JP3425639B2 - Heat treatment device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hyperthermia treatment device, and more particularly to a thermotherapy device in which a pair of conductors are clamped between affected parts of a human body.
The present invention relates to a high-frequency thermotherapy device for generating high-frequency waves between the pair of conductors and performing hyperthermia treatment on the affected part. 2. Description of the Related Art A high-frequency thermotherapy device has a frequency of several MHz to several tens of MHz.
The high frequency band electromagnetic wave is transmitted through the affected part to dielectrically heat the affected part. Therefore, in order to carry out treatment efficiently with minimum power loss, it is necessary to match the output impedance of the high-frequency thermal treatment device with the impedance of the human body as a load. For this purpose, a matching circuit including a variable capacitor or the like is interposed between the main body of the high-frequency generator and the conductor as the output terminal. Although the matching circuit was initially a manually adjustable type, the impedance of the human body differs depending on each part, and even in the same part, it varies depending on the posture of the human body and the surrounding environment, so the manual matching operation is extremely complicated. is there. In view of this, there has been proposed a means for mounting a control unit for automatically operating a matching circuit, as disclosed in Japanese Patent Publication No. 3-26981. The control unit operates the matching circuit to change the output impedance by a fixed amount per unit time,
Automatically matches by detecting the load current and changing the output impedance further in the forward direction when the load current is increasing, and changing the output impedance in the reverse direction when the load current is decreasing. It is configured as follows. When the control means changes the output impedance by a fixed amount per unit time, if the change per unit time is reduced, it takes a long time to reach the matching point. On the other hand, when the amount of change per unit time is increased, the error with respect to the matching point increases. Therefore, in automatically controlling the output impedance, there arises a technical problem to be solved so that impedance matching can be performed promptly and with high accuracy. An object is to solve the problem. SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-mentioned problems, and has a matching circuit interposed between a high-frequency generating means and a pair of conductors. By detecting the load current of the matching circuit to determine the matching state, the thermotherapy device provided with control means for operating the matching circuit so that the output impedance matches the load impedance between the pair of conductors, The control means is
The load current value I flowing through the combined circuit is slightly larger than the minimum value I _min
Are previously stored as an absolute value deal of load current value I _o,
A region of the load current smaller than the absolute value is defined as a bottom region B.
In addition, if I ≧ _Io and one side of the matching point P stands,
The other side is defined as a falling area R, and the other side is defined as a falling area R.
The load current value I is intermittently detected at regular time intervals.
Ri, when the load current of the bottom region B, the control means operates the matching circuit so that the change rate of the output impedance is the upper limit, and, when the load current is rising regions or falling region; The control means is the load at the time
The current value I is compared with the load current value one interval before to determine the load current.
Whether the flow is in the rising region or the falling region
Discriminating and operating the matching circuit such that the output impedance changes in the increasing direction of the load current in any region, and the rate of change of the output impedance decreases with the increase of the load current. when is near match point, said means to operate said matching circuit to match with a very slow speed changes as much as possible the output impedance
There is provided a heat treatment apparatus comprising configured. The load current greatly deviates from the matching point, and
Where the area is smaller than the preset absolute value
When in the bottom region, the output impedance is changed at a maximum rate. Also, when the load current rises or falls
In some cases, the load current value at that time and the load one interval before
The load current is in the rising region compared to the current value or
It is determined whether the load current is in the falling area and the load current is in the rising area.
, The output impedance decelerates while changing in the forward direction. When the load current is in the falling area, the output impedance decelerates while changing in the opposite direction. Then, when the load current reaches the vicinity of the matching point, the amount of change in the output impedance per unit time becomes very small and reaches the matching point. Accordingly, the output impedance is promptly controlled toward the matching point, and the accuracy with respect to the matching point is improved as much as possible. An embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 shows a configuration diagram of a high-frequency thermotherapy device 1. A high-frequency generator 2 includes a high-frequency oscillation circuit, a resonance circuit, and a plurality of stages of amplifier circuits. The output is transmitted to the output connectors 5 and 5 via the power supply. Output connectors 5 and 5
Plastic conductors 6, 6 each having a copper net covered with an insulating cloth are extended. If the conductors 6, 6 are sandwiched between the affected parts of the human body, a high-frequency band electromagnetic wave having a frequency of several MHz to several tens of MHz is generated between the pair of conductors 6, 6 to dielectrically heat the affected parts. Healing by healing. In order to match the output impedance Z _O of the high-frequency thermotherapy device 1 with the load impedance Z _{L of the} affected part sandwiched by the conductors 6, the matching circuit 4 is used. Is mounted with a variable capacitor 7 having a built-in rotary movable electrode, and further provided with a control unit 8 for automatically controlling the rotation angle θ and the angular velocity ω of the movable electrode of the variable capacitor 7. The control unit 8 first detects a load current value I flowing through the matching circuit 4 by a current detector 9. The load current value I is rectified by the rectifier 10,
Further, it is smoothed by the capacitor 11. Further, after the value is adjusted by the variable resistor 12, it is digitally converted through the A / D converter 13, and
Is input to the CPU 14 which is the main body of the. The detection of the load current value I is performed intermittently at regular time intervals. The CPU 14 temporarily stores the intermittently detected load current value I in the memory 15 and determines the matching state to determine the motor rotation control circuit 16.
The rotation speed of the motor 17 is controlled via the
The impedance matching is performed by rotating the movable electrode of the variable capacitor 7. Here, the control of impedance matching by the control unit 8 will be described with reference to FIG. FIG. 5 shows the relationship between the rotation angle θ of the movable electrode of the variable capacitor 7 and the load current value I. Since the rotation angle θ every 360 ° is in a proportional relationship with the output impedance Z _O , the same figure can be regarded as an illustration of the relationship between the output impedance Z _O and the load current value I at the same time. When the movable electrode of the variable capacitor 7 is rotated for one cycle, the load current value I rises in a pulse shape in a predetermined angle region. Then, P point indicating the load current value I in the raised portion of the maximum value I _max is a matching point between the output impedance Z _O and the load impedance Z _L. Therefore, if the rotation angle θ of the movable electrode of the variable capacitor 7 is adjusted so that the load current value I becomes the maximum, the output impedance Z _O becomes equal to the load impedance Z.
_It is consistent with _L. The load current value I deviates greatly from the matching state at an angle other than the above-mentioned raised portion, and shows a substantially flat minimum value _Imin . Then, the CPU14 is a load current value corresponds to the vicinity of the base of said raised portion, a large load current value I _O slightly than the minimum value I _min is, is stored in advance as an absolute amount, I <of I _O region bottom region B, the left side of the I ≧ I _O a a by matching point P rises region L, the right I ≧ I _O a a by matching point P is set to fall region R, each region as described below A different process is performed according to. [0015] In Thus, the current detected by the detector 9 the load current value I is the bottom region B, that, when was I <I _O, the CPU14 is the angular velocity of the movable electrode of the variable capacitor 7 omega The motor rotation control circuit 16 is operated so that (= θ / t) becomes maximum (ω = ω _max ). During the operation, the load current value I is continuously detected at regular time intervals,
I <I _O a is as long as omega = omega _max rotation angle θ is varied. Thus, the load current value I, that is, the output impedance Z _O can reach the rising region L in a shortest time from a position largely deviating from the first matching point. When the CPU 14 enters the rising region L, the CPU 14 determines the load current value I (t = n) at that time and the load current value I (t = n−1) one interval before stored in the memory 15. , The gradient φ = Δ of the load current value I with respect to the rotation angle θ.
I / Δθ = (I (t = n) −I (t = n−1)) / (θ
(T = n) −θ (t = n−1)), and the smaller the gradient φ, the smaller the angular velocity ω. As shown in the figure, the slope φ ₂ on the side closer to the matching point than the slope φ ₁ on the base side
Is smaller, the angular velocity ω decreases as the load current value I increases and approaches the matching point P (ω ₂ <ω
₁ <ω _max ). Then, as the gradient φ approaches zero near the matching point P, the angular velocity ω also decreases as much as possible. Therefore, the alignment accuracy is improved as much as possible. On the other hand, if the first detected load current value I is I ≧
In the case of _IO , it cannot be determined at that time whether the vehicle is in the rising region L or the falling region R. Therefore, the second detection of the load current value is performed by changing the rotation angle θ in the forward direction by a predetermined amount. If the second value is larger than the first time, it is determined that the vehicle is in the rising area L, and the rotation angle θ is increased in the forward direction. If the second value is smaller than the first time, it is determined that the vehicle is in the falling region R and the direction is reversed, and the rotation angle θ is changed in the direction of decreasing, that is, in the direction of increasing the load current value I. As a result, even when in the falling area R, the matching point P is matched at the shortest distance. The subsequent control in the falling area R is the same as that in the above-described rising area L. The gradient φ decreases as indicated by arrows ω ₃ and ω ₄ in the figure, and approaches the matching point P. As the angular velocity ω decreases, the direction is reversed. Since the gradient φ approaches zero near the matching point P, the angular velocity ω also becomes as small as possible. Thus, when the load current value I is in the bottom region B, the output impedance Z _O is
Corresponding to the angular velocity omega _max of the movable electrode and quickly moved to the rising region L of, whereas, when the load current value I is in the rising region L or falling region R, the output impedance Z _O is the closer to the matching point P As the rate of change decreases, impedance matching is performed quickly and with high accuracy. In the present embodiment, in the rising region L and the falling region R, the load current value I with respect to the rotation angle θ is determined.
Is controlled using only the gradient φ as a parameter, the CPU 14 sets a theoretical value I _im of the load current value at the matching point P in advance in the CPU 14, and the theoretical value I _im and the detected load current value The difference from I may be controlled in addition to the parameter. In this embodiment, the impedance matching is performed by changing the rotation angle θ of the variable capacitor 7 by the motor 17, but as shown in FIG. 3, the fixed capacitors 18, 18,. 19, impedance matching may be performed by switching. Further, the present invention can make various modifications without departing from the spirit of the present invention, and
Naturally, the invention extends to such modifications. According to the present invention, as described in detail in the above-described embodiment, the control means controls the load current based on the absolute value set in advance.
In the bottom area, which is a smaller area, and greatly deviates from the matching point, the change rate of the output impedance is maximized to quickly approach the matching point, and the rising area or the falling area where the matching point has the maximum value is obtained. When it is in the area , the load current value at that time is compared with the load current one interval before.
If the load current is in the rising region or the falling region
The output impedance in each area.
Changes in the increasing direction of the load current, and the output
The rate of change of the impedance decreases as the load current increases.
The matching circuit is controlled in such a manner that the change rate of the output impedance is reduced as the position approaches the matching point. Therefore, impedance matching can be performed promptly and with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing one embodiment of the present invention. FIG. 2 is a graph illustrating a relationship between a rotation angle of a movable electrode of a variable capacitor and a load current. FIG. 3 is a circuit diagram showing another embodiment of the matching method. [Description of Signs] 1 High-frequency thermotherapy device 2 High-frequency generator 3 Balun 4 Matching circuit 5 Output connector 6 Conductor 7 Variable capacitor 8 Control unit 9 Current detector 14 CPU 15 Memory 16 Motor rotation control circuit 17 Motor θ Variable capacitor Rotational angle of movable electrode ω Rotational angular velocity of movable electrode of variable capacitor Z _O Output impedance Z _L Load impedance I Load current value P Matching point B Bottom region L Rise region R Fall region φ Gradient of load current value with respect to rotation angle

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-4879 (JP, A) JP-A-62-236564 (JP, A) JP-A-61-20563 (JP, A) 4878 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61N 1/40 A61N 5/04

Claims (1)

(57) [Claim 1] A matching circuit is interposed between a high-frequency generator and a pair of conductors, and a matching state is determined by detecting a load current of the matching circuit. Accordingly, in the thermal treatment apparatus provided with control means for operating the matching circuit so that the output impedance matches the load impedance between the pair of conductors, the control means determines that the load current value I flowing through the matching circuit is a minimum value.
From Ya I _min ゝlarge load current I _o in advance with absolute value
And stores the area of the load current smaller than the absolute value.
Bottom region B is defined, and if I ≧ _Io , the matching point
One side from P is a rising area L, and the other side is a falling area R
On the other hand, the load current value I is intermittent at regular time intervals.
When the load current is in the bottom region B, the control means operates the matching circuit so that the rate of change of the output impedance becomes an upper limit, and the load current rises or falls. In the case of the area, the control means
The load current value I at that time and the load current value one interval before are
The load current is in the rising region or falling
And operating the matching circuit so that the output impedance changes in the increasing direction of the load current and the rate of change of the output impedance decreases as the load current increases in any region. Further, when the load current is near the matching point, the means is configured to operate the matching circuit so that the output impedance changes as quickly as possible to perform matching.