JPH03224400

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DESCRIPTION JPH03224400
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
piezoelectric ultrasonic transducer used for a fish finder or the like. [Prior Art] Currently, a
piezoelectric ultrasonic transducer using PZT (lead zirconate titanate) or the like is widely used
as a transducer of a fish finder. FIG. 4 is a perspective view schematically showing the structure
of a conventional piezoelectric ultrasonic transducer of this type, in which (1, 0a) is a
piezoelectric transducer, (10b ') and (10c) are electrode plates, respectively. (11) is an excitation
source. In this piezoelectric ultrasonic transducer, the outer wall and the inner wall of the
annular piezoelectric transducer (10a) are covered with the electrode plates (] Ob), (10c), and the
excitation source is applied to each electrode plate (10b), (10c) 11) are connected, and the
piezoelectric phenomenon (piezo electric transducer) of direct voltage effect and reverse voltage
effect is used. In addition to the PZT, it is possible to use a single crystal such as lithium niobate
(LiNb03) or a ceramic such as barium titanate for the piezoelectric vibrator (10a), or it is easy to
form and the Curie temperature is high (300 °) and stable. The piezoelectric effect is widely
used in PZT. FIG. 5 is a diagram showing the frequency characteristic of the piezoelectric
ultrasonic transducer shown in FIG. 4. As shown in FIG. 5, the frequency characteristic of this
piezoelectric ultrasonic transducer is a cylindrical piezoelectric transducer (10a It is determined
by the size of the diameter of> and has a single-peaked relatively narrow bandwidth excitation
frequency. [Problems to be Solved by the Invention] The conventional piezoelectric ultrasonic
transducer as described above is configured as described above, and its frequency characteristic
has a single-peaked relatively narrow bandwidth excitation frequency. Therefore, there is a
problem that it is difficult to use a signal technology such as a chirp signal technology or a
pseudo noise signal technology that requires a wide excitation frequency, for example, when
used in a fish finder. The present invention has been made to solve the problem and has an
object to obtain a piezoelectric ultrasonic transducer having a wide bandwidth with a simple
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configuration. [Means for Solving the Problems] The piezoelectric ultrasonic vibrator according
to the present invention comprises a plurality of toroidal or truncated conical piezoelectric
vibrator units having slightly different diameters, and the size of the diameter of each unit. In
order and with their axes aligned, or mechanically coupled between adjacent piezoelectric
vibrator units to form a single conical cylindrical piezoelectric vibrator . [Operation] According to
the present invention, with the above-described configuration, the peaks of the excitation
frequency can be superimposed with slight differences, and the frequency band can be
equivalently equivalent.
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a view showing an embodiment of the present invention, and FIG. 1 (A) is a perspective
view showing an outline of the configuration of a piezoelectric ultrasonic transducer according to
an embodiment of the present invention; Is a partial cross-sectional view thereof, and in the
figures (1) to (3) respectively show the whole of the truncated cone-shaped piezoelectric
ultrasonic transducer unit having different diameters, and (1a) to (3a) show the respective
piezoelectric vibrations The child unit, (lb) to (3b) is an outer wall electrode plate covering the
outer diameter wall of each of the piezoelectric vibrators (1a) to (3a), (IC) to (3C) 1a) to (3a) inner
wall electrode plate covering the inner diameter wall, (4) has acoustic characteristics such as
urethane rubber filled in the cylinder of each unit (1) to (3) close to water (5) is the outer
circumferential surface of the cylinder of each unit (1) to (3) and the end face of the cylinder
Smaller external reflection material formed Te acoustically reflective material such as cork
covering the end face of the, (6) shows the excitation source. As shown in FIG. 1, in the
piezoelectric ultrasonic transducer in this embodiment, a plurality of frusto-conical piezoelectric
transducers (la) to (3a) having different diameters are sequentially stacked with their axes
aligned, Outer wall electrode plates (1b) to (3b) are provided on the outer walls of the
piezoelectric vibrators (1a) to (3a), and inner wall electrode plates (IC) to (3C) are provided on
the inner walls, respectively. ) To (3b) are mutually connected in parallel to form one electrode
plate, and the inner wall electrode plates (IC) to (3C) are mutually connected in parallel to form
the other electrode plate, and these electrode plates The excitation source (6) is connected to to
form a single conical cylindrical piezoelectric ultrasonic transducer. Although not shown in FIG.
1, the entire piezoelectric ultrasonic transducer is waterproof-coated with urethane rubber or the
like, and the end face of the end face of the cylinder having the larger diameter is used as the
ultrasonic wave transmission / reception wavefront. Since each excitation frequency in each unit
(1) to (3) is inversely proportional to its diameter, the excitation frequency f1 of unit (1) is (D, + D
2) / 2, the excitation frequency f2 of unit (2) The excitation frequency f3 of (D2 + D3) / 2 unit (3)
is (D3 + D4) / 2, and the excitation frequency as shown in FIG. 2 as a whole can be equivalently
broadened in frequency. In the above embodiment, the whole of each of the piezoelectric
ultrasonic transducer units (1) to (3) is formed of the piezoelectric transducers (1a) to (3a), and
each of the units (1) to (3) Although (3) is stacked, the piezoelectric vibrator units (1a) to (3a) are
used as a part of each of the piezoelectric ultrasonic transducer units (1) to (3), and each unit (1)
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to (3) is used. ) May be mechanically coupled to form one conical cylindrical piezoelectric
vibrator.
FIG. 3 is a view showing another embodiment of the present invention, and FIG. 3 (A) shows a
plurality of cylindrical units (1) to (3) of different diameters stacked in parallel, FIG. (B) is formed
of the same piezoelectric material integrally with the units (1) to (3) at the beginning and,
similarly to the piezoelectric ultrasonic transducer shown in FIG. Can be The present invention is
not limited to these embodiments, and various shapes may be considered, such as using units
having different lengths for each unit (1) to (3) or using a trumpet-shaped one. By adjusting the
shape, it is possible to adjust the frequency characteristics to make it a piezoelectric ultrasonic
transducer suitable for charb signal technology and pseudo noise signal technology, and by
utilizing this invention, various types of fish finders can be obtained. Signal processing
techniques can be used. [Effects of the Invention] As described above, the invention makes it
possible to superimpose the peaks of the excitation frequency with slight differences, as a result
of which the frequency can be broadened, and chirp signal technology and pseudo It has become
possible to use signal processing technology that could not be easily used by fish finders, such as
noise signal technology, so that it is possible to achieve high sensitivity, low power consumption,
and miniaturization of fish finders. There is an effect that it can contribute.
[0002]
Brief description of the drawings
[0003]
FIG. 1 does not show an embodiment of the present invention, and FIG. 2 shows frequency
characteristics of the piezoelectric ultrasonic transducer in the embodiment shown in FIG. 1, and
FIG. 3 shows another embodiment of the present invention FIG. 4 is a diagram showing an
example, FIG. 4 is a diagram showing the structure of a conventional piezoelectric ultrasonic
transducer, and FIG. 5 is a diagram showing frequency characteristics of the conventional
piezoelectric ultrasonic transducer shown in FIG.
(1) to (3) are piezoelectric ultrasonic transducer units, (la) to (3a) are piezoelectric transducer
units, (1b) to (3b) are outer wall electrode plates, and (1c) to (3c) Is an inner wall electrode plate,
(4) is an internal filler, (5) is an external reflector, (6) is an excitation source 9).
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