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JP2009201005

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DESCRIPTION JP2009201005
PROBLEM TO BE SOLVED: To provide an electrodynamic speaker including an elongated coil
having a major axis direction and a minor axis direction, a voice coil including an elongated
bobbin, and an elongated diaphragm and an edge on which the bobbin is fixed at its center.
Provided is an electrodynamic speaker capable of suppressing peak-dip of reproduced sound
pressure frequency characteristics, having high efficiency, sufficiently high reproduced sound
pressure level, and excellent reproduced sound quality. SOLUTION: A movable supporting
portion of an edge has a long side roll portion corresponding to a track-shaped long side of an
inner peripheral portion and a short side roll portion corresponding to an arc of the inner
peripheral portion, The cross-sectional shape and size of the part is substantially equal to the
cross-sectional shape and size of the long side roll part in the connection with the long side roll
part and in the minor axis direction, and the connection angle with the long side and the short
side of the outer peripheral part of the edge It gradually changes so that the roll width becomes
the largest in the vicinity corresponding to the part. [Selected figure] Figure 4
Electrodynamic speaker
[0001]
The present invention relates to an elongated electrodynamic speaker having a short diameter
direction shorter than the major axis direction, which is excellent in sound reproduction
capability and suitable for being attached to a device such as a display.
[0002]
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1
In audio equipment such as a display to which a speaker for reproducing sound is attached, it is
required to miniaturize a space required to attach the speaker.
In particular, the elongated (rectangular, oval (elliptical, track, etc.)) electrodynamic speaker is
affected by the divided vibration unique to the elongated speaker diaphragm in which the
diaphragm area is limited in the minor axis direction. It is difficult to obtain a large, flat
reproduction sound pressure frequency characteristic. If it is attempted to adopt a speaker
magnetic circuit having a high magnetic flux density in the magnetic gap, the width of the
magnetic circuit becomes wider than the speaker diaphragm and can not be miniaturized. There
are disadvantages in audio playback capabilities for various reasons. Therefore, in order to solve
these problems, various speaker diaphragms, edges, magnetic circuits for speakers, and
electrodynamic speakers using the same have been proposed.
[0003]
In the case of a conventional elongated speaker, in the case of including a diaphragm having a
major axis direction and a minor axis direction such as an oval (track shape or oval), the inner
peripheral portion of the edge supporting the diaphragm is It is often formed in an oval (track
shape or oval) along the shape of the outer peripheral end of the diaphragm. On the other hand,
for example, it is connected to the outer periphery of an elliptical or non-circular diaphragm, and
the width on the minor axis direction side is narrower than the width on the major axis direction
side of the diaphragm, and There is an edge for a speaker which made the length dimension at
the time of unfolding equalized (patent documents 1).
[0004]
Also, for example, it has a substantially elongated circular diaphragm and an elongated external
shape larger than the diaphragm, and the diaphragm is disposed at the approximate center to
support the diaphragm and to surround the diaphragm. Each frame has a substantially frame
shape including an edge formed by forming a roll portion projecting in a substantially arc-shaped
vibration direction, and a pair of longitudinal frames and a pair of short frames. The edge of the
edge is fixed, and the frame supports the diaphragm so as to vibrate freely through the edge, and
the roll portions face each other along the longitudinal direction of the edge. In an electroacoustic transducer formed in a track shape comprising a pair of longitudinal portions and a pair
of arc-shaped portions connecting the pair of longitudinal portions at both ends thereof, the roll
portion includes the longitudinal portions and the arc-shaped portion Cross section near the
connecting part Kicking width and the projecting height, there is are speakers have progressively
larger so formed portion toward from the connecting portion near the top of the arc-shaped
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2
portion (Patent Document 2).
[0005]
On the other hand, conventionally, in the case of a so-called square speaker provided with a
diaphragm having a substantially rectangular edge at the joint with the roll edge, the roll inner
curvature of the arc portion of the roll edge coupled to the corner of the diaphragm There is a
square speaker which makes the same as or larger than the outer curvature (Patent Document 3).
Since the width of the roll of the edge portion coupled to the corner portion of the diaphragm is
larger than that of the linear portion and the inner circumferential curvature of the roll is large,
the increase of the compliance due to the expansion and contraction in the circumferential
direction is suppressed In general, the edge compliance can be reduced, thereby reducing the
lowest resonance frequency and expanding the low frequency reproduction capability.
[0006]
JP, 7-46690, A (Fig. 1, Fig. 2) JP, 2004-297315, A (Fig. 6-Fig. 8) A real fair 3-14878 (Fig. 1 a-2 b)
[0007]
However, none of the prior art speakers is sufficient.
The speaker described in Patent Document 2 is a special speaker having a track shape having
almost the same size as the outer diameter of the voice coil bobbin and the diaphragm outer
diameter, and the voice coil bobbin is at the center of the diaphragm. It is not always suitable for
the long and thin speakers fixing the In addition, when connecting a circular voice coil and a
bobbin to the center of the diaphragm, although the edge described in Patent Document 1 or 3 is
effective, in the case of an elongated speaker such as a track or oval diaphragm Since the
diameter of the circular voice coil to be used is limited so as not to protrude from the elongated
diaphragm, the length of the voice coil located in the magnetic gap of the magnetic circuit
becomes short, as a result, the efficiency and There is a problem that the playback sound
pressure level is low and the speaker is poor in input resistance.
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3
[0008]
The present invention has been made to solve the above-mentioned problems of the prior art,
and its object is to provide an elongated coil having a major axis direction and a minor axis
direction, and a voice coil including an elongated bobbin. With regard to an electrodynamic
speaker having an elongated diaphragm and an edge in which a bobbin is fixed at its center,
peak-dip of reproduced sound pressure frequency characteristics can be suppressed, efficiency is
high, and reproduced sound pressure level is sufficiently high. An object of the present invention
is to provide an electrodynamic speaker excellent in reproduced voice quality.
[0009]
The electrodynamic speaker according to the present invention comprises a voice coil including
an elongated coil having a major axis direction and a minor axis direction and a elongated
bobbin, an elongated diaphragm in which the bobbin is fixed at its center, and a diaphragm An
electrodynamic type comprising an elongated peripheral edge including an inner peripheral
portion joined to the outer peripheral end, an outer peripheral portion joined to the fixed portion
of the frame, and a support movable portion connecting the inner peripheral portion and the
outer peripheral portion A speaker, wherein the outer peripheral end of the diaphragm and the
inner peripheral portion of the edge are formed by a pair of long sides along a major axis
direction and a pair of arcs connecting the pair of long sides. The outer periphery of the edge and
the fixed part of the frame are formed of a pair of long sides along the major axis direction and a
pair of short sides along the minor axis connecting the pair of long sides. The support movable
portion is a long side corresponding to the long side of the track shape on the inner peripheral
portion. And a short side roll portion corresponding to the arc of the inner peripheral portion,
and the cross sectional shape and the dimensions of the short side roll portion are connected to
the long side roll portion and the long side roll in the short diameter direction The roll width is
gradually changed so as to be the largest in the vicinity of the cross-sectional shape and size of
the part and in the vicinity corresponding to the connection corner with the long side and the
short side of the outer periphery of the edge.
[0010]
Preferably, in the electrodynamic speaker according to the present invention, a first roll portion
in which the cross-sectional shape of the long side roll portion of the support movable portion of
the edge is continuously formed on the planar inner peripheral portion, and a first roll portion
And a second roll portion formed continuously.
[0011]
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Preferably, in the electrodynamic speaker according to the present invention, the cross-sectional
shape of the short side roll portion of the support movable portion of the edge is a first roll
portion defined by the radius r1, and 0.25 times to 1.0 of the radius r1. A second roll portion
defined by a radius r2 set in a double range, and defining a first roll portion in the vicinity
corresponding to a connecting corner portion with a long side and a short side of an outer
peripheral portion of an edge The radius R1 is set in the range of 2.0 times to 4.0 times the
radius r1, and the radius R2 defining the second roll portion is in the range of 2.0 times to 4.0
times the radius r2. It is set.
[0012]
Preferably, in the electrodynamic speaker according to the present invention, the elongated edge
has a front edge having a long side roll portion having a substantially convex cross-sectional
shape, and a rear edge obtained by inverting the front edge back and forth In particular, the
inner periphery of the front edge is connected to the front of the outer peripheral end of the
diaphragm, and the inner periphery of the rear edge is connected to the rear of the outer
peripheral end of the diaphragm.
[0013]
In addition, preferably, the electrodynamic speaker according to the present invention further
comprises an elongated frame having a fixed portion, and a magnetic circuit connected to the
frame and having an elongated magnetic gap, and the elongated voice coil A coil is placed in the
magnetic air gap.
[0014]
Hereinafter, the operation of the present invention will be described.
[0015]
The electrodynamic speaker according to the present invention comprises a voice coil including
an elongated coil having a major axis direction and a minor axis direction and a elongated
bobbin, an elongated diaphragm in which the bobbin is fixed at its center, and a diaphragm An
electrodynamic type comprising an elongated peripheral edge including an inner peripheral
portion joined to the outer peripheral end, an outer peripheral portion joined to the fixed portion
of the frame, and a support movable portion connecting the inner peripheral portion and the
outer peripheral portion It is a speaker.
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Preferably, the apparatus further comprises an elongated frame having a fixed part, and a
magnetic circuit connected to the frame and having an elongated magnetic gap, wherein the
elongated coil of the voice coil is disposed in the magnetic gap.
Therefore, even if the space to which the audio device is attached is narrow, it is possible to
realize an elongated electrodynamic speaker that can be attached with excellent reproduction
sound quality.
[0016]
In the electrodynamic speaker according to the present invention, the outer peripheral end of the
diaphragm and the inner peripheral part of the edge are composed of a pair of long sides along
the major axis direction and a pair of arcs connecting the pair of long sides. The outer periphery
of the edge and the fixed portion of the frame are formed in the form of a track, and the fixed
portion of the frame is a pair of long sides along the major axis direction and a pair of short sides
along the minor axis direction connecting the pair of long sides. And a substantially rectangular
shape.
Therefore, the support movable portion of the edge has a long side roll portion corresponding to
the track-shaped long side of the inner peripheral portion and a short side roll portion
corresponding to the arc of the inner peripheral portion. The cross-sectional shape and size of
the part is substantially equal to the cross-sectional shape and size of the long side roll part in
the connection with the long side roll part and in the minor axis direction, and the connection
angle with the long side and the short side of the outer peripheral part of the edge It gradually
changes so that the roll width becomes the largest in the vicinity corresponding to the part.
That is, in the connection corner portion of the edge, the cross-sectional shape and the size of the
short side roll portion become larger than the short diameter direction of the long side roll
portion and the short side roll portion.
[0017]
Specifically, the first roll portion, which has a cross-sectional shape of the long side roll portion
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6
of the support movable portion of the edge and which is continuously formed without having a
bending point on the planar inner peripheral portion, and the first roll portion And a second roll
portion formed continuously without having a bending point.
That is, the first roll portion is a concave roll portion, and the radius r1 defining the same is set in
the range of 0.25 times to 1.0 times the radius r2 defining the second roll portion which is a
convex roll portion. Be done.
Also, in the vicinity corresponding to the connecting corner portion with the long side and the
short side of the outer peripheral portion of the edge, the radius R1 defining the first roll portion
is 2 of the radius r1 defining the first roll portion of the long side roll portion .0 to 4.0 times, and
the radius R2 defining the second roll portion 2.0 to 4.0 times the radius r2 defining the second
roll portion of the long side roll portion It is set in the double range.
[0018]
Therefore, in the electrodynamic speaker according to the present invention, by making the
shape of the elongated edge as described above, the elongated diaphragm in which the bobbin of
the voice coil is fixed to the center of the diaphragm is compared. It is possible to obtain a
substantially flat reproduced sound pressure frequency characteristic.
That is, since the cross-sectional shape and the size of the short side roll portion of the edge are
gradually changed, the elongated voice coil is used to secure the voice coil length located in the
magnetic gap of the magnetic circuit. Even with the electrodynamic speaker, the divided vibration
of the diaphragm is suppressed, the efficiency and the reproduction sound pressure level can be
increased, and the reproduction sound quality and the input resistance can be improved.
[0019]
In addition, preferably, in the electrodynamic speaker, the elongated edge includes a front edge
having a long side roll portion having a substantially convex cross-sectional shape, and a rear
edge obtained by inverting the front edge back and forth. The inner peripheral portion of the
edge may be connected to the front side of the outer peripheral end of the diaphragm, and the
inner peripheral portion of the rear edge may be connected to the rear side of the outer
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7
peripheral end of the diaphragm. In addition, cross-sectional shape substantially convex shape
shows a mode that the whole shape in a cross section protrudes on one side on the basis of a
planar inner peripheral part or outer peripheral part like the edge of this invention. By providing
the front edge and the rear edge, the anteroposterior symmetry of the amplitude displacement of
the diaphragm is improved, and the even-order distortion represented by the second distortion
and the reproduction voice quality with less operation defects such as rolling Can provide an
electrodynamic speaker excellent in
[0020]
An electrodynamic speaker according to the present invention comprises an elongated coil
having a major axis direction and a minor axis direction and a voice coil including an elongated
bobbin, an elongated diaphragm and an edge on which the bobbin is fixed at its center. Even with
an electrodynamic speaker, it is possible to suppress peak and dip in reproduced sound pressure
frequency characteristics, to provide an electrodynamic speaker with high efficiency, sufficiently
high reproduced sound pressure level, and excellent reproduced sound quality. Can.
[0021]
The electrodynamic speaker according to the present invention is characterized in that the outer
peripheral end of the diaphragm and the inner peripheral part of the edge connect a pair of long
sides along a major axis direction with a pair of long sides. The track shape is formed of a set of
arcs, and the outer peripheral portion of the edge and the fixed portion of the frame are
connected in the minor axis direction connecting the pair of long sides with the pair of long sides
along the major axis direction And a pair of short sides along which the support movable portion
is a long side roll portion corresponding to the track-shaped long side of the inner peripheral
portion and a short side corresponding to the arc of the inner peripheral portion Side roll
portion, and the cross-sectional shape and size of the short side roll portion are substantially
equal to the cross-sectional shape and size of the long side roll portion in the short diameter
direction with the connecting portion with the long side roll portion and The roll width becomes
the largest in the vicinity corresponding to the connection corner with the long side and the
short side of the outer peripheral part By you gradually change to cormorants, it was realized.
[0022]
The following describes the electrodynamic speaker according to the preferred embodiments of
the present invention, but the present invention is not limited to these embodiments.
[0023]
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8
FIG. 1 is a view for explaining an electrodynamic speaker 1 according to a preferred embodiment
of the present invention.
FIG. 1A is a perspective view of the electrodynamic speaker 1 as viewed from the front upper
side, and FIG. 1B is a perspective view of the magnetic circuit 10 constituting the electrodynamic
speaker 1 from the front upper side. It is an enlarged perspective view.
The electrodynamic speaker 1 of the present embodiment is a slender electrodynamic speaker
having a track-shaped speaker diaphragm 2 having a length of about 15.0 cm in the major axis
direction and a length of about 2.5 cm in the minor axis direction.
In addition, as described later, a part of the structure of the electrodynamic speaker 1, an internal
structure, and the like are omitted. The direction in which the straight line connecting points A-A
'extends is the major axis direction, and the direction in which the straight line connecting points
B-B' extends is the minor axis direction.
[0024]
The speaker diaphragm 2 whose outer shape and inner shape have a track shape is a flat
diaphragm in which foam PP is press-formed, its outer peripheral end is supported by the edge 3,
and the outer peripheral end of the edge 3 is a frame 6 It is fixed to A voice coil 4 (not shown)
consisting of a bobbin and a coil is connected to the inner peripheral end of the speaker
diaphragm 2, and a dome-shaped dust cap 5 whose outer shape is a track is adhered to the upper
end ing. Here, the track shape is a shape formed of a pair of long sides along the major axis
direction and a pair of arcs connecting the pair of long sides, and the outer peripheral end of the
speaker diaphragm 2 The inner peripheral end of the edge 3 has a pair of long sides and a pair of
arcs connecting the pair of long sides. The speaker diaphragm 2 may be a flat diaphragm on
which PSP, PP, paper, aluminum alloy or the like is press-formed. Alternatively, the speaker
diaphragm 2 may be formed by punching flat materials each having a thin plate shape. .
[0025]
Further, the frame 6 has an elongated shape corresponding to the track-shaped speaker
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9
diaphragm 2, and the magnetic circuit 10 fixed to the frame 6 also has an elongated shape
having a narrow width equal to or less than the length in the short diameter direction.
Specifically, the fixed portion of the frame 6 is substantially formed of a pair of long sides along
the major axis direction and a pair of short sides along the minor axis connecting the pair of long
sides. It is rectangular and has an outer diameter of about 17.0 cm and an outer diameter of
about 3.0. From the window (not shown) on the back side of the frame 6, parts constituting the
vibration system such as the voice coil 4 are exposed. Therefore, the electrodynamic speaker 1 is
a speaker suitable for a device having a small width for attaching the speaker, such as a side
portion of a display unit of a device such as a display.
[0026]
The magnetic circuit 10 has an elongated top plate 11 fixed to the frame 6 and a center pole 12
inserted in a track shaped hole formed in the center of the top plate 11 which has a track-shaped
long cylindrical shape. And an elongated under plate 14 for centering the center pole 12 and a
magnet 15 held between the top plate 11 and the under plate 14. The top plate 11 and the
center pole 12 form a track-shaped magnetic air gap 13 having a uniform width. That is, the
magnetic circuit 10 is an external magnet type magnetic circuit having the track-type magnetic
gap 13, and the major axis direction and the minor axis direction of the magnetic circuit 10 are
the same as the major axis direction and the minor axis direction of the track type speaker
diaphragm 2. I do.
[0027]
The voice coil 4 (not shown) is formed of a bobbin whose cross-sectional shape is formed in a
track-shaped long cylindrical shape, and a coil wound around one end side and supplied with an
audio current. The bobbin is connected to the inner peripheral end of the speaker diaphragm 2
with an adhesive agent at the outer side near the other end where the coil is not wound. The
voice coil 4 is vibratably supported by the edge 3 through the speaker diaphragm 2, and the
track-shaped coil is disposed in the track-shaped magnetic gap 13 of the magnetic circuit 10. The
length in the major axis direction of the coil is about 22.0 mm, the length in the minor axis
direction is about 6.0 mm, and the radius of the track-shaped arc is about 3.0 mm. Therefore, the
speaker vibration system including the speaker diaphragm 2, the edge 3, the voice coil 4 and the
dust cap 5 is vibratably supported on the frame 6. In the electrodynamic speaker 1, when an
audio current is supplied to the coil of the voice coil 4, a driving force acts on the voice coil 4
disposed in the magnetic gap 13, and the voice coil 4 vibrates in the front-rear direction and is
connected The speaker diaphragm 2 also vibrates in the front-rear direction. In the
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electrodynamic speaker 1, when the speaker diaphragm 2 vibrates, the side on which the voice
coil 4 and the magnetic circuit 10 are attached is the rear side, and the speaker diaphragm 2 and
the dust cap 5 are referred to as front and rear. The side where is exposed is the front side.
[0028]
2 and 3 are views for explaining the edge 3 according to a preferred embodiment of the present
invention, FIG. 2 is a plan view of the edge 3 and FIG. 3 is a partial sectional view of the edge 3 in
FIG. is there. The edge 3 is, for example, a substantially annular shape obtained by injecting a
foamed rubber into the inside of a mold, hot press molding and foaming to obtain a
predetermined shape, and cutting the inner peripheral side and the outer peripheral side with a
cutting die It is a speaker edge formed in the shape of a slender roll edge. The edge 3 has a
thickness of approximately 0.2 mm, a length in the major axis direction of approximately 150
mm, and a length in the minor axis direction of approximately 25.0 mm. The inner diameter of
the edge 3 is about 135.8 mm in the major axis direction, about 11.2 mm in the minor axis
direction, and about 5.6 mm for the track-shaped arc. The edge 3 is formed, for example, by
impregnating a woven fabric in which a plurality of warps and wefts of cotton and polyester
fibers are substantially orthogonal to form a rubber as a base material, heat molding with a mold,
and cutting the inner periphery and outer periphery It may be an elongated roll edge.
[0029]
As shown in the partial cross-sectional view in the minor axis direction of FIG. 3, the edge 3 has a
track-shaped planar inner circumferential portion 31 joined to the outer peripheral end of the
speaker diaphragm 2 and a plane joined to the frame 6. A track-shaped outer peripheral portion
32 and a support movable portion 33 configured in a roll shape in which a cross section in the
radial direction connecting the inner peripheral portion 31 and the outer peripheral portion 32 is
continuous. The movable support portion 33 has a concave roll portion 33a continuously formed
without a bending point on the planar inner peripheral portion 31 and a convex continuously
formed without a bending point in the concave roll portion 33a. And the third roll portion 33b.
Specifically, for example, in the B-O cross section in the minor axis direction, the width Lw of the
support movable portion 33 is about 2.5 mm, and the radius r1 defining the concave roll portion
33a is about 1.67 mm, the convex The radius r2 defining the second roll portion 33b is about
0.75 mm. The radius r2 defining the convex roll 33b is preferably set in the range of 0.25 times
to 1.0 times the radius r1 defining the concave roll 33a, and in the case of this embodiment, the
radius r2 is about 0.44 times the radius r1. Further, the maximum height of the support movable
portion 33 of the edge 3 is substantially constant over the entire circumference, and is about 1.5
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11
mm.
[0030]
Then, as shown in the plan view of FIG. 2, the support movable portion 33 of the edge 3 has a
long side roll portion 34 x corresponding to the track-shaped long side 34 of the inner peripheral
portion 31 and an arc 35 of the inner peripheral portion 31. And the short side roll part 35x
corresponding to. Further, the outer peripheral portion 33 of the edge 3 has a pair of long sides
36 along the major axis direction and a pair of short sides 37 along the minor axis direction
connecting the pair of long sides 36 There is. In FIG. 2, the length L 1 a in the major axis
direction is the length of the long side 34 of the inner peripheral portion 31, and similarly, the
length L 2 a in the major axis direction is the length of the long side 36 of the outer peripheral
portion 33. Further, the length L1b in the minor axis direction is the diameter of the arc 35 of the
inner peripheral portion 31, and, similarly, the length L2b in the minor axis direction is the
length of the short side 37 of the outer peripheral portion 33.
[0031]
In the long side roll portion 34 x constituting the support movable portion 33 of the edge 3, the
roll shape shown in the sectional view of FIG. 3 continues over the long side 34 of the track
shape of the inner peripheral portion 31. That is, in the portion corresponding to the length L1a
of the long side 34 of the inner peripheral portion 31, the edge 3 has the same roll width Lw and
cross sectional shape, and the short side roll portion 35x corresponding to the arc 35 of the
inner peripheral portion 31. In the above, the cross-sectional shape in the normal direction of the
arc 35 changes as the angle defining the arc 35 changes. This corresponds to the substantially
rectangular shape of the fixed portion of the frame 6 while the inner peripheral portion 31 of the
edge 3 is a track shape corresponding to the track shape of the speaker diaphragm 2. It is
because it has a substantially rectangular shape. That is, the edge 3 gradually changes so that the
roll width Lw 'becomes the largest in the vicinity corresponding to the connecting corner 38 with
the long side 36 and the short side 37 of the outer peripheral portion 32 thereof. In the case of
the present embodiment, the outer end of the connecting portion 38 formed by the long side 36
and the short side 37 of the outer peripheral portion 33 is edged by a small arc as shown in the
plan view of FIG. There is.
[0032]
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12
FIG. 4 is a view for explaining a change in the cross-sectional shape of the connecting portion 38
of the edge 3. That is, in the short side roll portion 35x formed subsequently to the long side roll
portion 34x of the edge 3, the change in the cross sectional shape and the roll width Lw 'is
explained by a cross sectional view at 15 ° intervals. is there. The cross-sectional shape of the
short side roll portion 35 x includes a concave roll portion 33 a in the long side roll portion 34 x
and a convex roll portion 33 b. First, at 0 ° shown in FIG. 4A, the cross-sectional shape and
dimensions of the short side roll portion 35x are substantially equal to the cross-sectional shape
and the roll width Lw of the long side roll portion 34x. At 15 ° shown in FIG. 4B and 30 °
shown in FIG. 4C, the cross-sectional shape and dimensions of the short side roll portion 35x
change, and the roll width Lw ′ is compared to the roll width Lw at 0 ° growing. In FIG. 4D, 45
° corresponds to the connecting corner 38 where the long side 36 and the short side 37 join,
and the short side roll 35x has the largest roll width Lw '. Furthermore, at 60 ° shown in FIG. 4
(e) and 75 ° shown in FIG. 4 (f), the cross-sectional shape and dimensions of the short side roll
portion 35x change, and the roll width Lw 'becomes smaller. Then, the cross-sectional shape and
dimensions of the short side roll portion 35x become substantially equal to the cross-sectional
shape of the long side roll portion 34x and the roll width Lw again in the minor axis direction of
90 ° shown in FIG. ing.
[0033]
Specifically, in the case of the present embodiment, the largest roll width Lw 'at the connecting
corner portion 38 is at 45 ° shown in FIG. 4D, and the roll width Lw' is about It will be 4.27 mm.
Further, the cross-sectional shape of the short side roll portion 35 x is a shape in which the
concave roll portion 33 a and the convex roll portion 33 b are spread. Assuming that the radius
defining the concave roll 33a at the connection corner 38 is R1 and the radius defining the
convex roll 33b is R2, the radius R1 is approximately 5.41 mm, and the radius R2 is
approximately 2.73 mm. . The radius R1 is about 3.24 times the radius r1 defining the concave
roll 33a in the long side roll 34x, and the radius R2 defines the convex roll 33b in the long side
roll 34x. It is about 3.64 times the radius r2. Thus, the radii R1 and R2 at the connecting corner
38 are preferably set in the range of 2.0 times to 4.0 times the radii r1 and r2, respectively.
[0034]
FIG. 5 is a graph showing the on-axis 1 m sound pressure frequency characteristics of the
electrodynamic speaker 1 including the speaker vibration system including the edge 3 of the
present embodiment. Since the electrodynamic speaker 1 of the present embodiment includes
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the edge 3 described above, the track-shaped speaker diaphragm 2 and the track-shaped voice
coil 4, the track-shaped voice coil and the elongated speaker diaphragm A smooth frequency
characteristic can be realized by suppressing division vibration at 300 Hz or more which is likely
to occur by the combination of the above. In addition, in the electrodynamic speaker 1 of the
present embodiment, since the edge 3 for realizing the above-mentioned frequency characteristic
is used, the track-shaped voice coil 4 and the magnetic circuit 10 having the track-shaped
magnetic gap 13 are obtained. Using it, it achieves a high playback sound pressure level of about
80 dB / m / W. That is, as understood in comparison with a comparative example to be described
later, the electrodynamic speaker is high in efficiency and excellent in reproduction sound quality
while being a slender speaker.
[0035]
FIG. 6 is a graph showing the on-axis 1 m sound pressure frequency characteristics of another
electrodynamic speaker (not shown) including another edge (not shown) of the comparative
example. 6 (a) is a graph showing the on-axis 1 m sound pressure frequency characteristics of
the electrodynamic speaker 101 of Comparative Example 1, and FIG. 6 (b) is 1 m of the
electrodynamic speaker 102 of Comparative Example 2. It is a graph showing a sound pressure
frequency characteristic. Because the electrodynamic speaker 1 of this embodiment and the
electrodynamic speaker of Comparative Example 1 or Comparative Example 2 have the same
configuration as the speaker diaphragm 2 and frame 6 other than the parts to be compared and
studied, Description of these will be omitted.
[0036]
The difference between the electrodynamic speaker 101 of Comparative Example 1 is the shape
of the edge 103 (not shown) and the shapes of the voice coil 104 and the magnetic circuit 110
(not shown). That is, the edge 103 of Comparative Example 1 is a conventional edge shape in
which the cross-sectional shape of the support movable portion and the roll width do not change
over the entire circumference of the track shape, and the roll width is constant at about 2.5 mm.
Further, the voice coil 104 of Comparative Example 1 is a circular voice coil having a diameter of
about 6.0 mm having a circular bobbin, and the corresponding magnetic circuit 110 also has a
circular magnetic air gap 113 with a small radius. . As a result, as shown in FIG. 6A, the on-axis 1
m sound pressure frequency characteristic in which the peak and dip repeatedly appear in the
frequency band of 300 Hz to 10 kHz. In addition to the fact that the magnetic circuit 110 is
smaller than the magnetic circuit 10 of the present embodiment, the coil length of the circular
voice coil 104 disposed in the magnetic gap 113 of the magnetic circuit 110 is the same as that
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14
of the present embodiment. Since it becomes shorter than the track-shaped voice coil 4, the
electrodynamic speaker 101 of Comparative Example 1 remains at a low reproduction sound
pressure level of about 72 dB / m / W, and electrodynamic inferior to reproduction sound
quality. Type speaker.
[0037]
On the other hand, the only difference between the electrodynamic speaker 102 of Comparative
Example 2 is the shape of the edge 103 (not shown). That is, the edge 103 of Comparative
Example 2 is the same as the case of Comparative Example 1 above, and is a conventional edge
shape in which the cross-sectional shape and the roll width of the support movable portion do
not change over the entire circumference of the track shape. The roll width is constant at about
2.5 mm. Further, in the second comparative example, the voice coil 104 and the magnetic circuit
10 have the same track shape as the present embodiment, the reproduction sound pressure level
is about 78 dB / m / W, and the overall reproduction as in the first comparative example. There
is no reduction in sound pressure level and no reduction in efficiency. However, in the case of
Comparative Example 2, as shown in FIG. 6 (b), peak-dip repeatedly appears in the frequency
band of 300 Hz to 10 kHz, and the disturbance is larger than that in Comparative Example 1. . In
addition, the on-axis 1 m sound pressure frequency characteristic in which the level decreases
further greatly as it goes to the high region, this tends to be found in the speaker provided with
the elongated speaker diaphragm 2 provided with the track shaped voice coil 4 Thus, the
electrodynamic speaker 102 of Comparative Example 2 also becomes an electrodynamic speaker
inferior to the reproduction sound quality.
[0038]
Therefore, the electrodynamic speaker 1 of this embodiment fixes the bobbin of the track-shaped
voice coil 4 at the center of the track-shaped speaker diaphragm 2 by setting the shape of the
elongated edge 3 as described above. Even if it is a thing, comparatively flat reproduction sound
pressure frequency characteristics can be obtained. That is, since the cross-sectional shape of the
short side roll portion 35x of the edge 3 and the roll width Lw 'are made to gradually change
from the shape and size of the long side roll portion 34x, in the magnetic gap 13 of the magnetic
circuit 10. Even if the coil length of the voice coil 4 positioned is secured by adopting a trackshaped one, the divided vibration of the speaker diaphragm 2 can be suppressed. In addition, if
the efficiency and playback sound pressure level that are likely to be reduced by the elongated
electrodynamic speaker are increased, as a result, there is no need to input excessive audio signal
power and the rated input is also increased. It is possible to realize an electrodynamic speaker
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that is excellent in sound and has high input resistance and high quality.
[0039]
FIG. 7 is a view for explaining an electrodynamic speaker 1a (not shown) according to another
preferred embodiment of the present invention, and an enlargement of an edge portion in the
short diameter direction (B-O cross section) of the electrodynamic speaker 1a. FIG. That is, the
electrodynamic speaker 1a of this embodiment differs from the electrodynamic speaker 1 of the
previous embodiment in the configuration of the elongated edge 3 joined to the outer peripheral
end of the speaker diaphragm 2 in the embodiment. Specifically, the front edge 3 having the
substantially convex long side roll portion 34x and the rear edge 3Z having a shape obtained by
inverting the front edge 3 back and forth with the cross-sectional shape described in the previous
embodiment , Is included.
[0040]
The front edge 3 has a track-shaped planar inner periphery 31 joined with the outer peripheral
end of the speaker diaphragm 2 and a track-shaped outer periphery 32 provided with a plane
joined with the frame 6 as in the previous embodiment. And a support movable portion 33
configured by a roll shape in which a cross section in the radial direction connecting the inner
peripheral portion 31 and the outer peripheral portion 32 is continuous. Therefore, the movable
support portion 33 has a shape including the concave roll 33a and the convex roll 33b, and
forms a substantially convex roll edge in which the convex roll 33b largely protrudes to the front
side. ing. The inner peripheral portion 31 of the front edge 3 is connected to the front side of the
outer peripheral end of the speaker diaphragm 2, and the outer peripheral portion 32 of the
front edge 3 is connected to the front side of the fixed portion of the frame 6.
[0041]
On the other hand, the rear edge 3Z may have a shape obtained by inverting the front edge 3
back and forth, and may use the edge 3 formed through the same manufacturing process as
being reversed. Therefore, the support movable portion 33 of the rear edge 3Z has a shape
including the concave roll portion 33a and the convex roll portion 33b, and contrary to the front
edge 3, the convex roll portion 33b is largely rear It forms a roll edge protruding to the side. The
inner peripheral portion 31 of the rear edge 3Z is connected to the rear side of the outer
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peripheral end of the speaker diaphragm 2, and the outer peripheral portion 32 of the rear edge
3Z is connected to the rear side of the fixed portion of the frame 6. doing.
[0042]
Therefore, since the electrodynamic speaker 1a of this embodiment includes the front edge 3 and
the rear edge 3Z obtained by inverting the front edge 3 back and forth, when the speaker
diaphragm 2 is displaced in amplitude, the roll edge The anteroposterior asymmetry associated
with the shape is offset, as a result of which the anteroposterior symmetry is improved. Since the
front-back symmetry affects even-order distortion represented by second-order distortion, an
electrodynamic speaker 1a excellent in reproduced sound quality with less distortion can be
realized. In addition, it is possible to provide an electrodynamic speaker having high input
resistance and excellent in reproduced sound quality, since it is difficult for occurrence of
operation failure such as rolling of the speaker vibration system to occur.
[0043]
Moreover, the edge 3 which comprises the electrodynamic-type speaker of this invention is not
limited when shape | molding from the foamed rubber of the said Example, Materials, such as
urethane foam, may be sufficient. The elastic material forming the speaker edge may be molded
by, for example, injecting rubber or an elastomer into an injection mold. Further, the sheet of
elastomer may be press-molded.
[0044]
The electrodynamic speaker according to the present invention is not limited to a track-shaped
speaker diaphragm and a speaker using a track-shaped voice coil, and is driven by an elongated
diaphragm that emits sound waves, and the elongated diaphragm. The invention is also
applicable to other electro-mechanical-acoustic transducers that comprise other vibration
systems in which the drive member transmitting the force is a combination of elongated shapes.
[0045]
It is a figure explaining the electrodynamic-type speaker 1 by preferable embodiment of this
invention.
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(EXAMPLE 1) A diagram for explaining an edge 3 according to a preferred embodiment of the
present invention. (EXAMPLE 1) A diagram for explaining an edge 3 according to a preferred
embodiment of the present invention. (Example 1) It is a figure explaining the change of the
cross-sectional shape of the connection part 38 of the edge 3 by preferable embodiment of this
invention. (Example 1) It is a graph showing the on-axis 1-m sound pressure frequency
characteristic of the electrodynamic speaker 1 according to a preferred embodiment of the
present invention. (Example 1) It is a graph showing the on-axis 1 m sound pressure frequency
characteristic of the electrodynamic type speakers 101 and 102 of a comparative example.
Comparative Example 1 and Comparative Example 2 FIG. 6 is an enlarged sectional view of an
edge portion in the short diameter direction of the electrodynamic speaker 1 a according to
another preferred embodiment of the present invention. (Example 2)
Explanation of sign
[0046]
Reference Signs List 1 electrodynamic speaker 2 speaker diaphragm 3 edge 5 dust cap 6 frame
10 magnetic circuit 11 top plate 12 center pole 13 magnetic gap 14 under plate 15 magnet 31
inner circumferential portion 32 outer circumferential portion 33 supporting movable portion 34
length of inner circumferential portion Side 35 Short side of inner circumferential part 36 Long
side of outer circumferential part 37 Short side of outer circumferential part 38 Connecting
corner
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