refrigerator

Abstract

To provide a refrigerator having improved reliability on cooling and thawing in a storage room which can thaw frozen foods, while enabling stored objects stored in the storage room to be frozen, stored and thawed in desired states.SOLUTION: A refrigerator includes a storage room having a space enough to store stored objects, a vibration part to form high frequency electric power, and a vibration electrode (24) and an opposite electrode (25) arranged opposed to each other and each connected to the vibration part, the vibration electrode (24) and the opposite electrode (25) serving for receiving the high frequency electric power from the vibration part to generate an electrical field in the storage room. A space H between the vibration electrode (24) and the opposite electrode (25) is shorter than the long side size of the vibration electrode (24).SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to a refrigerator with a freezing function, the refrigerator having a storage compartment capable of thawing frozen items. [Background technology]

[0002] Patent Document 1 discloses a conventional refrigerator having a storage compartment capable of thawing frozen goods. This refrigerator has a freezer main body having a refrigeration device and a magnetron for generating high frequency waves. Inside the freezer main body, a high frequency heating chamber (storage chamber) capable of thawing frozen goods is provided together with the freezer chamber. The freezer main body is configured such that cold air from the refrigeration device is supplied to the high frequency heating chamber via a cold air circulation duct, and high frequency waves are irradiated from the magnetron to thaw frozen goods. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-147919 A Summary of the Invention

[0004] The present disclosure provides a refrigerator having a storage compartment capable of thawing frozen items, capable of freezing, storing, and thawing stored items in a desired state, while having improved reliability in cooling and thawing.

[0005] The refrigerator in the present disclosure includes: A storage chamber having a space capable of storing stored items; An oscillator for generating high frequency power; an oscillation electrode and a counter electrode that are arranged opposite to each other and connected to an oscillation unit, and that receive high-frequency power from the oscillation unit to generate an electric field in the storage chamber; The distance between the oscillation electrode and the counter electrode is shorter than the dimension of the long side of the oscillation electrode. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a vertical cross-sectional view of a refrigerator according to a first embodiment. [Diagram 2] FIG. 2 is a front cross-sectional view showing the freezing / thawing compartment of the refrigerator according to the first embodiment. [Diagram 3] FIG. 3 is a side cross-sectional view showing the freezing / thawing compartment in the refrigerator according to the first embodiment. [Figure 4] FIG. 4 is a vertical cross-sectional view of the refrigerator according to the first embodiment when the freezing / thawing compartment is assembled. [Diagram 5] FIG. 5 is a front cross-sectional view showing a modified example of the freezing / thawing compartment in the refrigerator according to the first embodiment. [Figure 6] FIG. 6 is a side cross-sectional view showing a modified example of the freezing / thawing compartment in the refrigerator according to the first embodiment. [Figure 7] FIG. 7 is a vertical cross-sectional view of the refrigerator according to the first embodiment when the freezing / thawing compartment is assembled. [Figure 8] FIG. 8 is a diagram showing an electrode holding area on the rear side of the freezing / thawing compartment in the first embodiment. [Figure 9] FIG. 9 is a block diagram showing a configuration of a dielectric heating mechanism provided in the refrigerator according to the first embodiment. As shown in FIG. [Figure 10] FIG. 10 is a schematic circuit diagram of an AC / DC converter that drives various circuits. [Figure 11] FIG. 11 is a plan view of an oscillation electrode and a counter electrode on the top surface side of a freezing / thawing compartment in the refrigerator according to the first embodiment, as viewed from above. [Figure 12] FIG. 12 is a diagram showing the relationship between the electrode distance between the oscillation electrode and the counter electrode and the electric field intensity between the two electrodes. [Figure 13A] FIG. 13A is a diagram showing the results of an electric field simulation performed on the dielectric heating configuration in the comparative example. [Figure 13B] FIG. 13B shows a result of an electric field simulation performed on the dielectric heating configuration of the freezing / thawing compartment in the refrigerator according to the first embodiment. [Figure 14] FIG. 14 shows waveforms of the control signals for the oscillator circuit and damper in the defrosting process in the configuration of embodiment 1, as well as the food temperature, room temperature in the freezing / defrosting compartment, and humidity in the freezing / defrosting compartment at that time. [Figure 15] FIG. 15 is a flowchart showing control after the thawing process is completed in the freezing / thawing compartment in the configuration of the first embodiment. [Figure 16A] FIG. 16A is a waveform diagram showing a cooling operation during frozen storage in a conventional refrigerator. [Figure 16B] FIG. 16B is a waveform diagram showing a cooling operation performed in the freezing / thawing compartment in the refrigerator in accordance with the first embodiment. [Figure 17] FIG. 17 is a waveform diagram showing the state of each element during a rapid cooling operation in the configuration of the first embodiment. [Figure 18A] FIG. 18A is a diagram illustrating an example of the high frequency cutting circuit when the door of the refrigerator in accordance with the first embodiment is opened. [Figure 18B] FIG. 18B is a diagram showing another example of the high frequency cutting circuit when the door of the refrigerator in accordance with the first embodiment is opened. [Figure 18C] FIG. 18C is a diagram showing still another example of the high frequency cutting circuit when the door of the refrigerator in accordance with Embodiment 1 is opened. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] (The knowledge and other information that formed the basis of this disclosure) At the time when the inventors came up with the present disclosure, the refrigerator described in Patent Document 1 was already known. This refrigerator is configured to irradiate frozen items in a high-frequency heating chamber with high-frequency waves from a magnetron via an antenna or the like to heat the frozen items. For this reason, it was difficult to heat the frozen items uniformly and defrost them to a desired state. In addition, because the refrigerator is configured to irradiate frozen items with high-frequency waves from a magnetron to heat them with high-frequency waves, it was necessary to provide a relatively large magnetron and a cooling mechanism for the magnetron, which made it difficult to reduce the size of the refrigerator.

[0008] In view of these problems, the inventors have come up with the subject matter of the present disclosure in order to solve these problems.

[0009] The present disclosure provides a refrigerator that can freeze, store, and thaw stored items in a storage compartment in a desired state, while at the same time achieving a compact size of the device.

[0010] Hereinafter, as an embodiment of the refrigerator of the present disclosure, a refrigerator having a freezing function will be described with reference to the accompanying drawings. Note that the refrigerator of the present disclosure is not limited to the configuration of the refrigerator described in the following embodiment, but can also be applied to a freezer having only a freezing function, and includes various refrigerators and freezers having the technical features described in the following embodiment. Therefore, in this disclosure, a refrigerator refers to a refrigerator having a refrigeration chamber and / or a freezer. Or, it is configured to have a freezer compartment.

[0011] In addition, the numerical values, shapes, configurations, steps, and order of steps shown in the following embodiments are merely examples and do not limit the present disclosure. Among the components in the following embodiments, components that are not described in the independent claims showing the highest concept are described as optional components. In the embodiments, the same elements are given the same symbols even in the modified examples, and descriptions may be omitted. In addition, the drawings are shown in a schematic manner with each component as the main focus, for ease of understanding.

[0012] (Embodiment 1) Hereinafter, a refrigerator according to a first embodiment of the present disclosure will be described with reference to the drawings. Note that in describing the present disclosure, in order to facilitate understanding, each item will be described separately.

[0013] [1-1. Overall configuration of the refrigerator] FIG. 1 is a vertical cross-sectional view of a refrigerator 1 according to the present embodiment.

[0014] 1, the left side is the front side of the refrigerator 1, and the right side is the rear side of the refrigerator 1. The refrigerator 1 is composed of an outer box 3 mainly made of steel plate, an inner box 4 molded from a resin such as ABS (acrylonitrile-butadiene-styrene) resin, and an insulating material 40 (for example, rigid urethane foam) filled and foamed in the space between the outer box 3 and the inner box 4.

[0015] The insulated box 2 of the refrigerator 1 has a plurality of storage compartments, and an openable door is provided at the front opening of each storage compartment. When the door is closed, each storage compartment is sealed so that cold air does not leak. In the refrigerator 1 of the first embodiment, the uppermost storage compartment is the refrigerator compartment 5. Two storage compartments, an ice-making compartment 7 and a freezer / thawing compartment 6, are arranged side by side on both sides directly below the refrigerator compartment 5. A freezer compartment 8 is provided directly below the ice-making compartment 7 and the freezer / thawing compartment 6, and a vegetable compartment 9 is provided at the bottom directly below the freezer compartment 8. Each storage compartment in the refrigerator 1 of the first embodiment has the above-mentioned configuration, but this configuration is one example, and the layout and configuration of each storage compartment can be appropriately changed during design depending on specifications, etc.

[0016] The refrigerator compartment 5 is maintained at a temperature at which food and other preserved items are not frozen, specifically, in the temperature range of 1°C to 5°C, for example. The vegetable compartment 9 is maintained at a temperature equal to or slightly higher than that of the refrigerator compartment 5, specifically, in the temperature range of 2°C to 7°C, for example. The freezer compartment 8 is set to a freezing temperature range for frozen storage, specifically, in the temperature range of -22°C to -15°C, for example. The freezer / thaw compartment 6 is normally maintained at the same freezing temperature range as the freezer compartment 8, and a thawing process is performed to thaw the stored items (frozen items) in response to a thawing command from the user. The configuration of the freezer / thaw compartment 6 and the details of the thawing process will be described later.

[0017] A machine room 10 is provided in the upper part of the refrigerator 1. The machine room 10 houses components constituting the refrigeration cycle, such as a compressor 19 and a dryer that removes moisture in the refrigeration cycle. The location of the machine room 10 is not limited to the upper part of the refrigerator 1, but is appropriately determined depending on the location of the refrigeration cycle, and the machine room 10 may be provided in another area, such as the lower part of the refrigerator 1.

[0018] A cooling compartment 11 is provided behind the freezer compartment 8 and the vegetable compartment 9 in the lower region of the refrigerator 1. The cooling compartment 11 is provided with a cooler 13, which is a component of the refrigeration cycle that generates cold air, and a cooling fan 14 that blows the cold air generated by the cooler 13 to each storage compartment (the refrigerator compartment 5, the freezer / thaw compartment 6, the ice-making compartment 7, the freezer compartment 8, and the vegetable compartment 9). The cool air is supplied to each storage compartment by flowing through air ducts 12 connected to each storage compartment by cooling fan 14. Damper 12a is provided in air ducts 12 connected to each storage compartment. Each storage compartment is maintained at a predetermined temperature range by controlling the rotation speed of compressor 19 and cooling fan 14 and opening / closing control of damper 12a. A defrost heater 15 for defrosting frost or ice adhering to cooler 13 and its surroundings is provided in the lower part of cooling compartment 11. A drain pan 16, a drain tube 17, and an evaporation dish 18 are provided in the lower part of defrost heater 15. These configurations allow moisture generated during defrosting to evaporate.

[0019] The refrigerator 1 of the first embodiment is provided with an operation unit 47 (see FIG. 9 described later). A user can use the operation unit 47 to issue various commands to the refrigerator 1 (for example, temperature setting for each storage compartment, a command to rapidly cool, a command to defrost, or a command to stop making ice, etc.). The operation unit 47 also has a display unit that notifies the occurrence of an abnormality, etc. The refrigerator 1 may be provided with a wireless communication unit and connected to a wireless LAN network, so that various commands can be input from a user's external terminal. The refrigerator 1 may be provided with a voice recognition unit and so that a user can input commands by voice.

[0020] 3, 4, 6, and 7 are vertical cross-sectional views showing the freezing / thawing compartment 6 in the refrigerator 1 of the embodiment 1. The freezing / thawing compartment 6 is a freezer that holds stored items such as food stored therein at a freezing temperature range. When a thawing command for the stored items is input in the refrigerator 1, the freezing / thawing compartment 6 becomes a thawing chamber that performs a thawing process by dielectric heating.

[0021] The features of each of Figures 3, 4, 6, and 7 will be explained again in "1-4. System structure of dielectric heating mechanism" described later.

[0022] In order to maintain the freezing / thawing chamber 6 in the same freezing temperature range as the freezing chamber 8, cold air generated in the cooler 13 flows through air passages 12 provided on the back and top sides of the freezing / thawing chamber 6 and is introduced into the freezing / thawing chamber 6 from a plurality of cold air introduction holes 20 provided on the top surface of the freezing / thawing chamber 6. A damper 12a is provided in the air passage 12 leading from the cooling chamber 11 to the freezing / thawing chamber 6. By controlling the opening and closing of the damper 12a, the freezing / thawing chamber 6 is maintained in a predetermined freezing temperature range and the stored items contained therein are frozen and stored.

[0023] A cold air exhaust hole (not shown) is formed on the back surface of the freezing / thawing compartment 6. The cold air that is introduced into the freezing / thawing compartment 6 and cools the inside of the freezing / thawing compartment 6 returns to the cooling compartment 11 through a return air duct (not shown) from the cold air exhaust hole, and is re-cooled by the cooler 13. That is, the refrigerator 1 of the first embodiment is configured so that the cold air generated by the cooler 13 circulates.

[0024] The top, back, both sides, and bottom constituting the inner surface of the storage space in the freezing / thawing compartment 6 are made of inner surface members 32 (32a to 32c) made of resin material molded from an electrically insulating material. A door 29 is provided at the front opening of the freezing / thawing compartment 6, and the storage space of the freezing / thawing compartment 6 is sealed when the door 29 is closed. In the freezing / thawing compartment 6 of the first embodiment, a storage case 31 with an open top is provided on the back side of the door 29. The storage case 31 is configured to move back and forth simultaneously when the door 29 is opened and closed in the front-rear direction. By opening and closing the door 29 in the front-rear direction, it is easy to put food and other preserved items into and take them out of the storage case 31.

[0025] [1-2. Dielectric heating mechanism for thawing frozen foods] Next, a dielectric heating mechanism that performs dielectric heating to perform a thawing process on the stored object frozen in the freezing / thawing chamber 6 will be described.

[0026] FIG. 9 is a block diagram showing the configuration of the dielectric heating mechanism provided in the refrigerator 1 of the first embodiment. The dielectric heating mechanism in the first embodiment includes an oscillation circuit 22, a matching circuit 23, an oscillation electrode 24, a counter electrode 25, and a control unit 50. The oscillation circuit 22 receives power from a power supply unit 48 and forms a predetermined high-frequency signal. The oscillation circuit 22 is configured using semiconductor elements and is miniaturized. As will be described later, the oscillation circuit 22 is formed on an electrode holding substrate 52 in an electrode holding area 30 (see FIGS. 3, 4, 6, and 7), which is a space on the back side of the freezing / thawing compartment 6, together with the matching circuit 23. The oscillation circuit 22 and the matching circuit 23 serve as a high-frequency power forming unit for forming a high-frequency electric field applied between the oscillation electrode 24 and the counter electrode 25.

[0027] The oscillation electrode 24 is an electrode disposed on the top surface side of the freezing / thawing chamber 6. The counter electrode 25 is an electrode disposed on the bottom surface side of the freezing / thawing chamber 6. The oscillation electrode 24 and the counter electrode 25 are disposed opposite each other across the storage space (thawing space) of the freezing / thawing chamber 6. An electrode holding substrate 52, which will be described later in "1-3. Configuration of the circuit board of the dielectric heating mechanism", and the like are provided, and the opposing distance between the oscillation electrode 24 and the counter electrode 25 is set to a predetermined distance (H in FIG. 8) that has been set in advance. As a result, in the dielectric heating mechanism in the first embodiment, the oscillation electrode 24 and the counter electrode 25 are disposed approximately parallel to each other. In this disclosure, "approximately parallel" refers to an essentially parallel state, but also indicates that it includes errors due to variations in processing accuracy and the like.

[0028] The oscillation electrode 24 is provided on one side of the storage space. The counter electrode 25 is provided on the other side of the storage space, facing the one side with the storage space in between. The matching circuit 23 on the back side, the oscillation electrode 24 on the top side, and the counter electrode 25 on the bottom side, which constitute the dielectric heating mechanism, are covered with an inner surface member 32. This makes it possible to reliably prevent the stored items from burning (Joule heating of food ingredients) due to contact of the stored items with the matching circuit 23, the oscillation electrode 24, or the counter electrode 25.

[0029] In the configuration of the first embodiment, the oscillation electrode 24 is provided on the top surface constituting the storage space of the freezing / thawing chamber 6, and the counter electrode 25 is provided on the bottom surface of the storage space of the freezing / thawing chamber 6. However, the present disclosure is not limited to this configuration. As long as the oscillation electrode 24 and the counter electrode 25 face each other across the storage space (thawing space), the same effect can be achieved even if the oscillation electrode 24 and the counter electrode 25 are arranged upside down compared to the present embodiment, or the oscillation electrode 24 and the counter electrode 25 are arranged to face each other in the left-right direction across the storage space.

[0030] The oscillator circuit 22 outputs a high-frequency voltage (40.68 MHz in the first embodiment) in the VHF (Very High Frequency) band. When the oscillator circuit 22 outputs the high-frequency voltage, an electric field is formed between the oscillator electrode 24 and the counter electrode 25, which are connected to the oscillator circuit 22. As a result, the stored object, which is a dielectric material and is placed in the storage space between the oscillator electrode 24 and the counter electrode 25 in the freezing / thawing chamber 6, is dielectrically heated and thawed.

[0031] The matching circuit 23 adjusts the load impedance formed by the oscillation electrode 24, the counter electrode 25, and the stored object contained in the freezing / thawing chamber 6 so that it matches the output impedance of the oscillation circuit 22. By matching the impedance, the matching circuit 23 minimizes reflected waves for the output high frequency wave.

[0032] The dielectric heating mechanism in this embodiment is provided with an incident and reflected wave detection unit 51 that detects the incident wave output from the oscillation circuit 22 to the oscillation electrode 24 and the reflected wave returning from the oscillation electrode 24 to the oscillation circuit 22. The oscillation circuit 22 is electrically connected to the oscillation electrode 24 via the incident and reflected wave detection unit 51 and the matching circuit 23. The control unit 50 controls the incident and reflected wave detection unit 51 to detect Based on the incident wave and reflected wave output, the ratio (reflectance) of the reflected wave output to the incident wave output is calculated, and various controls are performed based on the calculation results, as described below. Note that the ratio (reflectance) of the reflected wave output to the electromagnetic wave output may be calculated based on the set value of the high frequency power output from the oscillator circuit 22 after impedance matching in the matching circuit 23 and the reflected wave detected by the incident and reflected wave detection unit 51. Note that the various controls described below may be performed using only the reflected wave output, regardless of the set value of the electromagnetic wave output or the detected value of the incident wave.

[0033] As shown in the control block diagram of Fig. 9, in the dielectric heating mechanism, a control unit 50 drives and controls the oscillation circuit 22 and the matching circuit 23 based on signals from an operation unit 47 where a user performs setting operations and a temperature sensor 49 that detects the inside temperature, etc. The control unit 50 is composed of a CPU, and executes control programs stored in a memory such as a ROM to perform various controls.

[0034] [1-3. Configuration of the circuit board for the dielectric heating mechanism] It is desirable that the length of the positive electrode side wiring connecting the oscillation circuit 22, the incident and reflected wave detection unit 51, the matching circuit 23, and the oscillation electrode 24 is short in order to improve reliability. For this reason, in this embodiment, the electrode holding substrate 52 (see Figs. 3, 4, 6, and 7) including these circuits is directly connected to the oscillation electrode 24, and the electrode holding substrate 52 is directly connected to the counter electrode 25 without using a lead wire or a coaxial cable. The electrode holding substrate 52 is disposed in the electrode holding area 30 on the rear side of the freezing / thawing chamber 6. The electrode holding substrate 52 includes at least the matching circuit 23.

[0035] In order to accurately determine whether impedance matching is sufficient by the matching circuit 23, an incident and reflected wave detection unit 51 is configured on an electrode holding substrate 52. It is desirable to combine the incident and reflected wave detection unit 51 and the matching circuit 23 on a single substrate. This eliminates the need to place lead wires or coaxial cables, and connectors for connecting the lead wires or coaxial cables, between the matching circuit 23 and the incident and reflected wave detection unit 51. This also makes it possible to simplify the structure of the circuit substrate.

[0036] 9, the incident and reflected wave detection unit 51 and the matching circuit 23 are disposed on an electrode holding substrate 52. However, the matching circuit 23, the incident and reflected wave detection unit 51, and the oscillator circuit 22 may all be configured on a single substrate. This makes it possible to suppress the transmission loss caused by the lead wires or coaxial cables, and also to improve the accuracy of impedance matching.

[0037] Note that the above-mentioned circuits, for example, oscillator circuit 22 and matching circuit 23, may be configured separately and electrically connected by lead wires or coaxial cables, etc. In such a case, it is possible to realize a rational arrangement configuration that utilizes the free space in the refrigerator, for example, by installing oscillator circuit 22 in machine room 10 having a large free space.

[0038] [1-4. System structure of dielectric heating mechanism] In the dielectric heating mechanism in the first embodiment configured as described above, the oscillation electrode 24 and the counter electrode 25 face each other in a substantially parallel manner. This makes it possible to homogenize the electric field in the thawing space, which is the storage space of the freezing / thawing chamber 6. In order to dispose the oscillation electrode 24 and the counter electrode 25 in a substantially parallel manner with a predetermined gap (H in FIG. 8) therebetween, in the dielectric heating mechanism in the first embodiment, the electrode gap is maintained as described below.

[0039] Fig. 8 is a diagram showing the electrode holding area 30 on the rear side of the freezing / thawing chamber 6 in the first embodiment, and shows an electrode holding mechanism in the electrode holding area 30. Fig. 8 is a diagram showing the electrode holding area 30 as viewed from the rear side, with the oscillation electrode 24 disposed on the upper side (top side) and the counter electrode 25 disposed on the lower side (bottom side). Positive terminals 24a, 24b are provided at the rear end of the oscillation electrode 24. Positive electrode terminals 24a to 24c are bent at right angles from the rear end of the oscillation electrode 24 upward (top surface side) or downward (bottom surface side) and protrude from the rear end. Similarly, cathode terminals 25a, 25b, 25c are protruded from the center of the rear end of the counter electrode 25. Cathode terminals 25a to 25c are bent at right angles from the rear end of the counter electrode 25 upward (top surface side) or downward (bottom surface side) and protrude from the rear end.

[0040] The oscillation electrode 24 and the counter electrode 25 are fixed to the upper and lower parts of the electrode holding substrate 52, respectively. The matching circuit 23 and the incident and reflected wave detector 51 are fixed on the electrode holding substrate 52. The oscillation electrode 24 and the counter electrode 25 are securely held by the electrode holding substrate 52. In this manner, the electrode holding substrate 52 securely holds the oscillation electrode 24 and the counter electrode 25 with a predetermined distance (H in FIG. 8) between them. The electrode holding substrate 52 has a high rigidity due to the copper foil wiring pattern, since the matching circuit 23 and the like are configured on the electrode holding substrate 52. Therefore, the electrode holding substrate 52 can hold each of the oscillation electrode 24 and the counter electrode 25 in a cantilever manner with a predetermined opposing distance (H in FIG. 8) between the oscillation electrode 24 and the counter electrode 25. As described above, the electrode holding substrate 52 may further be provided with the oscillation circuit 22 and the like.

[0041] The positive terminals 24a to 24c of the oscillation electrode 24 and the cathode terminals 25a to 25c of the counter electrode 25 are connected to the positive and cathode side connection terminals of the matching circuit 23. The connection between the positive terminals 24a to 24c and the cathode terminals 25a to 25c and the connection terminals of the matching circuit 23 is a surface-contact connection having a predetermined contact area so as to ensure reliability even when a large current flows. In the first embodiment, in order to ensure a reliable surface-contact connection, the flat terminals are connected to each other by screwing. Note that the connection between the terminals may be made by any connection means that provides a reliable surface-contact connection, and is not limited to a screw connection.

[0042] In Embodiment 1, the terminal widths w (see FIG. 8) of the positive electrode terminals 24a to 24c protruding from the back-side end portion of the oscillation electrode 24 are configured to be narrower than the electrode width W (see FIG. 8) of the back-side end portion of the oscillation electrode 24 (w < W). This is to make it difficult for the heat generated in the matching circuit 23 to conduct to the oscillation electrode 24, and to suppress the dew condensation of the matching circuit 23 during cooling of the oscillation electrode 24 by suppressing the heat conduction between the matching circuit 23 and the oscillation electrode 24. Note that also in the counter electrode 25, the terminal widths of the cathode terminals 25a to 25c are formed narrower than the electrode width of the back-side end portion of the counter electrode 25 from which the cathode terminals 25a to 25c protrude, similar to the terminal widths of the positive electrode terminals 24a to 24c. By narrowing the terminal widths of the cathode terminals 25a to 25c in this way, the heat conduction between the counter electrode 25 and the matching circuit 23 is suppressed.

[0043] Note that in the configuration where the oscillation circuit 22 is disposed in the electrode holding region 30, a heat sink, which is a heat radiating member, may be provided for the oscillation circuit 22, and a cooling configuration may be adopted in which the heat sink is brought into contact with the air passage 12 for cooling.

[0044] As described above, on the back side of the refrigerating / freezing chamber 6, an electrode holding substrate 52 is provided as an electrode holding mechanism. For this reason, the oscillation electrode 24 and the counter electrode 25 are configured to face each other substantially in parallel. Further, in Embodiment 1, in order to make it more certain that the oscillation electrode 24 and the counter electrode 25 face each other substantially in parallel, they are configured as a high-frequency heating module 53a. The high-frequency heating module 53a includes the oscillation electrode 24, the counter electrode 25, and the electrode holding substrate 52, and is integrated in a state where the oscillation electrode 24 and the counter electrode 25 are substantially parallel, and is incorporated into the refrigerating / freezing chamber 6.

[0045] [1-5. Structure of Refrigerating / Freezing Chamber] As described above, the heat-insulating box body 2 of the refrigerator 1 is composed of an outer box 3 formed of a steel plate, an inner box 4 formed of a resin, and a heat insulating material 40 (for example, rigid foamed urethane) filled and foamed in the space between the outer box 3 and the inner box 4.

[0046] As shown in Figs. 2 and 3, the freezing / thawing compartment 6 is configured with an inner surface member 32a inside the heat insulating material 40 as an outer frame. The outside of the freezing / thawing compartment 6 is covered with an electromagnetic wave shield 26 (26a to 26d). This electromagnetic wave shield 26 is provided so as to surround the freezing / thawing compartment 6 in order to prevent electromagnetic waves from leaking outside the refrigerator 1. The electrode holding area 30 is separated from the freezing / thawing compartment 6 by the inner surface member 32a. A rear-side electromagnetic wave shield 26b is provided on the rear side of the inner surface member 32a. The main purpose of the rear-side electromagnetic wave shield 26b is to prevent mutual influence regarding impedance and electric field by separating the interior of the freezing / thawing compartment 6 from the electrode holding board 52 including the matching circuit 23 and the like.

[0047] A flat inner member 32b is provided horizontally at the top of the space surrounded by the inner member 32a, and the oscillation electrode 24 is mounted on the upper side of the inner member 32b. A flat inner member 32c is provided horizontally at the bottom of the space surrounded by the inner member 32a, and the counter electrode 25 is provided on the lower surface of the inner member 32c. The lower surface of the inner member 32c and the inner member 32b are held substantially parallel to each other at a predetermined distance (H in FIG. 8). Therefore, the oscillation electrode 24 and the counter electrode 25 are held substantially parallel by the electrode holding substrate 52 and the inner members 32a, 32b, and 32c. The outer box 3 may be insufficiently parallel to the upper and bottom surfaces of the interior due to foaming variations in the filled and foamed insulation material 40. However, the above-mentioned configuration allows the oscillation electrode 24 and the counter electrode 25 to be precisely and reliably held substantially parallel to each other without being affected by foaming.

[0048] The high-frequency heating module 53a is pre-assembled, and in the manufacturing process of the refrigerator 1, the high-frequency heating module 53a is incorporated by being inserted into the outer box 3 of the refrigerator 1, as shown in Fig. 4. Furthermore, the door unit including the door 29, the door-side electromagnetic shield 26d, the gasket 36, the storage case 31, etc. is inserted into the high-frequency heating module 53a to complete the refrigerator.

[0049] Alternatively, the refrigerator may have the configurations shown in Figures 5, 6 and 7. In Figures 5, 6 and 7, the outer box 3 of the refrigerator 1, the inner box 4 molded from resin, the heat insulating material 40 foamed and filled in the space between the outer box 3 and the inner box 4, the inner surface members 32 (32a to 32c) inside the heat insulating material 40 configured as the outer frame of the freezing / thawing compartment 6, and the electromagnetic wave shield 26 outside the inner surface member 32 have the same configurations as those in Figures 2 and 3.

[0050] A flat inner surface member 32b is provided in the upper portion of the space surrounded by the inner surface member 32a and extends in the horizontal direction. An oscillation electrode 24 is mounted on the upper side of the inner surface member 32b. Similarly, a flat inner surface member 32c is provided in the lower portion of the space surrounded by the inner surface member 32a and extends in the horizontal direction. A counter electrode 25 is provided on the lower surface of the inner surface member 32c. The front sides of the inner surface member 32b and the inner surface member 32c are fixed by supports 54. The rear sides of the inner surface member 32b and the inner surface member 32c are fixed by an electrode holding substrate 52 and the inner surface member 32a, and the oscillation electrode 24 and the counter electrode 25 are held in a substantially parallel state.

[0051] Since the inner surface members 32b and 32c are held substantially parallel at a predetermined distance (H in FIG. 8), the oscillation electrode 24 and the counter electrode 25 can be held substantially parallel by the electrode holding substrate 52, the support 54, and the inner surface members 32b and 32c. The outer box 3 of the refrigerator 1 may have insufficient parallelism between the interior top and bottom surfaces due to foaming variations in the foamed insulating material 40. However, with the above-mentioned configuration, the oscillation electrode 24 and the counter electrode 25 can be precisely and reliably held substantially parallel without being affected by foaming.

[0052] In the above-mentioned configuration, the high-frequency heating module 53a is an integrated device including the oscillation electrode 24, the counter electrode 25, the inner surface members 32a, 32b, 32c, the support 54, the back-side electromagnetic shield 26b that separates the electrode holding area 30 from the freezing / thawing compartment 6, and the matching circuit 23. The high-frequency heating module 53a is pre-assembled, and is incorporated in the manufacturing process by being inserted into the outer box 3 of the refrigerator 1, as shown in Fig. 4. Furthermore, a door unit including the door 29, the door-side electromagnetic shield 26d, the gasket 36, the storage case 31, etc. is inserted into the high-frequency heating module 53a to complete the refrigerator 1.

[0053] The inner surface members 32a-32c are preferably made of a material having a thermal conductivity of 10 W / (m·k) or less, which is a typical industrial ceramic material that is unlikely to cause condensation even in a freezer environment. In this embodiment, the inner surface members 32a-32c are made of a resin material such as polypropylene, ABS resin, or polycarbonate. The electromagnetic wave shield 26 (26a-26d) is configured to be thinner than the inner surface members 32 (32a-32c), thereby suppressing the heat capacity. This makes it possible to prevent condensation on the electromagnetic wave shield 26 and the inner surface members 32 (32a-32c) that are in contact with the electromagnetic wave shield 26.

[0054] In this way, in the refrigerator 1 of the first embodiment, the electrode holding mechanism is provided on the back side and the front side or the side side of the dielectric heating mechanism of the freezing / thawing compartment 6. Therefore, the oscillation electrode 24 and the counter electrode 25 can be arranged with a precise opposing distance from each other. Therefore, the oscillation electrode 24 and the counter electrode 25 can be arranged reliably and substantially parallel with a predetermined distance (H in FIG. 8). As a result, the dielectric heating mechanism of the freezing / thawing compartment 6 prevents the high-frequency electric field from being biased on the electrode surface and homogenizes the high-frequency electric field, so that the thawing process of the stored items (frozen items) can be performed uniformly. In addition, the refrigerator is completed by inserting a unit preassembled as a high-frequency heating module, so there is no need to perform manufacturing work in a narrow refrigerator, and the manufacturing process is simplified.

[0055] [1-6. Electromagnetic wave shielding mechanism] As described above, in freezing / thawing compartment 6, the dielectric object is placed in the atmosphere of the high-frequency electric field between oscillating electrode 24 and counter electrode 25 and dielectrically heated. For this reason, electromagnetic waves are emitted in freezing / thawing compartment 6. In order to prevent these electromagnetic waves from leaking outside refrigerator 1, refrigerator 1 of embodiment 1 is provided with an electromagnetic wave shielding mechanism surrounding freezing / thawing compartment 6.

[0056] 2 and 3, a top-side electromagnetic wave shield 26a is disposed in the air passage 12 portion on the top side of the freezing / thawing compartment 6. The top-side electromagnetic wave shield 26a is disposed on the lower surface of the heat insulating material 40 constituting the bottom side of the refrigeration compartment 5 (see FIG. 1) directly above the freezing / thawing compartment 6, and is disposed so as to cover the top side of the freezing / thawing compartment 6. The top-side electromagnetic wave shield 26a has a plurality of openings, and is configured so as to reduce the substantial opposing area with respect to the oscillation electrode 24.

[0057] In this embodiment, the opening is shaped like a slit whose longitudinal direction is from the rear side to the front side. Analysis by electromagnetic wave simulation has revealed that the opening in the top-side electromagnetic shield 26a allows the magnetic field (current) generated from the positive terminals 24a to 24c toward the front side to pass smoothly over the top-side electromagnetic shield 26a, thereby suppressing the leakage magnetic field diffusing to the surroundings.

[0058] The top surface side electromagnetic wave shield 26a configured in this manner suppresses the generation of an unnecessary electric field between the top surface side electromagnetic wave shield 26a and the oscillation electrode 24. The top surface side electromagnetic wave shield 26a may have a mesh structure having a plurality of openings. 26a may be provided inside the refrigerator compartment 5 located immediately above the freezing / thawing compartment 6. The refrigerator compartment 5 often has a partial compartment or a chilled compartment, and the top surface of the partial compartment or the chilled compartment may be used as an electromagnetic wave shield.

[0059] A rear electromagnetic shield 26b is disposed so as to cover an electrode holding area 30 provided on the rear side of the freezing / thawing chamber 6. The matching circuit 23 and the like are disposed in this electrode holding area 30. By providing the rear electromagnetic shield 26b in this manner, the electric field generated between the oscillation electrode 24 and the counter electrode 25 and the high-frequency noise generated from the matching circuit 23 are prevented from affecting the operation (control) of the electrical components of the cooling fan 14 and the damper 12a. An electromagnetic shield (not shown) is also disposed on the side of the freezing / thawing chamber 6.

[0060] Next, the door-side electromagnetic shield 26d provided on the door 29 that opens and closes the front opening of the freezing / thawing compartment 6 will be described. The door 29 is configured to open and close relative to the body of the refrigerator 1. For this reason, if the electromagnetic shield provided on the door 29 is configured to be connected to the grounded part of the body of the refrigerator 1 by a wired path, the wired path will repeatedly expand and contract as the door 29 opens and closes, and metal fatigue will accumulate in the wired path. In such a connected configuration, there is a risk of the wired path being broken. Therefore, a configuration in which the door-side electromagnetic shield 26d provided on the door 29 is connected to the grounded part of the body of the refrigerator 1 by a wired path is not preferable.

[0061] In general, to prevent electromagnetic wave leakage, it is necessary to make the distance between the door-side electromagnetic shield 26d and the cross rail 21 (connected to the outer case 3 and shown in FIG. 1) which serves as the electromagnetic shield on the body side of the refrigerator 1 shorter than ¼ of the wavelength λ of the electromagnetic wave when the door 29 is closed. In the first embodiment, the distance between the door-side electromagnetic shield 26d and the cross rail 21 is further reduced so that the grounding effect of the electromagnetic shield can be obtained without providing a wired path between the door-side electromagnetic shield 26d and the cross rail 21. For example, the distance between the door-side electromagnetic shield 26d and the cross rail 21 when the door 29 is closed is set to 30 mm or less. Since the cross rail 21 connected to the outer case 3 is grounded, the door-side electromagnetic shield 26d and the cross rail 21 are brought close to each other when the door 29 is closed, and thus an effect equivalent to grounding by a wired path can be obtained. Note that the end of the door-side electromagnetic shield 26d is bent toward the body side of the refrigerator 1, so that the door-side electromagnetic shield 26d can be easily brought close to the cross rail 21.

[0062] The door-side electromagnetic wave shield 26d may be arranged close to something other than the cross rail 21, for example, the electromagnetic wave shield 26 (26a, 26c).

[0063] Next, the connection of the electromagnetic shield and other circuits to the ground will be described.

[0064] FIG. 10 is a schematic circuit diagram of an AC (alternating current) / DC (direct current) converter that drives various circuits. In this circuit, a flyback type switching power supply circuit is used as a DC / DC converter arranged after a bridge diode BD1 and a rectifying capacitor C0 that rectify the AC commercial power supply ACV. However, the DC / DC converter is not limited to this, and any switching power supply that uses a transformer, such as a forward type, a push-pull type, or a half-bridge type, may be used. In the circuit of FIG. 10, only the main circuit components are shown, and a noise filter, a power supply control circuit, a protection circuit, etc. are omitted.

[0065] The AC commercial power supply ACV is converted to DC by the bridge diode BD1 and the rectifier capacitor C0, and this is called the primary DC power supply DCV0 (first power supply part). The zero volt reference potential of this primary DC power supply DCV0 is the primary ground GND0 (first ground part). .

[0066] The primary DC power supply DCV0 is applied to the primary winding P1 of the switching transformer T1, and is switched at a frequency of several tens of kHz by a FET (Field effect transistor) Q1. The power stored in the primary winding P1 is transferred to the electrically insulated secondary winding S1 by electromagnetic induction, and is rectified by the secondary rectifier diode D1 and the secondary rectifier capacitor C1 to output the secondary DC power supply DCV1. The secondary winding S2 has an output section between both ends of the winding, and is rectified by the secondary rectifier diode D2 and the secondary rectifier capacitor C2 to output a secondary DC power supply DCV2 with a voltage lower than that of the secondary DC power supply DCV1. The zero volt reference potential of these secondary DC power supplies DCV1 and DCV2 (second power supply section) is set as the secondary ground GND1 (second ground section).

[0067] In addition to being applied to the switching transformer T1, the primary DC power supply DCV0 is also branched and applied to the primary winding P2 of the switching transformer T2, and is switched at a frequency of several tens of kHz by the FET Q2. The power stored in the primary winding P2 is transferred to the electrically insulated secondary winding S3 by electromagnetic induction, and is rectified by the secondary rectifier diode D3 and secondary rectifier capacitor C3 to output the secondary DC power supply DCV3 (third power supply section). The zero volt reference potential of this secondary DC power supply DCV3 is set as the secondary ground GND2 (third ground section).

[0068] The insulation between the primary winding P1 and secondary winding S1 in the switching transformer T1, and the insulation between the primary winding P2 and secondary winding S3 in the switching transformer T2 shall have insulation performance equal to or higher than the basic insulation specified in Japan's Electrical Appliance and Material Safety Act or IEC (International Electrotechnical Commission) standards.

[0069] 9, in the oscillator circuit 22, a weak power of 40.68 MHz assigned to the ISM (Industrial, Scientific and Medical) band is output by an oscillator source 22a using a crystal or the like, and the weak power is slightly amplified by a first amplifier circuit 22b, and then further amplified by a second amplifier circuit 22c and output toward the matching circuit 23. The output frequency of the oscillator source 22a is not limited to 40.68 MHz.

[0070] In this embodiment, the secondary side DC power supply DCV1 is supplied to the second amplifier circuit 22c in the oscillator circuit 22, the secondary side DC power supply DCV2 is supplied to the oscillation source 22a and the first amplifier circuit 22b in the oscillator circuit 22, the incident and reflected wave detection unit 51 and the matching circuit 23, and the secondary side DC power supply DCV3 is supplied to the control unit 50.

[0071] As a result, a circuit system in which the secondary ground GND1 is set to a zero volt reference potential comprises the oscillator circuit 22, the incident and reflected wave detector 51, the matching circuit 23, and the counter electrode 25. In addition, a circuit system in which the secondary ground GND2 is set to a zero volt reference potential comprises the controller 50.

[0072] Each of the electromagnetic shields 26 (top-side electromagnetic shield 26a, bottom-side electromagnetic shield 26c, back-side electromagnetic shield 26b, and door-side electromagnetic shield 26d) is desirably insulated from the counter electrode 25 (same potential as the secondary ground GND1), or if not insulated, is connected at a location at least a certain distance away from the counter electrode 25. This reduces the electric and magnetic fields applied to each electromagnetic shield and also suppresses leakage to the outside. In other words, the effectiveness of the electromagnetic shielding is increased.

[0073] There are several ways to improve the effectiveness of electromagnetic shielding, which are described below.

[0074] One is to not connect each electromagnetic shield to any of the primary ground GND0, secondary ground GND1, and secondary ground GND2. This method is particularly effective when the total area or volume of the electromagnetic shields is equal to or greater than a certain level, and it can prevent high frequencies from leaking to the outside through the ground line and causing adverse effects as noise.

[0075] The other is a means for connecting each electromagnetic shield to the primary ground GND0. The primary ground GND0 is usually connected to the outer box 3 made of a metal material, and has a large ground surface area. Therefore, since the zero volt reference potential of the primary ground GND0 is the most stable, connecting each electromagnetic shield to the primary ground GND0 not only enhances the effect of each electromagnetic shield, but also suppresses malfunctions due to noise.

[0076] The other is a means for connecting each electromagnetic shield to the secondary ground GND2. Since the counter electrode 25 and each electromagnetic shield are insulated at two stages, that is, by the switching transformers T1 and T2, high-frequency noise is less likely to leak from the oscillation electrode 24 to each electromagnetic shield, and the electric field generation between the oscillation electrode 24 and the counter electrode 25 is stabilized.

[0077] The other is a means for connecting each electromagnetic shield to the secondary ground GND1, while connecting it at a location at least a certain distance from the counter electrode 25, at least outside each electromagnetic shield. This can provide a certain shielding effect, and makes it difficult for high-frequency noise to leak from the oscillation electrode 24 to each electromagnetic shield, stabilizing the generation of an electric field between the oscillation electrode 24 and the counter electrode 25.

[0078] The effectiveness of the above-mentioned means for enhancing the shielding effect may vary depending on the system structure and wiring, etc., so it is necessary to select the most suitable one taking into consideration the efficiency of electric field generation from the oscillation electrode 24 to the counter electrode 25, the electromagnetic wave shielding effect, etc.

[0079] In the refrigerator 1 of the first embodiment, since the outer box 3 is made of a steel plate, the steel plate itself functions as an electromagnetic wave shield. Therefore, the electromagnetic waves inside the refrigerator 1 are reliably prevented from leaking to the outside of the refrigerator 1.

[0080] [1-7. Configuration of the oscillating electrode and the counter electrode and the thawing performance according to said configuration] FIG. 11 is a plan view of the oscillation electrode 24 and the counter electrode 25 on the top surface side of the freezing / thawing chamber 6, as viewed from above.

[0081] As shown in Fig. 11, the size of the oscillation electrode 24 is configured to have an area slightly smaller than that of the counter electrode 25. A plurality of electrode holes 41, 42 are formed in the oscillation electrode 24 and the counter electrode 25, respectively. The plurality of electrode holes 41, 42 are shaped like vertically long slits extending from the interior back side toward the front side, where the positive electrode terminals 24a to 24c and the cathode terminals 25a to 25c of the counter electrode 25 are provided. This shape allows the high-frequency current input from the positive electrode terminals 24a to 24c to easily flow from the interior back side toward the front side, and the electric field strength generated between the two electrodes is slightly strengthened.

[0082] In this embodiment, as shown in Fig. 11, the electrode holes 41, 42 provided in the oscillation electrode 24 and the counter electrode 25 are not arranged in vertically symmetrical positions, but are arranged in positions offset from each other by approximately half the minor axis of the electrode hole 41. Since multiple electrode holes 41 are formed on the electrode surface of the oscillation electrode 24, the regions in which a strong electric field is formed on the electrode surface of the oscillation electrode 24 are uniformly distributed. This makes it possible to uniformly perform dielectric heating on the stored object. In other words, the edge of the opening of the electrode hole 41 becomes the electric field concentration region.

[0083] 11 are merely examples, and the shapes and arrangements of the electrode holes 41, 42 are appropriately designed in consideration of efficiency and manufacturing costs according to the specifications and configuration of the refrigerator. For example, the shapes of the electrode holes 41, 42 may be perfect circles. It is preferable that the electrode holes 41 of the oscillation electrode 24 and the counter electrode 25 are not symmetrical in the vertical direction but are shifted from each other by about half the hole diameter.

[0084] In the configuration of the first embodiment, the shape and arrangement of the electrode holes 41 of the oscillation electrode 24 are described as a configuration in which a plurality of electrode holes 41 are arranged, but the present disclosure is not limited to such a configuration. For example, the oscillation electrode 24 may have a shape in which at least one opening portion is formed. In this case, on the electrode surface of the oscillation electrode 24, the edge of the opening portion becomes an electric field concentration region in which the electric field is concentrated. In the present disclosure, it is sufficient that the electric field concentration region is dispersed on the electrode surface of the oscillation electrode 24. In the first embodiment, the configuration in which a plurality of electrode holes 42 are provided on the electrode surface of the counter electrode 25 is described, but the present disclosure is not limited to such a configuration. In other words, it is sufficient that an opening is formed in the counter electrode 25 so that a desired electric field is formed between the electrode and the oscillation electrode 24.

[0085] The electrode holding substrate 52 is configured to reliably hold the oscillation electrode 24 and the counter electrode 25 with a predetermined distance (H in FIG. 8) between them. In this embodiment, the electrode spacing H is shorter than the long side dimension (D in FIG. 11) of the oscillation electrode 24. Note that it is preferable to configure the electrode spacing H to be shorter than the diameter of the oscillation electrode when it is circular, or shorter than the major axis of the oscillation electrode when it is elliptical.

[0086] Fig. 12 shows the relationship between the electrode spacing H (see Fig. 8) between the oscillation electrode 24 and the counter electrode 25, and the electric field strength between the two electrodes. As shown in Fig. 12, the wider the electrode spacing H, the weaker the electric field strength tends to be. In particular, when the electrode spacing exceeds H1 (100 mm), the electric field strength drops significantly, and when the electrode spacing exceeds H2 (125 mm), the electric field strength drops to a level where high-frequency heating is not possible. For these reasons, it is desirable for the electrode spacing H to be 100 mm or less, and it must be at least 125 mm or less.

[0087] The inventors have conducted a simulation of electric field generation between electrodes using a freezing / thawing chamber 6 having the electrode configuration of embodiment 1 and, as a comparative example, a freezing / thawing chamber 6 having an electrode configuration provided with a counter electrode 25 that does not have an electrode hole.

[0088] Fig. 13A is a diagram showing the simulation results for an electrode configuration with an oscillation electrode 24 or a counter electrode 25 that does not have an electrode hole. Fig. 13B is a diagram showing the simulation results for an electrode configuration with an oscillation electrode 24 or a counter electrode 25 that has an electrode hole. In Figs. 13A and 13B, the darker parts are areas where the electric field is concentrated. As is clear from these electric field simulation diagrams, it can be seen that, compared to the electric field simulation diagram of Fig. 13A, the electric field concentration is alleviated over the entire electrode in the electric field simulation diagram of the dielectric heating configuration in Fig. 13B, and the electric field is made uniform.

[0089] 11, the electrode holes 41 of the oscillation electrode 24 and the electrode holes 42 of the counter electrode 25 are arranged so that the central axes of the electrode holes extending in the vertical direction (opposing direction) do not coincide, thereby alleviating electric field concentration in the entire electrode. In addition, in an electrode configuration in which the electrode holes 41 of the oscillation electrode 24 and the electrode holes 42 of the counter electrode 25 are arranged so that the central axes of the electrode holes extending in the vertical direction (opposing direction) coincide, electric field concentration is alleviated compared to a configuration using a counter electrode 25 that does not have an electrode hole, and electric field concentration is particularly alleviated at corner portions.

[0090] In the freezing / thawing compartment 6 of the refrigerator 1 according to the first embodiment, as shown in FIG. 2 and FIG. 3, a storage case 31 is fixed to the rear side of the door 29. The storage case 31 moves back and forth inside the freezing / thawing chamber 6. In the configuration of the first embodiment, rails are provided on the inside of both sides of the freezing / thawing chamber 6 so that the storage case 31 can move smoothly inside the freezing / thawing chamber 6. Sliding members that slide on the rails are provided on both sides of the outside of the storage case 31. These rails and the sliding members of the frame (storage case 31) are provided at positions outside the dielectric heating region, which is the region where the oscillation electrode 24 and the counter electrode 25 of the freezing / thawing chamber 6 face each other, so as to prevent dielectric heating.

[0091] [1-8. Decompression process] In the refrigerator 1 of the first embodiment, when a defrost command is input, a defrosting process is performed on a stored item (frozen item) placed between the oscillation electrode 24 and the counter electrode 25 in the freezing / defrosting compartment 6. In the defrosting process of the first embodiment, as described below, the control unit 50 controls the dielectric heating mechanism having the oscillation circuit 22, the incident and reflected wave detection unit 51, and the matching circuit 23, and also controls the cooling mechanism including a refrigeration cycle such as the compressor 19 and the cooler 13, and the cold air introduction mechanism including the cooling fan 14, the damper 12a, etc.

[0092] In the thawing process in the first embodiment, a predetermined high-frequency voltage is applied between the oscillation electrode 24 and the counter electrode 25, and the frozen goods, which are dielectrics, are dielectrically heated by the high-frequency electric field generated between the electrodes. During this dielectric heating, the control unit 50 controls the opening and closing of the damper 12a to intermittently introduce cold air. Figure 14 shows the waveforms of the control signals for the dielectric heating mechanism (oscillating circuit 22) and the cold air introduction mechanism (damper 12a) during the thawing process, as well as the food temperature, the room temperature of the freezing / thawing compartment 6, and the humidity of the freezing / thawing compartment 6 at that time.

[0093] In the case of a configuration in which VHF waves are used for the thawing process, the frequency characteristics make it less likely for "partial cooking" to occur than in the case of a configuration in which microwaves are used. In the refrigerator 1 of the first embodiment, in order to further improve the uniformity of thawing, an electrode holding substrate 52 is provided, and the oscillation electrode 24 and the counter electrode 25, which are essentially flat plate-like members, are reliably held approximately parallel with a predetermined gap (H in FIG. 8) by the electrode holding substrate 52.

[0094] As shown in FIG. 14, in the thawing process, when a thawing command is input (thawing start), the oscillator circuit 22 is turned on, and a high-frequency voltage of, for example, 40.68 MHz is applied between the oscillator electrode 24 and the counter electrode 25. At this time, the damper 12a is in an open state, so that the room temperature in the freezing / thawing compartment 6 is maintained at the freezing temperature t1 (for example, -20°C). The damper 12a is closed after a predetermined period has elapsed since the start of thawing. When the damper 12a is closed, the room temperature in the freezing / thawing compartment 6 starts to rise. In the thawing process in the first embodiment, the opening and closing of the damper 12a is controlled at the same time as the dielectric heating is performed, thereby suppressing the rise in the surface temperature of the frozen product, and thawing is performed without causing so-called "partial cooking."

[0095] The control unit 50 controls the opening and closing of the damper 12a based on the ratio (reflectance) of the reflected wave to the incident wave detected by the incident and reflected wave detection unit 51. The incident wave here refers to an electromagnetic wave that is matched by the matching circuit 23 and supplied between the oscillation electrode 24 and the counter electrode 25. When the reflectance increases and reaches a preset threshold, the control unit 50 opens the damper 12a to lower the temperature inside the freezing / thawing chamber 6. In this way, by controlling the opening and closing of the damper 12a, cold air is intermittently introduced into the freezing / thawing chamber 6, so that the stored items in the storage space (thawing space) of the freezing / thawing chamber 6 are dielectrically heated while maintaining a desired frozen state, and are brought to a desired thawed state.

[0096] The thawing process is completed when the stored object reaches the desired thawed state. In order to detect the desired thawed state at which the thawing process is completed, the thawing process of the first embodiment uses reflectance. As the melting of the stored object progresses due to dielectric heating, the amount of melted water molecules increases in the stored object. As the amount of melted water molecules increases in the stored object, the dielectric constant changes, resulting in an increase in the dielectric constant. The impedance matching state becomes misaligned. As a result, the reflectance, which is the ratio of the reflected wave to the output electromagnetic wave, increases. In the decompression process, when the reflectance increases and reaches a preset threshold, the matching circuit 23 performs impedance matching to reduce the reflectance.

[0097] In the thawing process of the first embodiment, the completion of thawing is detected when the reflectance after impedance matching by the matching circuit 23 exceeds a threshold value for the completion of thawing. The threshold value for the completion of thawing is the reflectance when the stored object has melted and reached a desired thawed state. Here, the desired thawed state of the stored object is a state in which a woman can cut the stored object with one hand and the amount of dripping from the stored object is very small. The threshold value for the completion of thawing is a value obtained in advance by experiment.

[0098] 14, by controlling the opening and closing of damper 12a, relatively low-humidity cool air that has passed through air passage 12 is supplied to freezing / thawing chamber 6 from cool air inlet hole 20, so that the humidity in freezing / thawing chamber 6 never reaches 100%. Therefore, condensation in freezing / thawing chamber 6 is prevented.

[0099] The method of calculating the reflectance is not limited to the ratio (reflectance) of the reflected wave to the incident wave detected by the incident and reflected wave detection unit 51. For example, only the reflected wave may be detected by the detection unit, and the reflectance may be calculated as the ratio of the reflected wave to an output preset in the oscillation circuit 22.

[0100] The defrosting process may be controlled without using the reflectance. For example, the defrosting process may be controlled only by the reflected wave detected by the incident reflected wave detection unit 51, regardless of the output. The control using the reflectance described below may also be performed using these methods.

[0101] [1-9. Control after decompression process is completed] Fig. 15 is a flowchart showing control after the thawing process is completed in the freezing / thawing chamber 6. Each step shown in the flowchart in Fig. 15 is performed by a CPU (Central Processing Unit) of the control unit 50 executing a control program stored in a memory such as a ROM (Read Only Memory). As described above, when the reflectance after impedance matching by the matching circuit 23 in the thawing process exceeds the threshold value for the completion of thawing, the control after the completion of the thawing process shown in Fig. 15 is performed.

[0102] As shown in step 101 of Fig. 15, after the thawing process is completed, the stored items are maintained in a desired thawed state. One of the means for achieving this is to set the room temperature of the freezing / thawing chamber 6 to a so-called slightly freezing temperature range, for example, about -1°C to -3°C. Another means is to set the room temperature of the freezing / thawing chamber 6 to a freezing temperature range, for example, -18°C to -20°C, and apply a high-frequency electric field with reduced output or apply a high-frequency electric field intermittently to cool and heat the stored items and maintain them in the desired temperature range.

[0103] When the freezing / thawing chamber 6 is maintained at a slightly freezing temperature, the presence or absence of a stored object in the freezing / thawing chamber 6 is constantly detected (step 102). The presence or absence of a stored object in the freezing / thawing chamber 6 is detected using the reflectance that is constantly detected. For this reason, the matching circuit 23 is always in intermittent operation, and a low-output electromagnetic wave is intermittently output from the oscillation electrode 24. The control unit 50 compares the reflectance with a preset threshold value for the presence or absence of a stored object to determine the presence or absence of a stored object in the freezing / thawing chamber 6.

[0104] In step 102, when it is detected that there is no stored object in the freezing / thawing chamber 6 (No in step 102), it is determined that the stored object in the desired thawed state has been taken out, and the room temperature of the freezing / thawing chamber 6 is set to the freezing temperature range, for example, −18° C. to −20° C. (step 10 5).

[0105] In step 102, when it is detected that a stored item is present in the freezing / thawing compartment 6 (Yes in step 102), it is determined whether the present stored items include new non-frozen items (e.g., room temperature food ingredients). Whether new non-frozen items are present in the freezing / thawing compartment 6 is determined by a change in reflectance. In step 103, when it is determined that a new non-frozen item has been placed in the freezing / thawing compartment 6 (Yes in step 103), the room temperature of the freezing / thawing compartment 6 is set as the freezing temperature zone (step 105).

[0106] On the other hand, in step 103, when it is determined that no new non-frozen product is stored in the freezing / thawing compartment 6 and the thawed stored object is still being held therein (No in step 103), it is determined whether or not the time since the completion of thawing has exceeded a predetermined time (step 104). Even if the thawing process for the stored object is completed, the user may not immediately remove the stored object from the freezing / thawing compartment 6. In such a case, the refrigerator 1 of the first embodiment is configured to maintain the slightly freezing temperature range in which the desired thawed state can be maintained for the stored object in the freezing / thawing compartment 6 for a predetermined time. If the stored object is stored in the freezing / thawing compartment 6 for more than the predetermined time, the refrigerator 1 of the first embodiment controls the room temperature of the freezing / thawing compartment 6 to be shifted to the freezing temperature range in order to maintain the freshness of the stored object. That is, in step 104, when it is determined that the time since the completion of thawing has exceeded a predetermined time while the thawed stored object is still being held therein (Yes in step 104), the process proceeds to step 105, and a freezing process is performed in which the room temperature of the freezing / thawing compartment 6 is set to the freezing temperature range.

[0107] As described above, in the refrigerator 1 of embodiment 1, the stored items can be kept in the desired thawed state in the freezing / thawing compartment 6 for a specified period of time to maintain their freshness after the thawing process is completed, and appropriate temperature control can be performed for the stored items inside the freezing / thawing compartment 6.

[0108] [1-10. Freezing / thawing chamber freezing operation] The refrigerator 1 of the first embodiment is configured to perform dielectric heating so that food, which is a preserved item, is frozen and preserved in a desired state during freezing processing in which the room temperature of the freezing / thawing compartment 6 is maintained within the freezing temperature range. Generally, when food is frozen, frosting occurs on the inner surface of the food packaging due to moisture in the freezing / thawing compartment 6 and moisture inside the food. When such frosting occurs on the surface of the food, the food becomes dry and has a dry texture, and is no longer tasty and fresh ("freezer burn"). To prevent such a condition, the refrigerator 1 of the first embodiment performs a dielectric heating operation together with a cooling operation at the same time.

[0109] Fig. 16A and Fig. 16B are waveform diagrams showing the state of each element during a cooling operation. Fig. 16A is a waveform diagram showing a cooling operation during frozen storage in a conventional refrigerator, and Fig. 16B is a waveform diagram showing a cooling operation performed in freezing / thawing compartment 6 in refrigerator 1 of embodiment 1.

[0110] In FIG. 16A, (1) is a waveform diagram showing ON / OFF of the cooling operation. The ON / OFF of the cooling operation corresponds to, for example, opening and closing of a damper, or ON / OFF operation of a compressor. In FIG. 16A, ON indicates a state in which cold air is introduced into the freezer, and OFF indicates a state in which the damper is closed and the introduction of cold air into the freezer is blocked. Therefore, as shown in the waveform diagram of FIG. 16A (2), the temperature of the food in the freezer will fluctuate greatly above and below the preset freezing temperature T1 (for example, −20° C.). As a result, evaporation of moisture and frosting will occur repeatedly on the surface of the food in the freezer, and the food may not be frozen in a desirable state.

[0111] On the other hand, in FIG. 16B showing the cooling operation of the first embodiment, unlike the conventional cooling operation, The food is cooled and dielectrically heated at the same time. Fig. 16B (1) is a waveform diagram showing the opening and closing operation of damper 12a. ON (on) indicates that damper 12a is open, and cold air passes through air passage 12 and is introduced into freezing / thawing chamber 6 from cold air inlet hole 20. OFF (off) indicates that damper 12a is closed, and the introduction of cold air into freezing / thawing chamber 6 is blocked. In the cooling operation of embodiment 1, cold air is introduced simultaneously with dielectric heating, so the time for introducing cold air is set longer than in the conventional example. That is, the cooling capacity in the cooling operation is increased.

[0112] FIG. 16B (2) is a waveform diagram showing the operating state of dielectric heating under drive control of oscillator circuit 22. When damper 12a is in the open state, dielectric heating is performed at the same time. In the cooling operation in embodiment 1, dielectric heating is performed with a much smaller output than in the thawing operation. As a result, as shown in FIG. 16B (3), the temperature of the food in freezing / thawing compartment 6 is maintained at a preset freezing temperature T1 (e.g., −20° C.), and fluctuations in the food temperature are suppressed.

[0113] Experiments have shown that if the fluctuation in food temperature is about 0.1 K or less, frost formation can be prevented. At the very least, the smaller the fluctuation in food temperature is, the more the occurrence of frost can be suppressed. Furthermore, dielectric heating has the effect of suppressing the growth of ice crystals inside the food. When dielectric heating is performed, an electric field tends to gather at the tips of ice crystals formed inside the food, so that ice crystals only grow slowly even if the temperature inside the freezing / thawing chamber 6 is below the maximum ice crystal formation zone.

[0114] As described above, in refrigerator 1 according to the first embodiment, the dielectric heating operation is performed even during the cooling operation during frozen storage. This makes it possible to freeze and store the frozen goods, which are the preserved goods, in a desired state.

[0115] [1-11. Freezing process] In the refrigerator 1 of the first embodiment, a freezing process can be performed on non-frozen food newly placed in the freezing / thawing compartment 6 based on a user's command from the operation unit 47 (see FIG. 9). FIG. 17 is a waveform diagram showing the state of each element in the rapid cooling operation, which is a freezing process. In FIG. 17, (a) is a graph showing whether or not a preserved item (food) is present in the freezing / thawing compartment 6. The determination of whether or not a preserved item is present in the freezing / thawing compartment 6 is made by the control unit 50 based on the ratio (reflectance) of the reflected wave detected by the incident reflected wave detection unit 51 to the output electromagnetic wave. (b) of FIG. 17 shows that the control unit 50 intermittently acquires information from the matching circuit 23 and the incident reflected wave detection unit 51. (c) of FIG. 17 is a graph showing an example of the transition of the reflectance. When the reflectance becomes equal to or less than the first threshold value R1, the control unit 50 determines that a preserved food item has been placed in the freezing / thawing compartment 6.

[0116] In the rapid cooling operation of food stored in the freezing / thawing compartment 6, the rotation speed of the compressor 19 and the cooling fan 14 of the cooling mechanism is increased to increase the cooling capacity and perform forced continuous operation. In addition, the damper 12a of the air passage 12 leading to the freezing / thawing compartment 6 is forcibly driven in a continuous open state, and the cold air introduction mechanism is driven and controlled so that cold air is introduced into the freezing / thawing compartment 6 (see the waveform diagram in FIG. 17(d)).

[0117] In the rapid cooling operation, a dielectric heating operation is performed to suppress the elongation of ice crystals when the food temperature is in the maximum ice crystal formation zone (approximately -1°C to approximately -5°C). The dielectric heating operation at this time is performed at a low output of approximately 1 W to approximately 10 W, and is performed intermittently (period T in (e) of Figure 17). In order to start the dielectric heating operation, it is detected that the food temperature has entered the maximum ice crystal formation zone. This detection is performed based on an increase in the change in reflectance when the food passes through the latent heat zone. In the first embodiment, the detected reflectance is compared to a preset second threshold When reflectance reaches R2, dielectric heating operation is started (see FIG. 17(e)). Note that the region from the second threshold value R2 to a third threshold value R3, which is lower than the second threshold value R2, is considered to be the maximum ice crystal formation zone for the food, and dielectric heating operation is continued. When a predetermined time (t2) has elapsed since the reflectance reached the third threshold value R3, control unit 50 determines that the food has passed through the maximum ice crystal formation zone, and dielectric heating operation is stopped.

[0118] As described above, when it is determined that the food has passed the maximum ice crystal formation zone, the dielectric heating operation is stopped, and the rapid cooling operation is terminated and the normal cooling operation is started. In this way, even when the rapid cooling operation is performed, the food can be brought to a desired frozen state by performing the dielectric heating operation for a desired period of time.

[0119] [1-12. Safety control by door switch] In this embodiment, as described above, in order to prevent electromagnetic waves from leaking outside of refrigerator 1, electromagnetic wave shield 26 is provided to surround freezing / thawing compartment 6. Furthermore, outer box 3 is made of a steel plate, and this steel plate itself functions as an electromagnetic wave shield, so that leakage of electromagnetic waves to the outside is prevented when door 29 is closed.

[0120] However, when door 29 is open, there is a possibility that electromagnetic waves may leak from the opening. In addition, when a user puts his or her hand inside the refrigerator through the opening, there is a concern that high frequencies may affect the human body, so measures are required.

[0121] Therefore, in this embodiment, when the door 29 is detected to be open by the door opening / closing detection unit 55a (see FIG. 9) that detects the door 29 being open, the oscillation circuit 22 is stopped to stop the power supply to the oscillation electrode 24. It is common for a refrigerator to have multiple doors. Here, when the electromagnetic wave shield 26 is functioning sufficiently, even if the door opening / closing detection unit 55b of the refrigerator compartment 5, the door opening / closing detection unit 55c of the ice-making compartment 7, the door opening / closing detection unit 55d of the freezer compartment 8, or the door opening / closing detection unit 55e of the vegetable compartment 9 detects that the door of a storage compartment other than the freezer / thawing compartment 6 is opened, there is no external leakage of electromagnetic waves above a specified level. Therefore, the oscillation circuit 22 does not stop and continues to operate.

[0122] On the other hand, this does not apply if the electromagnetic wave shield 26 cannot fully surround the freezing / thawing chamber 6 due to design issues.

[0123] For example, in the case where the electromagnetic wave shield 26 cannot be configured on the top surface of the freezing / thawing chamber 6, if the door of a storage chamber (refrigerator chamber 5 in the layout of FIG. 1) located at the top of the freezing / thawing chamber 6 is opened, the oscillation circuit 22 is stopped. In addition, in the case where the electromagnetic wave shield 26 cannot be configured on the bottom surface of the freezing / thawing chamber 6, if the door of a storage chamber (freezer chamber 8 or vegetable chamber 9 in the layout of FIG. 1) located at the bottom of the freezing / thawing chamber 6 is opened, the oscillation circuit 22 is stopped. In addition, in the case where the electromagnetic wave shield 26 cannot be configured on the side surface of the freezing / thawing chamber 6, if the door of a storage chamber (ice chamber 7 in the layout of FIG. 1) located at the side of the freezing / thawing chamber 6 is opened, the oscillation circuit 22 is stopped. In this way, by stopping the oscillation circuit 22 when the door of a storage chamber arranged in a direction in which the electromagnetic wave shield 26 cannot be configured is opened, leakage of electromagnetic waves can be prevented.

[0124] The oscillation circuit 22 can be stopped by the following means.

[0125] 18A shows a means for cutting off the power supply from the power supply unit 48 to the oscillation circuit 22 by the door open / close detection unit 55a. The door open / close detection unit 55a is a switch mechanism that is conductive when the door 29 is closed and cut off when the door 29 is open. When the switch is cut off, the power supply to the oscillation circuit 22 is cut off, thereby reliably stopping the operation of the oscillation circuit 22. .

[0126] Fig. 18B shows a means for stopping the operation of the power supply control unit 48a that controls the power supply unit 48 by the door opening / closing detection unit 55a. The door opening / closing detection unit 55a is a switch mechanism similar to that of Fig. 18A. When the door 29 is opened, the power supply to the power supply control unit 48a is stopped, and the power supply from the power supply unit 48 to the oscillation circuit 22 is also cut off, thereby stopping the operation of the oscillation circuit 22. In the example shown in Fig. 18B, the operation of the oscillation circuit 22 is stopped by cutting off the power supply to the circuit in the power supply control unit 48a, but a means for making the overcurrent protection circuit in the power supply control unit 48a recognize an overcurrent state and stop the operation, or a means for making the power supply unit 48 recognize an overload state and stop the operation may be used.

[0127] 18C shows a configuration in which the open / closed state of the door 29 is determined not only by the door open / close detection unit 55a but also by a magnetic sensor 55f. The magnetic sensor 55f outputs an open / closed signal of the door 29 to the control unit 50. The control unit 50 receives the signal from the magnetic sensor 55f and outputs an operation possible / prohibited signal to the power supply control unit 48a. A door open / close detection unit 55a is further inserted between the magnetic sensor 55f and the control unit 50, and is conductive when the door 29 is closed and is cut off when the door 29 is open. Therefore, when the door 29 is open, no signal is output from the magnetic sensor 55f, and as a result, the operation of the power supply unit 48 is stopped.

[0128] The above-described configuration for turning on / off the power supply or control signal is realized by hardware, and therefore has high resistance to high frequency noise or external noise, making malfunctions unlikely to occur.

[0129] 18B and 18C, door open / close detection unit 55a is a switch mechanism that is conductive when door 29 is closed and cut off when door 29 is open. However, a mechanism that is cut off when door 29 is closed and conductive when door 29 is open may be used. In this case, it is necessary to reverse the H (High) / L (Low) logic for stopping power supply control unit 48a.

[0130] In the refrigerator according to the first embodiment, the freezing / thawing compartment 6 has been described as having both a freezing function and a thawing function, but it may be configured as a thawing compartment having only a thawing function.

[0131] As described above, in the refrigerator of the present disclosure, a high-frequency electric field is generated between the oscillation electrode and the counter electrode to thaw the stored object stored in the storage chamber. This high-frequency electric field is made uniform in the thawing space of the freezing / thawing chamber, and the stored object held in the thawing space can be subjected to desired dielectric heating in the thawing and freezing processes. Therefore, according to the present disclosure, the stored object stored in the storage chamber can be frozen, stored, and thawed in a desired state. Therefore, a refrigerator having highly reliable cooling, storage, and thawing functions can be provided. In other words, it is possible to achieve the excellent effect of being able to freeze and store the stored object in a desired state, and being able to thaw the frozen stored object in a desired state in a short time. In addition, by using a dielectric heating mechanism composed of semiconductor elements, it is possible to achieve a miniaturization of the refrigerator having a thawing function.

[0132] [2-1. Effects, etc.] As described above, the refrigerator in one aspect of the present disclosure comprises at least one storage chamber having a space capable of storing preserved items, an oscillator unit that generates high-frequency power, an oscillator electrode that receives the high-frequency power generated by the oscillator unit and generates an electric field in the storage chamber, and a counter electrode provided opposite the oscillator electrode, and the installation distance between the oscillator electrode and the counter electrode is configured to be shorter than the long side dimension of the oscillator electrode.

[0133] This reduces the concentration of the high-frequency electric field for thawing stored items formed between the oscillation electrode and the counter electrode, and makes the electric field uniform. Therefore, food can be frozen, stored, and thawed in a desired state, and a small refrigerator with reliable cooling and storage functions can be obtained.

[0134] The distance between the oscillation electrode and the counter electrode may be 125 mm or less.

[0135] The distance between the oscillation electrode and the counter electrode may be 100 mm or less.

[0136] Although the present disclosure has been described in detail in the embodiments above, the disclosed contents of the embodiments may vary in details of the configuration, and substitution, combination, and change in order of elements in the embodiments may be realized without departing from the scope and spirit of the present disclosure as claimed. [Industrial Applicability]

[0137] INDUSTRIAL APPLICABILITY The refrigerator of the present disclosure can process stored items so as to achieve each of the desired freezing, storage, and thawing states, and has high market value, such as increased added value, reliability, and safety of the refrigerator, and can therefore be suitably applied to various types of refrigerators. [Explanation of symbols]

[0138] 1. Refrigerator 2. Insulated box 3 Outer box 4 Inner box 5. Refrigerator 6 Freezing / thawing room (storage room) 7 Ice Room 8 Freezer 9 Vegetable compartment 10 Machine room 11 Cooling room 12 Wind path 12a Damper 13 Cooler 14 Cooling fan 15 Defrost heater 16 Drain pan 17 Drain tube 18 Evaporation dish 19 Compressor 20 Cool air intake 21 Crossrail 22 Oscillator circuit (oscillator section) 22a Oscillator source 22b First amplifier circuit 22c Second amplifier circuit 23 Matching circuit (matching section) 24 Oscillation electrode 24a,24b,24c Positive terminal 25 Counter electrode 25a,25b,25c cathode terminal 26 Electromagnetic wave shield (shield part) 26a Top side electromagnetic shield 26b Rear electromagnetic shield 26c Bottom electromagnetic shield 26d Door side electromagnetic shield 29 Door 30 Electrode holding area 31 Storage Case 32a, 32b, 32c Inner surface members 36 Gasket 40 Insulation 41 Electrode hole (oscillating electrode hole) 42 Electrode hole (counter electrode hole) 47 Operation section 48 Power supply section 48a Power supply control unit 49 Temperature Sensor 50 Control section 51 Incident and reflected wave detector 52 Electrode holding board 53a High frequency heating module 54 Post 55a, 55b, 55c, 55d, 55e Door opening / closing detection unit 55f Magnetic Sensor D Long side dimension of oscillation electrode H, H1, H2 installation interval (electrode interval)

Claims

1. A storage chamber having a space capable of storing stored items; An oscillator for generating high frequency power; an oscillation electrode and a counter electrode that receive the high frequency power from the oscillation unit and generate an electric field in the storage chamber; The oscillation electrode and the counter electrode are disposed opposite to each other, an electrode holding substrate that holds the oscillation electrode and the counter electrode, the oscillation electrode and the counter electrode are connected to and held by the electrode holding substrate, a matching circuit that adjusts a load impedance formed by the oscillation electrode, the counter electrode, and a storage object so as to match with an output impedance of the oscillation unit, the matching circuit being fixed on the electrode holding substrate; A refrigerator in which the oscillation electrode and the counter electrode are connected to and held by the electrode holding substrate, and the oscillation electrode and the counter electrode are connected to the matching circuit by surface contact connection.

2. 2. The refrigerator according to claim 1, wherein an end of said oscillation electrode and an end of said counter electrode are bent at right angles and project from said electrode holding substrate.

3. 2. The refrigerator according to claim 1, wherein the distance between the oscillation electrode and the counter electrode is shorter than a dimension of a long side of the oscillation electrode.

4. a plurality of electrode holes are formed in each of the oscillation electrode and the counter electrode; The plurality of electrode holes are in the shape of vertically elongated slits.

2. The refrigerator according to claim 1.

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