JP2022051392A - Capacitor capacity measuring system and radiation dose measuring system - Google Patents

Abstract

To detect changes in capacitance from a distant location.SOLUTION: A capacitor capacity measuring system includes: a receiving side coil 14 that is placed at a predetermined distance from a transmitting side coil 10 and shares a magnetic field; a target coil CL3 placed between the transmitting side coil 10 and the receiving side coil 14; a capacitor C3 whose capacitance changes and which determines a resonance frequency of a resonance circuit 12 formed by connection of the capacitor C3 and the target coil CL3; and a resonance frequency detection unit (network analyzer 20) that analyzes the frequency of power transmitted from current flowing through the transmitting side coil 10 and the receiving side coil 14 and detects the resonance frequency of the resonance circuit from a phase change or loss of transmission power by resonance of the resonance circuit 12. The capacitance of the capacitor C3 is detected based on the detected resonance frequency.SELECTED DRAWING: Figure 2

Description

The present invention relates to a capacitor capacity measuring system for measuring the capacity of a capacitor by a phase change or loss of power transmission due to resonance of a resonance circuit, and a radiation amount measuring system using the same.

Conventionally, various sensors for detecting a change in the capacitance of a capacitor have been known. For example, many touch panels for inputting various data and motion sensors that detect changes in capacitance are used.

Here, Patent Document 1 discloses an inexpensive radiation dosimeter using only a capacitor and a coil by utilizing the fact that the capacitance of a capacitor changes according to the irradiation dose of radiation. Here, since an LC circuit in which a capacitor and a coil are connected in series has a frequency characteristic (resonance frequency) peculiar to the LC circuit, the peculiar frequency is analyzed by using an external antenna and a network analyzer. , Measure the change in capacitor capacity. Then, the irradiation dose of radiation is measured based on the change in the capacity of the capacitor. According to this system, an LC circuit can be embedded in the body and radiation dose measurement in the body can be performed using an external antenna and a network analyzer.

Japanese Patent No. 6512623

Kurs A, Karalis A, Moffatt R et al. Wireless power transfer via strongly coupled magnetic resonances. Science (80-) 2007; 317: 83-6

In Patent Document 1, the change in the capacitance of the capacitor can be detected at the position by using an antenna or the like arranged at a position away from the capacitor. However, if the distance between the antenna and the LC circuit increases, the detection accuracy deteriorates, and there is a possibility that sufficient measurement cannot be performed. On the other hand, considering the merit of being able to detect a change in capacitance in a non-contact manner, there is also a desire to detect it from a position as far away as possible.

In Non-Patent Document 1, as a wireless power transmission method, magnetic resonance (SCMR: Strongly Coupled Magnetic Resonance) is provided in a 4-coil configuration in which helical type coils (resonators) are installed in both transmission and reception coils. It is described that the high transmission efficiency S21 can be maintained even over a long distance by using it. The S parameter represents the relationship between the power entering the circuit and the power exiting the circuit (square root of power), and S21 is the transmission coefficient (= transmission efficiency) from the input terminal to the output terminal. be.

The present invention comprises a transmitting coil, a receiving coil that is arranged at a predetermined distance from the transmitting coil and shares a magnetic field generated by the transmitting coil, and a transmitting coil and a receiving coil. A target coil arranged between them, a capacitor whose capacitance changes, which determines the resonance frequency of a resonance circuit formed by being connected to the target coil, and flows through the transmitting side coil and the receiving side coil. The detected resonance includes a resonance frequency detection unit that analyzes the frequency dependence of the power transmitted from the current and detects the resonance frequency of the resonance circuit from the loss or phase change of the transmission power due to the resonance of the resonance circuit. The capacitance of the capacitor is detected based on the frequency.

The transmitting side coil is divided into a first coil and a second coil arranged close to each other, and the receiving side coil is divided into a fourth coil and a fifth coil arranged close to each other. By supplying a current to the first coil and detecting the current of the fifth coil, the power transmitted from the transmitting side coil to the receiving side coil may be frequency-analyzed.

The first coil and the fifth coil may be a one-turn coil, and the fourth coil and the fourth coil may be a plurality of winding coils.

The resonance frequency detection unit may detect the resonance frequency from the differential value of the transmission efficiency of the power transmitted from the transmitting side coil to the receiving side coil.

Further, the present invention is a radiation amount measuring system using the above-mentioned capacitor capacity measuring system, wherein the capacity of the capacitor changes depending on the dose of incident radiation, and the capacity of the capacitor detected by the resonance frequency detection unit is obtained. The amount of incident radiation is detected accordingly.

According to the present invention, for power transmission from the transmitting side coil to the receiving side coil, the capacitor capacity of the resonant circuit is detected by using the fact that a loss or a phase change occurs due to resonance of the resonant circuit. As a result, the capacitance can be detected even if the transmitting side coil and the receiving side coil are separated from the resonance circuit and the size of the resonance circuit is small.

It is a block diagram which shows the schematic structure of the capacitor capacity measurement system which concerns on this embodiment. It is a figure which shows the equivalent circuit of the capacitor capacity measurement system of FIG. It is a figure which shows the arrangement example of a coil. ) Is shown. It is a figure which shows the comparison result of the simulation (Simulation) and the actual measurement (measurement) of the transmission efficiency S21, (a) shows step1 and (b) shows step2. It is a figure showing the comparison result of the simulation and the actual measurement of the transmission efficiency S21 in Step 3, (a) shows the differentiation of S21, and (b) shows the differentiation of S21. It is a figure which shows S21 and its derivative when the magnetic field is strengthened and the measurement distance is increased, and is the case where (a) is 150 mm, (b) is 200 mm, and (c) is 250 mm. It is a figure which shows the structural example of a ferrite core, (a) shows only a ferrite core, and (b) shows the state where a coil is wound. It is a figure which shows the configuration example of the radiotherapy apparatus using the system of this embodiment. It is a figure which showed the configuration example which applied the capacitor capacity measurement system to the capacitance type touch panel.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described here.

"Outline configuration"
FIG. 1 is a block diagram showing a schematic configuration of a capacitor capacity measuring system according to the present embodiment.

The transmitting coil 10 has a first coil CL1 and a second coil CL2, which are two coils on the transmitting side. The resonant circuit 12 that functions as a sensor has a target coil CL3. The receiving side coil 14 has a fourth coil CL4 and a fifth coil CL5, which are two receiving side coils. A network analyzer 20 is connected to the first coil CL1 and the fifth coil CL5 as a resonance frequency detection unit. The network analyzer 20 supplies a signal of a desired frequency to the first coil CL1 and analyzes the signal received in the fifth coil CL5. The transmission side coil 10 and the reception side coil 14 may have one coil each or three or more coils. Further, as the first coil CL1 and the fifth coil CL5, a one-turn coil is suitable, and a plurality of winding coils are suitable for the others. Further, the resonance frequency detection unit may not perform frequency analysis like the network analyzer 20, but may detect the presence or absence of resonance at a predetermined frequency.

FIG. 2 shows an equivalent circuit of the capacitor capacity measurement system of FIG. Since the coil includes an electric resistance as well as an inductance, the inductance L and the resistance R are described separately in the equivalent circuit. Further, the capacitor C may include stray capacitance and the like.

The first coil CL1 is composed of an inductance L1 and a resistor R1 connected in series, to which a source resistance Rs and a capacitor C1 are further connected in series, and an AC signal is supplied from the network analyzer 20. The second coil CL2 is composed of an inductance L2 and a resistor R2 connected in series, to which a capacitor C2 is further connected in series, and an induced current flows according to the magnetic field generated by the first coil CL1.

The target coil CL3 is composed of an inductance L3 and a resistor R3 connected in series, to which a capacitor C3 is further connected in series, and an induced current flows according to the magnetic field generated by the second coil CL2. The fourth coil CL4 is composed of an inductance L4 and a resistor R4 connected in series, to which a capacitor C4 is further connected in series, and an induced current flows according to the magnetic field generated by the second coil CL2.

The fifth coil CL5 is composed of an inductance L5 and a resistor R5 connected in series, a capacitor C5 and a load resistance RL are further connected in series, and an induced current flows according to the magnetic field generated by the fourth coil CL4, and this current (voltage). Is measured by the network analyzer 20.

The resonance frequencies of the first, second, fourth and fifth coils CL1, CL2, CL4 and CL5 are set to be the same, whereby the first, second, fourth and fifth coils CL1, CL2, CL4 and CL5 Resonates at the resonance frequency, so that effective power transmission is performed.

Here, the source resistance Rs and the load resistance RL are for impedance matching with the network analyzer 20, and the capacitors C1, C2, C4, and C5 are the coils (CL1, CL2, CL4, and CL4) on the transmitting side and the receiving side. It is for setting the resonance frequency of CL5) to be the same, and it is preferable to use a variable capacitor.

In such a system, when an AC signal having a predetermined frequency is supplied to the first coil CL1 by the oscillator 20a of the network analyzer 20, a current flows through the second coil CL2 due to the magnetic field generated in the first coil CL1, and the second coil CL2 causes the current to flow. A current flows through the target coil CL3 and the fourth coil CL4 according to the generated magnetic field, a current flows through the fifth coil CL5 according to the magnetic field generated in the fourth coil CL4, and the current (voltage) of the fifth coil CL5 is generated. The network analyzer 20 detects it.

Here, a part of the induced current generated by the magnetic field of the second coil CL2 flows through the target coil CL3, and the induced current flows through the target coil CL3, so that the induced current flowing through the fourth coil CL4 decreases. Further, the resonance circuit 12 is composed of an LC circuit including a series connection of the target coil CL3 and the capacitor C3. Therefore, the resonant circuit 12 resonates at its natural resonant frequency, at which time a large current flows.

In the present embodiment, the network analyzer 20 detects the power transmission efficiency S21 of the first coil CL1 to the fifth coil CL5. Since S21 greatly decreases when the resonance circuit 12 resonates, the resonance frequency of the resonance circuit 12 (target coil CL3) is detected by detecting the frequency of this decrease peak (peak of transmission efficiency change). Therefore, the capacitance of the capacitor C3 can be measured.

Then, in the present embodiment, the capacitor C3 whose capacitance changes is adopted, and the capacitance of the capacitor C3 is measured by the network analyzer 20. As the capacitor C3, for example, the radiation dose can be measured by adopting a capacitor whose capacitance changes depending on the incident amount of radiation described in Patent Document 1.

The resonance frequency f of the resonance circuit 12 is f = 1 / 2π√ (L3 ・ C3), and when the frequency of the transmitted signal matches this resonance frequency, a resonance current flows in the resonance circuit 12, and here. The amount of current flowing through the frequency increases. In this case, the current flowing through the 4th coil CL4 and the 5th coil CL5 becomes small, and by detecting this decrease in the network analyzer 20, the resonance frequency of the resonance circuit 12 can be detected, and the capacitance of the capacitor C3 can be determined from this. Can be decided. Then, the amount of radiation incident can be known from the capacitance of the capacitor C3.

In the present embodiment, the network analyzer 20 sweeps the supplied AC signal at a frequency close to the resonance frequency of each coil, and detects the resonance frequency of the resonance circuit 12.

"Calculation of mutual induction current"
When two coils are electromagnetically coupled, a phenomenon (mutual induction) in which the currents flowing through the two coils affect each other occurs. When a current is passed through one coil by mutual induction, an induced electromotive force of V2 is generated in the other nearby coil by the magnetic field generated from that one coil.

Here, I ₁ is the current of one coil, t is the time, and M is the mutual inductance. When the distance between the coils is d ₁₂ , the radii of the two coils are r ₁ , r ₂ , and the number of turns is N ₁ , N ₂ , the mutual inductance M ₁₂ between one coil and the other coil is the first type. Using the elliptic integral K (k) and the second kind perfect elliptic integral E (k), it can be obtained as follows.

Further, since mutual induction interferes with not only adjacent coils but all coils, the relationship of voltage V, current I, and impedance Z in each coil is expressed as follows.

Here, M is the mutual inductance, Vs is the voltage applied to the first coil CL1, _VL is the voltage applied to the fifth coil CL5, and Vs is the voltage applied to the source resistance Rs. In addition, Vs may be a voltage applied to the source resistance Rs, and _VL may be a voltage applied to the resistance RL.

Since the respective current values (I ₁ to I ₅ ) can be calculated by solving the inverse matrix of the above formula, the transmission efficiency S21 can be calculated by the following formula.

Here, in the network analyzer 20, since the transmission efficiency S21 is expressed in decibels, the obtained S21 is substituted into the following equation, and the S21 _{Nwrwork Analyzer} is obtained. The following offset is an attenuation correction term by the internal attenuator of the network analyzer, and is obtained by actual measurement.

"Measurement of resonance frequency"
According to Faraday's law, when a coil is placed in a space where a magnetic field exists, an induced electromotive force is generated by a change in magnetic flux penetrating the loop surface. At this time, if the number of turns of the coil is N, the magnetic flux penetrating the coil is Φ, and the time is t, the induced electromotive force V is expressed by the following equation.

Further, since the coil is equivalent to the RLC series circuit, the impedance is expressed by the following equation, the impedance Z becomes the minimum value R at the resonance frequency, and the induced current due to the induced electromotive force becomes the maximum. That is, when the frequency of the electromagnetic wave penetrating the loop surface of the coil matches the natural resonance frequency of the coil, the induced current becomes maximum.

Therefore, the energy U stored in the coil by the induced current can be expressed by the following equation using the current I flowing through the coil.

From the above, when the target coil is placed in the space where power transmission is performed, the impedance becomes small near the resonance frequency of the target coil, and a part of the transmitted power is stored in the target coil for transmission. It is considered that a phase change occurs in the efficiency S21.

Further, since the impedance of the coil is the minimum at the resonance frequency, when the transmission efficiency S21 is observed with the network analyzer 20, the phase change that becomes the maximum at the resonance frequency of the target coil appears, and the power loss is caused by the resistance in the circuit. Occurs. Therefore, the phase change can be detected as a change in transmission efficiency (power loss), and can be similarly detected by, for example, measuring the standing wave ratio (SWR value).

In this way, the transmission efficiency S21 fluctuates depending on the frequency, and when the frequency of the signal to be transmitted matches the resonance frequency of the target coil CL3, which is the target coil, the transmission efficiency is greatly reduced. It becomes possible to detect the resonance frequency of (target coil CL3) from the outside. That is, in the network analyzer 20, the transmission frequency is swept, the transmission efficiency S21 at each frequency is obtained, and the frequency at which the transmission efficiency S21 drops can be specified as the resonance frequency of the resonance circuit 12 (target coil CL3).

"Experiment: Simulation, actual measurement"
The measurement of the resonance frequency in the present embodiment using the transmission efficiency S21 is validated step by step from a simple measurement system (Step1 → Step2 → Step3), so that the measurement of the resonance frequency using the transmission efficiency S21 is appropriate. I confirmed the sex.

For this measurement, a keysight company (trade name: E5071C) was used as the network analyzer.

<Step1>
As shown in FIG. 3A, the transmission efficiency S21 is measured when the resonance circuit 12 including the target coil CL3 which is the target does not exist and the distance between the second and fourth coils is relatively short (100 mm). do.

<Step2>
In the same measurement system as in FIG. 3A, as shown in FIG. 3B, the target coil CL3 (diameter: 18 mm, number of turns:) is located at an intermediate position (communication distance 50 mm) between the second coil CL2 and the fourth coil CL4. (4 times, length: 8 mm) is arranged, and it is verified whether a phase change occurs at the resonance frequency of the resonance circuit 12 including the target coil CL3 in the transmission efficiency S21.

<Step3>
In Step 3, the target coil CL3 was changed to a small coil (diameter 2.4 mm, number of turns 8 times, length 10 mm). Further, a ferrite core (diameter 2 mm, length 15 mm) was inserted as the core of the target coil CL3. The target communication distance was 100 mm, and frequency measurement was performed using the system shown in FIG. 3 (c).

Since the phase change of the transmission power in the resonance circuit 12 depends on the induced electromotive force, it is considered that the larger the mutual inductance M, the larger the peak of the phase change. Mutual inductance is a parameter that depends on the distance and radius between the coils, and can be calculated by simulation using the above equation. Therefore, the radius for increasing the mutual inductance M at a communication distance of 100 mm is determined to be 90 mm. Further, since the phase change peak due to the target coil CL3 is expected to become smaller as the target communication distance becomes longer, the phase change peak may not appear clearly. Therefore, by differentiating the obtained S21 [dB] with respect to the frequency (horizontal axis), it was devised so that it could be detected as a clear signal.

The resonance frequencies of the resonance circuits 12 used in Step 2 and Step 3 were measured in advance using the RFID principle, and those of 21.52 MHz and 17.68 MHz were used, respectively.

"Experimental result"
<Step1, Step2>
4 (a) and 4 (b) show the comparison results of the simulation and the measurement of the respective transmission efficiencies S21. As can be seen from FIG. 3A, the results of the simulation and the actual measurement are almost the same. It is presumed that the slight deviation between the simulation and the actual measurement is due to the fact that each coil is handmade and the slight deviation of the coils arranged in the actual measurement.

Further, by comparing FIG. 3A and FIG. 3B, it can be confirmed that a phase change peak occurs in the transmission efficiency S21 at the resonance frequency of the resonance circuit 12 including the target coil CL3. From the above, it can be seen that the frequency can be wirelessly measured by using the peak of the phase change portion.

<Step3>
FIG. 5A shows a comparison result between the simulation and the actual measurement of the transmission efficiency S21 in step3. In this way, as the distance increases, it becomes difficult to see the peak of the phase change portion. Therefore, FIG. 5B shows the transmission efficiency S21 differentiated by frequency.

As can be seen from FIGS. 5 (a) and 5 (b), the simulation and the actual measurement are in good agreement even when the target distance is extended, and the target is targeted even when the communication distance is longer than that of FIG. 5 (b). It was confirmed that the phase change occurred at the resonance frequency of the coil CL3.

It was also confirmed that the resonance frequency of the target coil CL3, which was separately measured in advance, matches the frequency at which the peak of the phase change occurs. Therefore, it was found that the resonance frequency can be measured even when the measurement distance is long by using the small resonance circuit 12 by combining the power transmission by SCMR and the phase change generated in the transmission efficiency S21.

"Extension of measurement distance"
6 (a) to 6 (c) show that for the first, second, fourth, and fifth coils CL1 to CL5, the magnetic field generated by using a large coil is strengthened, and the measurement distances are 150 mm, 200 mm, and 250 mm. The result (differentiation of S21 and S21 with respect to frequency) is shown. According to this, the phase change peak becomes smaller as the distance increases due to the differential value of S21 in the lower row, but if the measurement distance is about this level, it can be sufficiently identified by differentiating the transmission efficiency S21. I understand.

Further, in the present embodiment, a ferrite core is used for the target coil CL3 in order to extend the communication distance. On the other hand, a ferrite core can also be used for other coils such as CL2 and CL4. By using a ferrite core, the magnitude of the magnetic field between the coils becomes large, so that the communicable distance can be further extended.

<Shape of ferrite core>
In step 3 described above, a cylindrical ferrite core was used, and a coil was wound around the ferrite core. Here, as shown in FIGS. 7 (a) and 7 (b), both ends of the cylindrical ferrite core 30 in the axial direction are expanded in a conical shape to form a tapered portion 32 having a gradually increasing diameter. be able to. Then, by winding the coil 34 around the cylindrical portion, it is possible to suppress the movement of the coil 34 in the ferrite core 30 in the axial direction. When the target coil CL3 is embedded in the body, the movement of the coil is suppressed, so that more reliable detection can be performed.

<System configuration>
FIG. 8 shows a configuration example of a radiotherapy apparatus using the system of this embodiment. A patient 42 is placed on the examination table 40, and the affected portion of the patient 42 is irradiated with the therapeutic radiation 44. A resonance circuit 12 (target coil CL3) is embedded in a predetermined position of the patient 42. Thereby, the incident radiation dose at the place where the resonance circuit 12 is placed can be detected by the capacitance change of the capacitor C3 of the resonance circuit 12.

Here, the target coil CL3 of the present embodiment is a cylindrical helical coil and has good sensitivity to a magnetic field coming from its central axis direction (a large induced current is generated), but the closer it is to a direction orthogonal to this, the more sensitive it is. Is bad.

Therefore, as shown by the solid line in FIG. 11, when the directions of the target coil CL3 and the directions of the coils of the transmitting side coil 10 and the receiving side coil 14 are aligned, the sensitivity is good, and when they are different as shown by the broken line. The sensitivity becomes worse.

Therefore, it is preferable to make both or one of the examination table 40 on which the patient 42 is placed and the transmission / reception side coils 10 and 14 movable. As a result, it is possible to maintain a good sensitivity at all times, and high-sensitivity measurement becomes possible. When irradiating a patient with therapeutic radiation, it is often necessary to set the position of the examination table 40 in order to determine the irradiation position of the therapeutic radiation, and the orientation of the transmitting side coil 10 and the receiving side coil 14. Should be adjustable. The orientation of the target coil CL3 may be detected from the sensitivity, but may also be detected from an X-ray or ultrasonic image.

"Other configuration examples"
FIG. 9 is a diagram showing a configuration example in which a capacitor capacity measuring system is applied to a capacitance type touch panel. As described above, the metal plate 36 is connected to the resonance circuit 12, and the capacitance of the resonance circuit 12 changes depending on the proximity of the metal plate 36 to the metal plate 36. That is, in addition to the capacitor C3, the stray capacitance in the metal plate 36 is added, and this changes depending on the proximity of the hand or the like. If the capacitance of the resonance circuit 12 changes, it is not always necessary to provide the independent metal plate 36.

In the network analyzer 20, a predetermined signal is transmitted from the transmitting side coil 10, the received signal of the receiving side coil 14 is analyzed, and the change of the resonance frequency in the resonance circuit 12 is obtained from the phase change peak position (frequency) of the transmission efficiency S21. Can be detected. By shifting the resonance frequency of each resonance circuit 12 by a method such as changing the capacitance of the capacitor C3 of each resonance circuit 12, the resonance circuit 12 in which the resonance frequency has changed can be specified.

In addition, when there is a request to remotely detect a change in capacitance, the system of this embodiment can be adopted. In an element (capacitor) using a piezoelectric body, a pyroelectric body, or a ferroelectric body, the system of the present embodiment can be adopted when detecting a change in capacitance thereof.

Further, by connecting a capacitor, a coil, and a switch in series, an antenna having a resonance frequency can be generated only when the switch is pressed. By preparing a large number of similar capacitors, coils, and switches and setting their resonance frequencies to different values, it is possible to detect the on / off of the switch because a specific resonance frequency exists. Therefore, it is possible to function as a keyboard of a personal computer simply by arranging a switch containing a coil and a capacitor in the space without supplying power. In this case, on / off can be detected by detecting whether or not a resonance signal exists at a predetermined frequency for each switch, so that it is not necessary to perform frequency analysis using a network analyzer or the like.

"Effect of embodiment"
Currently, wireless communication technology is utilized in various fields, and the resonance frequency of the target coil is usually measured by S11 using electromagnetic induction. However, in the frequency measurement using S11, the communicable distance is short, and even a long one is about several centimeters.

In the present embodiment, the resonance frequency of the target coil 10 cm away can be measured by the method of detecting the phase change in the induced electromotive force in the target coil based on the power transmission by SCMR. It was also found that the resonance frequency can be measured over a long distance even with a small target coil.

Further, SCMR is a transmission method using magnetic field resonance, and it has been confirmed that the influence from a dielectric such as a living body is small and the transmission efficiency hardly changes. Therefore, it is considered that the resonance circuit 12 can be used as an internal sensor as it is, and there is a possibility that the problems related to the existing internal implantable device can be improved.

In Step 3 described above, the coil radius, etc., at which a measurement suitable for a measurement distance of 100 mm is performed was verified, but the distance can be further extended by strict optimization (coil winding number, coil pitch, resonance frequency band, etc.). It is thought that it can be done.

10 Transmitter coil, 12 Target coil, 14 Receiver coil, 20 Network analyzer, 30 Ferrite core, 32 Tapered part, 34 Coil, 36 Metal plate, 40 Examination table, 42 Patient, 44 Treatment radiation.

Claims (5)

With the transmitting coil
A receiving coil that is arranged at a predetermined distance from the transmitting coil and shares a magnetic field generated by the transmitting coil.
A target coil arranged between the transmitting side coil and the receiving side coil,
A capacitor whose capacitance changes and which determines the resonance frequency of a resonance circuit formed by being connected to the target coil.
Resonance that analyzes the frequency dependence of the power transmitted from the current flowing through the transmitting side coil and the receiving side coil, and detects the resonance frequency of the resonance circuit from the phase change or loss of the transmission power due to the resonance of the resonance circuit. Frequency detector and
Including
The capacitance of the capacitor is detected based on the detected resonance frequency.
Capacitor capacity measurement system. The capacitor capacity measuring system according to claim 1.
The transmitting side coil is divided into a first coil and a second coil arranged close to each other, and the receiving side coil is divided into a fourth coil and a fifth coil arranged close to each other. By supplying a current to the first coil and detecting the current of the fifth coil, the power transmitted from the transmitting side coil to the receiving side coil is frequency-analyzed.
Capacitor capacity measurement system. The capacitor capacity measuring system according to claim 2.
The first coil and the fifth coil are one-turn coils, and the fourth coil and the fourth coil are multiple-turn coils.
Capacitor capacity measurement system. The capacitor capacity measuring system according to any one of claims 1 to 3.
The resonance frequency detection unit is
The resonance frequency is detected from the differential value of the transmission efficiency of the electric power transmitted from the transmitting side coil to the receiving side coil.
Capacitor capacity measurement system. A radiation dose measurement system using the capacitor capacity measurement system according to any one of claims 1 to 4.
The capacity of the capacitor changes depending on the dose of incident radiation,
A radiation dose measurement system that detects the incident radiation dose according to the capacity of the capacitor detected by the resonance frequency detection unit.

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