CN106771676A - Based on the electric-field sensor probe that electrostriction material and electret are constructed - Google Patents

Abstract

The invention discloses an electric field sensor probe based on electrostrictive material and electret material. The invention includes electret material, electrostrictive material and metal pole plate. The electret material is bonded to one end of the metal pole plate or to the electrode at one end of the electrostrictive body, and the other end of the electrostrictive material is relatively fixed. A capacitor is formed between the metal electrode and the metal pole plate on the electrostrictive material, and both the metal electrode and the metal pole plate lead out wires to be connected to an external signal processing device. The invention has the advantages of simple structure, low cost, easy realization of device miniaturization and portability. The invention can not only detect electrostatic field and alternating electric field, but also can be used for metal detection.

Description

Electric field sensor probe based on electrostrictive material and electret material

technical field

The invention relates to a sensor probe, in particular to the preparation of a novel electric field sensor probe based on electrostrictive materials and electret materials.

Background technique

An electric field sensor is a sensor that can sense the strength of an electric field and convert it into an output signal. The electric field sensor is currently the main means of testing strong electric fields, especially transient electric fields in high-voltage power systems, which can effectively avoid the destructive effects of strong electric fields. In addition, the electric field sensor can also be used to detect the strength of the electric field in the environment, and is widely used in monitoring the electric field effect of electrical equipment, automatic switch control, liquid level moderate detection, automotive safety functions, etc. In the electric field sensors currently in use, the main principle of electric field detection is: based on the induction of charges by two conductors in the electric field, an induced voltage will appear on the conductors. The two conductors are two circular plate conductors parallel to each other, and are connected with the two plates to form a differential amplifier. By detecting the voltage between the conductors, the magnitude of the measured electric field can be obtained. This detection method based on the above principles requires the capacitance of the antenna to be particularly large, and the differential amplifier must have high input impedance and small capacitance, otherwise the original waveform will be easily distorted. Therefore, the preparation process requires high requirements, and has the disadvantage of easy distortion.

In addition, with the development of electrostrictive materials, it has become a reality to apply such materials to electric field sensors. Compared with traditional piezoelectric materials, such as lead zirconate titanate, barium titanate, etc., relaxation ferroelectric ceramic electrostrictive materials based on lead magnesium niobate and new polymer electrostrictive materials can be used in A sufficiently large amount of deformation can be obtained under a lower electric field. This makes this kind of material has a wider application prospect. Electret material is a solid dielectric with permanent polarization. Its characteristic is that the polarized charge "permanently" exists on the surface and body of the dielectric, so it can provide a stable voltage and is a good DC voltage source. This is very useful in the manufacture of electronic devices and electrical measuring instruments.

Contents of the invention

In order to improve the high requirements for the preparation of traditional electric field sensors and the deficiencies of easy distortion, and provide a simple and accurate measurement device, the present invention provides a new type of electric field sensor probe, which can be used for electric field detection. The structure of the electric field sensor probe is extremely simple, and the materials are selected from common electrostrictive materials and electret materials, so it can be miniaturized and meet the requirements of small-scale accurate measurement.

The technical scheme adopted by the present invention to solve the technical problem is: combine the electrostrictive material and the electret material together, and combine the metal electrodes to form a capacitor. Under the action of an external electric field, the electrostrictive material deforms, changing the distance between the two plates of the capacitor, thereby changing the capacitance of the capacitor. Since the charge of the electret can remain unchanged, there is a constant charge between the two metal plates. When the capacitance of the capacitor changes, the voltage between the two plates also changes. This realizes the electric field-voltage conversion. By connecting an external signal processing unit, the voltage change at both ends of the capacitor can be detected, and then the external electric field can be detected. If a changing electromagnetic field is emitted, when it encounters a conductive object such as metal, an eddy current will be formed in it. This eddy current will also excite an electric field in space. Using this electric field sensor probe, the excited electric field can be detected, and then it can be used to detect conductors such as metals. Therefore, the electric field sensor can not only detect the external electric field, but also can be used to detect conductive objects such as metals.

The beneficial effect of the invention is that the electric field sensor probe is composed of easily obtained electrostrictive material and electret material, has simple structure, low cost, is easy to realize device miniaturization and accurate detection, and is also easy to carry. The invention can not only detect static electricity field and alternating electric field, but also can be used to detect metal and conductive material.

Description of drawings

Figure 1 is an embodiment of the present invention.

Fig. 2 is another embodiment of the present invention.

In the figure: 1. Electrostrictive material, 2. Metal electrode coated on electrostrictive material, 3. Electret, 4. Back electrode (metal plate) of electret, 5. Air or dielectric gap, 6 . Outgoing leads (connected to the electrodes coated on the electrostrictive material), 7. Outgoing leads (connected to the back electrodes of the electret).

detailed description

The present invention will be further described below in conjunction with accompanying drawing.

What Fig. 1 and Fig. 2 showed is the working principle schematic diagram and the structural principle diagram of the present invention. The main body is composed of electrostrictive material 1 , electret material 3 and metal pole plate 4 . There are two electret bonding methods, as shown in Figure 1 and Figure 2 respectively. In the embodiment of Fig. 1, one end of the electrostrictive material 1 is fixed, and the other end is coated with a metal electrode 2, and the back electrode of the other end of the electret opposite to it is bonded together with the metal plate 4 by conductive glue, between the two conduction between each other. A parallel plate capacitor is formed between the metal electrode 2 and the metal pole plate 4 . The metal electrode 2 and the metal pole plate 4 are connected to the wires 6 and 7 respectively, and are externally connected to a signal processing device. What Fig. 2 shows is another kind of bonding mode of electret 3, the back electrode of electret 3 is bonded together with metal electrode 2 on electrostrictive material 1 by conductive glue, metal electrode 2 and metal pole plate 4 forms a capacitor between them. Similarly, the metal electrode 2 and the metal pole plate 4 are connected to the wires 6 and 7 respectively, and are externally connected to a signal processing device. In both bonding methods, the capacitor is sandwiched by a thin layer of air gap or other dielectric5.

According to the parallel plate capacitor capacitance C=ɛS/d, the capacitance is related to the dielectric constant ɛ, the plate area S and the distance d between the two plates. When testing the external electric field, the external electric field causes the deformation of the electrostrictive body, which changes the distance d between the two plates of the capacitor, thereby causing a change in capacitance. According to the formula: Q = CU, where Q represents the amount of charge and U represents the voltage. Therefore, when the capacitance C changes, it will inevitably cause a change in the voltage U across the capacitor, and an electrical signal will be output to realize the change of the electric field-voltage. The purpose of detecting the external electric field is achieved by connecting the external wires 6 and 7 to the signal processing device.

Claims (3)

1. The electric field sensor probe based on electrostrictive material and electret material construction, comprises electret, electrostrictive body and metal plate, is characterized in that: electret is arranged on one end of electrostrictive body, electrostrictive The other end of the telescopic body is relatively fixed; a metal electrode is arranged between the electret and the electrostrictive body, and a metal pole plate is arranged at a position opposite to the electret, and the metal pole plate and the metal electrode form a capacitor. Both the metal pole plate and the metal electrode lead out wires to be connected to an external signal processing device. 2. An electric field sensor probe based on electrostrictive materials and electret materials, including electrets, electrostrictive bodies and metal plates, is characterized in that: one end of the electrostrictive body is provided with a metal electrode, and the other end is relatively fixed The electret is arranged on one end of the metal pole plate close to the metal electrode, and is opposite to the metal electrode. The metal pole plate and the metal electrode form a capacitor, and the metal pole plate and the metal electrode both lead out wires to connect to the signal processing device. 3. An application of the electric field sensor probe according to claim 1 or 2 in electric field detection.