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JPWO2013153741

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DESCRIPTION JPWO2013153741
PROBLEM TO BE SOLVED: To improve sound quality by reducing mechanical resonance
sharpness and suppressing oscillation near the lowest resonance frequency. SOLUTION: A
magnet for generating a magnetic force, a magnetic gap for applying a magnetic force, a yoke at
least a part of which is positioned opposite to the magnet and which forms a magnetic circuit for
guiding the magnetic force of the magnet to the magnetic gap A coil bobbin formed so as to be
axially variable with respect to the magnet and the yoke, a coil wound around the coil bobbin and
at least a part of which is disposed in the magnetic gap, a cone that is vibrated with the
fluctuation of the coil bobbin, It has an edge that holds it in the approximate center, and a frame
that fixes the edge and the yoke, magnetic fluid is injected into the magnetic gap, the viscosity of
the magnetic fluid is set to a predetermined value or more, and mechanical resonance sharpness
is 1.0. As described below, the current drive produces an audio output proportional to the
current. [Selected figure] Figure 3
スピーカーユニット
[0001]
The present technology relates to the technical field of a speaker unit. More specifically, the
present invention relates to the technical field of improving sound quality by reducing
mechanical resonance sharpness and suppressing oscillation near the lowest resonance
frequency in a speaker unit operated by current drive.
[0002]
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1
The speaker unit has, for example, a magnetic circuit including a magnet, a yoke, and a coil (voice
coil), and a so-called dynamic in which a coil bobbin around which the coil is wound is vibrated in
the axial direction (vibration) Type speaker unit.
[0003]
There are types of such speaker units that are operated by voltage driving, but since the driving
force for the speaker unit is proportional to the current, in the case of a speaker unit by voltage
driving, the voltage and driving force in various situations are different. There is a possibility that
the linearity between them is broken and the sound quality of the sound outputted from the
speaker unit is deteriorated.
[0004]
For example, in the voltage-driven type speaker unit, the current is less likely to flow in the coil
as the frequency region becomes higher, so the output is reduced in the high frequency region.
[0005]
On the other hand, although there is an amplifier driven by current, when this speaker operates
the speaker unit on the premise of voltage driving, the electromagnetic brake by the power
generation of the coil is cancelled, so a large oscillation due to spring vibration occurs around the
lowest resonance frequency. Cause the sound quality to deteriorate.
[0006]
Therefore, there is a speaker unit in which a sheet such as non-woven paper for resistance
addition which adds air resistance to back pressure is attached to suppress oscillation around the
minimum resonance frequency.
[0007]
However, in such a speaker unit, the increase in the number of parts by the sheet causes a
problem of the appearance deterioration other than the increase of the manufacturing cost and
the increase of the work process of attaching the sheet.
In addition, if the sheet peels off, the oscillation suppression function is degraded.
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2
[0008]
From such a point of view, there is a speaker unit in which a magnetic fluid having a viscosity
that provides appropriate damping to the magnetic gap formed between the magnet and the
yoke is injected (see, for example, Patent Document 1 and Patent Document 2).
[0009]
JP-A-57-208794 JP-A-58-46798
[0010]
However, in the speaker units described in Patent Document 1 and Patent Document 2, it is
possible to reduce the oscillation by injecting a magnetic fluid having a viscosity that provides
appropriate damping to the magnetic gap. Depending on the strength of elasticity of the damper
and the edge, the weight of the cone, and the viscosity of the magnetic fluid, the sufficient
suppression effect of the oscillation that can improve the sound quality can not be exhibited.
[0011]
For example, even in the case of using a magnetic fluid, oscillation around the lowest resonance
frequency is sufficient unless the sharpness (mechanical resonance sharpness or combined
resonance sharpness), which is an index indicating the degree of convergence of vibration, is
sufficiently reduced. Can not be suppressed.
[0012]
Therefore, the present technology speaker unit has an object to overcome the above-mentioned
problems and to reduce mechanical resonance sharpness and suppress oscillation near the
lowest resonance frequency to improve sound quality.
[0013]
First, in order to solve the problems described above, the speaker unit has a magnet that
generates a magnetic force, a magnetic gap that exerts a magnetic force, and at least a part of
which is positioned to face the magnet. A yoke forming a magnetic circuit leading to a magnetic
gap, a coil bobbin formed in a cylindrical shape and made axially variable with respect to the
magnet and the yoke, at least a part of which is wound around the coil bobbin and disposed in
the magnetic gap Coil, a cone that is vibrated according to the variation of the coil bobbin, an
edge that holds the cone in the approximate center, and a frame that fixes the edge and the yoke
respectively, and the magnetic gap is in the magnetic gap Is injected, and the viscosity of the
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magnetic fluid is set to a predetermined value or more so that the mechanical resonance
sharpness is 1.0 or less It is one in which the output of the sound proportional to the current by
the current driving is performed.
[0014]
Therefore, in the speaker unit, the oscillation around the lowest resonance frequency is
suppressed.
[0015]
Second, in the above-described speaker unit, it is desirable that the speaker unit be used as a full
range or low range woofer for the entire band.
[0016]
By being used as a full range or low range woofer for the entire band, the lowest resonance
frequency is always included in the reproduction band of the speaker unit.
[0017]
Third, in the above-mentioned speaker unit, it is desirable that the mechanical resonance
sharpness be 0.5 or more and 0.6 or less.
[0018]
By setting the mechanical resonance sharpness to 0.5 or more and 0.6 or less, the oscillation at
the lowest resonance frequency is suppressed after securing a good output state in the low band.
[0019]
Fourth, in the above-described speaker unit, it is preferable that a damper having elasticity be
provided between the frame and the coil bobbin.
[0020]
Due to the provision of the elastic damper coupled between the frame and the coil bobbin, the
damper suppresses excessive fluctuation in the axial direction of the coil bobbin.
[0021]
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4
Fifth, in the above-described speaker unit, it is desirable that a material containing iron oxide in a
synthetic ester be used as the magnetic fluid.
[0022]
By using a material containing iron oxide in a synthetic ester as the magnetic fluid, a material
suitable as a material for reducing mechanical resonance sharpness is used as the magnetic fluid.
[0023]
A speaker unit according to the present technology includes a magnet that generates a magnetic
force, a magnetic gap that exerts a magnetic force, and a yoke that is positioned so as to face at
least a part of the magnet and guides a magnetic force of the magnet to the magnetic gap. A coil
bobbin formed in a tubular shape and made axially variable with respect to the magnet and the
yoke, a coil wound around the coil bobbin and at least a part of which is disposed in the magnetic
gap, and with the coil bobbin fluctuation And an edge for holding the cone substantially at the
center, and a frame for fixing the edge and the yoke, magnetic fluid is injected into the magnetic
gap, and the viscosity of the magnetic fluid is at least a predetermined value. The mechanical
resonance sharpness is made 1.0 or less, and the current drive is proportional to the current.
Output of voice is performed.
[0024]
Therefore, it is possible to sufficiently suppress oscillation around the lowest resonance
frequency, and sound quality can be improved.
[0025]
In the technology described in claim 2, it is used as a full range or low range woofer for the
entire band.
[0026]
Therefore, the lowest resonance frequency is always included in the reproduction band of the
speaker unit, and the oscillation at this lowest resonance frequency can be reliably suppressed to
improve the sound quality in the low band.
[0027]
In the technology described in claim 3, the mechanical resonance sharpness is set to 0.5 or more
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and 0.6 or less.
[0028]
Therefore, the oscillation at the lowest resonance frequency can be sufficiently suppressed to
further improve the sound quality after securing a good output state in the low band.
[0029]
According to the technology described in claim 4, a resilient damper coupled between the frame
and the coil bobbin is provided.
[0030]
Therefore, high output in the reproduction area can be secured.
[0031]
In the technology described in claim 5, a material in which iron oxide is contained in a synthetic
ester is used as the magnetic fluid.
[0032]
Therefore, the sound quality can be improved without increasing the manufacturing cost of the
speaker unit.
[0033]
An embodiment of the present technology is shown together with Drawing 2 thru / or Drawing 6,
and this figure is a block diagram of a speaker system.
It is a side view of a speaker unit.
It is a sectional view of a speaker unit.
It is an expanded sectional view which shows the injection state to the magnetic gap of magnetic
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6
fluid.
It is a graph which shows the reproduction | regeneration characteristic of the low region | pass
by the total resonance sharpness of a speaker unit.
It is sectional drawing of the speaker unit which concerns on a modification.
[0034]
Hereinafter, the best mode for implementing the present technology speaker unit will be
described according to the attached drawings.
[0035]
In the following description, the direction in which the speaker unit is directed is referred to as
the front, up, down, front, back, left, and right.
[0036]
In addition, the directions of up, down, front, rear, left, and right shown below are shown for
convenience of explanation, and the present technology is not limited to these directions and
applied.
[0037]
[Overall Configuration] First, the overall configuration of a speaker system in which a speaker
unit is used will be described (see FIG. 1).
[0038]
The speaker system 100 includes, for example, an audio signal output unit 101 such as a digital
music player (DMP) or a disc player, and an amplifier 102 for amplifying an audio signal output
from the audio signal output unit 101 by current drive and a speaker 103 for outputting audio.
And.
The amplifier 102 may have a built-in volume for volume control.
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[0039]
The audio signal output from the audio signal output unit 101 is an analog signal, which is
amplified by the amplifier 102 and output from the speaker 103 as audio.
In the speaker 103, sound output proportional to the current is performed by current driving.
[0040]
The speaker 103 is configured of an enclosure (casing) and a speaker unit 1.
As the enclosure, various types such as a closed type, a bass reflex type, a back load horn type
and an acoustic pipe type are used.
[0041]
[Specific Configuration of Speaker Unit] The speaker unit 1 has required parts disposed inside
and outside the frame 2 (see FIGS. 2 and 3).
[0042]
The frame 2 has a distal end side circumferential portion 3 formed in a substantially annular
shape, a proximal end side circumferential portion 4 positioned behind the distal end side
circumferential portion 3 and formed in a substantially annular shape, and a distal end side
circumferential shape It has connecting legs 5, 5... Connecting the part 3 and the proximal end
side circumferential part 4.
[0043]
The diameter of the proximal end side circumferential portion 4 is smaller than the diameter of
the distal end side circumferential portion 3, and the connecting legs 5, 5,... Are inclined so as to
be displaced outward as they go forward.
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The opening on the front side of the distal end side circumferential portion 3 is formed as an
opening 3a opened in the front, that is, in the sound output direction.
[0044]
A terminal 6 is attached to the connecting leg 5.
The terminal 6 is provided as a terminal portion to which connection with the amplifier 102 is
performed.
[0045]
A yoke 7 is disposed on the rear end side of the frame 2.
The yoke 7 is fixed to the rear end of the frame 2 and protrudes rearward from the frame 2
except for the front end.
[0046]
The yoke 7 has a substantially disk-shaped base surface portion 8, a substantially cylindrical
insertion / disposition portion 9 protruding forward from the outer peripheral portion of the
base surface portion 8, and a projection 10 protruding rearward from the central portion of the
base surface portion 8. It is integrally formed.
The yoke 7 is formed with a through hole 7 a penetrating the base surface portion 8 and the
projection 10.
[0047]
Holes 8a, 8a,... Are formed on the outer peripheral portion of the base surface portion 8 at
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9
intervals in the circumferential direction.
[0048]
Inside the yoke 7, a first plate 11, a magnet 12 and a second plate 13 are fixed and arranged in
order from the front side in contact with each other.
Each of the first plate 11, the magnet 12 and the second plate 13 is formed, for example, in an
annular shape.
The rear surface of the second plate 13 is fixed to the front surface of the base surface 8 of the
yoke 7.
[0049]
The central axis of the yoke 7 and the central axes of the first plate 11, the magnet 12 and the
second plate 13 coincide with each other.
A space between the inner circumferential surface of the insertion and placement portion 9 and
the outer circumferential surface of the first plate 11 and the magnets 12 and the second plate
13 serves as a magnetic gap 14 for applying a magnetic force generated from the magnet 12 to a
coil described later. It is formed.
[0050]
A cylindrical coil bobbin 15 is disposed inside the frame 2, and a rear end portion of the coil
bobbin 15 is positioned in the magnetic gap 14.
The coil bobbin 15 is movable (movable) in the axial direction (front-rear direction) with respect
to the yoke 7, the first plate 11, the magnet 12, and the second plate 13.
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10
[0051]
A coil (voice coil) 16 is wound around the outer peripheral surface of the rear end portion of the
coil bobbin 15.
The coil 16 is connected to the terminal 6 by being led out of the wound portion at both ends.
The coil 16 is located in the magnetic gap 14.
[0052]
By positioning the coil 16 in the magnetic gap 14, a magnetic circuit is configured by the first
plate 11, the magnet 12, the second plate 13, the yoke 7 and the coil 16.
[0053]
A magnetic fluid 17 is injected between the first plate 11 and the front end of the insertion
portion 9 in the yoke 7 (see FIGS. 3 and 4).
The magnetic fluid 17 is retained between the first plate 11 and the front end of the insertion
placement portion 9.
[0054]
As the magnetic fluid 17, for example, a material in which iron oxide is contained in a synthetic
ester is used, and the viscosity is increased to be in a colloidal state.
The magnetic fluid 17 is not limited to the material in which iron oxide is contained in the
synthetic ester, and another material may be used as the magnetic fluid 17.
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11
[0055]
However, as the magnetic fluid 17, it is desirable that a material having high heat resistance and
high magnetic flux density be used without being scattered with vibration during driving of the
speaker unit 1 and not solidified by temperature at the time of use.
From such a point of view, the material containing iron oxide in the above-mentioned synthetic
ester is a material suitable as a material used as the magnetic fluid 17.
[0056]
A cone 18 is attached to the front end of the coil bobbin 15.
The cone 18 is fluctuated (vibrated) with the fluctuation in the axial direction of the coil bobbin
15.
[0057]
An edge 19 formed in an annular shape is connected between the front end portion of the coil
bobbin 15 and the tip side circumferential portion 3 of the frame 2.
The edge 19 holds the cone 18 substantially at the center and is also fluctuated (vibrated) with
the fluctuation in the axial direction of the coil bobbin 15.
[0058]
As described above, the magnetic fluid 17 is injected into the speaker unit 1, and the magnetic
fluid 17 has a function of centering the coil bobbin 15.
Therefore, the speaker unit 1 may not be provided with a damper.
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[0059]
Since the speaker unit 1 is not provided with a damper, the number of parts is reduced
accordingly, and the manufacturing cost of the speaker unit 1 can be reduced.
[0060]
[Operation of Speaker Unit] In the speaker unit 1 configured as described above, when a drive
current is supplied to the coil 16, a thrust is generated in the magnetic circuit, and the coil
bobbin 15 is varied in the back and forth direction (axial direction). The cone 18 and the edge 19
vibrate with the fluctuation of.
At this time, the output of the voice proportional to the current, that is, the output of the voice
output from the voice signal output unit 101 and amplified by the amplifier 102 is performed.
[0061]
In the speaker unit 1, as described above, the viscosity of the magnetic fluid 17 is increased, and
the mechanical resonance sharpness Qms is set to 1.0 or less.
The mechanical resonance sharpness Qms is an index indicating the degree of convergence of
vibration together with the electrical resonance sharpness Qes and the total resonance sharpness
Qts, and the smaller the value, the lower the oscillation near the lowest resonance frequency F0.
[0062]
The total resonance sharpness Qts is indicated by Qts = (Qms × Qes) / (Qms + Qes).
[0063]
FIG. 5 is a graph showing the reproduction characteristics in the low range by the total
resonance sharpness Qts of the speaker unit.
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13
[0064]
As shown in FIG. 5, as the value of the total resonance sharpness Qts is larger, the peak of the
lowest resonance frequency F0 (about 500 Hz) is larger, and oscillation easily occurs.
Conversely, the smaller the value of the total resonance sharpness Qts, the smaller the peak of
the lowest resonance frequency F0 and the less likely the oscillation will occur, but the
reproduction capability is reduced.
Therefore, a balance is required to lower the resonance peak near the lowest resonance
frequency F0 and to secure a good reproduction capability.
[0065]
Speaker unit for voltage drive such as a full range or low range woofer for all bands where the
lowest resonance frequency F0 exists in the reproduction band When using a magnetic fluid with
high viscosity, it is expressed by electrical resonance sharpness Qes Due to the action of the
electromagnetic brake generated in proportion to the speed of the coil (coil bobbin), the total
resonance sharpness Qts of the speaker unit becomes too small, and the ability to reproduce bass
sounds is lowered.
[0066]
Therefore, in a speaker unit for voltage driving such as a full range or a woofer in which the
lowest resonance frequency F0 exists in the reproduction band, generally, the viscosity of the
magnetic fluid is reduced and the mechanical resonance sharpness Qms is not reduced. .
[0067]
However, in the speaker unit 1, since the operation is performed by current drive, the action of
the electromagnetic brake generated in proportion to the speed of the coil (coil bobbin) is
cancelled, and the electrical resonance sharpness Qes becomes a very large value.
Therefore, the electrical resonance sharpness Qes becomes an extremely large value with respect
to the mechanical resonance sharpness Qms, and the total resonance sharpness Qts is Qts = (Qms
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14
× Qes) / (Qms + Qes) = (Qms) / (Qms / Since Qms / Qes becomes approximately 0 from Qes + 1),
the total resonance sharpness Qts becomes approximately equal to the mechanical resonance
sharpness Qms.
[0068]
Therefore, in the speaker unit 1 operated by current drive, it is possible to ignore the electrical
resonance sharpness Qes at the total resonance sharpness Qts, and the total resonance sharpness
Qts is only the mechanical resonance sharpness Qms. It becomes a value determined by
[0069]
Therefore, in the speaker unit 1, as described above, the viscosity of the magnetic fluid 17 is
increased to appropriately adjust the mechanical resonance sharpness Qms to a value of 1.0 or
less, and the total resonance sharpening The oscillation around the lowest resonance frequency
F0 can be sufficiently suppressed after controlling the degree Qts and securing good
reproduction characteristics in the low band.
[0070]
In the speaker unit 1, it is more preferable that the mechanical resonance sharpness Qms be 0.5
or more and 0.6 or less.
[0071]
By setting the mechanical resonance sharpness Qms to 0.5 or more and 0.6 or less, while
securing a good output state in the low band, the oscillation at the lowest resonance frequency
F0 is sufficiently suppressed to further improve the sound quality. Can be
[0072]
[Modification of Speaker Unit] Hereinafter, a speaker unit 1A according to a modification will be
described (see FIG. 6).
[0073]
A speaker unit 1A described below is different from the above-described speaker unit 1 only in
that a damper is disposed.
12-05-2019
15
Therefore, in the following description of the speaker unit 1A, only different portions as
compared with the speaker unit 1 will be described in detail, and the other portions will be
denoted by the same reference numerals as those given to similar portions in the speaker unit 1
The explanation is omitted.
[0074]
In the speaker unit 1A, a damper 20 is attached to an intermediate portion in the axial direction
of the coil bobbin 15.
The damper 20 is formed in a thin substantially annular shape so as to be elastically deformable,
the inner peripheral portion is attached to the outer peripheral surface of the coil bobbin 15, and
the outer peripheral portion is attached to the frame 2.
The damper 20 is elastically deformed when a drive current is supplied to the coil 16 and the coil
bobbin 15 is varied in the axial direction, and has a function of suppressing excessive variation in
the axial direction of the coil bobbin 15.
[0075]
When the damper 20 is provided as in the speaker unit 1A, it is necessary to adjust the viscosity
of the magnetic fluid 17 to sufficiently suppress the oscillation around the minimum resonance
frequency F0 because the spring vibration tends to be large. It is possible to secure high output
at
[0076]
[Summary] As described above, in the speaker units 1 and 1A, the magnetic fluid 17 is injected
into the magnetic gap 14, the viscosity of the magnetic fluid 17 is set to a predetermined value
or more, and the mechanical resonance sharpness Qms is It is less than 1.0.
[0077]
Therefore, it is possible to sufficiently suppress the oscillation in the vicinity of the lowest
resonance frequency F0 and to improve the sound quality.
12-05-2019
16
[0078]
In addition, by using the speaker unit 1 or 1A as a woofer for full range or low frequency band
for the entire band, the minimum resonance frequency F0 is necessarily included in the
reproduction band of the speaker unit 1 or 1A, and oscillation at this minimum resonance
frequency F0 The sound quality in the low band can be improved by suppressing the noise
surely.
[0079]
Furthermore, by using a material containing iron oxide in a synthetic ester as the magnetic fluid
17, this material is suitable as a material that lowers the mechanical resonance sharpness Qms,
and the adjustment of viscosity is relatively easy. The sound quality can be improved without
increasing the manufacturing cost of the speaker units 1 and 1A.
[0080]
[Present Technology] The present technology can be configured as follows.
[0081]
(1) A magnet for generating a magnetic force, a magnetic gap for applying a magnetic force, a
yoke at least a part of which is positioned opposite to the magnet to form a magnetic circuit for
guiding the magnetic force of the magnet to the magnetic gap A coil bobbin formed to be
variable in the axial direction with respect to the magnet and the yoke, a coil wound around the
coil bobbin and at least a part of which is disposed in the magnetic gap, and vibrated along with
the fluctuation of the coil bobbin Cone, an edge for holding the cone substantially in the center,
and a frame for fixing the edge and the yoke, magnetic fluid is injected into the magnetic gap,
and the viscosity of the magnetic fluid is set to a predetermined value or more. And the
mechanical resonance sharpness is reduced to 1.0 or less, and the current drive produces an
audio output proportional to the current. Speaker unit.
[0082]
(2) The speaker unit according to (1), which is used as a full range or low range woofer for the
entire band.
[0083]
(3) The speaker unit according to (1) or (2), wherein the mechanical resonance sharpness is set
to 0.5 or more and 0.6 or less.
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[0084]
(4) The speaker unit according to any one of (1) to (3), in which a frame and an elastic damper
coupled between the coil bobbins are provided.
[0085]
(5) The speaker unit according to any one of (1) to (4), wherein a material containing iron oxide
in a synthetic ester is used as the magnetic fluid.
[0086]
The specific shapes and structures of the respective parts shown in the above-described best
mode are merely merely examples of implementation when the present technology is practiced,
and these limit the technical scope of the present technology. It should not be interpreted in any
way.
[0087]
DESCRIPTION OF SYMBOLS 1 ... Speaker unit, 2 ... Frame, 7 ... Yoke, 12 ... Magnet, 14 ... Magnetic
gap, 15 ... Coil bobbin, 16 ... Coil, 17 ... Magnetic fluid, 18 ... Cone, 1A ... Speaker unit, 20 ...
Damper
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