JPS6020913B2 - flexible piezoelectric sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piezoelectric sheet used in a vibrating membrane of a speaker, microphone, headphone, etc.

Conventionally, this type of vibrating membrane uses a flexible piezoelectric sheet made by uniformly dispersing electromagnetic powder in thermoplastic resin or synthetic rubber, but it has low mechanical strength and must be handled with care. It also had the disadvantage that it could not withstand use in medium and low environments with large vibrations.

The present invention solves the above-mentioned drawbacks, and the embodiments shown in the drawings will be described below.

In the drawings, 1 is a thermoplastic resin such as polyvinyl fluoride, polyvinylidene fluoride, or chloroprene rubber;
2 is a sheet-like mixture in which reinforced electromagnetic powder such as lead zirconate titanate is uniformly dispersed in a synthetic rubber such as fluororubber or silicone rubber as a matrix; 2 is a reinforcing cloth embedded in mixture 1; Made of organic fibers with excellent strength and elasticity, such as vinylon and polyester.

As a means for embedding this reinforcing cloth 2 in the above-mentioned mixture 1, a known dipping method, doctor blade method, roll coater method, or the like is employed. 3 and 3 are electrode layers formed on both sides of the sheet-like mixture.

Next, FIG. 2 shows an apparatus for manufacturing a reinforcing cloth-filled piezoelectric sheet of the present invention using the doctor blade method.

In the figure, reference numeral 11 denotes a mixture storage tank, and a doctor knife 1 forms a predetermined gap between one side wall and an endless belt 13.
It becomes 2. 14 and 15 are drive rolls around which the endless belt 13 is horizontally wound, 16 is a drying chamber, 17 is a roll for supplying reinforcing cloth, and 18 is a roll for winding up the sheet to be formed.

Now, 100 to 150 parts by weight of lead zirconate titanate is dispersed in 100 parts by weight of the mixture to be molded, for example, chloroprene rubber containing an appropriate amount of a sulfurizing agent and a solvent, and a well-mixed slurry IJ-shaped mixture is prepared. Fill the substance 1 into the pot 11,
When the endless belt 13 carrying the polyester fiber reinforcing cloth (thickness 0.1, mesh size 200 mesh) 2 is driven in the direction of the arrow, the mixture 1 is transferred to the doctor knife 12 as the belt 13 is transferred. Under the regulations, an unvulcanized sheet t impregnated and applied to a uniform thickness on the reinforcing cloth 2 is derived.

As shown in the enlarged view of FIG. 3, the vulcanized sheet ot drawn out from the doctor knife 12 is such that the mixture 1 passes from the surface layer of the reinforcing fabric 2 to the back layer through the mesh and covers the entire reinforcing fabric 2. It is in a buried state. This unvulcanized sheet t is sent to the subsequent drying chamber 16, where it is heated and dried while evaporating the solvent in the mixture. The dried sheet is peeled off from the endless belt 13 and wound up by a winding roll 18. After that, the cut sheet cut according to the predetermined shape and size is
As shown in the figure, it is rubberized by a desired vulcanization process, electrode layers 3, 3 are formed on the front and back surfaces by aluminum vapor deposition, etc., and polarization is performed by applying a voltage. When the piezoelectric constant d of the piezoelectric rubber sheet obtained by polarization was measured, it was 8 × 10-12 m/v.
In addition to the above, satisfactory results were also obtained in terms of toughness and elasticity. As described above, the antide piezoelectric sheet of the present invention is formed by embedding a reinforcing fabric made of organic fibers in a mirror piezoelectric sheet made by uniformly dispersing strong electromagnetic powder in a thermoplastic resin or synthetic rubber. Kame sheet has excellent rut resistance, making it easy to handle, and is also highly elastic, making it suitable for use as a vibrating membrane for speakers, etc. driven in large vibrations, compared to conventional piezoelectric sheets that do not have reinforcing cloth. Its practical value is extremely high.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a flexible piezoelectric sheet according to the present invention, and FIG. 2 is a schematic diagram of one manufacturing apparatus for the piezoelectric sheet of the present invention. FIG. 3 is an enlarged sectional view of the unloaded piezoelectric wire obtained by the apparatus shown in FIG. 2. 1... Piezoelectric mixture, 2... Reinforcement cloth. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A flexible piezoelectric sheet comprising a reinforcing cloth made of organic fiber embedded within a flexible piezoelectric sheet made of a thermoplastic resin or synthetic rubber with ferromagnetic powder uniformly dispersed therein.