refrigerator

Abstract

To provide a refrigerator that has a thawing function capable of easily thawing a frozen object in a high-quality state, and can store a stored object housed in a storage chamber in a desired state even during freezing treatment and freezing storage treatment, and a control method therefor.SOLUTION: A refrigerator according to the present invention comprises an air passage for guiding cold air from a cooling mechanism to a storage chamber, an oscillating electrode provided in a storage space, an opposite electrode provided in the storage space so as to be opposite to the oscillating electrode, a high-frequency electric field forming part for forming a high-frequency electric field to be applied between the oscillating electrode and the opposite electrode, a cold air introduction mechanism for guiding the cold air formed by the cooling mechanism to the storage chamber, and a control unit for controlling the cooling mechanism and the cold air introduction mechanism so as to introduce the cold air from the air passage to the storage chamber when the high-frequency electric field is applied between the oscillating electrode and the opposite electrode.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a refrigeration system having a freezing function. warehouse A refrigeration system having a storage compartment capable of thawing frozen products. warehouse Regarding. [Background technology]

[0002] A typical refrigerator is equipped with a freezer compartment and is used to freeze ingredients and foods and store them as frozen goods for long periods of time. It is desirable for such frozen goods to be thawed in a short time and used in cooking in a thawed state as close to fresh as possible.

[0003] There are thawing processes for thawing frozen foods, such as natural thawing at room temperature and thawing under running tap water, but these thawing processes do not satisfy the short-time thawing required by cooks. In general households, microwave cooking appliances, so-called microwave ovens, are used to thaw frozen foods in a short time. However, when thawing frozen foods in a microwave oven, although thawing in a short time is possible, there are cases where an undesirable thawing state occurs, such as so-called "partially cooked" in which high-frequency energy is concentrated in the previously thawed area and the food cannot be thawed uniformly. Thus, when thawing frozen foods using a microwave oven, it is not easy to obtain a desirable high-quality thawed state. Here, a high-quality thawed state refers to a thawed state that is not tasty as food, such as a "partially cooked" state.

[0004] Patent Document 1 discloses a refrigerator equipped with a high-frequency heating chamber configured to supply cold air and thaw frozen items while irradiating microwaves. In the refrigerator of Patent Document 1, the surface of the frozen items in the high-frequency heating chamber is covered with cold air, and the inside of the frozen items is thawed by irradiating microwaves to the frozen items. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-147919 A Summary of the Invention [Problem to be solved by the invention]

[0006] The refrigerator disclosed in Patent Document 1 is provided with a magnetron for generating microwaves, and is configured to irradiate microwaves to frozen items in a high-frequency heating chamber for microwave heating. The refrigerator in Patent Document 1 is configured to be large overall as a result of the magnetron, which is a microwave generating means, and its cooling mechanism, making it difficult to reduce the size of the refrigerator. In addition, since the refrigerator is configured to irradiate microwaves from an antenna to the frozen items in the high-frequency heating chamber for microwave heating, it is difficult to uniformly heat the frozen items and defrost them to a desired state.

[0007] In addition, in conventional refrigerators, when room temperature food stored in the storage compartment is frozen, frosting occurs on the inner surface of the food packaging due to moisture in the cold storage compartment and moisture inside the food. When this 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"). It has been a challenge in this field to perform a freezing process that prevents this "freezer burn" from occurring.

[0008] The present invention has a thawing function that can easily thaw frozen products to a high quality state. R The purpose is to provide refrigerators. [Means for solving the problem]

[0009] A refrigerator according to one aspect of the present invention includes at least one storage compartment having a storage space capable of storing and cooling stored items, a cooling mechanism that generates cold air, an air passage that guides the cold air from the cooling mechanism to the storage compartment, an oscillation electrode and a counter electrode that are arranged opposite each other across the storage space, a high-frequency electric field forming unit that forms a high-frequency electric field to be applied between the oscillation electrode and the counter electrode, a cold air introduction mechanism that is provided in the air passage and guides the cold air formed by the cooling mechanism to the storage compartment, and a control unit that starts a thawing process upon input of a thawing command for a frozen item that is a stored item contained in the storage space, controls the high-frequency electric field forming unit to apply a high-frequency electric field between the oscillation electrode and the counter electrode in the thawing process, and controls the cooling mechanism and the cold air introduction mechanism to introduce cold air from the air passage when the high-frequency electric field is applied.

[0010] The cold air introduction mechanism includes a damper provided in the air passage and capable of opening and closing the air passage, and the control unit controls the supply of cold air by performing a closing operation that changes the damper from an open state to a closed state and an opening operation that changes the damper from the closed state to an open state when a high-frequency electric field is applied during the thawing process. Effect of the Invention

[0011] According to the present invention, a thawing function that can easily thaw frozen products to a high quality state is provided. RA refrigerator can be provided. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view showing a vertical section of a refrigerator according to a first embodiment of the present invention. [Diagram 2] FIG. 1 is a vertical cross-sectional view showing a freezing / thawing compartment in a refrigerator according to a first embodiment. [Diagram 3] FIG. 1 is a block diagram showing a configuration of a dielectric heating mechanism provided in a refrigerator according to a first embodiment. [Figure 4] FIG. 1 is a diagram showing an electrode holding area on the rear side of a freezing / thawing compartment in a refrigerator according to a first embodiment. [Diagram 5] FIG. 1 is a plan view showing an oscillation electrode and an inner surface member on the top surface side of a freezing / thawing compartment in a refrigerator according to a first embodiment; [Figure 6] FIG. 1 is a back view showing a counter electrode on a bottom surface side arranged opposite to an oscillation electrode in the refrigerator according to the first embodiment. [Figure 7] FIG. 11 is a plan view showing a modified example of the oscillation electrode in the refrigerator according to the first embodiment. [Figure 8] (a) is a cross-sectional view showing a schematic diagram of a dielectric heating configuration provided with a counter electrode having no electrode holes, and (b) is an electric field simulation diagram showing the results of a simulation performed on the dielectric heating configuration shown in (a). [Figure 9] (a) is a cross-sectional view showing a schematic diagram of a dielectric heating configuration provided with a counter electrode having an electrode hole, and (b) is an electric field simulation diagram showing the results of a simulation performed on the dielectric heating configuration shown in (a). [Figure 10] FIG. 13 is a diagram showing waveforms of control signals for an oscillator circuit and a damper during a defrosting process in the configuration of the first embodiment, and also showing the food temperature, the room temperature in the freezing / defrosting compartment, and the humidity in the freezing / defrosting compartment at that time. [Figure 11] 1 is a flowchart showing control after the thawing process is completed in the freezing / thawing compartment in the configuration of the first embodiment. [Figure 12] FIG. 1A is a waveform diagram showing a cooling operation during freezing in a conventional refrigerator, and FIG. 1B is a waveform diagram showing a cooling operation performed in a freezing / thawing compartment in a refrigerator according to a first embodiment. [Figure 13] FIG. 1 is a waveform diagram showing the state of each element during rapid cooling in the configuration of the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a refrigerator having a freezing function will be described as an embodiment of the refrigerator of the present invention with reference to the accompanying drawings. The refrigerator of the present invention 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 the present invention, a refrigerator is configured to include a refrigeration compartment and / or a freezing compartment.

[0014] 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 invention. Among the components in the following embodiments, components that are not described in an independent claim showing the highest concept are described as optional components. In the embodiments, the same elements may be given the same reference numerals even in modified examples, and descriptions thereof may be omitted. In addition, the drawings mainly show each component in a schematic manner to facilitate understanding.

[0015] First, various embodiments of the refrigerator of the present invention will be illustrated. A refrigerator according to a first aspect of the present invention includes: At least one storage chamber having a storage space capable of storing and cooling stored items; A cooling mechanism for generating cold air; an air passage that guides cool air from the cooling mechanism to the storage chamber; an oscillation electrode provided in the storage space; a counter electrode provided in the storage space and facing the oscillation electrode; a high frequency electric field generating unit for generating a high frequency electric field to be applied between the oscillation electrode and the counter electrode; a cold air introduction mechanism provided in the air passage and guiding the cold air generated by the cooling mechanism to the storage chamber; a control unit that controls the cooling mechanism and the cold air introduction mechanism to introduce cold air from the air passage when a high frequency electric field is applied between the oscillation electrode and the counter electrode; The refrigerator of the first aspect thus configured can reliably perform freezing, freezing and thawing processes on the preserved items stored in the storage compartment so that the preserved items maintain a desired high quality state.

[0016] A second aspect of the present invention is the refrigerator of the first aspect, further comprising a reflected wave detection unit that detects a reflected wave returning from the oscillation electrode toward the high frequency electric field generating unit, The control unit may be configured to control the cooling mechanism and the cold air introduction mechanism based on a reflectance that indicates a ratio of a reflected wave to an electromagnetic wave output from the oscillation electrode.

[0017] The refrigerator of a third aspect according to the present invention may be the refrigerator of the first or second aspect, further comprising an inner surface member that forms an inner surface of the storage chamber, and the inner surface member is configured to cover each of the opposing electrode surfaces of the oscillation electrode and the counter electrode.

[0018] A fourth aspect of the refrigerator according to the present invention is the third aspect, wherein the inner surface member has a cold air inlet hole, and cold air in the air passage is introduced into the storage chamber through the cold air inlet hole.

[0019] A fifth aspect of the refrigerator according to the present invention is any one of the first to fourth aspects, wherein the oscillation electrode is arranged on a top side of the heating chamber, the counter electrode is arranged on a bottom side of the heating chamber, and an opening is formed in the oscillation electrode through which cool air from the air path passes.

[0020] A sixth aspect of the present invention provides a method for controlling a refrigerator, comprising the steps of: inputting a defrosting command for a frozen item that is a stored item stored in a storage compartment; applying a high frequency electric field to an oscillation electrode and a counter electrode disposed on either side of a storage space of the storage chamber when a defrosting command is input; and controlling a cooling mechanism for generating cold air and a cold air introduction mechanism for introducing cold air into the storage chamber when a high-frequency electric field is applied between the oscillation electrode and the counter electrode. The control method of the sixth aspect of the refrigerator having such steps can reliably perform freezing, freezing and thawing processes on the preserved items stored in the storage chamber so that the preserved items maintain a desired high quality state.

[0021] A seventh aspect of the present invention relates to a control method for a refrigerator according to the sixth aspect, and further includes: detecting a reflected wave returning from the oscillation electrode toward a high frequency electric field forming unit that forms a high frequency electric field; The method may further include controlling the introduction of cool air into the storage chamber based on a reflectance indicating a ratio of a reflected wave to an electromagnetic wave output from the oscillation electrode.

[0022] A refrigerator control method of an eighth aspect according to the present invention may be characterized in that, in the seventh aspect, a thawing process in response to a thawing command for frozen items stored in the storage compartment is terminated based on the reflectance.

[0023] A ninth aspect of the present invention relates to a control method for a refrigerator according to the eighth aspect, and may further comprise the step of: after completing a thawing process in response to a thawing command, maintaining the storage compartment in a slightly freezing temperature range.

[0024] A refrigerator control method according to a tenth aspect of the present invention may be configured such that, in any one of the sixth to ninth aspects, a freezing process is performed on a thawed stored item when the thawed stored item has been continuously stored in the storage chamber for a predetermined time from the end of a thawing process in response to a thawing command.

[0025] A control method for a refrigerator according to an eleventh aspect of the present invention may be configured in any one of the sixth to tenth aspects, in which a high-frequency electric field is applied to the oscillation electrode and the counter electrode in a freezing process, a frozen preservation process, and a thawing process for a preserved item stored in a storage compartment.

[0026] (Embodiment 1) A first embodiment of a refrigerator according to the present invention will be described below with reference to the drawings. Fig. 1 is a diagram showing a vertical cross section of a refrigerator 10 according to the first embodiment. In Fig. 1, the left side is the front side of the refrigerator 10, and the right side is the rear side of the refrigerator 10. The refrigerator 10 is composed of an insulated box body formed of an outer box 1 mainly made of steel plate, an inner box 2 molded from a resin such as ABS, and an insulating material (for example, rigid urethane foam) 40 filled and foamed in the space between the outer box 1 and the inner box 2.

[0027] The insulated box of refrigerator 10 has a plurality of storage compartments, and an openable door is provided at the front opening of each storage compartment. Each storage compartment is sealed when the door is closed to prevent cold air from leaking. In refrigerator 10 of embodiment 1, the uppermost storage compartment is refrigerator compartment 3. Two storage compartments, an ice-making compartment 4 and a freezer / thawing compartment 5, are arranged side by side on both sides directly below refrigerator compartment 3. Furthermore, a freezer compartment 6 is provided directly below ice-making compartment 4 and freezer / thawing compartment 5, and a vegetable compartment 7 is provided at the bottom directly below freezer compartment 6. Each storage compartment in refrigerator 10 of embodiment 1 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.

[0028] The refrigerator compartment 3 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 7 is maintained at a temperature equal to or slightly higher than that of the refrigerator compartment 3, specifically, in the temperature range of 2°C to 7°C, for example. The freezer compartment 6 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 5 is normally maintained at the same freezing temperature range as the freezer compartment 6, 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 5 and details regarding the thawing process will be described later.

[0029] A machine room 8 is provided in the upper part of the refrigerator 10. The machine room 8 accommodates components constituting the refrigeration cycle, such as a compressor 9 and a dryer that removes moisture in the refrigeration cycle. The location of the machine room 8 is not limited to the upper part of the refrigerator 10, but is appropriately determined depending on the location of the refrigeration cycle, and the machine room 8 may be provided in another area, such as the lower part of the refrigerator 10.

[0030] A cooling compartment 11 is provided behind the freezer compartment 6 and the vegetable compartment 7 in the lower region of the refrigerator 10. The cooling compartment 11 is provided with a cooler 12, which is a component of a refrigeration cycle that generates cold air, and a cooling fan 13 that blows the cold air generated by the cooler 12 to each storage compartment (3, 4, 5, 6, 7). The cold air generated by the cooler 12 flows through an air duct 18 connected to each storage compartment by the cooling fan 13 and is supplied to each storage compartment. A damper 19 is provided in the air duct 18 connected to each storage compartment, and each storage compartment is maintained at a predetermined temperature range by controlling the rotation speed of the compressor 9 and the cooling fan 13 and opening and closing the damper 19. A defrost heater 14 is provided at the bottom of the cooling compartment 11 to remove frost and ice that adheres to the cooler 12 and its surroundings. A drain pan 15, a drain tube 16, and an evaporation dish 17 are provided below the defrost heater 14, and are configured to evaporate moisture generated during defrosting or the like.

[0031] The refrigerator 10 of the first embodiment is provided with an operation unit 47 (see FIG. 3 described later). A user can use the operation unit 47 to issue various commands to the refrigerator 10 (for example, temperature setting for each storage compartment, a command to rapidly cool, a command to defrost, 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 10 may be configured to include a wireless communication unit and connect to a wireless LAN network, so that various commands can be input from a user's external terminal. The refrigerator 10 may also be configured to include a voice recognition unit and so that a user can input commands by voice.

[0032] 2 is a vertical cross-sectional view showing the freezing / thawing compartment 5 in the refrigerator 10 of the embodiment 1. The freezing / thawing compartment 5 is a freezer that keeps stored items such as food stored therein at a freezing temperature range, and also serves as a thawing compartment that performs a thawing process by dielectric heating when a thawing command for the stored items is input in the refrigerator 10.

[0033] In order to maintain the freezing / thawing chamber 5 at the same freezing temperature range as the freezing chamber 6, the cold air generated in the cooler 12 flows through air passages 18 provided on the back and top sides of the freezing / thawing chamber 5 and is introduced into the freezing / thawing chamber 5 from a plurality of cold air introduction holes 20 provided on the top surface of the freezing / thawing chamber 5. A damper 19 is provided in the air passage 18 leading from the cooling chamber 11 to the freezing / thawing chamber 5, and the freezing / thawing chamber 5 is maintained at a specified freezing temperature range by controlling the opening and closing of the damper 19, and the stored items contained therein are frozen and preserved.

[0034] A cold air exhaust hole 21 is formed on the back surface of the freezing / thawing compartment 5. The cold air that is introduced into the freezing / thawing compartment 5 and cools the inside of the freezing / thawing compartment 5 returns from the cold air exhaust hole 21 to the cooling compartment 11 through the return air passage 34, and is re-cooled by the cooler 12. That is, the refrigerator 10 of the first embodiment is configured so that the cold air formed by the cooler 12 is circulated.

[0035] The top, back, both sides, and bottom constituting the inner surface of the storage space in the freezing / thawing chamber 5 are formed of an inner surface member 32 made of a resin material molded from an electrically insulating material. A door 29 is provided at the front opening of the freezing / thawing chamber 5, and the storage space of the freezing / thawing chamber 5 is sealed when the door 29 is closed. In the freezing / thawing chamber 5 of the first embodiment, a storage case 31 with an open top is provided on the back side of the door 29, and the storage case 31 moves back and forth simultaneously when the door 29 is opened and closed in the front-rear direction. The opening of the door 29 in the front direction makes it easy to put food and other preserved items into and take them out of the storage case 31.

[0036] Next, a dielectric heating mechanism that performs dielectric heating to perform a thawing process on the stored object frozen in the freezing / thawing chamber 5 will be described.

[0037] FIG. 3 is a block diagram showing a configuration of a dielectric heating mechanism provided in refrigerator 10 of embodiment 1. The dielectric heating mechanism in embodiment 1 includes an oscillation circuit 22 that receives power from power supply unit 48 to form a predetermined high-frequency signal, a matching circuit 23, an oscillation electrode 24, a counter electrode 25, and a control unit 50. Oscillator circuit 22, which is configured using semiconductor elements, is miniaturized and provided in machine room 8 of refrigerator 10. Oscillator circuit 22 is electrically connected to matching circuit 23 by a coaxial cable. Matching circuit 23 is disposed in electrode holding area 30 (see FIG. 2), which is a space on the back side of freezing / thawing compartment 5. Oscillator circuit 22 and matching circuit 23 serve as a high-frequency electric field forming unit for forming a high-frequency electric field to be applied between oscillation electrode 24 and counter electrode 25.

[0038] The oscillation electrode 24 is a planar electrode disposed on the top surface side of the freezing / thawing chamber 5. The counter electrode 25 is a planar electrode disposed on the bottom surface side of the freezing / thawing chamber 5. 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 5, and a distance defining portion 33, which will be described in the "electrode holding mechanism" below, is provided to set the opposing distance to a predetermined distance (first distance) 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 the present invention, "approximately parallel" refers to an essentially parallel state, but also indicates that it includes errors due to variations in processing accuracy and the like.

[0039] The oscillation electrode 24 is provided on one side of the storage space, and the counter electrode 25 is provided on the other side of the storage space across the storage space. 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, which reliably prevents the stored items from being burned due to contact with them.

[0040] In the configuration of embodiment 1, an oscillating electrode 24 is provided on the top surface forming the storage space of the freezing / thawing chamber 5, and a counter electrode 25 is provided on the bottom surface of the storage space of the freezing / thawing chamber 5. However, the present invention is not limited to this configuration, and it is sufficient that the oscillating electrode 24 and the counter electrode 25 are configured to face each other across the storage space (thawing space), and the same effect can be achieved even if they are arranged upside down or facing each other in the left-right direction.

[0041] As shown in FIG. 2, the freezing / thawing compartment 5 has a configuration in which cold air from the cooler 12 passes through the air passage 18 and is introduced from the top side of the freezing / thawing compartment 5. At the top side of the freezing / thawing compartment 5, an oscillation electrode 24 is disposed on the lower surface of the air passage 18, and cold air from the cooling compartment 11 flows over the oscillation electrode 24. In the refrigerator 10 of the first embodiment, an insulated box is formed by the outer box 1, the inner box 2, and the insulating material 40 filled and foamed between them, and the space in which the storage compartment is formed in this insulated box does not have high dimensional accuracy. In the space in which the freezing / thawing compartment 5 is formed, an area that becomes the air passage 18 is formed on the top side, and this area that becomes the air passage 18 becomes a space that can absorb dimensional variations in the insulated box. The configuration in which the cold air that has passed through the air passage 18 passes through a plurality of electrode holes 41 formed in the oscillation electrode 24 and is introduced into the freezing / thawing compartment 5 from the cold air introduction hole 20 of the inner surface member 32 on the top side will be described later.

[0042] The oscillator circuit 22 outputs a high-frequency voltage in the VHF band (40.68 MHz in the first embodiment). When the oscillator circuit 22 outputs the high-frequency voltage, an electric field is formed between the oscillator electrode 24 to which the oscillator circuit 22 is connected and the counter electrode 25, and the stored object, which is a dielectric material arranged in the storage space between the oscillator electrode 24 and the counter electrode 25 in the freezing / thawing chamber 5, is dielectrically heated.

[0043] The matching circuit 23 adjusts the load impedance formed by the oscillation electrode 24, the counter electrode 25, and the stored object accommodated in the freezing / thawing chamber 5 so that it matches the output impedance of the oscillation circuit 22. The matching circuit 23 minimizes the reflected wave of the output electromagnetic wave by matching the impedance. The dielectric heating mechanism in the first embodiment is provided with a reflected wave detection unit 51 that detects the reflected wave returning from the oscillation electrode 24 to the oscillation circuit 22. Therefore, the oscillation circuit 22 is electrically connected to the oscillation electrode 24 via the reflected wave detection unit 51 and the matching circuit 23. The control unit 50 calculates the ratio (reflectance) of the reflected wave output to the electromagnetic wave output based on the electromagnetic wave output output from the oscillation circuit 22 after impedance matching in the matching circuit 23 and the reflected wave detected by the reflected wave detection unit 51, and performs various controls based on the calculation results as described below.

[0044] As shown in the block diagram of Fig. 3, 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 for performing setting operations by the user and a temperature sensor 49 for detecting the temperature inside the chamber. 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.

[0045] In addition, since it is desirable for the length of the positive electrode wiring connecting the oscillator circuit 22, the matching circuit 23, and the oscillator electrode 24 to be short, the high-frequency electric field forming portion of the oscillator circuit 22 and the matching circuit 23 may be configured to be disposed in the electrode holding area 30 on the rear side of the freezing / thawing chamber 5.

[0046] [Electrode holding mechanism] The dielectric heating mechanism in the first embodiment configured as described above has a configuration in which the flat-plate oscillating electrode 24 and the counter electrode 25 face each other substantially parallel to each other, thereby achieving a uniform electric field in the thawing space, which is the storage space of the freezing / thawing chamber 5. In order to thus dispose the oscillating electrode 24 and the counter electrode 25 substantially parallel to each other with a predetermined interval (first interval) therebetween, the dielectric heating mechanism in the first embodiment has an electrode holding mechanism, which will be described below.

[0047] FIG. 4 is a diagram showing the electrode holding area 30 on the back side of the freezing / thawing chamber 5 in the first embodiment, and shows an electrode holding mechanism in the electrode holding area 30. FIG. 4 is a diagram showing the electrode holding area 30 as seen from the back 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). A positive electrode terminal 24a protrudes from the center of the back side end of the flat plate-like oscillation electrode 24, and support members 24b, 24b protrude from both sides of the positive electrode terminal 24a. The positive electrode terminal 24a and the support member 24b protrude downward (bottom side) from the back side end of the flat plate-like oscillation electrode 24 at a right angle. Similarly, a negative electrode terminal 25a protrudes from the center of the back side end of the flat plate-like counter electrode 25, and support members 25b, 25b protrude from both sides of the negative electrode terminal 25a. The negative electrode terminal 25a and the support member 25b are bent at a right angle and protrude upward (toward the top surface) from the rear end of the flat plate-shaped counter electrode 25. That is, the protruding ends of the positive electrode terminal 24a of the oscillation electrode 24 and the support member 24b face the protruding ends of the negative electrode terminal 25a of the counter electrode 25 and the support member 25b, respectively.

[0048] As described above, the protruding direction of each of the support members 24b, 24b of the oscillation electrode 24 faces the protruding direction of each of the support members 25b, 25b of the counter electrode 25, and each of the support members 24b, 24b is linearly joined to the opposing support members 25b, 25b via the interval defining portion 33. The interval defining portion 33 is a planar member, and is formed of an electrically insulating member that is not substantially dielectrically heated. As shown in FIG. 4, the interval defining portion 33 has an H-shape when viewed from the rear side, and the support members (24b, 25b) are connected to the four upper and lower ends of the H-shape, and the matching circuit 23 is fixed to the center portion of the H-shape. Therefore, the oscillation electrode 24 and the counter electrode 25 are fixed to both the upper and lower ends of the interval defining portion 33, the matching circuit 23 is fixed to the center portion of the interval defining portion 33, and the oscillation electrode 24, the counter electrode 25, and the matching circuit 23 are reliably held by the interval defining portion 33. In this way, the spacing defining portion 33 is configured to reliably hold the oscillation electrode 24 and the counter electrode 25, which are essentially planar plate-like members, at a predetermined distance (first interval). Since the matching circuit 23 is fixed to the center of the H-shape of the spacing defining portion 33, the spacing defining portion 33 has high rigidity and is configured to be able to cantilever-hold the oscillation electrode 24 and the counter electrode 25 at a predetermined opposing interval (first interval). Also, the spacing defining portion 33 may be configured to be provided with a high-frequency electric field generating portion for the oscillation circuit 22 and the matching circuit 23.

[0049] The positive terminal 24a of the oscillation electrode 24 and the negative terminal 25a of the counter electrode 25 are connected to the positive and negative connection terminals of the matching circuit 23. The connection between the positive terminal 24a and the negative terminal 25a 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 screws. Note that the connection between the terminals may be any connection means that provides a reliable surface-contact connection, and is not limited to a screw connection.

[0050] In the first embodiment, the terminal width w (see FIG. 4) of the positive terminal 24a protruding from the rear end of the oscillation electrode 24 is formed to be much narrower than the electrode width W (see FIG. 4) of the rear end of the oscillation electrode 24 (w<<W). This is to make it difficult for heat generated in the matching circuit 23 to be conducted to the oscillation electrode 24, and to suppress the thermal conduction between the matching circuit 23 and the oscillation electrode 24, thereby suppressing the occurrence of condensation in the matching circuit 23 when the oscillation electrode 24 is cooled. In addition, the terminal width of the negative terminal 25a of the counter electrode 25 is also formed to be much narrower than the electrode width of the rear end of the counter electrode 25 from which the negative terminal 25a protrudes, similar to the terminal width of the positive terminal 24a. By narrowing the terminal width of the negative terminal 25a in this way, the thermal conduction between the counter electrode 25 and the matching circuit 23 is suppressed.

[0051] 2 and 4, the cold air that has frozen the stored items in the freezing / thawing chamber 5 is configured to pass through the electrode holding area 30 from the cold air exhaust hole 21 via the return air duct 34 and return to the cooling chamber 11. Because the return air duct 34 is configured to pass through the electrode holding area 30 in this manner, the cold air from the freezing / thawing chamber 5 is not discharged at the electrode holding area 30, and condensation is prevented in the electrode holding area 30 including the matching circuit 23.

[0052] In addition, in a configuration in which the oscillation circuit 22 is disposed in the electrode holding area 30, a cooling configuration in which a heat sink, which is a heat dissipation member in the oscillation circuit 22, is brought into contact with the return air passage 34 for cooling may be used.

[0053] As described above, an electrode holding mechanism is provided on the rear side of the freezing / thawing chamber 5, so that the flat plate-shaped oscillation electrode 24 and the counter electrode 25 face each other substantially parallel to each other. In the configuration of the first embodiment, an electrode holding mechanism is also provided on the front side of the freezing / thawing chamber 5 to further ensure that the oscillation electrode 24 and the counter electrode 25 face each other substantially parallel to each other.

[0054] As described above, the insulated box of refrigerator 10 is composed of outer box 1 made of steel plate, inner box 2 molded from resin, and insulating material (e.g., rigid urethane foam) 40 filled and foamed in the space between outer box 1 and inner box 2. In addition, cross rail 35, which is a frame for defining the edge of the front opening of each storage compartment, is provided in the insulated box of refrigerator 10. Cross rail 35 of the frame is joined to a predetermined position of outer box 1 and is positioned with high precision relative to outer box 1. Therefore, the position of cross rail 35 with respect to outer box 1 is not affected by the filled and foamed insulating material 40, and is positioned with high precision.

[0055] 2, a cross rail 35 is provided on the edge of the front side of the freezing / thawing compartment 5, and a front opening of the freezing / thawing compartment 5 is defined by this cross rail 35. This front opening is opened and closed by a door 29 of the freezing / thawing compartment 5. A gasket 36 is provided between the door 29 and the cross rail 35 to prevent leakage of cool air when the door is closed.

[0056] The electrode holding mechanism on the front side of the freezing / thawing chamber 5 utilizes a cross rail 35 which is a frame that precisely defines the front opening of the freezing / thawing chamber 5. First holding claw 37 and second holding claw 38 which are holding members are integrally formed at a predetermined interval on the approximately parallel frame members above and below the cross rail 35. The first holding claw 37 and second holding claw 38 which are holding members may be configured to be joined to the cross rail 35 which is the frame.

[0057] The first holding claw 37, which is a holding member, is configured to engage the front end of the oscillation electrode 24 so as to sandwich it, and determines the position of the front end of the oscillation electrode 24. The second holding claw 38, which is a holding member, is configured to support the front end of the counter electrode 25, and determines the position of the front end of the counter electrode 25. The first holding claw 37 and the second holding claw 38 hold the front end of each of the oscillation electrode 24 and the counter electrode 25 with a predetermined interval (first interval) between them. The first holding claw 37 and the second holding claw 38 also hold the oscillation electrode 24 and the counter electrode 25 in an electrically insulated state.

[0058] Therefore, in refrigerator 10 of embodiment 1, since the dielectric heating mechanism of freezing / thawing compartment 5 is provided with electrode holding mechanisms on both the back side and the front side, oscillation electrode 24 and counter electrode 25 can be arranged with a highly accurate opposing distance, and can also be arranged reliably approximately parallel with a predetermined distance (first distance). As a result, the dielectric heating mechanism of freezing / thawing compartment 5 is configured to prevent bias of the high-frequency electric field on the electrode surface and to homogenize the high-frequency electric field, enabling uniform thawing of stored items (frozen goods).

[0059] [Electromagnetic wave shielding mechanism] As described above, in freezing / thawing compartment 5, a dielectric object is placed in the atmosphere of a high-frequency electric field between oscillating electrode 24 and counter electrode 25 and dielectrically heated, and therefore, electromagnetic waves can be emitted in freezing / thawing compartment 5. In order to prevent these electromagnetic waves from leaking outside refrigerator 10, refrigerator 10 of the first embodiment is provided with an electromagnetic wave shielding mechanism surrounding freezing / thawing compartment 5.

[0060] As shown in FIG. 2, a top-side electromagnetic wave shield 26 is disposed above the air passage 18 on the top side of the freezing / thawing compartment 5. The top-side electromagnetic wave shield 26 is disposed on the top surface of the heat insulating material 40 constituting the bottom side of the refrigeration compartment 3 directly above the freezing / thawing compartment 5, and is disposed so as to cover the top side of the freezing / thawing compartment 5. The top-side electromagnetic wave shield 26 has a plurality of openings, and is configured so as to reduce the substantial opposing area with respect to the oscillation electrode 24. The top-side electromagnetic wave shield 26 configured in this manner is configured to suppress the generation of unnecessary electric fields between the oscillation electrode 24. The top-side electromagnetic wave shield 26 may have a mesh structure having a plurality of openings. The top-side electromagnetic wave shield 26 may be disposed inside the refrigeration compartment 3 located directly above the freezing / thawing compartment 5, but the refrigeration compartment 3 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 the electromagnetic wave shield.

[0061] A rear electromagnetic shield 27 is provided so as to cover the electrode holding area 30 having the matching circuit 23 and the like provided on the rear side of the freezing / thawing chamber 5. Providing the rear electromagnetic shield 27 in this manner prevents 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 from affecting the operation (control) of the electrical components of the cooling fan 13 and the damper 19. An electromagnetic shield (not shown) is also provided on the side of the freezing / thawing chamber 5.

[0062] Next, a description will be given of the door-side electromagnetic shield 39 provided on the door 29 that opens and closes the front opening of the freezing / thawing compartment 5. Since the door 29 is configured to open and close relative to the body of the refrigerator 10, if the electromagnetic shield provided on the door 29 is connected to the grounded part of the body of the refrigerator 10 by a wired path, the wired path will repeatedly expand and contract as the door 29 is opened and closed, and metal fatigue will accumulate in the wired path. Since such a connection configuration can cause the wired path to break, it is not preferable to connect the electromagnetic shield 39 provided on the door 29 to the grounded part of the body of the refrigerator 10 by a wired path.

[0063] In general, in order to prevent electromagnetic wave leakage, it is necessary to make the distance between the door-side electromagnetic shield 39 and the cross rail 35, which serves as the electromagnetic shield on the main body side, shorter than 1 / 4 of the wavelength λ of the electromagnetic wave when the door 29 is closed. In the first embodiment, the distance is further reduced to obtain the effect of contact without providing a wired path. For example, the distance between the door-side electromagnetic shield 39 and the cross rail 35 when the door 29 is closed is set to 30 mm or less. Since the cross rail 35 connected to the outer box 1 is grounded, by bringing the door-side electromagnetic shield 39 close to the cross rail 35 when the door 29 is closed, an effect equivalent to grounding by a wired path can be obtained. In addition, by making the end of the door-side electromagnetic shield 39 bent toward the main body side of the refrigerator 10, the door-side electromagnetic shield 39 can be easily brought close to the cross rail 35.

[0064] In refrigerator 10 according to the first embodiment, outer box 1 is made of a steel plate, and the steel plate itself functions as an electromagnetic wave shield. This reliably prevents electromagnetic waves from inside refrigerator 10 from leaking to the outside of refrigerator 10.

[0065] [Configuration of the oscillation electrode and the counter electrode] When the user opens the door 29, high humidity air flows from the outside into the freezing / thawing compartment 5, which is maintained in the freezing temperature range, and the inside of the freezing / thawing compartment 5 becomes in a state where condensation is likely to occur. If condensation occurs on the surfaces of the oscillation electrode 24 and the counter electrode 25, the electric field formation between the electrodes becomes unstable, and a state where the desired dielectric heating is not performed may occur. In order to prevent such a state from occurring, in the refrigerator 10 of the first embodiment, the oscillation electrode 24 and the counter electrode 25 are covered with an inner surface member 32, and cold air is introduced into the freezing / thawing compartment 5 through a plurality of cold air introduction holes 20 formed in the oscillation electrode 24. The cold air introduced into the freezing / thawing compartment 5 is cold air sent from the cooling compartment 11 through the air passage 18 by the cooling fan 13, and the cold air at the time of introduction is in a relatively low humidity state. Therefore, even if the door 29 is opened or closed and high humidity air flows in from the outside, low humidity cold air is blown into the freezing / thawing chamber 5 from the multiple cold air inlet holes 20 formed over the entire top side, and the air inside the freezing / thawing chamber 5 is exhausted from the cold air exhaust holes 21 on the back side, so that the inside of the freezing / thawing chamber 5 is less likely to develop condensation.

[0066] 5 is a plan view of the oscillation electrode 24 and the inner surface member 32 on the top surface side of the freezing / thawing chamber 5, as viewed from above. As shown in FIG. 5, a plurality of electrode holes 41 are formed in the oscillation electrode 24, and the plurality of electrode holes 41 are distributed over the entire surface of the electrode surface of the oscillation electrode 24. The electrode holes 41 are arranged approximately uniformly at equal intervals on the electrode surface of the oscillation electrode 24. The electrode holes 41 of the oscillation electrode 24 are provided in correspondence with the positions of the cold air introduction holes 20 formed in the inner surface member 32 covering the lower surface of the oscillation electrode 24. The hole diameter D of the electrode hole 41 is formed to be larger than the hole diameter d of the cold air introduction hole 20 of the inner surface member 32 (D>d).

[0067] Since the electrode holes 41 are formed at equal intervals and approximately uniformly on the electrode surface of the oscillation electrode 24, the regions where a strong electric field is formed are uniformly distributed on the electrode surface of the oscillation electrode 24, and the stored items can be uniformly dielectrically heated. That is, the edges of the openings of the electrode holes 41 become the electric field concentration regions. Note that the shapes and arrangements of the cold air introduction holes 20 and the electrode holes 41 shown in Fig. 5 are merely examples, and the shapes and arrangements of the cold air introduction holes 20 and the electrode holes 41 are appropriately designed in consideration of efficiency and manufacturing costs according to the specifications and configuration of the refrigerator.

[0068] FIG. 6 is a back view showing the bottom side counter electrode 25 arranged opposite the oscillation electrode 24. FIG. 6 is a view of the counter electrode 25 seen from below, and an inner surface member 32 that becomes the bottom surface of the freezing / thawing chamber 5 is arranged on the counter electrode 25. As shown in FIG. 6, a plurality of electrode holes 42 are formed at equal intervals and approximately uniformly on the electrode surface of the counter electrode 25, similar to the oscillation electrode 24. However, in the configuration of the first embodiment, the electrode holes 42 of the counter electrode 25 are formed at positions that do not face the electrode holes 41 of the oscillation electrode 24. That is, the position of the central axis extending in the vertical direction of the electrode holes 42 of the counter electrode 25 is shifted from the position of the central axis extending in the vertical direction of the electrode holes 41 of the oscillation electrode 24, and the electrode holes 42 of the counter electrode 25 and the electrode holes 41 of the oscillation electrode 24 are shifted in position in the vertical direction (opposing direction).

[0069] In the configuration of the first embodiment, the shape and arrangement of the electrode holes 41 of the oscillation electrode 24 are described as being arranged substantially uniformly at equal intervals, but the present invention is not limited to such a configuration. For example, the oscillation electrode 24 may have at least one opening, and the edge of the opening becomes an electric field concentration region in which the electric field is concentrated on the electrode surface of the oscillation electrode 24. That is, the present invention may be configured so that the electric field concentration region is dispersed on the electrode surface of the oscillation electrode 24. In addition, 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 invention is not limited to the configuration in which a plurality of electrode holes 42 are provided on the counter electrode 25, and may be an opening formed so that a desired electric field is formed between the electrode and the oscillation electrode 24.

[0070] FIG. 7 is a plan view showing an example of a modified example of the oscillation electrode 24 in the first embodiment. The modified example shown in FIG. 7(a) shows an example in which one opening portion is formed as the electrode hole 41A in the oscillation electrode 24. In the first embodiment, the opening portion formed in the oscillation electrode 24 is the electrode opening, and this electrode opening includes the electrode holes (41, 41A). The electrode opening 41A shown in FIG. 7(a) includes a circular opening 41a, an arc-shaped opening 41b, and a communication opening 41c that communicates the respective openings (41a, 41b). By forming the electrode opening 41A in such a shape, it is possible to disperse the region in which the electric field becomes strong on the electrode surface of the oscillation electrode 24. The modified example shown in FIG. 7(b) shows a modified example of the electrode opening (41B) in the oscillation electrode 24, and is an example in which an electrode notch portion 41B in which a notch portion is formed in the oscillation electrode 24 is formed. 7(b), by forming the electrode cutout portion 41B as the opening portion, the region where the electric field becomes strong is dispersed on the electrode surface of the oscillation electrode 24. The cold air introduction hole 20 formed in the inner surface member 32 covering the lower surface of the oscillation electrode 24 is formed at a position corresponding to the electrode openings (41, 41A, 41B) of the oscillation electrode 24, and is configured so that the cold air from the air passage 18 is smoothly introduced into the freezing / thawing chamber 5.

[0071] As described above, in the top surface side of the freezing / thawing chamber 5 in the first embodiment, cold air is introduced into the inside of the freezing / thawing chamber 5 through the electrode openings (41, 41A, 41B) which are the openings of the oscillation electrode 24 constituting the lower surface of the air passage 18. Therefore, in the freezing / thawing chamber 5, cold air is blown from the cold air introduction holes 20 formed on the top surface side, and a uniform and rapid freezing process can be performed in the freezing / thawing chamber 5. In addition, since the electrode surface of the oscillation electrode 24 is formed so that the electric field concentration area is dispersed, uniform dielectric heating can be performed on the stored items, and good thawing can be performed.

[0072] 5 and 6, the electrode hole 41 of the oscillation electrode 24 and the electrode hole 42 of the counter electrode 25 are formed so that their central axes extending in the vertical direction (opposing direction) do not coincide with each other, thereby dispersing the area where the electric field is concentrated between the oscillation electrode 24 and the counter electrode 25, and homogenizing the electric field in the storage space where the oscillation electrode 24 and the counter electrode 25 face each other. As a result, the stored items placed in the storage space of the freezing / thawing chamber 5 can be dielectrically heated more uniformly.

[0073] The inventors performed a simulation of electric field generation between electrodes using a freezing / thawing chamber 5 having the electrode configuration of embodiment 1 and, as a comparative example, a freezing / thawing chamber 5X having an electrode configuration provided with a counter electrode 25X that does not have an electrode hole.

[0074] FIG. 8(a) is a cross-sectional view showing a schematic electrode configuration in which a counter electrode 25X having no electrode hole is provided, and is a diagram showing a freezing / thawing chamber 5X cut in the left-right direction. FIG. 8(b) shows the results of simulating the electric field strength when an electric field is applied to the electrodes of the electrode configuration shown in FIG. 8(a). In FIG. 8(b), the dark parts are areas where the electric field is concentrated. As is clear from this electric field simulation diagram, the electric field is concentrated at the outer edge parts of the electrodes, and especially at the corner parts.

[0075] FIG. 9(a) is a cross-sectional view showing a schematic diagram of the electrode configuration of the freezing / thawing chamber 5 having the configuration of the first embodiment, and shows the freezing / thawing chamber 5 cut in the left-right direction. FIG. 9(b) shows the results of simulating the electric field strength when an electric field is applied to the electrodes of the electrode configuration shown in FIG. 9(a). In FIG. 9(b), as in FIG. 8(b), the darker parts are areas where the electric field is concentrated. As is clear from this electric field simulation diagram, compared to the electric field simulation diagram of FIG. 8(b), the dielectric heating configuration of FIG. 9(a) has a reduced electric field concentration over the entire electrode, and it can be understood that the electric field is made uniform.

[0076] 9(b), the electrode holes 41 of the oscillation electrode 24 and the electrode holes 42 of the counter electrode 25 are arranged so that their central axes extending in the vertical direction (opposing direction) do not coincide with each other, thereby alleviating electric field concentration in the entire electrode. In the 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 their central axes extending in the vertical direction (opposing direction) coincide with each other, electric field concentration is alleviated compared to the configuration in which the counter electrode 25X having no electrode hole shown in FIG. 8 is provided, and electric field concentration is particularly alleviated at the corners.

[0077] In the freezing / thawing compartment 5 of the refrigerator 10 according to the first embodiment, as shown in FIG. 2, the 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 compartment 5 as the door 29 opens and closes. In the configuration according to the first embodiment, rails 52 are provided on both sides of the freezing / thawing compartment 5 so that the storage case 31 can move smoothly inside the freezing / thawing compartment 5 (see FIG. 9). Furthermore, frames 53 that slide on the rails 52 are provided on both sides of the outside of the storage case 31. The sliding members of the rails 52 and the frames 53 are provided at positions outside the dielectric heating area, which is the area where the oscillation electrode 24 and the counter electrode 25 of the freezing / thawing compartment 5 face each other, so as not to be dielectrically heated.

[0078] [Decompression process] In refrigerator 10 of the first embodiment, when a defrost command is input, a defrosting process is performed on the stored item (frozen item) between oscillation electrode 24 and counter electrode 25 in freezing / defrosting compartment 5. In the defrosting process of the first embodiment, as described below, control unit 50 controls a dielectric heating mechanism having oscillation circuit 22 and matching circuit 23, and also controls a cooling mechanism including a refrigeration cycle such as compressor 9 and cooler 12, and a cold air introduction mechanism including cooling fan 13, damper 19, etc.

[0079] 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 between the electrodes. During this dielectric heating, cold air is intermittently introduced by controlling the opening and closing of the damper 19. Figure 10 shows the waveforms of the control signals for the dielectric heating mechanism (oscillating circuit 22) and the cold air introduction mechanism (damper 19) during the thawing process, as well as the food temperature, the room temperature of the freezing / thawing compartment 5, and the humidity of the freezing / thawing compartment 5 at that time.

[0080] A configuration using VHF waves as the frequency characteristic for the thawing process is less likely to cause "partial cooking" than a configuration using microwaves, but in order to further improve the uniformity of thawing, refrigerator 10 of embodiment 1 is provided with a spacing regulation part 33, which reliably holds oscillation electrode 24 and counter electrode 25, which are essentially flat plate-like members, approximately parallel with a predetermined spacing (first spacing).

[0081] As shown in FIG. 10, in the thawing process, when a thawing command is input (thawing start), the oscillation circuit is turned on, and a high-frequency voltage of, for example, 40 MHz is applied between the oscillation electrode 24 and the counter electrode 25. At this time, the damper 19 is in an open state, so that the room temperature of the freezing / thawing chamber 5 is maintained at the freezing temperature t1 (for example, −20° C.). The damper 19 is closed after a predetermined period has elapsed since the start of thawing. When the damper 19 is closed, the room temperature of the freezing / thawing chamber 5 begins to rise. In the thawing process in the first embodiment, dielectric heating is performed and the damper 19 is controlled to open and close, thereby suppressing an increase in the surface temperature of the frozen product and performing thawing without causing so-called “partial cooking”. The control unit 50 controls the opening and closing of the damper 19 based on the ratio (reflectance) of the reflected wave detected by the reflected wave detection unit 51 to the electromagnetic wave matched by the matching circuit 23 and supplied between the oscillation electrode 24 and the counter electrode 25. When the reflectance reaches a preset threshold value and increases, the control unit 50 opens the damper 19 to lower the temperature inside the freezing / thawing chamber 5. In this way, by controlling the opening and closing of the damper 19, cold air is intermittently introduced into the freezing / thawing chamber 5, so that the stored items in the storage space (thawing space) of the freezing / thawing chamber 5 are dielectrically heated while maintaining a desired frozen state, and reach a desired thawed state.

[0082] The thawing process is completed when the desired thawed state is reached, and in order to detect the desired thawed state at which the thawing process is completed, the reflectance is used in the thawing process of the first embodiment. As the melting of the stored object progresses due to dielectric heating, the number of melted water molecules in the stored object increases. As the number of melted water molecules in the stored object increases, the dielectric constant changes and the impedance matching state shifts. As a result, the reflectance, which is the ratio of reflected waves to output electromagnetic waves, increases. In the thawing process, when the reflectance increases and reaches a preset threshold, the matching circuit 23 performs impedance matching to reduce the reflectance.

[0083] 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 the threshold for completion of thawing. The threshold for completion of thawing is used to detect when the melting of the stored object reaches 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 for completion of thawing is a value determined in advance by experiment.

[0084] As shown in FIG. 10, by controlling the opening and closing of damper 19, relatively low-humidity cold air that has passed through air passage 18 is supplied to freezing / thawing chamber 5 through cold air inlet hole 20, so that the humidity in freezing / thawing chamber 5 never reaches 100%, thereby preventing condensation from forming in freezing / thawing chamber 5.

[0085] [Control after decompression process is complete] Fig. 11 is a flowchart showing control after the thawing process is completed in the freezing / thawing chamber 5. Each step shown in the flowchart in Fig. 11 is performed by the CPU of the control unit 50 executing a control program stored in a memory such as a ROM. 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. 11 is performed.

[0086] As shown in step 101 of FIG. 11, after the thawing process is completed, the room temperature of the freezing / thawing chamber 5 is maintained in a so-called slightly freezing temperature range, for example, about −1° C. to −3° C. Thus, the freezing / thawing chamber 5 is maintained in the slightly freezing temperature range, so that the stored object is maintained in a desired thawed state. In a state in which the freezing / thawing chamber 5 is maintained at the slightly freezing temperature, the presence or absence of the stored object in the freezing / thawing chamber 5 is constantly detected (step 102). The presence or absence of the stored object in the freezing / thawing chamber 5 is detected using the reflectance, which is constantly detected. For this reason, the matching circuit 23 is always intermittently operated, and low-power electromagnetic waves are 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 the stored object to determine the presence or absence of the stored object in the freezing / thawing chamber 5.

[0087] In step 102, when it is detected that there is no stored item in the freezing / thawing chamber 5, it is determined that the stored item in the desired thawed state has been removed, and the room temperature of the freezing / thawing chamber 5 is set to the freezing temperature range, for example, -18°C to -20°C (step 105).

[0088] In step 102, when it is detected that a stored item is present in the freezing / thawing chamber 5, it is determined whether the present stored item includes a new non-frozen item (e.g., foodstuff at room temperature). Whether a new non-frozen item is present in the freezing / thawing chamber 5 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 chamber 5, the room temperature of the freezing / thawing chamber 5 is set as the freezing temperature zone (step 105).

[0089] On the other hand, in step 103, when it is determined that no new non-frozen product is stored in the freezing / thawing compartment 5 and the thawed stored object is still being held, 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 5. In such a case, the refrigerator 10 of the first embodiment is configured to maintain the slightly freezing temperature range in which the stored object in the freezing / thawing compartment 5 can be maintained in a desired thawed state for a predetermined time. If the stored object is stored in the freezing / thawing compartment 5 for more than the predetermined time, the refrigerator 10 of the first embodiment controls the room temperature of the freezing / thawing compartment 5 to be shifted to the freezing temperature range in order to maintain the freshness of the stored object. 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, the process proceeds to step 105, and a freezing process is performed with the room temperature of the freezing / thawing compartment 5 in the freezing temperature range.

[0090] As described above, in refrigerator 10 of embodiment 1, after the thawing process is completed, the stored items can be kept in the desired thawed state in freezing / thawing compartment 5 for a specified period of time to maintain their freshness, and appropriate temperature control can be performed for the stored items inside freezing / thawing compartment 5.

[0091] [Freezing / thawing chamber freezing operation] Refrigerator 10 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 freezing / thawing compartment 5 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 freezing / thawing compartment 5 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, refrigerator 10 of the first embodiment performs a dielectric heating operation together with a cooling operation at the same time.

[0092] Fig. 12 is a waveform diagram showing the state of each element during a cooling operation. Fig. 12(a) is a waveform diagram showing the cooling operation during frozen storage in a conventional refrigerator, and Fig. 12(b) is a waveform diagram showing the cooling operation executed in freezing / thawing compartment 5 in refrigerator 10 of embodiment 1.

[0093] In FIG. 12(a), (1) is a waveform diagram showing ON / OFF of the cooling operation. The ON / OFF of the cooling operation corresponds to, for example, the opening and closing of a damper, or the ON / OFF operation of a compressor. 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. 12(a)(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 frost formation will occur repeatedly on the surface of the food in the freezer, and the food may not be frozen in a desirable state.

[0094] On the other hand, in Fig. 12(b) 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. 12(b) (1) is a waveform diagram showing the opening and closing operation of the damper 19, where ON indicates the open state of the damper 19, and cold air passes through the air passage 18 and is introduced into the freezing / thawing chamber 5 from the cold air introduction hole 20. OFF indicates the closed state of the damper 19, and the introduction of cold air into the freezing / thawing chamber 5 is blocked. The introduction of cold air in the cooling operation of the first embodiment is performed simultaneously with dielectric heating, so the introduction time of the cold air is set longer than in the conventional example, i.e., the cooling capacity is increased.

[0095] FIG. 12(b)(2) is a waveform diagram showing the operating state of dielectric heating when oscillator circuit 22 is driven and controlled. When damper 19 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. 12(b)(3), the temperature of the food in freezing / thawing compartment 5 is maintained at a preset freezing temperature T1 (e.g., -20°C), and fluctuations in the food temperature are suppressed.

[0096] 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, inside the food, dielectric heating has the effect of suppressing the extension of ice crystals. When dielectric heating is performed, an electric field tends to gather at the tips of ice crystals formed inside the food, so that even if the temperature inside freezing / thawing chamber 5 is below the maximum ice crystal formation zone, the ice crystals only extend slowly.

[0097] As described above, in refrigerator 10 of embodiment 1, the dielectric heating operation is performed even during the cooling operation during frozen storage, so that the frozen items to be stored can be frozen and stored in a desired state.

[0098] [Freezing process] In the refrigerator 10 of the first embodiment, a freezing process can be performed on non-frozen food newly placed in the freezing / thawing compartment 5 based on a user's command from the operation unit 47. FIG. 13 is a waveform diagram showing the state of each element in the rapid cooling operation, which is a freezing process. In FIG. 13, (a) is a graph showing whether or not a preserved item (food) is present in the freezing / thawing compartment 5. The determination of whether or not a preserved item is present in the freezing / thawing compartment 5 is made by the control unit 50 based on the ratio (reflectance) of the reflected wave detected by the reflected wave detection unit 51 to the output electromagnetic wave. (b) of FIG. 13 shows that the control unit 50 intermittently acquires information from the matching circuit 23 and the reflected wave detection unit 51. (c) of FIG. 13 is a graph showing an example of the transition of the reflectance. The control unit 50 determines that a preserved food item has been placed in the freezing / thawing compartment 5 when the reflectance becomes equal to or less than the first threshold value R1.

[0099] In the rapid cooling operation of food stored in the freezing / thawing compartment 5, the rotation speed of the compressor 9 and the cooling fan 13 of the cooling mechanism is increased to increase the cooling capacity and perform forced continuous operation. Also, the damper 19 of the air passage 18 leading to the freezing / thawing compartment 5 is forcibly driven in a continuous open state, and the cold air introduction mechanism is driven and controlled so as to introduce cold air (see the waveform diagram in FIG. 13(d)).

[0100] In the rapid cooling operation, a dielectric heating operation is performed to suppress the growth 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 1W to approximately 10W, and dielectric heating is performed intermittently (period H in FIG. 13(e)). In order to start the dielectric heating operation, the food temperature entering the maximum ice crystal formation zone is detected by an increase in the change in reflectance when the food passes through the latent heat zone. In the first embodiment, when the detected reflectance enters a preset second threshold value R2, the dielectric heating operation is started (see FIG. 13(e)). Note that the region from the second threshold value R2 to the third threshold value R3 is considered to be the maximum ice crystal formation zone for the food, so the dielectric heating operation is continued, and when a predetermined time (t2) has elapsed since the reflectance entered the third threshold value R3, it is determined that the food has passed the maximum ice crystal formation zone, and the dielectric heating operation is stopped.

[0101] 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 dielectric heating operation is performed for a desired period of time, so that the food can be frozen to a desired state.

[0102] As described above, in the freezing / thawing compartment 5 of the refrigerator in embodiment 1, it is possible to freeze and freeze-store items in a desired state, and it has the excellent effect of being able to thaw frozen items in a desired state to a desired state in a short period of time.By using a dielectric heating mechanism composed of semiconductor elements, it is possible to achieve a configuration that allows for the miniaturization of the refrigerator as a refrigerator with a thawing function.

[0103] In the refrigerator according to the first embodiment, the freezing / thawing compartment 5 has both a freezing function and a thawing function. However, the refrigerator may have a thawing compartment 5 with only a thawing function.

[0104] As described above, the refrigerator of the present invention has a thawing function that can easily thaw frozen products to a high-quality state as described in the first embodiment, and also has excellent performance as a food storage facility that stores the preserved products stored in the storage compartment in a desired state in the freezing process and the frozen storage process. Therefore, according to the present invention, it is possible to provide a highly safe refrigerator that has reliable cooling, storage, and thawing functions and can freeze, store, and thaw the preserved products stored in the storage compartment in a desired state.

[0105] As described above, the refrigerator of the present invention has the excellent effect of being able to freeze and store items in a desired state, and being able to thaw frozen items in a desired state to the desired state in a short period of time, and by using a dielectric heating mechanism composed of semiconductor elements, it is possible to achieve a compact refrigerator with a thawing function.

[0106] Although the present invention has been described in embodiments with a certain degree of detail, the disclosed contents of the embodiments may vary in the details of the configuration, and substitutions, combinations, and changes in the order of elements in the embodiments may be made without departing from the scope and spirit of the invention as claimed. [Industrial Applicability]

[0107] The refrigerator of the present invention has a configuration that can process the freezing, storage, and thawing of stored items to a desired state, and therefore has a configuration that increases the added value of the refrigerator and has high market value. [Explanation of symbols]

[0108] 1 Outer box 2 Inner box 3. Refrigerator 4 Ice Room 5 Freezing / thawing room 6 Freezer 7 Vegetable compartment 8 Machine room 9. Compressor 10. Refrigerator 11 Cooling room 12 Cooler 13 Cooling fan 14 Defrost heater 15 Drain pan 16 Drain tube 17 Evaporation dish 18 Wind path 19 Damper 20 Cool air intake 21 Cool air exhaust vent 22 Oscillator Circuit 23 Matching circuit 24 Oscillation electrode 25 Counter electrode 26 Top side electromagnetic shield 27 Rear electromagnetic shield 28 Front electromagnetic shield 29 Door 30 Electrode holding area 31 Storage Case 32 Inner surface material 33 Spacing Regulation Section 34 Return air duct 39 Door side electromagnetic shield 40 Insulation 41 Electrode hole (oscillating electrode) 42 Electrode hole (counter electrode) 47 Control section 48 Power supply section 49 Temperature Sensor 50 Control section 51 Reflected wave detector

Claims

1. At least one storage chamber having a storage space capable of storing and cooling stored items; A cooling mechanism for generating cold air; an air passage that guides cool air from the cooling mechanism to the storage chamber; an oscillation electrode and a counter electrode disposed opposite to each other with the storage space therebetween; a high frequency electric field generating unit for generating a high frequency electric field to be applied between the oscillation electrode and the counter electrode; a cold air introduction mechanism provided in the air passage and guiding the cold air generated by the cooling mechanism to the storage chamber; a control unit that starts a thawing process upon receiving a thawing command for the frozen product, which is the preserved item contained in the storage space, controls the high frequency electric field generating unit to apply a high frequency electric field between the oscillation electrode and the counter electrode during the thawing process, and controls the cooling mechanism and the cold air introducing mechanism to introduce cold air from the air passage when the high frequency electric field is being applied; a reflected wave detection unit that detects a reflected wave returning from the oscillation electrode toward the high frequency electric field generating unit, the cool air introduction mechanism includes a damper provided in the air passage and capable of opening and closing the air passage, The control unit, during the thawing process, when the high-frequency electric field is applied, controls the supply of cold air by performing a closing operation of changing the damper from an open state to a closed state and an opening operation of changing the damper from a closed state to an open state, and controls the opening operation and the closing operation of the damper based on a reflectivity that indicates a ratio of a reflected wave to an electromagnetic wave output from the oscillation electrode.

2. The refrigerator according to claim 1 , wherein the control unit, in the defrosting process, repeatedly performs the opening operation and the closing operation of the damper to intermittently supply the cool air.

3. The refrigerator according to claim 1, wherein, in the defrosting process, the control unit performs the closing operation of the damper after application of the high frequency electric field starts, and thereafter performs the opening operation of the damper while the high frequency electric field is being applied.

4. The refrigerator according to claim 1 , wherein the control unit performs the opening operation of the damper when it is detected that the reflectance exceeds a preset first threshold value.

5. The refrigerator according to claim 4, wherein when it is detected that the reflectance exceeds a second threshold value that is greater than the first threshold value, the control unit stops application of the high frequency electric field by the high frequency electric field forming unit and terminates the thawing process.

6. an inner surface member which is an electrically insulating resin member and constitutes an inner surface of the storage chamber; the electrode surfaces of the oscillation electrode and the counter electrode facing each other are covered with the inner surface member, 2. The refrigerator according to claim 1, wherein the inner surface member has a cold air inlet hole, and the cold air in the air passage is introduced into the storage compartment through the cold air inlet hole.

Images