Dielectric heating device

Abstract

The present invention provides a dielectric heating device that can perform dielectric heating according to the shape of the object to be heated. [Solution] The dielectric heating device includes a microwave dielectric heating unit that radiates microwaves into space to perform microwave dielectric heating, and two or more high-frequency dielectric heating units that apply a high-frequency electric field to the space to perform high-frequency dielectric heating.

Description

Technical Field

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

Background Art

[0002] Methods for thawing frozen food 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 food, but take a long time to thaw the food. Natural thawing is likely to cause problems such as discoloration and dripping of food and takes a long time to thaw the food. Thawing with a microwave oven does not take a long time to thaw the food, but is likely to cause problems such as discoloration, dripping, and uneven heating of the food.

[0004] [[ID=2--0]]A microwave oven heats food by microwave dielectric heating. In microwave dielectric heating, microwaves are radiated into the oven, the radiated microwaves are reflected by the inner wall, the radiated or reflected microwaves penetrate into the food in the oven, and the food is heated by vibrating the polarization direction of the molecules in the food 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 food will be explained.

[0006] When food is heated by microwave dielectric heating, the depth of penetration of microwaves into the food (hereinafter referred to as "penetration depth") becomes shorter as the frequency of the microwaves increases, and the loss factor ε of the food is determined by the relative permittivity ε and the dielectric loss tangent tanδ of the food. The penetration depth becomes shorter as tanδ increases. In many cases, when the temperature of the food becomes -10°C or higher, the loss factor ε of the food r and the dielectric loss tangent tanδ of the food r· tanδ becomes larger. r·When tanδ becomes significantly larger, 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 sufficiently, 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] Furthermore, in dielectric heating devices that perform both microwave dielectric heating and high-frequency dielectric heating, in order for microwaves to penetrate between two or more electrode plates, the distance between the two or more electrode plates must be at least half the wavelength of the microwaves. Therefore, there are limitations on narrowing the distance between the two or more electrode plates in order to eliminate the air layer between them.

[0013] One aspect of this disclosure has been made in view of this problem. One aspect of this disclosure aims to provide a dielectric heating apparatus that can perform dielectric heating according to the shape of the object to be heated, for example. [Means for solving the problem]

[0014] A dielectric heating apparatus according to one aspect of the present disclosure is: Multiple dielectric heating units, including a microwave dielectric heating unit that radiates microwaves into space to perform microwave dielectric heating and two or more high-frequency dielectric heating units that apply a high-frequency electric field to the space to perform high-frequency dielectric heating. Equipped with, The plurality of dielectric heating units include two or more arrayed dielectric heating units arranged in a sequence. [Brief explanation of the drawing]

[0015] [Figure 1] This figure schematically illustrates a dielectric heating device according to the first embodiment. [Figure 2] This figure schematically illustrates a dielectric heating device according to the second embodiment. [Figure 3] It is a top view schematically showing a dielectric heating part provided in the dielectric heating device of the second embodiment.

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Regarding the drawings, the same or equivalent elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0017] 1 First Embodiment 1.1 Combination of Microwave Dielectric Heating and High-Frequency Dielectric Heating FIG. 1 is a diagram schematically showing a dielectric heating device of the first embodiment.

[0018] The dielectric heating device 1 of the first embodiment shown in FIG. 1 is a hybrid type 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 an object to be heated other than food.

[0019] Table 1 shows the characteristics of magnetron type microwave dielectric heating, semiconductor type microwave dielectric heating, and semiconductor type high-frequency dielectric heating.

[0020]

Table 1

[0021] As methods of microwave dielectric heating, magnetron type microwave dielectric heating and semiconductor type microwave dielectric heating shown in Table 1 are mainly mentioned. As a method of high-frequency dielectric heating, semiconductor type high-frequency dielectric heating shown in Table 1 is mainly mentioned.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] In dielectric heating apparatus 1, these differences in characteristics are taken into consideration, and either magnetron-type microwave dielectric heating and semiconductor-type high-frequency dielectric heating are combined, or semiconductor-type microwave dielectric heating and semiconductor-type high-frequency dielectric heating are combined.

[0032] 1.2 Structure of a dielectric heating device The dielectric heating device 1 is a flat-table type dielectric heating device.

[0033] As shown in Figure 1, the dielectric heating device 1 comprises a heating chamber 11, four dielectric heating units 12, a drive unit 13, a detection unit 14, and a control unit 15. The four dielectric heating units 12 include one microwave dielectric heating unit 21 and three high-frequency dielectric heating units 22. The number of dielectric heating units 12 may be reduced to three or increased to five or more. The number of microwave dielectric heating units 21 may be increased to two or more. The number of high-frequency dielectric heating units 22 may be reduced to two or increased to four or more.

[0034] A heating chamber 11a is formed in the heating chamber 11. The heating chamber 11 is provided with an inner wall 11b. The inner wall 11b defines the heating chamber 11a. The heating chamber 11a houses the high-frequency dielectric heating unit 22. The heating chamber 11a includes a space 11c in which the object to be heated T is placed. The inner wall 11b serves as the ground.

[0035] The microwave dielectric heating unit 21 includes a diffuser plate 31 that radiates microwaves MW, and performs magnetron-type microwave dielectric heating by radiating microwaves MW into the space 11c. The diffuser plate 31 is positioned on one side of the first direction D1 with respect to the space 11c. Therefore, the microwave dielectric heating unit 21 is positioned on one side of the first direction D1 with respect to the space 11c. The microwave dielectric heating unit 21 may also include two electrode plates that radiate microwaves MW, and perform semiconductor-type microwave dielectric heating by radiating microwaves MW into the space 11c. The two electrode plates are positioned on both sides of the first direction D1 with respect to the space 11c. Therefore, when performing semiconductor-type microwave dielectric heating, the microwave dielectric heating unit 21 is positioned on both sides of the first direction D1 with respect to the space 11c. One of the two electrode plates may be omitted. If one of the two electrode plates is omitted, microwave power is supplied between the other electrode plate and ground, and one microwave dielectric heating unit 21 is positioned on one side of the first direction D1 with respect to space 11c.

[0036] Each of the high-frequency dielectric heating units 22 is equipped with two electrode plates 32 and 33 to which a high-frequency electric field HF is applied, and performs semiconductor-type high-frequency dielectric heating. The two electrode plates 32 and 33 are arranged on both sides of the second direction D2 with respect to the space 11c. Therefore, each of the high-frequency dielectric heating units 22 is arranged on both sides of the second direction D2 with respect to the space 11c.

[0037] The two electrode plates 32 and 33 provided in each of the high-frequency dielectric heating units 22 face each other across the space 11c from which microwaves MW are radiated, and are separated from each other in the second direction D2. To perform high-frequency dielectric heating with the most ideal energy efficiency, it is desirable that the object to be heated T and the two electrode plates 32 and 33 be in close contact. However, when performing microwave dielectric heating, it is desirable that the two electrode plates 32 and 33 be separated 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 two electrode plates 32 and 33 are preferably separated 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 11c by the two electrode plates 32 and 33. Based on the above, considering both high-frequency dielectric heating and microwave dielectric heating, when the microwave frequency MW is 2.45 GHz, energy efficiency can be increased when the distance between the two electrode plates 32 and 33 is brought close to 67 mm. However, the size of the object to be heated T may be taken into consideration and the distance may be increased from 67 mm.

[0038] The two electrode plates 32 and 33 are not integrated with the inner wall 11b and are electrically insulated from the inner wall 11b. This allows high-frequency power to be supplied to the two electrode plates 32 and 33 from independent power supply systems.

[0039] The three electrode plates 32 (32a, 32b, and 32c) provided in each of the three high-frequency dielectric heating units 22 are separated from each other and electrically insulated from one another. The three other electrode plates 33 (33a, 33b, and 33c) provided in each of the three high-frequency dielectric heating units 22 are separated from each other and electrically insulated from one another. This allows the three high-frequency dielectric heating units 22 to be driven independently of each other.

[0040] The three electrode plates 32 (32a, 32b, and 32c) of one electrode plate are arranged in a first direction D1 and positioned at different locations in the first direction D1. The three other electrode plates 33 (33a, 33b, and 33c) are arranged in a first direction D1 and positioned at different locations in the first direction D1. The three other electrode plates 33 (33a, 33b, and 33c) are positioned at the same locations in the first direction D1 as the three electrode plates 32 (33a, 33b, and 33c) of one electrode plate 32. For example, the position of the other electrode plate 33a in the first direction D1 is the same as the position of the one electrode plate 32a in the first direction D1. This allows the three high-frequency dielectric heating units 22 to independently apply a high-frequency electric field HF to different locations in the first direction D1. The applied high-frequency electric field HF has an electric field component perpendicular to the first direction D1.

[0041] In the dielectric heating apparatus 1, the axial direction of the microwave dielectric heating section 21 is different from the axial direction of the high-frequency dielectric heating section 22.

[0042] In this embodiment, the axial direction of the microwave dielectric heating section 21 is the direction between the position where the diffuser plate 31 is arranged and the space 11c (first direction D1). The axial direction of the high-frequency dielectric heating section 22 is the direction connecting the two electrode plates 32 and 33 that face each other across the space 11c (second direction D2).

[0043] The fact that the axial direction of the microwave dielectric heating section 21 is different from the axial direction of the high-frequency dielectric heating section 22 means that the axial direction of the microwave dielectric heating section 21 intersects with the axial direction of the high-frequency dielectric heating section 22. The axial direction of the microwave dielectric heating section 21 and the axial direction of the high-frequency dielectric heating section 22 may be perpendicular. The first direction D1 may be vertical, or perpendicular to the bottom surface of the heating chamber 11. The second direction D2 may be horizontal to the bottom surface of the heating chamber 11.

[0044] The microwave dielectric heating unit 21 is positioned vertically downward with respect to the space 11c. This allows the microwave dielectric heating unit 21 to be brought closer to the object to be heated T placed on the flat table. This enables efficient microwave dielectric heating of the object to be heated T. Each of the high-frequency dielectric heating units 22 is positioned on the left and right sides in the horizontal direction.

[0045] The four dielectric heating units 12 include three arrayed dielectric heating units 51. In the dielectric heating device 1, the three arrayed dielectric heating units 51 consist of three high-frequency dielectric heating units 22 and are arranged in a first direction D1. The number of arrayed dielectric heating units 51 changes when the number of high-frequency dielectric heating units 22 changes.

[0046] As shown in Figure 1, the drive unit 13 includes a microwave power supply 71, a waveguide 72, a high-frequency power supply 75, and a high-frequency transmission circuit 76.

[0047] The microwave power supply 71 generates high-power microwave power. The microwave power supply 71 includes an inverter or a 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 71 may generate high-power microwave power by other means.

[0048] Waveguide 72 transmits the generated high-power microwave power from microwave power supply 71 to microwave dielectric heating unit 21.

[0049] As a result, the drive unit 13 drives the microwave dielectric heating unit 21 to radiate microwaves MW onto the microwave dielectric heating unit 21.

[0050] The high-frequency power supply 75 generates high-power high-frequency power. The high-frequency power supply 75 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.

[0051] The high-frequency transmission circuit 76 transmits the generated high-power high-frequency power to at least one destination high-frequency dielectric heating unit 22T included in the three high-frequency dielectric heating units 22. If the at least one destination high-frequency dielectric heating unit 22T is two or more destination high-frequency dielectric heating units 22T, the high-frequency transmission circuit 76 distributes the high-power high-frequency power to the two or more destination high-frequency dielectric heating units 22T. The high-frequency transmission circuit 76 selects at least one destination high-frequency dielectric heating unit 22T from the three high-frequency dielectric heating units 22 according to the input control signal. The high-frequency transmission circuit 76 includes a power supply line and a relay. The drive unit 13 may include three high-frequency power supplies 75 that drive each of the three high-frequency dielectric heating units 22. The power values ​​of the high-frequency power generated by the three high-frequency power supplies 75 may be different from each other. For example, the power value of the high-frequency power generated by the high-frequency power supply 75 driving the high-frequency dielectric heating unit 22 located in the center of the first direction D1 may be greater than the power value of the high-frequency power generated by the high-frequency power supply 75 driving the high-frequency dielectric heating unit 22 located in the uppermost and lowermost parts of the first direction D1. A high-frequency power supply 75 driving one high-frequency dielectric heating unit 22 may be switched by relays between multiple high-frequency power supplies 75 that generate high-frequency power with different power values.

[0052] As a result, the drive unit 13 drives each of the three high-frequency dielectric heating units 22, that is, each of the three array dielectric heating units 51, to apply a high-frequency electric field HF to each array dielectric heating unit 51.

[0053] The detection unit 14 detects whether or not a heated object T is present at each of the three positions where the three array dielectric heating units 51 are arranged. The three positions are in the first direction D1, i.e., the vertical direction, in which the array dielectric heating units 51 are arranged. The detection unit 14 includes an RGB camera and a processing circuit. The RGB camera captures an image of the space 11c and generates an RGB image signal. The processing circuit processes the generated RGB image signal to determine whether or not a heated object T is present at each of the three positions. The RGB camera that generates the RGB image signal may be replaced with a monochrome camera that generates a monochrome image signal, a time-of-flight (ToF) distance sensor that generates a distance signal, etc., and the processing circuit that processes the RGB image signal may be replaced with a processing circuit that processes a monochrome image signal, a signal processing circuit that processes a distance signal, etc. Alternatively, the detection unit 14 includes a thermograph and a signal processing circuit. The thermograph captures an image of the space 11c and generates a temperature distribution image signal. The signal processing circuit processes the generated temperature distribution image signal to determine whether or not a heated object T is present at each of the three locations. The thermograph that generates the temperature distribution image signal may be replaced with a thermopile group, a bolometer or other temperature distribution sensor that generates a signal indicating the temperature distribution signal, and the processing circuit that processes the temperature distribution image signal may be replaced with a signal processing circuit that processes the temperature distribution signal.

[0054] In the dielectric heating apparatus 1, since the first direction D1 is the vertical direction, the vertical position where the object to be heated T exists is a vertical position lower than the vertical position where the vertical upper end of the object to be heated T is located. For this reason, the detection unit 14 may detect the height of the object to be heated T, i.e., the vertical position where the vertical upper end of the object to be heated T is located, using an RGB camera, thermography, etc., and determine that the object to be heated T exists at a vertical position lower than the detected vertical position.

[0055] The control unit 15 controls the drive unit 13. The control unit 15 drives the array dielectric heating unit 51 corresponding to the position where the presence of the object to be heated T is detected by the detection unit 14, and does not drive the array dielectric heating unit 51 corresponding to the position where the absence of the object to be heated T is detected by the detection unit 14. For example, the control unit 15 holds information that determines which array dielectric heating units 51 to drive and which not to drive from the position where the presence of the object to be heated T is detected, and determines which array dielectric heating units 51 to drive and which not to drive according to the held information, turns on and off one of the relays inserted in the power supply line that transmits high-frequency power to the array dielectric heating unit 51 that is driven, and turns on and off the other of the relays inserted in the power supply line that transmits high-frequency power to the array dielectric heating unit 51 that is not driven. The control unit 15 comprises a microcontroller and peripheral circuits. The microcontroller comprises a processor and memory. The processor executes a control program to operate the microcontroller and peripheral circuits as the control unit 15. All or part of the processing performed by the microcontroller may be performed by dedicated electronic circuits.

[0056] The microwave dielectric heating period during which the control unit 15 drives the microwave dielectric heating unit 21 with the microwave power supply 71 of the drive unit 13 may be before the high-frequency dielectric heating period during which the control unit 15 drives the high-frequency dielectric heating unit 22 with the high-frequency power supply 75 of the drive unit 13, or it may be after the high-frequency dielectric heating period, or it may overlap with the high-frequency dielectric heating period.

[0057] According to the dielectric heating device 1, a high-frequency electric field HF is applied to the vertical position where the object to be heated T is located, and is not applied to the vertical position where the object to be heated T is not located. This allows high-frequency dielectric heating to be performed on the object to be heated T by applying the high-frequency electric field HF to the object to be heated T, while suppressing the waste of high-frequency power due to the application of the high-frequency electric field HF to the air layer. Furthermore, high-frequency dielectric heating can be performed on objects to be heated T of various heights, while suppressing the waste of high-frequency power due to the application of the high-frequency electric field HF to the air layer. As a result, dielectric heating can be performed according to the shape of the object to be heated T.

[0058] According to the dielectric heating device 1, when the object to be heated T is a frozen food item, the food item can be thawed quickly and efficiently, while also suppressing energy loss.

[0059] 2. Second Embodiment The following describes the differences between the second embodiment and the first embodiment. For aspects not described, the second embodiment employs the same configuration as the first embodiment.

[0060] Figure 2 is a schematic diagram illustrating a dielectric heating device according to the second embodiment. Figure 3 is a schematic top view illustrating a dielectric heating section provided in the dielectric heating device according to the second embodiment.

[0061] In the dielectric heating device 2 of the second embodiment shown in Figure 2, as shown in Figure 3, the dielectric heating device 2 is equipped with 36 dielectric heating units 12. The 36 dielectric heating units 12 include 18 microwave dielectric heating units 21 and 18 high-frequency dielectric heating units 22. The number of dielectric heating units 12 may be reduced to 3 to 35 or increased to 37 or more. The number of microwave dielectric heating units 21 may be reduced to 1 to 17 or increased to 19 or more. The number of high-frequency dielectric heating units 22 may be reduced to 2 to 17 or increased to 19 or more. The number of high-frequency dielectric heating units 22 may be the same as the number of microwave dielectric heating units 21 or different from the number of microwave dielectric heating units 21.

[0062] Each microwave dielectric heating unit 21 is equipped with two electrode plates 41 and 42 that radiate microwaves MW, and performs semiconductor-type microwave dielectric heating by applying microwaves MW to the space 11c. The two electrode plates 41 and 42 are arranged on both sides of the first direction D1 with respect to the space 11c. Therefore, each microwave dielectric heating unit 21 is arranged on both sides of the first direction D1 with respect to the space 11c. One of the two electrode plates 41 and 42 may be omitted. If one of the two electrode plates 41 and 42 is omitted, microwave power is supplied between the other electrode plate 41 and 42 and ground, and each microwave dielectric heating unit 21 is arranged on one side of the first direction D1 with respect to the space 11c.

[0063] Each of the high-frequency dielectric heating units 22 is equipped with two electrode plates 32 and 33 to which a high-frequency electric field HF is applied, and performs semiconductor-type high-frequency dielectric heating. The two electrode plates 32 and 33 are arranged on both sides of the first direction D1 with respect to the space 11c. Therefore, each of the high-frequency dielectric heating units 22 is arranged on both sides of the first direction D1 with respect to the space 11c.

[0064] In the dielectric heating apparatus 2, the axial direction of the microwave dielectric heating section 21 is the same as the axial direction of the high-frequency dielectric heating section 22. Therefore, each of the microwave dielectric heating sections 21 is positioned on either side or one side of the first direction D1 with respect to the space 11c, and each of the high-frequency dielectric heating sections 22 is positioned on both sides of the first direction D1. The first direction D1 is the vertical direction.

[0065] The 36 dielectric heating units 12 include 36 arrayed dielectric heating units 51. In the dielectric heating device 2, the 36 arrayed dielectric heating units 51 consist of 18 microwave dielectric heating units 21 and 18 high-frequency dielectric heating units 22, and are arranged in a second direction D2 perpendicular to the first direction D1. The number of arrayed dielectric heating units 51 may change if the number of microwave dielectric heating units 21 or the number of high-frequency dielectric heating units 22 changes.

[0066] The second direction D2 is horizontal and is a two-dimensional spreading direction perpendicular to the first direction D1. The two-dimensional spreading direction is a plane direction of a virtual plane perpendicular to the first direction D1. An example of the two-dimensional spreading direction is a plane direction parallel to either of the electrode plates 41 and 42 arranged on both sides of the first direction D1. The microwave dielectric heating section 21 and the high-frequency dielectric heating section 22 are arranged in a checkerboard pattern. The microwave dielectric heating section 21 and the high-frequency dielectric heating section 22 are arranged alternately. The microwave dielectric heating section 21 and the high-frequency dielectric heating section 22 do not have to be arranged in a checkerboard pattern, and the microwave dielectric heating section 21 and the high-frequency dielectric heating section 22 do not have to be arranged alternately.

[0067] Each of the array dielectric heating units 51 is equipped with two electrode plates 61 and 62. The 36 electrode plates 61 provided in each of the 36 array dielectric heating units 51 are separated from each other and electrically insulated from each other. The 36 electrode plates 62 provided in each of the 36 array dielectric heating units 51 are separated from each other and electrically insulated from each other. This allows the 36 array dielectric heating units 51 to be driven independently of each other.

[0068] As shown in Figure 2, the drive unit 13 includes a microwave power supply 73, a microwave transmission circuit 74, a high-frequency power supply 75, and a high-frequency transmission circuit 76.

[0069] The microwave power supply 73 generates high-power microwave power. The microwave power supply 73 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.

[0070] The microwave transmission circuit 74 transmits the generated high-power microwave power to at least one destination microwave dielectric heating unit 21T included in the 18 microwave dielectric heating units 21. If the at least one destination microwave dielectric heating unit 21T is two or more destination microwave dielectric heating units 21T, the microwave transmission circuit 74 distributes the high-power microwave power to the two or more destination microwave dielectric heating units 21T. The microwave transmission circuit 74 selects at least one destination microwave dielectric heating unit 21T from the 18 microwave dielectric heating units 21 according to the input control signal. The microwave transmission circuit 74 includes a power supply line and a relay. The drive unit 13 may include 18 microwave power supplies 73 that drive each of the 18 microwave dielectric heating units 21.

[0071] The high-frequency power supply 75 generates high-power high-frequency power. The high-frequency power supply 75 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.

[0072] The high-frequency transmission circuit 76 transmits the generated high-power high-frequency power to at least one destination high-frequency dielectric heating unit 22T included in the 18 high-frequency dielectric heating units 22. If the at least one destination high-frequency dielectric heating unit 22T is two or more destination high-frequency dielectric heating units 22T, the high-frequency transmission circuit 76 distributes the high-power high-frequency power to the two or more destination high-frequency dielectric heating units 22T. The high-frequency transmission circuit 76 selects at least one destination high-frequency dielectric heating unit 22T from the 18 high-frequency dielectric heating units 22 according to the input control signal. The high-frequency transmission circuit 76 includes a power supply line and a relay. The drive unit 13 may include 18 high-frequency power supplies 75 that drive each of the 18 high-frequency dielectric heating units 22.

[0073] As a result, the drive unit 13 drives each dielectric heating unit included in the 18 microwave dielectric heating units 21 and the 18 high-frequency dielectric heating units 22, i.e., each array dielectric heating unit 51 included in the 36 array dielectric heating units 51, to cause each array dielectric heating unit 51 to radiate microwaves MW or apply a high-frequency electric field HF.

[0074] The detection unit 14 detects whether or not an object to be heated T is present at each of the 36 positions where the 36 array dielectric heating units 51 are arranged. The 36 positions are in the second direction D2, i.e., the horizontal direction, where the array dielectric heating units 51 are arranged.

[0075] The control unit 15 controls the drive unit 13. The control unit 15 drives the array dielectric heating unit 51 located at a position where the presence of the object to be heated T is detected by the detection unit 14, and does not drive the array dielectric heating unit 51 located at a position where the absence of the object to be heated T is detected by the detection unit 14.

[0076] According to the dielectric heating device 2, microwaves MW are irradiated or a high-frequency electric field HF is applied to the horizontal position where the object to be heated T is located, while microwaves MW are not irradiated and a high-frequency electric field HF is not applied to the horizontal position where the object to be heated T is not located. This allows for microwave dielectric heating or high-frequency dielectric heating of the object to be heated T by irradiating it with microwaves MW or applying a high-frequency electric field HF, while also suppressing the waste of microwave power or high-frequency power caused by microwaves MW being radiated into the air layer or a high-frequency electric field HF being applied. As a result, if the object to be heated T is a frozen food item, the food item can be thawed quickly and efficiently, and energy loss is suppressed. These features enable dielectric heating according to the shape of the object to be heated T.

[0077] In the dielectric heating apparatus 2, both the power supply system for microwaves (MW) and the power supply system for high-frequency electric fields (HF) are power supply systems equipped with the same signal generator and amplifier. Therefore, control can be performed solely by electrical switching of the power supply systems.

[0078] 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]

[0079] 1,2 Dielectric heating device 11 Heating cabinet 11a Heating chamber 11b Inner wall 11c space 12 Dielectric heating section 13 Drive unit 14 Detection unit 15 Control Unit 21 Microwave dielectric heating section 22 High-frequency dielectric heating section 31 Diffuser 32,33,41,42 Electrode plate 51 Dielectric heating element 61,62 Electrode plate 71 Microwave power supply 72 Waveguide 73 Microwave power supply 74 Microwave transmission circuits 75 High frequency power supply 76 High-Frequency Transmission Circuits T Heated object MW microwave HF high-frequency electric field

Claims

1. Multiple dielectric heating units, including a microwave dielectric heating unit that radiates microwaves into space to perform microwave dielectric heating and two or more high-frequency dielectric heating units that apply a high-frequency electric field to the space to perform high-frequency dielectric heating. Equipped with, The plurality of dielectric heating units include two or more arrayed dielectric heating units arranged in a sequence. Dielectric heating device.

2. The microwave dielectric heating section is arranged on both sides or one side in the first direction with respect to the space, Each of the two or more high-frequency dielectric heating units is arranged on both sides of a second direction intersecting the first direction with respect to the space. The aforementioned array of two or more dielectric heating units consists of the aforementioned two or more high-frequency dielectric heating units and is arranged in the first direction. The dielectric heating apparatus according to claim 1.

3. The first direction is the vertical direction, The second direction is the horizontal direction. The dielectric heating apparatus according to claim 2.

4. The microwave dielectric heating section is arranged on both sides or one side in the first direction with respect to the space, Each of the two or more high-frequency dielectric heating units is arranged on both sides in the first direction with respect to the space, The aforementioned array of two or more dielectric heating units consists of the microwave dielectric heating unit and the two or more high-frequency dielectric heating units, and is arranged in a second direction perpendicular to the first direction. The dielectric heating apparatus according to claim 1.

5. The second direction mentioned above is a two-dimensional spreading direction, The microwave dielectric heating section and the two or more high-frequency dielectric heating sections are arranged in a checkerboard pattern. The dielectric heating apparatus according to claim 4.

6. A drive unit that drives each of the array dielectric heating units included in the two or more array dielectric heating units, A detection unit for detecting whether or not an object to be heated is present at each of the two or more positions where the two or more array dielectric heating units are arranged, The drive unit includes a control unit that drives the array dielectric heating unit corresponding to the position where the object to be heated is detected to be present by the detection unit, and does not drive the array dielectric heating unit corresponding to the position where the object to be heated is detected to be absent by the detection unit, A dielectric heating apparatus according to any one of claims 1 to 5, comprising:

7. The microwave dielectric heating unit is positioned on the lower side in the vertical direction with respect to the space, Each of the two or more high-frequency dielectric heating units is arranged on both sides in the horizontal direction with respect to the space, The aforementioned array of two or more dielectric heating units consists of two or more high-frequency dielectric heating units, which are arranged in the vertical direction. The two or more positions are the two or more positions in the vertical direction. The dielectric heating apparatus according to claim 6.

8. The microwave dielectric heating section is arranged on both sides or one side in the vertical direction with respect to the space. Each of the two or more high-frequency dielectric heating units is arranged on both sides in the vertical direction with respect to the space, The aforementioned array of two or more dielectric heating units consists of the microwave dielectric heating unit and the two or more high-frequency dielectric heating units, and is arranged horizontally. The two or more positions are two or more positions in the horizontal direction. The dielectric heating apparatus according to claim 6.

9. Each of the two or more high-frequency dielectric heating units comprises two electrode plates facing each other across the space. The dielectric heating apparatus according to claim 1.

10. The two electrode plates include one electrode plate and the other electrode plate. Each of the two or more electrode plates provided in the two or more high-frequency dielectric heating sections is electrically insulated from each other. The two or more other electrode plates provided in each of the two or more high-frequency dielectric heating sections are electrically insulated from each other. Each of the two or more electrode plates faces the other of the two or more electrode plates. The dielectric heating apparatus according to claim 9.

11. The two electrode plates are separated from each other by a distance of at least half the wavelength of the microwave. The dielectric heating apparatus according to claim 9.

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