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JPH11275679

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DESCRIPTION JPH11275679
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
horn type speaker system provided with a screw horn.
[0002]
2. Description of the Related Art A horn type speaker system is one of the conventional
techniques for expanding the low frequency range of a speaker system, including a front loaded
horn type (hereinafter referred to as FLH) and a back loaded horn type Known as BLH) and
combination horns. FLH and BLH are speaker systems in which horns are attached to the front or
rear of the diaphragm of the speaker unit, and the combination horn type is a speaker in which
both the front and back of the diaphragm are horns or one is in phase reversal type It is a
system.
[0003]
In any case, it is possible to increase the sound pressure in the bass range since it can bear a
sufficient load up to the bass, and has a feature that the dynamic range is wide and the bass with
good transient characteristics and good crispness can be reproduced. ing.
[0004]
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1
On the other hand, as a drawback of the above-mentioned bass horn system, 1) If the cut-off
frequency showing the bass limit is selected low to widen the reproduction band, it becomes very
large and the practicability for home use is lost. .
2) In order to make the horn as small as possible, a bending horn in which the middle of the horn
is folded is put to practical use. However, since the structure is complicated, mass production is
difficult and it must be expensive. 3) Since the bending horn is formed by connecting straight
sound paths, it is not possible to avoid sound quality deterioration due to resonance at the
straight portion and air flow disturbance at the bending portion.
[0005]
Thus, while the bass horn speaker system according to the prior art has excellent features, it has
not become widespread due to a number of drawbacks.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of the abovementioned circumstances, and is a speaker which has good transient characteristics, is small in
size, has a structure that is easy to mass-produce, and is rich in bass volume. The purpose is to
provide a system.
[0007]
[Means for Solving the Problems]
[0008]
The speaker system of the present invention has a cabinet provided with screw horns on the
front and / or rear face of the speaker unit, and the screw horn is provided with a coaxial double
pipe consisting of an inner pipe and an outer pipe and a spiral provided in the gap. It is an
acoustic pipe formed of a partition plate, and the screw horn is provided with sound absorbing
means.
[0009]
The screw horn used in the present invention is a three-dimensional spiral sound pipe formed by
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providing a spiral partition in the gap of a coaxial double pipe consisting of an inner pipe and an
outer pipe, and is generally used for the sound path. The cross-sectional area is gradually
enlarged towards the horn opening.
Since the screw horn has a three-dimensional structure, space is effectively used, and downsizing
of the horn speaker system is possible.
[0010]
The screw horn functions as an acoustic filter for attenuating middle and high sound
components, but the higher the sound pressure attenuation rate of middle and high sound
components included in the sound emitted from the horn opening, the more interference with
the sound coming from other sound sources It is less and gives better results in sound quality.
Therefore, the sound quality can be expected to be further improved by incorporating auxiliary
means for improving the attenuation factor into the screw horn.
In the present invention, it has been clarified that the installation of a sound absorbing means is
effective as the above-mentioned auxiliary means.
[0011]
When the sound absorbing means in the present invention is a porous sound absorbing material,
part or all of the inner surface along the sound path of the screw horn is coated with the porous
sound absorbing material, thereby propagating in the screw horn Medium to high frequency
components in the sound are absorbed more than if not covered by the porous sound absorbing
material, and the attenuation factor is increased.
[0012]
The portion covered by the porous sound absorbing material may be the whole of the inner
surface of the screw horn, but is usually only a part thereof, and covering the outer periphery of
the inner tube is particularly advantageous in terms of ease of manufacture.
[0013]
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Any porous sound absorbing material may be used as long as it is generally used, and examples
include glass wool, rock wool, nylon wool, urethane foam, various woven or non-woven fabrics,
composites such as expanded polystyrene and quilting, felt Etc.
[0014]
As another sound absorption means in the present invention, a resonance pipe formed inside the
above-mentioned inner pipe can be mentioned.
The resonance tube comprises an air column closed at one end formed in the inner tube, ie, a
closed tube.
By resonating at a frequency at which the wavelength of the sound is approximately four times
the length of the resonance tube, part of the energy of the sound is converted to heat energy and
absorbed.
[0015]
If necessary, form a plurality of resonance tubes having different lengths by inserting a
longitudinal partition plate or the like into the inner pipe or inserting a pipe or the like having an
outer diameter smaller than the inner diameter of the inner pipe. It can also be done.
This enables sound absorption in a wider frequency band than when using a single resonance
tube.
[0016]
The above two sound absorbing means may be used alone or in combination.
[0017]
In general, the sound radiated to the outside from the opening through the horn has a phase
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delay proportional to the distance of the sound path formed in the horn.
Since the difference between the shortest distance along the inner circumference of the sound
path and the longest distance along the outer circumference of the sound path of the screw horn
of the present invention is large, the sound emitted from the diaphragm of the speaker unit for
the horn is a horn A distribution of phase delays occurs before it is emitted from the aperture.
[0018]
In the horn type system, the sound pressure output from the horn opening is added to the sound
pressure from other sound sources.
In the case of a conventional horn-type system, a phenomenon is often observed that, in the
above addition, a phase interference occurs in a specific frequency band to produce a sharp
valley. In the present invention, topological interference in a specific frequency band is mitigated
by the effect that the attenuation of middle and high-pitched sound components is enhanced by
the sound absorbing means, the effect of the phase delay distribution, etc., and flat sound
pressure frequency characteristics are obtained.
[0019]
In order to further ensure the prevention of the generation of valleys in the sound pressure
frequency characteristics, a small air chamber is provided between the speaker unit and the
screw horn, and a method of absorbing middle to high range by the acoustic capacitance is used
in combination. Can.
[0020]
Since the screw horn used in the present invention is formed by a smooth curved surface,
substantially no straight sound path or sharp bending portion exists, thus reducing the sound
quality deterioration due to unnecessary resonance or air flow disturbance. be able to.
Furthermore, the good characteristics of transient characteristics in the low frequency range and
the wide dynamic range are inherited from the advantages of the normal horn type system, and
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the flat sound pressure frequency characteristics etc. which are the advantages of the speaker
system of the present invention. Together, good sound quality is realized.
[0021]
Further, according to the manufacturing method described later, the screw horn has a structure
that is easy for industrial mass production, and a relatively inexpensive speaker system can be
provided.
[0022]
Embodiments of the present invention will be described below with reference to the drawings.
[0023]
(Embodiment 1) FIG. 4 shows an embodiment of the speaker system according to the present
invention, which is useful as a bass system.
In FIG. 4, the cabinet has a screw horn provided on the front surface of the speaker unit 1 for
horns and a cabinet 7 formed on the back surface of the speaker unit 1 with a vacant space 7.
The screw horn is formed by inserting the spiral shown in FIG. 2 into the outer tube 4 having a
circular internal sectional shape.
[0024]
The spiral in FIG. 2 is formed by arranging a spiral partition plate 3 around the inner pipe 2 to
form a spiral valley 5. When the spiral is inserted into the outer pipe 4, the outer pipe 4 and the
inner pipe 2 constitute a coaxial double pipe, the partition plate 3 is provided in the gap, and the
valley 5 has a three-dimensional spiral sound path shown in FIG. It will be 5.
[0025]
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A small air chamber 8 can be provided on the front surface of the horn speaker unit 1 as
necessary, and the sound on the front surface of the speaker unit 1 passes through the small air
chamber 8 and passes through the entrance of the helical sound path 5, that is, the throat 16 The
middle to high tone component is greatly attenuated through the helical sound path 5, and the
low tone component and the remaining middle to high tone component are emitted from the
opening 11 to the outside. The sound propagation direction is indicated by the arrows in FIG. The
shape in the vicinity of the throat 16 is shown in FIG. As shown, the opening is formed by a
straight horn 21 whose cross-sectional area is continuously enlarged. The direction of rotation of
the spiral may be either left or right.
[0026]
A porous sound absorbing material 20 is wound around the outer periphery of the inner pipe 2
substantially in parallel with the spiral partition plate and in the vicinity of the throat 16 to the
vicinity of the outlet of the spiral sound path 5. The material, thickness and width of the sound
absorbing material may be determined so as to obtain a sufficient sound absorbing effect within
the range where the cross-sectional area of the sound path is not significantly reduced.
[0027]
A resonance pipe 22 is formed inside the inner pipe, and a filler 15 such as sand is placed at the
bottom to adjust its length so as to resonate in a specific frequency band to be absorbed.
[0028]
The length of the helical sound path 5 is defined as the length measured along the center of the
sound path, that is, the middle point in the sound channel vertical direction by the arithmetic
mean diameter of the inner diameter and the outer diameter, 0.3 m or more and 4 m or less Is
preferred.
When the length is less than 0.3 m, the attenuation of the middle to high tone component is
insufficient. When the length exceeds 4 m, the sound quality is deteriorated because the time
delay until the sound radiated to the outside through the opening 11 reaches the listening
position can not be neglected, and the air flow resistance in the sound path is further increased.
Causes problems such as a decrease in sound output. There is no particular limitation on the
number of rotations of the spiral, but one or more times is desirable to sufficiently attenuate
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middle-high tone components.
[0029]
The cross-sectional area of the helical sound path is defined as the cross-sectional area of the
sound path cut by a plane passing through the central axis of the coaxial double tube. The
sectional area of the throat 16 is preferably in the range of 0.1 to 15, assuming that the effective
vibration area of the speaker unit is 1. The cross-sectional area of the helical sound path may be
constant in the direction of sound travel, but it is usually preferable to be gradually enlarged.
[0030]
In the case of expanding the cross-sectional area of the helical sound path, the expansion may be
continuous and smooth, and is not necessarily exponential. As a method of expanding the crosssectional area, there are a method of expanding the height of the sound path, a method of
expanding the width, and a method of expanding both simultaneously. 4 and 2 show the case
where only the height is enlarged and the width is fixed. Apart from FIGS. 4 and 2, the width of
the sound path can also be expanded by increasing the diameter of the outer pipe toward the
bottom or reducing the diameter of the inner pipe.
[0031]
It is desirable that the cross sectional shapes of the outside of the inner pipe 2 and the inside of
the outer pipe 4 used in the present invention are both circular. A circular cross-sectional shape
is easier to manufacture and can form a sound path substantially free of linear portions in the
sound traveling direction, so that resonance is less likely to occur and there is less turbulence in
the air flow. The outer cross-sectional shape of the outer tube 4 is not necessarily circular, and
may be square or the like. The inner pipe 2 and the outer pipe 4 are coaxially arranged to form a
coaxial double pipe.
[0032]
The inner pipe 2 is not necessarily required to be a pipe, and may be a rod-like body having no
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internal space. The diameters of the outer pipe and the inner pipe do not have to be constant,
and as described above, they may be changed for the purpose of expanding the sound path crosssectional area.
[0033]
The spiral partition 3 can be formed in various ways. For example, there is a method of winding a
band-shaped rubber plate, a cabtire cable, etc. around the inner pipe 2 in multiple layers and
fixing them with an adhesive. When the spiral partition 3 is formed of a flexible material such as
a cabtire cable, it is desirable to increase the rigidity of the spiral partition 3 by applying an
epoxy resin or the like in order to prevent vibration. The resulting helical body is inserted into
the outer tube 4 and the outer surface of the helical partition 3 and the inner surface of the outer
tube 4 are joined with an adhesive to form the helical sound path 5.
[0034]
In order to industrially mass-produce the helical sound path, various methods can be adopted
other than the above-described methods, but plastic injection molding is particularly preferable.
That is, only the portion where the outer pipe 4 and the spiral are integrated or only the spiral is
divided into blocks per rotation of the spiral partition 3 or each rotation less than 1 if necessary,
and each block is respectively formed by injection molding It is a method of forming and joining
a plurality of obtained blocks to form a helical sound path or a helical body. The above
manufacturing method and the like which do not require a high level of skilled artisans can be
adopted because the structure of the speaker system of the present invention is excellent in mass
productivity.
[0035]
In order to attach the speaker unit 1 and the cavity 7 to the above-mentioned coaxial double
pipe, a tube having a T-shaped or L-shaped joint or the like can be used. A sound absorbing
material can be installed inside the vacant space 7 and the small air chamber 8 (not shown).
[0036]
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The thick line in FIG. 5 is the sound pressure frequency characteristic of the above embodiment,
and a wide bass range and significant attenuation of middle and high range are observed. The
thin line in FIG. 5 is the sound pressure frequency characteristic when the sound absorbing
means is not provided, and the attenuation of the middle and high frequency range is insufficient.
[0037]
Second Embodiment FIG. 1 shows a system in which a second speaker unit 6 mainly sharing the
middle to high frequency range is attached to a baffle plate 10 of a vacant room in the system of
the first embodiment to provide a complete speaker system. The number of the speaker units 6
may be one as shown in the drawing, or a plurality of the speaker units 6 may be used for the
middle range and the high range.
[0038]
As shown in the drawing, the inside of the vacant room 7 may be divided between the two
speaker units by the partition plate 17 or may be without the partition plate.
[0039]
The relative relationship between the directions of the speaker unit 6 and the horn opening 11 is
arbitrary and may be the same, and may be reversed or rotatable.
[0040]
The thick line in FIG. 6 is the sound pressure frequency characteristic of the above embodiment,
in which the sound of the front surface of the speaker unit 6 is added to the bass radiated from
the horn opening 11, and a wide reproduction band is realized.
From the effects of the phase delay distribution, the small air chamber, the sound absorbing
material, etc., it can be seen that valleys due to interference are not generated.
The thin line in FIG. 6 is the sound pressure frequency characteristic when no sound absorbing
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means is provided, and the sound pressure level in the middle to high range is high, and the
sense of bass is insufficient.
[0041]
EXAMPLE 3 FIG. 7 shows an example of the BLH of the present invention, in which a porous
sound absorbing material 20 is wound around a middle pipe.
[0042]
EXAMPLE 4 FIG. 8 shows an example of a combination horn according to the present invention,
which is used as a bass system.
A porous sound absorbing material 20 is wound around the middle pipe.
[0043]
(Fifth Embodiment) FIG. 9 shows an example of a speaker system completed by attaching a full
range unit as a second speaker unit 6 to a combination horn according to a fourth embodiment
or a middle / high-tone unit.
[0044]
As described above, the present invention is a horn-type speaker system provided with a screw
horn, which has good transient characteristics, is small in size, has a structure that is easy to
mass-produce, and is rich in bass loudness. The system can be realized.
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