JPH04131716A - Fine vibration detector - Google Patents

Abstract

PURPOSE:To precisely detect one-dimensional to three-dimensional fine vibrations by utilizing the Meissner effect of a superconductor. CONSTITUTION:1 is a Sm-Co magnet having a ring form. 2 is a superconductor, which is worked into a spherical form and has a critical temperature of about 90 K. When the inner part surrounded by the dotted line of the drawing is cooled to less than about 77 K by a cooling device not shown, the superconductor 2 levitates by Meissner effect. The superconductor 2 is irradiated with the light 7 from a laser diode 3. When a vibration is generated, the magnet 1 is displaced by the vibration, but the position of the superconductor is not changed just after generation of the vibration by the inertia. Thus, the relative position between the superconductor and the magnet is changed by the vibration, so that the vibration can be detected by the positional change of the light detected by a light detector 5. By providing the light emitting source 3 and optical sensor 5 two-dimensionally or three-dimensionally, the two-dimensional or three-dimensional displacement can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a highly sensitive two- and three-dimensional microvibration detector using a superconductor.

[Prior Art] As shown in FIG. 5, a conventional microvibration detector uses a silicon substrate 9 to form a cantilever, and attaches a weight portion 10 to the tip of the cantilever and an electrode to the bending portion 8. This is a typical example (electrodes are omitted in Figure 5). Detection of minute vibrations is performed when the sensor receives acceleration α in two directions, and the weight portion 10 (
A force of F=mα is applied to the force (x amount is m), and the deflection portion 8 is deflected. As a result, the resistance of the bent portion 8 changes due to the piezoresistance effect due to the stress T generated in the bent portion 8, and minute vibrations are detected by measuring this resistance change with an electrode attached to the bent portion 8. The amount of change in resistance is proportional to stress T as expressed by the following equation.

Δρ : Ip π T Δρ : Amount of change in resistivity due to stress ρ : Resistivity when there is no strain π : Vieso resistance coefficient Accelerometers using semiconductors like this can be fabricated using semiconductor processing technology. Sensitivity can be improved by improving accuracy, downsizing, or changing the shape of the bending portion 8.

[Problem B to be Solved by the Invention] However, the conventional micro-vibration detector shown in FIG. 5 has many practical problems because it utilizes the deflection of the cantilever. For example, in order to increase the sensitivity of the sensor, the thickness of the flexure part 8 should be made thinner, and the thickness of the weight part 1 should be made thinner.
It is possible to increase the mass of the 0, but in this case, the mechanical strength of the bending portion 8 decreases. Furthermore, there is a possibility that the deflection portion 8 is deformed not only in the Z direction, which is the acceleration measurement direction, but also in the y direction and the torsional direction. For this reason, resistance generated from deflection in directions other than the Z direction is also measured, resulting in a decrease in two-direction resolution of acceleration. In addition, in the case of an acceleration sensor using a cantilever, −
Although acceleration in dimensional directions can be measured, two or three sensors must be used to measure in two or three dimensions, so it is necessary to correct the sensitivity of each sensor. Further, an electrode is attached to the bending part 8, but since the electrode and the bending part 8 are made of different materials, if the electrode is made by a thin film forming method such as a vacuum evaporation method, a crystal lattice is formed at the interface of each material. Film peeling of each constituent material may occur during operation due to mismatch in the film thickness or thermal stress during thin film formation.

[Means and effects for solving the problems] The present invention solves the above problems by utilizing a superconductor and its Meissner effect. That is, the present invention provides a microvibration detector characterized by having a magnetic circuit and an optical position detection mechanism for levitating a superconductor by the Meissner effect, and a microvibration detector that levitates a superconductor by the Meissner effect of the superconductor. This is a micro vibration detector characterized by having a magnet and an optical position detection mechanism.

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 shows the principle of the first invention, and FIG. 2 shows the principle of the second invention.

As the magnetic circuit 1 in FIG. 1, for example, Sm-Go
Any permanent magnet, electromagnet, superconducting magnet, etc., which can levitate the superconductor 2, is not particularly limited. Further, the shape and number of the magnetic circuits 1 are not particularly limited, and the shape and number may be determined in consideration of the gradient of the magnetic field.

In FIG. 1, the superconductor 2 is levitated, but in FIG. 2, the magnet 1' is levitated. At this time, the magnet 1' is, for example, Sm-C.

There is no particular limitation as long as it can levitate due to the Meissner effect of the superconductor 2, such as permanent magnets. Further, the shape and number of magnets 1' are not particularly limited, and may be determined by taking into consideration the gradient of the magnetic field.

As the superconductor 2, for example, a metal such as Nb or Nb3T is used.
Alloy superconductors such as i or Y-Ba-Cu-0, B
1-5r-Ca-Cu-0, TJ! -5r-Ca-Cu
Any material that exhibits superconductivity, such as a -0-based oxide superconductor, may be used. The shape of the superconductor 2 and the number used can be changed as necessary. In other words, magnetic circuit 1
Or, these are determined by the relative relationship with magnet 1', and due to the Meissner effect, superconductor 2 or magnet 1°
It should be arranged so that it will most easily float.

The optical position detection mechanism uses the levitated superconductor 2 or magnet 1
Any mechanism that can optically detect a change in position in degrees will suffice, but specifically, the shape of the light irradiated from the light irradiation source 3, such as a laser diode, a halogen lamp, or a semiconductor laser, can be detected by the optical system 4, for example. The superconductor 2 or magnet 1 is irradiated with light by modifying it from circular to linear using a cylindrical lens, glass lens, etc., or by enlarging or contracting the shape of the light and irradiating the superconductor 2 or magnet 1, which is floating due to the Meissner effect.
, or a mechanism in which the optical sensor 5 detects the light that is not blocked by the magnet 1°. A micro-vibration detector is formed with such a configuration, and when vibration occurs in the part where the micro-vibration detector is attached, the superconductor 2 and the magnetic surface path 1, which were levitated due to the Meissner effect, or the levitated magnet l
The relative position of the superconductor 2 and the superconductor 2 changes due to minute vibrations.

This change in the position of the superconductor 2 or the magnet 1' is detected by the optical sensor 5. Furthermore, by arranging the light irradiation source 3 and the light sensor 5 two-dimensionally or three-dimensionally,
It is possible to detect displacement in two or three dimensions. Furthermore, in FIGS. 1 and 2, the light from the light irradiation source 3 is irradiated onto the superconductor 2 or the magnet 1° which is floating due to the Meissner effect, and the projected light is applied to the superconductor 2 or the magnet. Although a positional change of 1° was detected, the positional change can also be detected by reflected light by changing the arrangement of the optical sensor 5 that detects light. In this way, the present invention does not detect minute vibrations using the mechanical strain of a semiconductor as in the past, but uses the superconductor 2 and its Meissner effect to detect minute vibrations in one-dimensional to three-dimensional directions. This allows accurate detection.

[Example] Example 1 FIG. 1 shows the configuration of a minute vibration detector of this example. 1
is a Sm-Co magnet with an outer diameter of 10 cm and an inner diameter of 2 cm.
It is ring-shaped. 2 is Y 1 B a 2 Cu
z O? -X superconductor, processed into a spherical shape with a diameter of 1.6 cm, and has a critical temperature of about 90°C. When the inside of the dotted line in FIG. 1 is cooled down to about 77°C by a cooling device (not shown), the superconductor 2 floats as shown in FIG. 1 due to the Meissner effect. This superconductor 2 has a laser diode 3
The cylindrical lens 4 irradiates the light 7 from the cylindrical lens 4 by changing the shape of the illumination into a line. Here, laser diode 3,
The cylindrical lens 4 and the photodetector 5 are fixed with the same structure so that their relative positions do not change.

When there is no vibration, a portion of the light 7 is reflected by the superconductor and does not reach the photodetector 5, but the unreflected light is detected by the photodetector 5. This photodetector has many optical sensors arranged in the X direction, and if the superconductor moves in the X direction, the movement can be detected by light that is not reflected by the superconductor. . When vibration occurs, the magnet 1 is displaced by the vibration, but the superconductor does not change its position due to inertia immediately after the vibration occurs. This means that
Since the relative position of the superconductor and the magnet changes due to the vibration, the vibration can be detected by changing the position of the light detected by the photodetector 5. The amplitude of the vibration that can be detected is determined by the distance between the optical sensors arranged in the optical detector 5, and is 100 μm.
When placed at intervals, a change of 100 μm is changed to 10 μm.
When arranged at intervals, a change of 10 μm can be detected.

Example 2 In FIG. 1, the light irradiation source 3 is a halogen lamp, and the light from the halogen lamp is converted into parallel light by an optical system 4 using a glass lens. Further, optical sensors are arranged two-dimensionally to form a photodetector 5. With this configuration, minute vibrations in two-dimensional directions, that is, in the xy force direction in FIG. 1, could be detected.

Embodiment 3 FIG. 2 shows a configuration diagram of a minute vibration detector of this embodiment. 1
゛ is a magnet processed into a ring shape, and in this example, the outer diameter is 10 mm and the inner diameter is 3 mm.

A Sm-Co magnet with a thickness of 1 mm was used. 2 is the same oxide superconductor as in Example 1, and has an outer diameter of 15 mm, an inner diameter of 5 mm, and a thickness of 1 mm. The superconductor 2 is cooled by a cooling device (not shown). The cooling temperature may be lower than the critical temperature of the superconductor, about 90°C, but in this example it is 70°C. With such a configuration, minute changes could be detected in the same manner as in Example 2.

Embodiment 4 FIG. 3 shows a configuration diagram of a minute vibration detector of this embodiment. 1
is the same magnet as in Example 1, and 2 is 13 mm in diameter and 2 mm in thickness.
This is a disc-shaped superconductor made of the same material as in Example 1.

3.4 and 5 are the same optical systems as in Example 2. Also,
Although not shown in FIG. 3, the same optical system as in 3.4 and 5 is also arranged in the direction perpendicular to the plane of the paper. 3° is
The semiconductor laser 5゛ is a two-dimensional optical sensor.

By cooling the superconductor as in Example 1, the superconductor levitates due to the Meissner effect. 3. Displacements in the Z and X directions are detected by the optical systems 4 and 5, and displacements in the 2 and X directions, as well as in the 3' and The optical system 5' detects the inclination of the superconductor from the horizontal direction (xy plane). By comprehensively analyzing the data from each photodetector, microvibrations in three-dimensional directions can be detected simultaneously.

Embodiment 5 FIG. 4 shows a configuration diagram of a minute vibration detector created by applying semiconductor processing technology. The basic configuration is almost the same as in Example 2, but the superconductor 2 is made of YI Ba2Cus produced by a thin film production technique, for example, cluster ion beam evaporation method.
o, -X thin film.

Reference numeral 11 denotes a substrate for forming a superconducting thin film, and in the present invention, an MgO single crystal of 1 inch square and 0.5 mm thick was used. The superconducting thin film was made using Y, BaO, and Cu as evaporation materials. Y and BaO were evaporated with an ionization current of 100 mA and an acceleration voltage of IKV, and Cu was evaporated with an ionization current of 200 mA and an acceleration voltage of 2KV using different cluster ion guns. The substrate temperature was 200° C., and after film formation, heat treatment was performed at 900° C. for 1 hour in an oxygen atmosphere.

The obtained thin film had a film thickness of 2 μm, and the electrical resistance became zero at low temperature due to 88. Thereafter, it was processed into a disk shape with an outer diameter of 200 μm and an inner diameter of 50 μm using photolithography technology. On the other hand, the Sm-co magnet 1'' to be levitated was fabricated by sputtering on a quartz glass substrate 11''. The thickness is 3 μm. In the same way as superconductor 2, this is processed into a disk shape with an outer diameter of 100 μm and an inner diameter of 20 μm.

Microvibrations in two-dimensional directions could be detected in the same manner as in Example 2 using the superconductor 2 and magnet 1'' thus produced.

[Effects of the Invention] As explained above, according to the present invention, by utilizing the Meissner effect of a superconductor, it has become possible to simultaneously detect minute vibrations in one to three dimensional directions. In the present invention,
The superconductor or magnet levitated by the Meissner effect does not come into contact with other parts of the detector, so there is no performance deterioration due to mechanical fatigue.Furthermore, vibrations are detected optically in x, y, and two directions. The detection resolution of
．． A relative change of about 0.018°C can be detected.

Furthermore, the size of the detector can be reduced by applying semiconductor processing technology, and its limits are similar to the microprocessing limits of semiconductors.

[Brief explanation of drawings]

1 to 4 are configuration diagrams of the minute vibration detector of the present invention. FIG. 5 is a configuration diagram of a conventional detector. 1: Magnetic circuit 1″: Magnet 2: Superconductor 3.3°: Light irradiation source 4: Optical system 5.5′: Photodetector 6: Cooling part
7: Ray 8: Deflection part 9: Substrate

Claims (1)

[Scope of Claims] 1. A minute vibration detector characterized by having a magnetic circuit for levitating a superconductor by the Meissner effect, a levitated superconductor, and an optical position detection mechanism. 2. The minute vibration detector according to claim 1, wherein the superconductor is spherical. 3. The minute vibration detector according to claim 1, wherein the superconductor is plate-shaped, rod-shaped, or a processed body thereof. 4. The minute vibration detector according to claims 1, 2 and 3, wherein the optical position detection mechanism includes a light irradiation source and a light sensor. 5. The minute vibration detector according to claims 1, 2, 3, and 4, wherein the optical position detection mechanism has a light irradiation source from one, two, or three directions. 6. A microvibration detector comprising a superconductor, a magnet levitated by the Meissner effect of the superconductor, and an optical position detection mechanism. 7. The minute vibration detector according to claim 6, wherein the optical position detection mechanism includes a light irradiation source and a light sensor. 8. The minute vibration detector according to claims 6 and 7, wherein the optical position detection mechanism has a light irradiation source from one, two, or three directions.