JP2001215239A - Detector for rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detector for a rotor having a light source and a photo detecting element with their temperatures not exceeding operable temperatures of their electronic elements, with facilitated positional adjustment of the light source and the detecting element, not adversely affecting the uniformity of a magnetostatic field of an NMR(nuclear magnetic resonance) device, and not requiring disposing the light source and the detecting element in at least two positions. SOLUTION: This detector is equipped with a light emitting means for emitting two or more kinds of light different in characteristics. The two or more kinds of light different in characteristics are switched at a prescribed frequency and emitted toward the rotor provided with a prescribed number of reflection areas corresponding to the number of kinds of light for reflecting only a prescribed kind of light of the two or more kinds of light different in characteristics. Light reflected from the rotor is detected by a prescribed photo detecting means, thereby judging whether the rotor exists or not and measuring the rotational speed of the rotor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating body detecting apparatus suitable for use in, for example, a nuclear magnetic resonance (NMR) apparatus for determining the presence or absence of a sample tube at a measurement site and measuring the rotation speed of the sample tube. About.

[0002]

2. Description of the Related Art In an NMR apparatus, a sample tube is rotated during measurement of an NMR spectrum in order to improve the magnetic field uniformity and increase the resolution. At this time, if the rotation speed is too high, a meniscus is formed and the resolution is reduced. If the rotation speed is too low, problems such as an increase in the spinning side band occur.
It is necessary to maintain 5 revolutions / sec. Conventionally, in order to maintain the rotation speed stably, the rotation speed of the sample tube is monitored using a rotating body detection device, and the result is fed back to a sample tube rotation mechanism via a rotation speed control circuit.

FIG. 1 schematically shows the structure of a conventional rotating body detecting device. In the figure, reference numeral 1 denotes an NMR sample tube. A sample tube holder 2 called a rotor is fitted into the upper part of the NMR sample tube 1. The sample tube holder 2 is floated in the space of the measurement unit by air blown from below, and air is strongly blown from the side of the sample tube holder 2 via a nozzle (not shown). Thus, the sample tube holder 2 rotates at a predetermined speed integrally with the NMR sample tube 1.

[0004] The sample tube holder 2 is usually made of a white material, such as Teflon or Duracon, which easily reflects light. It is configured so that only light is absorbed. Then, light is emitted from a light source 3 made of a photodiode or the like toward the sample tube holder 2, and reflected light reflected by a white portion of the sample tube holder 2 is received by a photodetector 4 made of a phototransistor or the like. . With the rotation of the sample tube holder 2, the light absorbing portion 5 painted black
Pass through the front of the light source 3 at a predetermined cycle, and the state without reflected light is periodically detected by the photodetector 4. The rotation speed of the NMR sample tube 1 and the sample tube holder 2 can be known by accurately measuring the period in which the state without reflected light comes.

[0005] The rotation speed measured in this way can be maintained at a predetermined value by controlling the blowing strength of air to the sample tube holder 2.
Therefore, usually, in order to control the rotation speed of the NMR sample tube 1, a difference between the measured rotation speed and a preset rotation speed is detected, and the difference signal is fed back to the air blowing intensity. A circuit 6 is provided.

Further, the conventional rotating body detecting device can not only measure the rotation speed of the NMR sample tube 1. It is also possible to determine whether or not the NMR sample tube 1 and the sample tube holder 2 are present, that is, whether the NMR sample tube 1 and the sample tube holder 2 are set at predetermined measurement positions. It is, as shown in FIG.
The light source 3 and the photodetector 4 described above are made into one set, and 18
This is made possible by arranging two opposing positions at a distance of 0 °.

That is, the reflected light is detected by the combination of the first light source 3 and the light detecting element 4 among the light sources 3 and the light detecting elements 4 provided at two places, and the second light source 3 and the light detecting element 4 are detected. When the reflected light is not detected due to the combination of the elements 4, the white portion of the sample tube holder 2 exists at a position facing the first light source 3 and the light detection element 4, and the second light source 3 and the light detection element 4 Sample tube holder 2 at the opposite position
It is determined that there is a black portion of
It can be determined that the R sample tube 1 and the sample tube holder 2 are set at predetermined measurement positions.

When the reflected light is detected by both the light source 3 and the light detecting element 4 provided at two places, the reflected light is located at a position facing both the light source 3 and the light detecting element 4 provided at the two places. It is determined that the white portion of the sample tube holder 2 exists, and in this case also, it can be determined that the NMR sample tube 1 and the sample tube holder 2 are set at predetermined measurement positions.

On the other hand, if the reflected light is not detected by both the light source 3 and the light detecting element 4 provided at two places, it is possible that the black portion of the sample tube holder 2 exists at a position 180 ° apart. Therefore, it is determined that the sample tube holder 2 does not exist, and only in this case, it is determined that the NMR sample tube 1 and the sample tube holder 2 are not set at the measurement position.

[0010]

In such a configuration, a problem of the conventional rotating body detecting apparatus is that the light from the light source 3 is applied to the sample tube holder 2 and the reflected light is detected by the light detecting element 4. Light source 3 and photodetector 4
Has been installed very close to the sample tube holder 2. As a result, when the temperature of the measurement sample is varied from high to low when measuring the NMR, the temperature of the light source 3 and the photodetector 4 can be changed according to the surrounding temperature change, and the respective electronic elements can operate. Beyond the temperature, the temperature greatly changes from about 100 ° C. to about −50 ° C.
There is a problem that deterioration or damage is caused.

In addition, in the conventional method, it is difficult to adjust the positions of the light source 3 and the light detecting element 4, and there is a problem that the reflected light cannot be correctly detected depending on the set angles of the two.

In the conventional method, the light source 3 and the photodetector 4 have a considerable adverse effect on the uniformity of the static magnetic field of the NMR apparatus due to the magnetic properties of the materials constituting the light source 3 and the photodetector 4. To disturb the uniformity of the static magnetic field and degrade the resolution of the NMR spectrum.

Further, in the conventional method, there is a problem that the light source 3 and the light detecting element 4 must be arranged at at least two places in order to determine the presence or absence of the NMR sample tube 1 and the sample tube holder 2.

In view of the above, it is an object of the present invention that the temperature of the light source 3 and the light detecting element 4 does not exceed the operable temperature of each electronic element, and the position of the light source 3 and the light detecting element 4 can be easily adjusted. Accordingly, an object of the present invention is to provide a rotating body detection device that does not adversely affect the uniformity of the static magnetic field of the NMR device and does not require the light source 3 and the light detection element 4 to be arranged at at least two places.

[0015]

In order to achieve this object, a rotating body detecting apparatus according to the present invention comprises light irradiating means for irradiating at least two kinds of light having different properties, and at least two kinds of light having different properties are provided. A rotating body provided with a predetermined number of reflection areas corresponding to the number of types of light, while switching the light at a predetermined frequency and reflecting only predetermined light of at least two types of light having different properties. And determining the presence or absence of the rotating body and measuring the rotating speed of the rotating body by detecting the reflected light reflected from the rotating body with a predetermined light detecting means. It is characterized by.

Further, at least two kinds of light having different properties are light having different wavelengths from each other.

Further, at least two kinds of light having different properties are polarized lights having different polarization angles from each other.

Further, the light irradiating means and the light detecting means are connected to the rotating body at a predetermined distance by a light transmitting means.

Further, the optical transmission means is an optical fiber.

Further, the light transmission means is constituted by a mirror.

Further, the reflection area is divided into at least two kinds of areas corresponding to at least two kinds of lights having different properties irradiated on the light irradiation part of the rotating body. And

Further, the switching frequency at the time of irradiating light from the light irradiating means toward the rotating body is as follows: multiply 360 ° by the upper limit of the number of rotations of the rotating body per unit time, and multiply the obtained value by The frequency is at least twice as large as the largest value among the values obtained by dividing by the circumferential angle occupied by the reflection area that reflects light of a predetermined property provided at the light irradiation site of the rotating body. .

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows an embodiment of the rotating body detection device according to the present invention. 1 in the figure
This is a sample tube for NMR. In the sample tube 1 for NMR, N
Contains MR sample 7. The NMR sample tube 1 is fitted into a sample tube holder 2 whose surface is painted in two stripes of red and green at equal intervals. Inside the rotation holding mechanism 8, air is blown from a nozzle (not shown) to
The sample tube 1 for MR and the sample tube holder 2 are levitated and rotated at a predetermined speed.

The light source 3 made of a two-color switching photodiode or the like receives a light emission control signal from the light emission / light reception control circuit 9 and emits light in red or green in a time division manner. The optical fiber 10 guides the light of the light source 3 to a position near the sample tube holder 2. When the light source 3 emits red light, the red light is irradiated on the surface of the sample tube holder 2 through the optical fiber 10 and is reflected by a red stripe portion painted on the surface of the sample tube holder 2. However, light is absorbed by the green stripes, and no reflection occurs. Conversely, when the light source 3 emits green light, the green light is radiated to the surface of the sample tube holder 2 through the optical fiber 10, and the green stripes are painted on the surface of the sample tube holder 2. Is reflected. However, light is absorbed in the red stripe portion, and no reflection occurs.

The light reflected by the red or green stripes applied to the surface of the sample tube holder 2 passes through the optical fiber 11 and is guided to the photodetector 4 made of a phototransistor or the like. In the light detection element 4, the received light is converted into an electric signal, and is guided to the light emission / light reception control circuit 9. The light emission / light reception control circuit 9 detects reflected light in synchronization with a light emission control signal to the light source 3.

Under the control of the light emission / light reception control circuit 9, the light source 3 alternately switches between red light and green light,
Light emission is repeated in a time sharing manner. Since the sample tube holder 2 is color-coded into two colors, red and green, when the red portion comes to the tip of the optical fiber 10, light is reflected when the light source 3 is shining red, and light detection is performed. A voltage is generated in the element 4. On the other hand, when the green portion is at the tip of the optical fiber 10, the light is reflected when the light source 3 is illuminating green, and a voltage is generated in the photodetector 4.

Therefore, when a predetermined color portion of the sample tube holder 2 crosses the distal end of the optical fiber 10, the switching is quickly performed to irradiate red light and green light in a time-division manner, and the presence or absence of reflected light at that time is determined. Photodetector 4 in time division
, It is possible to determine whether the color of the portion that is going to cross the tip of the optical fiber 10 is a red portion or a green portion. The number of rotations of the sample tube holder 2 per unit time is measured by continuously determining the color and counting the number of times that a stripe portion of a different color crosses the tip of the optical fiber 10 as a color change period. can do. This value is fed back to the blowing strength of air to the sample tube holder 2 by a feedback circuit (not shown), and the rotation speed of the sample tube holder 2 and the NMR sample tube 1 is controlled and maintained at a predetermined value.

FIG. 4 is a timing chart showing the above operation. FIG. 3A shows a state in which a red portion and a green portion painted on the surface of the sample tube holder 2 alternately cross the tip of the optical fiber 10 at a predetermined cycle. (B) shows the timing at which the light source 3 emits red light to the red and green portions, and (c) shows the timing at which green light is emitted. (D) shows the timing of the light receiving signal of the reflected light detected by the photodetector 4 in synchronization with the timing of the irradiated red light, and the light in synchronization with the timing of the irradiated green light. (E) shows the timing of the light receiving signal of the reflected light detected by the detecting element 4. In this example, the light source 3 has a switching frequency four times faster than the frequency of the color change of the sample tube holder 2.
, The reflected light of the same color is continuously detected at least four times or more, and the frequency of the color change of the sample tube holder 2 is measured.

At this time, the frequency at which red light and green light are switched by the light source 3 is determined from the viewpoint of time resolution.
The value must be at least twice as large as the value obtained by multiplying the upper limit of the number of rotations of the sample tube holder 2 per unit time by the number of color stripes. By alternately irradiating two types of light while switching at such a frequency,
Compared with the conventional rotating body detection device using a sample tube holder of a type having only one light absorbing portion, the sample tube holder 2
The rotation speed of the sample tube holder 2 can be detected with a higher time resolution as the number of stripes increases. This makes it possible to perform high-speed feedback control on fluctuations in rotational speed that occur during one rotation of the sample tube holder 2, for which feedback control was conventionally impossible.

According to the method of the present invention, if the sample tube holder 2 is opposed to the tip of the optical fiber 10, one of the red light and the green light is necessarily reflected. If the light source 3 emits red or green light in a time-division manner, it is possible to immediately determine whether or not the NMR sample tube 1 and the sample tube holder 2 are present in the measurement unit based on the presence or absence of reflected light. As a result, there is no need to provide a light source and a photodetector at at least two places as in the related art.

The combination of paints applied to the sample tube holder 2 reflects light of another wavelength, for example, visible light other than red and green, infrared light, or ultraviolet light instead of red and green. It is possible to use a combination of two paints that reflect light of a predetermined wavelength from the paints to be used. In this case, the light source 3 may be configured to emit two types of light, visible light other than red and green, infrared light, or ultraviolet light.

Also, the light used in the present invention has the same wavelength and a different polarization angle even if it is not light having a different wavelength.
There may be two polarized lights. In this case, a reflector and a polarizing filter are combined on the surface of the sample tube holder 2,
What is necessary is just to form a stripe portion that can reflect only polarized light having a predetermined polarization angle.

The stripes of the color on the surface of the sample tube holder 2 need not be stripes of different colors having the same width, but may be stripes of different colors having different widths. Also,
Only one stripe of another color may be painted while being painted in one color. In these cases, the switching frequency for alternately irradiating different light from the light source 3 toward the sample tube holder 2 multiplies 360 ° by the upper limit of the number of rotations per unit time of the sample tube holder 2, Of the values obtained by dividing the value obtained by the circumferential angle occupied by the stripes painted on the surface of the sample tube holder 2, it is necessary to set the frequency to at least twice the largest value. That is, (switching frequency) ≧ MAX {2 × 360} ×
(Upper limit of the number of rotations of the sample tube holder) / (angle in the circumferential direction occupied by the fringe) 周波 数 At frequencies lower than this, it is necessary only to determine the color of the fringe based on the presence or absence of reflected light from the fringe. This is because time resolution cannot be obtained.

Further, optical fibers 10 and 11 connecting between the light source 3 and the light detecting element 4 and the sample tube holder 2 are provided.
It is not always necessary to use two optical fibers each, and a bundle of optical fibers may be divided into two between the light source 3 and the photodetector 4 for use. Further, the optical fiber as the light transmission means is not necessarily an essential component for the present invention. The transmission path for transmitting light may be constituted by, for example, one or more mirrors.

Further, instead of coloring the side surface of the sample tube holder 2, a method may be used in which the upper surface or the lower surface of the sample tube holder 2 is colored to observe the reflection. Needless to say, instead of coloring the sample tube holder 2, the sample tube may be colored directly.

In the embodiment, the sample tube holder 2, which is limited to two colors in the embodiment, is colored in three or more colors, and the light source 3 emits light at multiple wavelengths of three or more wavelengths to perform time-division irradiation. However, needless to say, the same effects as those of the present invention can be obtained.

[0037]

As described above, according to the rotator detecting apparatus of the present invention, a predetermined number of reflection areas for reflecting only a predetermined light of at least two kinds of light having different properties are provided. At least two different properties for the rotating body
Using a light source that emits different types of light and a photodetector, the reflected light from the rotating body is detected in a time-division manner from a position that is separated from the rotating body by a predetermined distance. During measurement, the temperature of the light source and the photodetector do not exceed their respective operable temperatures, the position of the light source and the photodetector can be easily adjusted, There is no adverse effect, and it is not necessary to dispose the light source and the photodetector at at least two places for detecting the rotating body.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a conventional rotating body detection device.

FIG. 2 is a diagram showing another example of a conventional rotating body detection device.

FIG. 3 is a diagram showing one embodiment of a rotating body detection device according to the present invention.

FIG. 4 is a diagram showing one embodiment of a timing chart of the rotating body detection device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... NMR sample tube, 2 ... sample tube holder, 3 ... light source, 4 ... light detection element, 5 ... light absorption part, 6 ... feedback circuit, 7 ... NMR sample, 8 ... rotation holding mechanism,
9: light emission / light reception control circuit, 10: optical fiber, 11
... optical fiber.

Claims (8)

[Claims] A light irradiating means for irradiating at least two kinds of light having different properties, wherein at least two kinds of light having different properties are switched at a predetermined frequency, A predetermined number of reflection areas corresponding to the number of types of light are radiated toward a predetermined number of rotating bodies, and the reflected light reflected from the rotating bodies is detected by a predetermined light. A rotating body detecting device for determining the presence or absence of the rotating body and measuring the rotational speed of the rotating body by detecting the rotating body. 2. The rotating body detecting device according to claim 1, wherein said at least two types of light having different properties are lights having different wavelengths from each other. 3. The rotating body detecting device according to claim 1, wherein the at least two types of light having different properties are polarized lights having different polarization angles. 4. The rotating body detecting device according to claim 1, wherein the light irradiating means, the light detecting means and the rotating body are connected by a light transmitting means at a predetermined distance. 5. The rotating body detecting device according to claim 4, wherein said light transmitting means is an optical fiber. 6. A rotating body detecting device according to claim 4, wherein said light transmitting means is constituted by a mirror. 7. The reflection region is divided into at least two types of regions corresponding to at least two types of light having different properties and applied to a light irradiation site of the rotating body. The rotating body detection device according to claim 1, wherein 8. A switching frequency for irradiating light from said light irradiating means to said rotating body is obtained by multiplying 360 ° by an upper limit value of the number of rotations per unit time of said rotating body. It is characterized in that the frequency is at least twice as large as the largest value among the values obtained by dividing by the circumferential angle occupied by the reflection area that reflects light of a predetermined property provided at the light irradiation site of the rotating body. A rotating body detection device according to claim 7.