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DESCRIPTION JP2017067763
Abstract: To provide a sensor unit capable of detecting a sound as well as vibration while
protecting a piezoelectric element. A sensor unit according to the present invention is a sensor
unit including a sheet-like piezoelectric element having a porous layer, which covers at least one
surface of the piezoelectric element, and receives sound incident from one surface. It further
comprises a sound transmission sheet that transmits to the other surface. The difference in
sound pressure level between the sound incident on the sound propagation sheet and the
transmission sound is preferably 10 dB or less. The surface density of the sound propagation
sheet is preferably 0.03 g / m or more and 100 g / m or less. The sound transmission sheet may
have flexibility. The sound transmitting sheet may have an air gap. The piezoelectric element may
further include a sound blocking sheet which covers the other surface of the piezoelectric
element and substantially blocks transmission of sound incident from the other surface to one
surface. [Selected figure] Figure 1
Sensor unit and instrument
[0001]
The present invention relates to a sensor unit and an instrument.
[0002]
BACKGROUND Conventionally, a vibration detection sensor is known that is attached to a
vibrating portion of a musical instrument and can detect the vibration of the vibrating portion
and output it as an electrical signal.
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Moreover, the sensor using the piezoelectric element which arrange ¦ positioned the electrode
layer on both surfaces of the porous resin film as such a vibration detection sensor is known (for
example, refer Unexamined-Japanese-Patent No. 2010-89495). A sensor using a piezoelectric
element having such a porous layer is suitable for sound detection because it is soft in the
thickness direction, and it is light and thin, so it does not suppress the vibration of the musical
instrument. Therefore, a sensor using a piezoelectric element having such a porous layer is
suitably used as a pickup for an instrument that detects both vibration and sound. Note that
"sound" means a compressional wave of air transmitted through air, and "vibration" means
vibration transmitted through a solid and transmitted to a sensor.
[0003]
Here, when the above-described sensor is used in an instrument or the like, it is necessary to
prevent the piezoelectric element from being damaged in order to maintain the detection
accuracy of the sensor. However, if the sensor is covered with a protective film in order to
prevent the piezoelectric element from being damaged, there is a possibility that sound can not
be detected.
[0004]
JP, 2010-89495, A
[0005]
The present invention is made in view of the above-mentioned circumstances, and it aims at
providing a sensor unit which can detect a sound with vibration while protecting a piezoelectric
element, and a musical instrument provided with this sensor unit.
[0006]
The present invention made to solve the above problems is a sensor unit including a sheet-like
piezoelectric element having a porous layer, which covers at least one surface of the piezoelectric
element, and is incident from one surface. It is a sensor unit characterized by further having a
sound propagation sheet which transmits sound to the other side.
[0007]
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Since the sound propagation sheet covers one side of the piezoelectric element, the sensor unit
can protect one side of the piezoelectric element that detects sound from being scratched, and as
a result, the detection accuracy of the sound can be maintained.
Further, in the sensor unit, since the sound propagation sheet covering one surface of the
piezoelectric element transmits sound incident from one surface to the other surface, light is
incident from one surface of the sensor unit. Sound can not be easily reduced by the sound
propagation sheet, and sound can be detected along with vibration.
[0008]
The difference in sound pressure level between the sound incident on the sound propagation
sheet and the transmission sound is preferably 10 dB or less.
As described above, by using a sound propagation sheet in which the difference in sound
pressure level between the sound incident on the sound propagation sheet and the transmitted
sound is less than the upper limit, the reduction of the sound incident from one surface side can
be reliably suppressed. It is easier to maintain sound detection accuracy.
As a result, it can be used as a microphone.
[0009]
The surface density of the sound propagation sheet is preferably 0.03 g / m <2> or more and
100 g / m <2> or less. As described above, by using a sound propagation sheet having a surface
density within the above range, it is possible to reliably suppress the reduction of sound incident
from one surface side while reliably protecting one surface of the piezoelectric element. It is
easier to maintain detection accuracy.
[0010]
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The sound transmission sheet may have flexibility. As described above, since the sound
propagation sheet has flexibility, the piezoelectric element can be covered without being
compressed, so that the durability of the piezoelectric element can be improved. In addition,
since the sound propagation sheet has flexibility, it is easy to propagate the vibration due to the
incident sound on one surface side to the piezoelectric element, and it is easier to maintain the
sound detection accuracy. Note that flexibility means, for example, when a test piece of 5
mm in width and 10 mm in length is supported by one short side to be horizontal at the support
position, the vertical direction of the two opposing short sides is supported. It means that the
difference in position is 5 mm or more.
[0011]
The sound transmitting sheet may have an air gap. As described above, when the sound
propagation sheet has the air gap, the incident sound on one surface side of the sound
propagation sheet is propagated through the air gap, so that the sound is more easily propagated
to the piezoelectric element, and the sound is more Easy to detect.
[0012]
The sensor unit may further include a sound blocking sheet that covers the other surface of the
piezoelectric element and substantially blocks transmission of sound incident from the other
surface to one surface. As described above, by covering the other surface of the piezoelectric
element with a sound blocking sheet that substantially blocks the transmission of the sound
incident from the other surface to one surface, the incident sound from the other surface can be
obtained. As a result, it is possible to detect an incident sound from one side more accurately.
Note that "to substantially block transmission of sound" is not limited to blocking 100% of
transmission of sound, but refers to reduction to the extent that transmitted sound is not
detected by the piezoelectric element.
[0013]
Moreover, this invention made in order to solve the said subject is an instrument provided with
the said sensor unit.
[0014]
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The musical instrument can detect the sound as well as the vibration by the sensor unit, so that
the original timbre of the musical instrument can be converted into an electrical signal and
output.
[0015]
As described above, the sensor unit and the musical instrument of the present invention can
detect sound as well as vibration while protecting the piezoelectric element.
[0016]
It is a typical sectional view showing a sensor unit concerning a first embodiment of the present
invention.
It is a schematic cross section which shows the piezoelectric element of FIG.
It is a typical sectional view showing a sensor unit concerning a second embodiment of the
present invention.
It is a schematic cross section which shows the sensor unit of a structure different from FIG. It is
a typical sectional view showing a sensor unit concerning a third embodiment of the present
invention. It is a typical sectional view showing a sensor unit concerning a fourth embodiment of
the present invention. It is a schematic cross section for demonstrating the attachment structure
of the sensor unit of FIG. It is a schematic cross section for demonstrating the attachment
structure of a sensor unit different from FIG. It is a schematic cross section for demonstrating the
attachment structure of a sensor unit different from FIG.7 and FIG.8. It is a schematic cross
section for demonstrating the attachment structure of a sensor unit different from FIGS. 7-9. It is
a schematic cross section for demonstrating the attachment structure of a sensor unit different
from FIGS. 7-10. It is a schematic cross section for demonstrating the attachment structure of a
sensor unit different from FIGS. 7-11. It is a schematic cross section for demonstrating the
attachment structure of a sensor unit different from FIGS. 7-12. It is a schematic cross section for
demonstrating the attachment structure of a sensor unit different from FIGS. 7-13. It is a
schematic cross section for demonstrating the attachment structure of a sensor unit different
from FIGS. 7-14. It is a schematic cross section for demonstrating the attachment structure of a
sensor unit different from FIGS. 7-15. It is a schematic cross section for demonstrating the
attachment structure of a sensor unit different from FIGS. 7-16. FIG. 18 is a schematic cross-
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sectional view for illustrating a mounting configuration of a sensor unit different from those in
FIGS. It is a schematic cross section for demonstrating the attachment structure of a sensor unit
different from FIGS. 7-18. It is a graph which shows notionally the relationship between the
frequency of sound, and the detection sensitivity by a sensor unit. It is a typical perspective view
showing a box type piezoelectric element. It is a schematic plan view which shows the structure
before the assembly of the piezoelectric element of FIG. 21A. It is a typical side view showing an
example of assembling composition of a piezoelectric element different from Drawing 21A. FIG.
23 is a schematic side view showing an example of an assembled structure of a piezoelectric
element different from those in FIGS. 21A and 22. It is a schematic perspective view which shows
a stringed musical instrument provided with the sensor unit of FIG. It is a schematic plan view
which shows the inner surface side of the soundboard of the stringed instrument of FIG. It is a
typical sectional view showing a sensor unit concerning other embodiments.
[0017]
Hereinafter, embodiments of the present invention will be described in detail with reference to
the drawings as appropriate.
[0018]
First Embodiment Sensor Unit The sensor unit 1 shown in FIG. 1 is a sensor unit provided with a
sheet-like piezoelectric element 2 having a porous layer.
The sensor unit 1 covers one surface of the piezoelectric element 2 and covers the first sound
propagation sheet 3 a transmitting sound incident from one surface to the other surface and the
other surface of the piezoelectric element 2. , And a second sound propagation sheet 3b
transmitting the sound incident from the other surface to the one surface.
[0019]
<Piezoelectric Element> The piezoelectric element 2 is formed in a plate shape and in a
substantially rectangular shape in plan view. As shown in FIG. 2, the piezoelectric element 2 has
a porous layer 4 and a pair of electrode layers (a first electrode layer 5a and a second electrode
layer 5b). The piezoelectric element 2 generates a voltage corresponding to the amount of
compression of the porous layer 4.
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[0020]
(Porous Layer) The main component for forming the porous layer 4 is preferably one that can be
charged, for example, polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET),
polyvinyl chloride, polyolefin resin, fluorine resin Etc. In addition, a "main component" means the
component with most content, for example, the component whose content is 50 mass% or more.
[0021]
The porous layer 4 is generally formed by subjecting a plate-like body mainly composed of these
synthetic resins to polarization treatment. As such a polarization treatment method, for example,
a method of injecting a charge by adding a direct current or pulse-like high voltage, a method of
injecting a charge by irradiating ionizing radiation such as γ ray or electron beam, a charge by
corona discharge treatment And the like.
[0022]
As a lower limit of the average thickness of the porous layer 4, 30 micrometers is preferable and
50 micrometers is more preferable. On the other hand, as an upper limit of average thickness of
porous layer 4, 150 micrometers is preferred and 100 micrometers is more preferred. If the
average thickness of the porous layer 4 is less than the above lower limit, there is a possibility
that the processability may be reduced due to the reduction in strength. On the contrary, when
the thickness of the porous layer 4 exceeds the above-mentioned upper limit, there is a
possibility that polarization treatment efficiency may fall.
[0023]
The lower limit of the elastic modulus in the direction perpendicular to the thickness direction of
the porous layer 4 is preferably 1 GPa, more preferably 1.5 GPa. On the other hand, the upper
limit of the elastic modulus in the direction perpendicular to the thickness direction is preferably
3 GPa, more preferably 2.5 GPa. If the modulus of elasticity in the direction perpendicular to the
thickness direction is less than the lower limit, distortion in the direction perpendicular to the
thickness direction will be large, and the detection accuracy of vibration may be reduced.
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Conversely, when the elastic modulus in the direction perpendicular to the thickness direction
exceeds the upper limit, it is difficult for the porous layer 4 to follow the expansion and
contraction of the first electrode layer 5a and the second electrode layer 5b, and the first
electrode layer 5a and the second electrode layer 5b There is a possibility that the second
electrode layer 5 b may be easily peeled off from the porous layer 4. In addition, "elastic
modulus" is a value measured based on JIS-K7161 (2014).
[0024]
The lower limit of the elastic modulus in the thickness direction of the porous layer 4 is
preferably 0.1 GPa, and more preferably 0.3 GPa. On the other hand, as an upper limit of the
elastic modulus in the thickness direction, 10 GPa is preferable, and 2 GPa is more preferable. If
the elastic modulus in the thickness direction is less than the lower limit, the detection error of
the vibration may be increased. Conversely, when the elastic modulus in the thickness direction
exceeds the upper limit, it may be difficult to detect minute vibrations.
[0025]
The lower limit of the density of the porous layer 4 is preferably 0.2 g / cm <3>, and more
preferably 0.4 g / cm <3>. On the other hand, the upper limit of the density of the porous layer 4
is preferably 0.8 g / cm <3>, and more preferably 0.6 g / cm <3>. If the density of the porous
layer 4 is less than the lower limit, the strength of the porous layer 4 may be reduced.
Conversely, when the density of the porous layer 4 exceeds the upper limit, the porous layer 4
may not be sufficiently deformed, and the detection accuracy of vibration may be reduced.
[0026]
The porous layer 4 has a plurality of pores 6. The shape and size of the holes 6 are not
particularly limited, but the lower limit of the average height of the holes 6 is, for example,
preferably 1 μm, and more preferably 3 μm. On the other hand, the upper limit of the average
height of the holes 6 is, for example, preferably 30 μm, and more preferably 15 μm. If the
average height of the holes 6 is less than the lower limit, the porous layer 4 may not be
sufficiently deformed. Conversely, when the average height of the holes 6 exceeds the upper
limit, the strength of the porous layer 4 may be reduced. The average height of the holes 6 is
calculated by measuring the maximum length of any 20 holes in the thickness direction of the
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porous layer 4 in the thickness direction and calculating the arithmetic mean value thereof Say
the value being
[0027]
The lower limit of the porosity of the porous layer 4 is preferably 20%, and more preferably 30%.
On the other hand, the upper limit of the porosity of the porous layer 4 is preferably 80%, and
more preferably 70%. If the porosity of the porous layer 4 is less than the lower limit, the porous
layer 4 may not be sufficiently deformed, and sufficient detection accuracy may not be obtained.
Conversely, when the porosity of the porous layer 4 exceeds the upper limit, the strength of the
porous layer 4 may be reduced. The porosity means the proportion of pores per unit volume,
and the porosity ε (%) is, for example, the mass W (g) and the apparent volume V (cm) of the
porous layer 4 From <3> and the true density ((g / cm <3>), it can be determined by the
following equation (1). Here, since the true density 加熱 is heated for 5 minutes with a heat press
at 200 ° C. under a load of 1 kg / cm 2, and then cooled with a cooling press, the following is
obtained from the volume V 0 (cm 3): It can be determined by equation (2). Furthermore, the
porosity ε can be determined by the following equation (3) by substituting the following
equation (2) into the following equation (1). ε = (1−W / VV) × 100 (1) == W / V 0 (2) ε =
1−V 0 / V (3)
[0028]
(Electrode Layer) The first electrode layer 5 a and the second electrode layer 5 b are laminated
on both sides of the porous layer 4. The first electrode layer 5a and the second electrode layer 5b
are connected to lead wires (not shown), and the lead wires are connected to output terminals
(not shown).
[0029]
The material for forming the first electrode layer 5a and the second electrode layer 5b is not
particularly limited as long as it has conductivity, and examples thereof include various metals
such as aluminum and silver, alloys of these metals, carbon, and the like. .
[0030]
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The average thickness of the first electrode layer 5a and the second electrode layer 5b is not
particularly limited, but can be, for example, 0.1 μm to 30 μm.
If the average thickness of the first electrode layer 5a and the second electrode layer 5b is less
than the lower limit, breakage such as breakage may occur in the first electrode layer 5a or the
second electrode layer 5b. Conversely, when the average thickness of the first electrode layer 5a
and the second electrode layer 5b exceeds the upper limit, there is a possibility that the vibration
can not be detected accurately.
[0031]
The method of laminating the first electrode layer 5a and the second electrode layer 5b on the
porous layer 4 is not particularly limited, and examples thereof include vapor deposition of
aluminum, printing with a carbon conductive ink, and coating and drying of silver paste.
[0032]
The porous layer 4 has pores inside and is soft and easily scratched.
In addition, since the electrode layer 5 formed on the surface of the porous layer 4 is also soft, it
is easily scratched. Therefore, it is necessary to cover the piezoelectric element 2 formed of these
with a sheet in order to prevent a scratch. Therefore, the piezoelectric element 2 is covered with
a sound propagation sheet so that the sound can be detected by the piezoelectric element 2.
[0033]
<Sound Transmission Sheet> The first sound transmission sheet 3a and the second sound
transmission sheet 3b are formed of the same material, and are substantially rectangular sheets
having a size that includes a range surrounded by the outer periphery of the piezoelectric
element 2 in plan view. It is. The first sound propagation sheet 3 a covers one side of the
piezoelectric element 2, and the second sound propagation sheet 3 b covers the other side of the
piezoelectric element 2. The first sound propagation sheet 3a and the second sound propagation
sheet 3b are disposed so that the outer circumferences thereof substantially coincide with each
other in plan view, and are fixed to each other at the peripheral edges. Therefore, the
piezoelectric element 2 is surrounded by the first sound propagation sheet 3a and the second
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sound propagation sheet 3b. In addition, the fixing method of the 1st sound propagation sheet 3a
and the 2nd sound propagation sheet 3b is not specifically limited, For example, the fixing
method using an adhesive agent or an adhesive may be used, and the penetration of a pin like a
stapler may be sufficient. It may be a fixing method by the above, or may be a fixing method by
sewing.
[0034]
The sensor unit 1 is disposed such that the other surface of the second sound propagation sheet
3b abuts on the surface of the vibrating body P such as a musical instrument which is a detection
target of vibration. In addition, since the first sound propagation sheet 3a transmits the sound
incident from one surface side to the other surface side, the sensor unit 1 is disposed in this
manner to mainly transmit the first sound. While detecting the sound of the space which
propagates the propagation sheet 3a, the vibration of the vibrating body P which propagates the
2nd sound propagation sheet 3b is detected.
[0035]
As an upper limit of the difference of the sound pressure level of the incident sound to the 1st
sound propagation sheet ¦ seat 3a, and a transmitted sound, 10 dB is preferable and 5 dB is more
preferable. On the other hand, the lower limit of the difference in sound pressure level is
preferably 1 dB, more preferably 2 dB. When the difference between the sound pressure levels
exceeds the upper limit, the sound pressure level of the sound propagating to the piezoelectric
element 2 becomes too small, which may make it difficult for the piezoelectric element 2 to
detect sound. Conversely, if the difference between the sound pressure levels does not reach the
lower limit, it may be difficult to maintain the protective effect of the piezoelectric element 2 by
the first sound propagation sheet 3a. The difference between the sound pressure levels can be
detected, for example, in the state where the first sound propagation sheet 3 a covers the
piezoelectric element 2 and the state where the first sound propagation sheet 3 a is removed
from the sensor unit 1. The difference between the sound pressure levels of the incident sound
on the first sound propagation sheet 3a and the transmitted sound can be determined relatively
from the difference between the detected signal sounds by using the piezoelectric element 2 of
the unit 1 for detection. That is, the signal level of the transmitted sound detected when the first
sound propagation sheet 3a covers the piezoelectric element 2, and the signal level of the
incident sound detected when the first sound propagation sheet 3a is removed from the sensor
unit 1 The difference in sound pressure level can be determined relatively by comparing.
Specifically, for example, the above-described two types of sensor units and a speaker are
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disposed in an anechoic chamber, and the difference in sound pressure level is measured while
generating sound from the speaker. In this case, it is preferable to shield the surface opposite to
the measurement object of the two types of sensor units described above with a rigid body or a
sound absorbing material. The measurement for determining the difference in sound pressure
level is performed, for example, on the sound pressure level at a frequency of 100 Hz to 5000
Hz.
[0036]
As a lower limit of the surface density of the 1st sound propagation sheet 3a and the 2nd sound
propagation sheet 3b, 0.03 g / m <2> is preferable and 1 g / m <2> is more preferable. On the
other hand, the upper limit of the surface density is preferably 100 g / m <2>, and more
preferably 50 g / m <2>. If the surface density does not reach the lower limit, the strengths of the
first sound propagation sheet 3a and the second sound propagation sheet 3b decrease, and the
protective effect of the piezoelectric element 2 by the first sound propagation sheet 3a and the
second sound propagation sheet 3b May not be obtained enough. On the other hand, when the
surface density exceeds the upper limit, it is difficult for sound to be transmitted, which may
make it difficult for the piezoelectric element 2 to detect sound.
[0037]
The first sound propagation sheet 3a and the second sound propagation sheet 3b only have to be
capable of transmitting the sound incident from one surface to the other surface, and the forming
materials thereof are not particularly limited. For example, resins, metals, inorganic materials,
organic materials and the like can be used as the materials for forming these.
[0038]
When using resin as a forming material of the 1st sound propagation sheet 3a and the 2nd
sound propagation sheet 3b, as a main component of the formation material, PET, PP,
polystyrene (PS), polycarbonate (PC), polyphenylene sulfite (PPS) And polymethyl methacrylate
(PMMA), polyether imide (PEI), polyimide (PI), polyethylene naphthalate (PEN), triacetyl cellulose
(TAC), cyclic olefin resins, and the like. In addition, metal films such as aluminum, nickel and
platinum can also be used as the first sound propagation sheet 3a or the second sound
propagation sheet 3b. However, the metal film must be a thin film to propagate sound by the
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metal film, but if it is a thin film, it is easily broken. Therefore, it is preferable to form a metal film
in close contact with the surface of the piezoelectric element 2 by, for example, vapor deposition.
In that case, if the thickness of the metal film is about 10 nm, sound can be transmitted. If it is
possible to reduce the sound detection efficiency, it is also possible to further increase the
thickness of the metal film.
[0039]
Moreover, it is good for the 1st sound propagation sheet 3a to have a space ¦ gap. In the sheet
having an air gap inside, sound incident on one surface side is propagated to the other surface
side via the air gap, so the sound is easily propagated to the piezoelectric element 2 and the
piezoelectric element 2 detects the sound It becomes easy to do. In addition, the space ¦ gap
formed in the 1st sound propagation sheet 3a may penetrate in thickness direction. As described
above, since the air gap formed in the first sound propagation sheet 3a penetrates in the
thickness direction, it is easy to propagate the incident sound on one side to the other side.
[0040]
As the sheet having such a void, for example, a non-woven fabric, a cloth, a paper having a void, a
porous sheet or the like can be used. As the porous sheet, for example, a sheet of the same
material as the porous layer 4 may be used.
[0041]
Moreover, it is preferable that the 1st sound propagation sheet 3a and the 2nd sound
propagation sheet 3b have flexibility. When the first sound propagating sheet 3a and the second
sound propagating sheet 3b have flexibility, the first sound propagating sheet 3a and the second
sound propagating sheet 3b correspond to the shape and the compressive deformation of the
piezoelectric element 2. Since the deformation is possible, the piezoelectric element 2 can be
covered without being compressed, so that the durability of the piezoelectric element 2 can be
improved. In addition, since the first sound propagation sheet 3a has flexibility, the vibration due
to the incident sound on one surface side is easily propagated to the piezoelectric element 2, and
the detection accuracy of the sound by the piezoelectric element 2 is easily improved.
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[0042]
In addition, both surfaces of the piezoelectric element 2 may or may not be fixed to the other
surface of the first sound propagation sheet 3a and one surface of the second sound propagation
sheet 3b. When the piezoelectric element 2 is not fixed to the first sound propagating sheet 3a
and the second sound propagating sheet 3b, the piezoelectric element 2 does not distort with the
first sound propagating sheet 3a or the second sound propagating sheet 3b. It is easy to detect
sound and vibration more accurately. In addition, the fixing method in the case of fixing both
surfaces of the piezoelectric element 2 to the 1st sound propagation sheet 3a or the 2nd sound
propagation sheet 3 is not specifically limited, For example, the fixing method using an adhesive
agent or an adhesive may be sufficient. Alternatively, it may be a fixing method by the frictional
force between the surface of the piezoelectric element 2 and the surface of the first sound
propagation sheet 3 a or the second sound propagation sheet 3.
[0043]
Further, in FIG. 1, although the first sound propagation sheet 3 a and the second sound
propagation sheet 3 b are fixed to each other at the periphery in plan view, the first sound
propagation sheet 3 a and the second sound propagation sheet 3 b are And may be an integral
sound propagation sheet. For example, the first sound propagation sheet 3a and the second
sound propagation sheet 3b may be formed as one bag-shaped sound propagation sheet.
[0044]
<Advantage> Since the first sound propagation sheet 3a covers one surface of the piezoelectric
element 2, the sensor unit 1 can protect one surface of the piezoelectric element 2 for detecting
sound from being damaged, and as a result, the sound Can maintain the detection accuracy of In
addition, since the first sound propagation sheet 3 a covering one surface of the piezoelectric
element 2 transmits sound incident from one surface to the other surface, the sensor unit 1
transmits the sound to the other surface of the sensor unit 1. It is difficult for the first sound
propagation sheet 3a to reduce the sound incident from the side of the surface of the sheet, and
it is possible to detect the sound from the side of the surface together with the vibration of the
vibrator P. Therefore, by using the sensor unit 1 as a pickup of an instrument, it is possible to
easily reproduce the original tone of the instrument.
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[0045]
Further, in the sensor unit 1, since the second sound propagation sheet 3 b covers the other
surface of the piezoelectric element 2, it can also detect sound incident from the other surface
side, and at the time of installation on the vibrator P etc. Damage to the other surface of the
element 2 can be prevented.
[0046]
Second Embodiment In the sensor unit 11 of FIG. 3, a sound propagation sheet 13 is disposed so
as to cover one surface of the piezoelectric element 2.
In the sensor unit 11, no sound propagation sheet is disposed between the piezoelectric element
2 and the vibrating body P, and the other surface of the piezoelectric element 2 is disposed in
direct contact with the surface of the vibrating body P. In addition, since the piezoelectric
element 2 of the said sensor unit 11 of FIG. 3 is the same as that of the piezoelectric element 2 of
the sensor unit 1 of FIG. 1, the same code ¦ symbol is attached ¦ subjected and description is
abbreviate ¦ omitted.
[0047]
<Sound propagation sheet> As the sound propagation sheet 13, a sheet of the same quality as the
first sound propagation sheet 3a of the sensor unit 1 of FIG. 1 can be used. The sound
propagation sheet 13 is fixed to one surface of the piezoelectric element 2 so as to cover the
entire surface of the piezoelectric element 2 as shown in FIG. Thereby, damage to the
piezoelectric element 2 can be prevented. Further, since the sound propagation sheet 13
transmits the sound incident from one surface side to the other surface side, the piezoelectric
element 2 can detect the sound from the one surface side. In addition, the fixing method to the
piezoelectric element 2 of the sound propagation sheet 13 is not specifically limited, For
example, the sound propagation sheet 13 is fixed to one surface of the piezoelectric element 2
using an adhesive agent or an adhesive.
[0048]
Next, FIG. 4 shows the sensor unit 12 of another configuration of the present embodiment. The
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sound propagation sheet 14 of the sensor unit 12 has a size including a range surrounded by the
outer periphery of the piezoelectric element 2 in a plan view, covers one surface of the
piezoelectric element 2, and the peripheral edge is the surface of the vibrating body P It is fixed
to Thus, since the sound propagation sheet 14 is fixed to the surface of the vibrating body P, one
surface of the piezoelectric element 2 may not be fixed to the other surface of the sound
transmission sheet 14. By not fixing one surface of the piezoelectric element 2 to the other
surface of the sound propagation sheet 14, the piezoelectric element 2 does not distort along
with the expansion and contraction of the sound propagation sheet 14, and the piezoelectric
element 2 can accurately detect sound. .
[0049]
The sensor unit 12 of FIG. 4 may not have the other surface of the piezoelectric element 2 fixed
to the surface of the vibrating body P. If the piezoelectric element 2 is not fixed to the vibrating
body P, the piezoelectric element 2 does not distort along with the expansion and contraction of
the vibrating body P, and the piezoelectric element 2 can detect the vibration of the vibrating
body P with high accuracy.
[0050]
Advantages The sensor unit 11 and the sensor unit 12 can detect the vibration of the vibrating
body P more accurately because the other surface of the piezoelectric element 2 is in direct
contact with the surface of the vibrating body P.
[0051]
Third Embodiment The sensor unit 21 shown in FIG. 5 is a sensor unit provided with a sheet-like
piezoelectric element 2 having a porous layer.
The sensor unit 21 covers the first surface of the piezoelectric element 2, and the other surface
of the piezoelectric element 2 includes a first sound propagation sheet 3 a that transmits sound
incident from one surface to the other surface. And a sound blocking sheet 27 for covering and
substantially preventing transmission of sound incident from one surface to the other surface.
The first sound propagation sheet 3a and the piezoelectric element 2 of the sensor unit 21 in FIG.
5 are the same as the first sound propagation sheet 3a and the piezoelectric element 2 of the
sensor unit 1 in FIG. I omit explanation.
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[0052]
<Sound Blocking Sheet> The sound blocking sheet 27 is a substantially rectangular sheet having
a size including a range surrounded by the outer periphery of the piezoelectric element 2 in a
plan view, and a rigid body such as a metal plate can be used, for example. The sound blocking
sheet 27 is disposed such that the other surface is fixed to the surface of the vibrating body P
and one surface is in contact with the other surface of the piezoelectric element 2. Further, the
periphery of the first sound propagation sheet 3 a covering one surface of the piezoelectric
element 2 is fixed to the periphery of one surface of the sound blocking sheet 27.
[0053]
The sound blocking sheet 27 substantially prevents transmission of sound incident from the
other side to one side. As a result, since the sound propagating from the vibrating body P side is
significantly reduced, the sound from one surface side, that is, the space side can be
preferentially detected by the piezoelectric element 2. The sound from can be detected more
accurately.
[0054]
The lower limit of the difference between the sound pressure levels of the incident sound and the
transmitted sound on the sound blocking sheet 27 is preferably 50 dB, more preferably 60 dB.
On the other hand, the upper limit of the difference in sound pressure level is preferably 100 dB,
more preferably 90 dB. If the difference between the sound pressure levels is less than the lower
limit, the sound from the vibrating body P side is easily detected by the piezoelectric element 2,
and the detection accuracy of the sound from the space side may be reduced. Conversely, if the
difference between the sound pressure levels exceeds the upper limit, the thickness of the sound
blocking sheet 27 must be increased, and the sensor unit 21 may become unnecessarily large.
[0055]
The lower limit of the surface density of the sound blocking sheet 27 is preferably 500 g / m
04-05-2019
17
<2>, and more preferably 600 g / m <2>. On the other hand, the upper limit of the surface
density is preferably 2000 g / m <2>, and more preferably 1500 g / m <2>. If the surface density
is less than the lower limit, the sound from the vibrating body P can not be blocked sufficiently,
and the detection accuracy of the sound from the space side may be reduced. On the other hand,
when the surface density exceeds the upper limit, the thickness of the sensor unit 21 becomes
excessively large, which may unnecessarily increase the size.
[0056]
The sensor unit 21 shown in FIG. 5 may be turned over and disposed on the surface of the
vibrator P. That is, the surface of the first sound propagation sheet 3a opposite to the
piezoelectric element 2 may be fixed to the surface of the vibrating body P, and the sound
blocking sheet 27 may be disposed on the space side. When the mass of the sound blocking
sheet 27 is relatively large, when the sensor unit 21 is arranged as described above, the sound
blocking sheet 27 becomes a weight, and the vibration from the vibrating body P is easily
propagated to the piezoelectric element 2. Therefore, when the vibration from the vibrating body
P is to be detected preferentially, the vibration from the vibrating body P can be detected more
accurately by arranging the sensor unit 21 in this manner.
[0057]
<Advantage> Since the sensor unit 21 can reduce the transmitted sound from the other surface
side by the sound blocking sheet 27, it can detect the incident sound from one surface side more
accurately.
[0058]
Fourth Embodiment The sensor unit 31 shown in FIG. 6 is a sensor unit provided with a sheetlike piezoelectric element 2 having a porous layer.
The sensor unit 31 further includes a sound propagation sheet 33 that covers both surfaces of
the piezoelectric element 2 and transmits sound incident from the outer surface to the surface on
the piezoelectric element 2 side. In addition, since the piezoelectric element 2 of the said sensor
unit 31 of FIG. 6 is the same as that of the piezoelectric element 2 of the sensor unit 1 of FIG. 1,
the same code ¦ symbol is attached ¦ subjected and description is abbreviate ¦ omitted.
04-05-2019
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[0059]
<Sound Transmission Sheet> The sound transmission sheet 33 is, for example, a substantially
rectangular sheet, and has a size twice or more the planar area of the piezoelectric element 2 in a
plan view. The sound propagation sheet 33 is folded in half, and disposed so that the entire
surface of the piezoelectric element 2 abuts on the inner surface when folded. Thereby, both
surfaces of the piezoelectric element 2 are covered with the sound propagation sheet 33. As
described above, the piezoelectric element 2 whose both sides are covered with the sound
propagation sheet 33 is disposed such that one edge thereof abuts on the surface of the vibrating
body P. Further, both ends of the folded sound propagation sheet 33 are bent outward with
respect to the piezoelectric element 2 and fixed to the surface of the vibrating body P. Thus, the
sensor unit 31 is fixed to the vibrating body P by fixing the both ends of the sound propagation
sheet 33 to the surface of the vibrating body P. Further, the sensor unit 31 is fixed to the vibrator
P such that the thickness direction of the piezoelectric element 2 is substantially parallel to the
surface of the vibrator P. In addition, as the sound propagation sheet 33, the same quality as the
first sound propagation sheet 3a of the sensor unit 1 of FIG. 1 can be used.
[0060]
The sensor unit 31 is disposed such that the thickness direction of the piezoelectric element 2 is
substantially parallel to the surface of the vibrating body P. Therefore, both surfaces of the
piezoelectric element 2 are surfaces in space via the sound propagation sheet 33. Do. Therefore,
the sound from the space passes through the sound propagation sheet 33 and is detected on
both sides of the piezoelectric element 2. Since the sensor unit 31 can detect the sound from the
space on both sides of the piezoelectric element 2 as described above, the sound in the space can
be detected more accurately.
[0061]
<Advantage> Since the sensor unit 31 can accurately detect the sound from the space on both
sides of the piezoelectric element 2, it can be suitably used as a sensor incorporated in a
microphone or the like.
[0062]
04-05-2019
19
[Mounting Configuration of Sensor Unit] Next, the mounting configuration of the sensor unit to
the vibrator P will be described.
In addition, in FIGS. 7-19 which show the attachment structure of the said sensor unit, the thing
of the structure similar to the sensor unit of FIG. 1, FIG. 3 or FIG. 5 can be used as a sensor unit.
[0063]
<Mounting Configuration 1> In the configuration shown in FIG. 7, the non-vibration transmitting
material 48 and the vibration transmitting material 49 are disposed on the surface of the
vibrating body P. The non-vibration transmitting member 48 and the vibration transmitting
member 49 are both substantially rectangular parallelepipeds, and the lower surface is in contact
with the surface of the vibrating body P, and the side surfaces are in contact with each other. The
sensor unit 1 is disposed such that one surface faces the space, and the other surface abuts on
the top surfaces of the non-vibration transmitting member 48 and the vibration transmitting
member 49. The heights (distances between the upper and lower surfaces) of the non-vibration
transmitting material 48 and the vibration transmitting material 49 are substantially the same,
and the upper surface of the non-vibration transmitting material 48 and the upper surface of the
vibration transmitting material 49 are substantially flush.
[0064]
(Non-Vibration Transmission Material) The non-vibration transmission material 48 is a member
that hardly transmits the vibration of the vibrating body P. As a material for forming the nonvibration transmitting material 48, a gel or a sponge made of an organic material, an inorganic
material or the like can be used.
[0065]
(Vibration Transmission Material) The vibration transmission material 49 is a member that easily
propagates the vibration of the vibrating body P. As a material for forming the vibration
transmitting material 49, for example, wood, ceramics, metal or the like can be used, and as the
vibration transmitting material 49, a rigid body formed of these materials, that is, these materials
are not packed. It is possible to use one that is formed by Further, as the vibration transmitting
04-05-2019
20
material 49, a material of the same quality as that of the vibrating body P may be used.
Therefore, a convex portion may be formed on the surface of the vibrating body P, and the
convex portion may be used as a vibration transfer material.
[0066]
In the region where the other surface of the sensor unit 1 is in contact with the upper surface of
the non-vibration transmitting member 48, the piezoelectric element of the sensor unit 1 is hard
to propagate the vibration of the vibrating body P, so the sound from space is given priority. It is
detected. On the other hand, in the area where the other surface of the sensor unit 1 abuts on the
upper surface of the vibration transmitting member 49, the vibration of the vibrating body P is
easily propagated, so that the vibration of the vibrating body P is preferentially detected. Ru.
Therefore, the contact area between the sensor unit 1 and each of the non-vibration transmitting
member 48 and the vibration transmitting member 49 is adjusted by adjusting the size of the
non-vibration transmitting member 48 and the vibration transmitting member 49 in a plan view.
Thus, it is possible to adjust the ratio of the sound to the vibration detected by the piezoelectric
element. Thereby, for example, the tone of the electronic musical instrument using the sensor
unit 1 in a pickup can be adjusted.
[0067]
<Mounting Configuration 2> In the configuration shown in FIG. 8, in addition to the configuration
of FIG. 7, sheet-like air vibration occurs in a region overlapping with the top surface of the
vibration transmitting material 49 in plan view of one surface of the sensor unit 1. The blocking
material 47 is disposed. The air vibration blocking material 47 is disposed in the entire area
overlapping the upper surface of the vibration transmitting material 49 in plan view, and is
disposed in the area overlapping the upper surface of the non-vibration transmitting material 48
in planar view. Preferably not.
[0068]
(Air Vibration Shielding Material) The air vibration shielding material 47 is a member which
hardly transmits air vibration and easily transmits vibration from a solid. That is, by disposing the
air vibration blocking material 47 as shown in FIG. 8, the propagation of sound from the space to
the area of one surface of the sensor unit 1 in contact with the air vibration blocking material 47
04-05-2019
21
is suppressed. . For example, a metal plate or the like can be used as the air vibration blocking
material 47.
[0069]
In the area overlapping with the upper surface of the vibration transmitting member 49 in plan
view and preferentially detecting the vibration of the vibrating body P, the air vibration blocking
member 47 more reliably suppresses the detection of the sound from the space, and Since the
blocking member 47 functions as a weight, the piezoelectric element can detect the vibration of
the vibrating body P more accurately.
[0070]
<Mounting Configuration 3> In the configuration shown in FIG. 9, a sensor unit 41 is provided in
place of the sensor unit 1 in the configuration of FIG.
The sensor unit 41 has a sheet shape, and for example, a valley fold, a mountain fold and a valley
fold are formed in this order on a part from the one end to the other end of the sensor unit 1 in a
substantially parallel manner. The sensor unit 41 is disposed such that the surface projecting by
the mountain fold is one surface, and the other surface is in contact with the upper surface of the
non-vibration transmitting member 48 and the upper surface of the vibration transmitting
member 49. Further, the sensor unit 41 is disposed so that the ridge line of the mountain fold
overlaps the boundary between the non-vibration transmitting member 48 and the vibration
transmitting member 49 in a plan view.
[0071]
By disposing the sensor unit 41 in this manner, it is possible to suppress the propagation of the
vibration transmitted by the vibration transmitting member 49 to the non-vibration transmitting
member 48, and sound can be detected more accurately.
[0072]
<Mounting Configuration 4> In the configuration shown in FIG. 10, in place of the non-vibration
transmitting member 48 in the configuration of FIG. 7, a substantially rectangular non-vibration
transmitting member 58 having a greater height than the non-vibration transmitting member 48
04-05-2019
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is provided. Be done.
Further, in place of the sensor unit 1 having the configuration of FIG. 7, a sensor unit 51 having a
shape in contact with the upper surface of the vibration transmitting material 49 and the upper
surface of the non-vibration transmitting material 58 is disposed. The sensor unit 51 is in the
form of a sheet, and for example, the sensor unit 1 is formed such that the other surface is in
contact with the upper surface of the vibration transmitting member 49 disposed adjacently and
the upper surface of the non-vibration transmitting member 58 It is.
[0073]
By thus increasing the height of the non-vibration transmitting material 58, the propagation of
the vibration of the vibrating body P to the portion of the other surface of the sensor unit 51 in
contact with the non-vibration transmitting material 58 is further suppressed. Thereby, the
detection accuracy of the sound in the area of the piezoelectric element corresponding to the
upper surface of the non-vibration transmitting material 58 can be further improved.
[0074]
<Mounting Configuration 5> In the configuration shown in FIG. 11, in place of the vibration
transmitting member 49 in the configuration of FIG. 7, a substantially triangular prism shaped
vibration transmitting member 69 is provided. The vibration transmitting material 69 has a
substantially right triangle in cross section, and is disposed such that two surfaces sandwiching
the right angle in the cross section abut on the surface of the vibrating body P and the side
surface of the non-vibration transmitting material 48. The height of the side surface of the
vibration transmitting material 69 in contact with the side surface of the non-vibration
transmitting material 48 is substantially the same as the height of the non vibration transmitting
material 48.
[0075]
Further, in place of the sensor unit 1 of FIG. 7, a sensor unit 61 having a shape in contact with
the upper surface of the non-vibration transmitting member 48 and the inclined surface of the
vibration transmitting member 69 is provided. The sensor unit 61 is in the form of a sheet, and
04-05-2019
23
for example, the sensor unit 1 is bent so that the other surface is in contact with the upper
surface of the non-vibration transmitting member 48 disposed adjacently and the inclined
surface of the vibration transmitting member 69 It is.
[0076]
Thus, by using the vibration transfer material 69 having a slope inclined with respect to the
surface of the vibrating body P, the distance between the region for detecting vibration and the
surface of the vibrating body P in the other surface of the sensor unit 61 It can be made smaller.
Thereby, the vibration of the vibrating body P can be detected more accurately.
[0077]
<Mounting Configuration 6> In the configuration shown in FIG. 12, in place of the non-vibration
transmitting member 48 in the configuration of FIG. 11, a substantially square pole shaped nonvibration transmitting member 78 having a substantially trapezoidal cross section is disposed.
The cross section of the non-vibration transmitting member 78 is a trapezoid having two inner
angles perpendicular and having bases of different lengths. The non-vibration transmitting
member 78 is disposed such that the lower surface is in contact with the surface of the vibrating
body P, with the surface including the apex at which the right angle in the cross section is formed
as the lower surface. The non-vibration transmitting member 78 is disposed such that the side
surface including the shorter base of the trapezoidal shape in the cross section abuts on the side
surface of the vibration transmitting member 69. The height of the side surface of the nonvibration transmitting material 78 in contact with the side surface of the vibration transmitting
material 69 is substantially the same as the height of the side surface of the vibration
transmitting material 69, and the inclination angle of the upper surface of the non-vibration
transmitting material 78 is the vibration transmitting material It is almost the same as the
inclination angle of the slope of 69. Therefore, the upper surface of the non-vibration
transmitting member 78 and the slope of the vibration transmitting member 69 are substantially
flush with each other.
[0078]
Further, in place of the sensor unit 61 of FIG. 11, a sensor unit 71 having a shape to be in contact
with the upper surface of the non-vibration transmitting member 78 and the inclined surface of
04-05-2019
24
the vibration transmitting member 69 is provided. The sensor unit 71 is flat and flat on both
sides.
[0079]
Thus, by using the non-vibration transmitting material 78 and the vibration transmitting material
69 in which the upper surface of the non-vibration transmitting material 78 and the slope of the
vibration transmitting material 69 are substantially flush, the other of the flat sensor unit 71 Of
the non-vibration transmitting member 78 and the inclined surface of the vibration transmitting
member 69. Thus, the vibration of the vibrating body P can be detected with high accuracy, and
the sensor unit 71 can be easily formed without the need for bending the sensor unit 71 or the
like.
[0080]
<Mounting Configuration 7> In the configuration shown in FIG. 13, in the configuration of FIG. 7,
the non-vibration transmitting member 48 and the vibration transmitting member 49 are
disposed at an interval. That is, in the configuration shown in FIG. 13, an air gap is formed
between the non-vibration transmitting material 48 and the vibration transmitting material 49.
Thus, in the configuration shown in FIG. 13, the lower surface of the sensor unit 1 is in a space
between the portion where the upper surface of the non-vibration transmitting member 48
contacts, the portion where the upper surface of the vibration transmitting member 49 contacts,
and these members. And a facing portion. As a result, in a plan view, the sensor unit 1 has a
region overlapping the upper surface of the non-vibration transmitting member 48, a region
overlapping the upper surface of the vibration transmitting member 49, and a region located in
the air between these members. Have.
[0081]
As described above, the non-vibration transmitting member 48 and the vibration transmitting
member 49 are spaced apart, so that the interference between the non-vibration transmitting
member 48 and the vibration transmitting member 49 can be eliminated. Therefore, the
piezoelectric element of the sensor unit 1 has the detection accuracy of sound in the area
overlapping with the upper surface of the non-vibration transmitting material 48 in plan view,
and the vibrating body P in the area overlapping with the upper surface of the vibration
04-05-2019
25
transmitting material 49 in planar view. Vibration detection accuracy can be improved together.
[0082]
<Mounting Configuration 8> In the configuration shown in FIG. 14, in the configuration of FIG. 7,
the non-vibration transmitting member 48 and the vibration transmitting member 49 are
disposed at an interval, and between the non-vibration transmitting member 48 and the vibration
transmitting member 49. A substantially rectangular sound absorbing material 50 is disposed on
the In the configuration shown in FIG. 14, one side of the non-vibration transmitting member 48
and the other side of the sound absorbing member 50 are in contact, and one side of the sound
absorbing member 50 and the other side of the vibration transmitting member 49 are in contact.
. Thus, in the configuration shown in FIG. 14, the lower surface of the sensor unit 1 is in contact
with the portion where the upper surface of the non-vibration transmitting member 48 contacts,
the portion where the upper surface of the sound absorbing member 50 contacts, and the upper
surface of the vibration transmitting member 49 The part is provided continuously in one
direction. As a result, in the planar view, in the sensor unit 1, the area overlapping the upper
surface of the non-vibration transmitting material 48, the area overlapping the upper surface of
the sound absorbing material 50, and the area overlapping the upper surface of the vibration
transmitting material 49 are unidirectional. It is provided continuously to As a specific
configuration of the sound absorbing material 50, various configurations having sound absorbing
properties can be adopted. For example, a non-woven fabric or a woven fabric, or a member
obtained by coating a non-woven fabric or a woven fabric with a synthetic resin can be used.
[0083]
Thus, by arranging the sound absorbing material 50 between the non-vibration transmitting
material 48 and the vibration transmitting material 49, the interference between the nonvibration transmitting material 48 and the vibration transmitting material 49 can be reduced.
Therefore, the piezoelectric element of the sensor unit 1 has the detection accuracy of sound in
the area overlapping with the upper surface of the non-vibration transmitting material 48 in plan
view, and the vibrating body P in the area overlapping with the upper surface of the vibration
transmitting material 49 in planar view. Vibration detection accuracy can be improved together.
[0084]
04-05-2019
26
<Mounting Configuration 9> In the configuration shown in FIG. 15, the non-vibration
transmitting member 48 and the vibration transmitting member 49 are disposed at an interval in
the configuration of FIG. 7 and between the non-vibration transmitting member 48 and the
vibration transmitting member 49. A substantially rectangular parallelepiped cushioning material
60 is disposed on the In the configuration shown in FIG. 15, one side of the non-vibration
transmitting member 48 and the other side of the shock absorbing member 60 are in contact
with each other, and one side of the shock absorbing member 60 and the other side of the
vibration transmitting member 49 are in contact with each other. . Thereby, in the configuration
shown in FIG. 15, the lower surface of the sensor unit 1 is in contact with the portion where the
upper surface of the non-vibration transmitting member 48 abuts, the portion where the upper
surface of the shock absorbing material 60 contacts, and the upper surface of the vibration
transmitting member 49. The part is provided continuously in one direction. As a result, in the
planar view, in the sensor unit 1, the area overlapping the upper surface of the non-vibration
transmitting material 48, the area overlapping the upper surface of the shock absorbing material
60, and the area overlapping the upper surface of the vibration transmitting material 49 are
unidirectionally It is provided continuously to A specific configuration of the shock absorbing
material 60 is, for example, a configuration that can transmit sound and vibration moderately, is
more difficult to transmit sound than the non-vibration transmitting material 48, and hardly
transmits vibration more than the vibration transmitting material 49. It is possible to employ, for
example, a foam member having a plurality of pores based on a foam material can be used.
[0085]
As described above, by arranging the shock absorbing material 60 between the non-vibration
transmitting material 48 and the vibration transmitting material 49, the piezoelectric element of
the sensor unit 1 causes the shock absorbing material 60 to appropriately propagate both sound
and vibration. Thus, deep sounds and vibrations can be detected. Further, the piezoelectric
element can detect both sound and vibration with desired sensitivity by adjusting physical
properties such as elasticity, density and the like of the shock absorbing material 60.
[0086]
<Mounting Configuration 10> In the configuration shown in FIG. 16, the sensor unit 81a, the
non-vibration transmitting member 88a and the sensor unit 81b are stacked in this order on the
surface of the vibrating body P. The non-vibration transmitting member 88a is a sheet-like
member having a size including a range surrounded by the outer periphery of the sensor unit
81a and the sensor unit 81b in a plan view, and having a flat surface on both sides. The sensor
04-05-2019
27
unit 81a and the sensor unit 81b are, for example, sensor units of the same shape as the sensor
unit 1 of FIG. As the non-vibration transmitting material 88a, for example, the same material as
the non-vibration transmitting material 48 of FIG. 7 can be used.
[0087]
The sensor unit 81a disposed on the other surface of the non-vibration transmitting member 88a
is in direct contact with the surface of the vibrating body P, and mainly detects the vibration of
the vibrating body P. On the other hand, in the sensor unit 81b disposed on one surface of the
non-vibration transmitting material 88a, the propagation of the vibration of the vibrating body P
is suppressed by the non-vibration transmitting material 88a, so that the sound in space can be
detected with high accuracy. Therefore, by adjusting the ratio of the planar area of the sensor
unit 81a and the sensor unit 81b, the detection ratio of sound and vibration can be adjusted.
[0088]
<Mounting Configuration 11> In the configuration shown in FIG. 17, the sensor unit 81b in the
configuration of FIG. 16 is divided into a sensor unit 81c and a sensor unit 81d, and these two
sensor units 81b and 81c are one of the non-vibration transmitting members 88a. Arranged on
the surface.
[0089]
As described above, by separately arranging the sensor units for detecting the sound, the sensor
unit for detecting the sound can be selected, so that the detection ratio of the sound and the
vibration can be easily adjusted.
[0090]
In addition, although it was set as the structure which divides the sensor unit which detects a
sound into two in FIG. 17, the sensor unit which detects a sound may be divided into three or
more.
Also, the sensor unit 81a for detecting vibration may be divided and disposed.
04-05-2019
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[0091]
<Mounting Configuration 12> In the configuration shown in FIG. 18, an air vibration blocker 87
is further provided between the sensor unit 81a and the non-vibration transmitting member 88a
in the configuration of FIG.
The air vibration blocking material 87 is a sheet-like member having a size that includes a range
surrounded by the outer periphery of the sensor unit 81a in plan view, and is a sheet-like
member having flat surfaces on both sides, and for example, a metal plate can be used.
[0092]
By arranging the air vibration blocking material 87 in this manner, it is possible to suppress the
sound from transmitting through the non-vibration transmitting material 88a and propagating to
the sensor unit 81a, and the detection accuracy of the vibration of the vibrating body P in the
sensor unit 81a. Can be improved.
[0093]
<Mounting Configuration 13> In the configuration shown in FIG. 19, the non-vibration
transmitting member 88b and the sensor unit 81e are further disposed in this order on one
surface side of the sensor unit 81b in the configuration of FIG.
The sensor unit 81e is, for example, a sensor unit having the same shape as the sensor unit 81a.
The non-vibration transmitting material 88b is, for example, a non-vibration transmitting
material having the same shape as the non-vibration transmitting material 88a.
[0094]
The non-vibration transmitting material 88a and the non-vibration transmitting material 88b are
hard to propagate vibrations but easily propagate sounds, so in the sensor unit 81b, it is difficult
to detect vibrations from the vibrating body P and sounds from space are easily detected. .
Therefore, the vibration of the vibrating body P is detected by the sensor unit 81a, and the sound
from the space is detected by the sensor unit 81b and the sensor unit 81e. That is, with the
04-05-2019
29
configuration of FIG. 19, the area for detecting the sound in the sensor unit can be made larger
than the area for detecting the vibration, and the detection ratio of the sound can be increased.
[0095]
Furthermore, the sound detection ratio can be further increased by increasing the number of
stacked non-vibration transmitting materials and sensor units.
[0096]
In this case, as the non-vibration transmitting material, one that easily transmits sound is
preferable, and for example, one formed of a material having continuous pores such as a sponge
is preferable.
[0097]
[Configuration Example of Piezoelectric Element] Next, a configuration example of a piezoelectric
element provided in the sensor unit will be described.
[0098]
When sound is detected using a piezoelectric element having a rectangular planar porous body, if
the wavelength is smaller than the width of the piezoelectric element, the wavelength is canceled
and can not be detected.
Therefore, the piezoelectric element having a large area decreases in sensitivity when the
frequency becomes high.
However, in the odd mode such as the third mode, as shown in FIG. 20, there is a wavelength
which is not canceled even by the high frequency.
[0099]
By reducing the area for detecting the sound of the piezoelectric element, the sensitivity can be
made flat to a higher frequency. However, in this case, the capacitance decreases and the
04-05-2019
30
sensitivity decreases.
This decrease in capacitance can be suppressed by increasing the surface area of the
piezoelectric element. By making the piezoelectric element into the following configuration, the
surface area can be increased, and the sound can be detected with high sensitivity up to the high
frequency.
[0100]
<Structure Example 1> The piezoelectric element 92 shown in FIG. 21A is a box-shaped
piezoelectric element. For example, by setting it as the box-shaped structure of an open cube
shape in this way, the surface area of a piezoelectric element can be made to increase about 5
times compared with the case of forming in a sheet form, and the fall of electrostatic capacitance
can be suppressed.
[0101]
The piezoelectric element 92 shown in FIG. 21A is, for example, as shown in FIG. 21B, after
forming a flat plate-shaped piezoelectric element having one square as a center in plan view and
four squares connecting the sides of the square in common. This flat piezoelectric element can be
formed by bending along the four sides of the center square.
[0102]
<Structure Example 2> The piezoelectric element 102 shown in FIG. 22 is formed by bending the
sheet-shaped piezoelectric element 102 along the circumferential surfaces of a plurality of
cylindrical spacers 103.
Specifically, in the piezoelectric element 102, a plurality of spacers 103 are disposed
substantially in parallel so that the front and back piezoelectric elements bent on the
circumferential surface of the spacer 103 are substantially parallel. It is formed by passing a
piezoelectric element of the shape of a circle. For example, in the case of the piezoelectric
element 102 of FIG. 22, the surface area of the piezoelectric element in the same plane area can
be increased by about five times.
04-05-2019
31
[0103]
<Structure Example 3> The piezoelectric element 112 shown in FIG. 23 is formed by bending the
sheet-shaped piezoelectric element 112 at a plurality of places and supporting the sheet by the
cylindrical spacer 103 to form a bellows. Specifically, in the piezoelectric element 102, a plurality
of spacers 103 are arranged substantially in parallel at a position where the shape of the
piezoelectric element can be maintained by inserting a sheet-like piezoelectric element formed in
a bellows shape between two spacers 103. It is formed by inserting a plurality of sheet-like
piezoelectric elements, which are provided in advance and bent in a bellows shape, between the
plurality of spacers 103. For example, in the case of the piezoelectric element 112 of FIG. 23, the
surface area of the piezoelectric element in the same plane area can be increased by about six
times.
[0104]
Each piezoelectric element shown in FIGS. 21A, 22 and 23 may be installed in any direction.
[0105]
The stringed instrument 121 of FIGS. 24 and 25 includes a hollow body 123 having a
soundboard 122, a bridge 125 provided on the outer surface side of the soundboard 122 for
supporting a plurality of strings 124, and an outer surface of the bridge 125. A saddle 126
provided, a neck 127 connected to the body 123 and extending from one end of the soundboard
122, and a head 128 provided at one end of the neck 127 are mainly included.
The plurality of strings 124 is wound and locked at one end on a plurality of pegs 129 provided
on the head 128 and supported at the other end on the bridge 125 via the saddle 126 and is
locked to a plurality of pins 130 It is done. Also, the sound board 122 has a sound hole 131
between the other end of the neck 127 and the bridge 125.
[0106]
As shown in FIG. 25, a plurality of sounding bars 132 are attached to the inner surface of the
sounding board 122. Further, on the inner surface of the sounding plate 122, a plate 133
04-05-2019
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disposed at a position facing the bridge 125 with the sounding plate 122 interposed
therebetween, and a reinforcing plate 134 for reinforcing the strength of the sounding plate 122
are provided.
[0107]
The stringed instrument 121 includes the sensor unit 1 of FIG. The sensor unit 1 is attached to
the inner surface of the plate 133. That is, in the stringed instrument 121, the plate 133 is
configured as a vibrating body P, and the sensor unit 1 is disposed on the surface of the vibrating
body P. The stringed instrument 121 is configured as an electric acoustic guitar that converts the
vibration of the string 124 into an electrical signal by the sensor unit 121 and outputs the
electrical signal.
[0108]
<Advantage> The stringed instrument 121 can detect sounds generated by the resonance of the
vibration of the vibrating body P and the vibrations of the body 123 with the vibrations of the
plurality of strings 124 by the sensor unit 1, so the tone color of the musical instrument can Can
be converted to and output.
[0109]
Other Embodiments The above embodiments do not limit the configuration of the present
invention.
Therefore, the embodiment can omit, substitute, or add the components of each part of the
embodiment based on the description of the present specification and common technical
knowledge, and all of them can be construed as belonging to the scope of the present invention.
It should.
[0110]
For example, as shown in FIG. 26, the sensor unit 11 of the second embodiment may be disposed
such that a surface different from that of FIG. 3 abuts on the surface of the vibrator P. That is, the
04-05-2019
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sound propagation sheet 13 of the sensor unit 11 may be disposed in contact with the surface of
the vibrating body P. In this case, for example, by using a material of high strength as the
electrode layer of the surface on the opposite side of the sound propagation sheet 13 of the
piezoelectric element 2, sound is accurately detected while suppressing damage to the porous
layer. it can.
[0111]
In addition, since the sound propagation sheet disposed on the opposite side to the vibrating
body in the sensor unit of the first embodiment, the second embodiment and the third
embodiment has an effect as a weight, the thickness or thickness of these sound propagation
sheets By adjusting the mass, the characteristics detected by the piezoelectric element can be
changed. Furthermore, a weight may be disposed on the side opposite to the vibrating body of
the sensor unit. Specifically, a sheet formed of a synthetic resin may be disposed on the side
opposite to the vibrating body of the sensor unit, or a sheet, a plate, or the like formed of metal
may be disposed. When arranging such a sheet-like weight, a through hole may be formed in the
weight in order to facilitate the propagation of sound. Also, a cushioning layer may be disposed
between the sensor unit and the vibrator. By disposing the cushion layer in this manner, the
vibration transmitted from the vibrating body to the sensor unit can be reduced, and the
detection ratio of sound can be increased.
[0112]
The sensor unit does not have to be attached to the electric acoustic guitar. The sensor unit may
be attached to various stringed instruments such as a classical guitar, a violin, a cello, a mandolin,
a piano, etc., and may be attached to an instrument other than a stringed instrument such as a
percussion instrument. That is, the musical instrument according to the present invention does
not necessarily have to be a stringed instrument, and can be configured as a percussion
instrument or the like. Moreover, the attachment location of a sensor unit is not specifically
limited, It can attach to the arbitrary vibrating body of a musical instrument. Furthermore, the
sensor unit attached to the said musical instrument is not limited to the sensor unit 1 of FIG. 1, It
is possible to use any sensor unit in the said embodiment.
[0113]
The sensor unit may be configured as a musical instrument pickup attached to a musical
instrument, but may be used for a member other than a musical instrument such as a boundary
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microphone.
[0114]
As described above, since the sensor unit of the present invention can detect sound as well as
vibration while protecting the piezoelectric element, it is suitably used for various musical
instruments and the like, and malfunctions in buildings, machines, transport machines, etc. It is
suitably used for the detection of abnormal noise or noise that is a measure of
[0115]
1, 11, 12, 21, 21, 41, 51, 61, 71, 81, 81a, 81b, 81c, 81d, 81e Sensor unit 2, 92, 102, 112
Piezoelectric element 3a 1st sound propagation sheet 3b 2nd sound propagation sheet 4 Porous
Layer 5a First Electrode Layer 5b Second Electrode Layer 6 Holes 13, 14, 33 Sound
Transmission Sheet 27 Sound Shielding Sheet 47, 87 Air Vibration Shielding Material 48, 58, 78,
88a, 88b Non-vibration Transmission Material 49 , 69 Vibration transmitting material 50 Sound
absorbing material 60 Buffer material 103 Spacer 121 Stringed instrument 122 Sound board
123 Body 124 String 125 Bridge 126 Saddle 127 Neck 128 Head 129 Peg 130 Pin 131 Sound
hole 132 Sounding rod 133 Plate 134 Reinforcing plate P Vibrator
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