JP2009159035

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DESCRIPTION JP2009159035
An electromagnetic transducer for an acoustic radiation device is provided which effectively
prevents sound leakage caused by the expansion and contraction vibration of a giant
magnetostrictive element. An electromagnetic conversion unit (1) is joined to a handle (2) via a
buffer member (3). When the electromagnetic conversion unit 1 is not pressed against the
external vibrator, that is, when no sound is generated, the buffer member 3 forms a gap between
the partition 19 on the electromagnetic conversion unit 1 side and the partition 29 on the handle
2 side. They do not touch each other. The stretching vibration generated by the giant
magnetostrictive elements 151 and 152 is effectively absorbed because the handle 2 and the
electromagnetic conversion unit 1 are joined via the buffer member 3 and the buffer member 3
is organic. Therefore, transmission of the stretching vibration from the cover 8 to the second
exterior body 21 can be suitably suppressed, so that sound leakage can be effectively prevented.
[Selected figure] Figure 3
Electromagnetic converter for acoustic radiation device
[0001]
The present invention relates to an electromagnetic transducer for an acoustic radiation device
using a giant magnetostrictive element.
[0002]
The giant magnetostrictive element is an element having a property of stretching as the applied
magnetic field becomes stronger.
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Although giant magnetostrictive elements are used in products of various industrial fields, one of
them is an electromagnetic conversion device for an acoustic radiation device.
[0003]
The electromagnetic conversion device generates stretching vibration in the giant
magnetostrictive element based on the signal supplied to the coil, and presses the transmission
member directly or indirectly in contact with the stretchable end of the giant magnetostrictive
element against the external vibrator or the like. , To transmit the stretching vibration to the
external vibrating body. For example, Patent Document 1 discloses an electromagnetic
conversion device for an acoustic radiation device whose acoustic characteristics are mainly
improved.
[0004]
An acoustic radiation device generates sound by vibrating the above-mentioned external vibrator
based on a signal. There is no restriction ¦ limiting in particular as an external vibrating body, It
can comprise using metal, glass, wood, a synthetic resin, or those combination materials. Also,
the shape thereof may be any shape such as a flat plate shape, a block shape and the like.
Specific examples include outdoor advertising boards, indoor advertising boards, glass windows
of cars, tables, TV boxes and the like.
[0005]
In order to effectively generate sound, it is necessary to firmly press the electromagnetic
transducer against the external vibrator. Therefore, in order to do this manually, the
electromagnetic conversion device must be provided with a handle.
[0006]
However, expansion and contraction vibration generated by the electromagnetic conversion
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device is transmitted to the handle, and sound is generated by vibrating the handle. This sound
leakage is not a problem because it is wiped out due to the difference in volume when the
electromagnetic transducer is pressed against the external vibrator to generate sound, but
otherwise it is an unnecessary sound. It becomes a problem. JP, 2007-158911, A
[0007]
An object of the present invention is to provide an electromagnetic conversion device for an
acoustic radiation device in which sound leakage generated due to the stretching vibration of the
giant magnetostrictive element is effectively prevented.
[0008]
In order to solve the problems described above, an electromagnetic transducer for an acoustic
radiation device according to the present invention includes an electromagnetic transducer, a
handle, and a buffer member.
The electromagnetic conversion unit includes an exterior body, a coil, a super magnetostrictive
element, an expansion / contraction transmission member, a permanent magnet, and a first
partition wall. The exterior body has an internal space, and the coil, the super magnetostrictive
element, the expansion / contraction transmission member, and the permanent magnet are
accommodated in the internal space of the exterior body.
[0009]
The coil is excited by an externally supplied signal, and applies an alternating magnetic field to
the giant magnetostrictive element based on the excitation. One end side of the expansion /
contraction transmission member is connected to the first end of the giant magnetostrictive
element, and the other end side is exposed to the outside through an opening provided at the tip
of the exterior body.
[0010]
The permanent magnet applies a magnetic bias to the giant magnetostrictive element, and the
first permanent magnet disposed on the first end side of the giant magnetostrictive element; and
the second end side of the giant magnetostrictive element And a second permanent magnet
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disposed on the
[0011]
According to this configuration, the sound distortion can be reduced and the sound quality can
be improved by making the entire surface magnetic flux of the first permanent magnet and the
second permanent magnet different from each other.
[0012]
The first partition is connected to the second end of the giant magnetostrictive element, and is
fixed to the sheath so as to separate the inner space of the sheath from the handle.
[0013]
The configuration described so far can be found in the prior art, but the characterizing portion of
the present invention is that the buffer member is provided in addition to the handle described
next being provided as a separate member from the electromagnetic conversion unit. It is in.
That is, the handle includes a second partition arranged to face the first partition, and is joined to
the electromagnetic conversion unit through the buffer member.
The buffer member is made of an elastic material of organic material, and is provided between
the electromagnetic conversion unit and the handle to form a gap between the first partition and
the second partition.
[0014]
According to this configuration, when the electromagnetic conversion unit is not pressed against
the external vibrating body, that is, when the sound is not generated, the buffer member forms a
gap between the first partition and the second partition. They don't touch each other.
Further, the stretching vibration generated by the giant magnetostrictive element is effectively
absorbed because the handle and the electromagnetic conversion unit are joined via the buffer
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member and the buffer member is organic. Therefore, since it can suppress suitably that
expansion-contraction vibration transmits the said handle from the said exterior body, a sound
leak can be prevented effectively.
[0015]
On the other hand, when the electromagnetic conversion unit is pressed against the external
vibrator to generate sound, the buffer member is compressed by pressure, and temporarily the
first partition and the second partition contact with each other to cause sound leakage. However,
this is not a problem because it is scraped by the sound as described above. Furthermore, since
the buffer member is an elastic material, pressure is transmitted from the handle to the
electromagnetic conversion unit by the elastic force, so that the expansion / contraction
transmission member is firmly pressed against the external vibrating member, so that sound can
be suitably generated. .
[0016]
As described above, according to the present invention, it is possible to provide an
electromagnetic transducer for an acoustic radiation device in which sound leakage generated
due to the stretching vibration of the giant magnetostrictive element is effectively prevented.
[0017]
FIG. 1 is a side view of the electromagnetic conversion device for an acoustic radiation device
according to the present invention at the time of disassembly.
The electromagnetic transducer for the acoustic radiation device includes the electromagnetic
conversion unit 1, the handle 2, and the buffer member 3, and further includes the cover
member 4 and the bonding member 5.
[0018]
The electromagnetic conversion unit 1 stretches and vibrates the super magnetostrictive element
according to a signal supplied from the outside, and vibrates the external vibrating body via the
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stretch transmitting member 11. The electromagnetic conversion unit 1 has a substantially
cylindrical shape, and an expansion and contraction transmission member 11 protrudes from the
tip thereof. Also, the above signal includes the entire audio frequency band, including the voice
band.
[0019]
The handle 2 is joined to the electromagnetic conversion unit 1 via the buffer member 3. The
handle 2 has a substantially cylindrical shape whose central portion is constricted so as to be
easily held by hand, and a fixing portion 22 in which a screw groove is formed is provided on the
outer periphery on the tip side. The screw groove is screwed with the screw groove formed in the
second inner circumferential surface 52 of the joint member 5.
[0020]
The cover member 4 covers the electromagnetic conversion unit 1. Therefore, since the inside of
the electromagnetic conversion unit 1 is doubly covered by the exterior body 8 (see the symbol 8
in FIG. 3) of the electromagnetic conversion unit 1 and the cover member 4, sound leakage from
the inside of the electromagnetic conversion unit 1 Decreases.
[0021]
The cover member 4 has a substantially cylindrical shape and has an insertion hole 41 formed to
conform to the shape of the electromagnetic conversion unit 1. The insertion hole 41 is thinner
at its tip, and the expansion transmission member 11 is exposed from the opening at the tip so as
to be pressed against the external vibrator. Further, at the rear end of the cover member 4, a
band portion 42 having an outer diameter larger than that of other portions is formed.
[0022]
The joining member 5 joins the electromagnetic conversion unit 1 and the handle 2. The bonding
member 5 has a substantially annular shape, and inside thereof, a first inner circumferential
surface 51 having a larger diameter than the inner circumferential surface on the distal end side
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and a larger diameter than the first inner circumferential surface 51 It has an inner
circumferential surface 52 of two. The diameter of the first inner circumferential surface 51 is
substantially the same as the diameter of the band portion 42 of the cover member 4. Further, as
described above, the second inner circumferential surface 52 is formed with a screw groove
screwed with the fixing portion 22 of the handle 2.
[0023]
FIG. 2 is a side view of an electromagnetic transducer for an acoustic radiation device. The
electromagnetic conversion unit 1 is inserted into the insertion hole 41 of the cover member 4,
and the cover member 4 is further inserted into the opening of the joining member 5 until the
band 42 matches the first inner circumferential surface 51. There is. The second inner
circumferential surface 52 is in threaded engagement with the fixing portion 22 of the handle 2.
The opening of the joining member 5 and the insertion hole 41 of the cover member 4 are both
thinner at the tip, so the electromagnetic conversion unit 1 is combined with these to provide the
handle 2 with the handle 2. It is joined.
[0024]
Next, the details of the handle 2 will be described. The handle 2 includes a cover 21 which is a
main body, a partition 29 fixed to the front end side, and a lid 23 attached to the rear end side by
means such as a screw groove. The cover 21 has an internal space, and accommodates the circuit
board 28 on which the signal amplification unit 27 and the audio jack 26 are mounted, and the
battery storage room 24.
[0025]
The input terminal of the audio jack 26 is exposed to the outside from an opening 25 provided in
the cover 21 and connected to an external sound source such as a CD player via a commercially
available audio cable. The signal amplification unit 27 includes an element such as an amplifier,
amplifies a signal input from an external sound source, and outputs the amplified signal to the
electromagnetic conversion unit 1. A sound source may be provided inside the cover 21 instead
of the external sound source. In this case, for example, it is necessary to provide an insertion slot
for storing a commercially available memory card storing music data, and a reading means such
as a CPU for reading the music data.
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[0026]
Further, in order to output the amplified signal to the electromagnetic conversion unit 1, the
signal amplification unit 27 includes an opening 292 provided in the peripheral portion of the
partition wall 29 of the end face of the cover 21 and the partition wall 19 on the electromagnetic
conversion unit 1 side ( It connects with the lead wire of the coil 7 (refer FIG. 3) in the
electromagnetic conversion part 1 via the clearance gap part of the exterior body 8 (refer FIG. 3).
However, the connection method is not limited to this, and other methods such as connection by
terminals can also be used.
[0027]
Electric power is supplied to the circuit board 28 from the battery stored in the battery storage
room 24. The battery can be inserted into the battery storage room 24 by opening the lid 23
described above. Note that instead of the battery, power may be supplied from the outside
through a cable from a general outlet.
[0028]
The partition wall 29 is formed of a material such as iron or brass and has a substantially disc
shape and is disposed to face the partition wall 19 on the electromagnetic conversion unit 1 side,
and separates the internal space of the cover 21 from the electromagnetic conversion unit 1 Is
fixed to the cover 21.
[0029]
According to such a configuration, the configuration of the signal amplification unit 27 and the
like necessary for the generation of sound can be efficiently arranged, so that the
electromagnetic conversion device for an acoustic radiation device can be miniaturized.
[0030]
Next, the details of the electromagnetic conversion unit 1 will be described.
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FIG. 3 shows a cross section of the electromagnetic conversion unit 1 in a state of being joined to
the handle 2.
The electromagnetic conversion unit 1 includes an exterior body 8, a coil 7, super
magnetostrictive elements 151 and 152, an expansion / contraction transmission member 11, a
first permanent magnet 14, a second permanent magnet 17, and a partition wall 19. .
Furthermore, the electromagnetic conversion unit 1 includes a pressurizing member 12, a first
magnetic yoke 13, a second magnetic yoke 18, a third permanent magnet 16, and a bobbin 6.
[0031]
The exterior body 8 has an internal space, and the coil 7, the giant magnetostrictive element 151,
152, the expansion / contraction transmission member 11, the first to third permanent magnets
14, 17, 16, and the first and second magnetic yokes 13. , 18, the pressurizing member 12 and
the bobbin 6 are accommodated. Thus, the entire component is protected by the exterior body 8.
[0032]
The sheath 8 may be made of any of a magnetic material, a nonmagnetic conductive material, a
ceramic or a plastic material. When the package 8 is made of a magnetic material, the leakage
flux is reduced and the magnetic efficiency is increased. In the case of a conductive magnetic
material, for example, a metallic magnetic material, although a high shielding effect can be
obtained, it may cause problems of deterioration of frequency characteristics and heat generation
due to eddy currents. When configured with nonmagnetic conductive materials, the problem of
eddy current losses still remains. When made of a ceramic or plastic material, the problem of
heat generation does not occur, but the leakage flux increases and the magnetic efficiency
decreases. Therefore, the constituent material of the exterior body 8 needs to be selected
appropriately by comparing the advantages and disadvantages described above.
[0033]
The exterior body 8 is provided with a front end side opening 81 at the front end, and a rear end
side opening 82 at the rear end. A partition 19 is fixed to the rear end side opening 82 so as to
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separate the internal space of the exterior body 8 from the handle 2. An adhesive etc. can be
used as a fixing means. In addition, an expansion and contraction transmission member 11
protrudes from the distal end side opening 81.
[0034]
The giant magnetostrictive elements 151 and 152 have a first end 1521 and a second end 1511,
and have a leading end giant magnetostrictive element 152 with the first end 1521 and a trailing
end giant magnetostrictive element 151 with the second end 1511. Divided into The partition
wall 19 is connected to the second end 1511 of the giant magnetostrictive element 151 via the
second magnetic yoke 18 and the second permanent magnet 17. Therefore, when the
magnetostrictive elements 151 and 152 stretch and vibrate in a state in which the
electromagnetic conversion unit 1 is pressed against the external vibrator, the position of the
second end 1511 in the axial direction (see dashed dotted line in the figure) is not displaced. The
axial position of the first end 1521 is displaced.
[0035]
In addition, a third permanent magnet 16 is provided between the front end side super
magnetostrictive element 152 and the rear end side super magnetostrictive element 151. This is
to equalize the distribution of the bias magnetic field inside the giant magnetostrictive elements
151 and 152 and reduce acoustic distortion. In addition, since the two giant magnetostrictive
elements 151 and 152 are arranged in series and used, the length of one giant magnetostrictive
element is shortened, which also has the purpose of avoiding a breakage accident of the giant
magnetostrictive element.
[0036]
The bobbin 6 and the coil 7 are disposed around the giant magnetostrictive element 15. The coil
7 is excited by a signal input from the signal amplification unit 27 and applies an alternating
magnetic field to the giant magnetostrictive element 15 based on the excitation. The
magnetostrictive element 15 is driven to expand and contract in the axial direction by the
alternating magnetic field.
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[0037]
The coil 7 is wound around the winding space of the bobbin 6. The winding method may be
arbitrary, but split winding results have been obtained. As the split winding, first, it is wound to
half the coil winding thickness in the winding space between the collars 61-62, then transferred
to the winding space between the collars 62-63, and so on to half the coil winding thickness as
well. It is possible to adopt a method of repeating and completing the winding operation. The
divided winding method may be a method of further dividing the winding space and the winding
thickness. By dividing and winding the coil 7, the sound becomes tight and the sound becomes
good.
[0038]
Inside the cylindrical portion 64 of the bobbin 6, the giant magnetostrictive elements 151, 152
and the third permanent magnet 16 are inserted. The super magnetostrictive elements 151 and
152 are formed in a cylindrical shape using, for example, a material having a central composition
of Tb0.34-Dy0.66-Fe1.90 in accordance with the cylindrical portion 64.
[0039]
The first permanent magnet 14 and the second permanent magnet 17 apply a magnetic bias to
the giant magnetostrictive elements 151 and 152. The first permanent magnet 14 is disposed on
the first end side 1521 of the giant magnetostrictive element 152, while the second permanent
magnet 17 is disposed on the first end side 1511 of the giant magnetostrictive element 151. It is
desirable that the entire surface magnetic flux of the first permanent magnet 14 and the second
permanent magnet 17 be different from each other. According to this configuration, the acoustic
distortion is reduced and the sound quality is improved.
[0040]
The first and second magnetic yokes 13 and 18 are disposed adjacent to the first and second
permanent magnets 14 and 17, respectively. The first and second magnetic yokes 13 and 18 are
made of ferrite, iron or the like, and coil leakage can be reduced to increase the volume and to
reduce acoustic distortion.
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[0041]
The expansion / contraction transmission member 11 is connected at one end to the first end
1521 of the distal end side super magnetostrictive element 152 via the first permanent magnet
14, the first magnetic yoke 13 and the pressure application member 12, and the other end is at
the distal end. It is exposed to the outside through the side opening 81. In order to transmit the
stretching vibration, the material of the stretching transmission member 11 is preferably hard,
and is made of iron, brass, hard plastic or the like.
[0042]
FIG. 4 shows the expansion / contraction transmission member 11, the pressure application
member 12, and the first magnetic yoke 13. The expansion / contraction transmission member
11 has a substantially disc shape, and a flange portion 111 is provided around the periphery. A
recess 112 having a circular cross section is formed on the rear end side of the stretch
transmission member 11.
[0043]
The pressurizing member 12 has a substantially cylindrical shape, has a diameter smaller than
that of the recess 112, and has a height higher than that of the recess 112. Therefore, the
pressurizing member 12 is accommodated in the recess 112 in a state of projecting in the axial
direction from the recess 112.
[0044]
The pressure member 12 is made of an elastic material such as silicone rubber, and urges the
expansion / contraction transmission member 11 in the direction of the tip of the exterior body 8
and also the first magnetic yoke 13 and the first permanent magnet. The giant magnetostrictive
elements 151 and 152 are urged in the direction of the bulkhead 19 through 14 and the like.
The elastic transmission member 11 biased by the pressure member 12 is positioned in the axial
direction when the collar portion 111 abuts on the edge of the distal end side opening 81.
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[0045]
Furthermore, the first magnetic yoke 13 is substantially cylindrical and has a diameter larger
than that of the recess 112. For this reason, when the expansion transmission member 11 is not
pressed against the external vibrating body, a gap is generated between the flange portion 111 of
the expansion transmission member 11 and the first magnetic yoke 13 by the pressure member
12. Since this gap is longer than the length of the maximum expansion of the giant
magnetostrictive elements 151, 152, the vibrating first magnetic yoke 13 does not contact the
stretch transmission member 11.
[0046]
The electromagnetic conversion unit 1 is joined to the handle 2 via the buffer member 3 in a
state in which the partition wall 19 is opposed to the partition wall 29 on the handle 2 side. FIG.
5 shows the partition 19 on the electromagnetic conversion unit 1 side, the buffer member 3,
and the partition 29 on the handle 2 side.
[0047]
The partition 19 is formed of a material such as iron or brass and has a substantially semicircular
shape. When the partition 19 is formed of magnetic material such as iron, it functions as a
magnetic shield. In this case, the opposing partitions 29 need to be formed of a nonmagnetic
material such as brass so as not to attract each other. In addition, since the material or shape of
the partition 19 influences the sound quality which an apparatus emits, it is necessary to
determine suitably according to a design.
[0048]
In addition, since the partition wall 19 has a substantially semicircular disk shape, a gap is
formed between the partition wall 19 and the exterior body 8. As described above, the lead wire
of the coil 7 is drawn out from the gap and connected to the signal amplification unit 27.
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[0049]
The buffer member 3 has an annular shape, has an outer diameter substantially the same as that
of the partition wall 19 on the electromagnetic conversion unit 1 side, and has an inner diameter
larger than that of the partition wall 29 on the handle 2 side. Furthermore, the thickness of the
buffer member 3 is greater than the thickness of the partition 29 on the handle 2 side and the
plastic projecting portion (see reference numeral 291 in FIG. 3) adjacent thereto. In addition, the
buffer member 3 is not limited to the shape as illustrated, for example, in order to pass the lead
wire of the coil 7 mentioned above, the shape which provided the through-hole or the notch in a
part of annular ring, or The part may be cut into a C shape.
[0050]
A characteristic part of the present invention is that, in addition to the handle 2 being provided
as a separate member from the electromagnetic conversion unit 1, the buffer member 3 is
provided. That is, the buffer member 3 is made of an organic elastic material such as silicone
rubber or a combination of a metal spring and the like, and further has the shape and size as
described above. A gap is formed between the handle 2 and the partition wall 19 on the
electromagnetic conversion unit 1 side and the partition wall 29 on the handle 2 side.
[0051]
According to this configuration, as shown in FIG. 3, when the electromagnetic conversion unit 1
is not pressed against the external vibrating body, that is, when no sound is generated, the
partition 19 on the electromagnetic conversion unit 1 side and the partition on the handle 2 side
Since the buffer members 3 form a gap, 29 does not contact each other. The stretching vibration
generated by the giant magnetostrictive elements 151 and 152 is effectively absorbed because
the handle 2 and the electromagnetic conversion unit 1 are joined via the buffer member 3 and
the buffer member 3 is organic. Therefore, since it can suppress suitably that expansioncontraction vibration transmits to the handle 2 from the exterior body 8, a sound leak can be
prevented effectively.
[0052]
Furthermore, in this case, as described above, since the vibrating first magnetic yoke 13 does not
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come in contact with the expansion / contraction transmission member 11, the expansion /
contraction vibration is also absorbed by the pressure member 12 and the above sound leakage
is Preventive effect is improved.
[0053]
On the other hand, as shown in FIG. 6, when the electromagnetic conversion unit 1 is pressed
against the external vibrating body P to generate sound, the buffer member 3 is compressed by
pressure, and temporarily the partition 29 on the handle 2 side and the partition on the
electromagnetic conversion unit 1 side Even if the sound 19 is in contact with each other and a
sound leak occurs, it does not matter because it is scraped by the sound as described above.
Furthermore, since the buffer member 3 is an elastic material and transmits pressure from the
handle 2 to the electromagnetic conversion unit 1 by the elastic force, the expansion /
contraction transmission member 11 can be pressed firmly against the external vibrator P to
generate sound preferably. it can. At this time, in order to transmit the pressure more effectively,
it is desirable that the buffer member 3 be compressed and the partition wall 29 on the handle 2
side and the partition wall 19 on the electromagnetic conversion unit 1 contact each other.
[0054]
Further, in this case, the compression transmitting member 11 is directly connected to the first
end 1521 of the giant magnetostrictive element 152 by the compression of the pressure
applying member 12 which receives the pressure from the front end side, that is, it vibrates. The
first magnetic yoke 13 contacts the expansion / contraction transmission member 11. Therefore,
the stretching vibration is effectively transmitted to the stretching transmission member 11,
which contributes to the generation of a suitable sound.
[0055]
FIG. 7 shows a state in which the electromagnetic conversion unit 1 is inclined and pressed
against the external vibrator P. In this case, the pressure-applying member 12 is biased to one
side and compressed, so that the elastic transmission member 11 can be brought into contact
with the vibrating first magnetic yoke 13 while being maintained in a substantially horizontal
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posture. Therefore, it is also possible to preferably generate sound. In the case of a slight
inclination, the electromagnetic conversion unit 1 tilts while maintaining the state shown in FIG.
[0056]
Although the contents of the present invention have been specifically described with reference to
the preferred embodiments, it is obvious that those skilled in the art can adopt various
modifications based on the basic technical concept and the teaching of the present invention. It
is. Therefore, the shape, material, and the like of each part can be appropriately changed
according to the design. Also, for example, the first and second magnetic yokes 13 and 18 may
be omitted, or the single giant magnetostrictive element may be realized without separating the
giant magnetostrictive elements 151 and 152.
[0057]
It is a side view at the time of decomposition ¦ disassembly of the electromagnetic transducer for
acoustic radiation devices which concerns on this invention. It is a side view of an
electromagnetic transducer for acoustic radiation devices. It is sectional drawing of the
electromagnetic conversion part of the state joined with the handle. The expansion-contraction
transmission member, the pressurization member, and the 2nd magnetic yoke are shown. The
partition wall by the side of an electromagnetic conversion part, the buffer member, and the
partition by the side of a handle are shown. The state which pressed the electromagnetic
conversion part on the external vibrating body is shown. The state which inclined the
electromagnetic conversion part and pressed on the external vibrating body is shown.
Explanation of sign
[0058]
DESCRIPTION OF SYMBOLS 1 electromagnetic conversion part 2 handle 3 buffer member 7 coil
11 expansion-contraction transmission member 12 pressure member 14, 16, 18 permanent
magnet 19, 29 partition 8 exterior body 27 signal amplification part 151, 152 super
magnetostrictive element
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