JP2005210550

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DESCRIPTION JP2005210550
An actuator capable of reducing sound leakage is provided. A columnar magnetostrictive element
51 is provided with a partition plate 22 at one end side, one end being defined as a fixed end and
the other end side being defined as a free end, and extending and contracting along an axial
direction; The driving coil 54 for generating a magnetic field for expanding and contracting the
columnar magnetostrictive element 51 by the driving current, and the vibration transmission
which is disposed on the other end side of the columnar magnetostrictive element 51 and
transmits vibration due to expansion and contraction of the columnar magnetostrictive element
51 to the plate 7 Body 55 and a pair of magnets 52b and 53 that repel each other in a direction
away from each other along the axial direction, and the pair of magnets 52b and 53 extend in the
axial direction between the partition plate 22 and the vibration transmitting member 55 It is
arranged along. [Selected figure] Figure 1
Actuator and sound equipment
[0001]
The present invention relates to an actuator and an acoustic device using a magnetostrictive
element.
[0002]
An acoustic device disclosed in Japanese Patent Laid-Open No. 9-261797 is known as this kind
of acoustic device (actuator).
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This acoustic device includes a columnar magnetostrictive element and a drive coil wound
around a bobbin around the columnar magnetostrictive element. In this case, the columnar
magnetostrictive element is disposed in such a manner that one end thereof abuts against the
disk-shaped magnetic body and the other end abuts against the end of the magnetic member. In
this case, a flange is formed on the magnetic member, and an elastic member is inserted between
the flange and the case. Therefore, the magnetic member is urged toward the columnar
magnetostrictive element by the inserted elastic member, and is thus maintained in a state
capable of advancing and retracting in the direction along the vibration direction of the columnar
magnetostrictive element. As a result, the disk-shaped magnetic body, the columnar
magnetostrictive element, and the magnetic member are integrally connected in a state in which
the vibration of the columnar magnetostrictive element is allowed.
[0003]
In this acoustic device, when a drive current based on the acoustic signal is supplied, the drive
coil generates a magnetic field oriented in the axial direction of the columnar magnetostrictive
element. At this time, the columnar magnetostrictive element expands and contracts in the axial
direction when the generated magnetic field is applied. Therefore, the magnetic member vibrates
in the axial direction according to the expansion and contraction of the columnar
magnetostrictive element. Therefore, when the magnetic member is pressed against a vibrating
body such as a vibrating plate, the vibration is transmitted to the vibrating body, and a sound is
output from the vibrating body. JP-A-9-261797 (page 3, FIG. 1)
[0004]
However, this acoustic device (actuator) has the following problems. That is, in this acoustic
device, the disc-shaped magnetic body, the columnar magnetostrictive element, and the magnetic
member are made by urging the magnetic member toward the columnar magnetostrictive
element by the elastic member so as to allow the vibration of the columnar magnetostrictive
element. It is connected integrally. However, when the magnetic member is not pressed against
the vibrator, that is, when the output of sound is stopped, the elastic member is a columnar
magnetostrictive element due to, for example, the vibration frequency or the magnitude of
vibration of the columnar magnetostrictive element. In some cases, displacement due to
expansion and contraction can not be absorbed, and in that case, the integrated connection of the
disk-shaped magnetic body, the columnar magnetostrictive element, and the magnetic member is
released. Therefore, there is a risk that sound leakage based on the acoustic signal may occur due
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to the disc-shaped magnetic body and the magnetic member and the columnar magnetostrictive
element coming into contact with each other as the columnar magnetostrictive element expands
and contracts. Is preferred.
[0005]
The present invention has been made in view of the problem to be solved, and its main object is
to provide an actuator capable of reducing sound leakage. Another main object of the present
invention is to provide an acoustic device capable of reducing sound leakage when the output of
sound is stopped.
[0006]
In order to achieve the above object, the actuator according to the present invention has a
columnar magnetostriction in which a stopper is disposed at one end and the one end is defined
as a fixed end and the other end is defined as a free end to expand and contract along the axial
direction. An element, a magnetic field generation unit for generating a magnetic field for
expanding and contracting the columnar magnetostrictive element by a drive current based on
an acoustic signal, and the other end side of the columnar magnetostrictive element And a pair of
magnetic force generating means for repelling each other in a direction away from each other
along the axial direction, the pair of magnetic force generating means including the stopper to
the vibration transmitting body It is disposed along the axial direction between the two. In the
present invention, "between the stopper and the vibration transfer member" means a portion
including the vibration transfer member itself as a portion on which the pair of magnetic force
generating means is disposed. That is, it means that the structure which forms a vibration
transmission body by one of a pair of magnetic force generation means is also included.
[0007]
In this case, it is preferable that at least one of the pair of magnetic force generating means be a
permanent magnet.
[0008]
Preferably, the pair of magnetic force generating means are disposed adjacent to each other.
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[0009]
An acoustic device according to the present invention is constituted by the actuator according to
any one of claims 1 to 3, and transmits vibration due to the expansion and contraction of the
columnar magnetostrictive element to the vibrator to cause the vibrator to output sound. .
[0010]
In the actuator and the acoustic device according to the present invention, the stopper is
disposed on one end side of the columnar magnetostrictive element, and the vibration
transmitting body is disposed on the other end side of the columnar magnetostrictive element. In
the above, a pair of magnetic force generating means are provided which repel each other in a
direction away from each other.
Therefore, in a state where the vibration transfer body is not pressed against the vibrating body,
the space formed between the two functions as an elastic body by the repulsive force of the pair
of magnetic force generating means, thereby absorbing the displacement due to the expansion
and contraction of the columnar magnetostrictive element be able to.
As a result, according to the actuator and the acoustic device, it is possible to reduce the sound
leakage due to the contact between the member in the actuator including the stopper and the
vibration transmitter and the columnar magnetostrictive element.
On the other hand, when using the actuator and the acoustic device, the vibration transfer body
is pressed against the vibrating body so that the space functioning as an elastic body is narrower
than the limit at which the elasticity can be maintained. At this time, since the space functioning
as an elastic body functions as an inelastic body, the vibration due to the expansion and
contraction of the columnar magnetostrictive element is transmitted to the vibration transmitter,
and the vibration is transmitted to the vibrator via the vibration transmitter. Therefore, according
to the actuator and the acoustic device, when transmitting the vibration or outputting the sound,
the vibration is reliably transmitted to the vibrating body, and when the transmitting of the
vibration is stopped or the output of the sound is stopped, the sound leakage is sufficiently
reduced. can do.
[0011]
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In addition, according to the actuator and the acoustic device according to the present invention,
at least one of the pair of magnetic force generating means is constituted by the permanent
magnet, so that the structure is simple as compared with the structure in which the magnetic
force generating means is formed by the electromagnet. However, since the number of parts to
be configured can be reduced, parts costs and assembly costs can be reduced. In addition, since
the magnetic force generation means can be configured without using electric power as
compared with the configuration in which the magnetic force generation means is formed by the
electromagnet, the power consumption can be reduced.
[0012]
Further, according to the actuator and the acoustic device according to the present invention, by
arranging the pair of magnetic force generating means adjacent to each other, a space
functioning as an elastic body is formed by more effectively utilizing the respective magnetic
forces. Therefore, the displacement due to the expansion and contraction of the columnar
magnetostrictive element can be sufficiently absorbed. As a result, it is possible to further reduce
the sound leakage due to the contact between the columnar magnetostrictive element and the
member in the actuator including the stopper and the vibration transmitter.
[0013]
Hereinafter, the best mode of an actuator and an acoustic device according to the present
invention will be described with reference to the attached drawings.
[0014]
First, the configuration of a pencil-type speaker 1 to which an actuator and an acoustic device
according to the present invention are applied will be described with reference to the drawings.
[0015]
As shown in FIG. 1, the pencil type speaker 1 includes a cylindrical casing 2, an acoustic signal
amplification unit 3, a power supply unit 4 and a vibration conversion unit 5, and its tip end is,
for example, a plate 7 as a vibrator. It is configured to be able to output an acoustic signal when
pressed against.
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As shown in the figure, the housing unit 2 is configured to include an upper housing 2a and a
lower housing 2b respectively formed of synthetic resin, and is formed at each end of the both
housings 2a and 2b. By being fitted together and integrally coupled by the fitting portion, it is
configured in an elongated pencil type as a whole.
Further, a partition plate 21 is provided in the upper housing 2a, and the acoustic signal
amplifier 3 is housed in an inner space on the rear end side partitioned by the partition plate 21,
and the power supply unit 4 is a partition plate It is accommodated in the internal space by the
side of the tip part divided by 21. On the other hand, a partition plate (a stopper in the present
invention) 22 which divides the power supply unit 4 and the vibration conversion unit 5 is fixed
to the lower housing 2 b.
[0016]
As shown in FIG. 2, the acoustic signal amplification unit 3 amplifies the acoustic signal input
from the outside via the acoustic signal cable 6 and outputs the generated drive current to the
drive coil 54 via a connection cable (not shown). . Further, as shown in FIG. 1, the acoustic signal
amplification unit 3 includes an amplifier substrate 31 disposed on the rear end side of the upper
housing 2a, and the amplifier substrate 31 includes, as shown in FIG. A power switch 32 and an
acoustic signal input connector 33 are mounted. In this case, as shown in the figure, the power
switch 32 is configured to include a knob 34 that can turn on / off the power of the pencil type
speaker 1 by switching. Further, as shown in the figure, the audio signal input connector 33 is
configured as a plug that can be inserted into the jack 61 of the audio signal cable 6 for inputting
an audio signal from the outside.
[0017]
As an example, as shown in FIGS. 1 and 2, the power supply unit 4 includes three dry batteries
41, 41 and 41, a dry battery terminal 42 fixed to the partition plate 21, and a dry battery
terminal 43 fixed to the partition plate 22. And supplies power to the acoustic signal
amplification unit 3 via a connection cable connected to the dry cell terminals 42 and 43. In this
case, the dry battery 41 is taken in and out from the opening on the tip end side of the upper
housing 2a in a state in which the fitting portion is removed and the lower housing 2b is
separated.
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[0018]
The vibration converter 5 is disposed in the internal space of the lower housing 2b, and as shown
in FIGS. 1 and 2, the columnar magnetostrictive element 51, the bias magnets 52a and 52b, the
magnet 53, the drive coil 54 and the vibration transmitter 55 are provided. It is configured to be
equipped. The columnar magnetostrictive element 51 expands and contracts in the axial
direction by applying a magnetic field in the direction along the axial direction, and functions as
an element that converts magnetic field fluctuation into mechanical vibration. The columnar
magnetostrictive element 51 is formed of, for example, a super magnetostrictive material having
a central composition Tb0.34-Dy0.66-Fe1.90 which causes a large displacement of about 1500
ppm to 2000 ppm in the axial direction in the magnetic field. It is done. One end of the columnar
magnetostrictive element 51 on the side of the partition plate 22 corresponds to the fixed end in
the present invention, and the other end on the side of the vibration transfer body 55
corresponds to the free end in the present invention. The bias magnets 52a and 52b are, for
example, permanent magnets formed in a disk shape, one end face of each being defined as an S
pole, and the other end face being defined as an N pole. For example, the bias magnet 52 a is
fixed (arranged) to the columnar magnetostrictive element 51 such that one end face abuts on
the end face of the columnar magnetostrictive element 51 on the upper housing 2 a side and the
other end face can abut on the partition plate 22. ing. On the other hand, the bias magnet 52b
corresponds to one of the pair of magnetic force generating means in the present invention, one
end face is opposed to the magnet 53, and the other end face is fixed to the end face of the
columnar magnetostrictive element 51 on the vibration transfer body 55 side. (Disposed). That is,
the bias magnet 52b is disposed such that the magnetic pole of the other end face on the side
facing the bias magnet 52a has an N pole which is a different pole with respect to the S pole of
the bias magnet 52a. In this case, the bias magnets 52a and 52b apply the bias magnetic field so
that the columnar magnetostrictive element 51 can be operated at an operation point that
linearly expands and contracts (oscillates) the magnetic field in the axial direction.
[0019]
The magnet 53 corresponds to the other of the pair of magnetic force generating means in the
present invention, and as shown in FIG. 1, for example, is a permanent magnet formed in a disk
shape, and one end face on the bias magnet 52b side is S It is specified at the pole, and the other
end face is specified at the N pole. Further, as shown in the figure, the magnet 53 is fixed to the
flange 55 a so that the other end face is adjacent to the bias magnet 52 b and one end face is
opposed to one end face of the bias magnet 52 b. That is, the magnet 53 is repelled from the bias
magnet 52b in a direction away from each other by defining the magnetic pole of one end
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surface facing each other with one end face of the bias magnet 52b as the S pole as the same
pole S pole. It is arranged to fit. In this case, the number of parts can be reduced by adopting a
configuration in which the magnetic force generation means in the present invention is formed
using a magnet (in this example, the bias magnet 52b) that applies a bias magnetic field to the
columnar magnetostrictive element 51. As a result, parts costs and assembly costs are reduced.
The drive coil 54 corresponds to a magnetic field generation unit in the present invention, and as
shown in FIGS. 1 and 2, the drive coil 54 is disposed such that its central axis is coaxial with the
central axis of the columnar magnetostrictive element 51. Further, as shown in FIG. 2, the drive
coil 54 receives a drive current from the acoustic signal amplifier 3 via the connection cable, and
generates a magnetic field on the axis thereof (the axis of the columnar magnetostrictive element
51).
[0020]
As shown in FIG. 1, the vibration transmitting body 55 is integrally configured by including a
disk-shaped flange 55a, a shaft 55b and a tip contact portion 55c. As shown in the figure, the
magnet 53 is fixed to the upper end surface of the flange 55a, and the lower end surface of the
flange 55a abuts on the inner wall of the lower housing 2b. In this case, the flange 55a is pressed
against the lower housing 2b in a state in which the space S is formed between the two by the
repulsive force of the magnet 53 and the bias magnet 52b. The shaft 55b has the tip end contact
portion 55c fixed to the tip end surface thereof, and transmits the vibration of the flange 55a to
the tip end contact portion 55c. As shown in the figure, when the tip end side is formed in a
hemispherical shape and the tip end contact portion 55c is pressed against the plate 7, the
vibration of the vibration transfer body 55 can be applied to the plate 7 as shown in the figure.
introduce. Therefore, as shown in the figure, the vibration transfer body 55, the magnet 53, the
bias magnet 52b, the columnar magnetostrictive element 51, the bias magnet 52a and the
partition plate 22 are formed by the repulsive force of both the magnets 52b and 53. Are
integrally connected via the space S between them. In addition, when the tip contact portion 55c
(the vibration transmitter 55) is pressed against the plate 7, the space S between the magnets
52b and 53 is narrowed, and the direction toward the columnar magnetostrictive element 51 is
relative to the tip S. To move. Therefore, in this state, the space S between the magnets 52b and
53 functions as an inelastic body.
[0021]
Next, the overall operation of the pencil-type speaker 1 will be described.
[0022]
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In the pencil type speaker 1, when the tip contact portion 55 c of the vibration transfer body 55
is not pressed against the plate 7, that is, when the output of sound is stopped, the acoustic
signal amplification unit 3 externally receives the acoustic signal cable 6. The input acoustic
signal is amplified and a drive current is supplied to the drive coil 54.
At this time, the drive coil 54 applies a magnetic field generated based on the supplied drive
current to the columnar magnetostrictive element 51. Therefore, the columnar magnetostrictive
element 51 expands and contracts in the axial direction according to the applied magnetic field.
In this state, the space S between the two magnets 52b and 53 absorbs the displacement of the
distance between the two magnets 52b and 53 due to the expansion and contraction of the
columnar magnetostrictive element 51, and the repulsive force by the two magnets 52b and 53
transmits vibration. The integrally connected state of the body 55, the magnet 53, the bias
magnet 52b, the columnar magnetostrictive element 51, the bias magnet 52a, and the partition
plate 22 is maintained. Therefore, sound leakage due to the contact between the members is
effectively and sufficiently reduced.
[0023]
On the other hand, when the tip contact portion 55c is pressed against the plate 7 with a
predetermined pressure so that the space S between the magnets 52b and 53 is narrowed, the
partition plate 22 is a stopper (that is, the weight of the human hand and the pencil type speaker
1 Functions as an inertial mass), and the space S between the magnets 52b and 53 is narrowed
(that is, the distance between the magnets 52b and 53 is shortened). At this time, the repulsive
force of both magnets 52b and 53 is large, and one end face of the bias magnet 52b is pressed to
the plate 7 side via the narrowed space S, the magnet 53 and the vibration transmitter 55. And
the other end face of the bias magnet 52b is fixed at the predetermined position by the partition
plate 22 via the columnar magnetostrictive element 51 and the bias magnet 52a, so the
narrowed space S is a non-elastic body. As a result, the displacement due to the expansion and
contraction of the columnar magnetostrictive element 51 can not be absorbed. Therefore, in this
case, vibration due to expansion and contraction of the columnar magnetostrictive element 51 is
transmitted to the plate 7 through the bias magnet 52b, the narrowed space S, the magnet 53,
the flange 55a, the shaft 55b and the tip contact portion 55c. Ru. In this state, the vibration of
the plate 7 causes the acoustic signal input from the outside to be output from the plate 7 as a
sound that can be sufficiently heard.
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[0024]
As described above, according to this pencil type speaker 1, the partition plate 22 is disposed on
one end side of the columnar magnetostrictive element 51 and the vibration transmitting body
55 is disposed on the other end side of the columnar magnetostrictive element 51. By arranging
the pair of magnets 52b and 53 that repel each other in the direction away from each other
between the plate 22 and the vibration transmitter 55, both magnets 52b are not pressed to the
plate 7 by the vibration transmitter 55. , 53 can function as an elastic body, so that the
displacement due to the expansion and contraction of the columnar magnetostrictive element 51
can be absorbed. Therefore, according to this pencil type speaker 1, at the time of sound output,
the plate body 7 is vibrated to surely output the sound, and when the sound output is stopped,
the partition plate 22 or the bias magnet 52a in the pencil type speaker 1 , 52b, etc., and sound
leakage due to the contact between the columnar magnetostrictive element 51 can be sufficiently
reduced. Furthermore, according to this pencil type speaker 1, since the space S between the
both magnets 52b and 53 functions as an elastic body, it absorbs the force applied to the end
face of the columnar magnetostrictive element 51 due to the adhesion or fall of foreign matter.
As a result, the occurrence of breakage of the columnar magnetostrictive element 51 can be
avoided. Also, even when damage occurs, the extent of the damage can be reduced.
[0025]
In addition, according to this pencil type speaker 1, by configuring both magnets 52b and 53
with permanent magnets, compared with a configuration in which both magnets 52b and 53 are
formed with electromagnets, components configured while having a simple structure Since the
number can be reduced, parts costs and assembly costs can be reduced. In addition, compared to
the configuration in which both magnets 52 b and 53 are formed by electromagnets, magnetic
force can be generated without using electric power, and therefore power consumption can be
reduced.
[0026]
Moreover, according to this pencil type speaker 1, by arranging both magnets 52b and 53 so as
to be adjacent to each other, the space S functioning as an elastic body is formed by more
effectively utilizing the respective magnetic forces. Therefore, the displacement due to the
expansion and contraction of the columnar magnetostrictive element 51 can be sufficiently
absorbed. Therefore, sound leakage due to the contact between the columnar magnetostrictive
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element 51 and members such as the partition plate 22 and the bias magnets 52 a and 52 b in
the pencil type speaker 1 including the partition plate 22 and the vibration transfer body 55 is
further reduced. it can.
[0027]
The present invention is not limited to the above configuration. For example, although the above
describes the configuration in which the bias magnet 52b and the magnet 53 formed of
permanent magnets are disposed, one or both of the bias magnet 52b and the magnet 53 are
electromagnets as in the pencil type speaker 1A shown in FIG. It can also consist of In the
following, components having the same functions as the components of the pencil-type speaker 1
will be assigned the same reference numerals and redundant explanations will be omitted.
[0028]
The pencil-type speaker 1A is configured in the same manner as the pencil-type speaker 1 except
for the vibration converting unit 5A. On the other hand, as shown in FIG. 3, the vibration
conversion unit 5A is configured to include a columnar magnetostrictive element 51, a drive coil
54, a vibration transmitter 55, a ferromagnetic body 56, a coil 57, a ferromagnetic body 58 and a
coil 59. There is. The ferromagnetic body 56 is formed in a disk shape, for example, and is fixed
(disposed) to the end face of the columnar magnetostrictive element 51 on the vibration transfer
body 55 side. In addition, the coil 57 is supplied with a direct current from the amplifier
substrate 31 via a cable (not shown), and operates the columnar magnetostrictive element 51 at
an operating point that linearly expands and contracts (oscillates) against fluctuations in the
magnetic field in the axial direction. Thus, a DC bias magnetic field can be applied, and a DC
magnetic field can be applied to the ferromagnetic member 56. In this case, the ferromagnetic
body 56 and the coil 57 together constitute an electromagnet as one of the pair of magnetic
force generating means in the present invention. As shown in the figure, the ferromagnetic
member 58 is fixed to the flange 55 a so that one end surface thereof faces the ferromagnetic
member 56. The coil 59 is supplied with a direct current from the amplifier substrate 31 via a
cable (not shown), and is configured to be able to apply a direct current magnetic field to the
ferromagnetic body 58. In this case, the ferromagnetic body 58 and the coil 59 constitute an
electromagnet corresponding to the other of the pair of magnetic force generating means in the
present invention. The coil 59 is wound such that the direction of the magnetic field applied on
the axis of the ferromagnetic body 58 is opposite (in the opposite direction) to the direction of
the magnetic field applied on the axis of the ferromagnetic body 56 by the coil 57. It is done.
Therefore, the electromagnet formed by the ferromagnetic body 58 and the coil 59 is configured
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to repel the electromagnet formed by the ferromagnetic body 56 and the coil 57 in the direction
away from each other.
[0029]
In this pencil type speaker 1A, the electromagnet formed by the ferromagnetic body 56 and the
coil 57 and the electromagnet formed by the ferromagnetic body 58 and the coil 59 are
respectively for the bias magnet 52b and the magnet 53 in the pencil type speaker 1 Acts
correspondingly. Therefore, according to this pencil type speaker 1A, substantially the same
operation and effect as those of the pencil type speaker 1 can be achieved although the electric
power for operating the coil 57 and the coil 59 is required.
[0030]
Note that although the above describes the configuration in which both the electromagnet
formed by the ferromagnetic body 56 and the coil 57 and the electromagnet formed by the
ferromagnetic body 58 and the coil 59 are replaced with permanent magnets, only one of them is
an electromagnet. It can also be configured. Even in this configuration, sound leakage can be
sufficiently reduced as in the configuration of the pencil-type speakers 1 and 1A.
[0031]
In addition, a configuration in which a pair of magnets (bias magnet 52b and magnet 53, or
ferromagnetic body 56 and coil 57 and ferromagnetic body 58 and coil 59) is disposed between
columnar magnetostrictive element 51 and vibration transmitter 55 As described above, in place
of or in addition to the pair of magnets, another pair of magnets may be disposed between the
partition plate 22 and the distal end contact portion 55c. it can. Even in this configuration, sound
leakage can be sufficiently reduced as in the configuration of the pencil-type speakers 1 and 1A.
Furthermore, in place of the magnet 53 (the other of the pair of magnets), the vibration transfer
body 55 itself may be configured by a magnet. According to this configuration, the number of
parts can be reduced.
[0032]
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In addition, although the configuration in which the pair of magnets (bias magnet 52b and
magnet 53, or ferromagnetic material 56 and coil 57 and ferromagnetic material 58 and coil 59)
are disposed adjacent to each other has been described above, the present invention is not
limited thereto. It is also possible to adopt a configuration in which another member such as a
vibration transfer member is disposed between the pair of magnets and the two magnets are
disposed apart from each other. Even with this configuration, although the distance between the
pair of magnets is longer and the repulsive force of the magnetic force is slightly weakened as
compared with the configuration of the pencil type speakers 1 and 1A, sound leakage can be
sufficiently reduced. .
[0033]
In addition, the function of applying a bias magnetic field to enable operation of the columnar
magnetostrictive element 51 at an operating point that linearly expands and contracts (oscillates)
the bias magnet 52b against fluctuation of the magnetic field in the axial direction, and the
magnetic force of the magnet 53. Although the above-described configuration has the function of
forming the space S as the elastic body by the repulsive force, the invention is not limited to this
configuration, and only the function of forming the space S as the elastic body can be provided.
In this case, another separate magnet may apply a bias magnetic field to the columnar
magnetostrictive element 51. In addition, the ferromagnetic body 56 and the coil 57 in the
pencil-type speaker 1A can have only the function of forming the space S as an elastic body. Even
in this configuration, sound leakage can be sufficiently reduced as in the configuration of the
pencil-type speakers 1 and 1A.
[0034]
In addition, although the above-described pencil type loudspeakers 1 and 1A having a
configuration in which one columnar magnetostrictive element 51 is disposed, the number of
columnar magnetostrictive elements 51 is not limited to one, and a plurality of columnar
magnetostrictive elements 51 can be disposed. In addition, in this configuration, a pair of
magnets can be disposed between the columnar magnetostrictive elements 51, 51.
[0035]
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Further, in the configuration of the pencil type speaker 1 described above, although the
configuration in which the bias magnet 52b and the magnet 53 face each other at the S pole has
been described, the configuration is not limited to this. Of course you can. Furthermore, although
the pencil type speaker 1, 1A in which the actuator according to the present invention is applied
to an acoustic device has been described above, the actuator can be applied to various devices
that transmit vibration as well as the acoustic device.
[0036]
FIG. 1 is a cross-sectional view showing a configuration of a pencil type speaker 1; FIG. 2 is a
block diagram showing an electric circuit of a pencil type speaker 1; It is a sectional view
showing the composition of pencil type speaker 1A.
Explanation of sign
[0037]
1, 1A pencil type speaker 22 partition plate 51 columnar magnetostrictor 52b bias magnet 53
magnet 54 drive coil 55 vibration transmitter 56, 58 ferromagnetic 57, 59 coil
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