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DESCRIPTION JPH11196491

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DESCRIPTION JPH11196491
[0001]
The present invention relates to a voice coil directly connected to a diaphragm, an annular
magnet magnetized in a radial direction, and a magnetically conductive portion (plate, for guiding
direct current magnetic flux generated from the magnet to the voice coil). A speaker magnetic
circuit comprising: a center pole, a soft magnetic member such as a yoke), and driving an
oscillating plate using Lorentz force generated when current flows through a voice coil in a direct
current magnetic field; It is about
[0002]
2. Description of the Related Art FIG. 30 shows a conventional speaker magnetic circuit using a
magnet magnetized in the radial direction. The magnetically conductive portion is composed of a
center pole 101 provided at the center of the circuit and a yoke 102 provided outside the center
pole. The annular magnet 103 magnetized in the radial direction is fitted to the upper outer
surface of the center pole 101, and the magnetic pole 106 is formed on the outer surface of the
ring magnet 103 and the upper inner surface of the yoke 102. The voice coil 105 is installed.
The diaphragm 108 is connected to the voice coil 105 via the bobbin 107, and these are
supported by the damper 109 (not shown in FIG. 30).
[0003]
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Further, FIG. 31 shows another example of a conventional speaker magnetic circuit using a
magnet magnetized in the radial direction, which is described in, for example, Japanese Patent
Application Laid-Open No. 64-49500. The magnetically conductive portion is composed of a
center pole 101 provided at the center of the circuit and a yoke 102 provided around the center
pole. A radially magnetized annular magnet 103 is fitted to the upper inner surface of the yoke 2,
and the magnetic pole 106 is formed on the inner surface of the annular magnet 103 and the
upper outer surface of the center pole 101, and the air gap between both surfaces is formed. The
voice coil 105 is installed. The diaphragm 108 is connected to the voice coil 105 via the bobbin
106.
[0004]
32 and 33 show still another example of a conventional speaker magnetic circuit using a magnet
magnetized in the radial direction.
[0005]
SUMMARY OF THE INVENTION A conventional speaker magnetic circuit using an annular
magnet magnetized in the radial direction as a main magnet is generally configured as described
above, and in either case, the magnet is in the magnetic pole part. It was installed.
For this reason, the magnet is directly affected by the AC magnetic field generated by the voice
coil, and the DC magnetic flux density inside the magnet fluctuates greatly, causing a problem
that the drive distortion of the voice coil becomes large.
[0006]
In addition, a high output type speaker is required to have a high air-gap magnetic flux density of
the magnetic pole portion. However, conventionally, since the inner side surface or the outer side
surface of the radially magnetized annular magnet is a pole face, the shape and size of the
magnet are restricted by the specifications of the pole portion. For this reason, there is a limit to
the magnet volume that can be secured, and there is a problem that the air gap magnetic flux
density can not be easily increased.
[0007]
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The present invention has been made to solve the above problems, and in a magnetic circuit
using a magnet magnetized in the radial direction as a main magnet, driving distortion is reduced
by providing the magnet at a location other than the magnetic pole part. The purpose is to
further increase the air gap magnetic flux density.
[0008]
The speaker magnetic circuit according to claim 1 of the present invention is magnetized in the
radial direction, and is in contact with the annular magnet provided in contact with the outer
periphery of the center pole and the outer periphery of the annular magnet. A magnetic pole is
formed on a part of the inner side surface of the yoke and a part of the outer side surface of the
center pole, and a voice coil is inserted between the two magnetic poles. .
[0009]
In the speaker magnetic circuit according to a second aspect of the present invention, in the first
aspect, the height of the annular magnet is greater than any of the height of the center pole outer
peripheral magnetic pole surface and the height of the yoke inner peripheral magnetic pole
surface. It is specified.
[0010]
A speaker magnetic circuit according to a third aspect of the present invention is the speaker
magnetic circuit according to the first or second aspect, including the magnetic shielding cover
which is disposed apart from the yoke and the annular magnet and is formed of a member
including at least a soft magnetic member. is there.
[0011]
According to a fourth aspect of the present invention, in the speaker magnetic circuit according
to the first or second aspect, the magnetic shield comprises a member including at least a soft
magnetic member spaced apart from the center pole and the annular magnet and in contact with
the yoke. It is equipped with a cover.
[0012]
The speaker magnetic circuit according to claim 5 of the present invention is the speaker
magnetic circuit according to claim 3 or 4, wherein the magnetic repulsion with the annular
magnet is between the magnetic shielding cover and the center pole or between the magnetic
shielding cover and the yoke and at a position where a closed magnetic circuit is not formed. It
further comprises a second magnet in the direction in which the force acts.
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[0013]
DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment
An embodiment of the present invention will be described below based on the drawings.
FIG. 1 is a longitudinal sectional view showing a configuration of a speaker magnetic circuit
according to an embodiment of the present invention.
In the figure, it is in close contact with the lower outer surface of center pole 1 (upper outer
diameter: 30 mm, upper step height: 8 mm, lower outer diameter: 32 mm, lower step height: 8
mm, overall height: 32 mm) An annular magnet 3 (outside diameter: 48 mm, inside diameter: 32
mm, height: 8 mm) magnetized in the direction is installed, and yoke 2 (outside diameter: 54 mm,
upper inside diameter: 32 mm, upper step height) The lower inner diameter: 48 mm, the overall
height: 32 mm) is provided in close contact with the lower inner surface.
The material of the magnetic conducting part is, for example, carbon steel, and the material of
the magnet 3 is, for example, an Nd--Fe--B alloy.
A magnetic pole 6 is formed on the upper outer side surface of the center pole 1 and the inner
side surface of the yoke 2, and a voice coil 5 (inner diameter: 30.8 mm, length: 5 mm) is installed
in a magnetic gap between both surfaces.
The diaphragm 8 is connected to the voice coil 5 by a bobbin 7 and supported by a damper 9
located 3 mm above the yoke 2.
[0014]
FIG. 2 shows the result of examining the driving secondary distortion of the voice coil. Here,
Conventional Example 1 corresponds to FIG. 33, and the external dimensions of the magnetic
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circuit in FIG. 33, the shape dimensions and the material of the magnet are the same as those of
the present embodiment. That is, the outer diameter of the center pole 101: 32 mm, the upper
step height: 8 mm, the lower outer diameter: 48 mm, the lower step height: 8 mm, the entire
height: 32 mm, the outer diameter of the yoke 102: 54 mm, the same Inner diameter: 48 mm,
same height: 32 mm, outer diameter of annular magnet 103: 48 mm, same inner diameter: 32
mm, same height: 8 mm, inner diameter of voice coil 105: 30.8 mm, same length: 5 mm. In the
present embodiment, since the magnet 3 is not disposed in the magnetic pole portion 5, the
direct influence of the AC magnetic field by the voice coil is less likely than in the conventional
case. For this reason, the fluctuation of the DC magnetic flux density inside the magnet becomes
smaller than before, and as shown in FIG. 2, the secondary distortion becomes smaller than
before. If a nonmagnetic conductive ring is used in combination with the center pole outer
peripheral portion and the yoke inner peripheral portion, distortion is further reduced. Further,
in the present embodiment, since the magnet is separated from the voice coil, the coil is not
directly affected by heat generation, and in particular, thermal demagnetization causing problems
with Nd-Fe-B based alloy magnets can be avoided. It also has an advantage.
[0015]
Also, when a larger air gap magnetic flux density is required to increase the output of the
speaker, it is necessary to increase the volume of the magnet that is the source of the magnetic
flux, but if the height of the magnet is to be increased, As apparent from FIG. 33, it is hardly
possible to increase the height because the damper installed at the top of the yoke is an obstacle.
If the bobbin is lengthened and the mounting position of the damper is further moved upward,
although it is possible to further increase the height of the magnet, the lengthening of the bobbin
may cause the occurrence of rolling, which is not preferable. As described above, since the size of
the magnetic pole portion is restricted by various factors, in the conventional type in which the
magnet is disposed in the magnetic pole portion, the size of the magnet is restricted. On the other
hand, in the present invention, as shown in FIG. 1, the magnet is located at the lower part of the
magnetic circuit and there is nothing obstructive to the lower side, so the height of the magnet is
increased without problem toward the magnetic circuit downward. be able to. For example, the
magnet height of the present embodiment can be increased to, for example, 8 → 12 → 16 mm
(at this time, the heights of the yoke and the center pole are also increased). Although the
relationship between the height of the magnet and the air-gap magnetic flux density is shown in
FIG. In the conventional type, since the height of the magnet is equal to the height of the
magnetic pole portion, by making the height of the magnet of the present invention at least
larger than the height of the magnetic pole portion, air gap magnetic flux density higher than
conventional can be reliably obtained. it can. The magnet 3 is not limited to a ferrite magnet, and
a metal magnet, a rare earth magnet, or a composite magnet containing resin or rubber can be
used.
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[0016]
Second Embodiment Hereinafter, another embodiment of the present invention will be described
based on the drawings. FIG. 4 is a longitudinal sectional view showing the configuration of a
speaker magnetic circuit according to another embodiment of the present invention. In the
figure, an annular ring magnetized in the radial direction in close contact with the lower outer
surface of the center pole 1 (upper outer diameter: 40 mm, upper step height: 8 mm, lower outer
diameter: 24 mm, overall height: 32 mm) Magnet 3 (outside diameter: 40 mm, inside diameter:
24 mm, height: 8 mm) is installed, and yoke 2 (outside diameter: 54 mm, upper inside diameter:
48 mm, lower inside diameter: 40 mm, lower step height: 8 mm, overall height: 24 mm) is
provided in close contact with the lower inner surface. An annular top plate 4 (outside diameter:
54 mm, inside diameter 42 mm, height 8 mm) is installed on the top of the yoke 2. The material
of the magnetic conducting part is, for example, carbon steel, and the material of the magnet 3 is,
for example, an Nd--Fe--B alloy. A magnetic pole 6 is formed on the upper outer side surface of
the center pole 1 and the inner side surface of the top rate 4, and a voice coil 5 (inner diameter:
40.8 mm, length: 5 mm) is installed in a magnetic gap between both surfaces.
[0017]
FIG. 5 shows the result of examining the driving secondary distortion of the voice coil. Here,
Conventional Example 2 corresponds to FIG. 32, and the external dimensions of the magnetic
circuit of FIG. 32 and the shape dimensions and material of the magnet are the same as those of
the present embodiment. That is, the outer diameter of the center pole 101: 24 mm, the same
height: 32 mm, the outer diameter of the yoke 102: 54 mm, the upper inner diameter: 48 mm,
the lower inner diameter: 24 mm, the lower step height: 8 mm, the overall height Outer diameter
of annular magnet 103: 40 mm, inner diameter: 24 mm, same height: 8 mm, outer diameter of
top plate 104: 54 mm, same inner diameter 42 mm, same height 8 mm, inner diameter of voice
coil 105: 40.8 mm, Same length: 5 mm. The magnetic circuit according to the present invention
has a structure in which the magnet is not disposed in the magnetic pole portion, so that it is less
susceptible to the direct influence of the AC magnetic field by the voice coil than in the prior art.
For this reason, the fluctuation of the DC magnetic flux density inside the magnet becomes
smaller than that of the conventional one, and as shown in FIG. 5, the secondary distortion
becomes smaller than that of the conventional one. If a nonmagnetic conductive ring is used in
combination with the center pole outer peripheral portion and the yoke inner peripheral portion,
distortion is further reduced. Further, in the present embodiment, since the magnet is separated
from the voice coil, the coil is not directly affected by heat generation, and in particular, thermal
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demagnetization causing problems with Nd-Fe-B based alloy magnets can be avoided. It also has
an advantage.
[0018]
Furthermore, in the present embodiment, the size of the magnet is not constrained to the size of
the magnetic pole as in the prior art, so the height of the magnet can be freely set. For example,
the height of the magnet of the present embodiment can be increased to 8 → 12 → 16 mm or
the like (at this time, the heights of the yoke and the center pole are also increased). Although the
relationship between the height of the magnet and the air-gap magnetic flux density is shown in
FIG. 6, the air-gap magnetic flux density can be made higher in the present invention than in the
prior art. In the conventional type, since the height of the magnet is equal to the height of the
magnetic pole portion, by making the height of the magnet of the present invention at least
larger than the height of the magnetic pole portion, air gap magnetic flux density higher than
conventional can be reliably obtained. it can. The magnet 3 is not limited to a ferrite magnet, and
a metal magnet, a rare earth magnet, or a composite magnet containing resin or rubber can be
used.
[0019]
Third Embodiment Hereinafter, still another embodiment of the present invention will be
described based on the drawings. FIG. 7 is a longitudinal sectional view showing the
configuration of a speaker magnetic circuit according to still another embodiment of the present
invention. As shown, when the diaphragm is dome-shaped, the outer diameter of the diaphragm
is smaller than the outer diameter of the magnetic circuit. In other words, the outer diameter of
the magnetic circuit determines the outer diameter of the speaker. From the viewpoint of
downsizing the speaker, it is desirable that the outer diameter of the magnetic circuit be as small
as possible. On the other hand, when the outer diameter of the magnetic circuit is reduced, there
is a problem that the air-gap magnetic flux density of the voice coil portion is reduced. For
example, when forming a magnetic circuit using a dome-shaped diaphragm having an outer
diameter of 11 mm, the outer diameter of the magnetic circuit may be restricted to, for example,
24 mm for downsizing. In the conventional outer magnet type and inner magnet type, with this
magnetic circuit outer diameter, there is a problem that the air gap magnetic flux density hardly
increases even if the volume of the magnet is increased. In the present invention, this problem is
solved to improve the air gap magnetic flux density. The constitution of the present invention is
as follows, in close contact with the lower outer surface of the center pole 1 (upper outer
diameter: 10 mm, upper step height: 4 mm, lower outer diameter: 8 mm, overall height: 19-29
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mm) The annular magnet 3 (outer diameter: 17.5 mm, inner diameter: 8 mm, height: 11 to 21
mm) magnetized in the radial direction is installed, and the yoke 2 (outer diameter: 24 mm,
upper inner diameter: 21 mm, lower inner diameter: 17.5 mm, lower step height: 10 to 20 mm,
overall height: 15 to 25 mm) are provided in close contact with the lower inner surface. An
annular top plate 4 (outer diameter: 24 mm, inner diameter 12 mm, height 4 mm) is installed on
the top of the yoke 2. The material of the magnetic conducting part is, for example, carbon steel,
and the magnet 3 is, for example, an Nd-Fe-B based magnet. A magnetic pole 6 is formed on the
upper outer surface of the center pole 1 and the inner surface of the top rate 4, and a voice coil 5
(inner diameter: 10.7 mm, length: 3 mm) is installed in the magnetic gap between both surfaces.
The dome-shaped diaphragm 8 (outer diameter: 11 mm) is connected to the voice coil 5 via the
bobbin 7.
[0020]
For comparison, FIG. 8 (a) shows a conventional representative external magnet type magnetic
circuit. As the diaphragm, a dome shape having an outer diameter of 11 mm, which is the same
as that of the above embodiment, is used, and the outer diameter of the magnetic circuit is also
24 mm. Further, the material of the magnetic conducting part and the magnet, and the shape and
size of the magnetic pole part also use the same specifications as those of the present invention.
The details of the configuration are as follows, center pole 1 (upper outer diameter: 10 mm,
upper step height: 4 mm, lower outer diameter) on the upper surface of the disk-shaped bottom
plate 10 (outer diameter: 22 mm, height: 5 mm) The annular magnet 3 (outer diameter: 24 mm,
inner diameter: 14 mm, height: 11 to 21 mm) magnetized in the height direction is concentrically
attached to the magnet 3 of: 8 mm, overall height: 15 to 25 mm. An annular top plate 4 (outside
diameter: 22 mm, inside diameter 12 mm, height 4 mm) is installed at the top. A magnetic pole 6
is formed on the upper outer surface of the center pole 1 and the inner surface of the top rate 4,
and a voice coil 5 (inner diameter: 10.7 mm, length: 3 mm) is installed in the magnetic gap
between both surfaces. The dome-shaped diaphragm 8 (outer diameter: 11 mm) is connected to
the voice coil 5 via the bobbin 7.
[0021]
Further, for comparison, FIG. 8 (b) shows a typical internal magnetic circuit of the prior art. As
the diaphragm, a dome shape having an outer diameter of 11 mm, which is the same as that of
the above embodiment, is used, and the outer diameter of the magnetic circuit is also 24 mm.
Further, the same specifications as those of the present invention are used for the material of the
magnetic conducting part and the magnet, the shape and dimensions of the magnetic pole part,
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and the inner and outer diameters of the yoke. The details of the configuration are as follows,
and a cylindrical magnet 3 (outside diameter) at the center of the upper surface of the yoke 2
(outside diameter: 24 mm, inside diameter: 21 mm, bottom thickness: 5 mm, height: 24 to 34
mm) 16 mm, height: 11 to 21 mm) are attached, and the center pole 1 (upper outer diameter: 10
mm, upper step height: 4 mm, middle outer diameter: 8 mm, lower outer diameter: 16 mm)
Height: 12 mm) is installed. An annular top plate 4 (outer diameter: 24 mm, inner diameter 12
mm, height 4 mm) is installed on the top of the yoke 2. A magnetic pole 6 is formed on the upper
outer surface of the center pole 1 and the inner surface of the top rate 4, and a voice coil 5 (inner
diameter: 10.7 mm, length: 3 mm) is installed in the magnetic gap between both surfaces. The
dome-shaped diaphragm 8 (outer diameter: 11 mm) is connected to the voice coil 5 via the
bobbin 7.
[0022]
FIG. 9 shows the air gap magnetic flux density in the magnetic circuit (third embodiment) of the
present invention, the conventional external magnetic type (conventional example 3A), and the
internal magnetic type magnetic circuit (3B). As can be seen by comparing the embodiment 3-1
of FIG. 9 with the prior art example 3A-1 and the prior art example 3B-1, according to the
present invention, although the volume of the magnet is smaller than that of the other prior art
The value of magnetic flux density is the largest. This indicates that the magnetic utilization
efficiency of the magnet of the present invention is higher than that of other conventional
magnetic circuits. In addition, in Embodiments 3-1, 3-2 and 3-3, Conventional Examples 3A-1,
3A-2 and 3A-3, and Conventional Examples 3B-1, 3B-2 and 3B-3 in FIG. Although the height of
the magnet is increased to 11 → 16 → 21 mm, the gap magnetic flux density hardly increases
with the two conventional types with respect to the increase of the magnet height, whereas the
gap with respect to the increase of the magnet height according to the present invention The rate
of increase in magnetic flux density is extremely large.
[0023]
In FIG. 10, when the diameter of the diaphragm is, for example, 30 mm and the outer diameter of
the magnetic circuit is restricted to, for example, 44 mm (embodiments 3-4 to 3-6, conventional
examples 3A-4 to 3A-6, conventional example 3B-4 to 3B-6), or in the case where the diameter of
the diaphragm is, for example, 80 mm and the outer diameter of the magnetic circuit is restricted
to, for example, 92 mm (embodiments 3-7 to 3-9, conventional example 3A-7). The results are
also shown together for ~ 3A-9 and prior art examples 3B-7 to 3B-9). Also in these cases, as
described above, according to the present invention, although the volume of the magnet is
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smaller than that of other conventional types, the value of the air gap magnetic flux density is the
largest, and the air gap magnetic flux density against the increase of the magnet height The rate
of increase of is significantly larger than that of the conventional type. As described above, when
the outer diameter of the magnetic circuit is restricted to a small size, the present invention can
obtain a higher air-gap magnetic flux density than the conventional inner magnetic type or outer
magnetic type. In other words, if the air gap magnetic flux density is the same, the outer diameter
of the magnetic circuit can be made smaller according to the present invention.
[0024]
The dimensions of each component in each embodiment and conventional example shown in
FIGS. 9 and 10 are as follows. Embodiments 3-4 to 3-6 center pole 1; upper outer diameter: 29
mm, upper step height: 4 mm, lower outer diameter: 24 mm, overall height: 24 to 34 mm magnet
3; outer diameter: 36 mm, inner diameter : 24 mm, height: 16 to 26 mm yoke 2; outer diameter:
44 mm, upper inner diameter: 37 mm, lower inner diameter: 36 mm, lower step height: 15 to 25
mm, overall height: 20 to 30 mm top rate 4; outer diameter : 44 mm, inner diameter 31 mm,
height 4 mm voice coil 5; inner diameter: 29.7 mm, length: 3 mm diaphragm 8; outer diameter:
30 mm material of magnetic conducting part is carbon steel, magnet is Nd-Fe-B based magnet .
Conventional example 3A-4 to 3A-6 (FIG. 8 (a)) bottom plate 10; outer diameter: 42 mm, height:
5 mm center pole 1; upper outer diameter: 29 mm, upper step height: 4 mm, lower outer
diameter: 24 mm, overall height: 20 to 30 mm magnet 3; outer diameter: 44 mm, inner diameter:
33 mm, height: 16 to 26 mm top plate 4; outer diameter: 42 mm, inner diameter: 31 mm, height:
4 mm voice coil 5; inner diameter 29.7 mm, length: 3 mm, diaphragm 8; outer diameter: 30 mm,
for example, the material of the magnetic conducting part is carbon steel, and the magnet is, for
example, an Nd-Fe-B based magnet. Conventional example 3B-4 to 3B-6 (FIG. 8 (b)) Yoke 2; outer
diameter: 44 mm, inner diameter: 37 mm, bottom thickness: 5 mm, height: 29 to 39 mm magnet
3; outer diameter: 28 mm, height Upper outer diameter: 29 mm, upper step height: 4 mm, middle
outer diameter: 24 mm, lower outer diameter: 28 mm, overall height: 12 mm top plate 4; outer
diameter: 44 mm, inner diameter 31 mm , Height 4 mm voice coil 5; inner diameter: 29.7 mm,
length: 3 mm diaphragm 8; outer diameter: 30 mm, for example, the material of the magnetically
conductive portion is carbon steel, and the magnet is, for example, Nd-Fe-B based magnet.
Embodiment 3-7 to 3-9 Center pole 1; upper outer diameter: 79 mm, upper step height: 4 mm,
lower outer diameter: 45 mm, overall height: 53 to 73 mm magnet 3; outer diameter: 59 mm,
inner diameter : 45 mm, height: 45 to 65 mm yoke 2; outer diameter: 92 mm, upper inner
diameter: 83 mm, lower inner diameter: 59 mm, lower step height: 44 to 64 mm, overall height:
49 to 69 mm top rate 4; outer diameter : 92 mm, inner diameter 81 mm, height 4 mm voice coil
5; inner diameter: 79.7 mm, length: 3 mm diaphragm 8; outer diameter: 80 mm, for example,
material of magnetically conductive portion is carbon steel, magnet is, for example, Nd-Fe-B
based magnet .
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Conventional example 3A-7 to 3A-9 (FIG. 8 (a)) bottom plate 10; outer diameter: 90 mm, height:
5 mm center pole 1; upper outer diameter: 79 mm, upper step height: 4 mm, lower outer
diameter: 45 mm, overall height: 49 to 69 mm magnet 3; outer diameter: 92 mm, inner diameter:
83 mm, height: 45 to 65 mm top plate 4; outer diameter: 90 mm, inner diameter 81 mm, height
4 mm voice coil 5; inner diameter: 79.7 mm, length: 3 mm diaphragm 8; outer diameter: 80 mm,
for example, the material of the magnetically conductive portion is carbon steel, and the magnet
is, for example, an Nd-Fe-B based magnet. Conventional Example 3B-7 to 3B-9 (FIG. 8 (b)) Yoke 2;
Outer diameter: 92 mm, Inner diameter: 83 mm, Bottom thickness: 5 mm, Height: 58 to 78 mm
Magnet 3; Outer diameter: 63.5 mm, High Upper part diameter: 79 mm, upper step height: 4 mm,
middle part outer diameter: 45 mm, lower outer diameter: 63.5 mm, overall height: 12 mm top
plate 4; outer diameter: 92 mm, Inner diameter 81 mm, height 4 mm voice coil 5; inner diameter:
79.7 mm, length: 3 mm vibrating plate 8; The magnet is not limited to the Nd-Fe-B magnet, and
other rare earth magnets, metal magnets, ferrite magnets, or composite magnets containing resin
or rubber can be used.
[0025]
Fourth Embodiment An embodiment of the present invention will be described below based on
the drawings. FIG. 11 is a longitudinal sectional view showing the configuration of the speaker
magnetic circuit according to the embodiment of the present invention. In the figure, an annular
ring magnetized in the radial direction in close contact with the lower outer surface of the center
pole 1 (upper outer diameter: 36 mm, upper step height: 6 mm, lower outer diameter: 24 mm,
overall height: 30 mm) Magnet 3 (outside diameter: 40 mm, inside diameter: 24 mm, height: 16
mm) is installed, and yoke 2 (outside diameter: 46 mm, top inside diameter: 37.8 mm, top step
height: 6 mm, bottom inside diameter) 40 mm, overall height: 30 mm) are provided in close
contact with the lower inner surface. The material of the magnetic conducting part is, for
example, carbon steel, and the material of the magnet 3 is, for example, an Nd--Fe--B alloy. A
magnetic pole 6 is formed on the upper outer surface of the center pole 1 and the upper inner
surface of the yoke 2, and a voice coil 5 (inner diameter: 36.7 mm, length: 3 mm) is installed in
the magnetic gap between both surfaces. Then, a disk-shaped magnetic shielding cover 11
(outside diameter 46 mm, height 3 mm) is mounted at a position 6 mm below the magnetic
circuit, separated from the yoke 2 and the annular magnet 3 by the connecting member 12 of
nonmagnetic material. ing. Magnetic shielding cover 11 is, for example, mild steel, and
connecting member 12 is, for example, a resin. Because the connecting member 12 is a
nonmagnetic material, the magnetic shielding cover 11 is also magnetically separated from the
yoke 2 and the annular magnet 3.
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[0026]
Further, in FIG. 12, the main part of the magnetic circuit consisting of the magnetic conductive
part, the magnet and the voice coil is the same as FIG. 11, and the magnetic shielding cover 11
(outside diameter: 58 mm, U-shaped in cross section at 6 mm below the magnetic circuit) An
example is shown in which the inner diameter: 52 mm, bottom thickness: 3 mm, height: 24 mm)
is attached by the connecting member 12. Magnetic shielding cover 11 is, for example, mild steel,
and connecting member 12 is, for example, a resin.
[0027]
Also, in FIG. 13, the main part of the magnetic circuit consisting of the magnetic conductive part,
the magnet and the voice coil is the same as FIG. 11, and the magnetic shielding cover 11
(outside diameter: 46 mm, convex) is formed 6 mm below the magnetic circuit. An example in
which the outer diameter of the part: 24 mm, the height of the convex part 6 mm, the overall
height: 9 mm) is attached by the connecting member 12 is shown. Magnetic shielding cover 11
is, for example, mild steel, and connecting member 12 is, for example, a resin.
[0028]
Furthermore, in FIG. 14, the main part of the magnetic circuit consisting of the magnetic
conductive part, the magnet, and the voice coil is the same as that in FIG. 11, and the magnetic
shielding cover has a U-shaped cross section at a position 6 mm below the magnetic circuit An
example in which 11 (outer diameter: 58 mm, inner diameter: 52 mm, convex outer diameter: 24
mm, convex height 6 mm, bottom thickness: 3 mm, overall height: 24 mm) is attached by the
connecting member 12 is shown. Magnetic shielding cover 11 is, for example, mild steel, and
connecting member 12 is, for example, a resin. In FIGS. 13 and 14, although the magnetic
shielding cover 11 is magnetically connected to the center pole 1, the yoke 2 and the annular
magnet 3 are magnetically connected to each other through the connecting member 12 made of
a nonmagnetic material. It will be separated by
[0029]
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The present invention has the same effect as that of the first embodiment because the basic
configuration of the magnetic circuit is the same as that of the first embodiment. Further, FIG. 15
shows a leakage magnetic flux density, but in the embodiments 4-1 to 4-4 of the present
invention (corresponding to FIGS. 11 to 14 respectively), since the magnetic shielding cover is
installed, the magnetic shielding cover is used. Leakage flux to the outside of the magnetic circuit
is smaller than that in the case (Comparative Example 4). Here, the leakage magnetic flux density
indicates the magnetic flux density at a point (A) 10 mm below the bottom of the ring magnet.
When the magnetic shielding cover contacts both the center pole and the yoke, a closed magnetic
path is formed in the lower part of the magnetic circuit, most of the magnetic flux is circulated in
the lower part, and the air gap magnetic flux density of the magnetic pole decreases.
[0030]
Further, in FIGS. 13 and 14, although the convex portion is provided on the magnetic shielding
cover, the central portion of the magnetic shielding cover may be flat and the center pole may be
extended downward to be in close contact with the magnetic shielding cover. In addition, the
magnetic shielding cover 11 is not limited to mild steel, but may be an Fe-Ni alloy, an Fe-Co alloy,
a silicon steel plate, a magnetic material covered with a resin or the like, or a laminate of a
magnetic material and a nonmagnetic material. A member etc. can be used. The connecting
member is not limited to resin, and various nonmagnetic members such as nonmagnetic metals
such as aluminum and copper, rubber, and carbon fiber composite materials can be used.
[0031]
Embodiment 5 Hereinafter, an embodiment of the present invention will be described based on
FIG. FIG. 16 is a longitudinal sectional view showing a configuration of a speaker magnetic circuit
according to one embodiment of the present invention. In the figure, the main part of the
magnetic circuit consisting of the magnetic conductive part, the magnet and the voice coil is the
same as in Fig. 11, and the magnetic shielding cover 11 (outside diameter: 46 mm, inside
diameter: 40 mm, bottom thickness) : 3 mm, overall height: 9 mm) are provided in close contact.
Magnetic shielding cover 11 is, for example, a mild steel.
[0032]
Further, in FIG. 17, the main part of the magnetic circuit consisting of the magnetic conductive
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part, the magnet, and the voice coil is the same as FIG. 11, and the U-shaped magnetic shielding
cover 11 (outer diameter: 52 mm, inner diameter: 46 mm) , Bottom thickness: 3 mm, overall
height: 15 mm) An example is shown in which the upper inner periphery is in close contact. The
magnetic shielding cover and the center pole are separated by 6 mm. Magnetic shielding cover
11 is, for example, a mild steel.
[0033]
The present invention has the same effect as that of the first embodiment because the basic
configuration of the magnetic circuit is the same as that of the first embodiment. In addition to
this, in Embodiments 5-1 and 5-2 of the present invention (corresponding to FIGS. 16 and 17,
respectively), since the magnetic shielding cover is installed and its outer edge portion is in close
contact with the yoke, Then, a closed space surrounded by magnetic material is formed. As a
result, as shown in the leakage magnetic flux density measurement result of FIG. 18, the leakage
magnetic flux to the outside of the magnetic circuit is further reduced compared to Comparative
Examples 5-1 to 5-4. Here, the leakage magnetic flux density indicates a magnetic flux density at
a point (A) separated by 10 mm from the bottom of the ring magnet and a point (B) separated by
6 mm from the center of the end face of the magnetic shielding cover. When the magnetic
shielding cover contacts the center pole, a closed magnetic path is formed in the lower part of
the magnetic circuit, most of the magnetic flux is circulated in the lower part, and the air-gap
magnetic flux density of the magnetic pole decreases. 16 and 17, the cross section of the
magnetic shielding cover is U-shaped, but the magnetic shielding cover may be a disk, and the
yoke may be extended downward to be in close contact with the magnetic shielding cover. In
addition, the magnetic shielding cover 11 is not limited to mild steel, but may be an Fe-Ni alloy,
an Fe-Co alloy, a silicon steel plate, a magnetic material covered with a resin or the like, or a
laminate of a magnetic material and a nonmagnetic material. A member etc. can be used.
[0034]
Sixth Embodiment Hereinafter, an embodiment of the present invention will be described based
on FIG. FIG. 19 is a longitudinal sectional view showing the configuration of a speaker magnetic
circuit according to an embodiment of the present invention, in which the magnetic circuit shown
in FIG. 12 is magnetized in the height direction between the center pole and the magnetic shield
cover. The direction in which the two cylindrical magnets 3 '(outside diameter: 24 mm, height: 6
mm) have the same pole as the pole on the inner side of the first magnet disposed on the outside
of the center pole, It is installed in the direction in which the first magnet and the repulsive force
work. The magnetic shielding cover 11 is, for example, mild steel, the connecting member 12 is,
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for example, a resin, and the second magnet 3 'is, for example, a ferrite magnet.
[0035]
Further, in FIG. 20, a second annular magnet 3 '(outside diameter: 46 mm, inside diameter: 40
mm, high) magnetized in the height direction between the lower surface of the yoke of the
magnetic circuit in FIG. (6 mm), the magnetic pole on the top surface of which is the same as the
magnetic pole on the outer surface of the first magnet arranged outside the center pole, ie, the
direction in which the repulsive force with the first magnet acts. ing. The magnetic shielding
cover 11 is, for example, mild steel, the connecting member 12 is, for example, a resin, and the
second magnet 3 'is, for example, a ferrite magnet.
[0036]
Further, in FIG. 21, a second annular magnet 3 ′ (outer diameter: 52 mm, inner diameter: 46
mm, high) magnetized in the radial direction between the outer surface of the yoke of the
magnetic circuit in FIG. (6 mm), but with the magnetic pole on the inner side facing the same as
the magnetic pole on the outer side of the first magnet arranged outside the center pole, ie, the
direction in which the repulsive force with the first magnet works It is done. The magnetic
shielding cover 11 is, for example, mild steel, the connecting member 12 is, for example, a resin,
and the second magnet 3 'is, for example, a ferrite magnet.
[0037]
The present invention has the same advantages as the fourth embodiment because the basic
configuration of the magnetic circuit is the same as the fourth embodiment. Although the air-gap
magnetic flux density is shown in FIG. 22, in the present invention, the second magnet is installed
inside the magnetic shielding cover in a direction to generate a repulsive force with the first
magnet. As shown in -3 (each corresponding to FIGS. 19 to 21), the air-gap magnetic flux density
is larger than that in the case where the second magnet is not used for these (comparative
example 6).
[0038]
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Although a cylindrical magnet is used as the second magnet in FIG. 19, it is also possible to use
an annular magnet. In addition, the magnetic shielding cover 11 is not limited to mild steel, but
may be an Fe-Ni alloy, an Fe-Co alloy, a silicon steel plate, a magnetic material covered with a
resin or the like, or a laminate of a magnetic material and a nonmagnetic material. A member etc.
can be used. The connecting member is not limited to resin, and various members such as
nonmagnetic metal such as aluminum and copper, rubber, carbon fiber composite material, etc.
can be used. Furthermore, the magnets 3 and 13 are not limited to ferrite magnets, and may be
metal magnets, rare earth magnets, or composite magnets containing resin or rubber.
[0039]
Embodiment 7 Hereinafter, another embodiment of the present invention will be described based
on FIG. FIG. 23 is a longitudinal sectional view showing the configuration of a speaker magnetic
circuit according to another embodiment of the present invention, in which the outer diameter of
the convex portion of the magnetic shielding cover of the magnetic circuit in FIG. The second
annular magnet 3 '(outside diameter: 24 mm, inside diameter: 12 mm, height: 6 mm) magnetized
in the height direction is the first magnet whose top pole is disposed outside the center pole It is
installed in the same direction as the magnetic pole of the inner surface of the, that is, the
direction in which the first magnet and the repulsive force work. The upper and lower surfaces of
the second magnet are in close contact with the lower surface of the center pole and the
magnetic shield, respectively. The magnetic shielding cover 11 is, for example, mild steel, the
connecting member 12 is, for example, a resin, and the second magnet 3 'is, for example, a ferrite
magnet.
[0040]
Further, FIG. 24 shows a second annular magnet 3 '(outer diameter: 46 mm, inner diameter: 40
mm, height) magnetized in the height direction between the yoke lower surface of the magnetic
circuit in FIG. 14 and the magnetic shielding cover. (6 mm), with the magnetic pole on the top
surface oriented in the same direction as the magnetic pole on the outer surface of the first
magnet disposed outside the center pole, ie, in the direction in which the first magnet exerts
repulsive force Show an example. The magnetic shielding cover 11 is, for example, mild steel, the
connecting member 12 is, for example, a resin, and the second magnet 3 'is, for example, a ferrite
magnet.
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[0041]
Furthermore, FIG. 25 shows the second annular magnet 3 '(outer diameter: 52 mm, inner
diameter: 46 mm, high) magnetized in the radial direction between the yoke outer surface of the
magnetic circuit in FIG. 14 and the magnetic shielding cover. (6 mm), but with the magnetic pole
on the inner side facing the same as the magnetic pole on the outer side of the first magnet
arranged outside the center pole, ie, the direction in which the repulsive force with the first
magnet works An example is shown. The magnetic shielding cover 11 is, for example, mild steel,
the connecting member 12 is, for example, a resin, and the second magnet 3 'is, for example, a
ferrite magnet.
[0042]
The present invention has the same advantages as the fourth embodiment because the basic
configuration of the magnetic circuit is the same as the fourth embodiment. Although the air gap
magnetic density is shown in FIG. 26, the embodiments 7-1 to 7-3 (each corresponding to FIGS.
23 to 25) are compared with the case where the second magnet is not used for them
(comparative example 7). However, the air gap magnetic flux density is larger in the former as
well. When the magnetic shielding cover contacts both the center pole and the yoke, a closed
magnetic path is formed in the lower part of the magnetic circuit, most of the magnetic flux is
circulated in the lower part, and the air gap magnetic flux density of the magnetic pole decreases.
Moreover, although the convex part is provided in the magnetic shielding cover in FIGS. 23-25,
the center part of the magnetic shielding cover may be flat and the structure which extended |
stretched the center pole below and closely_contact | adhered with the magnetic shielding cover
may be sufficient. In addition, the magnetic shielding cover 11 is not limited to mild steel, but
may be an Fe-Ni alloy, an Fe-Co alloy, a silicon steel plate, a magnetic material covered with a
resin or the like, or a laminate of a magnetic material and a nonmagnetic material. A member etc.
can be used. The connecting member is not limited to resin, and various nonmagnetic members
such as nonmagnetic metals such as aluminum and copper, rubber, and carbon fiber composite
materials can be used. Furthermore, the magnets 3 and 13 are not limited to ferrite magnets, and
may be metal magnets, rare earth magnets, or composite magnets containing resin or rubber.
[0043]
Eighth Embodiment Hereinafter, an embodiment of the present invention will be described based
on FIG. FIG. 27 is a longitudinal sectional view showing the configuration of the speaker
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magnetic circuit according to one embodiment of the present invention, wherein a second
cylinder magnetized in the height direction between the center pole and the magnetic shielding
cover 11 in FIG. The magnet 3 '(outside diameter: 24 mm, height: 6 mm) is oriented in such a
manner that the pole on the top surface is the same as the pole on the inner surface of the first
magnet disposed outside the center pole, It is installed in the direction in which the magnet and
the repulsive force work. The magnetic shielding cover 11 is, for example, mild steel, and the
second magnet 3 ′ is, for example, a ferrite magnet.
[0044]
In FIG. 28, the second cylindrical magnet 3 '(outer diameter: 24 mm, height: 6 mm) magnetized in
the height direction is located between the center pole and the magnetic shielding cover 11 in
FIG. An example is shown in which the magnetic poles are disposed in the same direction as the
magnetic poles of the inner surface of the first magnet disposed outside the center pole, that is,
in the direction in which the first magnet and the repulsive force work. The magnetic shielding
cover 11 is, for example, mild steel, and the second magnet 3 ′ is, for example, a ferrite magnet.
[0045]
The present invention has the same advantages as the fifth embodiment because the basic
configuration of the magnetic circuit is the same as the fifth embodiment. In addition to this, in
the present invention, the second magnet is installed on the inner side of the magnetic shielding
cover in a direction to generate a repulsive force with the first magnet. Therefore, Embodiment 81 or 8-2 in FIG. As shown in FIGS. 27 and 28, the magnetic flux density at the central portion of
the magnetic gap is larger than that in the case where the second magnet is not used
(Comparative Examples 8-1 and 8-2). In FIGS. 27 and 28, a cylindrical magnet is used as the
second magnet, but it is also possible to use an annular magnet. Further, although the cross
section of the magnetic shielding cover is U-shaped, the magnetic shielding cover may be a disk,
and the yoke may be extended downward to be in close contact with the magnetic shielding
cover. In addition, the magnetic shielding cover is not limited to 11 soft iron, but Fe-Ni alloy, FeCo alloy, silicon steel, further, those obtained by covering these magnetic materials with resin,
etc., and lamination of magnetic materials and nonmagnetic materials A member etc. can be used.
The magnets 3 and 13 are not limited to ferrite magnets, and may be metal magnets, rare earth
magnets, or composite magnets containing resin or rubber. On the other hand, in FIG. 28, when
the second magnet 3 ′ is an annular magnet and disposed under the yoke, a magnetic path is
generated because the yoke and the magnetic shielding cover are in close contact with each
other around the second magnet 3 ′. Thus, even if the second magnet is disposed at the position
12-04-2019
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where the closed magnetic path is formed, the magnetic flux circulates in the closed magnetic
path, so the air gap magnetic flux density is hardly improved. Therefore, it is desirable to provide
the second magnet 3 'at a position where a closed magnetic circuit is not formed. In addition,
when the magnetic shielding cover contacts the center pole, a closed magnetic path is formed in
the lower part of the magnetic circuit, most of the magnetic flux is circulated in the lower part,
and the air-gap magnetic flux density of the magnetic pole portion decreases.
[0046]
The size of each component shown in the first to eighth embodiments is merely an example, and
is not limited to this size.
[0047]
As described above, in the speaker magnetic circuit according to the present invention, since the
ring magnet magnetized in the radial direction is disposed outside the magnetic pole portion
forming the magnetic gap, the magnet is an AC magnetic field generated by the voice coil. Avoid
the direct effects of heat and fever.
For this reason, the fluctuation of the DC magnetic flux density inside the magnet becomes
smaller than before, driving distortion of the voice coil is reduced, and the sound quality is
improved, and the thermal demagnetization that causes problems in Nd-Fe-B alloy magnets is
avoided. With the advantage of being able to Also, if the height of the annular magnet of the
present invention is made greater than any of the height of the magnetic pole surface of the
center pole outer peripheral portion and the height of the magnetic pole surface of the yoke
inner peripheral portion, the annular magnet magnetized in the radial direction is disposed. The
air gap magnetic flux density higher than that of the above magnetic circuit can be obtained, and
furthermore, the higher air gap magnetic flux density can be obtained for the external magnetic
type magnetic circuit and the internal magnetic type magnetic circuit. realizable. In other words,
the magnetic circuit can be further miniaturized if the output is the same.
[0048]
Further, in the speaker magnetic circuit according to the present invention, in addition to the
above-described configuration, since the magnetic shielding cover is further disposed apart from
below the center pole and the yoke, there is also an effect that the leakage flux to the outside of
the magnetic circuit is small. Have.
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[0049]
Furthermore, in the speaker magnetic circuit according to the present invention, in addition to
the above-described configuration, the second magnet has a repulsive force with the first magnet
(annular magnet) between the magnetic shielding cover and the center pole or between the
magnetic shielding cover and the yoke. Since it is installed in the direction in which it is
generated, it has an effect of reducing the leakage flux to the outside of the magnetic circuit and
improving the air gap magnetic flux density.
[0050]
Brief description of the drawings
[0051]
FIG. 1 is a longitudinal sectional view showing a configuration of a speaker magnetic circuit used
in Embodiment 1 of the present invention.
[0052]
FIG. 2 is a diagram showing driving secondary distortion caused by the speaker magnetic circuit
used in the first embodiment of the present invention in comparison with a conventional
example.
[0053]
FIG. 3 is a diagram showing air gap magnetic flux density by the speaker magnetic circuit used in
the first embodiment of the present invention in comparison with the conventional example.
[0054]
FIG. 4 is a longitudinal sectional view showing a configuration of a speaker magnetic circuit used
in Embodiment 2 of the present invention.
[0055]
FIG. 6 is a diagram showing driving secondary distortion caused by the speaker magnetic circuit
used in Embodiment 2 of the present invention in comparison with a conventional example.
[0056]
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FIG. 6 is a diagram showing air gap magnetic flux density by the speaker magnetic circuit used in
the second embodiment of the present invention in comparison with the conventional example.
[0057]
FIG. 7 is a longitudinal sectional view showing a configuration of a speaker magnetic circuit used
in Embodiment 3 of the present invention.
[0058]
FIG. 8 is a longitudinal sectional view showing the configuration of a conventional speaker
magnetic circuit to be compared with Embodiment 3 of the present invention, in which (a) is an
external magnet type and (b) is an internal magnet type speaker magnetic circuit .
[0059]
FIG. 9 is a diagram showing air gap magnetic flux density by a speaker magnetic circuit used in
Embodiment 3 of the present invention in comparison with a conventional example.
[0060]
FIG. 10 is another view showing the air-gap magnetic flux density by the speaker magnetic
circuit used in the third embodiment of the present invention in comparison with the
conventional example.
[0061]
FIG. 11 is a longitudinal sectional view showing a configuration of a speaker magnetic circuit
used in a fourth embodiment of the present invention.
[0062]
FIG. 12 is a longitudinal sectional view showing the configuration of another speaker magnetic
circuit used in a fourth embodiment of the present invention.
[0063]
FIG. 13 is a longitudinal sectional view showing the configuration of another speaker magnetic
circuit used in a fourth embodiment of the present invention.
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[0064]
FIG. 14 is a longitudinal sectional view showing the configuration of still another speaker
magnetic circuit used in a fourth embodiment of the present invention.
[0065]
FIG. 15 is a diagram showing the leakage magnetic flux density by four types of speaker
magnetic circuits used in Embodiment 4 of the present invention in comparison with a
comparative example.
[0066]
FIG. 16 is a longitudinal sectional view showing a configuration of a speaker magnetic circuit
used in a fifth embodiment of the present invention.
[0067]
FIG. 17 is a longitudinal sectional view showing the configuration of another speaker magnetic
circuit used in a fifth embodiment of the present invention.
[0068]
FIG. 18 is a diagram showing the leakage magnetic flux density of the two types of speaker
magnetic circuits used in the fifth embodiment of the present invention in comparison with a
comparative example.
[0069]
FIG. 19 is a longitudinal sectional view showing a configuration of a speaker magnetic circuit
used in a sixth embodiment of the present invention.
[0070]
FIG. 20 is a longitudinal sectional view showing the configuration of another speaker magnetic
circuit used in a sixth embodiment of the present invention.
[0071]
FIG. 21 is a longitudinal sectional view showing the configuration of still another speaker
magnetic circuit used in a sixth embodiment of the present invention.
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[0072]
FIG. 22 is a diagram showing air gap magnetic flux density by three types of speaker magnetic
circuits used in the sixth embodiment of the present invention in comparison with a comparative
example.
[0073]
FIG. 23 is a longitudinal sectional view showing a configuration of a speaker magnetic circuit
used in a seventh embodiment of the present invention.
[0074]
FIG. 24 is a longitudinal sectional view showing the configuration of another speaker magnetic
circuit used in a seventh embodiment of the present invention.
[0075]
FIG. 25 is a longitudinal sectional view showing the configuration of still another speaker
magnetic circuit used in a seventh embodiment of the present invention.
[0076]
FIG. 26 is a diagram showing air gap magnetic flux density by three types of speaker magnetic
circuits used in the seventh embodiment of the present invention in comparison with a
comparative example.
[0077]
FIG. 27 is a longitudinal sectional view showing a configuration of a speaker magnetic circuit
used in an eighth embodiment of the present invention.
[0078]
FIG. 28 is a longitudinal sectional view showing the configuration of another speaker magnetic
circuit used in an eighth embodiment of the present invention.
[0079]
FIG. 29 is a view showing air gap magnetic flux density by two types of speaker magnetic circuits
used in the eighth embodiment of the present invention in comparison with a comparative
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example.
[0080]
FIG. 30 is a cross-sectional view showing the configuration of a speaker magnetic circuit using a
conventional radially magnetized magnet.
[0081]
FIG. 31 is a cross-sectional view showing the configuration of another speaker magnetic circuit
using a conventional radially magnetized magnet.
[0082]
FIG. 32 is a cross-sectional view showing the configuration of another speaker magnetic circuit
using a conventional radially magnetized magnet.
[0083]
FIG. 33 is a cross-sectional view showing the configuration of still another speaker magnetic
circuit using a conventional radially magnetized magnet.
[0084]
Explanation of sign
[0085]
1 center pole, 2 yoke, 3, 3 'magnet, 4 top plate, 5 voice coil, 6 magnetic pole portion, 7 bobbin, 8
diaphragm, 9 damper, 10 bottom plate, 11 magnetic shield cover, 12 connecting member.
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