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JP2009060574

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DESCRIPTION JP2009060574
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 SOLUTION: An elongated speaker diaphragm has a first
diaphragm portion and a reinforcing rib continuously formed across the respective second
diaphragm portions, and the reinforcing rib is formed of the diaphragm body. A long diameter
center rib formed in the center portion in the short diameter direction and two sub long diameter
ribs disposed across the long diameter central rib, and respective end portions of the sub long
diameter rib are formed in the first diaphragm portion The central portion of the diaphragm
main body in the short diameter direction is approached to be connected to the major diameter
central rib. [Selected figure] Figure 7
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.
[0002]
12-05-2019
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, 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
speaker. There are some which try to absorb and reduce distortion due to deformation or the like
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2
and prevent deterioration of the sound quality due to these (Patent Document 3).
[0005]
Also, conventionally, in the modified speaker in which the outer periphery 3 of the diaphragm 4
is not a perfect circle, the rigidity of the speaker edges 1 and 2 is in the circumferential direction
of the diaphragm so that the sound quality does not deteriorate due to the disturbance of sound
pressure frequency characteristics. In some cases, the edge 1 with large rigidity is used near the
minor axis 5 and the major axis 6 where the resonance of the diaphragm is large, and the other
edge is used with the edge 2 with small rigidity. By making the rigidity in the circumferential
direction of the odd-shaped speaker different, the disturbance of the sound pressure frequency
characteristic resulting from the unnecessary vibration peculiar to the odd-shaped speaker is
suppressed so as not to cause the deterioration of the sound quality (Patent Document 4) .
[0006]
Furthermore, conventionally, in a track-type speaker in which the longitudinal and lateral
dimensions of the speaker shape are the longitudinal side and the short side, the magnet (3)
constituting the magnetic circuit has a large shape within a range substantially falling within the
speaker outer shape. The shape of the pole (1) and the voice coil VC constituting the magnetic
circuit is an elongated shape extending along the direction of the longitudinal side, while
securing the width dimension of the damper between the voice coil VC and the longitudinal side
When the pole shape of the pole (1) is a circle, the track type speaker has a cross section such as
a circle having a diameter of 1/3 or more of the dimension a of the short side. (Patent Document
5). In addition, a magnetic circuit in which at least two rod-like magnets are held in parallel by an
upper plate and a lower plate across a rod-shaped center pole portion provided on the lower
plate, a frame coupled to the magnetic circuit, and A speaker comprising: a diaphragm coupled to
an outer peripheral portion of a frame; and a voice coil coupled to the diaphragm and a part of
which is disposed in a magnetic gap of the magnetic circuit, the upper plate The magnetic gap
formed of the lower plate has at least two parallel straight portions, and the magnetic gap
window of the upper plate and the voice coil have a track shape (Patent Document 6). .
[0007]
Furthermore, in the speaker diaphragm according to the applicant of the present invention, an
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3
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 7). 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.
[0008]
JP-A-58-92198 JP-A-40-32164 JP-A-2001-285991 JP-A-7-15792 JP-A-2000-197190 JP-A2004-266337 JP-A-2007-180910
[0009]
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 7 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.
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4
[0010]
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
[0011]
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 including a junction with a voice coil at a central portion on the
back side, a second diaphragm extending respectively to both ends in the major axis direction of
the first diaphragm, and a first diaphragm 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. The reinforcing
rib has a free edge portion for free supporting and a fixing edge portion formed thicker than the
free edge portion to fix and support one end in the major axis direction of the second diaphragm
portion, and the reinforcing rib is vibrating A major diameter central rib formed at the central
portion in the minor diameter direction of the plate body and a major diameter central rib It
includes a two sub diameter ribs disposed, the respective ends of the sub-major axis ribs, close to
the central portion of the short diameter direction of the diaphragm body in the first diaphragm
portion, connected to the major axis central rib.
[0012]
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, 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.
[0013]
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
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5
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 short-diameter both-end
ribs formed at one end of the second diaphragm portion in the long-diameter direction, the shortdiameter both-end ribs connecting respective long-diameter both-end ribs Do not connect with
[0014]
Preferably, in the speaker diaphragm of the present invention, the major diameter central rib
heights defining the rib height of the major diameter central rib of the reinforcing rib are
respectively the highest at the first diaphragm portion and the major diameter at the second
diaphragm portion It gets lower towards one end of the direction.
[0015]
Further, in the electrodynamic speaker according to the present invention, the above-mentioned
speaker diaphragm, a frame to which the outer peripheral end side of the edge is fixed, a
magnetic circuit fixed to the frame and having a magnetic gap, and a junction of the speaker
diaphragm are connected And a voice coil including a voice coil.
[0016]
Further, in the electrodynamic speaker according to the present invention, the magnetic circuit
has a linear magnetic gap having two parallel sides, and the voice coil is a track-shaped voice coil
disposed in the magnetic circuit, and the track-shaped voice And a coil support.
[0017]
Still preferably, in an electrodynamic speaker according to the present invention, the two minor
major ribs of the diaphragm main body of the speaker diaphragm each have a junction of a
straight portion of the voice coil and a major rib at each cross section in the minor diameter
cross section. Formed between
[0018]
Hereinafter, the operation of the present invention will be described.
[0019]
The speaker diaphragm according to the present invention comprises an elongated (rectangular,
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6
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.
The diaphragm body is a thermoplastic resin foam sheet in which the thickness of the foam of
the contained thermoplastic resin is substantially uniform or uneven by using a vacuum forming
method in which the plug assist molding is used in combination Typically, the surface of a
foamed polystyrene sheet is laminated 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 an elongated electrodynamic
speaker by including a frame, a magnetic circuit, and a voice coil including a voice coil.
[0020]
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.
Further, the voice coil includes a coil through which an audio signal current is conducted, and a
structure in which the coil is disposed in the magnetic gap of the magnetic circuit.
The voice coil typically includes a voice coil formed by winding a coil of copper wire around a
tubular voice coil bobbin.
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7
Alternatively, in the voice coil, a coil in which a conductive metal coil pattern is bonded to a heatresistant film to form an annular shape is an annular shape having substantially the same shape
as the coil, and the coil is disposed in the magnetic gap Including those formed with a support
member.
[0021]
The diaphragm main body of the speaker diaphragm of the present invention is extended to the
first diaphragm including the junction with the voice coil at the center on the back side and the
both ends in the major axis 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.
[0022]
The first diaphragm portion is a portion to which a cylindrical or track-shaped voice coil is
attached at the central portion on the back side of the speaker diaphragm, includes a projected
cross-sectional area of the voice coil, and is an elongated speaker diaphragm And two imaginary
lines that cross between the long sides in the minor axis direction.
In addition, the second diaphragm portion is a region extending from the 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 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.
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8
[0023]
For example, the major diameter central rib of the reinforcing rib is formed at the central portion
in the minor diameter direction of the diaphragm main body, and one second diaphragm portion,
the first diaphragm portion, and the other second diaphragm portion It may be a rib continuously
formed so as to cross. The reinforcing rib further includes two minor long ribs arranged on both
sides of the major center rib, and respective end portions of the minor long ribs approach the
central portion in the minor axis direction of the diaphragm main body in the first diaphragm
portion. And may be connected to the major diameter central rib. The reinforcement rib including
the major diameter central rib and the two minor major diameter ribs enables reproduction of
the middle to high tone range by the first diaphragm portion as described later, while the major
diameter direction of the elongated speaker diaphragm The symmetry of the longitudinal
amplitude can be secured while enhancing the rigidity of the
[0024]
On the other hand, the edge is formed so as to be thicker than the free edge portion for freely
supporting the end portions in the minor axis direction of the first diaphragm portion and the
second diaphragm portion, and is formed thicker in the second diaphragm portion. And a fixed
edge portion for fixedly supporting one end in the major axis direction. 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.
[0025]
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
12-05-2019
9
rib, so that an electrodynamic speaker excellent in reproduction sound quality with less
distortion can be realized.
[0026]
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.
[0027]
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.
[0028]
If the voice coil has a circular magnetic gap corresponding to the shape of the magnetic gap of
the magnetic circuit, the voice coil may have a circular coil and a cylindrical voice coil bobbin or
a voice coil support. Just do it. Also, in the case where the magnetic circuit has a magnetic air gap
including parallel straight portions corresponding to an elongated shape, the voice coil is
disposed in the magnetic circuit, and the track-shaped coil and the track-shaped coil support And
as long as it is provided. In particular, in the case of having a track-shaped voice coil, in the
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10
electrodynamic speaker of the present invention, the two minor major ribs of the diaphragm
main body of the speaker diaphragm respectively have linear portions of the voice coil in a cross
section in the minor axis direction If it is formed between the joint portion and the long diameter
end ribs, the rigidity of the first diaphragm including the track-shaped long side of the voice coil
is strengthened to suppress the divided vibration and enhance the voice reproduction capability.
Can.
[0029]
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
[0030]
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 Is formed continuously across the first diaphragm portion
and the respective second diaphragm portions for the purpose of providing an electrodynamic
speaker suitable for attachment to equipment such as a display, etc. A free edge portion having a
reinforcing rib, the edge freely supporting an end portion in the minor axis direction of the first
diaphragm portion and the second diaphragm portion, and a thickness greater than the free edge
portion. (2) A fixed edge portion for fixedly supporting one end of the diaphragm portion in the
long diameter direction, and a reinforcing rib is formed at a central portion in the short diameter
direction of the diaphragm body, and a long diameter center Two minor long ribs placed across
the rib Includes, respective ends of the sub-major axis ribs, close to the central portion of the
short diameter direction of the diaphragm body in the first diaphragm portion, by so connecting
the major diameter central rib and realized.
[0031]
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.
[0032]
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11
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.
[0033]
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
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.
[0034]
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
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12
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.
[0035]
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,
while the flexibility of the polystyrene paper forming the loudspeaker diaphragm 2 in the major
axis direction The bending vibration is made possible.
[0036]
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 13 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.
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[0037]
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.
[0038]
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
5 is vibratably supported on the frame 6.
[0039]
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.
[0040]
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14
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.
[0041]
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.
[0042]
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
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.
[0043]
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
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15
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.
[0044]
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. 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.
[0045]
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.
[0046]
The speaker diaphragm 2 of this embodiment is formed by extrusion-forming polystyrene paper
12-05-2019
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(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: 4.6 E + 8 (dyne / cm <2>),
density: 0.43 (g / cm <3>), tan δ: 0.043 in the case of PSP alone Young's modulus: 9.7 E + 8
(dyne / cm <2>), density: 0.55 (g / cm <3>), tan δ: 0.074, when polystyrene films are laminated
on both sides of PSP as in this example. It can be improved to an excellent value.
[0047]
The outer dimensions of the track-type speaker diaphragm 2 are about 198 mm in the major axis
direction and about 23.4 mm in the minor axis direction. 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 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.
[0048]
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.
12-05-2019
17
[0049]
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.
[0050]
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
and can be set within about 1/2 of the length in the longitudinal direction of the speaker
diaphragm is there. 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.
[0051]
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
12-05-2019
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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.
[0052]
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
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.
[0053]
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
12-05-2019
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also integrally formed.
[0054]
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.
[0055]
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
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 fills 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 with the foam rubber so as not to
vibrate freely. The foam rubber has a thickness of 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.
[0056]
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
12-05-2019
20
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.
[0057]
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
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.
[0058]
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
12-05-2019
21
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.
[0059]
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。
[0060]
FIG. 7 and FIG. 8 are diagrams for explaining a speaker diaphragm 2A and an edge 3A of another
embodiment. FIG. 7 is a perspective view of the speaker diaphragm 2A and the edge 3A as
viewed obliquely from above the front side. 8 (a) is a cross-sectional view taken along the line B-B
'showing a cross section in the minor axis direction of the speaker diaphragm 2A and the edge
3A, and FIG. 8 (b) is a cross-sectional view taken along the line C-C'. 8 (c) is a cross-sectional view
taken along line DD ', and FIG. 8 (d) is a cross-sectional view taken along line EE'. As will be
described later, the structure of the speaker diaphragm 2A and a part of the edge 3A, the crosssectional 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.
[0061]
The speaker diaphragm 2A of the present 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 2A 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-mentioned vacuum forming method using plug assist molding. Is formed. The outer
12-05-2019
22
dimensions of the track-type speaker diaphragm 2A are approximately 262.0 mm in the major
axis direction and approximately 25.5 mm in the minor axis direction. The first diaphragm
portion 21A and the second diaphragm portion 22A of the speaker diaphragm 2A are defined in
the same manner as the previous embodiment.
[0062]
That is, in the central portion of the speaker diaphragm 2A, the first diaphragm portion 21A
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 this 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 a half of the length in the major axis direction of the speaker diaphragm 2A. It can
be set. As shown in the cross-sectional view of FIG. 8 (a), the first diaphragm portion 21A
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) It includes a circular flat portion 23A to
be attached. In addition, the second diaphragm portion 22A includes the two long sides of the
elongated speaker diaphragm 2A, the short sides of the elongated speaker diaphragm 2A, and
the above-described two sides of the elongated speaker diaphragm 2A. Is an area defined by an
imaginary line X (or X ′) of The short-side portion of the track-shaped speaker diaphragm 2A of
the present embodiment includes a semicircular portion defining the track shape. In the case of
the present embodiment, the average thickness of the second diaphragm portion 22A is about
1.1 mm, unchanged from that of the first diaphragm portion 21A, and is formed to have a
substantially uniform thickness.
[0063]
In the speaker diaphragm 2A of the present embodiment, since the whole is formed so as to have
a substantially uniform thickness, by devising the arrangement and shape of the reinforcing rib,
the rigidity required in the major axis direction can be secured . Specifically, the speaker
diaphragm 2A 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, the reinforcing rib includes a major diameter
central rib 24A formed at a central portion in the minor diameter direction and two minor major
diameter ribs 27A disposed so as to sandwich the major diameter central rib 24A. Then, the
respective end portions of the minor long diameter rib 27A are formed so as to approach the
central portion in the minor diameter direction of the diaphragm main body in the first
12-05-2019
23
diaphragm portion 21A and to be connected to the major diameter central rib 24A. The two
minor long ribs 27A are formed to extend in the major axis direction in parallel with the major
rib 24A, and are separated from the major rib 24A in the minor axis BB ′ cross section, but in
the minor axis direction. The both ends are connected close to the long diameter center rib 24A
up to the CC ′ cross section. Therefore, the sub major rib 27A is included in the area of the first
diaphragm portion 21A defined by the imaginary lines X and X 'and reinforces the periphery of
the circular flat portion 23A to which one end of the voice coil bobbin 4 is attached.
[0064]
The long diameter center rib 24A is continuously formed across the first diaphragm portion 21A
and the respective second diaphragm portions 22A, as in the case of the previous embodiment.
Further, the major diameter central rib height YL defining the height of the major diameter
central rib 24A is the highest in the first diaphragm portion 21A and is directed to one end in the
major diameter direction in the second diaphragm portion 22A. Take it to the bottom.
Furthermore, the width defined in the front view of the speaker diaphragm 2A of the major
diameter central rib 24A is the widest in the first diaphragm portion 21A and is directed to one
end in the major diameter direction in the second diaphragm portion 22A. It becomes narrow
with. In the first diaphragm portion 21A, two long diameter end ribs 25A are formed at both
ends in the short diameter direction outside the circular flat portion 23A, and two minor long
diameter ribs 27A for reinforcing the long diameter center rib 24A are further formed. Thus, the
rigidity in the major axis direction of the speaker diaphragm 2A can be improved, and as
described later, flat reproduction sound pressure frequency characteristics can be realized in the
middle to high frequency range. Furthermore, the short diameter end ribs 26A formed in an arc
shape corresponding to the semicircular shape of the second diaphragm portion 22A connect the
respective long diameter end ribs 25A, and the outer peripheral edge of the track-type speaker
diaphragm 2A Reinforce and increase rigidity.
[0065]
The edge 3A is an edge having a configuration similar to that of the edge 3 described in the first
embodiment, and is a track-shaped edge having a cutting inner diameter of about 259 mm ×
about 22 mm and a semicircular arc having a radius of about 11 mm. The edge 3A is different
from the edge 3 of the first embodiment in the shape of the reinforcing body 34A at the outer
peripheral end and the shape of the second free edge portion 32A of the free edge portion.
Specifically, the edge 3A is a free edge portion (first free edge portion 31A that freely supports
both ends in the minor axis direction of the speaker diaphragm 2A at the long side of the track
12-05-2019
24
shape extending linearly in the major axis direction of the speaker diaphragm 2A. , And the
second free edge portion 32A. ) And a fixed edge portion 33A for fixedly supporting the speaker
diaphragm 2A 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 2A and dried, and then the speaker
diaphragm 2A and the edge 3A are bonded by heat pressing with a bonding die, and the
reinforcing body 34A is also A diaphragm finished product integrally formed can be obtained.
[0066]
In the edge 3A of the present embodiment, the shape of the second free edge portion 32A of the
free edge portion is formed to be different from the shape of the first free edge portion 31A. That
is, in the free edge portion of the edge 3 (the first free edge portion 31A, the second free edge
portion 32A) in the first embodiment, the free edge path length le which is the length when the
cross section of the support movable portion is expanded. While the corrugation constituting the
support movable portion is formed so that the free edge portion has a substantially constant
value, the second free edge path length le2 of the second free edge portion 32A of this
embodiment is The corrugation constituting the support movable portion is formed such that the
length of the support movable portion is shorter than the first free edge path length le1 of the
first free edge portion 31A.
[0067]
Specifically, the first free edge path length le1 of the first free edge portion 31A is 13.5 mm, and
the second free edge path length le2 of the second free edge portion 32A monotonously
decreases from 13.5 mm to 5 It changes to .7 mm. The second free edge path length le2 is a long
diameter starting from the boundary X (or X ′) of the first diaphragm portion 21A and the
second diaphragm portion 22A as it extends from the first free edge portion 31A to the fixed
edge portion 33A. In proportion to the length of the direction, it linearly decreases from the first
free edge path length le1. Therefore, as shown in the BB 'sectional view of FIG. 8 (a) and the CC'
sectional view of FIG. 8 (b), the first free edge portion 31A corresponding to the first diaphragm
portion 21A While the height YE1 is constant at about 2.2 mm with reference to the bottom of
the reinforcing body 34A, the DD 'cross-sectional view of FIG. 8 (c) and the E-E of FIG. 8 (d) are
obtained. As shown in the cross-sectional view, the height YE2 of the second free edge portion
32A corresponding to the second diaphragm portion 22A gradually decreases toward the fixed
edge portion 33A.
12-05-2019
25
[0068]
As in the previous embodiment, the electrodynamic speaker 1A (not shown) provided with the
elongated speaker diaphragm 2A and the edge 3A of the present embodiment has a compliance
of the free edge portion of the edge 3A in the minor axis direction. While being supported
flexibly, bending vibration is caused by the flexibility of the thermoplastic resin foam sheet
forming the speaker diaphragm 2A in the major axis direction. As a result, as will be described
later, the rigidity of the front and rear amplitudes of the speaker diaphragm 2A can be improved
by the rigidity of the two minor major ribs 27A that reinforce the major median rib 24A and the
major minor rib 24A. An electrodynamic speaker with excellent reproduction quality is realized.
Therefore, in the electrodynamic speaker 1A of this embodiment, as the elongated speaker
diaphragm 2A bends and vibrates, the amount of amplitude decreases toward the vicinity of the
fixed edge portion 33A which is both ends in the major axis direction. The second free edge path
length le2 of the second free edge portion 32A may be shorter than the first free edge path
length le1.
[0069]
FIG. 9 is a graph showing a displacement amount of longitudinal amplitude when a driving force
is applied to the voice coil 4 provided with the speaker diaphragm 2A in the electrodynamic
speaker 1A of the present embodiment. FIG. 9A shows the displacement distribution of the
speaker diaphragm 2A in the major axis direction of the AA cross section when a static driving
force is applied such that the center point O of the speaker diaphragm 2A is displaced forward by
about 7 mm. FIG. 9B is a graph showing the displacement of the back and forth amplitude of the
voice coil 4 when a driving force is applied to the voice coil 4 provided with the speaker
diaphragm 2A. In FIG. 9 (b), the characteristic curve of the graph is turned back by taking the
absolute value of the amount of displacement of the amplitude in the front-rear direction, and
when the front-rear symmetry is good, the front displacement curve and the rear displacement
curve overlap It is displayed as. Further, FIG. 10 is a graph for explaining reproduced sound
pressure frequency characteristics (200 Hz to 20 kHz) of the electrodynamic speaker 1A
provided with the elongated speaker diaphragm 2A and the edge 3A of the present embodiment.
The solid line shows the reproduced sound pressure frequency characteristics of the
electrodynamic speaker 1A provided with the speaker diaphragm 2A of the present embodiment,
and the broken line reinforces the major rib 24A in the shape of the speaker diaphragm 2A as a
comparative example. The reproduction sound pressure frequency characteristics of an
electrodynamic speaker (not shown) provided with a speaker diaphragm (not shown) which does
not include the two minor length ribs 27A (not shown).
12-05-2019
26
[0070]
As shown in FIG. 9A, the displacement of the speaker diaphragm 2A is substantially constant up
to the virtual line X which is the area of the first diaphragm portion 21A to which the voice coil 4
is attached, and the minor axis in the major axis direction In the region of the second diaphragm
portion 22A directed to the end, the amount of displacement linearly decreases. Therefore,
according to this, if the first free edge path length le1 of the first free edge portion 31A is made
constant and the second free edge path length le2 of the second free edge portion 32A is linearly
shortened accordingly Good. The electrodynamic speaker 1A suppresses abnormal resonance
that is likely to occur in the first free edge portion 31A and the second free edge portion 32A
when the voice coil 4 is largely displaced at a frequency near or below the lowest resonance
frequency f0. be able to. The electrodynamic speaker 1A can realize a flat reproduction sound
pressure frequency characteristic at a frequency at which the edge 3A tends to generate
anomalous resonance, and the operation of the speaker vibration system is stabilized and the
sound reproduction capability is improved.
[0071]
In the electrodynamic speaker 1A of this embodiment, as shown in FIG. 9 (b), the asymmetry of
the front and back amplitudes seen in the case of the comparative example of the previous
embodiment is improved, and the even number caused by the front and rear asymmetry It is
possible to reduce the occurrence of secondary distortion and malfunctioning such as the
generation of rattling noise. Further, as shown in FIG. 10, the electrodynamic speaker 1A
provided with the elongated speaker diaphragm 2A and the edge 3A of the present embodiment
achieves flat frequency characteristics in the middle to high frequency range as in the other
embodiments. can do. Also, the anteroposterior symmetry of the displacement is improved, and
as a result, good sound reproduction becomes possible.
[0072]
In addition, since the speaker diaphragm 2A of these examples is formed by extrusion and
formed of a sheet of polypropylene (PP) having a substantially uniform thickness using a vacuum
forming method in combination with plug assist forming, the first vibration is generated. In this
case, the average thickness t1 of the plate portion 21A and the second average thickness value t2
12-05-2019
27
defining the average thickness of the second diaphragm portion 22A are substantially equal.
However, as in the first embodiment, the second average thickness value t2 of the second
diaphragm portion 22A may be formed thicker than the first average thickness value t1 of the
first diaphragm portion 21A. The reproduction efficiency in the middle and high range is further
improved, and an electrodynamic speaker with a wide reproduction range is realized.
[0073]
FIG. 11 is a view for explaining an electrodynamic speaker 1B according to another preferred
embodiment of the present invention. FIG. 11 (a) is a perspective view of the electrodynamic
speaker 1B as viewed from the front side, and FIG. 11 (b) is an enlarged perspective view of a
cross section B-B 'of the electrodynamic speaker 1B. Note that, as described later, a part of the
structure of the electrodynamic speaker 1B, an internal structure, and the like are omitted. The
direction in which the straight line (long axis) connecting the points O-A extends is the major axis
direction, and the direction in which the straight line (short axis) connecting the points O-B
extends is the short axis direction.
[0074]
The electrodynamic speaker 1B of this embodiment is a slender electrodynamic speaker having a
track-type speaker diaphragm 2B having a major axis length L1 of about 300.0 mm and a minor
axis length L2 of about 45.0 mm. Even in the elongated shape, it is a speaker having a diaphragm
area equal to that of a circular diaphragm having a diameter of about 131 mm. The outer
peripheral end of the speaker diaphragm 2B is supported by the edge 3B, and the outer
peripheral end of the edge 3B is fixed to the frame 6B. Further, a track-shaped voice coil 4B is
connected to the back side of the speaker diaphragm 2B. Further, the frame 6B has an elongated
shape corresponding to the track-type speaker diaphragm 2B, and the magnetic circuit 10B fixed
to the frame 6B also has a narrow elongated shape whose width is equal to or less than the minor
axis length L2 . Therefore, the electrodynamic speaker 1B is a speaker suitable for an apparatus
with a small width for attaching the speaker, such as a side surface of a display unit of an
apparatus such as a display.
[0075]
The inner peripheral side of the edge 3B is bonded to the outer peripheral end of the speaker
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28
diaphragm 2B of the electrodynamic speaker 1B, and a coil support member 4Ba constituting the
voice coil 4B is bonded to the central back surface. The speaker diaphragm 2B is formed by
forming a foamed thermoplastic resin to reduce the weight of the speaker diaphragm. In the case
of the present embodiment, a speaker diaphragm 2B having ribs is obtained by using a vacuum
forming method in which the extruded thermoplastic resin foam sheet (specifically,
polypropylene) is used in combination with plug assist molding. ing. That is, since the elongated
speaker diaphragm 2B having significantly different lengths in the major axis direction and the
minor axis direction 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 and the minor axis direction It has
a shape that has rigidity in the major axis direction so that the cross-sectional shape is
substantially W-shaped.
[0076]
In the present embodiment, the edge 3B 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
freely support the speaker diaphragm 2B so as to freely support the speaker diaphragm 2B on
the long side of the track shape linearly extending in the long axis direction of the speaker
diaphragm 2B. 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 2B. As a result, the elongated speaker
diaphragm 2B is flexibly supported by the compliance of the free edge portion of the edge 3B in
the minor axis direction, while the foamed sheet of thermoplastic resin forming the loudspeaker
diaphragm 2B in the major axis direction. Flexibility makes it possible to vibrate in bending.
[0077]
The voice coil 4B is formed of a coil support member 4Ba formed in a track shape, and a coil
laminate 4Bb to which an audio current having a similar track shape is supplied. The coil support
member 4Ba is, for example, a member molded of a polyetheretherketone resin, and is formed in
an annular track shape having an inner diameter and an outer diameter, and as a result, has an
inner hole 4Bc on the inner diameter side. ing. The coil supporting member 4Ba connects the coil
laminate 4Bb to one end of the cylindrical shape, while the other end is connected to the center
of the back surface of the speaker diaphragm 2B by an adhesive. The coil laminate 4Bb is also
formed in an annular track shape having an inner diameter and an outer diameter, and has an
inner hole 4Bc on the inner diameter side. Therefore, in the electrodynamic speaker 1B including
the voice coil 4B, the coil laminate 4Bb is disposed in the circular magnetic air gaps 13a and 13b
of the magnetic circuit 10B described later.
12-05-2019
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[0078]
The tinsel wire 8 (not shown) solders and electrically connects the terminal 7B (not shown) fixed
to the frame 6B and the coil laminate 4Bb to supply an audio current to the coil laminate 4Bb.
The tinsel wire 8 may be connected to the terminal 7 by providing a metal eyelet on the speaker
diaphragm 2B. Of course, the tinsel cord 8 may be substituted by a lead wire coated with an
insulator.
[0079]
The frame 6B is an iron plate frame press-formed into a slender basket shape corresponding to
the shape of the speaker diaphragm 2B, and a substantially rectangular fixing portion for fixing
the edge 3B and a fixing portion for fixing the magnetic circuit 10B And a connecting portion
connecting the fixing portions, a window defined between the plurality of connecting portions,
and a mounting hole for mounting the terminal 7B. Therefore, a speaker vibration system
including the speaker diaphragm 2B, the edge 3B, and the voice coil 4B is vibratably supported
with respect to the frame 6B and the magnetic circuit 10B.
[0080]
FIG. 12 is a perspective view for explaining the magnetic circuit 10B that constitutes the
electrodynamic speaker 1B. The magnetic circuit 10B has the same direction as the elongated top
plates 11a and 11b fixed to the frame 6B, respectively, and the pole 14 including the center pole
12 arranged to be held between the top plates 11a and 11b. And two main magnets 15a and 15b
which are magnetized to The top plate 11 and the center pole 12 form magnetic air gaps 13a
and 13b including straight portions of parallel two sides having uniform widths. Main magnets
15a and 15b are held between top plate 11a and the under plate of pole 14 and between top
plate 11 b and the under plate of pole 14, respectively, and center pole 12 in the short diameter
direction. It is arranged symmetrically with the The two main magnets 15 a and 15 b are long
and thin in the major axis direction and have a substantially elongated shape corresponding to
the shape of the elongated top plates 11 a and 11 b and the pole 14. The length in the major axis
direction of the magnetic circuit 10B is about 72.5 mm, the length in the minor axis direction is
about 36.2 mm, and the width of the magnetic gaps 13a and 13b is about 1.76 mm. The center
pole 12 may be integrally formed with the under plate of the pole 14 or another piece may be
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fixed by an adhesive.
[0081]
The two main magnets 15a and 15b of the present embodiment are Nd--Fe--B rare earth magnets
having a large residual magnetization and coercive force and a large volume even with a small
volume, and may be a ferrite based magnet. The magnetic circuit 10B is an external magnet type
magnetic circuit in which a magnet is disposed outside the area to be projected when the coil
laminate 4Bb of the voice coil 4B is viewed in a plan view, and is mainly elongated in the major
axis direction and has a high coercive force. Since the magnets 15a and 15b are arranged in the
minor axis direction, they are suitable for an elongated speaker such as the electrodynamic
speaker 1B of the present invention. This is because if the maximum width of the magnetic
circuit 10B can be reduced, the magnetic circuit 10B fits within the area formed when the
elongated speaker diaphragm 2B is viewed from the front. Therefore, an electrodynamic speaker
1B with high efficiency is realized, including adopting a lightweight speaker diaphragm 2B.
[0082]
FIG. 13 is a perspective view for explaining the voice coil 4B constituting the electrodynamic
speaker 1B. The voice coil 4B is formed of a coil supporting member 4Ba and a coil laminate 4Bb
and is formed in an annular track having an inner diameter and an outer diameter, and as a
result, has an inner hole 4Bc on the inner diameter side There is. Further, the track shape is
composed of two straight portions 4Bd parallel to each other along the major axis direction and
an arc portion 4Be connecting the long diameter side end portions of the straight portions 4Bd.
In the case of this embodiment, the voice coil 4B has a track shape having an outer length of
about 81.2 mm in the major axis direction, an outer length of about 12.7 mm in the minor axis
direction, and a radius of the circular arc part 4Be of about 6.35 mm. And corresponds to a
circular voice coil of about 64.4 mm in diameter. Further, the total height of the voice coil 4B is
about 5.6 mm, and the width of the straight portion 4Bd is about 1.3 mm. Two notches are
provided in one arc portion 4Be, and one end of each of the tinsel cords 8a and 8b electrically
connected to the coil laminate 4Bb is soldered and fixed thereto.
[0083]
In the electrodynamic speaker 1B, linear portions 4Bd on two parallel sides of the track-shaped
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voice coil 4B are disposed in the magnetic gaps 13a and 13b including linear portions on two
parallel sides of the magnetic circuit 10B. When the magnetic circuit 10B is viewed from the side
in the major axis direction, the major end portions 16a and 16b where the magnets 15a and 15b
are not disposed are formed, so that the arc portion 4Be of the track-shaped voice coil 4B
protrudes therefrom. Exposed. Since the voice coil 4B connects the tinsel cords 8a and 8b to the
track-shaped arc portion 4Be and takes it out, the tinsel cords 8a and 8b are led out to the
terminal 7B so as not to interfere with the magnetic circuit 10B. In the magnetic circuit 10B, the
long diameter end portions 16a and 16b are covered with a dustproof member formed of a
breathable woven or non-woven fabric or the like so that foreign matter such as iron powder
intrudes into the magnetic gaps 13a and 13b. You may make it prevent.
[0084]
When an audio current is supplied to the coil stack 4Bb of the voice coil 4B through the tinsel
wires 8a and 8b, a driving force acts on the linear portions 4Bd disposed in the magnetic gaps
13a and 13b, and the voice coil 4B is shown in FIG. It vibrates in the up-down direction in FIGS. 1
to 3 and the coupled speaker diaphragm 2B also vibrates in the up-down direction. In the
magnetic circuit 10B, since the magnetic gaps 13a and 13b including straight portions on two
parallel sides have equal widths in the major axis direction, the magnetic flux density distribution
becomes substantially constant in the major axis direction, and the parallel voice coil 4B in the
major axis direction. A substantially constant driving force is generated along the straight
portions 4Bd of the two sides. In the speaker diaphragm 2B, the free edge portion of the edge 3B
supporting the outer peripheral end of the speaker diaphragm 2B is flexibly supported in the
minor axis direction, while the flexibility of the thermoplastic resin foam sheet forming the
speaker diaphragm 2B in the major axis direction It becomes possible to vibrate by bending.
When the voice coil 4B is largely displaced at a frequency near or below the lowest resonance
frequency f0, the speaker diaphragm 2B to which both ends in the major axis direction are fixed
bends in a major axis direction and deforms.
[0085]
The voice coil 4B of this embodiment includes a coil laminate 4Bb and a coil support member
4Ba for arranging the coil laminate 4Bb in the magnetic gaps 13a and 13b of the magnetic
circuit 10B. The coil laminate 4Bb is formed by etching. It is a coil laminated body in which a
plurality of conductive metal (not shown) coil patterns 45p and a heat resistant film 45x (not
shown) to which the coil patterns 45p are attached are laminated. Specifically, in the case of the
coil laminate 4Bb of the present embodiment, an eight-layer coil laminate 4Bb in which coil
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layers 45a to 45h (not shown) are laminated is formed. The coil layers 45a to 45h are each
formed by etching a conductive metal coil pattern 45p on the heat resistant film 45x. In the
present embodiment, the heat-resistant film 45x is a polyimide film having a thickness of 50 μm,
and the coil pattern 45p is a copper foil having a thickness of 18 μm, which are adhered by an
adhesive. The coil pattern 45p is formed by etching a copper foil bonded to a polyimide film 45x,
and has a conductor width of 0.3 mm, a conductor pitch of 0.1 mm, and a through hole land at a
start point 45s1 and an end point 45s2 Is a coil of about 2 turns each having In each of the coil
layers 45a to 45h, a total of nine through hole lands 45s0 are provided at predetermined
positions common to the arc portion 4Be of the voice coil 4B, and the start point 45s1 and the
end point 45s2 of the coil pattern 45p are It is selected from two of them. In coil laminated body
4Bb, two laminated coil patterns 45p conduct electricity by copper plating through land holes
45s0 formed at respective start points 45s1 or end points 45s2, and eight layers of coil patterns
45p are connected in series. Form a voice coil. By connecting the tinsel wires 8a and 8b, a trackshaped coil having a total of about 16 turns and a DC resistance of about 8.39 Ω is formed. The
copper plating may be silver plating.
[0086]
Since the coil support member 4Ba is formed to have a track-shaped inner diameter and an outer
diameter substantially the same shape as the coil laminate 4Bb, the long diameter side of the two
straight portions 4Bd parallel to the long diameter direction and the straight portion 4Bd An arc
portion 4Be connecting the end portions is provided, and an inner hole 4Bc for accommodating
the center pole 12 of the magnetic circuit 10B is provided on the inner diameter side thereof.
The coil supporting member 4Ba is a member formed by injection molding of a resin or punching
out a resin member having a certain thickness with a press die, and has a track shape having a
thickness of about 1.3 mm. The coil laminate 4Bb is bonded to the lower end surface of the coil
support member 4Ba with an adhesive. Further, the connection between the coil support member
4Ba and the coil laminate 4Bb may be performed by heating using an epoxy prepreg sheet
instead of the adhesive. Therefore, coil support member 4Ba can arrange coil layered product
4Bb in magnetic air gaps 13a and 13b of magnetic circuit 10B. In addition, the member which
forms coil supporting member 4Ba is not restricted to the case of a present Example, A synthetic
resin, chemical wood (urethane), polypropylene (PP), polyimide, polyester, polycarbonate (PC),
epoxy, phenol It may be unsaturated polyester or the like, and may be a resin such as urethane,
acrylic, PC, PP or the like containing foam beads for weight reduction.
[0087]
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33
FIG. 14 and FIG. 15 are views for explaining the speaker diaphragm 2B and the edge 3B of this
embodiment. FIG. 14 is a perspective view of the speaker diaphragm 2B and the edge 3B as
viewed obliquely from above the front side. 15 (a) is a cross-sectional view taken along the line BB 'showing a cross section in the minor axis direction of the speaker diaphragm 2B and the edge
3B, and FIG. 15 (c) is a cross-sectional view taken along the line DD ', and FIG. 15 (d) is a crosssectional view taken along the line E-E'. In addition, as will be described later, the structure of the
speaker diaphragm 2B and a part of the edge 3B, 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.
[0088]
The speaker diaphragm 2B of the present embodiment is, similarly to the second embodiment, by
using a vacuum forming method in which a sheet of polypropylene (PP) which is extruded and
has a substantially uniform thickness is used in combination with plug assist molding. It is
formed to have a reinforcing rib. The outer dimensions of the track-type speaker diaphragm 2B
are approximately 262.0 mm in the major axis direction and approximately 25.5 mm in the
minor axis direction. The first diaphragm portion 21B and the second diaphragm portion 22B of
the speaker diaphragm 2B are defined in the same manner as the previous embodiment.
However, the speaker diaphragm 2B of the present embodiment is provided with the flat portion
23B of the track shape to which one end of the voice coil 4B of the track shape is attached
corresponding to the voice coil 4B of the track shape. As compared with the case where the
circular voice coil bobbin 4 is attached, the area of the first diaphragm portion 21B is wider, and
the two minor major ribs 27B disposed so as to sandwich the major diameter central rib 24B are
longer.
[0089]
That is, in the central portion of the speaker diaphragm 2B, the first diaphragm portion 21B has
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
110.0 mm, which is longer than the external length of the track-shaped voice coil 4B in the long
diameter direction, and 1 in the long diameter direction of the speaker diaphragm 2B. It can be
set in the range of about 2 or less. As shown in the cross-sectional view of FIG. 15 (a), the first
diaphragm portion 21B contributing to the reproduction of the mid and high tone regions has
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one end of a substantially cylindrical voice coil bobbin 4 (not shown) in the center on the back
side. It includes a track-shaped flat portion 23B to be attached.
[0090]
In addition, the second diaphragm portion 22B includes the two long sides of the elongated
speaker diaphragm 2B, the short sides of the elongated speaker diaphragm 2B, and the abovedescribed two sides of the elongated speaker diaphragm 2B. Is an area defined by an imaginary
line X (or X ′) of The short-side portion of the track-shaped speaker diaphragm 2B 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 22B is about
1.1 mm, unchanged from that of the first diaphragm portion 21B, and is formed to have a
substantially uniform thickness.
[0091]
In the speaker diaphragm 2B 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 the shape of the reinforcing rib . Specifically, the speaker
diaphragm 2B 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, the reinforcing rib includes a major diameter
central rib 24B formed at a central portion in the minor diameter direction and two minor major
diameter ribs 27B disposed so as to sandwich the major diameter central rib 24B. The respective
end portions of the minor long diameter rib 27B are formed so as to approach the central portion
in the minor axis direction of the diaphragm main body in the first diaphragm portion 21B and to
be connected to the major diameter central rib 24B. The minor major diameter rib 27B is formed
between the flat portion 23B, which is a joint portion of the straight portion of the voice coil, and
the major diameter both-end rib 25B in the cross section in the minor diameter direction.
Although the two minor long ribs 27B are separated from the major rib 24B in the minor
diameter direction B-B 'cross section, the major minor rib 24B is located between the minor
diameter direction rib C and the minor C-C' cross section. The both ends are connected.
Therefore, the sub major rib 27B is included in the area of the first diaphragm portion 21B
defined by the imaginary lines X and X ', and reinforces the periphery of the track-shaped flat
portion 23B to which one end of the voice coil bobbin 4 is attached.
12-05-2019
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[0092]
The major diameter central rib 24B is continuously formed across the first diaphragm portion
21B and the respective second diaphragm portions 22B as in the case of the previous
embodiment. Further, the major diameter central rib height YL defining the height of the major
diameter central rib 24B is the highest in the first diaphragm portion 21B and is directed to one
end in the major diameter direction in the second diaphragm portion 22B. Take it to the bottom.
Furthermore, the width defined in the front view of the speaker diaphragm 2B of the major
diameter central rib 24B is the widest in the first diaphragm portion 21B and is directed to one
end in the major diameter direction in the second diaphragm portion 22B. It becomes narrow
with. In the first diaphragm portion 21B, two long-diameter both-end ribs 25B are formed at both
ends in the short-diameter direction outside the flat portion 23B of the track shape, and two
minor long-diameter ribs 27B for reinforcing the long-diameter central rib 24B are further
formed As a result, the rigidity in the longitudinal direction of the speaker diaphragm 2B can be
improved, and as described later, relatively flat reproduced sound pressure frequency
characteristics can be realized. Furthermore, the short diameter end ribs 26B formed in an arc
shape corresponding to the semicircular shape of the second diaphragm portion 22B connect the
respective long diameter end ribs 25B, and the outer peripheral edge of the track-type speaker
diaphragm 2B Reinforce and increase rigidity.
[0093]
The edge 3B is an edge having a configuration similar to that of the edge 3 described in the first
embodiment, and is a track shaped edge having a cutting inner diameter of about 259 mm ×
about 22 mm and a semicircular arc having a radius of about 11 mm. The edge 3B is different
from the edge 3A of the second embodiment in the shape of the second free edge portion 32B of
the free edge portion. Specifically, the edge 3B is a free edge portion (first free edge portion 31B)
for freely supporting both ends in the minor axis direction of the speaker diaphragm 2B at the
long side of the track shape extending linearly in the major axis direction of the speaker
diaphragm 2B. , And a second free edge portion 32B. ) And a fixed edge portion 33B for fixedly
supporting the speaker diaphragm 2B at 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 2B and
dried, and then the speaker diaphragm 2B and the edge 3B are stuck by heat pressing with a
bonding die, and the reinforcing body 34B is also A diaphragm finished product integrally
formed can be obtained.
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[0094]
In the edge 3B of this embodiment, similarly to the edge 3A of the second embodiment, the shape
of the second free edge portion 32B of the free edge portion is formed to be different from the
shape of the first free edge portion 31B. . That is, in the second free edge portion 32B of this
embodiment, the support movable portion is configured such that the second free edge path
length le2 is shorter than the first free edge path length le1 of the first free edge portion 31B.
Corrugation is formed, and the area of the first diaphragm portion 21B becomes larger
corresponding to the provision of the track-shaped voice coil 4 as compared with the case of the
edge 3A of the previous embodiment. The ratio in the major axis direction of the first free edge
portion 31B is long, and the ratio of the second free edge portion 32B is small. Specifically, the
first free edge path length le1 of the first free edge portion 31B is 13.5 mm, and the second free
edge path length le2 of the second free edge portion 32B monotonously decreases from 13.5
mm to 5 It changes to .7 mm. The second free edge path length le2 is a long diameter starting
from the boundary X (or X ′) of the first diaphragm portion 21B and the second diaphragm
portion 22B as it extends from the first free edge portion 31B to the fixed edge portion 33B. In
proportion to the length of the direction, it linearly decreases from the first free edge path length
le1. Therefore, as shown in the BB 'sectional view of FIG. 15 (a) and the CC' sectional view of FIG.
15 (b), the first free edge portion 31B corresponding to the first diaphragm portion 21B The
height YE1 is constant at about 2.2 mm with reference to the bottom of the reinforcing body
34B, while the DD ′ cross-sectional view of FIG. 15 (c) and E-E of FIG. 15 (d). As shown in the
cross-sectional view, the height YE2 of the second free edge portion 32B corresponding to the
second diaphragm portion 22B gradually decreases toward the fixed edge portion 33B.
[0095]
As in the case of the previous embodiment, the electrodynamic speaker 1B provided with the
elongated speaker diaphragm 2B and the edge 3B of the present embodiment is flexibly
supported by the compliance of the free edge portion of the edge 3B in the short diameter
direction. On the other hand, in the major axis direction, bending and vibration occur due to the
flexibility of the thermoplastic resin foam sheet forming the speaker diaphragm 2B. As a result,
as will be described later, the symmetry of the front and rear amplitudes of the speaker
diaphragm 2B can be improved by the rigidity of the two minor major ribs 27B that reinforce the
major median rib 24B and the major minor rib 24B. An electrodynamic speaker with excellent
reproduction quality is realized.
[0096]
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FIG. 16 shows a cross section taken along the major axis O-A when a static driving force is
applied such that the center point O of the speaker diaphragm 2B is displaced about 5 mm on the
front side in the electrodynamic speaker 1B of this embodiment. It is a graph which shows
displacement distribution of the speaker diaphragm 2B in. FIG. 17 is a graph for explaining the
reproduced sound pressure frequency characteristics of the electrodynamic speaker 1B provided
with the elongated speaker diaphragm 2B and the edge 3B of this embodiment.
[0097]
As shown in FIG. 16, the displacement amount of the speaker diaphragm 2B is substantially
constant up to the virtual line X which is a region of the first diaphragm portion 21B to which
the voice coil 4B is attached. The amount of displacement linearly decreases in the region of the
second diaphragm portion 22B toward the Therefore, according to this, if the first free edge path
length le1 of the first free edge portion 31B is made constant and the second free edge path
length le2 of the second free edge portion 32B is linearly shortened accordingly Good. The
electrodynamic speaker 1B suppresses abnormal resonance that tends to occur in the first free
edge portion 31B and the second free edge portion 32B when the voice coil 4B is largely
displaced at a frequency near or below the lowest resonance frequency f0. be able to. The
electrodynamic speaker 1B can realize a flat reproduction sound pressure frequency
characteristic at a frequency at which the edge 3B tends to generate abnormal resonance, and
the operation of the speaker vibration system is stabilized and the sound reproduction capability
is improved.
[0098]
In addition, since the speaker diaphragm 2B of these Examples is formed by extrusion and
formed of a sheet of polypropylene (PP) having a substantially uniform thickness using a vacuum
forming method in combination with plug assist forming, the first vibration is generated. In this
case, the average thickness t1 of the plate portion 21B and the second average thickness value t2
defining the average thickness of the second diaphragm portion 22B are substantially equal.
However, as in the first embodiment, the second average thickness value t2 of the second
diaphragm portion 22B may be formed thicker than the first average thickness value t1 of the
first diaphragm portion 21B. The reproduction efficiency in the middle and high range is
improved, and an electrodynamic speaker with a wide reproduction range is realized.
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[0099]
As shown in FIG. 11, the electrodynamic speaker 1B according to the present embodiment has
the thin-walled speaker diaphragm 2B, but the thickness of the laminated coil stack 4Bb is
reduced to about 0.6 mm. And the voice coil 4B is not in contact with the magnetic circuit 10B
even when reproducing an audio signal including a low frequency component of a frequency
equal to or lower than the lowest resonance frequency f0, and the entire height of the
electrodynamic speaker 1B is It can be made thinner than a conventional electrodynamic speaker
as about 20 mm. The electrodynamic speaker 1B of this embodiment does not include a damper
for vibratably supporting the voice coil 4B, but it is formed by impregnating a phenolic resin with
a flexible fiber fabric as a base material. It may be provided with a corrugation damper or a
butterfly damper made of metal or resin.
[0100]
Further, in the magnetic gaps 13a and 13b of the magnetic circuit 10B, the lamination thickness
of the coil laminate 4Bb is thinner and shorter than the thickness of about 4.0 mm of the top
plates 11a and 11b maintaining high magnetic flux density. Therefore, the electrodynamic
speaker 1 B becomes a short voice electrodynamic speaker, and can realize an electrodynamic
speaker with less harmonic distortion and excellent sound reproduction capability. Furthermore,
even if the coil laminate 4Bb of the voice coil 4B includes the coil pattern 45p, the
electrodynamic speaker 1B includes the coil support member 4Ba, so that the magnetic flux
density of the magnetic circuit 10B of the coil laminate 4Bb is increased. Since it can be disposed
inside the high magnetic gaps 11a and 11b, an electrodynamic speaker with high efficiency and
excellent reproduction sound quality can be obtained.
[0101]
In the voice coil 4B of this embodiment, since both the coil support member 4Ba and the coil
laminate 4Bb are formed of resin, even if it is a track type including long parallel two side
straight portions 4Bd, paper, aluminum, etc. The rigidity can be enhanced as compared with a
track-shaped voice coil constructed by winding a wire around a cylindrical bobbin made of metal
foil or the like. Therefore, even if the track-type speaker diaphragm 2B is provided, the
electrodynamic speaker 1B excellent in stable reproduction sound quality of operation can be
realized. Of course, the shape of the speaker diaphragm 2B may be rectangular, oval, elliptical, or
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elongated including a track shape, and the voice coil 4B also has a wire wound around a trackshaped voice coil bobbin. It may be a coil to be formed.
[0102]
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
[0103]
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
[0104]
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.
[0105]
It is a figure explaining the electrodynamic-type speaker 1 by preferable embodiment of this
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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
figure explaining the speaker diaphragm 2A and edge 3A by other preferable embodiment of this
invention. (Example 2) FIG. 6 is a view for explaining a speaker diaphragm 2A and an edge 3A
according to another preferred embodiment of the present invention. (Example 2) In the
electrodynamic speaker 1A according to the 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 2) This is a graph illustrating the reproduced sound pressure frequency
characteristic of the electrodynamic speaker 1A according to another preferred embodiment of
the present invention. (Embodiment 2) FIG. 6 is a view for explaining an electrodynamic speaker
1B according to another preferred embodiment of the present invention. (Embodiment 3) FIG. 6
is a perspective view for explaining a magnetic circuit 10B constituting an electrodynamic
speaker 1B according to another preferred embodiment of the present invention. (Example 3) A
voice coil 4B constituting an electrodynamic speaker 1B according to another preferred
embodiment of the present invention will be described. (Example 3) FIG. 7 is a view for
explaining a speaker diaphragm 2B and an edge 3B according to another preferred embodiment
of the present invention. (Example 3) FIG. 7 is a view for explaining a speaker diaphragm 2B and
an edge 3B according to another preferred embodiment of the present invention. (Example 3) In
the electrodynamic speaker 1B 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 3) A graph illustrating the reproduced sound pressure frequency
characteristics of the electrodynamic speaker 1B according to another preferred embodiment of
the present invention. (Example 3)
Explanation of sign
[0106]
DESCRIPTION OF SYMBOLS 1, 1A, 1B Electrodynamic type speaker 2, 2A, 2B Speaker diaphragm
21, 21A, 21B 1st diaphragm part 22, 22A, 22B 2nd diaphragm part 23, 23A, 23B Round flat
part, flat part 24, 24A, 24B Long Diameter Center Rib 25, 25A, 25B Long Diameter Both End Rib
26, 26A, 26B Short Diameter Both End Rib 27A, 27B Sub Long Length Rib 3, 3A, 3B Edge 31,
31A, 31B First Free Edge 32, 32A, 32B 1st free edge 33, 33A, 33B Fixed edge 34, 34A, 34B
Reinforcement 4, 4B Voice coil 4a Voice coil bobbin 4b Coil 4Ba Coil support member 4Bb Coil
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stack 5, 5a, 5b Damper 6, 6B Frame 7, 7B terminal 8, 8a, 8b tinsel wire 10, 10B magnetic circuit
11, 11a, 1 b top plate 12 center pole 13, 13a, 13b magnetic gap 14 under plate 15a, 15b main
magnet
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