JPWO2016013122

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DESCRIPTION JPWO2016013122
Abstract: The present invention provides a composite speaker device capable of suppressing the
disturbance of the sound emission characteristic caused by the propagation of sound from the
high-pitched speaker unit to the low-pitched speaker unit. In the composite speaker device (1),
the first speaker unit (10, 16) having the first diaphragm (11, 16a) and the sound radiation
direction (D1) of the first diaphragm (11, 16a) And a second speaker unit (20, 26) having a
second diaphragm (21, 26a) smaller in diameter than the first diaphragm (11, 16a) installed, the
first diaphragm A sound absorbing material (30, 35, 36, 51, 61) is disposed on the surface of the
sound radiating direction (D1) of (11, 16a) so as to surround the second diaphragm (21, 26a) It
is characterized by
Composite speaker device
[0001]
The present invention relates to a composite speaker device.
[0002]
Heretofore, there has been known a composite speaker apparatus provided with a bass speaker
unit having a large diameter diaphragm and a high sound speaker unit installed in the sound
radiation direction of the large diameter diaphragm and having a small diameter diaphragm. (See,
for example, Patent Document 1).
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In the composite speaker device described in Patent Document 1, the shielding structure in the
sound radiation direction of the bass speaker unit is reduced by using a thin metal rod made of a
nonmagnetic material as a holding structure of the high-tone speaker unit. Thereby, the
disturbance of the sound emission characteristic of the composite speaker device due to the
reflection and the diffraction of the sound from the bass speaker unit by such a shield is
suppressed.
[0003]
JP, 2008-263257, A
[0004]
Here, part of the sound from the high-pitched speaker unit sometimes propagates to the lowpitched speaker unit positioned in the opposite direction to the sound radiation direction by
diffraction or the like.
Such propagation of sound from the high-pitched speaker unit to the low-pitched speaker unit
may also cause disturbances in the sound emission characteristics of the composite speaker
apparatus. In the composite speaker device described in Patent Document 1, there is a problem
that no effective measures are taken against such disturbance of the sound radiation
characteristic caused by the propagation of sound as an example.
[0005]
Then, this invention makes it a subject to provide the compound speaker apparatus which can
suppress disorder of the sound radiation characteristic resulting from propagation of the sound
from the speaker unit for high sound to the speaker unit for bass.
[0006]
In order to solve the above-mentioned subject, in the invention described in Claim 1, a first
speaker unit having a first diaphragm, and the first speaker unit installed in the sound radiation
direction of the first diaphragm. A second speaker unit having a second diaphragm having a
diameter smaller than the diameter of the first diaphragm, and sound absorption is performed on
the surface of the first diaphragm in the sound radiation direction so as to surround the second
diaphragm A composite speaker device is characterized in that a material is disposed.
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[0007]
It is a figure which shows the compound speaker apparatus concerning one Example of this
invention.
The sound propagated and reflected from the high sound speaker unit (second speaker unit)
shown in FIG. 1 to the bass speaker unit (first speaker unit) and the high sound speaker unit
(second speaker unit) Is a diagram showing how to measure the sound emitted from.
It is a figure which shows a mode that disorder of the sound radiation characteristic in the
composite speaker apparatus shown by FIG. 1 is suppressed by a sound absorbing material. FIG.
6 is a schematic view showing a bass speaker unit and a treble speaker unit as another example
of the first speaker unit and the second speaker unit according to the present invention. It is a
schematic diagram which shows the sound absorbing material of another example. It is a figure
which shows the phenomenon which arises when two sounds of equal frequency shift and
overlap mutually. It is a figure which shows the compound speaker apparatus of another example
which arrange ¦ positioned the sound absorbing material in the position away from the opening
of the diaphragm for basses. It is a figure which shows the composite speaker apparatus of
another example which arrange ¦ positions a sound absorbing material in the position away from
the opening of the diaphragm for basses.
[0008]
Hereinafter, a composite speaker device according to an embodiment of the present invention
will be described. A composite speaker device according to an embodiment of the present
invention has a first speaker unit having a first diaphragm, and a diameter smaller than that of
the first diaphragm installed in the sound radiation direction of the first diaphragm. A second
speaker unit having a second diaphragm, and a sound absorbing material is disposed on the
surface of the first diaphragm in the sound radiation direction so as to surround the second
diaphragm. I assume. In this composite speaker device, the first speaker unit functions as a bass
speaker unit, and the second speaker unit functions as a treble speaker unit. In this composite
speaker device, a sound absorbing material is disposed on the surface of the first diaphragm in
the sound radiation direction so as to surround the second diaphragm. For this reason, even if
the sound from the second speaker unit as the high-sound speaker unit propagates to the first
speaker unit as the low-sound speaker unit, the sound is absorbed by the sound absorbing
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material. According to this composite speaker device, it is possible to suppress the disturbance of
the sound emission characteristic caused by the propagation of the sound from the high sound
speaker unit to the low sound speaker unit by the sound absorption by the sound absorbing
material. Further, according to this composite speaker device, the arrangement of the sound
absorbing material on the surface of the first diaphragm in the sound radiation direction, which
is relatively low in material cost and manufacturing cost, suppresses the disturbance of the sound
radiation characteristics. be able to. Further, in the composite speaker device, the sound
absorbing material is disposed on the surface of the first diaphragm in the sound radiation
direction, and the space in the first diaphragm is free from foreign matter, and the appearance is
also favorable. It has become.
[0009]
Further, in the composite speaker device according to the embodiment of the present invention,
it is preferable that the axis of the first speaker unit and the axis of the second speaker unit
coincide with each other. According to this composite speaker device, since high and low tones
can be heard from substantially the same position, a good sound image can be obtained.
[0010]
Further, in this preferred composite speaker device, it is more preferable that the sound
absorbing material has an annular shape. According to this composite speaker device, the sound
propagating from the second speaker unit to the first speaker unit can be evenly absorbed
around the axis of the second speaker unit by the annular sound absorbing material. Therefore,
the disturbance of the sound radiation characteristic is further suppressed.
[0011]
Further, in the above preferred composite speaker apparatus in which the axes of the two
speaker units coincide with each other, an opening is formed at the central portion of the first
diaphragm, and the diameter of the second diaphragm is greater than the diameter of the
opening. It is further preferred that the size is small. According to this composite speaker device,
the situation that the second diaphragm becomes a shield in the sound radiation direction of the
first diaphragm is avoided.
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[0012]
In the above preferred composite speaker device, in which the opening is formed at the center of
the first diaphragm and the diameter of the second diaphragm is smaller than the diameter of the
opening, the sound absorbing material is disposed around the opening Is more preferred.
According to this composite speaker device, since the sound absorbing material is disposed
around the opening, which is relatively inconspicuous when viewed from the sound radiation
direction, the appearance can be improved.
[0013]
Further, in the composite speaker device according to one embodiment of the present invention,
the wavelength corresponding to the overlapping frequency that is the frequency of the sound
radiated at the same frequency from both the first speaker unit and the second speaker unit is λ.
When the natural number is represented by n, the surface of the first diaphragm in the sound
radiation direction from the surface of the second diaphragm in the sound radiation direction to
the surface of the first diaphragm in the sound radiation direction The propagation path
difference between the propagation path of the propagated and reflected sound and the
propagation path of the sound radiated from the surface in the sound radiation direction of the
second diaphragm is (2n + 1) × λ (1/2 ± 1) It is preferable that the sound absorbing material
be disposed in at least one location within the installation range including the location where the
position of the sound absorbing material is the position of the point 16 . In the above
installation range, the overlap frequency sound from the second speaker unit propagates from
the surface in the sound radiation direction of the second diaphragm to the surface in the sound
radiation direction of the first diaphragm and is reflected It overlaps with the sound of the
frequency in the state where it is shifted about half wavelength. This state means that the phase
shift is close to 180 °, and the two sounds interfere with each other to cancel each other, and
the sound pressure is easily reduced. According to the preferred composite speaker device
described above, by limiting the location of the sound absorbing material to a position where
such a sound pressure drop is likely to occur, the load on the first diaphragm can be reduced by
reducing the amount of the sound absorbing material used. While suppressing, the sound
pressure drop can be suppressed to suppress the disturbance of the sound emission
characteristics.
[0014]
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Further, in the preferred composite speaker device, of the surface of the first diaphragm in the
sound radiation direction, the length of the propagation path difference is (2n + 1) × λ (1 / 2-1
/ 16) to ((1) It is further preferable that the sound absorbing material be disposed at least at one
place within the range of 2n + 1) × λ (1/2 + 1/16). According to this composite speaker device,
the amount of use of the sound absorbing material is further suppressed by limiting the location
of the sound absorbing material to a position where the phase shift in the sounds of overlapping
frequencies that interfere with each other is closer to 180 °. The disturbance of the
characteristics can be suppressed.
[0015]
Further, in the further preferable composite speaker device, at least in the vicinity of a portion
where the length of the propagation path difference is (2n + 1) × λ (1/2) on the surface in the
sound radiation direction of the first diaphragm. It is more preferable that the sound absorbing
material is disposed at one place. According to this composite speaker device, by limiting the
location of the sound absorbing material to a position where the phase shift in the sound of
overlapping frequencies that interfere with each other is approximately 180 °, the usage
amount of the sound absorbing material is further suppressed and the sound emission
characteristics Can be suppressed.
[0016]
Further, in the above preferred composite speaker device in which the sound absorbing material
is disposed at at least one location near the location where the length of the propagation path
difference is (2n + 1) × λ (1/2), the above natural number n It is more preferable that is zero.
According to this composite speaker device, even if there are a plurality of locations where the
propagation path difference has a length of (2n + 1) × λ (1/2), there is a location near the
location closest to the second diaphragm among them. A sound absorbing material is placed. For
this reason, it is possible to dispose the sound absorbing material at a suitable position even in a
small-sized composite speaker device.
[0017]
A composite speaker device 1 according to an embodiment of the present invention will be
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described with reference to FIGS. 1 to 3. FIG. 1 is a view showing a composite speaker apparatus
according to an embodiment of the present invention. FIG. 1A shows a cross-sectional view of the
composite speaker device 1 along the sound radiation direction. Further, FIG. 1B is a schematic
view when two diaphragms described later included in the composite speaker device 1 are
viewed from the direction of the arrow D2 in FIG. 1A.
[0018]
The composite speaker device 1 includes a bass speaker unit 10 and a treble speaker unit 20.
The bass speaker unit 10 corresponds to an example of the first speaker unit according to the
present invention, and the high-sound speaker unit 20 corresponds to an example of the second
speaker unit according to the present invention.
[0019]
The bass speaker unit 10 includes a bass diaphragm 11, a bass frame 12, a bass damper 13, a
bass voice coil 14, and a bass magnetic circuit 15. The low frequency diaphragm 11 is a member
having a cone shape, and an opening 11 a is formed in the center thereof. The outer peripheral
edge of the bass diaphragm 11 is connected to the cylindrical bass frame 12, and the inner
peripheral edge of the opening 11a in the bass diaphragm 11 is connected to the cylindrical
voice coil bobbin 14a. The bass damper 13 is a flexible annular member having an outer
peripheral edge connected to the bass frame 12 and an inner peripheral edge connected to the
outer peripheral surface of the voice coil bobbin 14a. The bass voice coil 14 is formed on the
outer peripheral surface of the voice coil bobbin 14 a, and is disposed in the magnetic gap 15 a
of the bass magnetic circuit 15. The low frequency diaphragm 11 corresponds to an example of
the first diaphragm according to the present invention.
[0020]
The high-pitched speaker unit 20 is disposed inside the voice coil bobbin 14 a of the low-pitched
speaker unit 10. The high sound diaphragm 21, the high sound frame 22, the high sound damper
23, the high sound voice coil 24, and the high magnetic circuit 25 are provided. The high-tone
diaphragm 21 is a member provided in the sound radiation direction D1 of the low-pitch
diaphragm 11 and having a dome shape having a diameter smaller than that of the low-pitch
diaphragm 11. Furthermore, the outer diameter of the high-tone diaphragm 21 is smaller than
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the inner diameter of the voice coil bobbin 14 a in the bass speaker unit 10, that is, the inner
diameter of the opening 11 a in the bass diaphragm 11. The outer peripheral edge of the high
sound diaphragm 21 is connected to a cylindrical high sound frame 22. Further, the back surface
of the high sound diaphragm 21 opposite to the sound radiation direction D1 is connected to the
upper edge of the cylindrical voice coil bobbin 24a. Further, the high sound damper 23 is a
flexible annular member, the outer peripheral edge is connected to the high sound frame 22, and
the inner peripheral edge is connected to the outer peripheral surface of the voice coil bobbin
24a. The high-tone voice coil 24 is formed on the outer peripheral surface of the voice coil
bobbin 24 a, and is disposed in the magnetic gap 25 a of the high-tone magnetic circuit 25. The
high-tone diaphragm 21 corresponds to an example of the second diaphragm according to the
present invention.
[0021]
Of the audio signal supplied to the composite speaker device 1, the bass component is supplied
to the bass voice coil 14 in the bass speaker unit 10, and the treble component is supplied to the
treble voice coil 24 in the treble speaker unit 20. As a result, each voice coil vibrates due to
Lorentz force acting on each voice coil from each magnetic circuit, and the vibration is
transmitted to each diaphragm. As a result, the bass diaphragm 11 in the bass speaker unit 10
emits a bass sound in the sound radiation direction D1, and the treble diaphragm 21 in the treble
speaker unit 20 generates a treble sound in the sound radiation direction D1. Radiate. In the
composite speaker device 1, the tone range is expanded by having the two speakers handle the
low tone range and the high tone range as described above.
[0022]
Here, part of the sound radiated by the high-tone diaphragm 21 in the sound radiation direction
D1 in the high-tone speaker unit 20 exceeds the upper edge of the high-tone frame 22 due to
diffraction or the like and is used for the low-tone speaker unit 10 It propagates to the surface of
the diaphragm 11.
[0023]
Further, in the composite speaker device 1, the high range of the sound emitted by the lowfrequency speaker unit 10 and the low range of the sound emitted by the high-sound speaker
unit 20 partially overlap.
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In such a sound range, sounds of the same frequency are emitted from both of the bass speaker
unit 10 and the treble speaker unit 20. The range of frequencies at which the frequencies of the
sounds radiated from the two speaker units overlap is referred to herein as overlapping
frequency. One frequency in the range of this overlapping frequency is the crossover frequency.
[0024]
At such an overlapping frequency, the sound transmitted from the surface of the sound radiation
direction D1 of the high-tone diaphragm 21 to the surface of the sound radiation direction D1 of
the low-pitch diaphragm 11 is reflected on the surface of the low-pitch diaphragm 11. When the
sound of the overlapping frequency is transmitted to the bass diaphragm 11, the bass diaphragm
11 vibrates at the same frequency by the energy of a part of the sound wave, so the bass
diaphragm 11 can be regarded as a free end. The above reflection is the reflection associated
with the free end of the overlap frequency sound. Therefore, the sound of the overlap frequency
from the high-tone diaphragm 21 does not have a phase shift due to the reflection on the lowpitch diaphragm 11. Therefore, it is sufficient to consider only the phase shift due to the
propagation path difference described later.
[0025]
This reflected wave interferes with the sound emitted by the high-tone diaphragm 21. Then,
depending on the phase shift between the two sounds, the interference between the two sounds
cancels each other to reduce the sound pressure, and the sound emission characteristics of the
composite speaker device 1 may be disturbed. In the composite speaker device 1 of the present
embodiment, in order to suppress such disturbance of the sound radiation characteristics, a circle
is formed so that the high sound diaphragm 21 is surrounded on the surface of the sound
radiation direction D1 of the low sound diaphragm 11 in a single layer. An annular sound
absorbing material 30 is disposed at one place. Even if the sound from the high-pitched speaker
unit 20 propagates to the low-pitched speaker unit 10, the sound is absorbed by the sound
absorbing material 30. According to this composite speaker device 1, it is possible to suppress
the disturbance of the sound emission characteristic caused by the propagation of the sound
from the high sound speaker unit 20 to the low sound speaker unit 10 by the sound absorption
by the sound absorbing material 30. The sound absorbing material 30 corresponds to an
example of the sound absorbing material in the present invention.
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[0026]
FIG. 2 shows how to measure the characteristics of the sound propagated and reflected from the
high-tone diaphragm 21 shown in FIG. 1 to the low-pitch diaphragm 11 and the sound radiated
from the high-tone diaphragm 21. FIG. The propagation path difference R is the difference
between the propagation path of the reflected sound wave and the propagation path of the sound
wave from the high-tone diaphragm 21. The propagation path difference R in FIG. 2 is a
propagation path Ra from the treble diaphragm 21 to the surface of the bass diaphragm 11 and a
propagation path Rb from the surface of the bass diaphragm 11 to the same height as the treble
diaphragm 21. Is the sum of
[0027]
The measurement of the characteristics of the speaker device is generally performed by the
microphone 70 one meter away from the high-tone diaphragm 21 on the axis of the speaker
device. In the present embodiment, since the diameter of the low frequency diaphragm 11 is
sufficiently smaller than 1 m, Rb is approximately defined as the propagation path up to the
same height as the high frequency diaphragm 21 as described above. The propagation path Rb is
from the surface of the low-pitch diaphragm 11 to the circumference of a circle with a radius of
1 m centered on the microphone 70.
[0028]
FIG. 3 is a view showing a state in which the disturbance of the sound radiation characteristic in
the composite speaker device shown in FIG. 1 is suppressed by the sound absorbing material. In
FIG. 3, a graph G3 representing an example of the sound radiation characteristic of the composite
speaker device 1 is shown. In this graph G3, the frequency (Hz) of sound is taken on the
horizontal axis, and the sound pressure (dB) is taken on the vertical axis. And an example of a
sound radiation characteristic in compound speaker device 1 shown in Drawing 1 is indicated by
thick line L1, and an example of a sound radiation characteristic in case sound absorption
material 30 is not provided for comparison is indicated by thin line L2 ing. The sound emission
characteristics of the thin line L2 are measured by the measurement method shown in FIG. 2, and
the sound emission characteristics of the thick line L1 are the same as FIG. 2 for the composite
speaker device 1 shown in FIG. It was measured by the measurement method of
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[0029]
In the example of FIG. 3, frequencies near 4 kHz are overlapping frequencies. Then, as indicated
by the thin line L2, when the sound absorbing material 30 is not provided, the sound pressure is
sharply reduced at this overlapping frequency. This is because the sound of the overlapping
frequency propagated from the high-sound speaker unit 20 and the low-sound diaphragm 11 of
the low-sound speaker unit 10 are reflected in the high sound pressure region H1 in the sound
pressure distribution diagram G1 of FIG. It is considered that the noises of the same frequency
interfere with each other and cancel each other.
[0030]
On the other hand, in the composite speaker device 1 of the present embodiment in which the
sound absorbing material 30 is provided, the sound of the overlapping frequency from the high
sound speaker unit 20 is absorbed by the sound absorbing material 30 on the low sound
diaphragm 11 of the low sound speaker unit 10 Be done. As a result, as indicated by the thick
line L1, the sound pressure drop at the overlapping frequency is suppressed. As described above,
according to the composite speaker device 1 of the present embodiment, the disturbance of the
sound radiation characteristic caused by the propagation of the sound from the high-sound
speaker unit 20 to the low-sound diaphragm 11 of the low-sound speaker unit 10 is absorbed by
the sound absorbing material. This can be suppressed by the sound absorption at 30. Further,
according to this composite speaker device 1, the arrangement of the sound absorbing material
30 on the surface of the sound radiating direction D 1 of the low-pitch diaphragm 11, the
material cost and the manufacturing cost are relatively small, and the sound radiation
characteristic is disturbed. Can be suppressed. Further, in the composite speaker device 1, the
sound absorbing material 30 is disposed on the surface of the sound radiation direction D1 of the
low frequency diaphragm 11, and no foreign matter is present in the space of the sound
radiation direction D1 of the low frequency diaphragm 11. The appearance is also good.
[0031]
Further, the sound from the high-sound speaker unit 20 reaches the surface of the low-sound
diaphragm 11 of the low-sound speaker unit 10 and interferes with the sound radiated from the
low-sound speaker unit 10 to disturb the sound radiation characteristics as a speaker device
There is sex. In the composite speaker device 1 of the present embodiment, such interference is
suppressed by the sound absorption of the sound absorbing material 30, so that the disturbance
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of the sound emission characteristic as the speaker device can also be suppressed.
[0032]
Further, in the composite speaker device 1 of the present embodiment, as shown in FIG. 1A, the
axis of the bass speaker unit 10 and the axis of the treble speaker unit 20 coincide with each
other. According to this composite speaker device 1, since high and low tones can be heard from
substantially the same position, a good sound image can be obtained.
[0033]
Further, in the composite speaker device 1 of the present embodiment, the sound absorbing
material 30 has an annular shape surrounding the high sound diaphragm 21 as shown in FIG. 1
(b). According to the composite speaker device 1, the sound propagating from the high-sound
speaker unit 20 to the bass speaker unit 10 is evenly absorbed around the axis of the high-sound
speaker unit 20 by the annular sound absorbing material 30. Can. Thereby, the disturbance of
the sound radiation characteristic is further suppressed.
[0034]
In the present embodiment, the bass speaker unit 10 and the treble speaker unit 20 whose axes
coincide with each other are illustrated as an example of the first speaker unit and the second
speaker unit according to the present invention. However, the first speaker unit and the second
speaker unit according to the present invention are not limited to this, and may be another
example as follows.
[0035]
FIG. 4 is a schematic view showing a bass speaker unit and a treble speaker unit as another
example of the first speaker unit and the second speaker unit according to the present invention.
In FIG. 4, the low-pitched speaker unit 16 and the high-pitched speaker unit 26 are another
schematic example of the low-pitched diaphragm 16a and the high-pitched diaphragm 26a
viewed from the sound radiation side as in FIG. Is shown in plan view. In FIG. 4, the components
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other than the diaphragms are not shown.
[0036]
In this low-pitched speaker unit 16 and the high-pitched speaker unit 26, the axes are offset from
each other. Further, an annular sound absorbing material 35 is disposed on the surface of the
low-frequency diaphragm 16a so as to surround the high-tone speaker unit 26 at a position off
axis with respect to the low-frequency speaker unit 11. In this alternative example, since the bass
and treble are heard from a position slightly offset from each other, they are slightly inferior in
sound image compared to the composite speaker device 1 of the present embodiment shown in
FIG. The area is the same as that of the composite speaker device 1 of this embodiment. Also in
this another example, the sound propagating from the high-tone speaker unit 20 can be absorbed
by the sound absorbing material 35 to suppress the disturbance of the sound emission
characteristics. The sound absorbing material 35 of this other example also corresponds to an
example of the sound absorbing material in the present invention.
[0037]
Moreover, although the annular sound absorbing material 30 is illustrated as an example of the
sound absorbing material said to this invention in a present Example, the sound absorbing
material said to this invention is not restricted to this. The sound absorbing material referred to
in the present invention may be, for example, another example as follows.
[0038]
FIG. 5 is a schematic view showing another sound absorbing material. In FIG. 5, another sound
absorbing material 36 is shown in a schematic plan view seen from the sound radiation side as in
FIG. 1 (b). The sound absorbing material 36 of this another example surrounds the high-tone
diaphragm 21 in a partially broken state. Although the sound absorbing material 36 of this
example is slightly inferior to the sound absorbing material 30 of the present embodiment shown
in FIG. 1, the sound propagating from the high sound speaker unit 20 is absorbed to disturb the
sound radiation characteristics even with the sound absorbing material 36 of this example. Can
be reduced. The sound absorbing material 36 of this other example also corresponds to an
example of the sound absorbing material in the present invention.
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[0039]
Further, in the composite speaker device 1 of the present embodiment shown in FIG. 1, the
opening 11a is formed at the central portion of the bass diaphragm 11, and the diameter of the
treble diaphragm 21 is smaller than the diameter of the opening 11a. It has become. According
to this composite speaker device 1, the situation where the high-tone diaphragm 21 becomes a
shield in the sound radiation direction D <b> 1 of the low-pitch diaphragm 11 is avoided.
[0040]
Further, in the composite speaker device 1 of the present embodiment, the sound absorbing
material 30 is disposed around the opening 11 a of the low frequency diaphragm 11. More
specifically, the sound absorbing material 30 is disposed in the vicinity of the inner peripheral
edge of the opening 11 a along the inner peripheral edge. According to this composite speaker
device 1, the sound absorbing material 30 is disposed at a position that is relatively
inconspicuous when viewed in the sound radiation direction D1, so the appearance is improved.
[0041]
Here, in the graph G3 of FIG. 3, the decrease in sound pressure at the overlapping frequency
(near 4 kHz) described with reference to the thin line L2 representing the sound radiation
characteristic when there is no sound absorbing material 30 is as follows: It is easy to get up.
That is, the propagation path of the sound propagated from the high-sound speaker unit 20 and
reflected on the surface of the low-sound diaphragm 11 of the low-sound speaker unit 10 and
the propagation path of the sound radiated from the surface in the sound radiation direction of
the high-sound diaphragm 21 This is apt to occur when the difference in the sound path between
the overlapping frequencies is shifted by about a half wavelength. In this case, the phase shift of
the two sounds is close to 180 °, and the two interfere with each other and cancel each other, so
that the sound pressure is easily reduced.
[0042]
Therefore, in the present embodiment, the sound absorbing material 30 is disposed at one place
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in the following installation range Ar1 on the surface in the sound radiation direction of the low
frequency diaphragm 11. In this installation range Ar1, a propagation route difference R1 of a
sound propagating from the surface of the high-sound diaphragm 21 in the sound radiation
direction D1 to the surface of the low-sound diaphragm 11 in the sound radiation direction D1 is
represented by It is a range that includes the part where the RL1 = (2n + 1) × λ (1/2 ± 1/16)
(1) In the equation (1), λ is a wavelength corresponding to the overlap frequency, and n
is a natural number.
[0043]
Furthermore, the sound absorbing material 30 has a length RL1 of the propagation path
difference R1 of (2n + 1) × λ (1 / 2-1 / 16) to (2n + 1) × λ (1/2 + 1) within the above
installation range Ar1. / 16) is disposed within the range Ar2.
[0044]
The position where the length RL1 of the propagation path difference R1 is (2n + 1) × λ (1/2)
is the sound of the overlap frequency from the high sound speaker unit 20 and the sound of the
overlap frequency emitted by the low frequency speaker unit 10 Is a position where they overlap
with just a half wavelength shift.
[0045]
FIG. 6 is a diagram showing a phenomenon that occurs when two sounds having the same
frequency overlap and overlap with each other.
FIG. 6 (a) shows a graph G4 representing a phenomenon that occurs when two sounds overlap
with a half wavelength shift, and FIG. 6 (b) shows two sounds (1/2- 1/16) A graph G5 is shown
which represents a phenomenon that occurs when wavelength shifts overlap.
Further, FIG. 6 (c) shows a graph G6 representing a phenomenon that occurs when two sounds
overlap with a shift of (1 / 2-1 / 8) wavelength. In each graph, time is taken on the horizontal
axis, and normalized amplitude is taken on the vertical axis.
[0046]
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In the graph G4 of FIG. 6A, the first sound is indicated by the dotted line L2, and the second
sound overlapping the first sound by a half wavelength is indicated by the alternate long and
short dash line L3. The sound is indicated by a solid line L4. Also, in this example, it is assumed
that the amplitudes of the two sounds are equal. As described above, when the two sounds
overlap by a half wavelength shift, the phase shift of the two sounds is 180 ° and the two cancel
each other out the most. As a result, the amplitude of the synthesized sound becomes almost
zero.
[0047]
In the graph G5 of FIG. 6B, the second sound overlapping the first sound indicated by the dotted
line L2 by (1 / 2-1 / 16) wavelength shift is indicated by the alternate long and short dash line
L5. Is indicated by a solid line L6. Also here, the amplitudes of the two sounds are assumed to be
equal. Even in such a state, the phase shift between the two sounds is close to 180 °, and the
two sounds cancel each other until the amplitude of the synthesized sound becomes about 1/2 or
less.
[0048]
In the graph G6 of FIG. 6C, the second sound overlapping the first sound indicated by the dotted
line L2 by (1 / 2-1 / 8) wavelength is indicated by the alternate long and short dash line L7. Is
indicated by a solid line L8. Also here, the amplitudes of the two sounds are assumed to be equal.
In this state, the phase shift of the two sounds is far from 180 °, and the amplitude of the
synthesized sound is not attenuated so much.
[0049]
The above equation (1) indicates that the propagation path difference R1 has a length RL1 of at
least the phase shift of the two sounds close to 180 ° to the extent shown in FIG. 6 (b). I mean.
Further, in the present embodiment, the sound absorbing material 30 is disposed within the
above-described range Ar2 in which the length RL1 of the propagation path difference R1 is such
a length. That is, the former sound is within the range Ar2 where the phase shift between the
sound of the overlap frequency from the high sound speaker unit 20 and the sound reflected on
the surface of the low sound diaphragm 11 of the low sound speaker unit 10 is close to 180 °. A
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sound absorbing material 30 that absorbs sound is disposed. More specifically, in the vicinity of
the portion where the length RL1 of the propagation path difference R1 is (2n + 1) × λ (1/2)
when the natural number n = 0, ie, in the vicinity of the portion where λ (1/2) A sound
absorbing material 30 is disposed.
[0050]
As a specific numerical example, when the overlapping frequency is 4 kHz and the sound velocity
is 340 m / sec, the wavelength λ corresponding to the overlapping frequency is 85 mm.
Assuming that n = 0, the length RL1 of the propagation path difference R1 represented by the
equation (1) is 42.5 ± 5.3 mm. In the present embodiment, the overlap frequency is 4 kHz. In
addition, as shown in FIG. 1A, the propagation path difference R1 extends substantially
horizontally from the top of the dome-shaped high-tone diaphragm 21 and, in the vicinity of the
upper edge of the high-tone frame 22, vibration for bass The path between the plate 11 bent to
the opening 11a side and the path to the surface of the low-pitch diaphragm 11 and the path
reflected by the surface of the high-tone diaphragm 21 to the same height as the first diaphragm
. The sound absorbing material 30 is disposed at a position where the length RL1 of the
propagation path difference R1 is 41.8 mm. This position corresponds to the vicinity of a point
where the length RL1 of the propagation path difference R1 is λ (1/2) = 42.5 mm. The
propagation path difference R1 corresponds to an example of the propagation path difference in
the present invention.
[0051]
In the present embodiment, the propagation path difference R1 is at a position where the length
RL1 is 41.8 mm, and for improving the appearance, along the inner peripheral edge near the
inner peripheral edge of the opening 11a of the bass diaphragm 11 Sound absorbing material 30
is disposed. However, although slightly inferior in appearance, the sound absorbing material may
be disposed at the position which satisfies the above-mentioned conditions for the propagation
path difference at a position distant from the opening 11a of the bass diaphragm 11.
[0052]
FIG. 7 is a view showing another example of the composite speaker device in which the sound
absorbing material is disposed at a position away from the opening of the bass diaphragm. In
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FIG. 7, another composite speaker device 5 is shown in a cross-sectional view equivalent to the
cross-sectional view of FIG. 1 (a). However, in FIG. 7, only the right half in the figure is illustrated.
Further, the composite speaker device 5 of this another example is equivalent to the composite
speaker device 1 shown in FIG. 1 except for the location of the sound absorbing material 51. In
FIG. 7, components equivalent to the components shown in FIG. 1 are denoted by the same
reference numerals as those in FIG. 1, and the redundant description of the same components
will be omitted below.
[0053]
In the composite speaker device 5 of this another example, the propagation path R2 of the sound
from the treble diaphragm 21 of the treble speaker unit 20 extends substantially horizontally
from the apex of the dome-shaped treble diaphragm 21 and the treble frame 22 Through the
vicinity of the upper edge of the low-frequency sound board 11 to the surface of the lowfrequency diaphragm 11. However, unlike the propagation path difference R1 shown in FIG. 1A,
the propagation path R2 is a path directed to a point away from the opening 11a of the bass
diaphragm 11. In this example, the propagation path R2 is the propagation path difference.
[0054]
Then, the annular sound absorbing material 51 is located near the portion where the length RL2
of the propagation path difference R2 is λ (1/2) = 42.5 mm (for example, a position where RL2 =
41.8 mm). It is arranged in one place. Also by the sound absorbing material 51 disposed at this
position, the sound transmitted from the high-pitched speaker unit 20 and the phase shift from
the sound of the overlapping frequency from the low-pitched speaker unit 10 becomes close to
180 ° is absorbed. As a result, the disturbance of the sound emission characteristic is
suppressed even in the composite speaker device 5 of this another example. The sound
absorbing material 51 in this another example also corresponds to an example of the sound
absorbing material in the present invention. Further, the propagation path difference R2 in this
another example also corresponds to an example of the propagation path difference in the
present invention.
[0055]
FIG. 8 is a view showing still another example composite speaker device in which the sound
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absorbing material is disposed at a position away from the opening of the bass diaphragm. In
FIG. 8, a further alternative composite speaker device 6 is shown in a sectional view equivalent to
the sectional view of FIG. 1 (a). However, in FIG. 8 as well as FIG. 7 described above, only the
right half is illustrated. In addition, the composite speaker device 6 of another example is also
equivalent to the composite speaker device 1 shown in FIG. 1 except for the location of the sound
absorbing material 61. In FIG. 8, components equivalent to the components shown in FIG. 1 are
denoted by the same reference numerals as in FIG. 1, and duplicate explanations of the same
components will be omitted below.
[0056]
In the composite speaker device 6 of this further another example, the high-tone speaker unit 20
is provided so as to project in the sound radiation direction D1 more than the high-tone speaker
unit 20 shown in FIGS. 1 and 7. As a result, the propagation path difference R3 of the sound from
the high-pitched speaker unit 20 is slightly longer than the propagation path difference R1
shown in FIG. 1 or the propagation path difference R2 shown in FIG. The propagation path
difference R3 shown in FIG. 8 extends substantially horizontally from the top of the dome-shaped
high-tone diaphragm 21 and is directed to the opening 11a side of the low-tone diaphragm 11
near the upper edge of the high-tone frame 22. The path is bent to reach the surface of the low
frequency diaphragm 11. However, unlike the propagation path difference R1 shown in FIG. 1A,
the propagation path difference R3 is also a path directed from the opening 11a of the bass
diaphragm 11 to a place away from the opening 11a. Then, an annular sound absorbing material
61 is present in the vicinity of a portion where the length RL3 of such a propagation path
difference R3 is λ (1/2) = 42.5 mm (for example, a position where RL3 = 45.5 mm). It is
arranged in one place. Also by the sound absorbing material 61 disposed at this position, the
sound transmitted from the high-pitched speaker unit 20 and the phase shift from the sound of
the overlapping frequency from the low-pitched speaker unit 10 to 180 ° is absorbed. As a
result, the disturbance of the sound emission characteristic is suppressed even in the composite
speaker device 6 of this another example. The sound absorbing material 61 in this other example
also corresponds to an example of the sound absorbing material in the present invention.
Further, the propagation path difference R3 in this another example also corresponds to an
example of the propagation path difference in the present invention.
[0057]
As described above, according to the composite speaker device 1 of the present embodiment, the
sound absorbing material 30 is placed in the above installation range Ar1 in which the phase
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shift of the sound of the two overlapping frequencies is close to 180 ° and the sound pressure
drop easily occurs. Is arranged. As described above, by limiting the location of the sound
absorbing material 30 to such a position, the amount of use of the sound absorbing material 30
can be suppressed to suppress the load applied to the low frequency diaphragm 11, but the
sound pressure decrease can be suppressed. The disturbance of the radiation characteristic can
be suppressed.
[0058]
Further, in the composite speaker device 1 of the present embodiment, in the installation range
Ar1, the length RL1 of the propagation path difference R1 is (2n + 1) × λ (1 / 2−1 / 16) to (2n
+ 1) × λ The sound absorbing material 30 is disposed in the range Ar2 where (1/2 + 1/16) is
set. According to this composite speaker device 1, the amount of use of the sound absorbing
material 30 is further suppressed by limiting the position where the sound absorbing material 30
is disposed to a position where the phase shift in the sound of overlapping frequencies
interfering with each other approaches 180 ° further. Thus, the disturbance of sound emission
characteristics can be suppressed.
[0059]
Furthermore, in the composite speaker device 1 of the present embodiment, the sound absorbing
material 30 is disposed in the vicinity of a portion where the length RL1 of the propagation path
difference R1 is (2n + 1) × λ (1/2). According to this composite speaker device 1, the amount of
use of the sound absorbing material 30 is further suppressed by limiting the position where the
sound absorbing material 30 is disposed to a position where the phase shift in the sound of
overlapping frequencies interfering with each other is approximately 180 °. The disturbance of
the sound radiation characteristic can be suppressed.
[0060]
Further, in the composite speaker device 1 of the present embodiment, the sound absorbing
material 30 is disposed in the vicinity of the position where the natural number n is 0, ie, the
portion where the length RL1 of the propagation path difference R1 is λ (1/2). It is done. That
is, the sound absorbing material 30 is disposed in the vicinity of a portion closest to the hightone diaphragm 21 among the portions where the length RL1 of the propagation path difference
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R1 is (2n + 1) × λ (1/2). In the present embodiment, although the specific size of the composite
speaker device 1 is not specified, since the arrangement location of the sound absorbing material
30 is close to the high sound diaphragm 21 as described above, the composite speaker device 1
is small to some extent Even if it is, it is possible to arrange the sound absorbing material 30 at a
suitable position.
[0061]
The embodiments described above merely show typical forms of the present invention, and the
present invention is not limited to these embodiments. That is, those skilled in the art can carry
out various modifications without departing from the gist of the present invention in accordance
with conventionally known findings. As long as the configuration of the composite speaker device
of the present invention is provided even by such a modification, it is of course included in the
scope of the present invention.
[0062]
For example, in the embodiment described above, the sound absorbing materials 30, 35, 36, 51,
61 disposed at one place so as to surround the high sound diaphragm 21 in a single layer are
illustrated as an example of the sound absorbing material according to the present invention. ing.
However, the sound absorbing material according to the present invention is not limited to this,
and the sound absorbing material may be disposed at a plurality of places so as to surround the
high-tone diaphragm (second diaphragm) twice or more.
[0063]
In the embodiment described above, a cone type diaphragm (diaphragm 11 for bass) is
exemplified as an example of the first diaphragm according to the present invention, and a dome
type is exemplified as the second diaphragm according to the present invention. The diaphragm
(high frequency diaphragm 21) is illustrated. However, the first diaphragm and the second
diaphragm according to the present invention are not limited to the diaphragm of the above type,
and may be any of a cone type and a dome type.
[0064]
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1, 5 and 6 composite speaker devices 10, 16 bass speaker unit 11, 16a bass diaphragm 11a
opening 12 bass frame 13 bass damper 14 bass voice coil 15 bass magnetic circuit 20, 26 treble
speaker unit 21 , 26a treble diaphragm 22 treble frame 23 treble damper 24 treble voice coil 25
treble magnetic circuit 30, 35, 36, 51, 61 sound absorbing material
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