JPS6039576A - Nuclear magnetic resonator device - Google Patents

Abstract

PURPOSE:To lock easily the intensity of a static magnetic field to a prescribed value by adding a dispersing signal to a signal from a magnetic field control means and supplying it to a magnetic field generating means, when an absorbing signal from a sample attains to a prescribed intensity. CONSTITUTION:A high frequency of the maximum intensity from an oscillator 4 is supplied to an irradiating coil 3 by controlling an attenuator 5 by a control means 11, and also an energizing current supplied to a magnetic field generating coil 1 through a D/A converter 12 and an adder 9 is swept. Among resonance signals by a locking sample from a receiver 6, an absorbing signal is supplied to the control means 11 through an A/D converter 10, and when the intensity of this signal exceeds a threshold level, the sweep of intensity of a static magnetic field is stopped, and also the resonance signal of a locking sample attains to suitable intensity by controlling an attenuator 5. Also, an integrator 7 starts an integration of a dispersing signal, an integral output is supplied to the adder 9 through a relay 8, and a value of the static magnetic field by the coil 1 is locked to the center of a dispersing resonance signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nuclear magnetic resonance apparatus, and more particularly to a nuclear magnetic resonance apparatus having a function of automatically locking the strength of a static magnetic field to a predetermined strength.

In a nuclear magnetic resonance apparatus, the strength of the polarizing static magnetic field must always be maintained at a predetermined value. Therefore, a reference sample is placed in the sample to be measured, and the strength of the magnetic field is adjusted to that of the reference sample. Locking is performed to match the peak point of the resonance signal. In this case, when replacing the sample, etc., the lock of this magnetic field will inevitably be released, and even if you try to lock the magnetic field by placing Test i/31 in the magnetic field a3, If the static magnetic field drifts significantly, the resonance signal of the locking reference sample may not be found. In such a case, manually adjust the power supply of the magnet device that generates the static field or the power supply of the auxiliary coil installed separately from the magnet device, search for the resonance signal of the reference sample, After that, the lock loop must be turned on, which is a tedious task.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a nuclear magnetic resonance apparatus that can easily lock a static magnetic field.

A nuclear magnetic resonance apparatus based on the present invention includes a magnetic field generating means, a magnetic field controlling means for avoiding changes in the strength of the magnetic field, an oscillator for irradiating a sample in the magnetic field with high frequency, and a signal from the oscillator. A circuit for detecting a resonance signal from the sample as a reference signal and obtaining a dispersion signal and absorption (No. /j, the dispersion signal is combined with the signal from the magnetic field control means and supplied to the rIl field generation means.

An embodiment of the invention will be described below in detail based on the attached four drawings.

In FIG. 1, reference numeral 1 denotes a coil C that generates a static magnetic field, and a sample tube 2 is placed in the generated magnetic field, in which a sample to be measured and a reference sample for locking are placed.

An irradiation coil J3 is wound around the outside of the sample tube 2, and a high frequency wave oscillated from a high frequency oscillator 1 is supplied to the irradiation=1 coil via an attenuator 5G. The resonance signal of the L1 detection sample detected by the irradiation coil 3 is detected and amplified by the receiver 6 to which the reference signal is supplied from the oscillator. In the receiver 6,
The phase of the reference signal from the oscillator 4 is set to Oo, 90° and J.
It is configured to obtain a dispersion signal and an absorption signal by doing this. The distributed signal is integrated by an integrator 7 and then supplied to an adder 9 via a relay. The absorbed signal received by the receiver 6 is converted into a digital signal by an A/D converter 10 and then supplied to a control means 11 such as a microprocessor. The control means 11 is configured to control the current value supplied to the static magnetic field generating coil 1, and the signal from the control means 11 is converted into an analog signal by a D-A converter 12 and then , are supplied to the coil 1 via the adder 9.

In the above-described configuration, in order to lock the strength of the static magnetic field generated by the coil 1 to a predetermined value, the attenuator is first controlled by a signal from the control means 11;
The oscillator 4 supplies the irradiation coil 3 with a high frequency wave of maximum intensity. Next, the control means 11 to 1) -A converter 12. Excitation 11 supplied to the coil via adder 9
The current is swept relatively slowly. Along with the sweep, the receiver 6 transmits the dispersion and absorption of the resonance signal by the sample for [-1], as shown by the solid lines in FIGS. 2(a) and 2(b), respectively. @ A is obtained. Furthermore, at this time,
The integrator 7 is prevented from operating or is set to a low gain CL13, and the relay 8 is turned off. The absorption signal is transmitted through the △-1] converter 10 -(the control means 1
1, but the control means monitors the intensity of the supplied absorption signal, and the intensity of the CF signal is
When the threshold value I shown in FIG. 2(b) is less than -1, the control signal is transferred to the integrator 7. The relay 8 is supplied to the allinator 5, and at the same time, the control means stops sweeping the strength of the static magnetic field. The attenuator 5 is controlled by a signal from the control means 11, and the intensity of the high frequency wave supplied from the oscillator 4 to the irradiation coil 3 is attenuated, so that the resonance signal of the rock sample is as shown by the dotted line in FIG. The strength is suitable for automatic locking. The integrator 7 is connected to the control means 11
The output signal of the integrator 7 is supplied to the adder 9 via the relay 8. As a result, when the distributed signal has a positive value, the current added by the adder 9 and supplied to the coil 1 is increased, and when the distributed signal has a negative value, the current supplied to the coil 1 is increased. Since the current is reduced, the value of the static magnetic field due to the coil 1 is:
It will be locked to the center Zo of the distributed resonance signal.

In this way, the above-described embodiment sweeps the static magnetic field, monitors the intensity of the absorption signal of the resonance signal of the obtained rock sample, and when the intensity of the absorption signal exceeds a predetermined value, Since the static magnetic field is automatically locked using the dispersion signal of the resonance signal, the static magnetic field can be easily locked even when changing samples without any troublesome work. . Note that the present invention is not limited to the embodiments described above, and can be modified in many ways. For example, in the embodiment of FIG. 1, the static magnetic field was swept relatively slowly, but it is also possible to sweep the static magnetic field rapidly. During the rapid sweep, the absorption signal is detected with a certain time delay, so even if the value of the absorption signal exceeds the threshold value, the strength of the magnetic field has already exceeded the resonance signal. It is possible that it is passing through. () When the rapid (■) pull is performed, after the sweep is stopped, the strength of the magnetic field is slowly swept in the opposite direction, and as in the above embodiment, when the absorption signal exceeds the threshold value, Just stop sweeping the magnetic field and turn on the lock loop.

Also, the magnetic field strength is rapidly swept from the minimum to the maximum in a predetermined range in which the resonance signal is detected, and the magnetic field strength ZI of the peak point of resonance No. 18 detected at this time is memorized and stored as C. Next, Sweep the strength of the magnetic field in the same range from the maximum to the minimum in the opposite direction with the same *tX, memorize the magnetic field strength Z2 at the peak point of the resonance signal detected at this time, and apply the same magnitude in the opposite direction. Detected strong 1αZ+, from Z2 (Z+ → -22)
If the magnetic field strength is set to 1iri and then locked, the magnetic field will be locked to a predetermined value in a short time.

Furthermore, in the embodiments described above, the sweeping of the magnetic field and the threshold may be performed analogously.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing a dispersion signal and an absorption signal of a resonance signal from a rock sample. 1... Magnetic field generating coil 2... Sample tube 3... Irradiation coil 4... Oscillator 5... Attenuator 6... Receiver 7... Integrator 8... Relay 9... Shelving frame 10...A-D converter 11...Control means 12...D-A converter Patent applicant JEOL Ltd. Representative Mr. Ito

Claims (2)

[Claims] (1) a magnetic field generating means, and l for changing the strength of the magnetic field;
: A magnetic field control means, an oscillator for applying high frequency to the sample in the II magnetic field, and a resonance signal from the sample is detected using the signal from the oscillator as a reference signal to obtain a dispersion signal and an absorption signal. a circuit, and means for monitoring the intensity of the absorption signal, and when the absorption signal reaches a predetermined intensity, the magnetic field generation means adds the corresponding amount to the signal from the magnetic field control means. A nuclear magnetic resonance apparatus configured to supply (2) The high frequency from the oscillator is applied to the sample via an attenuator, and when monitoring the intensity of the absorption signal, the intensity of the high frequency applied to the sample by the attenuator is Emphasized Claim No. 1 In
The described nuclear magnetic resonance apparatus.