close

Вход

Забыли?

вход по аккаунту

?

JPH0622396

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH0622396
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
piezoelectric element in which a flexible band-shaped polymer piezoelectric material is spirally
wound around a certain central axis and has a cylindrical structure, as well as using the
piezoelectric element. The present invention relates to a hydrophone having excellent flexibility
as a mold sonar.
[0002]
2. Description of the Related Art As an example of a cylindrical piezoelectric element, a flying
type sonar is known (JP-A-55-76962, JP-A-57-60992, JP-A-2-278178, etc.). This is mainly a
hydrophone linear array that has a large number of hydrophone receivers arranged in a straight
line at predetermined intervals to receive engine sound, screw sound, cavitation sound etc.
emitted by a ship And, the phase of the output phase of each receiver is phased to detect the
target vessel, and usually the hydrophone linear array is towed by the vessel via a rope etc. Take
the form of
[0003]
Conventionally, as a sound wave detection element used for such a towed type sonar, a ceramic
piezoelectric element formed into a hollow cylindrical shape, for example, a PZT piezoelectric
element has been used.
04-05-2019
1
[0004]
When this type of hollow cylindrical piezoelectric element is used as a transmitter of sound
waves, the sound waves are radiated radially isotropically regardless of the frequency, that is,
with equal sound pressure, while receiving As for the waver, the reception sensitivity remains
unchanged even if the element is rotated about the longitudinal central axis.
In other words, the radial transmission / reception sensitivity is characterized by no directivity.
[0005]
On the other hand, in the field of ultrasonic processing, an electrostrictive element such as
barium titanate magnet is used in a cylindrical form in order to obtain a large displacement.
Further, U.S. Pat. No. 2,497,108 discloses a relay utilizing a bimorph which is cut out from a
hollow cylinder of a ceramic piezoelectric body and formed in a spiral shape.
[0006]
The above-described conventional cylindrical ceramic piezoelectric element achieves isotropic
sensitivity characteristics regardless of the frequency of the acoustic wave as a transducer of the
acoustic wave, and a large displacement occurs in the electrostrictive element. Although it has
the advantage of being obtained, it includes the following problems. (1) While it is rigid, it is
weak to impact and it is cumbersome to handle. For example, storage is not easy in a long
element due to poor flexibility. (2) It is not easy to manufacture large diameter and long ones. (3)
In the structure in which a large number of receivers are arranged in a straight line like the
hydrophone linear array, the mechanical properties such as bending and strength and the
specific gravity are uneven because there are joints, for example, towing It is easy to be damaged
due to the impact by the motion of the towing body transmitted through the rope, the bending
stress by the water flow, etc., and the property may be deteriorated.
[0007]
There is also the problem that the operability of the hydrophone linear array is considerably poor
when it is unwound or wound together with the rope.
04-05-2019
2
[0008]
It is also conceivable to solve the problems of the hollow cylindrical ceramic piezoelectric
element described above, particularly the problems caused by the rigidity of the ceramic, by
means of a polymer piezoelectric element having superior flexibility.
However, it is not easy to form a polymer piezoelectric body as a seamless cylindrical
piezoelectric element due to the difficulty of forming an electrode thereon, and the polymer
piezoelectric body is also flexible in a cylindrical shape. Does not improve so much. On the other
hand, conventional helical elements cut out from ceramic hollow cylinders have the disadvantage
that they are weak and vulnerable to impact, in addition to the fact that it is not easy to produce
particularly large diameter and long ones. Are also several orders of magnitude inferior to
polymer piezoelectrics.
[0009]
An object of the present invention is to provide a piezoelectric element improved as to the
problems of the conventional hollow cylindrical ceramic piezoelectric element described above,
and a hydrophone having flexibility using the same.
[0010]
SUMMARY OF THE INVENTION According to the research of the present inventors et al., It is
possible to maintain the isotropy of sensitivity by spirally winding a flexible strip-shaped
piezoelectric element into a substantially cylindrical shape. However, it has been found that a
significant improvement over the problems of the hollow cylindrical ceramic piezoelectric
element described above is obtained.
[0011]
That is, according to the present invention, a flexible band-shaped polymer piezoelectric material
provided with electrode layers opposite to each other is spirally wound around a central axis, and
the surface electrode layer is substantially parallel to the central axis extending direction.
Provided is a piezoelectric element having a structure arranged in parallel.
[0012]
04-05-2019
3
Further, according to the present invention, a strip-shaped piezoelectric element obtained by
laminating a pair of strip-shaped polymer piezoelectrics with the central electrode layer
interposed therebetween so as to reverse the polarization direction of each other is wound and
arranged in a spiral. It is an object of the present invention to provide a hydrophone having a
structure capable of extracting an electric output generated between surface electrodes formed
on both surfaces of a piezoelectric element and the central electrode layer.
[0013]
As described above, the piezoelectric element of the present invention is formed into a
substantially cylindrical shape by winding the strip-shaped piezoelectric element, and therefore,
in addition to having excellent isotropic sensitivity characteristics, A significant improvement is
obtained over the lack of flexibility and impact resistance that was a major problem with
cylindrically shaped ceramic piezoelectric elements.
[0014]
Further, in the piezoelectric body constituting the polymer piezoelectric element, deformations
connected to the output include expansion and contraction (two axes) in the surface direction,
thickness change (uniaxial), and volume compression / expansion change.
Among them, mechanical stress applied to a sailing type sonar or the like causes noise due to
expansion and contraction deformation in the plane direction. In the hydrophone of the present
invention, noise due to such expansion and contraction in the plane direction Is effectively offset
by the use of a strip-like piezoelectric element obtained by laminating a pair of polymer
piezoelectric materials through the central electrode layer so that the polarization directions of
the pair are opposite to each other, resulting in substantially no harmful noise.
On the other hand, by forming such a strip-shaped piezoelectric element in a spiral shape and
arranging it into a cylindrical structure, the sound pressure of the sound wave from the object to
be measured is the same as that of the polymer piezoelectric body without losing the flexibility as
a whole. It is effectively detected as deformation in the thickness direction or volumetric
compression / expansion change.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the piezoelectric
04-05-2019
4
element and the hydrophone of the present invention will be described in more detail with
reference to the drawings.
[0016]
FIG. 1 is a front view, partly cut away, of a helical piezoelectric element according to an
embodiment of the present invention configured as a wave receiver (hydrophone) of a tow type
sonar, and FIG. 2 is a cutaway surface II of FIG. It is the thickness direction cross section of the
piezoelectric element taken along -II.
[0017]
With reference to FIGS. 1 and 2, the strip-shaped piezoelectric element 10 constituting the spiral
piezoelectric element has surface electrodes 2a and 2b formed on both sides of a flexible stripshaped piezoelectric body 1.
The spiral piezoelectric element according to the present invention has a shape in which the
band-shaped piezoelectric element 10 is spirally wound around a central axis O.
The lead wires 8a and 8b are connected from the surface electrodes 2a and 2b by soldering 7,
respectively, and an electric output generated between these surface electrodes is provided at the
right end of the helical piezoelectric element when receiving a sound wave. A voltage can be
applied from the terminals A and B to the piezoelectric body 1 so that it can be taken out
between the terminals AB and at the time of transmission of a sound wave or the like.
[0018]
The width (d) and the helical pitch (p) of the strip-shaped piezoelectric element 10 are
appropriately selected according to the characteristics required for the piezoelectric element, but
generally the width is about 2 to 50 mm, preferably 5 to 20 mm, 1 <p / The range of d ≦ 3 is
preferable.
If the width is less than 2 mm, cutting is likely to occur during spiral winding, and if it exceeds
50 mm, it becomes difficult to form in a helical shape.
04-05-2019
5
In addition, when p / d ≦ 1, electrical noise may occur due to the overlapping of the strip-shaped
piezoelectric elements 10 or the contact between the surface electrodes 2 a or between 2 a and 2
b.
On the other hand, if p / d> 3, the area efficiency of the device is reduced. The number of turns
of the spiral constituting the helical piezoelectric element is preferably 1 or more, particularly 3
or more, so as to secure the above-mentioned isotropic sensitivity characteristics.
[0019]
The material of each portion will be described. The flexible piezoelectric body 1 of the present
invention is formed of a polymer piezoelectric body in order to give good flexibility as the whole
spiral piezoelectric element or to form a long spiral piezoelectric element. Do. Such a polymer
piezoelectric body 1 can be easily shaped into a spiral shape as shown in FIG. 1 by winding after
being formed into a strip having surface electrodes 2a and 2b.
[0020]
The polymer piezoelectric body 1 is optionally made of a generally known polymer piezoelectric
material, but has a VDF piezoelectric body made of a vinylidene fluoride (VDF) homopolymer or
copolymer, or has relatively high heat resistance. A vinylidene cyanide-vinyl acetate copolymer
etc. are used suitably. These polymer piezoelectric materials are subjected to uniaxial stretching
or heat treatment at a temperature below the softening temperature, and polarization treatment
by application of an electric field at the temperature below the softening temperature, if
necessary, after film formation by melt extrusion or the like. The polymer piezoelectric material 1
can generally take the form of a film or sheet, and the thickness thereof is preferably selected in
the range of about 20 to 2000 μm, particularly 100 to 1000 μm. When the thickness of the
polymer piezoelectric material is 20 μm or less, sufficient wave receiving sensitivity can not be
obtained. On the other hand, when the thickness is 2000 μm or more, the flexibility of the film is
impaired and further high voltage is required for polarization. Is extremely difficult.
[0021]
04-05-2019
6
The surface electrodes 2a and 2b are formed by vapor deposition, spraying, plating (especially
electroless plating) of a conductive material such as silver, copper, aluminum, zinc or the like on
the surface of the piezoelectric body 1 without impairing the flexibility of the entire helical
piezoelectric element. It can be formed in a thickness range of 0.02 μm to 200 μm by adhesive
bonding of a metal foil or the like. Among them, in order to provide good solderability and
excellent transmission / reception sensitivity while maintaining good flexibility in combination
with a polymer piezoelectric material, the counter electrodes 2a and 2b have a thickness of 10 to
100 μm, in particular It is preferable to form as a 20-50 micrometers sprayed electrode layer.
[0022]
An insulating coating is preferably applied to the surfaces of the electrodes 2a and 2b of the
spiral piezoelectric element of the present invention. This insulating coating can be formed as
insulating coating layers 5a and 5b selectively covering the electrodes 2a and 2b as shown in
FIG. 3 corresponding to FIG. 2, but more preferably as shown in FIG. Preferably, the entire helical
piezoelectric element is embedded in the insulator 11 and formed into a solid (or hollow)
cylindrical shape to improve the robustness and the handleability of the element. The insulating
coverings 5a, 5b or 11 can be selected from plastics, ceramics, elastomers and the like according
to the use situation. Among them, as for the insulator 11, it is preferable to use an elastomer
such as urethane rubber, silicone rubber and butyl rubber in order to maintain the flexibility of
the entire helical piezoelectric element in addition to the fastness.
[0023]
The outer shape of the buried cover 11 is not limited to a cylindrical (cylindrical) shape, and may
be another shape as long as directivity does not occur in sensitivity. For example, the buried
cover may be shaped like an elliptic cylinder (cylindrical) It is also possible to give directionality
to bending stress. In addition to electric wires, electric parts such as preamps, strength members,
filling materials, etc. may be embedded in the center of the embedded cover if necessary, or
hollows may be formed and disposed. it can.
[0024]
The surface electrodes 2a and 2b do not have to be provided over the entire surface of the
04-05-2019
7
elongated strip-shaped piezoelectric body 1. For example, as shown in FIG. 4 corresponding to
FIG. 1, the surface electrodes 2a (and 2b-not shown) are provided separately along the
longitudinal direction of the strip-shaped piezoelectric body 1, and in the middle blank portion It
is also possible to have a structure in which 1 is exposed. As a result, functionally, two helical
piezoelectric elements 10a and 10b are formed in each area where the surface electrode 2a (2b)
exists. Of these elements 10a and 10b, the front and back electrodes 2a and 2b of 10a are
connected to the terminals A1 and B1 through the lead wires 81a and 81b respectively
connected by the solder 7, and the electric output generated between both electrodes is It takes
out between terminals A1 and B1. On the other hand, the front and back electrodes 2a and 2b of
the element 10b are connected to the terminals A2 and B2 through the soldered lead wires 82a
and 82b, respectively, and the protrusion produced on the element 10b is taken out between the
terminals A2 and B2. The lead wires 81 and 82 are preferably passed through a portion (inside
of the spiral) close to the central axis of the helical piezoelectric element as shown. A hydrophone
having such a configuration is not limited to two, and a larger number of unit elements are
functionally independent and structurally linearly linked hydrophone linear arrays, and acoustic
waves in a wide frequency band are obtained. Conformity to is secured. In addition, since these
connecting elements are integrally formed, they have features such as uniform mechanical
properties such as bending and strength, and uniform specific gravity, and even with a plurality
of functional elements, it is possible to use one element in terms of structural handling. There is
an advantage that can be handled equally. The connection elements can transmit and receive at
different frequencies because each piezoelectric element is functionally independent, and one can
be used as a transmitter and the other as a receiver.
[0025]
Next, another preferred embodiment of the present invention will be described.
[0026]
FIG. 5 is a partially cutaway front view of an embodiment of the hydrophone of the present
invention, and FIG. 6 is a schematic cross-sectional view in the thickness direction of the
piezoelectric element taken along the cut surface VI-VI of FIG. .
In these drawings, parts similar to those shown in FIGS. 1 to 4 are indicated by the same
reference numerals.
[0027]
04-05-2019
8
With reference to FIGS. 5 and 6, the strip-shaped piezoelectric element 50 constituting the
hydrophone arranges the pair of strip-shaped polymer piezoelectric members 1a and 1b so that
their polarization directions p are opposite to each other, and It is stuck to the central electrode
layer 3 through the layers 4a and 4b. Moreover, these polymer piezoelectric materials 1 a and 1
b have surface electrodes 2 a and 2 b on the surface opposite to the central electrode layer 3,
respectively.
[0028]
In the hydrophone of the present invention, such a strip-shaped piezoelectric element 50 is
spirally disposed around a central axis O as shown in FIG. 5, and the output from the surface
electrodes 2a and 2b on both sides thereof (output The terminals A and C) are short-circuited,
and the voltage output between the central electrode layer 3 and the output (output terminal B)
can be taken out by the detection means 5.
[0029]
In order to prevent the noise due to the stretching stress in the plane direction as described
above, and to ensure the good detection characteristics of the sound wave and the excellent
flexibility as a whole, the strip-shaped piezoelectric element has the central electrode layer 3
located at the center. The center electrode layer 3 is a metal foil electrode that controls the
rigidity of the entire strip-like piezoelectric element, and is a flexible deposition electrode or In
particular, it is preferable to form the surface electrodes 2a and 2b by metal spray electrodes.
[0030]
In the second embodiment, as described above, the central electrode layer 3 is larger in rigidity
than the polymer piezoelectrics 1a and 1b and the surface electrodes 2a and 2b, for example,
copper, aluminum, tin, zinc, gold, It is preferable to form the metal foil of silver, platinum or the
like with a thickness of about 6 to 200 μm, particularly 20 to 120 μm.
However, as described above, a layer configuration in which the central electrode layer 3
becomes a neutral point and the upper and lower polymer piezoelectric bodies are deformed
symmetrically with respect to bending stress is preferably adopted. Other than the abovementioned metal foils may also be used.
04-05-2019
9
[0031]
The adhesive layers 4a and 4b can be formed of a conductive adhesive in which conductive
particles are dispersed, but an epoxy resin, a urethane resin, a polyester resin, a butadiene resin,
an acrylic resin, which is more excellent in adhesive strength. The output characteristics are well
maintained even when the layer is made about 5 to 40 μm by an adhesive such as a resin based
resin.
[0032]
In the present embodiment, the surface electrodes 2a and 2b of the piezoelectric element 50 are
made of silver, copper, aluminum, zinc or the like and have a thickness of 10 to 100 μm,
preferably 20 to 50 μm, or about 0.02 to 0.1 μm. It is preferred not to be a vapor deposition
electrode and to maintain good flexibility.
With this configuration, even when a relatively high-rigidity metal foil electrode is used as the
center electrode layer 3, good flexibility is maintained as a whole of the strip-like piezoelectric
element 50, and spiral winding as shown in FIG. Structure is possible.
Then, in combination with the spirally wound structure shown in FIG. 5, a cylindrically-shaped
piezoelectric element 50 having good flexibility as a whole can be obtained. This element has no
significant difference in flexibility in the radial direction, and is excellent in operability when
deploying and storing the sonar.
[0033]
Further, even in the case of using the polymer piezoelectric material laminated as in this
embodiment, the surface electrodes 2a and 2b do not have to be provided over the entire surface
of the long strip-shaped piezoelectric element 50, as described in the example of FIG. It is also
possible to form the electrode elements with a predetermined interval in the longitudinal
direction of the piezoelectric element 50 discontinuously. The hydrophone formed by winding
the strip-like piezoelectric element 50 in a spiral shape becomes a hydrophone linear array in
which many units of the elements shown in FIG. 5 are linearly connected, compared with the
conventional hydrophone array. Since they are integrally molded, they have features such as
uniform mechanical properties such as bending, elongation and strength and specific gravity.
04-05-2019
10
And for this reason, for example, the durability against a tensile impact is excellent.
[0034]
In the hydrophone of the present invention, a strip-like piezoelectric element 50 as described
above in the same manner as in the embodiments of FIGS. Alternatively, it may be wound in a
helical shape on a cylinder and have an outer surface coated with an insulating coating. However,
in order to prevent the residual stress applied to the strip-shaped piezoelectric element and
improve the measurement sensitivity, the strip-shaped piezoelectric element is temporarily
wound around a rigid or elastic rod-shaped body to form a spiral shape, Preferably, the rod-like
body is removed, and the spirally shaped strip-shaped piezoelectric element 50 is embedded in
an elastomer covering 11 made of urethane rubber, silicon rubber, butyl rubber or the like. Thus,
a cylindrical rod-like hydrophone as shown in FIG. 5 having good overall flexibility and good
wave reception sensitivity can be obtained.
[0035]
On the other hand, the outer shape of the cover 11 is preferably cylindrical, but may be another
shape, for example, it is possible to make the cover 11 elliptical-pillar and give directionality to
bending stress. . Also, in the center of the cover 11, electrical wires such as signal lines and
feeders, electric parts such as depth gauges and azimuth meters, strength members, fillers and
the like are embedded or hollows are formed and disposed. You can also
[0036]
The strip-shaped piezoelectric element 50 generally has a width of about 2 to 50 mm, preferably
5 to 20 mm, and has a gap of 1 to 20 mm (preferably a gap / width of 1), a winding number of 1
or more, and a winding diameter of 8 to 50 mm. By winding, a hydrophone having a desired
length is obtained.
[0037]
By sequentially connecting the individual hydrophone elements obtained in this way, at intervals
changed to match the sound waves of the desired wavelength range, a hydrophone array suitable
for use as a towing type sonar can be obtained. Be
04-05-2019
11
[0038]
In the above, although the case where the piezoelectric body 1 is a single layer or two layers has
been exemplified, the piezoelectric body 1 may have a structure in which a larger number of
piezoelectric bodies are stacked, and in this case, between the piezoelectric layers An
intermediate electrode layer may be interposed.
[0039]
Also, in the above, the helical piezoelectric element of the present invention has been mainly
described with respect to a receiver of a tow type sonar which is a preferred embodiment
thereof.
However, the spiral piezoelectric element using the band-shaped piezoelectric element 10 of the
present invention is not limited to this, but is not limited to this, or as a probe of an ultrasonic
flaw detector or ultrasonic thickness gauge for a cylindrical object to be inspected. It can also be
used as an oscillating (signal) element such as a probe of a sonic cleaner.
At this time, lead wires (signal wires) 8a, 8b, 8c, 81a, 81b, 82a, 82b, etc. shown in FIG. 1, FIG. 4
or FIG. 5 are used as feed lines.
[0040]
When the helical piezoelectric element of the present invention is used as a probe for inspecting
a cylindrical object to be inspected, in order to maintain good acoustic contact between the
object to be inspected and the piezoelectric element Preferably, the periphery of the element is
sealed with a flexible tube or balloon, and a means for sucking and discharging a liquid is
provided therein.
[0041]
According to the embodiment shown in FIGS. 1 and 2, a hydrophone was produced.
[0042]
First, a copolymer of vinylidene fluoride (VDF) / trifluoroethylene (TrFE) at a molar ratio of
75/25 (number average molecular weight = 1.75 × 10 5, manufactured by Toha Chemical
Industry Co., Ltd.) is used at a die temperature of 265 ° C. Sheet extrusion, heat treatment at
04-05-2019
12
125 ° C. for 13 hours, then polarization treatment under an electric field of 75 MV / m, holding
time at 123 ° C. for 5 minutes, elevation time for a total of 1 hour, 500 μm thick polymer A
piezoelectric film is obtained, and both surfaces thereof are roughened by sandblasting with an
alumina-based abrasive having a particle size of # 60, and then an electric wire thermal sprayer
(Kato Metallikon Co., Ltd., DK metallic sprayer E type) is used for air The thermal spraying was
performed under the conditions of a pressure of 5 kg / cm 2 and a voltage of 15 V to form zinc
sprayed electrodes 2 a and 2 b each having a thickness of about 40 μm.
[0043]
Next, from the piezoelectric element having the laminated structure shown in FIG. 2 obtained
above, a slit in the machine direction (MD) with a width of about 10 mm was obtained to obtain a
strip-shaped piezoelectric element 10.
[0044]
The band-shaped piezoelectric element 10 is wound around a brass rod having a diameter of 7
mm, wound with a tape and fixed, heat-treated at 70 ° C. for 1 hour, gradually cooled to room
temperature, and spirally attached to the band-shaped piezoelectric element I removed the brass
rod.
As the brass bar used in this setting process, one having a smaller diameter than that of the brass
bar used in the next shaping process is preferably used.
[0045]
Subsequently, a forming tool is prepared in which a plate-like screw blade is attached to a spiral
with a pitch of 15 mm to a brass rod with a diameter of 10 mm, and the above-mentioned helical
piezoelectric element attached to the tool is fixed to the tool with a fixed interval (about 5 mm). It
wound immediately so that it might become, and was left to stand at room temperature for 10
minutes or more, and it fixed.
Thus, a shaped helical piezoelectric element having a length of 120 mm is obtained, and then the
shaping tool is removed leaving about half of the element, and is aligned with a jig in a Teflon
mold frame having a diameter of 20 mm. After inserting it, pour in a polyurethane resin ("Type
04-05-2019
13
3318/2023 / DOA = 50/40/10" (weight ratio) made by Nippon Zeon Co., Ltd.) to about half of
the mold frame and After heat curing for a while, the jig, the mold frame and the shaping tool
were removed.
Then, lead wires 8a and 8b connected to the terminals A and B are joined to one end of the
helical piezoelectric element by the solder 7, returned to the mold frame again, and the
polyurethane resin is cast on the remaining uncovered portion. By curing, as shown in FIG. 1, a
hydrophone (about 135 mm in length) was obtained in which the strip-shaped piezoelectric
element 10 spirally wound and shaped was embedded in the insulation coating 11.
[0046]
In order to test the performance as a receiver for the hydrophone thus obtained, the hydrostatic
pressure of the slit-like strip piezoelectric element described above and the hydrophone formed
into a spiral shape and embedded in a urethane elastomer The piezoelectric strain constant dh
was measured and the two were compared.
[0047]
The measurement results are shown in Table 1 below.
From the table, it can be seen that in the piezoelectric element of the present invention, the
receiving sensitivity before shaping is maintained even after shaping.
Here, the hydrostatic pressure piezoelectric strain constant dh was determined by the following
method.
[0048]
The sample is immersed in silicon oil in a pressure container, and the charge amount Q (coulomb
(C)) of the sample is measured while applying a pressure P (newton (N) / m 2) from a nitrogen
gas source to the container.
04-05-2019
14
Then, the amount dQ of increase in charge with respect to the pressure rise dP near a gauge
pressure of 2 kg / cm 2 was obtained, and it was calculated by the following equation.
[0049]
dh = (dQ / dP) / A unit is C / N. Here, A is the electrode area (m2).
[0051]
This hydrophone can be easily bent by hand, and re-measurement is carried out after repeating
bending several times with a radius of curvature of about 8 cm, and there is no change in the dh
constant. Thus, it can be seen that the piezoelectric element of the present invention is excellent
in flexibility.
[0052]
Example 2 A hydrophone was prepared according to the embodiment shown in FIGS.
[0053]
First, in the same manner as in Example 1, a 500 μm-thick polymer piezoelectric film was
obtained, and one surface thereof was roughened.
[0054]
Separately, on both sides of a 35 μm thick copper foil surface roughened on both sides, a
polyester-based adhesive (99: 1 (Weight of “Bylon 30 SS” manufactured by Toyobo Co., Ltd.
and “Coronato L” Ratio) mixture is applied at a thickness of 10 μm, and then the pair of
piezoelectric films cut out from the polymer piezoelectric film obtained above are pasted so that
their polarization characteristics are opposite to each other, at 50 ° C. The adhesive was cured
under the conditions of 20 kg / cm 2 to obtain a laminate of 1a / 4a / 3 / 4b / 1b excluding the
surface electrodes 2a and 2b of FIG.
[0055]
Then, after roughening both surfaces of the laminate obtained above with sandblasting using an
alumina abrasive having a particle size of # 60, an electric wire thermal spraying machine (Kato
04-05-2019
15
Metallikon Co., Ltd., DK metallic spraying machine E type) The thermal spraying was performed
under the conditions of an air pressure of 5 kg / cm 2 and a voltage of 15 V to form zinc sprayed
electrodes 2 a and 2 b having a thickness of about 40 μm.
[0056]
Next, from the piezoelectric element having the laminated structure shown in FIG. 6 obtained
above, a strip-shaped piezoelectric element 50 was obtained by slitting in a machine direction
(MD) with a width of about 10 mm.
[0057]
The strip-like piezoelectric element 50 is fixed and molded in the same manner as in Example 1
to obtain a shaped helical piezoelectric element 50 having a length of 120 mm, and thereafter
embedded in polyurethane as in Example 1. The hydrophone (about 135 mm in length) of the
form by which the strip-shaped piezoelectric element 50 spirally wound and shaped as shown in
FIG.
[0058]
Between the terminals A and B and between the terminals AC and B (between AC as shown in
FIG. 6) when the electrode extraction portion (right end in FIG. 5) of the hydrophone obtained in
this way is shaken in a pendulum shape by hand. The output at the short circuit was measured
with a digital oscilloscope (type DL-2240, Yokogawa Electric Co., Ltd.).
Oscillograph charts of output waveforms are shown in FIG. 7 (between terminals A and B) and
FIG. 8 (between terminals AC and B), respectively.
In the figure, the vertical axis is the output (20 mV / div.), And the horizontal axis is the time (0.5
sec / div.
)である。
[0059]
As apparent from the comparison between FIG. 7 and FIG. 8, in the output between terminals AC
04-05-2019
16
and B according to the structure of the present invention (FIG. 8), it can be seen that deformation
noise due to expansion and contraction of the hydrophone is effectively offset. .
[0060]
In addition, the hydrostatic pressure piezoelectric strain constant dh of the slit-like strip-like
piezoelectric element and the hydrophone formed into a spiral shape and embedded in a
urethane elastomer was measured in the same manner as in Example 1 and both were compared
.
The measurement results are shown in Table 2 below.
From the table, as in Example 1, the reception sensitivity before shaping is maintained even after
shaping.
[0062]
Subsequently, when the hydrophone was fixed to a radius of curvature of 10 cm by a jig and the
same measurement was performed, the dh constant did not change.
[0063]
As described above, according to the present invention, the flexible belt-like piezoelectric
material has a spirally wound structure, whereby the flexibility significantly improved as
compared with a cylindrical piezoelectric element, and A piezoelectric element having impact
resistance and suitable as a sound wave transmitting / receiving element is provided.
[0064]
In addition, by adopting a strip-shaped piezoelectric element having a bonded structure on the
opposite side of a pair of strip-shaped polymer piezoelectric materials and a spiral winding
structure of the strip-shaped piezoelectric element, mechanical stress can be maintained while
maintaining flexibility as a whole. It is possible to prevent generation of noise due to application
and to provide a hydrophone with good reception sensitivity.
04-05-2019
17
Документ
Категория
Без категории
Просмотров
0
Размер файла
32 Кб
Теги
jph0622396
1/--страниц
Пожаловаться на содержимое документа