JPS58107161A - High-frequency thawing machine - Google Patents

Abstract

PURPOSE:To provide a high-frequency thawing machine which is constructed to cut the electric source automatically at the end of the thawing irrespective of the kind, size and shape of the food to be thawed when the temperature of the food approaches the melting point, and affords the optimum thawing without causing overthawing and abnormal heating. CONSTITUTION:The food 1 to be thawed is placed between the electrodes 2 and 3, and the thawing machine is connected to a low-frequency AC source, when DC voltage is applied to the high-frequency oscillator 7, high-frequency electric power is applied to the electrodes 2 and 3 and the thawing of the food 1 is started. The oscillation frequency depends upon the kind and size of the food 1 to be thawed, and is picked up with the current transformer 21 and converted to electric signal by the frequency detecting circuit 122, and the rate of change of the oscillation frequency is detected by the data processing circuit 123. When the rate of fequency change decreases below a definite value as the progress of thawing, the switching circuit 120 is operated by the electric source controlling circuit 124 to cut the electric supply.

Description

[Detailed Description of the Invention] The present invention relates to a high-frequency thawing device, and its purpose is to detect the end of thawing according to the type, size, and shape of the object to be thawed, and to perform thawing in a temporally appropriate manner. There is.

Conventional high-frequency thawing machines use a method of defrosting by setting a timer for a defrosting time determined from experience depending on the type, size, and shape of the object to be thawed. Even if the defrosting time for dogs was known, it was difficult to set the defrosting time for each dog. Therefore, there have been cases where the set time is incorrectly set and it takes more time than necessary, or over-thawing causes abnormal heating. In addition, from the viewpoint of usability, it is difficult to use because the timer must be set each time depending on the item to be thawed.

The present invention eliminates the conventional drawbacks and provides a high-frequency thawing machine that automatically detects the end of thawing and thaws in an appropriate time, regardless of the type, size, or shape of the object to be thawed. An embodiment of the present invention will be described below with reference to the drawings.

Fig. 1 shows a schematic configuration of a high-frequency thawing machine, in which an upper electrode 2 is constructed by providing a predetermined gap between the two parts of the object 1 to be thawed.
．． A lower electrode 3 is configured below the object 1 to be thawed, and both electrodes 2
, 3 is applied to heat and thaw the object 1 due to the dielectric loss of the object 1 to be thawed. 4 and 5 are insulating covers that insulate the upper and lower electrodes 2 and 3. Reference numerals 6 and 7 denote a high-voltage power supply section and a high-frequency oscillator that supply high-frequency energy to the object 1 to be thawed, which are shielded to prevent radio waves from leaking to the outside and are connected to the high-voltage power supply section through a power supply line 8.

Reference numeral 9.10 denotes a power supply line that supplies power to the upper and lower electrodes 2 and 3. Reference numeral 11 is a thawing chamber in which the object 1 to be thawed is stored.

FIG. 2 is a block diagram of a high-frequency defrosting machine according to an embodiment of the present invention, in which a high-voltage power source 6 is connected to a low-frequency AC power source.
DC power is applied to the high frequency oscillator 7 through 1. 120 is a controllable switching circuit that opens and closes the contacts and turns off the power supply according to commands from the control circuit 12. The control circuit 12 indirectly connects the high frequency output of the high frequency oscillator 7. Current transformer 121
The frequency is picked up by the frequency detection circuit 122, converted into an electrical signal, and added to the information processing circuit 123. When the rate of change in frequency within a certain time becomes less than a certain value, the switching circuit 120 is activated by the power supply control circuit 124. The game is set to turn off the power.

In this example, the oscillation frequency is detected using current transformer 1.
Although this is done indirectly using the frequency detection circuit 12, of course, the output is directly taken out from a part of the oscillation circuit and the frequency detection circuit 12
You can put it in 2. Generally, when a certain amount of energy is applied to a frozen product, the change in temperature during thawing is as shown by the dotted line in Figure 3.

In other words, in the early stages of thawing, the energy given to the thawed object turns into sensible heat, causing its temperature to rise rapidly, but as thawing progresses and the temperature of the material approaches its melting point, the given energy is taken away as latent heat. The product temperature will almost no longer rise. Conversely, when the product temperature hardly increases, it can be said that the product temperature has reached the melting point, and it can be said that thawing is completed. Figure 3 shows a comparison of changes in high-frequency oscillation frequency when thawing is performed using a high-frequency thawing machine, as well as changes in product temperature. From this figure, it can be seen that the oscillation frequency changes in accordance with the product temperature, that the oscillation frequency decreases rapidly at the beginning of thawing, and hardly changes near the end of thawing. As can be seen from the high-frequency oscillator 7 in Fig. 2, the parts connected to the thawing object 1, upper and lower molds @2.3 form part of the resonant circuit of the high-frequency oscillator 7 as a capacitor. Therefore, the oscillation frequency is determined by the temperature of the item to be thawed.

As mentioned above, the oscillation frequency rapidly decreases at the beginning of thawing, and remains almost unchanged at the end of thawing, which is known to occur regardless of the type, size, or shape of the object to be thawed. By constantly detecting the change rate and knowing when the rate of change becomes small, you can know when the defrosting is finished.

Based on this principle, the operation of this embodiment can be summarized as follows: When the object 1 to be thawed is installed between the electrodes 2 and 3 and connected to a low frequency AC power source, a DC voltage is applied to the high frequency oscillator 7, and the electrode 2 , 3, a high frequency output is applied between the thawing object 1
begins to thaw. The oscillation frequency at this time varies depending on the type, size, etc. of the object 1 to be thawed. Current transformer 1
21, the frequency detection circuit 122 captures it as an electrical signal, the information processing circuit 123 detects the rate of change in the oscillation frequency, and when the decompression progresses and the rate of change in the oscillation frequency falls below a certain value, the power supply control circuit 124 detects the The switching circuit 120 is operated to turn off the power.

Thus, according to the present invention, the type of the object to be thawed.

Regardless of the size or shape, the power is automatically turned off when the temperature of the item to be thawed approaches the melting point and thawing is complete, so there is no need for troublesome tasks such as setting a timer.
It is possible to provide a high-frequency thawing machine that can obtain an optimal thawing state without excessive thawing or abnormal heating.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing a high-frequency thawing machine according to an embodiment of the present invention, Fig. 2 is a block diagram of the same high-frequency thawing machine, and Fig. 3 is the relationship between oscillation frequency and product temperature with respect to elapsed time during thawing. FIG. 1...Object to be thawed, 2, 3...Electrode, 6
・・High voltage power supply section, 7・・High frequency oscillator, 11
... Thawing chamber, 12 ... Control circuit, 122
...Frequency detection circuit, 123... Information processing circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 11'l Figure 2 Figure 3

Claims (1)

[Claims] , a thawing chamber that stores the object to be thawed, a high frequency oscillator that supplies high frequency energy to the object to be thawed, and upper and lower electrodes that apply high voltage to perform thawing by dielectric heating. It has a frequency detection circuit that extracts the oscillation frequency as an electrical signal, and an information processing circuit that detects the rate of change in frequency and issues a command when it falls below a certain value.The information processing circuit automatically detects the completion of defrosting by J: in response to the command from the information processing circuit. High frequency thawing machine.