JPH0514533Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field: The present invention relates to an improvement in a lead wire attachment structure in an electrode layer of conductive rubber formed on a piezoelectric rubber body.

Problems to be solved by conventional techniques and ideas: Piezoelectric rubber is made of a composite material made of synthetic rubber or elastic elastomer material mixed with ferroelectric ceramic particles such as lead zirconate titanate or lead titanate. It is formed in the shape of a cable, and because of its flexibility, it can easily be displaced in response to mechanical stress and can obtain a good output voltage, so it is used in tread pressure switches, pickups, etc. Furthermore, since the acoustic impedance has a characteristic similar to that of water, it is suitable as an underwater microphone (hydrophone).

The piezoelectric rubber has the advantage that it does not break like piezoelectric ceramics even if subjected to deformation or impact, but as shown in FIGS.
The electrode layer 2 formed on the upper and lower surfaces of the substrate must also have sufficient durability. Therefore, the electrode layer 2
The piezoelectric rubber body 1 is made of conductive rubber containing metal powder.
It is integrally formed by simultaneous vulcanization.

By the way, in use, a lead wire 3 is attached to the electrode layer 2, and an electric signal is supplied from the lead wire 3 to excite the piezoelectric rubber body 1, or conversely, when mechanical strain is applied to the piezoelectric rubber body 1, The charge induced in the electrode layer 2 is derived from the lead wire 3, but when the lead wire 3 is directly soldered 4 to the electrode layer 2 made of conductive rubber, the amount of metal powder mixed with the rubber should be 70% by volume. It has been found that strong brazing 4 cannot be achieved unless the above conditions are met. However, as described above, when the amount of metal powder is increased, there is a problem that when the piezoelectric rubber body 1 is bent, the electrode layer 2, which has a large surface distortion, breaks due to lack of flexibility.

Means for solving the problems: This proposal is a proposal to improve these conventional drawbacks. In other words, this proposal has a piezoelectric rubber body with a volume ratio of
A conductive rubber containing 50 to 10% metal powder is formed as an electrode layer by vulcanization, and a metal foil for brazing lead wires is integrally provided on the main part of the electrode layer. This is a characteristic piezoelectric rubber.

Example 1: This example is applied to a case where the piezoelectric rubber is in the form of a sheet. 1 and 2, the longitudinal sectional front views of FIGS. 2a to 2c show the manufacturing process, and FIG. 2a shows electrode layers 2 on the upper and lower surfaces of the sheet-like piezoelectric rubber body 1. For example, a silver rubber solution consisting of conductive silver powder, rubber, and a solvent toluene is applied. In this case, the volume ratio of silver powder and rubber is 50
% or less, it can be lowered to about 10%. As shown in FIG. 2b, a silver foil is attached as a metal member 5 to the main part of the electrode layer 2, and these laminates are vulcanized between molds 6 and bonded together. Note that as the material of the metal member 5, foil or thin plate of tin, stainless steel, aluminum, etc., which can be soldered to the lead wire and has appropriate conductivity, may be used.

Next, as shown in FIG. 2c, the lead wire 3 is brazed 4 to the metal member 5. As a result, it was possible to obtain an adhesive with superior adhesive strength compared to a conventional conductive rubber electrode layer directly soldered. This conductive rubber electrode layer 2 has a much lower metal powder content than conventional products, so it has excellent flexibility and there is no risk of the electrode layer being cut even when bent. FIG. 1 is a perspective view showing this embodiment.

Example 2: This example is applied to a case where the piezoelectric rubber is in the form of a cable. Explaining based on FIG. 3, 1 is a cable-shaped piezoelectric rubber body, and 2 is an electrode layer made of conductive rubber containing metal powder at a volume ratio of 50 to 10%, similar to that described in Example 1. . 5 is a metal member to which the lead wire 3 is brazed 4. In this case, since the conductive core (center electrode) 7 serves as a lead wire, only one metal member 5 to which the lead wire 3 is brazed is required. The adhesive strength of the lead wire 3 also had the same effect as in Example 1. The electrode layer 2 is also flexible and will not break when bent.

Effects of the invention: As described above, according to the present invention, a lead is formed in the main part of the electrode layer of a laminate in which conductive rubber containing 50 to 10% metal powder by volume is adhered to the piezoelectric rubber body as an electrode layer. By integrally providing a metal member for brazing the wire, the adhesive strength is extremely high compared to the conventional method of directly brazing the conductive rubber, and in addition, the lead wire can be brazed directly to the electrode layer. Since it is not necessary, the mixing ratio of metal powder can be lowered to about 10% by volume. Therefore, the flexibility of the conductive rubber electrode layer is increased, and the conventional disadvantage of the electrode layer breaking when the piezoelectric rubber body is bent can be completely eliminated, which is extremely useful in practice.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the piezoelectric rubber of the present invention, Fig. 2 a, b, and c are vertical sectional views sequentially showing the manufacturing process thereof, and Fig. 3 is a perspective view showing another embodiment of the piezoelectric rubber of the present invention. FIG. FIG. 4 is a plan view of essential parts of a conventional piezoelectric rubber, and FIG. 5 is a longitudinal sectional front view thereof. 1... Piezoelectric rubber body, 2... Conductive rubber electrode layer,
3...Lead wire, 4...Brazing, 5...Metal member,
7... Conductive core.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) For a laminate in which a conductive rubber containing 50 to 10% metal powder by volume is vulcanized and adhered to a piezoelectric rubber body as an electrode layer, the material on the electrode layer is A piezoelectric rubber characterized in that a metal member for brazing a lead wire is integrally attached to the part. (2) The piezoelectric rubber according to claim 1, wherein the metal member is integrally formed by vulcanization with the piezoelectric rubber body and the conductive rubber electrode layer. (3) The piezoelectric rubber according to claim 1, wherein the piezoelectric rubber and conductive rubber electrode layers are formed concentrically around a center electrode constituting one electrode in the laminate.