Dielectric heating device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- SHARP KK
- Filing Date
- 2025-01-22
- Publication Date
- 2026-08-03
Smart Images
Figure 2026125141000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a dielectric heating device.
Background Art
[0002] Methods for thawing frozen foodstuffs are roughly classified into thawing with ice water, thawing in a refrigerator, thawing with running water, natural thawing, and thawing with a microwave oven.
[0003] Thawing with ice water, thawing with running water, and thawing in a refrigerator are less likely to cause problems such as discoloration and dripping of foodstuffs, but take a long time to thaw the foodstuffs. Natural thawing is likely to cause problems such as discoloration and dripping of foodstuffs and takes a long time to thaw the foodstuffs. Thawing with a microwave oven does not take a long time to thaw the foodstuffs, but is likely to cause problems such as discoloration, dripping, and uneven heating of the foodstuffs.
[0004] A microwave oven heats foodstuffs by microwave dielectric heating. In microwave dielectric heating, microwaves are radiated into the oven cavity, the radiated microwaves are reflected by the inner wall, the radiated or reflected microwaves penetrate into the foodstuffs in the oven cavity, and the foodstuffs are heated by vibrating the polarization direction of the molecules in the foodstuffs with the penetrated microwaves.
[0005] Here, the reason why thawing with a microwave oven is likely to cause problems such as discoloration, dripping, and uneven heating of foodstuffs will be explained.
[0006] When foodstuffs are heated by microwave dielectric heating, the depth (hereinafter referred to as "penetration depth") at which microwaves penetrate into the foodstuffs becomes shorter as the frequency of the microwaves increases, and the loss factor ε of the foodstuffs is determined by the relative permittivity ε of the foodstuffs r and the dielectric tangent tanδ of the foodstuffs, and becomes shorter as the loss factor ε r ·tanδ of the foodstuffs increases. In many cases, when the temperature of the foodstuffs reaches -10°C or higher, the loss factor ε of the foodstuffs r• Tanδ becomes significantly larger, and the penetration depth becomes significantly shorter. When the penetration depth is significantly shorter, microwaves concentrate near the surface of the food, causing a phenomenon called the runaway effect, where only the area near the surface of the food is significantly heated. If the microwaves are stopped before the runaway effect occurs, the center of the food cannot be heated uniformly, and the food cannot be thawed uniformly. As a result, microwave thawing is prone to problems such as discoloration of food, dripping, and uneven heating.
[0007] High-frequency dielectric heating is a type of dielectric heating that is less likely to cause problems such as discoloration of food, dripping, and uneven heating compared to microwave dielectric heating.
[0008] In high-frequency dielectric heating, food is sandwiched between two or more electrode plates, and high-frequency power is supplied to the two or more electrode plates to apply a high-frequency electric field to the food. The applied high-frequency electric field causes the polarization direction of molecules within the food to rotate and vibrate, thereby heating the food.
[0009] Patent Document 1 discloses a microwave oven that combines dielectric heating. In this microwave oven, a power supply port is formed on the side of the heating chamber, and an upper electrode plate and a lower electrode plate are installed inside the heating chamber. Microwaves are emitted from the power supply port. The upper electrode plate is movable up and down. The lower electrode plate is fixed. The upper electrode plate and the lower electrode plate sandwich the frozen food to be thawed. High frequency is applied to the upper electrode plate and the lower electrode plate (paragraphs 0009, 0023, 0024 and 0027). [Prior art documents] [Patent Documents]
[0010] [Patent Document 1] Patent No. 3290859 [Overview of the project] [Problems that the invention aims to solve]
[0011] When food is heated by high-frequency dielectric heating, if there is an air layer between two or more electrode plates that sandwich the food, a high voltage is applied to the air layer, while only a low voltage is applied to the food. Therefore, when there is an air layer between two or more electrode plates, the food cannot be sufficiently heated by high-frequency dielectric heating. For this reason, in the dielectric heating combined microwave oven disclosed in Patent Document 1, the upper electrode plate is movable up and down, and the upper and lower electrode plates sandwich the frozen food to be defrosted. However, if the upper electrode plate is movable up and down, the structure of the dielectric heating combined microwave oven becomes complex.
[0012] When both microwave dielectric heating and high-frequency dielectric heating are performed, the axial directions of the microwave dielectric heating and the axial directions of the high-frequency dielectric heating are set to be different in order to avoid mechanical and electrical interference between the radiating part that emits microwaves and the electrode plates to which the high-frequency electric field is applied. For this reason, in the combined dielectric heating microwave oven disclosed in Patent Document 1, the power supply port that emits microwaves is formed on the side of the heating chamber, and the electrode plates to which the high-frequency electric field is applied are the upper electrode plate and the lower electrode plate.
[0013] In flat-table microwave ovens, the microwave radiation unit is located either below or above the heating chamber. Therefore, to ensure that the axial directions of microwave dielectric heating and high-frequency dielectric heating are different, the electrode plates to which the high-frequency electric field is applied are positioned on the left and right sides of the heating chamber. Consequently, if the heating chamber is widened to improve the design and functionality of the microwave oven, the spacing between the electrode plates increases, creating an air gap that hinders high-frequency dielectric heating of the food, making it difficult to perform high-frequency dielectric heating. Conversely, if the spacing between the electrode plates is narrowed to facilitate high-frequency dielectric heating of the food, the heating chamber becomes narrower, reducing the design and functionality of the microwave oven. When the electrode plates are positioned above and below the heating chamber, the microwave radiation unit and the electrode plates to which the high-frequency electric field is applied mechanically and electrically interfere with each other.
[0014] One aspect of the present disclosure has been made in view of these issues. One aspect of the present disclosure aims to provide a dielectric heating apparatus that can perform, for example, microwave dielectric heating and high-frequency dielectric heating, and that can suppress interference between elements for microwave dielectric heating and elements for high-frequency dielectric heating. [Means for solving the problem]
[0015] A dielectric heating apparatus according to one aspect of the present disclosure is: A radiating section that emits microwaves, Electrode plate and The diffuser plate has a gap formed therein that allows microwaves to pass through, and a conductive plate, and the electrode plate has a facing portion that faces the electrode plate, A switching mechanism for switching the arrangement of the diffuser plate and the conductive plate between a first arrangement in which the conductive plate does not cover the missing portion in a plan view and a second arrangement in which the conductive plate covers the missing portion in a plan view, A drive unit that drives the radiating unit to cause the radiating unit to emit microwaves, and drives the electrode plate and the opposing unit to apply a high-frequency electric field to the electrode plate and the opposing unit, A control unit which, when the drive unit drives the radiating portion, causes the switching mechanism to adopt the first arrangement, and when the drive unit drives the electrode plate and the opposing portion, causes the switching device to adopt the second arrangement, It is equipped with. [Brief explanation of the drawing]
[0016] [Figure 1] This figure schematically illustrates a dielectric heating device according to the first embodiment. [Figure 2] This is a table showing the planar shapes of the electrode plate, diffuser plate, conductive plate, and opposing part provided in the dielectric heating device of the first embodiment, when microwave dielectric heating is performed and when high-frequency dielectric heating is performed. [Figure 3]A list showing the planar shapes of the electrode plate, diffusion plate, conductor plate, and opposing portion provided in the dielectric heating device according to the first modification of the first embodiment when microwave dielectric heating is performed and when high-frequency dielectric heating is performed. [Figure 4] A side view schematically showing the opposing portion and the switching mechanism provided in the dielectric heating device according to the first embodiment. [Figure 5] A plan view schematically showing the state when the arrangement of the diffusion plate and the conductor plate of the opposing portion, the first contact portion, the second contact portion, and the third contact portion provided in the dielectric heating device according to the first embodiment is the first arrangement. [Figure 6] A plan view schematically showing the state when the arrangement of the diffusion plate and the conductor plate of the opposing portion, the first contact portion, the second contact portion, and the third contact portion provided in the dielectric heating device according to the first embodiment is the second arrangement. [Figure 7] A side view schematically showing the opposing portion and the switching mechanism provided in the dielectric heating device according to the second modification of the first embodiment. [Figure 8] A view schematically showing the dielectric heating device according to the second embodiment.
Embodiments for Carrying Out the Invention
[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted.
[0018] 0 Combination of Microwave Dielectric Heating and High-Frequency Dielectric Heating Table 1 shows the characteristics of magnetron-type microwave dielectric heating, semiconductor-type microwave dielectric heating, and semiconductor-type high-frequency dielectric heating.
[0019]
Table 1
[0020] The main methods of microwave dielectric heating are the magnetron-type microwave dielectric heating and semiconductor-type microwave dielectric heating shown in Table 1. The main method of high-frequency dielectric heating is the semiconductor-type high-frequency dielectric heating shown in Table 1.
[0021] In magnetron-type microwave dielectric heating, an inverter or high-voltage transformer generates a high voltage, and the magnetron is driven by the generated high voltage to produce high-power microwave power. In semiconductor-type microwave dielectric heating, a semiconductor amplifier amplifies low-power microwave power to produce high-power microwave power. In semiconductor-type high-frequency dielectric heating, a semiconductor amplifier amplifies low-power high-frequency power to produce high-power high-frequency power.
[0022] As shown in Table 1, in magnetron-type microwave dielectric heating and semiconductor-type microwave dielectric heating, the frequency of the generated microwave power is 300 MHz or more and 300 GHz or less, preferably 2.45 GHz within the Industrial Scientific and Medical Band (ISM) band. In semiconductor-type high-frequency dielectric heating, the frequency of the generated high-frequency power is 1 MHz or more and 300 MHz or less, preferably 13.56 MHz, 27.12 MHz, or 40.68 MHz within the ISM band.
[0023] In magnetron-type microwave dielectric heating or semiconductor-type microwave dielectric heating, impedance control to match the power supply impedance and load impedance is unnecessary. In semiconductor-type high-frequency dielectric heating, impedance control to match the power supply impedance and load impedance is necessary.
[0024] In magnetron-type microwave dielectric heating and semiconductor-type microwave dielectric heating, the half-depth, which indicates how deep microwaves penetrate beef at -15°C, is approximately 7 cm at 2.45 GHz, and the half-depth, which indicates how deep microwaves penetrate beef at 15°C, is approximately 3 cm at 2.45 GHz. In semiconductor-type high-frequency dielectric heating, the half-depth, which indicates how deep high-frequency waves penetrate beef at -15°C, is approximately 61 cm at 13.56 MHz, and the half-depth, which indicates how deep high-frequency waves penetrate beef at 15°C, is approximately 26 cm at 13.56 MHz.
[0025] In magnetron-type microwave dielectric heating, microwaves generated by the magnetron are radiated throughout the entire heating chamber. Therefore, it is not possible to restrict the area irradiated with microwaves to only a selected area. Consequently, magnetron-type microwave dielectric heating does not possess selective region heating capabilities, which allow heating only a selected area. In semiconductor-type microwave dielectric heating, microwaves are radiated into the heating chamber from an antenna installed in the heating chamber, and in semiconductor-type high-frequency dielectric heating, a high-frequency electric field is applied to the heating chamber by an antenna installed in the heating chamber. Therefore, in semiconductor-type microwave dielectric heating, the area irradiated with microwaves can be restricted to only a selected area by the shape of the antenna, and in semiconductor-type high-frequency dielectric heating, the area to which the high-frequency electric field is applied can be restricted to only a selected area by the shape of the antenna. Consequently, antenna-based methods such as semiconductor-type microwave dielectric heating and semiconductor-type high-frequency dielectric heating possess selective region heating capabilities, which allow heating only a selected area.
[0026] Magnetron-type microwave dielectric heating exhibits low uniformity of defrosting. Semiconductor-type microwave dielectric heating exhibits uniformity of defrosting that is intermediate between that of magnetron-type microwave dielectric heating and semiconductor-type high-frequency dielectric heating. Semiconductor-type high-frequency dielectric heating exhibits high uniformity of defrosting.
[0027] In magnetron-type microwave dielectric heating, the power value of the generated microwaves is up to about 1000W in consumer-grade dielectric heating devices, and up to about 1900W in commercial-grade dielectric heating devices such as those installed in convenience stores. In semiconductor-type microwave dielectric heating, the power value of the generated microwaves is up to about 300W. In semiconductor-type high-frequency dielectric heating, the power value of the generated high-frequency power is up to about 400W.
[0028] In magnetron-type microwave dielectric heating, the power supply and signal oscillator that generate microwave power are inexpensive, ranging from a few thousand yen to tens of thousands of yen. In semiconductor-type microwave dielectric heating, the power supply and signal amplifier that generate microwave power are expensive, ranging from several hundred thousand yen to several million yen. In semiconductor-type high-frequency dielectric heating, the power supply and signal amplifier that generate high-frequency power are expensive, ranging from tens of thousands to several hundred thousand yen.
[0029] In magnetron-type microwave dielectric heating and semiconductor-type microwave dielectric heating, liquid water is primarily subjected to dielectric heating. In semiconductor-type high-frequency dielectric heating, solid ice is primarily subjected to dielectric heating.
[0030] In the dielectric heating apparatus of the first embodiment described later, these differences in characteristics are taken into consideration, and magnetron-type microwave dielectric heating and semiconductor-type high-frequency dielectric heating are combined. In the dielectric heating apparatus of the second embodiment described later, these differences in characteristics are taken into consideration, and semiconductor-type microwave dielectric heating and semiconductor-type high-frequency dielectric heating are combined.
[0031] 1. First Embodiment 1.1 Dielectric heating device Figure 1 is a schematic diagram illustrating a dielectric heating device according to the first embodiment.
[0032] The dielectric heating device 1 of the first embodiment shown in Figure 1 is a hybrid dielectric heating device that performs both microwave dielectric heating and high-frequency dielectric heating on the object to be heated T. The object to be heated T is food. The dielectric heating device 1 is suitable for thawing frozen food. The object to be heated T may be something other than food.
[0033] The dielectric heating device 1 is a flat-table type dielectric heating device.
[0034] As shown in Figure 1, the dielectric heating device 1 comprises a heating chamber 101, a radiating section 102, an electrode plate 103, a counter section 104, a drive section 105, a switching mechanism 106, and a control section 107.
[0035] A heating chamber 101a is formed in the heating chamber 101. The heating chamber 101 is provided with an inner wall 101b. The inner wall 101b defines the heating chamber 101a. The heating chamber 101a houses the electrode plate 103 and the opposing part 104. The heating chamber 101a includes a space 101c in which the object to be heated T is placed.
[0036] The radiating section 102 is positioned on one side of the first direction D1 with respect to the heating chamber 101a and the space 101c. The radiating section 102 radiates microwaves MW into the heating chamber 101a. The radiating section 102 is the opening of a waveguide, etc.
[0037] The electrode plate 103 is positioned on the other side of the first direction D1 with respect to space 101c. The opposing portion 104 is positioned on one side of the first direction D1 with respect to space 101c. Therefore, the electrode plate 103 and the opposing portion 104 are separated from each other in the first direction D1 and face each other across space 101c. The opposing portion 104 is positioned between the radiating portion 102 and space 101c. The electrode plate 103 and the opposing portion 104 are parallel to each other. The planar shape exhibited by the opposing portion 104 when viewed from above can be switched between a first planar shape and a second planar shape. The planar shape when viewed from above refers to the planar shape when viewed from the first direction D1. The first planar shape is a planar shape with a part of the second planar shape missing. The second planar shape is the same planar shape as the electrode plate 103. The second planar shape may be different from the planar shape of the electrode plate 103. When the planar shape of the opposing portion 104 is the first planar shape, the opposing portion 104 is used as a diffuser plate and diffuses the microwave MW radiated by the radiating portion 102 into the space 101c. This makes it possible to perform microwave dielectric heating on the object to be heated T placed in the space 101c and to increase the uniformity of the microwave MW irradiating the object to be heated T. When the planar shape of the opposing portion 104 is the second planar shape, the opposing portion 104 is used as an electrode plate facing the electrode plate 103, and the electrode plate 103 and the opposing portion 104 apply a high-frequency electric field HF to the space 101c. This makes it possible to perform high-frequency dielectric heating on the object to be heated T placed in the space 101c.
[0038] To improve energy efficiency when performing high-frequency dielectric heating on an object T to be heated, it is desirable for the electrode plate 103 and the opposing part 104 to be in close contact with the object T. However, in order to perform microwave dielectric heating on an object T to be heated, microwaves MW must be radiated into the space 101c between the electrode plate 103 and the opposing part 104. For this reason, the electrode plate 103 and the opposing part 104 are preferably separated from each other by a distance of at least half the wavelength of the radiated microwaves MW. For example, if the frequency of the microwaves MW is 2.45 GHz, the electrode plate 103 and the opposing part 104 are preferably separated from each other by a distance of at least 67 mm. This makes it possible to suppress the obstruction of the radiation of microwaves MW into the space 101c by the electrode plate 103 and the opposing part 104. Therefore, when the microwave frequency MW is 2.45 GHz, both microwave dielectric heating and high-frequency dielectric heating can be performed on the object to be heated T when the distance between the electrode plate 103 and the opposing part 104 is brought close to 67 mm, and the energy efficiency when performing high-frequency dielectric heating on the object to be heated T can be increased. However, the size of the object to be heated T may be taken into consideration and the distance may be increased from 67 mm.
[0039] The electrode plate 103 and the opposing portion 104 are not integrated with the inner wall 101b and are electrically insulated from the inner wall 101b. This allows high-frequency power to be supplied to the electrode plate 103 and the opposing portion 104 from an independent power supply system.
[0040] In the dielectric heating apparatus 1, the axial direction of microwave dielectric heating is the same as the axial direction of high-frequency dielectric heating. Therefore, the electrode plate 103 and the opposing part 104 to which the high-frequency electric field HF is applied are arranged on both sides of the first direction D1 with respect to the space 101c, and the radiating part 102 that radiates microwaves MW is arranged on one side of the first direction D1. The first direction D1 is preferably the vertical direction, and one side of the first direction D1 is preferably the downward side in the vertical direction. When one side of the first direction D1 is the downward side in the vertical direction, the radiating part 102 can be brought closer to the object to be heated T placed on the flat table. This makes it possible to efficiently perform microwave dielectric heating on the object to be heated T.
[0041] In the dielectric heating apparatus 1, the axial direction of microwave dielectric heating is the same as the axial direction of high-frequency dielectric heating, but because the opposing part 104 also serves as a diffuser plate and an electrode plate, interference between the elements for microwave dielectric heating and the elements for high-frequency dielectric heating can be suppressed.
[0042] The switching mechanism 106 switches the planar shape of the opposing portion 104 between a first planar shape and a second planar shape.
[0043] As shown in Figure 1, the drive unit 105 includes a microwave power supply 111, a waveguide 112, a high-frequency power supply 113, and a high-frequency transmission line 114.
[0044] The microwave power supply 111 generates high-power microwave power. The microwave power supply 111 includes an inverter or high-voltage transformer, a magnetron, etc. The inverter or high-voltage transformer generates a high voltage. The magnetron generates high-power microwave power from the generated high voltage. The microwave power supply 111 may generate high-power microwave power by other means.
[0045] Waveguide 112 transmits the generated high-power microwave power from microwave power supply 111 to radiator 102.
[0046] As a result, the drive unit 105 drives the radiating unit 102 with microwave power to radiate microwaves from the radiating unit 102.
[0047] In the dielectric heating apparatus 1, high-power microwave power is generated by the magnetron, which reduces the cost of the microwave power supply 111.
[0048] The high-frequency power supply 113 generates high-power high-frequency power. The high-frequency power supply 113 includes a signal generator and an amplifier. The signal generator generates a high-frequency signal. The amplifier amplifies the generated high-frequency signal to generate high-power high-frequency power. The amplifier includes semiconductor amplifying elements. The semiconductor amplifying elements include metal oxide semiconductor field-effect transistors (MOSFETs), insulated gate bipolar transistors (IGBTs), bipolar transistors (BJTs), etc.
[0049] The high-frequency transmission line 114 transmits the generated high-power high-frequency power to the electrode plate 103 and the opposing part 104. The high-frequency transmission line 114 is a coaxial cable, coaxial tube, etc.
[0050] As a result, the drive unit 105 drives the electrode plate 103 and the opposing part 104 with high-frequency power to apply a high-frequency electric field to the electrode plate 103 and the opposing part 104.
[0051] One of the two transmission lines provided in the high-frequency transmission line 114 is directly connected to the diffuser plate 121 and the conductive plate 122, respectively. However, the one transmission line may also be connected to an element that connects to the diffuser plate 121 and the conductive plate 122, and then connected to the diffuser plate 121 and the conductive plate 122 via that element. For example, the one transmission line may be connected to a rotating mechanism 131, described later, provided in the switching mechanism 106, and then connected to the diffuser plate 121 and the conductive plate 122 via the rotating mechanism 131. If the one transmission line is connected to the diffuser plate 121 and the conductive plate 122 via the rotating mechanism 131, for example, the one transmission line may be connected to a brush of a motor provided in the rotating mechanism 131, and then connected to the diffuser plate 121 and the conductive plate 122 via the motor brush and the rotating shaft.
[0052] The control unit 107 controls the drive unit 105 and the switching mechanism 106. When the drive unit 105 drives the radiating unit 102 with microwave power, the control unit 107 causes the switching mechanism 106 to set the planar shape of the opposing unit 104 to a first planar shape, and when the drive unit 105 drives the electrode plate 103 and the opposing unit 104 with high-frequency power, the control unit 107 causes the switching mechanism 106 to set the planar shape of the opposing unit 104 to a second planar shape. The control unit 107 includes a microcontroller and peripheral circuits. The microcontroller includes a processor and memory. The processor executes a control program to operate the microcontroller and peripheral circuits as the control unit 107. All or part of the processing performed by the microcontroller may be performed by dedicated electronic circuits.
[0053] The microwave dielectric heating period, during which the control unit 107 drives the radiating unit 102 with microwave power to the drive unit 105, may be before or after the high-frequency dielectric heating period, during which the control unit 107 drives the electrode plate 103 and the opposing unit 104 with high-frequency power to the drive unit 105.
[0054] 1.2 Planar shape of electrode plate, diffuser plate, conductive plate and opposing part Figure 2 is a table showing the planar shapes of the electrode plate, diffuser plate, conductive plate, and opposing part provided in the dielectric heating device of the first embodiment when microwave dielectric heating is performed and when high-frequency dielectric heating is performed.
[0055] As shown in Figure 2, the planar shape of the electrode plate 103 is circular. Therefore, the first planar shape of the opposing portion 104 when microwave dielectric heating is performed is a planar shape in which a part of the circular planar shape is missing, and the second planar shape of the opposing portion 104 when high-frequency dielectric heating is performed is circular. In the opposing portion 104, a part of the circular planar shape is missing. Hereinafter, the missing part will be called the missing portion 104a. Two or more missing portions 104a may be formed in the opposing portion 104. The planar shape of the electrode plate 103 may be a planar shape other than a circular planar shape. Therefore, the first planar shape may be a planar shape in which a part of a planar shape other than a circular planar shape is missing, and the second planar shape may be a planar shape other than a circular planar shape.
[0056] As shown in Figures 1 and 2, the opposing portion 104 includes a diffusion plate 121 and a conductive plate 122.
[0057] The diffuser plate 121 is positioned between the space 101c and the radiating unit 102. The diffuser plate 121 has a gap 121a that allows microwaves MW to pass through. When the diffuser plate 121 is rotated, it diffuses the microwaves MW emitted by the radiating unit 102 into the space 101c. This makes it possible to increase the uniformity of the microwaves MW irradiating the object to be heated T placed in the space 101c. Two or more gaps 121a may be formed on the diffuser plate 121.
[0058] The missing portion 121a is a hole. The hole has a planar shape with a contour consisting of an arc and line segments connecting the two ends of the arc. The hole may also have a planar shape other than the said planar shape.
[0059] The conductive plate 122 is positioned between the space 101c and the radiating portion 102. The conductive plate 122 is positioned on one side of the first direction D1 relative to the diffuser plate 121, and is positioned between the space 101c and the diffuser plate 121. The conductive plate 122 has the same planar shape as the diffuser plate 121. Therefore, the conductive plate 122 has a missing portion 122a which has the same planar shape as the missing portion 121a of the diffuser plate 121. The conductive plate 122 is positioned parallel to the diffuser plate 121 and is positioned close to the diffuser plate 121. When the missing portion 122a of the conductive plate 122 overlaps with the missing portion 121a of the diffuser plate 121 in the first direction D1, the missing portion 122a of the conductive plate 122 transmits microwaves MW that have passed through the missing portion 121a of the diffuser plate 121. The portion of the conductive plate 122 other than the missing portion 122a has a planar shape larger than the planar shape of the missing portion 121a of the diffuser plate 121. Therefore, when this portion overlaps with the missing portion 121a of the diffuser plate 121 in the first direction D1, it blocks the missing portion 121a of the diffuser plate 121 in a plan view. The conductive plate 122 may be positioned between the diffuser plate 121 and the radiating portion 102. The missing portion 122a of the conductive plate 122 may have a planar shape larger than the planar shape of the missing portion 121a of the diffuser plate 121. Two or more missing portions 122a may be formed on the conductive plate 122. The arrangement in a plan view means the arrangement when viewed from the first direction D1.
[0060] If the portion of the conductive plate 122 other than the missing portion 122a overlaps with the missing portion 121a of the diffuser plate 121 in the first direction D1, it completely covers the missing portion 121a of the diffuser plate 121. However, the portion in question does not have to completely cover the missing portion 121a of the diffuser plate 121. Therefore, the portion in question covers the missing portion 121a of the diffuser plate 121 when it overlaps with the missing portion 121a of the diffuser plate 121 in the first direction D1, but does not have to cover the missing portion 121a of the diffuser plate 121 when it does not overlap with the missing portion 121a of the diffuser plate 121 in the first direction D1.
[0061] The arrangement of the diffuser plate 121 and the conductive plate 122 can be switched between a first arrangement and a second arrangement. In the first arrangement, the circumferential positions of the missing portion 121a of the diffuser plate 121 and the missing portion 122a of the conductive plate 122 are the same, and the missing portion 121a of the diffuser plate 121 and the missing portion 122a of the conductive plate 122 overlap each other. In the second arrangement, the circumferential positions of the missing portion 121a of the diffuser plate 121 and the missing portion 122a of the conductive plate 122 are different, and the missing portion 121a of the diffuser plate 121 and the missing portion 122a of the conductive plate 122 do not overlap each other. Therefore, when the arrangement of the diffuser plate 121 and the conductive plate 122 is the first arrangement, in a plan view, the conductive plate 122 does not block the missing portion 121a of the diffuser plate 121, and in a plan view, the diffuser plate 121 does not block the missing portion 122a of the conductive plate 122. When the arrangement is the second arrangement, in a plan view, the conductive plate 122 blocks the missing portion 121a of the diffuser plate 121, and in a plan view, the diffuser plate 121 blocks the missing portion 122a of the conductive plate 122. Therefore, when the arrangement is the second arrangement, the entire diffuser plate 121 and conductive plate 122 can be used as a single electrode plate without any missing portions. Therefore, when the arrangement is the second arrangement, a high-frequency electric field HF having a uniform electric field distribution can be applied to the electrode plate 103 and the opposing portion 104.
[0062] The switching mechanism 106 rotates the conductive plate 122 in the circumferential direction to switch the arrangement of the diffuser plate 121 and the conductive plate 122 between a first arrangement and a second arrangement. The switching mechanism 106 may also rotate the diffuser plate 121 in the circumferential direction to switch its arrangement between the first arrangement and the second arrangement. The switching mechanism 106 may also rotate the diffuser plate 121 and the conductive plate 122 in opposite directions in the circumferential direction to switch their arrangement between the first arrangement and the second arrangement.
[0063] When the drive unit 105 drives the radiating unit 102 with microwave power, the control unit 107 causes the switching mechanism 106 to set the arrangement of the diffuser plate 121 and the conductive plate 122 to the first arrangement, and when the drive unit 105 drives the electrode plate 103 and the opposing unit 104 with high-frequency power, the control unit 107 causes the switching mechanism 106 to set the arrangement to the second arrangement. Thus, when microwave dielectric heating is performed, the control unit 107 sets the arrangement to the first arrangement, and when high-frequency dielectric heating is performed, it sets the arrangement to the second arrangement.
[0064] Furthermore, in a plan view of the region where the object to be heated T is placed, the energy efficiency of high-frequency dielectric heating can be further improved by matching the planar shapes of the opposing portion 104 and the electrode plate 103. Therefore, in the region where the object to be heated T is placed, if the portion of the conductive plate 122 other than the missing portion 122a overlaps with the missing portion 121a of the diffuser plate 121 in the first direction D1 (or if the arrangement is the second arrangement), that portion may completely block the missing portion 121a of the diffuser plate 121. This configuration eliminates the field-free region in the region where the object to be heated T is placed during high-frequency dielectric heating. On the other hand, in the region other than where the object to be heated T is placed, if the portion of the conductive plate 122 other than the missing portion 122a overlaps with the missing portion 121a of the diffuser plate 121 in the first direction D1 (or if the arrangement is the second arrangement), that portion does not need to completely block the missing portion 121a of the diffuser plate 121.
[0065] Figure 3 is a table showing the planar shapes of the electrode plate, diffuser plate, conductive plate, and opposing part provided in the dielectric heating device of the first modified example of the first embodiment, when microwave dielectric heating is performed and when high-frequency dielectric heating is performed.
[0066] In the first modified example of the first embodiment, as shown in Figure 3, the missing portion 121a of the diffuser plate 121 and the missing portion 122a of the conductive plate 122 are notches formed along the outer circumference of the diffuser plate 121 and the conductive plate 122.
[0067] If two or more missing portions 121a are formed on the diffuser plate 121, the two or more missing portions 121a may include both holes and notches. If two or more missing portions 122a are formed on the conductive plate 122, the two or more missing portions 122a may include both holes and notches.
[0068] 1.3 Switching Mechanism Figure 4 is a schematic side view illustrating the opposing section and switching mechanism provided in the dielectric heating device of the first embodiment. Figure 5 is a schematic plan view illustrating the state in which the arrangement of the diffuser plate and conductive plate in the opposing section, first contact section, second contact section, and third contact section of the dielectric heating device of the first embodiment is in the first arrangement. Figure 6 is a schematic plan view illustrating the state in which the arrangement of the diffuser plate and conductive plate in the opposing section, first contact section, second contact section, and third contact section of the dielectric heating device of the first embodiment is in the second arrangement.
[0069] As shown in Figures 4 to 6, the switching mechanism 106 comprises a rotating mechanism 131, a first contact portion 132, a second contact portion 133, and a third contact portion 134.
[0070] The rotation mechanism 131 rotates the diffuser plate 121 about the rotation axis RA and supports the conductive plate 122 so that it can rotate about the rotation axis RA. The rotation mechanism 131 directly transmits rotational driving force to the diffuser plate 121, causing the diffuser plate 121 to rotate by the transmitted rotational driving force, but does not directly transmit rotational driving force to the conductive plate 122, allowing the conductive plate 122 to rotate freely. The rotation mechanism 131 can rotate the conductive plate 122 in either of the two opposite first rotation directions D11 and second rotation directions D12. The rotation axis RA coincides with the central axis of the electrode plate 103, the conductive plate 122, and the diffuser plate 121.
[0071] The diffuser plate 121 and the conductive plate 122 each have a main surface 121b and a main surface 122b that face each other.
[0072] The first contact portion 132 is connected to the diffuser plate 121 and rotates integrally with the diffuser plate 121. The second contact portion 133 and the third contact portion 134 are connected to the conductive plate 122 and rotate integrally with the conductive plate 122.
[0073] The first contact portion 132 is positioned on the main surface 121b of the diffuser plate 121 and is a projection that protrudes from the main surface 121b of the diffuser plate 121 toward the main surface 122b of the conductor plate 122. The second contact portion 133 and the third contact portion 134 are positioned on the main surface 122b of the conductor plate 122 and are projections that protrude from the main surface 122b of the conductor plate 122 toward the main surface 121b of the diffuser plate 121. The sum of the heights of the first contact portion 132 and the second contact portion 133 is greater than the distance between the main surface 121b of the diffuser plate 121 and the main surface 122b of the conductor plate 122. The sum of the heights of the first contact portion 132 and the third contact portion 134 is greater than the said distance. Therefore, when the first contact portion 132 is positioned in a horizontal position adjacent to the horizontal position of the second contact portion 133, it will contact the side surface of the second contact portion 133. When the first contact portion 132 is positioned in a horizontal position adjacent to the horizontal position of the third contact portion 134, it will contact the side surface of the third contact portion 134.
[0074] The second contact portion 133 and the third contact portion 134 are positioned at different locations relative to each other in the circumferential direction around the rotation axis RA. The first contact portion 132, the second contact portion 133, and the third contact portion 134 are positioned at the same location in the radial direction perpendicular to the rotation axis RA. Therefore, when the rotation mechanism 131 rotates the diffuser plate 121 in the first rotation direction D11 while the first contact portion 132 is not in contact with the second contact portion 133, the diffuser plate 121 rotates in the first rotation direction D11 until the first contact portion 132 comes into contact with the second contact portion 133, as shown in Figure 5. When the first contact portion 132 is in contact with the second contact portion 133, if the rotation mechanism 131 further rotates the diffuser plate 121 in the first rotation direction D11, the first contact portion 132 pushes the second contact portion 133 in the first rotation direction D11, causing the diffuser plate 121 and the conductive plate 122 to rotate integrally in the first rotation direction D11. When the rotation mechanism 131 rotates the diffuser plate 121 in the second rotation direction D12 while the first contact portion 132 is not in contact with the third contact portion 134, the diffuser plate 121 rotates in the second rotation direction D12 until the first contact portion 132 comes into contact with the third contact portion 134, as shown in Figure 6. When the first contact portion 132 is in contact with the third contact portion 134, if the rotation mechanism 131 further rotates the diffuser plate 121 in the second rotation direction D12, the first contact portion 132 pushes the third contact portion 134 in the second rotation direction D12, causing the diffuser plate 121 and the conductive plate 122 to rotate integrally in the second rotation direction D12. The first contact portion 132 and the second contact portion 133 are positioned such that when the first contact portion 132 is in contact with the second contact portion 133, the arrangement of the diffuser plate 121 and the conductive plate 122 becomes the first arrangement. The first contact portion 132 and the third contact portion 134 are positioned such that when the first contact portion 132 is in contact with the third contact portion 134, the arrangement becomes the second arrangement.
[0075] When the control unit 107 drives the radiating unit 102 with microwave power, it rotates the diffuser plate 121 in the first rotation direction D11 using the rotating mechanism 131 until the first contact portion 132 contacts the second contact portion 133, and continues to rotate the diffuser plate 121 in the first rotation direction D11 using the rotating mechanism 131 even after the first contact portion 132 contacts the second contact portion 133. As a result, when microwave dielectric heating is performed, the control unit 107 sets the arrangement of the diffuser plate 121 and the conductive plate 122 to the first arrangement, and rotates the opposing portion 104 in the first rotation direction D11 while maintaining this arrangement. As a result, the control unit 107 rotates the missing portion 121a of the diffuser plate 121 and the missing portion 122a of the conductive plate 122 in the first rotation direction D11 while keeping them overlapping.
[0076] When the control unit 105 drives the electrode plate 103 and the opposing portion 104 with high-frequency power, the control unit 107 rotates the diffuser plate 121 in the second rotation direction D12 using the rotation mechanism 131 until the first contact portion 132 contacts the third contact portion 134. As a result, when high-frequency dielectric heating is performed, the control unit 107 sets the arrangement of the diffuser plate 121 and the conductive plate 122 to the second arrangement. The control unit 107 may continue to rotate the diffuser plate 121 in the second rotation direction D12 using the rotation mechanism 131 even after the first contact portion 132 contacts the third contact portion 134.
[0077] The rotating mechanism 131 may support the diffuser plate 121 so as to be rotatable about the rotation axis RA, and rotate the conductive plate 122 about the rotation axis RA.
[0078] As shown in Figure 4, the rotating mechanism 131 includes a motor 141 and a shaft 142.
[0079] The motor 141 generates rotational driving force and transmits the generated rotational driving force to the shaft 142.
[0080] The center of the diffuser plate 121 is fixed to the shaft 142, and the center of the conductive plate 122 is rotatably fixed by bearings or the like. The shaft 142 rotates due to the transmitted rotational driving force and transmits the transmitted rotational driving force to the diffuser plate 121.
[0081] The diffuser plate 121 rotates due to the transmitted rotational driving force.
[0082] The rotating mechanism 131 may have a structure different from the one shown in Figure 4. For example, the rotating mechanism 131 may include a transmission mechanism such as gears and pulleys, and the transmission mechanism may transmit the rotational driving force generated by the motor 141 to the shaft 142.
[0083] Figure 7 is a schematic side view illustrating the opposing section and switching mechanism provided in the dielectric heating device of the second modified example of the first embodiment.
[0084] The switching mechanism 106 shown in Figure 7 differs from the switching mechanism 106 shown in Figures 4 to 6 in the following respects.
[0085] In the switching mechanism 106 shown in Figure 7, the first contact portion 132 is positioned on the main surface 122b of the conductive plate 122 and is a projection that protrudes from the main surface 122b of the conductive plate 122 toward the main surface 121b of the diffuser plate 121. The second contact portion 133 and the third contact portion 134 are positioned on the main surface 121b of the diffuser plate 121 and are projections that protrude from the main surface 121b of the diffuser plate 121 toward the main surface 122b of the conductive plate 122. The rotation mechanism 131 rotates the diffuser plate 121 about the rotation axis RA and supports the conductive plate 122 so that it can rotate about the rotation axis RA. The rotation mechanism 131 may rotate the conductive plate 122 about the rotation axis RA, or it may support the diffuser plate 121 so that it can rotate about the rotation axis RA.
[0086] 2. Second Embodiment Figure 8 is a schematic diagram illustrating a dielectric heating device according to the second embodiment.
[0087] As shown in Figure 8, the dielectric heating apparatus 2 of the second embodiment comprises a heating chamber 201, a first electrode plate 202, a second electrode plate 203, a drive unit 204, and a control unit 205.
[0088] A heating chamber 201a is formed in the heating chamber 201. The heating chamber 201 includes an inner wall 201b. The inner wall 201b defines the heating chamber 201a. The heating chamber 201a houses the first electrode plate 202 and the second electrode plate 203. The heating chamber 201a includes a space 201c in which the object to be heated T is placed.
[0089] The first electrode plate 202 is positioned on one side of the first direction D1 with respect to space 201c. The second electrode plate 203 is positioned on the other side of the first direction D1 with respect to space 201c. Therefore, the first electrode plate 202 and the second electrode plate 203 are separated from each other in the first direction D1 and face each other across space 201c. The first electrode plate 202 and the second electrode plate 203 are parallel to each other. The first electrode plate 202 and the second electrode plate 203 have the same planar shape. The first electrode plate 202 and the second electrode plate 203 may have different planar shapes.
[0090] To improve the energy efficiency when performing high-frequency dielectric heating on an object T to be heated, it is desirable for the first electrode plate 202 and the second electrode plate 203 to be in close contact with the object T. However, in order to perform microwave dielectric heating on an object T to be heated, microwaves MW must be radiated into the space 201c between the first electrode plate 202 and the second electrode plate 203. For this reason, the first electrode plate 202 and the second electrode plate 203 are preferably separated from each other by a distance of at least half the wavelength of the radiated microwaves MW. For example, if the frequency of the microwaves MW is 2.45 GHz, the first electrode plate 202 and the second electrode plate 203 are preferably separated from each other by a distance of at least 67 mm. This makes it possible to suppress the obstruction of the radiation of microwaves MW into the space 201c by the first electrode plate 202 and the second electrode plate 203. Therefore, when the microwave frequency MW is 2.45 GHz, both microwave dielectric heating and high-frequency dielectric heating can be performed on the object to be heated T when the first electrode plate 202 and the second electrode plate 203 are brought close to 67 mm, and the energy efficiency when performing high-frequency dielectric heating on the object to be heated T can be increased. However, the size of the object to be heated T may be taken into consideration and the distance may be increased from 67 mm.
[0091] As shown in Figure 8, the drive unit 204 includes a microwave power supply 211, a microwave transmission line 212, a high-frequency power supply 213, and a high-frequency transmission line 214.
[0092] The microwave power supply 211 generates high-power microwave power. The microwave power supply 211 includes a signal generator and an amplifier. The signal generator generates a microwave signal. The amplifier amplifies the generated microwave signal to generate high-power microwave power. The amplifier includes semiconductor amplifying elements. The semiconductor amplifying elements are MOSFETs, IGBTs, BJTs, etc.
[0093] The microwave transmission line 212 transmits the generated high-power microwave power to the first electrode plate 202 and the second electrode plate 203. The microwave transmission line 212 is a coaxial cable, coaxial tube, etc.
[0094] As a result, the drive unit 204 drives both the first electrode plate 202 and the second electrode plate 203 with microwave power to radiate microwaves MW to both electrode plates.
[0095] The high-frequency power supply 213 generates high-power high-frequency power. The high-frequency power supply 213 includes a signal generator and an amplifier. The signal generator generates a high-frequency signal. The amplifier amplifies the generated high-frequency signal to generate high-power high-frequency power. The amplifier includes semiconductor amplifying elements. The semiconductor amplifying elements are MOSFETs, IGBTs, BJTs, etc.
[0096] The high-frequency transmission line 214 transmits the generated high-power high-frequency power to the first electrode plate 202 and the second electrode plate 203. The high-frequency transmission line 214 is a coaxial cable, coaxial tube, etc.
[0097] As a result, the drive unit 204 drives the first electrode plate 202 and the second electrode plate 203 with high-frequency power to apply a high-frequency electric field HF to the first electrode plate 202 and the second electrode plate 203.
[0098] A single transmission line may serve as both a microwave transmission line 212 and a high-frequency transmission line 214.
[0099] In the dielectric heating apparatus 2, a first electrode plate 202 and a second electrode plate 203 that radiate microwaves MW are arranged on both sides in the first direction D1, and a first electrode plate 202 and a second electrode plate 203 that apply a high-frequency electric field HF are also arranged on both sides in the first direction D1. Therefore, the axial direction of microwave dielectric heating is the same as the axial direction of high-frequency dielectric heating. Preferably, the first direction D1 is the vertical direction.
[0100] The microwave dielectric heating period, during which the control unit 205 drives the first electrode plate 202 and the second electrode plate 203 with microwave power, may occur before the high-frequency dielectric heating period, after the high-frequency dielectric heating period, or overlap with the high-frequency dielectric heating period.
[0101] The drive unit 204 may drive one of the electrode plates, the first electrode plate 202 and the second electrode plate 203, with microwave power to radiate microwave MW onto that electrode plate. When the drive unit 204 drives one electrode plate with microwave power, the microwave power is supplied between the electrode plate and the ground.
[0102] Unlike the dielectric heating device 1 of the first embodiment, the dielectric heating device 2 of the second embodiment can further standardize the elements for microwave dielectric heating and the elements for high-frequency dielectric heating. This simplifies the structure of the dielectric heating device 2. Unlike the dielectric heating device 1 of the first embodiment, the dielectric heating device 2 of the second embodiment does not require mechanical mechanisms such as the switching mechanism 106. This increases the robustness of the dielectric heating device 2 and reduces the size of the dielectric heating device 2 in the first direction D1.
[0103] This disclosure is not limited to the embodiments described above, and may be replaced with configurations that are substantially the same as those shown in the embodiments, configurations that produce the same effects, or configurations that can achieve the same purpose. [Explanation of Symbols]
[0104] 1,2 Dielectric heating device 101 Heating storage 101a Heating chamber 101b Interior wall 101c space 102 Radiation section 103 Electrode plate 104 Opposite section 105 Drive unit 106 Switching mechanism 107 Control Unit 111 Microwave power supply 112 Waveguide 113 High frequency power supply 114 High-frequency transmission lines 121 Diffuser 121a Missing part 121b Main surface 122 Conductive plate 122a Missing part 122b Main surface 131 Rotation mechanism 132 First contact portion 133 Second contact section 134 Third contact part 141 Motor 142 axes 201 Heating storage 201a Heating chamber 201b Interior wall 201c space 202 First electrode plate 203 Second electrode plate 204 Drive Unit 205 Control Unit 211 Microwave power supply 212 Microwave transmission lines 213 High frequency power supply 214 High-frequency transmission lines MW microwave HF high-frequency electric field RA rotation axis T Heated object
Claims
1. A radiating section that emits microwaves, Electrode plate and The diffuser plate has a gap formed therein that allows microwaves to pass through, and a conductive plate, and the electrode plate has a facing portion that faces the electrode plate, A switching mechanism for switching the arrangement of the diffuser plate and the conductive plate between a first arrangement in which the conductive plate does not cover the missing portion in a plan view and a second arrangement in which the conductive plate covers the missing portion in a plan view, A drive unit that drives the radiating unit to cause the radiating unit to emit microwaves, and drives the electrode plate and the opposing unit to apply a high-frequency electric field to the electrode plate and the opposing unit, A control unit which, when the drive unit drives the radiating portion, causes the switching mechanism to adopt the first arrangement, and when the drive unit drives the electrode plate and the opposing portion, causes the switching device to adopt the second arrangement, A dielectric heating device equipped with the following features.
2. The missing portion includes at least one selected from the group consisting of holes and notches. The dielectric heating apparatus according to claim 1.
3. When the arrangement is the second arrangement, the opposing portion exhibits a circular planar shape in a planar view, and when the arrangement is the first arrangement, it exhibits a planar shape in a planar view in which a part of the circular planar shape is missing. The dielectric heating apparatus according to claim 1.
4. The electrode plate and the opposing portion are separated from each other by a distance of at least half the wavelength of the microwave. The dielectric heating apparatus according to claim 1.
5. The aforementioned switching mechanism is A rotating mechanism that rotates one of the conductive plate and the diffuser plate about a rotation axis, and supports the other plate of the conductive plate and the diffuser plate so as to be rotatable about the rotation axis, A first contact portion connected to one of the aforementioned plates, A second contact portion connected to the other plate, A third contact portion is connected to the other plate and is positioned at a different location from the position where the second contact portion is located in the circumferential direction around the rotation axis, Equipped with, The first arrangement is one in which the first contact portion contacts the second contact portion. The second arrangement is one in which the first contact portion contacts the third contact portion. The dielectric heating apparatus according to claim 1.
6. A rotating mechanism that rotates one of the conductive plate and the diffuser plate around a rotation axis, and rotatably supports the other plate of the conductive plate and the diffuser plate around the rotation axis, A first contact portion connected to the other plate, A second contact portion connected to one of the aforementioned plates, A third contact portion is connected to one of the plates and is positioned at a different location from the position where the second contact portion is located in the circumferential direction around the rotation axis, Equipped with, The first arrangement is one in which the first contact portion contacts the second contact portion. The second arrangement is one in which the first contact portion contacts the third contact portion. The dielectric heating apparatus according to claim 1.
7. The first electrode plate and A second electrode plate facing the first electrode plate, A drive unit that drives at least one of the first electrode plate and the second electrode plate to radiate microwaves onto the at least one electrode plate, and drives the first electrode plate and the second electrode plate to apply high frequency to the first electrode plate and the second electrode plate, A dielectric heating device equipped with the following features.
8. The first electrode plate and the second electrode plate are separated from each other by a distance of at least half the wavelength of the microwave. The dielectric heating apparatus according to claim 7.