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DESCRIPTION JP2008034956

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DESCRIPTION JP2008034956
A magnetic circuit for a speaker device of radial type capable of reducing a product cost mainly.
The magnetic circuit has magnetism and is uniformly disposed around a center pole and a yoke
including a center pole formed in a columnar shape, and forms a magnetic gap between the
center pole and the yoke. A plurality of flat plate type magnets are provided, and each of the
magnets is magnetized in a direction parallel to the thickness direction and in a direction toward
the center pole to constitute a radial type magnetic circuit. As described above, since each of the
flat plate magnets is formed in a flat plate shape instead of an arc shape, machining of the
magnets is easy, and the number of steps for forming the magnet can be reduced. In addition,
since each of the flat type magnets is magnetized in the thickness direction, no special
magnetizing machine is required. Therefore, the number of steps for magnetizing the flat plate
type magnet can be reduced. As a result, the product cost of the magnetic circuit can be reduced.
[Selected figure] Figure 2
Magnetic circuit for speaker device and speaker device
[0001]
The present invention relates to the configuration of a magnetic circuit for a speaker device.
[0002]
Conventionally, a radial type speaker device capable of obtaining high magnetic efficiency by
providing an annular magnet magnetized in the radial direction and a yoke, and forming a
magnetic gap (air gap) between the magnet and the yoke. Magnetic circuits are known.
12-04-2019
1
[0003]
Patent Document 1 also describes an example of this type of magnetic circuit.
In the magnetic circuit described in Patent Document 1, the arc-shaped magnet forms a magnetic
gap with the center pole or the yoke, and the magnetic flux density of the magnet of the yoke or
the center pole opposed to the magnet via an air gap. Notches are provided at multiple sparse
locations.
Thus, it is assumed that the heat radiation effect and the like of the magnetic circuit can be
obtained.
[0004]
JP 2002-27591 A
[0005]
However, in the radial type magnetic circuit described above, there is a problem that a special
magnetizing machine is required to magnetize the annular magnet in the radial direction (magnet
radial direction), and the man-hour increases accordingly. The
[0006]
Further, in the magnetic circuit described in Patent Document 1 described above, in addition to
the above problems, it is necessary to form the magnet in an arc shape, but its processing is
difficult compared to the case where an annular magnet is formed. There is a problem that the
number of man-hours increases by that amount.
[0007]
Therefore, in the radial type magnetic circuit described above and the magnetic circuit described
in Patent Document 1, there is a problem that the product cost of the magnetic circuit increases
as the number of steps increases.
[0008]
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2
As problems to be solved by the present invention, the above-mentioned ones can be mentioned
as an example.
An object of the present invention is to mainly provide a magnetic circuit for a speaker device for
a radial type capable of reducing the production cost and a speaker device provided with the
magnetic circuit.
[0009]
The invention according to claim 1 is a magnetic circuit for a speaker device, comprising: a yoke
having magnetism and having a center pole formed in a columnar shape, and uniformly disposed
around the center pole; And a plurality of flat type magnets forming a magnetic gap with the
center pole, each of the flat type magnets being magnetized in a direction parallel to the
thickness direction and in a direction toward the center pole It is characterized by
[0010]
In one embodiment of the present invention, a magnetic circuit for a speaker device has
magnetism, and has a yoke having a center pole formed in a columnar shape, and is uniformly
disposed around the center pole, and the center pole And a plurality of flat plate-type magnets
forming a magnetic gap therebetween, each of the flat plate-type magnets being magnetized in
the direction parallel to the thickness direction and in the direction toward the center pole .
[0011]
The above-described magnetic circuit for a speaker device is magnetic, and is uniformly disposed
around the center pole and a yoke having a center pole formed in a columnar shape, and forms a
magnetic gap with the center pole. And a plurality of flat type magnets.
Each flat magnet is magnetized in a direction parallel to the thickness direction and in a direction
toward the center pole.
Here, the thickness direction of each of the flat plate-type magnets may be a direction
substantially orthogonal to the protruding direction of the center pole.
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[0012]
In a preferred embodiment, a magnetic first plate is preferably provided between each of the flat
type magnets and the center pole.
In addition, it is preferable that a second plate having magnetism is provided on the outer side of
each of the flat type magnets.
[0013]
Thus, the speaker device magnetic circuit constitutes a radial type magnetic circuit having a
plurality of flat plate type magnets.
And since each of this flat plate type magnet is formed in flat plate type shape instead of arc
shape like the above-mentioned prior art (comparative example), processing of a magnet is easy
compared with a comparative example, and The number of steps for forming the magnet can be
reduced.
Further, since each of the flat type magnets is magnetized in the thickness direction, a special
magnetizing machine is not required to magnetize each of the flat type magnets. Therefore,
compared with the above-described comparative example, it is possible to reduce the number of
steps for magnetizing the flat plate type magnet. Thus, since the number of processes can be
reduced, the product cost of the magnetic circuit can be reduced.
[0014]
Further, since this speaker device magnetic circuit constitutes a radial type magnetic circuit using
a plurality of flat plate type magnets, as in the comparative example, a radial type magnetic
circuit is constituted using an arc shaped magnet. Magnet efficiency is improved compared to
what is being done. This is because, in the comparative example, the magnets adjacent to each
other are bonded to each other, so that the magnetic flux is reduced at the bonded portion due to
the influence of the repulsive magnetic field, and the magnet efficiency is deteriorated. In the
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circuit, since a plurality of flat type magnets are uniformly arranged around the center pole, the
magnetic flux becomes uniform over the entire magnetic gap, and the magnet efficiency is
improved compared to the comparative example. . Therefore, according to the configuration of
the magnetic circuit for a speaker device, the material cost of the magnet can be lowered as
compared with the comparative example, and the weight reduction of the magnetic circuit can be
achieved.
[0015]
In one aspect of the above-described magnetic circuit for a speaker device, adjacent flat platetype magnets are not bonded to each other. Therefore, since no repulsive magnetic field is
generated at the boundary between adjacent flat plate magnets when assembling the magnetic
circuit for a speaker device, each of the magnets can be made into a magnetic circuit without
being affected by the repulsive magnetic field. It can be easily attached. Therefore, as compared
with the above-described comparative example, it is possible to improve the workability of the
assembling operation of the magnetic circuit for a speaker device.
[0016]
Moreover, in this aspect, the flat type magnets adjacent to each other are not bonded as
described above. Therefore, in the magnetic gap corresponding to the boundary portion of the
adjacent flat plate type magnets, the magnetic flux of one flat plate type magnet is added to the
magnetic flux of the other flat plate type magnet, so the magnetic flux becomes dense. That is, in
the magnetic gap corresponding to the area where the distance from the flat magnet to the
center pole is the largest, the magnetic flux becomes dense. On the other hand, in the magnetic
gap corresponding to the region where the distance from the flat plate type magnet to the center
pole is the shortest, there is only one flat plate type magnet, so compared to the above-mentioned
region where the magnetic flux becomes dense. Magnetic flux is sparse. Thereby, the magnetic
flux can be made uniform over the entire inside of the magnetic gap formed in the
circumferential direction of the center pole.
[0017]
In another embodiment of the present invention, a speaker device provided with the abovedescribed magnetic circuit for a speaker device can be configured.
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[0018]
Hereinafter, preferred embodiments of the present invention will be described with reference to
the drawings.
[0019]
[Configuration of Speaker Device] First, the configuration of a speaker device 100 having a
magnetic circuit 30 for a speaker device according to an embodiment of the present invention
will be described with reference to FIGS. 1 to 3.
[0020]
FIG. 1 shows a cross-sectional view of a speaker device 100 including a magnetic circuit 30 for a
speaker device according to an embodiment of the present invention, cut along a plane passing
through the central axis L1.
[0021]
The speaker device 100 mainly includes a magnetic circuit 30 having a yoke 1, a first plate 2, a
plurality of magnets 3, and a plurality of second plates 4, a frame 5, a voice coil bobbin 6, a voice
coil 7, a damper 8, And a vibration system member 31 having a diaphragm 9, an edge 10, and a
cap 11.
[0022]
(Configuration of Magnetic Circuit) Here, the configuration of the magnetic circuit 30 will be
described with reference to FIGS. 1 to 3.
[0023]
FIG. 2A shows an exploded perspective view of the magnetic circuit 30. FIG.
FIG. 2 (b) is a perspective view showing a configuration in a state where the magnetic circuit 30
shown in FIG. 2 (a) is assembled.
FIG. 3 shows a front view of the magnetic circuit 30 observed from the direction opposite to the
arrow Y1 direction of FIG.
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[0024]
The magnetic circuit constitutes a so-called radial magnetic circuit.
[0025]
The yoke 1 has magnetism and is formed so as to extend outward from the lower end portion of
the center pole 1a formed in a columnar shape (in this example, a hollow cylindrical shape) and
the outer peripheral wall of the center pole 1a. And the flange portion 1b.
The flange portion 1b has notches 1ba at positions near the boundary of the magnets 3 adjacent
to each other and near the boundary of the second plate 4 adjacent to each other.
[0026]
The first plate 2 is magnetic and formed in the shape of a rectangular parallelepiped including an
opening having a diameter larger than that of the center pole 1a.
The first plate 2 is mounted on the flange portion 1b so as to form a fixed gap between the inner
peripheral wall and the outer peripheral wall of the center pole 1a.
This gap is a magnetic gap 32 in which the magnetic flux of each of the magnets 3 described
later is concentrated.
[0027]
Each of the magnets 3 has a flat plate shape, is disposed at a position surrounding the center
pole 1a, and is further divided into four in the circumferential direction of the center pole 1a.
Attached to the outer wall of the
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Each of the magnets 3 is uniformly disposed around the center pole 1a, and forms a magnetic
gap 32 with the center pole 1a via the first plate 2.
Each of the magnets 3 is magnetized in a direction parallel to its thickness direction, as shown by
the arrow in FIG. 3, and in a direction toward the center pole 1a. Here, the thickness direction of
each of the magnets 3 is a direction substantially orthogonal to the projecting direction of the
center pole 1a (the arrow Y1 direction in FIG. 1). Moreover, as shown to the broken line area |
region E1 of FIG. 3, the flat type magnet 3 comrades to adjoin adjacently are not adhere |
attached.
[0028]
Each of the second plates 4 has magnetism and is formed in a circular arc, semicircular or bowllike cross-sectional shape. Each of the second plates 4 is attached to the outside of each of the
magnets 3.
[0029]
(Structure of Vibration System Member) The frame 5 has a bowl-like shape and a step-like crosssectional shape, and supports various components constituting the speaker device 100. The
frame 5 has a step-like shape in the vicinity of its central portion and has a step 5a to which an
outer peripheral portion of a damper 8 described later is attached. A magnetic circuit 30 is
mounted on the lower end of the frame 5.
[0030]
The voice coil bobbin 6 has a cylindrical shape and is disposed at a position covering the outer
peripheral wall of the center pole 1 a which is an element of the yoke 1.
[0031]
The voice coil 7 has a pair of plus and minus lead wires (not shown) and is wound around the
lower end of the outer peripheral wall of the voice coil bobbin 6.
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For this reason, the voice coil 7 is disposed in the magnetic gap 32. Here, the lead on the positive
side is an input wiring of the L (or R) channel signal, and the lead on the negative side is an input
wiring of the ground (GND: ground) signal. Each lead wire is electrically connected to a speaker
device terminal (not shown) provided at an appropriate position of the frame 5. The speaker
device terminal is also electrically connected to a pair of positive and negative output wires on
the amplifier side. As a result, a signal and power for one channel (hereinafter, also simply
referred to as "audio current") are input to the voice coil 7 from the amplifier side.
[0032]
The damper 8 has an annular shape and a plurality of concentric wave shapes (corrugations), and
elastically supports the voice coil bobbin 6. The inner peripheral edge portion of the damper 8 is
attached to the upper end portion of the outer peripheral wall of the voice coil bobbin 6, while
the outer peripheral portion of the damper 8 is attached on the step 5 a of the frame 5.
[0033]
The diaphragm 9 has a cone shape and has a function of emitting an acoustic wave according to
an input signal. The inner peripheral edge portion of the diaphragm 9 is attached to the upper
end portion of the outer peripheral wall of the voice coil bobbin 6.
[0034]
The edge 10 has an annular shape and an Ω-like cross-sectional shape, and has a function of
absorbing unnecessary vibrations and the like generated in the speaker device 100. The inner
peripheral edge of the edge 10 is attached to the outer peripheral edge of the diaphragm 9, while
the outer peripheral edge of the edge 9 is attached to the upper end of the frame 9.
[0035]
The cap 11 has a dome shape, and has a function of preventing dust and the like from intruding
into the inside of the speaker device 100. The cap 11 is disposed at a position covering the upper
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surface side of the voice coil bobbin 6 and is attached to the sound emitting surface of the
diaphragm 9.
[0036]
In the speaker device 100 having the above configuration, the audio current output from the
amplifier side is input to the voice coil 7 through the speaker device terminal and the pair of
positive and negative lead wires of the voice coil 7. As a result, based on Fleming's left-hand rule,
a driving force is generated in the voice coil 7 in the magnetic gap 32 to vibrate the diaphragm 9
in the direction of the central axis L1 of the speaker device 100. Thereby, sound waves are
emitted in the direction of the arrow Y1 through the diaphragm 9.
[0037]
Next, advantageous points of the magnetic circuit according to the embodiment of the present
invention in comparison with the comparative example will be described.
[0038]
First, the configuration of the magnetic circuit 35 according to the comparative example will be
described with reference to FIG.
In the following, the same elements as those of the above-described embodiment will be denoted
by the same reference numerals, and the description thereof will be omitted.
[0039]
A magnetic circuit 35 according to the comparative example includes a yoke 1 having a center
pole 1a and a flange portion 1b, a plurality of magnets 3x having an arc-like, semicircular or
bowl-like cross-sectional shape, and a plate 45 having an annular shape. , And constitute a socalled radial type magnetic circuit.
[0040]
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Each of the magnets 3x is magnetized in the thickness direction and in the radial direction
toward the center pole 1a as shown by the arrow in the figure, and is disposed at a position
surrounding the center pole 1a, and also in the circumferential direction of the center pole 1a. Is
divided into four.
The end portions of the magnets 3x adjacent to each other are bonded to each other, and a
magnetic gap 32 is formed between each of the magnets 3x and the center pole 1a. The plate 45
has an annular shape and is disposed at a position covering the respective magnets 3x.
[0041]
In the comparative example having such a configuration, it is necessary to form the magnet in an
arc shape, but its processing is difficult as compared with the case where an annular magnet is
formed, and the number of man-hours increases accordingly. was there. Further, in the case of
the comparative example, a special magnetizing machine is required to magnetize the arc-shaped
magnet 3x in the radial direction (magnet radial direction), and the number of steps for
magnetizing increases accordingly. There was a problem. Therefore, in the comparative example,
there is a problem that the product cost of the magnetic circuit 35 is increased with the increase
of the number of steps.
[0042]
Further, in the comparative example, when attention is paid to one pair of adjacent magnets 3x,
the end of one magnet 3x and the end of the other magnet 3x bonded to the end are not shown
in the drawings. The polarities of the north pole and the south pole are reversed. Therefore, when
the adjacent magnets 3x are adhered to each other at the time of assembly of the magnetic
circuit 35, the magnets 3x of the both repel each other, and under the influence of the repulsive
magnetic field, the assembling operation of the magnetic circuit 35 is performed. There was a
problem that work efficiency was bad.
[0043]
Further, in the comparative example, as described above, since the ends of the magnets 3x
adjacent to each other are opposite in polarity, the magnetic flux cancels each other in the
magnetic gap 32 corresponding to the boundary portion of the adjacent magnets 3x. The
problem was that the
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[0044]
About this point, the result of experiment is shown in the graph of FIG.
FIG. 5 is a graph showing the relationship between the magnetic flux (T) and the angle (θ) of the
magnetic circuit 35 according to the comparative example and the magnetic circuit 30 according
to the present embodiment. In FIG. 5, the vertical axis represents the magnitude of the magnetic
flux (T), and the horizontal axis represents the angle (°) in the circumferential direction of the
magnetic circuit. That is, when the position of the magnetic circuit 30 or 35 on the right side of
the paper surface is 0 ° (or 360 °) in FIGS. 3 and 4, the angle (°) is an angle θ measured
counterclockwise from that position. It shows. Further, in FIG. 5, a graph g1 indicated by a solid
line indicates a graph of the magnetic circuit 30 of the present embodiment, and a graph g2
indicated by an alternate long and short dash line indicates a graph of the magnetic circuit 35
according to the comparative example.
[0045]
From the graph of FIG. 5, in the comparative example, the decrease in magnetic flux is observed
in the vicinity of 0 ° (= 360 °), 90 °, 180 °, and 270 °. This corresponds to 0 ° (= 360 °),
90 °, 180 °, and 270 ° at the boundary where the polarities of the end portions of the
magnets 3x adjacent to each other in the comparative example are reversed. This is because in
the magnetic gap 32 corresponding to the boundary portion, the magnetic flux cancels out and
the magnetic flux decreases. Therefore, in the comparative example, there is a problem that the
magnetic flux can not be formed uniformly in the circumferential direction of the magnetic gap
32.
[0046]
In order to solve the problems described above, it is effective to adopt the configuration of the
magnetic circuit 30 according to the present embodiment.
[0047]
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That is, the magnetic circuit 30 according to the present embodiment has magnetism and is
uniformly disposed around the center pole 1a, the yoke 1 having the center pole 1a formed in a
columnar shape, and the center pole 1a And a plurality of flat plate-shaped magnets 3 forming a
magnetic gap 32 between each of the flat plate-shaped magnets 3 as shown by the arrows in FIG.
It is magnetized in the direction toward the pole 1a.
Here, the thickness direction of each of the flat plate-shaped magnets 3 is a direction
substantially orthogonal to the projecting direction of the center pole 1a.
[0048]
Thereby, this magnetic circuit constitutes a radial type magnetic circuit having a plurality of flat
plate type magnets 3. And since each of this flat plate type magnet 3 is formed in flat plate type
shape instead of circular arc shape like a comparative example, processing of magnet 3 is easy
compared with a comparative example, and magnet 3 Man-hours for forming can be reduced.
Further, since each of the flat-plate-type magnets 3 is magnetized in the thickness direction, no
special magnetizing machine is required to magnetize each of the flat-plate-type magnets 3.
Therefore, compared with the above-described comparative example, the number of steps for
magnetizing the flat plate type magnet 3 can be reduced. Thus, since the number of processes
can be reduced, the product cost of the magnetic circuit 30 can be reduced.
[0049]
Further, in the magnetic circuit 30 according to the present embodiment, as shown by the broken
line area E1 in FIG. 3, the flat plate type magnets 3 adjacent to each other are not bonded.
Therefore, since no repulsive magnetic field is generated at the boundary between adjacent flat
plate-type magnets 3 when assembling the magnetic circuit 30, each of the magnets 3 can be
used as a first plate without being affected by the repulsive magnetic field. It can be easily
attached to the outer wall of 2. Therefore, the workability of the assembling operation of the
magnetic circuit 30 can be improved as compared with the comparative example.
[0050]
Further, as described above, the flat type magnets 3 adjacent to each other are not bonded.
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Therefore, in the magnetic gap 32 corresponding to the boundary portion (broken line area E1)
of the adjacent flat plate type magnet 3, the magnetic flux of the other flat plate type magnet 3 is
added to the magnetic flux of one flat type magnet 3. Therefore, the magnetic flux becomes
dense. That is, the magnetic flux becomes dense in the magnetic gap 32 corresponding to the
broken line area E1 where the distance from the flat magnet 3 to the center pole 1a is the largest.
On the other hand, since only one corresponding flat plate magnet 3 exists in the magnetic gap
32 corresponding to the dashed line area E2 where the distance from the flat magnet 3 to the
center pole 1a is the shortest, it corresponds to the dashed line area E1. As compared with the
magnetic flux generated in the magnetic gap 32, the magnetic flux becomes sparse. Thereby, in
the present embodiment, as shown by the graph g1 in FIG. 5, the magnetic flux can be made
uniform over the entire inside of the magnetic gap 32 formed in the circumferential direction of
the center pole 1a.
[0051]
Further, in the present embodiment, since the radial type magnetic circuit is configured using the
plurality of flat plate type magnets 3, the radial type magnetic circuit is configured using the arcshaped magnet 3x as in the comparative example. The magnet efficiency is better than that of
This is because, in the comparative example, the magnets adjacent to each other are adhered to
each other, so that the magnetic flux is lowered due to the above-mentioned reason and the
magnet efficiency is deteriorated in the adhered portion, but in the present embodiment, the
above-mentioned reason Also, since the plurality of flat type magnets are uniformly arranged
around the center pole, the magnetic flux becomes uniform over the entire inside of the magnetic
gap 32, and the magnet efficiency is improved compared to the comparative example. It is for.
Here, those in which a radial type magnetic circuit is configured using annular magnets (other
comparative examples), the comparative example, and the present example are formed in the
magnetic gap under the same conditions. As a result of comparing the usage of magnets required
to equalize the magnitude of the magnetic flux density, 36.2 (g) of magnets are required in the
other comparative examples, and the magnets are in the comparative example. It was found that
44.7 (g) is required, and in this example, 33.8 (g) of magnet is required. In addition, "the same
conditions" means the case where structures other than a magnet are substantially the same
structure in each magnetic circuit of another comparative example, a comparative example, and a
present Example.
[0052]
From the above experimental results, when magnetic circuits capable of obtaining the same
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performance in the other examples, comparative examples and the present example are used, the
present example is compared with the other comparative examples and the comparative
examples. It is understood that the usage of magnets can be reduced the most. Therefore, in the
present embodiment, the material cost of the magnet can be lowered as compared with the other
comparative examples and the comparative examples, and the weight reduction of the magnetic
circuit 30 can be achieved.
[0053]
Further, in the present embodiment, portions of the flange portion 1b corresponding to the
vicinity of the boundary of the adjacent magnets 3 and the vicinity of the boundary of the
adjacent second plate 4 (that is, the flange portion 1b corresponding to the broken line area E1)
Since the notch portion 1ba is provided in the part (1), the following becomes possible. That is, in
the present embodiment, when focusing on the magnets 3 adjacent to each other, the polarities
of one magnet 3 and the other magnet 3 are opposite to each other. Therefore, in the boundary
portion (broken line area E1) of the magnets 3 adjacent to each other, the magnetic flux of the
one magnet 3 and the magnetic flux of the other magnet 3 cancel each other, and the magnetic
flux is easily reduced. However, in the present embodiment, since the notch portion 1ba is
provided in the flange portion 1b corresponding to the broken line area E1, a short circuit of the
magnetic flux hardly occurs in the portion of the magnetic circuit 30 corresponding to the
broken line area E1. It is possible to suppress the decrease.
[0054]
[Modifications] The present invention is characterized in that the flat plate type magnet 3 is
applied to the radial type magnetic circuit 30, so in the magnetic circuit 30, the shapes of
components other than the flat type magnet 3; There is no limitation on the size and the like, and
those components can be variously modified. Further, in the present invention, the magnet 3 only
needs to have a flat plate shape, and the cross sectional shape of the magnet 3 is not limited.
Hereinafter, configurations of magnetic circuits according to various modifications will be
described with reference to FIGS. 6 and 7. In the following, the same elements as those of the
above-described embodiment are denoted by the same reference numerals, and the description
thereof is omitted.
[0055]
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FIG. 6A is a perspective view showing the configuration of the magnetic circuit 30 w according to
the first modification. FIG. 6B is a perspective view showing a configuration of a magnetic circuit
30x according to the second modification. FIG. 7A is a perspective view showing the
configuration of the magnetic circuit 30y according to the third modification. FIG. 7B is a
perspective view showing the configuration of the magnetic circuit 30z according to the fourth
modification.
[0056]
Comparing the magnetic circuit 30 w of the first modification with the magnetic circuit 30
according to the above-described embodiment, in the first modification, the notch 1 b is formed
in the flange 1 b corresponding to the boundary between adjacent flat type magnets 3. The point
which is not provided is different from the embodiment described above, and the other
configuration is the same as the embodiment described above. For this reason, in the first
modification, although the magnetic flux is slightly reduced at the portion of the magnetic circuit
corresponding to the boundary portion of the adjacent flat plate-type magnets 3, on the other
hand, it is cut into the yoke 1 The product cost of the yoke 1 can be reduced compared to the
above-described embodiment by the absence of the notch 1ba.
[0057]
Further, comparing the magnetic circuit 30x of the modification 2 with the magnetic circuit 30
according to the above-described embodiment, in the above-described embodiment, the second
plate 4 has an arc shape (蒲 鉾 shape or semicircular shape). While the sectional shape is formed,
in the second modification, the second plate 4x is formed in a flat plate shape. As a result, the
second plate 4x of the modification 2 becomes easier to process as compared with the second
plate 4 of the above-described embodiment, and the part cost of the second plate 4x can be
reduced accordingly. Further, in the second modification, the flange portion 1b is formed in a
rectangular shape so as to conform to the shape of the rectangular second plate 4x, and
corresponds to the boundary portion of the magnets 3 adjacent to each other. The notch 1ba is
provided in the flange 1b. As a result, it is possible to suppress the reduction of the magnetic flux
at the portion of the magnetic circuit corresponding to the boundary portion between the
adjacent flat plate-type magnets 3.
[0058]
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Further, comparing the magnetic circuit 30y of the third modification with the magnetic circuit
30 according to the above-described embodiment, in the above-described embodiment, the
second plate 4 has a circular arc shape (蒲 鉾 shape or semicircular shape). While the sectional
shape is formed, in the third modification, the second plate 4y is formed in an annular shape. As
a result, the second plate 4y of the modification 3 becomes easier to process as compared to the
second plate 4 of the above-described embodiment, and the part cost of the second plate 4y can
be reduced accordingly. In the third modification, in order to match the magnet 3 with the shape
of the second plate 4y, the size of the magnet 3 is slightly smaller than that of the above
embodiment.
[0059]
Further, when the magnetic circuit 30z of the modification 4 is compared with the magnetic
circuit 30 according to the above-described embodiment, in the above-described embodiment,
each of the flat plate-shaped magnets 3 has a rectangular cross-sectional shape. In the fourth
modification, each of the flat plate-shaped magnets 3z has a trapezoidal cross-sectional shape.
And in the modification 4, the said flat type | mold magnet 3z adjacent to each other is adhere |
attached. With this configuration, in the fourth modification, the area of the magnet 3z
surrounding the center pole 1a is increased as compared with the above-described embodiment
and the first to third modifications, so that more magnetic flux is generated in the magnetic gap
32. It is possible to obtain In the fourth modification, a second plate 4z having an opening 4za
matching the shape of the flat plate-shaped magnet 3z is disposed outside each magnet 3z.
[0060]
FIG. 1 is a cross-sectional view of a speaker device 100 including a magnetic circuit according to
an embodiment of the present invention. They are a perspective view and an exploded
perspective view of a magnetic circuit concerning this example. It is a front view of the magnetic
circuit concerning a present Example. It is a front view of the magnetic circuit concerning a
comparative example. It is a graph which shows the relationship between the magnitude | size of
the magnetic flux in the magnetic circuit of a comparative example and the magnetic circuit of a
present Example, and the angle of the circumferential direction of a magnetic circuit. FIG. 10 is a
perspective view of a magnetic circuit according to Modifications 1 and 2; FIG. 18 is a
perspective view of a magnetic circuit according to Modification 3 and Modification 4;
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Explanation of sign
[0061]
1 yoke 1a center pole 1b flange portion 2 1st plate 3 magnet 4 2nd plate 30 magnetic circuit 32
magnetic gap 100 speaker device
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