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JP2009060571

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DESCRIPTION JP2009060571
PROBLEM TO BE SOLVED: To provide a long dynamic electrodynamic speaker having a short
diameter direction shorter than the long diameter direction, which is high in efficiency and
excellent in voice reproduction capability, and is less affected even if the long and narrow
speaker diaphragm is divided and vibrated A speaker diaphragm and an electrodynamic speaker
suitable for attaching to a device such as An elongated speaker diaphragm includes a first
diaphragm portion including a junction portion with a voice coil bobbin at a central portion on
the back side of the elongated diaphragm portion, and both end sides of the first diaphragm
portion in the long diameter direction. It has the 2nd diaphragm part extended, respectively, the
1st diaphragm part, and the reinforcement rib continuously formed over the 2nd diaphragm
parts of each, edge is the 1st vibration A free edge portion for freely supporting the end portion
in the minor axis direction of the plate portion and the second diaphragm portion, and one end
portion in the major diameter direction of the second diaphragm portion is formed thicker than
the free edge portion And a fixed edge portion to support. [Selected figure] Figure 1
Speaker diaphragm and electrodynamic speaker using the same
[0001]
The present invention is a slender (rectangular, oblong (including oval, track-shaped))
electrodynamic speaker having a shorter minor axis direction than the major axis direction,
which is excellent in sound reproduction capability and is a slender speaker. The present
invention relates to a speaker diaphragm and an electrodynamic speaker suitable for being
attached to a device such as a display with little influence even when the diaphragm is divided
and vibrated.
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1
[0002]
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, and it is difficult to increase the high
frequency reproduction limit frequency if resin material etc. are used to make the speaker
diaphragm rigid and lightweight compatible. There are disadvantages in sound reproduction
capability for reasons. Therefore, in order to solve these problems, various speaker diaphragms,
magnetic circuits for speakers, and electrodynamic speakers using the same have conventionally
been proposed.
[0003]
For example, a rectangular flat diaphragm has a voice coil bobbin which simultaneously contacts
two nodes in different vibration modes among free vibration modes of the rectangular flat plate,
and the rectangular plane is provided by the voice coil provided on this bobbin for piston
movement in the gap of the magnetic circuit. A diaphragm is attached and configured to be
driven, and the short side side far from the drive part of the voice coil is widely asymmetric as
compared with the outer side of the rectangular flat diaphragm on the short side close to the
drive part of the voice coil Patent Document 1 discloses an electrodynamic speaker configured to
be supported on a frame by an edge member.
[0004]
In addition, the speaker is provided with a rectangular flat diaphragm made of a foamable resin,
and the major diameter peripheral edge of the planar diaphragm is fixed to the frame, and the
minor diameter peripheral edge is free edge to stabilize the operation and stabilize the operation.
There is a target speaker (Patent Document 2).
In addition, an elastic resin layer of approximately arc shape is superimposed on the corner
formed by the frame of the edge, and heat molding is performed, and an elastic resin layer is
provided near the corner where deformation is likely to occur at the edge when driving the
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2
speaker. There are some which try to absorb and reduce distortion due to deformation or the like
and prevent deterioration of the sound quality due to these (Patent Document 3).
[0005]
In addition, conventionally, there is a speaker diaphragm in which a thermoplastic film foam and
a lightweight, highly rigid body are joined in a laminated manner, and a vibrating substrate is not
used at an edge portion (Patent Document 4). Moreover, while obtaining the laminated board
which laminated | stacked the thermoplastic resin film on the single side | surface or both
surfaces of the thermally foamable resin sheet of a non-foaming state, heat-processing in the
metal mold of diaphragm shape, plasticizing a thermoplastic resin film, There is a speaker
diaphragm in which a laminate is formed in a diaphragm shape by foaming a thermally foamable
resin sheet, and a thermoplastic resin film extended around the periphery is formed as an edge
(Patent Document 5).
[0006]
Furthermore, in the speaker diaphragm according to the applicant of the present invention, an
edge joint portion joined to the edge on the outer peripheral side of the diaphragm, and a
diaphragm portion provided on the inner peripheral side of the edge joint portion and joined to
the voice coil And the diaphragm portion has a virtual reference plane defined as a plane
including an edge junction, and a plurality of node lines defined as lines intersecting the virtual
reference plane and the distance from the virtual reference plane are maximal Provided with a
wave shape having a plurality of ridge lines defined as a line connecting the two points, and the
plurality of node lines do not intersect with the major axis of the diaphragm non-parallel and
intersect with the minor axis of the diaphragm (Patent Document 6). By making the speaker
diaphragm into such a waveform shape, the strength in the longitudinal direction of the
elongated diaphragm, ie, the major axis direction is improved, and the resonance frequency at
which split resonance occurs in the major axis direction can be shifted to a high frequency .
Furthermore, the resonance frequency of the split resonance that is likely to occur in the long
axis direction can be dispersed by gradually changing the interval of the wave-shaped
unevenness in the short axis direction toward the long axis direction. As a result, if the elongated
diaphragm having this waveform shape is used, a speaker with less peak-dip on the sound
pressure frequency characteristic and excellent reproduction sound quality can be realized.
[0007]
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JP-A-58-92198 JP-A-40-32164 JP-A-2001-285991 JP-A-50-61834 JP-A-57-132500 JP-A-2007180910
[0008]
In an audio device such as a display, for good sound reproduction, it is preferable that an
electrodynamic speaker having a good reproduction sound quality comparable to that of Patent
Document 6 be attached to the inside thereof.
However, in the case of employing a speaker diaphragm formed of resin foam to reduce the
weight of the speaker diaphragm with the aim of improving the reproduction sound pressure
level, the influence of the divisional vibration in the major axis direction is remarkable. As a
result, various problems such as difficulty in obtaining a flat reproduction sound pressure
frequency characteristic and high frequency reproduction limit frequency may not occur. In
addition, when the end of the speaker diaphragm is fixed and supported, there may be a problem
that the symmetry of the longitudinal amplitude is bad and the distortion characteristic is
deteriorated. In the front and rear amplitude, when the diaphragm of the speaker vibrates, the
side on which the voice coil, the damper, and the magnetic circuit are attached is the rear side,
and the side on which the diaphragm is exposed is the front side.
[0009]
The present invention has been made to solve the above-mentioned problems of the prior art,
and its object is to reduce the length of the elongated shape (rectangular, oblong (elliptical, trackshaped) in comparison with the major axis direction. And so on), which are high in efficiency and
excellent in voice reproduction ability, have little influence even if the long and thin speaker
diaphragms are divided and vibrate, and have good symmetry of longitudinal amplitude and little
distortion, etc. It is an object of the present invention to provide a speaker diaphragm and an
electrodynamic speaker that are suitable for being attached to the
[0010]
The speaker diaphragm according to the present invention is a speaker diaphragm including an
elongated diaphragm main body having a major axis direction and a minor axis direction, and an
edge for supporting the outer peripheral edge of the diaphragm main body, and the diaphragm
main body is A first diaphragm portion including a joint portion with a voice coil bobbin at a
central portion on the back side thereof, a second diaphragm portion extended respectively at
both ends in the major axis direction of the first diaphragm portion, and a first diaphragm
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4
Portion and a reinforcing rib continuously formed across the respective second diaphragm
portions, and the edge is an end portion of the first diaphragm portion and the second diaphragm
portion in the minor axis direction. It has a free edge portion to be freely supported, and a fixed
edge portion which is formed thicker than the free edge portion to fix and support one end in the
major axis direction of the second diaphragm portion.
[0011]
Preferably, in the speaker diaphragm of the present invention, the first diaphragm portion of the
diaphragm body has a surface area larger than the projected cross-sectional area of the voice coil
bobbin, and defines the average thickness of the first diaphragm portion. The first average
thickness value is smaller than the second average thickness value that defines the average
thickness of the second diaphragm portion.
[0012]
In addition, preferably, in the speaker diaphragm of the present invention, the reinforcing ribs
are formed at the long diameter both end ribs formed respectively at both ends in the minor
diameter direction of the diaphragm main body, and at the central portion in the minor diameter
direction of the diaphragm main body. Long-diameter central rib and a short-diameter both-end
rib formed at one end in the long-diameter direction of the second diaphragm portion, the shortdiameter both-end ribs connect the respective long-diameter both-end ribs, and a long-diameter
central rib Do not connect with
[0013]
Preferably, in the speaker diaphragm according to the present invention, the major diameter
central rib of the reinforcing rib comprises two separate major diameter central first ribs and
major diameter central second rib disposed across the junction with the voice coil bobbin. The
major-diameter central rib height defining the rib height of the major-diameter central first rib
and the major-diameter central second rib is respectively the highest at the first diaphragm
portion, and at one end in the major-diameter direction at the second diaphragm portion It gets
lower as you head.
[0014]
Further, the speaker diaphragm of the present invention includes a thermoplastic resin foam
sheet in which the diaphragm body is extruded and laminated on the surface with a
thermoplastic resin film, and the diaphragm body, the free edge portion and the fixed edge
portion The integrally molded edge is bonded by an adhesive.
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[0015]
In the speaker diaphragm of the present invention, the diaphragm main body includes a
thermoplastic resin foam sheet in which the front and rear are laminated by extruding the
thermoplastic resin film, and the edges are from the front and rear of the diaphragm main body
A diaphragm body and an edge, and a reinforcing body formed of a thermoplastic resin foam
sheet laminated on the front and back with a thermoplastic resin film, which includes a
thermoplastic resin film to be extended, and which supports the outer peripheral end of the edge
, Are integrated.
[0016]
Still preferably, in a loudspeaker diaphragm according to the present invention, the free edge
portion of the edge is a first free edge portion for freely supporting an end portion in the minor
axis direction of the first diaphragm portion, and a short side of the second diaphragm portion.
And a second free edge portion for freely supporting the radial end, wherein the stiffness k1 of
the first free edge portion is smaller than the stiffness k2 of the second free edge portion.
[0017]
The electrodynamic speaker of the present invention comprises the speaker diaphragm of the
present invention, a frame to which the outer peripheral end of the edge is fixed, a magnetic
circuit fixed to the frame and having a magnetic gap, and a voice coil bobbin. A voice coil and a
damper for disposing the voice coil in the magnetic gap.
[0018]
Hereinafter, the operation of the present invention will be described.
[0019]
The speaker diaphragm according to the present invention comprises an elongated (rectangular,
oval (elliptical, track-shaped)) diaphragm body having a major axis direction and a minor axis
direction, and an edge for supporting the outer peripheral edge of the diaphragm body. And a
speaker diaphragm.
A thermoplastic resin foam sheet (typically, the diaphragm body is formed so that the thickness
thereof is made uneven by using a vacuum forming method in which the foam of the contained
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6
thermoplastic resin is used in combination with plug assist molding A foamed polystyrene sheet
is laminated on the surface thereof with a thermoplastic resin film.
Further, the thermoplastic resin film (or sheet) for laminating the diaphragm main body is
typically a polystyrene resin film or a polyurethane elastomer resin film.
Therefore, in the speaker diaphragm of the present invention, the thermoplastic resin foam sheet
laminated on the surface is preheated, softened, die-pressed and cooled to form the diaphragm
main body into an elongated shape, and the diaphragm main body An arbitrary elongated shape
can be obtained by bonding an edge made of a foamable rubber or the like to the periphery of
the above, or integrally forming the edge with a thermoplastic resin film having a surface
laminated.
The speaker diaphragm of the present invention can also provide a slender electrodynamic
speaker by including a frame, a magnetic circuit, a voice coil wound around a voice coil bobbin,
and a damper.
The major axis direction is the direction in which the major axis defining the elongated shape
including the rectangular, oval, elliptical, or track shape extends, and the minor axis direction is
the direction in which the minor axis orthogonal to the major axis extends It is.
[0020]
The diaphragm main body of the speaker diaphragm according to the present invention is
extended to the first diaphragm including the joint with the voice coil bobbin at the center on the
back side and the both ends in the long diameter direction of the first diaphragm. It has a 2nd
diaphragm part, a 1st diaphragm part, and the reinforcing rib continuously formed over each
2nd diaphragm part.
The diaphragm main body is formed into an elongated shape including a rectangle, an oval, an
ellipse, and a track, while connecting the first diaphragm and the second diaphragm extended to
both ends thereof. Since the reinforcing rib is provided, it is possible to suppress the divided
vibration of the reinforcing rib in the major axis direction, and to realize a flat reproduction
sound pressure frequency characteristic with less peak and dip.
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[0021]
The first diaphragm portion is a portion to which a cylindrical voice coil bobbin is attached at the
central portion on the back side of the speaker diaphragm, includes the projected cross-sectional
area of the voice coil bobbin, and has two long sides of the elongated speaker diaphragm. And
two imaginary lines crossing in the minor axis direction between these long sides, and a
substantially rectangular area defined by the two.
In addition, the second diaphragm portion is a region extending from these imaginary lines of the
first diaphragm portion to both end sides (that is, the outward side in the major diameter
direction) opposite to the voice coil bobbin in the major diameter direction. is there.
In addition, the reinforcing rib is a projecting structure that forms a ridge line or a valley line
when viewed from the front side of the speaker diaphragm, and the major diameter both ribs
formed in the minor diameter direction and the major diameter central rib , And may further
have short-diameter end ribs formed at one end in the long diameter direction of the second
diaphragm portion.
[0022]
For example, the major diameter central rib of the reinforcing rib may be a rib continuously
formed so as to cross one second diaphragm part, the first diaphragm part, and the other second
diaphragm part. Also, the long central rib is formed of two separated major radial center first ribs
and major radial center second ribs disposed so as to sandwich the joint with the voice coil
bobbin, and the major radial rib heights defining these rib heights are respectively The height
may be highest in the one diaphragm portion and may be lower toward one end in the major
diameter direction in the second diaphragm portion.
The reinforcement rib including the long diameter center rib enables regeneration of the middle
and high tone range by the first diaphragm portion as described later, while enhancing the
rigidity in the long diameter direction of the elongated speaker diaphragm, while providing
longitudinal amplitude The symmetry of can be ensured.
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[0023]
On the other hand, the edge whose thickness is formed unevenly is formed thicker than the free
edge which freely supports the first diaphragm and the end in the minor axis direction of the
second diaphragm, and thicker than the free edge. And a fixed edge portion for fixedly
supporting one end portion in the major axis direction of the second diaphragm portion.
That is, in the diaphragm body of the present invention, the end in the minor axis direction (the
part corresponding to the long side of the diaphragm body) is freely supported by the free edge
portion of the edge, and the fixed edge portion of the edge is the end portion in the major
diameter direction (The part corresponding to the short side of the diaphragm main body) is
fixed and supported. Therefore, in the case of a long-speaker speaker diaphragm having a
significantly longer major axis compared to the minor axis, the end in the major axis direction is
large when the voice coil is largely displaced at a frequency near or below the lowest resonance
frequency f0. Because it is fixed and supported and becomes a node, it vibrates in the lowest
bending vibration mode in which the central part in the major axis direction is driven and
becomes an antinode, so it suppresses dips that are likely to appear first in the low frequency
range, and reproduces a flat sound. Pressure frequency characteristics can be realized.
Furthermore, the symmetry of the front-rear amplitude of the speaker diaphragm can be
improved by the rigidity of the reinforcing rib, so that an electrodynamic speaker excellent in
reproduction sound quality with less distortion can be realized.
[0024]
Further, the first diaphragm portion of the diaphragm main body has a surface area larger than
the projected cross-sectional area of the voice coil bobbin, and a first average thickness value
defining the average thickness of the first diaphragm portion is the first The value is smaller than
the second average thickness value that defines the average thickness of the two diaphragms.
Therefore, since the average thickness of the first diaphragm portion attached to the back
surface of the voice coil bobbin is configured to be thin, the equivalent mass around the voice
coil bobbin contributing to the emission of the sound wave in the middle to high range is
lightened, and the voice coil As a result of efficiently transmitting the driving force generated in
the above, it is possible to raise the reproduction sound pressure level in the middle to high
range. The free edge portion of the edge freely supports the first free edge portion that freely
supports the short diameter direction end portion of the first diaphragm portion and the second
free edge portion that freely supports the short diameter direction end portion of the second
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diaphragm portion A free edge portion, and by designing the material or the shape, the stiffness
k1 of the first free edge portion is smaller than the stiffness k2 of the second free edge portion ,
The possible amplitude range of the first diaphragm portion is expanded, and the reproduction
sound pressure level can be further raised, and the efficiency is improved.
[0025]
The diaphragm main body is not limited to the extruded polystyrene foam sheet as long as it is a
thermoplastic resin containing polystyrene foam, and is selected from polystyrene, acrylic,
polyethylene, polypropylene, polycarbonate, ABS resin, etc. It may be a foam of one or more
blended resins. Further, the edge to be bonded to the diaphragm main body is an elastomer
material, and it is sufficient if the thickness is not uniform and the free edge portion and the fixed
edge portion can be configured. In addition to the above-described foamable rubber or
thermoplastic resin film, a sheet of urethane foam may be formed by heating, or it may be a
rubber edge whose thickness is changed by injection molding or the like. When the edge of the
speaker diaphragm is a laminate of the front and back of the diaphragm body and includes a
thermoplastic resin film extended around the diaphragm body, the diaphragm body and the edge,
and further the edge Since the reinforcing body that reinforces the outer peripheral end is
integrally formed, it is possible to reduce the number of processes and man-hours for producing
a diaphragm complete product including the diaphragm body, the edge, and the reinforcing body,
and the cost reduction of the electrodynamic speaker Can be
[0026]
Even if it is a slender speaker diaphragm whose minor axis direction is shorter than the major
axis direction, it has high efficiency and excellent voice reproduction ability, little influence of
divided vibration, good symmetry of longitudinal amplitude, little distortion, etc. Can provide an
electrodynamic speaker suitable for attachment to
[0027]
The speaker diaphragm according to the present invention is highly efficient and excellent in
voice reproduction capability even with a slender speaker diaphragm having a short diameter
direction shorter than the major axis direction, and is less affected by divided vibration, and is
symmetrical in longitudinal amplitude Have a low distortion and an object of providing an
electrodynamic speaker suitable for mounting on a device such as a display by forming a
diaphragm body having a non-uniform thickness and made of foamed thermoplastic resin, with
the center on the back side A first diaphragm portion including a joint portion with the voice coil
bobbin in the second portion, a second diaphragm portion extended respectively at both ends in
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10
the major axis direction of the first diaphragm portion, a first diaphragm portion, and The
reinforcing rib formed continuously across the second diaphragm portion, and the edge having
an uneven thickness is an end portion in the minor axis direction of the first diaphragm portion
and the second diaphragm portion. Freely supported free edge and free edge A second
diaphragm portion fixing edge portion of one end of the major axis to the fixed support of
Rimoatsumi is the thick, by to have, was realized.
[0028]
Hereinafter, a speaker diaphragm and an electrodynamic speaker according to preferred
embodiments of the present invention will be described, but the present invention is not limited
to these embodiments.
[0029]
1 and 2 illustrate 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 obliquely from above, and FIG. 1B is a perspective view of the electrodynamic speaker 1 as
viewed from the lower rear side.
FIG. 2A is a cross-sectional view of the electrodynamic speaker 1 taken along the line O-A, and
FIG. 2B is a cross-sectional view of the electrodynamic speaker 1 taken along the line B-B '.
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.
[0030]
The electrodynamic speaker 1 of this embodiment is a slender electrodynamic speaker having a
track-type speaker diaphragm 2 having a major axis length L1 of about 210 mm and a minor axis
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length L2 of about 35 mm. It is a speaker having a diaphragm area equal to that of a circular
diaphragm having a diameter of about 90 mm even if there is any. The speaker diaphragm 2 is
supported at its outer peripheral end by the edge 3, and the outer peripheral end of the edge 3 is
fixed to the frame 6. Further, the voice coil 4 is connected to the back side of the speaker
diaphragm 2 and is supported so as to be vibrated by the damper 5 (the front damper 5a and the
rear damper 5b). The frame 6 has an elongated shape corresponding to the track-shaped speaker
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 minor axis length L2. Therefore, the
electrodynamic speaker 1 is a speaker suitable for a device having a small width for attaching the
speaker, such as a side surface of a display unit of a device such as a display.
[0031]
The inner peripheral side of the edge 3 is bonded to the outer peripheral end of the speaker
diaphragm 2 of the electrodynamic speaker 1, and the bobbin 4a constituting the voice coil 4 is
bonded to the central back surface. The speaker diaphragm 2 is formed by forming a foamed
thermoplastic resin in order to reduce the weight of the speaker diaphragm. In the case of the
present embodiment, the extruded thermoplastic resin foam sheet (specifically, polystyrene
paper) is formed into a non-uniform thickness and has ribs by using a vacuum forming method
using plug assist forming in combination. The speaker diaphragm 2 is obtained. That is, since the
speaker diaphragm 2 of the elongated shape in which the major axis length L1 and the minor
axis length L2 are significantly different is likely to be significantly affected by the divisional
vibration in the major axis direction, it has a rib extending in the major axis direction The radial
cross-sectional shape is substantially W-shaped, and the shape has rigidity in the major axis
direction. In addition, a thermoplastic resin film (specifically, a polystyrene film) is heat-sealed on
the front and back surfaces of the speaker diaphragm 2 to increase the rigidity of the speaker
diaphragm 2.
[0032]
In the present embodiment, the edge 3 is formed by injecting a flexible foam rubber into a mold
and performing heat foaming. A free edge is formed by a thin corrugation (or a roll) so as to
support the speaker diaphragm 2 freely on the long side of the track shape extending linearly in
the major axis direction of the speaker diaphragm 2, and is arced in the minor axis direction. In
the short side of the track shape, there is formed a thick, non-oscillating fixed edge so as to fix
and support the speaker diaphragm 2. As a result, the elongated speaker diaphragm 2 is flexibly
supported by the compliance of the free edge portion of the edge 3 in the minor axis direction,
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while the flexibility of the polystyrene paper forming the loudspeaker diaphragm 2 in the major
axis direction The bending vibration is made possible.
[0033]
The voice coil 4 is formed of a bobbin 4a formed in a cylindrical shape and a coil 4b wound on
one end side thereof and supplied with an audio current. The other end of the bobbin 4 a on
which the coil 4 b is not wound is connected to the center of the back surface of the speaker
diaphragm 2 by an adhesive. The coil 4 b is disposed in a circular magnetic air gap 12 of the
magnetic circuit 10 described later. The tinsel wire 8 solders the terminal 7 fixed to the frame 6
and the lead wire from the terminal 7 to the coil 4b to conduct electricity, and supplies an audio
current to the coil 4b. However, the tinsel wire 8 may be connected to the terminal 7 by
providing a metal eyelet on the speaker diaphragm 2.
[0034]
The damper 5 is a two-stage damper including a front damper 5a and a rear damper 5b, and is a
long and thin shape by cutting a circular corrugation damper formed by impregnating a phenolic
resin with a flexible fiber woven fabric as a base material. (Track type). The inner peripheral ends
of the front damper 5a and the rear damper 5b are connected to the cylindrical outer surface
side of the bobbin 4a to support the rear central side of the speaker diaphragm 2. The outer
peripheral end sides of the front damper 5 a and the rear damper 5 b are fixed to a fixing portion
of the frame 6. In addition, the damper 5 is a corrugation damper of another shape, and may not
be formed in two stages, and may be formed of another material, and connects the inner
peripheral side ring and the outer peripheral side ring It may be a butterfly damper having an
arm and formed of metal or resin.
[0035]
The frame 6 is an iron plate frame press-formed into a slender basket shape corresponding to the
shape of the speaker diaphragm 2, and a substantially rectangular fixing portion for fixing the
edge 3, dampers 5a and 5b, and a magnetic circuit A fixing portion for fixing 10, a connecting
portion for connecting the fixing portions, a window defined between the plurality of connecting
portions, and a mounting hole for mounting the terminal 7 are provided. Therefore, the speaker
vibration system including the speaker diaphragm 2, the edge 3, the voice coil 4 and the damper
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5 is vibratably supported on the frame 6.
[0036]
The magnetic circuit 10 comprises an elongated top plate 11 fixed to the frame 6, a center pole
12 which is cylindrical and inserted in a circular hole formed at the center of the top plate 11,
and an elongated under plate 14. And two main magnets 15a and 15b magnetized in the same
direction. The top plate 11 and the center pole 12 form a circular magnetic air gap 13 having a
uniform width in the radial direction. The main magnets 15 a and 15 b are sandwiched between
the top plate 11 and the under plate 14, and are arranged symmetrically with the center pole 12
in between in the major axis direction.
[0037]
The two main magnets 15a and 15b are Nd-Fe-B-based rare earth magnets having a high
coercive force even with a small volume, and each has a substantially cylindrical shape. The rare
earth magnet is a Nd-Fe-B neodymium magnet or a Sm-Co samarium cobalt magnet, and the
maximum energy product (BH) max of the magnet takes a large value, and residual
magnetization and retention are maintained. It is a magnet with a large magnetic force. Since the
rare earth magnet has a large coercive force, it can generate a high magnetic flux density, but has
a large permeance coefficient and is hard to demagnetize.
[0038]
The two main magnets 15a and 15b are disposed in the major axis direction of the magnetic
circuit 10 of the present embodiment, while the magnet (magnet) for generating the magnetic
force is not disposed in the minor axis direction. When the magnetic circuit 10 is viewed from
the side of the magnetic circuit 10 from the short diameter direction, the angle of the opening is
wide enough to directly view the cylindrical side surface of the center pole 12 from the open
space where the magnet is not disposed. It has become.
[0039]
The magnetic circuit 10 is an external magnet type magnetic circuit in which a magnet is
disposed outside the area to be projected when the coil 4b of the voice coil 4 is viewed in a plan
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view, and the main magnets 15a and 15b having a strong magnetomotive force are in the major
axis direction. Because it is disposed in the above, it is suitable for an elongated speaker such as
the electrodynamic speaker 1 of the present invention.
This is because if the maximum width of the magnetic circuit 10 can be reduced, the magnetic
circuit 10 fits within the area formed when the elongated speaker diaphragm 2 is viewed from
the front. Therefore, an efficient dynamic speaker 1 is realized including the adoption of a
lightweight speaker diaphragm 2.
[0040]
When a voice current is supplied to the coil 4b 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 vertical
direction in FIG. The diaphragm 2 also vibrates in the vertical direction. The speaker diaphragm 2
flexibly supports the free edge portion of the edge 3 supporting the outer peripheral end in the
minor axis direction. On the other hand, in the major axis direction, bending and vibration
becomes possible due to the flexibility of the polystyrene paper forming the speaker diaphragm
2, and when the voice coil 4 is largely displaced at a frequency near or lower than the lowest
resonance frequency f0, the major axis direction The speaker diaphragm 2 fixed at its both ends
is bent and deformed in an arc shape in the major axis direction.
[0041]
In the magnetic circuit 10, even if the circular magnetic gap 13 has an equal width in the radial
direction, the magnetic flux density distribution differs in the major axis direction and the minor
axis direction, and the substantially cylindrical main magnets 15a and 15b are circular An
extremely strong magnetic flux density is generated in the major axis direction in which the
magnetic gap 13 of FIG. 6 most approaches, and the magnetic flux density in the major axis
direction becomes higher than the magnetic flux density in the minor axis direction. Since the
magnetic flux density distribution in the circumferential direction in the circular magnetic gap 13
is different in the major axis direction and the minor axis direction, the driving force for driving
the speaker diaphragm 2 can also be different in the major axis direction and the minor axis
direction. The peak dip of the characteristic can be reduced.
[0042]
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3 and 4 illustrate the speaker diaphragm 2 and the edge 3. FIG. 3A is a perspective view of the
speaker diaphragm 2 and the edge 3 as viewed from the front upper side, and FIG. 3B is a
perspective view of the speaker diaphragm 2 and the edge 3 as viewed from the rear lower side
FIG. 4A is a cross-sectional view of the speaker diaphragm 2 and the edge 3 taken along the line
O-A ', and FIG. 4B is a cross-sectional view of the speaker diaphragm 2 and the edge 3 taken
along the line B-B'; (C) is CC 'sectional drawing of the speaker diaphragm 2 and the edge 3. FIG.
In addition, as will be described later, the structure of the speaker diaphragm 2 and a part of the
edge 3, the cross-sectional 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.
[0043]
The speaker diaphragm 2 of this embodiment is formed by extrusion-forming polystyrene paper
(PSP) to have ribs with uneven thickness by using a vacuum forming method in combination with
plug assist forming, and the surface thereof And on the back side, a film of polyurethane
elastomer is heat-sealed to increase its rigidity. Specifically, the speaker diaphragm 2 uses a 10fold expanded extruded polystyrene sheet (about 2.0 mm in thickness) blended with 10% of
acrylic as a raw material, and a polystyrene film (about 50 μm in thickness) on both sides
thereof It is heat-sealed and laminated, and a diaphragm is formed by the vacuum forming
method in combination with plug-assisted forming. The rigidity and the loss can be improved by
laminating a polystyrene film on one side or both sides as compared with the case where the
speaker diaphragm is formed only by the extruded foam polystyrene sheet. For example, the
physical properties of the speaker diaphragm are Young's modulus: 4.6E + 8 (dyne / Cm2),
density: 0.043 (g / Cm3), tan δ: 0.043 in the case of PSP alone, as in this example. By laminating
a polystyrene film on both sides of PSP, the Young's modulus: 9.7E + 8 (dyne / Cm2), density:
0.055 (g / Cm3), tan δ: 0.074, can be improved to excellent values.
[0044]
The outer dimensions of the track-shaped speaker diaphragm 2 are about 198 mm in the major
axis direction length L1 and about 23.4 mm in the minor axis direction length L2. The thickness
of the speaker diaphragm 2 changes in the range of about 1 mm to about 3 mm by vacuum
forming, and the thickness can be made uneven according to the rigidity required for the speaker
diaphragm. The speaker diaphragm 2 has a rib extending in the major axis direction, and the
10-05-2019
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cross-sectional shape in the minor axis direction is substantially W-shaped. For example, the
long-diameter both-end ribs forming the outermost periphery of the speaker diaphragm 2 have a
thickness of about 1 mm.
[0045]
In addition, the vacuum forming which used the plug assist molding together is a forming
method which preheats and softens the laminated material, and then, while suctioning with a
desired concave shape, pressing with a convex shape. The polystyrene paper of this embodiment
may be a foam sheet of another thermoplastic resin, and the thermoplastic foam sheet is
obtained by an extrusion foaming method, a bead foaming method, or the like. The thermoplastic
resin constituting the foam sheet is one kind of resin selected from polystyrene, acrylic,
polyethylene, polypropylene, polycarbonate, ABS resin, vinyl chloride resin, vinyl acetate, vinyl
acetate-ethylene resin etc., or a plurality of selected resins Any resin obtained by blending may
be used.
[0046]
The resin constituting the thermoplastic resin film to be laminated is one selected from
polystyrene, acrylic, polyethylene, polypropylene, polyurethane, polyethylene terephthalate,
polyethylene naphthalate, nylon, or polyurethane elastomer, polyolefin elastomer, polyamide
elastomer, etc. Or a resin obtained by blending a plurality of selected resins. In this embodiment,
in the double-sided lamination of the front and back, the thermoplastic resin film is the same on
both sides, but the front and back may be different thermoplastic resin films. The laminate may
be heat-sealed by the thermoplasticity of the thermoplastic foam sheet and the thermoplastic
resin film, or by a thermoplastic adhesive printed or applied to the thermoplastic resin film. And
may be heat-sealed.
[0047]
The first diaphragm portion 21 of the speaker diaphragm 2 crosses the two long sides of the
elongated speaker diaphragm 2 and the long sides in the short diameter direction at the central
portion on the back side of the speaker diaphragm 2 It is a substantially rectangular area defined
by two virtual lines X and X '. In the case of the present embodiment, the distance between the
virtual lines X and X 'is about 40 mm, which is larger than the diameter of the voice coil bobbin 4
10-05-2019
17
and can be set within about 1/2 of the longitudinal diameter L1 of the speaker diaphragm. It is.
As shown in FIG. 4B, the first diaphragm portion 21 includes a circular flat portion 23 to which
one end of the substantially cylindrical voice coil bobbin 4 is attached at the central portion on
the back side. Is dome-shaped. Further, the outside of the circular flat portion 23 has a
substantially cone shape having a rising, and has a shape connected to a second diaphragm
portion 22 described later. The first diaphragm portion 21 contributing to the reproduction of
the mid and high tone ranges is formed to be thinner than the second diaphragm portion 22, and
the first average defining the average thickness of the first diaphragm portion 21. The thickness
value t1 is about 2 mm.
[0048]
The second diaphragm portion 22 has two long sides of the elongated speaker diaphragm 2 at
both ends of the elongated speaker diaphragm 2, short sides of the elongated speaker diaphragm
2, and the above-described virtual It is an area defined by the line X (or X '). The short-side
portion of the track-shaped speaker diaphragm 2 of the present embodiment includes a
semicircular portion that defines the track shape, and the cross-sectional shape of the second
diaphragm portion 22 in the short diameter direction is as shown in FIG. As shown, it is
substantially W-shaped, and has a substantially constant cross-sectional shape except for the
semicircular portion corresponding to the short side. In the case of the present embodiment, the
second average thickness value t2 defining the average thickness of the second diaphragm
portion is about 3 mm, and the diaphragm is formed to be thicker than the first diaphragm
portion 21.
[0049]
The reinforcing rib of the speaker diaphragm 2 has a protruding structure that forms a ridge or a
valley when viewed from the front side of the speaker diaphragm 2. Specifically, in the case of
the present embodiment, the first diaphragm portion 21 includes the major diameter central rib
24 and the two major diameter end ribs 25 formed on both ends of the speaker diaphragm 2 in
the minor diameter direction. And, it is formed continuously across the respective second
diaphragm portions 22. That is, in the cross sectional shape of the speaker diaphragm 2, the
major diameter central rib 24 and the major diameter both ends rib 25 penetrate the portion
corresponding to three upper end points of the substantially W shape in the major diameter
direction, and the major diameter direction of the loudspeaker diaphragm 2 Improve the rigidity
of the Further, the short diameter end ribs 26 formed in an arc shape corresponding to the
semicircular shape of the second diaphragm portion 22 connect the respective long diameter end
10-05-2019
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ribs 25 to form the track-shaped speaker diaphragm 2. Reinforce the outer rim to increase
rigidity. The ridges of the ridges of the long center rib 24 do not reach both ends of the trackshaped speaker diaphragm 2 in the long axis direction, so the long center rib 24 and the short
end ribs 26 are not connected. Since the first diaphragm portion 21 and the second diaphragm
portion 22 are reinforced so as to be connected to each other, the track-type speaker diaphragm
2 is reinforced to enhance the rigidity.
[0050]
On the other hand, the edge 3 is in the form of a track having a cutting inner diameter of about
195 mm × about 21 mm and a semicircular arc-shaped radius of about 10.5 mm. In this
embodiment, flexible foam rubber is injected into the mold. Then, the reinforcing body 34 of the
outer peripheral end fixed to the fixed portion of the frame 6 as well as the movable portion of
the edge by heating and foaming is integrally formed. In the present embodiment, after a heat
fusible adhesive is applied to the outer peripheral portion of the speaker diaphragm 2 and dried,
the speaker diaphragm 2 and the edge 3 are bonded by heat pressing with a bonding die. In
addition, it is possible to obtain a diaphragm finished product in which the reinforcing body 34 is
also integrally formed.
[0051]
Specifically, the edge 3 is a free edge portion (first diaphragm portion 21 that freely supports
both ends in the minor axis direction of the speaker diaphragm 2 at the long side of the track
shape extending linearly in the major axis direction of the speaker diaphragm 2 And a second
free edge portion 32 corresponding to the second diaphragm portion 22. And a fixed edge
portion 33 for fixedly supporting the speaker diaphragm 2 on the short side of the track shape in
an arc shape. As shown in FIGS. 4 (b) and 4 (C), the first free edge portion 31 and the second free
edge portion 32 are free edges having a roll of inverted V-shape having mobility. The thickness
of the foamed rubber is about 0.2 mm.
[0052]
Further, as shown in FIG. 4A, the fixed edge portion 33 is a fixed edge which is formed thick from
the gasket-like reinforcing body 34 without having a roll-like movable portion. The connected
outer peripheral side is fixed to the fixing portion of the frame 6, and the inner peripheral side is
10-05-2019
19
fixed to the second diaphragm portion 22, and supports both short sides of the track shape of the
speaker diaphragm 2 so as not to vibrate freely. That is, the fixed edge portion 33 has a shape in
which the portion corresponding to the movable portion including the inverted V-shaped portion
of the first free edge portion 31 and the second free edge portion 32 is filled with foam rubber to
prevent free vibration. The thickness of the foamed rubber is about 2 mm to about 3.5 mm. As a
result, the fixed edge portion 33 restrains both ends in the major axis direction of the speaker
diaphragm 2. The fixed edge portion 33 does not have to be thickened in all the arcs of the short
side of the track shape, and a part of the arcs of the short side of the track shape is a fixed edge,
and the other portions of the arcs are fixed. Is a free edge, and may be intermittently connected
to the free edge portion.
[0053]
Therefore, while the electrodynamic speaker 1 including the elongated speaker diaphragm 2 and
the edge 3 of the present embodiment is flexibly supported by the compliance of the free edge
portion of the edge 3 in the minor axis direction, the loudspeaker in the major axis direction
Flexural vibration occurs due to the flexibility of the thermoplastic resin foam sheet forming the
diaphragm 2. As a result, as described later, it is possible to suppress the dip that tends to appear
first in the low tone range, and it is possible to realize a flat reproduction sound pressure
frequency characteristic. Furthermore, as will be described later, the symmetry of the front-rear
amplitude of the speaker diaphragm can be improved by the rigidity of the reinforcing rib, so
that an electrodynamic speaker excellent in reproduction sound quality with less distortion can
be realized. Further, since the average thickness t1 of the first diaphragm portion 21 is formed
thinner than the thickness t2 of the diaphragm of the second diaphragm portion 22, the
reproduction efficiency in the middle range and the high range is improved, and the reproduction
range is wide. An electrodynamic speaker is realized.
[0054]
FIG. 5 is a graph for explaining the operation of the electrodynamic speaker 1 provided with the
elongated speaker diaphragm 2 and the edge 3 of the present embodiment, and FIG. 5 (a)
describes the reproduced sound pressure frequency characteristics of the embodiment. FIG. 5B is
a graph for explaining the reproduced sound pressure frequency characteristics of the
conventional electrodynamic speaker of the comparative example. Further, FIG. 6 is a graph
showing a displacement amount of longitudinal amplitude when a driving force is applied to the
voice coil 4 having the speaker diaphragm 2 in the electrodynamic speaker 1, and the absolute
value of the value in the longitudinal direction is shown. By taking it, the characteristic curve of
10-05-2019
20
the graph is turned back, and when the front-back symmetry is good, the forward displacement
curve and the backward displacement curve are displayed so as to overlap. The electrodynamic
speaker of the comparative example is an elongated speaker diaphragm (not shown) formed of
the same materials and parts as those of the embodiment, and the difference from the
embodiment is that the speaker diaphragm has a central long diameter It is a wedge shape which
does not have a rib 24, and is a point which has a free edge part which supports a speaker
diaphragm freely in the track-shaped short side which becomes circular arc shape.
[0055]
The electrodynamic speaker 1 provided with the elongated speaker diaphragm 2 and the edge 3
of the present embodiment, as shown in FIGS. 5 (a) and 5 (b), has a frequency of about 120 Hz
observed in the comparative example. A wide range of dips around 240 Hz and a dip of about 1.5
kHz disappear to realize relatively flat frequency characteristics. Further, as shown in FIGS. 6 (a)
and 6 (b), the electrodynamic speaker 1 of the present embodiment is improved in the
asymmetry of the longitudinal amplitude seen in the case of the comparative example, and it is
possible to It is possible to reduce the occurrence of even-order distortion caused as well as
malfunction such as the generation of rattling noise. In the case of the comparative example
which is a wedge-shaped diaphragm which does not have the long diameter central rib 24, it
shows remarkable anteroposterior asymmetry due to lack of rigidity in the long diameter
direction, but in the case of this embodiment Symmetry is improved to allow good audio
reproduction.
[0056]
In the case of the present embodiment, the weight of the vibration system of the finished
diaphragm including the elongated speaker diaphragm 2 and the edge 3 (including the
reinforcing body 34) is about 1.56 g (diaphragm main body 1. 18 g, diaphragm part adhesive 0.2
g, edge movable part 0.55 g. However, 1/3 of the edge movable part is considered as the
vibration system mass. )である。 On the other hand, the number of steps required to make this
diaphragm finished product is 10 seconds for forming the speaker diaphragm 2, 5 seconds for
cutting, 30 seconds for forming the edge 3, 15 seconds for cutting, 10 seconds for applying the
adhesive, and 15 A total of 85 seconds of seconds.
[0057]
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21
Next, a speaker diaphragm 2A (not shown) of the present embodiment will be described. The
speaker diaphragm 2A uses a thermoplastic foam sheet as a core material and a thermoplastic
resin film laminated on the front and back surfaces, and simultaneously the main body portion of
the speaker diaphragm 2A, the edge 3A, and the reinforcing body 34A. Integrally form. In the
speaker diaphragm 2A, a film of polyurethane elastomer is heat-sealed on the front and back of
an extruded polystyrene paper, and this is molded by a vacuum molding method using the above
plug assist molding, and the above-mentioned implementation The diaphragm main body having
the same shape as the speaker diaphragm 2 of Example 1 is obtained. However, the edge 3A is
integrally formed of a film of polyurethane elastomer extending from the front and back of the
speaker diaphragm 2A to form a free edge at the end in the minor axis direction, and the end in
the major axis direction Are different in that they form a fixed edge. Further, like the main body
portion of the speaker diaphragm 2A, the reinforcing body 34A supporting the outer peripheral
end of the edge 3A is integrally formed of polystyrene paper in which a film of polyurethane
elastomer is laminated on both sides.
[0058]
Specifically, the diaphragm body portion of the speaker diaphragm 2A is the same as the speaker
diaphragm 2 of the previous embodiment in that the laminated thermoplastic resin film is a
polyurethane elastomer film (about 50 μm in thickness). It is different. However, the outer
dimensions of the track-shaped speaker diaphragm 2 are about 198 mm in the major axis
direction length L1 and about 23.4 mm in the minor axis direction length L2. Since the speaker
diaphragm 2A changes in thickness in the range of about 0.3 mm to about 3 mm and has the
cross-sectional shape and the reinforcing rib described in the speaker diaphragm 2, the
electrodynamic speaker 1 described in the first embodiment is provided. The same parts as those
in FIG.
[0059]
The edge 3A has a track shape having a cutting inner diameter of about 195 mm × about 21
mm and a semicircular arc-shaped radius of about 10.5 mm, and in this embodiment, the free
edge portion of the edge 3A (corresponding to the first diaphragm portion 21) A first free edge
portion 31A and a second free edge portion 32A corresponding to the second diaphragm portion
22 are included. ) Is formed integrally with a film of polyurethane elastomer which is formed
extremely thinly in a film of polyurethane elastomer extended from the front and back of the
speaker diaphragm 2A, so that its thickness is about 0.3 mm . Further, the fixed edge portion
10-05-2019
22
33A of the edge 3A is gradually thickened from about 0.3 mm to 2.5 mm as in the speaker
diaphragm 2, and is continuously formed on the reinforcing body 34A as it is. The reinforcing
body 34 </ b> A is formed into a thick shape, and forms a rigid arrow paper and gasket utilizing
the thickness of the foamed polystyrene sheet to be foamed.
[0060]
In the case of the present embodiment, the weight of the completed diaphragm including the
elongated speaker diaphragm 2A and the edge 3A (including the reinforcing body 34) is about
1.51 g, and 1/1 of the edge movable portion. Assuming that 3 is a vibration system mass, the
weight of the vibration system is about 1.29 g. Compared to the case of the edge 3 of the
previous embodiment, the weight of the vibration system can reduce the weight by about 17%,
and when it is used for an electrodynamic speaker, the level of reproduced sound pressure can
be improved.
[0061]
Therefore, even if the edge 3A in the present embodiment is integrally formed with the speaker
diaphragm 2A, the cross-sectional shape can be made substantially the same as that of the foam
rubber edge of the previous embodiment. In the minor axis direction, flexible vibration is
supported by the compliance of the free edge portion of the edge 3A, while in the major axis
direction, bending vibration is caused by the flexibility of the polystyrene paper forming the
speaker diaphragm 2A. As a result, the electrodynamic speaker adopting the speaker diaphragm
of the present embodiment can suppress a dip that is likely to appear first in the low frequency
range, and can realize flat reproduction sound pressure frequency characteristics. No variation
occurs in the amount of adhesive applied for bonding the speaker diaphragm 2A to the edge 3A,
and the edge 3A to the reinforcing member 34A, and no variation such as a bonding deviation
occurs in the bonding process. Also, since variations in the amount of adhesive agent applied to
the bonded portions occur, as a result, stable quality free of variations in the characteristics of
the electrodynamic speaker can be obtained.
[0062]
Further, in the case of the present embodiment, it is possible to obtain a diaphragm finished
product in which the speaker diaphragm, the edge, and the reinforcing body are integrally
10-05-2019
23
formed in one step, and the material cost and the molding relating to the edge and the
reinforcing body No need for construction costs. In addition, the material cost and application of
the adhesive for bonding the speaker diaphragm and the edge and the edge and reinforcing
paper, and the cost for the bonding, and the cost and material for the adhesive for the surface of
the bonding portion. There is no need for expenses. The man-hours required to produce this
diaphragm finished product is 10 seconds of forming, while the total of 85 seconds including
bonding when the speaker diaphragm 2 and the edge 3 are separate bodies, and cutting Since it
takes only 15 seconds in total of 5 seconds, it is possible to obtain a completed diaphragm in
about 1/6 of the number of steps. As compared with the electrodynamic speaker of the previous
embodiment, the number of components can be reduced, and the overall weight reduction and
cost reduction can be achieved.
[0063]
Next, an electrodynamic speaker 1B provided with a speaker diaphragm 2B (not shown) and an
edge 3B (not shown) of this embodiment will be described. The speaker diaphragm 2B is
common to the speaker diaphragm 2A of the second embodiment in that the polyurethane
elastomer film is heat-sealed to the front and back surfaces of the extruded polystyrene paper, so
the description will be omitted. . Also, the size and shape of the edge 3B are the same as in the
previous embodiment. However, the material of the edge 3B and the arrangement thereof are
different from those of the previous embodiment.
[0064]
In the edge 3B of this embodiment, the material constituting the free edge portion for freely
supporting the both ends in the minor axis direction of the speaker diaphragm 2B is a trackshaped long side linearly extending in the major axis direction of the speaker diaphragm 2B. The
first diaphragm portion 21B and the second diaphragm portion 22B are selected to be different.
That is, the first free edge portion 31B corresponding to the first diaphragm portion 21B to
which the voice coil 4 is attached has a stiffness k1 higher than the stiffness k2 of the second
free edge portion 32B corresponding to the second diaphragm portion 22B. Is a free edge
formed of a small soft material.
[0065]
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24
Specifically, the first free edge portion 31B for freely supporting the short diameter direction end
of the first diaphragm portion 21B is a lightweight and soft edge obtained by bonding two
polyurethane elastomer films with an adhesive, The second free edge portion 32B for freely
supporting the short diameter direction end of the second diaphragm portion 22B is an edge
formed by sandwiching an edge of urethane foam having a thickness of about 0.3 mm with the
above-described two films of polyurethane elastomer And is heavier and harder than the first
free edge portion 31B. For example, in the present embodiment, the stiffness k1 of the first free
edge portion 31B is about 250 N / m, whereas the stiffness k2 of the second free edge portion
32B is a large value of about 400 N / m.
[0066]
FIG. 7 is a graph for explaining the reproduction sound pressure frequency characteristics of the
electrodynamic speaker 1B provided with the elongated speaker diaphragm 2B and the edge 3B
of the present embodiment. As in the previous embodiment, the average thickness t1 of the first
diaphragm portion 21B of the speaker diaphragm 2B is thinner than the thickness t2 of the
diaphragm of the second diaphragm portion 22B. The efficiency of playback is improved, and an
electrodynamic speaker with a wide playback bandwidth is realized. In the electrodynamic
speaker 1B of this embodiment, since the first free edge portions 31B for freely supporting both
end portions of the first diaphragm portion 21B in the minor axis direction are soft and light
edges, the mid and high tone ranges are realized. It is possible to further improve the
regeneration efficiency of
[0067]
In addition, the thickness of the edge roll is made to be different not only when the material of
the first free edge portion 31B is different from the material of the second free edge portion 32B,
but also when the material is the same. , It may adjust the correlation of stiffness. When the edge
3B of this embodiment is an edge formed by two-color molding using two different rubber
materials or resin materials, the material arrangement is set by the elastic modulus of the
material to optimize the shape of the edge. By doing this, the stiffness of the first free edge
portion 31B and the second free edge portion 32B can be adjusted.
[0068]
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25
FIG. 8 is a view for explaining a speaker diaphragm 2C and an edge 3C of another embodiment.
FIG. 8 (a) is a perspective view of the speaker diaphragm 2C and the edge 3C viewed obliquely
from the front upper side, and FIG. 8 (b) is a cross-sectional view of the speaker diaphragm 2C
and the AA 'cross section of the edge 3. It is the figure which expanded a part. In addition, as will
be described later, the structure of the speaker diaphragm 2C and a part of the edge 3C, the
cross-sectional 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.
[0069]
The speaker diaphragm 2C of this embodiment is formed by extrusion forming a sheet of
polypropylene (PP) having a substantially uniform thickness so as to have a reinforcing rib by
using a vacuum forming method in combination with plug assist forming. There is. Specifically,
the speaker diaphragm 2C uses a 10-fold extruded extruded polypropylene sheet (about 1.1 mm
in thickness) in which 10% of acrylic is blended, as a raw material, and the diaphragm is formed
by the above-described vacuum forming method using plug assist molding. Is formed. The outer
dimensions of the track-shaped speaker diaphragm 2C are approximately 262.0 mm in the major
axis direction length L1 and approximately 25.5 mm in the minor axis direction length L2. The
first diaphragm portion 21C and the second diaphragm portion 22C of the speaker diaphragm
2C are defined in the same manner as the previous embodiment.
[0070]
That is, in the central portion of the speaker diaphragm 2C, the first diaphragm portion 21C
includes two long sides of the elongated speaker diaphragm 2 and two imaginary lines X
crossing the long sides in the short diameter direction. And X ′, and is a substantially
rectangular area defined by In the case of the present embodiment, the distance between the
virtual lines X and X 'is about 34.0 mm, which is larger than the diameter of the voice coil bobbin
4 and within about 1⁄2 of the longitudinal diameter L1 of the speaker diaphragm 2C. It can be set
by. As shown in the enlarged cross-sectional view of FIG. 8B, the first diaphragm portion 21C
contributing to the reproduction of the mid-tone range and the high-tone range has one end of a
substantially cylindrical voice coil bobbin 4 (not shown) in the center on the back side. And the
inner side of the circular flat portion 23C is dome-shaped. Further, the outer side of the circular
flat portion 23C has a substantially cone shape having a rising, and has a shape connected to a
second diaphragm portion 22C described later.
10-05-2019
26
[0071]
In addition, the second diaphragm portion 22C includes the two long sides of the elongated
speaker diaphragm 2C, the short sides of the elongated speaker diaphragm 2C, and the abovedescribed two sides of the elongated speaker diaphragm 2C. Is an area defined by an imaginary
line X (or X ′) of The short-side portion of the track-shaped speaker diaphragm 2C of the
present embodiment includes a semicircular portion that defines the track shape. In the case of
the present embodiment, the average thickness of the second diaphragm portion 22C is about
1.1 mm, unchanged from that of the first diaphragm portion 21C, and is formed to have a
substantially uniform thickness.
[0072]
In the speaker diaphragm 2C of the present embodiment, since the whole is formed to have a
substantially uniform thickness, the rigidity required in the major axis direction can be secured
by devising the arrangement and shape of the reinforcing rib . Specifically, the speaker
diaphragm 2C has reinforcing ribs extending respectively in the major axis direction and the
minor axis direction, and the cross-sectional shape in the minor axis direction is substantially Wshaped. In the case of the present embodiment, of the reinforcing ribs, the two major long center
first ribs 241 and the long major center first rib 241 with the long major center rib 24 disposed
across the junction with the voice coil bobbin 4 (not shown). A convex dome portion formed to
protrude is formed at the center of the circular flat portion 23C which is composed of the two
ribs 242 and constitutes the joint portion. Then, two long-diameter both-end ribs 25C formed at
both ends in the minor-diameter direction of the speaker diaphragm 2C are continuously formed
across the first diaphragm portion 21C and the respective second diaphragm portions 22C. Ru.
[0073]
The first major-diameter first rib 241 and the second major-diameter second rib 242
symmetrically arranged with respect to the center point O are, as shown in FIG. 8, a first
diaphragm portion 21C and respective second diaphragm portions 22C. It is formed continuously
over the Further, the major diameter central rib height YL defining the rib heights of the major
diameter central first rib 241 and the major diameter central second rib 242 is respectively the
highest in the first diaphragm portion 21, and in the second diaphragm portion 22. It becomes
lower toward one end in the major axis direction. Furthermore, the first diameter major first rib
10-05-2019
27
241 and the second major diameter second rib 242 have the widest width defined in front view
of the speaker diaphragm 2C in the first diaphragm portion 21 and the second diaphragm
portion 22. The width narrows toward one end in the major axis direction. In the first diaphragm
portion 21C, two long diameter end ribs 25C are formed at both ends in the short diameter
direction outside the circular flat portion 23C, and a convex dome portion is formed inside the
circular flat portion 23C. Therefore, even if the major central first rib 241 and the major central
second rib 242 are separated, the rigidity in the major diameter direction of the speaker
diaphragm 2 is improved, and as will be described later, the relatively flat reproduction sound
pressure frequency Characteristics can be realized.
[0074]
On the other hand, the edge 3C is an edge having substantially the same configuration as that
described in the first embodiment except that the shape of the reinforcing body 34C at the outer
peripheral end is different, and the cutting inner diameter is about 259.5 mm × about 22.0 mm.
, A semicircular arc shaped track with a radius of about 11.0 mm. Specifically, the edge 3C is a
free edge portion (first free edge portion 31C) that freely supports both ends in the minor axis
direction of the speaker diaphragm 2C on the long side of the track shape extending linearly in
the major axis direction of the speaker diaphragm 2C. And a second free edge portion 32C. ) And
a fixed edge portion 33C for fixedly supporting the speaker diaphragm 2C on the short side of
the track shape to be arc-shaped, and the flexible foam rubber is injected into the mold and
thermally foamed to form It is A heat fusible adhesive is applied to the outer peripheral portion
of the speaker diaphragm 2C and dried, and then the speaker diaphragm 2C and the edge 3C are
adhered by heat pressing using a bonding die, and the reinforcing body 34C is also formed. A
diaphragm finished product integrally formed can be obtained.
[0075]
Therefore, the electrodynamic speaker 1C (not shown) provided with the elongated speaker
diaphragm 2C and the edge 3C of the present embodiment is flexibly supported by the
compliance of the free edge portion of the edge 3C in the short diameter direction, In the major
axis direction, bending and vibration occur due to the flexibility of the thermoplastic resin foam
sheet forming the speaker diaphragm C2. As a result, as will be described later, since the
symmetry of the front-rear amplitude of the speaker diaphragm 2C can be improved by the
rigidity of the major long center first rib 241 and the major long center second rib 242, the
reproduction sound quality is excellent with less distortion. An electrodynamic speaker is
realized.
10-05-2019
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[0076]
FIG. 9 is a graph for explaining reproduced sound pressure frequency characteristics of the
electrodynamic speaker 1C provided with the elongated speaker diaphragm 2C and the edge 3C
of this embodiment. Further, FIG. 10 is a graph showing a displacement amount of longitudinal
amplitude when a driving force is applied to the voice coil 4 having the speaker diaphragm 2C in
the electrodynamic speaker 1C of the present embodiment, and a value in the longitudinal
direction By taking the absolute value of, the characteristic curve of the graph is folded, and it is
displayed that the forward displacement curve and the backward displacement curve overlap
when the front-rear symmetry is good.
[0077]
In the electrodynamic speaker 1C of this embodiment, as shown in FIG. 9, the asymmetry of the
longitudinal amplitude seen in the case of the comparative example of the previous embodiment
is improved, and even-order distortion due to the longitudinal asymmetry, Also, the occurrence of
malfunction such as the generation of rattling noise can be reduced. Further, as shown in FIG. 10,
the electrodynamic speaker 1C provided with the elongated speaker diaphragm 2C and the edge
3C of the present embodiment realizes relatively flat frequency characteristics as in the other
embodiments. And the displacement front and back symmetry is improved, as a result of which
good sound reproduction is possible.
[0078]
The speaker diaphragms of these embodiments may be other narrow shape or speaker
diaphragms of different dimensions corresponding to the diameter of the voice coil. In addition,
the electrodynamic speaker using this is not limited to the track-type speaker diaphragm, but is
an elongated electrodynamic speaker having a large ratio of major axis dimension to minor axis
dimension such as oval, oval, rectangular, or rectangular. If it is
[0079]
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29
The speaker magnetic circuit of this embodiment may be a magnetic circuit of different
dimensions corresponding to other voice coil diameters. In any magnetic circuit such as internal
magnet type, external magnet type, or repulsive type, the width of the magnetic circuit is smaller
than the width of the elongated frame, and the approximately cylindrical voice coil is at the
center of the back of the speaker diaphragm. It may be an electrodynamic speaker using another
magnetic circuit as long as it can be attached to the
[0080]
The electrodynamic speaker according to the present invention can be applied not only to a
speaker incorporated in video and audio equipment such as a display, but also to a game
machine such as a game machine having a cabinet incorporating a speaker for reproducing audio
and a slot machine etc. It is. In addition, the electrodynamic speaker including the magnetic
circuit for a speaker according to the present invention can realize a speaker system that
reproduces audio in a small-sized and thin cabinet having a narrow width, and is particularly
applicable to a vehicle speaker having a limited installation space. Suitable.
[0081]
It is a figure explaining the electrodynamic-type speaker 1 by preferable embodiment of this
invention. (Example 1) A diagram illustrating an electrodynamic speaker 1 according to a
preferred embodiment of the present invention. (Example 1) It is a figure explaining the speaker
diaphragm 2 and edge 3 by preferred embodiment of this invention. (Example 1) It is a figure
explaining the speaker diaphragm 2 and edge 3 by preferred embodiment of this invention.
(Example 1) It is a graph explaining the operation of the electrodynamic speaker 1 according to a
preferred embodiment of the present invention. (Example 1) In the electrodynamic speaker 1
according to a preferred embodiment of the present invention, it is a graph showing the amount
of displacement of the longitudinal amplitude when a driving force is applied. (Example 1) It is a
graph explaining the reproduction sound pressure frequency characteristic of the electrodynamic
speaker 1B according to another preferred embodiment of the present invention. (Example 3)
FIG. 6 is a view for explaining a speaker diaphragm 2C and an edge 3C according to a preferred
embodiment of the present invention. (Example 4) In the electrodynamic speaker 1C according to
a preferred embodiment of the present invention, it is a graph showing the amount of
displacement of the longitudinal amplitude when a driving force is applied. (Example 4) A graph
illustrating the reproduced sound pressure frequency characteristics of the electrodynamic
speaker 1C according to another preferred embodiment of the present invention. (Example 4)
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30
Explanation of sign
[0082]
DESCRIPTION OF SYMBOLS 1, 1C Electrodynamic-type speaker 2, 2A, 2B, 2C Speaker diaphragm
21, 21C 1st diaphragm part 22, 22C 2nd diaphragm part 23, 23C Round flat part 24, 241, 242
Major diameter center rib 25, 25C Long diameter end rib 26, 26C short diameter end rib 3 edge
31 first free edge portion 32 second free edge portion 33 fixed edge portion 34 reinforcement 4
voice coil 5 damper 6 frame 7 terminal 8 tinsel wire 10 magnetic circuit 11 top plate 12 Center
pole 13 Magnetic air gap 14 Under plate 15a, 15b Main magnet
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31
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