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JP2004274206

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DESCRIPTION JP2004274206
To provide a fluid edge speaker with excellent sound quality by providing sufficient stroke
characteristics to an edge and a damper without sacrificing an effective acoustic diameter of the
speaker even with a small diameter speaker. In the present invention, the edge for supporting the
outer peripheral portion of the diaphragm has a structure using a magnetic fluid that moves in
the same manner as the diaphragm while supporting the diaphragm outer peripheral portion,
and has a voice coil coupled to the diaphragm. The damper for supporting the voice coil bobbin
is configured to be supported by a butterfly damper which has high stroke property and also has
centering property. The butterfly damper 5 has a connecting portion 5d for connecting the inner
circumferential ring portion 5b and the outer circumferential ring portion 5c outside thereof with
a shape obtained by combining a substantially circular arc-shaped curved portion and a linear
portion extending in the radial direction. The curved portion and the straight portion have high
stroke property, and the straight portion has centering property. [Selected figure] Figure 1
スピーカ
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker for an acoustic device, and more particularly to a speaker having a structure supported
by an edge formed of a magnetic fluid and including a diaphragm. 2. Description of the Related
Art FIG. 6 (a) shows a schematic half sectional view of a conventional loudspeaker having a
structure in which an outer peripheral portion of a cone-shaped diaphragm 1A 'is supported by
an edge 2'. The outer periphery of the edge 2 'is coupled to a frame (not shown), and the
diaphragm 1A' is coupled to the voice coil 4 ', and the voice coil 4' is vibratably supported via the
damper 5 '. The other 7 'is an external magnet type magnetic circuit, and a voice coil 6' is
disposed in this magnetic gap. FIG. 6 (b) shows another conventional example in which the
diaphragm 1 'is formed in a dome shape. The outer periphery of the diaphragm 1 'is also
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supported via the edge 2'. Also, a voice coil bobbin 4 'having a voice coil 6' is supported by a
damper 5 '. As described above, in the conventional general speaker, the diaphragms 1A 'and 1'
are vibratably supported via the edge 2 '. [0005] When the diaphragms 1A 'and 1' vibrate due to
the sound signal application to the voice coil 6 ', the edge 2' is integrally coupled to the
diaphragms 1A 'and 1', so the diaphragm 1A It will vibrate with ', 1' and a sound will come out
from this edge 2 'part. If the edge 2 'moves in the same phase as the diaphragms 1A' and 1 ', the
vibration of the diaphragms 1A' and 1 'will not be inhibited, but depending on the material and
the shape, etc. At the time of large amplitude, low frequency distortion occurs due to nonlinearity of the support system, and desired characteristics and sound quality can not be
obtained. In particular, in the case of a speaker with an extremely small diameter, such as φ30
or φ50, the diameter of the edge 2 ′ which is a supporting system of the diaphragms 1 A ′
and 1 ′ also becomes small, and it is not possible to make a high stroke structure. If the edge
width is increased to give the edge 2 ′ a high stroke property, the diameter of the diaphragms 1
A ′ and 1 ′ must be reduced due to the restriction of the aperture of the speaker, and the
speaker acoustically The problem is that the effective diameter decreases and the efficiency
decreases. Further, when the dampers 5 'supporting the diaphragms 1A', 1 'are formed into a
spiral shape as shown in FIG. 7 to have a high stroke property, the diaphragms 1A', 1 'rotate with
the amplitude. Although movement occurs, there is a problem that the edge 2 'does not
rotationally move and exerts an undue burden on the edge 2' or can not obtain a sufficient
stroke.
Furthermore, the high stroke type damper 5 'having a spiral shape simply by an arc-shaped
notch as shown in FIG. 7 has a defect in the centering property of the voice coil bobbin 4'
because the strength in the radial direction is weak. There was also the problem of. JP-B-5831157 is a prior art example in which a diaphragm is supported via a magnetic fluid in order to
eliminate the defects in the case of using the edge of the solid structure described above. As
shown in FIG. 8, this speaker adopts a configuration in which the outer periphery of a flat
diaphragm 20 is supported by an edge 21 formed of a magnetic fluid. The edge 21 is provided
on the upper surface of the lower yoke 22 whose end is bent upward, the ring-shaped magnet 23
provided on the upper surface of the lower yoke 22, and the upper surface of the magnet 23. The
magnetic circuit includes an upper yoke 24 whose lower end is bent downward and an upper
yoke 24 disposed opposite to the lower yoke 22. A magnetic fluid 25 is filled between the bent
portions of the respective yokes 22, 24. A flat diaphragm 20 is supported. As another
conventional example of this type, JP-A-54-147028 exists. FIG. 9 shows an example of the
configuration. The edge 30 including the magnetic fluid of this speaker also constitutes a
magnetic circuit by the pair of yokes 31 and 32, the magnet 33 and the like as in the abovedescribed embodiment. The magnetic fluid 34 is disposed in the magnetic gap between the bent
portions on one end side of each of the yokes 31 and 32, and the flange portion 35a formed on
the outer peripheral end of the diaphragm 35 is inserted and supported there. Furthermore, as
another prior art, there is Japanese Patent Application Laid-Open No. 61-230497 as shown in
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FIG. In this conventional example, a flange portion 41 is provided on the dome-shaped
diaphragm 40, and the flange portion 41 is supported via the magnetic fluid 42. In the figure,
reference numeral 43 denotes a magnetic circuit for holding a magnetic fluid, which comprises a
ring-shaped magnet 44 and magnetic plates 45 and 46 provided on the upper and lower sides
thereof. Still another conventional example is Japanese Utility Model Application Publication No.
56-57582 as shown in FIG. In this conventional example, a ferromagnetic plate 51 having a
substantially V-shaped cross section is provided on the periphery of a conical diaphragm 50, and
a magnetic fluid 52 and a magnet 53 are provided on the outside thereof. In the Japanese Patent
Publication No. 58-31157 shown in FIG. 8, the flat diaphragm 20 of a 90φ woofer is supported
by a magnetic fluid 25 and a magnetic circuit. The magnetic circuit is composed of a pair of
yokes 22, 24 and the like having a bent portion, has a large number of parts, is complicated in
structure, and has problems in the assembling surface, cost and the like.
Japanese Patent Application Laid-Open No. 54-147028 shown in FIG. 9 similarly has a
complicated magnetic circuit, and has the same disadvantages as the above-described
conventional example. Further, in these conventional examples, the main cause is to remove the
non-linearity due to the edge non-linearity in the cone-shaped diaphragm, and no special special
consideration is given to the damper 36 for supporting the vibration system, There is no
technical idea that even with a small diameter speaker, sufficient stroke can be obtained. In JP-A61-230497 shown in FIG. 10, a separate flange portion 41 is provided at the periphery of the
diaphragm 40 and supported via the flange portion 41, so that the structure and manufacture of
the vibration system is There is a problem that it is complicated. In the case of the Japanese
Utility Model Application No. 56-57582 shown in FIG. 11, a ferromagnetic plate 51 which is a
separate body and has a substantially V-shaped cross section is joined to the peripheral edge of
the diaphragm 50. There is a problem in that the structure is supported and the structure and
manufacture of the vibration system are complicated. Also, Japanese Patent Application LaidOpen No. 61-230497 and Japanese Utility Model Application Publication No. 56-57582 etc. are
not conscious of extremely small diameter speakers such as φ30 or φ50, and dampers are also
used as conventional ones. It has not been done. The present invention has been proposed in
view of the above, and an object thereof is to combine a magnetic circuit for holding a magnetic
fluid with a simple configuration and a butterfly damper of a special shape to have a small
diameter. Nevertheless, the object is to provide a speaker that can take a large stroke, obtain
sufficient bass, and have a simple vibration system. According to the present invention, there is
provided an annular magnet 2a provided on the side of the outer peripheral portion of the
diaphragm 1 or on the side of a frame opposed to and spaced from the outside of the diaphragm
1. And a butterfly damper 5 for supporting a voice coil bobbin 4 coupled to the diaphragm 1. The
butterfly damper 5 is disposed on the voice coil bobbin 4 side. And an outer circumferential ring
portion 5c concentrically formed outside the inner circumferential ring portion 5b, and the outer
circumferential ring portion 5c and the inner circumferential ring region 5c. Between the part 5
b and the part 5 b, a band-like connecting part extending substantially in the radial direction and
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an arc-like connecting part extending along the inner circumferential annular part 5 b are
connected to achieve the above object. Further, in this case, the butterfly damper 5 is provided
on the outer side or the inner side of the voice coil bobbin 4 to support the diaphragm 1 to
achieve the above object.
The diaphragms 1 and 1A have a dome shape or a cone shape, and a flange portion 1a which is
bent downward is formed on the outer peripheral portion of the cone-shaped diaphragm 1A. The
magnetic fluid 2 b is in contact with the magnetic fluid 2 b to achieve the above object.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the edge
supporting the outer peripheral portion of the diaphragm has a structure using a magnetic fluid
that moves in the same manner as the diaphragm while supporting the outer peripheral portion
of the diaphragm, and vibration A damper for supporting a voice coil bobbin having a voice coil
coupled to a plate is configured to be supported by a butterfly damper having high stroke
property and also having centering property. Hereinafter, the present invention will be described
with reference to the drawings. FIG. 1 (a) is a schematic half sectional view of a fluid edge
speaker according to a first embodiment of the present invention, and FIG. 1 (b) is a plan view of
a butterfly damper used in this speaker. In FIG. 1 (a), reference numeral 1 denotes a domeshaped diaphragm, and the outer peripheral portion of the diaphragm 1 is supported on a
support member 3 on the frame side via an edge 2 including a magnetic fluid 2b. There is. In this
embodiment, the edge 2 is provided between the ring-shaped magnet 2 a provided on the outer
peripheral portion of the diaphragm 1 and the outer peripheral surface of the magnet 2 and the
inner peripheral surface of the support member 3. And the magnetic fluid 2b. The inner
peripheral surface of the support member 3 on the frame side is formed in a circular shape, and
is provided concentrically around the outer peripheral surface of the voice coil bobbin 4 coupled
to the diaphragm 1 with a space therebetween. The voice coil bobbin 4 connected to the
diaphragm 1 is connected to the inner peripheral portion of the butterfly damper 5, the outer
peripheral portion of the butterfly damper 5 is connected to the inner peripheral surface side of
the support member 3, and the voice coil bobbin 4 It is vibratably supported via the butterfly
damper 5. A voice coil 6 is provided on the lower outer periphery of the voice coil bobbin 4, and
the voice coil 6 is disposed in the magnetic gap 8 of the internal magnetic circuit 7. The magnetic
circuit 7 has a bottom portion and an outer peripheral wall, and is provided on an upper portion
of a yoke 9 having a substantially U-shaped longitudinal cross section, a short cylindrical magnet
10 provided at the center of the bottom surface, And a disk-like plate 11. As shown in FIG. 1B,
the butterfly damper 5 for vibratably supporting the voice coil bobbin 4 is formed with a circular
hole 5 a for inserting and attaching the voice coil bobbin 4 in the center, and the hole An inner
circumferential annular portion 5b is formed on the outer periphery.
The inner circumferential ring portion 5b and the outer circumferential ring portion 5c formed
on the outer circumferential side of the butterfly damper 5 are connected by a plurality of
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connecting portions 5d. The butterfly damper 5 according to the present invention is a linear
portion extending in a substantially radial direction with a substantially circular arc-like curved
portion and a connecting portion 5 d connecting the inner peripheral annular portion 5 b and the
outer peripheral annular portion 5 c outside thereof. And a high stroke property, and a centering
property is provided by a substantially radially extending connection portion. That is, the inner
end 5e of the connecting portion 5d is connected to the inner circumferential ring 5b, and the
outer end 5f is connected to the outer circumferential ring 5c, and between the inner end 5e and
the outer end 5f. The connecting portion main body 5d 'is formed on the. The butterfly damper 5
of the illustrated example has four connecting portions 5d, and their respective inner end
portions 5e are equally spaced apart and connected to the inner circumferential ring portion 5b.
In this case, the inner end portion 5e extends in a substantially radial direction with a slight
inclination, and the connecting portion main body 5d 'connected to the inner end portion 5e
extends substantially along the outer periphery of the inner circumferential annular portion 5b.
The end portion 5f extends in a substantially radial direction while being slightly inclined, and is
connected to the outer circumferential ring portion 5c. As described above, the butterfly damper
5 has a high stroke property due to the above-described shape, and the strength in the radial
direction is improved by the inner and outer ends 5e and 5f extending in the diagonal radial
direction of the connecting portion 5d. The centering property of the voice coil bobbin 4 is good.
Although the butterfly damper 5 of the illustrated example has four connecting portions 5 d, the
number of the connecting portions 5 d can of course be appropriately increased or decreased
according to the diameter of the voice coil bobbin 4. In operation, when an audio signal is applied
to the voice coil 6, the diaphragm 1 vibrates accordingly, but the edge of the diaphragm 1 is
mechanical because it consists of the fluid edge 2 which encloses the magnetic fluid 2b. There is
no limitation of stroke. Further, since the magnet 2 a of the fluid edge 2 is joined to the vibration
system side, the magnetic fluid also moves simultaneously with the vibration system, and the
effective vibration diameter can be maximized for the speaker diameter. Further, since the
damper uses the butterfly damper 5, it is possible to take a sufficiently large stroke even with a
small diameter. Further, since the magnetic fluid 2 b is supported, there is no limitation on the
rotational movement, the stress is not applied to the butterfly damper 5, and the strength is
improved. Since there is nothing to impede the rotational movement of the butterfly damper 5,
the butterfly damper 5 can be designed to actively incorporate the rotational movement in order
to achieve a high stroke, and the degree of freedom in design is increased.
The rotational movement of the vibration system increases the apparent mass due to inertia, and
has the effect of lowering the f0 of the speaker. The butterfly damper 5 of the present invention
has good centering ability, but since the edge encloses the magnetic fluid 2 b, it is possible to
compensate for the defect in centering ability of the butterfly damper 5. The control of Q can be
easily adjusted by the viscosity of the magnetic fluid 2b. Embodiment 2 FIG. 2 shows a second
embodiment of the present invention. In this embodiment, most of the diameter of the speaker is
acoustically effective so that the magnet 2a of the fluid edge 2 is joined to the diaphragm 1 side
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and the butterfly damper 5 is positioned and supported inside the voice coil bobbin 4 It is
characterized in that it can be In this case, the outer peripheral portion of the butterfly damper 5
is coupled to the inside of the voice coil bobbin 4, and the inner peripheral portion of the
butterfly damper 5 is supported by a support portion 12 erected at the central portion of the
pole piece 11. The other configuration, operation and the like are substantially the same as in the
first embodiment. Third Embodiment FIG. 3 shows a third embodiment of the present invention.
This embodiment differs from the second embodiment in that the magnet 2a of the fluid edge 2
is provided on the inner peripheral side of the support member 3 on the frame side. Other
configurations and actions are substantially the same as those of the above-described
embodiment. Fourth Embodiment FIG. 4 shows a fourth embodiment of the present invention.
This embodiment is characterized in that the outer peripheral portion of the cone-shaped
diaphragm 1A is supported by the fluid edge 2, and the butterfly damper 5 is provided on the
outer peripheral side of the voice coil bobbin 4 for support. The fluid edge 2 includes a magnetic
fluid 2 b provided on the outer peripheral side of the diaphragm 1 A, a ring-shaped magnet 2 a
provided outside the magnetic fluid 2 b, and a magnet magnetized in the axial direction It is
comprised by the ring-shaped magnetic board 2c provided in the upper and lower surface of 2a,
respectively. In this case, a flange portion 1a bent downward is formed on the outer peripheral
portion of the diaphragm 1A. The outer peripheral side of the magnet 2a is provided and
supported by a support member (not shown) on the frame side. The outer peripheral portion of
the butterfly damper 5 is also supported by the support member on the frame side. In this
embodiment, the magnetic plate 2c is joined to the upper and lower sides of the magnet 2a to
form a magnetic path, thereby enhancing the holding power of the magnetic fluid 2b. In the
figure, 1 B is a dustproof center cap.
Further, in this example, the magnetic circuit 7 is an external magnet type including an inverted
T-shaped yoke 9 ', a ring magnet 10' and a ring plate 11 '. Other configurations, actions, and the
like are substantially the same as those of the above-described embodiment. FIG. 5 shows the
frequency characteristic diagram of the present invention as compared to the conventional small
aperture dome speaker of φ28. The solid line indicates the product of the present invention, and
the broken line indicates the conventional product. According to the present invention, since a
sufficiently high stroke can be obtained, the sound pressure in the low range can be improved,
and a sufficient bass can be obtained even with a small aperture speaker. As described above,
according to the present invention, the ring-shaped magnet 2a provided on the side of the outer
peripheral portion of the diaphragm 1 or on the side of the frame oppositely disposed facing
away from the diaphragm 1 is provided. And a magnetic fluid 2b for supporting the diaphragm 1
by suction and held by the magnet 2a; and a butterfly damper 5 for supporting a voice coil
bobbin 4 coupled to the diaphragm 1; An inner circumferential ring portion 5b coupled to the
coil bobbin 4 side and an outer circumferential ring portion 5c concentrically formed on the
outer side of the inner circumferential ring portion 5b, the outer circumferential ring portion 5c
and the inner portion The magnetic fluid 2b for supporting the diaphragm 1 is connected
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between the circumferential annular portion 5b by a strip-like coupling portion extending
substantially in the radial direction and an arc-like coupling portion extending along the inner
circumferential annular portion 5b. 2a adsorbed and held A pull configuration, a magnetic circuit
for the magnetic fluid retention because of the compact a simple configuration, can be an
effective vibration diameter maximally speaker diameter. Further, since the voice coil bobbin is
supported by the butterfly damper 5 having a high stroke property, a large stroke can be
obtained even with a small diameter, and the bass characteristic can be improved. Further, since
the butterfly damper 5 has the connecting portion extending substantially in the radial direction,
the strength in the radial direction is improved, the centering property of the voice coil bobbin 4
is improved, and the rubbing can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1
(a) is a schematic half sectional view of a loudspeaker according to a first embodiment of the
present invention, and FIG. 1 (b) is a plan view of a butterfly damper used in the present
invention. FIG. 2 shows a schematic half sectional view of a loudspeaker according to a second
embodiment of the present invention. FIG. 3 shows a schematic half sectional view of a
loudspeaker according to a third embodiment of the present invention. FIG. 4 shows a schematic
half sectional view of a loudspeaker according to a fourth embodiment of the present invention.
FIG. 5 shows a frequency characteristic diagram of the present invention. FIG. 6 (a) is a schematic
half sectional view of a speaker according to a conventional example, and FIG. 6 (b) is a
schematic half sectional view of another conventional example.
FIG. 7 is a plan view of a conventional butterfly damper. FIG. 8 shows still another conventional
example of a speaker. FIG. 9 shows another prior art example. FIG. 10 shows another prior art
example. FIG. 11 shows another conventional example. Explanation of mark 1, 1A diaphragm 1a
flange part 2 edge 2a magnet 2b magnetic fluid 2c magnetic board 3 support member 4 voice
coil bobbin 5 butterfly damper 5a hole 5b inner circumference annular part 5c outer
circumference annular part 5d connection part 5d ' Coupling body 5e inner end 5f outer end 6
voice coil 7 magnetic circuit 8 magnetic gap 9, 9 'yoke 10, 10' magnet 11, 11 'plate 12 support
portion
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