JPH01185463A - Magnetism detecting element - Google Patents

Abstract

PURPOSE:To improve the sensitivity of a magnetism detecting element and to prevent fluctuation due to temperature, by providing a superconductor and a piezoelectric body which detects the Lorentz force generated due to the Meissner effect as stress at one surface of the pressure receiving surfaces. CONSTITUTION:Electrodes 2 and 2 are deposited on two surfaces of a piezoelectric body 1 having a crystal structure by evaporation and the like. The two surfaces are arranged at aright angle to the crystal orientation where the piezoelectric effect of the piezoelectric body 1 appears most intensely. A superconductor 3 is deposited on one of the electrode 2 by the same way. The other electrode 2 is fixed to a fixing plate 4. When this element is placed in a magnetic field 8, a screening current which repels the magnetic field 8 flows in the surface of the conductor 3. Lorentz force is generated in the conductor 8 due to the Meissner effect and transmitted to the piezoelectric body 1. At this time, since one end of the piezoelectric body 1 is fixed 4, the transmitted Lorentz force becomes stress. The piezoelectric body 1 is contracted or expanded with the stress, and a potential is generated between the electrodes 2 and 2 which are disposed on both ends. The magnitude of the potential is detected with a voltmeter 7 through a lead wires 6. The intensity of the magnetism in the magnetic field 8 is measured as the voltage.

Description

[Detailed description of the invention] [Prior art and problems to be solved by the invention] Conventionally,
Many solid-state magnetic sensors use semiconductor elements, and these magnetic sensors typically utilize the Hall effect or magnetoresistive effect of semiconductors.

In addition, two superconducting quantum interference devices using Josephson junctions (Super Quantum Interfer
There is a magnetic sensor that uses ence device; 5QtllD) and has very high sensitivity.

However, these magnetic sensors consist of a magnetic detection section that detects magnetism and an electric circuit section that amplifies the detected signal, making the structure of the magnetic detection device complicated.

For example, in the 5QtllD magnetic sensor, an LC resonant circuit is arranged near a superconducting ring, and sensitivity to magnetism is increased and detected by amplifying changes in the Q of the C resonant circuit due to hysteresis of the ring current. In other words, as a magnetic sensor, the electric signal produced by only two superconducting rings using Josephson junctions is weak, and unless the detected magnetic electric signal is amplified with an LC resonator, the detected amount cannot be converted into an electric signal. It is difficult to extract the electric signal, and in order to minimize the attenuation of this electric signal, the C resonator must be placed near the sensor body, making the sensor configuration complicated.

Furthermore, the 5QUID magnetic sensor uses two superconductors using Gisefson junctions, but the elements themselves are minute, requiring advanced integrated circuit manufacturing technology to manufacture the elements, and the manufacturing cost is high. It has the disadvantage of being expensive.

On the other hand, a magnetic sensor that uses the Hall effect detects a magnetic field as a voltage change, but since this voltage change depends not only on the magnetic field but also on the element shape, it is difficult to obtain linearity in the relationship between the voltage and the magnetic field. InSb, InAs, etc. have low sensitivity as a sensor, and m-v materials such as InSb and InAs can be used as materials for Hall elements.
Semiconductors using group elements are the mainstream, but the Hall coefficients of these materials have a temperature dependence of about 0.05χ/°C, and this temperature fluctuation tends to cause errors in the measurement accuracy of the sensor.

In addition, in magnetic sensors that utilize the magnetoresistive effect, the magnetoresistive element itself has inherently low sensitivity to magnetic field strength.For example, InSb has sensitivity for the first time to a magnetic field of 0.15 Tesla or more, so the magnetoresistive effect Magnetic sensors using this technology are successful in measuring high magnetic fields. Therefore, for low magnetic field measurements, a bias magnetic field of about 0.1 to 0.2 Tesla is added.

Furthermore, this magnetic sensor requires an operating voltage on the order of IOV, and driving energy for the sensor must be constantly supplied, making the element configuration complicated.

Recently, magnetic sensors have been devised that utilize changes in electrical resistance due to magnetism in superconductors, but in this case, the relationship between the external magnetic field and electrical resistance is not linear, and the relationship can be determined based on the characteristics of the superconductor. Therefore, when using this as a magnetic sensor, it is necessary to know in advance the complex function between the external magnetic field and electrical resistance, which poses the problem of low utilization efficiency as a magnetic sensor. Ta.

The present invention has been made to solve these problems, and provides a magnetic sensing element that does not require a drive circuit or the application of an external bias magnetic field, has small temperature fluctuations, and has a simple manufacturing process, and its use. The purpose is to provide a method.

[Means to solve the problem]

The magnetic sensing element according to the present invention is characterized by sensing a superconductor and Lorentz force generated by the Meissner effect of the superconductor as stress on one or both of its pressure receiving surfaces, and the magnetic sensing element according to the present invention The device is characterized in that a plurality of the magnetic sensing elements are arranged in a one-dimensional, two-dimensional, or three-dimensional direction.

[Effect]

In the magnetic sensing element according to the present invention, the Lorentz force generated by the Meissner effect of the superconductor on magnetism is transmitted to the piezoelectric material, the stress generates a potential between the pressure-receiving surfaces of the piezoelectric material, and the generated potential is detected to detect the magnetic field. Detect strength.

Further, in the magnetic sensing device according to the present invention, the magnetic sensing elements are arranged in a two-dimensional or three-dimensional direction, and the distribution of magnetic strength in the two-dimensional or three-dimensional direction is detected.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof. FIG. 1 is a schematic diagram showing the configuration of a magnetic sensing element according to the present invention, and numeral 1 in the figure represents a piezoelectric material having a crystal structure.

Electrodes 2.2 are deposited by vapor deposition on each of the two planes perpendicular to the crystal orientation in which the piezoelectric effect of the piezoelectric body 1 appears most strongly, and a superconductor 3 is deposited or pasted on one of the electrodes 2. etc., and the other electrode 2 is fixed to the fixing plate 4. Further, a lead wire 6 is provided between the picture electrodes 2, 2, and the lead wire 6 is connected to a voltmeter 7.

The principle of magnetic detection by the magnetic sensing element configured as above will be explained below. When the magnetic sensing element is placed in the magnetic field 8, a shielding current that repulses the magnetic field 8 flows on the surface of the superconductor 3, and a Lorentz force is generated in the superconductor 3 due to this Meissner effect. In addition, the Lorentz force, the magnetic strength of the magnetic field 8, and ′
The relationship is a quadratic function.

Next, the Lorentz force generated in the superconductor 3 is transmitted to the piezoelectric body 1, but one side of the piezoelectric body 1 is fixed to the fixed plate 5, and the transmitted Lorentz force becomes stress and the piezoelectric body 1 As a result, a potential is generated between the electrodes 2 arranged on both sides of the piezoelectric body 1, and this potential is transmitted to the voltmeter 7 via the lead wire 6, and the magnitude of the potential is measured by the voltmeter 7. is detected.

That is, the potential generated in the piezoelectric body 1 is proportional to the stress applied to the piezoelectric body l from the superconductor 4, and the stress generated in the superconductor 3 is proportional to the square of the magnetic strength of the magnetic field 8. Magnetic strength is measured as a voltage.

Furthermore, when the magnetic field 8 is in the opposite direction, the direction of the potential generated in the piezoelectric body is reversed, so the direction of the magnetic field 8 can be detected by the deflection direction of the needle of the voltmeter 7.

Furthermore, if a plurality of such magnetic sensing elements are connected in series, the measured voltage is amplified and the sensitivity of the magnetic sensor is improved.

Furthermore, by arranging such magnetic sensing elements in two or three dimensions, it is possible to detect the magnetic field distribution in two or three dimensions.

Next, details of the magnetic sensing element of this example will be explained.

FIG. 2 is a diagram showing the detailed configuration of the magnetic sensing element according to the present invention, and 1 in 0 represents the voltage output coefficient. Made of large PZT ceramic fuchs, about 10 cranes in diameter and about 2 in length.
It is a cylindrical piezoelectric body of 0fi. As shown in the figure, two piezoelectric bodies 1 are arranged side by side with end faces having the same polarity facing each other with an electrode 5 interposed therebetween, and both ends of the piezoelectric bodies 1, 1 arranged in parallel are each coated with a thickness made of AI metal. Approximately 2 m of aluminum electrodes 2,2 are deposited. One aluminum electrode 2 is fixed to the bottom surface of a metal cylinder 10 with a diameter of 22 tm, and the other aluminum electrode 2 is fixed to a metal plate 11 whose peripheral edge is slidably inscribed in the metal cylinder 10. be done.

On the other hand, the weight ratio of BaCO31Cu20+ Y2O3 is 4
: Mixed in a ratio of 3:1, this mixed powder was pressed at it/-, and this was calcined in the air for 24 hours. This calcined material was crushed, mixed again and pressed with it/-, with a diameter of 24 mm.
After forming a disk-shaped superconductor 3 made of YBaCu oxide ceramics with a thickness of 6 fi, this superconductor 3
is sintered at 900° C. for 16 hours in air.

This superconductor 3 is bonded to the metal plate 11 using a mixture of metal and frit glass, and the bonded portion is heated to about 120° C. to fix it.

Further, a lead wire 6 is connected to the electrode 5 via an insulator 12, and the lead wire 6 and the lead wire 6 connected to the metal cylinder 10 are respectively connected to a terminal of a voltmeter 7.

Table 1 shows the relationship between the magnetic field and the induced potential in the magnetic sensing element formed as described above. Note that the temperature fluctuation at that time was 0.001 or less.

Therefore, if a circuit that calculates the magnetic field from the induced potential based on the quadratic relationship between the induced potential and the magnetic field as shown in Table 1 is connected to this sensing element, the magnetic strength can be read directly from the meter. can.

Table 2 also compares the characteristics of a magnetic sensor using the magnetic sensing element according to the present invention and a conventional magnetic sensor.

〔Effect of the invention〕

The magnetic sensing element of the present invention utilizes the Meissner effect of superconductors to increase the sensitivity of the element, and as is clear from the comparison in Table 2, it does not require a drive circuit or an external bias circuit.
The manufacturing process of the device is simple, and furthermore, it has excellent effects such as small temperature fluctuations.

Table 1 Table 2

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams showing the structure of a magnetic sensing element according to the present invention. 1... Piezoelectric body 2... Aluminum electrode 3...
Superconductor 4... Fixed plate 5... Electrode 6... Lead wire 7... Voltmeter 8... Magnetic field patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono 22

Claims (1)

[Claims] 1. A magnetic sensing element comprising a superconductor and a piezoelectric body that senses the Lorentz force generated by the Meissner effect of the superconductor as stress on one or both of its pressure-receiving surfaces. 2. A superconductor and one of its pressure-receiving surfaces using the Lorentz force generated by the Meissner effect of the superconductor as stress.
1. A magnetic sensing device comprising a plurality of magnetic sensing elements each having a piezoelectric body that senses on one or both sides arranged in one, two or three dimensions.