High-frequency heating apparatus

Abstract

A high-frequency heating apparatus (100) according to the present disclosure is provided with a placement table (3), a surface waveguide (8), an oscillation source (4), and a power supply unit (20). The placement table (3) can allow placement of an object to be heated (2) thereon. The surface waveguide (8) is installed below the placement table (3). The oscillation source (4) generates high-frequency power. The power supply unit (20) transmits the high-frequency power from the oscillation source (4) to the surface waveguide (8). The distance between the upper end (8c) of the surface waveguide (8) and the lower surface of the object to be heated (2) is set to 10 mm or less.

Description

High-frequency heating equipment

[0001] The present disclosure relates to a high-frequency heating device that heats an object to be heated using a surface wave line.

[0002] Patent Document 1 discloses a high-frequency heater that aims to uniformly and efficiently heat an object to be heated by configuring the surface wave line or the object to be heated to be freely movable. The high-frequency heater described in Patent Document 1 includes a surface wave line, a radio wave oscillator, a conductive member, and a rotating device.

[0003] The surface wave line excites high frequency power in a surface wave mode within the heating chamber. The radio wave oscillator generates radio wave energy. The waveguide is coupled to the radio wave oscillator and has an opening in the wall of the heating chamber. The conductive member protrudes into the waveguide through the opening of the waveguide and is fixed to a portion of the surface wave line. The rotating device rotates the object to be heated or the surface wave line.

[0004] Hereinafter, in this disclosure, high frequency power in the form of a surface wave is referred to as a surface wave, and heating by the surface wave is referred to as surface wave heating.

[0005] Japanese Unexamined Patent Publication No. 52-155442

[0006] The present disclosure provides a high-frequency heating device that suppresses variations in the intensity of surface waves absorbed by an object to be heated during surface wave heating, and is capable of stably heating various objects to be heated.

[0007] The high-frequency heating device according to the present disclosure includes a mounting table, a surface wave line, an oscillation source, and a power supply unit. An object to be heated can be placed on the mounting table. The surface wave line is installed below the mounting table. The oscillation source generates high-frequency power. The power supply unit transmits the high-frequency power from the oscillation source to the surface wave line. The distance between the upper end of the surface wave line and the lower surface of the object to be heated is set to 10 mm or less.

[0008] The high-frequency heating device according to the present disclosure can maintain a constant distance between the surface wave transmission line and the object to be heated, thereby suppressing variations in the intensity of the surface waves absorbed by the object to be heated and enabling stable surface wave heating of various objects to be heated.

[0009] FIG. 1 is a schematic diagram of a radio-frequency heating device according to a first embodiment of the present disclosure. FIG. 2 is a schematic diagram showing the configuration of a surface wave line and a power supply unit included in the radio-frequency heating device according to the first embodiment. FIG. 3 is a cross-sectional view of a power supply shaft included in the radio-frequency heating device according to the first embodiment. FIG. 4 is a perspective view showing the configuration of a spacer included in the radio-frequency heating device according to the first embodiment. FIG. 5 is a perspective view showing the configuration of a spacer included in the radio-frequency heating device according to the first embodiment, with the surface wave line visible. FIG. 6 is a diagram for explaining the heating region of an object to be heated by the surface wave line included in the radio-frequency heating device according to the first embodiment. FIG. 7 is a diagram for explaining the heating region of an object to be heated by the surface wave line included in the radio-frequency heating device according to the first embodiment. FIG. 8 is a schematic diagram of a radio-frequency heating device according to a second embodiment.

[0010] (Findings that Form the Basis of the Present Disclosure) At the time when the present inventors arrived at the present disclosure, a technology for propagating high-frequency power converted into a surface wave form through a surface wave line and heating an object placed near the surface wave line, as described above, was already known. However, with the prior art described in Patent Document 1, when the object to be heated was moved away from the surface wave line in the vertical direction, the heating was weakened and uniform heating was sometimes not possible.

[0011] In this situation, the inventors of the present application discovered the following two problems. The first problem is that the energy density of the surface wave exponentially decays as the distance from the surface wave line increases in the vertical direction, and the heating performance of the heated object changes depending on the vertical distance between the surface wave line and the heated object. The second problem is that the heating performance of the heated object changes due to deformation or deterioration of the surface wave line, discharge from the surface wave line, etc.

[0012] The present inventors came up with the idea that in order to stably position the object to be heated within the heating area of ​​the surface wave line, it is desirable to fix the position of the surface wave line based on the mounting table on which the object to be heated is placed, and this led to the invention of the subject matter of the present disclosure.

[0013] According to the high-frequency heating device of the present disclosure, by setting the distance between the upper end of the surface wave line and the lower surface of the object to be heated to a predetermined value, it is possible to suppress variations in the intensity of the surface waves absorbed by the object to be heated.

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, for example, detailed descriptions of known matters and redundant descriptions of identical or substantially identical configurations may be omitted.

[0015] 1 to 7, a radio-frequency heating apparatus 100 according to a first embodiment of the present disclosure will be described below. Note that the Cartesian coordinate system shown in the following drawings has an X-axis, a Y-axis, and a Z-axis that respectively indicate the left and right, front and rear, and top and bottom of the radio-frequency heating apparatus 100. That is, the width direction, depth direction, and height direction of the radio-frequency heating apparatus 100 are directions along the X-axis, Y-axis, and Z-axis, respectively. The positive direction of the X-axis, the positive direction of the Y-axis, and the positive direction of the Z-axis correspond to the right, rear, and vertically upward, respectively.

[0016] Fig. 1 is a schematic diagram of a radio-frequency heating apparatus 100. As shown in Fig. 1, the radio-frequency heating apparatus 100 includes a heating chamber 1, a mounting table 3, an oscillation source 4, a waveguide 5, a feed shaft 6, a feed line 7, and two surface wave lines 8.

[0017] The heating chamber 1 is sealed with a metal wall when the front opening is closed with a door (not shown), and has a mounting table 3 arranged approximately horizontally inside. The object 2 to be heated is placed on the mounting table 3, which is a dielectric. The oscillation source 4 is a device that generates high-frequency power, such as a magnetron or a semiconductor oscillator. The waveguide 5 transmits the high-frequency power generated by the oscillation source 4 to the power feed shaft 6.

[0018] The feed shaft 6 has a lower end 6a and an upper end 6b and is a cylindrical shaft that communicates between the waveguide 5 and the heating chamber 1. The lower end 6a is disposed inside the waveguide 5. The upper end 6b is disposed within the housing that constitutes the heating chamber 1 and below the mounting table 3. The feed line 7 is disposed within the housing that constitutes the heating chamber 1 and below the mounting table 3, and is connected to the upper end 6b of the feed shaft 6.

[0019] High-frequency power is transmitted from the oscillation source 4 through the waveguide 5 and the feed shaft 6 to the feed line 7 and the heating chamber 1. The feed line 7 is disposed between two surface wave lines 8. One end of the feed line 7 is connected to one of the two surface wave lines 8, and the other end of the feed line 7 is connected to the other of the two surface wave lines 8. With this configuration, the feed line 7 transmits high-frequency power evenly from the feed shaft 6 to each of the two surface wave lines 8.

[0020] In this embodiment, the waveguide 5 , the feed shaft 6 and the feed line 7 constitute a feed section 20 that transmits high-frequency power from the oscillation source 4 to the two surface wave lines 8 .

[0021] The surface wave line 8 converts the received high frequency power into a surface wave form. This high frequency power in the surface wave form heats the object 2 to be heated, which is placed near the surface wave line 8, and browns the object 2 to be heated.

[0022] 2 is a schematic diagram showing the configuration of the surface wave lines 8 and the power supply unit 20 included in the high-frequency heating apparatus according to this embodiment. As shown in Fig. 2, each of the two surface wave lines 8 has a periodic structure including a plurality of stubs 81 that are erected parallel to each other at regular intervals on a base.

[0023] In each of the two surface wave lines 8, the multiple stubs 81 include a stub 81a and a stub 81b. The stub 81a is the stub closest to the feeder line 7 and connected to the feeder line 7. The stub 81b is the stub next closest to the feeder line 7 and adjacent to the stub 81a. That is, the stub 81a is the first stub as seen from the feeder line 7, and the stub 81b is the second stub as seen from the feeder line 7.

[0024] The surface wave line 8 converts the supplied high frequency power into high frequency power in a surface wave mode. The surface wave line 8 transmits the high frequency power in a surface wave mode, i.e., surface waves, in a transmission direction 14 near the tips of the multiple stubs 81. The transmission direction 14 is a direction perpendicular to the multiple stubs 81, i.e., a radiation direction perpendicular to the feed axis 6 and centered on the feed axis 6.

[0025] The surface wave line 8 is connected to the feed shaft 6 via a feed line 7. The feed shaft 6 is coupled to a drive shaft 9 of a motor (not shown) and rotates in conjunction with the drive shaft 9. In other words, the feed shaft 6 functions as a rotation shaft that rotatably supports the feed line 7 and the surface wave line 8. The feed line 7 and the two surface wave lines 8 connected to the feed line 7 have shapes symmetrical with respect to the center of the feed shaft 6 (i.e., the rotation axis).

[0026] 3 is a cross-sectional view taken along the ZX plane of the power feed shaft 6 included in the high-frequency heating device according to this embodiment. The power feed shaft 6 is made of metal and includes a hollow cavity 6c having an opening on its lower surface.

[0027] The cavity 6c and the drive shaft 9 are fitted together in the rotational direction of the motor, and when the drive shaft 9 rotates, the power supply shaft 6, which is the outer shell of the cavity 6c, rotates in conjunction with the drive shaft 9. The drive shaft 9 is made of a dielectric material such as resin so that the power supply shaft 6 is not electrically connected to the waveguide 5 and so that high-frequency power is not transmitted to the motor.

[0028] The elastic support 10 is installed in a cavity 6c provided between the drive shaft 9 and the feed shaft 6. For example, the elastic support 10 is a metal spring. The motor is fixed to the waveguide 5, and the drive shaft 9 is fixed to the motor. Therefore, the metal spring urges the feed shaft 6 upward. In conjunction with the feed shaft 6, the surface wave line 8 is also urged upward toward the mounting table 3.

[0029] The spacer 11 is made of a dielectric material such as resin. The spacer 11 has an upper end with a protrusion 11a that protrudes upward from an upper end 8c of the surface wave line 8. The upper end 8c of the surface wave line 8 refers to the entire area near the upper ends of the multiple stubs 81 included in the surface wave line 8.

[0030] When the surface wave line 8 is urged upward toward the mounting table 3, the protrusion 11a comes into contact with the lower surface of the mounting table 3. This keeps the distance between the surface wave line 8 and the mounting table 3 constant. When the surface wave line 8 rotates in this state, the protrusion 11a rotates while sliding on the lower surface of the mounting table 3 while remaining in contact with the lower surface of the mounting table 3.

[0031] This configuration makes it possible to stably maintain a desired distance between the upper end 8c of the surface wave line 8 and the object 2 placed on the mounting table 3. The metal spring is made of a conductive material, but is shielded from high-frequency power because it is installed inside the metal power supply shaft 6. This makes it possible to prevent problems caused by the material of the metal spring.

[0032] The configuration of the spacer 11 provided in the high-frequency heating device 100 according to this embodiment will be described with reference to FIGS. 4 and 5. FIG.

[0033] Fig. 4 is a perspective view showing the configuration of a spacer 11 installed on one of the two surface wave lines 8. Fig. 5 is a perspective view showing the configuration of the spacer 11 shown in Fig. 4, seen through the surface wave line 8. Note that the spacer 11 installed on the other of the two surface wave lines 8 has the same configuration as the spacer 11 shown in these figures, and therefore will not be shown or described here.

[0034] 4 and 5 , the surface wave line 8 has a corrugated plate shape formed by repeatedly bending a plate-shaped conductive material. The surface wave line 8 includes a plurality of protrusions 8 a and a plurality of recesses 8 b arranged alternately in the width direction of the high-frequency heating device 100 (the direction along the X-axis in FIG. 5 ). The protrusions 8 a are the upper ends of the stubs 81, and the recesses 8 b are the valleys between two stubs 81.

[0035] Due to this shape, the surface wave line 8 has a periodic structure including a plurality of stubs 81 standing parallel to one another at regular intervals.

[0036] The surface wave line 8 has a spacer 11 and a fixing member 12. The spacer 11 is inserted into the recess 8b between the stubs 81a and 81b. The spacer 11 includes three integrally molded members: a protrusion 11a, an arm portion 11b, and a spacer body 11c.

[0037] The protrusion 11a is provided on the arm portion 11b so as to protrude upward from the upper end portion 8c of the surface wave transmission line 8. The arm portion 11b is provided on the spacer body 11c so as to extend along the Y axis from the spacer body 11c along the stubs 81a and 81b. When the protrusion 11a is pressed downward, the arm portion 11b bends downward. The restoring force of the arm portion 11b against this bending urges the protrusion 11a upward.

[0038] The fixing members 12 are made of a dielectric material and are installed in the spaces 8d below the convex portions 8a on both sides of the concave portion 8b into which the spacer 11 is inserted, and fix the spacer 11 to the surface wave guide 8. A method for fixing the spacer 11 to the surface wave guide 8 using the fixing members 12 will be described below with reference to FIG. 5 .

[0039] 5, as described above, the spacer 11 is inserted into the recess 8b of the surface wave line 8. Therefore, the position of the spacer 11 in the vertical direction (the direction along the Z axis in FIG. 5) is fixed by the recess 8b, and the position of the spacer 11 in the width direction of the high-frequency heating device 100 (the direction along the X axis in FIG. 5) is fixed by the stubs 81a and 81b. At this time, the position of the spacer 11 in the depth direction of the high-frequency heating device 100 (the direction along the Y axis in FIG. 5) is not fixed.

[0040] Therefore, the fixing member 12 is placed in the space 8d below the convex portions 8a on both sides of the concave portion 8b into which the spacer 11 is inserted, while abutting against the side end portions of the spacer 11 in the depth direction.

[0041] The fixing member 12 includes four integrally molded members: two insert members 12a and two positioning members 12b. The two insert members 12a are arranged parallel to the XY plane and extend parallel to each other along the Y axis.

[0042] The two positioning members 12b are arranged parallel to the XY plane and extend parallel to each other along the X axis. One of the two positioning members 12b connects the two front ends of the two insert members 12a, and the other of the two positioning members 12b connects the two far ends of the two insert members 12a. With this configuration, the fixing member 12 has a low rectangular tubular shape overall.

[0043] One of the two insertion members 12a is inserted into and fixed in the space 8d below the protrusion 8a provided on the stub 81a, and the other of the two insertion members 12a is inserted into and fixed in the space 8d below the protrusion 8a provided on the stub 81b.

[0044] When the two insertion members 12a are fixed in place, the two positioning members 12b abut against the spacer 11 (specifically, both side ends of the spacer body 11c in the positive and negative directions of the Y axis) disposed in the recess 8b, i.e., the two positioning members 12b sandwich the spacer 11 along the X axis direction.

[0045] This configuration can prevent the spacer 11 from shifting in the depth direction and from coming loose. Measures to prevent the fixing member 12 from coming loose in the vertical downward direction from the surface wave transmission line 8 are taken by press-fitting the fixing member 12 into the surface wave transmission line 8, or by engaging the spacer 11 and the fixing member 12 with tabs.

[0046] The contact between the mounting table 3 and the protruding portion 11a prevents the spacer 11 from coming off vertically upward (in the positive direction of the Z axis in FIG. 5).

[0047] The surface wave line 8 has a corrugated plate shape as described above, and is therefore prone to bending in the vertical direction. According to this embodiment, spacers 11 are provided in the recesses 8b of the surface wave line 8, and fixing members 12 are also provided in the spaces 8d below the protrusions 8a. With this configuration, the surface wave line 8 can be reinforced by the spacers 11 and the fixing members 12, and deformation such as bending of the surface wave line 8 can be suppressed.

[0048] If a corner or a protrusion exists at the upper end 8c of the surface wave line 8, surface wave energy is concentrated at the corner or the protrusion. This concentration of surface wave energy may cause phenomena such as deformation or deterioration of the surface wave line 8, which may result in uneven heating of the object 2 to be heated.

[0049] In this embodiment, the upper end 8c has a curved shape. Since the surface wave energy is dispersed by the curved surface, it is possible to suppress local concentration of the surface wave energy at the upper end 8c of the surface wave line 8. This makes it possible to prevent the occurrence of a phenomenon that may cause uneven heating of the object 2 to be heated.

[0050] The heating area of ​​the object 2 to be heated by the surface wave line 8 will be described with reference to FIGS. 6 and 7. FIG.

[0051] 6 shows the area of ​​an apple that has changed color after it is placed on the upper end 8c of a surface wave transmission line 8 and heated. In this experiment, the thickness of the apple was set between 10mm and 20mm in 5mm increments. In this case, the thickness of the apple refers to the dimension of the apple in the positive direction of the Z axis in FIG. 5.

[0052] As a result, as shown in Figure 6, discoloration of the apple was confirmed in a range of 10 mm to 12 mm above the top end 8c. From this result, it was found that the area of ​​the apple that can be heated by surface wave heating is within a range of about 10 mm from the top end 8c.

[0053] 7 shows the browned area of ​​a rectangular slice of bread that was placed on the upper end 8c of the surface wave transmission line 8 and heated. In this experiment, the height of the underside of the bread from the upper end 8c of the surface wave transmission line 8 was set at 1mm intervals between 0mm and 5mm. In this case, the height of the underside of the bread from the upper end 8c means the distance from the upper end 8c to the underside of the bread in the positive direction of the Z axis in FIG. 5.

[0054] As a result, browning of the bread was confirmed in an area up to 5 mm above the top end 8c, as shown in Figure 7. This result shows that the area of ​​the bread that can be browned by surface wave heating is within a distance of about 5 mm from the top end 8c.

[0055] From the above results, it was found that the object 2 can be stably heated when the distance between the upper end 8c of the surface wave line 8 and the lower surface of the object 2 is set to 10 mm or less. It was also found that the surface of the object 2 can be stably browned when the distance between the upper end 8c of the surface wave line 8 and the lower surface of the object 2 is set to 5 mm or less.

[0056] In addition, when the object to be heated 2 is placed on the mounting table 3, the distance between the upper end 8c of the surface wave line 8 and the lower surface of the object to be heated 2 is synonymous with the distance between the upper end 8c and the upper surface of the mounting table 3.

[0057] [Effects, etc.] The high-frequency heating device 100 according to this embodiment includes a mounting table 3, a surface wave line 8, an oscillation source 4, and a power supply unit 20. The object 2 to be heated can be placed on the mounting table 3. The surface wave line 8 is installed below the mounting table 3. The oscillation source 4 generates high-frequency power. The power supply unit 20 transmits the high-frequency power from the oscillation source 4 to the surface wave line 8. The distance between an upper end 8c of the surface wave line 8 and the bottom surface of the object 2 to be heated is set to 10 mm or less.

[0058] This allows the object 2 to be placed in an area where efficient surface wave heating is possible, and suppresses variations in the intensity of the surface waves absorbed by the object 2. Therefore, stable surface wave heating can be performed on various objects 2.

[0059] The high-frequency heating apparatus 100 according to this embodiment may further include a spacer 11 installed on the surface wave line 8. The spacer 11 may include a protrusion 11a that protrudes from the upper end 8c of the surface wave line 8 and comes into contact with the lower surface of the mounting table 3.

[0060] This makes it possible to keep constant the distance between the upper end 8c of the surface wave line 8 and the lower surface of the mounting table 3. Therefore, the object 2 can be placed in an area where efficient surface wave heating is possible, and variations in the intensity of the surface waves absorbed by the object 2 can be suppressed.

[0061] The high-frequency heating device 100 according to this embodiment may further include a rotation shaft for rotating the surface wave line 8 .

[0062] This allows the surface wave line 8 to rotate while maintaining a constant distance between the upper end 8c of the surface wave line 8 and the lower surface of the mounting table 3. Therefore, the object 2 to be heated can be placed in an area where efficient surface wave heating is possible, and variations in the intensity of the surface waves absorbed by the object 2 to be heated can be suppressed.

[0063] In the high-frequency heating device 100 according to this embodiment, the power supply unit 20 may have a power supply shaft 6 that functions as a rotation axis. The power supply shaft 6 may have a hollow portion 6c having an opening on the lower surface of the power supply shaft 6. An elastic support 10 that urges the power supply shaft 6 upward may be installed in the hollow portion 6c.

[0064] This allows the protruding portion 11a of the spacer 11 to be continuously pressed against the lower surface of the mounting table 3. Therefore, the distance between the upper end 8c of the surface wave line 8 and the lower surface of the mounting table 3 can be kept constant.

[0065] In the high-frequency heating device 100 according to this embodiment, the surface wave line 8 may be formed by continuously bending a plate-shaped conductive member, and have a corrugated plate shape including a plurality of convex portions 8a and a plurality of concave portions 8b arranged alternately along a predetermined direction.

[0066] This allows the spacer 11 to be placed in the recess 8b of the surface wave line 8. Therefore, the spacer 11 can be stably fixed to the surface wave line 8. Furthermore, the upper end 8c of the surface wave line 8, where surface wave power is concentrated, can be formed into a curved shape. This makes it possible to suppress local concentration of surface wave energy at the upper end 8c of the surface wave line 8, and to prevent deformation and deterioration of the surface wave line 8, as well as discharge from the surface wave line.

[0067] The high-frequency heating device 100 according to this embodiment may have a fixing member 12 in which the surface wave line 8 is installed in the space 8d below the plurality of protrusions 8a.

[0068] This makes it possible to suppress deformation such as bending of the recess 8 b of the surface wave line 8. As a result, it is possible to suppress local concentration of surface wave energy at the upper end 8 c of the surface wave line 8, and to prevent deformation and deterioration of the surface wave line 8, as well as discharge from the surface wave line.

[0069] The high-frequency heating apparatus 100 according to this embodiment further includes a spacer 11 installed on the surface wave line 8. The spacer 11 includes a protrusion 11a that protrudes from an upper end 8c of the surface wave line 8 and contacts the lower surface of the mounting table 3. A fixing member 12 may fix the spacer 11 to the surface wave line 8.

[0070] This allows the spacer 11 to be fixed to the surface wave guide 8 with fewer parts, thereby preventing the structure of the high frequency heating device 100 from becoming complicated and large in size.

[0071] In the high-frequency heating device 100 according to this embodiment, the upper end 8c of the surface wave line 8 may have a curved shape. This makes it possible to suppress local concentration of surface wave energy at the upper end 8c of the surface wave line 8. This makes it possible to prevent deformation and deterioration of the surface wave line 8, as well as discharge from the surface wave line.

[0072] Second Embodiment Hereinafter, a high-frequency heating device 100 according to a second embodiment of the present disclosure will be described with reference to Fig. 8. Fig. 8 is a schematic configuration diagram of the high-frequency heating device 100 according to the present embodiment.

[0073] 8, the high-frequency heating apparatus 100 according to this embodiment differs from the first embodiment in that the mounting table 3 has a ring portion 13. The ring portion 13 is a ring-shaped convex portion provided on the lower surface of the mounting table 3, and protrudes downward from the mounting table 3 so as to come into contact with the surface wave line 8. The lower end of the ring portion 13 comes into contact with the upper end 8c of the surface wave line 8, thereby setting the distance between the surface wave line 8 and the mounting table 3 to a constant value.

[0074] When the surface wave line 8 rotates in this state, the upper end 8c of the surface wave line 8 rotates while sliding on the lower surface of the ring portion 13 while remaining in contact with the lower surface of the ring portion 13. With this configuration, the distance between the upper end 8c of the surface wave line 8 and the object 2 placed on the mounting table 3 can be stably maintained at a desired value.

[0075] Other configurations and effects of this embodiment are the same as or substantially the same as those of the first embodiment, and therefore description thereof will be omitted.

[0076] The present disclosure is applicable to a high-frequency heating device capable of performing surface wave heating.

[0077] REFERENCE SIGNS LIST 1 heating chamber 2 object to be heated 3 mounting table 4 oscillation source 5 waveguide 6 feed shaft 6a lower end 6b upper end 6c cavity 7 feed line 8 surface wave line 8a convex portion 8b concave portion 8c upper end 8d space 9 drive shaft 10 elastic support 11 spacer 11a protrusion 11b arm portion 11c spacer body 12 fixing member 12a insertion member 12b positioning member 13 ring portion 14 transmission direction 20 feed portion 81, 81a, 81b stub 100 high frequency heating device

Claims

1. A high frequency heating device comprising: a mounting table on which an object to be heated can be placed; a surface wave line installed below the mounting table; an oscillation source configured to generate high frequency power; and a power supply unit configured to transmit the high frequency power from the oscillation source to the surface wave line, wherein the distance between the upper end of the surface wave line and the lower surface of the object to be heated is set to 10 mm or less.

2. The high frequency heating device according to claim 1, further comprising a spacer disposed on the surface wave line, the spacer including a protrusion protruding from the upper end of the surface wave line and contacting the lower surface of the mounting table.

3. The high frequency heating device according to claim 2, further comprising a rotation shaft configured to rotate the surface wave line.

4. The high frequency heating device according to claim 3, wherein the power supply unit has a power supply shaft that functions as the rotation shaft, the power supply shaft has a hollow portion with an opening on the lower surface of the power supply shaft, and an elastic support that urges the power supply shaft upward is installed in the hollow portion.

5. The high frequency heating device according to claim 1, wherein the surface wave line has a corrugated plate shape including a plurality of convex portions and a plurality of concave portions arranged alternately along a predetermined direction.

6. The high frequency heating device according to claim 5, wherein the surface wave transmission line has a fixing member installed in the space below the plurality of protrusions.

7. The high frequency heating device according to claim 6, further comprising a spacer disposed on the surface wave line, the spacer including a protrusion protruding from the upper end of the surface wave line and contacting the lower surface of the mounting table, and the fixing member fixing the spacer to the surface wave line.

8. The high frequency heating device according to claim 5, wherein the upper end of the surface wave line has a curved shape.

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