JP2007010331A - Automatic controller for electron spin resonance measurement device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic controller for a continuous electron spin resonance measurement device capable of compensating the disturbance caused by the motion of a specimen and capable of stable measurement at the time of measuring the living specimen in a microwave resonator. <P>SOLUTION: The automatic matching controller of the electron spin resonance measurement device comprises the detection circuit D2 for envelope detecting the reflection signal partially branched from the transmission line connected with the resonator, the oscillator O3 for outputting the reference signal, the phase shifter 103 for phase regulating the inversion processed reference signal, the highpass filter circuit 105 connected to the behind of the phase shifter, the balanced modulator M2 for mixing the detection signal of the detection circuit and the reference signal passed through the highpass filter circuit, the integrator 104 for integrating the output of the balanced modulator, the phase compensation circuit 106 for operating for securing the margin of the phase regulation by the phase shifter, and the adder for sending the control signal by adding the reference signal to the output signal of the integrator. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an automatic control device for an electron spin resonance measuring apparatus, and more particularly to a biological sample stored in or close to a microwave resonator in a continuous wave electron spin resonance measuring apparatus. The present invention relates to an automatic control device that can compensate for disturbance caused by the movement of the sensor and stably perform electron spin resonance measurement.

  In general, the electron spin resonance (ESR) measurement method is a method for measuring atoms and molecules having unpaired electrons such as free radicals by using the motion of magnetic moment of electrons. Normally, electrons are included in pairs on the orbits of atoms or molecules, but on the outermost orbitals of transition metal ions and radicals, for example, when only one electron exists, this is an unpaired electron. It becomes.

  ESR has a wide range of application fields such as chemistry, physics, biology, and medicine. Recently, free radicals that occur naturally in the living body are thought to be related to cancer, aging, and the like, and have become a hot topic in the fields of medicine and biology. The ESR measurement can measure a free radical having an unpaired electron nondestructively, and is an effective method at the present stage.

  The ESR measurement apparatus mainly employs the pulse ESR method and the continuous wave ESR (CW-ESR) method, but the conventional CW-ESR method performs a magnetic field sweep with a constant microwave frequency. Therefore, it is based on the principle of measuring the ESR signal, and in order to further increase the sensitivity, the measurement is performed by applying magnetic field modulation.

  A schematic configuration of a conventional CW-ESR measuring apparatus is shown in FIG. The basic configuration for the ESR measurement in the CW-ESR measurement device includes an oscillator O1, a bridge C, an ESR resonance unit R, a phase sensitive detection (PSD) circuit 1, and an ESR resonance measurement control device 2. The ESR resonance resonance section R includes a resonator R1, a pair of DC magnetic field magnets R2, and a pair of modulation magnetic field coils R3. The oscillator O1 generates a measurement carrier wave such as a microwave. For example, 1.1 GHz is used as the oscillation frequency.

  In FIG. 1, the resonator R1 is placed above the modulation magnetic field coil R3, but at the time of measurement, the sample is disposed between the modulation magnetic field coils R3, and therefore the resonator R1 is a surface coil type. In some cases, the sample is in contact with or close to the sample, or in the case of a loop gap type, the sample is placed therein. The pair of DC magnetic field magnets R <b> 2 performs a magnetic field sweep by applying a DC magnetic field to the measurement site of the sample, and is driven by the DC power supply 5. The pair of modulation magnetic field coils R3 apply a modulation magnetic field in order to realize high-sensitivity measurement, and the power amplifier 6 power-amplifies and supplies the modulation signal of the oscillator O2.

  The bridge C includes a circulator therein, or may be configured by a directional coupler, a hybrid, or the like. Its role is to supply the microwave from the oscillator O1 to the resonator R1, and transmit the microwave reflected and amplitude-modulated by the resonator R1 to the PSD circuit 1. The PSD circuit 1 performs phase detection on the reflected microwave based on the modulation signal from the oscillator O2, and transmits the detection signal to the ESR resonance measurement control device 2. The ESR resonance measurement control device 2 controls the entire measurement system and performs measurement based on the detection signal.

  In the CW-ESR measuring apparatus configured as described above, a microwave having a constant frequency is transmitted to, for example, a loop gap resonator R1 having a one-turn coil via a coaxial cable, and is placed inside the sample. To be supplied. The reflected wave reflected from the resonator R1 on which the sample is placed is returned to the bridge C through the one-turn coil. At the time of measurement, the DC magnetic field coil R2 sweeps the magnetic field applied to the sample by DC, and the modulation magnetic field coil R3 generates a temporal change of the magnetic field.

  Next, an outline of the operation of the measurement apparatus will be described with reference to FIG. 2 showing a partial detailed configuration of the CW-ESR measurement apparatus. The modulation signal oscillated and output from the modulation oscillator O2 is supplied to the modulation magnetic field coil R3 through the power amplifier and also to the PSD circuit 1, where the phase, amplitude and DC component are adjusted. Is done. The microwave output from the oscillator O1 is branched into a main line microwave and a reference microwave by a distributor.

  The main line microwave is supplied to the bridge C. The main line microwave branched by the bridge C is guided to the resonator R1 through a one-turn coil, and supplied to the sample in the resonator R1. At this time, the distance between the one-turn coil and the resonator R1 is adjusted so that the reflection is minimized. The reflected wave reflected from the resonator R1 in which the sample is contained returns to the bridge C through the one-turn coil again. The reflected wave is amplified by the amplifier 7 and then supplied to the power combiner A1.

  On the other hand, the reference microwave distributed by the distributor is adjusted by the phase shifter 9 so as to be in phase with the reflected wave from the resonator R1, and supplied to the power combiner A1. Therefore, the power combiner A1 adds the reflected wave output from the bridge C and the reference microwave supplied from the phase shifter 9, and performs detection by the detection circuit D1. The detection output outputted from the detection circuit D1 is phase-detected by the PSD circuit 1. The ESR detection signal that is the output of the PSD circuit 1 is guided to a measurement control device 2 that includes a personal computer or the like. The measurement control device 2 controls the DC current supplied to the DC magnetic field magnet R2 and sweeps the DC magnetic field, thereby measuring the electron spin resonance based on the detected ESR detection signal.

  By the way, in the electron spin resonance measuring apparatus having the above-described configuration, various automatic control circuits are incorporated so that the electron spin resonance measurement can be stably performed. Typical examples of these automatic control circuits include an automatic frequency control circuit (AFC), an automatic tuning control circuit (ATC), and an automatic matching control circuit (AMC).

  Although an automatic frequency control circuit (AFC) is not shown in FIGS. 1 and 2, it has been proposed to tune the microwave frequency to the resonance frequency of the microwave resonator O1 (for example, Non-Patent Document 1). See). In this AFC, the oscillation frequency of the microwave oscillator O1 is automatically controlled so that the microwave frequency always matches the resonance frequency of the microwave resonator O1.

  In this automatic control, the frequency deviation is detected by introducing the output of the frequency-modulated microwave oscillator O1 into the reflection type resonator R1 and detecting the phase of the envelope of the reflected microwave signal. The oscillator O1 is subjected to negative feedback control according to this frequency shift. This automatic control can remove the influence of dispersion caused by the electron spin resonance phenomenon, and the amount of absorption can be measured accurately.

  Further, as shown in FIGS. 1 and 2, the automatic tuning control circuit (ATC) has been proposed to tune the resonance frequency of the microwave resonator R1 to the microwave frequency (for example, Non-Patent Document 2). See). According to this ATC, even if the sample moves, the resonance frequency of the microwave resonator R1 can be matched with the microwave frequency.

  In order to make the resonance frequency of the microwave resonator O1 coincide with the microwave frequency, this ATC system includes, for example, a microwave oscillator, a phase detection circuit, and an electromagnetic motor that takes a dielectric in and out of the gap portion of the resonator. By using it, negative feedback control can be realized. Alternatively, it can be realized by controlling the position of the dielectric plate using a piezoelectric actuator in addition to the electromagnetic motor.

  Further, as shown in FIGS. 1 and 2, an automatic matching control circuit (AMC) is usually proposed to match the input impedance of the microwave resonator R1 to the characteristic impedance of the transmission line, for example, 50Ω. (For example, see Non-Patent Document 3). According to this AMC, for example, when measuring a moving sample such as an animal, noise signals appearing in the spectrum due to the movement of the animal can be suppressed, and stable ESR measurement can be performed.

  In this AMC, a signal output from an oscillator incorporated in a lock-in amplifier is applied to a varactor diode connected to a microwave resonator, and a perturbation is given to impedance matching so that the reflected microwave is reflected. A voltage for controlling impedance matching is obtained by phase detection of the envelope.

  Furthermore, as another configuration of AMC, there has been proposed one that detects a shift in impedance matching by monitoring the phase of the microwave reflected by the resonator (for example, see Non-Patent Document 4). reference).

M. Alecci, S. J. McCallum, and D. J. Lurie, Design and Optimization of an Automatic Frequency Control System for a Radiofrequency Electron Paramagnetic Resonance Spectrometer, Journal of Magnetic Resonance Series A, Vol. A117, pp. 272-277 (1995) J. A. Brivati, A. D. Stevens, and M. C. R. Symons, A radiofrequency ESR spectrometer for in vivo imaging, Journal of Magnetic Resonance, Vol. 92, pp. 480-489 (2001) G. He, S. Petryakov, A. Samouilov, M. Chzhan, P. Kuppusamy, and JL Zweier, Development of a resonator with automatic tuning and coupling capability to minimize sample notion noise for in vivo EPR spectroscopy, Journal of Magnetic resonance, Vol. 149, pp. 218-227 H. Hirata, Y. Yamaguchi, T. Takahashi, and Z.-W. Luo, Control characteristics of automatic matching control system for in vivo EPR spectroscopy, Magnetic Resonance in Medicine, Vol. 50, pp. 223-227 (2003)

  However, in the above-described automatic matching control circuit (AMC), the phase margin of the control circuit is insufficient, and it may be difficult to stabilize as a feedback control system. Further, in the case of automatic matching control using a phase detection circuit, in order to realize negative feedback control, it is necessary to adjust the phase of the reference signal. In order to perform this phase adjustment, in particular, an operational amplifier When a one-stage phase shifter using is used, the variable range of the phase is limited to 180 degrees at the maximum. Therefore, this phase shifter has a problem that appropriate phase adjustment cannot be performed in the vicinity of both ends of the variable range.

  Further, in the phase detection circuit constituting the AMC, a DC component may be included in the reference signal input to the balanced modulator or the modulator by the multiplier. When this DC component is not zero, the switching duty ratio of the balanced modulator or the like does not become 50%. For this reason, the switching interval is biased, and there is a problem that the phase detection circuit cannot be operated intentionally.

  On the other hand, an automatic frequency control circuit (AFC) that controls the microwave frequency based on the reflected wave signal from the microwave resonator so that stable measurement can be performed in the conventionally used electron spin resonance measurement apparatus, And an automatic tuning control circuit (ATC) for controlling the resonance frequency of the microwave resonator. However, for example, when measuring by exchanging the resonator with another resonator, it may be necessary to select AFC and ATC.

  Therefore, when considering switching between AFC and ATC, both are automatically controlled based on the reflected wave signal from the microwave resonator, and the phase detection circuit can be shared. Since the objects are different, it is necessary to apply different bias voltages. Therefore, even if the phase detection circuit is shared, the bias voltage must be changed and readjusted every time the AFC and ATC are switched, which may prevent easy replacement of the resonator. there were.

  Accordingly, an object of the present invention is to provide an automatic control device for an electron spin resonance measuring apparatus that solves the above-described problems, and ensures a phase margin of the control circuit and stabilizes it as a feedback control system. The variable range of phase adjustment in the phase detection circuit used for AMC is set appropriately so that appropriate phase adjustment can be performed. The switching duty ratio in the balanced modulator of the phase detection circuit is maintained at 50%. Furthermore, switching between AFC and ATC can be easily performed without the need for bias voltage adjustment.

  In view of the above problems, in order to solve the problem, in the present invention, in an automatic control device for an electron spin resonance measurement device, a reflected wave signal partially branched from a transmission line connected to the electron spin resonance resonator is used. A detection circuit that detects an envelope, an oscillator that outputs a reference signal, a phase shifter that adjusts the phase of the reference signal that is phase-inverted or non-inverted, and a high-pass filter circuit that is connected after the phase shifter A balanced modulator that multiplies the detection signal of the detection circuit and the reference signal that has passed through the high-pass filter circuit, an integrator that integrates the output of the balanced modulator, and an output signal of the integrator And an adder for adding the reference signal, and based on the added output signal of the adder, the input impedance of the resonator is matched with the characteristic impedance of the transmission line.

  The high-pass filter circuit has a cutoff frequency around the frequency of the reference signal.

  Further, the phase shifter includes an operational amplifier having the reference signal as an input, the phase of the reference signal can be adjusted to a phase within a predetermined range, and a phase compensation circuit is interposed between the integrator and the adder. The phase compensation circuit is inserted and operated so as to ensure a phase margin of the feedback control system.

  The automatic control device includes: a phase detection circuit that detects a phase of the detection signal of the detection circuit based on a modulation signal; and a first adder that adds a first bias voltage to the output signal of the phase detection circuit. The automatic tuning control circuit includes an automatic tuning control circuit that performs automatic control for tuning the resonance frequency of the resonator to the frequency of the microwave supplied to the resonator.

  The automatic control device also includes a phase detection circuit for detecting a phase of the detection signal of the detection circuit based on a modulation signal, and a second bias voltage and the modulation signal added to the output signal of the phase detection circuit. An automatic frequency control circuit having an adder is included, and the automatic frequency control circuit performs automatic control for tuning the microwave frequency supplied to the resonator to the resonance frequency of the resonator.

  A phase detection circuit for detecting a phase of the detection signal of the detection circuit based on a modulation signal; a first adder for adding a first bias voltage to the output signal of the phase detection circuit; and an output signal of the phase detection circuit. A second adder for adding the second bias voltage and the modulation signal, and a switching circuit capable of switching and outputting the output signal of the phase detection circuit to the first adder and the second adder. .

  As described above, in the present invention, the automatic matching control circuit using the phase detection circuit is configured in the automatic control device of the electron spin resonance measuring apparatus, and immediately after the phase shifter in the phase detection circuit, near the modulation frequency. Since a high-pass filter circuit having a cut-off frequency is inserted, the phase of the phase shifter can be rotated extra. For this reason, it is not necessary to adjust the phase shifter at 0 degrees or around 180 degrees, and the phase adjustment can be performed within a range where the phase shifter can sufficiently operate.

  Furthermore, by inserting a high-pass filter circuit immediately after the phase shifter, even if a direct current component is included in the reference signal used for the phase detection circuit, this direct current component is generated by the inserted high-pass filter circuit. The duty ratio of switching in the mixer can be set to 50% without adjustment.

  Further, in the automatic matching control circuit used in the phase detection circuit, the phase compensator is inserted immediately after the integrator in the phase detection circuit, so that the phase margin of the feedback control system can be sufficiently secured, and the biological Even if the sample moves, disturbance due to the movement can be compensated, and the electron spin resonance measurement can be performed stably.

  In the automatic control apparatus for an electron spin resonance apparatus according to the present invention, a first adder for adding a first bias voltage to the output signal of the phase detection circuit, and a second bias voltage and the modulation to the output signal of the phase detection circuit. Independent of automatic frequency control and automatic tuning control because it has a second adder that adds signals and a switching circuit that can switch and output the output signal of the phase detection circuit to the first adder and the second adder Thus, a necessary bias voltage can be provided. Therefore, according to the switching by the switching circuit, it is possible to easily adjust the bias voltage when the control target of the automatic control is switched to the microwave oscillator or the microwave resonator.

  Next, an embodiment related to the automatic control device of the electron spin resonance measuring apparatus of the present invention will be described. Before that description, various automatic control devices serving as the basis of the present embodiment will be described with reference to FIGS. The description will be given with reference.

  FIG. 3 shows a configuration example of an automatic tuning control (ATC) circuit, and this ATC circuit corresponds to the ATC 3 shown in FIG. Components of the ATC circuit shown in FIG. 3 are denoted by the same reference numerals in the same parts as those shown in FIG. Although not shown in FIG. 2, as shown in FIG. 1, the ATC circuit of FIG. 3 has an oscillator O3 that supplies a modulation signal to the oscillator O1 in order to modulate the oscillation signal of the oscillator O1. Is provided. The frequency of this modulation signal is, for example, 20 kHz.

  The ATC circuit of FIG. 3 includes a detection circuit D2, a phase sensitive detection (PSD) circuit 10, and an adder A2. The detection circuit D2 is reflected by the microwave resonator R1 by the branching unit 8. A reflected wave signal is partially branched from the transmission path and input. The input reflected wave signal is envelope-detected by the detection circuit D 2 and output to the PSD circuit 10.

  The PSD circuit 10 is supplied with a modulation signal oscillated and output by the oscillator O3 as a reference signal. The PSD circuit 10 performs phase detection on the detection signal of the reflected wave signal input based on this reference signal. The output of the phase detection is a DC voltage corresponding to the magnitude of the phase shift. Here, in order to generate a control signal for controlling the tuning circuit provided in the resonator R1, the adder A2 adds the bias voltage Vb1 to the phase detection output. This bias voltage Vb1 serves as a reference voltage for driving the tuning circuit, and is set in accordance with the characteristics of the tuning circuit.

  Next, FIG. 4 shows a configuration example of an automatic frequency control (AFC) circuit, and this AFC circuit is usually provided as an automatic control device of an electron spin resonance measuring apparatus. Components of the AFC circuit shown in FIG. 4 are denoted by the same reference numerals as those shown in FIG. Although not shown in FIG. 2, the AFC circuit of FIG. 4 includes an oscillator O3 that supplies a modulation signal to the oscillator O1 as in the case of the ATC circuit shown in FIG. The frequency of this modulation signal is the same as that of the ATC circuit.

  The AFC circuit of FIG. 4 includes a detection circuit D2, a PSD circuit 10, and an adder A3. A reflected wave signal reflected by the microwave resonator R1 is transmitted to the detection circuit D2 by the branching unit 8. A part of the road is branched and input. The input reflected wave signal is envelope-detected by the detection circuit D 2 and output to the PSD circuit 10.

  The PSD circuit 10 is supplied with a modulation signal oscillated and output by the oscillator O3 as a reference signal. The PSD circuit 10 performs phase detection on the detection signal of the reflected wave signal input based on this reference signal. The output of the phase detection is a DC voltage corresponding to the magnitude of the phase shift. The signal processing so far is the same as the ATC circuit shown in FIG. Here, in order to create a control signal for controlling the oscillation frequency of the oscillator O1, the adder A3 inserted into the oscillation signal output of the oscillator O3 adds the phase detection output and the bias voltage Vb2 to the oscillation signal output of the oscillator O3. Is done. The bias voltage Vb2 is a voltage for adjusting the oscillation of the oscillator O1, and is set according to the characteristics of the oscillator O1.

  FIG. 5 shows a configuration example of an automatic matching control (AMC) circuit, and this AMC circuit corresponds to the AMC 4 shown in FIG. Components of the AMC circuit shown in FIG. 5 are denoted by the same reference numerals as those shown in FIG. Although not shown in FIG. 2, the AMC circuit of FIG. 5 includes an oscillator O4 that oscillates and outputs an AMC reference signal. The frequency of this reference signal is, for example, 3.5 kHz.

  The AMC circuit of FIG. 5 includes a phase detection circuit that uses the oscillation signal of the oscillator O4 as a reference signal at the output of the detection circuit D2. The phase detection circuit detects a phase shift in the reflected wave signal from the resonator R1, and controls to match the input impedance of the microwave resonator R1 with the characteristic impedance of the transmission line based on the detected output.

  As in the case of the ATC circuit and the AFC circuit described above, the reflected wave signal reflected by the microwave resonator R1 is partly branched from the transmission line by the branching device 8, and the branched reflected wave signal is detected by the detection circuit D2. The detected signal is amplified by the amplifier 101 as necessary, and then input to the phase detection circuit.

  Here, the phase detection circuit included in the AMC circuit includes a phase inverter 102, a phase shifter 103, an integrator 104, a balanced modulator M2, and an adder A4 as shown in FIG. A switching circuit 111 having a changeover switch is provided between the inverter 102 and the phase shifter 103. The integrator 104 may be a low-pass filter circuit, and the balanced modulator M2 may be a multiplier. The reference signal used for phase detection is supplied to the phase inverter 102 and the adder A4. The reference signal phase-inverted by the phase inverter 102 is input to the phase shifter 103 and phase-adjusted in the range of 0 degrees to 180 degrees. Here, the phase-adjusted reference signal is mixed with the aforementioned detection signal in the balanced modulator M2. Note that a non-inverted reference signal may be directly input from the oscillator O4 to the phase shifter 103 without phase inversion by the switching operation of the switching circuit 111.

  The output signal of the balanced modulator M2 is integrated and smoothed in the integrator 104, and added to the reference signal output from the oscillator O4 in the adder A4. This added signal is output to the impedance matching circuit provided in the resonator R1, and the impedance matching circuit is controlled based on the added signal, and the input impedance of the microwave resonator R1 matches the characteristic impedance of the transmission line. Is done.

  By the way, in the AMC circuit as described above, since the phase margin as the control circuit is insufficient, it may be difficult to stabilize the feedback control system in the electron spin resonance measuring apparatus. In order to realize negative feedback control, it is necessary to adjust the phase of the reference signal. In order to perform this phase adjustment, particularly when a one-stage phase shifter using an operational amplifier is used. The variable range of the phase is limited to 180 degrees at the maximum. For this reason, this phase shifter cannot perform appropriate phase adjustment near both ends of the variable range.

  In the AMC phase detection circuit, the reference signal input to the mixer may include a direct current component. When this DC component is not zero, the switching duty ratio of the balanced modulator or the like does not become 50%. For this reason, the switching interval is biased, and the phase detection circuit cannot be operated intentionally.

  Therefore, in the AMC circuit in the electron spin resonance measuring apparatus of this embodiment, as a solution to such a problem, a high-pass filter circuit is inserted between the phase shifter and the balanced modulator, and the integration is further performed. A phase compensator is inserted between the adder and the adder.

  FIG. 6 shows a configuration example of the AMC circuit according to the present embodiment. The configuration of the AMC circuit of this embodiment basically adopts the configuration of the AMC circuit shown in FIG. 5, and the AMC circuit shown in FIG. 6 is different from the AMC circuit shown in FIG. The same parts are denoted by the same reference numerals. The AMC circuit of the present embodiment is different from the AMC circuit of FIG. 5 in that a high-pass filter circuit 105 is inserted and connected between the phase shifter 103 and the balanced modulator M2, and is further added to the integrator 104. The phase compensator 106 is inserted and connected to the device A4.

  By the way, when the phase shifter having a single-stage configuration is configured using an operational amplifier, the variable range of the phase adjustment is limited to 0 degree to 180 degrees at the maximum. In this case, the phase adjustment may not be properly performed in the vicinity of 0 degrees and 180 degrees that are both ends of the variable range.

  The high-pass filter circuit 105 has a filter characteristic adjusted so as to have a cutoff frequency near the frequency of the reference signal. For example, the high-pass filter circuit 105 may be a filter circuit including a capacitor and a resistor. By connecting the high-pass filter circuit 105 after the phase shifter 103, the phase of the reference signal is rotated by an extra amount, for example, by an extra 45 degrees. For this reason, adjustment is not made near 0 degrees and 180 degrees at both ends in the variable range of the phase shifter 103, and operation at both ends can be avoided.

  Further, since the high-pass filter circuit 105 has a function as a low-frequency cutoff for the signal as a matter of course, when the reference signal input to the phase detection circuit includes a DC component, This DC component is blocked. For this reason, even when a DC component is generated due to an offset on the circuit, the DC component is blocked and adjustment of this offset is unnecessary. Since the high-pass filter circuit 105 is inserted and connected, the bias due to the direct current component is suppressed, so that the switching duty ratio in the balanced modulator M2 is maintained at 50% without requiring adjustment therefor. The intended operation as a phase detection circuit can be performed.

  Next, the phase compensator 106 inserted and connected between the integrator 104 and the adder A4 of the phase detection circuit in the AMC circuit of this embodiment will be described. The phase compensator 106 is inserted in order to ensure the phase margin of the feedback control system, and the configuration of the phase compensator may be any as long as the phase margin can be obtained. For example, a series connection body is formed by two resistors and a capacitor, the output of the integrator 104 is supplied to the series connection body, and a signal is extracted from the connection point of the two resistances. You can also.

  According to the phase compensator of this form, a signal having a voltage division ratio due to resistance is extracted on the high frequency side, and a signal higher than the voltage division ratio due to resistance is extracted on the low frequency side, so that a phase margin can be obtained. Become. In addition, it is not restricted to this form, It can comprise with an inductance instead of a capacitor | condenser, and various forms can be applied. This phase compensator can realize stable automatic matching control by being incorporated in an automatic control device of an electron spin resonance measuring apparatus.

  Next, another embodiment of the automatic control device of the electron spin resonance measuring apparatus will be described with reference to FIG. In an automatic control apparatus for an electron spin resonance measuring apparatus according to another embodiment, the ATC circuit shown in FIG. 3 and the AFC circuit shown in FIG. 4 are related.

  As described above, in the electron spin resonance measuring apparatus, the AFC circuit that controls the microwave frequency based on the reflected wave signal from the microwave resonator and the resonance of the microwave resonator so that the measurement can be performed stably. And an ATC circuit for controlling the frequency. However, for example, when measuring by exchanging the resonator with another resonator, it may be necessary to select AFC and ATC.

  Therefore, in the automatic control device of the electron spin resonance measuring apparatus of another embodiment, paying attention to the fact that the AFC circuit and the ATC circuit are configured by common circuit elements, the controlled objects of the AFC circuit and the ATC circuit are different. Therefore, the AFC circuit and the ATC circuit can be easily switched so that they can be selected and automatically controlled.

  As shown in FIGS. 3 and 4, both the AFC circuit and the ATC circuit are automatically controlled based on the reflected wave signal from the microwave resonator, and the phase detection circuit can be shared. . That is, it is common until a part of the reflected wave signal from the microwave resonator R1 is branched from the transmission line, the branched reflected wave signal is detected by envelope detection, and the detected signal is phase-detected.

  However, after the phase detection, the control target is the oscillator O1 in the AFC, whereas in the ATC, the control target is different depending on the tuning circuit provided in the microwave resonator R1, and therefore the phase detection. The bias voltage applied to the output of the circuit will also be different. Therefore, in the automatic control apparatus of the electron spin resonance measuring apparatus of another embodiment, even when the phase detection circuit is shared, it is not necessary to change the bias voltage every time the AFC and ATC are switched. A switching circuit is arranged so that easy replacement of the resonator is not hindered.

  FIG. 7 shows a switching configuration of a control circuit in an automatic control device of an electron spin resonance measuring apparatus according to another embodiment. In FIG. 7, since this switching configuration is mainly illustrated, other control configurations of the automatic control device are omitted. In the automatic control apparatus shown in FIG. 7, the oscillator O3, the phase sensitive detection (PSD) circuit 10, and the adder A2 constitute an ATC circuit. The oscillator O3, the PSD circuit 10, and the adder The AFC circuit is configured with A3, and the phase detection circuit is shared.

  The output of the PSD circuit 10 common to ATC and AFC is connected to the input terminal of the switching circuit 110. The switching circuit 110 has two output terminals, and switches and outputs a signal input to the input terminal to one of the output terminals based on, for example, an external control signal by an operator's manual operation. The input phase detection output is supplied to either the adder A2 or the adder A3.

  When the phase detection output of the phase detection circuit is supplied to the adder A2, the ATC circuit is activated and operates, or when the phase detection output is supplied to the adder A3, the AFC circuit Is enabled and works.

  With the above configuration, for example, when an automatic control device of an electron spin resonance measuring apparatus is provided with an AFC circuit, and when it is desired to add an ATC control function, it is necessary for the ATC control function. For the phase detection circuit, the AFC circuit can be shared between the AFC circuit and the ATC circuit by simply providing a simple switching circuit without separately providing an ATC circuit. Each time switching is performed, it is not necessary to adjust the bias voltage suitable for control.

It is a block diagram explaining schematic structure of the electron spin resonance measuring apparatus used as the foundation of the present invention. It is a block diagram explaining schematic structure of the automatic control circuit in an electron spin resonance measuring apparatus. FIG. 2 is a block diagram illustrating a specific example of an automatic tuning control circuit in the automatic control circuit shown in FIG. 1. It is a block diagram explaining the specific example of the automatic frequency control circuit in the automatic control circuit shown by FIG. It is a block diagram explaining the specific example of the automatic matching control circuit with which an electron spin resonance measuring apparatus is equipped. It is a block diagram explaining embodiment of the automatic matching control circuit with which the electron spin resonance measuring apparatus by this invention is equipped. It is a figure explaining the switching control circuit in the case of switching and operating an automatic tuning control circuit and an automatic frequency control circuit.

Explanation of symbols

1, 10 Phase sensitive detection circuit (PSD)
2 Electron spin resonance measurement controller 3 Automatic tuning control circuit (ATC)
4 Automatic matching control circuit (AMC)
DESCRIPTION OF SYMBOLS 5 DC power supply 6 Power amplifier 7, 101 Amplifier 8 Branch device 9 Phase shifter 102 Phase inverter 103 0-180 degree variable phase shifter 104 Integrator 105 High-pass filter circuit 106 Phase compensator 110, 111 Switching circuit A1- A4 adder C bridge D1, D2 detection circuit O1-O4 oscillator R1 microwave resonator R2 DC magnetic field magnet R3 modulation magnetic field coil M2 balanced modulator

Claims (6)

A detection circuit for detecting an envelope of a reflected wave signal partially branched from a transmission line connected to the electron spin resonance resonator;
An oscillator that outputs a reference signal;
A phase shifter for phase-adjusting the phase-inverted or non-inverted reference signal;
A high-pass filter circuit connected after the phase shifter;
A balanced modulator that multiplies the detection signal of the detection circuit by the reference signal that has passed through the high-pass filter circuit;
An integrator for integrating the output of the balanced modulator;
An adder for adding the reference signal to the output signal of the integrator,
An automatic control device for an electron spin resonance measuring apparatus, wherein an input impedance of the resonator is matched with a characteristic impedance of the transmission line based on an addition output signal of the adder.   2. The automatic control circuit for an electron spin resonance measuring apparatus according to claim 1, wherein the high-pass filter circuit has a cutoff frequency around a frequency of the reference signal. The phase shifter includes an operational amplifier that receives the reference signal, and can adjust the phase of the reference signal to a predetermined range of phase;
A phase compensation circuit is inserted between the integrator and the adder;
3. The automatic control circuit for an electron spin resonance measuring apparatus according to claim 1, wherein the phase compensation circuit operates so as to ensure a phase margin of a feedback control system. A phase detection circuit for detecting a phase of the detection signal of the detection circuit based on a modulation signal for automatic tuning control; and
An automatic tuning control circuit having a first adder for adding a first bias voltage to the output signal of the phase detection circuit;
4. The automatic tuning control circuit performs automatic control for tuning a resonance frequency of the resonator to a frequency of a microwave supplied to the resonator. 5. Automatic control circuit for electron spin resonance measurement equipment. A phase detection circuit for detecting a phase of the detection signal of the detection circuit based on a modulation signal for automatic frequency control; and
An automatic frequency control circuit having a second bias voltage and a second adder for adding the modulation signal to the output signal of the phase detection circuit;
5. The automatic frequency control circuit performs automatic control for tuning a microwave frequency supplied to the resonator to a resonance frequency of the resonator. 6. Automatic control circuit for electron spin resonance measuring device. A phase detection circuit for detecting a phase of a detection signal of the detection circuit based on a modulation signal;
A first adder for adding a first bias voltage to the output signal of the phase detection circuit;
A second adder for adding a second bias voltage and the modulation signal to the output signal of the phase detection circuit;
6. The automatic spin resonance measuring apparatus according to claim 4, further comprising a switching circuit capable of switching and outputting the output signal of the phase detection circuit to a first adder and a second adder. Control circuit.

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