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FIELD OF THE INVENTION This invention relates to acoustic transducers. BACKGROUND OF THE
INVENTION It has previously been proposed to make acoustic transducers using an array of
ceramic columns embedded in an ovoxy resin. As an effect of epoxy resin, it is possible to
improve the acoustic matching to the load based on wave noise and to widen the bandwidth.
Moreover, conversion efficiency is improved by using a columnar converter. SUMMARY OF THE
INVENTION The present invention has been made as a result of researching a technique for
control of beam shape (especially removal of side ropes) in the directivity of an acoustic
transducer. Such control is usually achieved by applying the apodization function to the
individual transducers in a row. To do this requires complex and expensive drive circuits, as well
as separate connections for each element in the column. We recognize that this problem can be
overcome using the techniques described in the previous section. SUMMARY OF THE
INVENTION The acoustic transducer of the present invention comprises a layer of piezoelectric
and non-piezoelectric material arranged across the aperture, and provided on both sides of the
nucleus layer to supply input signals to the nucleus layer. Or an electrode means for receiving an
output signal from the nuclear layer, wherein the method of piezoelectric and non-piezoelectric
alignment is caused by an amplitude (or constant deflection caused by a constant manual signal).
The amplitude of the output signal being sent will be ta) according to the ratio and / or the
arrangement and / or the type and / or the type of the piezoelectric material and / or the control
function specified by the ratio and / or the arrangement and / or the type of non bl piezoelectric
material The transducer is characterized in that the functions differ across the aperture. By thus
changing the control functions described above, it is possible to obtain the desired apodization
characteristics from a single excitation source, and it is possible to construct individual
connections using only two electrodes. . This control function may be, for example, (1) the ratio
of the area showing the piezoelectric properties of the aperture, (2) the type of piezoelectric or
non-piezoelectric material used for different parts of the aperture, or (3) It can be changed in
several different ways, such as changing its shape. One possible structure is one that consists of
an array of discrete piezoelectric materials separated by a matrix of non-piezoelectric material.
Another possibility involves the use of a single piezoelectric slab formed with non-piezoelectric
filling holes.
Another possibility is to use non-piezoelectric-filled honeycomb or sponge-like piezoelectrics or
vice versa. Another possibility is to mix piezoelectric and non-piezoelectric, for example by
mixing the ceramic piezoelectric material with powder and mixing with a suitable nonpiezoelectric filler. Another possible way of changing the aforementioned "function" is to change
the shape of the piezoelectric or non-piezoelectric part across the aperture. In order to simplify
the structure, it is advantageous to organize the columns by several blocks, so that the function is
uniform for each block. An example of practicing the present invention will be specifically
described below with reference to the attached drawings. EXAMPLE The illustrated converter is
constituted by nine blocks 1.2, 2B, 3A, 3B, 4A, 4B, 5A and 5B. Each block is made individually
and the blocks are arranged together as shown. Each block contains several ceramic piezoelectric
columns, as shown for example at 5. They are made of commonly used materials, in particular of
the lead-zirconate-titanate type of ceramic. These columns are embedded in rigid epoxy resin
using pre-made slicing and filling techniques. The individual blocks are united by adhesive and
then coated on both sides with metallic paint to form the electrodes 6 and 7. It can be seen from
FIG. 1 that the pillars are substantially equally distributed over the face of each block, but the
spacing is greater in the outlying blocks. For this reason, the amplitude of the radiation energy
shown in FIG. 2 is the largest from the central block 1 and the smallest from the outer blocks 4A
and 4B. This variation is only one-dimensional in the illustrated configuration, but of course in
other configurations similar variations in two dimensions can be obtained. In operation as a
transmitter, the electrical signal from circuit 8 is supplied to pole 5 via electrodes 6 and 7 and
the desired acoustic signal is delivered in the direction indicated by the arrow in FIG. The
electrode 7 is mounted on a rigid substrate to prevent large radiation in the opposite direction. In
operation as a receiver, acoustic energy causes the pole 5 to develop a potential difference across
the electrodes 6-7, which is detected by 8. In both modes of operation, the diminishing
subdivisions (numbers in FIG. 1) of the width of the acoustic aperture show the gain pattern of
the transducer which highlights the main lobe and reduces the side lobe.
Of course, in other contexts, similar techniques can be used to obtain certain patterns with other
characteristics such as, for example, two main lobes and omnidirectional radiation and reception.
Brief description of the drawings
FIG. 1 is a plan view of a transducer of a structure according to the invention, FIG. 2 is a
graphical illustration of the magnitude of acoustic energy transmitted from different parts of the
transducer of FIG. 1, and FIG. FIG. 3 is a cross-sectional view taken along line I [[-III of FIG.
1.2A, 2B, 3A, 3B 4A, 4B, 5A, 5B ..... block, 5.・ Transceiver. Amendment to procedure (type) 1,
display of case 1990 patent application No. 144263 2, name of invention sounding converter 3,
relation to person making correction case name of applicant Applicant day-ai group limited 4,
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