JPH09257898A - Magnetoelectric transducer, manufacture of the transducer and magnetic sensor using the transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetoelectric transducer having a thin thickness and a small-sized magnetic sensor using the transducer. SOLUTION: This magnetoelectric transducer 20 is integrally constituted by adhering a soft magnetic board 5 formed with a magnetoresistance effect film 1 to a hard magnetic board 6 made of a rare earth element and the like for applying a bias magnetic field and laminating it. Thus, since the transducer 20 contains a hard magnetic material for applying the bias magnetic field and is integrated, the thickness can be reduced, and a small-sized magnetic sensor can be constituted.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a magnetoelectric conversion element and a magnetic sensor using the same.

[0002]

2. Description of the Related Art A conventional magnetoelectric conversion element and a magnetic sensor using the same will be described with reference to FIGS. FIG. 3 is a sectional view of a conventional magnetoelectric conversion element 30, and FIG. 4 is a partial sectional view of a magnetic sensor 40 using the magnetoelectric conversion element 30.

As shown in FIG. 3, a conventional magnetoelectric conversion element 30 has a magnetoresistive effect film 1, and one main surface of the magnetoresistive effect film 1 is bonded to a soft magnetic substrate 5 by a resin layer 4. , A plurality of short-circuit films 2, 2 ,. . . 2 are formed, and the magnetoresistive effect film 1 and a plurality of short-circuit films 2, 2. . . A protective film 3 is formed on the upper surface of 2,
Further, a soft magnetic material plate 5 is adhered to the protective film 3 by a resin layer 4, and an input electrode 7a and an output electrode 7b for extracting a change in resistance value are connected to both ends of the magnetoresistive film 1, respectively.

The magnetoresistive film 1 is formed by a thin film forming technique and has a thickness of 100 μm or less, so that its strength is very small. In order to reinforce the thin magnetoresistive effect film 1, the magnetoresistive effect film 1 is bonded to the soft magnetic substrate 5 as described above. The thickness of this soft magnetic substrate 5 is 5
Those having a diameter of 00 μm or more are used. Further, in order to concentrate the magnetic field on the magnetoresistive effect film 1, the magnetoresistive effect film 1 is sandwiched by two soft magnetic material plates 5.

As shown in FIG. 4, the magnetic sensor 40 has magnets 8a and 8b attached to both main surfaces of a plate-like holding portion 11 by an adhesive agent 14, and further magnets 8a and 8b.
On the outer main surface of each of the
0 and 30 are attached by an adhesive 14, the whole is housed in a case 15, and then a resin 17 is enclosed.

Lead wires 13, 13, 13 are respectively connected to the electrodes 7a, 7b of the two magnetoelectric conversion elements 30, respectively.
13 is connected.

The magnets 8a and 8b are made of an oxide-based ferrite material such as strontium ferrite, and it is necessary to increase the permeance coefficient in order to apply a sufficiently large bias magnetic field to the magnetoelectric conversion elements 30 and 30 without demagnetization. Therefore, the one having a large thickness is used.

The magnetic sensor 40 is used, for example, to check the corrosion state of the inner wall of a thin tube used in a heat exchanger of a nuclear power plant. The usage method will be described below.

First, the magnetic sensor 40 is inserted into the thin tube and the resistance value of each magnetoelectric conversion element 30 is measured. From the measured value, the distance between each magnetoelectric conversion element 30 and the magnetic metal that is the object to be measured is calculated. If the inner wall of the thin tube is not corroded, the inner wall of the thin tube (made of magnetic metal) itself is the object to be measured, and if the inner wall of the thin tube is corroded, the corroded material bulging toward the center of the thin tube. The object to be measured is made of magnetic metal.

In this way, the distance between one magnetoelectric conversion element 30 measured from the resistance value of the magnetoelectric conversion element and the object to be measured located near the magnetoelectric conversion element 30, and the other magnetoelectric conversion element. By adding the distance between the element 30 and the object to be measured located in the vicinity of the magnetoelectric conversion element 30 and the previously known distance between the magnetoelectric conversion elements 30 to each other, the function in the thin tube can be improved. The inner diameter of the existing portion, that is, the inner diameter that functions to pass the liquid such as water in the heat exchanger can be calculated. That is, when the inner wall of the thin tube is not corroded, the inner diameter of the functioning part in the thin tube is the same as the inner diameter of the thin tube, and the inner wall of the thin tube corrodes and corrosive matter bulges toward the center of the thin tube. The inner diameter of the functioning part in the thin tube is smaller than the inner diameter of the thin tube. By calculating the inner diameter of the functioning part of the thin tube, the thickness of the corrosive material bulging toward the center of the thin tube can be recognized.

A thin tube used for a heat exchanger of a nuclear power plant is replaced with a new one when the corroded material on its inner wall exceeds a certain thickness.

[0012]

However, in the conventional magnetic sensor 40, two magnets 8a, 8b made of an oxide ferrite material such as strontium ferrite are used.
However, since it is housed in the case 15 together with the magnetoelectric conversion element 30, there is a problem that the shape is large. Therefore, a thin tube such as that used in a heat exchanger of a nuclear reactor cannot be used as the object to be detected.

[0013]

Means for Solving the Problems The magnetoelectric conversion element according to claim 1 of the present invention is a magnetoelectric conversion device comprising two sets of sensing portions each having a plurality of short-circuit films intermittently formed on a magnetoresistive effect film. In the element, the two sets of detection portions are arranged on the front surface and the back surface of a hard magnetic substrate made of a rare earth magnet, respectively.

In the method of manufacturing a magnetoelectric conversion element according to a second aspect of the present invention, the two sets of detection portions formed by intermittently forming a plurality of short-circuit films on the magnetoresistive film are made of a rare earth magnet. In a method of manufacturing a magnetoelectric conversion element arranged on a front surface and a back surface of a hard magnetic substrate, respectively, a hard magnetic body made of a rare earth magnet after detecting portions are respectively arranged on the front surface and the back surface of a hard magnetic substrate made of a rare earth magnet. It is characterized in that the substrate is vertically magnetized.

The magnetic sensor according to claim 3 of the present invention comprises:
The magnetoelectric conversion element according to claim 1 is housed in a case.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A magnetoelectric conversion element of the present invention and a magnetic sensor using the same will be described with reference to FIGS. 1 is a sectional view of the magnetoelectric conversion element 20, and FIG. 2 is a magnetic sensor 50.
FIG. The same parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 1, the magnetoelectric conversion element 20 of the present invention comprises a hard magnetic substrate 6 on one main surface, a soft magnetic substrate 5 and a resin layer 4 on one main surface of the magnetoresistive effect film 1. Surface is adhered and a plurality of short-circuit films 2, 2. . . 2 are formed, and the magnetoresistive effect film 1 and a plurality of short-circuit films 2, 2. . . A protective film 3 for protecting the protective film 2 is formed, and the resin film 4 adheres the metal magnetic substrate 9 to the protective film 3 by the resin layer 4.

Further, on the other main surface of the hard magnetic substrate 6,
In the reverse order to the above, the metal magnetic substrate 9, the protective film 3,
A plurality of short-circuit films 2, 2. . . 2. The magnetoresistive film 1 and the soft magnetic substrate 5 are adhered via the resin layer 4.

Furthermore, insulating layers 10 and 10 are provided on the end faces of the metal magnetic substrate 9 and 9 and the magnetoresistive effect films 1 and 1, respectively, and electrically connected to both ends of one magnetoresistive effect film 1. The input electrode 7a and the output electrode 7b are also electrically connected to both ends of the other magnetoresistive film 1, respectively.

The metal magnetic material plate 9 is a low coercive force magnetic material made of a silicon steel plate, pure iron, soft iron, etc.
When magnetized, it has the effect of concentrating the magnetic field. Therefore, the output is larger when the magnetoresistive effect element is laminated via the metal magnetic material 9 than when it is directly laminated on the rare earth hard magnetic material substrate. This is because the amount of change in the magnetic flux density becomes larger when the element is located at the set distance than the magnetized surface of the hard magnetic substrate.

Since the metal magnetic substrate 9 and the hard magnetic substrate 6 have electrical conductivity, the insulating layers 10 and 10 are required on their respective end faces.

Next, a method of manufacturing the magnetoelectric conversion element 20 will be described.

First, a bulk made of InSb or the like is adhered to a soft magnetic substrate 5 with a resin layer 4, the bulk is polished and processed into a predetermined shape to form a magnetoresistive film 1, and its magnetoresistive effect is obtained. The short-circuit film 2 is intermittently formed on the surface of the effect film 1,
2. . . 2 are formed, and the magnetoresistive effect film 1, the short-circuit film 2, 2. . . 2 is formed with a protective film 3, and the protective film 3 is formed.
Two sets are prepared by adhering the metal magnetic substrate 9 with the resin layer 4 thereon.

Next, these are adhered to the front and back surfaces of the hard magnetic substrate 6 by the resin layer 4.

Next, the insulating layers 10 and 10, the input electrodes 7a and 7c, and the output electrodes 7b and 7d are formed.

Next, the hard magnetic substrate 6 is vertically magnetized to manufacture the magnetoelectric conversion element 20.

The hard magnetic substrate 6 constituting the magnetoelectric conversion element 20 of the present invention is formed of a rare earth magnet such as samarium cobalt, and has a large permeance coefficient as compared with an oxide ferrite material, and a maximum. Energy
Since the product is high, demagnetization does not occur even if the thickness is reduced, and a sufficiently large bias magnetic field can be applied to the magnetoresistive effect film 1. Therefore, the thickness of the magnetoelectric conversion element 20 including the hard magnetic substrate 6 for applying the bias magnetic field can be reduced.

A magnetic sensor 50 using the magnetoelectric conversion element 20 of the present invention will be described with reference to the partial sectional view of FIG.

As shown in the figure, in the magnetic sensor 50, the magnetoelectric conversion element 20 is placed on the holding portion 12, and is inserted into the center of the case 16 having a cylindrical shape together with the holding portion 12.
The resin 17 is enclosed. Further, the input electrode 7a, the output electrode 7b, the input electrode 7c, and the output electrode 7d formed on the end surface of the magnetoelectric conversion element 20 are respectively connected with leads.
Wires 13, 13, 13, 13 are attached.

Since the magnetic sensor 50 uses the magnetoelectric conversion element 20 having a small thickness, it has a small outer diameter. Therefore, it can be used, for example, to measure the inner diameter of a thin tube used in a heat exchanger of a nuclear reactor, which could not be measured conventionally.

As described above, the magnetoelectric conversion element 20 of the present invention includes the hard magnetic substrate 6, the magnetoresistive effect film 1 for each one, the soft magnetic substrate 5, and the metallic magnetic substrate 9. Although two sets are provided, the magnetoresistive film 1 and the soft magnetic substrate 5 are not limited to two sets.

For example, a plurality of soft magnetic substance substrates and a plurality of magnetoresistive effect films are bonded to one main surface of one hard magnetic substance substrate, and each magnetoresistive effect film is electrically connected by electrodes. If the magnetoresistive effect films of the same number and the same number are formed on the other main surface of the hard magnetic substrate in the same manner, a magnetoelectric conversion element with a large change in resistance value can be obtained without increasing the thickness too much. Can be configured. A part of the plurality of soft magnetic substrates may be replaced with a resin that serves as an insulating layer.

Further, by forming a plurality of magnetoresistive films electrically independent of each other, a magnetic sensor capable of extracting a plurality of electric signals can be constructed.

In the method of manufacturing the magnetoelectric conversion element of the present invention, the hard magnetic substance substrate is magnetized after the magnetoresistive film is bonded to the hard magnetic substance substrate for applying the bias magnetic field. Therefore, the position of the bias magnetic field can be applied to the magnetoresistive effect film with high accuracy, and the variation in the output voltage is reduced. Further, since the hard magnetic substrate is made of a rare earth magnet, the hard magnetic substrate can be made thin, so that it can be made thin without lowering the amount of change in the resistance value of the magnetoresistive effect film with respect to the change in the magnetic field. In addition, it is easy to reduce the thickness and size.

[0035]

EFFECTS OF THE INVENTION Since the magnetoelectric conversion element of the present invention is configured by adhering a soft magnetic substrate on which a magnetoresistive effect film is formed to a hard magnetic substrate for applying a bias magnetic field, Can be made smaller. Furthermore, a magnetic sensor having a small outer diameter can be configured by using the magnetoelectric conversion element.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetoelectric conversion element according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a magnetic sensor according to an embodiment of the present invention.

FIG. 3 is a sectional view of a conventional magnetoelectric conversion element.

FIG. 4 is a partial cross-sectional view of a conventional magnetic sensor.

[Explanation of symbols]

 1 Magnetoresistive film 2 Short-circuit film 3 Protective film 4 Resin layer 5 Soft magnetic substrate 6 Hard magnetic substrate 7a, 7c Input electrode 7b, 7d Output electrode 8a, 8b Magnet 9 Metal magnetic substrate 10 Insulating layer 11, 12 Holding Part 13 Lead wire 14 Resin layer 15, 16 case 17 Resin 20, 30 Magnetoelectric conversion element 40, 50 Magnetic sensor

Claims (3)

[Claims] 1. A magnetoelectric conversion element comprising two sets of sensing portions each having a plurality of short-circuit films intermittently formed on a magnetoresistive film, wherein the two sensing portions are made of a hard magnetic material made of a rare earth magnet. A magnetoelectric conversion element, which is arranged on the front surface and the back surface of a body substrate, respectively. 2. A magnetoelectric device comprising two sets of detection portions, which are formed by intermittently forming a plurality of short-circuit films on a magnetoresistive film, and are arranged on a front surface and a back surface of a hard magnetic substrate made of a rare earth magnet, respectively. In the method for manufacturing a conversion element, a magnetoelectric conversion is characterized in that the hard magnetic substrate made of a rare earth magnet is vertically magnetized after the detection portions are arranged on the front surface and the back surface of the hard magnetic substrate made of a rare earth magnet. Device manufacturing method. 3. A magnetic sensor comprising the magnetoelectric conversion element according to claim 1 housed in a case.