阅读说明：本技术 高频解冻装置 (High-frequency thawing device ) 是由 岸本卓士 于 2020-03-03 设计创作，主要内容包括：本发明提供一种高频解冻装置,其特征在于,具备：加热室(1),上部电极(2a)和下部电极(2b),平行配置在该加热室(1)内且被解冻物插入在其间,高频电源(4)以及匹配电路(6),将高频电压施加在上部电极(2a)和下部电极(2b)之间,功率检测电路(5),检测被施加的高频电压的反射功率,控制装置(7),基于从在功率检测电路(5)的检测信号的从解冻开始时以来的变化,推定被解冻物的进展状态,判断解冻完成,基于判断控制高频电源(4)。(The present invention provides a high-frequency thawing apparatus, comprising: the thawing apparatus comprises a heating chamber (1), an upper electrode (2a) and a lower electrode (2b) which are arranged in parallel in the heating chamber (1) with an object to be thawed interposed therebetween, a high-frequency power supply (4) and a matching circuit (6) which apply a high-frequency voltage between the upper electrode (2a) and the lower electrode (2b), a power detection circuit (5) which detects reflected power of the applied high-frequency voltage, and a control device (7) which estimates the progress state of the object to be thawed based on a change from the thawing start time of a detection signal of the power detection circuit (5), determines that thawing is completed, and controls the high-frequency power supply (4) based on the determination.)

1. A heating high-frequency thawing apparatus is characterized by comprising:

a heating chamber,

an upper electrode and a lower electrode disposed in parallel in the heating chamber with an object to be thawed interposed therebetween,

a voltage applying section that applies a high-frequency voltage between the upper electrode and the lower electrode,

a reflected power detection unit for detecting the reflected power of the high-frequency voltage applied by the voltage application unit,

a thawing completion determination unit that estimates a state of progress of the object to be thawed based on a change from a time of thawing start of the detection signal at the reflected power detection unit and determines completion of thawing,

and a control unit that controls the voltage application unit based on the determination by the thawing completion determination unit.

2. The high-frequency thawing apparatus according to claim 1, wherein the thawing completion determination unit determines that thawing has been completed when the detection signal changes from an increase region indicating a rapid increase in reflected power to a steady region not indicating a rapid increase.

3. The high-frequency thawing apparatus according to claim 2, comprising:

an extended heating mode in which heating is extended even after the detection signal is changed to the stable region,

the control unit uses a time from the start of heating until the detection signal reaches the stable region as an element for determining an extended heating time in the extended heating mode.

4. The high-frequency thawing apparatus according to claim 3, wherein the control unit further uses temperature information before the start of heating of the object to be thawed as an element for determining the time for the extended heating in the extended heating mode.

5. The high-frequency thawing apparatus according to any one of claims 1 to 4, wherein the voltage application unit comprises a matching circuit that adjusts impedance when a ratio of reflected power of incident power of the high-frequency voltage exceeds a threshold value,

the thawing completion determination unit determines that thawing has been completed when the ratio of the reflected power to the incident power of the high-frequency voltage does not exceed the threshold value even after a predetermined time has elapsed after the impedance adjustment of the matching circuit.

Technical Field

The present invention relates to a high-frequency thawing apparatus for applying a high-frequency electric field to an object to be thawed such as frozen food to thaw the object.

Background

A high-frequency thawing apparatus is known which applies a high frequency of MHz or more and thaws an object to be thawed, such as a food frozen by dielectric heating (for example, patent documents 1 and 2). The high-frequency thawing apparatus includes an upper electrode and a lower electrode in a heating chamber, and performs thawing by dielectric loss of a thawed object by supplying a high-frequency electric field between the two electrodes from a high-frequency power supply. Since the induction heating method is a method in which a parallel electric field uniformly reaches the inside of a frozen food, it is suitable for thawing a large-sized object to be thawed, as compared with thawing by microwave using a microwave oven.

Disclosure of Invention

Technical problem to be solved by the invention

However, in the conventional high-frequency thawing apparatus, a predetermined processing time (for example, 15 minutes per 1000g of meat) is set according to the type and amount (size, weight) of the object to be thawed. Therefore, before starting the treatment, it is necessary to recognize the type and amount of the object to be thawed and set the treatment time based on the recognized type and amount.

Further, when thawing is performed for a predetermined processing time, there is a problem that the completion accuracy is unstable due to excessive thawing caused by an excessively long processing time due to a difference in the shape of the food, the initial temperature of the food (the temperature before thawing is started), or the like, or conversely, due to insufficient thawing caused by an excessively short processing time.

An object of one aspect of the present invention is to realize a high-frequency thawing apparatus having excellent completion accuracy without setting a thawing time.

Means for solving the problems

In order to solve the above problem, a high-frequency device according to an aspect of the present invention includes: a heating chamber, an upper electrode and a lower electrode which are arranged in parallel in the heating chamber and between which an object to be thawed is inserted; a voltage applying section that applies a high-frequency voltage between the upper electrode and the lower electrode; a reflected power detection unit that detects reflected power of the high-frequency voltage applied by the voltage application unit; a thawing completion determination unit that estimates a state of progress of the object to be thawed based on a change from a time of thawing start of the detection signal at the reflected power detection unit and determines completion of thawing; and a control unit that controls the voltage application unit based on the determination by the thawing completion determination unit.

Effects of the invention

According to an aspect of the present invention, a high-frequency thawing apparatus having excellent completion accuracy can be realized without setting a thawing time.

Drawings

Fig. 1 is a schematic diagram showing a configuration of a high-frequency thawing apparatus according to a first embodiment of the present invention.

Fig. 2 is a diagram showing a circuit configuration in the high-frequency thawing apparatus.

Fig. 3 is a diagram showing a correlation between detection signals of incident power and reflected power detected by the power detection circuit of the high-frequency thawing apparatus and a thawing progress state when thawing an object to be thawed.

FIG. 4 is a flowchart showing the operation of the high-frequency thawing apparatus.

FIG. 5 is a diagram showing the correlation between detection signals of incident power and reflected power detected by the power detection circuit of the high-frequency thawing apparatus and the progress of thawing when thawing an object to be thawed,

which is different from fig. 3 in the initial temperature of the thawed matter.

Fig. 6 is a flowchart showing the operation of the high-frequency thawing apparatus according to the second embodiment of the present invention.

Detailed Description

[ first embodiment ]

Hereinafter, an embodiment of the present invention will be described in detail. First, a schematic configuration of a high-frequency thawing apparatus according to the present embodiment will be described with reference to fig. 1 and 2. Fig. 1 is a schematic diagram showing the configuration of the high-frequency thawing apparatus according to the present embodiment. Fig. 2 is a diagram showing a circuit configuration in the high-frequency thawing apparatus.

The high-frequency thawing apparatus applies a high-frequency electric field to an object 3 to be thawed, such as frozen food, to perform a thawing process of the object 3. More specifically, the high-frequency thawing apparatus is an induction heating type thawing apparatus, and applies a principle that when a high-frequency electric field is applied to a dielectric, the object 3 to be thawed is placed in a parallel electric field generated between parallel electrodes to which a high-frequency voltage is applied by heating the object by generating heat (dielectric loss) due to molecular friction thereof, and is thawed by the dielectric loss heat.

As shown in fig. 1, the high-frequency thawing apparatus includes a heating chamber 1, an upper electrode 2a, a lower electrode 2b, a high-frequency power supply 4, a power detection circuit 5, a matching circuit 6, a control device (thawing completion determination unit, control unit) 7, an operation input unit 8, and the like. A voltage application unit for applying a high-frequency voltage between the upper electrode 2a and the lower electrode 2b is constituted by the high-frequency power supply 4 and the matching circuit 6.

The heating chamber 1 is formed of a metal frame. The upper electrode 2a and the lower electrode 2b are disposed vertically in parallel in the heating chamber 1. An object to be thawed 3 such as food is placed between the upper electrode 2a and the lower electrode 2 b. The upper electrode 2a is vertically movable by an unshown elevating mechanism, and its height is adjusted to a position corresponding to the thickness of the object 3 to be thawed.

The high-frequency power source 4 transmits a voltage signal of a frequency in a band from HF to VHF. The voltage signal transmitted from the high-frequency power supply 4 is amplified to a desired power by an amplifier (not shown). The amplified voltage signal is transmitted to the matching circuit 6 via the power detection circuit 5.

The power detection circuit 5 detects incident power (incident wave) from the high-frequency power supply 4 to the matching circuit 6 and reflected power (reflected wave) from the matching circuit 6 to the high-frequency power supply 4. These detection signals are sent to the control device 7. The power detection circuit 5 corresponds to a reflected power detection unit that detects reflected power of the high-frequency voltage applied by the voltage application unit.

As shown in fig. 2, the matching circuit 6 includes variable capacitors 6a and 6b, a variable coil 6c, and the like, and cancels the reactance of the capacitor formed by the upper electrode 2a and the lower electrode 2 b. Further, the matching circuit 6 can make the input impedance to the matching circuit 6 and the output impedance to the amplifier uniform by adjusting the values of the variable capacitors 6a and 6b and the variable coil 6 c. This enables a high-frequency electric field to be effectively applied to the object 3 to be thawed. The output of the matching circuit 6 is supplied to the upper electrode 2a and the lower electrode 2b in the heating chamber 1, and the object 3 to be thawed inserted between the upper electrode 2a and the lower electrode 2b is subjected to high-frequency dielectric heating.

Returning to fig. 1, the control device 7 controls the respective parts of the high-frequency thawing apparatus such as the high-frequency power supply 4 and the matching circuit 6. When the start of the thawing process is instructed from the operation input unit 8, the control device 7 operates the high-frequency power supply 4 after adjusting the height of the upper electrode 2a by a not-shown elevating mechanism.

The detection signals of the incident power and the reflected power are input from the power detection circuit 5 to the control device 7. The control device 7 controls the output of the high-frequency power source 4 so that the power of the reflected power subtracted from the incident power, i.e., the power after being efficiently transmitted to the matching circuit 6, is fixed.

Fig. 3 is a diagram showing a correlation between detection signals of incident power and reflected power detected by the power detection circuit 5 when the object 3 to be thawed is thawed and a progress state of thawing. The horizontal axis of fig. 3 represents time (minutes) and the vertical axis represents power (W).

As shown in fig. 3, the control device 7 controls the output of the high-frequency power supply 4 so that the power obtained by subtracting the reflected power from the incident power is always constant, and the incident power is increased in accordance with the increase in the reflected power. In the example of fig. 3, the output of the high-frequency power supply 4 is adjusted so that the power obtained by subtracting the reflected power from the incident power always remains 150W.

When the high-frequency electric field is applied and the moisture contained in the object 3 to be thawed starts to change from a solid to a liquid, the reflected power increases rapidly. When the incident power is continuously increased in accordance with such an increase in the reflected power, the output of the high-frequency power supply 4 increases, and the load applied to the high-frequency power supply 4 and the like increases. Therefore, when the ratio RW/FW of the reflected power (RW) to the incident power (FW) exceeds the threshold value X, the control device 7 adjusts the variable capacitors 6a and 6b, the variable coil 6c, and the like in the matching circuit 6 so that the reflected power is set to 0W. Such impedance adjustment is repeated every time the ratio RW/FW exceeds the threshold value X. In the example of fig. 3, the threshold value X is set to 10%, and impedance adjustment is performed every time the ratio RW/FW exceeds 10%.

Then, as shown in fig. 3, the amount of increase in reflected power with time is large and the rate of change is steep (increasing region) for a while after thawing is started. This is because a large amount of moisture contained in the thawed material 3 changes from solid to liquid during this period. Then, when time elapses, the amount of increase in reflected power with respect to time becomes small, the rate of change becomes gentle, and then becomes almost horizontal, and enters a stable region where no sharp increase is exhibited. This is because the thawing has progressed, a large amount of moisture contained in the object to be thawed 3 is changed into liquid, and the state has stopped changing. That is, the proportion of change in reflected power with respect to time changes from a steep increase region to a stable region that does not show a sharp increase, and it can be determined that thawing has been completed.

Using the correlation between the reflected power and the change in the moisture state of the object 3 to be thawed, the control device 7 estimates the progress of thawing of the object 3 based on the change from the time of thawing start in the detection signal of the reflected power, and determines completion of thawing. Specifically, when the detection signal of the reflected power changes from an increase region indicating a rapid increase in the reflected power to a stable region not indicating a rapid increase, the control device 7 determines that the thawing has been completed.

In the present embodiment, after the control device 7 performs impedance adjustment using the impedance adjustment function and sets the reflected power to 0W, even if the preset time T1 has elapsed, the control device determines that thawing of the object 3 has been completed and stops the output of the high-frequency power supply 4 if the ratio RW/FW does not exceed the threshold value X. The time T1 is set to a time at which the proportion of the change in reflected power can be judged to be in the stable region.

In the example of fig. 3, the interval between the fourth and fifth impedance adjustments takes about 2.2 minutes, and the interval of about 1.5 minutes from the end becomes long. Then, the interval between the fifth and sixth impedance adjustments was set to be 5.3 minutes longer. In the waveform state, the time T1 is set to 4 minutes, for example. When the ratio RW/FW does not exceed 10% even after 4 minutes has elapsed since the impedance adjustment, the control device 7 determines that the thawing has been completed and stops the output of the high-frequency power supply 4.

The time T1 is a value that varies depending on the output of the high-frequency power supply 4, the threshold X for impedance adjustment, and the like. Therefore, the time until the object 3 is uniformly thawed at 0 degrees is set after the thawing state of the object 3 is confirmed. In the case of the device that varies the output of the high-frequency power supply 4 and the threshold value X for impedance adjustment, a plurality of times T1 are held with priority based on the combination of variable parameters (elements) that affect the time T1.

Next, the operation of the high-frequency thawing apparatus having the above-described configuration will be described with reference to the flowchart of fig. 4. Fig. 4 is a flowchart showing the operation of the high-frequency thawing apparatus. The object 3 to be thawed is set between the upper electrode 2a and the lower electrode 2b, and the user instructs thawing by the operation input unit 8. The control device 7 receives the signal from the operation input unit 8 (S1), moves the upper electrode 2a to adjust the height (S2), and then operates the high-frequency power source 4 (S3). Thereby, a high-frequency voltage is applied to the upper electrode 2a and the lower electrode 2 b.

The high-frequency voltage supplied from the high-frequency power supply 4 is supplied to a capacitor formed by the upper electrode 2a and the lower electrode 2b as a voltage signal for impedance matching at the matching circuit 6. Thereby, a high-frequency electric field is generated between the upper electrode 2a and the lower electrode 2 b. Then, the object 3 to be thawed disposed between the upper electrode 2a and the lower electrode 2b is heated by the medium and thawed.

While the high-frequency power source 4 is operating, the incident power and the reflected power are measured by the power detection circuit 5 and transmitted to the control device 7. The control device 7 calculates a ratio RW/FW using the received incident power and reflected power (S4), and determines whether the calculated ratio RW/FW exceeds 10% which is the threshold value X (S5).

When the control device 7 determines in S5 that the ratio is not exceeded (NO), the process returns to S4 to calculate the ratio RW/FW again. In S5, the control device 7 repeats the processing of S4 and S5 until the determination is YES. On the other hand, if the controller 7 determines that the reflected power exceeds the predetermined threshold value at S5 (YES), the impedance is adjusted by the matching circuit 6 to set the reflected power to 0W (S6).

When the impedance adjustment is performed, the control device 7 determines whether or not the time T1, for example, 4 minutes, has elapsed after the adjustment is performed (S7). When the control device 7 determines in S7 that the ratio has not elapsed (NO), it returns the process to S4 to calculate the ratio RW/FW again. The control device 7 repeats the processing from S4 to S7 until the determination of YES is made in S7.

When the control device 7 determines in S7 that the time T1 has elapsed (YES), it stops the output of the high-frequency power source 4 (S8). Since the ratio RW/FW does not exceed 10% even after the time T1 elapses after the impedance adjustment is performed and the reflected power is set to 0W, it can be judged that the reflected power is in a stable state in a stable region and the thawing is completed. This allows the object 3 to be thawed with good completion accuracy.

Note that, although not shown in the flowchart of fig. 4, if the repetition of the processing of S4 and S5 continues after a predetermined time has elapsed, the operation jumps to the stop of the high-frequency power supply of S8.

(Effect)

In the above configuration, the detection signal of the reflected power estimates the progress of thawing of the object based on the change in the reflected power from the start of thawing, and changes from an increase region showing a rapid increase (an increase region in which the rate of change in the reflected power with respect to time is steep) to a steady region not showing a rapid increase (a steady region in which the rate of change in the reflected power with respect to time is gradually close to horizontal), thereby determining completion of thawing.

Thus, since the user appropriately determines completion of thawing by the high-frequency thawing apparatus based on the type and amount (size) of the object 3 to be thawed even if the time for performing the thawing process is not set, automatic thawing with satisfactory completion accuracy can be performed only by setting the object 3 to be thawed and giving an instruction to start thawing.

In addition, although temperature unevenness is less likely to occur as compared with thawing by microwaves, when the surface temperature of the object 3 to be thawed is measured by infrared rays or the like and completion of thawing is determined, if the temperature at the measurement site is different from that at most other sites, over-thawing or under-thawing may occur. However, in the above-described mechanism, the completion of thawing is determined by using information obtained from the whole object 3 to be thawed, such as a detection signal of reflected power, and such a defect does not occur.

Further, in the above-described configuration, with the ratio RW/FW used for the impedance adjustment, even if the ratio RW/FW does not exceed the threshold value X after the time T1 has elapsed from the previous impedance adjustment, it is judged that the detection signal of the reflected power has changed to the stable region. This makes it possible to include the thawing completion determination process in the conventional impedance adjustment process flow.

[ second embodiment ]

Other embodiments of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiments are given the same reference numerals, and the explanation thereof will not be repeated.

In the food material such as sliced raw fish which is eaten without being heated after thawing, it is preferable to finish thawing in a state of being heated to, for example, 10 ℃ instead of 0 ℃. This is because the human tongue can feel the deliciousness and taste of food at a temperature of 10 c instead of 0 c. By heating to 0 deg.C or higher in the range where ice is felt, the sashimi can be made more delicious.

The high-frequency thawing apparatus according to the present embodiment differs from the high-frequency thawing apparatus according to the first embodiment only in that it has an extended heating mode and heats the object 3 to be thawed by extending the detection signal even after the detection signal has changed to the stable region. The thawed material 3 can be heated to a higher temperature than 0 ℃ and supplied by using the extended heating mode.

The control device 7 uses the time required for thawing from the start of heating to the time when the detection signal reaches the stable region as an element for determining the extended heating time for extending the heating. In other words, the control device 7 is determined by using at least the extended heating time and the defrosting time in the extended heating mode.

In the present embodiment, when the extended heating mode is selected, the control device 7 continues the driving of the high-frequency power source 4 from the time when the thawing of the object 3 is determined to be completed to the set extended heating time. This extended heating time is a heating time for heating the object 3 to be thawed at 0 ℃ from 0 ℃ to, for example, 10 ℃. Therefore, the heating time needs to be set according to the heat capacity of the object 3 to be thawed. The control device 7 uses a time Tt required for thawing from the start of thawing the object 3 to the judgment of completion of thawing as an element for determining the extended heating time. This is because the thawing required time Tt contains information on the heat capacity of the object 3 to be thawed. By using the thawing required time Tt according to the change in the heat capacity of the object 3 to be thawed, it is possible to set the heating time to be longer according to the heat capacity of the object 3 to be thawed, even if the type and amount of the object 3 to be thawed are not recognized.

However, the time Tt required for thawing depends not only on the heat capacity of the object 3 to be thawed but also on the initial temperature of the object 3 to be thawed. Therefore, it is preferable to measure the initial temperature and correct the extended heating time obtained from the thawing required time Tt. This will be described with reference to fig. 3 and 5.

Fig. 5 is a diagram showing a correlation between detection signals of incident power and reflected power detected by the power detection circuit 5 when the thawed article 3 is thawed and a state of progress of thawing. Similarly to fig. 3, the horizontal axis of fig. 6 represents time (minutes) and the vertical axis represents power (W). In fig. 3 and 5, the thawed material 3 is the same, but the initial temperature of the thawed material 3 is different, the initial temperature of fig. 3 is-20 degrees, and the initial temperature of fig. 5 is-40 ℃.

As is clear from a comparison of fig. 3 and 5, the time Tt required for thawing depends on the initial temperature, and the time required for the initial temperature to be lower is longer. Therefore, for example, the extended heating time is k (k > 0) times the thawing required time Tt, and similarly, the heating is started from 0 ℃, but the lower initial temperature extends the heating time and the finish temperature increases.

Therefore, for example, when k is set based on an initial temperature of-20 ℃, k' after correction is corrected to a time required for thawing Tt (-40 ℃) × k after correction when the initial temperature is-40 ℃. Thus, the completion temperature is stabilized regardless of the initial temperature.

The correction value for correcting the value k is stored as a table in a storage unit provided in the control device 7. The value k and the table for correcting the value k are prepared for each of the temperatures set to 10 ℃, 20 ℃, 30 ℃ and the like in the extended heating mode.

The operation of such a high-frequency thawing apparatus will be described with reference to the flowchart of fig. 6. Fig. 6 is a flowchart showing the operation of the high-frequency thawing apparatus according to the present embodiment. The object 3 to be thawed is set between the upper electrode 2a and the lower electrode 2b, and the user instructs thawing in the extended heating mode by using the operation input unit 8. Upon receiving the signal from the operation input unit 8 (S11), the control device 7 performs the processing of S2 to S7 described in the flowchart of fig. 4. Then, when the control device 7 determines in S7 that the time T1 has elapsed (YES), S12 and S13 are performed before the process of stopping the output of the high-frequency power supply 4 in S8.

In S12, when it is judged that thawing has been completed, the time Tt × k (or k') required for thawing is set as the extended heating time. Then, in S13, it is repeatedly determined whether or not the time of the prolonged heating set in S12 has elapsed. If it is judged at S13 that the voltage has passed (YES), the routine proceeds to S8 where the output of the high frequency power source 4 is stopped.

The information on the initial temperature of the object 3 to be thawed may be inputted by the user by operating the input unit 8, or by providing the heating chamber 1 with an infrared temperature sensor for measuring the surface temperature of the object 3 to be thawed. The user can acquire the information of the initial temperature from the set temperature of the freezing chamber.

Normal thawing in which stopping is performed at 0 ℃ or thawing by an extended heating mode can be set by the operation input section 8. The operation input unit 8 may be provided with a thawing button for starting normal thawing and an extended heating thawing button for starting thawing in the extended heating mode, or may be provided with a thawing start button for starting normal thawing and a selection button for selecting thawing in the extended heating mode by operating before the thawing start button. The temperature reached by the defrosting in the extended heating mode may be selected from a predetermined temperature such as 10 ℃ or 20 ℃ or may be arbitrarily set between 5 ℃ and 30 ℃.

[ third embodiment ]

Other embodiments of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiments are given the same reference numerals, and the explanation thereof will not be repeated.

When a food material such as meat is sliced, the whole may be frozen to such an extent that the food material is easily cut with a knife or a slicer, and the food material may be easily processed as compared with a completely thawed state. Therefore, it is desired to stop the thawing function in a half-thawed state where the whole is frozen to such an extent that the whole is easily cut with a knife or a microtome. The high-frequency thawing apparatus according to the present embodiment is different from the high-frequency thawing apparatus according to the first embodiment only in that it further includes a half-thawing function for stopping thawing of the article 3 to be thawed in a half-thawed state.

When the half-thaw is selected, the control device 7 changes the time T1 in the flowchart of fig. 4 to the time T2 corresponding to the half-thaw which is shorter than the time T1. Thus, even if the ratio RW/FW does not exceed 10% after the time T2 has elapsed since the impedance adjustment was performed and the reflected power was set to 0W, the control device 7 determines that the object 3 has been half-thawed and stops the high-frequency power supply 4.

It is preferable that the time T2 for determining the semi-thawing state be adjusted by the initial temperature of the object 3 to be thawed. As shown in fig. 5, in the case where the initial temperature was-40 ℃, time T2 was set to 3 minutes. Thus, even if 3 minutes have elapsed after the sixth impedance adjustment, the controller 7 determines that the time is half-thaw without the ratio RW/FW exceeding 10%. On the other hand, as shown in FIG. 3, in the case where the initial temperature was-20 ℃, time T2 was set to 2 minutes. Thus, even if 2 minutes have elapsed after the fourth impedance adjustment, the controller 7 determines that the time is half-thaw without the ratio RW/FW exceeding 10%.

The full thawing or the half thawing can be set by the operation input section 8. A full-thaw button for starting full-thaw and a half-thaw button for starting half-thaw may be set in the operation input unit 8, or a full-thaw start button for starting full-thaw and a selection button for selecting thawing by half-thaw by operating before the thaw start button may be set.

[ conclusion ]

A high-frequency thawing apparatus according to embodiment 1 of the present invention includes a heating chamber 1, an upper electrode 2a and a lower electrode 2b arranged in parallel in the heating chamber 1 with an object to be thawed 3 interposed therebetween; a voltage applying unit (high-frequency power source 4, matching circuit 6) for applying a high-frequency voltage between the upper electrode 2a and the lower electrode 2 b; a reflected power detection unit (power detection circuit 5) for detecting the reflected power of the high-frequency voltage applied by the voltage application unit; a thawing completion determination unit (control device 7) that estimates a state of progress of the object 3 to be thawed based on a change from a time of thawing start of the detection signal at the reflected power detection unit and determines completion of thawing; and a control unit (control device 7) for controlling the voltage applying unit based on the determination by the thawing completion determining unit.

In the high-frequency thawing apparatus according to aspect 2 of the present invention, in aspect 1, the thawing completion determination unit may be configured to determine that thawing has been completed when the detection signal changes from an increase region indicating a rapid increase in reflected power to a stable region not indicating a rapid increase.

In the high-frequency thawing apparatus according to aspect 3 of the present invention, in aspect 2, the extended heating mode is configured to extend heating even after the detection signal changes to the stable region, and the control unit uses a time from a start of heating until the detection signal reaches the stable region as an element for determining the time of extended heating in the extended heating mode.

In the high-frequency thawing apparatus according to aspect 4 of the present invention, in aspect 3, the control unit may further use temperature information before the start of heating the object 3 to be thawed as an element for determining the time for which heating is extended in the extended mode.

In the high-frequency thawing apparatus according to aspect 5 of the present invention, in any one of aspects 1 to 4, the voltage applying unit may include a matching circuit 6 that performs impedance adjustment when a ratio of the reflected power to the high-frequency voltage exceeds a threshold, and the thawing completion determining unit may determine that thawing has been completed when the ratio of the reflected power to the high-frequency voltage does not exceed the threshold even after a predetermined time has elapsed after the impedance adjustment by the matching circuit 6.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention. Further, new technical features can be formed by combining the technical means disclosed in the respective embodiments.

Description of the reference numerals

1 heating chamber

2a upper electrode

2b lower electrode

3 object to be thawed

4 high frequency power supply (Voltage applying part)

5 Power detection circuit (reflected power detection unit)

6 matching circuit (Voltage applying part)

6a, 6b variable capacitor

6c variable coil

7 control device (control unit, thawing completion determination unit)

8 operation input unit