refrigerator

Abstract

To provide a refrigerator that comprises a storage chamber capable of freezing, storing, and thawing a stored object in a desired state, and is highly reliable.SOLUTION: A refrigerator comprises: a coaxial cable 56 directly or indirectly connecting an oscillation circuit 22 for forming high-frequency power, and a matching circuit 23 for matching load impedance and output impedance of the oscillation circuit 22; and noise suppressing means for preventing leakage of noise from the coaxial cable 56. The refrigerator can restrain a malfunction caused by noise and leakage of radio waves to the outside, is compact and highly reliable, and has cooling and storage functions.SELECTED DRAWING: Figure 19A

Description

Technical Field

[0001] The present disclosure relates to a refrigerator having a storage compartment with both a refrigeration function and a function for thawing frozen goods.

Background Art

[0002] Patent Document 1 shows a refrigerator having a storage compartment capable of thawing conventional frozen goods. This refrigerator is provided with a high-frequency heating compartment (storage compartment) capable of thawing frozen goods together with a freezing compartment inside a refrigerator body having a refrigeration device and a magnetron for generating high frequency. Cold air from the refrigeration device is supplied to the high-frequency heating compartment through a cold air circulation duct, and high frequency is irradiated from the magnetron to thaw the frozen goods.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a refrigerator that can freeze, store, and thaw stored items in a desired state in a storage compartment capable of thawing, thereby enhancing storage performance.

Means for Solving the Problems

[0005] At least one storage compartment having a space capable of storing stored items, An oscillation unit that forms high-frequency power, A first electrode and a second electrode that receive the high-frequency power formed by the oscillation unit and generate an electric field in the storage space, A matching unit that matches the load impedance formed by the first electrode, the second electrode, and the stored items accommodated in the storage compartment with the output impedance of the oscillation unit, High-frequency wiring that directly or indirectly connects the oscillator and the matching unit, It is equipped with noise suppression means to prevent noise leakage from the aforementioned high-frequency wiring. [Effects of the Invention]

[0006] The refrigerator according to this disclosure is capable of freezing, storing, and thawing items stored in the storage chamber in a desired state by a high-frequency electric field formed between a first electrode and a second electrode, and provides a compact and reliable refrigerator. [Brief explanation of the drawing]

[0007] [Figure 1] Longitudinal cross-sectional view of the refrigerator according to Embodiment 1 [Figure 2] Front cross-sectional view showing the freezing / thawing compartment in the refrigerator of Embodiment 1 [Figure 3] Side cross-sectional view showing the freezing / thawing compartment in the refrigerator of Embodiment 1 [Figure 4] Vertical cross-sectional view of the refrigerator in Embodiment 1 when the freezing / thawing compartment is incorporated. [Figure 5] Front cross-sectional view showing a modified example of the freezing / thawing compartment in the refrigerator of Embodiment 1. [Figure 6] Side cross-sectional view showing a modified example of the freezing / thawing compartment in the refrigerator of Embodiment 1. [Figure 7] Vertical cross-sectional view of the refrigerator in Embodiment 1 when the freezing / thawing compartment is incorporated. [Figure 8] Diagram showing the electrode holding area on the back side of the freezing / thawing chamber in Embodiment 1. [Figure 9] Block diagram showing the configuration of the dielectric heating mechanism provided in the refrigerator of Embodiment 1. [Figure 10] Schematic circuit diagram of an AC / DC converter that drives various circuits. [Figure 11] Plan view from above of the first and second electrodes on the top surface of the freezing / thawing compartment in the refrigerator of Embodiment 1. [Figure 12] This diagram shows the relationship between the distance between the first and second electrodes and the electric field strength between the two electrodes. [Figure 13A] Electric field simulation diagram showing the results of simulating the dielectric heating configuration [Figure 13B] Electric field simulation diagram showing the results of simulating the dielectric heating configuration of the refrigerating / freezing chamber in the refrigerator of Embodiment 1 [Figure 14] Diagram showing the waveforms of the control signals of the oscillation circuit and the damper in the electric field generation process in the configuration of Embodiment 1, and showing the food temperature, the room temperature of the refrigerating / freezing chamber, and the humidity of the refrigerating / freezing chamber at that time [Figure 15] Flowchart showing the control after the electric field generation process is completed in the refrigerating / freezing chamber in the configuration of Embodiment 1 [Figure 16A] Waveform diagram showing the cooling operation during frozen storage in a conventional refrigerator [Figure 16B] Waveform diagram showing the cooling operation performed in the refrigerating / freezing chamber in the refrigerator of Embodiment 1 [Figure 17] Waveform diagram showing the states of each element during the rapid cooling operation in the configuration of Embodiment 1 [Figure 18A] Diagram showing an example of a high-frequency cutoff circuit when the door of the refrigerator of Embodiment 1 is opened [Figure 18B] Diagram showing another example of a high-frequency cutoff circuit when the door of the refrigerator of Embodiment 1 is opened [Figure 18C] Diagram showing yet another example of a high-frequency cutoff circuit when the door of the refrigerator of Embodiment 1 is opened [Figure 19A] Cross-sectional view showing an example of cable wiring to the refrigerating / freezing chamber in the refrigerator of Embodiment 1 [Figure 19B] Cross-sectional view showing an example of cable wiring to the refrigerating / freezing chamber in the refrigerator of Embodiment 1 [Embodiments for Carrying Out the Invention]

[0008] (Findings etc. on which the present disclosure is based) When the inventors arrived at the idea of the present disclosure, the refrigerator described in Patent Document 1 was known.

[0009] However, the refrigerator described in Patent Document 1 is configured to heat frozen items in a high-frequency heating chamber by irradiating them with high-frequency waves from a magnetron via an antenna or the like. As a result, the high-frequency waves tend to be unevenly distributed, making it difficult to uniformly heat the frozen items and thaw them to the desired state. Furthermore, because the configuration involves irradiating frozen items with high-frequency waves from a magnetron for high-frequency heating, it is necessary to include a relatively large magnetron and its cooling mechanism, which presents a challenge in miniaturization.

[0010] Furthermore, because these devices use high frequencies, they generate normal-mode noise or common-mode noise, which presents the challenge of being difficult to suppress.

[0011] In light of these challenges, the inventors have come to form the subject matter of this disclosure in order to solve these problems.

[0012] Therefore, this disclosure provides a compact and reliable refrigerator capable of freezing, storing, and thawing items stored in the storage chamber in a desired state.

[0013] Hereinafter, an embodiment of the refrigerator of the present invention, specifically a refrigerator equipped with a freezing function, will be described with reference to the attached drawings. It should be noted that the refrigerator of this disclosure is not limited to the configuration of the refrigerator described in the following embodiments, but is also applicable to freezers having only a freezing function, and includes various refrigerators and freezers having the technical features described in the following embodiments. Therefore, in the present invention, a refrigerator is a configuration comprising a refrigerator compartment and / or a freezer compartment.

[0014] Furthermore, the numerical values, shapes, configurations, steps, and order of steps shown in the following embodiments are examples only and do not limit the present invention. Among the components in the following embodiments, components not described in the independent claim indicating the highest-level concept will be described as optional components. In the embodiments, the same reference numerals are used for the same elements in modified examples, and their description may be omitted. Also, the drawings schematically show each component in order to facilitate understanding. (Embodiment 1) Hereinafter, Embodiment 1 of the refrigerator according to this disclosure will be described with reference to the drawings. In order to facilitate understanding, this disclosure will be explained in sections, item by item.

[0015] [1-1. Overall configuration of the refrigerator] Figure 1 is a diagram showing a vertical cross-section of the refrigerator 1 according to Embodiment 1.

[0016] In Figure 1, the left side is the front of the refrigerator 1, and the right side is the back of the refrigerator 1. The refrigerator 1 is composed of an insulated box body formed by an outer box 3 mainly made of steel plate, an inner box 4 molded from a resin such as ABS, and an insulating material (for example, rigid polyurethane foam) 40 filled in the space between the outer box 3 and the inner box 4.

[0017] The insulated box 2 of the refrigerator 1 is equipped with multiple storage compartments, and each storage compartment has an openable and closable door at its front opening. Each storage compartment is sealed to prevent cold air leakage when the door is closed. In the refrigerator 1 of Embodiment 1, the uppermost storage compartment is the refrigerator compartment 5. Directly below the refrigerator compartment 5, on both sides, are two storage compartments: an ice-making compartment 7 and a freezing / thawing compartment 6. Furthermore, a freezer compartment 8 is provided directly below the ice-making compartment 7 and the freezing / thawing compartment 6, and a vegetable compartment 9 is provided at the very bottom, directly below the freezer compartment 8. Each storage compartment in the refrigerator 1 of Embodiment 1 has the above configuration, but this configuration is just an example, and the arrangement of each storage compartment can be appropriately changed during the design phase according to specifications, etc.

[0018] The refrigerator compartment 5 is maintained at a temperature that does not freeze food and other stored items, specifically in the range of 1°C to 5°C. The vegetable compartment 9 is maintained at a temperature equivalent to or slightly higher than the refrigerator compartment 5, for example, 2°C to 7°C. The freezer compartment 8 is set to a freezing temperature range for frozen storage, specifically in the range of -22°C to -15°C. The freezer / thawing compartment 6 is normally maintained at the same freezing temperature range as the freezer compartment 8, and in response to the user's electric field generation command, an electric field generation process is performed to thaw the stored items (frozen goods). Details regarding the configuration of the freezer / thawing compartment 6 and the electric field generation process will be described later.

[0019] A machine room 10 is provided at the top of the refrigerator 1. The machine room 10 houses components that constitute the refrigeration cycle, such as a compressor 19 and a dryer that removes moisture from the refrigeration cycle. The location of the machine room 10 is not limited to the top of the refrigerator 1, but is determined as appropriate according to the location of the refrigeration cycle, and may be located in other areas such as the bottom of the refrigerator 1.

[0020] A cooling chamber 11 is provided behind the freezer compartment 8 and vegetable compartment 9 in the lower area of ​​refrigerator 1. The cooling chamber 11 is equipped 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 (3, 4, 5, 6, 7). The cold air generated by the cooler 13 flows through air passages 12 connected to each storage compartment by the cooling fan 14 and is supplied to each storage compartment. A damper 12a is provided in the air passage 12 connected to each storage compartment, and each storage compartment is maintained at a predetermined temperature range by controlling the rotation speed of the compressor 19 and the cooling fan 14 and by controlling the opening and closing of the damper 12a. A defrost heater 15 is provided at the bottom of the cooling chamber 11 to remove frost and ice that accumulates on the cooler 13 and its surroundings. Below the defrost heater 15, a drain pan 16, a drain tube 17, and an evaporation tray 18 are provided, providing a configuration for evaporating moisture generated during defrosting.

[0021] The refrigerator 1 of Embodiment 1 is equipped with an operation unit 47 (see Figure 9, described later). The user can issue various commands to the refrigerator 1 using the operation unit 47 (for example, temperature setting for each storage compartment, rapid cooling command, electric field generation command, ice making stop command, etc.). The operation unit 47 also has a display unit that notifies the user of abnormalities, etc. The refrigerator 1 may also be equipped with a wireless communication unit and connected to a wireless LAN network so that the user can input various commands from an external terminal. Alternatively, the refrigerator 1 may be equipped with a voice recognition unit so that the user can input commands by voice.

[0022] Figures 2, 3, 5, and 6 are longitudinal cross-sectional views showing the freezing / thawing compartment 6 in the refrigerator 1 of Embodiment 1. The freezing / thawing compartment 6 is a freezer that freezes stored food and other items stored within it and maintains them at freezing temperatures. It also becomes a thawing compartment that performs electric field generation processing by dielectric heating when an electric field generation command is input to the refrigerator 1 for the stored items.

[0023] The characteristics of Figures 2, 3, 5, and 6 will be explained again in the "System Structure" section below.

[0024] In the freezing / thawing chamber 6, 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 through multiple cold air inlet holes 20 provided on the top surface of the freezing / thawing chamber 6, so that it can be maintained at the same freezing temperature range as the freezing chamber 8. A damper 12a is provided in the air passage 12 leading from the cooling chamber 11 to the freezing / thawing chamber 6, and the freezing / thawing chamber 6 is maintained at a predetermined freezing temperature range by controlling the opening and closing of the damper 12a, so that the stored items are frozen and preserved.

[0025] A cold air exhaust vent (not shown) is formed on the back of the freezing / thawing compartment 6. The cold air introduced into the freezing / thawing compartment 6 and used to cool the inside of the compartment returns to the cooling compartment 11 through the cold air exhaust vent and a return air passage (not shown), where it is recooled by the cooler 13. In other words, in the refrigerator 1 of Embodiment 1, the cold air formed by the cooler 13 is circulated.

[0026] In the freezing / thawing chamber 6, the top, back, both sides, and bottom surfaces that constitute the inner surface of the storage space are formed of inner surface members 32 (32a~32c) made of resin material molded from an electrically insulating material. A door 29 is provided at the front opening of the freezing / thawing chamber 6, and the storage space of the freezing / thawing chamber 6 is sealed when the door 29 is closed. In the freezing / thawing chamber 6 of Embodiment 1, 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 with the opening and closing operation of the door 29 in the front-to-back direction. The opening and closing operation of the door 29 in the front-to-back direction makes it easy to put food and other stored items into and take them out of the storage case 31.

[0027] [1-2. Dielectric heating mechanism for generating an electric field in the storage space] Next, we will describe the dielectric heating mechanism that generates an electric field in the storage space where the stored items in the freezing / thawing chamber 6 are located.

[0028] Furthermore, this dielectric heating mechanism allows for adjustment of heating capacity, such as output power. Therefore, if the amount of heat applied to the stored items exceeds the amount of cooling in the freezing / thawing chamber 6, the stored items will be heated. Conversely, if the amount of heat applied to the stored items falls below the amount of cooling in the freezing / thawing chamber 6, the stored items will be cooled.

[0029] Figure 9 is a block diagram showing the configuration of the dielectric heating mechanism provided in the refrigerator 1 of Embodiment 1. The dielectric heating mechanism in Embodiment 1 includes an oscillation circuit 22, a matching circuit 23, a first electrode 24, a second electrode 25, and a control unit 50, to which power from the power supply unit 48 is input to form a predetermined high-frequency signal. The oscillation circuit 22, which is constructed using semiconductor elements, is miniaturized and, as will be described later, is formed on an electrode holding substrate 52 in the electrode holding region 30 (see Figures 2, 3, 5, and 6), which is the space on the back side of the freezing / thawing chamber 6. The oscillation circuit 22 and the matching circuit 23 form a high-frequency electric field forming unit for forming a high-frequency electric field applied between the first electrode 24 and the second electrode 25.

[0030] The first electrode 24 is an electrode located on the top side of the freezing / thawing chamber 6. The second electrode 25 is an electrode located on the bottom side of the freezing / thawing chamber 6. The first electrode 24 and the second electrode 25 are arranged facing each other across the storage space (thawing space) of the freezing / thawing chamber 6, and are provided with an electrode holding substrate 52, which will be explained later in the "Circuit Board Configuration" section, so that the distance between them is set to a predetermined distance (H in Figure 8). As a result, in the dielectric heating mechanism of Embodiment 1, the first electrode 24 and the second electrode 25 are arranged substantially parallel to each other. In this invention, "substantially parallel" means essentially parallel, but also includes errors caused by variations in processing accuracy, etc.

[0031] The first electrode 24 is provided on one side of the storage space, and the second electrode 25 is provided on the other side of the storage space, separated by the storage space. The matching circuit 23 on the back side, the first electrode 24 on the top side, and the second electrode 25 on the bottom side, which constitute the dielectric heating mechanism, are covered by an internal component 32, which reliably prevents burning due to contact with the stored items.

[0032] In the configuration of Embodiment 1, the first electrode 24 is provided on the top surface of the storage space of the freezing / thawing chamber 6, and the second electrode 25 is provided on the bottom surface of the storage space of the freezing / thawing chamber 6. However, the present invention is not limited to this configuration, and any configuration in which the first electrode 24 and the second electrode 25 face each other across the storage space (thawing space) is acceptable, and similar effects can be achieved with an inverted arrangement or an arrangement facing each other in the left-right direction.

[0033] The oscillation circuit 22 outputs a high-frequency voltage in the VHF band (40.68 MHz in Embodiment 1). When the oscillation circuit 22 outputs a high-frequency voltage, an electric field is formed between the first electrode 24 and the second electrode 25 to which the oscillation circuit 22 is connected, and the stored material, which is a dielectric placed in the storage space between the first electrode 24 and the second electrode 25 of the freezing / thawing chamber 6, is dielectrically heated.

[0034] The matching circuit 23 adjusts the load impedance formed by the first electrode 24, the second electrode 25, and the stored material contained in the freezing / thawing chamber 6 to match the output impedance of the oscillation circuit 22. By matching the impedances, the matching circuit 23 minimizes reflected waves from the output electromagnetic wave.

[0035] The dielectric heating mechanism in Embodiment 1 is provided with an input / reflection wave detection unit 51 that detects the incident wave output from the oscillation circuit 22 to the first electrode 24 and the reflected wave returning from the first electrode 24 to the oscillation circuit 22. Therefore, the oscillation circuit 22 is electrically connected to the first electrode 24 via the input / reflection wave detection unit 51 and the matching circuit 23. The control unit 50 calculates the ratio of the reflected wave output to the incident wave output (reflectance) based on the incident wave and reflected wave detected by the input / reflection wave detection unit 51, and performs various controls based on the calculation result as described later. Alternatively, the ratio of the reflected wave output to the electromagnetic wave output (reflectance) may be calculated based on the set value of the electromagnetic wave output from the oscillation circuit 22 after impedance matching in the matching circuit 23 and the reflected wave detected by the input / reflection wave detection unit 51. Furthermore, the controls described later may be performed based only on the reflected wave output, regardless of the electromagnetic wave output set value or the detected value of the incident wave.

[0036] As shown in the control block diagram of Figure 9, in the dielectric heating mechanism, the control unit 50 drives and controls the oscillation circuit 22 and the matching circuit 23 based on signals from the operation unit 47 for user setting operations and the temperature sensor 49 for detecting the internal temperature. The control unit 50 is composed of a CPU, and various controls are performed by executing a control program stored in memory such as ROM.

[0037] [1-3. Circuit board configuration of the dielectric heating mechanism] Since it is desirable for the length of the positive electrode wiring connecting the oscillation circuit 22, the input / reflection wave detection unit 51, the matching circuit 23, and the first electrode 24 to be short, in this embodiment, the electrode holding substrate 52 (see Figures 2, 3, 5, and 6) containing these circuits, the first electrode 24, and the second electrode 25 are directly connected without using lead wires or coaxial cables, and the substrate is arranged in the electrode holding area 30 on the back side of the freezing / thawing chamber 6. This electrode holding substrate 52 is assumed to include at least the matching circuit 23.

[0038] The matching circuit 23 performs impedance matching by adjusting the values ​​of inductance and capacitance. Therefore, it generates heat, particularly due to losses in the inductor on the matching circuit 23. This heat generation is referred to as waste heat from the matching circuit 23. The matching circuit 23, and devices including metal components such as the first electrode 24, second electrode 25, and the electromagnetic shield 26 (described later) located around it, are prone to condensation in freezing temperatures, raising concerns about malfunctions due to water droplets and frost. However, by configuring the matching substrate 23 to facilitate the conduction of waste heat, malfunctions can be prevented. For this reason, it is essential that the electrode holding substrate 52 includes at least the matching circuit 23.

[0039] The first electrode 24, the second electrode 25, and the electromagnetic wave shield 26 (described later) generate heat due to a certain amount of electrical loss. In Embodiment 1, this heat generation is minimal and does not contribute to preventing condensation or frost formation. However, it is possible to prevent condensation and frost formation by deliberately using materials with high losses.

[0040] The operation to prevent condensation and frost formation using waste heat is performed when the possibility of condensation or frost formation is detected, regardless of whether an electric field needs to be generated inside the freezing / thawing chamber 6. That is, the oscillation circuit 22 is operated appropriately to deliberately generate waste heat.

[0041] Furthermore, in order to accurately determine whether impedance matching is sufficiently achieved by the matching circuit 23, it is desirable to configure the input / reflected wave detection unit 51 on the electrode holding substrate 52 and to combine it with the matching circuit 23 on a single substrate. This eliminates the need for lead wires, coaxial cables, and connectors to connect them between the matching circuit 23 and the input / reflected wave detection unit 51, thereby simplifying the structure.

[0042] Furthermore, although Figure 9 shows the input / reflected wave detection unit 51 and matching circuit 23 arranged on the electrode holding substrate 52, by composing the matching circuit 23, input / reflected wave detection unit 51, and oscillation circuit 22 all onto a single substrate, it becomes possible to suppress power transmission losses due to lead wires and coaxial cables and improve the accuracy of impedance matching.

[0043] The above circuits, for example, the oscillation circuit 22 and the matching circuit 23, may be electrically connected separately by lead wires or coaxial cables. In this case, a rational arrangement can be achieved by utilizing the available space inside the refrigerator, for example, by installing the oscillation circuit 22 in the machine room 10, which has ample free space. In this case, it is desirable to place the oscillation circuit 22 and the input / reflected wave detection unit 51 on a single circuit board in order to perform impedance matching including the coaxial cable.

[0044] [1-4. System Structure of the Dielectric Heating Mechanism] In the dielectric heating mechanism of Embodiment 1, configured as described above, the first electrode 24 and the second electrode 25 are arranged to face each other substantially parallel to one another, thereby ensuring uniformity of the electric field in the storage space of the freezing / thawing chamber 6. In order to arrange the first electrode 24 and the second electrode 25 substantially parallel to each other with a predetermined distance (H in Figure 8) between them, the dielectric heating mechanism of Embodiment 1 maintains the electrode spacing as described below.

[0045] Figure 8 shows the electrode holding area 30 on the back side of the freezing / thawing chamber 6 in Embodiment 1, and illustrates the electrode holding mechanism in the electrode holding area 30. Figure 8 is a view of the electrode holding area 30 from the back side, with the first electrode 24 positioned on the upper side (top side) and the second electrode 25 positioned on the lower side (bottom side). Positive electrode terminals 24a, 24b, and 24c are provided protruding from the back end of the first electrode 24. The positive electrode terminals 24a to 24c are bent at a right angle upward (top side) or downward (bottom side) from the back end of the first electrode 24. Similarly, cathode terminals 25a, 25b, and 25c are provided protruding from the center of the back end of the second electrode 25. The cathode terminals 25a to 25c are bent at a right angle upward (top side) or downward (bottom side) from the back end of the second electrode 25.

[0046] The first electrode 24 and the second electrode 25 are fixed to the upper and lower parts of the electrode holding substrate 52, and the matching circuit 23 and the input / reflected wave detection unit 51 are fixed on the electrode holding substrate 52, so that the first electrode 24 and the second electrode 25 are securely held by the electrode holding substrate 52. In this way, the electrode holding substrate 52 is configured to securely hold the first electrode 24 and the second electrode 25 with a predetermined distance (H in Figure 8). Furthermore, because the matching circuit 23 and the like are configured on the electrode holding substrate 52, the rigidity is increased by the copper foil wiring pattern, and it is configured to cantilever hold the first electrode 24 and the second electrode 25 with a predetermined opposing distance (H in Figure 8). In addition, as described above, the electrode holding substrate 52 may also be configured to include an oscillation circuit 22 and the like.

[0047] The positive terminals 24a to 24c of the first electrode 24 and the cathode terminals 25a to 25c of the second electrode 25 are connected to the respective connection terminals on the positive and cathode sides of the matching circuit 23. The connections between the positive terminals 24a to 24c and the cathode terminals 25a to 25c and the respective connection terminals of the matching circuit 23 are surface contact connections with a predetermined contact area to ensure reliability even when large currents flow. In Embodiment 1, the flat terminals are connected to each other by screws to ensure reliable surface contact connections. Note that any connection method that ensures reliable surface contact connections is acceptable and is not limited to screw connections. Furthermore, in order to implement the aforementioned condensation and frost prevention operation using waste heat, terminal connections with excellent thermal conductivity are necessary.

[0048] As described above, an electrode holding substrate 52 is provided on the back side of the freezing / thawing chamber 6 as an electrode holding mechanism, so that the first electrode 24 and the second electrode 25 are positioned facing each other in approximately parallel positions. Furthermore, in the configuration of Embodiment 1, in order to further ensure that the first electrode 24 and the second electrode 25 face each other in approximately parallel positions, the first electrode 24, the second electrode 25, and the electrode holding substrate 52 are integrated into a high-frequency heating module 53a in a state where the approximately parallel position is confirmed, and incorporated into the freezing / thawing chamber 6.

[0049] [1-5. Structure of the Freezer / Thawing Compartment] As described above, the insulated body of the refrigerator 1 is composed of an outer box 3 made of steel plate, an inner box 4 molded from resin, and an insulating material (for example, rigid polyurethane foam) 40 filled in the space between the outer box 3 and the inner box 4.

[0050] As shown in Figures 2 and 3, the freezing / thawing chamber 6 is constructed with an inner surface member 32a inside the insulation material 40 as its outer frame, and its outside is covered with an electromagnetic wave shield 26 (26a-26d). This electromagnetic wave shield 26 is provided to surround the freezing / thawing chamber 6 in order to prevent electromagnetic waves from leaking to the outside of the refrigerator 1. In addition, the electrode holding area 30 is separated from the freezing / thawing chamber by an inner surface member 32c, and a rear-side electromagnetic wave shield 26b is also installed on the rear side of the inner surface member 32c. The main purpose of the rear-side electromagnetic wave shield 26b is to prevent interference between the impedance and electric field of the freezing / thawing chamber 6 and the electrode holding substrate 52, which includes the matching circuit 23, by separating them.

[0051] Above the space enclosed by the inner surface member 32a, a flat inner surface member 32b is provided horizontally, and the first electrode 24 is mounted on the upper part of the inner surface member 32b. A second electrode 25 is also installed on the bottom surface of the inner surface member 32a, and the bottom surface of the inner surface member 32a and the inner surface member 32b are held approximately parallel at a predetermined distance (H in Figure 8). Thus, the first electrode 24 and the second electrode 25 can maintain an approximately parallel state by the electrode holding substrate 52 and the inner surface members 32a, 32b, and 32c. In the outer box 3, the parallelism between the top and bottom surfaces of the interior may be insufficient due to variations in the foaming of the filled foam insulation material 40, but with the above configuration, the interior is not affected by foaming and can be accurately and reliably maintained in an approximately parallel state.

[0052] In the manufacturing process, the high-frequency heating module 53a is pre-assembled and installed by inserting it into the outer casing 3 of the refrigerator 1, as shown in Figure 4. Furthermore, the refrigerator is completed by inserting the door unit, which includes the door 29, door-side electromagnetic shield 26d, gasket 36, storage case 31, etc., into the high-frequency heating module 53a.

[0053] Alternatively, the configurations shown in Figures 5, 6, and 7 may also be used. In Figures 5, 6, and 7, the configuration of the refrigerator 1, consisting of an outer box 3, an inner box 4 molded from resin, a foamed insulation material 40 filling the space between the outer box 3 and the inner box 4, inner surface members 32 (32a~32c) inside the insulation material 40 which constitute the outer frame of the freezing / thawing compartment 6, and an electromagnetic wave shield 26 on the outside, is the same as in Figures 2 and 3.

[0054] Above the space enclosed by the inner surface member 32, a first electrode 24 is mounted on the upper part of a horizontally positioned flat inner surface member 32b, and similarly, a second electrode 25 is installed on the bottom surface of a horizontally positioned flat inner surface member 32c below the space enclosed by the inner surface member 32a. The front sides of the inner surface members 32b and 32c are fixed by support columns 54, respectively, and the back sides are fixed by an electrode holding substrate 52 and the inner surface member 32c, holding the first electrode 24 and the second electrode 25 in a substantially parallel state.

[0055] Since the inner members 32b and 32c are held approximately parallel to each other at a predetermined distance (H in Figure 8), the first electrode 24 and the second electrode 25 can maintain an approximately parallel state by the electrode holding substrate 52, the support column 54, and the inner members 32b and 32c. The outer box 3 of the refrigerator 1 may have insufficient parallelism between the top and bottom surfaces due to variations in the foaming of the filled foam insulation material 40, but with the above configuration, it is not affected by foaming and can be reliably and accurately maintained in an approximately parallel state.

[0056] In this configuration, the high-frequency heating module 53b integrates an electrode holding substrate 52 which includes a first electrode 24, a second electrode 25, internal components 32a, 32b, 32c, a support column 54, a rear-side electromagnetic wave shield 26b that separates the electrode holding area 30 from the freezing / thawing compartment 6, and a matching circuit 23. In the manufacturing process, the high-frequency heating module 53a is pre-assembled and installed by inserting it into the outer casing 3 of the refrigerator 1 as shown in Figure 4. Furthermore, the refrigerator is completed by inserting the door unit, which includes the door 29, door-side electromagnetic wave shield 26d, gasket 36, storage case 31, etc., into the high-frequency heating module 53b.

[0057] Furthermore, the inner components 32a to 32c are preferably made of a general industrial ceramic material with a thermal conductivity of 10 W / (m·k) or less that is less prone to condensation even in a freezer environment, and in this embodiment, they are made of resin materials such as polypropylene, ABS, and polycarbonate. The electromagnetic wave shield 26 (26a to 26d) is made thinner than the inner components 32 (32a to 32c) to suppress its heat capacity. This prevents condensation on the electromagnetic wave shield 26 and on the inner components 32 (32a to 32c) that are in contact with the electromagnetic wave shield 26.

[0058] Thus, in the refrigerator 1 of Embodiment 1, since electrode holding mechanisms are provided on the back side, front side, or side side of the dielectric heating mechanism of the freezing / thawing chamber 6, the first electrode 24 and the second electrode 25 can be arranged with a highly accurate opposing distance, and can be reliably arranged substantially parallel to each other with a predetermined distance (H in Figure 8). As a result, the dielectric heating mechanism of the freezing / thawing chamber 6 is configured such that bias in the high-frequency electric field on the electrode surface is prevented, the high-frequency electric field is made uniform, and the electric field generation process for stored items (frozen products) can be performed uniformly. Furthermore, since the refrigerator is completed by inserting a pre-assembled unit as a high-frequency heating module, the manufacturing process is simplified as it eliminates the need for manufacturing work within the narrow refrigerator compartment.

[0059] [1-6. Electromagnetic Shielding Mechanism] As described above, in the freezing / thawing chamber 6, a dielectric material, which is the stored material, is placed in the atmosphere of a high-frequency electric field between the first electrode 24 and the second electrode 25 and heated by dielectric heating. Therefore, electromagnetic waves are emitted in the freezing / thawing chamber 6. In order to prevent these electromagnetic waves from leaking to the outside of the refrigerator 1, the refrigerator 1 of Embodiment 1 is provided with an electromagnetic wave shielding mechanism that surrounds the freezing / thawing chamber 6.

[0060] As shown in Figures 2 and 3, a top-side electromagnetic shield 26a is installed in the air passage 12 portion on the top side of the freezing / thawing chamber 6. The top-side electromagnetic shield 26a is installed on the upper surface of the insulating material 40 that constitutes the bottom side of the refrigerator chamber 5 directly above the freezing / thawing chamber 6, and is installed so as to cover the top side of the freezing / thawing chamber 6. The top-side electromagnetic shield 26a has multiple openings and is configured to reduce the effective facing area with respect to the first electrode 24.

[0061] The opening has a slit shape with the longer side running from the back to the front. Electromagnetic wave simulations have shown that this allows the magnetic field (current) generated from the positive terminals 24a to 24c towards the front to pass smoothly over the top electromagnetic wave shield 26a, thereby suppressing the leakage magnetic field that diffuses into the surroundings.

[0062] The top-side electromagnetic shield 26a configured in this way suppresses the generation of unwanted electric fields between it and the first electrode 24. The top-side electromagnetic shield 26a may also be a mesh structure with multiple openings. The top-side electromagnetic shield 26a may be installed inside the refrigerator compartment 5 located directly above the freezing / thawing compartment 6, but the refrigerator compartment 5 often has a partial freezing compartment or a chilled compartment, and the top surface of this partial freezing compartment or chilled compartment may be used as the electromagnetic shield.

[0063] Furthermore, a rear-side electromagnetic shield 26b is provided to cover the electrode holding area 30, which includes a matching circuit 23 and other components, located on the rear side of the freezing / thawing chamber 6. By providing the rear-side electromagnetic shield 26b in this manner, it is prevented that the electric field generated between the first electrode 24 and the second electrode 25, and the high-frequency noise generated from the matching circuit 23, will affect the operation (control) of the electrical components of the cooling fan 14 and damper 12a. An electromagnetic shield (not shown) is also provided on the side of the freezing / thawing chamber 6.

[0064] Next, we will explain the door-side electromagnetic shield 26d provided on the door 29 that opens and closes the front opening of the freezer / thawing compartment 6. Since the door 29 is configured to open and close relative to the main body of the refrigerator 1, if the electromagnetic shield provided on the door 29 is connected to the grounding part of the main body of the refrigerator 1 by a wired connection, the wired connection will repeatedly expand and contract due to the opening and closing of the door 29, and metal fatigue will accumulate in the wired connection. In such a connection configuration, it can cause the wired connection to break, so it is not desirable to connect the door-side electromagnetic shield 26d provided on the door 29 to the grounding part of the main body of the refrigerator 1 by a wired connection.

[0065] Generally, to prevent electromagnetic wave leakage, it is necessary to make the distance between the door-side electromagnetic shield 26d when the door 29 is closed and the cross rail 21 (connected to the outer casing 3, shown in Figure 1), which serves as the main body's electromagnetic shield, shorter than 1 / 4 of the wavelength λ of the electromagnetic wave. In Embodiment 1, the distance is further reduced to achieve a grounding effect without the need for a wired connection. 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 casing 3 is grounded, when the door 29 is closed, bringing the door-side electromagnetic shield 26d close to the cross rail 21 provides an effect equivalent to grounding by a wired connection. Furthermore, by making the end of the door-side electromagnetic shield 26d bent towards the main body of the refrigerator 1, it becomes easy to bring the door-side electromagnetic shield 26d close to the cross rail 21.

[0066] In addition to the cross rail 21, a configuration in which it is placed close to the electromagnetic shield 26 (26a, 26c) is also acceptable.

[0067] Next, we will explain the connection of electromagnetic shielding and other circuits to ground.

[0068] Figure 10 is a schematic circuit diagram of an AC / DC converter that drives various circuits. In this circuit, the DC / DC converter, which is obtained by rectifying the AC commercial power supply ACV with a bridge diode BD1 and rectifier capacitor C0, is a flyback switching power supply circuit, but it is not limited to this type; any switching power supply using a transformer, such as a forward type, push-pull type, or half-bridge type, is acceptable. Also, this circuit only shows the main circuit components, and noise filters, power control circuits, and protection circuits are omitted.

[0069] The AC commercial power supply ACV is converted to DC by a bridge diode BD1 and a rectifier capacitor C0, and this is referred to as the primary DC power supply DCV0 (first power supply section). The zero-volt reference potential of this primary DC power supply DCV0 is defined as the primary ground GND0 (first ground section).

[0070] The primary DC power supply DCV0 is applied to the primary winding P1 of the switching transformer T1 and switched by FET Q1 at a frequency of several tens of kHz. The power stored in the primary winding P1 is transmitted by electromagnetic induction to the electrically isolated secondary winding S1, where it is rectified by the secondary rectifier diode D1 and secondary rectifier capacitor C1, and the secondary DC power supply DCV1 is output. The secondary winding S2 has an output section between its ends, where it is rectified by the secondary rectifier diode D2 and secondary rectifier capacitor C2, and the secondary DC power supply DCV2, which has a lower voltage than the secondary DC power supply DCV1, is output. 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).

[0071] Furthermore, the primary DC power supply DCV0 is branched and applied not only to the switching transformer T1 but also 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 transmitted to the electrically isolated secondary winding S3 by electromagnetic induction, rectified by the secondary rectifier diode D3 and secondary rectifier capacitor C3, and the secondary DC power supply DCV3 (third power supply section) is output. The zero-volt reference potential of this secondary DC power supply DCV3 is set as the secondary ground GND2 (third ground section).

[0072] Furthermore, the insulation between the primary winding P1 and the secondary winding S1 within the switching transformer T1, and the insulation between the primary winding P2 and the secondary winding S3 within the switching transformer T2, shall be at least as effective as the basic insulation standards set forth in Japan's Electrical Appliances and Materials Safety Act or IEC standards.

[0073] Within the oscillation circuit 22, a small power signal of 40.68 MHz, allocated to the ISM band, is output by an oscillation source 22a using a crystal or the like. This signal is slightly amplified by the first amplifier circuit 22b, then further amplified by the second amplifier circuit 22c, and output towards the matching circuit 23. Note that the output frequency of the oscillation source 22a is not limited to 40.68 MHz.

[0074] In this embodiment, the secondary DC power supply DC1 is supplied to the second amplifier circuit 22c in the oscillation circuit 22, the secondary DC power supply DC2 is supplied to the oscillation source 22a, the first amplifier circuit 22b, the input / reflected wave detection unit 51, and the matching circuit 23 in the oscillation circuit 22, and the secondary DC power supply DC3 is supplied to the control unit 50.

[0075] As a result, the circuit system that uses the secondary ground GND1 as a zero-volt reference potential consists of the oscillation circuit 22, the input / reflected wave detection unit 51, the matching circuit 23, and the second electrode 25. In addition, the circuit system that uses the secondary ground GND2 as a zero-volt reference potential consists of the control unit 50.

[0076] Each of the electromagnetic shields, 26, 26a, 26b, the rear-side electromagnetic shield 26b, and the door-side electromagnetic shield 26d, should be insulated from the second electrode 25 (which is at the same potential as the secondary ground GND1), or, if not insulated, connected at a certain distance from the second electrode 25. This reduces the electric and magnetic fields applied to each electromagnetic shield and suppresses leakage to the outside. In other words, the effectiveness of the electromagnetic shielding is enhanced.

[0077] There are several ways to enhance the effectiveness of electromagnetic shielding, which are described below.

[0078] One method is to not connect each electromagnetic shield to any of the primary ground GND0, secondary ground GND1, or secondary ground GND2. This method is particularly effective when the total area or volume of the electromagnetic shield is above a certain level, and it minimizes adverse effects from noise, such as high-frequency leakage to the outside through the ground line.

[0079] Another method involves connecting each electromagnetic shield to the primary side ground GND0. The primary side ground GND0 is typically connected to the outer casing 3, which is made of metal material, and has a large grounding area. Therefore, the zero-volt reference potential of the primary side ground GND0 is the most stable, resulting in high effectiveness for each electromagnetic shield and less malfunction due to noise.

[0080] Another method involves connecting each electromagnetic shield to the secondary ground GND2. This method isolates the second electrode 25 and each electromagnetic shield in two stages using switching transformers T1 and T2, making it less likely for high-frequency noise to leak from the first electrode 24 to each electromagnetic shield, and thus stabilizing the electric field generation to the second electrode 25.

[0081] Another method involves connecting each electromagnetic shield to the secondary ground GND1, but at a location a certain distance away from the second electrode 25, at least outside each electromagnetic shield. This method provides a certain shielding effect, reduces leakage of high-frequency noise from the first electrode 24 to each electromagnetic shield, and stabilizes the electric field generation to the second electrode 25.

[0082] Since the effectiveness of the above-mentioned methods for enhancing shielding may vary depending on the system structure and wiring, it is necessary to select the optimal method by considering the electric field generation efficiency from the first electrode 24 to the second electrode 25 and the electromagnetic wave shielding effect.

[0083] Furthermore, in the refrigerator 1 of Embodiment 1, since the outer casing 3 is made of steel plate, this steel plate itself functions as an electromagnetic wave shield. Therefore, electromagnetic waves inside the refrigerator 1 are reliably prevented from leaking to the outside of the refrigerator 1.

[0084] In the electromagnetic shielding configuration described above, malfunctions caused by normal-mode noise generated within the system, common-mode noise conducted to secondary ground 1 or secondary ground 2, and radio wave leakage can be problematic. In particular, common-mode noise is often superimposed on the cable conducting the high-frequency output generated by the oscillation circuit 22, and radiates noise from the cable surface. For this reason, coaxial cables are usually used to conduct the high-frequency output, but common-mode noise can also be conducted outside the outer conductor, which is supposed to act as a shield, within the coaxial cable.

[0085] Figures 19a and 19b show a configuration that prevents malfunctions and radio wave leakage caused by common-mode noise. In Figure 19a, the oscillation circuit 22 and the input / reflected wave detection unit 51 are located away from the electrode holding substrate 52, which includes the matching circuit 23, and the coaxial cable 56a electrically connects the electrode holding substrate 52 and the input / reflected wave detection unit 51. The outer shell of the refrigerator's outer casing 3a is made of metal, and the coaxial cable 56 is wired inside the outer casing 3a, thereby suppressing the diffusion of leaked radio waves radiated due to common-mode noise conducted through the coaxial cable 56 to the outside of the refrigerator.

[0086] In Figure 19a, the coaxial cable 56a is routed so that it is in contact with the inside of the outer casing 3a at least once. The outer casing 3a has a large surface area and its reference potential is approximately the same as that of GND0 shown in Figure 10, thus it has the effect of diverting common-mode noise conducted to the coaxial cable 56 to the GND0 side.

[0087] Furthermore, in Figure 19b, the coaxial cable 56 is routed inside the outer casing 3a, but the coaxial cable 56b is routed so that it does not come into contact with the inside of the outer casing 3a.

[0088] The configuration shown in Figure 19a, or the configuration shown in Figure 19b, is selected based on the path by which common-mode noise is conducted through the coaxial cable 56 and the outer casing 3a, in order to suppress malfunctions and radio wave leakage.

[0089] Furthermore, the arrangement of coaxial cables 56a and 56b and the outer casing 3a must be wired to ensure that the configuration is either that shown in Figure 19a or Figure 19b. Designs where it is unclear which wiring configuration will be used during mass production are undesirable.

[0090] [1-7. Configuration of the first and second electrodes and thawing performance based on said configuration] Figure 11 is a plan view of the first electrode 24 and the second electrode 25 on the top surface of the freezing / thawing chamber 6, as seen from above.

[0091] As shown in Figure 11, the size of the first electrode 24 is slightly smaller in area than that of the second electrode 25. In addition, multiple electrode holes 41 and 42 are formed in the first electrode 24 and the second electrode 25. The multiple electrode holes 41 and 42 are elongated slits that extend from the rear side of the chamber, where the positive electrode terminals 24a to 24c and the cathode terminals 25a to 25c of the second electrode 25 are located, toward the front side. This shape makes it easier for the high-frequency current input from the positive electrode terminals 24a to 24c to flow from the rear side of the chamber toward the front side, and slightly increases the electric field strength generated between the two electrodes.

[0092] Furthermore, the electrode holes 41 and 42 provided in the first electrode 24 and the second electrode 25 are not positioned symmetrically, but are offset by approximately half the minor axis of the electrode hole 41. Since multiple electrode holes 41 are formed on the electrode surface of the first electrode 24, the regions where a strong electric field is formed on the electrode surface of the first electrode 24 are uniformly distributed, resulting in a configuration that enables uniform dielectric heating of the stored material. In other words, the edges of the openings in the electrode holes 41 become electric field concentration regions.

[0093] Note that the shape and arrangement of the electrode holes 41 and 42 shown in Figure 11 are illustrative examples, and the shape and arrangement of the electrode holes 41 and 42 should be designed appropriately considering efficiency and manufacturing costs, depending on the specifications and configuration of the refrigerator. For example, the shape of the electrode holes 41 and 42 may be a perfect circle, and it is desirable that the electrode holes 41 of the first electrode 24 and the second electrode 25 are not in vertically symmetrical positions, but are offset by about half the diameter of the holes.

[0094] In the configuration of Embodiment 1, the shape and arrangement of the electrode holes 41 of the first electrode 24 were described as being arranged in a configuration with multiple holes. However, the present invention is not limited to this configuration. For example, the first electrode 24 may have at least one opening, and the edge of that opening becomes an electric field concentration region on the electrode surface of the first electrode 24 where the electric field is concentrated. In other words, the present invention is sufficient as long as the electric field concentration region is dispersed on the electrode surface of the first electrode 24. Furthermore, in Embodiment 1, a configuration in which multiple electrode holes 42 are provided on the electrode surface of the second electrode 25 was described. However, the present invention is not limited to a configuration in which multiple electrode holes 42 are provided on the second electrode 25. The opening is sufficient as long as it is formed so that a desired electric field is formed between the electrodes of the first electrode 24 and the second electrode 25.

[0095] The electrode holding substrate 52 is configured to securely hold the first electrode 24 and the second electrode 25 with a predetermined distance (H in Figure 8), and the electrode distance H is shorter than the length of the long side of the first electrode 24 (D in Figure 11). It is desirable that the electrode distance H be shorter than the diameter of the first electrode if it is circular, or shorter than the major axis if it is elliptical.

[0096] Figure 12 shows the relationship between the electrode spacing H (see Figure 8) between the first electrode 24 and the second electrode 25 and the electric field strength between the two electrodes. As shown in Figure 12, the electric field strength tends to decrease as the electrode spacing H increases. In particular, the electric field strength decreases significantly when the electrode spacing H1 (100 mm) is exceeded, and when the electrode spacing H2 (125 mm) is exceeded, the electric field strength decreases to a level where high-frequency heating capability cannot be obtained. For these reasons, it is desirable that the electrode spacing H be 100 mm or less, and at least 125 mm or less.

[0097] The inventors performed simulations 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 with a second electrode 25 that does not have an electrode hole.

[0098] Figure 13A shows the results of a simulation using an electrode configuration with either a first electrode 24 or a second electrode 25 that does not have an electrode hole. Figure 13B shows the results of a simulation using an electrode configuration with either a first electrode 24 or a second electrode 25 that has an electrode hole. In Figures 13A and 13B, the darker areas represent regions where the electric field is concentrated. As is clear from these electric field simulation diagrams, compared to the electric field simulation diagram in Figure 13A, the dielectric heating configuration in Figure 13B shows reduced electric field concentration throughout the electrode, resulting in a more uniform electric field.

[0099] As shown in Figure 11, by arranging the electrode hole 41 of the first electrode 24 and the electrode hole 42 of the second electrode 25 so that their central axes extending in the vertical direction (opposing direction) do not coincide, electric field concentration is mitigated throughout the electrode. Furthermore, in the electrode configuration in which the electrode hole 41 of the first electrode 24 and the electrode hole 42 of the second electrode 25 are arranged so that their central axes extending in the vertical direction (opposing direction) coincide, electric field concentration is mitigated compared to a configuration in which a second electrode 25 without an electrode hole is provided, and electric field concentration in the corner portions is particularly mitigated.

[0100] In the freezer / thawing compartment 6 of the refrigerator 1 of Embodiment 1, as shown in Figures 2 and 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 freezer / thawing compartment 6 as the door 29 is opened and closed. In the configuration of Embodiment 1, rails are provided on both sides of the freezer / thawing compartment 6 so that the storage case 31 can move smoothly inside the freezer / thawing compartment 6. Sliding members that slide along these rails are also provided on both sides of the outside of the storage case 31. These rails and sliding members of the frame are positioned outside the dielectric heating region, which is the region where the first electrode 24 and the second electrode 25 of the freezer / thawing compartment 6 face each other, so as not to be dielectrically heated.

[0101] [1-8. Heat treatment operation by electric field generation] In the refrigerator 1 of Embodiment 1, when an electric field generation command is input, an electric field generation process is performed in the space between the first electrode 24 and the second electrode 25 of the freezing / thawing chamber 6. In the electric field generation process of Embodiment 1, as will be described later, the control unit 50 controls a dielectric heating mechanism having an oscillation circuit 22, an input / reflected wave detection unit 51, and a matching circuit 23, as well as a cooling mechanism including a refrigeration cycle such as a compressor 19 and a cooler 13, and a cold air introduction mechanism including a cooling fan 14 and a damper 12a.

[0102] In Embodiment 1, the electric field generation process applies a predetermined high-frequency voltage between the first electrode 24 and the second electrode 25, thereby dielectrically heating the food, which is a dielectric material, with the high-frequency electric field between the electrodes. During this dielectric heating, the control unit 50 controls the opening and closing of the damper 12a to continuously or intermittently introduce cold air. Figure 14 shows an example of the waveforms of the control signals for the dielectric heating mechanism (oscillation circuit 22) and the cold air introduction mechanism (damper 23) in the electric field generation process, along with the food temperature, the room temperature of the freezing / thawing chamber 6, and the humidity of the freezing / thawing chamber 6 at that time.

[0103] The configuration using VHF waves as the frequency characteristic for the electric field generation process is less prone to "partial boiling" than the configuration using microwaves. Furthermore, in order to improve the uniformity of thawing, the refrigerator 1 of Embodiment 1 is provided with an electrode holding substrate 52 to securely hold the first electrode 24 and the second electrode 25, which are substantially flat plate-shaped members, in substantially parallel positions with a predetermined distance (H in Figure 8).

[0104] As shown in Figure 14, for example, when performing a thawing process, when an electric field generation command is input (thawing start), the oscillation circuit 22 turns ON, and a high-frequency voltage of, for example, 40.68 MHz is applied between the first electrode 24 and the second electrode 25. At this time, the damper 12a is in the open state, so the room temperature of the freezing / thawing chamber 6 is maintained at the freezing temperature t1 (for example, -20°C). After a predetermined period has elapsed from the start of thawing, the damper 12a is closed. When the damper 12a is closed, the room temperature of the freezing / thawing chamber 6 begins to rise. In the electric field generation process in Embodiment 1, dielectric heating is performed and the opening and closing control of the damper 12a is controlled to suppress the rise in the surface temperature of the frozen product, thereby performing thawing without so-called "partial boiling".

[0105] 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 wave detection unit 51, relative to the electromagnetic wave supplied between the first electrode 24 and the second electrode 25, which has been matched by the matching circuit 23. When the reflectance reaches a preset threshold and the reflectance becomes large, the control unit 50 opens the damper 12a to lower the internal temperature of 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 (electric field generation space) of the freezing / thawing chamber 6 are dielectrically heated while maintaining the desired frozen state, and reach the desired thawed state.

[0106] The electric field generation process is completed when the desired thawing state is reached. In the electric field generation process of Embodiment 1, reflectance is used to detect the desired thawing state at which the electric field generation process is completed. As the melting of the stored material progresses due to dielectric heating, the number of molten water molecules in the stored material increases. As the number of molten water molecules in the stored material 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 electric field generation process, when the reflectance increases and reaches a preset threshold, the matching circuit 23 performs impedance matching to reduce the reflectance.

[0107] In the electric field generation process of Embodiment 1, the detection of thawing completion is defined as the moment when the reflectance after impedance matching by the matching circuit 23 exceeds the thawing completion threshold. The thawing completion threshold is used to detect when the thawing of the stored material has reached a desired thawing state. Here, the desired thawing state of the stored material is one in which a woman can cut the stored material with one hand, and the amount of drip from the stored material is very small. The thawing completion threshold is a value determined in advance through experimentation.

[0108] As shown in Figure 14, by controlling the opening and closing of the damper 12a, relatively low-humidity cold air that has passed through the air passage 12 is supplied to the freezing / thawing chamber 6 from the cold air inlet 20. As a result, the humidity in the freezing / thawing chamber 6 never reaches 100%, and condensation inside the freezing / thawing chamber 6 is prevented.

[0109] Furthermore, the method for calculating reflectance in this embodiment is not limited to the ratio (reflectance) of the reflected wave to the incident wave detected by the incident wave detection unit 51. For example, it may also be a method in which only the reflected wave is detected and the ratio with the output preset in the oscillation circuit 22 is calculated.

[0110] Alternatively, the electric field generation process may be controlled using only the reflected wave detected by the input reflected wave detection unit 51, regardless of the output, rather than using reflectivity. The same applies to the control using reflectivity described below.

[0111] [1-9. Preservation operation by generating an electric field] Figure 15 is a flowchart showing the control process for cooling and generating an electric field in the freezing / thawing chamber 6 to bring food to a desired state. Each step shown in the flowchart of Figure 15 is performed by the CPU of the control unit 50 executing a control program stored in memory such as ROM. As mentioned above, when the reflectance after impedance matching by the matching circuit 23 in the electric field generation process exceeds the threshold for thawing completion, the post-electric field generation process control shown in Figure 15 is performed. For example, after the thawing process is completed, the stored food is maintained in a desired thawed state. One way to do 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 way 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 low-output high-frequency electric field, or intermittently apply high-frequency to perform cooling and heating and maintain the stored food in a desired temperature range. Furthermore, the room temperature of the freezing / thawing chamber 6 can also be periodically varied. For example, periodically varying the temperature to -12°C to -5°C can affect the composition of the food. In the above method, cooling and heating are performed by applying a reduced-output high-frequency electric field, or by intermittently applying high-frequency fields, to maintain the stored items within the desired temperature range.

[0112] As shown in step 101 of Figure 15, after the preservation process starts, the presence or absence of stored items in the freezing / thawing chamber 6 is constantly detected (step 101). The presence or absence of stored items in the freezing / thawing chamber 6 is detected using the reflectance, which is constantly detected. For this reason, the matching circuit 23 is always operating intermittently, and low-power electromagnetic waves are intermittently output from the first electrode 24. The control unit 50 compares the reflectance with a preset threshold for the presence or absence of stored items to determine the presence or absence of stored items in the freezing / thawing chamber 6.

[0113] In step 101, if it is detected that no stored items are present in the freezing / thawing chamber 6, the room temperature of the freezing / thawing chamber 6 is set to the freezing temperature range, for example, -18°C to -20°C (step 105).

[0114] In step 101, when the presence of stored items is detected in the freezing / thawing chamber 6, it is determined by the change in reflectance whether or not the stored items include thawed, non-frozen products.

[0115] Even after the electric field generation process for the stored items is completed, the user may not immediately remove the items from the freezing / thawing compartment 6. In such cases, the refrigerator 1 of Embodiment 1 is configured to maintain a slightly freezing temperature range for a predetermined time, which is sufficient to maintain the desired thawed state for the stored items in the freezing / thawing compartment 6. If the stored items remain stored for longer than this predetermined time, the refrigerator 1 of Embodiment 1 controls the temperature of the freezing / thawing compartment 6 to shift to the freezing temperature range in order to maintain the freshness of the stored items. In step 102, if it is determined that the time since thawing has been completed has exceeded the predetermined time while the thawed stored items remain stored, the process proceeds to step 105, and a freezing process is performed to set the temperature of the freezing / thawing compartment 6 to the freezing temperature range.

[0116] If it is determined that no thawed, unfrozen items are stored in the freezer / thawing compartment 6, in step 103, if, for example, the food temperature exceeds the target temperature, a freezing operation is performed (step 105); otherwise, an electric field is generated to raise the temperature of the food. A specific example of this control is described below. In the refrigerator 1 of Embodiment 1, dielectric heating is performed to freeze food items in a desired state during the freezing process, while maintaining the room temperature of the freezing / thawing chamber 6 at the freezing temperature range. Generally, when food is frozen, frost formation occurs on the inner surface of the food packaging due to moisture inside the freezing / thawing chamber 6 and moisture inside the food. When such frost formation occurs on the surface of the food, the food dries out, becomes dry and crumbly, and is no longer delicious or fresh ("freezer burn"). To prevent this, the refrigerator 1 of Embodiment 1 performs dielectric heating simultaneously with the cooling operation.

[0117] Figures 16A and 16B are waveform diagrams showing the state of each element during the cooling operation. Figure 16A is a waveform diagram showing the cooling operation during frozen storage in a conventional refrigerator, and Figure 16B is a waveform diagram showing the cooling operation performed in the freezing / thawing compartment 6 of the refrigerator 1 of Embodiment 1.

[0118] In Figure 16A, (1) is a waveform diagram showing the ON / OFF state of the cooling operation. The ON / OFF state 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 that cold air is introduced into the freezer compartment, and OFF indicates that the damper is closed and the introduction of cold air into the freezer compartment is blocked. Therefore, as shown in the waveform diagram (2) of Figure 16A, the temperature of the food in the freezer compartment will fluctuate greatly up and down around the preset freezing temperature (e.g., -20°C) T1. As a result, evaporation of moisture and frost formation will occur repeatedly on the surface of the food in the freezer compartment, and the food may not be frozen to a desirable state.

[0119] On the other hand, in Figure 16B, which shows the cooling operation of Embodiment 1, unlike conventional cooling operations, dielectric heating is performed in addition to cooling the food. (1) in Figure 16B is a waveform diagram showing the opening and closing operation of the damper 12a. ON indicates the damper 12a is open, and cold air is introduced into the freezing / thawing chamber 6 through the air passage 12 and the cold air introduction hole 20. OFF indicates the damper 12a is closed, and the introduction of cold air into the freezing / thawing chamber 6 is blocked. Since the introduction of cold air in the cooling operation of Embodiment 1 is performed simultaneously with dielectric heating, the introduction time of cold air is set to be longer than in the conventional example, which increases the cooling capacity.

[0120] Figure 16B (2) is a waveform diagram showing the operating state of dielectric heating when the oscillation circuit 22 is driven and controlled. Dielectric heating is performed simultaneously when the damper 12a is open.

[0121] In the cooling operation in Embodiment 1, dielectric heating is performed with a lower output compared to the defrosting operation. The output power is adjusted by the power supplied to the oscillation circuit 22 or by PWM control of the oscillation circuit 22.

[0122] As a result, as shown in (3) of Figure 16B, the food temperature in the freezing / thawing chamber 6 is maintained at a preset freezing temperature (e.g., -20°C) T1, and fluctuations in food temperature are suppressed.

[0123] Experiments have shown that frost formation can be eliminated if the food temperature fluctuation is approximately 0.1K or less. At the very least, the less the food temperature fluctuation, the more effectively frost formation can be suppressed. Furthermore, within the food, dielectric heating at the same frequency as during thawing, but with a lower output power, has the effect of suppressing the elongation of ice crystals. When dielectric heating is performed, the electric field tends to concentrate at the tips of ice crystals formed inside the food, so even if the temperature inside the freezing / thawing chamber 6 is below the maximum ice crystal formation zone, the ice crystals will only elongate slowly.

[0124] As described above, in the refrigerator 1 of Embodiment 1, dielectric heating is performed even during the cooling operation while freezing, making it possible to freeze and preserve frozen items in the desired state.

[0125] [1-10. Freezing operation due to electric field generation] In the refrigerator 1 of Embodiment 1, it is possible to perform freezing on newly placed non-frozen food in the freezing / thawing compartment 6 based on a user command from the operation unit 47. Figure 17 is a waveform diagram showing the state of each element in the rapid cooling operation, which is the freezing process. In Figure 17, (a) is a graph showing whether or not there is stored food in the freezing / thawing compartment 6. The determination of whether or not there is stored food in the freezing / thawing compartment 6 is made by the control unit 50 based on the ratio (reflectance) between the reflected wave detected by the input / reflected wave detection unit 51 and the output electromagnetic wave. Figure 17(b) shows that the control unit 50 intermittently acquires information from the matching circuit 23 and the input / reflected wave detection unit 51. Figure 17(c) is a graph showing an example of the change in reflectance. The control unit 50 determines that food, which is stored food, has been placed in the freezing / thawing compartment 6 when the reflectance falls below the first threshold R1.

[0126] During the rapid cooling operation of food stored in the freezing / thawing chamber 6, the rotational speed of the compressor 19 and cooling fan 14 of the cooling mechanism is increased to enhance the cooling capacity and enable forced continuous operation. In addition, the damper 12a of the air passage 12 leading to the freezing / thawing chamber 6 is forcibly driven in a continuously open state, and the cold air introduction mechanism is driven and controlled to introduce cold air (see waveform diagram in Figure 17(d)).

[0127] During rapid cooling, dielectric heating 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 at this time is at a lower power output than during thawing, at several tens of watts or less, and is performed intermittently (period h in Figure 17(e)). To initiate the dielectric heating, the detection of the food temperature entering the maximum ice crystal formation zone is performed by an increase in the change in reflectance when the food passes through the latent heat region. In Embodiment 1, the dielectric heating is initiated when the detected reflectance enters a preset second threshold R2 (see Figure 17(e)). The dielectric heating continues in the region from the second threshold R2 to the third threshold R3, which is considered the maximum ice crystal formation zone for the food. When a predetermined time (t2) has elapsed since the reflectance entered the third threshold R3, it is determined that the food has passed the maximum ice crystal formation zone, and the dielectric heating is stopped.

[0128] As described above, when it is determined that the food has passed the maximum ice crystal formation zone, the dielectric heating operation is stopped, the rapid cooling operation is terminated, and the system transitions to normal cooling. In this way, even when performing rapid cooling, the dielectric heating operation can be performed for a desired period of time to bring the food to a desirable frozen state.

[0129] [1-11. Safety control via door switches] In this embodiment, as described above, an electromagnetic wave shield 26 is provided surrounding the freezing / thawing compartment 6 to prevent electromagnetic waves from leaking outside the refrigerator 1. Furthermore, since the outer casing 3 is made of steel plate, and this steel plate itself functions as an electromagnetic wave shield, external leakage of electromagnetic waves is prevented when the door 29 is closed.

[0130] However, when door 29 is opened, electromagnetic waves may leak from the opening. Furthermore, there is a concern that high-frequency waves may be applied to the human body if the user puts their hand inside the storage unit through the opening, so countermeasures are necessary.

[0131] Therefore, in this embodiment, when the door opening / closing detection means 55a (see Figure 9), which detects that the door 29 has been opened, detects that the door 29 is open, the oscillation circuit 22 is stopped and the power supply to the first electrode 24 is stopped. Although refrigerators generally have multiple doors, if the electromagnetic wave shield 26 is functioning sufficiently, even if the door opening / closing detection means 55b for the refrigerator compartment 5, the door opening / closing detection means 55c for the ice-making compartment 7, the door opening / closing detection means 55d for the freezer compartment 8, and the door opening / closing detection means 55e for the vegetable compartment detect that the door of a storage compartment other than the freezer / thawing compartment 6 has been opened, there is no external leakage of electromagnetic waves exceeding the specified amount, so the oscillation circuit 22 does not stop and continues to operate.

[0132] However, this does not apply if the freezing / thawing chamber 6 cannot be adequately enclosed by the electromagnetic shield 26 due to design limitations.

[0133] For example, if an electromagnetic wave shield 26 cannot be constructed on the top surface of the freezing / thawing compartment 6, the oscillation circuit 22 will be stopped if the door of the storage compartment above it (refrigerator compartment 5 in the layout of Figure 1) is opened. Similarly, if an electromagnetic wave shield 26 cannot be constructed on the bottom surface of the freezing / thawing compartment 6, the oscillation circuit 22 will be stopped if the door of the storage compartment below it (freezer compartment 8, vegetable compartment 9 in the layout of Figure 1) is opened. Furthermore, if an electromagnetic wave shield 26 cannot be constructed on the side surface of the freezing / thawing compartment 6, the oscillation circuit 22 will be stopped if the door of the storage compartment to the side of that compartment (ice-making compartment 7 in the layout of Figure 1) is opened. In this way, the oscillation circuit 22 is stopped when the door of a storage compartment in a direction where an electromagnetic wave shield 26 cannot be constructed is opened, thereby preventing leakage of electromagnetic waves.

[0134] The following are some ways to stop the oscillation circuit 22.

[0135] Figure 18A shows the means by which the door open / close detection means 55a cuts off the power supply from the power supply unit 48 to the oscillation circuit 22. The door open / close detection means 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, and its operation is reliably stopped.

[0136] Furthermore, Figure 18B shows a means by which the door opening / closing detection means 55a stops the operation of the power control unit 48a that controls the power supply unit 48. The door opening / closing detection means 55a is a switch mechanism similar to that in Figure 18A, and when the door 29 is opened, the power supply to the power control unit 48a is stopped, which also cuts off the power supply from the power supply unit 48 to the oscillator unit 22, causing it to stop. In Figure 18B, the operation is stopped by cutting off the power supply to the circuit in the power control unit 48a, but it is also possible to stop it by causing the overcurrent protection circuit in the power control unit 48a to recognize an overcurrent condition, or by causing the power supply unit 48 to recognize an overload condition and cause it to stop.

[0137] Furthermore, Figure 18C shows that the open / closed state of the door 29 can be determined not only by the door open / closed detection means 55a but also by the magnetic sensor 55f. The magnetic sensor 55f outputs an open / closed signal for the door 29 to the control unit 50, and the control unit 50 receives the signal from the magnetic sensor 55f and outputs an operation / failure signal for the power supply control unit 48a. Between the magnetic sensor 55f and the control unit 50, the door open / closed detection means 55a is inserted, which conducts when the door 29 is closed and disconnects when the door 29 is open, preventing the output of a signal and stopping the operation of the power supply unit 48.

[0138] Because the power supply and / or control signal conduction / interruption are implemented in hardware, the system is highly resistant to high-frequency noise or external noise, and less prone to malfunction.

[0139] In Figures 18B and 18C, the door opening / closing detection means 55a is a switch mechanism that conducts when the door 29 is closed and disconnects when the door 29 is open. However, a means that disconnects when the door 29 is closed and conducts when the door 29 is open may also be used. In this case, it is necessary to reverse the H / L logic for stopping the power control unit 48a.

[0140] In the refrigerator of Embodiment 1, the freezer / thawing compartment 6 was described as having both a freezing function and a thawing function, but it may also be configured as a thawing compartment with only a thawing function.

[0141] As described above, in the refrigerator of this disclosure, as explained in Embodiment 1, the electric field is made uniform in the thawing space of the freezing / thawing chamber, and desired dielectric heating can be performed in the electric field generation process and freezing process for stored items held in the thawing space. Therefore, according to the refrigerator of this disclosure, it is possible to freeze, store, and thaw stored items in the storage chamber in a desired state, and a refrigerator with highly reliable cooling, storage, and thawing functions can be provided. In other words, it has the excellent effect of being able to freeze and store stored items in a desired state, and to thaw frozen stored items in a desired state in a short time, and by using a dielectric heating mechanism composed of semiconductor elements, it is possible to miniaturize the refrigerator as a refrigerator with a thawing function.

[0142] [2-1. Effects, etc.] As described above, the refrigerator in the embodiment of this disclosure includes at least one storage chamber having a space for storing stored goods, an oscillator that forms high-frequency power, a first electrode and a second electrode that receive the high-frequency power formed from the oscillator and generate an electric field in the storage space, a load impedance formed by the first electrode, the second electrode and the stored goods contained in the storage chamber, a matching unit that matches the output impedance of the oscillator, high-frequency wiring that directly or indirectly connects the oscillator and the matching unit, and noise suppression means for preventing noise leakage from the high-frequency wiring, thereby suppressing malfunctions caused by high-frequency noise and radio wave leakage to the outside.

[0143] Although the present invention has been described above with a certain degree of detail in its embodiments, the disclosure of Embodiment 1 is subject to change in the details of its configuration, and substitutions, combinations, and changes in the order of elements in the embodiments can be implemented without departing from the claimed scope and spirit of the present invention. [Industrial applicability]

[0144] The refrigerator of the present invention can process frozen, stored, and thawed items to achieve desired states, thereby enhancing the added value, reliability, and safety of the refrigerator, and thus possessing high market value, making it suitable for application to various types of refrigerators. [Explanation of Symbols]

[0145] 1. Refrigerator 3, 3a Outer box 4 Inner box 5. Refrigerated compartment 6. Freezing / Thawing Room (Storage Room) 7 Ice maker 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 Evaporating dishes 19 Compressor 20 Cold air inlet holes 21 Crossrail 22. Oscillator circuit (oscillator section) 22a Oscillator 22b First Amplifier Circuit 22c Second Amplifier Circuit 23 Matching circuit (matching section) 24 First electrode 24a~24c Positive terminal 25 Second electrode 25a~25c Cathode terminal 26 Electromagnetic wave shielding (shielding section) 26a Top-side electromagnetic shielding 26b Rear-side electromagnetic shielding 26c Bottom-side electromagnetic shielding 26d Door-side electromagnetic shielding 29 Doors 30 Electrode holding area 31 Storage Cases 32a~32c Inner surface material 36 Gaskets 40 Insulation 41 Electrode hole (first electrode hole) 42 Electrode hole (second electrode hole) 47 Control section 48 Power supply section 49 Temperature Sensor 50 Control Unit 51 Input / Reflected Wave Detection Unit 52 Electrode holding board 53 frames 54 Post 55a~f Door opening / closing detection means 56a, b Coaxial cable D Long side dimension of the first electrode H Installation interval (electrode spacing)

Claims

1. A storage room having space for storing preserved items, An oscillator that generates high-frequency power, A first electrode and a second electrode that receive high-frequency power generated from the oscillator and generate an electric field in the storage space, A load impedance formed by the first electrode, the second electrode, and the stored material contained in the storage chamber, and a matching unit that matches the output impedance of the oscillator with the load impedance, A refrigerator comprising high-frequency wiring that directly or indirectly connects the oscillator and the matching unit, and noise suppression means for preventing noise leakage from the high-frequency wiring, The matching unit is located in the electrode holding region on the rear side of the storage chamber. A refrigerator characterized in that the waste heat generated in the matching section is configured to conduct heat to the metal member of the electrode holding region, thereby suppressing condensation or frost formation in the electrode holding region.

2. The storage chamber is provided with a metal enclosure that surrounds the outside of the storage chamber. The refrigerator according to claim 1, wherein the noise suppression means is configured such that most of the high-frequency wiring is routed inside the metal casing.

3. The refrigerator according to claim 2, wherein the noise suppression means is configured such that the inside of the metal housing and the high-frequency wiring are in contact at least one place.

4. The refrigerator according to claim 2, wherein the noise suppression means is configured such that the inside of the metal housing and the high-frequency wiring do not come into contact within a path of 50 cm from the matching section.

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