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JPH0556493

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JPH0556493
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
nondirectional speaker system in which a speaker unit is attached to a cylindrical casing, and in
particular, a nondirectional speaker system in which a bass reproduction unit and a treble
reproduction unit are arranged in a coaxial speaker shape. It is about
[0002]
2. Description of the Related Art Conventionally, as a nondirectional speaker in which a speaker
unit is attached to a cylindrical casing, as shown in FIG. 9, a large number of speaker units 32 are
attached to the circumferential side surface of a cylindrical casing 31. As shown in FIG. 10, there
is one in which the bass speaker unit 42 is mounted upside down on the top plate portion of the
cylindrical casing 41 and the radial horn speaker 44 is mounted on the upper portion thereof.
[0003]
However, in the speaker system shown in FIG. 9, there are a large number of sound sources
because a large number of speaker units 32 are arranged, and there is a drawback that
localization is not determined when listening at a short distance.
[0004]
On the other hand, in the speaker system shown in FIG. 10, since the magnetic circuit unit 43 of
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the low frequency speaker unit 42 functions as an equalizer of the horn in the radial horn
speaker 44, directivity is good only in the horizontal direction but considerably deteriorated in
the vertical direction. And there is a drawback that the directivity of vertical and horizontal can
not be balanced.
In addition, since the magnetic circuit unit 43 of the bass speaker unit 42 occupies a
considerably large position as a sound wave radiation resistor, there are disadvantages such as a
decrease in sound pressure level and disturbance of high frequency characteristics.
[0005]
An object of the present invention is to eliminate the drawbacks of the conventional nondirectional speaker provided with the above-described cylindrical casing, and to provide a nondirectional speaker system for sound field reproduction excellent in frequency characteristics
and localization.
[0006]
A nondirectional speaker system according to the present invention is a nondirectional speaker
system in which a speaker unit is attached to a cylindrical casing, wherein a bass reproduction
unit is provided at the upper opening of the cylindrical casing. A treble reproduction unit having
a dome diaphragm mounted coaxially with the upward attachment is disposed, and the treble
reproduction unit is provided with a holding case having a curved surface having a surface
extending outward from the dome diaphragm, and the above dome vibration A reflector having
the same curved surface as the curved surface of the holding case is disposed to face the plate,
and the curved surface of the holding housing and the curved surface of the reflector form a
horn shape.
When attaching a high-sound radiation unit composed of a high-tone reproduction unit and a
reflector, the attachment pole is extended from the center pole in the magnetic circuit unit of the
bass speaker unit and supported by this attachment pole like a conventional coaxial speaker
However, if the diameter of the center pole is small, there is concern about strength, and in such
a case, it can be held in a bridge structure by the bridge leg member whose one end is fixed to
the cylindrical casing side. .
In the case of such a bridge structure, the wiring material of the high-pitched sound reproducing
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portion can be wired in the bridge leg member. Also, the treble reproduction unit may be
disposed on the front side of the bass reproduction unit and the reflector may be disposed on the
front side thereof, or the treble reproduction unit is disposed upside down so as to face the bass
reproduction unit. The reflector may be disposed between the cone diaphragm of the bass
reproduction unit and the dome diaphragm of the treble reproduction unit. A hemispherical
protrusion having the same shape as the dome diaphragm is projected on the surface of the
reflector so that the dome diaphragm and the hemispherical protrusion are closely opposed to
each other, and the horn shape can be made symmetrical. As a reflector, this can be made into a
hollow molded body, and the back side of a holding housing or a reflector can be formed with a
foam. When the sound absorbing material is disposed in the cylindrical casing, the acoustic
impedance ratio of the sound absorbing material is adjusted to be 0.5 to 3. As the cylindrical
casing, the outermost periphery can be a circle and the internal thickness can be partially
different, whereby extreme peaks do not occur in the vibration rising characteristics of the
casing. The bridge pier member may be a separate member such as a metal pipe or the like, but
may be integrally formed of a synthetic resin with the holding housing or the reflector.
[0007]
[Operation] The high-tone radiation portion composed of the high-tone reproduction portion and
the reflector has a horn shape formed by the holding case and the reflector so that the reflected
sound is synthesized. Therefore, the apex of the dome diaphragm of the high-tone reproduction
portion Can be regarded as a point sound source whose power is doubled, and in the case of a
short horn opening, a spherical wave can be propagated at 360 ° in the horizontal plane and in
the direction of the horn opening angle. Since the low-frequency regeneration unit is installed at
the opening with a small mounting area of the cylindrical casing, the influence of diffraction is
extremely small, and the spherical wave propagates without being separated by the casing. In
addition, since the sound source axes of the treble reproduction unit and the bass reproduction
unit are the same and the sound source center is close, the speaker system has a good balance of
horizontal and vertical directivity.
[0008]
Embodiment 1 As shown in FIGS. 1 and 2, a bass reproduction unit 1 consisting of a 61/2 inch
bass speaker unit 11 is made of an acrylic resin cylindrical casing (outer diameter 186 mm /
inner diameter 176 mm / length). The high-pitched sound reproducing unit 2 is coaxially
mounted by extending the mounting pole 15 from the center pole 13 of the magnetic circuit unit
12 of the bass speaker unit 11 upward. The high-sound reproduction unit 2 is configured by
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attaching a high-sound speaker unit 21 having a dome diaphragm 22 with a diameter of 25 mm
to the holding case 23. The holding case 23 includes a front surface 24 and a rear surface 25.
The front surface 24 has a curved surface so as to extend from the dome diaphragm 22 in the
outer peripheral direction. Further, the rear surface portion 25 also has a curved surface of two
steps as shown, and the rear half portion 25 is fixed to the mounting pipe 15. In this case, the
wiring material 26 for the high sound speaker unit 21 passes through the inside of the mounting
pipe 14.
[0009]
A reflector 3 is disposed on the front side of the high-pitched sound reproducing unit 2 so as to
face the dome diaphragm 22 via a support 4. The reflector 3 includes an opposing surface
portion 31 and a back surface portion 32, and at least the opposing surface portion 31 is formed
in the same curved surface as the curved surface of the holding housing 24. In the embodiment,
the back surface portion 32 is also formed symmetrically with the facing surface portion. A
hemispherical projection 33 symmetrical to the dome diaphragm 22 is projected on the facing
surface portion 31. The hemispherical projection 33 and the dome diaphragm 22 are disposed in
proximity to each other by about 1 to 2 mm. . However, when the protrusion of the dome
diaphragm 22 is small, the hemispherical protrusion 33 is unnecessary.
[0010]
With the above configuration, the curved surface of the front surface portion 24 of the holding
housing 23 and the curved surface of the facing surface portion 31 of the reflector 3 form a horn
shape, and the cutoff frequency is an exponential curve. Is adjusted to be 2 KHz. A bottom plate
101 was attached to the bottom side of the cylindrical casing 10, and a duct 102 made of a resin
pipe having a diameter of 46 mm and a length of 45 mm was attached to the middle part. In the
first embodiment, the directivity characteristic in the horizontal plane shows the result of nondirectivity, and the vertical plane also shows the result of being nearly non-directivity at a solid
angle of 90 °. Further, as a result of providing the duct 102, it is possible to eliminate the
shortage of the cabinet volume, and since the duct 102 is located in the middle part, if the sound
absorbing material 103 of high density glass wool is inserted, the primary mode of standing
waves in the housing is reduced. Is less likely to occur. The undulation of the characteristic of
100 to 200 Hz of reduction was not eliminated. The same frequency characteristics and
directivity characteristics were obtained even when the high-sound radiation unit 20 constituted
by the high-tone reproduction unit 2 and the reflector 3 was mounted upside down.
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[0011]
[Embodiment 2] The cylindrical casing 10 is made of vinyl chloride resin having an outer
diameter of 216 mm, an inner diameter of 200 mm, and a length of 500 mm, and as shown in
FIG. The bass speaker unit 11 was attached to the baffle 5 in the same manner as in the first
embodiment. A bridge member 6 consisting of a curved metal pipe 61 is attached to the top plate
baffle 5 at a symmetrical position, and the high-pitched sound reproducing unit 2 is supported by
the bridge member 6 with a bridge structure. In this case, the high-pitched sound reproducing
unit 2 is supported upside down so that the dome vibrating unit 22 faces downward. Therefore,
the reflector 3 is positioned between the cone diaphragm 14 and the dome diaphragm 22 of the
bass reproduction unit 1. The wiring material for the high-pitched sound reproduction unit 2
may be directly derived from the top plate baffle 5 side to the high-pitched sound reproduction
unit 2 side, but the wiring dedicated material 62 made of a flexible material etc. Alternatively, the
wiring material 26 may be led through the inside of the part 2 side and the wiring material may
be passed through the inside, or as shown in FIG. . Reference numeral 64 denotes a rubber bush.
FIG. 5 shows a construction in which three bridge members 6 consisting of metal pipes 61 are
provided and one of them 63 is passed through a wiring material. In the second embodiment, the
rear surface 25 of the holding housing 23 can be formed symmetrically with the front surface
24. Furthermore, since there is no mounting pole 15 etc. as in the first embodiment, the
frequency characteristic in the second embodiment is near crossover. The flatness at 1 to 4 KHz
came out.
[0012]
In the embodiment in which the high-pitched sound reproducing unit 2 is supported by a bridge
structure, as shown in FIGS. 6 and 7, the bridge pier member 6 is integrally formed with the
holding case 23 by a synthetic resin having excellent flowability, such as polypropylene. Further,
the support 4 can be integrally formed. In this case, as shown in FIG. 8, when the slit groove 64 is
provided in the bridge leg member 6, the wiring member 26 can be inserted into the slit groove
64 and fixed together with the seal rubber member 65 with an adhesive. In the figure, reference
numeral 26 denotes a rubber gasket for attaching the high-pitched sound reproducing unit 2.
[0013]
In order to reduce the weight of the high-sound reproduction unit 2 and the reflector 3, as shown
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in FIG. 6, it is desirable to mold the rear surface 25 of the holding housing 23 and the rear
surface 32 of the reflector 3 using foam. Moreover, weight reduction can also be achieved by
hollow-molding the reflector 3.
[0014]
EXAMPLE 3 A cylindrical casing 10 having an outer diameter of 186 mm was formed of ceramic
silica fume-containing non-sintered concrete, and the wall thickness was partially changed. The
other configurations were the same as in Example 1. As an effect of partially changing the
thickness of the cylindrical casing 10, an extreme peak does not occur in the vibration rising
characteristics of the casing. In addition, the attenuation became straight and the sound quality
was improved.
[0015]
[Embodiment 4] In the speaker system of Embodiment 1, the sound absorbing material 103
made of high density glass wool filled in the cylindrical casing 10 is removed, and a urethane
foam of 5 mm thickness is stretched on the inner peripheral surface and the bottom surface The
urethane foam of the quantity whose acoustic impedance ratio approaches 1 was inserted in. The
deviation of the characteristic of 100 to 200 Hz increases as the diameter of the cylindrical
casing 10 and the diameter of the diaphragm in the low frequency speaker unit 1 become 1: 1. In
this phenomenon, the mass inertance in the housing can not be ignored, and parallel resonance is
connected. In Example 4, the acoustic impedance ratio such as urethane foam could be solved by
approaching it to 1 with a small sound absorbing material. When the acoustic impedance ratio is
in the range of 0.5 to 3, the characteristic deviation is within 2 db, and it has been confirmed that
"low buildup" is removed.
[0016]
According to the omnidirectional speaker system of the present invention, the horizontal axis
directivity becomes 360 ° omnidirectional, and the vertical axis directivity is also adjusted by
adjusting the height of the leg base of the cylindrical casing. , The directional characteristics at
the trial position are very good. Moreover, there is no deterioration in the characteristics due to
the diffraction of the cylindrical casing, and by coaxially arranging the bass reproduction unit
and the treble reproduction unit, it is possible to radiate a spherical wave with less disturbance of
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the wavefront, and localization and spreading It harmonizes, and it can obtain the sound quality
of the sense of depth especially excellent. Furthermore, the mounting structure of the high-tone
playback unit can be changed according to the input resistance, and stereophonic playback can
be performed without degrading the characteristics.
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