JPS587788A - High frequency deicing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a high-frequency decompression device 6QKQm'@ that uses a complex resonance IZi Mengyo circuit as a resonance circuit of a high-frequency oscillation circuit.

In conventional high-frequency oscillators, the resonant circuit of the high-frequency oscillation circuit that generates the high-frequency high voltage applied to the heating electrode involves connecting a resonant capacitor and a resonant coil in series to form a series resonant circuit. . Although this method simplifies the formation of a resonant circuit, it has the disadvantage that the Q value of the resonant circuit cannot be set high and the oscillation operation of the high frequency oscillation circuit tends to become unstable.

The present invention uses a composite resonant circuit as a resonant circuit of a high-frequency oscillation circuit, and provides a high-frequency decompression device that eliminates the above-mentioned drawbacks.

An embodiment of the present invention will be described below with reference to the drawings.

A casing 1 of the high-frequency thawing device includes an oven cavity 2 made of metal and grounded, and a high-frequency oscillation circuit chamber 3. Inside the oven cavity 2, there is a lower fixed heating electrode 4;
Above the heating electrodes 6, which are movable up and down, the heating electrodes 6 are opposed to each other in a parallel relationship. The heating electrodes 4 and 6 are each connected to a high frequency oscillation circuit 6. The heating electrode 6 is made of non-metallic material with low dielectric loss (small tan δ) for the purpose of protecting the electrode surface, etc.
A protection plate 7 is attached.

Also placed above the heating electrode 4 is a mounting plate 8 which is also made of non-metal and has low dielectric loss.

FIG. 2 shows the high frequency oscillation circuit 6 and its heating electrodes 4 and 5.
An example of connection to is shown. A choke coil 1o and a field effect transistor 11, which is one of the signal amplification elements, are connected in series to the output terminal of the DC power supply 9, and a capacitor 12 is connected in parallel to the field effect transistor 11. A bypass capacitor 16 is connected between the gate terminal 13 and the source terminal 14, which are input terminals of the field effect transistor 11, and a resonant circuit is connected between the drain terminal 16 and the gate terminal 13.

In this resonant circuit, a capacity stabilizing capacitor 17 is connected in parallel to the heating electrodes 4 and 6 which also serve as resonance capacitors, and a capacitor 17 is connected in series to the parallel connection of the heating electrodes 4 and 6 and the capacitance stabilizing capacitor 17. A resonance coil 18 is connected to the parallel heating electrode 4.5 and a capacitor 17 for stabilizing the capacitance, and a capacitor for stabilizing oscillation is connected in parallel to the parallel series connection body in which the resonance coil 18 is connected in series to the parallel connection body of the parallel heating electrode 4.5 and the capacitor 17 for stabilizing the capacitance. 19 are connected. In this way, the drain terminal 16 and gate terminal 13 of the field effect transistor 11
A composite resonant circuit is provided between them, and as a whole, an oscillation circuit with a frequency of about 6 MHz is formed around the field effect transistor 11. The output terminal of the DC power supply is a capacitor 20.21
It is connected to the high frequency thawing device main body 1, and is in a state close to grounding in terms of alternating current.

With the above configuration, the food to be thawed 22 is placed on the placing plate 8, and the heating electrode 5 is moved up and down from above to thaw the food 22.
The position of the heating electrode 6 is set so that the top surface of the heating electrode 2 and the bottom surface of the protection plate 7 are in contact with each other. Thereafter, when the DC power supply 9 is started, the high frequency oscillation circuit 6 using the field effect transistor 11 starts oscillating, and a high frequency high voltage is induced between the heating electrode 4 and the heating electrode 6. Ru. The food to be thawed 22- is heated due to dielectric loss due to the electric field generated by the high frequency and high voltage. As the food 22 to be thawed is heated, the magnitude of the dielectric loss of the food 22 to be thawed changes, and the capacitance and Q value of the heating electrode 4.6 change.

In the Colpitts oscillation circuit, which is the oscillation method used in this example, oscillation is stable when the Q value of the resonant circuit is high. Therefore, the resonant circuit in this example combines a heating electrode with a variable Q value with a capacitor with a high Q value to resonate. The Q value of the entire circuit is set high.

The relationship between AC angular frequency and actance of this composite resonant circuit is shown in FIG. From the figure, it can be seen that there is an angular frequency ω1 at which the reactance becomes 0 and an angular frequency ω2 at which the reactance becomes maximum or minimum. The high frequency oscillation circuit of this embodiment is a Colpitts oscillation circuit, and in this system, the reactance of the resonant circuit section is positive, that is, the oscillation occurs in a portion above the horizontal axis of the characteristic diagram of FIG. Therefore, this high frequency oscillation circuit operates in a relatively narrow frequency band between angular frequencies ω1 and ω2.

As described above, the high frequency thawing device of the present invention uses a composite resonant circuit consisting of three capacitors and one coil in the resonant circuit section, so that it can stably generate high frequency and high voltage even when the load to be thawed changes. It has a high-frequency oscillation circuit that supplies high-frequency signals, and is highly effective in practice.

[Brief explanation of drawings]

FIG. 1 is a perspective front view of a high-frequency thawing device according to an embodiment of the present invention, FIG. 2 is an electric circuit diagram of the same high-frequency thawing device, and FIG. 3 is a composite resonant circuit section glue of a high-frequency oscillation circuit of the high-frequency thawing device It is an actance characteristic diagram. 2... Oven cavity, 4... Fixed heating electrode, 6... Moving heating electrode, 6...
...High frequency oscillation circuit, 9...DC power supply, 1
o...Choke coil, 11...Field effect transistor, 12...Capacitor, 16
......Bypass capacitor, 17...Capacitance stabilization capacitor, 18...Resonance coil, 19...Oscillation stabilization capacitor, 22...
...Thawing mole. . a-s *m-work, i, ka1,71
,4'III

Claims (1)

[Claims] A high frequency oscillation circuit that generates high frequency and high voltage, a parallel heating electrode connected to the high frequency oscillation circuit, and an oven cavity that houses the heating electrode. a bypass capacitor connected between the input terminal of the signal amplification element, a capacitor connected in parallel with the signal amplification element, and an output terminal of the signal amplification element connected to each other. The resonant circuit connected between the input terminals has a capacitance stabilizing capacitor connected in parallel with parallel heating electrodes that also serve as resonant capacitors, and a resonant capacitor connected in series with the parallel connected body. Connect the coil,
Furthermore, a high frequency decompression device is characterized in that it uses a composite resonant circuit in which an oscillation stabilizing capacitor is connected in parallel with the parallel connection body.