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DESCRIPTION JP2007174604

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DESCRIPTION JP2007174604
An object of the present invention is to realize a high magnetic flux density in a magnetic gap
without generating unnecessary space in a speaker device provided with a long plate. A speaker
device (100) has a magnetic circuit (102) including a yoke (3) integrally formed with a center
pole (1) and a bottom yoke (2), an annular magnet (4), and a top plate (5). In the magnetic gap g
between the center pole 1 and the yoke 3, a voice coil 7 wound around a voice coil bobbin 6 to
which the diaphragm 10 is fixed is supported so as to vibrate in the central axis direction of the
center pole 1. In addition, a first magnet 41 of a first inner diameter r411 disposed on the
bottom yoke 2 and a second magnet of a second inner diameter r421, which is disposed on the
first magnet 41, are larger than the first inner diameter r411. A magnet 42 is disposed, and a
cylindrical bent portion 502 is formed in which the plate 5 is bent from the radial cross section
rectangular portion 501 to the space between the inner peripheral side surface 42c of the second
magnet 42 and the center pole 1 . [Selected figure] Figure 3
Speaker device
[0001]
The present invention relates to a speaker device.
[0002]
For example, in a speaker having a magnetic circuit of an external magnet type, in order to
improve vibration linearity (vibration linearity), a portion of the plate that is a component of the
magnetic circuit is disposed in the magnetic gap portion in a portion facing the magnetic gap
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portion. There is known a speaker provided with a so-called long plate which is formed wider
than the winding width of the voice coil (see, for example, Patent Document 1).
One specific example of a speaker device provided with a long plate will be described with
reference to FIG.
[0003]
This speaker device constitutes a magnetic circuit by arranging a plate 5j via a magnet 4j on a
yoke base 2j of a yoke 3j in which a center pole 1j is integrally formed. A frame 9j is attached to
the plate 5j, and a diaphragm 10j is disposed between an edge 12j connected to the frame 9j and
a cylindrical voice coil bobbin 6j. Further, a ring-shaped cancel magnet 16j is disposed below the
yoke 3j. The voice coil bobbin 6j is held by the damper 8j, and the voice coil 7j is wound. The
voice coil 7j is arranged so as to be axially vibrated in the magnetic gap G between the plate 5j
and the center pole 1j. Then, a signal current is sent to the voice coil 7j via a terminal (not
shown). As a result, the voice coil 7j is moved along the axial direction (z-axis direction) in
relation to the magnetic flux of the magnet 4j by the electromagnetic force generated by the
voice coil 7j. The movement of the voice coil 7j is propagated as the vibration of the diaphragm
10j and is output as sound to the outside.
[0004]
In the magnetic circuit, as shown in FIG. 1, the width of the portion facing the magnetic gap
portion G is larger than the thickness of the magnet bonding portion, and the thickness of the
portion is thinner than the other thicknesses. A voice coil 7j having a winding width narrower
than the width of the portion facing the magnetic gap portion G is disposed in the magnetic gap
portion G. The width of the portion opposed to the magnetic gap portion G is formed wide to
form a uniform magnetic flux density distribution over a wide range, so that, for example, even
when a large volume signal is input, the voice coil has a uniform magnetic flux density
distribution It vibrates inside and reduces distortion caused by magnetic flux density asymmetry.
[0005]
Japanese Patent Application Laid-Open No. 6-327095
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[0006]
However, in the speaker provided with the above-described plate structure, since the plate is
formed to have a relatively long width along the axial direction, an equal flux density distribution
can be formed over a wide range between the magnetic gap portions, As a result, the magnetic
flux density is reduced, and the driving force of the diaphragm 10j is reduced.
In addition, for example, if the magnet 4 j having a large magnetic force is simply adopted, there
is a problem that the cost becomes high. In addition, in the case where a plurality of magnets 4j
having the same shape are simply arranged in an overlapping manner, there is a problem that an
unnecessary space is generated between the inner peripheral portion of the magnet and the
center pole 1j.
[0007]
In a general speaker device, for example, when a signal current including a high frequency
component is input to the voice coil, an AC magnetic flux is input when a high frequency
component of the signal current, for example, a high frequency component of about 100 Hz or
more is input from the voice coil. Will occur. The AC magnetic flux is concentrated and
distributed in the vicinity of the magnetic gap portion G, in detail, on the center pole 1 j and the
plate 5 j in the vicinity of the magnetic gap portion G. In general, the material constituting the
center pole 1j and the plate 5j has nonlinearity such as a hysteresis loop (minor loop) as a
magnetic property. For this reason, the eddy current generated by the alternating magnetic flux
is affected by the minor loop, distortion occurs in the current flowing through the voice coil, and
the reproduced sound is distorted. In particular, in the speaker apparatus provided with the long
plate of the above configuration, there is a problem that distortion due to alternating magnetic
flux is relatively large.
[0008]
The present invention takes an example of the problem to address such a problem. That is, in a
speaker device provided with a long plate, achieving a high magnetic flux density in the magnetic
gap without generating unnecessary space, reducing distortion due to alternating magnetic flux,
and reducing distortion of reproduced sound. It is an object of the invention.
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[0009]
In order to achieve such an object, the present invention at least comprises the configurations
according to the following independent claims. According to the first aspect of the present
invention, there is provided a center pole standing at a substantially central portion of a speaker
device, a yoke integrally formed with a bottom yoke extending radially outward from a base end
of the center pole; And a magnetic circuit including an annular magnet coaxially formed on the
bottom yoke and an annular plate disposed on the magnet, in a magnetic gap between the center
pole and the yoke, A speaker device in which a voice coil wound around a voice coil bobbin to
which a diaphragm is fixed is vibratably supported in the center axis direction of the center pole,
and the magnet is disposed on the bottom yoke A first annular magnet of a first inner diameter,
and a second annular magnet of a second inner diameter larger than the first inner diameter,
disposed on the first annular magnet; The plate is formed of a radial cross-sectional rectangular
portion provided with a surface facing the second annular magnet, between the inner peripheral
side surface of the second annular magnet and the center pole, An inner circumferential side
surface and a cylindrical bent portion bent at a prescribed interval are formed, and a portion of
the bent portion of the plate facing the magnetic gap is along the central axis direction from the
winding width of the voice coil. It is formed to be long, and the tip of the bent portion is disposed
at a predetermined interval on the plate side from the vicinity of the corner on the plate side in
the inner peripheral edge portion of the first annular magnet. It is characterized by
[0010]
According to the second aspect of the present invention, there is provided a center pole standing
substantially at a central portion of a speaker device, a yoke integrally formed with a bottom
yoke extending radially outward from a base end of the center pole; And a magnetic circuit
including an annular magnet coaxially formed on the bottom yoke and an annular plate disposed
on the magnet, in a magnetic gap between the center pole and the yoke, A speaker device in
which a voice coil wound around a voice coil bobbin to which a diaphragm is fixed is vibratably
supported in the center axis direction of the center pole, the plate has a surface facing the
magnet The cylindrical shape is bent from the radially cross-sectional rectangular portion toward
the inner circumferential side surface of the magnet and the center pole at a prescribed interval
from the inner circumferential side surface of the magnet A bent portion is formed, and a portion
of the bent portion of the plate facing the magnetic gap is formed along the central axis direction
longer than a winding width of the voice coil, and is opposed to the magnetic gap of the bent
portion. A short ring made of a nonmagnetic material is formed on one or both of the portion and
the outer peripheral side surface of the center pole.
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[0011]
According to an embodiment of the present invention, there is provided a speaker device
comprising: a center pole standing substantially at the center of the speaker device; and a yoke
integrally formed with a bottom yoke extending radially outward from a base end of the center
pole. It has a magnetic circuit including an annular magnet formed on the bottom yoke coaxially
with the center pole and an annular plate disposed on the magnet.
In the magnetic gap between the center pole and the yoke, a voice coil wound around a voice coil
bobbin to which a diaphragm is fixed is vibratably supported in the central axis direction of the
center pole. The magnet includes a first annular magnet of a first inner diameter disposed on a
bottom yoke, and a second inner diameter of a second inner diameter disposed on the first
annular magnet and greater than the first inner diameter. And an annular magnet. In addition,
the above-mentioned plate is directed to the space between the inner circumferential side surface
of the second annular magnet and the center pole from the radial cross-sectional rectangular
portion provided with the surface facing the second annular magnet, and the inner periphery of
the second annular magnet A cylindrical bent portion which is bent at a specified distance from
the side surface is formed. Further, a portion of the bent portion of the plate facing the magnetic
gap is formed longer along the central axis direction than the winding width of the voice coil (socalled long plate structure). Further, the tip end portion of the bending portion is disposed so as
to be spaced apart on the plate side from the vicinity of the corner portion on the plate side in
the inner peripheral edge portion of the first annular magnet, at a prescribed interval. In the
speaker device of the above-described configuration, the first and second annular magnets
having different inner diameters are disposed on the bottom yoke, and the second cross section
from the radial direction section having the surface in which the plate faces the second annular
magnet A cylindrical bent portion is formed between the inner circumferential side surface of the
annular magnet and the center pole and spaced apart from the inner circumferential side surface
of the second annular magnet at a prescribed interval, and the tip of the bent portion is In the
inner peripheral edge portion of the annular magnet 1, since the plate side is disposed at a
prescribed interval on the plate side from the vicinity of the corner portion on the plate side,
there is no waste space in the magnetic circuit Space efficiency can be improved. Also, even when
a so-called long plate is adopted, high magnetic flux density can be realized in the magnetic gap
of the magnetic circuit.
[0012]
Further, in the speaker device according to another embodiment of the present invention, a
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center pole standing at a substantially central portion of the speaker device and a bottom yoke
extending radially outward from a base end portion of the center pole are integrally formed. A
magnetic circuit including a yoke, an annular magnet formed on the bottom yoke coaxially with
the center pole, and an annular plate disposed on the magnet. In the magnetic gap between the
center pole and the yoke, a voice coil wound around a voice coil bobbin to which a diaphragm is
fixed is vibratably supported in the central axis direction of the center pole. The above-mentioned
plate has a cylindrical shape which is bent from the radial cross-sectional rectangular part having
the surface facing the magnet to the inner peripheral side surface of the magnet and the center
pole with a predetermined distance from the inner peripheral side surface of the magnet The part
is formed. Further, a portion of the bent portion of the plate facing the magnetic gap is formed
longer along the central axis direction than the winding width of the voice coil. Under the present
circumstances, the short ring which consists of nonmagnetic materials is formed in the part
which opposes a magnetic gap among the bending parts, and one or both of the outer peripheral
side part of a center pole. In the speaker device of the above configuration, a short ring made of a
nonmagnetic material is formed on one or both of the portion facing the magnetic gap in the
bent portion and the outer peripheral side surface portion of the center pole, so a so-called long
plate is adopted. Even in this case, the short ring can reduce distortion due to alternating
magnetic flux, and can reduce distortion of reproduced sound. Hereinafter, a speaker device
according to an embodiment of the present invention will be described with reference to the
drawings.
[0013]
First Embodiment FIG. 2 is a cross-sectional view for explaining a speaker device according to a
first embodiment of the present invention. FIG. 3 is an enlarged view around the center pole of
the speaker device shown in FIG. As shown in FIGS. 2 and 3, in the speaker device 100 according
to the present embodiment, the center pole 1 erected substantially at the center of the speaker
device 100 and the proximal end 1 A of the center pole 1 radially outward The yoke 3 is
integrally formed with an expanding bottom yoke 2, an annular magnet 4 which is a permanent
magnet coaxially formed around the center pole 1, and coaxially formed around the center pole
1. And a top plate 5 constituting an outer diameter side magnetic flux applying unit disposed in
the The yoke 3, the magnet 4 and the center pole 1 form a magnetic circuit 102 that generates a
magnetic flux 101. Only the left side portion of the magnetic flux 101 is shown in FIG. Further, a
portion of the center pole 1 facing the top plate 5 corresponds to an inner diameter side
magnetic flux application portion. The magnetic circuit 102 forms a magnetic gap g between the
outer peripheral surface 1 a of the center pole 1 and the inner peripheral surface 5 c of the top
plate 5. The top plate 5 according to the present embodiment has a first piece 51 and a second
piece 52. Moreover, the magnet 4 which concerns on this embodiment has the 1st magnet 41
and the 2nd magnet 42. As shown in FIG. Details of each component will be described later. Here,
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the magnet 4 corresponds to an embodiment of the magnet according to the present invention.
The top plate 5 corresponds to an embodiment of the plate according to the present invention.
[0014]
Further, as shown in FIGS. 2 and 3, in the speaker device 100, the voice coil 7 wound around the
voice coil bobbin 6 is disposed in the magnetic gap g. The voice coil bobbin 6 is supported by the
frame 9 so as to be capable of vibrating along the axial direction (the central axis direction (z-axis
direction) of the center pole 1) by a damper member 8 such as a spider, for example. In the
vicinity of the upper end portion of the voice coil bobbin 6, the central portion of the diaphragm
10 is fixed. The outer peripheral edge portion of the diaphragm 10 is connected to the inner
peripheral portion of the frame 9 via the edge 12. In addition, on the side of the diaphragm 10 of
the top plate 5, a heat dissipation member 11 for fixing the top plate 5 and dissipating the heat
of the top plate 5 is disposed.
[0015]
The yoke 3 is disposed at the center of the speaker device 100. The yoke 3 according to the
present embodiment is formed of, for example, a magnetic body such as iron. Further, as
described above, the yoke 3 extends radially outward from the cylindrical center pole 1 standing
at the center of the speaker device 100 and the base end of the center pole 1 opposite to the
diaphragm 10 side. A bottom yoke 2 which is a radially extending portion is integrally formed. A
flat portion 2 a for mounting the magnet 4 is formed on the side surface of the diaphragm of the
outer peripheral portion of the bottom yoke 2. An annular magnet 4 having a rectangular cross
section in the radial direction is mounted on the flat portion 2 a in a concentric axial shape with
the center pole 1. A top plate 5 is also mounted coaxially with the center pole 1 on the
diaphragm side of the magnet 4.
[0016]
The magnet 4 according to the present embodiment has the first magnet 41 and the second
magnet 42 as described above. The first magnet 41 and the second magnet 42 are disposed so as
to overlap so that the directions of the magnetic moments become equal. The first magnet 41
corresponds to an embodiment of a first annular magnet according to the present invention, and
the second magnet 42 corresponds to an embodiment of a second annular magnet according to
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the present invention. The inner diameter r411 of the first magnet 41 is larger than the inner
diameter r421 of the second magnet 42. Further, in the present embodiment, the outer diameter
412 of the first magnet 41 and the outer diameter 413 of the second magnet 42 are set to have
substantially the same length. That is, from the distance r1 between the outer peripheral surface
1a of the center pole 1 and the inner peripheral surface 41c of the first magnet 41, the distance
between the outer peripheral surface 1a of the center pole 1 and the inner peripheral side
surface 42c of the second magnet 42 is The distance r2 is long. Further, the length L41 along the
axial direction (z-axis direction in the drawing) of the first magnet 41 according to the present
embodiment is substantially the same length as the length L42 along the axial direction of the
second magnet 42. It is set.
[0017]
The top plate 5 is made of, for example, a magnetic material such as iron. The top plate 5 is a
second magnet directed from the radial cross section rectangular portion 501 provided with the
surface 51 A facing the second magnet 42 to the space between the inner peripheral side surface
42 c of the second magnet 42 and the center pole 1. A cylindrical bent portion 502 which is bent
at a predetermined interval g42 and the inner circumferential side surface 42c of 42 is formed. A
portion (inner circumferential surface 5c) of the bent portion 502 of the top plate 5 facing the
magnetic gap g is formed to have a width L1 longer than the winding width w7 of the voice coil 7
along the central axis c direction. The width L 1 is set to be substantially the same as or larger
than the vibration range of the voice coil bobbin 6. The tip end portion 521 of the bent portion
502 is disposed on the plate side at a specified interval g45 from the vicinity of the corner
portion 41e on the plate side of the inner peripheral edge portion 41d of the first magnet 41.
[0018]
FIG. 4 is a view for explaining the top plate of the speaker device 100 shown in FIGS. 2 and 3.
FIG. 4 (a) is an exploded perspective view of the plate, and FIG. It is a perspective view for doing.
In the present embodiment, the top plate 5 has a first piece 51 and a second piece 52 as shown
in FIGS. 2 to 4 (a) and (b), and by combining them, The top plate 5 of the above shape is formed.
Each component will be described below.
[0019]
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The first piece 51 has a large diameter through hole 51B at the center and is formed in a thin
plate ring shape. Further, the first piece 51 is formed with a surface 51 </ b> A that faces the
second magnet 42. Further, the first piece 51 is a disk which is formed in a slender rectangular
shape in a radial direction in cross section and which extends in the radial direction while
maintaining a uniform thickness L2 in the axial direction. In detail, the first piece 51 has a crosssectional shape in which the radial dimension W2 is larger than the axial dimension L2 in the
radial cross-sectional shape. The second piece 52 has an axially extending cylindrical portion
522 and an engaging portion 523. Specifically, the cylindrical portion 522 has a large-diameter
thin-walled cylindrical shape, is an elongated rectangular cross-sectional shape in the radial
direction, and is a cylinder extending in the axial direction while maintaining a uniform thickness
W1 in the radial direction. As shown in FIG. 3, the second piece 52 has a magnetic gap facing
surface 5f facing the magnetic gap g in the inner circumferential surface 5c, and in the radial
direction cross sectional shape, the axial direction of the magnetic gap facing surface 5f The
dimension L1 has a cross-sectional shape larger than the radial dimension W1. The engaging
portion 523 is bent toward the first piece 51 from the side surface (peripheral surface) of the
cylindrical portion 522, and is formed so as to project over the entire circumference, as shown in
FIGS. 4 (a) and 4 (b). As such, it engages with the first piece 51 at the time of assembly. A corner
51D, which is a right-angled cross section on the inner peripheral portion diaphragm 10 side
formed by the inner peripheral surface of the through hole 51B of the first piece 51 and the
diaphragm side large area surface 51C, corresponds to the engagement of the second piece 52.
An engagement portion on the first piece 51 side engaged with the joint portion 523 is
configured. As shown in FIG. 4 (b), the two engaging portions are engaged with each other and
positioned relative to each other. In the corner portion 51D, the first piece 51 brings the side
open side surface of the inner peripheral portion into close contact (closely in the axial direction)
with the back surface of the engaging portion 523 of the second piece 52. The outer
circumferential surface of the piece 52 is in close contact (in the radial direction). Here, a first
length L3 of the second piece 52 extending to the axial diaphragm side with respect to the first
piece 51 is a second length L4 extending to the opposite side of the diaphragm 10 It is set
shorter than.
[0020]
As shown in FIGS. 2 to 4, in the first piece 51 and the second piece 52 of the present
embodiment, the side open side surface of the inner peripheral portion is in close contact with
the back surface of the engaging portion 523 of the first piece 51. The inner peripheral surface is
in close contact with the outer peripheral surface of the second piece 52 (in the radial direction)
(generally, the two cylindrical members are in close contact in the radial direction. difficult. The
first piece 51 and the second piece 52 may not necessarily be in close contact with each other in
the radial direction. It suffices to be magnetically bonded. It is preferable that the joining surfaces
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of the first piece 51 and the second piece 52 be joined with a magnetically sufficiently large
surface so as not to narrow the magnetic path. For this reason, as in the present embodiment,
when the contact surfaces of both the axial contact surface and the radial contact surface are
joined in a close contact state, or when a slight gap is generated between the two, this gap Is
preferably embedded in a magnetic material or the like. Here, “magnetically bonding”
corresponds to a state in which one member is connected to be able to transmit a magnetic flux
to another member, and is directly connected, for example, through a layer of magnetic adhesive.
Also includes non-contacting states.
[0021]
The first piece 51 and the second piece 52 are adhered by an adhesive (not shown) applied
between the outer peripheral surface of the first piece 51 and the inner peripheral surface of the
second piece 51 . The first piece 51 placed directly on the magnet 4 is bonded to the magnet 4
with an adhesive, for example. On the side of the top plate 5 further to the diaphragm 10, a heat
dissipation member 11 having good thermal conductivity and made of a nonmagnetic material
such as aluminum is disposed. The heat dissipating member 11 is preferably a nonmagnetic
material so as not to disturb the magnetic circuit.
[0022]
The heat dissipation member 11 is formed such that a part of the inner side of the frame 9
extends to the open end face of the second piece 5b, and the end face contact portion 11a
formed at the tip contacts the open end face of the second piece 5b. doing. A through hole is
bored in the surface contact portion 11 a in the axial direction, and a screw hole is screwed in the
second piece 52 at a corresponding position, and the heat dissipation member 11 is inserted into
the screw hole The bolt 14 is fastened and fixed to the second piece 52. The heat radiating
member 11 is a heat radiating means for radiating the heat of the top plate 5 and is a fixing
means for fixing the top plate 5 on the magnet 4.
[0023]
Between the outer peripheral surface 1a of the center pole 1 and the inner peripheral surface 5c
of the top plate 5, a magnetic gap g formed at a predetermined distance in the radial direction is
formed over the entire circumference. The magnetic gap g is formed over the outer peripheral
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surface of the center pole 1. The magnetic gap g is formed to extend in the axial direction along
the outer peripheral surface of the center pole 1. That is, the magnetic gap g is formed in a
cylindrical shape. In the magnetic gap g, the voice coil 7 is wound around an outer peripheral
surface of a position corresponding to the magnetic gap g of the thin-walled long cylindrical
voice coil bobbin 6. The voice coil bobbin 6 is supported from the frame 9 by a spider 8 which is
a damper member. Thus, the voice coil 7 can vibrate in the axial direction of the center pole 1 in
the magnetic gap g. The other end of the voice coil bobbin 6 is connected to a small diameter end
of a so-called cone-shaped diaphragm 10. The frame 9 has a tapered cylindrical shape, and screw
holes through which bolts pass at equal intervals in the circumferential direction are screwed at
the bottom side edge. A fixing plate for supporting the yoke 3 from the back surface is fixed to
the frame 9 by bolts. Further, as shown in FIG. 2, on the center pole 1, a center piece 15 having
substantially the same diameter as that of the center pole 1 is fixed by bolts 16 inside the voice
coil bobbin 6.
[0024]
In the speaker device 100 configured as described above, when a signal current is input to the
voice coil 7 via a terminal (not shown), the voice coil bobbin 6 is generated in relation to the
magnetic flux of the magnet 4 by the electromagnetic force generated by the voice coil 7. Is
moved along the axial direction (z-axis direction). The movement of the voice coil bobbin 6 is
propagated as the vibration of the diaphragm 10 and output as sound to the outside. At this time,
the speaker device 100 includes the top plate 5 (so-called long plate) in which the inner
circumferential surface 5c of the second piece 52 is formed larger than the winding width W7 of
the voice coil 7. An equal flux density distribution can be formed over the. In addition, since the
first magnet 41 and the second magnet 42 are provided, the magnetic force can be made
stronger than that of the conventional single annular magnet, and the reduction of the magnetic
flux density when the long plate is adopted can be prevented. Can.
[0025]
Further, the speaker device 100 has a first magnet 41 of a first inner diameter r411 disposed on
the bottom yoke 2 and a second magnet disposed on the first magnet 41 that is larger than the
first inner diameter r411. The second magnet 42 of the inner diameter r421 of the second
magnet 42 is disposed, and the radial cross section rectangular portion 501 provided with the
surface 51A in which the plate 5 faces the second magnet 42 and the inner circumferential side
surface 42c of the second magnet 42 A cylindrical bent portion 502 bent at a prescribed interval
g42 from the inner circumferential side surface 42c of the second magnet 42 is formed toward
the center pole 1 and the tip portion 521 of the bent portion 502 is a first The magnetic circuit is
arranged so as to be spaced apart from the corner 41e on the plate side of the inner peripheral
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edge 41d of the magnet 41 by the specified gap g45, so that even when a long plate is adopted,
the magnetic circuit Waste inside Without space occurs, it is possible to improve the space
efficiency of the magnetic circuit.
[0026]
Second Embodiment FIG. 5 is a cross-sectional view for explaining a speaker device 100a
according to a second embodiment of the present invention.
The description of the same configuration, operations and effects as those of the first
embodiment will be omitted. In a general speaker device, for example, when a signal current
including a high frequency component is input to the voice coil 7, AC magnetic flux is input when
a high frequency component of the signal current, for example, a high frequency component of
about 100 Hz or more is input from the voice coil 7. It occurs. The AC magnetic flux is
concentrated and distributed on the center pole 1 and the top plate 5 in the vicinity of the
magnetic gap portion G, specifically, in the vicinity of the magnetic gap portion G. Generally, the
material constituting the center pole 1 and the top plate 5 has non-linearity such as a hysteresis
loop (minor loop) as a magnetic property. For this reason, the eddy current generated by the
alternating magnetic flux is affected by the minor loop, distortion occurs in the current flowing
through the voice coil, and the reproduced sound is distorted. In particular, in the speaker
provided with the long plate of the above configuration, the distortion due to the AC magnetic
flux is relatively large.
[0027]
For this reason, as shown in FIG. 5, in the speaker device 100a according to the present
embodiment, a portion (inner peripheral surface 5c) of the bent portion 502 of the top plate 5
facing the magnetic gap g and the outer peripheral surface portion 1a of the center pole 1 A
short ring made of a nonmagnetic material and a conductor is formed on one or both of them. In
the present embodiment, by providing a short ring made of a nonmagnetic material in both of
them, distortion due to AC magnetic flux is reduced.
[0028]
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In detail, as shown in FIG. 5, the speaker device 100a is made of various nonmagnetic materials
such as aluminum or copper in a portion (inner peripheral surface 5c) of the bent portion 502 of
the top plate 5 facing the magnetic gap g. And a cap (short ring) 18 made of nonmagnetic
material on both outer peripheral surface portions 1 a of the center pole 1. Each component will
be described below with reference to the drawings.
[0029]
The short ring 17 has a cylindrical portion 171 and a bent portion 172, as shown in FIG. The
cylindrical portion 171 is formed in a cylindrical shape, and is formed along a portion (inner
circumferential surface 5 c) of the bending portion 502 facing the magnetic gap g. A lower end
portion 171 a of the cylindrical portion 171 is formed to be positioned at a substantially distal
end portion 521 of the bending portion 502. The bent portion 172 is bent outward in the radial
direction from the upper end portion 171 b of the short ring 17. That is, the short ring 17 has an
L-shaped cross section. The short ring 17 is electrically connected to the top plate 5.
[0030]
The cap 18 has a tubular portion 181 and a bending portion 182, as shown in FIG. The
cylindrical portion 181 is formed in a cylindrical shape, and is disposed along the outer
peripheral surface portion 1 a of the center pole 1, and the lower end portion 181 a is positioned
near the position facing the tip portion 521 of the top plate 5. The bent portion 182 is bent from
the upper end portion 181 a toward the central axis. That is, the cap 18 has an inverted L-shape
in cross section. Also, the cap 18 is electrically connected to the center pole 1.
[0031]
The short ring 17 and the cap 18 function as a secondary winding of the voice coil 7 and are
disposed on the top plate 5 and the center pole 1 to reduce the inductance of the voice coil 7, for
example, the second order Reduce third-order harmonic distortion such as third order. In detail,
even when the magnetic material constituting the center pole 1 and the top plate 5 has nonlinearity of the magnetic characteristics, the amount of change in inductance is small, and
distortion can be reduced.
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[0032]
As described above, in the speaker device 100a according to the present embodiment, one or
both of the portion (inner peripheral surface 5c) of the bent portion 502 of the top plate 5 facing
the magnetic gap g and the outer peripheral surface 1a of the center pole 1 In addition, since the
short ring made of a nonmagnetic material and a conductor is included, distortion of the current
flowing through the voice coil can be reduced, and distortion of the reproduced sound can be
reduced. Further, the speaker device 100a adopts a long plate and also adopts a copper short
ring 17 and a copper cap 18. Furthermore, as in the first embodiment, since the first magnet 41
and the second magnet 42 of two-tiered stacks having different inner diameters are employed,
maximum magnet capacity can be obtained within limited dimensional constraints. And a
sufficient magnetic flux density Bg can be secured in the magnetic gap g.
[0033]
[Comparison of Amplitude Amounts of Vibration System Portions of Speaker] The inventor of the
present invention has compared a conventional speaker device to be compared with the speaker
device 100a according to the present invention in order to confirm the performance of the
speaker according to the embodiment of the present invention. The amplitude amount frequency
characteristic of the diaphragm of was measured and compared. In the conventional speaker to
be compared, for example, the thickness of the plate is smaller than the number of turns of the
voice coil, and with respect to the magnetic flux distribution, the winding width of the voice coil
is not centered and the magnetic flux distribution is outside along the axial direction of the plate
In the upper and lower asymmetry.
[0034]
FIG. 6 is a diagram for explaining frequency characteristics of amplitude amounts of the speaker
device according to an embodiment of the present invention and the conventional speaker device
to be compared. Fig.6 (a) is a figure which shows the amplitude amount from the reference
(standard) position of the diaphragm of the speaker apparatus based on 2nd Embodiment of this
invention. FIG. 6B is a diagram showing the amount of amplitude from the reference position of
the diaphragm of the conventional speaker device to be compared. The horizontal axis shows the
frequency, the vertical axis shows the amplitude amount, the solid line shows the amplitude
amount (upper amplitude amount) from the reference position (specified position) to the upper
side (front side), and the broken line shows the reference position (specified position) The
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amplitude amount (lower amplitude amount) from the lower side (back side) is shown.
[0035]
In the conventional speaker device, for example, as shown in FIG. 6B, the upper amplitude
amount is a substantially constant amplitude amount from a frequency of 20 Hz to 50 Hz, and
rapidly decreases from a frequency of 50 Hz to 400 Hz. The lower amplitude amount is a
substantially constant amplitude amount from frequency 20 Hz to 50 Hz, smaller than the
amount of upper amplitude, and rapidly decreases from frequency 50 Hz to 400 Hz. On the other
hand, in the speaker device according to the embodiment of the present invention, as shown in
FIG. 6A, the difference between the upper amplitude amount and the lower amplitude amount is
smaller than that of the conventional speaker device.
[0036]
As described above, in the speaker device 100a according to the present invention, the upper
amplitude amount and the lower amplitude amount are substantially equal to each other as
compared to the conventional speaker having a relatively large difference between the upper
amplitude amount and the lower amplitude amount. It can be confirmed that it vibrates
approximately symmetrically from). That is, it was possible to confirm that the distortion was
reduced in the speaker device 100a according to the present invention compared to the
conventional speaker.
[0037]
[Comparison of Various Frequency Characteristics of Loudspeaker] The inventor of the present
application measured frequency characteristics of various performances in order to confirm the
performance of the loudspeaker according to the second embodiment of the present invention.
For comparison, various frequencies were measured and compared for the speaker device 100a
according to the second embodiment and the speaker device 100 not provided with the copper
cap and the copper short ring according to the first embodiment for comparison.
[0038]
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FIG. 7 shows acoustic frequency characteristics of the speaker device. FIG. 7 (a) shows the
acoustic frequency characteristics of the conventional speaker device, and FIG. 7 (b) shows the
frequency characteristics of the speaker device according to the present invention. The solid line
indicates the sound pressure frequency characteristic, the broken line indicates the frequency
characteristic of second harmonic distortion, the alternate long and short dashed line indicates
the frequency characteristic of third harmonic distortion, and the alternate long and two short
dashed line indicates an impedance curve. Show. In FIGS. 7A and 7B, distortion amounts (second
harmonic distortion and third harmonic distortion) are illustrated with a 30 dB increase. For
example, as specifically shown in FIG. 7A, the second harmonic distortion at a frequency of 50 Hz
is actually 69 dB.
[0039]
As shown in FIGS. 7A and 7B, in the speaker device 100a, the sound pressure level p1 indicated
by the solid line is larger than the sound pressure level p1b of the speaker device 100 in the
vicinity of a frequency of 2000 to 5000 Hz. Further, in the speaker device 100a, the second
harmonic distortion p2 indicated by the broken line has a peak near a frequency of 170 Hz
significantly reduced compared to the second harmonic distortion p2b of the speaker device 100.
In the third harmonic distortion p3 indicated by the alternate long and short dash line in the
speaker device 100a, the distortion level near a frequency of 100 to 2000 Hz is significantly
reduced as compared with the third harmonic distortion p3b of the speaker device 100. Further,
in the speaker device 100 a, the impedance p 4 indicated by the two-dot chain line has a level
near the frequency of 500 Hz to 40 kHz significantly reduced compared to the impedance p 4 b
of the speaker device 100. As described above, in the speaker device 100 a according to the
second embodiment, since the short ring 17 and the cap 18 are provided, the second harmonic
distortion and the third harmonic distortion are the same as those of the speaker device 100
according to the first embodiment. It could be confirmed that it was reduced compared to that of
[0040]
The present invention is not limited to the embodiment described above. For example, the
embodiments according to the present invention described above may be combined. Further, in
the embodiment described above, the top plate 5 adopts the form in which the first piece 51 and
the second piece 52 are combined, but the present invention is not limited to this form. For
example, as shown in FIG. 8, the speaker device 100b may adopt the top plate 5b in which the
first piece 51 and the second piece 52 are integrally formed. In the embodiment described above,
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the second piece 52 of the top plate 5 includes the cylindrical portion 522 and the engaging
portion 523. However, the present invention is not limited to this. For example, the engaging
portion 523 may not be provided only at the cylindrical portion 522. In the embodiment
described above, the magnetic circuit provided with the magnet 4, the yoke 3 and the top plate 5
in which the two magnets 41 and 42 having different inner diameters are overlapped is adopted.
In this case, the first magnet 41 is used. A magnetically closed circuit is formed from the inner
peripheral portion of the top plate 5 to the top plate 5 and the magnet 4 via the tip of the second
piece 54 of the top plate 5 close to the inner peripheral portion thereof to form a center pole.
Since the magnitude of the magnetic flux between 1 and the top plate 5 may decrease, the
positional relationship, the shape, etc. of the magnets 41, 42, top plate 5, center pole 1, etc. are
optimally set in consideration of this point. Thus, the magnetic flux between the center pole 1
and the top plate 5 can be made larger.
[0041]
As described above, in the speaker device 100, the center pole 1 erected substantially at the
center of the speaker device 100 and the bottom yoke 2 extending radially outward from the
base end of the center pole 1 are integrally formed. The magnetic circuit 102 includes a yoke 3,
an annular magnet 4 formed on the bottom yoke 2 coaxially with the center pole 1, and an
annular top plate 5 disposed on the magnet 4. In the magnetic gap g between the center pole 1
and the yoke 3, a voice coil 7 wound around a voice coil bobbin 6 to which the diaphragm 10 is
fixed is supported so as to vibrate in the central axis direction of the center pole 1. Further, the
speaker device 100 has a first magnet 41 of a first inner diameter r411 disposed on the bottom
yoke 2 and a second magnet disposed on the first magnet 41 that is larger than the first inner
diameter r411. The second magnet 42 of the inner diameter r421 of the second magnet 42 is
disposed, and the radial cross section rectangular portion 501 provided with the surface 51A in
which the plate 5 faces the second magnet 42 and the inner circumferential side surface 42c of
the second magnet 42 A cylindrical bent portion 502 bent at a prescribed interval g42 from the
inner circumferential side surface 42c of the second magnet 42 is formed toward the center pole
1 and the tip portion 521 of the bent portion 502 is a first The magnetic circuit is arranged so as
to be spaced apart from the corner 41e on the plate side of the inner peripheral edge 41d of the
magnet 41 by the specified gap g45, so that even when a long plate is adopted, the magnetic
circuit Waste inside Without space occurs, it is possible to improve the space efficiency of the
magnetic circuit. Also, even when a so-called long plate is adopted, high magnetic flux density
can be realized in the magnetic gap of the magnetic circuit.
[0042]
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The speaker device 100 a is a nonmagnetic material and conductor in one or both of the portion
(inner peripheral surface 5 c) of the bent portion 502 of the top plate 5 facing the magnetic gap
g and the outer peripheral surface portion 1 a of the center pole 1. As a result, the distortion of
the current flowing through the voice coil can be reduced, and the distortion of the reproduced
sound can be reduced. Further, the speaker device 100a adopts a long plate, and also adopts a
copper short ring 17 and a copper cap 18. Furthermore, as in the first embodiment, since the
first magnet 41 and the second magnet 42 of two-tiered stacks having different inner diameters
are employed, maximum magnet capacity can be obtained within limited dimensional constraints.
And a sufficient magnetic flux density Bg can be secured in the magnetic gap g.
[0043]
It is a half section view for explaining one example of a speaker apparatus provided with the
conventional long plate. It is a sectional view for explaining a speaker device concerning a 1st
embodiment of the present invention. It is an enlarged view of center pole vicinity of the speaker
apparatus shown in FIG. It is a figure for demonstrating the top plate of the speaker apparatus
100 shown to FIG.2, 3, (a) is a disassembled perspective view of a plate, (b) is a perspective view
for demonstrating the plate after an assembly. It is sectional drawing for demonstrating the
speaker apparatus 100a which concerns on 2nd Embodiment of this invention. It is a figure for
demonstrating the frequency characteristic of the amplitude amount of the speaker apparatus
which concerns on one Embodiment of this invention, and the conventional speaker apparatus of
comparison object. (A) is a figure which shows the amount of amplitudes from the reference
(standard) position of the diaphragm of the speaker apparatus concerning a 2nd embodiment of
the present invention. (B) is a figure which shows the amount of amplitudes from the reference
(standard) position of the diaphragm of the conventional speaker apparatus of comparison
object. The acoustic frequency characteristic of a speaker apparatus is shown. (A) shows the
acoustic frequency characteristic of the conventional speaker apparatus, (b) shows the frequency
characteristic of the speaker apparatus based on this invention. It is sectional drawing for
demonstrating the speaker apparatus 100b which concerns on other embodiment of this
invention.
Explanation of sign
[0044]
DESCRIPTION OF SYMBOLS 1 center pole 2 bottom yoke 3 yoke 4 magnet 5 top plate 6 voice
coil bobbin 7 voice coil 8 damper member 9 frame 10 diaphragm 11 heat dissipation member 12
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edge 41 1st magnet (1st annular magnet) 42 2nd magnet Second annular magnet) 51 First piece
51 Second piece 100, 100a, 100b Speaker device 101 Magnetic flux 102 Magnetic circuit 171
Tube-shaped portion 172 Bending portion 181 Tube-shaped portion 182 Bending portion 501
Radial direction rectangular section 502 Bending part 521 Tip part 522 Cylindrical part 523
engaging part
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