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DESCRIPTION JP2010171927

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DESCRIPTION JP2010171927
To generate vibration waveform (sound) efficiently, suppress attenuation of the vibration
waveform and transmit it to a distant place, and suppress reflection of sound to reduce
reverberation, directivity, frequency characteristic, etc. To provide a speaker that is sufficiently
improved in the sound quality of. SOLUTION: A bending stress is applied to a speaker diaphragm
including a pair of sheets and a honeycomb core of a hollow honeycomb structure sandwiched
between them and adhered so that a hollow portion is sealed, The speaker is configured to
include such a speaker diaphragm. [Selected figure] Figure 3
Loudspeaker diaphragm and speaker using the same
[0001]
The present invention relates to a diaphragm for a speaker that vibrates a plate with a magnetic
coil, a piezoelectric vibrator, or the like to generate music and sound, and a speaker using the
diaphragm.
[0002]
Conventionally, there are a cone type, a dome type, a horn type, etc., and the speaker is used
properly according to a use.
Among these, the cone type speaker having a conical diaphragm is widely used in general, and
the diaphragm is vibrated by passing a driving current to a voice coil disposed on the diaphragm,
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and this causes the colossal wave of air. Sound is output by creating (longitudinal waves) (Patent
Documents 1 and 2).
[0003]
In the past, NTX Corporation and others have long developed and put into practical use a speaker
that generates sound by vibrating a flat plate as a diaphragm and using it (see, for example,
Patent Document 3). This type of speaker has the advantages of being lightweight, space-saving,
and easy to install, but in terms of tone range, frequency characteristics, and sound reproduction,
a cone-shaped woofer, dome-shaped tweeter, and squawker are mounted. The application was
limited compared with the usual box type speaker.
[0004]
Speakers used in the past output sound by creating a compressional wave of air (longitudinal
wave), so the sound propagation is attenuated in proportion to the square of the distance, and
the sound is sent to a distant place Had to generate a loud sound.
[0005]
On the other hand, the transverse wave is characterized in that the attenuation factor is very low
compared to the longitudinal wave, and a speaker capable of transmitting sound to a distant
place using this has been proposed (for example, Patent Document 4).
In this method, bending stress is applied to the diaphragm of the speaker, and a transverse wave
is generated due to the bending. However, in such a technique, it is premised that a plate-like
member made of wood, plastic, metal or the like is used as the diaphragm and this plate-like
member is bent to generate and apply the bending stress.
[0006]
In a speaker, an electromagnetic coil or a piezoelectric element converts an electric signal into
vibration, and the sound is emitted by transmitting the vibration to air through a flat panel
(diaphragm). Therefore, when the rigidity of the panel (diaphragm) is small and soft, the panel
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can not follow the vibration of the vibrator. That is, only the periphery of the vibrator vibrates,
and most of the others can not obtain the vibration at the required frequency, and extraneous
noise is generated or no necessary sound is produced due to interference. In the case of highpitched sound (the frequency is high and the vibration is fast), the above-mentioned phenomenon
is particularly noticeable.
[0007]
Therefore, when the panel is made of the above-described plate-like plastic or the like, the abovementioned phenomenon becomes remarkable, and the panel, that is, the speaker has a
performance that can be put to practical use. Can not.
[0008]
On the other hand, when the panel (diaphragm) is formed of a hard plate-like member such as
metal, the rigidity of the panel can be enhanced, but the panel itself becomes too heavy, so the
vibrator vibrates the panel. Even so, the panel can not follow the vibration of the vibrator
because the inertial force of the panel becomes too large.
As a result, the panel can reproduce only a partial frequency with respect to the vibration from
the vibrator.
[0009]
Therefore, when the panel is made of the above-mentioned plate-like metal, the above-mentioned
phenomenon becomes remarkable, and the panel, that is, the speaker can not have the
performance that can be put to practical use. .
[0010]
Patent Document 1: JP-A-2004-64726 Patent Document 2: JP-A-2002-78077 Patent Document
2: JP-A-11-512249
[0011]
The present invention is capable of efficiently generating a vibration waveform (sound),
suppressing attenuation of the vibration waveform and transmitting it to a distant place, and
suppressing reflection of sound to reduce reverberation, directivity and frequency characteristics.
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The purpose is to provide a speaker that is sufficiently improved in sound quality.
[0012]
In order to achieve the above object, the present invention is a diaphragm for a speaker,
comprising: a pair of sheets; and a honeycomb core of a hollow honeycomb structure sandwiched
between them and bonded so that the hollow portion is sealed, The present invention relates to a
speaker diaphragm, wherein a bending stress is applied to the speaker diaphragm.
[0013]
The inventor conducted intensive studies to achieve the above object.
As a result, at both ends of the hollow honeycomb core, while sandwiching the honeycomb core
and sealing the hollow portion of the honeycomb core to bond a pair of sheets, the vibration for a
speaker obtained in this way Bending stress is applied to the plate.
[0014]
In this case, since bending stress is generated in the diaphragm constituting the speaker
diaphragm, as described above, it is estimated that a transverse wave is generated from the
speaker diaphragm.
Therefore, the vibration waveform (sound) generated from the speaker diaphragm can be
transmitted to a long distance without being attenuated.
[0015]
In the speaker diaphragm, the diaphragm has a hollow honeycomb structure.
Since this honeycomb core is hollow, it is excellent in weight reduction and excellent in rigidity.
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Therefore, as in the case of a plate-like plastic or the like, the rigidity of the speaker diaphragm is
small and soft, and the speaker diaphragm can not follow the vibration of the vibrator. Absent.
That is, only the periphery of the vibrator vibrates, and most of the others can not obtain the
vibration at the required frequency, so that irrelevant noise is produced, or necessary noise is not
produced due to interference. It can be prevented.
[0016]
Furthermore, as in the case of a plate-like metal member, even if the diaphragm for the speaker
becomes too heavy and the vibrator tries to vibrate the diaphragm for the speaker, the inertial
force becomes too large. The speaker diaphragm can be prevented from being unable to follow
the vibration of the vibrator. As a result, it is possible to prevent the panel from being able to
reproduce only a partial frequency with respect to the vibration from the vibrator.
[0017]
That is, according to the present invention, a vibration waveform can be generated efficiently,
and attenuation of the vibration waveform can be suppressed and transmitted to a distant place.
[0018]
Further, as described above, since the speaker diaphragm is light in weight and excellent in
rigidity, the vibration waveform has little reflection even on a barrier such as a ceiling or a wall,
and the reverberation is extremely reduced. The sound quality such as frequency characteristics
will be excellent.
[0019]
The speaker of the present invention is characterized by including the above-mentioned
diaphragm for a speaker, and exhibits the same function and effect as the above-described
diaphragm for a speaker.
[0020]
As described above, according to the present invention, a vibration waveform (sound) can be
efficiently generated, attenuation of the vibration waveform can be suppressed and transmitted
to a long distance, and reflection of sound can be suppressed to reduce reverberation. It is
possible to provide a speaker in which sound quality such as directivity and frequency
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characteristics is sufficiently improved.
[0021]
It is a block diagram which shows an example of the diaphragm for speakers of this invention.
Similarly, it is a block diagram which shows an example of the diaphragm for speakers of this
invention.
It is a block diagram which shows an example of the speaker of this invention.
It is a block diagram which shows the other example of the speaker of this invention.
It is a block diagram which shows the other example of the speaker of this invention. It is a graph
which shows the relationship between a sound pressure level and the distance from a sound
source in an Example.
[0022]
Hereinafter, other features and advantages of the present invention will be described in detail
based on the best mode for carrying out the invention.
[0023]
(Honeycomb Core) The speaker diaphragm of the present invention has a honeycomb core of a
hollow honeycomb structure.
The honeycomb core contributes to weight reduction and high rigidity of the entire speaker
diaphragm because it is lightweight and highly rigid due to its structural features.
[0024]
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The honeycomb core can be made of at least one selected from the group consisting of organic
fiber non-woven fabric, thermosetting resin sheet and kraft paper.
[0025]
As the organic fiber non-woven fabric, an aramid non-woven fabric, a liquid crystal polymer nonwoven fabric or the like can be used.
For example, Metex (trade name) manufactured by DuPont can be used as the aramid non-woven
fabric, and Beculus (trade name) manufactured by Kuraray Co., Ltd. can be used as the liquid
crystal polymer non-woven fabric.
[0026]
The thermosetting resin sheet can be obtained, for example, by impregnating a glass woven
fabric with a thermosetting resin such as an epoxy resin. Furthermore, the said kraft paper can
use what is marketed.
[0027]
The hollow honeycomb structure can be formed by a known method. For example, a gas
generating agent is attached to the organic fiber non-woven fabric, a predetermined gas is
generated in the heating process in forming the diaphragm, and a hexagonal cavity caused by the
gas generation is formed in the non-woven fabric. can do. Examples of the gas generating agent
include sodium bicarbonate and the like.
[0028]
Further, the cell size of the honeycomb core is not particularly limited, and when the diaphragm
for a speaker including the honeycomb core is used as a speaker, it is appropriately adjusted to
have appropriate strength and weight. For example, when the thickness of the honeycomb core is
large, the cell size is increased, and when the thickness of the honeycomb core is small, the cell
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size is decreased.
[0029]
Furthermore, since the thickness of the honeycomb core characterizes the thickness of the
speaker diaphragm, the thickness is determined in such a range that the speaker diaphragm has
an appropriate thickness. For example, in the present invention, the thickness of the honeycomb
core can be 1.5 mm to 10 mm. This makes it possible to more effectively improve the directivity
and frequency characteristics of the diaphragm to be finally obtained.
[0030]
The thickness of the honeycomb core is preferably at least 15 times the thickness of the sheet
provided at the both ends described in detail below. If the thickness of the sheet is too large with
respect to the thickness of the honeycomb core, the obtained speaker diaphragm becomes a form
close to a simple plate, and the characteristics of weight reduction and high rigidity by providing
the honeycomb core May not be able to demonstrate enough. Therefore, it may not be possible to
obtain a high-characteristic diaphragm intended by the present invention.
[0031]
The upper limit of the thickness can be, for example, 100 times. Even if the thickness of the sheet
is increased beyond the upper limit value, only the size of the entire speaker diaphragm is
increased and does not contribute to the above-described effects.
[0032]
(Sheet) The speaker diaphragm of the present invention has a pair of sheets sandwiching the
honeycomb core at both end portions of the honeycomb core and sealing the hollow portion of
the honeycomb core.
[0033]
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The said sheet | seat which comprises the diaphragm for speakers of this invention can be
comprised from a glass woven fabric base-material epoxy resin sheet.
In this case, the honeycomb core and the glass woven fabric base epoxy resin sheet are formed
by bonding by heating and pressing with a hot press or an autoclave-type molding machine. Such
adhesion is carried out along with the heat curing of the epoxy resin constituting the sheet. In
addition, when adhesion | attachment is inadequate, an adhesive agent can be used suitably.
[0034]
The glass woven fabric base epoxy resin sheet can be formed, for example, by impregnating a
glass woven fabric with a thermosetting epoxy resin. The sheet obtained in this manner exhibits a
sufficiently high rigidity and can fully satisfy the effects of the present invention. However, the
sheet can also be formed in other ways. For example, it can also be obtained by sticking an epoxy
resin sheet on a glass fiber substrate.
[0035]
The glass woven fabric constituting the glass woven fabric base material needs to have
appropriate lightness and strength (rigidity), and the density thereof is 40 g / m <2> to 220 g /
m < 2> is preferable. Moreover, it is preferable that it is a plain weave structure. As such a glass
woven fabric, 106 type, 1080 type, 2116 type and 7628 type (all of which are IPC specifications)
used for building materials, printed wiring boards and the like can be used.
[0036]
Moreover, as an epoxy resin which comprises the said glass woven fabric base material epoxy
resin sheet, it will not be specifically limited if adhesive strength is obtained after hardening, The
epoxy resin used for a general industrial product is used be able to. Specifically, epoxy resins
such as bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, glycidyl ether
epoxy resin, alicyclic epoxy resin, and heterocyclic epoxy resin, and biphenyl skeleton are
included. Such polyfunctional epoxy resins can be used. These can be used alone or in
combination of two or more.
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[0037]
Furthermore, in the case of imparting the flame retardancy, an epoxy resin having a general
flame retardant mechanism such as a brominated epoxy resin, a phosphorus-modified epoxy
resin, or the like can also be used.
[0038]
In addition, when hardening the said epoxy resin, the hardening | curing agent for epoxy can be
used suitably.
As such curing agents for epoxy, general purpose ones can be used, and dicyandiamide, amine
curing system such as aromatic diamine, phenol novolac resin, cresol novolac resin, bisphenol A
novolac resin, triazine modified phenol novolac resin, etc. A phenol curing system etc. can be
used. These curing agents can be used alone or in combination of two or more.
[0039]
Moreover, in addition to the said hardening agent for epoxy, the hardening accelerator for epoxy
can also be used suitably. As such epoxy curing accelerators, general purpose ones can be used,
and imidazole compounds such as 2-ethyl-4-methylimidazole and 1-benzyl-2-methylimidazole,
boron trifluoride amine complex, triphenyl A phosphine etc. can be used. These curing
accelerators can be used alone or in combination of two or more.
[0040]
In addition to the above-mentioned curing agent and / or curing accelerator, fillers of inorganic
or organic fine powder, pigments, anti-deterioration agents, etc. can be added to the abovementioned epoxy resin as appropriate. .
[0041]
Furthermore, it is preferable that the content rate of the said epoxy resin in the said glass woven
fabric base epoxy resin sheet is 35 weight%-70 weight%.
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Also in this case, appropriate lightness and strength (rigidity) can be imparted to the sheet, and
the intended effects of the present invention can be sufficiently achieved.
[0042]
(Speaker Diaphragm) FIGS. 1 and 2 are configuration diagrams showing an example of a speaker
diaphragm of the present invention. FIG. 1 shows only the honeycomb core portion from which
the sheet is removed, and FIG. 2 shows the honeycomb core sandwiched between the sheets.
Fig.2 (a) is a top view of the said diaphragm, FIG.2 (b) is a side view of the said diaphragm.
[0043]
As shown in FIG. 1, in the present invention, the honeycomb core 11 has a honeycomb structure
in which hexagonal cells are densely packed, and as shown in FIG. It can be seen that the hollow
portion 11A of the honeycomb core 11 is sealed while being sandwiched by the cloth base epoxy
resin sheet 12 respectively.
[0044]
When the thickness of the honeycomb core 11 is t1 and the thickness of the resin sheet 12 is t2,
as described above, it is preferable to satisfy the relationship of t1 ≧ 15t2.
[0045]
According to the speaker diaphragm of the present invention, it is presumed that a transverse
wave is generated from the speaker diaphragm as described above by being fixed in a state
where a bending stress is applied, as described above. It is possible to obtain various effects.
[0046]
The magnitude of the bending stress is preferably in the range of 5% to 50% of the breaking limit
stress of the diaphragm.
If it is less than 5%, the magnitude of the bending stress is not sufficient, the generated
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transverse waves become small, and the effects of the present invention may not be sufficiently
exhibited.
On the other hand, if it exceeds 50%, the sheet, in this example, the resin sheet 12 may be broken
by bending stress.
[0047]
It is also confirmed that the directivity of sound can be changed by bending the diaphragm.
[0048]
Also, by increasing the number and area of the diaphragms, it is possible to efficiently generate a
broadband vibration waveform (sound).
[0049]
The bending stress described above can be preloaded on the diaphragm.
This loading method can be performed by a mechanical method.
Furthermore, as described below, when the speaker diaphragm is incorporated into a housing, a
compressive stress is applied from the housing to the diaphragm, thereby generating a bending
stress in the diaphragm. You can also.
[0050]
The above-described methods of applying bending stress can be used alone or in combination.
[0051]
(Speaker) FIG. 3 is a schematic block diagram of an example of the speaker of the present
invention.
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As shown in FIG. 3, in the speaker 20 of this example, the above-described speaker diaphragm 10
is fixed to the side walls 21A and 21B of the housing 21, and bolts and nuts 23 are provided
substantially at the center of the speaker diaphragm 10. The piezoelectric element 22 is fixed via.
Therefore, the vibration from the piezoelectric element 22 is transmitted to the speaker
diaphragm 10 through the bolt and nut 23, whereby the speaker diaphragm 10 is vibrated, and
the vibration waveform (sound) is propagated into the air to be the speaker 20 will play a
function as a speaker.
[0052]
At this time, it was estimated that a transverse wave was generated from the speaker diaphragm
10 due to the bending stress being applied to the sheet 12 of the speaker diaphragm 10 and
generated from the speaker diaphragm 10 The vibration waveform (sound) can be transmitted to
a distance without attenuation. Further, since the honeycomb core 11 is light in weight and high
in rigidity, the speaker diaphragm 10 follows the vibration of the piezoelectric element 22 even
when the vibration of the piezoelectric element 22 is loaded on the speaker diaphragm 10,
Furthermore, the frequency of vibration from the piezoelectric element 22 can be reproduced
with respect to the speaker diaphragm 10.
[0053]
In addition, even when the vibration waveform hits a barrier such as a ceiling or a wall, the
reflection is small, the reverberation is extremely small, and the sound quality such as directivity
and frequency characteristics is excellent.
[0054]
In addition, as shown in FIG. 3, compressive stress can be applied to the side surfaces 21A and
21B of the housing 21, and thereby, bending stress can be applied to the speaker diaphragm 10.
Similarly, when fixing with the bolt and nut 23, stress can be applied perpendicularly to the
speaker diaphragm 10, and bending stress can also be applied.
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[0055]
Therefore, even when bending stress is not applied to the diaphragm 10 in advance, the bending
stress can be applied in the process of forming the speaker 20 as shown in FIG. 3. However,
apply bending stress to the diaphragm 10 in advance, and additionally apply additional bending
stress when configuring the speaker 20 as described above, so that the above-described effects
can be obtained more easily. You can also.
[0056]
FIG. 4 is a schematic configuration view of another example of the speaker according to the
present invention, in which the speaker 30 is fixed to the side surfaces 21A and 21B of the
housing 21 with the two speaker diaphragms 10 separated from each other. And the speaker 20
shown in FIG.
[0057]
In the speaker 30 of this example, since the two speaker diaphragms 10 are used, the abovedescribed effects and effects of the speaker diaphragm 10 are more emphasized and exhibited as
compared with the speaker 20 in FIG. 3. Become.
[0058]
It is to be noted that bending stress can be applied to each sheet 12 of the speaker diaphragm 10
by stress load in the arrow direction due to compressive stress from the housing 21 as in the
above specific example.
[0059]
FIG. 5 is a schematic configuration diagram of another example of the speaker according to the
present invention, in which the speaker 40 separates the two speaker diaphragms 10 from each
other via the spacer 41 and fixes them by the bolt and nut 23. There is.
Further, the bolt and nut 23 connect the piezoelectric elements 22 to the speaker diaphragms 10
on the outer side of one of the speaker diaphragms 10.
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[0060]
Also in this example, since the speaker 40 uses the two speaker diaphragms 10, the abovedescribed effects of the speaker diaphragm 10 can be enhanced and exhibited as compared with
the speaker 20 in FIG. become.
[0061]
It is to be noted that bending stress can be applied to each of the sheets 12 of the speaker
diaphragm 10 by the stress load in the arrow direction by the bolt and nut 23, as in the above
specific example.
[0062]
EXAMPLES Hereinafter, the present invention will be specifically described based on examples,
but the present invention is not limited to these examples.
Further, "parts" in the following means "parts by weight".
[0063]
(Example 1) 70 parts of Epicoat 1001 (product name of Yuka Shell Co., Ltd.) of bisphenol A type
epoxy resin, 30 parts of cresol novolac epoxy resin YDCN-704P (product name of Toto Kasei Co.,
Ltd.), 3 parts of dicyandiamide propylene glycol Monomethyl ether was added to adjust the
varnish to a solid content of 65% by weight.
This resin was applied to a 7628 type (ICP grade) glass cloth with a resin content of 40% by
weight, dried, and semi-cured to prepare a prepreg for a glass woven fabric base epoxy resin
sheet.
[0064]
Next, a honeycomb core (made by Jamco, thickness 4 mm) obtained by impregnating nomex
paper with a phenol resin is prepared, and the prepreg is used to seal the hollow portion of the
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honeycomb core at both ends of the honeycomb core. And press for 65 minutes at a temperature
of 160 ° C. and a pressure of 2 kgf / cm <2> to heat and cure the prepreg to obtain a glass
woven fabric base epoxy resin sheet, and this sheet and the honeycomb core I was glued.
[0065]
The thickness of the honeycomb core after pressing is 4 mm, the thickness of the glass woven
fabric base epoxy resin sheet formed from the prepreg is 0.19 mm, and the thickness of the
honeycomb core is the glass woven fabric base It was about 21 times the thickness of the epoxy
resin sheet.
[0066]
Next, the laminate obtained by press-molding as described above is cut into 300 mm × 420 mm
to obtain a target diaphragm for a speaker, and a hole having a diameter of 3 mm is formed at
the center of each of the two speaker diaphragms. The location was fixed, and the two speaker
diaphragms were fixed so as to face each other at a distance of 10 mm with a bolt and a nut of 3
mm diameter acrylic resin.
At this time, a spacer is placed on the end of the two speaker diaphragms so that a bending load
of 15 N (a bending stress of 0.019 N / mm <2>) is applied to each speaker diaphragm. I made it.
Further, the breaking limit load of this speaker diaphragm was 78N breaking limit stress was
0.0621 N / mm <2>).
[0067]
Further, one or two piezoelectric elements PZT-PbO3 manufactured by Fuji Ceramics Co., Ltd.
were attached via the aforementioned bolts and nuts to obtain a speaker having the abovedescribed two speaker diaphragms and piezoelectric elements.
The results of the characteristic evaluation of the obtained speaker are shown in Table 1 and FIG.
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[0068]
Comparative Example 1 A speaker fixed without applying stress in Example 1 was produced.
The characteristics of the speaker were evaluated in the same manner, and the results are shown
in Table 1 and FIG.
[0069]
Comparative Example 2 Using a commercially available balsa plate with a thickness of 2.0 mm in
place of the honeycomb diaphragm in Example 1, the characteristics were evaluated using a
stress-fixed speaker, and the results are shown in Table 1. Indicated.
[0070]
(Comparative example 3) Instead of a honeycomb diaphragm in Example 1, using a 1.0 mm thick
aluminum plate, stress evaluation was performed using a fixed speaker, and the results are
shown in Table 1 .
[0071]
(-) Shows the case where it has not been measured.
[0072]
(Measuring method) 1) Reverberation time The reverberation time of the sound source at 250 to
8000 Hz was measured with a measuring instrument (Responsive Schecker RC-1 manufactured
by Japan Audio Co., Ltd.) in an anechoic chamber.
(Unit: 1/10 second) 2) Attenuation of sound pressure (i) At a frequency of 1000 to 10000 Hz
with a measuring instrument (Respons-speaker RC-1 manufactured by Japan Audio Corporation)
at a position 1 m or 4 m away from the speaker Sound pressure was measured.
3) Perceivable distance A speaker set at the same volume with a frequency of 4000 to 6000 Hz
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was installed outdoors to measure the limit distance that human can hear.
4) Attenuation of sound pressure (ii) The sound pressure at a frequency of 500 Hz was measured
by a measuring device at a position 0.5 m to 3.9 m away from the speaker in the anechoic
chamber. The following measuring instruments were used. Microphone: MI-1233 (Ono Sokki)
Microphone preamp: MI-3110 (Ono Sokki) Multi-channel data station: DS-2000 (Ono Sokki) Realtime octave Analysis software: DS-0223 (Ono Sokki)
[0073]
As is clear from Table 1 and FIG. 6, the loudspeaker obtained in the example has less
reverberation compared to the loudspeaker obtained in Comparative Example 1 and exhibits high
sound pressure (dB) to far, so far to far It can be seen that the vibration waveform (sound) can be
transmitted.
[0074]
As mentioned above, although the present invention was explained in detail based on the abovementioned example, the present invention is not limited to the above-mentioned example, and
various modification and change are possible unless it deviates from the category of the present
invention.
[0075]
Reference Signs List 10 diaphragm for speaker 11 honeycomb core 11A hollow portion of
honeycomb core 12 sheet t1 thickness of honeycomb core t2 thickness of sheet 20, 30, 40
speaker 21 housing 22 piezoelectric element 23 bolt / nut
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