High-frequency heating apparatus

Abstract

A high-frequency heating apparatus according to the present disclosure comprises a heating chamber, a surface wave line, an oscillation source, a waveguide, a power feed shaft, a power feed line, and a coupling point. The surface wave line is disposed in the heating chamber. The oscillation source oscillates high-frequency power. The waveguide transmits the high-frequency power from the oscillation source. The power feed shaft transmits the high-frequency power transmitted by the waveguide to the heating chamber. The power feed line transmits the high-frequency power transmitted by the power feed shaft to the surface wave line. The coupling point electrically connects the power feed line and the surface wave line. Among a plurality of terminal portions provided in a resonant current flow path in the surface wave line, the distance from the terminal portion closest to the coupling point to the coupling point is set to (the wavelength of the resonant current × 1 / 4 + 1 / 2 × integer value ± 1 / 8).

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 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] Patent Document 2 discloses a high-frequency heating device that automatically adjusts the output power of an oscillation source so as to supply maximum power to food regardless of the amount of food. The high-frequency heating device described in Patent Document 2 includes an oscillation source, a surface wave exciter, a heating chamber, a waveguide, a dielectric, an adjustment device, a drive device, a cutoff unit, a detector, and a control unit.

[0006] The oscillation source oscillates high-frequency power. The surface wave exciter converts the high-frequency power into a surface wave form and propagates the high-frequency power in the surface wave form to heat food. The heating chamber contains the object to be heated. The waveguide guides the high-frequency power into the heating chamber. The food is placed on the dielectric.

[0007] The adjustment device is disposed within the waveguide and adjusts the impedance so that maximum power is supplied to the food. The drive device moves the adjustment device. The blocking unit blocks radio waves leaking from the adjustment device and drive device. The detector detects that maximum power is being supplied to the food based on high-frequency noise, etc. The control unit controls the oscillation source, adjustment device, and drive device.

[0008] JP-A-52-155442 JP-A-6-338387

[0009] The present disclosure provides a radio frequency heating device that can maximize surface wave heating.

[0010] A high-frequency heating device according to the present disclosure includes a heating chamber, a surface wave line, an oscillation source, a waveguide, a feed shaft, a feed line, and a coupling point.

[0011] The surface wave line is placed in the heating chamber. The oscillation source oscillates high frequency power. The waveguide transmits the high frequency power from the oscillation source. The feed shaft transmits the high frequency power transmitted by the waveguide to the heating chamber. The feed line transmits the high frequency power transmitted by the feed shaft to the surface wave line. The coupling point electrically connects the feed line and the surface wave line.

[0012] Of the multiple terminations provided in the resonant current flow path, which is the flow path of the resonant current in the surface wave line, the distance from the termination closest to the coupling point to the coupling point is set to (1 / 4 wavelength + integer multiple of 1 / 2 wavelength) ± 1 / 8 wavelength, i.e., wavelength of the resonant current × (1 / 4 + 1 / 2 × integer value ± 1 / 8).

[0013] The high frequency heating device according to the present disclosure can supply power to the surface wave line under appropriate conditions, thereby optimizing impedance matching at the coupling point and suppressing unnecessary radiation and reflection of high frequency power, thereby maximizing surface wave heating.

[0014] FIG. 1 is a schematic diagram of a radio-frequency heating apparatus according to a first embodiment of the present disclosure. FIG. 2 is a schematic diagram for explaining the operation of a surface wave line included in the radio-frequency heating apparatus according to the first embodiment. FIG. 3 is a schematic diagram illustrating an enlarged view of a surface wave line and a power supply unit included in the radio-frequency heating apparatus according to the first embodiment. FIG. 4 is a schematic diagram illustrating an enlarged view of a surface wave line and a power supply unit included in the radio-frequency heating apparatus according to the first embodiment. FIG. 5A is a diagram illustrating a configuration of an electromagnetic field analysis model of the radio-frequency heating apparatus according to the first embodiment. FIG. 5B is a cross-sectional view of a main part of FIG. 5A. FIG. 6A is a diagram illustrating an electromagnetic field analysis result when the distance Lf is fixed to a predetermined value and the distance Hf is varied in the electromagnetic field analysis model shown in FIG. 5A. FIG. 6B is a diagram illustrating an electromagnetic field analysis result when the distance Hf is fixed to a predetermined value and the distance Lf is varied in the electromagnetic field analysis model shown in FIG. 5A. FIG. 7 is a schematic diagram of a surface wave line and a power supply unit included in a radio-frequency heating apparatus according to a second embodiment of the present disclosure.

[0015] (Knowledge forming the basis of the present disclosure) At the time when the inventors came up with the idea for the present disclosure, surface wave heating using a surface wave line was known as one of the techniques for grilling an object to be heated.

[0016] The conventional technique described in Patent Document 1, in which a conductor member is fixed to a portion of the surface wave transmission line and protrudes into the waveguide, makes it difficult to achieve impedance matching at the fixed position, which can increase the reflection and radiation of high-frequency power at the fixed portion and reduce the efficiency of conversion to surface wave form.

[0017] The high-frequency heating device described in Patent Document 2 is intended to supply the maximum power of the high-frequency power oscillated from the oscillation source to food. However, even if the conventional technology described in Patent Document 2 can improve the impedance mismatch in the waveguide using an adjustment device, radiation of the high-frequency power occurs at an impedance discontinuity point during the transmission of the high-frequency power from the waveguide to the surface wave line, making it impossible to maximize surface wave heating.

[0018] The present inventors have investigated maximizing surface wave heating by a surface wave line in a configuration in which the surface wave line is rotated to suppress uneven heating of an object to be heated.

[0019] Possible methods for feeding power to a surface wave transmission line include electric field coupling, magnetic field coupling, and current coupling. Of these, electric field coupling and magnetic field coupling do not contact the surface wave transmission line with the power feeder. This makes the device structure complex, leading to an increase in the overall size of the device and an increase in manufacturing costs.

[0020] In the case of current coupling, the surface wave line and the power supply are directly connected. Therefore, if impedance matching is not achieved at the connection point, reflection and radiation of high-frequency power increases at the connection point between the surface wave line and the conductor member protruding into the waveguide. As a result, the high-frequency power converted into surface waves decreases.

[0021] To solve these problems, it is necessary to achieve both rotation of the surface wave guide to suppress uneven heating of the object to be heated and maximization of heating of the object by the surface wave guide. To achieve this, the inventors of the present application came up with the idea that it is necessary to optimize impedance matching at the connection position between the surface wave guide and the power supply device using a simple power supply structure, and have devised the subject matter of the present disclosure.

[0022] According to the high frequency heating device of the present disclosure, the position of the coupling point between the surface wave line and the power feed line and the length of the power feed path can be optimized to maximize surface wave heating.

[0023] 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.

[0024] First Embodiment Hereinafter, a high-frequency heating device 100 according to a first embodiment of the present disclosure will be described with reference to FIGS. 1 to 6B.

[0025] Fig. 1 shows a schematic configuration diagram of a high-frequency heating apparatus 100. As shown in Fig. 1, the high-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, a coupling point 8, and a surface wave line 9.

[0026] 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.

[0027] 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.

[0028] High-frequency power is transmitted from the oscillation source 4 to the feed line 7 and heating chamber 1 via the waveguide 5 and the feed shaft 6. A coupling point 8 is provided at the end of the feed line 7. The feed line 7 and the surface wave line 9 are connected at the coupling point 8. The feed line 7 transmits high-frequency power from the feed shaft 6 to the surface wave line 9 via the coupling point 8. In this embodiment, the waveguide 5, the feed shaft 6, and the feed line 7 constitute a power supply section 20 that transmits high-frequency power from the oscillation source 4 to the surface wave line 9.

[0029] The surface wave line 9 converts the high frequency power received via the coupling point 8 into a surface wave form and transmits the high frequency power in the surface wave form to the surface wave line 9. This high frequency power in the surface wave form heats the object 2 to be heated, which is placed near the surface wave line 9, and browns the object 2 to be heated.

[0030] The surface wave line 9 is connected to the feed shaft 6 via the feed line 7. The feed shaft 6 is connected to a motor (not shown) and rotates in conjunction with the rotation of the motor. That is, the feed shaft 6 functions as a rotation shaft that rotatably supports the feed line 7 and the surface wave line 9.

[0031] 2 is a schematic diagram for explaining the operation of the surface wave line 9 provided in the high-frequency heating apparatus 100 according to this embodiment. As shown in Fig. 2, the surface wave line 9 has a periodic structure including a plurality of stubs 91 that are erected parallel to one another at regular intervals on a base.

[0032] The multiple stubs 91 include stub 91a and stub 91b. Stub 91a is the stub closest to the feeder line 7 and connected to the feeder line 7 at coupling point 8. Stub 91b is the stub relatively close to the feeder line 7 and adjacent to stub 91a. In FIG. 2 , stub 91a is the first stub as viewed from the feeder line 7, and stub 91b is the third stub as viewed from the feeder line 7.

[0033] The surface wave line 9 converts the supplied high frequency power into high frequency power in a surface wave mode. The surface wave line 9 transmits the high frequency power in a surface wave mode, i.e., surface waves, in a direction perpendicular to the multiple stubs 91. That is, the propagation direction of the surface waves is a radial direction perpendicular to the feed axis 6 and centered on the feed axis 6.

[0034] The surface wave line 9 has two end portions 9a and 9b that are close to the mounting table 3 (see FIG. 1). The end portion 9a is the end portion (the upper end portion in this embodiment) of the stub 91a that is closest to the mounting table 3. The end portion 9b is the end portion (the upper end portion in this embodiment) of the stub 91b that is closest to the mounting table 3.

[0035] In the surface wave line 9 exciting the surface wave, a resonant current 10 flows through a flow path connecting the end 9a and the end 9b of the surface wave line 9 via the stubs 91a and 91b.

[0036] Hereinafter, the path through which the resonant current 10 flows is referred to as the resonant current path 10a. The resonant current path 10a has a length of approximately half the wavelength of the resonant current 10. Therefore, charges are accumulated between the end portions 9a and 9b, generating an electric field 11. As a result, the object 2 to be heated, which is placed near the surface wave line 9, is heated.

[0037] In the present disclosure, a length that is half the wavelength of the resonant current 10 is referred to as a 1 / 2 wavelength. That is, the wavelength refers to the wavelength of the resonant current 10. Similarly, a length that is one-quarter the wavelength of the resonant current 10 is referred to as a 1 / 4 wavelength, and a length that is one-eighth the wavelength of the resonant current 10 is referred to as a 1 / 8 wavelength. The 1 / 4 wavelength and the 1 / 8 wavelength will be described later.

[0038] In the resonant current flow path 10a, a magnetic field 12 is generated around the resonant current 10. Energy transfer occurs between the electric field 11 and the magnetic field 12 via the resonant current 10. This energy transfer causes the electric field 11 and the magnetic field 12 to resonate.

[0039] By setting the path length of the resonant current path 10a to approximately 1 / 2 wavelength, the potential at the end portions 9a and 9b can be maximized. As a result, surface wave heating can be maximized. As described above, the stub 91b is positioned at a distance such that the path length of the resonant current 10 is approximately 1 / 2 wavelength.

[0040] It is desirable to provide only one coupling point 8 on the surface wave line 9. If multiple coupling points are provided, multiple high-frequency currents flowing into the surface wave line 9 from the multiple coupling points may interfere with each other, hindering current excitation at each coupling point. Furthermore, if one tries to avoid this situation, the structure of the device may become complicated.

[0041] 3 and 4 are enlarged schematic diagrams of the surface wave line 9 and the power supply unit 20 provided in the high-frequency heating device 100 according to this embodiment. Fig. 3 shows a case where the distance L1 is equal to the distance L3, and Fig. 4 shows a case where the distance L1 is equal to the distance L2. The distances L1 to L3 will be described later.

[0042] 3 and 4 , the feeder line 7 is current-coupled at a coupling point 8 provided midway along the resonant current path 10a in the surface wave line 9. Structurally, the feeder line 7 is connected to the surface wave line 9 so as to protrude from the side surface of the surface wave line 9 at the coupling point 8. In this embodiment, the feeder line 7 is connected to the surface wave line 9 so as to abut at a substantially right angle against the side surface of the stub 91a that is closest to the feeder line 7, among the multiple stubs 91 included in the surface wave line 9.

[0043] When a high-frequency current flows into the side surface of the surface wave line 9 via the feeder line 7, a resonant current 10 is generated in the surface wave line 9 and propagates along a resonant current path 10a, thereby exciting a surface wave in the surface wave line 9.

[0044] The distance L1 is the length of the power feed path from the lower end 6a of the feed shaft 6 through the upper end 6b of the feed shaft 6 and the feed line 7 to the coupling point 8. The impedance at the end of the feed line 7, i.e., the impedance at the coupling point 8, can be adjusted by adjusting the distance L1.

[0045] Distance L2 is the length of the power supply path between the termination 9a and the coupling point 8 via the stub 91a. Distance L3 is the length of the power supply path between the termination 9b and the coupling point 8 via the stubs 91a and 91b. The impedance of the surface wave line 9 is maximum at the terminations 9a and 9b. The impedance at the coupling point 8 is determined by distances L2 and L3.

[0046] The current coupling excites a resonant current 10 in the resonant current path 10a. Therefore, to maximize the degree of current coupling, it is desirable to provide the coupling point 8 at a position in the resonant current path 10a where the resonant current 10 is at its maximum. Specifically, it is desirable to provide the coupling point 8 at a position approximately ¼ wavelength away from the end 9a of the stub 91a.

[0047] However, the impedance of the power supply line 7, which is electrically floating above the heating chamber 1, is somewhat high due to the influence of the impedance of the space within the heating chamber 1. In addition, in a configuration in which the surface wave line 9 is rotated by a motor, the impedance fluctuates somewhat due to fluctuations in stray capacitance with the surroundings, etc.

[0048] Therefore, it is necessary to balance the degree of current coupling with impedance matching at the connection position. Specifically, the position of the coupling point 8 needs to be adjusted slightly from a position approximately 1 / 4 wavelength away from the terminal end 9a. Adjusting the position of the coupling point 8 from the viewpoint of impedance matching will be described later with reference to Figures 5A to 6B.

[0049] 3 and 4, when the impedance matching at the coupling point 8 is optimized and a surface wave is excited in the surface wave line 9, the sum of the distances L1 and L2 or the sum of the distances L1 and L3 is, in principle, an integer multiple of 1 / 2 wavelength.

[0050] In this state, for example, when the sum of the distances L1 and L2 is an integer multiple of 1 / 2 wavelength, the distance L3 is approximately equal to the distance L1, as shown in Fig. 3. When the sum of the distances L1 and L3 is an integer multiple of 1 / 2 wavelength, the distance L2 is approximately equal to the distance L1, as shown in Fig. 4.

[0051] Next, the allowable range of dimensions that can maintain impedance matching at the coupling point 8 will be described with reference to FIGS. 5A, 5B, 6A, and 6B.

[0052] Fig. 5A is a diagram for explaining the configuration of an electromagnetic field analysis model in the high-frequency heating device 100 according to this embodiment. Fig. 5B is a cross-sectional view of a main part of Fig. 5A, specifically a cross-sectional view taken along line A-A in Fig. 5A. Figs. 6A and 6B show the results of electromagnetic field analysis of the electromagnetic field analysis model shown in Fig. 5A.

[0053] 5A and 5B , the orthogonal coordinate system including the X-axis, Y-axis, and Z-axis is intended to indicate the orientation of the arrangement of each component in the electromagnetic field analysis model of the high-frequency heating device 100. The origin of this orthogonal coordinate system is located at the intersection of the bottom of the housing that constitutes the heating chamber 1 and the center line of the power feed shaft 6.

[0054] The X-axis extends in the longitudinal direction of the waveguide 5 and the surface wave line 9. That is, the X-axis corresponds to the lateral direction of the high-frequency heating device 100. The high-frequency power supplied to the waveguide 5 propagates within the waveguide 5 in the negative direction of the X-axis, and the high-frequency power in the form of a surface wave propagates through the surface wave line 9 in the negative direction of the X-axis.

[0055] The Y-axis extends in the short-side direction of the waveguide 5 and the surface wave line 9. That is, the Y-axis corresponds to the depth direction of the high-frequency heating device 100. The XY plane is a horizontal plane. The Z-axis extends in the vertical direction, and the positive direction of the Z-axis is vertically upward.

[0056] 5B, the distance Lf is the length of the feed path in the feed line 7 from the intersection of the feed line 7 and the feed axis 6 to the coupling point 8. The distance Hf is the length of the feed path in the stub 91a from the coupling point 8 to the terminal end 9a.

[0057] 6A shows the results of impedance matching at the coupling point 8 when the distance Lf is fixed at a predetermined value and the distance Hf is varied. Fig. 6B shows the results of impedance matching at the coupling point 8 when the distance Hf is fixed at a predetermined value and the distance Lf is varied. In Figs. 6A and 6B, the horizontal axis represents frequency, and the vertical axis represents a value (scattering parameter S11) relative to the target value of impedance matching.

[0058] As shown in Fig. 5A, the electromagnetic field analysis model of the high-frequency heating device 100 includes a heating chamber 1, a waveguide 5, a feed shaft 6, a feed line 7, and a surface wave line 9, similar to the high-frequency heating device 100 shown in Fig. 1. In this electromagnetic field analysis model, an end face of the waveguide 5 parallel to the YZ plane was set as the inlet port, and an electromagnetic field analysis was performed.

[0059] 6A and 6B show the results of impedance matching at coupling point 8 as viewed from the inlet port of waveguide 5, with distances Hf and Lf as variable factors. Using FIGS. 6A and 6B, the ranges of distances Hf and Lf that can maintain the impedance matching target value at −3 dB or less, which is the lower limit, are determined.

[0060] In the analysis shown in Fig. 6A, the distance L is fixed at 8 mm, and the distance H is varied from 5 mm to 20 mm. In this case, the frequency range FR (the range indicated by the horizontal arrow in Fig. 6A) in which the scattering parameter S can be maintained at or below -3 dB is 0.057 GHz.

[0061] That is, if the distance Hf changes by 15 mm, the frequency at which impedance matching is achieved at the coupling point 8 changes by 0.057 GHz. From this analysis result, the fluctuation range of the distance Hf, which corresponds to a frequency bandwidth of 0.1 GHz from 2.4 GHz to 2.5 GHz, which is the ISM band (Industrial Scientific and Medical Band) in the high-frequency heating device 100, is calculated. As a result, the fluctuation range is 26.2 mm.

[0062] 6B, the distance Hf is fixed at 10 mm, and the distance Lf is varied from 5 mm to 15 mm. In this case, the frequency range FR (the range indicated by the horizontal arrow in the figure) in which the scattering parameter S11 can be maintained at or below −3 dB is 0.03 GHz.

[0063] That is, if the distance Lf changes by 10 mm, the frequency at which impedance matching is achieved at the coupling point 8 changes by 0.03 GHz. From this analysis result, the fluctuation range of the distance Lf, which corresponds to the 0.1 GHz frequency bandwidth from 2.4 GHz to 2.5 GHz, which is the ISM band in the high-frequency heating device 100, is calculated. As a result, the fluctuation range is 32.9 mm.

[0064] From the above results, the average fluctuation width in the ISM band is approximately 30 mm. This average fluctuation width corresponds to 1 / 4 wavelength. Therefore, it is desirable that the dimension to maintain impedance matching at coupling point 8 be the center value ± 1 / 8 wavelength. Note that the above-mentioned predetermined values ​​for distance Hf and distance Lf are merely examples and are not limited to the above values.

[0065] As described above, it is possible to optimize impedance matching at the coupling point 8 by adjusting the length of the feed path, which is determined by the position of the coupling point 8, the dimensions of the feed shaft 6, and the dimensions of the feed line 7. That is, by slightly adjusting the position and setting each dimension to an intended value, it is possible to optimize impedance matching at the coupling point 8 and maintain the optimized state.

[0066] This simplifies the connection of the mechanical parts required to rotate the surface wave line 9. As a result, it is possible to maximize surface wave heating while suppressing uneven heating.

[0067] [Effects, etc.] The high-frequency heating device 100 according to this embodiment includes a heating chamber 1, a surface wave line 9, an oscillation source 4, a waveguide 5, a feed shaft 6, a feed line 7, and a coupling point 8.

[0068] The surface wave line 9 is disposed in the heating chamber 1. The oscillation source 4 oscillates high frequency power. The waveguide 5 transmits the high frequency power from the oscillation source 4. The feed shaft 6 transmits the high frequency power transmitted by the waveguide 5 to the heating chamber 1. The feed line 7 transmits the high frequency power transmitted by the feed shaft 6 to the surface wave line 9. The coupling point 8 electrically connects the feed line 7 and the surface wave line 9.

[0069] Of the multiple terminations provided on the resonant current flow path 10a, which is the flow path of the resonant current 10 in the surface wave line 9, the distance from the termination 9a closest to the coupling point 8 to the coupling point 8 is set to the wavelength of the resonant current 10 × (1 / 4 + 1 / 2 × integer value ± 1 / 8), i.e., (1 / 4 wavelength + integer multiple of 1 / 2 wavelength) ± 1 / 8 wavelength.

[0070] This optimizes the impedance matching between the feeder line 7 and the surface wave line 9 at the coupling point 8, thereby maximizing surface wave heating while suppressing uneven heating. As a result, various objects 2 can be heated to a desired state.

[0071] In the high-frequency heating device 100 according to this embodiment, the connection point 8 may be provided midway along the resonant current path 10 a. The feed line 7 may be connected to the connection point 8 in a direction protruding from the resonant current path 10 a.

[0072] This ensures that the surface wave mode is excited in the surface wave line 9, maximizing surface wave heating. As a result, various objects 2 to be heated can be heated to a desired state.

[0073] In the high-frequency heating device 100 according to this embodiment, the distance from the end (lower end 6 a) installed on the waveguide 5 to the terminal end closest to the coupling point, via the feed shaft 6 and the feed line 7, may be set to the wavelength of the resonant current 10 × (½ × integer value ±⅛), i.e., an integer multiple of ½ wavelength ±⅛ wavelength.

[0074] This optimizes the impedance matching between the feeder line 7 and the surface wave line 9 at the coupling point 8, thereby maximizing surface wave heating while suppressing uneven heating. As a result, various objects 2 can be heated to a desired state.

[0075] In the high-frequency heating device 100 according to this embodiment, the coupling point may be set at a position such that the distance L1 from the end (lower end 6 a) of the feed shaft 6 installed in the waveguide 5 to the coupling point 8 is equal to the distance L2 from the end 9 a of the resonant current path 10 a of the surface wave line 9 that is the end closest to the coupling point 8.

[0076] This optimizes the impedance matching between the feeder line 7 and the surface wave line 9 at the coupling point 8, thereby maximizing surface wave heating while suppressing uneven heating. As a result, various objects 2 can be heated to a desired state.

[0077] The high-frequency heating device 100 according to this embodiment may have one connection point 8 .

[0078] This ensures that the surface wave mode is excited in the surface wave line 9, maximizing surface wave heating, and therefore various objects 2 to be heated can be heated to a desired state.

[0079] In the high-frequency heating device 100 according to this embodiment, the power feed line 7 and the surface wave line 9 may be electrically connected to the power feed shaft 6 and may be rotatable about the power feed shaft 6 as a central axis.

[0080] This makes it possible to suppress uneven heating of the object 2 due to surface waves with a simple configuration that allows the surface wave line 9 to rotate, and therefore makes it possible to heat various objects 2 to a desired state.

[0081] In the high-frequency heating device 100 according to this embodiment, the coupling point 8 may be set at a position where the impedance at the end of the feed line 7, which is determined by the distance L1 from the end (lower end 6 a) of the feed shaft 6 installed in the waveguide 5 to the end of the feed line 7, matches the impedance determined by the distribution of the resonant current 10 midway along the resonant current path 10 a.

[0082] This optimizes the impedance matching between the feeder line 7 and the surface wave line 9 at the coupling point 8, thereby maximizing surface wave heating while suppressing uneven heating. As a result, various objects 2 can be heated to a desired state.

[0083] Second Embodiment A second embodiment will now be described with reference to Fig. 7. Fig. 7 is a schematic diagram of a surface wave line 9 and a power supply unit 20 provided in a high-frequency heating device according to this embodiment.

[0084] In the first embodiment, the length of the feed path is adjusted based on the position of the coupling point 8, the dimensions of the feed shaft 6, and the dimensions of the feed line 7. This makes it possible to achieve both rotation of the surface wave line 9 and optimization of impedance matching at the coupling point 8 with a simple structure.

[0085] However, according to the first embodiment, when the surface wave line 9 is arranged above the feed axis 6, the coupling point 8 cannot be provided midway along the surface wave line 9 having a periodic structure.

[0086] 7, the surface wave line 9 according to this embodiment has a notch 13 provided in the center of the lower part of a stub 91a. The coupling point 8 is provided in the notch 13 of the stub 91a, and the feeder line 7 is connected to the stub 91a at the coupling point 8.

[0087] In this configuration, the distance L1 is the length of the feed path from the lower end 6 a of the feed shaft 6 installed in the waveguide 5 to the coupling point 8, i.e., the sum of the length of the feed shaft 6 and the length of the feed line 7.

[0088] Distance L2 is the length of the power supply path on stub 91a from termination 9a, which is closest to node 8 among the multiple terminations provided on resonant current path 10a, to node 8. Distance L3 is the length of the power supply path from node 8 to termination 9b of stub 91b via stubs 91a and 91b. The dimension (height) of notch 13 is set by adjusting distances L1 to L3.

[0089] In particular, a notch 13 is provided in the center of the lower part of the stub 91a of the surface wave line 9 so that the distance L1 is ¼ wavelength + an integral multiple of ½ wavelength ± ⅛ wavelength. The feeder line 7 is coupled to the stub 91a of the surface wave line 9 at a coupling point 8 provided in the notch 13.

[0090] This configuration makes it possible to optimize impedance matching at the coupling point 8 when a surface wave is excited in the surface wave line 9, thereby maximizing surface wave heating.

[0091] [Effects, etc.] In the high-frequency heating device 100 according to this embodiment, the surface wave line 9 is disposed on the central axis of the feeder shaft 6. The surface wave line 9 has a notch 13 provided on the side of the feeder shaft 6. The coupling point 8 is provided in the notch 13.

[0092] This optimizes the impedance matching between the feeder line 7 and the surface wave line 9 at the coupling point 8, thereby maximizing surface wave heating while suppressing uneven heating. As a result, various objects 2 can be heated to a desired state.

[0093] The high-frequency heating device 100 according to this embodiment may be capable of adjusting the impedance at the coupling point 8 of the power supply line 7 in accordance with the dimensions of the cutout portion 13 .

[0094] This optimizes the impedance matching between the feeder line 7 and the surface wave line 9 at the coupling point 8, thereby maximizing surface wave heating while suppressing uneven heating. As a result, various objects 2 can be heated to a desired state.

[0095] The present disclosure is applicable to a high-frequency heating device capable of performing surface wave heating.

[0096] 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 7 feed line 8 coupling point 9 surface wave line 9a, 9b end 10 resonant current 10a resonant current flow path 11 electric field 12 magnetic field 13 notch 20 feed section 91, 91a, 91b stub 100 high frequency heating device

Claims

1. A high frequency heating device comprising: a heating chamber; a surface wave line arranged in the heating chamber; an oscillation source configured to oscillate high frequency power; a waveguide arranged to transmit the high frequency power from the oscillation source; a feed shaft configured to transmit the high frequency power transmitted by the waveguide to the heating chamber; a feed line configured to transmit the high frequency power transmitted by the feed shaft to the surface wave line; and a coupling point electrically connecting the feed line and the surface wave line, wherein the distance from a coupling point to a coupling point from a plurality of termination points provided in a resonant current flow path, which is a flow path of a resonant current in the surface wave line, that is the termination point closest to the coupling point is set to the wavelength of the resonant current × (1 / 4 + 1 / 2 × integer value ± 1 / 8).

2. The high frequency heating device according to claim 1, wherein the coupling point is provided midway along the resonant current flow path, and the power supply line is connected at the coupling point in a direction protruding from the resonant current flow path.

3. The high-frequency heating device according to claim 1, wherein the distance from the end of the feed shaft installed in the waveguide, via the feed shaft and the feed line, to the termination closest to the coupling point is set to the wavelength of the resonant current × (1 / 2 × integer value ± 1 / 8).

4. The high frequency heating device according to claim 1, wherein the coupling point is set at a position where the distance from the end of the feed shaft installed in the waveguide to the coupling point is equal to the distance from the terminal end closest to the coupling point to the coupling point.

5. The high frequency heating device according to claim 1 or 2, having one said bonding point.

6. The high frequency heating device according to claim 1 or 2, wherein the power feed line and the surface wave line are electrically connected to the power feed shaft and are rotatable about the power feed shaft as a central axis.

7. The high frequency heating device according to claim 1, wherein the surface wave line is arranged on the central axis of the power feed shaft, the surface wave line has a notch provided on the side of the power feed shaft, and the coupling point is provided in the notch.

8. The high frequency heating device according to claim 7, wherein the impedance at the coupling point of the power supply line is adjustable according to the dimensions of the notch.

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