Heating device

Abstract

Provided is a heating device capable of shortening thawing time. The heating device is provided with a housing for accommodating an object to be heated, a heating unit for heating the object to be heated, and a control unit for controlling the heating unit. The control unit first dielectrically heats the object to be heated by an alternating electric field of a first frequency, and then microwave-heats the object to be heated by microwaves of a second frequency higher than the first frequency.

Description

Technical Field

[0001] The present invention relates to a heating device. Background Art

[0002] In recent years, as an example of a heating device, a heating cooker capable of thawing has been developed, as disclosed in Japanese Patent Application Laid-Open No. 9-08246. In the heating device disclosed in Patent Document 1, microwave heating and dielectric heating are alternately performed when thawing a frozen object to be heated. Summary of the Invention

[0003] In the aforementioned Japanese Patent Application Laid-Open No. 9-08246, microwave heating is first performed, followed by dielectric heating, whereby microwave heating and dielectric heating are alternately repeated. According to this technique, microwave heating is initially performed on a frozen object. In this case, the frozen object absorbs the microwave energy and cannot be thawed. As a result, microwave energy is wasted, prolonging the thawing time of the object.

[0004] The present invention has been made in view of the above problems. An object of the present invention is to provide a heating device that can shorten the thawing time.

[0005] The heating device disclosed herein comprises: a shell that accommodates a heating object; a heating unit that heats the heating object; and a control unit that controls the heating unit. The control unit first performs dielectric heating on the heating object using an alternating electric field of a first frequency, and then performs microwave heating on the heating object using microwaves of a second frequency that is higher than the first frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a diagram showing a schematic configuration of a heating device according to the first embodiment. Figure 2 This is a flowchart for explaining the processing executed by the control unit of the heating device according to the first embodiment. Figure 3 This is a graph showing the relationship between the temperature of the surface portion and the center portion of the heating object heated by the heating device of the first embodiment and the heating time. Figure 4 It is a diagram showing a schematic configuration of a heating device according to a second embodiment. Figure 5 This is a flowchart for explaining the processing executed by the control unit of the heating device according to the second embodiment. Figure 6 It is a diagram showing a schematic configuration of a heating device according to a third embodiment. Figure 7This is a flowchart for explaining the processing executed by the control unit of the heating device according to the third embodiment. DETAILED DESCRIPTION

[0007] Hereinafter, the heating device according to the embodiment of the present disclosure will be described with reference to the accompanying drawings. In addition, regarding the drawings, the same or equivalent elements are marked with the same reference numerals and will not be described again.

[0008] (First embodiment) Figures 1 to 3 The following describes the heating device 10 according to the first embodiment.

[0009] Figure 1 It is a figure which shows the schematic structure of the heating device 10 of this embodiment.

[0010] The heating device 10 of this embodiment is generally a heating cooking machine called a microwave oven, but the heating device 10 can be any type as long as it can heat the heating object OB. The heating object OB of this embodiment is food, but any item that can be heated within the housing 1 can be used as the heating object.

[0011] The heating device 10 includes a housing 1 , a heating unit 23 , a non-contact temperature sensor 4 , a camera 5 , an operation panel 6 , an antenna 7 , and a control unit 8 .

[0012] The housing 1 is configured to accommodate the object to be heated OB. Figure 1 In the figure, the door provided on the housing 1 is not shown.

[0013] The heating unit 23 has the function of heating the object OB using an alternating electric field E and microwaves M. The heating unit 23 includes a dielectric heater 2 and a microwave heater 3. The dielectric heater 2 has a pair of opposing electrodes. The dielectric heater 2 generates an alternating electric field E between the pair of electrodes, thereby dielectrically heating the object OB placed between the pair of electrodes. The microwave heater 3, known as a magnetron, performs microwave heating on the object OB by irradiating the object OB with microwaves M.

[0014] In this specification, the heating unit 23 generates an alternating electric field E with a frequency of 10 kHz or higher and less than 300 MHz during dielectric heating, and generates microwaves M with a frequency of 300 MHz or higher and less than 30 GHz during microwave heating. Dielectric heating is used to heat the surface of the object OB. Microwave heating is performed to conduct heat from the surface to the center of the object OB. In this embodiment, the frequency of the alternating electric field E during dielectric heating is, for example, 40 MHz, and the frequency of the microwaves M during microwave heating is, for example, 2.45 GHz.

[0015] In this embodiment, the heating unit 23 is composed of the dielectric heater 2 and the microwave heater 3 provided independently of each other. However, the heating unit 23 may perform dielectric heating and microwave heating simultaneously using a single heater.

[0016] The non-contact temperature sensor 4 is composed of an infrared sensor called a thermopile or a thermography sensor. The non-contact temperature sensor 4 is disposed within the housing 1. The non-contact temperature sensor 4 estimates the surface temperature of the heating object OB by detecting infrared image data generated by infrared rays emitted from the heating object OB.

[0017] A camera 5 is also disposed within the housing 1. The camera 5 is an RGB camera capable of acquiring RGB image data that can identify the surface color of the heating object OB. RGB image data is, for example, image data represented by the three primary colors of red, green, and blue. However, the camera 5 need not be an RGB camera. For example, the camera 5 may be an infrared camera. The camera 5 acquires RGB image data of the heating object OB and transmits the RGB image data to the control unit 8.

[0018] The operation panel 6 has an operation unit operable by the user, and based on the user's operation of the operation unit, various command signals are sent to the control unit 8. For example, when the user operates the operation unit of the operation panel 6, a command signal instructing the heating object OB to thaw is sent from the operation panel 6 to the control unit 8.

[0019] Antenna 7 receives electromagnetic waves reflected by the object OB (hereinafter referred to as "reflected waves"). The intensity of these reflected waves allows control unit 8 to determine the degree of thawing of the central portion of the object OB. Furthermore, as the thawing progresses in the central portion of the object OB, the intensity of the electromagnetic waves reflected by the object OB increases, and thus the intensity of the reflected waves received by antenna 7 also increases.

[0020] The control unit 8 is a device called a controller and includes a memory storing a program for controlling the operation of the heating device 10 and a processor. The control unit 8 receives command signals from the operation panel 6, infrared image data of the surface of the heating object OB from the non-contact temperature sensor 4, and RGB image data of the surface of the heating object OB from the camera 5. The control unit 8 controls the heating unit 23 based on the received signals and data.

[0021] The control unit 8 estimates the size and type of the heating object OB based on sample images (such as machine learning results such as food images of each type) pre-stored in the memory according to the size and type of each heating object OB, and the RGB image data obtained by the camera 5.

[0022] Furthermore, the control unit 8 estimates the surface temperature of the object being thawed based on data such as sample images pre-stored in memory according to the size and type of the object being thawed, and infrared image data acquired by the non-contact temperature sensor 4. In this embodiment, the control unit 8 determines whether to terminate the repeated dielectric heating and microwave heating. Thus, when the control unit 8 determines that the surface temperature of the object being thawed reaches 0°C or higher, the control unit 8 terminates the dielectric heating by the dielectric heater 2 and initiates the microwave heating by the microwave heater 3. Furthermore, when the control unit 8 determines that the surface temperature of the object being thawed reaches 5°C or higher, the control unit 8 terminates the microwave heating by the microwave heater 3 and simultaneously terminates the dielectric heating by the dielectric heater 2.

[0023] Furthermore, the control unit 8 determines the number of times dielectric heating and microwave heating are repeated, that is, the condition for ending the repetition of dielectric heating and microwave heating, based on the intensity of the reflected wave on the heating object OB acquired by the antenna 7 .

[0024] However, the control unit 8 may also determine the execution time of each of the alternately repeated dielectric heating and microwave heating, and the number of repetitions of dielectric heating and microwave heating, based on the estimated size and type of the object to be heated OB. The details of the determination method in this case will be described in the subsequent embodiments.

[0025] The control unit 8 is equipped with a timer. The timer measures the duration of application of the 40 MHz alternating electric field E by the dielectric heater 2 to the heating object OB, and the duration of irradiation of the 2.45 GHz microwaves by the microwave heater 3 to the heating object OB. Furthermore, the control unit 8 is equipped with a counter for counting the number of repetitions of dielectric heating and microwave heating.

[0026] In summary, the control unit 8 first performs dielectric heating on the object OB using the alternating electric field E of a first frequency, and then performs microwave heating on the object OB using microwaves M of a second frequency higher than the first frequency. In this manner, dielectric heating, which is effective for thawing the surface of the object OB, is first performed, followed by microwave heating, which is effective for thawing the center of the object OB. Consequently, the microwave energy emitted by the heating unit 23 is effectively utilized, thereby shortening the thawing time of the frozen object OB.

[0027] The control unit 8 controls the heating unit 23 to alternately and repeatedly perform dielectric heating and microwave heating. This repeated operation allows the surface, center, and intermediate portions of the object OB to be thawed uniformly and rapidly. It should be noted that, as an alternative to the repeated operation, the initial dielectric heating of the object OB using the alternating electric field E of the first frequency can be extended, and microwave heating of the object OB using microwaves M of the second frequency can be performed only once.

[0028] When the surface temperature estimated based on the infrared image data acquired by the non-contact temperature sensor 4 reaches a first temperature (e.g., 0°C) or higher, the control unit 8 controls the heating unit 23 to switch from dielectric heating to microwave heating. When the surface temperature estimated based on the infrared image data acquired by the non-contact temperature sensor 4 reaches a second temperature (e.g., 5°C) higher than the first temperature, the control unit 8 controls the heating unit 23 to switch from microwave heating to dielectric heating.

[0029] More specifically, the control unit 8 determines whether the surface temperature of the heating object OB is equal to or higher than 0°C based on the infrared image data acquired by the non-contact temperature sensor 4. Therefore, when the control unit 8 determines that the surface temperature of the heating object OB is equal to or higher than 0°C, the dielectric heater 2 terminates the dielectric heating.

[0030] Furthermore, the control unit 8 determines whether the surface temperature of the object OB reaches 5° C. or higher based on the infrared image data acquired by the non-contact temperature sensor 4. If the surface temperature of the object OB reaches 5° C. or higher, the control unit 8 ends the microwave heating by the microwave heater 3.

[0031] In the present embodiment, the control unit 8 determines whether the temperature of the central portion of the object to be heated OB has reached 0° C. or higher based on the intensity of the reflected wave from the object to be heated OB received by the antenna 7. When the control unit 8 determines that the temperature of the central portion of the object to be heated OB has reached 0° C. or higher, the control unit 8 ends the repeated control of the dielectric heating by the dielectric heater 2 and the microwave heating by the microwave heater 3.

[0032] Whether the temperature of the central portion of the heating object OB has reached 0°C or above is determined by determining whether the intensity of the reflected wave from the heating object OB, received by antenna 7, has reached or exceeded a threshold. The control unit 8 determines the threshold based on the image data acquired by the camera 5. The threshold is determined by comparing the image data acquired by the camera 5 with pre-stored sample image data of similar heating objects to the heating object OB. The threshold is then determined to a value corresponding to the number of repetitions required to thaw the central portion of the similar sample image data. This threshold is obtained through pre-tests conducted under the same conditions and stored in the memory of the control unit 8.

[0033] It should be noted that when measuring the surface temperature of the heating object OB, the surface includes the top and all sides. When the heating object OB has multiple sides, the temperature of only one side can be measured, or the temperatures of all the multiple sides can be measured. The number of measurement points for the surface temperature of the heating object OB depends on the size of the heating object OB (such as food). In this embodiment, it is assumed that an infrared camera is used to measure the temperature of each of multiple 1cm×1cm areas. When the heating object OB (such as food) is placed on a plate, the area of ​​the food is identified by using an RGB image, and the temperature of only the food area is estimated from the infrared image. When judging whether the surface temperature of the heating object OB has reached a predetermined temperature, the surface temperature of the heating object OB can be the overall temperature of the surface of the heating object OB, or the temperature of a partial area of ​​the surface of the heating object OB.

[0034] The reason for alternating dielectric heating and microwave heating multiple times is to prevent uneven thawing of the heated object. This is because using only microwaves M for thawing and heating to above 0°C could further heat the surface of the heated object OB, even though its center is still frozen but its surface is already thawed. This is to prevent further heating of the surface of the thawed food, which could damage its cells and deteriorate its texture and nutritional content.

[0035] When the intensity of the reflected wave received by antenna 7 reaches or exceeds a threshold, control unit 8 terminates the repetitive control of dielectric heating and microwave heating. Thus, in this embodiment, by receiving the reflected wave from the object OB via antenna 7, the thawing state of the central portion of the object OB can be estimated, thereby accurately determining the thawing state of the object OB. Therefore, it is possible to accurately determine that the central portion of the object OB has been thawed. As a result, uneven thawing of the object OB can be suppressed. Therefore, for example, when the object OB is food, a deterioration in the food's texture after thawing can be suppressed.

[0036] Figure 2 This is a flowchart for explaining the processing executed by the control unit of the heating device 10 according to the present embodiment.

[0037] In step S1, the control unit 8 determines the size and type of the heating object OB placed in the housing 1 based on the RGB image data acquired by the camera 5. The control unit 8 compares the RGB image data with sample image data stored in the control unit 8 memory and determines the size and type corresponding to the sample image data that most closely resembles the RGB image data as the size and type of the heating object OB. Furthermore, the control unit 8 estimates the surface temperature of the heating object OB based on the infrared image data of the heating object OB acquired by the non-contact temperature sensor 4. The control unit 8 compares the infrared image data with the sample image data stored in the control unit 8 memory and determines the temperature value corresponding to the sample image data that most closely resembles the infrared image data as the surface temperature of the heating object OB.

[0038] In step S2, it is determined whether the defrost function has been selected by the user operating the operating section of the operating panel 6. If it is determined in step S2 that the defrost function has been selected by the user operating the operating section of the operating panel 6, the control unit 8 causes the heating unit 23 to alternately repeat dielectric heating (40 MHz) and microwave heating (2.45 GHz) a predetermined number of times. To this end, in step S3, the control unit 8 compares the RGB image data acquired by the camera 5 with the sample image data and determines a threshold value for determining the number of times the alternating dielectric heating and microwave heating are repeated. The control unit 8 selects a threshold value corresponding to the size and type of the heating object OB determined in step S1 from among multiple threshold value candidates stored in the memory.

[0039] In this embodiment, the control unit 8 controls the heating unit 23 to repeat dielectric heating using the alternating electric field E and microwave heating using the microwaves M until the intensity of the reflected wave from the heating object OB, as detected by the antenna 7, exceeds a threshold. In this embodiment, the number of times dielectric heating and microwave heating are alternately repeated is not a fixed number, but rather the number of times the intensity of the reflected wave received by the antenna 7 exceeds a threshold value determined based on the RGB image data. Therefore, the number of times dielectric heating and microwave heating are alternately repeated varies depending on the size and type of the heating object OB for which the camera 5 captures image data.

[0040] If, in step S2, the user determines that the defrost function has not been selected by operating the operating portion of the operation panel 6, the control unit 8 then determines in step S11 whether the heating object OB is being heated to a surface temperature of 0°C or above. The control unit 8 makes this determination based on whether it has received a command signal, which is a signal instructing the user to heat the object OB to a temperature of 0°C or above by operating the operating portion of the operation panel 6. Subsequent processing will be described later.

[0041] In step S4 , the control unit 8 causes the dielectric heater 2 to perform dielectric heating on the heating object OB using the 40 MHz frequency alternating electric field E. In step S5 , the control unit 8 determines whether the surface temperature of the heating object OB measured by the non-contact temperature sensor 4 is 0° C. or higher.

[0042] If, in step S5, the surface temperature of the object OB is determined not to have reached 0°C or above, the control unit 8 repeats the processes of steps S4 and S5. On the other hand, if, in step S5, the surface temperature of the object OB is determined to have reached 0°C or above, the control unit 8 causes the dielectric heater 2 to terminate dielectric heating of the object OB using the 40 MHz frequency alternating electric field E. This is because if dielectric heating of the object OB continues while the surface temperature of the object OB is at least 0°C, the center of the object OB will remain frozen, while the surface of the object OB will reach an excessively high temperature.

[0043] Therefore, in step S7, the control unit 8 causes the microwave heater 3 to perform microwave heating of the heating object OB using 2.45 GHz microwaves. In step S8, the control unit 8 determines whether the surface temperature of the heating object OB measured by the non-contact temperature sensor 4 is 5°C or higher. If, in step S8, it is determined that the surface temperature of the heating object OB is not 5°C or higher, the control unit 8 determines that microwave heating of the surface layer of the heating object OB can continue, and repeats the processes of steps S7 and S8.

[0044] On the other hand, in step S8, it may be determined that the surface temperature of the object OB has reached 5°C or higher. In this case, in step S9, the control unit 8 determines that dielectric heating of the surface of the object OB should no longer be performed to prevent uneven thawing of the object OB, and causes the microwave heater 3 to stop microwave heating of the object OB. Furthermore, in step S9, the control unit 8 measures the intensity of the reflected wave from the surface of the object OB received by the antenna 7.

[0045] In step S10, the control unit 8 determines whether the intensity of the reflected wave from the heating object OB, received by the antenna 7, reaches the threshold value determined in step S3. If, in step S10, the intensity of the reflected wave from the heating object OB does not reach the threshold value determined in step S3, the control unit 8 deems that the center portion of the heating object OB has not yet thawed and repeats the operations from steps S4 to S10.

[0046] On the other hand, in step S10, if the reflected wave intensity of the heating object OB reaches the threshold value determined in step S3, the control unit 8 deems the central portion of the heating object OB to have thawed and terminates the repeated heating control of the heating object OB using the alternating electric field E and microwaves M. Thereafter, in step S11, the control unit 8 determines whether to heat the heating object OB to a temperature of 0°C or above. If, in step S11, it is determined that heating the heating object OB to a temperature of 0°C or above is not necessary, the control unit 8 terminates all processing.

[0047] On the other hand, if it is determined in step S11 that the surface of the heating object OB is to be heated to 0°C or above, the control unit 8 starts microwave heating of the heating object OB using microwaves M having a frequency of 2.45 GHz in step S12. Thereafter, after a predetermined time has elapsed, the control unit 8 terminates microwave heating of the heating object OB using microwaves having a frequency of 2.45 GHz in step S13.

[0048] Next, the method for creating learning data by machine learning in step S3 of this embodiment will be described. This method includes the following steps (1) to (6).

[0049] Step (1): Measure the dimensions of a rectangular heating object OB (e.g., beef slices or other food). During this measurement, camera 5 (RGB camera) within heating apparatus 10 acquires RGB image data, and the dimensions of the three sides of the rectangular heating object OB are determined based on the acquired RGB image data. Alternatively, a ruler can be used to measure the dimensions of the three sides of the rectangular heating object OB.

[0050] Step (2): Dielectric heating is performed by applying an alternating electric field E with a frequency of 40 MHz to the heating object OB using the dielectric heater 2. In this state, the time required for the temperature of the top and side surfaces of the heating object OB to reach 0°C or above is measured. Furthermore, when the temperature of the top and side surfaces of the heating object OB reaches 0°C or above, the temperature of the center of the heating object OB is measured by freezing the heating object OB to -20°C and inserting a thermometer into the center of the heating object OB. The temperature of the top and side surfaces of the heating object OB can be measured using the non-contact temperature sensor 4 or by measuring the temperature after freezing to -20°C using a thermometer. At this time, the room temperature can also be measured.

[0051] Step (3): Immediately after the dielectric heater 2 ceases dielectric heating by applying the 40 MHz alternating electric field E, the microwave heater 3 begins microwave heating of the object OB using microwaves M having a frequency of 2.45 GHz. This microwave heating continues until the top and side surfaces of the object OB reach a temperature of 5°C or higher. The time required for the top and side surfaces of the rectangular object OB to reach a temperature of 5°C or higher is recorded, as is the temperature of the center of the object OB at the time of reaching these temperatures. The room temperature may also be recorded at this time.

[0052] Step (4): When the temperature of the top and side surfaces of the rectangular object OB reaches 5°C or higher, the intensity of the reflected wave of the microwave M having a frequency of 2.45 GHz from the object OB is acquired using antenna 7. It should be noted that as the temperature of the center of the object OB approaches 0°C from a negative temperature, the intensity of the reflected wave of the microwave M increases. Therefore, when the reflected wave intensity reaches or exceeds a threshold value, it can be inferred that the center of the object OB has thawed.

[0053] Step (5): When the temperature of the top and side surfaces of the rectangular parallelepiped object OB reaches 5°C or higher, microwave heating of the object OB using the microwaves M at a frequency of 2.45 GHz is stopped. Dielectric heating of the object OB using the alternating electric field E at a frequency of 40 MHz is then resumed until the temperature of the top and side surfaces of the object OB again reaches 0°C or higher. This is because heat from the surface of the object OB is transferred to the center, causing the surface temperature of the object OB to drop below 0°C.

[0054] The time required for the top and side surfaces of the heated object OB to reach a temperature of 5°C or higher, and the temperature of the center of the heated object OB when the temperature is reached are recorded. The room temperature can also be measured at this time.

[0055] Step (6): Repeat the above steps (3) to (5) until the temperature of the center of the heating object OB reaches 0°C.

[0056] The data obtained from the experiments (1) to (6) above include: the temperature of the center of the heating object OB, the room temperature, and the reflected wave intensity when the temperature of the top and side surfaces of the heating object OB reaches 5°C or above, depending on the size and type of food, when the dielectric heating and microwave heating are repeated for different numbers of times.

[0057] Figure 3 Graph 10 is a graph showing the relationship between the temperatures of the surface portion and the center portion of the heating object OB and the heating time when the heating device 10 of the present embodiment heats the heating object OB.

[0058] from Figure 3It can be seen that when the object OB is heated alternately by dielectric heating (using the alternating electric field E) and microwave heating (using the microwaves M), the heating time required to thaw the central portion of the object OB is shortened. This will be described in detail below.

[0059] During the thawing process of the frozen heating object OB, microwaves M are irradiated onto the heating object OB in a conventional heating device 10 (e.g., a microwave oven). As a result, the surface temperature of the heating object OB reaches 0°C or above and the object becomes liquid. Figure 3 As can be seen from the long dashed line graph at 2.45 GHz, the surface temperature of the liquid heating object OB rises rapidly. Figure 3 As can be seen from the solid line graph at the center of 2.45 GHz, the center of the object OB is still frozen. Therefore, the object OB will experience a so-called uneven thawing phenomenon.

[0060] In addition, when only dielectric heating of the alternating electric field E is performed on the heating object OB, Figure 3 As can be seen from the dotted line graph of the surface portion at 40 MHz and the short-dashed line graph of the center portion at 40 MHz, it takes a long time to thaw the surface portion and the center portion of the heating object OB.

[0061] On the other hand, in the heating device 10 of this embodiment, dielectric heating by the alternating electric field E and microwave heating by the microwaves M are performed alternately. Figure 3 The dotted line diagram of the alternating center and Figure 3 As can be seen from the two-dot chain line graph of the middle alternating surface layer portion, the central portion of the object to be heated OB can be thawed in a short time while suppressing the occurrence of uneven thawing.

[0062] It should be noted that while thermopiles or thermal imaging devices such as the non-contact temperature sensor 4 can measure the surface temperature of the object OB, they cannot estimate the temperature at the center of the object OB. Therefore, in this embodiment, an antenna 7 is used to receive waves reflected from the object OB. When the object OB is frozen, microwaves with a frequency of 2.45 GHz are easily absorbed by the object OB, resulting in a low energy level of the reflected waves received by the antenna 7.

[0063] On the other hand, as the thawing process progresses, when only the center of the object OB remains frozen, the amount of microwaves reflected by the object OB increases. Consequently, the energy of the reflected waves received by antenna 7 gradually increases. Therefore, by measuring the energy of the reflected waves from the object OB, the degree of thawing at the center of the object OB can be estimated.

[0064] However, the reflected wave energy received by the antenna 7 varies depending on the size and type of the heating object OB. Therefore, even if the degree of thawing at the center of the heating object OB is the same, the reflected wave energy will vary depending on the size and type of the heating object OB.

[0065] Therefore, the size and type of the object to be heated OB are determined based on the image data acquired by the camera 5. Thus, the threshold value of the reflected wave energy during thawing of the central portion of the object to be heated OB is predetermined based on the combination of the size and type of the object to be heated OB. As a result, the central portion of the object to be heated OB can be thawed in an optimal state while suppressing overheating or incomplete thawing (i.e., uneven thawing).

[0066] For objects of varying sizes and types, the threshold energy of reflected waves reflected from the object OB during central thawing is determined using machine learning. Information input into the machine learning model includes, for example, the size, type, and surface temperature of the object OB before thawing begins.

[0067] The following is a detailed explanation of the method for determining the above thresholds. It should be noted that the values ​​in brackets after the following steps are Figure 3 The value of the horizontal axis of the chart is in seconds. Figure 3 The vertical axis represents the temperature value.

[0068] Step 0 (at the manufacturing stage of the heating device 10): Based on the image data obtained by the camera 5, for heating objects OB of different sizes and types, the reflected wave energy emitted by the heating object OB when the center of the heating object OB is thawed is estimated, and the threshold value for the antenna 7 to receive the reflected wave is determined.

[0069] Step 1 (0-70): Dielectric heating is performed by irradiating the heating object OB with an alternating electric field E having a frequency of 40 MHz until the surface temperature of the heating object OB reaches 0°C or above. It should be noted that when the surface temperature of the heating object OB is below 0°C, the 40 MHz alternating electric field E heats the surface of the heating object OB faster than the 2.45 GHz microwave M.

[0070] Step 2 (70-80): The object OB is heated using 2.45 GHz microwaves M until its surface temperature reaches 5°C or higher. Furthermore, when the surface temperature of the object OB reaches 0°C or higher, the 2.45 GHz microwaves M heat the object OB faster than the 40 MHz alternating electric field E.

[0071] Step 3 (80-100): The surface portion of the heating object OB, which has a temperature of 5°C or higher, is cooled to a temperature below 0°C due to heat transfer to the center portion, which has a temperature below 0°C.

[0072] Step 4 (80-130): The heating object OB is heated using a 40 MHz alternating electric field E until the surface temperature of the heating object OB reaches 0°C or above again.

[0073] Step 5 (130-220): Repeat the above steps 1 to 4 until the reflected wave energy of the heating object OB reaches or exceeds the threshold.

[0074] Step 6 (220): When the reflected wave energy of the heating object OB exceeds the threshold, the heating unit 23 stops the alternating operation of dielectric heating by the alternating electric field E and microwave heating by the microwaves M. That is, thawing of the heating object OB is completed.

[0075] (Second embodiment) use Figure 4 and Figure 5 The heating device 10 of the second embodiment will be described. The same parts as those of the heating device 10 of the first embodiment will not be described again. The heating device 10 of this embodiment differs from the heating device 10 of the first embodiment in the following respects.

[0076] Figure 4 A schematic structure of the heating device 10 according to this embodiment is shown.

[0077] like Figure 4 As shown, the heating device 10 of this embodiment is different from the heating device 10 of the first embodiment in that the antenna 7 is not provided in this embodiment.

[0078] In this embodiment, the control unit 8 determines the number of repetitions of dielectric heating and microwave heating based on image data captured by the camera 5, rather than the reflected waves received by the antenna 7. Specifically, the control unit 8 compares the RGB image data captured by the camera 5 with a large amount of sample image data previously acquired through machine learning. Based on the comparison results, the control unit 8 determines the number of repetitions of dielectric heating and microwave heating. During this comparison, the control unit ultimately adopts the number of repetitions corresponding to sample image data of a similar size and type to the heated object OB.

[0079] This number of repetitions is determined based on the results of a heating experiment on the object OB, specifically, the number of repetitions of dielectric heating and microwave heating required to thaw the central portion of the object OB. Once the control unit 8 determines that the dielectric heating and microwave heating have been repeated for the number of repetitions determined by the comparison, the control unit 8 terminates the repetitive control of the dielectric heating and microwave heating.

[0080] According to the heating device 10 of this embodiment, since the antenna 7 is not required, the number of parts of the heating device 10 can be reduced, and the structure of the heating device 10 can be simplified.

[0081] Figure 5 This is a flowchart for explaining the processing executed by the control unit 8 of the heating device 10 according to the second embodiment.

[0082] In step S3A of this embodiment, the control unit 8 determines the number of repetitions of dielectric heating and microwave heating based on the RGB image data captured by the camera 5, which differs from the process performed by the control unit 8 (step S3) in the first embodiment. Furthermore, in step 9A, this embodiment terminates microwave heating using the 2.45 GHz microwaves M without measuring the reflected wave intensity, which differs from the process performed by the control unit 8 (step 9) in the first embodiment. Furthermore, in step S10A of this embodiment, the control unit 8 repeats the dielectric heating and microwave heating operations for the number of times determined in step S3A, which differs from the process performed by the control unit 8 (step S10) in the first embodiment.

[0083] The processing of the control unit 8 in the present embodiment other than the above-mentioned steps is the same as the processing of each step in the first embodiment.

[0084] (Third embodiment) use Figure 6 and Figure 7 The heating device 10 of the third embodiment will be described. The same parts as those of the heating device 10 of the first embodiment will not be described again. The heating device 10 of this embodiment differs from the heating device 10 of the first embodiment in the following respects.

[0085] Figure 6 A schematic structure of the heating device 10 according to this embodiment is shown.

[0086] The heating device 10 of this embodiment is a commercial heating device. In the heating device 10, a two-dimensional code attached to a packaging bag of a heating object OB of a predetermined size, shape and type, such as food, is read from the RGB image data obtained by the camera 5. Thus, the number of repetitions of dielectric heating and microwave heating for the heating object OB, as well as the first heating time of dielectric heating and the second heating time of microwave heating are determined. It should be noted that the two-dimensional code can be, for example, a QR code (registered trademark), which is an example of an identifier read by the camera 5. A one-dimensional code can also be used as long as it is an identifier that can be obtained through image data. That is, the identifier can be any identifier such as a barcode (registered trademark) that can be used to determine the predetermined number of repetitions of dielectric heating and microwave heating of the heating object OB, as well as the first heating time of dielectric heating and the second heating time of microwave heating.

[0087] like Figure 6 As shown, the difference between the heating device 10 of the present embodiment and the heating device 10 of the first embodiment is that the present embodiment does not include the non-contact temperature sensor 4 and the antenna 7. Therefore, the number of parts of the heating device 10 can be greatly reduced, making the structure of the heating device 10 extremely simple.

[0088] In this embodiment, similar to the second embodiment, the control unit 8 determines the number of repetitions of dielectric heating and microwave heating based on the image data acquired by the camera 5. Specifically, the control unit 8 determines the number of repetitions of dielectric heating and microwave heating for the heating object OB by reading the QR code in the image data acquired by the camera 5.

[0089] After dielectric heating and microwave heating are repeated for the number of times specified by the QR code, control unit 8 terminates the repeated control of dielectric heating and microwave heating. This number of times is predetermined by repeated heating experiments involving dielectric heating and microwave heating of a heating object OB similar to the heating object OB within the packaging bag. The determined number of times dielectric heating and microwave heating of the heating object is repeated can be determined using the RGB image data of the QR code.

[0090] Specifically, in this embodiment, unlike the first and second embodiments, the control unit 8 determines a first heating time for dielectric heating and a second heating time for microwave heating based on a QR code included in the image data captured by the camera 5. Furthermore, in this embodiment, the control unit 8 terminates dielectric heating when the first heating time determined by the QR code has elapsed since the start of dielectric heating. Furthermore, in this embodiment, the control unit 8 terminates microwave heating when the second heating time determined by the QR code has elapsed since the start of microwave heating.

[0091] Figure 7This is a flowchart for explaining the processing executed by the control unit 8 of the heating device 10 according to the present embodiment.

[0092] In this embodiment, in step S2B, the control unit 8 determines whether the packaging bag of the heating object OB or the like has any prior information (identification) such as a QR code affixed to it in the RGB image data acquired by the camera 5. If, in step S2B, the packaging bag of the heating object OB or the like does not have any identification such as a QR code affixed to it, the control unit 8 proceeds to step S11.

[0093] On the other hand, if it is determined in step S2B that a QR code or other identifier is attached to the packaging bag or the like of the heating object OB, the control unit 8 determines the number of repetitions of alternating heating, the first heating time, and the second heating time based on the identifier in step S3B. Furthermore, in step 9B, microwave heating using the 2.45 GHz microwaves M is terminated without measuring the reflected wave intensity of the heating object OB.

[0094] Furthermore, in step S5B, the control unit 8 determines whether the dielectric heating at 40 MHz has been performed for the first heating time specified by the QR code. If it is determined that the dielectric heating has been performed for the first heating time, the control unit 8 ends the dielectric heating at 40 MHz in step S6.

[0095] Furthermore, in step S8B, control unit 8 determines whether the 2.45 GHz microwave heating has been performed for the second heating time specified by the QR code. If it is determined that the microwave heating has been performed for the second heating time, control unit 8 terminates the 2.45 GHz microwave heating in step S9B. It should be noted that the intensity of the reflected wave from the heating object OB is not measured in step S9B.

[0096] Furthermore, in step S10B of the present embodiment, the control unit 8 determines whether the alternating operation of dielectric heating and microwave heating has been completed the predetermined number of times determined in step S3B. If it is determined that the alternating operation of dielectric heating and microwave heating has been completed the predetermined number of times determined in step S3B, the control unit 8 determines whether to heat the object OB to a temperature of 0° C. or above in step S11.

[0097] The processing of the control unit 8 in the present embodiment other than the above-mentioned steps is the same as the processing of each step in the first embodiment.

Claims

1. A heating device, characterized in that: have: a housing for accommodating a heating object; a heating unit that heats the heating object; a control unit that controls the heating unit; The control unit first performs dielectric heating on the heating object using an alternating electric field of a first frequency, and then performs microwave heating on the heating object using microwaves of a second frequency higher than the first frequency.

2. The heating device according to claim 1, characterized in that The control unit controls the heating unit so that the dielectric heating and the microwave heating are alternately and repeatedly performed.

3. The heating device according to claim 2, characterized in that Also features: a camera, disposed in the housing and configured to acquire image data of the heating object; an antenna for receiving a reflected wave reflected from the heating object; The control unit determines a threshold value based on the image data acquired by the camera, and ends the repetitive control of the dielectric heating and the microwave heating when the intensity of the reflected wave received by the antenna reaches or exceeds the threshold value.

4. The heating device according to claim 2, characterized in that A camera is also provided in the housing for acquiring image data of the heating object. The control unit determines a number of repetitions of the dielectric heating and the microwave heating based on the image data acquired by the camera, and ends the repetitive control of the dielectric heating and the microwave heating when the dielectric heating and the microwave heating reach the repetition number.

5. The heating device according to claim 1, characterized in that A camera is also provided in the housing for acquiring image data of the heating object. The control unit determines a first heating time for the dielectric heating and a second heating time for the microwave heating based on the image data acquired by the camera, and ends the dielectric heating when the first heating time has passed after the start of the dielectric heating; and ends the microwave heating when the second heating time has passed after the start of the microwave heating.

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