JPH0632551B2 - Mechanical-electrical conversion element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention uses a flexible piezoelectric material to convert mechanical stress into an electrical signal, or to convert an electrical signal into a mechanical vibration. Regarding the conversion element.

<Prior Art> A flexible piezoelectric material applied to this type of electromechanical conversion element is made by mixing ferroelectric ceramic particles such as lead zirconate titanate and lead titanate in synthetic rubber or synthetic resin. Due to its flexibility, it can be easily displaced with respect to mechanical stress and a good output voltage can be obtained. Therefore, ultrasonic transducers, hydrophones, vibration detection sensors for internal combustion engines, electric piano string vibration pickups, etc. It is used for various purposes.

As the electromechanical conversion element, two flexible electrodes are arranged via a piezoelectric layer made of a flexible piezoelectric material, and the piezoelectric layer is polarized in the corresponding directions of the two electrodes, and at least one of the electrodes is polarized. The electrode is connected to a lead wire, and a signal voltage corresponding to mechanical stress is taken out from the lead wire.

However, in this type of conventional structure, when a load is applied at the connecting portion of the lead wire by pulling, bending, or swinging of the lead wire, this acts as a mechanical stress on the piezoelectric layer, which causes noise. Occurred, which was a cause of false detection.

It is an object of the present invention to provide a mechanical-electrical conversion element capable of preventing generation of a voltage due to a load at a connecting portion of the lead wire and extracting a good signal voltage.

<Means for Solving Problems> According to the present invention, two flexible electrodes, at least one of which is a jacket electrode, are arranged via a piezoelectric layer made of a flexible piezoelectric material. In a corresponding direction of two electrodes and further connecting the electrodes to a lead wire.In a mechanical-electrical conversion element, an insulating layer is interposed between the piezoelectric layer and the jacket electrode at the peripheral side of the connecting side of the lead wire. It is characterized by having done.

Here, examples of the flexible piezoelectric material include piezoelectric rubber and piezoelectric resin. Further, the material applied to the electrode layer includes conductive rubber and the like.

<Operation> In the present invention, the insulating layer is interposed between the piezoelectric layer and the jacket electrode at the peripheral portion on the side where the lead wire is connected. Therefore, even if a load is generated in the peripheral portion of the connection side due to pulling of the lead wire or the like, the load is not converted into an electric signal and noise is not generated.

<Example> FIG. 1 shows the present invention applied to a mechanical-electrical conversion element 1 in the form of a coaxial cable.

Here, 2 is a piezoelectric layer made of piezoelectric rubber, and a core electrode layer 4 made of a conductive rubber having a core electrode 3 made of a linear conductive material is embedded in the center thereof. Further, the outer electrode layer 5 made of conductive rubber is formed on the outer periphery thereof. The outer electrode layer 5 also covers the end portion of the piezoelectric layer 2, and a moisture-proof coating or the like is applied to the periphery of the outer electrode layer 5 if necessary.

6 is a lead wire, and the conductor wire 7 is inserted through the center of the lead wire,
Further, the outer peripheral surface is covered with the conductive braid 9 via the insulating layer 8 to form a known structure.

The core electrode 3 is exposed from the end of the electromechanical conversion element 1 and connected to the conductor wire 7, and a conductive tube 10 is externally fitted between the electromechanical conversion element 1 and the lead wire 6. The conductive tube 10 electrically connects the jacket electrode layer 5 and the conductive braid 9.

In the above structure, an insulating layer 11 such as a rubber plate is interposed between the piezoelectric layer 2 and the outer electrode 5 on the peripheral side of the connection side of the lead wire 6.

FIG. 2 is a diagram in which the present invention is applied to a plate-shaped electromechanical conversion element 20, and outer electrodes 22 and 22 made of conductive rubber are formed on the upper and lower surfaces of a piezoelectric rubber plate 21 (piezoelectric layer). Has been done. Conductive braids 23, 23 for connection are embedded in the outer electrodes 22, 22, respectively. At the ends of the piezoelectric rubber plate 21, the conductive braids 23, 23 are exposed and the lead wires 24, 24 are connected.

Even with such a configuration, insulating layers 25, 25 are provided between the piezoelectric rubber plate 21 and the outer electrodes 22, 22 on the peripheral side of the connection side of the lead wires 24, 24.

<Effects of the Invention> As described above, according to the present invention, since the insulating layer is interposed between the piezoelectric layer and the jacket electrode in the peripheral portion on the side of connection with the lead wire, the connection is made by pulling the lead wire or the like. Even if a load is generated in the part, it is not converted into a voltage around the connection part, and therefore, there is an excellent effect that a good output signal can be obtained.

[Brief description of drawings]

The attached drawings show an embodiment of the present invention. FIG. 1 is a vertical sectional side view of an embodiment in which the present invention is applied to a coaxial electromechanical conversion element 1, and FIG. It is a vertical side view of the applied example. 1; electromechanical conversion element, 2; piezoelectric layer, 3; core electrode, 5;
Jacket electrode, 7; Lead wire, 11; Insulating layer, 20; Mechanical-electrical conversion element, 22; Jacket electrode, 24; Lead wire, 25;
Insulation layer

Claims (3)

[Claims] 1. A piezoelectric layer made of a flexible piezoelectric material is interposed,
At least two flexible electrodes, at least one of which is a jacket electrode, are arranged, and the piezoelectric layer is polarized in the corresponding directions of the two electrodes.
Further, in the electromechanical conversion element in which the electrode is connected to a lead wire, the electromechanical conversion element is characterized in that an insulating layer is interposed between the piezoelectric layer and the outer electrode on the peripheral side of the connection side of the lead wire. . 2. A coaxial electromechanical conversion element comprising a core electrode embedded in the center of a piezoelectric layer, the outer surface of the piezoelectric layer being covered with a jacket electrode, and the electrode being connected to a lead wire. The electromechanical conversion element according to claim 1), characterized in that an insulating layer is provided between the piezoelectric layer and the outer electrode on the peripheral side of the connection side of the lead wire. 3. A piezoelectric layer is formed on the peripheral side of a lead wire connecting side of a mechanical-electrical conversion element in which outer electrodes are formed on the upper and lower surfaces of the plate-like piezoelectric layer and the electrodes are connected to the lead wire. The electromechanical conversion element according to claim 1), characterized in that an insulating layer is interposed between the outer electrodes.