JP2002365354A - Magnetic resonance equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic resonance equipment which will not be influenced by magnetic field delay of an electromagnet, even if quick magnetic field sweeps are made. SOLUTION: This equipment comprises a high frequency oscillator, a high-frequency resonator capable of setting a measurement sample in the inner part and resonating a radio frequency supplied from the radio frequency oscillator, a magnetic field generating means for applying a magnetic field to the resonator, and a magnetic field sweeping means. In this device, high-frequency is resonated to the radio frequency resonator in the state where the measuring sample is set in the resonator, and a sweeping magnetic field is applied simultaneously to the resonator to detect a high-frequency spectrum, which is then converted to digital data by use of an A/D converter to acquire the high-frequency spectrum; and the sampling interval of the A/D converter is controlled interlocked with the actual intensity change of the sweeping magnetic field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic resonance apparatus such as an electron spin resonance (ESR) apparatus and a nuclear magnetic resonance (NMR) apparatus, and more particularly, to a method in which a delay in a sweep magnetic field is not directly reflected on measurement data. The present invention relates to a magnetic resonance apparatus capable of performing a magnetic resonance measurement.

[0002]

2. Description of the Related Art Normally, an ESR apparatus irradiates a sample with a fixed microwave frequency and, at the same time, sweeps the strength of a magnetic field applied to the sample. A microwave absorption spectrum with the microwave absorption amount on the axis is measured. FIG. 1 shows a conceptual diagram of the ESR device in order to understand the entire configuration of the ESR device.

In FIG. 1, reference numeral 1 denotes a host computer for controlling the entire ESR apparatus. When the measurer sets measurement conditions in the host computer 1, the host computer 1 controls the spectrometer 2 to supply a microwave to the cavity 3 in which the sample is set. And a control signal to the pair of electromagnets 5 for applying a main magnetic field to the cavity resonator 3 to control the entire ESR apparatus under predetermined conditions.

The ESR spectrum is detected as a microwave absorption spectrum in the spectrometer 2 by sweeping the magnetic field strength of the electromagnet 5 while supplying the microwave to the cavity resonator 3. During the magnetic field sweep, this ESR
The spectrum data is converted into a digital signal by the A / D converter 6 based on a sampling clock signal oscillating at a constant cycle, and is recorded in a storage unit such as a memory or a hard disk of the host computer 1. Displayed above.

Although not shown in FIG. 1, the electromagnet 5 is controlled by feedback control using a Hall element for converting the intensity of the magnetic field generated by the electromagnet 5 into a voltage value as a magnetic field detector. I have. That is, from the magnetic field setting unit of the spectrometer 2, the voltage value corresponding to the magnetic field strength to be set is
The voltage is output to the power supply for the electromagnet via the error amplifier, and the intensity of the magnetic field generated by the electromagnet 5 is converted into a voltage value by the Hall element. The converted voltage value and the voltage output by the magnetic field setting unit of the spectrometer 2 The value is fed back to the electromagnet power supply via an error amplifier to control the amount of current flowing through the electromagnet 5 so that the values become equal to each other.

FIG. 2A shows a magnetic field control signal at the time of ESR spectrum measurement, FIG. 2B shows an A / D converter sampling clock, and FIG. 2C shows an ESR spectrum. First, a magnetic field sweep signal is set based on a preset magnetic field sweep time and a value of a magnetic field sweep width, and the magnetic field strength of the electromagnet is linearly controlled. Next, at the start of the sweep, a sampling clock having a predetermined cycle determined by the number of sampling data and the magnetic field sweep time is generated at a constant time interval toward the A / D converter. This sampling
The signal digitized by the A / D converter based on the clock is stored in a storage device such as a memory, and becomes an ESR spectrum. The ESR spectrum obtained in this manner is generally represented by the relationship between the signal strength (vertical axis) and the magnetic field strength (horizontal axis).

When measuring the ESR spectrum, the sweep magnetic field is modulated in order to enhance the detection sensitivity, and the ESR spectrum is extracted as a modulation signal of a predetermined frequency. Therefore, the obtained ESR spectrum (microwave absorption spectrum) Usually has a first-order differential waveform as shown in FIG.

[0008]

However, in general, even if a control signal is sent from the spectrometer 2 to the electromagnet power supply so as to linearly increase the magnetic field generated by the electromagnet 5, the electromagnet 5 itself has an inductance. There are ingredients. Further, the magnetic pole of the iron core excited by the electromagnet 5 has magnetic hysteresis. As a result, the intensity of the magnetic field actually generated by the electromagnet 5 always has a delay with respect to the control signal from the spectrometer 2. When a high-speed magnetic field sweep is performed, the delay of the actual magnetic field intensity becomes remarkable, and the sampling interval of the A / D converter 6 is constant with respect to time. It becomes a distorted thing containing a component.

If the distortion is avoided, an accurate ES
In order to obtain the R spectrum, when setting the time and speed of the magnetic field sweep, it is necessary to set gentle conditions so that the magnetic field can actually accurately follow the control signal of the electromagnet 5. . For that purpose, the time of the magnetic field sweep must be lengthened and the sweep speed must be slowed down, and the measurement conditions must be significantly restricted.

[0010] Such a problem is not limited to only the ESR device. The same applies to a nuclear magnetic resonance (NMR) apparatus using both a high frequency and a magnetic field sweep method.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a magnetic resonance apparatus of a magnetic field sweeping type in which the effect of a magnetic field delay of an electromagnet does not appear even when a fast magnetic field sweep is performed.

[0012]

In order to achieve this object, a magnetic resonance apparatus according to the present invention comprises a high-frequency oscillator,
A high-frequency resonator capable of setting a measurement sample therein and resonating a high frequency supplied from a high-frequency oscillator;
Magnetic field generating means for applying a magnetic field to the high-frequency resonator,
Magnetic field sweeping means for sweeping the magnetic field strength of the magnetic field generating means, with the measurement sample set in the high-frequency resonator, resonate the high-frequency wave in the resonator, and simultaneously apply a sweep magnetic field to the resonator In a magnetic resonance apparatus configured to detect a high-frequency spectrum, convert the data into digital data using an A / D converter, and obtain the high-frequency spectrum, the magnetic resonance apparatus interlocks with the actual intensity change of the sweep magnetic field. A / D
It is characterized in that the sampling interval of the converter is controlled.

Further, the present invention is characterized in that the actual change in the intensity of the sweep magnetic field during the magnetic field sweep is stored in advance as data in the storage means of the magnetic resonance apparatus.

Further, the present invention is characterized in that the actual change in the intensity of the sweep magnetic field during the magnetic field sweep is calculated based on a predetermined function obtained in advance by experiments.

[0015] Further, the present invention is characterized in that the actual change in the intensity of the sweep magnetic field during the magnetic field sweep is measured by magnetic field measuring means provided near the measurement sample.

A high-frequency oscillator, a high-frequency resonator capable of setting a measurement sample therein and resonating a high-frequency supplied from the high-frequency oscillator, and a magnetic-field generating means for applying a magnetic field to the high-frequency resonator; Magnetic field sweeping means for sweeping the magnetic field strength of the magnetic field generating means, in a state where the measurement sample is set in the high-frequency resonator, the high-frequency resonance in the resonator, simultaneously applying a sweep magnetic field to the resonator In a magnetic resonance apparatus configured to detect a high-frequency spectrum, convert the high-frequency spectrum into digital data using an A / D converter, and obtain the high-frequency spectrum, a predetermined value stored in a storage unit of the magnetic resonance apparatus in advance is used. The A / D converter is controlled based on a sampling clock output at a timing.

A high-frequency oscillator, a high-frequency resonator capable of setting a measurement sample therein and resonating a high-frequency supplied from the high-frequency oscillator, and a magnetic-field generating means for applying a magnetic field to the high-frequency resonator; Magnetic field sweeping means for sweeping the magnetic field strength of the magnetic field generating means, with the measurement sample set in the high-frequency resonator, resonate the high-frequency wave in the resonator, and simultaneously apply a sweep magnetic field to the resonator In a magnetic resonance apparatus configured to detect a high-frequency spectrum, convert it to digital data using an A / D converter, and obtain the high-frequency spectrum, the actual intensity of the sweep magnetic field increases or decreases by a unit. The A / D converter is controlled based on a sampling clock output every time.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows the ESR according to the present invention.
1 shows an embodiment of the apparatus.

In FIG. 1, reference numeral 1 denotes a host computer for controlling the entire ESR apparatus. When the measurer sets measurement conditions in the host computer 1, the host computer 1 controls the spectrometer 2 to supply a microwave to the cavity 3 in which the sample is set. And a control signal to the pair of electromagnets 5 for applying a main magnetic field to the cavity resonator 3 to control the entire ESR apparatus under predetermined conditions.

The ESR spectrum is detected as a microwave absorption spectrum in the spectrometer 2 by sweeping the magnetic field strength of the electromagnet 5 while supplying the microwave to the cavity resonator 3. During the magnetic field sweep, this ESR
A sampling clock signal output via a newly provided oscillation control circuit 7 so that the spectrum data is taken into the host computer 1 at a timing linked to the actual change in the magnetic field strength of the electromagnet 5. , The A / D converter 6 is operated.

The oscillation control circuit 7 which outputs the sampling clock at a timing corresponding to the actual change amount of the magnetic field strength is constituted by a circuit as shown in FIG. 8 in the figure
Is an MPU. As the MPU 8, a device having an arithmetic processing function or a device operable based on measurement condition data is used. When the conditions of the magnetic field sweep are set in the spectrometer 2, the MPU 8 sets the data on the magnetic field delay stored in the memory 9 in advance, that is, the data of the actual swept magnetic field strength of the electromagnet 5, or the control signal of the electromagnet 5 and the actual signal. The data on the difference with the sweep magnetic field strength is read out, and the output timing of the sampling clock oscillated from the oscillator 10 is controlled in accordance with the magnetic field delay of the electromagnet 5 actually occurring. This means that every time the actual magnetic field strength value of the electromagnet 5 increases or decreases by a unit, a sampling clock for notifying the operation timing of the A / D converter 6 is supplied to the A / D converter 6. Means The A / D converter 6 operates according to the clock speed.
Since the SR data is converted into digital data, the host computer 1 can accurately calculate the E without the magnetic field delay component of the electromagnet 5.
An SR spectrum can be obtained.

The functions of the MPU 8 and the memory 9 may be provided inside the host computer 1 or the spectrometer 2. Also, the oscillator 10 may be any oscillator that can generate a clock at an arbitrary timing. Also, M
The clock may be generated directly from the PU 8.

In the above description, the memory 9 has
The data on the magnetic field delay, that is, the data on the actual sweeping magnetic field strength of the electromagnet 5 or the data on the difference between the control signal of the electromagnet 5 and the actual sweeping magnetic field strength have been stored in advance. It is not limited. For example, the output timing itself of the sampling clock output to the A / D converter 6 and corresponding to the magnetic field delay of the electromagnet 5 may be stored, or a function expressing the magnetic field delay may be stored in advance. It may be configured such that the value is obtained by an experiment, stored in the memory 9, and the actual value of the sweep magnetic field strength is calculated based on the function.

FIG. 5A shows a magnetic field control signal output to the electromagnet power supply at the time of ESR spectrum measurement and the actual magnetic field strength of the electromagnet swept with a predetermined magnetic field delay from the magnetic field control signal. (B) shows the sampling clock for the A / D converter. First, a magnetic field sweep signal is set based on a preset value of the magnetic field sweep time and the value of the magnetic field sweep width, and the magnetic field strength of the electromagnet is linearly controlled. Next, at the same time as the start of the sweep, a sampling clock that is accurately linked to the actual magnetic field sweep speed accompanied by the magnetic field delay is generated toward the A / D converter. The period of the sampling clock can be obtained by calculation from the number of data samples and the actual magnetic field sweep speed.

While the conventional sampling clock is a clock at a constant interval with respect to time, this sampling clock is a clock at a constant interval with respect to the amount of change in the magnetic field. There are features. ES that is A / D converted based on this sampling clock
The R signal is stored in a storage device such as a memory,
It becomes a spectrum. The ESR spectrum thus obtained is accurately represented by the relationship between the magnetic field strength (horizontal axis) and the signal strength (vertical axis). When the magnetic field sweep is completed,
The measurement completion flag is set from the MPU 8 or the oscillator 10 to terminate the data capture.

FIG. 6 shows the flow of control in this embodiment. First, the ESR measurement conditions are set in the host computer 1. Then, the control conditions of the microwave oscillator 4 and the electromagnet 5 are set in the spectrometer 2 under the control of the host computer 1. The oscillation control circuit 7 includes data on the magnetic field delay stored in the memory 9 in advance,
That is, the data of the actual sweeping magnetic field strength of the electromagnet 5 or the data relating to the difference between the control signal of the electromagnet 5 and the actual sweeping magnetic field strength is read out, and the output timing of the sampling clock oscillated from the oscillator 10 is determined. The conditions are set so that the control is performed in accordance with the magnetic field delay of the electromagnet 5 that occurs in the above.

Next, at the same time as the start of the magnetic field sweep, a sampling clock precisely linked to the actual magnetic field sweep speed with a magnetic field delay is generated toward the A / D converter, and the observed ESR signal is swept. A in conjunction with magnetic field strength change
/ D conversion. The host computer 1 takes in the digitized ESR signal and stores it in the storage device. When the magnetic field sweep is completed, a measurement end flag is set from the MPU 8 or the oscillator 10 to terminate the data acquisition.

FIG. 7 shows another embodiment of the ESR apparatus according to the present invention. In the figure, reference numeral 1 denotes a host computer that controls the entire ESR device. When the measurer sets measurement conditions in the host computer 1, the host computer 1 controls the spectrometer 2 to supply a microwave to the cavity 3 in which the sample is set. And a control signal to the pair of electromagnets 5 for applying a main magnetic field to the cavity resonator 3 to control the entire ESR apparatus under predetermined conditions.

The ESR spectrum is detected as a microwave absorption spectrum in the spectrometer 2 by sweeping the magnetic field strength of the electromagnet 5 while supplying the microwave to the cavity resonator 3. During the magnetic field sweep, this ESR
A sampling clock signal output via a newly provided oscillation control circuit 7 so that the spectrum data is taken into the host computer 1 at a timing linked to the actual change in the magnetic field strength of the electromagnet 5. , The A / D converter 6 is operated. This oscillation control circuit 7 is controlled by an output signal from a magnetic field strength detection circuit 11 arranged near the electromagnet 5.

The oscillation control circuit 7 which outputs the sampling clock at a timing corresponding to the actual change amount of the magnetic field strength is constituted by a circuit as shown in FIG. 8 in the figure
Is an MPU. As the MPU 8, a device having an arithmetic processing function or a device operable based on measurement condition data is used. When the magnetic field sweep is started, the MPU 8 outputs the output signal of the magnetic field detector 12 composed of a Hall element or the like arranged near the electromagnet 5 to the A / D converter 13.
A (During pre-reading, in accordance with the actual magnetic field strength), the A / D is instantaneously (read ahead) according to the actual sweep magnetic field strength reaches the magnetic field strength at which the ESR signal is sampled. Generate a sampling clock to the converter. This means that every time the actual magnetic field strength value of the electromagnet 5 increases or decreases by a unit, the sampling clock for notifying the operation timing of the A / D converter 6 is set to A.
/ D converter 6. A / D
Since the converter 6 converts the ESR data into digital data corresponding to the clock speed, the host computer 1
An accurate ESR spectrum that does not include the magnetic field delay component of the electromagnet 5 can be obtained.

The function of the MPU 8 may be provided inside the host computer 1 or the spectrometer 2. Also, the oscillator 10 may be any oscillator that can generate a clock at an arbitrary timing. Further, the clock may be directly generated from the MPU 8.

FIG. 9 shows a control flow of the present embodiment. First, the ESR measurement conditions are set in the host computer 1. Then, the control conditions of the microwave oscillator 4 and the electromagnet 5 are set in the spectrometer 2 under the control of the host computer 1. MPU of oscillation control circuit 7
8, when the magnetic field sweep is started, the signal of the magnetic field detector 12 composed of a Hall element or the like arranged near the electromagnet 5 is constantly (high-speed and periodically) transmitted through the A / D converter 13. Go to read, and when the actual swept magnetic field strength reaches the magnetic field strength at which the ESR signal is sampled, instantaneously (look ahead and match the actual magnetic field strength), generate a sampling clock to the A / D converter, Observed ESR
A / D conversion is performed on the signal in conjunction with the change in the intensity of the sweep magnetic field. The host computer 1 has a digitalized ES
The R signal is fetched and stored in the storage device. When the magnetic field sweep is completed, a measurement end flag is set from the MPU 8 or the oscillator 10 to terminate the data acquisition.

Although all of the above embodiments relate to an ESR apparatus, it goes without saying that the present invention is also applicable to an NMR apparatus using both a high frequency and a magnetic field sweep method.

[0034]

As described above, according to the magnetic resonance apparatus of the present invention, the sampling interval of the A / D converter for digitizing the measurement data is controlled in conjunction with the actual change in the intensity of the sweep magnetic field. Thus, it is possible to provide a magnetic resonance apparatus in which the effect of the magnetic field delay of the electromagnet does not appear even when the fast magnetic field sweep is performed. As a result, in the past, it was not possible to obtain an accurate magnetic resonance spectrum unless the magnetic field sweep time was set within a range where the magnetic field strength of the electromagnet could follow. , An accurate magnetic resonance spectrum can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing the concept of a conventional ESR device.

FIG. 2 is a diagram showing a relationship between a magnetic field control signal, a sampling clock, and an ESR spectrum of a conventional ESR device.

FIG. 3 is a diagram showing one embodiment of an ESR device according to the present invention.

FIG. 4 is a diagram showing one embodiment of a transmission control circuit of the ESR device according to the present invention.

FIG. 5 is a diagram showing a relationship between a sweep magnetic field and a sampling clock of the ESR device according to the present invention.

FIG. 6 is a diagram showing an embodiment of a control flow of the ESR device according to the present invention.

FIG. 7 is a diagram showing another embodiment of the ESR device according to the present invention.

FIG. 8 is a diagram showing another embodiment of the transmission control circuit of the ESR device according to the present invention.

FIG. 9 is a diagram showing another embodiment of the control flow of the ESR device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Host computer, 2 ... Spectrometer, 3 ... Cavity resonator, 4 ... Microwave oscillator, 5 ... Electromagnet, 6 ...
A / D converter, 7 ... oscillation control circuit, 8 ... MPU, 9 ...
Memory, 10 oscillator, 11 magnetic field strength detection circuit, 12 magnetic field detector, 13 A / D converter.

Claims (6)

[Claims] 1. A high-frequency oscillator, a high-frequency resonator capable of setting a measurement sample therein and resonating a high-frequency supplied from the high-frequency oscillator, and a magnetic-field generating means for applying a magnetic field to the high-frequency resonator; Magnetic field sweeping means for sweeping the magnetic field strength of the magnetic field generating means, with the measurement sample set in the high-frequency resonator, resonate the high-frequency wave in the resonator, and simultaneously apply a sweep magnetic field to the resonator In a magnetic resonance apparatus configured to detect a high-frequency spectrum, convert the data into digital data using an A / D converter, and obtain the high-frequency spectrum, the magnetic resonance apparatus interlocks with the actual intensity change of the sweep magnetic field. A magnetic resonance apparatus wherein a sampling interval of an A / D converter is controlled. 2. The magnetic resonance apparatus according to claim 1, wherein the actual change in the intensity of the sweep magnetic field during the magnetic field sweep is stored in advance in a storage unit of the magnetic resonance apparatus as data. 3. The magnetic resonance apparatus according to claim 1, wherein the actual change in the intensity of the sweep magnetic field during the sweep of the magnetic field is calculated based on a predetermined function obtained in advance by experiment. 4. The magnetic resonance apparatus according to claim 1, wherein the actual change in the intensity of the sweep magnetic field during the sweep of the magnetic field is measured by magnetic field measuring means provided near the measurement sample. 5. A high-frequency oscillator, a high-frequency resonator capable of setting a measurement sample therein and resonating a high-frequency supplied from the high-frequency oscillator, and a magnetic-field generating means for applying a magnetic field to the high-frequency resonator. Magnetic field sweeping means for sweeping the magnetic field strength of the magnetic field generating means, in a state where the measurement sample is set in the high-frequency resonator, the high-frequency resonance in the resonator, simultaneously applying a sweep magnetic field to the resonator In a magnetic resonance apparatus configured to detect a high-frequency spectrum, convert the high-frequency spectrum into digital data using an A / D converter, and obtain the high-frequency spectrum, a predetermined frequency stored in a storage unit of the magnetic resonance apparatus in advance is used. A magnetic resonance apparatus wherein the A / D converter is controlled based on a sampling clock output at a timing. 6. A high-frequency oscillator, a high-frequency resonator capable of setting a measurement sample therein and resonating a high-frequency supplied from the high-frequency oscillator, and a magnetic field generating means for applying a magnetic field to the high-frequency resonator; Magnetic field sweeping means for sweeping the magnetic field strength of the magnetic field generating means, with the measurement sample set in the high-frequency resonator, resonate the high-frequency wave in the resonator, and simultaneously apply a sweep magnetic field to the resonator In a magnetic resonance apparatus configured to detect a high-frequency spectrum, convert it to digital data using an A / D converter, and obtain the high-frequency spectrum, the actual intensity of the sweep magnetic field increases or decreases by a unit. A magnetic resonance apparatus characterized in that the A / D converter is controlled based on a sampling clock output every time.