DESCRIPTION JP2009042264

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DESCRIPTION JP2009042264
To provide an acoustic filter having a small thickness, a small number of parts, a simple structure
and easy manufacture. In an apparatus (101) according to the present invention, an acoustic
filter (20α) made of a plurality of film-like materials is provided. By making at least one of them
a member having a concavo-convex shape, the rigidity of the material can be enhanced and the
insertion loss only in the ultrasonic region can be enhanced. Further, by providing the through
holes in addition to the concavo-convex shape, the insertion loss in the audible range other than
the ultrasonic range can be suppressed low. [Selected figure] Figure 4
Acoustic filter
[0001]
The present invention relates to an acoustic filter used in applications for significantly
attenuating sound waves in the ultrasonic range to pass only audible sound waves.
[0002]
Conventionally, for high sound pressure ultrasonic waves, filters for parametric speakers have
been developed.
[0003]
For example, in Patent Document 1, when an audible sound is to be reproduced using a speaker
using a parametric effect that blocks ultrasonic waves and transmits audible frequency sound
waves, for example, a nonlinear interaction of ultrasonic waves, An acoustic filter suitable for
protecting a listener from strong ultrasound waves, which is installed between a speaker and the
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listener, is disclosed.
[0004]
FIG. 15 is an explanatory view for explaining an acoustic filter described in Patent Document 1.
As shown in FIG.
As shown in FIG. 15, in the apparatus 900 described in Patent Document 1, the speaker 901 is
disposed on one side, the microphone 903 is disposed on the other side, and the acoustic filter
902 is disposed between the speaker 901 and the microphone 903.
[0005]
As shown in FIG. 15, in the acoustic filter 902 described in Patent Document 1, a sound
absorbing material is attached to the surface of a plurality of plate members, and a flat door state
(specifically, the sound absorbing material is adhered to both sides of the sound insulation plate
Used as an array with an inclination angle of 40 degrees, a gap between one sound insulation
board and another sound insulation board (80 mm, 15 stages).
As a result, it is described that the effect of reducing the primary wave to a level safe for the
human body and hardly affecting the sound pressure level and directivity characteristic of the
secondary wave can be obtained.
[0006]
In addition, Patent Document 2 describes a speaker using a parametric effect, which includes an
acoustic filter for reducing strong ultrasonic waves harmful to the human body, and in particular,
a description of an exhibit in an exhibition and a guide at a station home. It is disclosed about a
directional parametric speaker optimal for broadcasting and the like.
[0007]
FIG. 16 is an explanatory view for explaining a parametric speaker described in Patent Document
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2. As shown in FIG.
As shown in FIG. 16, the parametric speaker 910 described in Patent Document 2 includes an
acoustic filter 912 and a speaker 911, and includes a microphone 913 in order to confirm the
effect of the parametric speaker 910.
Also, the acoustic filter 912 includes two films 914 and 915 and a spacer 916.
[0008]
The acoustic filter 912 in the parametric speaker 910 shown in FIG. 16 is provided via a
predetermined space so that the films 914 and 915 sandwich the grid-like spacer 916. Thus, by
inserting the lattice-like spacer 916 between the films 914 and 915, there is no decrease in the
filter performance due to the films 914 and 915 adhering to each other, and the installation
direction can be arbitrarily selected.
[0009]
In addition, Patent Document 3 describes a speaker using a parametric effect, which includes an
acoustic filter for reducing strong ultrasonic waves harmful to the human body, and in particular,
an explanation of an exhibit at an exhibition and a guide at a station home. It is disclosed about a
directional parametric speaker optimal for broadcasting and the like.
[0010]
FIG. 17 is an explanatory view for explaining a parametric speaker described in Patent Document
3. As shown in FIG.
As shown in FIG. 17, the parametric speaker 920 described in Patent Document 3 includes an
acoustic filter 922 and a speaker 921, and includes a microphone 923 in order to confirm the
effect of the parametric speaker 920. The acoustic filter 922 is obtained by sandwiching the film
924 with a polyurethane foam 925.
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[0011]
The acoustic filter 922 in the parametric speaker 920 shown in FIG. 17 has the film 924
sandwiched between polyurethane foams 925, and thus reduces the primary wave to a level safe
for the human body, and the sound pressure level and direction of the secondary wave. It has
almost no influence on the characteristics. By adopting such an acoustic filter, it is possible to
eliminate the influence of the human body caused by the ultrasonic wave which is the
conventional neck without impairing the sharp directivity inherent to the parametric speaker,
and it is possible to realize the practical use of the parametric speaker. JP-A-61-41195 JP-A-6157197 JP-A-61-57198
[0012]
However, in the acoustic filter 902 described in Patent Document 1, the number of component
parts of the acoustic filter 902 is large, and the manufacturing cost is also significant. In addition,
the structure is complicated because it is necessary to make the door state, and the thickness of
the acoustic filter 902 becomes considerably large.
[0013]
Further, in the acoustic filter 912 of the parametric speaker 910 described in Patent Document
2, since it is necessary to provide a predetermined space between the films 914 and 915 and the
spacer 916, the thickness of the acoustic filter 912 is increased. In addition, it takes time to form
a predetermined space, and the manufacturing cost also increases.
[0014]
Furthermore, in the acoustic filter 922 of the parametric speaker 920 described in Patent
Document 3, the thickness of the polyurethane foam needs to be at least 3 cm, and 12 cm in the
case of a single element, so the thickness of the acoustic filter 922 becomes large.
[0015]
An object of the present invention is to provide an acoustic filter having a small thickness, a small
number of parts, a simple structure and easy manufacture.
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Means and effect for solving the problem
[0016]
(1) The acoustic filter according to the present invention is an acoustic filter composed of a
plurality of film-like materials, and at least one of the plurality of film-like materials is a film-like
material having an uneven shape. .
[0017]
In the acoustic filter according to the present invention, filters of a plurality of film-like materials
are provided.
An uneven shape is formed on at least one film-like material of the acoustic filter.
[0018]
In this case, by forming the concavo-convex shape in at least one film-like material, the rigidity of
the film-like material can be enhanced, and the damping can be improved to suppress the
vibration of the material.
Thereby, high insertion loss can be obtained with a film-like material of the same surface density.
As a result, it is possible to realize a thin and efficient filter. In addition, in uneven | corrugated
shape, a round shape may be sufficient and trapezoid shape, triangle shape, and rectangular
shape may be sufficient.
[0019]
In order to increase the insertion loss of the acoustic filter, there is also a method of increasing
the surface density of each film-like material and overlapping a plurality of materials, but in this
case, the insertion loss in the audible range also increases.
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[0020]
(2) At least one of the plurality of film-like materials may be made of a film-like material having a
concavo-convex shape and a through hole.
[0021]
In this case, by providing the through holes, attenuation of the audible area by the film-like
material due to the uneven shape can be reduced.
In the high sound pressure ultrasonic region, the transmission loss is not impaired because the
contribution of the sound radiated due to vibration of the film-like material is larger than the
contribution of the sound transmitted through the hole.
[0022]
(3) Preferably, at least one of the plurality of film-like materials is in contact with the convex
shape of the film-like material having the uneven shape.
[0023]
In this case, when the material having the concavo-convex shape is in contact with the other
material, structural attenuation is further imparted, and the attenuation of the ultrasonic wave
becomes large.
Further, when the through hole is formed, since the space is formed by the convex shape and the
other film-like material, attenuation by the acoustic system, that is, attenuation by the resonance
can be given.
[0024]
(4) The film-like material having a concavo-convex shape is formed only in a range
corresponding to the area of the sound generation source centering on the location where the
traveling direction of the sound to be attenuated by the film-like material intersects It is also
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good.
[0025]
In this case, the film-like material is formed to have a concavo-convex shape only in a range
corresponding to the area of the sound generation source centering on the location where the
traveling direction of the sound to be attenuated intersects the film-like material. As a result, the
uneven member can be reduced, and the manufacturing cost can be reduced.
Further, only the directional ultrasonic waves can be reduced, and the reduction of the audible
area sound waves can be suppressed without affecting the low directional sound area.
[0026]
(5) The uneven shape is formed such that the distance between the uneven shape of the film-like
member and another adjacent uneven shape is 0.034 mm or more and 17 mm or less, and the
height of one uneven shape is 0.034 mm or more and 17 mm or less Is preferred.
[0027]
In this case, it is possible to appropriately attenuate sound of a predetermined wavelength
according to the spacing of the asperities and the height of the asperity.
[0028]
(6) The uneven shape is formed such that the distance between the uneven shape of the film
member and another adjacent uneven shape is 0.5 mm or more and 17 mm or less, and the
height of one uneven shape is 0.5 mm or more and 17 mm or less Is preferred.
[0029]
In this case, it is possible to appropriately attenuate sound of a predetermined wavelength
according to the spacing of the asperities and the height of the asperity.
[0030]
(7) In the through holes, the hole area ratio may be 2% or less with respect to the total area of
the film-like material, and the hole diameter may be 3 mm or less.
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[0031]
In this case, if the hole area ratio is larger than 2% or the pore diameter is larger than 3 mm, the
blocking ability in the ultrasonic region is reduced.
[0032]
Hereinafter, embodiments according to the present invention will be described.
First Embodiment FIG. 1 is a schematic view showing an example of an apparatus 100 for
confirming the effect of an acoustic filter according to an embodiment of the present invention.
[0033]
The device 100 shown in FIG. 1 includes a speaker 10, an acoustic filter 20 and a microphone
30.
[0034]
The distance between the speaker 10 and the acoustic filter 20 shown in FIG. 1 is L1 (m), and the
distance between the acoustic filter 20 and the microphone 30 is L2 (m), and the speaker 10, the
acoustic filter 20 and the microphone 30 are in line. , And the straight line is disposed to pass
through the central portion of the acoustic filter 20.
Also, the acoustic filter 20 is disposed to intersect the straight line perpendicularly.
[0035]
The acoustic filter 20 is formed of two members.
In the present embodiment, the acoustic filter 20 is composed of one embossed member 20a and
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a non-embossed flat member 20b.
Moreover, it is preferable that it is depth 0.034 mm-17 mm, and, as for the uneven | corrugated
shape 220 formed by embossing, it is more preferable that they are depth 0.5 mm-17 mm.
Moreover, it is preferable that they are 0.034 mm or more and 17 mm or less, and it is more
preferable that they are 0.5 mm or more and 17 mm or less.
[0036]
Second Embodiment FIG. 2 is a schematic view showing an example of a device 100a according
to an embodiment of the present invention.
[0037]
The apparatus 100 a shown in FIG. 2 includes a speaker 10, an acoustic filter 21 and a
microphone 30.
[0038]
The distance between the speaker 10 and the acoustic filter 21 shown in FIG. 2 is L1 (m), and the
distance between the acoustic filter 21 and the microphone 30 is L2 (m), and the speaker 10, the
acoustic filter 21 and the microphone 30 are in line. , And the straight line is disposed to pass
through the central portion of the acoustic filter 21.
Further, the acoustic filter 21 is disposed to intersect the straight line perpendicularly.
[0039]
The acoustic filter 21 is formed of two members.
In the present embodiment, the acoustic filter 21 is embossed, and is a single member 21 a
having a plurality of through holes 221 formed therein, and a flat member 21 b having neither
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the embossing nor the through holes 221 formed thereon. It consists of
The acoustic filter 21 is formed by arranging the one member 21 a and the flat member 21 b at a
predetermined interval.
In this case, an air layer 280 can be provided between the concavo-convex shape 220 and the
planar member 21b formed by embossing the one member 21a.
Moreover, it is preferable that it is depth 0.034 mm-17 mm, and, as for the uneven | corrugated
shape 220 formed by embossing, it is more preferable that they are depth 0.5 mm-17 mm.
Moreover, it is preferable that they are 0.034 mm or more and 17 mm or less, and it is more
preferable that they are 0.5 mm or more and 17 mm or less. Furthermore, the through hole 221
preferably has a hole area ratio of 2% or less with respect to the area of the member 21a and a
hole diameter of 3 mm or less. In addition, in FIG. 2, although the through-hole 221 is provided
in addition to the uneven | corrugated shape 220, it is not limited to this, You may provide also
in any one or both of a recessed part or a convex part.
[0040]
Third Embodiment FIG. 3 is a schematic view showing an example of an apparatus 100b
according to an embodiment of the present invention.
[0041]
The device 100 b shown in FIG. 3 includes a speaker 10, an acoustic filter 22 and a microphone
30.
[0042]
The space between the speaker 10 and the acoustic filter 22 shown in FIG. 3 is L1 (m), and the
space between the acoustic filter 22 and the microphone 30 is L2 (m), and the loudspeaker 10,
the acoustic filter 22 and the microphone 30 are in line. , And the straight line is disposed to pass
through the central portion of the acoustic filter 22.
Also, the acoustic filter 22 is disposed to intersect the straight line perpendicularly.
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[0043]
The acoustic filter 22 is formed of two members.
In the present embodiment, the acoustic filter 22 is embossed, and is a single member 22a in
which a plurality of through holes 221 are formed, and a flat member 22b in which neither the
embossing nor through holes 221 are formed. It consists of The acoustic filter 22 is formed by
overlapping the one member 22a and the planar member 22b. That is, one member 22a and the
flat member 22b are provided in contact with each other. Moreover, it is preferable that they are
0.034 mm or more and 17 mm or less in depth, and, as for the uneven | corrugated shape 220
formed of the embossing, it is more preferable that they are depth (height) 0.5 mm or more and
17 mm or less. Moreover, it is preferable that they are 0.034 mm or more and 17 mm or less,
and it is more preferable that they are 0.5 mm or more and 17 mm or less. Furthermore, the
through hole 221 preferably has a hole area ratio of 2% or less with respect to the area of the
member 22a, and a hole diameter of 3 mm or less. In addition, although the through-hole 221 is
provided in addition to the uneven | corrugated shape 220, it is not limited to this, You may be
provided also in any one or both of a recessed part and a convex part.
[0044]
Fourth Embodiment FIG. 4 is a schematic view showing an example of a device 101 according to
an embodiment of the present invention.
[0045]
The device 101 shown in FIG. 4 is provided with an acoustic filter 20α instead of the acoustic
filter 20 of the device 100 shown in FIG.
The acoustic filter 20α is formed of two members. In the present embodiment, the acoustic filter
20α is composed of a member 20c embossed and a flat member 20b not embossed. The
acoustic filter 20α is formed by arranging the member 20c and the flat member 20b at a
predetermined interval.
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[0046]
Here, the member 20c will be described. FIG. 5 is a schematic view for explaining the details of
the member 20c constituting the acoustic filter 20α.
[0047]
As shown in FIG. 5, the member 20c is formed of a single rectangular member. In the present
embodiment, although it has a rectangular shape, the present invention is not limited to this, and
it may have an arbitrary shape such as a triangular shape or a trapezoidal shape.
[0048]
The member 20c has a size about the diameter of the speaker 10 and is smaller than the area of
the flat member 20b.
[0049]
Further, in the present embodiment shown in FIG. 4, L1 (m) is between the speaker 10 and the
acoustic filter 20α, and between the acoustic filter 20α and the microphone 30 as in the first
embodiment. L2 (m).
Further, the air layer 280 can be provided by the member 20c and the flat member 20b.
Moreover, it is preferable that it is depth 0.034 mm-17 mm, and, as for the uneven | corrugated
shape 220 formed by embossing, it is more preferable that they are depth 0.5 mm-17 mm.
Moreover, it is preferable that they are 0.034 mm or more and 17 mm or less, and it is more
preferable that they are 0.5 mm or more and 17 mm or less.
[0050]
Fifth Embodiment FIG. 6 is a schematic view showing an example of a device 101a according to
an embodiment of the present invention.
[0051]
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An apparatus 101a shown in FIG. 6 is provided with an acoustic filter 21α instead of the
acoustic filter 21 of the apparatus 100a shown in FIG.
The acoustic filter 21α is formed of two members. In the present embodiment, the acoustic filter
21α is formed of a member 21c which is embossed and in which a plurality of through holes
221 are formed, and a flat member 21b which is not embossed. The acoustic filter 21α is
formed by arranging the member 21c and the plane member 21b at a predetermined interval.
[0052]
The member 21c is formed of a single rectangular member, similarly to the member 20c shown
in FIG. Further, unlike the one member 20c, the member 21c is embossed, and a plurality of
through holes 221 are further formed.
[0053]
In the present embodiment shown in FIG. 6, as in the second embodiment, L1 (m) is between the
speaker 10 and the acoustic filter 21α, and L2 (m) between the acoustic filter 21α and the
microphone 30. m). In addition, the air layer 280 can be provided by the member 21c and the
flat member 21b, and the concavo-convex shape 220 formed by embossing is preferably a depth
of 0.034 mm or more and 17 mm or less, and a depth (height It is more preferable that it is 0.5
mm or more and 17 mm or less. Moreover, it is preferable that they are 0.034 mm or more and
17 mm or less, and it is more preferable that they are 0.5 mm or more and 17 mm or less.
Furthermore, the through hole 221 preferably has a hole area ratio of 2% or less with respect to
the area of the member 21c, and a hole diameter of 3 mm or less. In addition, although the
through-hole 221 is provided in addition to the uneven | corrugated shape 220, it is not limited
to this, You may be provided in any one or both of a recessed part or a convex part.
[0054]
Sixth Embodiment FIG. 7 is a schematic view showing an example of a device 101b according to
an embodiment of the present invention.
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[0055]
The device 101b shown in FIG. 7 is provided with an acoustic filter 22α instead of the acoustic
filter 22 of the device 100b shown in FIG.
The acoustic filter 22α is formed of two members. In the present embodiment, the acoustic filter
22α is formed of a member 22c which is embossed and in which a plurality of through holes
221 are formed, and a flat member 22b which is not embossed. The acoustic filter 22α is
formed by bringing the member 22c and the flat member 22b into contact with each other.
[0056]
The member 22c is formed of a single rectangular member, similar to the member 20c shown in
FIG. Further, the member 22c is embossed, and a plurality of through holes 221 are further
formed.
[0057]
In the present embodiment shown in FIG. 7, L1 (m) is between the speaker 10 and the acoustic
filter 22α, and L2 (m) between the acoustic filter 22α and the microphone 30, as in the third
embodiment. m). The acoustic filter 22α is formed by overlapping the member 22c and the
planar member 22b. That is, the member 22c and the planar member 22b are in a state of being
in contact with each other. Moreover, it is preferable that it is depth 0.034 mm-17 mm, and, as
for the uneven | corrugated shape 220 formed by embossing, it is more preferable that they are
depth 0.5 mm-17 mm. Moreover, it is preferable that they are 0.034 mm or more and 17 mm or
less, and it is more preferable that they are 0.5 mm or more and 17 mm or less. Furthermore, the
through hole 221 preferably has a hole area ratio of 2% or less with respect to the area of the
member 22c, and a hole diameter of 3 mm or less. In addition, although the through-hole 221 is
provided in addition to the uneven | corrugated shape 220, it is not limited to this, You may be
provided in any one or both of a recessed part or a convex part.
[0058]
As described above, in the apparatuses 100, 100a, 100b, 101, 101a, 101b according to the first
to sixth embodiments, at least one member 20a, 21a, 22a, 20c, 21c, By forming the concavo-
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convex shape in 22c, the attenuation of the acoustic filters 20, 21, 22, 20α, 21α, 22α can be
increased.
[0059]
In addition, since the flat member 22b in the third and sixth embodiments is in contact with one
member 22a or 22c having a concavo-convex shape, structural attenuation is further applied,
and the attenuation of ultrasonic waves is increased.
Further, since the plurality of air layers 280a are formed by the convex shape of the concavoconvex shape 220 formed by embossing and the plane member 22b, attenuation by the acoustic
system, that is, attenuation by resonance can be further imparted.
[0060]
Further, the members 21a, 22a, 21c and 22c in the second, third, fifth and sixth embodiments
can reduce the attenuation of the audible range by having the through holes 221. In the
ultrasonic region of high sound pressure, the contribution of the sound emitted when the
members 21a, 22a, 21c, 22c vibrate is larger than the contribution of the sound transmitted
through the plurality of through holes 221, so the transmission loss The decrease in
[0061]
Example 1 In Example 1, in the device 101 in FIG. 4, as shown in FIG. 7, the member 20 c and the
flat member 20 b are acoustic filters in a state where one member 20 c and the flat member 20 b
are in contact with each other. It formed 20α. The member 20c is embossed so that a 480 mm
long and 560 mm wide aluminum foil with a thickness of 30 μm can be formed to have an
uneven shape 220 with a depth of 0.5 mm or more and 1 mm or less and a peak distance of
about 8 mm. On the other hand, polyvinyl fluoride (PVF) of 900 mm × 900 mm and 21 μm in
thickness was used as the planar member 20 b. The member 20c was adhered and attached only
to the periphery of the central portion of the plane member 20b, and an acoustic filter 20α was
formed.
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[0062]
An interval L1 between the speaker 10 and the acoustic filter 20α, and an interval L2 between
the acoustic filter 20α and the microphone 30 are each 0.1 m.
[0063]
In this device 101, sound pressure levels were measured at microphone positions when an
ultrasonic wave of 40 kHz was emitted at a high sound pressure of about 130 dB from the
speaker 10 and when an acoustic wave of about 80 dB was emitted.
[0064]
Example 2 In Example 2, the device 101 b in FIG. 7 was formed.
The acoustic filter 22α is composed of a member 22c and a flat member 22b.
The member 22c is embossed to have a height of 480 mm and a width of 560 mm, and an
aluminum foil with a thickness of 30 μm having a depth of 0.5 mm or more and 1 mm or less
and a concavoconvex shape 220 with about 8 mm between peaks. On the other hand, polyvinyl
fluoride (PVF) of 900 mm × 900 mm and 21 μm in thickness was used as the planar member
22 b. A member 22c was adhered and attached only to the periphery of the central portion of the
planar member 22b, to produce an acoustic filter 22α.
[0065]
The interval L1 between the speaker 10 and the acoustic filter 22α and the interval L2 between
the acoustic filter 22α and the microphone 30 are each 0.1 m.
[0066]
In this device 101b, sound pressure levels at microphone positions were measured when an
ultrasonic wave of 40 kHz was emitted at a high sound pressure of about 130 dB from the
speaker 10 and when an acoustic wave of about 80 dB was emitted.
[0067]
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Comparative Example In Comparative Example 1, the device 800 in FIG. 8 was formed.
An acoustic filter 80 was used instead of the acoustic filter 22α.
The acoustic filter 80 was prepared by adhesively fixing the periphery of an aluminum foil 80c
having a thickness of 30 μm (480 mm × 560 mm) to a center of a polyvinyl fluoride (PVF) 80 b
having a thickness of 21 μm (900 mm × 900 mm).
[0068]
The distance L1 between the speaker 10 and the acoustic filter 80 and the distance L2 between
the acoustic filter 80 and the microphone 30 were each 0.1 m.
[0069]
In this apparatus 800, sound pressure levels at microphone positions were measured when an
ultrasonic wave of 40 kHz was emitted at a loud sound pressure of about 130 dB from the
speaker 10 and when an acoustic wave of about 80 dB was emitted.
[0070]
In the following description, the insertion loss (dB) is used as a result of subtracting the sound
pressure level when the acoustic filter is provided from the sound pressure level when the
acoustic filter is not provided between the speaker and the microphone.
[0071]
FIG. 9 is a view showing the measurement results of the insertion loss of the devices 101, 101b,
and 800 when a 40 kHz ultrasonic wave is emitted from the speaker 10 at a high sound pressure
of about 130 dB.
[0072]
The vertical axis of FIG. 9 indicates the insertion loss (dB), and the horizontal axis indicates the
device 800 (comparative example), the device 101 (example 1) and the device 101 b (example 2)
which are the test object.
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[0073]
As shown in FIG. 9, when a 40 kHz ultrasonic wave is emitted from the speaker 10 with a high
sound pressure of about 130 dB, the device 800 (comparative example) has an insertion loss of
23.2 dB, whereas the device 101 (implementation In Example 1) there was an insertion loss of
38.8 dB and in the device 101b (Example 2) there was an insertion loss of 40.5 dB.
As a result, it is understood that the insertion loss in the acoustic filter 20α and the acoustic
filter 22α of the devices 101 and 101b in the first and second embodiments is about 15 dB to
about 17 dB larger than that of the acoustic filter of the device 800. The
[0074]
FIG. 10 is a view showing the measurement results of the devices 101, 101b, and 800 when the
speaker 10 emits an acoustic sound wave in the audible range of about 80 dB.
[0075]
The vertical axis of FIG. 10 represents insertion loss (dB), the horizontal axis represents
frequency (Hz), the solid line represents the result of apparatus 800 (comparative example), and
the broken line represents the result of apparatus 101 (Example 1). The dashed-dotted line
shows the result of the device 101b (Example 2).
[0076]
As shown in FIG. 10, the device 101 exhibited a main fraction characteristic of insertion loss
almost equal to that of the device 800.
Further, when the device 101 and the device 101 b are compared, it can be understood that the
insertion loss in the audible range is suppressed by the through hole 221.
[0077]
Thus, by making at least one of the plurality of film-like materials into a material having
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asperities, insertion loss in the ultrasonic band can be increased.
Moreover, the insertion loss of an audible area can be suppressed by opening a through-hole.
[0078]
Example 3 In Example 3, instead of polyvinyl fluoride (PVF) having a thickness of 21 μm of the
flat member 22b of the apparatus 101b in Example 2, polyvinyl chloride having a thickness of
30 μm was provided as the flat member 22b. The device 101c was formed.
[0079]
The interval L1 between the speaker 10 and the acoustic filter 22α and the interval L2 between
the acoustic filter 22α and the microphone 30 are each 0.1 m.
[0080]
In this device 101c, sound pressure levels were measured at microphone positions when
ultrasonic waves of 40 kHz were emitted at a high sound pressure of about 130 dB from the
speaker 10 and when sound waves of about 80 dB were emitted.
[0081]
FIG. 11 is a view showing the measurement results of the devices 101b and 101c in the case
where a 40 kHz ultrasonic wave is emitted from the speaker 10 at a high sound pressure of
about 130 dB.
[0082]
The vertical axis of FIG. 11 indicates the insertion loss (dB), and the horizontal axis indicates the
device 101b which is the test body of the second embodiment and the test body 101c of the
third embodiment.
[0083]
As shown in FIG. 11, when a 40 kHz ultrasonic wave is emitted from the speaker 10 at a high
sound pressure of about 130 dB, the apparatus 101b (Example 2) has an insertion loss of 40.5
dB, and the apparatus 101c (Example 3) ) Had an insertion loss of 35.2 dB.
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[0084]
FIG. 12 is a view showing the measurement results of the devices 101b and 101c in the case of
emitting an acoustic sound wave in the audible range of about 80 dB from the speaker 10. As
shown in FIG.
[0085]
The vertical axis in FIG. 12 indicates the insertion loss (dB), the horizontal axis indicates the
frequency (Hz), the solid line indicates the result of the device 101c (Example 3), and the dasheddotted line indicates the device 101b (Example 2) Show the results of
[0086]
As shown in FIGS. 11 and 12, it has been found that the acoustic filters 22α in the devices 101b
and 101c exhibit substantially the same insertion loss.
[0087]
That is, the material of the flat member 22b is not limited to polyvinyl fluoride (PVF), and the
same effect can be obtained even if it is another material such as polyvinyl chloride.
[0088]
Example 4 In Example 4, an apparatus 101 d using an acoustic filter 20 d instead of the acoustic
filter 20 α of the apparatus 101 in Example 1 was formed.
The acoustic filter 20d is made of the same material as the acoustic filter 20α, and the
arrangement of the member 20c and the planar member 20b (see FIG. 4) is reversed.
That is, the flat member 20 b is provided on the speaker 10 side, and the member 20 c is
provided on the microphone 30 side.
[0089]
The distance L1 between the speaker 10 and the acoustic filter 20d and the distance L2 between
the acoustic filter 20d and the microphone 30 are each 0.1 m.
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[0090]
In this device 101d, sound pressure levels at microphone positions were measured when an
ultrasonic wave of 40 kHz was emitted at a high sound pressure of about 130 dB from the
speaker 10 and when an acoustic wave of about 80 dB was emitted.
[0091]
FIG. 13 is a view showing the measurement results of the devices 101 and 101 d when the 40
kHz ultrasonic wave is emitted from the speaker 10 at a high sound pressure of about 130 dB.
[0092]
The vertical axis of FIG. 13 indicates the insertion loss (dB), and the horizontal axis indicates the
device 101 which is the test body of the embodiment 1 and the test body 101d of the
embodiment 4.
[0093]
As shown in FIG. 13, when ultrasonic waves of 40 kHz are emitted from the speaker 10 at a high
sound pressure of about 130 dB, the device 101 (Example 1) has an insertion loss of 38.8 dB,
and the device 101 d (Example 4) ) Had an insertion loss of 39.5 dB.
[0094]
FIG. 14 is a view showing the measurement results of the devices 101 and 101 d when the
speaker 10 emits an acoustic sound wave in the audible range of about 80 dB.
[0095]
The vertical axis in FIG. 14 represents the insertion loss (dB), the horizontal axis represents the
frequency (Hz), the solid line represents the result of the device 101d (Example 4), and the
broken line represents the device 101 (Example 1). Show the results.
[0096]
As shown in FIGS. 13 and 14, the devices 101 and 101d were found to exhibit approximately
equal insertion loss.
[0097]
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When the acoustic filter 20α is replaced with the acoustic filter 20d as described above, the flat
member 20b is provided on the speaker 10 side and the member 20c is provided on the
microphone 30 side instead of providing the member 20c on the speaker 10 side in FIG. Even
with the configuration (the arrangement of the member 20c and the flat member 20b shown in
FIG. 4 is interchanged), substantially the same effect can be obtained.
[0098]
In the first to sixth embodiments, the planar members 20b, 21b and 22b and the one members
20a, 21a, 22a, 20c, 21c and 22c correspond to film materials, and the acoustic filters 20, 21 and
22 are used. , 20α, 21α, 22α correspond to acoustic filters, one member 20a, 21a, 22a, 20c,
21c, 22c corresponds to a film-like material having an uneven shape, and one member 21a, 22a,
21c, 22c The plurality of through holes 221 correspond to through holes, and the uneven shape
220 formed by embossing corresponds to an uneven shape.
[0099]
Although the present invention is described in the preferred first to sixth embodiments described
above, the present invention is not limited thereto.
It will be understood that various other embodiments may be made without departing from the
spirit and scope of the present invention.
Furthermore, in the present embodiment, actions and effects according to the configuration of
the present invention are described, but these actions and effects are only examples and do not
limit the present invention.
[0100]
The schematic diagram which shows an example of the apparatus which concerns on one
embodiment which concerns on this invention The schematic diagram which shows an example
of the apparatus which concerns on one embodiment which concerns on this invention A model
which shows an example of the apparatus which concerns on one embodiment which concerns
on this invention A schematic diagram showing an example of the device according to the
embodiment of the present invention A schematic diagram for explaining details of members
constituting the acoustic filter A schematic diagram showing an example of the device according
to the embodiment according to the present invention A schematic diagram showing an example
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of an apparatus according to an embodiment of the present invention A schematic view showing
an example of an apparatus in a comparative example A diagram showing an insertion loss in the
ultrasonic region of the present invention and a comparative example The figure shows the
insertion loss in the audible range of the figure. The figure shows the insertion loss in the
ultrasonic range of the present invention and the comparative example. The figure shows the
insertion loss in the audible range of the present invention and the comparative example. Figure
showing the insertion loss in comparison with the present invention Explanatory drawing for
demonstrating the acoustic filter of patent document 1 which shows the insertion loss in the
audible range with the explanatory diagram for demonstrating the parametric speaker of patent
document 2 for explaining the parametric speaker of patent document 3 for explaining the
parametric speaker of patent document 3 Explanation
Explanation of sign
[0101]
10 Speaker 20, 21, 22, 20α, 21α, 22α Acoustic filter 30 Microphone 20a, 21a, 22a One
member 20c, 21c, 22c Member 20b, 21b, 22b Flat member 100, 100a, 100b Device 220 formed
by embossed shape Irregular shapes 221 Multiple through holes
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