly, as shown in FIGS. 2 and 4, the first electrode 30 has an arc shape protruding in the −Z direction when viewed along the Y direction. Therefore, an end portion of the first electrode 30 in the longitudinal direction and an end portion of the first electrode 30 in the lateral direction are positioned in the +Z direction with respect to a central portion of the first electrode 30.

The electrode unit 20 preferably has a shape that can prevent a variation in the electric field intensity within the range of the vicinity electromagnetic field. For example, as described with reference to FIGS. 2 to 4, the first electrode 30 in the present embodiment has a rounded shape as a whole with few sharp corners. Accordingly, for example, as compared with a case where the end portion of the first electrode 30 or the like has an angular shape, the concentration of the electric field on a specific portion such as an end portion of the first electrode 30 can be prevented. In the present embodiment, since the first electrode 30 has a boat shape, a distance between the end portion of the first electrode 30 and the object OH to be heated in the Z direction is longer than a distance between the central portion of the first electrode 30 and the object OH to be heated in the Z direction. A curvature radius r of the end portion of the first electrode 30 in the lateral direction shown in FIG. 2 is smaller than a curvature radius R of the end portion of the first electrode 30 in the longitudinal direction shown in FIG. 4. Accordingly, the concentration of the electric field on the end portion of the first electrode 30, in particular, the concentration of the electric field on the end portion of the first electrode 30 in the longitudinal direction can be further prevented. In this way, by preventing the variation in the electric field intensity within the range of the vicinity electromagnetic field, a variation in the electric field intensity within the plane of the object OH to be heated can be prevented, and the heating unevenness of the object OH to be heated can be prevented.

The case unit 300 shown in FIG. 1 blocks a radiation wave from the electrode unit 20 accommodated therein. The radiation wave from the electrode unit 20 refers to an electromagnetic wave radiated from the electrode unit 20. The radiation wave includes, for example, a far electromagnetic field radiated from the first electrode 30 and the second electrode 40 described above and an electromagnetic field generated by the coil 50.

The “blocking of the radiation wave” by the case unit 300 refers to setting, by the case unit 300, an intensity of the electromagnetic field radiated from the electrode unit 20 to the outside of the case unit 300 to a predetermined reference value or less. The reference value is determined based on a regulation value defined in guidelines or the like related to exposure limitation of an electromagnetic field in each country or region. Such guidelines include, for example, radio wave protection guidelines in Japan and guidelines defined by International Committee on Non-Ionization Radiation Protection (ICNIRP). For example, in the guidelines of ICNIRP, an exposure limit value of a magnetic field at a frequency of 40.68 MHz is 0.16 A/m in the case of an occupational exposure and 0.073 A/m in the case of a public exposure. These exposure limit values in the guidelines of ICNIRP are all an average value for 6 minutes.

FIG. 5 is a perspective diagram showing a schematic configuration of the first cover unit 310 provided in the case unit 300. The case unit 300 blocks the radiation wave by generating an electromagnetic field due to an eddy current generated in the first cover unit 310 when a radiation wave is radiated from the electrode unit 20. The electromagnetic field weakens the radiation wave from the first cover unit 310. The magnitude of the eddy current generated in the first cover unit 310 when the radiation wave is radiated is proportional to one-half power of an electric conductivity and one-half power of an absolute magnetic permeability of a material constituting the first cover unit 310. Therefore, the material constituting the first cover unit 310 is preferably a material having a high electric conductivity and a high absolute magnetic permeability. The first cover unit 310 in the present embodiment is made of zinc having a relatively high electric conductivity among metal materials.

The first cover unit 310 in the present embodiment has a rectangular parallelepiped outer shape. The first cover unit 310 includes the first insertion port 312, the first feed-out port 314, and a plurality of first opening portions 316. The first insertion port 312 is an opening portion for inserting the object OH to be heated into the first cover unit 310. The first feed-out port 314 is an opening portion for feeding the object OH to be heated in the first cover unit 310 out of the first cover unit 310. In the present embodiment, the first insertion port 312 is provided in a surface of the first cover unit 310 on a +Y direction side, and the first feed-out port 314 is provided in a surface of the first cover unit 310 on a −Y direction side. That is, the first insertion port 312 and the first feed-out port 314 are disposed to face each other in the Y direction with the electrode unit 20 interposed therebetween. The first insertion port 312 and the first feed-out port 314 each have a rectangular opening shape with the X direction as a longitudinal direction and the Z direction as a lateral direction similarly.

The first opening portion 316 is an opening portion that is different from the first insertion port 312 and the first feed-out port 314. More specifically, in the present embodiment, each surface of the first cover unit 310 is formed of a wire mesh obtained by vertically and horizontally plain-weaving a wire material made of zinc, and opening portions separated by the wire material correspond to the first opening portions 316. Accordingly, in the present embodiment, the plurality of first opening portions 316 each having a square opening shape are formed on each surface of the first cover unit 310 so as to be arranged vertically and horizontally in a direction along the surface. In FIG. 5, among the first opening portions 316, only the first opening portions 316 provided in a surface of the first cover unit 310 on a +X direction side are shown, and the first opening portions 316 provided in other surfaces are omitted.

In the present embodiment, an opening area of one first opening portion 316 is smaller than an opening area of the first insertion port 312 and an opening area of the first feed-out port 314. On the other hand, a sum of opening areas of the first opening portions 316 is larger than the opening area of the first insertion port 312 and the opening area of the first feed-out port 314. An opening diameter of the first opening portion 316 is smaller than an opening diameter of the first insertion port 312 and an opening diameter of the first feed-out port 314. In the present description, the opening diameter refers to a maximum length of the opening. For example, in the present embodiment, a length of a diagonal line of the first opening portion 316 corresponds to the opening diameter of the first opening portion 316. In the present embodiment, a length of each side of the first opening portion 316 is shorter than a length of either side of the first insertion port 312 and the first feed-out port 314.

In other embodiments, each surface of the first cover unit 310 may be formed of, for example, a wire mesh obtained by twill weaving a wire material, an expanded metal, or a punched metal. An opening shape of the first opening portion 316 or the like may not be rectangular, and may be, for example, a circular shape, an oval shape, a rhombic shape, or other polygonal shapes. When the opening shape of the first opening portion 316 or the like is, for example, a circular shape, the diameter thereof corresponds to the opening diameter of the first opening portion 316 or the like. The first opening portion 316 may not be provided in all surfaces of the first cover unit 310, and the first opening portion 316 may be provided in only a part of surfaces of the first cover unit 310.

The opening shape, the opening area, the opening diameter, the number, the position, and the like of the first opening portion 316 are preferably determined such that when a radiation wave is radiated from the electrode unit 20, an eddy current is generated in the first cover unit 310 to an extent that an electromagnetic field that weakens the radiation wave is generated. The opening diameter of the first opening portion 316 is preferably set to, for example, one-tenth or less of the wavelength λ₀in order to prevent the radiation wave from leaking to the outside of the first cover unit 310 through the first opening portions 316. In the present embodiment, as described above, since the radiation of the far electromagnetic field from the first electrode 30 and the second electrode 40 can be prevented, the opening shape of the first opening portion 316 or the like can be determined by taking this into account. In this case, the weight of the case unit 300 can be reduced by increasing, for example, the opening area, the opening diameter, and the number of the first opening portions 316 within a range where the radiation wave can be prevented from leaking to the outside of the first cover unit 310 through the first opening portions 316.

As shown in FIG. 5, a first edge portion 317 is disposed around the first insertion port 312. The first edge portion 317 is made of an electrically insulating magnetic material, and continuously surrounds the first insertion port 312. In the present embodiment, a Ni—Zn-based soft ferrite material formed in a sheet shape is used as the first edge portion 317. The first edge portion 317 is fixed to an outer surface of the first cover unit 310 via an adhesive so as to surround the first insertion port 312 without interruption. Hereinafter, the first edge portion 317 may be simply referred to as an edge portion. In FIG. 1 described above, the first edge portion 317 is omitted.

In the present embodiment, the first edge portion 317 includes a first portion 318 and a second portion 319. The second portion 319 is a portion of the first edge portion 317 provided at a position corresponding to the electrode unit 20 in the X direction, and has a width larger than that of the first portion 318. The “width” of the edge portion refers to a dimension in a direction perpendicular to a direction along the periphery of the first insertion port 312. More specifically, the second portion 319 is provided so as to sandwich, in the Z direction, a portion of the first insertion port 312 provided in the position corresponding to the electrode unit 20 in the X direction. The first portion 318 and the second portion 319 may be separate bodies or may be integrally formed as long as they are provided in a continuous manner with each other.

The first insertion port 312 may act as a pseudo slot antenna depending on the opening diameter, the opening area, and the like thereof, and an electromagnetic field may be radiated to the outside of the first cover unit 310 through the first insertion port 312. More specifically, the eddy current generated in the first cover unit 310 by the far electromagnetic field radiated from the electrode unit 20 generates an electric field in the first insertion port 312, and thus the first insertion port 312 may act as a pseudo slot antenna. In the present embodiment, as described above, since the first edge portion 317 made of a magnetic material is disposed to surround the first insertion port 312, generation of the eddy current around the first insertion port 312 is prevented. In addition, since the first edge portion 317 has electrical insulation, the eddy current generated due to the far electromagnetic field radiated from the electrode unit 20 is less likely to be generated in the first edge portion 317 itself. Accordingly, the first insertion port 312 can be prevented from acting as a pseudo slot antenna, and the electromagnetic field radiated from the first insertion port 312 to the outside of the first cover unit 310 can be prevented. In the present embodiment, since the first edge portion 317 includes the second portion 319, the generation of the eddy current in a portion around the first insertion port 312, the portion having a shorter distance from the electrode unit 20, is further prevented, and the radiation of the electromagnetic field to the outside of the first cover unit 310 can be more effectively prevented.

In the present embodiment, although not shown, the first edge portion 317 is similarly provided around the first feed-out port 314 so as to continuously surround the first feed-out port 314. The effect of the first edge portion 317 provided around the first feed-out port 314 is the same as the effect of the first edge portion 317 provided around the first insertion port 312 described above.

According to the first embodiment described above, the metal first cover unit 310 that surrounds the electrode unit 20 includes the plurality of first opening portions 316 that are different from the first insertion port 312 and the first feed-out port 314. Accordingly, the vapor generated by heating of the object OH to be heated in the first cover unit 310 can be moved to the outside of the first cover unit 310 through the first opening portions 316, and thus the retention of the vapor in the first cover unit 310 can be prevented. Therefore, it is possible to prevent the liquid generated by condensation of the retained vapor from contaminating the object OH to be heated, and to prevent a decrease in drying efficiency when heating and drying the object OH to be heated. In addition, since the first cover unit 310 includes the first opening portions 316, the first cover unit 310 is lighter as compared with a case where the first cover unit 310 does not include the first opening portions 316. Therefore, the overall weight of the dielectric heating apparatus 100 can be reduced.

According to the present embodiment, the first edge portion 317 that is made of an electrically insulating magnetic material and continuously surrounds at least one of the first insertion port 312 and the first feed-out port 314 is provided. Therefore, the electromagnetic field radiated from the first insertion port 312 or the first feed-out port 314 to the outside of the first cover unit 310 can be prevented by the first edge portion 317.

According to the present embodiment, the first cover unit 310 is made of zinc. Therefore, the weight of the first cover unit 310 can be reduced as compared with a case where the first cover unit 310 is made of, for example, carbon steel or copper. In addition, for example, the strength of the first cover unit 310 can be further increased as compared with a case where the first cover unit 310 is made of aluminum.

B. Second Embodiment

FIG. 6 is a schematic diagram showing a schematic configuration of a dielectric heating apparatus 100b according to a second embodiment. Unlike the first embodiment, a case unit 300b in the present embodiment includes the first cover unit 310 and a metal second cover unit 320 that surrounds the first cover unit 310. Portions of the configuration of the dielectric heating apparatus 100b, which are not particularly described, are the same as those of the first embodiment.

FIG. 7 is a perspective diagram showing a schematic configuration of the second cover unit 320. The second cover unit 320 in the present embodiment is made of zinc and has a rectangular parallelepiped shape. External dimensions of the second cover unit 320 in the X, Y, and Z directions are larger than external dimensions of the first cover unit 310 in the X, Y, and Z directions.

As shown in FIGS. 6 and 7, the second cover unit 320 includes a second insertion port 322, a second feed-out port 324, and a plurality of second opening portions 326. In FIG. 6, the second opening portion 326 is omitted. The second insertion port 322 is an opening portion for inserting the object OH to be heated into the second cover unit 320. The second feed-out port 324 is an opening portion for feeding the object OH to be heated in the second cover unit 320 out of the second cover unit 320. As shown in FIG. 6, the second insertion port 322 is provided in a surface of the second cover unit 320 on a +Y direction side, and the second feed-out port 324 is provided in a surface of the second cover unit 320 on a −Y direction side. More specifically, the second insertion port 322 is provided in a position corresponding to the first insertion port 312, and the second feed-out port 324 is provided in a position corresponding to the first feed-out port 314. In the present embodiment, the second insertion port 322 and the second feed-out port 324 have an opening shape and dimensions the same as those of the first insertion port 312 and the second feed-out port 324, respectively.

In the present embodiment, the object OH to be heated is first inserted into the second cover unit 320 through the second insertion port 322. Thereby, the object OH to be heated is inserted into the case unit 300b. Next, the object OH to be heated is inserted into the first cover unit 310 through the first insertion port 312. Then, the object OH to be heated is heated by the electrode unit 20 in the first cover unit 310, and then is fed out of the first cover unit 310 through the first feed-out port 314. Next, the object OH to be heated is fed out of the second cover unit 320 through the second feed-out port 324. Thereby, the object OH to be heated is fed out of the case unit 300b.

The second opening portion 326 shown in FIG. 7 is an opening portion that is different from the second insertion port 322 and the second feed-out port 324. More specifically, similar to each surface of the first cover unit 310, each surface of the second cover unit 320 is formed of a wire mesh obtained by vertically and horizontally plain-weaving a wire material made of zinc, and opening portions separated by the wire material corresponds to the second opening portions 326. The second opening portion 326 in the present embodiment has an opening shape and dimensions same as those of the first opening portion 316. As described above, since the external dimensions of the second cover unit 320 are larger than the external dimensions of the first cover unit 310, a sum of opening areas of the second opening portions 326 is larger than a sum of opening areas of the first opening portions 316. In FIG. 7, among the second opening portions 326, only the second opening portions 326 provided in a surface of the second cover unit 320 on the +X direction side are shown, and the second opening portions 326 provided in other surfaces are omitted.

As shown in FIG. 7, a second edge portion 327 is disposed around the second insertion port 322. The second edge portion 327 is made of an electrically insulating magnetic material, and continuously surrounds the second insertion port 322. In the present embodiment, a Ni—Zn-based soft ferrite material formed in a sheet shape is used as the second edge portion 327, similar to the first edge portion 317. The second edge portion 327 is fixed to an outer surface of the second cover unit 320 via an adhesive so as to surround the second insertion port 322 without interruption.

In the present embodiment, the second edge portion 327 includes a third portion 328 and a fourth portion 329. The fourth portion 329 is a portion of the second edge portion 327 provided at a position corresponding to the electrode unit 20 in the X direction, and has a width larger than that of the third portion 328. The configuration of the third portion 328 is the same as the configuration of the first portion 318 of the first edge portion 317, and the configuration of the fourth portion 329 is the same as the configuration of the second portion 319 of the first edge portion 317. The second edge portion 327 prevents radiation of an electromagnetic field to the outside of the second cover unit 320, similar to the first edge portion 317 preventing the radiation of the electromagnetic field to the outside of the first cover unit 310. As shown in FIG. 6, the second edge portion 327 is also provided around the second feed-out port 324 so as to continuously surround the second feed-out port 324.

According to the second embodiment described above, the metal second cover unit 320 that surrounds the first cover unit 310 is provided, and the second cover unit 320 includes the plurality of second opening portions 326 that are different from the second insertion port 322 and the second feed-out port 324. Accordingly, a radiation wave from the electrode unit 20 can be prevented not only by the first cover unit 310 but also by the second cover unit 320, so that a radiation wave having a higher intensity can be blocked by the case unit 300b as a whole as compared with a case without the second cover unit 320. Therefore, for example, a high voltage can be applied to the electrode unit 20, and the heating efficiency of the object OH to be heated can be further increased.

According to the present embodiment, the sum of the opening areas of the second opening portions 326 is larger than the sum of the opening areas of the first opening portions 316. Accordingly, as compared with a case where the sum of the opening areas of the second opening portions 326 is equal to or smaller than the sum of the opening areas of the first opening portions 316, the retention of a vapor in the second cover unit 320 can be further prevented and the weight of the second cover unit 320 can be reduced.

In other embodiments, the second insertion port 322 and the second feed-out port 324 may not be provided in positions corresponding to the first insertion port 312 and the first feed-out port 314. For example, when the object OH to be heated that is inserted into the first cover unit 310 in the −Y direction through the second insertion port 322 and the first insertion port 312 is fed out of the first cover unit 310 through the first feed-out port 314, and then is fed out of the second cover unit 320 by changing the direction of the object OH to be heated so as to be folded back in the second cover unit 320 in the +Y direction, the second feed-out port 324 may be provided in a surface of the second cover unit 320 facing the first insertion port 312. That is, in this case, both the second insertion port 322 and the second feed-out port 324 may be provided in the surface of the second cover unit 320 on the +Y direction side.

C. Third Embodiment

FIG. 8 is a perspective diagram showing a schematic configuration of a dielectric heating apparatus 100c according to a third embodiment. Unlike the first embodiment, the dielectric heating apparatus 100c includes a plurality of electrode units 20. Portions of the configuration of the dielectric heating apparatus 100c, which are not particularly described, are the same as those of the first embodiment. In FIG. 8, the first edge portion 317 is omitted as in FIG. 1 described in the first embodiment.

The plurality of electrode units 20 are arranged side by side in a third direction intersecting the first direction and orthogonal to the second direction. The third direction includes both one side direction and an opposite direction along the same axis, and is a direction along the X-axis in the present embodiment.

The dielectric heating apparatus 100c in the present embodiment includes two columns of unit columns UC. The unit columns UC each include four electrode units 20 arranged side by side in the X direction. That is, the dielectric heating apparatus 100c includes a total of eight electrode units 20. The unit columns UC are arranged side by side in the Y direction.

As shown in FIG. 8, in the present embodiment, eight substrates 110 are provided corresponding to the respective electrode units 20. In other embodiments, for example, the substrate 110 may be provided in common for the plurality of electrode units 20, for example, only one substrate 110 may be provided for all of the electrode units 20.

In the present embodiment, alternating current voltages whose phases are inverted by 180° are applied to the electrode units 20 adjacent to each other in the X direction and the Y direction. Accordingly, radiation waves from the adjacent electrode units 20 can be weakened to each other, so that the radiation waves can be blocked by the case unit 300 and the heating efficiency of the object OH to be heated can be further increased, for example, even when a higher voltage is applied to each electrode unit 20. In other embodiments, for example, alternating current voltages having inverted phases may be applied to the electrode units 20 adjacent to each other in the X direction, and alternating current voltages having the same phase may be applied to the electrode units 20 adjacent to each other in the Y direction. Even in this case, the radiation waves from the electrode units 20 to which the alternating current voltages having inverted phases are applied can also be mutually weakened.

According to the third embodiment described above, the plurality of electrode units 20 are provided, and the plurality of electrode units 20 are arranged side by side in the X direction. Therefore, for example, even in the case of heating the object OH to be heated that has a larger dimension in the X direction, the object OH to be heated can be efficiently heated by the plurality of electrode units 20 while being conveyed in the −Y direction. In addition, for example, even when the voltage applied every one of the electrode units 20 is reduced, a sufficient output to heat the object OH to be heated can be easily obtained with the plurality of electrode units 20 as a whole. Therefore, by reducing the voltage applied every one of the electrode units 20, Joule heat generated by parasitic resistance of the electrode unit 20 can be prevented, and concentration of an electric field when an alternating current voltage is applied to the electrode unit 20 can be prevented.

In other embodiments, the number of unit columns UC may not be two, and may be, for example, one or three or more. The number of electrode units 20 provided in one unit column UC may not be four, and may be, for example, two, three, or five or more. In addition, the number of electrode units 20 provided in each unit column UC may be different from each other.

D. Fourth Embodiment

FIG. 9 is a schematic diagram showing a dielectric heating apparatus 100d according to a fourth embodiment. Unlike the first embodiment, the dielectric heating apparatus 100d includes an airflow generation unit 120 that generates an airflow in the first cover unit 310. Portions of the configuration of the dielectric heating apparatus 100d, which are not particularly described, are the same as those of the first embodiment. In FIG. 9, the first opening portion 316 provided in the first cover unit 310 is omitted.

The airflow generation unit 120 in the present embodiment includes a blower fan. The airflow generation unit 120 is disposed in the +Y direction of the first cover unit 310, and blows air toward the first cover unit 310. Accordingly, a gas sent from the airflow generation unit 120 is supplied into the first cover unit 310 through the first opening portions 316 shown in FIG. 5, and an airflow is generated in the first cover unit 310. In particular, in the present embodiment, since the first opening portions 316 are provided in each surface of the first cover unit 310, the inside and outside of the first cover unit 310 can be more efficiently ventilated by the airflow generated in the first cover unit 310. In other embodiments, the airflow generation unit 120 may include a suction fan, a duct, or the like for sucking and discharging the gas in the first cover unit 310 to the outside. In addition, the airflow generation unit 120 may not be disposed in the +Y direction of the first cover unit 310, and may be disposed, for example, in an upper portion of the first cover unit 310.

According to the fourth embodiment described above, the dielectric heating apparatus 100d includes the airflow generation unit 120 that generates an airflow in the first cover unit 310. Therefore, by generating the airflow in the first cover unit 310 by the airflow generation unit 120, the inside and outside of the first cover unit 310 can be efficiently ventilated. Therefore, it is possible to further prevent a vapor generated by heating of the object OH to be heated from retaining in the first cover unit 310.

E. Fifth Embodiment

FIG. 10 is a perspective diagram showing a schematic configuration of a dielectric heating apparatus 100e according to a fifth embodiment. FIG. 11 is a schematic diagram showing the schematic configuration of the dielectric heating apparatus 100e according to the fifth embodiment. Unlike the first embodiment, the dielectric heating apparatus 100e includes a movement unit 130. In addition, a case unit 300c in the present embodiment includes the first cover unit 310 and a third cover unit 330. Portions of the configuration of the dielectric heating apparatus 100e, which are not particularly described, are the same as those of the first embodiment. In FIG. 10, the first edge portion 317 is omitted as in FIG. 1 described in the first embodiment. In FIG. 11, the first opening portion 316 is omitted.

The third cover unit 330 is disposed in the first cover unit 310. The third cover unit 330 is a metal member that covers the electrode unit 20 and faces, in the −Z direction, the object OH to be heated that is conveyed in the −Y direction. The third cover unit 330 has a third opening portion 335 that is opened toward the object OH to be heated in the −Z direction. The third opening portion 335 surrounds at least the first electrode 30 and the second electrode 40 when viewed along the Z direction. In the present embodiment, the third cover unit 330 has a rectangular parallelepiped outer shape as a whole, and the third opening portion 335 is formed as an opening portion having a rectangular opening shape over the entire lower surface of the third cover unit 330. The third cover unit 330 in the present embodiment is made of zinc, similar to the first cover unit 310. Outer dimensions of the third cover unit 330 in the X, Y, and Z directions are smaller than outer dimensions of the first cover unit 310 in the X, Y, and Z directions. In FIG. 11, in order to facilitate understanding of the configuration, the third cover unit 330 and the substrate 110 are separated from each other, but actually, the lower end of the third cover unit 330 and the upper surface of the substrate 110 are in contact with each other.

FIG. 12 is a perspective diagram showing a schematic configuration of the third cover unit 330. As shown in FIG. 12, the third cover unit 330 has a plurality of fourth opening portions 336. The fourth opening portion 336 is an opening portion that is different from the third opening portion 335. More specifically, similar to each surface of the first cover unit 310, each surface of the third cover unit 330 except for the lower surface is formed of a wire mesh obtained by vertically and horizontally plain-weaving a wire material made of zinc, and opening portions separated by the wire material corresponds to the fourth opening portions 336. The fourth opening portion 336 in the present embodiment has dimensions and a shape the same as those of the first opening portion 316. That is, in the present embodiment, an opening area of the fourth opening portion 336 is smaller than an opening area of the first insertion port 312 and an opening area of the first feed-out port 314. An opening diameter of the fourth opening portion 336 is smaller than an opening diameter of the first insertion port 312 and an opening diameter of the first feed-out port 314. In FIG. 12, among the fourth opening portions 336, only the fourth opening portions 336 provided in a surface of the third cover unit 330 on the +X direction side are shown, and the fourth opening portions 336 provided in other surfaces are omitted. In FIGS. 10 and 11 described above, the fourth opening portion 336 is omitted.

The movement unit 130 shown in FIGS. 10 and 11 is configured to reciprocate the electrode unit 20 in a fourth direction. The fourth direction is a direction intersecting the first direction and orthogonal to the second direction. The fourth direction includes both one side direction and an opposite direction along the same axis, and is a direction along the X-axis in the present embodiment. The third cover unit 330 is configured to move in the X direction together with the electrode unit 20 by the movement unit 130.

The movement unit 130 includes, for example, a support portion that supports the electrode unit 20 and the third cover unit 330, and a drive unit that moves the support portion along the X direction. The support portion may directly support both the electrode unit 20 and the third cover unit 330, or may directly support only the third cover unit 330 when the third cover unit 330 is fixed to the electrode unit 20, for example. For example, the drive unit may include a belt mechanism having an endless belt and a pulley, or may include a ball screw mechanism having a ball screw and a motor.

According to the fifth embodiment described above, the dielectric heating apparatus 100e includes the movement unit 130 configured to reciprocate the electrode unit 20 in the X direction. Therefore, for example, even in the case of heating the object OH to be heated that has a larger dimension in the X direction, the object OH to be heated can be efficiently heated by the electrode unit 20, that is reciprocated in the X direction, while being conveyed in the −Y direction. Therefore, for example, even when a plurality of electrode units 20 are not provided, the object OH to be heated that has a larger dimension in the X direction can be efficiently heated.

Further, in the present embodiment, the metal third cover unit 330 that is disposed in the first cover unit 310, covers the electrode unit 20, and faces, in the −Z direction, the object OH to be heated that is conveyed in the −Y direction is provided. The third cover unit 330 is configured to reciprocate in the X direction together with the electrode unit 20, and includes the third opening portion 335 that is opened toward the object OH to be heated in the −Z direction and surrounds the first electrode 30 and the second electrode 40 when viewed along the Z direction, and the plurality of fourth opening portions 336 that are different from the third opening portion 335. Accordingly, a radiation wave from the electrode unit 20 can be prevented not only by the first cover unit 310 but also by the third cover unit 330, so that a radiation wave having a higher intensity can be blocked by the case unit 300 as a whole as compared with a case where the third cover unit 330 is not provided. In addition, since the third cover unit 330 is configured to reciprocate in the X direction together with the electrode unit 20, weight reduction and cost reduction of the dielectric heating apparatus 100e can be implemented by setting the dimension of the third cover unit 330 in the X direction to a dimension sufficient to accommodate the electrode unit 20, for example, as compared with a case where the electrode unit 20 is accommodated in a metal cover having a dimension corresponding to a movement range of the electrode unit 20. Further, since the third cover unit 330 is provided with the plurality of fourth opening portions 336, it is possible to prevent a vapor generated by the heating of the object OH to be heated from retaining in the third cover unit 330.

F. Sixth Embodiment

FIG. 13 is a perspective diagram showing a schematic configuration of a dielectric heating apparatus 100f according to a sixth embodiment. FIG. 14 is a schematic diagram showing the schematic configuration of the dielectric heating apparatus 100f according to the sixth embodiment. Unlike the first embodiment, the dielectric heating apparatus 100f does not include the case unit 300, i.e., the first cover unit 310, but includes a movement unit 130b, a fourth cover unit 340, and a facing unit 150. Portions of the configuration of the dielectric heating apparatus 100f, which are not particularly described, are the same as those of the first embodiment.

The fourth cover unit 340 is a metal member that covers the electrode unit 20 and faces, in the −Z direction, the object OH to be heated that is conveyed in the −Y direction. The fourth cover unit 340 has a fifth opening portion 345 that is opened toward the object OH to be heated in the −Z direction. The fifth opening portion 345 surrounds at least the first electrode 30 and the second electrode 40 when viewed along the Z direction. In the present embodiment, the fourth cover unit 340 has a rectangular parallelepiped outer shape as a whole, and the fifth opening portion 345 is formed as an opening portion having a rectangular opening shape extending over the entire lower surface of the fourth cover unit 340. The fourth cover unit 340 may be made of, for example, zinc, similar to the first cover unit 310 described in the first embodiment or the like, or may be made of carbon steel, aluminum, stainless steel, copper, alloys of various metals, or the like. In addition, all or a part of surfaces of the fourth cover unit 340 may be formed of, for example, a wire mesh, and have a plurality of opening portions, similar to the first cover unit 310.

The movement unit 130b is configured to reciprocate the electrode unit 20 in a fifth direction. The fifth direction is a direction intersecting the first direction and orthogonal to the second direction. The fifth direction includes both one side direction and an opposite direction along the same axis, and is a direction along the X-axis in the present embodiment. The fourth cover unit 340 is configured to move in the X direction together with the electrode unit 20 by the movement unit 130b. The movement unit 130b includes a support portion that supports the electrode unit 20 and the fourth cover unit 340, and a drive unit that moves the support portion along the X direction. The support portion and the drive unit are configured in the same manner as, for example, the support portion and the drive unit of the movement unit 130 described in the fifth embodiment.

The facing unit 150 is a metal member that faces, in the Z direction, the first electrode 30 and the second electrode 40 with the object OH to be heated interposed therebetween. The facing unit 150 in the present embodiment has a recessed portion 151 that is opened in the +Z direction, which is an opposite direction with respect to the −Z direction. As shown in FIG. 14, a lower end 341 of the fourth cover unit 340 is disposed in the opening of the recessed portion 151. It can also be said that the lower end 341 of the fourth cover unit 340 is located below an upper end 152 of an inner wall portion of the opening of the recessed portion 151. The opening of the recessed portion 151 in the present embodiment has a dimension larger than the movement range of the fourth cover unit 340 in the X direction. Accordingly, the movement unit 130b can reciprocate the fourth cover unit 340 and the electrode unit 20 in the X direction while keeping the lower end 341 of the fourth cover unit 340 in the recessed portion 151.

According to the sixth embodiment described above, the dielectric heating apparatus 100f includes the movement unit 130b configured to reciprocate the electrode unit 20 in the X direction, the metal fourth cover unit 340 that covers the electrode unit 20, and faces, in the −Z direction, the object OH to be heated that is conveyed in the −Y direction, and the metal facing unit 150 that faces, in the Z direction, the first electrode 30 and the second electrode 40 with the object OH to be heated that is conveyed in the −Y direction interposed therebetween. The fourth cover unit 340 is configured to reciprocate in the X direction together with the electrode unit 20, and has the fifth opening portion 345 that is opened toward the object OH to be heated in the −Z direction and surrounds the first electrode 30 and the second electrode 40 when viewed along the Z direction. Accordingly, even without providing a casing for heating the object OH to be heated while preventing leakage of the radiation wave from the electrode unit 20, the object OH to be heated can be heated by the electrode unit 20 while the radiation wave can be blocked by the fourth cover unit 340 and the facing unit 150. Therefore, the retention of a vapor generated by the heating of the object OH to be heated can be prevented. Accordingly, it is possible to prevent the liquid generated by condensation of the retained vapor from contaminating the object OH to be heated, and to prevent a decrease in drying efficiency when the object OH to be heated is dried by heating.

Further, in the present embodiment, the facing unit 150 includes the recessed portion 151 that is opened in the +Z direction, and the lower end 341 of the fourth cover unit 340 is disposed in the opening of the recessed portion 151. Accordingly, as compared with a case where the lower end 341 of the fourth cover unit 340 is disposed outside the opening of the recessed portion 151, a radiation wave having a higher intensity can be blocked by the fourth cover unit 340 and the facing unit 150. Therefore, for example, a higher voltage can be applied to the electrode unit 20, and the heating efficiency of the object OH to be heated can be further increased.

G. Seventh Embodiment

FIG. 15 is a schematic diagram showing a dielectric heating apparatus 100g according to a seventh embodiment. FIG. 16 is a perspective diagram showing a schematic configuration of a fourth cover unit 340b according to the seventh embodiment. Unlike the sixth embodiment, the dielectric heating apparatus 100g according to the present embodiment includes a fourth edge portion 347 that continuously surrounds the fifth opening portion 345 of the fourth cover unit 340b. Portions of the configuration of the dielectric heating apparatus 100g in the present embodiment, which are not particularly described, are the same as those in the sixth embodiment.

The fourth edge portion 347 is made of an electrically insulating magnetic material. In the present embodiment, a Ni—Zn-based soft ferrite material formed in a sheet shape is used as the fourth edge portion 347, similar to the first edge portion 317. The fourth edge portion 347 is fixed to an outer surface of the lower end 341 of the fourth cover unit 340b via an adhesive so as to surround the fifth opening portion 345 without interruption. In other embodiments, for example, the fourth edge portion 347 may be fixed to an inner surface of the lower end 341, or may be fixed to both outer and inner surfaces of the lower end 341.

According to the seventh embodiment described above, the fourth edge portion 347 is disposed around the fifth opening portion 345 of the fourth cover unit 340b, and the fourth edge portion 347 is made of a magnetic material having an electric conductivity lower than that of the metal forming the fourth cover unit 340b. Accordingly, similar to the case where the first edge portion 317 described in the first embodiment prevents the electromagnetic field radiated from the first insertion port 312 to the outside of the first cover unit 310, the fourth edge portion 347 can prevent the electromagnetic field radiated from the fifth opening portion 345 to the outside of the fourth cover unit 340b.

H. Eighth Embodiment

FIG. 17 is a diagram showing a schematic configuration of a printing system 600 according to an eighth embodiment. The printing system 600 includes the dielectric heating apparatus 100 described in the first embodiment and a liquid discharge device 610.

The liquid discharge device 610 according to the present embodiment is configured as an inkjet printer, and includes a liquid discharge unit 620 that discharges a liquid onto a printing medium, a medium conveyance unit 630 that conveys the printing medium, and a discharge control unit 640 that controls the liquid discharge unit 620 and the medium conveyance unit 630. The liquid discharge unit 620 includes, for example, a piezo-type or thermal-type liquid discharge head. The medium conveyance unit 630 includes, for example, a roller, similar to the conveyance unit 200. The discharge control unit 640 includes, for example, a computer, similar to the control unit 500 of the dielectric heating apparatus 100. The discharge control unit 640 controls the liquid discharge unit 620 and the medium conveyance unit 630 such that the liquid is discharged and adhered to the printing medium while the printing medium is being conveyed.

As described in the first embodiment, the dielectric heating apparatus 100 heats, as the object OH to be heated, the printing medium on which the liquid discharged by the liquid discharge unit 620 is adhered. That is, the conveyance unit 200 conveys, as the object OH to be heated, the printing medium on which the liquid is adhered. As shown in FIG. 17, the object OH to be heated may be continuously conveyed from the liquid discharge device 610 to the dielectric heating apparatus 100. In this case, for example, the conveyance unit 200 of the dielectric heating apparatus 100 may function as the medium conveyance unit 630. In addition, the object OH to be heated may not be continuously conveyed from the liquid discharge device 610 to the dielectric heating apparatus 100. For example, after the printing medium on which the liquid discharged by the liquid discharge device 610 is adhered is once wound in a roll shape, the wound printing medium may be moved to the dielectric heating apparatus 100 by a robot or the like. In this case, the object OH to be heated can be heated in the dielectric heating apparatus 100 by conveying the rolled printing medium as the object OH to be heated by the conveyance unit 200 while unwinding the printing medium.

According to the eighth embodiment described above, it is also possible to prevent a vapor generated by the heating of the object OH to be heated from retaining in the case unit 300. In other embodiments, the configurations described in the second to seventh embodiments may be adopted as the configuration of the dielectric heating apparatus 100 provided in the printing system 600.

I. Other Embodiments

(I-1) In the embodiments described above, the first edge portion 317 is disposed around at least one of the first insertion port 312 and the first feed-out port 314. However, the first edge portion 317 may not be disposed around the first insertion port 312 or the first feed-out port 314. Similarly, the second edge portion 327 may not be disposed around the second insertion port 322 or the second feed-out port 324.

(I-2) In the embodiments described above, the sum of the opening areas of the second opening portions 326 is larger than the sum of the opening areas of the first opening portions 316. On the other hand, the sum of the opening areas of the second opening portions