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JP2009164991

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DESCRIPTION JP2009164991
An object of the present invention is to make it possible to always obtain a suitable
magnetostrictive characteristic and obtain a constant sound quality and volume. SOLUTION: A
magnetostrictive actuator 30 and a coil spring 51 are inserted into a storage portion 23 which is
a hole penetrating in the vertical direction of a base casing 20, and a screw 52 is further made. It
abuts on the lower end surface 12 of the diaphragm 10 and is inserted to a position where the
coil spring 51 is compressed by a predetermined amount. For the amount of contraction of the
coil spring 51, the sum of the preload F1 applied to the magnetostrictive element 31 in the
magnetostrictive actuator 30 and the load F2 applied to the magnetostrictive element 31 by the
coil spring 51 is an optimum value. The magnetic field range in which the magnetostrictive value
linearly changes with respect to the change is the widest, and the characteristic is set such that
the characteristic in which the change in the magnetostriction value with respect to the change in
the control magnetic field in the magnetic field range becomes the largest. [Selected figure]
Figure 2
Speaker device
[0001]
The present invention relates to a speaker device that reproduces sound by applying vibration to
an acoustic diaphragm by a magnetostrictive actuator.
[0002]
As a speaker device, one that applies vibration to an acoustic diaphragm by a magnetostrictive
actuator to reproduce sound is considered.
04-05-2019
1
[0003]
Specifically, in Patent Document 1 (Japanese Patent Laid-Open No. 2007-166027), for example,
as shown in FIG. 8, a cylindrical acoustic diaphragm 110 made of acrylic or the like is vertically
supported, and the acoustic diaphragm 110 is A plurality of magnetostrictive actuators 130 are
disposed on the lower end side, and drive rods 135 of the respective magnetostrictive actuators
130 are brought into contact with the lower end surface 112 of the acoustic diaphragm 110, and
the acoustic diaphragm 110 is in the direction perpendicular to the lower end surface 112 That
is, it is shown to apply vibration in the plate surface direction.
[0004]
In this case, the lower end surface 112 of the acoustic diaphragm 110 is excited by the
longitudinal wave, but the vibrational elastic wave propagates in the direction of the plate surface
of the acoustic diaphragm 110 and becomes a wave in which the longitudinal wave and the
transverse wave are mixed. A sound wave is emitted by the transverse wave in the direction
perpendicular to the plate surface of the diaphragm 110, and a sound field having a sense of
spreading can be obtained.
[0005]
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.
In addition, since the magnetostrictive element generates a large stress when the shape changes,
even a small magnetostrictive actuator can make the acoustic diaphragm ring at a relatively large
volume, and even a hard acoustic diaphragm such as an iron plate can ring. be able to.
[0006]
Furthermore, the magnetostrictive actuator is also excellent in response speed, and the response
speed of the magnetostrictive element alone is on the nanosecond order.
[0007]
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The prior art documents mentioned above are as follows.
JP, 2007-166027, A
[0008]
A structure as shown in FIG. 9 can be considered as a structure for supporting the
magnetostrictive actuator 130 in the speaker device shown in FIG.
[0009]
Specifically, when the acoustic diaphragm 110 is cylindrical, a disk-shaped base casing 120
having a certain height (thickness), which is larger than the outer diameter of the acoustic
diaphragm 110, is provided. The lower end portion of the acoustic diaphragm 110 is attached to
the base housing 120 at four positions of the upper surface 121 of the upper surface 121 at
equal angular intervals by an attachment such as an L-shaped angle omitted in FIG.
[0010]
In the base housing 120, storage portions 123, which are holes vertically penetrating from the
upper surface 121 to the lower surface 122, are formed at four positions at equal angular
intervals between the attachment positions described above, The magnetostrictive actuators 130
are respectively inserted into the respective storage portions 123 from the lower side with the
respective drive rods 135 directed upward.
[0011]
Furthermore, the lower surface 122 of the base housing 120 holds the respective
magnetostrictive actuators 130 inserted in the respective housing portions 123, and the tips of
the respective drive rods 135 are in contact with the lower end surface 112 of the acoustic
diaphragm 110. The leaf spring 151 is attached by screws 152 and 153 so as to be in contact.
[0012]
In the magnetostrictive actuator 130, a solenoid coil 132 is disposed around a rod-like
magnetostrictive element 131, a magnet 133 and a yoke 134 are disposed around the solenoid
coil 132, and a drive rod 135 is connected to one end of the magnetostrictive element 131. The
actuator main body having the fixed disc 136 attached to the other end of the electrode 131 is
loaded in the outer casing case 139 such that the tip end of the drive rod 135 protrudes to the
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outside of the outer casing case 139.
[0013]
Further, a damping material 137 made of silicon rubber or the like is loaded on the drive rod
135, and a screw 138 is inserted behind the fixed plate 136 to apply a preload F 1 to the
magnetostrictive element 131.
[0014]
As described above, by applying the preload F1 to the magnetostrictive element 131 by the
magnetostrictive actuator 130, it is possible to prevent the destruction of the magnetostrictive
element 131 due to the repeated stress at the time of driving the actuator.
[0015]
Furthermore, when the control current is supplied to the solenoid coil 132 and the control
magnetic field is applied to the magnetostrictive element 131, the characteristics of the
magnetostriction value with respect to the control magnetic field largely change depending on
the load applied to the magnetostrictive element 131 and a certain load is applied. At this time,
the magnetic field range in which the magnetostrictive value changes linearly with the change in
the control magnetic field is the widest, and the change in the magnetostrictive value with the
change in the control magnetic field in the magnetic field range is the largest.
[0016]
Therefore, the load at this time is taken as the optimum value, and the characteristic of the
magnetostriction value with respect to the control magnetic field at this time is made as the
optimum magnetostriction characteristic.
[0017]
Specifically, for example, when the load applied to the magnetostrictive element 131 is 105 kg /
cm <2>, the magnetic field range in which the magnetostriction value changes linearly with the
change of the control magnetic field becomes the widest, and the magnetic field The change of
the magnetostriction value with respect to the change of the control magnetic field in the range
is the largest.
[0018]
Therefore, in the magnetostrictive actuator 130, for example, the diameter of the
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magnetostrictive element 131 is 2 mm, and the cross-sectional area is 3.14 mm <2> so that the
preload F1 is 105 kg / cm <2> of the optimum value. At the same time, the degree of tightening
of the screw 138 is adjusted so that a load of 3.30 kg is applied to the magnetostrictive element
131.
[0019]
However, in the configuration shown in FIG. 9, the magnetostrictive elements are caused by
dimensional or adjustment variations among a large number of manufactured speaker devices, or
among a plurality of magnetostrictive actuators or storage portions of one speaker device. The
load applied to 131 changes largely, and the magnetostriction characteristic changes greatly.
[0020]
For example, when the total length of magnetostrictive actuator 130 (the length from the tip of
drive rod 135 to the bottom of screw 138) is shorter than the design value, or the distance from
lower end surface 112 of acoustic diaphragm 110 to lower surface 122 of base housing 120 Is
longer than the design value, the contact pressure of the drive rod 135 to the acoustic diaphragm
110 decreases, and in some cases, a slight gap between the tip of the drive rod 135 and the
lower end surface 112 of the acoustic diaphragm 110 It occurs.
[0021]
Therefore, even if the preload F1 is set to the above optimum value, the load applied to the
magnetostrictive element 131 decreases with respect to the above optimum value, and the
magnetostriction characteristic deviates from the above optimum magnetostriction characteristic.
.
[0022]
Conversely, if the total length of the magnetostrictive actuator 130 is longer than the designed
value, or if the distance from the lower end surface 112 of the acoustic diaphragm 110 to the
lower surface 122 of the base housing 120 is shorter than the designed value, the
magnetostrictive actuator By pressing 130 against the acoustic diaphragm 110, a load larger
than the preload F1 is applied to the magnetostrictive element 131.
[0023]
Therefore, even if the preload F1 is set to the above optimum value, the load applied to the
magnetostrictive element 131 increases relative to the above optimum value, and the
magnetostriction characteristic deviates from the above optimum magnetostriction characteristic.
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.
[0024]
Further, in the configuration of FIG. 9, when the portion of the lower end surface 112 of the
acoustic diaphragm 110 in contact with the drive rod 135 is abraded by driving the
magnetostrictive actuator 130 for a long time such as 1000 hours or more, as described above.
The same result as in the case where the distance from the lower end surface 112 of the acoustic
diaphragm 110 to the lower surface 122 of the base housing 120 is longer than the designed
value is obtained.
[0025]
Furthermore, in the configuration of FIG. 9, if the tightening degree of the screw 152 and the
tightening degree of the screw 153 are different such that the screw 152 is tightened loose and
the screw 153 is tightened tightly, the axial direction of the magnetostrictive actuator 130 Is
inclined relative to the vertical direction, and the direction and the magnitude of the vibration
applied to the acoustic diaphragm 110 become different from the intended direction and
magnitude, and the desired sound quality and volume can not be obtained.
[0026]
Therefore, the present invention relates to a speaker device that reproduces sound by applying
vibration to an acoustic diaphragm by a magnetostrictive actuator, regardless of variations in
dimensions or adjustment of the magnetostrictive actuator, the support, etc., wear of the acoustic
diaphragm, etc. The preferred magnetostrictive characteristics are always obtained, and a certain
sound quality and volume are obtained.
[0027]
According to another aspect of the present invention, there is provided a speaker device
comprising: an acoustic diaphragm; a support having a hole-shaped storage portion facing the
acoustic diaphragm; a magnetostrictive element; and a drive rod connected to one end of the
magnetostrictive element; A magnetostrictive actuator for applying vibration to the acoustic
diaphragm, the drive rod being inserted into the housing so as to abut the acoustic diaphragm,
and in the housing, on the opposite side of the magnetostrictive actuator from the drive rod side
And a spring for pressing the magnetostrictive actuator inserted toward the acoustic diaphragm
side to apply a load to the magnetostrictive element.
[0028]
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In the speaker apparatus according to the present invention having the above-described
configuration, the magnetostrictive actuator of the spring may be disposed on the acoustic
diaphragm side, depending on the dimensional or adjustment variation of the magnetostrictive
actuator, the support, etc., or the wear of the acoustic diaphragm. The pressing force increases
within the preferred range, and in other cases the pressing force of the spring's magnetostrictive
actuator toward the acoustic diaphragm decreases within the preferred range, and the load
applied to the magnetostrictive element is within the preferred range. Increase or decrease, and
the magnetostrictive characteristics change within a preferred range.
[0029]
Therefore, regardless of the dimensional or adjustment variation of the magnetostrictive
actuator, the support, etc., the wear of the acoustic diaphragm, etc., it is possible to always obtain
suitable magnetostrictive characteristics, and to obtain a certain sound quality and volume.
[0030]
Moreover, since the spring is inserted into the hole-like housing and pushes the center of the
magnetostrictive actuator to the acoustic diaphragm side, the axial direction of the
magnetostrictive actuator is inclined with respect to the desired direction and is applied to the
acoustic diaphragm The direction and magnitude of vibration do not differ from the intended
direction and magnitude.
[0031]
As described above, according to the present invention, suitable magnetostrictive characteristics
can always be obtained regardless of the dimensional or adjustment variations of the
magnetostrictive actuator, the support, etc., the wear of the acoustic diaphragm, etc. And you can
get the volume.
[0032]
[1.
First Embodiment: FIG. 1 to FIG. 5] As a first embodiment, a hole penetrating as a housing portion
is formed in a base casing as a support, and a magnetostrictive actuator and a spring as an
example in the hole. The case of loading a coil spring and a member for compressing the coil
spring is shown.
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[0033]
(1−1.
Example of Overall Configuration of Speaker Device: FIG. 1) FIG. 1 shows an example of the
speaker device of the first embodiment, and FIG. 1 (A) is a top view (view from above), FIG. 1 (B)
These are the side views which made the part of line BB of FIG. 1 (A) the cross section about the
base housing | casing as a support body.
[0034]
The acoustic diaphragm 10 is formed of, for example, acrylic and has a cylindrical shape with
both ends open, and has a thickness of 2 mm, a diameter of 10 cm, and a length (height) of 100
cm.
[0035]
The base housing 20 is formed, for example, of aluminum in a disk shape having a certain height
(thickness), which is larger than the outer diameter of the acoustic diaphragm 10.
[0036]
The acoustic diaphragm 10 has an end face on one end side as the upper end face 11 and an end
face on the other end as the lower end face 12 so that its axial direction is vertical and its central
axis is aligned with the central axis of the base housing 20 , Mounted on the upper surface 21 of
the base housing 20.
[0037]
Specifically, one end of the L-shaped angle 41 is made to interpose the damping material 42
made of silicon rubber between it and the base casing 20 at four positions of the equiangular
interval of the upper surface 21 of the base casing 20, respectively. And the damping members
44 and 45 made of silicone rubber are respectively interposed on the inside and the outside of
the acoustic diaphragm 10, and the other end of the L-shaped angle 41 is screwed It is attached
to the lower end of the acoustic diaphragm 10 by a nut 47.
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[0038]
By attaching the acoustic diaphragm 10 to the base casing 20 via the damping members 44, 45
and 42 in this manner, the vibration of the acoustic diaphragm 10 is transmitted to the base
casing 20 and a sound image is formed on the base casing 20 side. It is possible to prevent
localization.
[0039]
Furthermore, in the base housing 20, a storage portion which is a hole vertically penetrating
from the upper surface 21 to the lower surface 22 at four positions at equal angular intervals
between the attachment positions of the L-shaped angle 41. Form 23.
[0040]
The magnetostrictive actuators 30 are respectively inserted from the lower side with the
respective drive rods 35 directed upward into the respective housing portions 23 of the base
housing 20, and the magnetostrictive actuators 30 in the respective housing portions 23 are
further provided below. The coil spring (coil spring) 51 and the screw 52 are respectively
inserted into the side.
[0041]
The screw 52 is inserted into the housing 23 until the tip of the drive rod 35 abuts on the lower
end surface 12 of the acoustic diaphragm 10 and the coil spring 51 is compressed by a
predetermined amount.
[0042]
Legs 27 are formed on the lower surface 22 of the base housing 20 at three positions at equal
angular intervals.
[0043]
In addition, if necessary, in order to increase the degree of sealing between the acoustic
diaphragm 10 and the base housing 20, the magnetostriction between the lower end surface 12
of the acoustic diaphragm 10 and the upper surface 21 of the base housing 20 is At a position
excluding the position of the drive rod 35 of the actuator 30, the damping material 13 made of
silicon rubber or the like is interposed.
[0044]
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When the magnetostrictive actuator 30 is driven by an audio signal in the speaker device of the
example of FIG. 1 having the above configuration, the magnetostrictive element described later of
the magnetostrictive actuator 30 expands and contracts in the axial direction according to the
audio signal. Are displaced in the same direction, and longitudinal wave vibration is applied to
the lower end surface 12 of the acoustic diaphragm 10.
[0045]
This longitudinal wave propagates along the plate surface of the acoustic diaphragm 10 to the
upper end surface 11, but in the process of propagation, it becomes a wave in which the
longitudinal wave and the transverse wave are mixed, and is perpendicular to the plate surface of
the acoustic diaphragm 10. A transverse wave is emitted as a sound wave in the direction.
[0046]
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.
[0047]
By driving each magnetostrictive actuator 30 with the same audio signal, it is possible to obtain
nondirectionality, but each magnetostrictive actuator 30 is obtained from audio signals of
different channels or from the same audio signal. By driving with audio signals having different
levels, delay times, or frequency characteristics, it is possible to obtain a more extensive sound
field.
[0048]
As shown in FIG. 1A, the central portion of the base housing 20 is an opening 29, and the
speaker unit of the dynamic speaker is attached to the opening 29, for example, with the front
side facing downward. The diaphragm 10 and the magnetostrictive actuator 30 can function as
tweeters that handle the high frequency side of the audio frequency band, and the dynamic
speaker can also function as a woofer that handles the low frequency side of the audio frequency
band.
[0049]
(1−2.
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10
First Example: FIGS. 2 to 4 As a first example of the first embodiment, the case where a preload is
applied as a magnetostrictive actuator is shown.
[0050]
<Configuration: FIG. 2> In FIG. 2, the state in which the magnetostrictive actuator 30, the coil
spring 51, and the screw 52 are loaded in the respective housing portions 23 of the base housing
20 of the speaker device of the example of FIG. Indicates
[0051]
In the magnetostrictive actuator 30, a solenoid coil 32 is disposed around a bar-shaped
magnetostrictive element 31, a magnet 33 and a yoke 34 are disposed around the solenoid coil
32, a drive rod 35 is connected to one end of the magnetostrictive element 31, The actuator main
body with the fixed board 36 attached to the other end of 31 is loaded in an outer casing case 39
made of, for example, aluminum so that the tip end of the drive rod 35 protrudes to the outside
of the outer casing case 39.
[0052]
Furthermore, a damping material 37 made of silicon rubber or the like is loaded on the drive rod
35, and a screw 38 is inserted behind the fixed plate 36 to apply a preload F 1 to the
magnetostrictive element 31.
[0053]
The magnetostrictive actuator 30 to which the preload F1 is applied is, for example, a person
who manufactured the magnetostrictive actuator 30 after another manufacture (manufacturer)
manufactures the magnetostrictive actuator 30 and the speaker device. When testing the
magnetostrictive actuator 30, or the like, there is an advantage that destruction of the
magnetostrictive element 31 can be prevented.
[0054]
When an audio signal is supplied to the solenoid coil 32 and the magnetostrictive actuator 30 is
driven by the audio signal, the higher the range, the smaller the magnetostrictive element 31 is
reproduced, and the diameter of the magnetostrictive element 31 is 2 mm, for example. Make it
smaller.
04-05-2019
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[0055]
In the example of FIG. 2, with the acoustic diaphragm 10 supported by the base housing 20 as
described above, the magnetostrictive actuator 30 having the above configuration is inserted into
the housing 23, and the coil spring 51 is further housed in the housing 23. Then, the coil spring
51 is compressed in the housing portion 23 with the screw 52, and the tip end of the drive rod
35 abuts on the lower end surface 12 of the acoustic diaphragm 10, and the preload F1 is
applied to the magnetostrictive element 31. In addition, the coil spring 51 is inserted to a
position where a load F2 is applied.
[0056]
In this case, if one end (upper end) of the coil spring 51 is in direct contact with the screw 38 at
the bottom of the magnetostrictive actuator 30, when the screw 52 is turned and inserted into
the housing 23, the coil spring 51 is screwed Since it rotates together with 52, a torsional stress
is applied to the magnetostrictive element 31 of the magnetostrictive actuator 30, and the
magnetostrictive element 31 may be broken.
[0057]
Therefore, as illustrated, a ring 57 made of metal, PET (polyethylene terephthalate), or the like is
inserted between the magnetostrictive actuator 30 and the coil spring 51 so that the coil spring
51 rotates smoothly without receiving resistance. Is desirable.
[0058]
By this, the screw 52 is turned and inserted into the housing portion 23, and when the coil spring
51 is rotated together with the screw 52, the coil spring 51 is smoothly rotated without receiving
resistance, and a torsional stress is generated in the magnetostrictive element 31. There is no
risk that the magnetostrictive element 31 will break.
[0059]
Further, in this case, when the magnetostrictive actuator 30 is driven to apply vibration to the
acoustic diaphragm 10, the outer casing case 39 of the magnetostrictive actuator 30 contacts the
base casing 20 on the inner peripheral surface of the housing 23. The outer case 39 or the base
case 20 may be scratched or the outer case 39 or the base case 20 may be worn.
[0060]
Therefore, as shown in the drawing, direct contact between the outer peripheral surface of the
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outer casing case 39 and the inner peripheral surface of the storage portion 23 of the base
housing 20 is prevented, and the drive of the magnetostrictive actuator 30 is affected. It is
desirable to form or load a thin film 59 such as lubricating oil that does not
[0061]
<Magnetostrictive Characteristics and Loads: FIG. 3 and FIG. 4> In the example of FIG. 2, the total
load Ft (= F1 + F2) of the sum of the preload F1 and the load F2 is set to the following optimum
value.
[0062]
The characteristic of the magnetostriction value with respect to the control magnetic field when
the control current is supplied to the solenoid coil 32 and the control magnetic field is applied to
the magnetostrictive element 31 changes according to the total load Ft, for example, as shown in
FIG.
[0063]
In FIG. 3, (a) Curve 1 is for a total load Ft of Fα = 105 kg / cm <2>, and (b) Curve 2 is for a total
load Ft of 0.5Fα = 52.5 kg / cm <2> In the case of (c) curve 3 when the total load Ft is 0.3Fα =
31.5 kg / cm <2>, and (d) curve 4 the total load Ft is 1.5Fα = 157.5 kg / cm <2 In the case of (e),
the curve 5 is as follows when the total load Ft is 1.8Fα = 189 kg / cm <2>.
[0064]
The total load Ft is a load per unit area (1 cm <2>). For example, the magnetostrictive element 31
has a diameter of 2 mm and a cross-sectional area of 3.14 mm <2>.
[0065]
Therefore, the total load Gt actually applied to the magnetostrictive element 31 is as follows: (f)
curve 1 Gα = 3.30 kg, (g) curve 2 0.5 Gα = 1.65 kg, (h) curve 3 0.3 Gα = 0.99 kg, (i) 1.5 G α =
4.95 kg for the curve 4 and (1.8 g α = 5.94 kg for the (j) curve 5
[0066]
As shown in curve 1, when the total load Ft is Fα = 105 kg / cm <2> (the total load Gt is Gα =
3.30 kg), the magnetic field range in which the magnetostriction value changes linearly with the
change of the control magnetic field is the most The change of the magnetostriction value with
respect to the change of the control magnetic field in the magnetic field range becomes the
04-05-2019
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largest.
[0067]
Therefore, Fα = 105 kg / cm <2> and Gα = 3.30 kg are set as optimum values.
Assuming that the total load Ft is an optimum value Fα and the bias magnetic field is about 500
Oe, an audio signal is supplied to the solenoid coil 32 to apply a control magnetic field to the
magnetostrictive element 31, whereby an optimum magnetostrictive characteristic can be
obtained.
[0068]
Although omitted in FIG. 3, even if the total load Ft is 80 kg / cm <2> or more even if it is smaller
than Fα = 105 kg / cm <2>, compared to the case of the curve 2 or the curve 3, The magnetic
field range in which the magnetostriction value changes linearly with the change of the control
magnetic field is wide, and the change of the magnetostriction value with respect to the change
of the control magnetic field in the magnetic field range is large.
[0069]
Conversely, if the total load Ft is 110 kg / cm <2> or less even if it is greater than Fα = 105 kg /
cm <2>, compared to the case of Curve 4 or Curve 5, the change in the control magnetic field is
The magnetic field range in which the magnetostriction value changes linearly is wide, and the
change in the magnetostriction value with respect to the change in the control magnetic field in
the magnetic field range is large.
[0070]
Therefore, the total load Ft is in the range of 80 to 110 kg / cm <2>, and the range of 2.5 to 3.45
kg in terms of the total load Gt is a preferable range for driving the magnetostrictive actuator 30.
[0071]
Although the total load Ft is set to the optimum value Fα, for example, 0.5Fα = 52.5 kg / cm
<2> of 1/2 thereof is shared by the preload F1 and the load F2.
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[0072]
That is, in the magnetostrictive actuator 30, a torque equivalent to F1 = 0.5Fα = 52.5 kg / cm
<2> is applied to the magnetostrictive element 31 by the screw 38.
In terms of the preload G1 actually applied to the magnetostrictive element 31, G1 = 0.5 Gα =
1.65 kg.
[0073]
On the other hand, for the load F2, the coil spring 51 is compressed by the screw 52 to apply a
load of F2 = 0.5Fα = 52.5 kg / cm <2> to the magnetostrictive element 31.
In terms of the load G2 actually applied to the magnetostrictive element 31, G2 = 0.5 Gα = 1.65
kg.
[0074]
For example, as the coil spring 51, one having a free length of 32.3 mm and a spring constant of
0.2 to 0.3 kgf / mm is used, and as shown in FIG. By compressing, the load F2 is set to F2 =
0.5Fα = 52.5 kg / cm <2>.
[0075]
Therefore, in the example of FIG. 2, in the magnetostrictive actuator 30, the preload F1 becomes
0.5F.alpha. = 52.5 kg / cm <2>, and the screw 52 is in the storage portion 23 to a position where
the coil spring 51 is compressed by about 5 mm. By inserting it in the magnet, the
magnetostrictive actuator 30 or the base housing is made such that the load F2 becomes 0.5Fα
= 52.5 kg / cm <2> and the total load Ft (= F1 + F2) becomes Fα = 105 kg / cm <2>. Each
component such as the body 20 and each member such as the coil spring 51 and the screw 52
are designed and manufactured, and the speaker device is assembled.
[0076]
In this case, even if dimensional and adjustment variations occur among a large number of
04-05-2019
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manufactured speaker devices or between a plurality of magnetostrictive actuators or storage
portions of one speaker device, the amount of contraction of the coil spring 51 The change
absorbs that variation.
[0077]
For example, when the total length L of the magnetostrictive actuator 30 (the length from the tip
of the drive rod 35 to the bottom surface of the screw 38) L is shorter than the design value, or
the distance D from the lower end surface 12 of the acoustic diaphragm 10 to the upper surface
of the screw 52 is If it is longer than the design value, the amount of contraction of the coil
spring 51 is smaller than the set value.
At this time, the total load Ft decreases from the optimum value Fα, but the amount of reduction
is small, and the total load Ft falls within the range of 80 to 110 kg / cm <2> described above.
[0078]
Conversely, when the total length L of the magnetostrictive actuator 30 is longer than the design
value, or when the distance D is shorter than the design value, the amount of contraction of the
coil spring 51 increases more than the set value.
At this time, the total load Ft increases from the optimum value Fα, but the amount of increase is
small, and the total load Ft falls within the range of 80 to 110 kg / cm <2> described above.
[0079]
Therefore, in the example of FIG. 2, the total load Ft is kept within the preferred range regardless
of the dimensional and adjustment variations, and the magnetostriction value of the
magnetostrictive actuator 30 changes linearly with the change of the control magnetic field. Can
be driven with a suitable magnetostrictive characteristic in which the magnetic field range is
wide and the change in the magnetostriction value with respect to the change in the control
magnetic field in the magnetic field range is large.
[0080]
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In addition, when the magnetostrictive actuator 30 is driven for a long time, the portion of the
lower end surface 12 of the acoustic diaphragm 10 where the drive rod 35 abuts is abraded.
According to the test, when the acoustic diaphragm 10 is formed of acrylic, the drive rod 35 is
made of iron, and the solenoid coil 32 is supplied with a music signal having a peak voltage of 6
to 7 Vrms, the magnetostrictive actuator 30 is driven for 1000 hours. The portion of the lower
end surface 12 of the diaphragm 10 where the drive rod 35 abuts was abraded about 10 μm.
[0081]
In the example of FIG. 2, even if the portion of the lower end face 12 of the acoustic diaphragm
10 which is abutted against the drive rod 35 wears due to such long use, the amount of wear is
small, as described above As in the case where the distance D is longer than the design value, the
total load Ft is held within the range of 80 to 110 kg / cm <2> described above, and the
magnetostrictive actuator 30 can be driven with the above-described suitable magnetostrictive
characteristics.
[0082]
Furthermore, in the example of FIG. 2, since the coil spring 51 pushes the center of the
magnetostrictive actuator 30 to the acoustic diaphragm 10 side, the axial direction of the
magnetostrictive actuator 30 does not incline with respect to the vertical direction. A constant
magnitude of vibration is applied to a constant direction.
[0083]
(1−3.
Second Example: FIG. 5 As the magnetostrictive actuator, one to which a preload is not applied
can also be used.
[0084]
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17
FIG. 5 shows an example of this case as a second example of the first embodiment.
The acoustic diaphragm 10, its supporting structure, etc. are the same as the example of FIG.
[0085]
Similar to the magnetostrictive actuator 30 of the example of FIG. 2, in the magnetostrictive
actuator 60 of the example of FIG. 5, the solenoid coil 32 is disposed around the bar-like
magnetostrictive element 31, and the magnet 33 and the yoke 34 are disposed around the
solenoid coil 32. The actuator main body with the drive rod 35 connected to one end of the
magnetostrictive element 31 and the fixed disc 36 attached to the other end of the
magnetostrictive element 31 has a tip of the drive rod 35 protruding outside the outer casing
case 39 In addition, although it is loaded in an outer casing case 39 made of, for example,
aluminum, unlike the magnetostrictive actuator 30 in the example of FIG. 2, the above screw 38
and the damping material 37 are not provided, and a preload is applied to the magnetostrictive
element 31. It is not done.
[0086]
In this case, an O-ring 67 is attached, for example, between the disc portion of the drive rod 35
and the outer casing case 39 so as to be resistant to the lateral stress.
[0087]
As described above, the magnetostrictive actuator 60 to which the preload is not applied has an
advantage that the structure is simplified since it does not require parts for applying the preload
such as the screw 38 and the damping member 37 described above.
[0088]
In this example, with the acoustic diaphragm 10 supported by the base housing 20 as described
above, the magnetostrictive actuator 60 having the above configuration is inserted into the
housing 23 from the lower side with the drive rod 35 directed upward. Further, after inserting
the ring 57 and the coil spring 51 into the housing portion 23, the coil spring 51 is compressed
into the housing portion 23 with the screw 52 so that the tip of the drive rod 35 is the lower end
face of the acoustic diaphragm 10. 12, and insert the magnetostrictive element 31 to a position
where the load F3 is applied by the coil spring 51.
[0089]
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18
In this example, the load F3 applied by the coil spring 51 is the total load Ft applied to the
magnetostrictive element 31.
Therefore, the load F3 is set to the optimal value Fα as described above.
[0090]
Thus, in this example as well as in the example of FIG. 2, the magnetostrictive actuator 60 is
always always selected regardless of the dimensional or adjustment variation of the
magnetostrictive actuator 60 or the base housing 20 or the wear of the acoustic diaphragm 10. It
is possible to drive with a suitable magnetostriction characteristic in which the magnetic field
range in which the magnetostriction value changes linearly with the change of the control
magnetic field is wide and the change of the magnetostriction value with respect to the change of
the control magnetic field in the magnetic field range is large.
[0091]
Furthermore, also in this example, the coil spring 51 pushes the center of the magnetostrictive
actuator 60 toward the acoustic diaphragm 10 as in the example of FIG. 2, so that the axial
direction of the magnetostrictive actuator 60 is inclined with respect to the vertical direction.
Instead, a constant magnitude of vibration is always applied to the acoustic diaphragm 10 in a
constant direction.
[0092]
(1−4.
Another Example) Although the example of FIG. 2 and the example of FIG. 5 are the case where a
screw 52 is inserted into the housing 23 as a member for compressing the coil spring 51, a pluglike member is used instead of the screw 52. You may insert it.
[0093]
In this case, for example, a step or an inclination for restricting the insertion position of the
member is formed on the inner peripheral surface of the storage portion 23, or one end side of
04-05-2019
19
the member is a head (bottom) having a large diameter. The amount of contraction of the coil
spring 51 becomes a predetermined amount when the head is inserted to a position regulated by
the step or inclination or to a position where the head abuts against the lower surface 22 of the
base housing 20, and the total load Each part and each member are designed and manufactured
so that Ft becomes the optimal value Fα.
[0094]
As the magnetostrictive actuator 30 or 60, a buffer member may be provided at the tip of the
drive rod 35 in order to reduce the wear of the portion of the lower end face 12 of the acoustic
diaphragm 10 that is in contact with the drive rod 35.
[0095]
The buffer member may be formed into a sheet and attached to the end surface of the drive rod
35 with an adhesive, but it may be formed into a cap and loaded on the end of the drive rod 35
This is more preferable in that the mounting to the drive rod 35 and the removal from the drive
rod 35 are facilitated.
[0096]
If the thickness of the buffer member is large, the sound quality changes because the buffer
member abuts on the lower end surface 12 of the acoustic diaphragm 10, so the thickness of the
buffer member is set to several mm or less.
[0097]
The cushioning member may basically be formed of a material softer than the material of the
drive rod 35 and the acoustic diaphragm 10 in order to reduce the impact on the acoustic
diaphragm 10 by the drive rod 35.
[0098]
However, if the buffer member is too soft, the deflection of compression becomes large, the
transmission force of the excitation to the acoustic diaphragm 10 decreases, and the sound
pressure decreases.
On the contrary, even if the material of the drive rod 35 and the acoustic diaphragm 10 is softer,
04-05-2019
20
if the buffer member is harder than a certain value, the adhesion is deteriorated and the
transmission force of the excitation to the acoustic diaphragm 10 is reduced. The pressure falls.
[0099]
Therefore, as a material of the cushioning member, a material having a softness (hardness) in the
range of 30 to 75 of a durometer D which is one of the measures of softness (hardness) is
preferable.
One such material is ETFE (tetrafluoroethylene-ethylene copolymer), which is one of the
fluororesins.
[0100]
[2.
Second Embodiment: FIG. 6 and FIG. 7] The above-described first embodiment is a case where a
through hole is formed as the storage portion 23 in the base casing 20 as a support. The housing
portion into which the coil spring is inserted may be a hole (groove) having a bottom portion not
penetrating.
This case is shown as a second embodiment.
[0101]
(2−1.
First Example: FIG. 6) FIG. 6 shows a first example of the second embodiment.
The acoustic diaphragm 10, its supporting structure, etc. are the same as the example of FIG.
04-05-2019
21
[0102]
In the example of FIG. 6, a hole not penetrating through the lower surface 22 of the base housing
20 is formed as the housing 23 in the base housing 20, and the coil spring 51 is formed in the
housing 23. The magnetostrictive actuator 30 to which the preload F1 is applied as shown in FIG.
2 is inserted on the upper side of the coil spring 51 in the housing 23.
[0103]
In this case, with the acoustic diaphragm 10 not attached to the base housing 20, the coil spring
51 and the magnetostrictive actuator 30 are inserted into the housing portion 23, and then the
tip of the drive rod 35 of the magnetostrictive actuator 30 is the acoustic diaphragm The
acoustic diaphragm 10 is attached to the base housing 20 as described above in the example of
FIG. 1 so that the coil spring 51 is compressed by contacting the lower end surface 12 of the
base 10.
[0104]
At this time, when the amount of contraction of the coil spring 51 becomes a predetermined
amount, a preload F1 applied to the magnetostrictive element 31 in the magnetostrictive
actuator 30 and a load F2 applied to the magnetostrictive element 31 by the coil spring 51 in a
compressed state. Each component such as the magnetostrictive actuator 30 and the base casing
20 and each member such as the coil spring 51 are designed and manufactured such that the
total load Ft (= F1 + F2) of the sum becomes the above-mentioned optimum value Fα, and the
speaker device is assembled.
[0105]
Therefore, also in this example, dimensional and adjustment variations among a large number of
manufactured speaker devices, or among a plurality of magnetostrictive actuators or storage
portions of one speaker device, and an acoustic diaphragm 10 The dimensional change due to
wear of the portion of the lower end face 12 in contact with the drive rod 35 is absorbed by the
change in the amount of contraction of the coil spring 51, and the total load Ft (= F1 + F2) is
made within the preferred range. The magnetostrictive actuator 30 always has a wide magnetic
field range in which the magnetostrictive value linearly changes with respect to a change in
control magnetic field, and a large change in magnetostrictive value with respect to a change in
control magnetic field in the magnetic field range. It can be driven.
[0106]
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22
Furthermore, also in this example, since the coil spring 51 pushes the center of the
magnetostrictive actuator 30 toward the acoustic diaphragm 10, the axial direction of the
magnetostrictive actuator 30 does not incline with respect to the vertical direction. Thus, a
constant magnitude of vibration is always applied.
[0107]
Also in this example, direct contact between the outer circumferential surface of the outer casing
case 39 and the inner circumferential surface of the storage portion 23 of the base casing 20 is
prevented, and the driving of the magnetostrictive actuator 30 is affected. It is desirable to form
or load a thin film 59 such as lubricating oil that does not
[0108]
(2−2.
Second Example: FIG. 7 FIG. 7 shows a second example of the second embodiment.
The acoustic diaphragm 10, its supporting structure, etc. are the same as the example of FIG.
[0109]
In the example of FIG. 7, a hole not penetrating to the lower surface 22 side of the base housing
20 is formed as the housing 23 in the base housing 20, and the coil spring 51 is formed in the
housing 23. The magnetostrictive actuator 60 to which the preload is not applied as shown in
FIG. 5 is inserted on the upper side of the coil spring 51 in the housing 23.
[0110]
In this case, when the amount of contraction of the coil spring 51 becomes a predetermined
amount, the magnetostrictive actuator 60 or the base housing is set such that the load F3 applied
to the magnetostrictive element 31 by the coil spring 51 becomes the above optimum value Fα
as the total load Ft. The parts such as the body 20 and the members such as the coil spring 51
are designed and manufactured, and the speaker device is assembled.
[0111]
04-05-2019
23
Therefore, also in this example, dimensional and adjustment variations among a large number of
manufactured speaker devices, or among a plurality of magnetostrictive actuators or storage
portions of one speaker device, and an acoustic diaphragm 10 The dimensional change due to
the wear of the portion of the lower end face 12 in contact with the drive rod 35 is absorbed by
the change in the amount of contraction of the coil spring 51, and the total load Ft (= F3) is made
within the preferred range. The magnetostrictive actuator 60 always has a wide magnetic field
range in which the magnetostrictive value linearly changes with respect to a change in control
magnetic field, and a large change in magnetostrictive value with respect to a change in control
magnetic field in the magnetic field range. It can be driven.
[0112]
Furthermore, also in this example, since the coil spring 51 pushes the center of the
magnetostrictive actuator 60 toward the acoustic diaphragm 10, the axial direction of the
magnetostrictive actuator 60 does not incline with respect to the vertical direction. Thus, a
constant magnitude of vibration is always applied.
[0113]
[3.
Other Examples or Embodiments] When the acoustic diaphragm is cylindrical as in each of the
above examples, one end or both ends may have a bottom.
[0114]
For example, in the example of FIG. 1, if the upper end side of the acoustic diaphragm 10 is a
bottomed sound wave, the sound wave is also emitted from the bottom portion on the upper end
side, which makes it possible to further enhance the sense of the sound image.
[0115]
Further, the acoustic diaphragm is not limited to a cylindrical shape, but may be a semicylindrical shape, an elliptical cylindrical shape, or an angular cylindrical shape whose cross
section perpendicular to the central axis direction is a polygon. Good.
[0116]
04-05-2019
24
When the acoustic diaphragm is flat, one end side of the acoustic diaphragm may be supported
by a support such as a base case, as in the case of cylindrical as shown in FIG.
[0117]
Furthermore, the acoustic diaphragm is not limited to a tubular shape or a flat shape, and may be
a hemispherical shape, a spherical shape, a conical shape, a pyramid shape, a box shape, or the
like.
[0118]
The material of the acoustic diaphragm is not limited to acrylic, and glass or the like can also be
used.
[0119]
It is a figure which shows an example of the whole structure of the speaker apparatus of 1st
Embodiment.
It is a figure which shows the principal part of the speaker apparatus of the 1st example of 1st
Embodiment.
It is a figure which shows an example of the characteristic of the magnetostriction value with
respect to a control magnetic field.
It is a figure which shows an example of the relationship between the compression amount of the
coil spring in the example of FIG. 2, and the load by a coil spring.
It is a figure which shows the principal part of the speaker apparatus of the 2nd example of 1st
Embodiment.
It is a figure which shows the principal part of the speaker apparatus of the 1st example of 2nd
Embodiment.
04-05-2019
25
It is a figure which shows the principal part of the speaker apparatus of the 2nd example of 2nd
Embodiment.
It is a figure which shows the basic composition of an example of the speaker apparatus shown
by patent document.
It is a figure which shows an example of the magnetostrictive actuator support structure of the
speaker apparatus of the example of FIG.
Explanation of sign
[0120]
The main part is described in the figure, so it is omitted here.
04-05-2019
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