JPH0799389B2 - Magnetic detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention uses a magnetoresistive element made of a superconducting material to detect a weak magnetic field due to, for example, biomagnetism or rock magnetism. Regarding the device.

<Prior Art> An example of such a magnetic detection device is shown in FIG. This magnetic detection device detects the magnetic field strength as a change in resistance value by utilizing the phenomenon that a superconductor moves from a superconducting state to a state having electric resistance due to a magnetic field. That is, the current electrodes 62a and 62a are connected to the ceramic superconductor 61.
By passing a current through b and measuring the voltage between the voltage electrodes 63a and 63b, the magnetic field acting between the voltage electrodes is detected as a change in resistance between the voltage electrodes. FIG. 7 shows the electric resistance characteristics with respect to this magnetic field for various current values. The characteristic shown in FIG. 7 is an example of the characteristic in the case of a rod-shaped ceramic superconductor, but this characteristic can be widely changed depending on the shape, composition, manufacturing process, etc. of the superconducting material.

This is not only the case where the superconductor is rod-shaped or plate-shaped,
The same applies to the case where an extremely thin superconductor is formed on a non-magnetic insulating plate, such as an alumina plate, by silk screen or spraying, and the resistance characteristics against a magnetic field can be drastically changed depending on the film thickness, electrode pattern width, composition, etc. it can.

FIG. 8 shows a magnetic detection device having a magnetoresistive element in which a superconductor 81, current electrodes 82a and 82b, and voltage electrodes 83a and 83b are formed by screen printing on such an insulating substrate. In the case of this magnetoresistive element, the resistance change with respect to the magnetic field can be made larger than that of the rod-shaped or plate-shaped magnetoresistive element, and the variation in characteristics can be reduced. Further, it is needless to say that the resistance characteristic with respect to the magnetic field can be changed by changing the composition, particle size, and manufacturing process of the superconductor 81. Even if these are kept constant, the length l and width W of the superconducting pair 81,
The characteristics can be widely changed by changing the thickness d.

FIG. 9 shows an example in which this characteristic changes. Here, the characteristic C is a characteristic when both the width W and the thickness d are made larger than the characteristic D. However, if the magnetic field is made sufficiently large, that is, the resistance value in the normal conducting state instead of the superconducting state, the length l is increased so that the characteristic C and the characteristic D have similar values. ing.

As described above, in the magnetic detection device, the resistance characteristics represented by the characteristics C and D of FIG. 9 are obtained. However, in the case of the characteristic D, the sensitivity is improved in a region where the magnetic field B is small because the change in the resistance R is large with respect to the change in the magnetic field, but there is a problem that the measurable magnetic field region becomes narrow because the resistance is saturated in a small magnetic field. is there. On the other hand, in the case of the characteristic C, there is no sensitivity in a region where the magnetic field is weak because the resistance is zero, and in the region of the magnetic field where the resistance appears, the resistance changes to a wide region of the magnetic field. Although the magnetic field area can be widened, there is a problem that the resistance changes little with respect to the change of the magnetic field and the sensitivity is poor.

Therefore, conventionally, by making a series connection of magnetoresistive elements made of a superconducting material and having different characteristics (JP-A-56-34130), or by partially changing the width of an integral magnetoresistive element made of a superconducting material, , In which magnetoresistive elements having substantially different characteristics are connected in series (JP-A-56-34132)
Is proposed.

For example, if the magnetoresistive element having the characteristic C and the magnetoresistive element having the characteristic D shown in FIG. 9 are installed close to each other so that substantially the same magnetic field acts, and if they are connected in series, the resistance to the magnetic field is increased. The characteristic becomes like the characteristic E. That is, the composite characteristic E slightly bends near the rising magnetic field of the characteristic C of FIG. 9, but the measurable region of the magnetic field is wider than that of the characteristic D. Further, compared to the characteristic C, the sensitivity is particularly good in a region where the magnetic field is small. Therefore, it is possible to obtain a magnetic detection device having high sensitivity and a wide measurable region.

<Problems to be Solved by the Invention> However, since the characteristics of the above-described conventional magnetoresistive element are largely influenced by the widths and the ratios of the respective parts to be connected in series, there is a problem that it is difficult to control the element design and manufacturing process. . Further, there is a problem that the magnetic field generated by the current for measuring the resistance disturbs the magnetic field distribution to be detected.

Therefore, an object of the present invention is to provide a magnetic detection device that has high sensitivity, a wide measurable magnetic field region, can be easily designed and manufactured, and does not disturb the magnetic field distribution to be detected.

<Means for Solving the Problems> In order to achieve the above object, the magnetic detection device according to claim 1 is a magnetic detection device that measures a magnetic field using a magnetoresistive element having a superconducting material. A shield member for shielding a part of the magnetic field acting on the magnetoresistive element is provided in a part of the above.

Further, in the magnetic detection device according to claim 2, a magnetoresistive element having a superconducting material is provided in a strip shape on the surface of a substrate made of a nonmagnetic material, and the magnetoresistive element is provided between one end side and the other end side of the magnetoresistive element. In the magnetic detection device adapted to measure the magnetic field by energizing the magnetic resistance element, the magnetoresistive element includes a portion extending from the one end side to a central portion in a substantially spiral shape, and the portion passing through a gap between the central portion and the portion. And a portion extending in the opposite direction to the other end side.

Further, in the magnetic detection device according to claim 3, a magnetoresistive element having a superconducting material is bent and provided in a strip shape on the surface of a substrate made of a nonmagnetic material, and one end side and the other end of the magnetoresistive element are provided. In the magnetic detection device adapted to measure a magnetic field by energizing between the side and the side, the magnetoresistive element includes a current flowing in a bent adjacent portion including the one end side on one surface of the substrate. Has a first portion having a pattern in which the direction of is opposite, and through the through hole provided in the substrate on the other surface of the substrate, the side opposite to the one end side of the first portion. Is characterized by having a second portion which is connected to the end portion of and has a pattern obtained by projecting the pattern of the first portion.

<Operation> In the magnetic detection device of the first aspect, the shield member shields a part of the magnetic field acting on a part of the magnetoresistive element. As a result, the shielded portion and the unshielded portion of the magnetoresistive element show different electric resistances. That is,
The magnetic resistance elements having different characteristics are connected in series, and the total electric resistance is the sum of the electric resistance of the shielded portion and the electric resistance of the unshielded portion.
Therefore, the magnetic detection sensitivity is improved and the measurable magnetic field region is widened as compared with the rod-shaped structure. Moreover, since only the shield member is provided, it can be easily designed and manufactured.

Further, in the magnetic detection device of the second aspect, since the magnetoresistive element has a substantially spiral pattern, a long current path is formed in a relatively narrow area on the substrate surface. Therefore, the electric resistance can be increased and the magnetic detection sensitivity can be improved as compared with the conventional case. In addition, currents flow in opposite directions to the adjacent portions of the magnetoresistive element. Therefore, the magnetic fields generated by the currents cancel each other out, and the magnetic field distribution to be detected is not disturbed. Also, because it does not disturb the magnetic field,
The measurable magnetic field area becomes wider. It should be noted that current paths flowing in opposite directions, that is, a portion from one end side of the magnetoresistive element to the central portion and a portion from the central portion to the other end side are adjacent to each other over the entire path including the end portion. Therefore, the effect of not disturbing the magnetic field distribution is extremely large.

Further, in the magnetic detection device according to the third aspect, since the magnetoresistive element is bent in each of the first portion and the second portion on both surfaces of the substrate, a relatively small area on the substrate surface. Then, a long current path is formed. Therefore, the electric resistance can be increased and the magnetic detection sensitivity can be improved as compared with the conventional case. In addition, current flows in opposite directions to the adjacent portions of the magnetoresistive element on each surface of the substrate. Moreover, on the one surface and the other surface of the substrate, currents flow in opposite directions to each other in the first portion and the second portion. Therefore, the magnetic fields generated by the currents cancel each other out, and the magnetic field distribution to be detected is not disturbed. In addition, since the magnetic field is not disturbed, the measurable magnetic field region is widened. In addition, the current paths that flow in opposite directions, that is, the first portion and the second portion,
Since they are adjacent to each other over the entire path including the end portions, the effect of not disturbing the magnetic field distribution is extremely large as in the magnetic detection device according to the second aspect.

<Example> Hereinafter, the present invention will be described in detail with reference to illustrated examples.

FIG. 3 shows a schematic configuration of the magnetic detection device of the first embodiment. This magnetic detection device includes a superconductor 21 forming a part of a magnetoresistive element on a substrate 23 made of a nonmagnetic dielectric material.
Are provided in a predetermined pattern. A shield member 24 for shielding a part of the magnetic field acting on the superconductor 21 is provided on the right half of the superconductor 21 in the figure. A magnetic material or a superconductor is used as the shield member 24,
The magnetic shield effect of the magnetic substance or the magnetic shield effect of the Meissner effect of the superconductor is used.

As shown in FIG. 2, in the magnetoresistive element, a superconductor 21 having a constant width is formed on a substrate 23 so as to be bilaterally symmetric with respect to a constant chain line in the central portion. A resistance measuring terminal 22 is provided. The entire superconductor 21 is made of superconductors having the same characteristics.

With this configuration, the magnetic field acting on the portion of the superconductor 21 shielded by the shield member 24 is reduced, which is equivalent to the case where two types of superconductors having different resistance characteristics are connected in series as a whole. For example, the non-shielded portion exhibits the characteristic like the characteristic D shown in FIG. 9, the shielded portion exhibits the characteristic like C, and the characteristic E as a whole is obtained. That is, the total electric resistance is the sum of the electric resistance of the shielded portion and the electric resistance of the unshielded portion. Therefore, the magnetic detection sensitivity is improved, and the measurable magnetic field region is widened, as compared with the structure that is not in series. Moreover, this magnetic detection device
Since only the shield member is provided in the conventional structure, it can be easily designed and manufactured.

In this example, a part of the magnetic field acting on the superconductor 21 is shielded, but the same effect can be obtained by placing a sparse mesh made of a magnetic material or a plate having low magnetic permeability in the vicinity of the substrate 23. In this case, the measurable magnetic field region can be further widened by changing the mesh size and material of the mesh, the wire diameter, the thickness of the shield plate, and other factors that cause the shielding property.

The superconductor 21 shown in FIG. 2 is composed of superconductors of the same characteristic formed symmetrically on the substrate 23. However, two kinds of superconductors having different characteristics or three or more kinds of superconductors having different characteristics are used. It may be configured by the body.

The magnetoresistive element may be configured as shown in FIG. In this magnetoresistive element, superconductors 11 having patterns of different widths are formed in series on a substrate 13, and resistance measuring terminals 12 are provided at both ends of the superconductor 11. In this case, the composition, manufacturing process and thickness of the magnetoresistive element are constant,
These may be changed for each pattern.

In the magnetoresistive element shown in FIGS. 1 and 2, superconductors having different characteristics per unit length are formed in series on the same plane of the substrate. The body may be formed and these superconductors may be connected in series. Alternatively, a plurality of small substrates on which superconductors having different characteristics are formed may be prepared, these substrates may be bonded onto one substrate, and each superconductor may be connected by wire bonding or the like.

In the magnetoresistive element shown in FIGS. 1 and 2, resistance measuring terminals are provided at both ends of the superconductor, and the resistance measuring terminals also function as current electrodes and voltage electrodes. As shown, the current electrode and the voltage electrode may be provided separately.

The above is the description of the case of the magnetoresistive element in which the film-shaped superconductor is generated on the substrate, but the present invention is not limited to this, and the bar-shaped, linear or plate-shaped superconductor may be used. It may be a combination of superconductors of different forms, such as a combination of the ones and the rod-shaped ones.

When a plurality of magnetoresistive elements having different resistance characteristics with respect to a magnetic field are connected in series, when an element of characteristic C and an element of characteristic D are connected in series as shown in FIG. As described above, it is possible to obtain an element with improved characteristics. However, even when a plurality of elements having the same characteristics, for example, characteristics D, are connected in series, the change in resistance with respect to the change in magnetic field becomes large, and It can be seen that is improved.

Connecting the elements having the same characteristics in series is, for example, the eighth method.
In the magnetoresistive element shown in the figure, it is equivalent to making the width W and the thickness d the same and increasing the length l. However, if l is simply increased, it is difficult to place it in the same magnetic field, which causes a problem in measurement accuracy. Therefore, for example, it is necessary to fold the superconducting material on the substrate into a strip shape to make the detection unit small.

However, in this case, the magnetic field generated by the current passed to measure the resistance may disturb the magnetic field distribution to be detected.

Therefore, next, the magnetic detection devices of the second and third embodiments having a pattern in which the directions of the currents flowing through the adjacent portions are opposite to each other will be described.

FIG. 4 shows a magnetoresistive element included in the magnetic detector of the second embodiment. This magnetoresistive element includes a detection unit 41 made of a superconducting material on the surface of a non-magnetic dielectric substrate (not shown).
Is bent to create a strip. As shown in the figure, the detection unit 41 includes a portion that extends from one end side to the center portion in a substantially spiral shape, and a portion that extends from the center portion to the other end side through the gap between the portions and opposite to the above portion. Have Terminal portions 42, 42 are provided at both ends of the detection portion 41.

Since the detection unit 41 of the magnetoresistive element has a substantially spiral pattern in this manner, a relatively small area on the substrate surface
A long current path can be formed. Therefore, the electric resistance can be increased and the magnetic detection sensitivity can be improved as compared with the related art. In addition, currents flow in opposite directions to the adjacent portions of the magnetoresistive element. Therefore, the magnetic fields generated by the currents cancel each other out and do not disturb the magnetic field distribution to be detected. Moreover, since the magnetic field is not disturbed, the measurable magnetic field region can be widened. Since the current paths that flow in opposite directions are adjacent to each other over the entire path including the end portions 42, 42, the effect of not disturbing the magnetic field distribution can be extremely increased.

The terminal portion 42 is wider than the detecting portion 41 in order to reduce the current density of the terminal portion 42 and reduce the resistance generated by the magnetic field. With such a structure, the magnetic field strength of the terminal portion 42 does not enter the measurement value for the magnetic field strength of the detection portion 41 as an error.

FIG. 5 shows a magnetoresistive element included in the magnetic detector of the third embodiment. In this magnetoresistive element, a superconductor 51a shown by a solid line as a first portion is bent and formed in a strip shape on the surface of a non-magnetic dielectric substrate (not shown), and
On the back surface of the substrate, a superconductor 51b shown by a dotted line as a second portion is bent to form a strip shape. Specifically, the pattern of the superconductor 51a is the same as that of the detection unit 41 of FIG.
The resistance measuring terminal 52a is provided with a portion that extends from one end side to a central portion in a substantially spiral shape, and a portion that extends from the central portion through a gap between the portions to the other end side in the opposite direction to the above portion. There is. The superconductor 51b is connected to the other end side of the superconductor 51a (the end opposite to the resistance measuring element 52a) through a through hole 53 provided in the substrate, and has a pattern in which the pattern of the superconductor 51a is projected. ing. That is, although the superconductors 51a and 51b are drawn with a shift for convenience of drawing, they are made to be symmetrical with respect to the front and back of the substrate, respectively. Further, an end portion of the superconductor 51b, which is symmetrical with one end side of the superconductor 51a,
It is connected to a resistance measuring terminal 52b provided on the back surface of the substrate.

In this way, since the superconductors 51a and 51b are bent on both surfaces of the substrate, a long current path can be formed in a relatively narrow area on the substrate surface. Therefore,
The electric resistance can be increased and the magnetic detection sensitivity can be improved as compared with the conventional case. In addition, currents flow in opposite directions to the adjacent portions of the superconductors 51a and 51b on each surface of the substrate. Moreover, on the front surface and the back surface of the substrate, currents flow in opposite directions in the portions of the superconductor 51a and the superconductor 51b which face each other. Therefore, the magnetic fields generated by the currents cancel each other out and do not disturb the magnetic field distribution to be detected. Moreover, since the magnetic field is not disturbed, the measurable magnetic field region can be widened. Since the current paths that flow in the opposite directions are adjacent to each other over the entire path including the end portions 52a and 52b, the effect of not disturbing the magnetic field distribution should be made extremely large as in the magnetic detection device of the second embodiment. You can

By forming the patterns shown in FIGS. 4 and 5 in this manner, it is possible to eliminate the influence of the magnetic field generated by the current and obtain a magnetoresistive element having a wide measurement range and high sensitivity.

<Effects of the Invention> As is clear from the above, in the magnetic detection device according to claim 1, since the shield member shields a part of the magnetic field acting on a part of the magnetoresistive element, the shielded part of the magnetoresistive element. And the unshielded portion show different electric resistances. As a result, the magnetic detection sensitivity can be improved and the measurable magnetic field region can be widened as compared with the rod-shaped structure. Moreover, since only the shield member is provided, it can be easily designed and manufactured.

Further, in the magnetic detection device of the second aspect, since the magnetoresistive element has a substantially spiral pattern, a long current path can be formed in a relatively narrow area on the substrate surface. Therefore, the electric resistance can be increased and the magnetic detection sensitivity can be improved as compared with the related art. In addition, since currents flow in opposite directions in the adjacent portions of the magnetoresistive element, the magnetic fields generated by the currents cancel each other out, and the magnetic field distribution to be detected is not disturbed. Moreover, since the magnetic field is not disturbed, the measurable magnetic field region can be widened. It should be noted that current paths flowing in opposite directions, that is, a portion from one end side of the magnetoresistive element to the central portion and a portion from the central portion to the other end side are adjacent to each other over the entire path including the end portion. Therefore, the effect of not disturbing the magnetic field distribution can be made extremely large.

Further, in the magnetic detection device according to the third aspect, since the magnetoresistive element is bent in each of the first portion and the second portion on both surfaces of the substrate, a relatively small area on the substrate surface. In addition, a long current path can be formed. Therefore, the electric resistance can be increased and the magnetic detection sensitivity can be improved as compared with the related art. In addition, current flows in opposite directions to the adjacent portions of the magnetoresistive element on each surface of the substrate. Moreover, on the one surface and the other surface of the substrate, currents flow in opposite directions to each other in the first portion and the second portion. Therefore, the magnetic fields generated by the currents cancel each other out and do not disturb the magnetic field distribution to be detected. Moreover, since the magnetic field is not disturbed, the measurable magnetic field region can be widened. The current paths that flow in the opposite directions, that is,
Since the first portion and the second portion are adjacent to each other over the entire path including the end portion, the effect of not disturbing the magnetic field distribution can be extremely increased, as in the magnetic detection device according to the second aspect.

[Brief description of drawings]

FIG. 1 is a diagram showing a magnetoresistive element included in the magnetic detector of the first embodiment, FIG. 2 is a diagram showing a magnetoresistive element included in the magnetic detector of the first embodiment, and FIG. It is a figure which shows schematic structure of the magnetic detection apparatus of an Example. FIG. 4 is a diagram showing a magnetoresistive element included in the magnetic detection device of the second embodiment,
FIG. 5 is a diagram showing a magnetoresistive element included in the magnetic detection device of the third embodiment. 6 and 7 are views showing a conventional rod-shaped superconducting magnetoresistive element and its characteristics,
8 and 9 are diagrams showing a conventional film-shaped superconducting magnetoresistive element and its characteristics, respectively. 11,21,41,51a, 51b …… Superconductor, 12,22,42,52a, 52b …… Resistance measuring terminal, 13,23 …… Board, 24 …… Shield member.

Claims (3)

[Claims] 1. A magnetic detection device for measuring a magnetic field using a magnetoresistive element having a superconducting material, wherein a shield member for shielding a part of a magnetic field acting on the magnetoresistive element is provided in a part of the magnetoresistive element. A magnetic detection device characterized by being provided. 2. A magnetic resistance element having a superconducting material is provided in a strip shape on the surface of a substrate made of a non-magnetic material, and a magnetic field is measured by energizing the magnetic resistance element between one end side and the other end side. In the magnetic detection device configured as described above, the magnetoresistive element includes a portion that extends substantially spirally from the one end side to a central portion, and the other end side that is opposite to the portion through a gap between the central portion and the portion. And a part extending to the magnetic detection device. 3. A magnetoresistive element having a superconducting material is bent and provided in a strip shape on a surface of a substrate made of a nonmagnetic material, and an electric current is applied between one end side and the other end side of the magnetoresistive element. In the magnetic detection device configured to measure a magnetic field, the magnetoresistive element includes the one end side on one surface of the substrate, and a direction of a current flowing through a bent adjacent portion is opposite. A first portion having a different pattern, and is connected to an end portion of the first portion opposite to the one end side through a through hole provided in the substrate on the other surface of the substrate. A magnetic detection device having a second portion having a pattern obtained by projecting the pattern of the first portion.