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JP2008294719

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2008294719
[PROBLEMS] To obtain a compact transmitter that oscillates a low frequency sound wave with a
wide bandwidth and a high output. A first bending wave transmitter (10) is composed of a
diaphragm (11) and a diaphragm (12) having the same shape. The vibrating portion 11
comprises a metal disc plate 111 and an active plate 112 embedded in a form fitted to one
surface of the metal disc plate 111. The shape of the active plate 112 is also a substantially disc
shape. The diaphragm 12 also comprises a metal disc plate 121 and an active plate 122.
Deflections (dotted lines) generated in the first bending transmitter 10 and the second bending
transmitter 20 have opposite phases. That is, the bending direction of the diaphragm 11 and the
bending direction of the diaphragm 21 are opposite, and the bending direction of the diaphragm
12 and the bending direction of the diaphragm 22 are also opposite. [Selected figure] Figure 1
Transmitter and method of driving the same
[0001]
The present invention relates to a transmitter that emits a sound wave using a piezoelectric
ceramic and a method of driving the same.
[0002]
For example, ultrasonic waves and sound waves having a frequency lower than that are used for
long distance sonar and marine resource exploration.
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1
For these applications, sound waves with a small propagation loss in water and frequencies with
a long reach of several kHz are suitable, and in particular, transmitters capable of transmitting
sound waves with such frequencies are used. . This transmitter is required to be able to oscillate
a sound wave of this frequency at a high output, and is also required to be compact according to
the use situation. However, the energy of the transmitted sound wave becomes smaller as the
frequency is lower. Also, in general, if the transmitter is miniaturized, the resonant frequency is
increased. For this reason, it is difficult to cause low-frequency sound waves to oscillate at high
output with a small size transmitter. In order to achieve high output at low frequencies, it is
particularly necessary to increase the amount of displacement (amplitude) in vibration.
[0003]
On the other hand, the frequency emitted by such a transmitter is not constant but preferably
variable. For this reason, it is also required that the frequency band of the sound wave which can
oscillate is wide.
[0004]
As a transmitter that satisfies these requirements, there is a transmitter using a piezoelectric
ceramic (ceramic) described, for example, in Patent Documents 1 and 2. These utilize
piezoelectric characteristics of the piezoelectric ceramic, that is, minute displacements generated
by minute deformation due to voltage application. In these, in particular, a structure in which a
minute displacement of this piezoelectric ceramic is amplified to increase a displacement amount
finally obtained is taken.
[0005]
Patent Document 1 describes a bending disk type wave transmitter having a structure shown in
FIG. The wave transmitter 60 has a structure in which an active disc body 62 made of
piezoelectric ceramic is fitted in a recess formed in a pair of metal discs 61. These metal disks 61
are pasted together via a metal ring 63 having a low Young's modulus, and fixed by bolts 64 near
the outer periphery of the metal disks 61. Further, in this structure, a protective plate 65 and a
urethane resin 66 for protecting around the outer diameter are used. According to this structure,
the original displacement of the active disk 62, which is a piezoelectric body, is amplified as a
deflection of the metal disk 61 into which it is incorporated, and a large displacement can be
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obtained.
[0006]
Patent Document 2 describes a similar structure in which a metal disc is fixed to the outer
peripheral portion of the metal disc via a ring structure having a particularly high strength. Also
in this structure, a large amount of displacement could be obtained as well.
[0007]
With these structures, the displacement amount inherent to the active disc (piezoelectric
ceramic) is amplified to obtain a large displacement amount, whereby it is possible to obtain a
transmitter that oscillates a sound wave of high output even at low frequency.
[0008]
On the other hand, such a piezoelectric vibrator (piezoelectric ceramic) generally has a very high
Q value due to its resonance characteristics, and the oscillation frequency bandwidth of the
piezoelectric vibrator itself is very narrow.
Therefore, in order to obtain a wide frequency band using piezoelectric ceramic, according to
Patent Document 3, in a structure in which a plurality of cylindrical piezoelectric vibrators are
stacked with their central axes aligned, the phase of the voltage applied to each vibrator and An
ultrasonic transducer is described in which the amplitude is controlled to broaden the bandwidth.
This ultrasonic transducer was particularly suitable as an ultrasonic distance meter in air or a
transducer for obstacle search.
[0009]
JP-A-5-219588 JP-A-5-344582 JP-A-10-234498
[0010]
Although the transmitters described in Patent Documents 1 and 2 described above have high
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output, when the size is reduced, the acoustic load is reduced because the radiation surface of the
sound wave is also reduced, and the frequency bandwidth is reduced. .
Therefore, the frequency band of the sound wave that can oscillate is narrowed. For example, the
relative bandwidth (bandwidth / center frequency) was at most about 10 to 20%.
[0011]
Conversely, the bandwidth of the transmitter (ultrasonic transducer) described in Patent
Document 3 is sufficiently wide for this, and the performance is sufficient for ultrasonic
oscillation in the atmosphere. However, when the acoustic characteristic impedance is higher
than the atmosphere, especially in water, it has been impossible to obtain a sufficiently high
output.
[0012]
Therefore, it has been difficult to obtain a compact transmitter that oscillates a wide frequency
band sound wave at a high output.
[0013]
The present invention has been made in view of the above problems, and an object thereof is to
provide a transmitter and a method of driving the transmitter which solve the above problems.
[0014]
The present invention has the following configuration in order to solve the above-mentioned
problems.
The gist of the invention according to claim 1 is a diaphragm made of a piezoelectric ceramic,
which comprises an active plate generating displacement when a voltage is applied, and a metal
disc plate having the active plate embedded in one surface. Are connected via a metal ring on the
other surface side of the metal disc plate, and a plurality of bending type wave transmitters are
combined that oscillate sound waves by vibrating the two diaphragms in the opposite direction to
each other. It is a wave device, and a plurality of the bending type transmitters having different
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resonance frequencies are stacked in the order of high and low of the resonance frequency, and
the vibrations in the adjacent bending type transmitters are driven to be in opposite phase.
Resides in a transmitter characterized by
The gist of the invention according to claim 2 is that the transmission according to claim 1 is
characterized in that three or more of the bent transmitters are combined, and the distance
between the bent transmitters is substantially constant. It exists in the wave. The gist of the
invention according to claim 3 is characterized in that the polarization directions of the two
active plates in each of the bent wave transmitters are directions perpendicular to the surface of
the active plate and opposite to each other. It exists in the wave transmitter of Claim 1 or 2. The
gist of the invention according to claim 4 is that, in the plurality of bending type transmitters, the
polarization direction of one active plate in one bending type transmitter is another bending type
transmission adjacent to the one active plate. The transmitter according to claim 3, wherein the
direction of polarization is the same as the polarization direction of the active plate located on
the side of the one active plate in the wave device. The gist of the invention according to claim 5
is that, in the plurality of bending type transmitters, the polarization direction of one active plate
in one bending type transmitter is another bending type transmission adjacent to the one active
plate. The transmitter according to claim 3, wherein the polarization direction of the active plate
located on the side of the one active plate in the wave device is opposite to the polarization
direction. The gist of the invention according to claim 6 is set such that the frequency
characteristics of the oscillation gain of each of the adjacent bent transmitters intersect at a point
where the oscillation gain of each bent transmitter is 3 dB to 8 dB lower than the maximum gain.
The transmitter according to any one of claims 1 to 5, characterized in that: The gist of the
invention according to claim 7 is a diaphragm made of a piezoelectric ceramic, which comprises
an active plate generating displacement when a voltage is applied, and a metal disk plate having
the active plate embedded in one surface. Are joined together via a metal ring on the other
surface side of the metal disk plate, and a plurality of bending type wave transmitters are
oscillated that oscillate sound waves by the two diaphragms vibrating in opposite directions to
each other. A method of driving a transmitter, wherein resonance frequencies of the bent
transmitters are made different, and a plurality of the bent transmitters are stacked at
substantially constant intervals in the order of the resonance frequency, and adjacent to each
other. The present invention relates to a method of driving a transmitter characterized in that the
vibration in the bending type transmitter to be fitted is driven as the opposite phase.
[0015]
According to the present invention, it is possible to obtain a compact transmitter that oscillates a
sound wave in a wide frequency band at a high output.
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[0016]
First Embodiment FIG. 1 is a diagram showing a configuration of a transmitter according to a
first embodiment of the present invention.
The transmitter 1 is composed of a first bending transmitter 10 and a second first bending
transmitter 20. These bend type transmitters generate sound waves corresponding to their
frequencies by being driven by the same AC oscillator. The first bending type transmitter 10 and
the second first bending type transmitter 20 both have a substantially disc-like shape, and FIG. 1
shows a sectional view of the laminated structure. Note that the sound wave referred to here
includes ultrasonic waves in addition to sound waves that are audible to humans.
[0017]
The first bending type wave transmitter 10 is constituted of a diaphragm 11 and a diaphragm 12
which have the same shape. The vibrating portion 11 comprises a metal disc plate 111 and an
active plate 112 embedded in a form fitted to one surface of the metal disc plate 111. The shape
of the active plate 112 is also a substantially disc shape. The diaphragm 12 also comprises a
metal disc plate 121 and an active plate 122.
[0018]
The metal disc plates 111 and 121 are made of aluminum alloy. The active plates 112 and 122
are made of piezoelectric material, for example, made of hard lead zirconate titanate piezoelectric
ceramic, and fixed to the metal disk plates 111 and 121 by an adhesive or the like. In addition,
spontaneous polarization is applied so that the active plates 112 and 122 have piezoelectric
characteristics. This direction is the direction indicated by the white arrow in FIG. 1, and is the
upper side in the active plate 112 and the lower side in the active plate 122, that is, the reverse
direction. Electrodes (not shown) are formed on the upper side of the active plate 112 and the
lower surface of the active plate 122 in FIG. 1, and these electrodes are electrically connected
and connected to the input 1 . The metal disc plates 111 and 121 are also electrically connected
and connected to the input 2.
[0019]
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A convex ring 13 having a ring shape is provided on an outer peripheral portion of the other
surface of the diaphragm 11 viewed from the surface on which the active plate 112 is formed. A
concave ring 14 is provided on the outer peripheral portion of the other surface of the
diaphragm 12 as viewed from the surface on which the active plate 122 is formed. As shown in
FIG. 1, the diaphragms 11 and 12 are fixed in a shape in which the convex ring (metal ring) 13
and the concave ring (metal ring) 14 are fitted at the outer peripheral portion. Therefore, in the
first bending transmitter 10, the active plate 112 is exposed on the upper side, and the active
plate 122 is exposed on the lower side. An adhesive or a bolt (not shown) or the like is used for
this fixing. The convex ring 13 and the concave ring 14 are ring-shaped, and are made of a metal
material having high wear resistance such as Cr-Mo steel. The distance between the diaphragm
11 and the diaphragm 12 after assembly can be adjusted by adjusting the shapes of the convex
ring 13 and the concave ring 14.
[0020]
About the above 1st bending | flexion type | mold transmitter 10, it is the same as that of what is
described in patent document 1, 2. FIG. That is, when an AC signal is applied between the input 1
and the input 2, displacement (vibration) corresponding to this is generated in the active plate
112 due to the piezoelectric effect. When the radial displacement of the disc generated in the
active plate 112 occurs, the metal disc plate 111 is deformed accordingly, but since it is fixed at
the outer peripheral portion, the dotted line in FIG. Deflection occurs as indicated by. That is,
bending vibration of the peripheral support is caused in the diaphragm 11. The
electromechanical coupling coefficient of the diameter spread vibration at this time is about 50
to 55%. Similarly, deflection occurs in the diaphragm 12, but due to the polarization direction
and the electrode configuration, this deflection is in the opposite direction to the diaphragm 11,
as shown by the broken line in FIG. This deflection occurs according to the frequency applied to
the active plate, and a sound wave corresponding to this is oscillated. The oscillation gain of this
sound wave becomes maximum at the resonance frequency (first resonance frequency f1)
determined by the configuration (material and geometrical configuration) of the diaphragm 11
and the diaphragm 12. Since the amplitude of this vibration is larger than the amplitude of the
radial vibration of the active plate, the sound wave is oscillated at a high output. Further, as
described in Patent Documents 1 and 2, the bending type transmitter 10 can generate a highoutput sound wave at a low frequency even if it is compact.
[0021]
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7
The configuration of the second bending transmitter 20 is also similar to that of the first bending
transmitter 10. That is, the diaphragms 21 and 22 are joined via the convex ring (metal ring) 23
and the concave ring (metal ring) 24. The diaphragm 21 comprises a metal disc plate 211 and an
active plate 212, and the diaphragm 22 comprises a metal disc plate 221 and an active plate
222. However, the outer diameter of the diaphragms 21 and 22 is smaller than that of the
diaphragms 11 and 12. For this reason, the frequency (second resonance frequency f2) at which
the oscillation gain of the sound wave oscillated by the second bending transmitter 20 is
maximum is higher than the first resonance frequency. Also, the distance between the first
bending transmitter 10 and the second bending transmitter 20 can be set appropriately.
[0022]
Here, as shown in FIG. 1, in FIG. 1, the polarization direction in the active plate 212 is the lower
side, and the polarization direction in the active plate 222 is the upper side. Alternatively, the
polarization direction of the lower active plate 122 in the bending transmitter 10 is the same as
the polarization direction of the active plate 212 located on the side of the active plate 122 in the
bending transmitter 20. That is, in the first bending transmitter 10 and the second bending
transmitter 20, their polarization directions are reverse to each other.
[0023]
On the other hand, the upper electrode of the active plate 212 and the lower electrode of the
active plate 222 are electrically connected and connected to the input 1. Similarly, the metal disc
plate 211 and the metal disc plate 221 are electrically connected and connected to the input 2.
Therefore, when an AC signal is applied between the input 1 and the input 2, the vibrators of the
first bending transmitter 10 and the second bending transmitter 20 vibrate in opposite directions
accordingly. A sound wave corresponding to the frequency of alternating current is oscillated.
[0024]
At this time, as shown in FIG. 1, the deflections (broken lines) generated in the first bending
transmitter 10 and the second bending transmitter 20 are in opposite phase. That is, the bending
direction of the diaphragm 11 and the bending direction of the diaphragm 21 are opposite, and
the bending direction of the diaphragm 12 and the bending direction of the diaphragm 22 are
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also opposite.
[0025]
This state means that, in the equivalent circuit, a transformer having a transformation ratio of
−1: 1 is incorporated in the bending transmitter 20. Because this transformer works effectively,
the transmitter shown in FIG. 1 forms a water-loaded multi-mode filter, which is more than three
times the single mode ratio bandwidth of each of the bending transmitters 10 and 20. A
fractional bandwidth can be obtained. An equivalent circuit as seen from the electrical system
when these bent type transmitters 10 and 20 are driven in this state is shown in FIG. In FIG. 2,
Cd 1, L 1, R 1, C 1, and ZL 1 respectively represent the braking capacity, equivalent mass,
equivalent mechanical resistance, equivalent compliance, and load resistance of the bending
transmitter 10. Further, Cd2, L2, R2, C2, and ZL2 represent the braking capacity, equivalent
mass, equivalent mechanical resistance, equivalent compliance, and load resistance of the
bending type transmitter 20, respectively. The transformer of -1: 1 appears because the bending
transmitter 10 is different from the bending transmitter 20 in the polarization direction of the
piezoelectric ceramic active disk. By this transformer, this transmitter 1 functions as a differential
connection type multimode filter in the equivalent circuit.
[0026]
Therefore, the frequency dependence of the oscillation gain of the transmitter 1 is as shown by
the solid line in FIG. Here, the characteristic of the broken line is the characteristic in the case
where the bending transmitter 10 vibrates the bending transmitter 20 in the same phase by
changing the above-mentioned electrical connection. f1 is a resonant frequency of the bending
transmitter 10. f2 is a resonant frequency of the bending transmitter 20. Although the frequency
is f1 and f2 and the transmission gain takes maximum values regardless of the opposite phase
and the same phase, it is between f1 and f2 in the case of the opposite phase (solid line) due to
the effect of the transformer in the above equivalent circuit. But the output does not decrease
significantly. On the other hand, in the case of the same phase (dotted line), there is a region
where it greatly falls between f1 and f2 because there is no effect of this transformer. Therefore,
by setting the phases opposite to each other, sound waves in a wider frequency band can be
oscillated.
[0027]
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9
Here, even when the bending type transmitter 10 and the bending type transmitter 20 are driven
in opposite phase, the output is smaller than these maximum values between f1 and f2. In order
to make the characteristic between f1 and f2 close to a flat characteristic by reducing this
reduction value, the oscillation gain characteristic of bending transmitter 10 alone and the
oscillation gain of bending transmitter 20 alone It is preferred that the points of intersection of
the characteristics lie in the region 3 dB to 8 dB lower than the respective maximum gains
(values at f1 and f2).
[0028]
As described above, each of the bending transmitters 10 and 20 is compact and can emit a sound
wave with high output. Although the respective resonance frequencies (f1, f2) are different, by
combining them into the transmitter 1 having the configuration of FIG. 1, a band of the
oscillation frequency, ie, a frequency having a value of a certain oscillation gain or more The
bandwidth can be broadened. Therefore, this transmitter becomes a small transmitter that
oscillates a sound wave in a wide frequency band at a high output.
[0029]
In this transmitter, the bending transmitters 10 and 20 are driven in reverse phase, but in order
to perform this operation, a configuration different from that of FIG. 1 may be employed. FIG. 4 is
a diagram showing the configuration of the transmitter 2. In this transmitter 2, the polarization
directions in each active plate are different, and the electrical connection is different. That is, the
polarization direction of the active plates 212 and 222 is opposite to that of the transmitter 1
described above, and the polarization direction of the lower active plate 122 in the bending
transmitter 10 is the bending transmitter 20. The polarization direction of the active plate 212
located on the side of the active plate 122 in FIG. The polarization directions of the active plates
in the same bending type transmitter are opposite to each other in the same manner as the
transmitter 1 in FIG. Further, the upper electrode of the active plate 212 and the lower electrode
of the active plate 222 are electrically connected, and are connected to the input 1 together with
the metal disk plate 111 and the metal disk plate 121. The metal disc plate 211 and the metal
disc plate 221 are electrically connected, and are connected to the input 2 together with the
lower electrode of the active plate 112 and the upper electrode of the active plate 122.
[0030]
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10
Also in the transmitter 2, when an AC signal is applied between the input 1 and the input 2, the
bending transmitters 10 and 20 are driven in opposite phase. Therefore, the same effect as the
above-mentioned transmitter 1 is brought about.
[0031]
In both of the above examples, the polarization directions of both active plates in each bending
type wave transmitter are opposite to each other, but the present invention is not limited to this.
Even in the case where the polarization directions are the same, the same effect can be obtained
as long as the same operation as in the above example can be performed. Other than this, the
same effect can be obtained as long as the same operation can be realized.
[0032]
Further, as described in Patent Documents 1 and 2, by making each metal disc plate and each
active plate into a substantially disc shape, it is possible to achieve particularly high output, but it
is not limited thereto. It is also possible to set these shapes appropriately.
[0033]
Second Embodiment In the first embodiment, although an example using two bent transmitters
10 and 20 having different resonance frequencies has been described, the number thereof is
three. You can also.
FIG. 5 is a diagram showing the configuration of the transmitter 51. As shown in FIG.
[0034]
In this transmitter 51, in addition to the first bent transmitter 10 and the second bent transmitter
20, the third bent transmitter 30 is also used, and the order shown in FIG. Are arranged at
approximately equal intervals. The first and second bending transmitters 10 and 20 are the same
as in the case of the transmitter 1. Similarly to the third bending type wave transmitter 30, the
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diaphragms 31, 32 are joined via the convex ring (metal ring) 33 and the concave ring (metal
ring) 34. The diaphragm 31 comprises a metal disk plate 311 and an active plate 312, and the
diaphragm 32 comprises a metal disk plate 321 and an active plate 322. However, the outer
diameter of the diaphragms 31 and 32 is smaller than that of the diaphragms 21 and 22. For this
reason, the frequency (third resonance frequency f3) at which the oscillation gain of the sound
wave oscillated by the third bending transmitter 30 is maximum is higher than the second
resonance frequency f2. Therefore, these three bent transmitters are stacked in the order of the
resonance frequency. Also, these intervals are substantially constant.
[0035]
Also, the polarization directions of the active plates 112, 222, 312 are the same, and are
downward in FIG. Similarly, the polarization directions of the active plates 122, 212, 322 are the
same and are downward in FIG. That is, the polarization directions of the two active plates in the
same bending type transmitter are perpendicular to the surface, and the two sheets are in the
opposite direction to each other. In addition, the polarization direction of one active plate in one
bending transmitter is the polarization direction of the active plate located on the side of the
active plate in another bending transmitter adjacent to the one active plate. It is in the same
direction. That is, the polarization directions of the respective active plates are configured in the
opposite direction in the adjacent bending transmitters.
[0036]
The upper electrodes of the active plates 112, 212, 312 and the lower electrodes of the active
plates 122, 222, 322 are electrically connected to each other and connected to the input 1. The
metal disk plates 111, 121, 211, 221, 311, 321 are electrically connected to each other and
connected to the input 2.
[0037]
FIG. 6 is a schematic view showing the configuration of the transmitter 51. As shown in FIG. As
shown in FIG. 5, the bending type wave transmitters 10, 20 and 30 are stacked at equal intervals
in order from the top. Each bending type transmitter is fixed to a wire 91 as a support by a
transmitter support 90. In addition, although each wiring shown in FIG. 5 is abbreviate | omitted
in FIG. 6, the wiring can be suitably performed using soldering etc. FIG.
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[0038]
The deflection of each diaphragm in this configuration is shown by the broken line in FIG. That is,
it operates in the state where the phase of vibration of each bending type wave transmitter 10,
20, 30 differs by 180 degrees in order from the top. Also, the resonance frequencies f1, f2 and f3
become higher as they go down from the top.
[0039]
An equivalent circuit of the transmitter 51 is shown in FIG. In FIG. 7, Cd 3, L 3, R 3, C 3, and ZL 3
respectively represent the braking capacity, equivalent mass, equivalent mechanical resistance,
equivalent compliance, and load resistance of the bending transmitter 30. The Cd1 and the like,
the Cd2 and the like are the same as in the first embodiment. Also in this case, a transformer of 1: 1 appears in the equivalent circuit, and this transformer 51 functions as a differential
connection type multi-mode filter like the above-described transmitter 1 due to this transformer.
The frequency dependency of the oscillation gain is as shown in FIG. That is, although it has a
peak in resonant frequency f1, f2, f3 of each bending type | mold transmitter 10, 20, 30, it can
oscillate the frequency of a wide bandwidth as a whole. In particular, by combining the bending
transmitters having three different resonance frequencies, high oscillation gain can be obtained
in a wider frequency band than in the first embodiment.
[0040]
In order to effectively widen this bandwidth particularly, the portion where the oscillation gain
characteristics of each bending transmitter itself intersects is 3 to 8 dB lower than the maximum
value, as in the first embodiment. It is preferable to set f1, f2 and f3 as much as possible. For this
purpose, the geometrical dimensions of each bent transmitter are set appropriately, and the
resonance frequency is set.
[0041]
Each of the bent transmitters is similar to that described in Patent Documents 1 and 2 as in the
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first embodiment. That is, it is compact and can oscillate a sound wave with high output.
Therefore, the transmitter 51 is a small transmitter that oscillates a sound wave in a wide
frequency band at a high output.
[0042]
In addition, when each diaphragm performs the same operation as the above, it is clear that the
same effect can be obtained even when the polarization method of each active plate and the
electrical connection method are different. Further, as described in Patent Documents 1 and 2, in
order to achieve high output, it is preferable that each metal disc plate and each active plate have
a substantially disc shape, but the present invention is not limited thereto. The shape can be set
appropriately. Similarly, in order to achieve high output, it is preferable that the distance between
the bent transmitters be substantially constant, but can be set appropriately.
[0043]
Hereinafter, the embodiment of the present invention will be described in detail.
[0044]
Example 1 As Example 1, a transmitter having a structure shown in FIG. 1 in which two bending
transmitters were combined was manufactured.
Here, each active plate in the first bending type wave transmitter is a hard lead zirconate titanate
piezoelectric ceramic, and is a disk having a thickness of 10 mm and a diameter of 150 mm. Each
metal disk plate is made of an aluminum alloy, and the maximum thickness thereof is a disk of 20
mm and a diameter of 200 mm, and the above-mentioned active plate is fitted and embedded in
the surface using an adhesive. The convex ring and the concave ring (metal ring) were both made
of Cr-Mo steel, and the outer diameter was 200 mm and the inner diameter was 190 mm. The
distance between the projections and the recesses was set as close as possible to 2 mm between
the metal disk plates after assembly. The fixing at the time of assembly was performed by a bolt.
The resonance frequency f1 in this first bending transmitter was 3.5 kHz.
[0045]
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14
Each material in the second bending type wave transmitter was the same as that of the first
bending type wave transmitter, and both active plates were circular plates with a thickness of 9
mm and a diameter of 120 mm. The metal disc plate had a thickness of 18 mm and a diameter of
150 mm. Both the convex ring and the concave ring were made of Cr-Mo steel, and the outer
diameter was 150 mm and the inner diameter was 142 mm. The distance between the
projections and the recesses was set as close as possible to 2 mm between the metal disk plates
after assembly. The resonance frequency f2 in this second bending transmitter was 4.6 kHz.
[0046]
The above-mentioned bent type transmitters were combined at an interval of 180 mm to prepare
a transmitter as shown in FIG. In this case, the portion where the oscillation gain characteristics
of each bending type transmitter itself intersect intersects at a point 7 dB lower than the
maximum value. As a result, as shown in FIG. 3, the characteristic of -6 dB relative bandwidth
48% was obtained. On the other hand, the -6 dB fractional bandwidth of each bending transmitter
was at most 15%. Therefore, the broadband characteristic more than twice that is obtained.
[0047]
Example 2 As Example 2, a transmitter having a structure shown in FIG. 4 in which three bent
transmitters were combined was manufactured. Here, the first and second bent transmitters are
the same as those in the first embodiment. The same applies to the respective materials of the
third bent wave transmitter, and the thickness of both active plates was a disk of 8 mm in
diameter and 90 mm in diameter. Each metal disk plate is made of an aluminum alloy, and the
maximum thickness thereof is a disk of 16 mm and a diameter of 120 mm, and the abovementioned active plate is fitted and embedded in the surface using an adhesive. Both the convex
ring and the concave ring were made of Cr-Mo steel, and the outer diameter was 120 mm and
the inner diameter was 114 mm. The distance between the projections and the recesses was set
as close as possible to 2 mm between the metal disk plates after assembly. The resonance
frequency f3 in this third bent transmitter was 6.1 kHz.
[0048]
The above-mentioned bent type transmitters were combined at an interval of 150 mm to make a
09-05-2019
15
transmitter of the configuration shown in FIGS. With this configuration, the characteristics cross
each other at a point 3 to 8 dB lower than the maximum gain of each of the first to third bend
type transmitters. As a result, as shown in FIG. 7, the characteristic of -6 dB relative bandwidth
54% was obtained. On the other hand, the -6 dB fractional bandwidth of each bending transmitter
was at most 15%. Therefore, three times or more broadband characteristics were obtained.
[0049]
It is sectional drawing which shows the structure of an example of the wave transmitter which
becomes the 1st Embodiment of this invention. It is a figure which shows the equivalent circuit of
operation | movement of the wave transmitter which becomes the 1st Embodiment of this
invention. It is a figure which shows the frequency characteristic of the oscillation gain of the
wave transmitter which becomes the 1st Embodiment of this invention. It is sectional drawing
which shows the structure of the other example of the wave transmitter which becomes the 1st
Embodiment of this invention. It is sectional drawing which shows the structure of an example of
the wave transmitter which becomes the 2nd Embodiment of this invention. It is an external view
which shows the structure of an example of the wave transmitter which becomes the 2nd
Embodiment of this invention. It is a figure which shows the equivalent circuit of operation |
movement of the wave transmitter which becomes the 2nd Embodiment of this invention. It is a
figure which shows the frequency characteristic of the oscillation gain of the transmission device
which becomes the 2nd Embodiment of this invention. It is a figure which shows an example of a
structure of the conventional transmitter.
Explanation of sign
[0050]
1, 2, 51, 60 transmitters 10, 20, 30 bent type transmitters 11, 12, 21, 22, 31, 32 diaphragms
111, 121, 211, 221, 311, 321 metal disc plates 112, 122 212, 222, 312, 322 Active plate 13,
23, 33 Convex ring (metal ring) 14, 24, 34 Concave ring (metal ring) 61 Metal disc 62 Active
disc body 63 Metal ring 64 bolt 65 Protective plate 66 Urethane Resin 90 Wave carrier support
91 wire
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