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JP2004233064

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complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JP2004233064
[Purpose] The object of the present invention is to easily determine the directivity angle of the
ultrasonic wave transmitting / receiving surface regardless of the size of the radiation surface of
the ultrasonic wave transmitting / receiving element, and detect ultrasonic wave transmitting /
receiving elements of different frequencies in the same manner. The scope is to make ultrasonic
transducers of the same sensitivity. According to the present invention, in an ultrasonic
transducer for transmitting an ultrasonic wave and receiving a reflected wave, the ultrasonic
wave transmitting / receiving element, a reflection plate, and an ultrasonic wave transmitting /
receiving surface are integrated. Between the ultrasonic wave transmitting / receiving element
and the ultrasonic wave transmitting / receiving surface is an ultrasonic wave propagation path
via the reflection plate. [Selected figure] Figure 6
Ultrasonic transducer
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic transducer that transmits ultrasonic waves into water and receives reflected waves of
objects in the water such as fish. [0002] A fish finder is generally used as an ultrasonic sounding
device for measuring water depth and detecting a fish school in water. The fish finder comprises
an ultrasonic transducer, a display, an operation panel, a transmitter / receiver, etc., and is a
device for displaying the underwater situation. An ultrasonic transducer, which is one of the
components of a fish finder, uses many types of transmission and reception frequencies and
transmission power. Then, an ultrasonic transducer that transmits and receives ultrasonic waves
at a plurality of transmission and reception frequencies using one or more ultrasonic wave
transmitting and receiving elements is used. In fish school detection using ultrasonic waves, fish
whose length is short, such as Shirasu, has a body length longer than its wavelength (0.75 cm)
when the transmission / reception frequency is a high frequency such as 200 kHz. It becomes a
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large reflection signal level. In the case of a low frequency such as 50 kHz, since the body length
of Shirasu is shorter than its wavelength (3.0 cm), a small reflection signal level is obtained. In
addition, fish with a long length such as salmon and salmon as compared with the body length of
shirasu will have the salmon and salmon length as their wavelength (0.75, 3.10) regardless of
whether the transmission frequency is 200 kHz or 50 kHz. Since it is longer than 0 cm), a large
reflected signal level is obtained. Thus, in the detection of a school of fish, a fish species or the
like can be determined from the relationship between the frequency used and the level of the
reflected signal (see, for example, Patent Document 1). By the way, when detecting fish which
inhabit very shallow depth like shirasu, in order to widen the detection range, it is necessary to
widen the directivity angle of the ultrasonic wave emitted from the ultrasonic transducer. . In
addition, since the ultrasonic transducer vibrates at the mechanical resonance frequency of the
ultrasonic transducer, there is a property that the afterglow of the vibration remains. (This is
generally called reverberation. 2.) Reverberation occurs immediately after transmission, and the
near-field reflection signal is extinguished. As a method of reducing the influence of the
reverberation, immediately after transmission, the distance between the ultrasonic wave
transmitting / receiving element and the bottom of the ship is set larger than the ultrasonic wave
propagation distance of the reverberation time of the ultrasonic wave transmitting / receiving
element. A method is disclosed to eliminate the effects of reverberation that occur in And
according to this example, FRP (strengthening plastic) is used for the transmission-and-reception
wave face of an ultrasonic wave (for example, refer patent document 2) (1st prior art).
In general, the directivity angle θ of the ultrasonic wave radiated from the ultrasonic wave
transmitting / receiving element is s, where the radiation area of the ultrasonic wave transmitting
/ receiving element is f and the transmission / reception frequency (driving frequency of the
ultrasonic transducer) is f It is given by <img class = "EMIRef" id = "198577860-00003" />.
Further, since the allowable input power of the ultrasonic wave transmitting / receiving element
is proportional to the radiation area s, the input of the transmission power more than the
allowable input power determined by the radiation area s causes the destruction of the ultrasonic
wave transmitting / receiving element. If the radiation area s is made the same in order to enable
input of the same transmission power in each of the ultrasonic wave transmitting and receiving
elements for 200 kHz (high frequency) and 50 kHz (low frequency), From the equation, the
directivity angle of the high frequency ultrasonic transducer is 1/4 of that of the low frequency,
and the directivity angles of the two are different. Therefore, in order to make the directivity
angles of the two equal, the first method can be considered in which the radiation area of the
high-frequency ultrasonic transducer is set to 1/16 of the low-frequency radiation area according
to the equation (1) . Conversely, a second method may be considered in which the radiation area
of the low frequency ultrasonic transducer is made 16 times the radiation area of the high
frequency. As a method of changing the directivity angle without changing the radiation area,
there is a method of adjusting the directivity angle by changing the radiation direction of the
ultrasonic wave by making the radiation surface shape of the ultrasonic transducer element
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convex or concave. Usually, a large number of minute ultrasonic transducer elements are used,
and each radiation surface is arranged to form a convex surface or a concave surface. Another
method is to place an acoustic lens on the radiation surface of the transducer. Since ultrasonic
waves are also waves similar to light and are refracted according to Snell's law, ultrasonic waves
can be converged or diverged by using convex lenses or concave lenses made of materials with
different sound speeds, and the same for high and low frequencies. A configuration can be
considered in which the directional angle of Further, as another method, there is disclosed a
method of making the directivity angles the same by arranging a cone-shaped reflector and a
plurality of cylindrical transmitting and receiving elements having different transmitting and
receiving frequencies on the axis thereof. ing. (For example, refer to Patent Document 3) (Second
Prior Art) Patent Document 1 Japanese Patent Publication No. 40-025555 Patent Document 2
Japanese Utility Model Publication No. 05-026545 Patent Document 3 Japanese Utility Model
Application Publication No. 57 As described above, according to the equation (1), either of the
radiation areas of the ultrasonic transmitting and receiving elements whose transmitting and
receiving frequencies are high frequency or low frequency are given. By making one larger or
smaller, the directivity angles of both can be made the same.
However, by reducing the radiation area of the high-frequency ultrasonic transducer element,
when making the directivity angles of the two equal, no large transmission power can be applied
to the ultrasonic transducer element having a small radiation area, and as a result, There is a
drawback that the high frequency detection ability is inferior. Further, increasing the radiation
area of the low frequency ultrasonic transducer has a problem that the low frequency ultrasonic
transducer becomes extremely large and expensive. In the second related art, a plurality of
cylindrical ultrasonic transducer elements having different transmitting and receiving
frequencies are arranged on the axis of a cone-shaped reflector, and ultrasonic waves emitted
from the ultrasonic transducer elements are cone-shaped. It is reflected by the mold reflecting
plate, and the radiation directions of the ultrasonic waves are made the same. And, in the second
prior art, in order to use a 45 degree cone type planar reflector, in order to reduce the directivity
angle, the radiation surface of the ultrasonic wave transmitting / receiving element itself is
lengthened, or plural ultrasonic wave transmission / reception of the same frequency is
performed. It is necessary to arrange the wave elements vertically to make the ultrasonic
radiation surface longer. Therefore, there is a problem that the more the number of ultrasonic
wave transmitting / receiving elements, the more expensive. Further, in the method of changing
the radiation direction by making the radiation surface shape of the ultrasonic wave transmitting
/ receiving element convex or concave, a large number of minute ultrasonic wave transmitting /
receiving elements are used, and each radiation surface forms a convex or concave It is arranged
and configured. However, in this configuration, a large number of ultrasonic transmitting and
receiving elements are required, and the number of wires is increased. Therefore, there is a
problem that the ultrasonic transducer becomes complex and expensive. Furthermore, in the
method of placing the acoustic lens on the radiation surface of the ultrasonic transducer, the
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acoustic impedance must be taken into consideration, and there is a problem that the material is
limited to extremely special materials. Therefore, it is an object of the present invention to easily
determine the directivity angle at the ultrasonic wave transmitting / receiving wavefront
regardless of the size of the radiation surface of the ultrasonic wave transmitting / receiving
element, and to transmit and receive ultrasonic waves of different frequencies. An element is an
ultrasonic transducer having the same detection range and the same sensitivity. In the first prior
art, the distance between the ultrasonic transducer and the bottom of the ship is selected to be
larger than the ultrasonic wave propagation distance of the reverberation time of the ultrasonic
transducer. The ultrasonic wave transmitting and receiving surface uses a material which
transmits ultrasonic waves, for example, a material such as FRP (reinforced plastic), which is
compatible with the material of the bottom of a ship. For this reason, water and acoustic
impedance differ, and there is a problem that an ultrasonic wave attenuates. Therefore, according
to a second object of the present invention, by providing an ultrasonic wave propagation path
larger than the reverberation time in the ultrasonic transducer, the ultrasonic wave is not
influenced by the reverberation occurring immediately after transmission. An object of the
present invention is to provide an ultrasonic transducer which is hard to attenuate ultrasonic
waves transmitted and received by a transmitting and receiving wave surface.
Further, in each of the above-described conventional techniques, there is no ultrasonic
transducer which is integrally molded including the ultrasonic wave transmitting / receiving
element, the reflection plate and the ultrasonic wave transmitting / receiving wave surface.
Therefore, still another object of the present invention is to provide an ultrasonic transducer
including an integrated ultrasonic transducer, a reflection surface and an ultrasonic transducer.
SUMMARY OF THE INVENTION In order to achieve the above object, according to the invention
of claim 1, an ultrasonic transducer for transmitting ultrasonic waves and receiving the reflected
waves, which comprises transmitting and receiving ultrasonic waves Integrally including the
wave element, the reflection plate, and the ultrasonic wave transmission / reception surface, and
the ultrasonic wave propagation path through the reflection plate is configured between the
ultrasonic wave transmission / reception element and the ultrasonic wave transmission /
reception surface It is done. Next, in the invention of claim 2, a plurality of ultrasonic wave
transmitting and receiving elements are provided. Further, in the invention of claim 3, the
directivity angles of the ultrasonic radiation at the corresponding ultrasonic wave transmitting /
receiving wavefronts of the plurality of ultrasonic wave transmitting / receiving elements are
configured to be the same. Further, according to the invention of claim 4, the propagation path
length between the ultrasonic wave transmitting / receiving element and the corresponding
ultrasonic wave transmitting / receiving surface is the ultrasonic wave of the reverberation time
of the ultrasonic wave transmitting / receiving element in the medium of the propagation path. It
is configured to be longer than the propagation distance. According to the invention of claim 5,
the medium of the propagation path between the ultrasonic wave transmitting / receiving
element and the corresponding ultrasonic wave transmitting / receiving surface is configured to
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be the same medium as the corresponding ultrasonic wave transmitting / receiving surface .
According to the invention of claim 6, as the reflector interposed between the ultrasonic wave
transmitting / receiving element and the corresponding ultrasonic wave transmitting / receiving
surface, a curved surface reflecting plate and a plane reflecting plate are used singly or in
combination. It is configured. DETAILED DESCRIPTION OF THE INVENTION Preferred
embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a sectional view showing an ultrasonic transducer 1 according to a first embodiment of
the present invention. The transducer case 10 is a box-shaped case of urethane rubber. The
ultrasonic wave transmitting / receiving surface 40, which is an inlet / outlet surface of
ultrasonic waves into water, is a thick line portion on the lower side of the figure. The acoustic
impedance of the urethane rubber is substantially equal to that of water and seawater, and is a
material which has a very small reflection loss at the ultrasonic wave transmitting / receiving
surface 40 and transmits the ultrasonic wave well. FIG. 1a) is an example using a concave
reflector 20a in which the reflective surface of the reflector is concave, and FIG. 1b) uses a
convex reflector 20b in which the reflective surface of the reflector is convex. It is an example.
Hereinafter, the concave reflector 20 a or the convex reflector 20 b may be collectively referred
to as the curved reflector 20.
The transducer case 10 includes an ultrasonic transducer 30 and a curved reflector 20, which
are filled with a filler 12. The ultrasonic wave transmitting / receiving element 30 is surrounded
by the sound insulating material 21 except for the radiation surface on one side. The sound
insulation member 21 plays a role of preventing the radiation of the ultrasonic wave in the
unnecessary direction from the ultrasonic wave transmitting / receiving element 30 or the
incidence of the ultrasonic wave on the ultrasonic wave transmitting / receiving element 30 from
the unnecessary direction. The radiation direction or the incident direction of the ultrasonic wave
from the ultrasonic wave transmitting / receiving element 30 is restricted to the direction of the
curved reflecting plate 20 by the sound insulation member 21. The material of the sound
insulating material 21 is a material such as a cork material or a single foam sponge which is
weak in rigidity and has air bubbles inside. The ultrasonic transducer 30 is a piezoelectric
ceramic element such as barium titanate. The ultrasonic wave transmitting / receiving element
30 has two electrodes (not shown), and two signal lines extend from each electrode. An electrical
pulse signal in the form of a tone burst at the resonant frequency of the ultrasonic transducer 30
is input as a transmission signal to the two signal lines. Due to this transmission signal, the
ultrasonic wave transmitting / receiving element 30 is distorted due to the piezoelectric reverse
effect, and vibrates in the thickness direction of the ultrasonic wave transmitting / receiving
element 30, that is, in the left and right directions of FIG. It emits ultrasonic waves from the
surface. The curved reflecting plate 20 is made of an aluminum plate or the like, and a part
thereof is fixed to the transducer case 10 as shown, and the periphery thereof is filled with the
filler 12. For example, castor oil is used as the filler 12. Since the acoustic impedance of the
curved reflector 20 is larger than that of the filler 12, the curved reflector 20 reflects ultrasonic
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waves well in the filler 12. A slight amount of ultrasonic wave passes through the curved
reflector 20. In order to prevent the influence of the transmission, the same material as the
sound insulating material 21 may be attached to the opposite side of the curved reflecting plate
20 to the reflecting surface (not shown). The ultrasonic wave emitted from the ultrasonic wave
transmitting / receiving element 30 to the curved reflecting plate 20 is reflected by the curved
reflecting plate 20 and emitted from the ultrasonic wave transmitting / receiving surface 40 to
the outside of the ultrasonic wave transmitter / receiver 1. In FIG. 1a), the ultrasonic waves
reflected by the concave reflecting plate 20a have their beams converged, the directivity angle
becomes smaller, and they are emitted from the ultrasonic wave transmitting / receiving surface
40 to the outside of the ultrasonic transducer 1. Further, the ultrasonic wave incident from the
outside of the ultrasonic wave transmitter / receiver 1 is also reflected by the concave reflection
plate 20 a through the reverse path and is incident on the radiation surface of the ultrasonic
wave transmission / reception element 30. Similarly, in FIG. 1 b), the ultrasonic wave reflected by
the convex reflector 20 b has its beam diverged, the directivity angle becomes large, and it is
emitted from the ultrasonic wave transmitting / receiving surface 40 to the outside of the
ultrasonic transducer 1.
In addition, the ultrasonic wave incident from the outside of the ultrasonic wave transmitter /
receiver 1 is also reflected by the convex reflecting plate 20 b in the reverse path and is incident
on the radiation surface of the ultrasonic wave transmitting / receiving element 30. In each of
the ultrasonic transducers 1 of FIGS. 1a) and 1b), the directivity angle at the ultrasonic wave
transmitting / receiving surface 40 is changed by changing the curvature of the curved reflecting
plate 20 using the ultrasonic wave transmitting / receiving element 30 having the same radiation
area. Can be identical. FIG. 2 is a cross-sectional view showing an ultrasonic transducer 2
according to a second embodiment of the present invention. The description of the same
reference numerals as FIG. 1 will be omitted. The transducer case 10 includes an ultrasonic
transducer 30a, an ultrasonic transducer 30b, a curved reflector 20, and a flat reflector 20c,
which are filled with the filler 12 as in the first embodiment. There is. The flat reflector 20c is
also made of an aluminum plate or the like. In the present embodiment, the sizes of the radiation
planes of the ultrasonic transducer 30a and the ultrasonic transducer 30b are the same.
Therefore, assuming that the ultrasonic wave transmitting / receiving element 30a has a
transmitting / receiving frequency of 50 kHz and the ultrasonic wave transmitting / receiving
element 30b has a transmitting / receiving frequency of 200 kHz, the ultrasonic wave
transmitting / receiving element 30a has a directivity angle on the radiation surface than the
ultrasonic wave transmit / receive element 30b. Becomes smaller. FIG. 2A shows the directivity
angles of ultrasonic waves of different frequencies radiated from the ultrasonic wave
transmitting / receiving surface 40 by using the convex reflecting plate 20 b and the plane
reflecting plate 20 c to point the ultrasonic wave transmitting / receiving elements of high
frequency. It is a figure showing an example of composition adjusted to a corner. The ultrasonic
wave emitted from the ultrasonic wave transmitting / receiving element 30a to the plane
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reflecting plate 20c is reflected by the plane reflecting plate 20c and is emitted to the outside of
the ultrasonic transducer 2 at the directivity angle calculated by the equation (1). . Then, the
externally incident ultrasonic waves are incident on the radiation surface of the ultrasonic wave
transmitting / receiving element 30a through the reverse path. Similarly, the ultrasonic wave
emitted from the ultrasonic wave transmitting / receiving element 30b to the convex reflecting
plate 20b is reflected by the convex reflecting plate 20b and diverged. Therefore, by
appropriately selecting the curvature of the convex reflecting plate 20b, it is possible to emit the
ultrasonic transducer 2 at a directivity angle larger than the directivity angle calculated by the
equation (1). Then, the ultrasonic wave incident from the outside also enters the radiation surface
of the ultrasonic wave transmitting / receiving element 30 through the reverse path. FIG. 2 b)
shows the directivity angles of ultrasonic waves of different frequencies emitted from the
ultrasonic wave transmitting / receiving wave surface 40 by using the concave reflecting plate
20 a and the plane reflecting plate 20 c to point the ultrasonic wave transmitting / receiving
elements of low frequency. It is a figure showing an example of composition adjusted to a corner.
The ultrasonic wave emitted from the ultrasonic wave transmitting / receiving element 30a to
the concave reflecting plate 20a is reflected by the concave reflecting plate 20a and converged.
Therefore, by appropriately selecting the curvature of the concave reflecting plate 20a, the
ultrasonic wave transmitting / receiving surface 40 is emitted to the outside of the ultrasonic
transducer 2 at a directivity angle smaller than the directivity angle calculated by the equation
(1). be able to. Then, the ultrasonic wave incident from the outside also enters the radiation
surface of the ultrasonic wave transmitting / receiving element 30 through the reverse path.
Similarly, the ultrasonic wave emitted from the ultrasonic wave transmitting / receiving element
30b to the plane reflection plate 20c is reflected by the reflection plate 20c, and is emitted to the
outside of the ultrasonic wave transmitter / receiver 2 at the directivity angle calculated by
equation (1). Ru. Then, the externally incident ultrasonic waves are incident on the radiation
surface of the ultrasonic wave transmitting / receiving element 30a through the reverse path. In
the above-mentioned FIG. 2 a) and FIG. 2 b), the directivity angles at the respective radiation
planes of the ultrasonic transducer 30 a and the ultrasonic transducer 30 b differ depending on
the difference in frequency. However, by configuring as described above, by reflecting the
ultrasonic wave on the curved reflecting plate 20, it is possible to make the directivity angles at
the ultrasonic wave transmitting / receiving surface 40 the same. FIG. 3 is a cross-sectional view
showing the structure of an ultrasonic transducer 3 according to a third embodiment of the
present invention. The description of the same reference numerals as FIG. 2 will be omitted. As in
the case of FIG. 2, the sizes of the radiation planes of the ultrasonic wave transmitting / receiving
elements of the ultrasonic wave transmitting / receiving element 30a and the ultrasonic wave
transmitting / receiving element 30b are the same. FIG. 3A shows an example in which the
directivity angles of ultrasonic waves of different frequencies emitted from the ultrasonic wave
transmitting / receiving surface 40 are made the same by respectively converging or diverging
using the concave reflecting plate 20a and the convex reflecting plate 20b. FIG. The ultrasonic
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wave emitted from the ultrasonic wave transmitting / receiving element 30a (the transmitting /
receiving frequency is lower than that of the ultrasonic wave transmitting / receiving element
30b) to the concave reflection plate 20a is reflected by the concave reflection plate 20a and
converged. Therefore, by appropriately selecting the curvature of the concave reflecting plate
20a, the ultrasound transmitting / receiving surface 40 is emitted to the outside of the ultrasonic
transducer 3 at a directivity angle smaller than the directivity angle calculated by the equation
(1). be able to. Then, the ultrasonic wave incident from the outside also enters the radiation
surface of the ultrasonic wave transmitting / receiving element 30 through the reverse path.
Similarly, the ultrasonic wave radiated from the ultrasonic wave transmitting / receiving element
30b (the transmitting / receiving frequency is higher than that of the ultrasonic wave
transmitting / receiving element 30a) to the convex reflecting plate 20b is reflected by the
convex reflecting plate 20b and diverged. Accordingly, by appropriately selecting the curvature
of the convex reflecting plate 20b, the ultrasonic wave transmitting / receiving surface 40 emits
radiation to the outside of the ultrasonic transducer 3 at a directivity angle larger than the
directivity angle calculated by the equation (1). be able to. Then, the ultrasonic wave incident
from the outside also enters the radiation surface of the ultrasonic wave transmitting / receiving
element 30a through the reverse path.
FIG. 3 b) shows different frequencies emitted from the ultrasonic wave transmitting / receiving
surface 40 by reflecting and diverging both by using the convex reflecting plate 20 b and the
convex reflecting plate 20 d having a curvature larger than that of the convex reflecting plate 20
b. It is a figure which shows the example which makes the directivity angle in the ultrasonic wave
transmission-and-reception wave surface of the same. The convex reflecting plate 20d is made of
an aluminum plate or the like. Here, the ultrasonic wave transmitting / receiving elements 30a
and 30b have ultrasonic wave transmitting / receiving radiation surfaces of the same size. The
ultrasonic wave emitted from the ultrasonic wave transmitting / receiving element 30a (the
transmission / reception frequency is lower than that of the ultrasonic wave transmitting /
receiving element 30b) to the convex reflecting plate 20b is reflected by the convex reflecting
plate 20b and diverged. Therefore, by appropriately selecting the curvature of the convex
reflecting plate 20b, radiation from the ultrasonic wave transmitting / receiving surface 40 to the
outside of the ultrasonic transducer 3 is performed at a directivity angle larger than the
directivity angle calculated by the equation (1). can do. Then, the ultrasonic wave incident from
the outside also enters the radiation surface of the ultrasonic wave transmitting / receiving
element 30a through the reverse path. Similarly, the ultrasonic wave radiated from the ultrasonic
wave transmitting / receiving element 30b (the transmission / reception frequency is higher than
that of the ultrasonic wave transmitting / receiving element 30a) to the convex reflecting plate
20d is reflected by the convex reflecting plate 20d and diverged. Therefore, by appropriately
selecting the curvature of the convex reflecting plate 20d, radiation from the ultrasonic wave
transmitting / receiving surface 40 to the outside of the ultrasonic transducer 3 is performed at a
directivity angle larger than the directivity angle calculated by the equation (1). Be done. Then,
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the ultrasonic wave incident from the outside is also incident on the radiation surface of the
ultrasonic wave transmitting / receiving element 30b through the reverse path. The directivity
angles at the respective radiation planes of the ultrasonic transducer 30a and the ultrasonic
transducer 30b are different. However, by reflecting the ultrasonic wave by an appropriate
curved reflecting plate 20, the directivity angle when emitted from the ultrasonic wave
transmitting / receiving surface 40 can be made to be a directivity angle of a predetermined
frequency. FIG. 4 is a cross-sectional view showing an ultrasonic transducer 4 according to a
fourth embodiment of the present invention. The description of the same reference numerals as
FIG. 2 will be omitted. Inside the transducer case 10, there are an ultrasonic wave transmitting /
receiving element 30, a curved reflecting plate 20, and a flat reflecting plate 20c, which are filled
with the filler 12 as in the first embodiment. FIG. 4A shows that the ultrasonic wave emitted from
the ultrasonic wave transmitting / receiving element 30 is emitted from the ultrasonic wave
transmitting / receiving surface 40 by using the planar reflecting plate 20 c and the convex
reflecting plate 20 b by using two reflecting plates. It is a figure which shows the example which
enlarges the directivity angle of the ultrasonic wave to be carried out. Further, by using the flat
reflecting plate 20c and the convex reflecting plate 20b, the path length from the ultrasonic wave
transmitting / receiving element 30 to the ultrasonic wave transmitting / receiving wavefront 40
is lengthened.
The ultrasonic wave emitted from the ultrasonic wave transmitting / receiving element 30 to the
plane reflecting plate 20c is reflected by the plane reflecting plate 20c. Then, the path-changed
ultrasonic wave is further reflected by the convex reflector 20 b and diverges. Thus, the
ultrasonic wave emitted from the ultrasonic wave transmitting / receiving element 30 is emitted
from the ultrasonic wave transmitting / receiving surface 40 at a directivity angle larger than the
directivity angle at the radiation surface of the ultrasonic wave transmitting / receiving element
30. Then, the ultrasonic wave incident from the ultrasonic wave transmitting / receiving surface
40 is incident on the radiation surface of the ultrasonic wave transmitting / receiving element 30
in the reverse path. FIG. 4 b) shows that the ultrasonic wave emitted from the ultrasonic wave
transmitting / receiving element 30 is emitted from the ultrasonic wave transmitting / receiving
surface 40 by using the concave reflecting plate 20 a and the plane reflecting plate 20 c by using
two reflecting plates. It is a figure which shows the example which makes the directivity angle of
the ultrasonic wave to be reduced. Also, as in FIG. 4a), the path length of the ultrasonic wave is
increased. The ultrasonic wave emitted from the ultrasonic wave transmitting / receiving element
30 to the plane reflecting plate 20c is reflected by the plane reflecting plate 20c. Then, the pathchanged ultrasonic waves are further reflected by the concave reflection plate 20 a and
converged. Thus, the ultrasonic wave emitted from the ultrasonic wave transmitting / receiving
element 30 is emitted from the ultrasonic wave transmitting / receiving surface 40 at a
directivity angle smaller than the directivity angle at the radiation surface of the ultrasonic wave
transmitting / receiving element 30. Then, the ultrasonic wave incident from the outside of the
ultrasonic transducer 4 is incident on the radiation surface of the ultrasonic wave transmitting /
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receiving element 30 through the reverse path. FIG. 4 c) shows ultrasonic transmission /
reception when the directivity angle of the ultrasonic wave emitted from the ultrasonic wave
transmission / reception element 30 is emitted from the ultrasonic wave transmission / reception
surface 40 using two convex reflecting plates 20 b. FIG. 7 is a diagram showing an example in
which the directivity angle emitted from the element 30 is made larger. The ultrasonic wave
emitted from the ultrasonic wave transmitting / receiving element 30 to the convex reflecting
plate 20b-1 is reflected and diverged. Then, the path-changed ultrasonic wave is further reflected
and diverged by the convex reflecting plate 20b-2. As described above, the ultrasonic wave
transmitting / receiving surface 40 emits radiation with a directivity angle larger than the
directivity angle when emitted from the ultrasonic wave transmitting / receiving element 30.
Then, the ultrasonic wave incident from the outside is incident on the radiation surface of the
ultrasonic wave transmitting / receiving element 30 through the reverse path. As in the present
embodiment, by using a plurality of reflecting plates, the ultrasonic wave transmitting / receiving
element 30 can be made almost without lengthening the width of the transmitter / receiver case
10, that is, the horizontal direction of the transmitter / receiver radiation surface of FIG. It is
possible to lengthen the propagation path between and the ultrasonic wave transmitting /
receiving surface 40. At the same time, the directivity angle of the ultrasonic wave transmission /
reception surface 40 can be set arbitrarily. FIG. 5 is a cross-sectional view showing the structure
of an ultrasonic transducer 5 according to a fifth embodiment of the present invention.
The description of the same reference numerals as FIG. 2 will be omitted. In the transducer case
10, there are an ultrasonic wave transmitting / receiving element 30 and a plurality of reflecting
plates including a curved reflecting plate 20, which are filled with a filler 12 as in the first
embodiment. In this embodiment, the ultrasonic wave transmitting / receiving elements 30a and
30b, the flat reflecting plate 20c and the curved reflecting plate 20 are provided. FIG. 5a) is
constructed using a concave reflector 20a and a plurality of planar reflectors 20c. In the present
embodiment, the paths and directivity angles of the ultrasonic waves radiated from the ultrasonic
wave transmitting / receiving elements 30a and 30b are the same as those described above, and
the description thereof is omitted. FIG. 5 b) is configured using a plurality of curved reflectors 20
and a plurality of planar reflectors 20 c. Also in the present embodiment, the paths and
directivity angles of the ultrasonic waves radiated from the ultrasonic wave transmitting /
receiving elements 30a and 30b are the same as those described above, and the description
thereof will be omitted. FIG. 6 is a cross-sectional view showing the structure of an ultrasonic
transducer 6 according to a sixth embodiment of the present invention. The structure and
principle in the transmitter / receiver case 10 are the same as in the other embodiments, and
therefore the description of the components described above is omitted. In the present
embodiment, the medium of the ultrasonic wave propagation path is not the filler 12 but the
filler 13. The filler 13 is made of the same material as the ultrasonic wave transmitting /
receiving surface 40, for example, urethane rubber. As a result, the manufacturing cost is
lowered, and the same acoustic impedance is obtained up to the radiation surface ultrasonic
03-05-2019
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wave transmission / reception surface 40 of the ultrasonic wave transmission / reception
elements 30a and 30b, and the attenuation of the ultrasonic wave signal can be reduced. In the
above embodiments, it has been described that the size of the radiation surface of the
transmitting and receiving wavefront of the ultrasonic transmitting and receiving element is the
same. If the size of the radiation surface of the ultrasonic transducer is the same, the transmit
power that can be supplied is also the same, and the detection range, sensitivity, etc. of the
ultrasonic transducer can also be the same. In addition, by changing the curvature of the curved
reflector incorporated in the ultrasonic transducer of the present invention, a plurality of
ultrasonic transducers of the same transmission frequency are provided, and the pointing angles
of the respective ultrasonic transducers are determined. It can be made different. As described
above in detail, the ultrasonic transducer according to the present invention is integrated by
including the ultrasonic wave transmitting / receiving element, the reflection plate and the
ultrasonic wave transmitting / receiving surface. When the ultrasonic wave emitted from the
ultrasonic transducer is emitted from the ultrasonic transducer without changing the size and
shape of the radiation surface of the ultrasonic transducer by being reflected by the reflection
plate. Can change the pointing angle of ultrasonic waves.
Therefore, the detection ranges and sensitivities of the ultrasonic transducer with a plurality of
frequencies having different transmission and reception frequencies can be made the same.
Furthermore, with ultrasonic transducers having a plurality of transmission and reception
frequencies that are the same, the effect of enabling more precise detection can be achieved by
providing different directivity angles. Further, by reflecting the ultrasonic wave emitted from the
ultrasonic wave transmitting / receiving element to the reflection plate, the propagation path in
the ultrasonic wave transmitting / receiving device becomes long, and the reverberation
immediately after the transmission of the ultrasonic wave transmitting / receiving element is
affected. The effect of being able to detect the vicinity of the ultrasonic transducer is exhibited
without being <Brief Explanation of Drawings> <Figure 1> It is the cross section diagram which
shows the ultrasonic transducer 1 of 1st execution example of this invention. FIG. 2 is a crosssectional view showing an ultrasonic transducer 2 according to a second embodiment of the
present invention. FIG. 3 is a cross-sectional view showing an ultrasonic transducer 3 according
to a third embodiment of the present invention. FIG. 4 is a cross-sectional view showing an
ultrasonic transducer 4 according to a fourth embodiment of the present invention. FIG. 5 is a
cross-sectional view showing an ultrasonic transducer 5 according to a fifth embodiment of the
present invention. FIG. 6 is a cross-sectional view showing an ultrasonic transducer 6 according
to a sixth embodiment of the present invention. Explanation of code 10 Transducer case 12 Filler
13 Filler 20 Curved reflector 20a Concave reflector 20b Convex reflector 20c Flat reflector 20d
Convex reflector 21 Sound insulation material 30 Ultrasonic wave transceiver 30a Ultrasonic
wave transceiver Element 30b Ultrasonic transducer 40 Ultrasonic transducer
03-05-2019
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