JPH03113999A - Acoustic converter - Google Patents

Abstract

PURPOSE: To obtain a prescribed apodization characteristic from a single excitation source for constituting individual connections only with two electrodes by making a control function different over an aperture to change the control function. CONSTITUTION: A transducer consists of 9 blocks 1, 2A, 2B, 3A, 3B, 4A, 4B, 5A, and 5B. These blocks are individually produced and are arranged together a shown. Each block includes several ceramic piezoelectric columns shown in 5. These columns are buried in an epoxy resin. Individual blocks are integrated into one body with an adhesive, and both sides are coated with a metallic paint to form electrode 6 and 7 thereafter. Through columns are distributed approximately uniformly over the surface of each block, intervals of columns are longer in outer blocks. Therefore, the amplitude of radiated energy is largest in the center block 1 and is smallest in outermost blocks 4A and 4B.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an acoustic transducer.

[Conventional technology]

It has previously been proposed to create acoustic transducers using rows of ceramic columns embedded in oxy resin. The effects of epoxy resin include improving acoustic matching for loads based on wave sound and widening the bandwidth. Furthermore, the conversion efficiency is improved by using a columnar converter.

[Problem to be solved by the invention]

This invention was made as a result of research into techniques for beam shape control (particularly side rope removal) in the directivity of acoustic transducers. Such control is typically achieved by applying an apodisney function to each individual transducer in the row. Implementing this requires complex and expensive drive circuitry, as well as separate connections for each element in the column. The inventors recognize that this problem can be overcome using the techniques described in the previous section.

[Means to solve the problem]

The acoustic transducer of the present invention includes a layer of piezoelectric and non-piezoelectric materials arranged across the aperture and on either side of the nuclear layer to provide input signals to or receive output signals from the nuclear layer. a transducer comprising electrode means for a piezoelectric and a non-piezoelectric arrangement, the amplitude caused by a constant human signal (or the amplitude of the output signal caused by a constant deflection) is ta ) the proportion and/or arrangement and/or type of piezoelectric material and/or (
bl A transducer which is subject to a control function specified by the proportion and/or arrangement and/or type of non-piezoelectric material, characterized in that said function is different across the aperture.

By changing the aforementioned control function in this way,
It is possible to obtain predetermined apodispense properties from a single excitation source and to construct individual connections using only two electrodes.

This control function includes, for example: (1) the ratio of the area exhibiting the piezoelectric properties of the aperture; (2)
This can be varied in a number of different ways, such as by changing the type of piezoelectric or non-piezoelectric material used in different parts of the aperture, or (3) the shape of the piezoelectric or non-piezoelectric parts.

One possible structure consists of rows of individual piezoelectric materials separated by a matrix of non-piezoelectric material. Another possibility includes utilizing a single piezoelectric slab formed with holes filled with non-piezoelectric material.

Another possibility is to use a honeycomb or spongy piezoelectric material filled with a non-piezoelectric material or vice versa. Another possibility is to mix piezoelectric and non-piezoelectric, for example by mixing the ceramic piezoelectric material in powder form with a suitable non-piezoelectric filler.

Another possible way to change the aforementioned "features" is to
Some change the shape of the piezoelectric or non-piezoelectric portion across the aperture.

To simplify the construction, it is advantageous to organize the arrays by several blocks, with uniform functionality for each block.

An example of implementing the present invention will be specifically described below with reference to the accompanying drawings.

〔Example〕

The illustrated transducer consists of nine blocks 1.2 people, 2B,
It is composed of 3A, 3B, 4A, 4B, 5A and 5B. Each block is made individually and the blocks are placed together as shown.

Each block includes several ceramic piezoelectric columns, such as those shown at 5, for example. These are made from commonly used materials, especially ceramics of the lead-zirconate-titanate type. These pillars are embedded in rigid epoxy resin using off-the-shelf slice and fill techniques. The individual blocks are held together by adhesive and then coated on both sides with metallic paint to form electrodes 6 and 7.

It can be seen from Figure 1 that the columns are distributed approximately evenly across the face of each block, but that the spacing is greater in the outer blocks. Therefore, the amplitude of the radiant energy shown in FIG. 2 is greatest from the central block 1 and least from the outer blocks 4A and 4B. Although this change is only one-dimensional in the configuration shown, it is of course possible to obtain a similar change in two dimensions in other structures.

In operation as a transmitter, electrical signals from the circuit 8 are applied to the column 5 via electrodes 6 and 7 to transmit the desired acoustic signal in the direction indicated by the arrows in FIG.

The electrode 7 is mounted on a rigid substrate, preventing significant radiation in the opposite direction. In operation as a receiver, the acoustic energy causes the column 5 to create a potential difference across the electrodes 6 to 7, which is detected by 8. In both modes of operation, the decreasing fractional volume (numbers in FIG. 1) across the width of the acoustic aperture indicates a transducer gain pattern that accentuates the main lobe and reduces the side lobes. Of course, in other situations similar techniques can be used to obtain a pattern with other characteristics, such as two main lobes or omnidirectional radiation and reception.

[Brief explanation of drawings]

1 is a plan view of a transducer constructed according to the invention; FIG. 2 is a graphical representation of the magnitude of the acoustic energy transmitted from different parts of the transducer of FIG. 1; FIG. , is a cross-sectional view along line I[[-III of FIG. 1.2A, 2B, 3A, 3B 4A, 4B, 5A, 5B...Block, 5...
... Ceramic pillar, 6.7 ... Electrode, 8 ... Transmitter/receiver. Procedural amendment (method) 1. Indication of the case 1990 Patent Application No. 144263 2. Name of the invention Sound transducer 3. Person making the amendment Name of applicant related to the case NID-I Group Limited 4. Agent

Claims (4)

[Claims] 1. a layer of piezoelectric and non-piezoelectric material disposed across the aperture of the transducer, and electrode means disposed on either side of the layer for providing an input signal to the layer or receiving an output signal from the layer; An acoustic transducer constructed of piezoelectric and non-piezoelectric arrays in which the amplitude induced by a constant input signal (or the amplitude of an output signal induced by a constant deflection) is (a) of a piezoelectric material; (b) a control function specified by the proportion and/or arrangement and/or type of non-piezoelectric material, said function being different across the aperture; An acoustic transducer characterized by: 2. 2. Acoustic transducer according to claim 1, constituted by several blocks of a plurality of elements, characterized in that said functionality is uniform across each individual block but differs between adjacent blocks. 3. 3. Acoustic transducer according to claim 1, characterized in that it is constituted by a pillar of ceramic piezoelectric material embedded in epoxy resin. 4. 4. Transducer according to claims 1 to 3, characterized by two electrodes in contact with the piezoelectric material across the transducer aperture and a single excitation source or receiver connected to the electrodes.