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JP2009130663

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DESCRIPTION JP2009130663
A speaker device which reproduces sound by applying vibration to an acoustic diaphragm by an
actuator. A sound image is uniformly spread over the entire surface of the acoustic diaphragm,
and the entire speaker device can be made compact. SOLUTION: A square hole 12 is formed in a
flat plate-like acoustic diaphragm 10, and a magnetostrictive actuator 30 is shown in the square
hole 12, and an angle to the extension direction of the outer end face 11a of the acoustic
diaphragm 10 in the drive axis direction. Wear so that α is non-right angle. When the
magnetostrictive actuator 30 is driven by an audio signal, longitudinal vibration is applied to the
point Pa of the acoustic diaphragm 10. In the process of propagating the longitudinal wave to the
outer end face 11a, the longitudinal wave and the transverse wave become a mixed wave, and the
transverse wave is emitted as a sound wave in the direction perpendicular to the plate surface of
the acoustic diaphragm 10. Since the angle α is non-right angle, the resonance due to the
longitudinal wave reflected by the outer end face 11a is reduced. [Selected figure] Figure 9
Speaker apparatus and speaker driving method
[0001]
The present invention relates to a speaker device that reproduces sound by applying vibration to
an acoustic diaphragm by an actuator such as a magnetostrictive actuator, and a method of
driving the speaker device.
[0002]
As a speaker device, one that applies vibration to an acoustic diaphragm by an actuator such as a
magnetostrictive actuator to reproduce sound is considered.
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1
[0003]
One type is that, as shown in FIG. 18, the drive rod 95 of the magnetostrictive actuator 90 is in
contact with the flat acoustic diaphragm 81 so that the acoustic diaphragm 81 is in the thickness
direction, ie, in the plate surface. It adds vertical vibration.
[0004]
Another type is, for example, a cylindrical acoustic diaphragm 85 having openings at both ends
as shown in Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-166027) and
as shown in FIG. Vertically supported, a plurality of magnetostrictive actuators 90 are disposed
on the lower end side of the acoustic diaphragm 85, and the drive rod 95 of each
magnetostrictive actuator 90 is brought into contact with the lower end surface 86 of the
acoustic diaphragm 85. , Vibration in the direction perpendicular to the lower end surface 86,
that is, in the direction of the plate surface.
[0005]
In the speaker device of the type shown in FIG. 19, the lower end face 86 of the acoustic
diaphragm 85 is excited by the longitudinal wave, but the propagating elastic wave propagates in
the plate surface direction of the acoustic diaphragm 85 and the longitudinal wave and the
transverse wave are mixed. As a wave, a sound wave is emitted by the transverse wave in the
direction perpendicular to the plate surface of the acoustic diaphragm 85, and a sound field
having a spreading feeling can be obtained.
[0006]
The magnetostrictive actuator is an actuator using a magnetostrictive element whose shape
changes when an external magnetic field is applied. Recently, a magnetostrictive element whose
shape change amount is about 1000 times that of the conventional one appears as a
magnetostrictive element. Because of the large stress that occurs when the pressure change
occurs, even a small magnetostrictive actuator can make the acoustic diaphragm sound at a
relatively large volume, and even a hard acoustic diaphragm such as an iron plate can make it.
[0007]
Furthermore, the magnetostrictive actuator is also excellent in response speed, and the response
speed of the single magnetostrictive element is on the order of nanoseconds.
[0008]
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2
The prior art documents mentioned above are as follows.
JP, 2007-166027, A
[0009]
However, in the speaker apparatus shown in FIG. 18 which applies vibration to the flat acoustic
diaphragm 81 in the direction perpendicular to the plate surface, the vibration point of the
acoustic diaphragm 81 (point to which the vibration is applied) Pa is The amplitude is maximized,
and the amplitude of the vibration decreases at a point away from the excitation point Pa, so that
directivity is generated in sound reproduction and the sound image does not spread.
[0010]
Moreover, in the conventional speaker device shown in FIG. 18, when the length (the length of
the magnetostrictive element) of the magnetostrictive actuator 90 is increased in order to
increase the amplitude of vibration by the magnetostrictive actuator 90, the acoustic diaphragm
81 of the entire speaker device The size (thickness) in the thickness direction increases, and the
speaker device can not be made compact.
[0011]
On the other hand, in the speaker device shown in FIG. 19 which applies vibration in the
direction perpendicular to the end face of acoustic diaphragm 85, ie, in the direction of the plate
surface of acoustic diaphragm 85, the plate surface of acoustic diaphragm 85 as described above.
The sound image spreads uniformly over the whole, and the sound image is localized uniformly
over the entire acoustic diaphragm 85.
[0012]
However, in the conventional speaker device shown in FIG. 19, the hole for accommodating each
magnetostrictive actuator 90 is formed, the diameter is larger than the diameter of the acoustic
diaphragm 85, and the height in the central axis direction of the acoustic diaphragm 85 ( It is
necessary to provide a support having a large thickness) and store the respective
magnetostrictive actuators 90 in the respective holes, and the size of the entire speaker device
becomes considerably larger than the size of the acoustic diaphragm 85.
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3
[0013]
Therefore, according to the present invention, the sound image is uniformly spread over the
entire plate surface of the acoustic diaphragm, and the entire speaker device can be made
compact.
[0014]
A speaker device according to the present invention comprises: an acoustic diaphragm; and an
actuator mounted on the acoustic diaphragm such that one end and the other end in the drive
axis direction are present in the plate surface of the acoustic diaphragm. I assume.
[0015]
In the speaker apparatus according to the present invention having the above-described
configuration, one end and the other end of the actuator in the drive axis direction are present in
the plate surface of the acoustic diaphragm, whereby the acoustic diaphragm vibrates at a point
in the plate surface. In addition, since the longitudinal wave propagates from the excitation point
toward the outer end face (end face) of the acoustic diaphragm, the sound image spreads
uniformly over the entire surface of the acoustic diaphragm.
[0016]
Moreover, since the actuator is present in the plate surface of the acoustic diaphragm, the entire
speaker device does not increase in size compared to the size of the acoustic diaphragm, and the
entire speaker device is as compact as the size of the acoustic diaphragm. Can be
[0017]
[1.
First Embodiment: FIGS. 1 to 8] As a first embodiment, one magnetostrictive actuator is attached
to a flat acoustic diaphragm, and longitudinal waves of the acoustic diaphragm in the drive axis
direction of the magnetostrictive actuator are The case where the angle with respect to the
extension direction of the outer end face where vibration propagates is made right angle is
shown.
[0018]
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4
(1−1.
First Example of First Embodiment: FIGS. 1 to 3) FIG. 1 shows a first example of the speaker
device of the first embodiment, and FIG. 1 (A) is a plan view, FIG. ) Is a side view of a section of
the acoustic diaphragm.
[0019]
The acoustic diaphragm 10 is, for example, a square flat plate having a side length of 290 mm
and a thickness of 3 mm, and made of acrylic, and the square hole 12 is formed in the central
portion thereof.
[0020]
In this example, the inner end faces 13a, 13b, 13c and 13d facing the square holes 12 of the
acoustic diaphragm 10 are parallel to the outer end faces 11a, 11b, 11c and 11d of the
respective sides of the acoustic diaphragm 10.
[0021]
Then, the magnetostrictive actuator 30 is mounted in the square hole 12 by bringing the end of
the drive rod 35 at one end of the magnetostrictive actuator 30 into contact with the inner end
face 13a and bringing the base at the other end into contact with the inner end face 13c. ).
The base on the other end side may be bonded to the inner end face 13c with an adhesive or a
double-sided tape.
[0022]
In the magnetostrictive actuator 30, as an example, as shown in FIG. 2, a solenoid coil 32 for
applying a control electric field to the magnetostrictive element 31 is disposed around the rodlike magnetostrictive element 31, and a magnet is provided around the solenoid coil 32. 33 and
an yoke 34 are disposed, the drive rod 35 is connected to one end of the magnetostrictive
element 31, and the actuator body to which the fixed plate 36 is attached to the other end of the
magnetostrictive element 31; The outer case 39 is loaded so as to protrude to the outside of the
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5
case.
[0023]
Furthermore, in this example, the driving rod 35 is loaded with a damping material 37 made of
silicon rubber or the like, and a screw 38 is inserted behind the fixed plate 36 so that a
predetermined preload is applied to the magnetostrictive element 31. Be added.
As a result, the magnetostrictive element 31 can be expanded and contracted in accordance with
the control current supplied to the solenoid coil 32, centering on the state in which the
magnetostrictive element 31 is made to have a predetermined length.
[0024]
If the magnetostrictive element 31 is a giant magnetostrictive element, the magnetostrictive
actuator 30 can be a giant magnetostrictive actuator.
[0025]
When an audio signal is supplied to the solenoid coil 32 of the magnetostrictive actuator 30, that
is, when the magnetostrictive actuator 30 is driven by the audio signal, the magnetostriction of
the magnetostrictive actuator 30 is performed according to the audio signal. The element 31
expands and contracts in the direction indicated by the arrow 1, and the drive rod 35 is displaced
in the same direction, so that longitudinal vibration is applied to a point Pa at which the drive rod
35 abuts on the inner end face 13a of the acoustic diaphragm 10.
[0026]
This longitudinal wave propagates along the plate surface of the acoustic diaphragm 10 from the
point Pa to a point Pr on the outer end face 11a, but becomes a wave in which the longitudinal
wave and the transverse wave are mixed in the propagation process. Transverse waves are
emitted as sound waves in the direction perpendicular to the plate surface of
[0027]
The expansion and contraction of the magnetostrictive element 31 of the magnetostrictive
actuator 30 in the direction indicated by the arrow 1 causes the vibration of the longitudinal
wave also to a point Pc to which the base of the other end of the magnetostrictive actuator 30 on
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6
the inner end face 13c of the acoustic diaphragm 10 abuts. Be added.
[0028]
This longitudinal wave propagates along the plate surface of the acoustic diaphragm 10 to a
point on the outer end face 11c in phase with the longitudinal wave applied to the point Pa, but
in the propagation process, a wave in which the longitudinal wave and the transverse wave are
mixed As a result, a transverse wave is emitted as a sound wave in the direction perpendicular to
the plate surface of the acoustic diaphragm 10.
[0029]
Therefore, the sound image is uniformly spread over the entire plate surface of the acoustic
diaphragm 10, and the sound image is localized uniformly over the entire acoustic diaphragm 10.
[0030]
Moreover, when the acoustic diaphragm is very thin, it has been difficult to support the acoustic
diaphragm in the conventional support structure, but in the example of FIG. 1 of the present
invention, the square holes 12 are formed in the acoustic diaphragm 10 Thus, the acoustic
diaphragm 10 can be supported easily and reliably.
[0031]
Furthermore, even if the length of the magnetostrictive actuator 30 (length of the
magnetostrictive element 31) is increased in order to increase the amplitude of vibration due to
the magnetostrictive actuator 30, the size (thickness of the acoustic diaphragm 10 of the entire
speaker device (thickness) Because the same is true, as shown in FIG. 18, the entire speaker
device can be made compact as compared to the conventional speaker device in which vibration
in a direction perpendicular to the plate surface is applied to the flat acoustic diaphragm 81. .
[0032]
As a structure which supports the speaker apparatus of the example of FIG. 1, it can be set as a
structure as shown in FIG. 3 as an example.
[0033]
The example of FIG. 3 directly supports the acoustic diaphragm 10, and one end of each of the Lshaped angled supporting legs 41 and 42 is provided at the end of the acoustic diaphragm 10 on
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7
the outer end face 11c side. Damping members 43 and 44 made of silicon rubber or the like are
interposed between the acoustic diaphragm 10 and the acoustic diaphragm 10. The screws 45
and a nut 46 are attached to one surface and the other surface of the acoustic diaphragm 10,
respectively.
[0034]
The support legs 41 and 42 are mounted as they are on a desk or the like, or attached to a wall
or the like by screws or the like.
[0035]
By attaching the acoustic diaphragm 10 to the support legs 41 and 42 via the damping members
43 and 44, the vibration of the acoustic diaphragm 10 is transmitted to the desk or wall, and the
sound image is localized on the side of the desk or wall Can be prevented.
[0036]
(1−2.
Second Example of First Embodiment: FIG. 4 to FIG. 4 FIG. 4 shows a second example of the
speaker device of the first embodiment, and FIG. 4 (A) is a plan view, FIG. ) Is a side view of a
section of the acoustic diaphragm.
[0037]
Also in this example, as in the example of FIG. 1, the square holes 12 are formed in the square
flat acoustic diaphragm 10 and the magnetostrictive actuator 30 is attached to the square holes
12. Is provided with drive rods 35a and 35c on one end side and the other end side, the tip end
of drive rod 35a on one end side is in contact with inner end face 13a and the tip end of drive
rod 35c on the other end side contacts inner end face 13c. Get in touch.
[0038]
As an example, as shown in FIG. 5, in the magnetostrictive actuator 30 of this example, a solenoid
coil 32 for applying a control electric field to the magnetostrictive element 31 is disposed around
the rod-like magnetostrictive element 31. An actuator body having a magnet 33 and a yoke 34
arranged around it, a drive rod 35a connected to one end of the magnetostrictive element 31,
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8
and a drive rod 35c connected to the other end of the magnetostrictive element 31 is silicon
rubber for the drive rods 35a and 35c. Are loaded into the outer casing case 39 such that the tip
end portions of the drive rods 35a and 35c protrude outside the outer casing case 39.
[0039]
The outer casing case 39 is formed by dividing the case into one on the one end side and the
case into the other end, or into two half-cylindrical cases, and after each component is loaded,
both cases are formed. Or the case main body and the lid are formed in two parts, and after each
component is loaded, the lid is fitted to the case main body, or the like.
[0040]
In the speaker apparatus of the example of FIG. 4 having the above configuration, when the
magnetostrictive element 31 of the magnetostrictive actuator 30 is expanded and contracted in
the direction indicated by the arrow 1 by driving the magnetostrictive actuator 30 with an audio
signal, the inner end face of the acoustic diaphragm 10 The vibration of the longitudinal wave is
equally applied to the point Pa at which the drive rod 35a of 13a abuts and the point Pc at which
the drive rod 35c of the inner end face 13c abuts, so the inner end face 13a and the outer end
face 11a of the acoustic diaphragm 10 Similar sound waves are emitted from the plate surface
portion between and the plate surface portion between the inner end surface 13c and the outer
end surface 11c, and the sound image spreads more uniformly over the entire plate surface of
the acoustic diaphragm 10.
[0041]
As a structure which supports the speaker apparatus of the example of FIG. 4, it can be set as a
structure as shown in FIG. 6 as an example.
[0042]
The example of FIG. 6 directly supports the magnetostrictive actuator 30, and the
magnetostrictive actuator 30 is attached to the tip of the support 52 of the support 50 consisting
of the pedestal 51 and the support 52.
[0043]
The pedestal 51 is mounted as it is on a desk or the like, or attached to a wall surface or the like
by a screw or the like.
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9
[0044]
Even in the speaker device of the example of FIG. 1, as the support structure, the
magnetostrictive actuator 30 can be directly supported as in the example of FIG. 6, and
conversely, the speaker device of the example of FIG. However, as a support structure, it can be
set as the structure which supports the acoustic diaphragm 10 directly like the example of FIG.
[0045]
As compared with the support structure, the structure supporting the magnetostrictive actuator
30 directly as in the example of FIG. 6 is that the acoustic diaphragm 10 is not fixed and the
sound quality is improved. As such, it is preferable to a structure supporting the acoustic
diaphragm 10 directly.
[0046]
(1−3.
Third example of the first embodiment: FIG. 7) FIG. 7 shows a third example of the speaker
device of the first embodiment, FIG. 7 (A) is a plan view, and FIG. 7 (B) is an acoustic It is the side
view which made the part of the diaphragm a section.
[0047]
In this example, the magnetostrictive actuator 30 is mounted on the acoustic diaphragm 10 so
that the acoustic diaphragm 10 is sandwiched between one end and the other end of the
magnetostrictive actuator 30.
[0048]
Specifically, in this example, in the magnetostrictive actuator 30, the tip of the drive rod 35 at
one end and the base at the other end are shaped to sandwich the acoustic diaphragm 10, and
the corners of the acoustic diaphragm 10 The holes 12 make the portion closer to the inner end
surface 13b and the portion closer to the inner end surface 13d longer in the extension direction
of the inner end surfaces 13b and 13d than the central portion in the direction in which the
inner end surface 13b and the inner end surface 13d face each other.
[0049]
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10
Then, after the magnetostrictive actuator 30 is inserted from one surface side of the acoustic
diaphragm 10 into a part near the inner end face 13b of the square hole 12 or a part near the
inner end face 13d, the tip and the other end of the drive rod 35 on one end side The
magnetostrictive actuator 30 is slid along the plate surface of the acoustic diaphragm 10 so as to
sandwich the acoustic diaphragm 10 at the base of the side.
[0050]
The portion of the drive rod 35 on one end side of the magnetostrictive actuator 30 or the base
portion on the other end side sandwiching the acoustic diaphragm 10 may be screwed to the
acoustic diaphragm 10.
[0051]
The magnetostrictive actuator 30 may have drive rods at one end and the other end as shown in
FIG.
[0052]
(1−4.
Resonance due to Reflected Wave: FIG. 8) In the speaker device of the example of FIG. 1, FIG. 4 or
FIG. 7, the angle α of the magnetostrictive actuator 30 in the drive axis direction with respect to
the extension direction of the outer end face 11a of the acoustic diaphragm 10 shown by arrow 1
is Since it is perpendicular, the longitudinal wave propagated from the excitation point Pa of the
acoustic diaphragm 10 to the point Pr on the outer end face 11a is reflected in the drive axis
direction of the magnetostrictive actuator 30 at the point Pr and propagates to the point Pr
There is a resonance between the and the longitudinal wave reflected at point Pr.
The same applies to the outer end face 11 c side.
[0053]
The measurement result of the resonance by this reflected wave is shown in FIG.
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11
As described above, the magnetostrictive actuator 30 is mounted as in the example of FIG. 1 with
the acoustic diaphragm 10 as a square flat plate having a side length of 290 mm and a thickness
of 3 mm, and in the anechoic chamber, This is the result of measuring the SPL (sound pressure
level) and the second-order distortion and third-order distortion by supplying an audio signal of
2 Vrms to the magnetostrictive actuator 30.
[0054]
It was found that the resonance due to the reflected wave is increased around 15000 Hz in SPL
and around 5000 Hz in third-order distortion.
[0055]
In order to reduce the resonance due to the reflected wave, the speaker device may be
configured as shown below as a second embodiment.
[0056]
[2.
Second Embodiment: FIGS. 9 to 12] As a second embodiment, a case where one magnetostrictive
actuator is attached to a flat acoustic diaphragm and the resonance due to the above-mentioned
reflected wave is reduced is shown.
[0057]
(2−1.
First Example of Second Embodiment: FIG. 9 and FIG. 10 FIG. 9 shows a first example of the
speaker device of the second embodiment.
[0058]
In this example, as in the example of FIG. 1 of the first embodiment, the square hole 12 is formed
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12
in the square flat acoustic diaphragm 10, but the inner end faces 13a, 13b, 13c and the square
hole 12 are exposed. 13d is not parallel to the outer end faces 11a, 11b, 11c and 11d of each
side of the acoustic diaphragm 10 but inclined 30 °, and the outer end face of the acoustic
diaphragm 10 in the drive axis direction indicated by the arrow 1 of the magnetostrictive
actuator 30 The angle α with respect to the extension direction of 11a is 60 ° instead of a right
angle.
[0059]
In this example, the longitudinal wave propagated from the excitation point Pa of the acoustic
diaphragm 10 to the point Pr on the outer end face 11a is not mainly in the drive axis direction
of the magnetostrictive actuator 30 at the point Pr, but the outer end face of the acoustic
diaphragm 10 Since the light is reflected in the direction toward 11b, the resonance due to the
reflected wave is reduced.
The same applies to the outer end face 11 c side.
[0060]
FIG. 10 shows the measurement result in the case of this example.
As described above, the magnetostrictive actuator 30 is mounted as in the example of FIG. 9 with
the acoustic diaphragm 10 as a square flat plate having a side length of 290 mm and a thickness
of 3 mm, and in the anechoic chamber, This is the result of measuring the SPL (sound pressure
level) and the second-order distortion and third-order distortion by supplying an audio signal of
2 Vrms to the magnetostrictive actuator 30.
[0061]
As apparent from comparison with FIG. 8 which is the measurement result in the case of the
example of FIG. 1, it is understood that the resonance by the reflected wave is significantly
reduced in the example of FIG.
[0062]
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13
When making the acoustic diaphragm 10 square as in the example of FIG. 9, the longitudinal
wave reflected in the drive axis direction of the magnetostrictive actuator 30 decreases as the
angle α decreases within the range of 45 ° or more, and the reflected wave Resonance is
reduced.
[0063]
(2−2.
Second Example of Second Embodiment: FIG. 11 FIG. 11 shows a second example of the speaker
device of the second embodiment.
[0064]
In this example, as in the example of FIG. 1 of the first embodiment, the angle α with respect to
the extension direction of the outer end face 11a of the acoustic diaphragm 10 in the drive axis
direction indicated by the arrow 1 of the magnetostrictive actuator 30 is made perpendicular.
The outer end faces 11a, 11b, 11c and 11d of the acoustic diaphragm 10 are made to be uneven
surfaces (waved surfaces).
[0065]
In this example, the longitudinal wave propagated from the excitation point Pa of the acoustic
diaphragm 10 to the point Pr on the outer end face 11 a is dispersed in the reflection direction at
the point Pr, reflected, and reflected in the drive axis direction of the magnetostrictive actuator
30 Since the longitudinal waves are reduced, the resonance due to the reflected waves is
reduced.
The same applies to the outer end face 11 c side.
[0066]
Since the longitudinal waves applied to the points Pa and Pc propagate to the outer end faces
11a and 11c, only the outer end faces 11a and 11c may be made uneven.
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14
[0067]
(2−3.
Third example of the second embodiment: FIG. 12) Although the above examples are cases where
the acoustic diaphragm is square, the acoustic diaphragm may be, for example, circular.
FIG. 12 shows an example in that case.
[0068]
In this example, the acoustic diaphragm 10 is formed in a disk shape, and a square hole 12
facing the inner end faces 13a, 13b, 13c and 13d is formed at the center portion, and the
magnetostrictive actuator 30 is attached to the square hole 12 Let the outer end surface 11 of
the diaphragm 10 be an uneven surface.
[0069]
Also in this example, as in the example of FIG. 11, the longitudinal wave propagated from the
excitation point Pa of the acoustic diaphragm 10 to the point Pr on the outer end face 11 has its
reflection direction dispersed and reflected at the point Pr, and the magnetostrictive actuator
Since the longitudinal waves reflected in the direction of the drive axis 30 are reduced, the
resonance due to the reflected waves is reduced.
[0070]
[3.
Third Embodiment: FIG. 13] As a third embodiment, the case where the acoustic diaphragm is
curved is shown.
[0071]
FIG. 13 shows an example of the speaker device according to the third embodiment, FIG. 13 (A) is
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15
a side sectional view showing a state where the speaker device is suspended from the ceiling, and
FIG. 13 (B) is a plan view.
[0072]
In this example, the acoustic diaphragm 10 is curved in a hemispherical shape, and the square
hole 12 is formed in the center, and the magnetostrictive actuator 30 attached with the member
61 for suspension is attached to the square hole 12 and suspended. The magnetostrictive
actuator 30 is suspended from the ceiling 69 together with the acoustic diaphragm 10 by the
lowering wire 62.
[0073]
In this example, the magnetostrictive actuator 30 is provided with drive rods 35 a and 35 c at
one end and the other end as shown in FIG. 5.
[0074]
Since the speaker device of the present invention can be made lightweight and the acoustic
diaphragm can be supported by the actuator, it can be configured as a ceiling suspension type as
in this example and can be suspended from the ceiling.
[0075]
In order to reduce the resonance due to the longitudinal wave reflected by the outer end face
(terminal face) 11 of the acoustic diaphragm 10, the outer end face 11 may be a rough surface.
[0076]
[4.
Fourth Embodiment: FIGS. 14 and 15] As a fourth embodiment, the case where the acoustic
diaphragm is cylindrical is shown.
[0077]
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16
(4−1.
First Example of Fourth Embodiment: FIG. 14 FIG. 14 shows a first example of the speaker device
of the fourth embodiment.
[0078]
In this example, the acoustic diaphragm 10 is formed in a cylindrical shape having openings at
both ends, a square hole 12 is formed in a portion close to the one end face 15, and the
magnetostrictive actuator 30 is shown in the square hole 12. The axial direction is inclined with
respect to the central axis direction indicated by the straight line 3 of the acoustic diaphragm 10
and the direction indicated by the straight line 5 orthogonal thereto so that the tip of the drive
rod 35 faces the direction of the other end face 16 of the acoustic diaphragm 10 Installing.
[0079]
Furthermore, this example corresponds to the angle α in the example of FIG. 9 of the second
embodiment, and the angle β with respect to the direction indicated by the straight line 5 in the
drive axis direction shown by the arrow 1 of the magnetostrictive actuator 30 is smaller than 90
°. It is a case to make it relatively large.
[0080]
When the acoustic diaphragm 10 is vertically supported, for example, the one end surface 15
side is the lower side, the other end surface 16 side is the upper side, and the direction indicated
by the straight line 5 is the horizontal direction.
When the acoustic diaphragm 10 is horizontally supported, the direction indicated by the
straight line 5 is the vertical direction.
[0081]
In this example, as in the examples shown in FIG. 1 and the like, the sound image is uniformly
spread over the entire plate surface of the acoustic diaphragm 10, and the sound image is
localized uniformly over the entire acoustic diaphragm 10.
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17
[0082]
Moreover, since the angle β is made smaller than 90 °, the other end face (outside end face on
the other end side) 16 and one end face (outside of one end side) of the acoustic diaphragm 10
as in the example of FIG. 9 of the second embodiment. The resonance due to the longitudinal
wave reflected by the end face 15 is reduced.
[0083]
Furthermore, it is not necessary to mount the magnetostrictive actuator 30 in the square holes
12 of the acoustic diaphragm 10 and to provide a support having a hole for accommodating the
magnetostrictive actuator as in the conventional speaker device shown in FIG. The entire device
can be made as compact as the size of the acoustic diaphragm 10.
[0084]
As a structure which supports the speaker apparatus of this example, it can be set as the
structure similar to the structure shown in FIG. 3 as an example.
[0085]
Specifically, for example, one end of an L-shaped angled support leg at a plurality of equiangular
intervals in the circumferential direction of the acoustic diaphragm 10 at the end on the one end
face 15 side of the acoustic diaphragm 10, respectively A damping material made of silicone
rubber or the like is interposed between the acoustic diaphragm 10 and the acoustic diaphragm
10, and is attached to the outer surface of the acoustic diaphragm 10 with a screw and a nut.
[0086]
Note that one end, the other end, or both ends of the acoustic diaphragm 10 may be bottomed.
[0087]
(4−2.
Second Example of Fourth Embodiment: FIG. 15 FIG. 15 shows a second example of the speaker
device of the fourth embodiment.
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18
[0088]
Also in this example, as in the example of FIG. 14, the acoustic diaphragm 10 is cylindrical, and
the square hole 12 is formed in a portion close to the one end face 15, and the magnetostrictive
actuator 30 is mounted. The angle .beta. Is made larger than 0.degree. But relatively small.
[0089]
In this example, since the angle β is small, the vibration of the longitudinal wave applied to the
point Pa at which the drive rod 35 of the magnetostrictive actuator 30 of the acoustic diaphragm
10 abuts is an acoustic diaphragm along the plate surface of the acoustic diaphragm 10 10,
propagates to the other end face 16 of the acoustic diaphragm 10 while spirally winding.
Therefore, as compared with the example of FIG. 14, the sound image spreads more uniformly
over the entire plate surface of the acoustic diaphragm 10, and the sound image is localized more
uniformly over the entire sound diaphragm 10.
[0090]
Moreover, since the angle β is small, the resonance due to the longitudinal wave reflected by the
other end face 16 and the one end face 15 of the acoustic diaphragm 10 is further reduced.
[0091]
[5.
Fifth Embodiment: FIGS. 16 and 17] A fifth embodiment shows a case where two
magnetostrictive actuators are attached to one (one) acoustic diaphragm to perform stereo
reproduction.
[0092]
(5−1.
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19
First Example of Fifth Embodiment: FIG. 16 FIG. 16 shows a first example of the speaker device
of the fifth embodiment.
[0093]
In this example, two square holes 12L and 12R are formed in parallel in a portion close to the
outer end face 11c on one side of the acoustic diaphragm 10 as a square or a rectangle, and the
driving rods 35L and 12R are respectively formed in the square holes 12L and 12R. The
magnetostrictive actuators 30L and 30R provided with 35R are mounted such that the drive axis
directions indicated by the arrows 1L and 1R are parallel and the tips of the drive rods 35L and
35R face the outer end face 11a opposite to the outer end face 11c.
[0094]
The magnetostrictive actuator 30L is driven by the audio signal of the left channel in the stereo
audio signal, and the magnetostrictive actuator 30R is driven by the audio signal of the right
channel in the stereo audio signal.
[0095]
Therefore, the vibration of the longitudinal wave by the sound signal of the left channel and the
right channel propagates along the same plane of the acoustic diaphragm 10, and the stereo
sound is reproduced.
[0096]
In order to reduce the resonance due to the longitudinal waves reflected by the outer end faces
11a and 11c of the acoustic diaphragm 10, the outer end faces 11a and 11c may be made
uneven.
[0097]
(5−2.
Second Example of Fifth Embodiment: FIG. 17 FIG. 17 shows a second example of the speaker
device of the fifth embodiment.
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[0098]
In this example, the acoustic diaphragm 10 is formed as a square or a rectangle, and two square
holes 12L and 12R are formed at an angle to the other in a portion near the outer end face 11c
of one side, and the square holes 12L and 12R are Drive axis directions shown by arrows 1L and
1R respectively tilt the magnetostrictive actuators 30L and 30R provided with drive rods 35L
and 35R, respectively, with respect to each other, and the tips of the drive rods 35L and 35R are
outside on the opposite side to the outer end face 11c It is mounted so as to face a portion close
to the corner of the acoustic diaphragm 10 of the end face 11a.
[0099]
The magnetostrictive actuator 30L is driven by the audio signal of the left channel in the stereo
audio signal, and the magnetostrictive actuator 30R is driven by the audio signal of the right
channel in the stereo audio signal.
[0100]
Therefore, the vibration of the longitudinal wave by the sound signal of the left channel and the
right channel propagates along the same plane of the acoustic diaphragm 10, and the stereo
sound is reproduced.
[0101]
Moreover, in this example, the longitudinal wave applied to the acoustic diaphragm 10 by the
magnetostrictive actuator 30L in response to the audio signal of the left channel and the
longitudinal wave applied to the acoustic diaphragm 10 by the magnetostrictive actuator 30R in
response to the audio signal of the right channel. Since the spread between the two becomes
larger as it approaches the outer end face 11a, the stereo feeling becomes higher compared to
the example of FIG.
[0102]
Further, in this example, since the angle of the drive shaft direction of the magnetostrictive
actuators 30L and 30R with respect to the extension direction of the outer end face 11a of the
acoustic diaphragm 10 is not perpendicular, as in the example of FIG. 9 of the second
embodiment The resonance due to waves is reduced.
[0103]
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[6.
Other Examples and Embodiments] (6-1.
Regarding the Acoustic Diaphragm) The shape of the acoustic diaphragm in the case of making
the acoustic diaphragm in a flat plate shape may be a polygonal shape such as a triangle or a
pentagon, or a curved shape such as an oval other than a square or a circle.
[0104]
The overall shape of the acoustic diaphragm can be a box shape such as a cubic shape or a
rectangular solid shape, a pyramid shape such as a triangular pyramid shape or a quadrangular
pyramid shape, a cone shape, or a spherical shape.
In the case of a box or pyramid, each surface is flat (planar), but not flat as a whole.
Similar to the hemispherical shape in the example of FIG. 13, the conical shape and the spherical
shape are examples in the case of the curved shape.
[0105]
As the shape of the acoustic diaphragm in the case of making the acoustic diaphragm cylindrical,
in addition to the cylindrical shape in the example of FIG. 14 or FIG. 15, a semi-cylindrical shape
or an elliptical cylindrical shape, or a cross section perpendicular to the central axis direction is
triangular It may be in the shape of a square tube which is a polygon such as a square or a
square.
The semi-cylindrical shape and the elliptical cylindrical shape are also examples of cases where
they are curved as in the cylindrical shape.
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In the case of a square tube, each surface is flat (planar), but not flat as a whole.
[0106]
The hole formed in the acoustic diaphragm is not limited to a square hole, but may be a circular
hole or an oval hole as long as an actuator such as a magnetostrictive actuator can be mounted.
[0107]
The material of the acoustic diaphragm is not limited to acrylic, and glass or the like can also be
used.
[0108]
(6−2.
Regarding the Actuator) In each of the above examples, a magnetostrictive actuator (including a
super magnetostrictive actuator) is used as an actuator, but a piezoelectric actuator (an actuator
using a piezoelectric element) or the like may be used as an actuator.
[0109]
(6−3.
Embodiment as Speaker System) The examples of FIGS. 16 and 17 shown as the fifth
embodiment are for stereo reproduction by one speaker device in which two magnetostrictive
actuators 30L and 30R are mounted on one acoustic diaphragm 10. In this case, two speaker
devices such as in the example of FIG. 1 or 9 are provided for the left and right channels, and the
drive axis direction of the actuator of the speaker device for the left channel and the drive of the
actuator of the speaker device for the right channel The two speaker devices may be arranged to
be parallel to each other or to intersect with each other to perform stereo reproduction.
[0110]
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It is a figure which shows the 1st example of the speaker apparatus of 1st Embodiment.
It is a figure showing an example of a magnetostrictive actuator.
It is a figure which shows an example of the support structure of a speaker apparatus.
It is a figure which shows the 2nd example of the speaker apparatus of 1st Embodiment.
It is a figure showing an example of a magnetostrictive actuator.
It is a figure which shows an example of the support structure of a speaker apparatus.
It is a figure which shows the 3rd example of the speaker apparatus of 1st Embodiment.
It is a figure which shows the measurement result of the sound pressure level of the speaker
apparatus of the example of FIG.
It is a figure which shows the 1st example of the speaker apparatus of 2nd Embodiment.
It is a figure which shows the measurement result of the sound pressure level of the speaker
apparatus of the example of FIG.
It is a figure which shows the 2nd example of the speaker apparatus of 2nd Embodiment.
It is a figure which shows the 3rd example of the speaker apparatus of 2nd Embodiment.
It is a figure which shows an example of the speaker apparatus of 3rd Embodiment.
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It is a figure which shows the 1st example of the speaker apparatus of 4th Embodiment.
It is a figure which shows the 2nd example of the speaker apparatus of 4th Embodiment.
It is a figure which shows the 1st example of the speaker apparatus of 5th Embodiment.
It is a figure which shows the 2nd example of the speaker apparatus of 5th Embodiment.
It is a figure which shows an example of the conventional speaker apparatus.
It is a figure which shows the other example of the conventional speaker apparatus.
Explanation of sign
[0111]
The main parts are all described in the figure, so they are omitted here.
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