JPS5932039B2 - Polymer piezoelectric transducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention allows for any connection method to be used depending on the purpose and performance of the acoustic transducer (equipment), to improve sensitivity, control directivity, and improve configuration with a high degree of design freedom. This invention relates to molecular piezoelectric transducers.

Hereinafter, the present invention will be explained with reference to the drawings.

First, FIG. 1 shows an embodiment of a multi-segmented electrode according to the present invention, in which a continuous polymeric piezoelectric film 10 such as a polyvinylidene fluoride film is adhered to both sides by means such as vapor deposition, adhesion, or painting. The conductive electrode layer is etched by chemical, optical, or mechanical means, leaving a large number of rectangular electrodes 2.2' (here, electrode 2' is the back side of the drawing) in any shape depending on the purpose of the device. It is something that

Thereafter, FIG. 1 shows a portion of the film 1 which is alternately polarized by multi-electrodes as indicated by the + and - symbols shown in the figure, thereby imparting piezoelectricity.

That is, in FIG. 1, a large number of rectangular electrodes 2, 2' are provided on one piezoelectric film 1, and the front and back surfaces are polarized in different directions, and the electrodes 2, 2' are arranged vertically and horizontally. have polarizations of opposite signs on the same plane.

Also, 3, 4, 5, 6 and 3', 4', 5',
Reference numeral 6'(3' to 6' are on the back side) is a connecting terminal portion for a lead wire used for output or input as a transducer or for connection during assembly.

Next, FIG. 2 shows an element a1 t cut along the dotted line dtm in FIG.
a2 1 a3 t a+ ,・・・・・・・・・
・It is made by pasting together one of the following.

Here, the cut out elements a1 to a4...
・A device attached to the fixed frame 7 will be referred to as a conversion device unit.

In addition, in the figure, smaller chips (forming a capacitor) pl, p2 . p3゜p4
Although the cutting size is 12m to include 4 chips, this may be 2 or 3 chips depending on the purpose and performance of the equipment.
It can be cut into any size, such as pieces, four pieces, five pieces, six pieces, etc.

Next, to explain the details of the element a1 as an example, the chips p0 and p3 are multi-polarized alternately so that the surface of the drawing is a positive pole, and the chips p2 and p4 are one pole.

Now, when a sound wave hits the front side of element a0 and the entire film vibrates and sinks to the back side, chip p1. If a voltage of 10 is generated on the surface of p3, the direction of polarization is opposite, so the chip p2. A negative voltage is generated on the p4 table.

At this time, chip p2. Naturally, a child voltage is generated on the back side of p4.

These chips p1. p2. If p3 and p4 are all connected in series as shown in Figures 2 and 4, four times the voltage generated between one chip will be obtained between terminals 3 and 6, increasing the sensitivity. can.

In Figures 2 and 4, 8.9.10 is the terminal section 3'.
and 4', 4 and 5, and 5' and 6'.

FIG. 5 shows another connection state, in which chips p1 and p2
are connected in series, chips p3 and p4 are similarly connected in series, and these are connected in parallel in opposite directions.

In this case, for example, in the horizontal direction, the output voltages cancel each other out and become zero, and in the direction that intersects with the horizontal direction, the output voltages have directivity, resulting in bidirectionality.

Fixed frame 7 in Figure 3. In one example, a plastic frame is used to connect terminal parts 3' and 4' with lead wires 8 and 10.
5' and 6' were connected, but the dotted line part lL12 in Figure 3
Terminal parts 3' and 47. are plated with plastic and used with conductive adhesive. It is also possible to connect s/ and 6'.

Furthermore, instead of plating, a thin metal lead piece can be inserted during plastic molding.

Figure 6 shows the above conversion device units) al', a2♂a
3/, a, and / (four in this example) are arranged on a single circumference with the same curvature. This example shows a principle application to an acoustic transducer. In this case, the element al.

a2. a3. If a4 and chips (referring to p1.p2.p3゜p4 above) are connected in series, one chip per chip.
Six times more sensitivity can be obtained.

In the figure, 13 is a part of a case that fixes or houses the units a1' to a4'.

At this time, units) a1', a2'. a 3/, a
, / are connected in series or in parallel, which has the advantage of being used to change impedance and control directivity.

FIG. 7 is an example of a fan-shaped divided electrode that can be attached to a circular fixed frame (corresponding to the fixed frame 7 described above) depending on the design purpose of the device, and the same electrode pattern as above can be formed on a large film.

The numbers in FIG. 7 correspond to those in FIG.

In this case, cut line 7. m can be punched out in a circle.

The present invention is based on the theory in an ideal model that the sound pressure sensitivity of a polymer piezoelectric film curved in a uniaxial direction is always constant regardless of the vibration receiving area of the film. Therefore, there are some changes in sensitivity depending on the specific implementation, ie, the clamping condition of the peripheral part of the fixed frame, the ratio of vertical and horizontal dimensions, etc.

For reference, the theoretical sensitivity formula is described below.

Sensitivity 1-1 is when the microphone output is received at high impedance, where R is the curvature of the diaphragm, d is the piezoelectric constant of the film,
ε is the dielectric constant of the film.

In the above equation, the sensitivity depends on the curvature R of the diaphragm, the piezoelectric constant d of the film, and the dielectric constant ε, but is unrelated to the area of the diaphragm.

In other words, even if the size of one chip is reduced, the sensitivity of the one chip itself does not change.

Therefore, sensitivity can be improved by connecting these chips in series.

In addition, in the above embodiment, the polarization directions of the multi-divided electrodes were explained using a vice unit in which the left and right sides and the top and bottom of the same plane have polarizations with different signs, but this is a vice unit in which the left and right sides have the same sign and the top and bottom have polarizations with different signs. Of course, a device unit with a

The present invention is constructed as described above, and since a plurality of chips are alternately polarized on one vibrating membrane (piezoelectric film), the connection method may vary depending on the purpose and performance of the device. It can be used arbitrarily to improve sensitivity, change internal impedance, control directivity, and provide a high degree of design freedom, making it an industrial dog.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a top view of an embodiment of a multi-segmented electrode according to the polymer piezoelectric transducer of the present invention, and Fig. 2 is a perspective view of an embodiment of the conversion device unit. Figure 3 is a perspective view of the fixed frame constituting the device unit, Figures 4 and 5 are schematic diagrams showing the connection state of the device unit, and Figure 6 is a perspective view of the device unit with no curvature on one circumference. FIG. 7 is a perspective view showing an application example of a plurality of transducers arranged in total, and a top view showing another example of the multi-divided electrode. 1... Polymer piezoelectric film, 2,2'-...
...Multi-divided electrode, 3...Fixed frame.

Claims (1)

[Claims] 1. In a transducer using a polymer piezoelectric film, a plurality of multi-segmented electrodes are provided on one vibrating membrane (piezoelectric film), and the polarization directions of the front and back surfaces of the film are mutually A polymer piezoelectric transducer characterized by being polarized differently, connecting the divided electrodes in series or parallel, and curving the film so that only one axial direction thereof has a curvature. 2. The polymer piezoelectric transducer according to claim 1, wherein the polarization directions of the multi-segmented electrodes are polarized with opposite signs on the left and right sides and the top and bottom of the same plane. 3. The polymer piezoelectric transducer according to claim 1, wherein the polarization directions of the multi-divided electrodes are polarized with the same sign on the left and right sides and different signs on the top and bottom on the same plane. 4. A polymer piezoelectric transducer according to claim 2 or 3, comprising multi-divided electrodes connected in series or in parallel. 5. Claims 2, 3, or 4, which use a fixing frame that has a grid-like window that fixes each of the multi-divided electrodes independently and is curved so that it has curvature in only one axis direction. Polymer piezoelectric transducer as described in .