Heater

Abstract

To provide a heater capable of performing a heating process as appropriately as possible according to a type of an object to be heated.SOLUTION: A heater 1 includes: a housing 10; a mounting table 71 which is provided in the housing and on which an object to be heated HO is mounted; an antenna 40 which radiates a high frequency wave for heating the object to be heated into the housing; a driving part 80 which moves at least one of the mounting table and the antenna in a vertical direction; and a control part 100 which derives a reflection loss amount of the high frequency wave. The control part changes a distance between the antenna and the object to be heated by controlling the driving part in accordance with the reflection loss amount.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a heater. [Background technology]

[0002] In the past, a microwave heating device has been proposed that includes: a heating chamber; a mounting table that is placed within the heating chamber and on which an object to be heated is placed; a dielectric plate-shaped member that is placed below the mounting table within the heating chamber; an antenna that is placed below the plate-shaped member within the heating chamber and radiates microwaves; a first moving mechanism that moves the plate-shaped member up and down; an intensity measuring unit that measures the intensity of the reflected microwaves via the antenna; and a control unit that controls the movement of the first moving mechanism based on the intensity measured by the intensity measuring unit and moves the plate-shaped member to a first position where the intensity is equal to or less than a predetermined intensity (see, for example, JP 2018-152245 A). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-152245 Summary of the Invention [Problem to be solved by the invention]

[0004] In the microwave heating device described above, the object to be heated in the heating chamber can be heated by microwaves radiated into the heating chamber. However, when heating an object to be heated, such as a frozen whole cake, which should be heated evenly throughout, the center of the object to be heated may be heated intensively, and there is a risk that the microwave heating device will not be able to perform an appropriate heating process depending on the type of object to be heated.

[0005] An object of the present invention is to provide a heater that can perform heat treatment as appropriately as possible according to the type of object to be heated. [Means for solving the problem]

[0006] A heater according to a first aspect of the present invention includes a housing, a mounting base, an antenna, a drive unit, and a control unit. The mounting base is provided within the housing, and an object to be heated is placed on the mounting base. The antenna radiates high-frequency waves into the housing for heating the object to be heated. The drive unit moves at least one of the mounting base and the antenna in an up-and-down direction. The control unit derives the amount of return loss of the high-frequency waves. The control unit also controls the drive unit to change the distance between the antenna and the object to be heated according to the amount of return loss. The object to be heated includes, for example, an object to be thawed, such as a frozen whole cake or frozen meat, or an object to be cooked, such as vegetables, meat, or fish.

[0007] After extensive research, the inventors discovered that not only does the amount of high-frequency return loss change depending on the state of the object (e.g., from solid to liquid), but also the distance between the antenna and the object changes. For example, the return loss of a frozen whole cake increases as it changes from solid to liquid, and changing the distance between the antenna and the object creates a mountain-shaped curve of return loss versus distance. Furthermore, the inventors discovered that when the return loss is large, the center of the object is heated intensively, while when the return loss is small, the entire object is heated uniformly. With the above configuration, for example, when heating an object that requires uniform heating throughout, such as a frozen whole cake, even if the return loss increases as the object changes from solid to liquid, potentially resulting in concentrated heating of the center, the drive unit can be controlled to change the distance between the antenna and the object to reduce the return loss and heat the entire object uniformly. This heating device therefore allows for optimal heating according to the type of object.

[0008] A heater according to a second aspect of the present invention is the heater according to the first aspect, wherein the control unit controls the drive unit so that the peak of the resonant frequency at which the heated object resonates moves away from the high-frequency frequency or moves closer to the high-frequency frequency.

[0009] According to the above configuration, by controlling the drive unit so that the peak of the resonant frequency at which the object to be heated resonates moves away from (shifts) the high-frequency frequency, the force that vibrates the object to be heated can be dispersed. Therefore, this heater can uniformly heat the entire object to be heated. Furthermore, according to the above configuration, by controlling the drive unit so that the peak of the resonant frequency approaches (synchronizes) the high-frequency frequency, large vibration energy is applied to the center of the object to be heated, and large force can be generated at the center of the object to be heated. Therefore, this heater can heat the center of the object to be heated in a concentrated manner.

[0010] A heater according to a third aspect of the present invention is the heater according to the first or second aspect, wherein the control unit derives an average value of the amount of return loss per fixed time period, controls the drive unit so that the average value falls within a set range, and when a cumulative value of the average value reaches a value set for each heated object, causes the antenna to stop emitting high frequency waves.

[0011] According to the above configuration, the radiation of high frequency waves can be automatically stopped when the heating that is deemed necessary is completed.

[0012] A heater according to a fourth aspect of the present invention is the heater according to the first aspect, further comprising a heater and a first temperature measuring unit. The heater is disposed above the object to be heated. The first temperature measuring unit measures the temperature of the object to be heated. The control unit controls the drive unit based on the temperature measured by the first temperature measuring unit.

[0013] According to the above configuration, it is possible to assist the heating by high frequency waves, for example by actively heating the surface of the object to be heated by the heater.

[0014] A heater according to a fifth aspect of the present invention is the heater according to the first aspect, further comprising a dummy substrate and a second temperature measuring unit. The dummy substrate converts reflected high-frequency waves into heat. The second temperature measuring unit measures the temperature of the dummy substrate. The control unit detects an abnormality based on the relationship between the amount of return loss and the temperature measured by the second temperature measuring unit.

[0015] As the return loss decreases, the reflected wave energy increases, which places an excessive load on the dummy board that converts the reflected wave into heat. With the above configuration, it is possible to detect abnormalities such as cable breakage that accompany such loads. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 2 is a right side cross-sectional view of the heater according to the embodiment of the present invention. [Figure 2] 1 is a block diagram showing a configuration of a heater according to an embodiment of the present invention. [Figure 3] 10 is a flowchart showing a process flow when uniform heating is performed in a heater according to an embodiment of the present invention. [Figure 4] 10 is a flowchart showing a process flow when local heating is performed in a heater according to an embodiment of the present invention. [Figure 5] 1 is a conceptual diagram showing the distance between the antenna and the object to be heated and the amount of high frequency reflection loss corresponding to the heating state of the object in a heater according to an embodiment of the present invention. FIG. [Figure 6] FIG. 10 is a diagram showing the results of verification example 1. [Figure 7] FIG. 10 is a diagram showing the results of verification example 2. [Figure 8] FIG. 10 is a diagram showing the results of verification example 3. [Figure 9] FIG. 10 is a diagram showing the results of verification example 4. DETAILED DESCRIPTION OF THE INVENTION

[0017] <Configuration of heater according to an embodiment of the present invention> A heater 1 according to an embodiment of the present invention is intended to heat an object to be heated HO (for example, an object to be thawed such as a frozen whole cake or frozen meat, or an object to be cooked such as vegetables, meat, or fish), and as shown in Figures 1 and 2, is mainly composed of a housing 10, an input / output device 20, a high-frequency circuit 30, an antenna 40, a heater 50, a temperature sensor 60, a vertical movement unit 70, a drive unit 80, a position sensor 90, and a control unit 100. These components will be described in detail below.

[0018] (1) Housing As shown in FIGS. 1 and 2, the housing 10 accommodates the object to be heated HO, the antenna 40, the heater 50, a mounting table 71 for the vertical movement unit 70, etc., and is mainly composed of an upper container 11 and a lower container 12. The housing 10 is made of a conductor (e.g., stainless steel, aluminum, copper, etc.) and has the function of reflecting high-frequency waves radiated from the antenna 40 to the inside. As shown in FIGS. 1 and 2, the upper container 11 is disposed above the lower container 12 and has a cylindrical shape with a lid. The antenna 40 and the heater 50 are disposed inside the upper container 11, as shown in FIGS. 1 and 2. The lower container 12 is disposed below the upper container 11 and has a cylindrical shape with a bottom, as shown in FIGS. 1 and 2. In addition, a through hole is formed in the bottom of the lower container 12 to allow the rod portion 72 of the vertical movement portion 70 to pass through so that the rod portion 72 of the vertical movement portion 70 can move freely in the vertical direction.

[0019] (2) Input / output devices The input / output device 20 is a display device such as a display having a touch panel function. The input / output device 20 transmits information input by a user of the heater 1 (for example, information indicating the type of the object to be heated HO) to the microcomputer of the control unit 100, and outputs text, images, videos, sounds, etc. based on commands from the microcomputer of the control unit 100.

[0020] (3) High-frequency circuit As shown in FIG. 2, the high-frequency circuit 30 is mainly composed of an amplifier 31, a monitor circuit 32, a dummy substrate 33, and the like. The amplifier 31 amplifies the high-frequency wave output from an oscillator circuit (not shown). The output of the amplifier 31 is supplied to the antenna 40. The monitor circuit 32 measures the incident and reflected high-frequency waves radiated from the antenna 40. The reflected waves are electromagnetic waves received by the antenna 40 without being absorbed by the object to be heated HO, etc. The monitor circuit 32 also has a temperature sensor and measures the temperature of the dummy substrate 33, etc. The monitor circuit 32 then transmits this measurement result information, etc. to the microcomputer of the control unit 100. The dummy substrate 33 has a heat exchanger unit, etc., and converts the reflected high-frequency waves radiated from the antenna 40 into heat.

[0021] (4) Antenna 1 and 2, the antenna 40 is a loop antenna or the like, and is disposed inside the upper container 11 of the housing 10 so as to be located above the object to be heated HO. The antenna 40 radiates the high frequency power supplied from the high frequency circuit 30 into the housing 10 as electromagnetic waves for heating the object to be heated HO. The frequency of the high frequency power is not particularly limited, but is, for example, 50 Hz or 60 Hz.

[0022] (5) Heater The heater 50 is, for example, an infrared heater that emits infrared rays, and is arranged inside the upper container 11 of the housing 10 so as to be located above the object to be heated HO, as shown in FIGS.

[0023] (6) Temperature sensor The temperature sensor 60 is a sensor such as an infrared temperature sensor that measures the temperature of the object to be heated HO inside the housing 10.

[0024] (7) Vertical movement part As shown in Figures 1 and 2, the vertical movement unit 70 is mainly composed of a mounting table 71, a rod portion 72, and the like. As shown in Figure 2, the mounting table 71 is disposed inside the housing 10, and the object to be heated HO is placed on the mounting table 71. Also, as shown in Figures 1 and 2, the rod portion 72 is attached to the bottom of the mounting table 71. Therefore, when the rod portion 72 is moved up and down by the drive unit 80, the mounting table 71 also moves up and down. As described above, the rod portion 72 passes through a through-hole in the bottom of the lower container 12 of the housing 10 so as to be freely movable up and down.

[0025] (8) Drive unit The driving unit 80 is composed of an electric motor that performs rotational motion, a conversion device that converts the rotational motion of the electric motor into reciprocating motion and moves the vertically moving unit 70 in the vertical direction, and the like.

[0026] (9) Position sensor The position sensor 90 detects the position of the vertical movement unit 70 within the housing 10 and transmits information relating to the position of the vertical movement unit 70 to the microcomputer of the control unit 100 .

[0027] (10) Control unit The control unit 100 includes electronic components such as a microcomputer, and is connected to the input / output device 20, the high-frequency circuit 30, the antenna 40, the heater 50, the temperature sensor 60, the drive unit 80, and the position sensor 90, as shown in FIG. 2, and controls these components. The microcomputer in the control unit 100 also derives the high-frequency return loss (hereinafter, sometimes abbreviated as "RL") based on measurement result information from the monitor circuit 32 of the high-frequency circuit 30. In an embodiment of the present invention, the high-frequency return loss is the ratio of the reflected wave to the incident high-frequency wave, expressed in decibels, and is calculated using the formula [10log(transmitted power amount / received power amount)]. The high-frequency return loss varies depending on changes in the state of the object HO (e.g., a change from solid to liquid phase) and changes in the distance between the antenna 40 and the object HO.

[0028] The microcomputer of the control unit 100 is also equipped with a memory. The memory stores various programs, control tables, etc. In the control table, information indicating the type of the object HO to be heated is associated with heating type information (information indicating uniform heating that uniformly heats the entire object HO, information indicating local heating that concentrates heating on the center of the object HO, etc.), information on the required amount of heating that has been set, etc.

[0029] <Example of control by the control unit in the heater according to the embodiment of the present invention> Here, an example of control by the control unit 100 in the heater 1 according to an embodiment of the present invention will be described. First, the microcomputer of the control unit 100 compares information indicating the type of object to be heated HO input by the user via the input / output device 20 with a control table, and acquires heating type information, required heating amount information, etc. Then, the microcomputer of the control unit 100 executes process SA when it acquires information indicating that uniform heating is to be performed from the heating type information, and executes process SB when it acquires information indicating that localized heating is to be performed from the heating type information. Process SA will be described below with reference to FIG. 3, and then process SB will be described with reference to FIG. 4.

[0030] <Processing SA> (Step Sa1) The microcomputer of the control unit 100 controls the high frequency circuit 30 to cause the antenna 40 to radiate high frequency waves into the housing 10 .

[0031] (Step Sa3) The microcomputer of the control unit 100 receives measurement result information of the reflected high frequency wave radiated from the antenna 40 from the monitor circuit 32 of the high frequency circuit 30 .

[0032] (Step Sa5) The microcomputer of the control unit 100 derives the amount of high frequency return loss.

[0033] (Step Sa6) The microcomputer of the control unit 100 determines whether a certain period of time has elapsed.

[0034] -If step Sa6 is YES- If the microcomputer of the control unit 100 determines that the certain time has elapsed, the process of step Sa7 is executed.

[0035] -If step Sa6 is NO- If the microcomputer of the control unit 100 determines that the certain time has not elapsed, the process is repeated from step Sa3.

[0036] (Step Sa7) The microcomputer of the control unit 100 calculates the average value of the return loss amount for each fixed time period.

[0037] (Step Sa9) The microcomputer of the control unit 100 determines whether the derived average value of the return loss is within the range of X or more and Y or less. Here, X is, for example, 3, and Y is, for example, 6. If the average value of the return loss is less than 3, the heating efficiency for the object HO to be heated may be low, and if the average value of the return loss is more than 6, the heating for the object HO to be heated may be localized heating.

[0038] -If step Sa9 is YES- If the microcomputer of the control unit 100 determines that the calculated average value of the return loss amount is within the range of X or more and Y or less, the process of step Sa11 is executed.

[0039] -If step Sa9 is NO- If the microcomputer of the control unit 100 determines that the calculated average value of the return loss amount is not within the range of X or more and Y or less, the process of step Sa15 is executed.

[0040] (Step Sa11) The microcomputer of the control unit 100 determines whether the cumulative value of the calculated average values ​​of the return loss amounts is equal to or greater than Z. Here, Z is a value indicated by the required heating amount information in the control table.

[0041] -If step Sa11 is YES- If the microcomputer of the control unit 100 determines that the cumulative value of the calculated average values ​​of the return loss amounts is equal to or greater than Z, the process proceeds to step Sa13.

[0042] -If step Sa11 is NO- If the microcomputer of the control unit 100 determines that the cumulative value of the calculated average values ​​of the return loss amounts is not equal to or greater than Z, the process is repeated from step Sa3.

[0043] (Step Sa13) The microcomputer of the control unit 100 controls the high frequency circuit 30 to stop the radiation of high frequency waves from the antenna 40. Then, the process SA ends here.

[0044] (Step Sa15) The microcomputer of the control unit 100 controls the drive unit 80 to move the vertical movement unit 70 in the vertical direction, thereby changing the distance between the antenna 40 and the object to be heated HO.

[0045] Here, with reference to FIG. 6, the relationship between the distance between the antenna 40 and the object to be heated HO and the amount of return loss, which corresponds to the heating state of the object to be heated HO, will be described. In FIG. 6, the distances between the antenna 40 and the object to be heated HO are represented by D1 to D3, and the amount of return loss is represented by RL. Furthermore, D1>D2>D3, where D1 is long, D2 is an intermediate distance between D1 and D2, and D3 is short. When the distance is D1, the object to be heated HO is in a state of being uniformly heated. In this case, it can be seen that the peak of the resonant frequency at which the object to be heated HO resonates shifts to the right from the high-frequency frequency, and the amount of return loss is small. When the distance is D2, the object to be heated HO is in a state of being locally heated. In this case, it can be seen that the peak of the resonant frequency is synchronized with the high-frequency frequency, and the amount of return loss is large. When the distance is D3, the object to be heated HO is in a state of being uniformly heated. In this case, it can be seen that the peak of the resonant frequency shifts to the left from the high-frequency frequency, and the amount of return loss is small.

[0046] Taking these factors into consideration, step Sa15 will be described in more detail. First, if the average value in step Sa9 is less than X, the resonant frequency peak is moved closer to the high-frequency frequency to increase the heating efficiency of the object HO. That is, if the resonant frequency peak is significantly shifted to the right from the high-frequency frequency, the microcomputer of the control unit 100 controls the drive unit 80 to move the vertical movement unit 70 upward to shorten the distance between the antenna 40 and the object HO. If the resonant frequency peak is significantly shifted to the left from the high-frequency frequency, the microcomputer of the control unit 100 controls the drive unit 80 to move the vertical movement unit 70 downward to lengthen the distance between the antenna 40 and the object HO. On the other hand, if the average value in step Sa9 is greater than Y, the resonant frequency peak is moved away from the high-frequency frequency to prevent localized heating of the object HO. That is, when the resonant frequency peak is perfectly synchronized with the high frequency, the microcomputer of the control unit 100 controls the drive unit 80 to move the vertical movement unit 70 downward to increase the distance between the antenna 40 and the object to be heated HO, or to move the vertical movement unit 70 upward to decrease the distance between the antenna 40 and the object to be heated HO. Also, when the resonant frequency peak is slightly shifted to the right of the high frequency but is substantially synchronized with the high frequency, the microcomputer of the control unit 100 controls the drive unit 80 to move the vertical movement unit 70 downward to increase the distance between the antenna 40 and the object to be heated HO. In this case, the microcomputer of the control unit 100 may control the drive unit 80 to move the vertical movement unit 70 upward to decrease the distance between the antenna 40 and the object to be heated HO, so that although the resonant frequency peak temporarily approaches the high frequency, the resonant frequency peak exceeds the high frequency and then moves away from the high frequency. Furthermore, when the peak of the resonant frequency is slightly shifted to the left of the high frequency frequency but is nearly synchronized, the microcomputer of the control unit 100 controls the drive unit 80 to move the up / down moving unit 70 upward to shorten the distance between the antenna 40 and the object to be heated HO.In such a case, the peak of the resonant frequency will be temporarily brought closer to the high-frequency frequency, but the microcomputer of the control unit 100 may control the drive unit 80 to move the up-and-down moving unit 70 downward to increase the distance between the antenna 40 and the object to be heated HO so that the peak of the resonant frequency exceeds the high-frequency frequency and then moves away from the high-frequency frequency.

[0047] <Processing SB> (Step Sb1) The microcomputer of the control unit 100 controls the high frequency circuit 30 to cause the antenna 40 to radiate high frequency waves into the housing 10 .

[0048] (Step Sb3) The microcomputer of the control unit 100 receives measurement result information of the reflected high frequency wave radiated from the antenna 40 from the monitor circuit 32 of the high frequency circuit 30 .

[0049] (Step Sb5) The microcomputer of the control unit 100 derives the amount of high frequency return loss.

[0050] (Step Sb6) The microcomputer of the control unit 100 determines whether a certain period of time has elapsed.

[0051] -If step Sb6 is YES- If the microcomputer of the control unit 100 determines that the predetermined time has elapsed, the process proceeds to step Sb9.

[0052] -If step Sb6 is NO- If the microcomputer of the control unit 100 determines that the certain time has not elapsed, the process proceeds to step Sb7.

[0053] (Step Sb7) The microcomputer of the control unit 100 controls the drive unit 80 to slightly move the vertical movement unit 70 upward, thereby slightly shortening the distance between the antenna 40 and the object to be heated HO. Then, the microcomputer of the control unit 100 executes the process of step Sb3.

[0054] (Step Sb9) The microcomputer of the control unit 100 calculates the average value of the return loss amount for each fixed time period and the difference between the return loss amounts.

[0055] (Step Sb11) The microcomputer of the control unit 100 determines whether the average value of the derived return loss amounts exceeds Y and whether the average value of the differences between successive return loss amounts is within the range of P to Q. Here, Y is, for example, 6 as described above, P is, for example, −0.2, and Q is, for example, 0.2.

[0056] -If step Sb11 is YES- If the microcomputer of the control unit 100 determines that the derived average value of the return loss exceeds Y and the average value of the differences in the return loss falls within the range of P or more and Q or less, the process of step Sb13 is executed.

[0057] -If step Sb11 is NO- If the microcomputer of the control unit 100 determines that the derived average value of the return loss amounts is not greater than Y, or that the average value of the differences in the return loss amounts is not within the range of P or more and Q or less, the process of step Sb17 is executed.

[0058] (Step Sb13) The microcomputer of the control unit 100 determines whether the cumulative value of the derived average values ​​of the return loss amounts is equal to or greater than Z. Here, Z is the value indicated by the required heating amount information in the control table as described above.

[0059] -If step Sb13 is YES- If the microcomputer of the control unit 100 determines that the cumulative value of the calculated average values ​​of the return loss amounts is equal to or greater than Z, the process proceeds to step Sb15.

[0060] -If step Sb13 is NO- If the microcomputer of the control unit 100 determines that the cumulative value of the calculated average values ​​of the return loss amounts is not equal to or greater than Z, the process is repeated from step Sb3.

[0061] (Step Sb15) The microcomputer of the control unit 100 controls the high frequency circuit 30 to stop the radiation of high frequency waves from the antenna 40. Then, the process SB ends here.

[0062] (Step Sb17) The microcomputer of the control unit 100 controls the drive unit 80 to move the vertical movement unit 70 in the vertical direction, thereby changing the distance between the antenna 40 and the object to be heated HO. More specifically, if the peak of the resonant frequency is shifted to the right from the high-frequency frequency so that the peak of the resonant frequency approaches the high-frequency frequency, the microcomputer of the control unit 100 controls the drive unit 80 to move the vertical movement unit 70 upward to shorten the distance between the antenna 40 and the object to be heated HO, and if the peak of the resonant frequency is shifted to the left from the high-frequency frequency, the microcomputer of the control unit 100 controls the drive unit 80 to move the vertical movement unit 70 downward to lengthen the distance between the antenna 40 and the object to be heated HO.

[0063] The microcomputer of the control unit 100 may energize the heater 50 when, for example, the temperature measured by the temperature sensor 60 is below a predetermined temperature while executing processes SA and SB and between the processing of an arbitrary step and the processing of another arbitrary step. The microcomputer of the control unit 100 may energize the heater 50 when, for example, the temperature measured by the temperature sensor 60 is below a predetermined temperature while executing processes other than processes SA and SB. The microcomputer of the control unit 100 may not energize the heater 50 at all.

[0064] Furthermore, while executing processes SA and SB, the microcomputer of the control unit 100 receives measurement result information on the temperature of the dummy substrate 33 from the monitor circuit 32 of the high-frequency circuit 30. Note that, since the reflected wave energy increases as the amount of return loss decreases, an excessive load is placed on the dummy substrate 33 if the amount of return loss is too small. The microcomputer of the control unit 100 then detects an abnormality when the temperature of the dummy substrate 33 exceeds a threshold value. Then, for example, the microcomputer of the control unit 100 causes the input / output device 20 to output a sound or the like to notify the user that an abnormality has been detected.

[0065] <Features of the heater according to the embodiment of the present invention> (1) In the heater 1 according to the embodiment of the present invention, the microcomputer of the control unit 100 controls the drive unit 80 to change the distance between the antenna 40 and the object to be heated HO, thereby moving the peak of the resonant frequency at which the object to be heated HO resonates away from the high-frequency frequency from the antenna 40. This allows the heater 1 to distribute the force that vibrates the object to be heated HO. This allows the heater 1 to uniformly heat the object to be heated HO. Furthermore, in the heater 1, the microcomputer of the control unit 100 controls the drive unit 80 to change the distance between the antenna 40 and the object to be heated HO, thereby moving the peak of the resonant frequency closer to the high-frequency frequency. This allows the heater 1 to apply large vibration energy to the center of the object to be heated HO, thereby generating large force at the center of the object to be heated HO. This allows the heater 1 to locally heat the object to be heated HO.

[0066] (2) In the heater 1 according to the embodiment of the present invention, when the cumulative value of the derived average values ​​of the return loss amounts becomes equal to or greater than the value indicated in the required heating amount information in the control table, the microcomputer of the control unit 100 controls the high-frequency circuit 30 to stop the radiation of high-frequency waves from the antenna 40. Therefore, in this heater 1, once the heating that is deemed necessary has been completed, the radiation of high-frequency waves from the antenna 40 can be automatically stopped.

[0067] (3) In the heater 1 according to the embodiment of the present invention, the heater 50 is provided inside the upper container 11 of the housing 10. Therefore, in this heater 1, when the microcomputer of the control unit 100 energizes the heater 50, it is possible to actively heat the surface of the object to be heated HO, and to assist heating by the high frequency waves radiated from the antenna 40.

[0068] (4) In the heater 1 according to the embodiment of the present invention, the microcomputer of the control unit 100 receives measurement result information of the temperature of the dummy substrate 33 from the monitor circuit 32 of the high-frequency circuit 30 while executing processes SA and SB, and detects an abnormality when the temperature of the dummy substrate 33 exceeds a threshold value. Therefore, in this heater 1, it is possible to detect abnormalities such as cable breakage caused by the load on the dummy substrate 33.

[0069] <Modification> (A) In the heater 1 according to the previous embodiment, the heater 50 is provided inside the upper container 11 of the housing 10. However, the heater 50 may be omitted.

[0070] (B) Although not mentioned in the heater 1 according to the previous embodiment, the mounting table 71 of the vertical movement unit 70 may be configured to be rotatable about the rod portion 72. Then, in a case where the peak of the resonant frequency at which the object to be heated HO resonates can be moved closer to or further away from the high-frequency frequency by rotating the mounting table 71 using the drive unit (for example, in a case where the antenna 40 is provided close to the inner surface of the side wall portion of the upper container 11 of the casing 10, the object to be heated HO is placed at a position shifted from the center of the mounting table 71, and the distance between the antenna 40 and the object to be heated HO is changed by rotating the mounting table 71), the microcomputer of the control unit 100 may cause the drive unit to perform at least one of position adjustment by vertical movement of the mounting table 71 of the vertical movement unit 70 and position adjustment by rotation of the mounting table 71 in step Sa15 of process SA and steps Sb7 and Sb17 of process SB.

[0071] (C) Although not mentioned in the heater 1 according to the previous embodiment, the number of antennas 40 is not particularly limited, and may be one or more.

[0072] (D) In the heater 1 according to the previous embodiment, the distance between the antenna 40 and the object to be heated HO was changed by vertical movement of the vertical moving unit 70. However, the antenna 40 may be configured to be movable in the vertical direction by a drive unit, and the distance between the antenna 40 and the object to be heated HO may be changed by vertical movement of at least one of the vertical moving unit 70 and the antenna 40. Note that, when a design is made such that only the antenna 40 is moved in the vertical direction by a drive unit, for example, the drive unit 80 may be omitted so that the vertical moving unit 70 does not move in the vertical direction, and the vertical moving unit 70 may be fixed at a predetermined height position. Furthermore, in such a case, for example, the drive unit 80 and the vertical moving unit 70 may be omitted, and a platform for placing the object to be heated HO may be provided on the upper surface of the bottom of the lower container 12 of the housing 10.

[0073] (E) Although not mentioned in the heater 1 according to the previous embodiment, a weight sensor for measuring the weight of the object to be heated HO may be provided, and weight information of the object to be heated HO may be transmitted to the microcomputer of the control unit 100. Then, the microcomputer of the control unit 100 may estimate the required amount of heating based on information indicating the type of the object to be heated HO and weight information of the object to be heated HO input by the user via the input / output device 20, and set the estimated required amount of heating as value Z in step Sa11 of process SA and step Sb13 of process SB.

[0074] The above modified examples may be applied individually or in combination.

[0075] <Verification example> The present invention will be described in more detail below by showing verification examples, but the present invention is not limited to the verification examples shown below.

[0076] (Verification example 1) The object to be heated (HO) was a No. 5 (15 cm diameter) frozen whole cake (weight: 350–360 g). Using the heater 1, the frequency of the radio frequency radiated from the antenna 40 was set to 915 MHz, and the initial height of the object to be heated (HO) was set to approximately 80 mm. Heating of the object to be heated (HO) was initiated. The distance between the antenna 40 and the object to be heated (HO) was adjusted so that the return loss was within the range of 3 to 6 as much as possible from the start to the end of heating. The results shown in Figure 6 were obtained. As shown in Figure 6, the return loss increased sharply approximately 4 and 6 minutes after the start of heating. This is presumably due to a change in the state of the object to be heated (HO) from solid to liquid. After heating was completed, the temperatures of the center and sides of the object to be heated (HO) were measured. The center temperature was approximately 21°C, and the side temperature was approximately 19°C. This indicates that adjusting the distance between the antenna 40 and the object to be heated (HO) to minimize the return loss can result in uniform heating of the object to be heated.

[0077] (Verification example 2) The object to be heated (HO) was a No. 5 (15 cm diameter) frozen whole cake (weight: 350-360 g). Using heater 1, the frequency of the high-frequency waves radiated from antenna 40 was set to 915 MHz, and the initial height of the object to be heated (HO) was set to approximately 80 mm. Heating of the object to be heated (HO) was then initiated. The distance between antenna 40 and the object to be heated (HO) was not adjusted from the start to the end of heating. The results shown in Figure 7 were obtained. As shown in Figure 7, a high return loss persisted. After heating was completed, the temperatures of the center and side of the object to be heated (HO) were measured. The center temperature was approximately 47°C, and the side temperature was approximately 15°C. This indicates that when the return loss is high, the object to be heated (HO) is heated locally, rather than uniformly.

[0078] (Verification example 3) The object to be heated (HO) was roast beef (weight: 200 g). Using the heater 1, the frequency of the radio frequency radiated from the antenna 40 was set to 915 MHz, and the initial height of the object to be heated (HO) was set to approximately 33 mm. The distance between the antenna 40 and the object to be heated (HO) was adjusted so that the return loss was within the range of 3 to 6 as much as possible from the start to the end of heating. The results shown in Figure 8 were obtained. In Figure 8, the return loss increases approximately 30 seconds after the start of heating. However, even if the return loss increases in the solid phase, the target core temperature (approximately 65°C for roast beef) was not fully reached. It was also found that excessive increases in the core temperature were mitigated by heat transfer. When the object to be heated (HO) was examined after heating (thawing) was completed, it was found to be uniformly heated. Therefore, it was shown that the object HO to be heated can be heated uniformly by adjusting the distance between the antenna 40 and the object HO to reduce the value of the amount of return loss.

[0079] (Verification example 4) The object to be heated HO was roast beef (weight: 200 g). Using the heater 1, the frequency of the high-frequency waves radiated from the antenna 40 was set to 915 MHz, and the initial height position of the object to be heated HO was set to approximately 72 mm. Then, heating of the object to be heated HO was started. The distance between the antenna 40 and the object to be heated HO was adjusted so that the return loss was within the range of 3 to 6 as much as possible from the start to the end of heating of the object to be heated HO. As a result, the results shown in FIG. 9 were obtained. When the object to be heated HO was checked after heating was completed, it was found to be uniformly heated. This indicates that the object to be heated HO can be heated uniformly by adjusting the distance between the antenna 40 and the object to be heated HO so that the return loss value is reduced. [Explanation of symbols]

[0080] 1 Heater 10. Cabinet 32 Monitor circuit (second temperature measurement unit) 33 Dummy board 40 Antenna 50 Heater 60 Temperature sensor (first temperature measurement unit) 71 Mounting table 80 Drive unit 100 control section HO Heated object

Claims

1. The housing and a mounting table provided in the housing and on which an object to be heated is placed; an antenna that radiates high frequency waves into the housing to heat the object to be heated; a drive unit that moves at least one of the mounting table and the antenna in a vertical direction; a control unit that derives the amount of reflection loss of the high frequency wave, The control unit controls the drive unit to change the distance between the antenna and the object to be heated in accordance with the amount of return loss. Heater.

2. The control unit controls the drive unit so that a peak of a resonant frequency at which the object to be heated resonates moves away from the frequency of the high frequency or moves closer to the frequency of the high frequency. The heater of claim 1 .

3. The control unit derives an average value of the amount of return loss for each fixed time period, controls the drive unit so that the average value falls within a set range, and when a cumulative value of the average value reaches a value set for each of the objects to be heated, stops the antenna from emitting the high frequency wave. The heater according to claim 1 or 2.

4. A heater disposed above the object to be heated; Further comprising a first temperature measuring unit for measuring the temperature of the object to be heated, The control unit controls the drive unit based on the temperature measured by the first temperature measurement unit. The heater of claim 1 .

5. a dummy substrate that converts the reflected high frequency wave into heat; a second temperature measurement unit for measuring the temperature of the dummy substrate, The control unit detects an abnormality based on a relationship between the amount of return loss and the temperature measured by the second temperature measurement unit. The heater of claim 1 .

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