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JP2016213550

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DESCRIPTION JP2016213550
Abstract: To provide a speaker capable of suppressing deterioration of sound quality. A speaker
according to an aspect of the embodiment includes a piezoelectric actuator and a plurality of
diaphragms. Piezoelectric actuators expand and contract in response to applied voltages. The
plurality of diaphragms vibrate at different resonance frequencies to generate sounds according
to the expansion and contraction of the piezoelectric actuator. [Selected figure] Figure 1A
スピーカ
[0001]
The present invention relates to a speaker.
[0002]
Conventionally, a piezoelectric speaker using a piezoelectric element (piezo element) is known.
In such a speaker, by attaching a piezoelectric element to a diaphragm, the diaphragm is
resonated to increase the sound pressure (see, for example, Patent Document 1).
[0003]
Japanese Utility Model Application Publication No. 4-119200
11-05-2019
1
[0004]
However, if the sound pressure is increased by the resonance of the diaphragm, the resonance
does not occur at all frequencies. If the sound pressure is increased using this, the peak dip of the
sound pressure frequency characteristic becomes large and the sound quality is degraded. There
is a problem of
[0005]
This invention is made in view of the above, Comprising: It aims at providing the speaker which
can suppress degradation of a sound quality.
[0006]
In order to solve the above problems and achieve the object, the speaker of the present invention
includes a piezoelectric actuator and a plurality of diaphragms.
Piezoelectric actuators expand and contract in response to applied voltages.
The plurality of diaphragms vibrate at different resonance frequencies to generate sounds
according to the expansion and contraction of the piezoelectric actuator.
[0007]
According to the present invention, degradation of sound quality can be suppressed.
[0008]
FIG. 1A is a perspective view showing a configuration example of a speaker according to a first
embodiment.
FIG. 1B is a top view showing a configuration example of the speaker according to the first
embodiment.
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2
FIG. 1C is a cross-sectional view of the speaker at line X1 of FIG. 1B. FIG. 2A is a diagram
showing an example of sound pressure frequency characteristics when a plurality of diaphragms
are vibrated respectively. FIG. 2B is a diagram showing an example of sound pressure frequency
characteristics of the speaker according to the first embodiment. FIG. 3A is a top view showing a
configuration example of a speaker according to a second embodiment. FIG. 3B is a crosssectional view of the speaker at line X1 of FIG. 3A. FIG. 4A is a top view showing a configuration
example of a speaker according to a third embodiment. FIG. 4B is a side view showing a
configuration example of a loudspeaker according to a third embodiment. FIG. 5A is a top view
showing a configuration example of a speaker according to a first modification. FIG. 5B is a side
view showing a configuration example of a speaker according to a first modification. FIG. 6A is a
top view showing a configuration example of a speaker according to a fourth embodiment. 6B is
a cross-sectional view of the speaker at line X1 of FIG. 6A. FIG. 7A is a top view showing a
configuration example of a speaker according to a fifth embodiment. FIG. 7B is a side view
showing a configuration example of a speaker according to a fifth embodiment. FIG. 8A is a top
view showing a configuration example of a loudspeaker according to a sixth embodiment. FIG. 8B
is a side view showing a configuration example of a speaker according to a sixth embodiment.
FIG. 9A is a top view showing a configuration example of a loudspeaker according to a seventh
embodiment. FIG. 9B is a cross-sectional view of the speaker at line X1 of FIG. 9A. FIG. 10A is an
enlarged view of the region R1 of FIG. 9A. FIG. 10B is a view of the region R1 of FIG. 9A as
viewed in the X-axis direction. FIG. 11 is a view for explaining the recess according to the second
modification. FIG. 12 is a cross-sectional view showing a configuration example of a speaker
according to a third modification. FIG. 13A is a top view showing a configuration example of a
loudspeaker according to an eighth embodiment. FIG. 13B is a side view showing a configuration
example of a speaker according to an eighth embodiment. FIG. 14 is a top view showing a
configuration example of a speaker according to a fourth modification.
[0009]
Hereinafter, embodiments of the speaker disclosed in the present application will be described in
detail with reference to the attached drawings. Note that the present invention is not limited by
the embodiments described below.
[0010]
<1. First Embodiment> FIG. 1 is a view showing a configuration example of a speaker 100
according to a first embodiment. FIG. 1A is a perspective view of the speaker 100. FIG. FIG. 1B is
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3
a top view of the speaker 100, and FIG. 1C is a cross-sectional view of the speaker 100 taken
along line X1 of FIG. 1B.
[0011]
FIG. 1A illustrates a three-dimensional orthogonal coordinate system including a Z-axis in which
the upward direction in the figure is a positive direction and the downward direction in the figure
is a negative direction. Such an orthogonal coordinate system may also be shown in other
drawings used in the following description.
[0012]
As shown in FIG. 1, the speaker 100 includes a frame 10, a plurality of diaphragms 20A and 20B,
and a piezoelectric actuator 30.
[0013]
The diaphragms 20A and 20B are plate-like members that vibrate in response to the expansion
and contraction of the piezoelectric actuator 30, and generate sound.
The vibrating plates 20A and 20B have a substantially rectangular vibrating surface. The
diaphragms 20A and 20B are arranged such that the respective vibration planes are substantially
in the same plane (X-Y plane in FIG. 1). In the example shown in FIG. 1B, the diaphragms 20A
and 20B are disposed apart from the gap G.
[0014]
The vibrating plates 20A and 20B have mutually different resonant frequencies. The diaphragms
20A and 20B are made of, for example, metals such as aluminum, iron and copper, ABS resins,
acrylic resins, resins such as polycarbonate, and materials such as paper and wood. At this time,
in order to make the resonance frequencies of the diaphragms 20A and 20B different from each
other, for example, the diaphragm 20A and the diaphragm 20B may be made of different
materials.
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4
[0015]
The vibrating plates 20A and 20B preferably have largely different resonant frequencies. For this
reason, when one of the diaphragms 20A and 20B is a metal, the other is desirably made of a
material other than a metal (for example, a resin or the like). If the resonance frequencies of the
diaphragms 20A and 20B are different from each other, both of the diaphragms 20A and 20B
may be metal or resin.
[0016]
Alternatively, the resonant frequencies may be different from each other depending on the shape
or size of the diaphragms 20A and 20B. In this case, the diaphragms 20A and 20B may be made
of the same material (for example, aluminum). Alternatively, by adjusting the positional
relationship between the diaphragms 20A and 20B and the piezoelectric actuator 30, the
resonance frequencies of the diaphragms 20A and 20B may be different from each other.
[0017]
The frame 10 has a substantially rectangular bottom surface 10A and a frame-like support wall
10B. The frame 10 is a box-shaped member whose surface facing the bottom surface 10A is
open. The frame 10 is fixed to the placement target of the speaker 100. For example, in the case
where the placement target is an instrument panel in a vehicle compartment of a vehicle, the
frame 10 is fixed to the instrument panel.
[0018]
The support wall 10B is in contact with the outer peripheral portion of the diaphragms 20A and
20B excluding the sides adjacent to each other. Thus, the support wall 10B supports the
diaphragms 20A and 20B. Thus, the support wall 10B of the frame 10 supports the outermost
periphery of the region formed by the diaphragms 20A and 20B. Hereinafter, the outer
peripheral portions of the diaphragms 20A and 20B in contact with the support wall 10B are also
referred to as fixed ends, and the outer peripheral portions of the diaphragms 20A and 20B not
in contact with the support wall 10B are also referred to as free ends.
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5
[0019]
The piezoelectric actuator 30 expands and contracts in the longitudinal direction (X-axis
direction) according to the applied voltage. For example, the piezoelectric actuator 30 shown in
FIG. 1 is a monomorph type actuator composed of one piezoelectric element.
[0020]
As shown in FIG. 1C, the piezoelectric actuator 30 is provided in the space formed by the frame
10 and the diaphragms 20A and 20B. Further, as shown in FIG. 1B, the piezoelectric actuator 30
is provided substantially at the center of the region formed by the diaphragms 20A and 20B.
[0021]
The piezoelectric actuator 30 has a substantially rectangular main surface, and is disposed such
that the main surface is in contact with the vibration surface of the diaphragm 20A and the
vibration surface of the diaphragm 20B. Thereby, in response to the expansion and contraction
of the piezoelectric actuator 30, both of the diaphragms 20A and 20B vibrate, and sound is
generated from the diaphragms 20A and 20B.
[0022]
Here, although the piezoelectric actuator 30 is a monomorph type actuator, it is not limited
thereto. For example, it may be a bimorph actuator or a stacked actuator.
[0023]
Subsequently, the operation of the speaker 100 will be described with reference to FIG. FIG. 2A is
a diagram showing an example of sound pressure frequency characteristics when the plurality of
diaphragms 20A and 20B are vibrated respectively. FIG. 2B is a diagram showing an example of
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6
sound pressure frequency characteristics of the speaker 100 according to the first embodiment.
The horizontal axis in FIG. 2 indicates the frequency, and the vertical axis indicates the sound
pressure.
[0024]
The solid line in FIG. 2A shows an example of the sound pressure frequency characteristic when
vibrating the diaphragm 20A, and the dotted line shows an example of the sound pressure
frequency characteristic when vibrating the diaphragm 20B. .
[0025]
For example, in the example of FIG. 2A, when the diaphragm 20A is vibrated, a dip in which the
sound pressure decreases at the frequency F1 occurs, and a peak in which the sound pressure
increases at the frequency F2 occurs.
On the other hand, when the diaphragm 20B is vibrated, a peak where the sound pressure
increases at the frequency F1 occurs, and a dip where the sound pressure decreases near the
frequency F2 occurs.
[0026]
As shown in FIG. 2A, when the plurality of diaphragms 20A and 20B are vibrated alone, the peak
dip of the sound pressure frequency characteristic becomes large and the sound quality is
degraded. Thus, in the speaker 100 of the present embodiment, the plurality of diaphragms 20A
and 20B are vibrated by the piezoelectric actuator 30. Thereby, the peak dips of the sound
pressure frequency characteristics of the diaphragms 20A and 20B cancel each other, and the
sound pressure frequency characteristics of the speaker 100 become flat as shown in FIG. 2B.
[0027]
As described above, the speaker 100 according to the present embodiment can flatten the sound
pressure frequency characteristics of the speaker 100 by vibrating the diaphragms 20A and 20B
arranged on the same plane by the piezoelectric actuator 30. Thereby, the speaker 100 can
11-05-2019
7
suppress the deterioration of the sound quality.
[0028]
Further, in the speaker 100 according to the present embodiment, the diaphragms 20A and 20B
are disposed apart from each other by the gap G, and the outermost peripheral part of the region
formed by the diaphragms 20A and 20B is supported by the support wall 10B. As a result, the
outer peripheries of the diaphragms 20A and 20B close to each other become free ends, and the
diaphragms 20A and 20B easily resonate. That is, the types of resonance modes of the
diaphragms 20A and 20B increase.
[0029]
For example, if the resonance frequencies of the diaphragms 20A and 20B are close, that is, if the
sound pressure frequency characteristics when vibrating the diaphragms 20A and 20B are
similar, even if the diaphragms 20A and 20B are simply vibrated simultaneously The peak dips of
the sound pressure frequency characteristics may not cancel each other.
[0030]
Even in such a case, the types of resonance modes of the diaphragms 20A and 20B can be
increased by setting the outer peripheral parts of the diaphragms 20A and 20B close to each
other as the free ends as described above.
As a result, the diaphragms 20A and 20B can be vibrated in different resonance modes, and the
number of peak dips in the sound pressure frequency characteristic of the speaker 100 can be
reduced. As described above, when the diaphragms 20A and 20B have free ends, the sound
pressure frequency characteristics of the speaker 100 can be flattened, and the deterioration of
the sound quality can be suppressed.
[0031]
In addition, although embodiment mentioned above demonstrated the case where several
diaphragms 20A and 20B were two sheets, the number of diaphragms is not restricted to this.
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8
The number of diaphragms may be two or more. Further, although the case where each of the
diaphragms 20A and 20B is made of one type of material has been described, a plurality of
materials may be combined to form each of the diaphragms 20A and 20B. For example, the
diaphragms 20A and 20B may be configured by laminating plates of different materials.
[0032]
In the embodiment described above, although the case where the shape of the diaphragms 20A
and 20B is a rectangular shape has been described, the present invention is not limited to this.
For example, the diaphragms 20A and 20B may have a shape obtained by dividing an elliptical
plate into two. The diaphragms 20A and 20B may not have the same shape, and may not have
the same size.
[0033]
Moreover, although the case where the piezoelectric actuator 30 is arrange | positioned in the
approximate center of the area | region formed by diaphragm 20A, 20B was demonstrated in
embodiment mentioned above, it is not restricted to this. For example, by disposing the
piezoelectric actuator 30 closer to the diaphragm 20A, the area in which the piezoelectric
actuator 30 and the diaphragm 20A are in contact may be larger than the area in which the
piezoelectric actuator 30 and the diaphragm 20B are in contact. As described above, the
resonance frequencies of the diaphragms 20A and 20B may be made different from each other
by making the areas in which the piezoelectric actuator 30 and the diaphragms 20A and 20B
contact each other have different sizes.
[0034]
In addition, the amplitude of the free end is larger at the frequency of the vibration mode in
which the vicinity of the outermost periphery vibrates than the fixed end of the outermost
periphery of the diaphragm. Therefore, with the free end, the sound pressure can be increased at
some resonance frequencies.
[0035]
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9
In addition, in the case of reproducing high frequency sound and suppressing low frequency
sound, it is divided into two rather than one integral diaphragm, and the longest part (X direction
in the figure) of each diaphragm By shortening the length and enhancing the shape rigidity, the
resonance frequency can be realized in a high frequency region (that is, the lowest resonance
frequency is made higher than that of the one-piece integrated diaphragm). In addition, it is
possible to suppress the reproduction of unnecessary low frequency sound.
[0036]
Although the resonance frequency can be reduced by simply making the diaphragm small with
only one sheet (that is, shortening the longest part), the sound pressure is reduced because the
area is reduced compared to the single sheet diaphragm. Become. By dividing the diaphragm into
two smaller ones, it is possible to prevent a reduction in sound pressure by maintaining the
resonance frequency high and keeping the total area equal to that of one diaphragm.
[0037]
Further, in the embodiment described above, even when the diaphragms 20A and 20B have the
same characteristics, the amplitude at resonance becomes large because a part of the diaphragm
is a free end, and the whole circumference is fixed. Sound pressure can be increased by
comparison.
[0038]
Further, in the above-described embodiment, the longest resonance frequency of each of the
diaphragms is smaller than the longest portion of the undivided diaphragm, so that the lowest
resonance frequency among the resonance frequencies is higher than that of the undivided
diaphragm. .
Therefore, the sound quality adjustment in the case where the reproduction of the low frequency
is unnecessary can be realized without maintaining the same area as the undivided diaphragm
and without reducing the sound pressure.
[0039]
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10
<2. Second Embodiment> FIG. 3 is a view showing a configuration example of a speaker 110
according to a second embodiment. FIG. 3A is a top view of the speaker 110, and FIG. 3B is a
cross-sectional view of the speaker 110 taken along line X1 of FIG. 3A. The speaker 110 has the
same configuration as the speaker 100 of FIG. 1 except that the speaker 110 has the damping
material 40, and thus the same components are denoted by the same reference numerals and the
description thereof will be omitted.
[0040]
The damping material 40 is provided between the plurality of diaphragms 20A and 20B.
Damping material 40 is in contact with the adjacent outer peripheral portions of diaphragms 20A
and 20B. As shown in FIG. 3, the damping material 40 has a substantially rectangular
parallelepiped shape. The damping material 40 is provided outside the space formed by the
frame 10 and the diaphragms 20A and 20B so as to close the gap G between the diaphragms
20A and 20B.
[0041]
As shown to FIG. 3A, the length of the longitudinal direction (Y-axis direction) of the damping
material 40 is the same as the length of the free end of diaphragm 20A, 20B. Moreover, as shown
to FIG. 3B, the damping material 40 is arrange | positioned so as to oppose the piezoelectric
actuator 30 on both sides of diaphragms 20A and 20B. The damping material 40 converts the
vibration at the free end of the diaphragms 20A and 20B into, for example, thermal energy and
absorbs it.
[0042]
Here, the point which provides damping material 40 in the perimeter which is not in contact with
support wall 10B of diaphragms 20A and 20B is explained. The fixed ends of the diaphragms
20A and 20B do not vibrate significantly because they are in contact with the support wall 10B.
On the other hand, free ends of the diaphragms 20A and 20B can freely vibrate when the
damping material 40 is not provided. Therefore, depending on the frequency, the free ends of the
diaphragms 20A and 20B may vibrate largely, and an excessive peak may occur in the sound
11-05-2019
11
pressure frequency characteristics of the speaker 110.
[0043]
Therefore, in the speaker 110 according to the present embodiment, by providing the damping
material 40 at the free ends of the diaphragms 20A and 20B, resonance generated at the free
end is appropriately suppressed. Thereby, the excessive peak which generate | occur | produces
in the sound pressure frequency characteristic of the speaker 110 can be suppressed, and
degradation of a sound quality can be suppressed.
[0044]
Here, although the case where the length in the longitudinal direction of the damping material
40 is the same as the length of the free end of the diaphragms 20A and 20B has been described,
the present invention is not limited thereto. It is sufficient that the resonance occurring at the
free end of the diaphragms 20A and 20B can be appropriately suppressed by the damping
member 40, and the longitudinal length of the damping member 40 is longer than the free end of
the diaphragms 20A and 20B. May be
[0045]
Moreover, the shape of the damping material 40 is not limited to a rectangular parallelepiped
shape, and may be any shape. Furthermore, a plurality of damping materials 40 may be provided.
For example, a plurality of damping materials 40 may be disposed along the gap G.
[0046]
Alternatively, the damping material 40 may have a first damping material in contact with the free
end of the diaphragm 20A and a second damping material in contact with the free end of the
diaphragm 20B. As described above, by providing the first and second damping materials in
contact with the outer peripheral portions of the diaphragms 20A and 20B, respectively, for
example, selecting the damping materials according to the materials of the diaphragms 20A and
20B and the resonance frequency. Can.
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12
[0047]
<3. Third Preferred Embodiment> FIG. 4 is a view showing a configuration example of a
speaker 120 according to a third preferred embodiment. 4A is a top view of the speaker 120, and
FIG. 4B is a side view of the speaker 120. In addition, the same code | symbol is attached |
subjected to the component same as the speaker 100 of FIG. 1, and description is abbreviate |
omitted.
[0048]
As shown in FIG. 4, the speaker 120 includes a frame 11, a diaphragm 21, and a piezoelectric
actuator 30.
[0049]
The diaphragm 21 is a plate-like member that vibrates in response to the expansion and
contraction of the piezoelectric actuator 30 to generate a sound.
The diaphragm 21 has a substantially rectangular vibration surface. The diaphragm 21 is made
of, for example, a metal such as aluminum, iron or copper, an ABS resin, an acrylic resin, a resin
such as polycarbonate, a material such as paper or wood.
[0050]
The frame 11 has a substantially rectangular bottom surface 11A and a frame-shaped support
wall 11B. The frame 11 is a box-shaped member whose surface facing the bottom surface 11A is
open. The support wall 11B supports a part of the outer peripheral portion of the diaphragm 21.
Specifically, the support wall 11B has a plurality of support members 11C, and supports the
diaphragm 21 via the plurality of support members 11C.
[0051]
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13
The plurality of support members 11C are substantially rectangular parallelepiped shaped
members having the same thickness and predetermined height as the support wall 11B. The
plurality of support members 11C are integrally formed with the support wall 11B. Further, in
the example of FIG. 4, the plurality of support members 11 </ b> C are provided substantially at
the centers of the respective sides of the support wall 11 </ b> B.
[0052]
As shown in FIG. 4, in the present embodiment, the support member 11C of the support wall 11B
supports a part of the outer peripheral portion of the diaphragm 21. Thus, the approximate
centers of the sides of the outer peripheral portion of the diaphragm 21 are fixed by the plurality
of support members 11C. Hereinafter, the outer peripheral portion of the diaphragm 21
supported by the support member 11C is also referred to as a fixed end of the diaphragm 21. On
the other hand, corner portions of each side are not fixed by the plurality of support members
11C, and vibrate freely. Hereinafter, a portion of the outer peripheral portion of the diaphragm
21 which is not in contact with the support member 11C is also referred to as a free end of the
diaphragm 21.
[0053]
Of the outer peripheral portion of the diaphragm 21, the free end not in contact with the support
member 11C resonates more easily than the fixed end in contact, and the type of resonance
mode of the diaphragm 21 increases. For this reason, the number of peak dips of the sound
pressure frequency characteristic of the speaker 120 is reduced and flattened. Further, of the
outer peripheral portion of the moving plate 21, the free end not in contact with the support
member 11C has a larger amplitude at resonance of the diaphragm 21 than the fixed end in
contact. For this reason, the sound pressure of the speaker 120 can be increased.
[0054]
As described above, the support member 11C of the support wall 11B supports a part of the
outer peripheral portion of the diaphragm 21, whereby the sound pressure frequency
characteristics of the speaker 120 can be flattened, and the deterioration of the sound quality
can be suppressed. it can. Further, the support member 11C of the support wall 11B supports a
11-05-2019
14
part of the outer peripheral portion of the diaphragm 21 so that the sound pressure can be
increased at some resonance frequencies of the speaker 120.
[0055]
Generally, the amplitude of the piezoelectric element alone is small. For this reason, the speaker
using the piezoelectric element has a low sound pressure. As in the present embodiment, in the
configuration provided with the free end, the amplitude becomes larger compared to the fixed
end, and the sound pressure can be increased.
[0056]
Here, although the case where the number of the plurality of support members 11C is four has
been described, the number of the plurality of support members 11C is not limited to this. The
diaphragm 21 may be supported by the plurality of support members 11C, and may be more or
less than four.
[0057]
Further, the arrangement of the plurality of support members 11C is not limited to the center of
each side of the support wall 11B. For example, a plurality of support members 11C may be
provided at the corner of each side of the support wall 11B. The corners of the diaphragm 21
vibrate more easily than the central portions of the sides. Therefore, by providing the plurality of
support members 11C at the corner portions of each side of the support wall 11B, excessive
resonance in the corner portions can be suppressed, and excessive peaks of the sound pressure
frequency characteristics of the speaker 120 are suppressed. be able to. Further, since the type
of resonance frequency is different as compared with the case where the support wall 11B is
provided at the central part of each side, the sound pressure frequency characteristic of the
speaker 120 can be changed by changing the position where the support wall 11B is provided.
The sound quality can be adjusted according to the performance required of the speaker 120.
[0058]
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15
The shape of the plurality of support members 11C is not limited to a substantially rectangular
parallelepiped shape. For example, in the case where the plurality of support members 11C are
provided at the corner of each side of the support wall 11B, it may be L-shaped in accordance
with the corner of the support wall 11B. Alternatively, the shape of the support member 11C may
be, for example, a substantially trapezoidal shape in which the area in contact with the support
wall 11B is larger than the area in contact with the diaphragm 21.
[0059]
Thus, the number, arrangement, or shape of the plurality of support members 11C can be
appropriately changed in accordance with the sound pressure frequency characteristics of the
speaker 120.
[0060]
<3−1.
Modified Example 1> Note that although the case where the number of the diaphragms 21 is one
is described in FIG. 4, the number of the diaphragms may be plural. FIG. 5 shows a speaker 130
having a plurality of diaphragms 20A and 20B. FIG. 5A is a top view of the speaker 130
according to the first modification, and FIG. 5B is a side view of the speaker 130.
[0061]
The speaker 130 illustrated in FIG. 5 includes the diaphragms 20A and 20B, similarly to the
speaker 100 illustrated in FIG. As described above, the plurality of diaphragms 20A and 20B may
be supported by the plurality of support members 11C. Thereby, the number of free ends of the
plurality of diaphragms 20A and 20B can be increased.
[0062]
The number, arrangement, or shape of the plurality of support members 11C can be
appropriately changed in accordance with the sound pressure frequency characteristics of the
diaphragms 20A and 20B. By changing the number, arrangement, and the like of the plurality of
11-05-2019
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support members 11C, for example, even if the diaphragms 20A and 20B are made of the same
material, it is possible to make the resonance frequency different.
[0063]
Moreover, although FIG. 5 demonstrated the case where the flame | frame 10 of the speaker 100
shown in FIG. 1 was substituted to the flame | frame 11 shown in FIG. 4, it is not this limitation.
For example, the frame 10 of the speaker 110 shown in FIG. 3 may be replaced with the frame
11 shown in FIG. Or you may apply to each speaker of embodiment mentioned later.
[0064]
<4. Fourth Embodiment> FIG. 6 is a view showing a configuration example of a speaker 140
according to a fourth embodiment. 6A is a top view of the speaker 140, and FIG. 6B is a crosssectional view of the speaker 140 taken along line X1 of FIG. 6A. In addition, the same code |
symbol is attached | subjected to the component same as another embodiment, and description is
abbreviate | omitted.
[0065]
As shown in FIG. 6, the speaker 140 includes a frame 10, a diaphragm 21, a piezoelectric
actuator 30, and a support and damping material 50.
[0066]
The support and damping material 50 is a frame-like damping material having the same
thickness and predetermined height as the support wall 10B.
The support damping material 50 is provided between the diaphragm 21 and the support wall
10B. The support and damping material 50 supports the outer peripheral portion of the
diaphragm 21. That is, the support wall 10 </ b> B supports the outer peripheral portion of the
diaphragm 21 via the support damping material 50.
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17
[0067]
The speaker 140 has a space formed by the frame 10, the support damping material 50 and the
diaphragm 21. Also, the piezoelectric actuator 30 is disposed in the space.
[0068]
As described above, by supporting the outer peripheral portion of the diaphragm 21 with the
support and damping material 50, unnecessary resonance of the outer peripheral portion of the
diaphragm 21 can be suppressed. Thereby, the excessive peak on the sound pressure frequency
characteristic of the speaker 140 can be suppressed, and the sound pressure frequency
characteristic can be flattened. Therefore, deterioration of the sound quality of the speaker 140
can be suppressed.
[0069]
In addition, although the case where the diaphragm 21 was one piece was demonstrated here,
the number of sheets of a diaphragm may be plural. For example, the support damping material
50 may be provided between the support walls 10B of the speakers 100 and 110 shown in FIGS.
1 and 3 and the plurality of diaphragms 20A and 20B. In this case, the support damping material
50 is disposed between the outermost periphery of the region formed by the plurality of
diaphragms and the support wall 10B.
[0070]
<5. Fifth Embodiment> FIG. 7 is a view showing a configuration example of a speaker 150
according to a fifth embodiment. 7A is a top view of the speaker 150, and FIG. 7B is a side view
of the speaker 150. In addition, the same code | symbol is attached | subjected to the component
same as another embodiment, and description is abbreviate | omitted.
[0071]
As shown in FIG. 7, the speaker 150 includes a frame 10, a diaphragm 21, a piezoelectric
actuator 30, and a plurality of support damping members 51A to 51D (hereinafter, also referred
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to as a support damping member 51).
[0072]
The plurality of support damping members 51 are substantially rectangular parallelepiped
damping members having the same thickness and a predetermined height as the support wall
10B of the frame 10.
The support damping material 51 is provided between the diaphragm 21 and the support wall
10B. In the present embodiment, as shown in FIG. 7, the plurality of support and damping
members 51 are disposed substantially at the center of each side of the support wall 10 </ b> B.
The support wall 10 </ b> B supports the outer peripheral portion of the diaphragm 21 via the
plurality of support damping members 51.
[0073]
Thus, the approximate center of each side of the outer peripheral portion of the diaphragm 21 is
supported by the support wall 10B via the plurality of support damping members 51. On the
other hand, the corner of each side is freely supported without being supported by the plurality
of support and damping members 51.
[0074]
A portion of the outer peripheral portion of the diaphragm 21 which is not supported by the
support wall 10B is likely to resonate, and the types of resonance modes of the diaphragm 21
increase. Further, since the portion of the outer peripheral portion of the diaphragm 21
supported by the support wall 10B is supported via the support damping material 51,
unnecessary resonance of the outer peripheral portion is suppressed, and the sound pressure
frequency of the diaphragm 21 Excessive characteristic peaks can be suppressed. Thereby, the
sound pressure frequency characteristic of the speaker 150 can be flattened, and the
deterioration of the sound quality of the speaker 150 can be suppressed. In addition, the
amplitude of the portion of the outer peripheral portion of the diaphragm 21 which is not
supported becomes large, and the sound pressure of the speaker 150 can be increased. When the
amplitude becomes excessive, the peak is on the sound pressure frequency characteristics, but
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19
the excessive vibration can be suppressed by the damping action of the support damping
material 51 receiving the reaction of the resonance at the time of excessive amplitude. The sound
pressure can be increased while maintaining the flatness of the sound pressure frequency
characteristics.
[0075]
In addition, although the case where the diaphragm 21 was one piece was demonstrated here,
the number of sheets of a diaphragm may be plural. For example, a plurality of support damping
members 51 may be provided between the support walls 10B of the speakers 100 and 110
shown in FIGS. 1 and 3 and the plurality of diaphragms 20A and 20B. In this case, the support
damping material 51 is disposed between the outermost periphery of the region formed by the
plurality of diaphragms and the support wall 10B.
[0076]
<6. Sixth Embodiment> FIG. 8 is a view showing a configuration example of a speaker 160
according to a sixth embodiment. 8A is a top view of the speaker 160, and FIG. 8B is a side view
of the speaker 160. In addition, the same code | symbol is attached | subjected to the component
same as another embodiment, and description is abbreviate | omitted.
[0077]
A speaker 160 shown in FIG. 8 includes a frame 12, a diaphragm 21, a piezoelectric actuator 30,
and a plurality of support damping members 52A and 52B (hereinafter, also referred to as a
support damping member 52).
[0078]
The frame 12 has a substantially rectangular bottom surface 12A and a frame-like support wall
12B.
The frame 12 is a box-shaped member whose surface facing the bottom surface 12A is open. The
support wall 12B has a plurality of support members 12C.
11-05-2019
20
[0079]
The plurality of support members 12C are substantially rectangular parallelepiped shaped
members having the same thickness and predetermined height as the support wall 12B. The
length of the support member 12C in the longitudinal direction (X-axis direction in FIG. 8A) is
substantially equal to the length in the longitudinal direction of the diaphragm 21 (X-axis
direction in FIG. 8A) excluding the thickness of the support damping material 52. It is the same.
[0080]
The plurality of support members 12C are provided between the outer periphery in the
longitudinal direction of the diaphragm 21 and the support wall 12B. In the example shown in
FIG. 8A, two support members 12C are provided substantially in parallel. The support wall 12B
supports the outer peripheral portion in the longitudinal direction of the diaphragm 21 via the
plurality of support members 12C. The support member 12C may be integrally formed with the
support wall 12B.
[0081]
The plurality of support damping members 52 is a substantially rectangular parallelepiped
damping member having the same thickness as the support wall 12B and the same height as the
support member 12C. The length in the longitudinal direction (Y-axis direction in FIG. 8A) of the
support damping material 52 is substantially the same as the length in the short-side direction
(Y-axis direction in FIG. 8A) of the diaphragm 21.
[0082]
The plurality of support damping members 52 are provided between the outer periphery of the
diaphragm 21 in the short direction and the support wall 12B. The support wall 12 </ b> B
supports the outer peripheral portion in the short direction of the diaphragm 21 via the plurality
of support damping members 52.
11-05-2019
21
[0083]
The speaker 160 has a space formed by the frame 12, the support damping material 52 and the
diaphragm 21. Also, the piezoelectric actuator 30 is disposed in the space.
[0084]
As described above, when the outer peripheral portion of the diaphragm 21 is in contact with
both the support damping material 52 and the support wall 12B, excessive resonance of the
outer peripheral portion is suppressed, and excessive peaks on the sound pressure frequency
characteristics of the diaphragm 21. Can be suppressed. Thereby, the sound pressure frequency
characteristic of the speaker 160 can be flattened, and the deterioration of the sound quality of
the speaker 160 can be suppressed.
[0085]
In addition, although the case where the diaphragm 21 was one piece was demonstrated here,
the number of sheets of a diaphragm may be plural. For example, the support member 12C and
the support damping member 52 may be provided between the support wall 10B of the speakers
100 and 110 shown in FIGS. 1 and 3 and the plurality of diaphragms 20A and 20B. In this case,
the support member 12C and the support damping member 52 are disposed between the
outermost periphery of the region formed by the plurality of diaphragms 20A and 20B and the
support wall 12B.
[0086]
Further, the number, arrangement, or shape of the plurality of support members 12C and the
plurality of support damping members 52 can be appropriately changed in accordance with the
sound pressure frequency characteristics of the diaphragm 21. Furthermore, as shown in FIG. 5
and FIG. 7, a part of the outer peripheral portion of the diaphragm 21 may not be in contact with
the plurality of support members 12C and the plurality of support damping members 52. As
described above, by providing a gap between a part of the outer peripheral portion of the
diaphragm 21 and the support wall 12B, a part of the outer peripheral portion of the diaphragm
11-05-2019
22
21 may be easily resonated.
[0087]
<7. Seventh Preferred Embodiment> FIG. 9 is a view showing a configuration example of a
speaker 170 according to a seventh preferred embodiment. 9A is a top view of the speaker 170,
and FIG. 9B is a cross-sectional view of the speaker 170 along line X1 of FIG. 9A.
[0088]
The speaker 170 shown in FIG. 9 includes a frame 13, diaphragms 22A and 22B, and
piezoelectric actuators 30A and 30B.
[0089]
The diaphragm 22A is a plate-like member that vibrates in response to the expansion and
contraction of the piezoelectric actuator 30A and generates a sound.
The diaphragm 22B is a plate-like member that vibrates in response to the expansion and
contraction of the piezoelectric actuator 30B to generate a sound. The vibrating plates 22A and
22B have a substantially rectangular vibrating surface. The diaphragms 22A and 22B are
arranged such that the respective vibration planes are substantially on the same plane (X-Y plane
in FIG. 1).
[0090]
The diaphragms 22A and 22B shown in FIG. 9 have different sizes. The vibrating plates 22A and
22B have mutually different resonant frequencies. The material and the like of the diaphragms
22A and 22B are the same as the diaphragms 20A and 20B shown in FIG.
[0091]
11-05-2019
23
The frame 13 has a substantially rectangular bottom surface 13A, a frame-shaped support wall
13B, and a partition wall 13C. The frame 13 is a box-shaped member whose surface facing the
bottom surface 13A is open. The support wall 13B supports the outermost periphery of the
region formed by the diaphragms 22A and 22B. The support wall 13B is in contact with the
outer peripheral portion of the diaphragms 22A and 22B excluding the sides adjacent to each
other.
[0092]
The partition wall 13C supports the outer peripheral portion of at least one of the plurality of
diaphragms 22A and 22B. In the example of FIG. 9, the partition wall 13C supports the outer
peripheries of the diaphragms 22A and 22B which are close to each other.
[0093]
The partition wall 13C divides the space formed by the frame 13 and the diaphragms 22A and
22B into a first space including the piezoelectric actuator 30A and a second space including the
piezoelectric actuator 30B. Thus, the speaker 170 has the first space and the second space.
[0094]
The partition wall 13C has a recess 60 that allows the first space and the second space to
communicate with each other. The recess 60 has a shape in which the outer peripheral portions
of the plurality of diaphragms 22A and 22B are in contact with the partition wall 13C in the
direction along the partition wall 13C (Y-axis direction in FIG. 9). This point will be described in
detail with reference to FIG.
[0095]
FIG. 10 is a diagram for explaining the details of the recess 60. As shown in FIG. FIG. 10A is an
enlarged view of the area R1 in FIG. 9A, and FIG. 10B is a view of the area R1 as viewed in the Xaxis direction.
11-05-2019
24
[0096]
The recess 60 is provided at an end of the plurality of diaphragms 22A and 22B (in the positive
Z-axis direction) of the partition wall 13C. That is, the concave portion 60 is opened at the side of
the plurality of diaphragms 22A and 22B (in the positive direction of the Z-axis), and the
diaphragms 22A and 22B are disposed on the partition wall 13C, and a space including the
piezoelectric actuator 30A; The through holes communicate with the space including the
piezoelectric actuator 30B.
[0097]
As shown in FIG. 10A, the partition wall 13C has convex portions 13D to 13F. The convex
portion 13D is a wall located substantially at the center of the partition wall 13C in the thickness
direction (X-axis direction) and extending in the negative direction from the Y-axis positive
direction of the concave portion 60. Further, the convex portions 13E and 13F are walls
respectively located at both end portions in the thickness direction of the partition wall 13C, and
extending in the positive direction from the negative Y-axis direction of the concave portion 60.
The concave portion 60 has a bent path by the convex portions 13D to 13F.
[0098]
The length L1 in the Y-axis direction of the convex portion 13D is equal to or greater than the
width L2 in the direction (Y-axis direction) along the partition wall 13C of the concave portion 60
(L1LL2). In FIG. 10A, the case of L1 = L2 is illustrated. Thus, the outer peripheral portions of the
diaphragms 22A and 22B contact the partition wall 13C at any position in the short direction of
the partition wall 13C in the longitudinal direction of the partition wall 13C. Therefore, as shown
in FIG. 10B, when the partition wall 13C is viewed from the X-axis direction, the space connected
through the recess 60 can not be seen, and the recess 60 appears to be blocked by the
protrusion 13D.
[0099]
As described above, in the present embodiment, the outer peripheral portion of the diaphragms
11-05-2019
25
22A and 22B is provided by providing the convex portion 13D that blocks the opening between
the opening on the first space side and the opening on the second space side of the recess 60.
But contact the partition wall 13C and the support wall 13B at any position. That is, the outer
peripheral portions of the diaphragms 22A and 22B are both fixed ends.
[0100]
The speaker 170 according to the present embodiment vibrates the two diaphragms 22A and
22B with the piezoelectric actuators 30A and 30B, respectively, and the sound pressure
frequency characteristics of the two diaphragms 22A and 22B as the sound pressure frequency
characteristics of the speaker 170. Is obtained. Therefore, the sound pressure frequency
characteristic of the speaker 170 can be flattened, and the speaker 170 can suppress the
deterioration of the sound quality.
[0101]
Further, when the speaker 170 is simply divided into the first space and the second space by the
partition wall 13C, when the speaker 170 is operated, a force is generated in the Z-axis positive
direction of FIG. 9, and the diaphragms 22A and 22B are peeled off. There is a possibility of
Therefore, in the present embodiment, the recess 60 is provided in the partition wall 13C.
Thereby, the force generated in the Z-axis direction can be suppressed, and the peeling of the
diaphragms 22A and 22B can be suppressed.
[0102]
When the recessed portion 60 is provided, as described above, the outer peripheral portions of
the diaphragms 22A and 22B are in contact with any of the partition walls 13C in the
longitudinal direction of the partition wall 13C. Thereby, the outer peripheral part of diaphragm
22A, 22B will contact either of partition wall 13C and support wall 13B, and can suppress the
unnecessary resonance generate | occur | produced in the outer peripheral part of diaphragm
22A, 22B. Thereby, the sound pressure frequency characteristic of the speaker 170 can be
flattened, and the speaker 170 can suppress the deterioration of the sound quality.
[0103]
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26
Next, the connection hole will be described. The air on the back of the diaphragm acts as an air
spring supporting the diaphragm. Therefore, the elastic modulus of the air spring changes (that
is, the resonance point changes) according to the volume of the space surrounded by the frame
side surface and the bottom surface, and the sound pressure frequency characteristic changes. In
order to obtain good sound pressure frequency characteristics, it is necessary to make the
volume of the space surrounded by the side and bottom of the frame appropriate.
[0104]
However, due to the restriction of the mounting space, if the dimensions of the speaker
outermost shape are determined, there is a possibility that only a volume smaller than the
required volume can be obtained.
[0105]
Therefore, as shown in FIG. 9 to FIG. 12, in the case of a frame structure in which each of the two
diaphragms is attached in front of separate air chambers and the two are integrated, holes are
formed in the partitions of both air chambers. When opened and connected, each diaphragm can
also use the next air chamber as a volume.
Therefore, the volume can be increased without increasing the external dimensions of the
speaker, and good sound pressure frequency characteristics can be obtained. A method of
connecting the air chambers is to make a hole in the vicinity of the center of the partition wall as
shown in FIG. 12 because it is necessary to secure the affixing surface of the diaphragm of the
frame.
[0106]
However, when a hole is made in the vicinity of the center of the partition wall, when the frame is
manufactured by resin molding, the portion of the hole is perpendicular to the forming direction
of the mold (the direction of removing the mold · Z direction). Can not be formed by the mold
(can not be removed from the mold). In addition, if it can be formed with a mold at the time of
resin molding (if the mold is removed), the shape of the hole becomes a simple notch-like hole
(concave portion), and the diaphragm attaching surface is interrupted. In the case of a so-called
11-05-2019
27
slide mold structure, the mold structure becomes complicated, and the cost further increases.
[0107]
Therefore, by adopting the configuration as shown in FIG. 9 to FIG. 11, the frame can be formed
by the mold (removed from the mold), and the vibration sticking surface can not be interrupted.
[0108]
<7−1.
Modification 2> Note that the shape of the recess 60 is not limited to the example shown in FIG.
For example, as shown in FIG. 11, the recess 61 may be provided obliquely in the longitudinal
direction of the partition wall 13C (Y-axis direction in FIG. 11).
[0109]
The partition wall 13C shown in FIG. 11 has tapered portions 13G and 13H. The recesses 61 are
provided so that the tops of the tapered portions 13G and 13H overlap each other by a distance
L3 (L330) in the Y-axis direction. Thus, when the partition wall 13C is viewed from the X-axis
direction, the space connecting through the recess 61 can not be seen, and the recess 61 appears
to be blocked by the tapered portions 13G and 13H.
[0110]
As described above, by making the opening on the first space side of the recess 61 and the
opening on the second space side not to overlap from the X-axis direction, the outer peripheral
portions of the diaphragms 22A and 22B are at any position. It may be in contact with the
partition wall 13C and the support wall 13B.
[0111]
In addition, the shape of the recessed parts 60 and 61 mentioned above is not restricted to the
example mentioned above.
11-05-2019
28
The outer peripheral portions of the diaphragms 22A and 22B only have to be fixed ends, and
the concave portions 60 and 61 may be, for example, a plurality of diffracted rays and may be
curved.
[0112]
<7−2. Modification 3> FIG. 12 is a cross-sectional view of a speaker 180 according to
Modification 3. As shown in FIG. The speaker 180 has the same configuration as the speaker 170
of FIG. 10 except for the through hole 62, so the same components are denoted by the same
reference numerals and the description thereof will be omitted.
[0113]
The through hole 62 is provided substantially at the center of the partition wall 13C in the Z-axis
direction. The through holes 62 may have a bent path or an oblique path in a plan view as shown
in FIGS. 10 and 11, or may be a linear path parallel to the X axis.
[0114]
The shape of the through hole 62 can be appropriately changed by providing the through hole
62 substantially at the center in the height direction (Z-axis direction) of the partition wall 13C.
[0115]
Thus, the outer peripheral portions of the diaphragms 22A and 22B may be in contact with the
partition wall 13C in the longitudinal direction of the partition wall 13C, and the shapes and
positions of the concave portions 60 and 61 and the through holes 62 are limited to the abovedescribed example. I can not.
[0116]
Moreover, in 7th Embodiment, although the speaker 170 was divided into two space by 13 C of
partition walls, it is not restricted to this.
11-05-2019
29
For example, two speakers may be connected to form one speaker.
In this case, a recess may be provided in each of the support walls to be connected.
[0117]
In the seventh embodiment, the diaphragms 22A and 22B are disposed such that the short sides
of the diaphragms 22A and 22B are in contact with each other. However, the present invention is
not limited to this. The diaphragms 22A and 22B may be arranged such that the longitudinal
directions of the diaphragms 22A and 22B are in contact with each other.
[0118]
Furthermore, for example, as shown in FIG. 1 and FIG. 3, the diaphragms 22A and 22B may be
configured by a plurality of diaphragms, respectively. Alternatively, as shown in FIGS. 4 to 8, the
support wall 13B and the partition wall 13C of the frame 13 may support a part of the outer
peripheral portion of the diaphragms 22A and 22B, and the support wall 13B and the partition
wall You may make it provide the support damping material 51 and 52 between 13C.
[0119]
<8. Eighth Embodiment> FIG. 13 is a view showing a configuration example of a speaker 190
according to an eighth embodiment. 13A is a top view of the speaker 190, and FIG. 13B is a side
view of the speaker 190.
[0120]
In the speaker 190, two diaphragms having different resonance modes (resonance frequencies
are different) are stacked and arranged, and the sound from the diaphragm 23A and the
radiation from the diaphragm 23B come out through the diaphragm 23A. An object of the
11-05-2019
30
present invention is to make the sound pressure frequency characteristics flatter by interfering
with sound and according to the principle shown in FIGS. 2A and 2B. In other words, in the
configuration example of FIG. 1A to FIG. 1C described above, although the plurality of
diaphragms are arranged side by side and the effect of flattening shown in FIGS. 2A and 2B is
exhibited, the configuration example shown in FIG. The purpose is to arrange a plurality of
diaphragms vertically and to arrange them, and to exert the effect of flattening shown in FIG. 2A
and FIG. 2B. Note that this does not indicate that one diaphragm is advantageous for
reproduction of low frequencies and the other diaphragm is advantageous for reproduction of
high frequencies.
[0121]
Further, as shown in FIG. 2A, when the plurality of diaphragms 23A and 23B are vibrated alone,
the peak dip of the sound pressure frequency characteristic becomes large, and the sound quality
is deteriorated. Therefore, in the speaker 190 according to the present embodiment, the plurality
of diaphragms 23A and 23B are disposed so as to overlap in the Z direction, and vibrated by the
piezoelectric actuator 31. Thereby, the peak dips of the sound pressure frequency characteristics
of the diaphragms 23A and 23B cancel each other, and the sound pressure frequency
characteristics of the speaker 190 become flat as shown in FIG. 2B.
[0122]
That is, the speaker 190 according to the present embodiment flattens the sound pressure
frequency characteristics of the speaker 190 by vibrating the diaphragms 23A and 23B arranged
so as to overlap in the direction perpendicular to the surface of the diaphragm by the
piezoelectric actuator 31. it can. Thereby, the speaker 190 can suppress the deterioration of the
sound quality.
[0123]
The speaker 190 shown in FIG. 13 includes a frame 15, diaphragms 23A and 23B, a piezoelectric
actuator 31, and a plurality of support members 70A to 70D (hereinafter, also referred to as
support members 70). The frame 15, the diaphragms 23A and 23B, and the piezoelectric
actuator 31 are the same as the diaphragms 20A and 20B shown in FIG.
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31
[0124]
The diaphragms 23A and 23B according to the present embodiment are arranged such that the
vibration planes are substantially parallel. Specifically, they are spaced apart in the Z-axis
direction of FIG. 13A by the same amount as the thickness of the piezoelectric actuator 31.
[0125]
The piezoelectric actuator 31 is provided between the diaphragms 23A and 23B. The
piezoelectric actuator 31 is provided in contact with the adjacent diaphragms 23A and 23B.
Specifically, the piezoelectric actuator 31 is disposed such that one surface is in contact with the
vibration surface of the diaphragm 23A, and the opposing surface facing the one surface is in
contact with the vibration surface of the diaphragm 23B. Thereby, the piezoelectric actuator 31
vibrates both of the diaphragms 23A and 23B.
[0126]
The support member 70 is provided between the diaphragms 23A and 23B. The support member
70 is provided in contact with the outer peripheral portions of the adjacent diaphragms 23A and
23B. Thus, the support member 70 supports the diaphragm 23A. The thickness (length in the Zaxis direction) of the support member 70 is substantially the same as the thickness (length in the
Z-axis direction) of the piezoelectric actuator 31.
[0127]
The support member 70 is made of, for example, a metal such as aluminum, a resin, and a
material such as wood. The support member 70 may be made of, for example, the same material
as the frame 15. Alternatively, the support member 70 may be made of a damping material.
[0128]
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32
The frame 15 supports the outer peripheral portion of the diaphragm 23B. In the example shown
to FIG. 13B, although the case where the flame | frame 15 supports all the outer peripheral parts
of diaphragm 23B is shown, it is not restricted to this. For example, as shown in FIGS. 4 to 8, the
frame 15 may support a part of the outer peripheral portion of the diaphragm 23B, and the
support damping material may be provided between the frame 15 and the outer peripheral
portion of the diaphragm 23B. 51 and 52 may be provided.
[0129]
The speaker 190 according to the present embodiment can flatten the sound pressure frequency
characteristics of the speaker 190 by vibrating the diaphragms 23A and 23B disposed
substantially in parallel by the piezoelectric actuator 31. Thereby, the speaker 190 can suppress
the deterioration of the sound quality.
[0130]
Specifically, the diaphragm 23B whose outer peripheral portion is fixed by the frame 15 vibrates
according to the expansion and contraction of the piezoelectric actuator 31, so that a relatively
good sound pressure can be obtained in a low frequency region. Further, by vibrating the
diaphragm 23A, of which a part of the outer peripheral portion is fixed by the support member
70, according to the expansion and contraction of the piezoelectric actuator 31, relatively good
sound pressure can be obtained in a high frequency region.
[0131]
Accordingly, by vibrating the diaphragms 23A and 23B according to the expansion and
contraction of the piezoelectric actuator 31, a good sound pressure can be obtained in a wide
frequency range, and the deterioration of the sound quality of the speaker 190 can be
suppressed.
[0132]
In addition, since the diaphragms 23A and 23B are disposed substantially in parallel, the speaker
190 can be miniaturized.
11-05-2019
33
Furthermore, by making the thickness of the support member 70 and the thickness of the
piezoelectric actuator 31 approximately the same, it is possible to suppress an increase in the
thickness of the speaker 190 (the length in the Z-axis direction in FIG. 13). That is, it is possible
to suppress the deterioration of the sound quality while realizing the downsizing and thinning of
the speaker 190.
[0133]
The number, arrangement, or shape of the support members 70 can be appropriately changed
according to the sound pressure frequency characteristics of the speaker 190. Further, the size of
the diaphragms 23A and 23B can be appropriately changed in accordance with the sound
pressure frequency characteristics of the speaker 190. At this time, the sizes of the diaphragms
23A and 23B may not necessarily be the same. The number of diaphragms 23A and 23B is not
limited to two, and may be two or more.
[0134]
<8−1. Modification 4> FIG. 14 is a top view showing a configuration example of a speaker
200 according to Modification 4. As shown in FIG. The speaker 200 has the same configuration
as the speaker 190 of FIG. 13 except for the diaphragm 24A, so the same components are
denoted by the same reference numerals and the description thereof will be omitted.
[0135]
The diaphragm 24A has at least one hole 80. The hole 80 is a sound emission hole for emitting
the sound emitted from one diaphragm 23B whose outer peripheral portion is supported by the
support wall of the frame 15 from the other diaphragm 24A to the outside of the speaker 200.
[0136]
Thus, by providing the holes 80 in the diaphragm 24A provided on the outside of the speaker
200, the radiation efficiency of the sound generated from the diaphragm 23B provided on the
inside of the speaker 200 can be improved.
11-05-2019
34
[0137]
Further effects and modifications can be easily derived by those skilled in the art.
Thus, the broader aspects of the invention are not limited to the specific details and
representative embodiments represented and described above. Accordingly, various
modifications may be made without departing from the spirit or scope of the general inventive
concept as defined by the appended claims and their equivalents.
[0138]
10 to 13, 15 Frame 20 to 24 Diaphragm 30, 31 Piezoelectric actuator 40 Vibration damping
material 50 to 52 Support vibration damping material 60, 61 Recess 62 62 Through hole 70
Support member
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35
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