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DESCRIPTION JP2009005197
To provide a novel vibration device utilizing a magnetostrictive element. A vibration device (300)
includes a magnetostrictive device (30), a main body (40), and a vibration transmission
mechanism (310). The magnetostrictive device 30 includes a super magnetostrictive element 1
that expands and contracts according to a magnetic field, a coil 4 and a bias magnet 2 that
generate a magnetic field, and a housing 8 that holds them at predetermined positions. The main
body 40 has sufficient hardness and mass to suppress vibration of the end on the main body 40
side of the giant magnetostrictive element 1. The vibration transfer mechanism 310 comprises a
tube 302 and a wire 304 slidably disposed within the tube 302. One end of the wire 304 is
connected to the giant magnetostrictive element 1. [Selected figure] Figure 10
Vibration device
[0001]
The present invention relates to a vibrating device, and more particularly to a vibrating device
that generates vibration using a magnetostrictive element.
[0002]
Some magnetic materials distort in response to changes in the external magnetic field.
In addition, when stress is applied to such a magnetic material to deform it, the magnetic
characteristics change according to the stress. These phenomena are called "magnetostriction". In
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recent years, materials showing displacement of 50 to 100 times the displacement amount of the
conventionally known magnetostrictive element have been discovered, and they are called "super
magnetostrictive elements".
[0003]
When an alternating magnetic field is applied to the magnetostrictive element, vibrations having
a frequency equal to that of the alternating magnetic field can be generated. It is expected that
the magnetostrictive element is applied to a bone conduction type headphone, a hearing aid or
the like by utilizing such a phenomenon, for example (see, for example, Patent Documents 1 and
2). JP 2001-258095 A JP 2004-266307 A
[0004]
The present inventor has conceived of a completely new vibration device utilizing a
magnetostrictive element by utilizing the characteristics of the magnetostrictive element that the
displacement of vibration is large and the generated stress is large.
[0005]
The present invention has been made in view of these circumstances, and an object thereof is to
provide a novel vibration device using a magnetostrictive element.
[0006]
In order to solve the above problems, the vibration device according to an aspect of the present
invention holds a magnetostrictive element that expands and contracts according to a magnetic
field, a magnetic field generating unit that generates a magnetic field, and a magnetostrictive
element and a magnetic field generating unit at predetermined positions. A housing and a
vibration transmission mechanism for remotely transmitting the vibration of the magnetostrictive
element.
[0007]
According to this aspect, it is possible to configure a vibration device capable of remotely
transmitting the vibration of the magnetostrictive element.
[0008]
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The displacement of the end on the external member side of the magnetostrictive element may
be suppressed by the external member by connecting the housing to the external member of the
vibration device.
[0009]
The mass of the external member may be available to suppress displacement of the external
member side end of the magnetostrictive element by connecting the housing to the external
member of the vibration device.
[0010]
The vibration transmission mechanism may include a tube and a wire slidably disposed in the
tube, and one end of the wire may be coupled to the magnetostrictive element.
In this case, a vibration transmission mechanism can be configured to transmit the vibration
through the wire.
[0011]
The vibration transmission mechanism includes a tube, a lid that respectively closes both ends of
the tube, and a liquid filled in a space formed by the tube and the lid. The lid on one end side of
the tube is a magnetostrictive element. It may be linked.
In this case, a vibration transmission mechanism can be configured to transmit vibration through
the liquid.
[0012]
The liquid may be filled in the space formed by the tube and the lid with a predetermined
pressure applied.
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In this case, the vibration can be efficiently transmitted.
Also, the tube may be formed by an elastic member.
In this case, the vibration transmission mechanism can be made deformable.
[0013]
It is to be noted that any combination of the above-described components, and a conversion of
the expression of the present invention among methods, apparatuses, systems, and the like are
also effective as an aspect of the present invention.
[0014]
According to the present invention, it is possible to provide a novel vibration device using a
magnetostrictive element.
[0015]
First, the underlying technology of the magnetostrictive device for driving the magnetostrictive
element will be described.
Subsequently, a vibration device using the magnetostrictive device will be described.
[0016]
Prerequisite Technology FIG. 1 shows the configuration of a conventional magnetostrictive
device.
The conventional magnetostrictive device 90 includes a magnetostrictive element 91, a coil 92, a
biasing magnet 93, a cap 94, and a case 95.
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The magnetostrictive element 91 has a substantially cylindrical shape, and is displaced so as to
expand and contract in the height direction according to the magnetic field generated by the coil
92 and the bias magnet 93. The magnetostrictive element 91 is disposed substantially at the
center of the case 95 so that the height direction thereof coincides with the depth direction of
the substantially cylindrical case 95. The coil 92 is provided around the magnetostrictive element
91, and generates a magnetic field around the magnetostrictive element 91 by a current input
from an external drive device. The bias magnet 93 is provided to fixedly apply a magnetic field of
a predetermined strength as a bias around the magnetostrictive element 91. The cap 94 has a
substantially disk shape, and is provided to seal the case 95 including the magnetostrictive
element 91, the coil 92, and the bias magnet 93 inside. An engagement groove 96 is formed in
the upper portion of the side wall portion of the case 95, and the locking portion 97 of the cap
94 is locked there, and the cap 94 and the case 95 are fixed to each other. At this time, the
magnetostrictive element 91 is pressed from above and below by the cap 94 and the case 95,
and is given a predetermined prestress.
[0017]
When an alternating current is applied to the coil 92, an alternating magnetic field is generated
around the coil 92, whereby the magnetostrictive element 91 expands and contracts in the axial
direction. The expansion and contraction of the magnetostrictive element 91 vibrates the cap 94,
and the vibration is transmitted to the outside through the cap 94. For example, when the
magnetostrictive device 90 shown in FIG. 1 is used as a headphone, the cap 94 is pressed in
contact with the vicinity of the ear, and the vibration generated by the magnetostrictive element
91 is transmitted to the head through the cap 94. The cap 94 is formed to have a greater
elasticity than the bottom of the case 95. Thus, the vibration of the magnetostrictive element 91
is prevented from being absorbed by the bottom of the case 95, and efficiently transmitted to the
object, for example, the head of the user via the cap 94.
[0018]
FIG. 2 shows the characteristics of the giant magnetostrictive material and the piezoelectric
material. Super magnetostrictive materials such as terbium, dysprosium and iron (TbDyFe) have
the following superior properties as compared to piezoelectric materials such as lead zirconate
titanate (PZT: PbZrO3-PbTiO3) . First, since the giant magnetostrictive material has a large
generated stress and a large amount of displacement, it is possible to efficiently transmit the
vibration generated by the giant magnetostrictive element to the outside. In addition, since the
drive voltage is low, the power consumption can be small. Moreover, since the Curie temperature
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is high, it can be used even at high temperatures. Further, since the vibration is caused by the
magnetic field, the drive part is not in contact with the power supply, and the safety is excellent.
[0019]
Furthermore, since the giant magnetostrictive material has a large generated stress, it can
reliably transmit low frequency vibrations with high energy to the outside, and its response
speed is fast, so it reliably follows the high frequency input signal as well. Can be generated.
Therefore, flat characteristics are realized in a wide frequency band. This is particularly
convenient for use in headphones, speakers and the like. In headphones and the like using a
conventional piezoelectric material, only sounds up to about 5 to 20 kHz can be generated, but
by using a giant magnetostrictive material, sounds of 30 kHz or more can be generated. The limit
of the audible range of human beings is said to be around 20 kHz, but there is also a theory that
it senses ultrasound. Also, research on hearing by bone conduction, not hearing through the
tympanic membrane, has not progressed so much, and the sense of listening to the sound in the
ultrasound region by bone conduction is an unknown world. In view of the development of
equipment capable of recording sound in the ultrasonic range in recent years, the present
inventor faithfully reproduces the sound in the ultrasonic range, not the piezoelectric material
which can not generate high-frequency sounds. We wanted to develop headphones and speakers
using possible giant magnetostrictive materials.
[0020]
However, the present inventor has come to recognize that the following problems exist in order
to exhibit the excellent frequency characteristics of the giant magnetostrictive material. FIGS. 3A
and 3B schematically show how the magnetostrictive element vibrates. As shown in FIG. 3A,
when one end (hereinafter referred to as fixed end ) 98 of the magnetostrictive element 91 is
fixed, the magnetostrictive element 91 is referred to as the opposite end (hereinafter referred to
as output end ). The vibration when the magnetostrictive element 91 expands and contracts
is efficiently transmitted from the output end 99 to the outside. However, as shown in FIG. 3B,
when the member supporting the fixed end 98 of the magnetostrictive element 91 has elasticity
or is light in weight, the fixed end 98 vibrates. The amount of displacement or stress of vibration
transmitted from the output end 99 to the outside is attenuated by the amount. In the
magnetostrictive device 90 shown in FIG. 1, when the cap 94 is pressed against the object and
the vibration of the magnetostrictive element 91 is transmitted to the object, the reaction of the
cap 94 pressing the object causes a reaction of the magnetostrictive element 91. A force is
generated by which the fixed end 98 pushes the bottom of the case 95. At this time, as shown in
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FIG. 3B, if the case 95 does not have a sufficient inertia mass, the vibration at the output end 99
is attenuated and the vibration of the magnetostrictive element 91 is not sufficiently transmitted
to the object . This phenomenon is particularly noticeable in the low frequency band where
vibration energy is large. For example, when the magnetostriction device 90 is used for
headphones, it becomes difficult to hear sound in the bass region.
[0021]
The inventor recognizes such a problem, and in order to prevent deterioration of the frequency
characteristic of the magnetostrictive element 91 in a wide frequency band, a member with
which the fixed end 98 of the magnetostrictive element 91 abuts, for example, magnetostriction
in FIG. It has been conceived that in the device 90 the case 95 needs to have sufficient inertial
mass and hardness. Such a problem is a problem unique to the magnetostrictive element having
a larger generated stress than the piezoelectric element, and it is considered that the developer of
the sound transmission device using the piezoelectric element did not even recognize the
problem. In addition, it is recognized from the present inventors' desire to realize a voice
transmission device capable of faithfully reproducing all sounds in the human audible range
without allowing compromise even in a difficult-to-hear range. It can be said that it is a challenge.
As described later, according to the experiments of the present inventor, it is preferable that the
movable mass be about 13.8 times or more, in order to drive efficiently in a wide frequency
band, when using the super magnetostrictive device as a vibration generating device. It is known
that it is necessary to provide an inertial mass of 21 times or more, more preferably 69 times or
more on the fixed end 98 side of the magnetostrictive element 91.
[0022]
FIG. 4 shows the configuration of a magnetostrictive device improved in consideration of the
above problems. The magnetostrictive device 20 mainly includes the giant magnetostrictive
element 1, the bias magnet 2 (the bias upper magnet 2a and the bias lower magnet 2b), the
bobbin 3, the coil 4, the lead wires 5a and 5b, the vibrating rod 6, and the prestress cap 7a, a
case 7b, and an elastic member (string wound spring) 9 are included.
[0023]
The giant magnetostrictive element 1 is used as a vibration conversion element for converting a
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signal obtained by converting a voice into vibration, and has a substantially cylindrical outer
shape, and has a bias upper magnet 2a on the top and a bias on the bottom. The lower magnets
2b are disposed respectively. The super magnetostrictive element 1 is accommodated in the case
7b in a state of being held between the upper biasing magnet 2a and the lower biasing magnet
2b, and a magnetic field generated by the upper biasing magnet 2a and the lower biasing magnet
2b. Is set as a bias magnetic field (the bias magnetic field constantly penetrates the super
magnetostrictive element 1). At the same time, the super magnetostrictive element 1 is pressed
against the upper surface of the vibrating rod 6 by receiving the elastic force of the elastic
member 9 while the bottom surface is supported by the case 7b in a state housed inside the case
7b. So-called pre-stress is set to be applied constantly. The super magnetostrictive element 1
responds to the input electric signal by receiving the variable magnetic field by the coil 4
disposed in the periphery in a state where the bias magnetic field and the prestress are
constantly given as described above. Generate vibration.
[0024]
The coil 4 is formed by winding a conductor wire around a central barrel of a bobbin 3 made of,
for example, a material such as a glass substrate polycarbonate as a winding axis. When an
electrical signal is input to the conductor wire through the lead wire, the coil 4 generates a
magnetic field correspondingly. When the variable magnetic field emitted from the coil 4
penetrates the giant magnetostrictive element 1, the giant magnetostrictive element 1 expands
and contracts in response to the strength of the variable magnetic field, and this is output as
vibration.
[0025]
One end of the vibrating rod 6 is mechanically connected to the giant magnetostrictive element 1
via the bias upper magnet 2a, and the vibration output from the giant magnetostrictive element 1
is transmitted from the other end to the outside. The vibrating rod 6 is provided with a flange
portion 61. The flange portion 61 receives an urging force from the elastic member 9 and is
pressed against the bias upper magnet 2a. The pressing force is applied to the giant
magnetostrictive element 1 via the bias upper magnet 2a. Further, the flange portion 61 and the
elastic member 9 prevent the whole vibration rod 6 from falling out of the case 7 b and the
prestress cap 7 a.
[0026]
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The case 7b accommodates the giant magnetostrictive element 1, the bias upper magnet 2a, the
bias lower magnet 2b, the bobbin 3, the coil 4, the vibrating rod 6, and the elastic member 9 in
the predetermined state. The so-called container (or body). The prestress cap 7a is fixed to the
case 7b by a screw mechanism, welding, caulking, resin hardening, or the like. When the
prestressing cap 7a is fixed to the case 7b, the super magnetostrictive element is prestressed
through the elastic member 9. By prestressing the giant magnetostrictive element 1, the
conversion efficiency between the electric signal and the vibration can be improved. It is
desirable that the prestress cap 7a and the case 7b be made of a magnetic material in order to
prevent the magnetic field in the inside from leaking to the outside and in order to more
effectively generate the magnetic field in the inside.
[0027]
FIG. 5 shows a configuration of a headphone which is an example of an electronic device
provided with the magnetostrictive device 20 as a vibration generating device. The headphone
100 includes a main body 110, a magnetostrictive device 20, and a vibration pad 28. The main
body 110 includes a circuit 29 for transmitting an electrical signal input from an external
reproduction device or the like to the coil of the magnetostrictive device 20. The vibrating pad
28 is attached to the vibrating rod 6 of the magnetostrictive device 20, and transmits the
vibration transmitted from the vibrating rod 6 to the skull near the user's ear. The user can
recognize the vibration transmitted from the front surface of the vibration pad 28 as voice by
bone conduction. The inventor made a prototype of the bone conduction type headphone 100
shown in FIG. 5, and confirmed that the wide sound range from bass to treble was faithfully
reproduced, and excellent acoustic characteristics were realized.
[0028]
Thus, although the magnetostriction device for efficiently generating vibrations in a wide
frequency band could be realized, on the other hand, the inventor uses the magnetostriction
device as a headphone, a hearing aid, a speaker of a mobile phone terminal, etc. It was also
recognized as a challenge that in the case of use, further downsizing and weight reduction of the
device were necessary. For products that are preferred to be small and lightweight, such as
headphones and cell phones, it has already been proven in the market that small differences in
size and weight have a significant impact on product sales. It is. Even though they have superior
characteristics to similar similar products, it is possible that the slightly larger or heavier weight
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of the preceding products may contribute to the decline in the consumer's willingness to
purchase. The inventors of the present invention have also recognized that this is proved also
from the fact that headphones using a piezoelectric element are commercialized prior to a
magnetostrictive element having excellent performance.
[0029]
Since the giant magnetostrictive element 1 has a columnar shape and is displaced in the height
direction, it is necessary to connect movable parts in series in the height direction of the
magnetostrictive element. In addition, since it is necessary to provide the giant magnetostrictive
element 1 having a certain height in order to give the required vibration to the object, there is a
limit in reducing the size in the height direction. Therefore, in order to reduce the size and weight
of the magnetostrictive device 20, it is necessary to reduce the size and weight of the case 7b and
the prestress cap 7a which occupy a considerable proportion of the total weight of the
magnetostrictive device 20. However, also in the case 7b, as described above, in order to
maintain the characteristics in the low frequency region, it is necessary to have a certain amount
of inertial mass. The present inventor has conceived of a technique for meeting such
contradictory demands while repeating various experiments and repeating trial and error.
[0030]
FIG. 6 shows the configuration of the magnetostrictive device according to the base technology.
The magnetostrictive device 30 includes a housing 8 in place of the prestress cap 7a and the
case 7b, as compared with the configuration of the magnetostrictive device 20 shown in FIG. The
housing 8 includes a screw portion 81 which is an example of a connection mechanism for
attaching the magnetostrictive device 30 to the main body of the electronic device in which the
magnetostrictive device 30 is provided. That is, each component of the magnetostrictive device
30 is attached to the main body of the electronic device by the screw portion 81 in a state of
being accommodated in the housing 8. The housing 8 is a yoke made of a soft iron plate or the
like for adjusting the magnetic circuit of the magnetic field generated by the bias magnet 2 as the
magnetic field generating means, the coil 4 and the lead wires 5a and 5b. Including. A closed
magnetic circuit is formed in the housing 8 by the yoke, and the magnetic field is shut off so as
not to leak to the outside.
[0031]
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FIG. 7 schematically shows the configuration of an electronic device provided with the
magnetostrictive device 30 shown in FIG. The main body 40 of the electronic device 50 includes
a screw portion 41 which is an example of a connection mechanism for attaching the
magnetostrictive device 30. The magnetostrictive device 30 is attached to the main body 40 by
screwing the screw portion 81 of the magnetostrictive device 30 and the screw portion 41 of the
main body 40. The connection mechanism may also connect the magnetostrictive device 30 and
the main body 40 by welding, caulking, resin hardening or the like. The surface on the main body
40 side of the housing 8 is open, and when the magnetostrictive device 30 is attached to the
main body 40, the biasing lower magnet 2b directly abuts on the main body 40. At this time, a
protrusion 42 is provided at a position where the lower bias magnet 2b of the main body 40
abuts, and tightening the screw causes the super magnetostrictive element 1 to be pressed from
the protrusion 42 via the lower bias magnet 2b. A predetermined prestress is applied to the giant
magnetostrictive element 1. Further, the lead wires 5 a and 5 b are connected to the circuit 49 of
the main body 40, and the electric signal input from the circuit 49 is transmitted to the coil 4.
[0032]
In the magnetostrictive device 20 shown in FIG. 4, the case 7 b has a function of supporting the
fixed end of the giant magnetostrictive element 1. However, in the magnetostrictive device 30
shown in FIGS. The main body 40 of the electronic device 50 includes a configuration such as a
circuit for inputting an electric signal. That is, the housing 8 is provided to accommodate the
configurations of the giant magnetostrictive element 1, the coil 4, the biasing magnet 2, the
elastic member 9 and the like, and has a function of supporting the fixed end of the giant
magnetostrictive element 1 or a giant magnetostrictive element. 1 does not bear the function of
applying prestress. By connecting the housing 8 to the main body 40, the mass of the main body
40 becomes available to suppress the displacement of the fixed end of the giant magnetostrictive
element, and the main body 40 suppresses the displacement of the fixed end of the giant
magnetostrictive element Ru. As a result, since the displacement of the fixed end of the super
magnetostrictive element can be suppressed by the member outside the magnetostrictive device
30, it is not necessary to provide the magnetostrictive device 30 with a member having a large
inertial mass. Furthermore, since the prestress cap for applying prestress to the giant
magnetostrictive element 1 can also be omitted, the magnetostriction device 30 can be
miniaturized and reduced in weight, and consequently, the entire electronic device 50 can be
miniaturized and reduced in weight. Can be
[0033]
Moreover, in the conventional magnetostrictive device, a magnetostrictive device assembled
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including the case and the prestress cap was first present, and it was necessary to incorporate
the magnetostrictive device into an electronic device etc. However, in the magnetostrictive device
30, the main body 40 is sufficient As long as it has such a mass and hardness, it can be attached
to any main body 40, so that an electronic device using the magnetostrictive device 30 can be
designed flexibly.
[0034]
In the conventional magnetostrictive device 90 shown in FIG. 1, as long as a mechanism for
applying prestress to the magnetostrictive element 91 is necessary, the mechanism is implicit in
the idea that it is natural to provide the mechanism in the magnetostrictive device 90. It can be
said that it was bound.
Also in the magnetostrictive device 20 shown in FIG. 4, a mechanism for supporting vibration of
the fixed end of the giant magnetostrictive element 1 is required, and the mechanism is provided
in the magnetostrictive device 20. And since the magnetostrictive devices 90 and 20 can not be
reduced in size and weight because they can not break away from the idea, this is fundamentally
impeding the spread of the magnetostrictive element far surpassing the piezoelectric element in
terms of performance. It was a factor.
[0035]
In Patent Document 2 (Japanese Patent Application Laid-Open No. 2004-266307), a counter
mass using the mass of a receiving circuit, a battery, and a case is provided in a housing of a
speaker unit, and a vibrating element is extended / contracted driven by a drive coil. There is
disclosed a technique for efficiently transmitting the generated vibration to the diaphragm on the
other end side. However, there is no change in providing a counter mass inside the speaker unit,
and it can not be said that the speaker unit is reduced in weight. Furthermore, since the large
counter mass is provided on the fixed end side of the magnetostrictive element, the speaker unit
has a stick shape that is long in the vibration direction of the vibrating element, and it can not be
said that the speaker unit is miniaturized.
[0036]
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The inventor of the present invention aims to change the idea in order to reduce the weight and
size of the magnetostrictive device, in particular to miniaturize the vibration direction of the
vibrating element, and the main body 40 of the electronic device 50 applies prestress to the giant
magnetostrictive element 1 And, it has been realized that it may function as a member that
suppresses the vibration of the fixed end of the giant magnetostrictive element 1. As a result, the
magnetostrictive device 30 is free from the constraint that it must have an inertial mass
sufficient to suppress the vibration of the fixed end of the giant magnetostrictive element 1, and
the size and weight can be greatly reduced. It became. Furthermore, it becomes possible to omit a
part of the member for applying prestress by sandwiching the giant magnetostrictive element 1
from above and below, and the miniaturization of the giant magnetostrictive element 1 in the
vibration direction succeeded. This means that both the maintenance of the frequency
characteristics and the contradictory demands of miniaturization and weight reduction have been
satisfied. Therefore, it can be said that the present invention is a ground-breaking invention that
overcomes the problem that has hindered the commercialization of magnetostrictive elements,
which are excellent in characteristics, and is a breakthrough for the widespread use of devices
using magnetostrictive elements.
[0037]
As described above, in order to suppress the vibration at the fixed end of the magnetostrictive
element and efficiently transmit the vibration at the output end to the outside, if an inertial mass
of about 13.8 or more times the movable mass is on the fixed end side Good. Therefore, the main
body 40 has a mass of about 13.8 times, preferably about 21 times, more preferably about 69
times or more of the total mass of the giant magnetostrictive element 1, the biasing magnet 2,
the elastic member 9 and the vibrating rod 6. As long as you have In addition, in the case where
another configuration to be vibrated by the vibrating rod 6 is provided, for example, a vibrating
pad or the like for applying headphones near the user's ear, the mass thereof is also included in
the mass of the vibrating rod 6. Also, the mass of a component that can be considered to be
mechanically integrated with the main body 40 may be included in the mass of the main body
40.
[0038]
It is desirable that the member of the main body 40 at the position where the fixed end side
configuration abuts, in the example of FIG. 7, the projection 42 have sufficient hardness to
suppress the vibration at the fixed end side of the giant magnetostrictive element 1 . Further, the
housing 8 is desirably a magnetic body. However, for example, when the magnetostriction device
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30 is used for headphones or the like, the generated magnetic field is not so large, so the housing
8 may not be a magnetic body. In this case, the housing 8 may be made of a lightweight material
to further reduce the weight.
[0039]
FIG. 8 shows a configuration of a headphone which is an example of the electronic device 50
provided with the magnetostriction device 30 shown in FIG. The headphone 200 includes an
open type magnetostrictive device 30 shown in FIG. 6 in place of the closed type
magnetostrictive device 20 provided in the headphone 100 shown in FIG. The inventor made a
prototype of the headphone 200 shown in FIG. 8, and like the headphone 100 shown in FIG. 5, a
wide range from bass to high tone was faithfully reproduced, and excellent acoustic
characteristics were realized. It was confirmed.
[0040]
The present inventor made a prototype of the headphone 200 of FIG. 8 provided with the
headphone 100 of FIG. 5 provided with the closed cylinder type magnetostrictive device 20
shown in FIG. 4 and the open type magnetostrictive device 30 shown in FIG. The relationship
between the mass ratio of the movable mass to the inertial mass supporting the fixed end and the
frequency characteristics of the sound output from the headphones was confirmed by the
hearing of the same subject actually wearing the headphones. Since it is difficult to measure the
frequency characteristics of the voice perceived by the human body as bone conduction as a
numerical value, the difference in the frequency characteristics is confirmed by the subject's
hearing this time.
[0041]
In the experiment using the closed type magnetostrictive device 20 of FIG. 4, a prototype of the
magnetostrictive device 20 having a mass of the movable portion of 1.3 g, an inertial mass
supporting the fixed end of 17.9 g, and a total mass of 22.2 g However, it has been confirmed
that it has better frequency characteristics, that is, the ability to output sound in a wide range of
frequencies than bone-conduction headphones using a conventional piezoelectric element or the
like. Accordingly, it has been found that the inertial mass supporting the fixed end is preferably
at least about 13.8 times the movable mass. When the mass of the vibration pad for transmitting
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the vibration of the super magnetostrictive element 1 of the magnetostrictive device 20 to the
head of the subject is included in the movable mass, it is preferable that the inertial mass is about
3.4 times or more of the movable mass. The prototype of headphone 100 equipped with this
magnetostrictive device 20 has an inertial mass on the fixed end side including the main body of
about 90 g, which is about 69 times the movable mass (about 9 times if the vibration pad is
included) It has been confirmed that it has better acoustic characteristics than conventional bone
conduction headphones.
[0042]
On the other hand, in the open type magnetostrictive device 30 of FIG. 6, the mass of the
magnetostrictive device 30 could be suppressed to 12.8 g by replacing the prestress cap 7 a and
the case 7 b with the housing 8. Since the mass of the prototype of the magnetostrictive device
20 was about 22.2 g, the mass of the magnetostrictive device is suppressed to about half. It is
known from the above-mentioned experiment that excellent frequency characteristics can be
obtained by providing a member having an inertial mass of about 13.8 times or more, more
preferably 69 times or more of the movable mass, to obtain excellent frequency characteristics.
The main body on which the 30 is to be mounted may have the mass. In the case of the
prototype magnetostrictive device 30, since the movable mass is 1.3 g, the mass of the main
body may be 17.9 g or more. The inventor made a prototype of a headphone 200 in which a
12.8 g magnetostrictive device 30 was mounted on a 27 g (about 21 times the movable mass)
body 40, and confirmed that a headphone having excellent acoustic characteristics was realized.
The headphone 200 is significantly lighter than the headphone 100 while maintaining the same
excellent acoustic characteristics as the headphone 100. In this prototype, the housing 8 is made
of metal, but the housing 8 may be made of a lightweight material such as resin if the coil is a
closed magnetic path with a yoke such as permalloy. Thereby, the magnetostriction device 30
can be further reduced in weight, and the entire device such as headphones can be reduced in
weight.
[0043]
FIG. 9 shows another configuration example of the electronic device 50 according to the base
technology. The magnetostrictive device 30 shown in FIG. 9 further includes a bottom plate 11 in
addition to the configuration of the magnetostrictive device 30 shown in FIG. The bottom plate
11 may be made of a waterproofed plate, for example, to prevent water droplets from entering
the magnetostrictive device 30 or the main body 40, or a magnetic body to prevent the magnetic
field from leaking to the main body 40 side. It may be configured. The magnetostrictive device
04-05-2019
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30 of this figure is not an open type but a closed type because the bottom plate 11 is provided
on the main body 40 side, but the bottom plate 11 is necessary to suppress the vibration of the
fixed end of the giant magnetostrictive element 1. It does not have to have a good inertial mass.
The bottom plate 11 is not provided to suppress the vibration of the fixed end of the giant
magnetostrictive element 1, and the inertial mass necessary for suppressing the vibration may be
included in the main body 40 of the electronic device 50.
[0044]
Also in this case, the main body 40 may have a mass of at least about 16.8 times, preferably at
least about 21 times, more preferably at least about 69 times the movable mass. It may be
included in the mass of In addition to the bottom plate 11, when a member is provided between
the main body 40 and the giant magnetostrictive element 1, the mass of the member may be
included in the mass of the main body 40. The point is that the fixed end side of the giant
magnetostrictive element 1 only needs to have sufficient mass and hardness to suppress the
vibration of the fixed end. Thereby, the vibration of the giant magnetostrictive element 1 can be
efficiently transmitted to the outside. Further, the excellent frequency characteristics of the
magnetostrictive device 30 can be exhibited without any problems, and in particular, when the
magnetostrictive device 30 is used for the headphones 200, the sound quality can be improved.
[0045]
(Embodiment) The present inventor has conceived a vibrating device capable of remotely
transmitting the vibration of the magnetostrictive device, paying attention to the magnitude of
the generated stress and the displacement amount of the magnetostrictive device described in
the base technology. . This vibration device has a large amount of generated stress and
displacement, and can also transmit vibrations in the ultrasonic band, so it can be used in various
fields such as the acoustic field and the medical field. Hereinafter, this vibrating device will be
described with reference to the drawings.
[0046]
FIG. 10 is a view showing the configuration of the vibration device according to the embodiment.
As shown in FIG. 10, the vibration device 300 includes a magnetostrictive device 30, a main body
40, and a vibration transmission mechanism 310.
04-05-2019
16
[0047]
The magnetostrictive device 30 is the magnetostrictive device shown in FIG. 6 and FIG. 7, and the
magnetostrictive device 30 is attached to the main body 40 by screwing the screw portion 81 of
the housing 8 and the screw portion 41 of the main body 40. . Thus, by connecting the housing 8
to the main body 40, the mass of the main body 40 can be used to suppress the displacement of
the fixed end of the giant magnetostrictive element 1, and the main magnetostrictive element 1 is
fixed by the main body 40. The displacement of the end is suppressed. As a result, since the
displacement of the fixed end of the super magnetostrictive element can be suppressed by the
member outside the magnetostrictive device 30, it is not necessary to provide the
magnetostrictive device 30 with a member having a large inertial mass. Furthermore, since the
pre-stress cap for applying pre-stress to the giant magnetostrictive element 1 can be omitted, the
magnetostriction device 30 can be made smaller and lighter, and consequently, the whole
vibration device 300 can be made smaller and lighter. Can be
[0048]
The vibration transfer mechanism 310 has a function of remotely transferring the vibration of
the giant magnetostrictive element 1. As shown in FIG. 10, the vibration transmission mechanism
310 includes a tube 302 and a wire 304 slidably disposed in the tube 302.
[0049]
One end of the wire 304 is in contact with the vibrating rod 6, and the wire 304 is mechanically
connected to the giant magnetostrictive element 1 through the vibrating rod 6 and the upper
biasing magnet 2a. One end of the wire 304 in contact with the vibrating rod 6 is called a giant
magnetostrictive element side end 304a, and the other end of the wire 304 is called a vibrating
end 304b. The length of the wire 304 can be any length depending on the application for which
the vibrating device 300 is used. Further, the type of the wire 304 is not particularly limited, but
it is preferable to use a flexible material wire, for example, a metal wire such as an aluminum
wire or a steel wire, or a plastic wire.
[0050]
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17
The giant magnetostrictive element side end 304 a and the vibrating rod 6 may be permanently
connected by an adhesive, welding or the like, or may be detachably connected by providing a
magnet or a mounting member. When connected releasably, it is possible to replace wires of
different lengths depending on the application. Also, the wire 304 and the vibrating rod 6 may be
formed as an integral part. In this case, since the number of parts is reduced, the parts cost and
the number of assembling steps can be reduced.
[0051]
The tube 302 is provided to cover the wire 304. The end 302 a of the tube 302 on the
magnetostrictive device 30 side is attached to a tube attachment portion 312 provided in the
housing 8. The vibrating end 304 b of the wire 304 is exposed from the other end 302 b of the
tube 302. The inner diameter of the tube 302 is formed larger than the outer diameter of the
wire 304 so that the wire 304 can slide within the tube 302. A lubricant such as oil may be
applied to the inner wall of the tube 302 to reduce the coefficient of friction of the wire 304 and
the tube 302. The material of the tube 302 is not particularly limited, but the vibration
transmission mechanism 310 can be configured to be deformable by forming it with a flexible
elastic material.
[0052]
In the vibration device 300 configured as described above, when an alternating current is applied
to the coil 4 by the circuit 49 of the main body 40, an alternating magnetic field is generated
around the coil 4 and the super magnetostrictive element 1 expands and contracts. The
expansion and contraction of the giant magnetostrictive element 1 is transmitted as vibration to
the wire 304 via the bias upper magnet 2a and the vibrating rod 6, and the vibrating end 304b
can be vibrated. Thus, the vibration device 300 can transmit the vibration generated by the
magnetostrictive device 30 to a remote place by providing the vibration transmission mechanism
310. Also, the vibration direction can be converted to a direction different from the vibration
direction of the giant magnetostrictive element 1 to transmit the vibration.
[0053]
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18
When attempting to remotely transmit the vibration of the vibration source using a wire, a large
generated stress is required for the vibration source because of the mass of the entire wire to be
vibrated and the frictional force between the tube and the wire. The vibration device 300
according to the present embodiment realizes transmission of vibration through a wire by using
a super magnetostrictive element having a large generated stress as a vibration source. By
providing a plurality of wires, the vibration of one giant magnetostrictive element 1 can also be
transmitted to a plurality of objects.
[0054]
FIG. 11 is a diagram illustrating another configuration example of the vibration device according
to the embodiment. As shown in FIG. 11, the vibration device 400 includes a magnetostrictive
device 30, a main body 40, and a vibration transmission mechanism 410. The vibration device
400 is different from the vibration device 300 of FIG. 10 in the configuration of the vibration
transmission mechanism 410.
[0055]
As shown in FIG. 11, the vibration transfer mechanism 410 includes a tube 402, a vibrating end
side lid portion 406, a magnetostrictive element side lid portion 408, and a liquid 404.
[0056]
The length of the tube 402 is not particularly limited, and may be any length depending on the
application of the vibrating device 400.
Further, the material of the tube 402 is not particularly limited, but the vibration transmission
mechanism 410 can be configured to be deformable by forming it with a flexible elastic material.
[0057]
The vibrating end side lid portion 406 and the magnetostrictive element side lid portion 408 are
provided to close the openings at both ends of the tube 402. The vibrating end side lid portion
406 and the magnetostrictive element side lid portion 408 can be formed of an elastic material
04-05-2019
19
such as rubber or a metal material. The liquid 404 is filled in the space formed by the tube 402,
the vibrating end side lid portion 406 and the magnetostrictive element side lid portion 408. The
liquid 404 is preferably filled with a predetermined pressure applied. By filling the liquid 404
under pressure, vibrations can be efficiently transmitted.
[0058]
The vibration transfer mechanism 410 is mechanically connected to the giant magnetostrictive
element 1 through the vibrating rod 6 and the upper magnet for bias 2 a by the magnetostrictive
element side cover 408 being in contact with the vibrating rod 6. The vibration transfer
mechanism 410 is supported by a vibration transfer mechanism support portion 412 provided in
the housing 8. The vibration transfer mechanism 410 may be permanently attached to the
vibration transfer mechanism support portion 412 by an adhesive, welding or the like, or may be
provided so as to be removable. If removable, it becomes possible to select a different vibration
transfer mechanism 410 depending on the application.
[0059]
In the vibration device 400 configured as described above, when an alternating current is applied
to the coil 4 by the circuit 49 of the main body 40, an alternating magnetic field is generated
around the coil 4 and the super magnetostrictive element 1 expands and contracts. The
expansion and contraction of the giant magnetostrictive element 1 is transmitted as vibration to
the magnetostrictive element side cover 408 through the bias upper magnet 2 a and the
vibrating rod 6. The vibration of the magnetostrictive element side lid 408 is transmitted to the
vibrating end side lid 406 via the liquid 404, and the vibrating end side lid 406 can be vibrated.
Thus, the vibration device 400 can transmit the vibration generated by the magnetostrictive
device 30 to a remote place by providing the vibration transmission mechanism 410.
[0060]
In order to remotely transmit vibrations through the liquid, the vibration source requires a large
generated stress. The vibration device 400 according to the present embodiment realizes
transmission of vibration via liquid by using a super magnetostrictive element having a large
generated stress as a vibration source.
04-05-2019
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[0061]
FIG. 12 is a diagram showing a headphone using the vibration device shown in FIG. The
headphones 250 comprise two vibrating devices 300. A vibrating pad 252 is provided at the tip
of the wire 304 of each vibrating device 300. The vibration pad 252 is supported by the support
portion 262 so that when the user mounts the headphones 250, the vibration can be transmitted
to the skull near the user's left and right ears. The length of the tube 302 and the wire 304 is set
to a predetermined length, for example, a length that allows the magnetostrictive device 30 to be
in the pocket of the user's clothes when the user mounts the headphones 250.
[0062]
When the headphone 250 is configured using the vibration device 300 as described above, it is
not necessary to provide a magnetostrictive device, a circuit, or the like in a portion mounted on
the user's head as in the headphone of FIG. The weight on the head of the head can be reduced.
In addition, the portion of the headphone 250 mounted on the head of the user can be
miniaturized. Although FIG. 12 shows headphones using the vibration device 300 of FIG. 10, the
vibration device 400 shown in FIG. 11 may be used as the vibration device.
[0063]
FIG. 13 is a view showing an acoustic system using the vibration device shown in FIG. In the
acoustic system 500, the vibration transfer mechanism 310 of the vibration device 300 placed in
the room is inserted from below the wall 520 to the back of the wall 520, and is disposed
upward from there. In FIG. 13, the broken line represents the wiring on the back side of the wall.
Further, the wire of the vibration transfer mechanism 310 is bifurcated from the middle, and one
vibrating end 304 c is abutted on the back surface of the wall 520 so as to vibrate the wall 520.
Also, the other vibrating end 304 d is disposed on the back side of the wall 522 adjacent to the
wall 520, and abuts on the back side of the wall 522 to vibrate the wall 522.
[0064]
In the sound system 500, when an audio signal emitted by the television receiver 510 is supplied
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to the vibrating device 300, the vibrating ends 304c and 304d of the vibration transfer
mechanism 310 vibrate in accordance with the audio signal. The vibration of the vibrating ends
304c, 304d is transmitted to the walls 520, 522 of the room, and the walls 520, 522 function as
speakers to generate sound in the room.
[0065]
In this way, by making the surrounding wall, floor, ceiling, etc. of the audience function as
speakers and generating sound, a completely new acoustic space can be created. The chair 530
or the table 540 can also function as a speaker by abutting the vibrating end of the vibrating
device 300 on the chair 530 or the table 540 on which the audience is sitting. In this case, not
only the sound is sensed through the vibration of air, but the vibration can be directly
transmitted from the floor or chair to the audience, and the voice can be complexly sensed
through bone conduction or the like. Thus, by installing the vibration device 300 in accordance
with the purpose and needs, it is possible to produce an optimal acoustic space.
[0066]
In FIG. 13, the wire of the vibration transfer mechanism 310 is branched to vibrate the two
vibration ends. However, it is possible to simultaneously vibrate a plurality of vibration ends in
this manner. This is a function unique to the vibration device using. Although FIG. 13 shows an
acoustic system using the vibration device 300 of FIG. 10, the vibration device 400 shown in FIG.
11 may be used as the vibration device.
[0067]
FIG. 14 is a view showing an ultrasonic endoscope using the vibration device shown in FIG. FIG.
14 shows the distal end portion of the ultrasonic endoscope 600. An illumination unit 602, an
observation unit 604, a forceps port 606, a nozzle 608, and an ultrasonic transducer 620 are
provided on the distal end surface 610 of the ultrasonic endoscope 600.
[0068]
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22
The observation unit 604 includes an objective lens and a solid-state imaging device such as a
CCD, and has a function of transmitting a captured image to a main body (not shown). The
illumination units 602 are disposed at positions on both sides of the observation unit 604. The
lighting unit 602 has a function of emitting light from a light source provided in the main body.
The forceps port 606 is provided to lead out forceps and other treatment portions used for tissue
collection and treatment, foreign matter recovery and the like. The nozzle 608 is provided to
eject and wash water and air when the objective lens of the observation unit 604 is contaminated
with mucus and blood inside the organ.
[0069]
The ultrasonic transducer 620 has a function of transmitting an ultrasonic wave to an object
such as a living tissue and receiving an ultrasonic wave reflected from the object. In an ultrasonic
endoscope 600 shown in FIG. 14, a vibration device 400 shown in FIG. 11 is used as an
ultrasonic transducer 620. In the ultrasonic endoscope 600, the distal end portion of the
vibration transfer mechanism 410 of the vibrating device 400 is provided so as to protrude from
the distal end surface 610.
[0070]
In the ultrasonic endoscope 600 configured as described above, when an alternating current of a
predetermined frequency is applied to the coil of the vibrating device, the vibrating end side
cover 406 is vibrated to emit an ultrasonic wave. The ultrasonic wave emitted from the vibrating
end side lid 406 is reflected by the object. The reflected ultrasonic wave vibrates the vibrating
end side cover 406, and in this case, the reflected ultrasonic wave is transmitted to the giant
magnetostrictive element of the magnetostrictive device through the liquid in the tube 402.
When the giant magnetostrictive element changes in response to this vibration, the magnetic
characteristics of the giant magnetostrictive element change, so the current flowing through the
coil changes. An ultrasonic tomographic image can be generated by detecting, processing and
imaging this current change.
[0071]
As described above, when the vibration device 400 shown in FIG. 11 is used for an ultrasonic
endoscope, the vibration generated by the giant magnetostrictive element can be transmitted to
04-05-2019
23
the remote through the vibration transmission mechanism. There is no need to provide an
ultrasound transducer to generate sound waves. Thereby, size reduction and weight reduction of
an endoscope tip part are realizable.
[0072]
FIG. 15 is a view showing a dismantling machine using the vibration device 300 shown in FIG.
The giant magnetostrictive element can be used as a dismantling machine for disassembling an
object by giving vibration because the generated stress and the amount of displacement are
large. The vibrating device 300 shown in FIG. 15 includes a vibrating plate 710 at the tip of the
wire 304. FIG. 15 shows a state in which the diaphragm 700 is vibrated by driving the vibration
device 300 and the wall 700 is disassembled. When the vibration device 300 is used as a
disassembling machine in this manner, the size of the giant magnetostrictive element may be set
according to the size, hardness, etc. of the object to be disassembled.
[0073]
The present invention has been described above based on the embodiments. It will be understood
by those skilled in the art that this embodiment is an exemplification, and that various
modifications can be made to the combinations of the respective constituent elements and
processing processes, and such modifications are also within the scope of the present invention.
is there.
[0074]
It is a figure which shows the structure of the conventional magnetostriction apparatus. It is a
figure which shows the characteristic of super-magnetostrictive material and a piezoelectric
material. FIGS. 3A and 3B show how the magnetostrictive element vibrates. It is a figure which
shows the structure of the improved magnetostriction apparatus. It is a figure which shows the
structure of the headphone which is an example of the electronic device provided with the
magnetostriction apparatus shown in FIG. It is a figure which shows the structure of the
magnetostriction apparatus which concerns on a premise technology. It is a figure which shows
the structure of the electronic device which concerns on a premise technology. It is a figure
which shows the structure of the headphone which is an example of the electronic device
provided with the magnetostriction apparatus shown in FIG.6 and FIG.7. It is a figure which
04-05-2019
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shows another structural example of the electronic device which concerns on a premise
technology. It is a figure showing the composition of the oscillating device concerning an
embodiment. It is a figure which shows another structural example of the vibration apparatus
which concerns on embodiment. It is a figure which shows the headphone which used the
vibration apparatus shown in FIG. It is a figure which shows the acoustic system using the
vibration apparatus shown in FIG. It is a figure which shows the ultrasonic endoscope which used
the vibration apparatus shown in FIG. It is a figure which shows the dismantling machine using
the vibration apparatus shown in FIG.
Explanation of sign
[0075]
1 Magnetostrictive Device, Magnet for 2 Bias, 4 Coil, 6 Vibrating Rod, 8 Housing, 30
Magnetostrictive Device, 40 Body, 41 Screws, 42 Projections, 49 Circuits, 81 Screws, 250
Headphones, 252 Vibration Pads, 262 Support Part, 300 vibration device, 302 tube, 304 wire,
310 vibration transmission mechanism, 400 vibration device, 402 tube, 404 liquid, 406
vibration end side lid portion, 408 magnetostrictive element side lid portion, 410 vibration
transmission mechanism, 500 acoustic system, 510 television receiver, 520, 522 wall, 600
ultrasound endoscope, 610 tip surface, 620 ultrasound transducer.
04-05-2019
25

JP2006025381

JP2001258095

JP2007079869

JP2008258719

JP2002066457

JP2000337435

JP2005278226

JP2008228248

JP2005349155

JP2005080462