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JP2014072711

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DESCRIPTION JP2014072711
An acoustic generator, an acoustic generator and an electronic device capable of improving the
sound quality by reducing the difference between the resonance peak and the dip in the
frequency characteristic of sound pressure to suppress the frequency fluctuation of the sound
pressure as much as possible. Provide equipment. According to one embodiment, a sound
generator according to an embodiment includes a thin plate-like vibrator and an exciter provided
on the vibrator. The vibrating body has a first area and a second area in which the distance
between the nodes of the standing wave of the vibration is different from the distance between
the nodes of the standing wave in the first area in the plane on which the exciter is provided.
Have. [Selected figure] Figure 2
Acoustic generator, acoustic generator and electronic device
[0001]
Embodiments of the disclosure relate to a sound generator, a sound generator and an electronic
device.
[0002]
Heretofore, it has been known that a sound generator represented by a piezoelectric speaker can
be used as a small and thin speaker.
Such a sound generator can be used as a speaker incorporated in an electronic device such as a
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mobile phone or a flat-screen television.
[0003]
As the sound generator, for example, there is one including a vibrating body and a piezoelectric
vibrating element provided in the vibrating body (see, for example, Patent Document 1). This
configuration is configured to vibrate the vibrating body by the piezoelectric vibrating element
and generate sound by utilizing the resonance phenomenon of the vibrating body.
[0004]
Unexamined-Japanese-Patent No. 2004-23436
[0005]
However, in the configuration in which the sound pressure is generated by the resonance of the
vibrating body itself as in the above-described sound generator, the difference between the
resonance peak and the dip (the valley between the resonance peaks) in the frequency
characteristic of the sound pressure There was a risk of frequency fluctuations.
And there was a possibility that that might disturb the sound quality improvement.
[0006]
One aspect of the embodiment is made in view of the above, and the difference between the
resonance peak and the dip in the frequency characteristic of the sound pressure is reduced to
suppress the frequency fluctuation of the sound pressure as much as possible, and the sound
quality is improved. It is an object of the present invention to provide an acoustic generator, an
acoustic generator and an electronic device that can be improved.
[0007]
The sound generator according to one aspect of the embodiment includes a thin plate-like
vibrator and an exciter provided on the vibrator.
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In the vibrating body, in a surface on which the exciter is provided, a distance between a first
region and a node of a standing wave of vibration is different from a distance of a node of a
standing wave of vibration in the first region And an area of
[0008]
According to the sound generator of one aspect of the embodiment, the difference between the
resonance peak and the dip in the frequency characteristic of the sound pressure can be reduced
to suppress the frequency fluctuation of the sound pressure as much as possible, and the sound
quality can be improved. .
[0009]
FIG. 1A is a schematic plan view of the sound generator according to the first embodiment.
FIG. 1B is a cross-sectional view taken along line A-A 'of FIG. 1A. FIG. 2 is an explanatory view
showing a standing wave of vibration generated in a vibrator of the sound generator shown in
FIG. FIG. 3 is a schematic plan view showing an acoustic generator according to a modification of
the first embodiment. FIG. 4 is a schematic plan view showing an acoustic generator according to
another modification of the first embodiment. FIG. 5 is a cross-sectional view taken along the line
A-A ′ of FIG. 1A, showing an acoustic generator according to another modification in the first
embodiment. FIG. 6 is a block diagram of the sound generator. FIG. 7 is a block diagram of the
electronic device. FIG. 8 is a schematic plan view showing the sound generator according to the
second embodiment. FIG. 9 is a schematic plan view showing another arrangement example of
the first and second regions.
[0010]
Hereinafter, embodiments of a sound generator, a sound generator and an electronic device
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.
[0011]
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First Embodiment FIG. 1A is a schematic plan view of an acoustic generator 1 according to a first
embodiment as viewed from a direction perpendicular to the main surface of a vibrating body 10,
and FIG. 1B is an A view of FIG. It is a -A 'line sectional view. In order to make the description
easy to understand, FIGS. 1A and 1B illustrate a three-dimensional orthogonal coordinate system
including a Z axis in which the vertically upward direction is a positive direction and the
vertically downward direction is a negative direction. Such an orthogonal coordinate system may
also be shown in other drawings used in the following description. Further, in FIG. 1B, the sound
generator 1 is expanded and deformed in the vertical direction (Z-axis direction) to facilitate
understanding.
[0012]
As shown in FIGS. 1A and 1B, the acoustic generator 1 according to the embodiment includes a
vibrating body 10, a plurality of piezoelectric vibrating elements 20, and a frame 30. The sound
generator 1 is called a so-called piezoelectric speaker, and generates sound pressure using the
resonance phenomenon of the vibrating body 10 itself.
[0013]
In addition, as shown to FIG. 1A, although the case where the sound generator 1 is equipped with
the two piezoelectric vibration elements 20 is illustrated in this embodiment, the number of
objects is not limited to this, 1 or 3 It may be more than one. Further, in the present embodiment,
the description will be given assuming that the two piezoelectric vibrating elements 20 have
substantially the same shape.
[0014]
The vibrating body 10 can be formed using various materials such as resin, metal, and paper. For
example, the thin plate-like vibrator 10 can be made of a resin film of polyethylene, polyimide,
polypropylene or the like having a thickness of about 10 to 200 μm. Since the resin film is a
material having a lower elastic modulus and mechanical Q value than a metal plate or the like, by
forming the vibrating body 10 with a resin film, the vibrating body 10 is bent and vibrated with a
large amplitude to obtain sound pressure The width and height of the resonance peak in the
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frequency characteristic can be increased to reduce the difference between the resonance peak
and the dip.
[0015]
The piezoelectric vibrating element 20 is an exciter that excites the vibrating body 10 by
vibrating in response to application of a voltage, and is, for example, a bimorph-type laminated
piezoelectric vibrating element. As described above, since the exciter is the piezoelectric vibrating
element 20, it becomes possible to make it thinner as compared with an electromagnetic exciter
using a coil and a magnet, etc., thereby making the acoustic generator 1 thin. be able to. In
addition, since the piezoelectric vibration element 20 is a bimorph type in which the element
itself bends and vibrates (one element), it is suitable for vibrating the thin plate-like vibrating
body 10, which causes the vibrating body 10 to vibrate largely and is high. It is possible to
generate sound pressure.
[0016]
Specifically, as shown in FIG. 1B, the piezoelectric vibrating element 20 includes the laminate 21,
the surface electrode layers 22 and 23 formed on the upper and lower surfaces of the laminate
21, and the internal electrode layer 24 of the laminate 21. And an external electrode formed on
the side surface where the end face is exposed. The lead terminals 27a and 27b are connected to
the external electrodes 25 and 26, respectively.
[0017]
The laminate 21 is formed, for example, by alternately laminating four layers of piezoelectric
material layers 28a, 28b, 28c, and 28d made of ceramic and three layers of internal electrode
layers 24. Further, the piezoelectric vibrating element 20 has a rectangular main surface on the
upper surface side and the lower surface side, and the piezoelectric layers 28a and 28b and the
piezoelectric layers 28c and 28d are alternately polarized in the thickness direction (Z-axis
direction). It is done.
[0018]
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Therefore, when a voltage is applied to the piezoelectric vibrating element 20 through the lead
terminals 27a and 27b, for example, the lower surface side of the piezoelectric vibrating element
20, in other words, the piezoelectric layers 28c and 28d on the vibrating body 10 side shrinks,
The side piezoelectric layers 28a and 28b deform so as to extend. As described above, the
piezoelectric layers 28a and 28b on the upper surface side of the piezoelectric vibrating element
20 and the piezoelectric layers 28c and 28d on the lower surface exhibit opposite stretching
behavior, and as a result, the piezoelectric vibrating element 20 has bimorph-type bending. By
vibrating, the vibrating body 10 can be given a constant vibration to generate a sound.
[0019]
Here, as materials for forming the piezoelectric layers 28a, 28b, 28c and 28d, lead-free
piezoelectric materials such as lead zirconate titanate (PZT (lead zirconate titanate)), Bi layer
compounds, tungsten bronze structure compounds, etc. Piezoelectric ceramics conventionally
used can be used.
[0020]
The material of the internal electrode layer 24 preferably contains a metal component composed
of silver and palladium and material components constituting the piezoelectric layers 28a, 28b,
28c, 28d.
When the internal electrode layer 24 contains the ceramic component that constitutes the
piezoelectric layers 28a, 28b, 28c, 28d, the thermal expansion difference between the
piezoelectric layers 28a, 28b, 28c, 28d and the internal electrode layers 24, 24, 24 The
piezoelectric vibrating element 20 can be obtained with reduced stress due to the above.
[0021]
Further, as the wiring connected to the lead terminals 27a and 27b, in order to reduce the height
of the piezoelectric vibrating element 20, it is preferable to use a flexible wiring in which a metal
foil such as copper or aluminum is sandwiched by resin films.
[0022]
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The piezoelectric vibrating element 20 configured as described above is provided on the
vibrating body 10.
Specifically, the piezoelectric vibrating element 20 is bonded to the vibrating surface 10 a of the
vibrating body 10 via a bonding portion 40 formed of an adhesive. The thickness of the bonding
portion 40 between the piezoelectric vibrating element 20 and the vibrating body 10 is relatively
thin, for example, 20 μm or less. As described above, when the thickness of the bonding portion
40 is 20 μm or less, the vibration of the stacked body 21 can be easily transmitted to the
vibrating body 10.
[0023]
As an adhesive agent which forms the junction part 40, although a well-known thing, such as an
epoxy resin, a silicone resin, polyester resin, can be used, for example, it is not limited to this. In
addition, as a method of curing the resin used for the adhesive, any method such as heat curing,
photo curing, anaerobic curing and the like may be used.
[0024]
The frame 30 holds the vibrating body 10 and plays a role of forming a fixed end of a standing
wave of vibration described later. For example, although not shown, the vibrating body 10 is
attached to a ring-shaped frame 30 having a circular or elliptical shape, or, as shown in FIG. 1B,
both have a polygonal shape, specifically, For example, the rectangular upper frame member 30
a and the lower frame member 30 b are vertically joined to constitute the frame 30. And the
outer peripheral part of the vibrating body 10 is pinched ¦ interposed between the upper frame
member 30a and the lower frame member 30b, and it is fixing in the state to which
predetermined ¦ prescribed tension ¦ tensile̲strength was provided. Therefore, it becomes the
sound generator 1 provided with the vibrating body 10 with few deformations, such as bending,
even if it is used for a long time.
[0025]
A portion of the vibrating body 10 located inside the frame 30, that is, a portion of the vibrating
body 10 which is not sandwiched by the frame 30 and can freely vibrate is referred to as a
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vibrating surface 10 a. Therefore, the vibrating surface 10 a of the vibrating body 10 on which
the piezoelectric vibrating element 20 is provided is a polygonal portion, specifically, a
substantially rectangular portion, for example, in the frame 30.
[0026]
Although the thickness and the material of the frame 30 are not particularly limited, in the
present embodiment, for example, a stainless steel material having a thickness of 100 to 1000
μm is used because it is excellent in mechanical strength and corrosion resistance. Use.
[0027]
FIG. 2 is an explanatory view showing a standing wave of vibration generated in the vibrating
body 10 of the sound generator 1, and is a cross-sectional view along the line A-A 'similar to FIG.
1B.
Although FIG. 2 does not expand and deform the sound generator 1 in the vertical direction (Zaxis direction) as shown in FIG. 1B, the piezoelectric vibrating element 20 and the like are shown
in a simplified manner.
[0028]
In the sound generator 1, for example, components such as the piezoelectric vibration element
20 are disposed on the vibration body 10 so as to be substantially vertically symmetrical and
substantially symmetrical in FIG. 1A so that the center of gravity is near the center In this case,
the distance (wavelength) La of the nodes (the wavelength) of the nodes of the standing wave W
′ of the vibration of the vibrating body 10 becomes substantially constant throughout the
vibrating body 10 as shown by an imaginary line in FIG. However, when the interval La of the
nodes of the standing wave W 'of vibration becomes substantially constant, strong resonance
occurs at a specific frequency, so that the resonance peak and dip (valley between resonance
peaks) in the frequency characteristic of sound pressure There was a problem that the difference
would increase.
[0029]
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Therefore, in the present embodiment, the vibrating body 10 has the first region 11 and the node
L2 of the standing wave W of the vibration at the first region on the surface on which the
piezoelectric vibrating element 20 is provided, ie, the vibrating surface 10a. The second region
12 has a gap L1 between the nodes of the standing wave W of the vibration at 11 and the second
region 12 which is different. As a result, it becomes difficult to generate strong resonance at a
specific frequency, and it becomes possible to reduce the difference between the resonance peak
and the dip in the frequency characteristic of the sound pressure. The first and second regions
11 and 12 will be described later.
[0030]
Continuing with the description of the sound generator 1, in the sound generator 1, as shown in
FIG. 1B, the piezoelectric vibrating element 20 and the vibrating surface 10a of the vibrating
body 10 are covered with the covering portion 50 which is a resin. Specifically, the covering
portion 50 is configured to pour a resin into the frame of the upper frame member 30a of the
frame 30 and to cure the resin, thereby covering the piezoelectric vibrating element 20 and the
like. In FIG. 1A, for easy understanding, the covering portion 50 is transparently shown, and the
piezoelectric vibrating element 20 covered by the covering portion 50 and the vibrating surface
10 a of the vibrating body 10 are shown.
[0031]
Although resin which forms the coating ¦ coated part 50 is an epoxy resin, acrylic resin, silicone
resin, rubber ¦ gum etc., for example, these are an illustration and it is not limited. As described
above, by covering the piezoelectric vibration element 20 with the covering portion 50, an
appropriate damping effect can be induced, and it is possible to suppress the difference between
the resonance peak and the dip as well as suppressing the resonance phenomenon. preferable.
Furthermore, the piezoelectric vibrating element 20 can also be protected from the external
environment.
[0032]
In the sound generator 1 according to the present embodiment, the entire vibrating surface 10a
of the vibrating body 10 is covered with the covering portion 50, but it is not necessary to cover
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the whole. That is, in the sound generator 1, the piezoelectric vibrating element 20 and at least a
part of the vibrating surface 10 a of the vibrating body 10 on which the piezoelectric vibrating
element 20 is provided may be covered by the covering portion 50. Moreover, as a curing
method of the resin used for the coating ¦ coated part 50, you may use any methods, such as
thermosetting, photocuring, and moisture hardening.
[0033]
Here, the first area 11 and the second area 12 described above will be described in detail. The
first area 11 and the second area 12 are disposed across the piezoelectric vibrating element 20
on the vibrating surface 10a on which the piezoelectric vibrating element 20 of the vibrating
body 10 is provided, as shown in FIG. 1A. For example, the piezoelectric vibrating element 20 is
disposed so as to straddle the first area 11 and the second area 12. Further, the first area 11 and
the second area 12 are arranged side by side (in parallel) in the longitudinal direction (Y-axis
direction) of the vibrating surface 10a on which the piezoelectric vibrating element 20 of the
vibrating body 10 is provided. Specifically, the first area 11 and the second area 12 are
substantially parallel to the line 13 substantially orthogonal to the longitudinal direction on the
vibrating surface 10a, in other words, substantially parallel to the lateral direction (X-axis
direction) on the vibrating surface 10a. It is divided by the line 13 and formed. The line 13 is, for
example, a line which divides the area of the vibrating surface 10a into substantially equal parts
in the left and right in the plan view of FIG.
[0034]
Although the position of the line 13 dividing the first area 11 and the second area 12 is
illustrated in FIG. 1A and the like, the position of the line 13 is not limited to this, and the first
and second It is sufficient if it is a position at which the vibrating surface 10 a is divided so that
the regions 11 and 12 are aligned in the longitudinal direction. Further, although the vibration
surface 10a is divided into two regions of the first region 11 and the second region 12, it may be
divided into three or more regions. Also, although the line 13 is shown as a straight line, it may
be a curved line or the like. Moreover, in FIG. 1A etc., although the line 13 was shown with the
dashed-two dotted line in order to understand easily, a line is not necessarily drawn by the
vibration surface 10a.
[0035]
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The sound generator 1 further includes a damping material 60, and the damping material 60 is
attached to the surface of the covering portion 50 corresponding to the first region 11 of the
vibrating body 10 described above. Hereinafter, the damping material 60 is formed in, for
example, a substantially rectangular parallelepiped shape. However, the shape of the damping
material 60 shown to FIG. 1A etc. is an illustration, and is not limited to a substantially
rectangular parallelepiped shape.
[0036]
The damping material 60 is attached to the surface of the covering 50 via an adhesive 61 as
shown in FIG. 1B, and is integrated with the vibrating body 10, the piezoelectric vibrating
element 20, and the covering 50. In other words, the covering portion 50 is disposed between
the vibrating body 10 and the damping material 60, and the vibrating body 10, the piezoelectric
vibrating element 20, the covering portion 50, and the damping material 60 are integrally joined.
[0037]
The adhesive 61 may be, for example, a known one such as an epoxy resin, a silicone resin, or a
polyester resin, but is not limited thereto. The adhesive 61 may be cured by any method such as
heat curing, light curing, moisture curing and the like.
[0038]
The damping member 60 may be any member having a mechanical loss, but it is desirable that
the damping member 60 be a member having a high mechanical loss coefficient, in other words,
a low mechanical quality coefficient (so-called mechanical Q). Such a damping material 60 can be
formed, for example, using various elastic bodies, but since it is desirable that it be soft and easily
deformed, it can be suitably formed using a rubber material such as urethane rubber. In
particular, porous rubber materials such as urethane foam can be suitably used.
[0039]
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Further, as well shown in FIG. 1A, the damping material 60 is a surface of the covering portion
50 corresponding to the first region 11 of the vibrating body 10, and is along the short direction
(X-axis direction) of the frame 30. One is arranged as follows. In addition, although arrangement
¦ positioning of the damping material 60 was shown in FIG. 1A etc., this is an example and does
not limit arrangement ¦ positioning places.
[0040]
As described above, in the sound generator 1 according to the present embodiment, the
arrangement of the damping material 60 is made different between the first area 11 and the
second area 12. Specifically, for example, the damping material 60 is disposed on the surface of
the covering portion 50 corresponding to the first region 11 while the damping material 60 is
not disposed on the surface of the covering portion 50 corresponding to the second region 12.
Make it That is, in plan view of the vibrating body 10, the damping material 60 is disposed so as
to be asymmetrical with respect to the line 13, so that the center of gravity is shifted from near
the center.
[0041]
Thus, when the center of gravity shifts from near the center in the sound generator 1 and the
load acting on the vibrating body 10 is different between the first area 11 and the second area
12, the vibration occurring in the vibrating body 10 is determined. The standing wave W is, as
shown by a solid line in FIG. 2, an interval L 1 between nodes of the standing wave W in the first
region 11 and an interval L 2 between nodes of the standing wave W in the second region 12.
And will be different. Specifically, for example, the distance L1 of the nodes of the standing wave
W of the vibration in the first region 11 is larger than the distance L2 of the nodes of the
standing wave W of the vibration in the second region 12.
[0042]
As described above, the vibrating body 10 has the first area 11 and the second area 12 which
have different intervals of the nodes of the standing wave W of vibration, and they are arranged
side by side in the longitudinal direction of the vibrating surface 10a. As a result, strong
resonance is less likely to occur at a specific frequency, and as a result, the difference between
the resonance peak and the dip in the frequency characteristic of sound pressure is reduced to
suppress the frequency fluctuation of sound pressure as much as possible. The sound quality can
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be improved.
[0043]
Further, since the first region 11 and the second region 12 are arranged to sandwich the
piezoelectric vibrating element 20, the vibrating body 10 vibrates at different resonance
frequencies with the piezoelectric vibrating element 20 interposed therebetween. The width of
the resonance peak of the audio signal generated from the sound generator 1 can be expanded,
and the difference between the resonance peak and the dip can be further reduced.
Furthermore, even if the frequency of the wave reflected from the vibrating body 10 to the
piezoelectric vibrating element 20 is different, the role of the piezoelectric vibrating element 20
between the first region 11 and the second region 12 shielding the reflected wave Therefore, the
wave does not propagate from the other region to each region, and a sound signal can be
generated stably at the unique resonance frequency.
[0044]
In addition, since the arrangement of the damping member 60 is made different between the first
area 11 and the second area 12, the distance L1 between the nodes of the standing wave W of
the vibration in the first area 11 and the second The distance L2 between the nodes of the
standing wave W of the vibration in the region 12 of FIG.
[0045]
Further, by using the damping material 60, the area (that is, the first area 11) of the vibration
surface 10 a of the vibrating body 10 corresponding to the location where the damping material
60 is disposed is vibrated by the damping material 60 via the covering portion 50. Due to the
loss, the resonance phenomenon is suppressed.
Therefore, the resonance peak can be lowered in the frequency characteristic of the sound
pressure, and the difference between the resonance peak and the dip can be further reduced.
[0046]
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Further, in the sound generator 1, since the damping material 60 is disposed on the covering
portion 50 covering the vibrating body 10, materials having different acoustic impedances
overlap. Therefore, the attenuation of the resonance peak can be increased at the interface
between the covering portion 50 and the damping member 60, and the peak of the sound
pressure at the resonance frequency of the vibrating body 10 can be reduced more efficiently.
[0047]
In addition, although one damping material 60 is illustrated in FIG. 1A etc., the number is not
limited. For example, a plurality of damping members 60 may be provided, and in this case, the
number of disposed damping members may be different between the first region 11 side and the
second region 12 side. Furthermore, for example, the number of damping members 60 may be
the same on the first region 11 side and the second region 12 side, in which case, as shown in
FIG. It may be asymmetric with respect to the line 13 on the side of the area 11 of 1 and on the
side of the second area 12. The point is that the damping member 60 may be disposed so as to
be asymmetrical to the line 13 in plan view.
[0048]
As described above, in the sound generator 1, the vibrating body 10 has the first region 11 and
the interval L 2 between the nodes of the standing wave W of the vibration at the first surface on
the surface where the piezoelectric vibration element 20 is provided. The difference between the
resonance peak and the dip in the frequency characteristic of the sound pressure is reduced
because the second region 12 is configured to have the second region 12 different from the node
distance L1 of the standing wave W of the vibration in the region 11 Sound pressure frequency
fluctuation can be suppressed as much as possible, and sound quality can be improved.
[0049]
In addition, although the example which makes the space ¦ interval L1 and L2 of the node of the
standing wave W of a vibration different using the damping material 60 was demonstrated in the
above, it is not limited to this.
For example, as shown in FIG. 4, by shifting the piezoelectric vibrating element 20 disposed near
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the center of the vibrating body 10 toward the first region 11, the intervals L1 and L2 of the
nodes of the standing wave W of the vibration are You may make it differ. That is, by displacing
the piezoelectric vibrating element 20 to the first area 11 side, it is possible to make the load
acting on the vibrating body 10 different between the first area 11 and the second area 12,
thereby determining the vibration. The intervals L1 and L2 of the nodes of the standing wave W
can be made different.
[0050]
Furthermore, as shown in FIG. 5, by making the thickness in the Z-axis direction of the covering
portion 50 different between the first region 11 side and the second region 12 side, the distance
between the nodes of the standing wave W of vibration L1 and L2 can be different. That is, for
example, by increasing the thickness in the Z-axis direction of the covering portion 50 on the side
of the first region 11 in comparison with that on the side of the second region 12, the load acting
on the vibrating body 10 becomes the first region. 11 and the second region 12 can be made
different, so that the intervals L1 and L2 of the nodes of the standing wave W of vibration can be
made different.
[0051]
Moreover, as shown in FIG. 6, the sound generator 2 can be comprised by accommodating the
sound generator 1 of the structure mentioned above in the resonance box 200. As shown in FIG.
The resonance box 200 is a housing that accommodates the sound generator 1. The resonance
box 200 resonates the sound emitted by the sound generator 1 and emits the sound from the
housing surface as a sound wave. The sound generation device 2 can be used alone as a speaker,
or can be suitably incorporated into, for example, various electronic devices 3.
[0052]
As described above, since it is possible to reduce the difference between the resonance peak and
the dip in the frequency characteristic of the sound pressure which is disadvantageous in the
piezoelectric speaker, the sound generator 1 according to the present embodiment is a mobile
phone or a thin television Or, it is possible to be suitably incorporated in an electronic device 3
such as a tablet terminal.
[0053]
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The electronic device 3 to which the sound generator 1 can be incorporated is not limited to the
above-described mobile phone, flat-screen TV, tablet terminal, etc., but, for example, a
refrigerator, a microwave, a vacuum cleaner, a washing machine, etc. Also included are home
appliances that were not previously considered important for sound quality.
[0054]
Here, the electronic device 3 provided with the above-described sound generator 1 will be briefly
described with reference to FIG.
FIG. 7 is a block diagram of the electronic device 3.
The electronic device 3 includes the sound generator 1 described above, an electronic circuit
connected to the sound generator 1, and a housing 300 for housing the sound generator 1 and
the electronic circuit.
[0055]
Specifically, as shown in FIG. 7, the electronic device 3 accommodates an electronic circuit
including a control circuit 301, a signal processing circuit 302, and a wireless circuit 303 as an
input device, an antenna 304, and the like. A housing 300 is provided. Although the wireless
input device is illustrated in FIG. 7, it can naturally be provided as a signal input by ordinary
electrical wiring.
[0056]
In addition, description is abbreviate ¦ omitted about the other electronic members (For example,
devices and circuits, such as a display, a microphone, a speaker, etc.) with which the electronic
device 3 is equipped, here. Moreover, although one sound generator 1 was illustrated in FIG. 7,
two or more sound generators 1 and other transmitters can also be provided.
[0057]
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The control circuit 301 controls the entire electronic device 3 including the wireless circuit 303
via the signal processing circuit 302. An output signal to the sound generator 1 is input from the
signal processing circuit 302. Then, the control circuit 301 generates the audio signal S by
controlling the signal processing circuit 302 and outputs the signal input to the wireless circuit
303 to the sound generator 1.
[0058]
Thus, the electronic device 3 shown in FIG. 7 reduces the difference between the resonance peak
and the dip to suppress the frequency fluctuation as much as possible while incorporating the
small and thin acoustic generator 1. The sound quality can be improved as a whole even in the
low tone region as well as the low tone region.
[0059]
In addition, in FIG. 7, although the electronic device 3 which mounted the acoustic generator 1
directly as an acoustic output device was illustrated, as an acoustic output device, the acoustic
generator 2 which accommodated the acoustic generator 1 in the housing is mounted, for
example The configuration may be different.
[0060]
Second Embodiment FIG. 8 is a schematic plan view showing an acoustic generator 1 according
to a second embodiment.
As shown in FIG. 8, in the sound generator 1 according to the second embodiment, the first area
11 a and the second area 12 a are vibration planes in which the piezoelectric vibration element
20 of the vibration body 10 is provided. It is arrange ¦ positioned along with the transversal
direction (X-axis direction) of 10a.
[0061]
Specifically, the first area 11a and the second area 12a are substantially parallel to the
longitudinal direction (Y-axis direction) in the vibrating surface 10a, in other words, a line 13a
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substantially orthogonal to the lateral direction in the vibrating surface 10a. It is divided and
formed by the line 13a.
The line 13a is, for example, a line which divides the area of the vibrating surface 10a into upper
and lower portions substantially equally in a plan view of FIG.
[0062]
Although FIG. 8 illustrates the position of the line 13a that divides the first area 11a and the
second area 12a, the position of the line 13a is not limited to this, and the first and second
positions are not limited. Any position may be used as long as it divides the vibration surface 10
a so that the regions 11 a and 12 a are aligned in the lateral direction.
[0063]
The damping material 60 is attached to the surface of the covering portion 50 corresponding to
the first area 11 a of the vibrating body 10 as in the first embodiment described above.
Specifically, the damping member 60 is disposed, for example, on the surface of the covering
portion 50 corresponding to the first region 11a, in the vicinity of the piezoelectric vibrating
element 20 in plan view and along the longitudinal direction of the frame 30. Ru. The
arrangement of the damping member 60 is not limited to the illustrated example as in the first
embodiment.
[0064]
As a result, the load acting on the vibrating body 10 is different between the first area 11a and
the second area 12a, whereby the standing wave W of the vibration generated in the vibrating
body 10 is vibrated in the first area 11a. The interval L1 of the nodes of the standing wave W
and the interval L2 of the nodes of the standing wave W of the vibration in the second region
12a are made different.
[0065]
Therefore, even in the sound generator 1 according to the second embodiment, strong resonance
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is less likely to occur at a specific frequency, and as a result, the difference between the
resonance peak and the dip is reduced in the frequency characteristic of sound pressure. The
frequency variation of pressure can be suppressed as much as possible, and the sound quality
can be improved.
The remaining configuration and effects are the same as in the first embodiment, and thus the
description thereof is omitted.
[0066]
Further, another arrangement example of the first and second regions is shown in FIG. As shown
in FIG. 9, the first region 11 b and the second region 12 b are strip-like regions including the
diagonal line 14 of the vibrating surface 10 a on which the piezoelectric vibrating element 20 of
the vibrating body 10 is provided (specifically, FIG. In the area 15 surrounded by a broken line in
9), the lines may be arranged in the direction of the diagonal line 14.
[0067]
Specifically, the first area 11 b and the second area 12 b are formed by being divided by the line
13 b substantially orthogonal to the diagonal line 14 in the band-like area 15 of the vibrating
surface 10 a. The line 13 b is a line which divides the area of the band-like region 15 of the
vibrating surface 10 a into, for example, the upper right portion and the lower left portion in a
plan view of FIG.
[0068]
In addition, the position of the line 13b shown in FIG. 9 is an illustration and is not limited. That
is, the line 13 b may be any position as long as it divides the band-like area 15 so that the first
and second areas 11 b and 12 b are arranged in the direction of the diagonal line 14.
[0069]
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The damping material 60 is attached to the surface of the covering portion 50 corresponding to
the first region 11 b of the vibrating body 10 as in the first and second embodiments described
above. Specifically, the damping material 60 is disposed, for example, on the surface of the
covering portion 50 corresponding to the first region 11 a and in the vicinity of the corner of the
frame 30.
[0070]
Thereby, also in the example shown in FIG. 9, the load acting on the vibrating body 10 is
different between the first area 11 b and the second area 12 b, and in the standing wave W of
the vibration generated in the vibrating body 10, The interval L1 of the nodes of the standing
wave W of the vibration in the first region 11b is made different from the interval L2 of the
nodes of the standing wave W of the vibration in the second region 12b.
[0071]
Therefore, even in the example shown in FIG. 9, since strong resonance hardly occurs at a
specific frequency, the difference between the resonance peak and the dip in the frequency
characteristic of the sound pressure is reduced to allow the frequency fluctuation of the sound
pressure. The sound quality can be improved.
Each modification described in the first embodiment can also be applied to the sound generator 1
according to the second embodiment and the sound generator 1 shown in FIG.
[0072]
In the embodiment described above, the positions at which the first regions 11, 11a and 11b and
the second regions 12, 12a and 12b are disposed in the vibrator 10 are specifically described,
but these are only examples. It is not limited. The point is that in the sound generator 1, if the
first regions 11, 11 a, 11 b and the second regions 12, 12 a, 12 b are arranged in the vibrating
body 10 so as to reduce the difference between the resonance peak and the dip. Good.
[0073]
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In the embodiment described above, the piezoelectric vibrating element 20 is disposed on the
same surface of the vibrating surface 10 a of the vibrating body 10, but may be disposed on both
sides. Further, although the piezoelectric vibrating element 20 is rectangular in plan view, it may
be square.
[0074]
In addition, although the vibrating surface 10a of the vibrating body 10 is rectangular, this is an
example and is not limited. For example, it may be polygonal other than rectangular, circular or
elliptical, or any other shape. . That is, the shape of the frame 30, that is, the shape of the inside
(inner edge) of the frame 30 may be, for example, a polygonal shape other than a rectangular
shape, or another shape such as a circle or an oval.
[0075]
Further, in the above description, the case where the frame 30 is configured by the two frame
members 30a and 30b and the outer peripheral portion of the vibrating body 10 is sandwiched
and supported by the two frame members 30a and 30b is exemplified. However, it is not limited
to this. For example, the frame 30 may be configured of a single frame member, and the outer
peripheral portion of the vibrating body 10 may be adhered and fixed to the frame 30 and
supported.
[0076]
Moreover, although the so-called bimorph-type laminated type is illustrated as the piezoelectric
vibration element 20, a unimorph-type piezoelectric vibration element can also be used.
[0077]
Although the case where the exciter is the piezoelectric vibrating element 20 has been described
as an example, the exciter is not limited to the piezoelectric vibrating element, and has a function
of receiving an electric signal to vibrate. Anything is fine.
For example, an electrodynamic exciter, an electrostatic exciter, or an electromagnetic exciter
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well known as an exciter for vibrating a speaker may be used. It is to be noted that the
electrodynamic exciter is such that a current is supplied to the coil disposed between the
magnetic poles of the permanent magnet to vibrate the coil, and the electrostatic exciter is
formed of two facing metals The bias and the electrical signal are supplied to the plate to cause
the metal plate to vibrate, and the electromagnetic exciter is to cause the electrical signal to flow
to the coil to cause the thin iron plate to vibrate.
[0078]
Further, in the above-described embodiment, the piezoelectric vibrating element 20 and the
vibrator 10 are covered by the covering portion 50. However, the present invention is not limited
to this. The covering portion 50 may not be provided.
[0079]
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.
[0080]
DESCRIPTION OF SYMBOLS 1 sound generator 2 sound generator 3 electronic device 10
vibrator 11, 11a, 11b 1st area ¦ region 12, 12a, 12b 2nd area ¦ region 20 piezoelectric vibration
element 30 frame 40 junction part 50 coating part 60 damping material 200 resonance Box
(casing) 300 Casing 301 Control circuit 302 Signal processing circuit 303 Radio circuit 304
Antenna
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