CN106291408B

CN106291408B - Magneto-electric converter based on magnetostrictors and electrets

Info

Publication number: CN106291408B
Application number: CN201610885046.5A
Authority: CN
Inventors: 周云
Original assignee: China Jiliang University
Current assignee: China Jiliang University
Priority date: 2016-10-11
Filing date: 2016-10-11
Publication date: 2023-06-09
Anticipated expiration: 2036-10-11
Also published as: CN106291408A

Abstract

The invention discloses a magneto-electric converter based on magnetostrictors and electrets. The invention includes electrets, magnetostrictors and metal plates. The electret is arranged at one end of the magnetostriction body, the other end of the magnetostriction body is relatively fixed, a metal film is plated between the electret and the magnetostriction body, a metal polar plate is arranged at the position opposite to the electret, the metal polar plate and the electret form a capacitor, and the metal film and the metal polar plate lead out wires to the signal processing unit. The invention has simple structure and low cost, is easy to realize miniaturization of devices and is convenient to carry. The invention can detect direct current and alternating magnetic fields and can be used for metal detection.

Description

Magneto-electric converter based on magnetostrictors and electrets

Technical Field

The invention relates to a magneto-electric converter, in particular to a magneto-electric converter based on a magnetostrictor and an electret.

Background

Magneto-electric converters are an important component part in most of the current magnetic sensing devices, and magnetic sensing is widely used in various aspects such as biomedicine, resource detection, geological disaster prediction, military and the like, and plays a significant role in the fields of magnetic detection and metal detection. In the current magnetic sensor, the magneto-electric conversion is mainly made based on a coil fluxgate effect, a magneto-resistance effect, a magneto-electric effect of multiferroic materials, a Hall effect, a flux quantum effect and the like. In general, magneto-electric converters based on the above effects have their respective advantages, as well as their respective disadvantages, mainly manifested in: some have large power consumption, some have large volume, some have high cost, have low sensitivity, some have complex structures, need low-temperature refrigeration, limit the use environment and the like.

Disclosure of Invention

In order to solve the testing problems of magnetic sensing in the aspects of testing sensitivity, portability and the like, a quick, convenient and accurate testing method is provided. The magneto-electric converter has the advantages of simple structure, easy carrying and low cost because the materials are common magnetostrictive materials and electret materials.

The technical scheme adopted for solving the technical problems is as follows: the magnetostrictor is bonded with the electret, and the electret surface and the metal electrode form a capacitor. Under the action of the magnetic field, the magnetostrictor generates displacement to drive the electrets to move, so that the distance between the electrets and the metal electrodes is changed, and the capacitance of the capacitor is further changed. This achieves magneto-electric conversion. The magnetic field can be detected by detecting the voltage at the two ends of the capacitor through external signal processing. If a changing magnetic field is sent out from the outside and meets a metal object, eddy current is formed in the metal, the eddy current can excite a magnetic field in space, and the magnetoelectric transducer can sense the excited magnetic field and further can play a role in detecting the metal. The magneto-electric transducer can be used for constructing magnetic sensors, and can be used for detecting metal objects in addition to magnetic fields.

The beneficial effects of the invention are as follows: the magneto-electric converter is formed by using the magnetostrictive material and the electret material which are easy to obtain, has simple structure and low cost, and is easy to realize miniaturization and convenient to carry. The invention can detect direct current and alternating magnetic fields and can be used for metal detection.

Drawings

Fig. 1 is a schematic diagram of the working principle of the present invention.

Fig. 2 is a schematic view of the construction of the present invention.

In the figure: 1. electret, metal film evaporated on electret, metal polar plate, air gap, small hole on metal polar plate, magnetostrictor, external signal processing unit, casing and conducting wire.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Fig. 1 shows a schematic diagram of the working principle, in the embodiment of fig. 1, the electret 1 and the metal polar plate 3 form a parallel plate capacitor, the metal film 2 is evaporated on the electret, the medium in the middle is a very thin air gap 4, and the metal film 2 is evaporated on the electret. The metal polar plate is provided with a small hole 5, which is convenient for air flow and balances the air pressure at the two sides of the metal polar plate. The magnetostrictor 6 and the electret are bonded together. During testing, the external magnetic field changes to cause the deformation of the magnetostrictors to drive the electret film to displace. This changes the distance between the plates of the capacitor, thereby causing a change in the capacitance. Since the number of charges on the electret remains constant throughout, according to the formula: q=cu, where Q represents the charge amount, C represents the capacitance, and U represents the voltage. Therefore, when C changes, the voltage U at the two ends of the capacitor is inevitably changed, an electric signal is output, and the magneto-electric conversion is realized through the external signal processing unit 7. In the external signal processing unit 7, the output electric signal is weak and the output impedance is high in consideration of the small capacitance of the actually composed capacitor. The external signal processing unit is generally connected to the amplifying circuit after the impedance converter is connected.

Fig. 2 is a schematic diagram of the construction of the invention. In the embodiment of fig. 2, the electret and evaporated metal film are bonded to one end of a magnetostrictive body, the other end of which is fixed to the housing 8. Thus, under the action of an external magnetic field, the magnetostrictor can drive the electret to stretch towards the direction of the metal polar plate 3 under the magnetostriction effect. The capacitance of a parallel plate capacitor consisting of an evaporated metal film and a metal plate is further changed by changing the distance between the electret and the metal plate. The vapor plating metal film is connected with one end of the external signal processing unit through a lead 9 in the shell, and the metal polar plate is connected with the other end of the external signal processing unit, so that the formed converter can be used as a magnetic sensor for detecting magnetic fields and detecting metals.

Claims

1. Magneto-electric converter based on magnetostriction body and electret, including electret, magnetostriction body and metal polar plate, its characterized in that: the electret is arranged at one end of the magnetostriction body, the other end of the magnetostriction body is relatively fixed, a metal film is plated between the electret and the magnetostriction body, a metal polar plate is arranged at the position opposite to the electret, the metal polar plate and the electret form a capacitor, and the metal film and the metal polar plate lead out wires to the signal processing unit.

2. The magneto-electric converter of claim 1, wherein: the metal polar plate is provided with a plurality of through holes.

3. Use of the magneto-electric transducer of claim 1 in a magnetic sensor.