JP2015186103

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DESCRIPTION JP2015186103
Abstract: [Problem] To provide a bone conduction device capable of high output even in a small
size and light weight. SOLUTION: A bottomed cylindrical main body 2 made of a magnetic
material is opened at the upper end, a diaphragm 3 is provided across the opening 2a of the
cylindrical main body 2, and an inner bottom surface 2b of the cylindrical main body 2 stands.
An end member comprising a yoke 4 to be provided and a voice coil 6 disposed around the yoke
4 in the cylindrical main body 2 and comprising the magnet 41 and a magnetic material joined to
the upper end of the magnet 41 42 and composed. [Selected figure] Figure 2
Bone conduction device
[0001]
The present invention relates to a bone conduction device suitably used as a vibration driver for
a bone conduction speaker or a microphone, and more particularly to an efficient bone
conduction device capable of high output even in a small size and light weight.
[0002]
Conventionally, as a bone conduction device of this type, as disclosed in, for example, FIG. 1 of
Patent Document 1, an extension (30) (30 ') for supporting a diaphragm (70) is provided, and a
voice coil (40) is provided. And the central magnetic pole (yoke) (50), and the diaphragm (70) on
the upper part of which the iron piece (60) is fixed is extended between the extension parts (30)
and (30 '). A structure having a magnet (90) attached to the top is provided.
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This structure simplifies the assembly process and reduces costs, and because the magnet is
located not on the outer periphery of the voice coil but on the top of the diaphragm, the size and
the like of the voice coil can be changed relatively freely. The range of adjustment is broadened,
and the overall size and weight of the device can be reduced.
[0003]
However, according to the structure of the bone conduction device of Patent Document 1, there
is no magnet on the outer peripheral side of the voice coil, and the whole can be slimmed, and
the width and design of adjustment of characteristics of the voice coil and the magnet The degree
of freedom also increases, but there has been a certain limit to the increase in output.
[0004]
JP 2007-74693 A
[0005]
Therefore, in view of the above-described situation, the present invention is to provide a bone
conduction device capable of high output even with small size and light weight.
[0006]
As a result of intensive studies conducted by the inventor in view of the present situation, the
present inventors have studied the upper part where the magnet is on the opposite side to the
voice coil with respect to the diaphragm as the cause of the limitation of the output increase of
the bone conduction device. It has been found that this leads to magnetic leakage and leads to
inefficiency of the magnetic circuit, thus completing the present invention.
[0007]
That is, according to the present invention, a bottomed cylindrical main body made of a magnetic
material is opened at the upper end, a diaphragm which is provided across the opening of the
cylindrical main body, and the inner bottom surface of the cylindrical main body A yoke, and a
voice coil disposed around the yoke in the cylindrical main body, wherein the yoke is composed
of a magnet and an end member made of a magnetic material joined to the upper end of the
magnet; The bone conduction device was characterized.
[0008]
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Here, it is preferable that the cylindrical main body be provided with a peripheral wall which
surrounds the opening at the upper end over the entire circumference.
[0009]
Preferably, a plate made of a magnetic material or a second magnet is fixed to the lower surface
side of the diaphragm.
[0010]
According to the bone conduction device of the present invention as described above, since the
yoke is composed of the magnet and the end member made of the magnetic material joined to
the upper end of the magnet, the magnet is present on the outer periphery of the voice coil. In
addition to the function and effect of achieving slimming of the whole without increasing the
width of adjustment of characteristics and increasing the degree of freedom of design, the
magnet can be omitted from the diaphragm, and it is compact and the magnetic flux from the
magnet does not diverge The upper end of the upper end of the end member is made of magnetic
material, and from there, it is captured by the upper end of the peripheral wall of the cylindrical
main body made of magnetic material, and is guided again to the magnet of the yoke through the
cylindrical main body.
The direction of the magnetic flux is not limited, and the same applies to the reverse flow.
That is, according to the present invention, the flow of magnetic flux is compact, an efficient
magnetic circuit is formed, magnetic leakage to the outside is extremely small, and the efficiency
is high, and high output can be obtained even if it is small and lightweight. Is possible.
[0011]
In addition, since the cylindrical main body is provided with a peripheral wall that surrounds the
opening at the upper end over the entire circumference, most of the magnetic flux from the end
member covers the entire circumference of the opening. Are efficiently captured and guided to
the yoke through the tubular body.
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That is, an efficient magnetic circuit is formed in which the flow of the magnetic flux is uniform
and compact, and the magnetic leakage to the outside is extremely small, so that the efficiency is
higher, and a high output can be obtained even if it is small and lightweight. It becomes.
[0012]
Further, since a plate member or a second magnet made of a magnetic material is fixed to the
lower surface side of the diaphragm, the magnetic flux from the end member can be more
efficiently guided to the cylindrical main body and the yoke. High output and high efficiency.
[0013]
1 is a perspective view of a bone conduction device according to a representative embodiment of
the present invention.
Similarly, a longitudinal sectional view of a bone conduction device.
The same exploded perspective view.
The simulation result of the magnetic flux density distribution of Example 1. FIG.
[0014]
Next, an embodiment of the present invention will be described in detail with reference to the
attached drawings.
[0015]
The bone conduction device 1 according to the present invention, as shown in FIG. 1 to FIG. 3, is
opened at the upper end, and is extended to the bottomed cylindrical main body 2 made of
magnetic material and the opening 2a of the cylindrical main body 2 And the voice coil 6
disposed around the yoke 4 in the cylindrical main body 2, and the yoke 4 is The magnet 41 and
the end member 42 made of a magnetic material joined to the upper end of the magnet 41 are
constituted.
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[0016]
The cylindrical main body 2 is a bottomed case in which the yoke 4, the plate member 5 and the
voice coil 6 are disposed inside, and the inner cylindrical portion 20 formed of a magnetic
material and the outer covering portion 21 formed of a nonmagnetic material. And consists of.
Then, by providing the fixing portion for fixing the diaphragm 3 to the outer covering portion 21
of the nonmagnetic body and making the inner cylindrical portion 20 of the magnetic body into a
simple cylindrical body having no such complicated structure, The magnetic flux from the
magnet 41 of the yoke 4 can be uniformly and efficiently guided through the inner cylindrical
portion 20 without being disturbed.
That is, the degree of freedom in shape design can be kept high in the inner cylindrical portion
20 to be a magnetic circuit, and it is possible to make the shape and structure as simple as
possible without causing disturbance of the magnetic flux, making the flow of magnetic flux
uniform. It is possible to prevent magnetic leakage and further pursue efficiency and high output.
[0017]
The inner cylindrical portion 20 is a bottomed cylindrical body provided with a peripheral wall
24 extending over the entire circumference, which makes a part of the peripheral wall 2c, and is
formed by pressing a magnetic metal, for example, a stainless steel of SUS430. .
The position of the upper end of the peripheral wall 24 of the inner cylindrical portion 20 is
substantially the same height over the entire circumference.
From the upper surface of the plate 5 on the lower surface side of the diaphragm which receives
the magnetic flux emitted from the yoke end member 42, the magnetic flux tries to spread in all
directions around the circumference, but the inner side surrounds most of the circumference at
substantially the same height. The upper end portion of the peripheral wall 24 of the cylindrical
portion 20 can be efficiently captured, and the magnetic leakage to the outside can be extremely
reduced.
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[0018]
Further, the peripheral wall 24 has a substantially uniform thickness over the entire
circumference, and in the present example, at least the inner peripheral surface of the peripheral
wall 24 is a continuous curved surface without corners in a plan view viewed from the upper
side, particularly substantially circular (this example In this case, the cylindrical body is a true
circular shape, and there is no notch or hole on the entire surface of the peripheral wall 24, and
the uniform thickness and uniform height are provided over the entire circumference. Therefore,
the inner cylindrical portion 20 forms a uniform and efficient magnetic circuit in the
circumferential direction. It is also preferable to have a substantially elliptical shape in plan view.
However, although the uniformity is lowered, it may of course be a quadrangle or other
polygonal or irregular shape, and a notch or a hole may be formed in part of the peripheral wall.
[0019]
In the central portion of the bottom wall 25 of the inner cylindrical portion 20, a throughattached mounting hole 20c for fixing the yoke 4 (base member 40) is bored. Then, the
substantially cylindrical yoke 4 (base member 40) is fixed by caulking the bottom portion to the
mounting hole 20c. Of course, it may stand on bottom wall 25 by other fixing methods, such as
welding fixation. Further, instead of fixing the separately formed base member 40 as in this
example, the base member 40 may be integrally formed with the cylindrical main body 2 (inner
cylindrical portion 20) by shaving or casting.
[0020]
The outer covering portion 21 is provided on the outer surface side of the inner cylindrical
portion 20 and has a fixing portion 23 for fixing the diaphragm 3. Specifically, the same
bottomed cylindrical portion is insert-molded on the outer surface side of the inner cylindrical
portion 20 using a synthetic resin material, and a plurality of flanges are provided protrudingly
as the fixing portion 23 on the upper outer peripheral portion. The diaphragm 3 is bridged
between the upper surfaces of the flanges (fixing portions 23).
[0021]
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The formation of the outer covering portion 21 is performed in a state where the base member
40 of the yoke 4 is crimped to the bottom surface of the inner cylindrical portion 20 in advance
as described above. Therefore, the caulking portion of the base member 40 projecting downward
from the mounting hole 20c of the inner cylindrical portion 20 is also buried in the synthetic
resin constituting the outer covering portion 21, and the assembling strength of the yoke 4 is
improved.
[0022]
In this example, as in the case of the inner cylindrical portion 20, although it is a bottomed
cylindrical shape having a peripheral wall 26 covering the entire circumference that makes a part
of the peripheral wall 2c, it is not limited thereto. The one having a wall or the one having a
cylindrical shape may be coated only on the upper end side where the flange (fixing portion 23)
is formed. Since the outer covering portion 21 does not constitute a magnetic circuit, it does not
affect the reduction of magnetic leakage and the improvement of the efficiency even if the
peripheral wall 24 is the same as the peripheral wall 24 of the inner cylindrical portion 20.
Further, not limited to the insert molding, for example, a member formed into a cylindrical shape
separately from the synthetic resin as the outer covering portion 21 may be assembled to the
outside of the inner cylindrical portion 20.
[0023]
The diaphragm 3 has an annular frame portion 30 fixed by an attachment screw 7 to the upper
end portion of the cylindrical main body 2, specifically the upper surface of the flange (fixing
portion 23) of the outer covering portion 21; The vibrating portion 31 disposed inside the gap s1
via the gap s1, and the connecting portion 32 which connects the vibrating portion 31 so as to
be movable relative to the frame 30 in the axial direction (axial direction of the cylindrical main
body 2) And consists of. Further, a plate member 5 made of a magnetic material is fixed to the
lower surface of the vibrating portion 31.
[0024]
The height of the upper surface of the fixing portion 23 to which the frame portion 30 is fixed is
set to be the same as or higher than the upper end surface 22 of the inner cylindrical portion 20.
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Therefore, the diaphragm 3 is substantially flat. Preferably, the vibrating portion 31 is provided
so as to cover the opening 2 a of the cylindrical main body 2. The shape of the outer peripheral
edge facing the gap s1 of the vibrating portion 31 with the frame portion 30 is a perfect circular
shape substantially along the opening edge 22a of the inner cylindrical portion 20, but is not
limited thereto. The diaphragm 3 is made of a nonmagnetic material, for example, stainless steel
of SUS304. Therefore, although the diaphragm 3 does not constitute a magnetic circuit, the plate
material 5 fixed to the lower surface of the diaphragm 3 is surrounded by the peripheral wall 24
of the inner cylindrical portion 20 of the magnetic body. It is efficiently captured at the upper
end of the
[0025]
Of course, the diaphragm 3 may be made of a magnetic material such as SUS430 in the same
manner as the inner cylindrical portion 20. In this case, the plate 5 may be omitted. Since the
diaphragm 3 constitutes a magnetic circuit if the diaphragm 3 is a magnetic material, the shape
of the outer peripheral edge of the vibrating portion 31 is the opening edge 22a of the inner
cylindrical portion 20 (upper end edge of the peripheral wall 24 as in this example) By forming
the shape along the part), the flow of magnetic flux is smoothly formed from the outer peripheral
edge 31a to the opening edge 22a of the cylindrical main body 2, and the magnetic leakage can
be further suppressed.
[0026]
The vibration portion 31 is provided with a mounting hole 31b for attaching a vibration
transmission member (not shown), and when used as a bone conduction speaker, the vibration of
the vibration portion 31 is transmitted to the scalp or the like of a human body through the
vibration transmission member. As a result, even a deaf person with an abnormality in the
eardrum and earlobes in the skull of the human body can surely hear the sound if the cochlea
and the auditory nerve are normal.
[0027]
The yoke 4 is a substantially flat cylindrical base member 40 made of a magnetic material whose
bottom is crimped to the attachment hole 20c of the inner cylindrical portion 20, a substantially
flat cylindrical magnet 41 provided on the upper surface thereof, It is comprised from the end
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member 42 which similarly consists of a substantially flat cylindrical magnetic material provided
on the upper surface, and these are made into the state laminated ¦ stacked coaxially. Specifically,
the base member 40, the magnet 41, and the end member 42 are integrally assembled by the
core member 43 made of a magnetic material penetrating the central portion of the magnet 41.
[0028]
That is, a bottomed attachment hole 40a for erecting the core member 43 is bored in the upper
surface of the base member 40 in advance, and after the base member 40 is attached to the
cylindrical main body 2 by caulking, first of all, A core member 43 is inserted into and fixed to
the mounting hole 40a to be erected, and the magnet 41 and the end member 42 in which
through holes 41a and 42a are bored at the center of the core member 43 are sequentially
arranged. The core member 43 is inserted through the through holes 41a and 42a, mounted, and
assembled. Thus, the yoke 4 is efficiently assembled by the core member 43, and high strength
after assembly is maintained.
[0029]
Incidentally, the assembly structure using the core member 43 is not limited in this way, and it is
also preferable to assemble with the other fitting structure with high strength as well, and it may
be simply adhered. Furthermore, although the base member 40 and the magnet 41 which consist
of a magnetic material are separately comprised in this example, the base member 40 may be
abbreviate ¦ omitted and what fixed the magnet 41 directly to the bottom face of the cylindrical
main body 2 may be used.
[0030]
The plate member 5 has a flat cylindrical or cylindrical shape in a plan view and a substantially
circular (perfect circle) shape substantially similar to the inner peripheral surface of the inner
cylindrical portion 20, and the inner cylindrical shape of the lower surface 3 c of the diaphragm
3. It is fixed at a position (substantially central position of the vibrating portion 31) coaxial with
the portion 20, and the lower surface side is disposed to face the upper surface of the end
member 42 of the yoke 4 with a gap. With such a shape and arrangement, the yoke 4, the plate
member 5, and the inner cylindrical portion 20 constituting the magnetic circuit are all coaxially
arranged, and an efficient magnetic circuit in which the flow of the magnetic flux becomes
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uniform is formed.
[0031]
The plate 5 can be omitted. Further, as the shape thereof, in addition to the cylindrical shape and
the cylindrical shape, various shapes such as a triangular prism shape, a pentagonal prism shape
and the like can be adopted. In particular, if the diaphragm 3 itself is a magnetic body, the
necessity of providing the plate member 5 is low. Alternatively, the plate member 5 may be a
second magnet. In that case, the magnetic poles may be disposed so as to attract each other to
the magnet 41 of the yoke 4.
[0032]
The voice coil 6 is fixed on the outer peripheral surface of the yoke 4 or on the bottom surface of
the inner cylindrical portion 20 of the cylindrical main body 2. Both end portions of the coil wire
of the voice coil 6 are drawn out through the through holes 2 d of the bottom surface of the
cylindrical main body 2, and a sound signal or the like is input to the voice coil 6 from the
outside.
[0033]
Although the embodiments of the present invention have been described above, the present
invention is not limited to these examples, and it is needless to say that the present invention can
be practiced in various forms without departing from the scope of the present invention.
[0034]
Hereinafter, with respect to the model of the bone conduction device of Example 1 according to
the present invention, an analysis result of calculation of magnetic flux density distribution by
computer simulation will be described.
[0035]
The model of Example 1 was a bone conduction device (FIGS. 1 to 3) according to the present
invention.
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The diaphragm is made of SUS304 (spring steel) with an outer diameter of 20 mm and a
thickness of 0.7 mm, and the cylindrical main body (inner cylindrical portion) is made of SUS430
with an outer diameter of 14 mm, a height of 5.6 mm and a thickness of 1 mm. Cylindrical main
body (outside covering part), made of PPS with peripheral wall and bottom wall thickness of 1.5
mm, plate material of diaphragm lower surface, made of SUS430 with outer diameter of 7 mm
and thickness of 0.5 mm, base of yoke Made of SS400 outer diameter 4.5 mm, height 1.1 mm
excluding crimped parts, yoke magnet, N-35 material with outer diameter 4.5 mm, height
(thickness) 1.1 mm, The end member of the yoke is an SS400 product with an outer diameter of
4.5 mm and a height (thickness) of 1.1 mm, the core material of the yoke is an electromagnetic
steel plate 50A400, and the coil is a copper wire.
[0036]
The calculation of magnetic flux density distribution used simulation software "JMAG"
manufactured by JSOL Corporation.
The analysis result of the magnetic flux density distribution is shown in FIG. As can be seen from
FIG. 4, in the first embodiment, the magnetic flux from the magnet of the yoke guides the
cylindrical main body through the plate material, an efficient magnetic circuit is formed from the
cylindrical main body to the yoke, and the magnetic leakage is reduced.
[0037]
DESCRIPTION OF SYMBOLS 1 bone conduction device 2 cylindrical main body 2a opening 2b
inner bottom surface 2c peripheral wall 2d through hole 3 diaphragm 3c lower surface 4 yoke 5
plate 6 voice coil 7 mounting screw 20 inner cylindrical portion 20c mounting hole 21 outer
cover 22 upper end surface 22a Opening edge 23 Fixed portion 24 Peripheral wall 25 Bottom
wall 26 Peripheral wall 30 Frame portion 31 Vibration portion 31a Outer peripheral edge 31b
Mounting hole 32 Connecting portion 40 Base member 40a Mounting hole 41 Magnet 41a
Through hole 42 End member 43 Core member s1 Clearance
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