JP2565497Y2 - Power supply circuit for thermal treatment - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency heat treatment apparatus for heating and treating a living body with electromagnetic waves, and more particularly to a power matching circuit used in a high-frequency heat treatment apparatus.

[0002]

2. Description of the Related Art Conventionally, for example, a circuit as shown in FIG. 3 has been used as a circuit for supplying high frequency power to an applicator. This circuit forms a balanced output type matching circuit,
A variable capacitor VC ₁₃ and the coil L ₁₁ receives the unbalanced input power, a high frequency transformer T that converts the imbalance power to a balanced signal, the variable capacitor VC ₁₁ interlocking connected to the secondary side of the high-frequency transformer T, It is composed of a VC _12. The output power of this circuit is supplied to an applicator AP for high-frequency hyperthermia.

In the power supply circuit having the above circuit configuration,
To supply a maximum power to the applicator AP, it is necessary to take the matching of the so-called circuit, in this circuit by varying the interlock variable capacitor VC _11, VC _12, to cancel the imaginary components of the applicator AP mainly , by changing the variable capacitor VC _13, we are taking the integrity of the real component of the applicator AP. Then, the value of the variable capacitor VC _11, VC ₁₂ interlocked is constantly changing with the same capacitance value.

[0004]

However, if different electrodes are used for the two electrodes AP ₁ and AP ₂ in the circuit as described above, a current difference occurs between the two power supply lines, and the circuit is connected to peripheral devices. This can have adverse effects and can cause high-frequency electric shock to patients and equipment operators. For this reason, it is necessary to balance the current of the feeder line separately from the matching adjustment for supplying the maximum power.

However, the aforementioned conventional interlocked variable capacitor (VC _11, VC _12), since the two capacitors change while maintaining the same capacitance value, adjusting the two feeder current averagely is can not, after all, another two variable capacitors operate independently, even could only achieve adjustment by changing the capacitance respectively interlocked variable capacitor VC _11, VC ₁₂ times and connected in series. This adjustment is extremely complicated and takes a long time, for example, when trying to balance the currents of both power supply lines, the matching condition of the circuit is broken.

The present invention has been made in view of this problem, and has as its object to provide a circuit which does not significantly affect the matching state and easily realizes the balance correction of the feed line. I do.

[0007]

In order to achieve the above object, the present invention provides a circuit for receiving high-frequency power and supplying the same to an applicator, wherein the two capacitance values always change at the same value. In the thermotherapy power supply circuit that performs matching adjustment using one interlocking variable capacitor, when one of the electrostatic capacitance values increases, the other interlocking variable capacitor decreases by the increased amount. , At the power output to the applicator.

[0008]

Since the second interlocking variable capacitors are interlocked in an inverted relationship with each other, the capacity of the other capacitor is reduced by an increase in the capacity of one capacitor. Therefore, even if the second interlocking variable capacitor is changed after the matching with the first interlocking variable capacitor, the matching state is not affected so much. it can.

[0009]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. This circuit comprises a balun 1 for converting an unbalanced signal P _i into a balanced signal, a first interlocking variable capacitor 2 (VC1, VC2) provided on the output side of the balun 1,
The second interlocking variable capacitor 3 (VC3, V3) is connected between the interlocking variable capacitor 2 and the load (applicator) 4.
C4).

Here, the first linked variable capacitor 2 (V
C1, VC2) are ordinary linked variable capacitors, and when the movable piece of the capacitor is moved, the capacitance of the two capacitors changes while maintaining the same value. On the other hand, when the movable piece of this capacitor is moved, the second interlocking variable capacitor 3 (VC3, VC4)
The capacitance of C3) increases, and the capacitance of the other capacitor (for example, VC4) decreases by an amount corresponding to the increase in the capacitance of one capacitor (VC3). The balun 1 is
Although not particularly limited, for example, the circuit shown in FIG. 3 corresponds thereto. The input side of the balun 1 is connected to a high-frequency power oscillating unit (not shown).

This circuit also adjusts the matching to supply the maximum power to the applicator 4.
_{When -1} and _4-2 are heterogeneous electrodes, for example, it is necessary to correct the balance of the feed line. Hereinafter, the adjustment procedure will be described. First, the first interlocking variable capacitors 2 (VC1, VC2) are adjusted to adjust the matching between the high-frequency power oscillating unit (not shown) and the applicator unit 4. Then, the second interlocking variable capacitor 3 (VC3, VC4) is adjusted to adjust the balance of both power supply lines, thereby removing or suppressing the common mode current. Here, in the second interlocking variable capacitor 3, since the sum of the capacitance values of the two capacitors is always constant,
Even if the movable piece of the capacitor is changed to change the capacitance of each capacitor, the matching state is hardly affected. Therefore, for example, even during application of high-frequency power, balance correction can be performed safely without concern for reflected waves. Further, unlike the related art, there is no need to separately adjust individual capacitors. Then, after suppressing the common-mode current, there is no fear of adverse effects on peripheral devices or high-frequency electric shock to patients and the like. Although the movement of the capacitor in the above description can be automated, also in this case, the adjustment of the capacitor is easy, the software is simple, and the time required for the adjustment is short.

FIG. 2 is a circuit diagram showing another embodiment of the present invention. The difference from the circuit of FIG. 2 is that the second interlocking variable capacitors 3 (VC3, VC4) are connected in parallel to the first interlocking variable capacitors 2 (VC1, VC2). The circuit operation and adjustment method are the same as those in FIG.

[0013]

[Effects of the Invention] As described above, in the present invention, an interlocking variable capacitor is provided, which is interlocked in a mutually inverted relationship.
As a result, the common-mode current is controlled and suppressed, so that adjustment is easy. Further, as described above, the balance can be safely corrected without concern for the reflected wave, and the operation can be easily automated.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit diagram showing an example of a conventional balanced output type matching circuit.

[Explanation of symbols]

 2 (VC1, VC2) First linked variable capacitor 3 (VC3, VC4) Second linked variable capacitor 4 Load (applicator)

Claims (1)

(57) [Scope of request for utility model registration] A circuit for receiving high-frequency power and supplying the same to an applicator, wherein the power for thermotherapy is adjusted by using a first interlocking variable capacitor whose two capacitance values always change at the same value. In the supply circuit, a second interlocking variable capacitor in which when one capacitance value increases, the other capacitance value decreases by the increase, is provided at a power output unit to the applicator. Power supply circuit for thermal treatment.