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JPWO2015182197

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DESCRIPTION JPWO2015182197
Abstract: PROBLEM TO BE SOLVED: To provide a sound generator with improved sound quality,
a sound generator including the same, and an electronic apparatus. SOLUTION: A sound
generator 1 of the present invention has a piezoelectric element 11 as an exciter and a
piezoelectric element 11 attached thereto, and a diaphragm 12 that vibrates together with the
piezoelectric element 11 by the vibration of the piezoelectric element 11; 12 includes a frame 13
provided on the outer peripheral portion of the frame 12 to support the diaphragm 12, and a
cover layer 14 provided on the inner side of the frame 13. The cover layer 14 is different from
the resin 141 in the resin 141 A plurality of fillers 142 made of a material is included. [Selected
figure] Figure 1
Acoustic generator, acoustic generator provided with the same, electronic device
[0001]
The present invention relates to an acoustic generator, an acoustic generator including the same,
and an electronic device.
[0002]
A small-sized, low-current-driven acoustic generator using a piezoelectric element as an exciter
(electro-acoustic transducer) is known.
Such a sound generator can be used by being incorporated into a small electronic device such as
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a mobile computing device, for example.
[0003]
Specifically, such a sound generator includes a diaphragm, a frame supporting the outer
peripheral portion of the diaphragm, and a piezoelectric element mounted on the diaphragm (for
example, Patent Document 1). reference).
[0004]
JP, 2013-162141, A
[0005]
Here, since the above-mentioned sound generator utilizes resonance, there is a possibility that
peak dip may occur in sound pressure and sound quality may be degraded.
Sound generators are required to further improve the sound quality.
[0006]
The present invention has been made in view of the above circumstances, and an object of the
present invention is to provide an acoustic generator having improved sound quality, and an
acoustic generator and an electronic apparatus provided with the acoustic generator.
[0007]
The sound generator of the present invention comprises an exciter, a diaphragm to which the
exciter is attached, a frame provided on the outer peripheral portion of the diaphragm to support
the diaphragm, and provided inside the frame And the covering layer is characterized in that the
covering layer contains a plurality of fillers of a material different from the resin in the resin.
[0008]
A sound generator according to the present invention is characterized by comprising the sound
generator according to any one of the above and a case for housing the sound generator.
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[0009]
Furthermore, an electronic device according to the present invention includes the sound
generator according to any one of the above, an electronic circuit connected to the sound
generator, and a case for housing the electronic circuit and the sound generator. It is
characterized by
[0010]
According to the sound generator of the present invention, the propagating vibration is changed
by the filler to suppress the resonance, so it is possible to suppress the peak dip and flatten the
frequency characteristic.
Therefore, the sound quality is improved.
[0011]
(A) is a schematic plan view which shows an example of embodiment of the sound generator of
this invention, (b) is the AA line schematic sectional drawing shown to (a).
(A) is a schematic plan view showing another example of the embodiment of the sound generator
of the present invention, (b) is a schematic bottom view of the sound generator shown in (a), (c)
is (a) It is an AA line schematic sectional view shown to.
It is a schematic sectional drawing of the piezoelectric element shown to FIG. 1 and FIG.
The variation of the filler contained in the sound generator of this invention is shown, (a) is
spherical, (b) is flake-like, (c) is needle-like, and (d) is random.
It is the graph which contrasted an example of the frequency characteristic of sound pressure
with an example of the present invention, and a comparative example. It is a figure which shows
the structure of embodiment of the sound generation apparatus of this invention. It is a figure
which shows the structure of embodiment of the electronic device of this invention.
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[0012]
Hereinafter, an example of an embodiment of a sound generator of the present invention will be
described with reference to the drawings.
[0013]
Fig.1 (a) is a schematic plan view which shows an example of embodiment of the sound
generator of this invention, FIG.1 (b) is an AA line schematic sectional drawing shown to Fig.1 (a).
Further, FIG. 2 (a) is a schematic plan view showing another example of the embodiment of the
acoustic generator of the present invention, and FIG. 2 (b) is a schematic bottom view of the
acoustic generator shown in FIG. 2 (a). 2 (c) is a schematic cross-sectional view taken along the
line AA shown in FIG. 2 (a).
[0014]
The sound generator 1 of the example shown in FIGS. 1 and 2 includes a piezoelectric element
11 as an exciter, a diaphragm 12 to which the piezoelectric element 11 is attached, and a
diaphragm 12 provided on the outer peripheral portion of the diaphragm 12. The covering layer
14 includes a plurality of fillers 142 made of a material different from the resin 141 in the resin
141, including the supporting frame 13 and the covering layer 14 provided on the inner side of
the frame 13.
[0015]
As an exciter which comprises the sound generator 1, the plate-shaped piezoelectric element 11
is used, for example.
The piezoelectric element 11 is attached by being attached to the surface of the diaphragm 12 or
the like, and excites the diaphragm 12 by vibrating upon receiving an applied voltage.
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[0016]
For example, as shown in FIG. 3, in the case where the piezoelectric element 11 is used as an
exciter, piezoelectric layers 11a, 11b, 11c and 11d made of four layers of ceramics alternate with
three internal electrode layers 11e. And the surface electrode layers 11f and 11g formed on the
upper and lower surfaces of the laminate, and the external electrodes 11h and 11i formed on the
side surfaces from which the internal electrode layer 11e is derived.
[0017]
The piezoelectric layer constituting the piezoelectric element 11 is formed of a ceramic having
piezoelectric characteristics, and as such ceramics, lead zirconate titanate, lithium niobate,
lithium tantalate, Bi layered compound Conventional piezoelectric ceramics such as lead-free
piezoelectric materials such as tungsten bronze structure compounds can be used.
The thickness of one layer of the piezoelectric layer is preferably set to, for example, 0.01 to 0.1
mm in order to drive at a low voltage. Further, in order to obtain a large flexural vibration, it is
preferable to have a piezoelectric constant d31 of 200 pm / V or more.
[0018]
The internal electrode layer 11e constituting the piezoelectric element 11 is formed by co-firing
with the ceramic forming the piezoelectric layers 11a, 11b, 11c and 11d, and is a first internal
electrode connected to the external electrode 11h. It consists of a layer and the 2nd internal
electrode layer connected to the exterior electrode 11i. The internal electrode layers 11e are
alternately stacked with the piezoelectric layers 11a, 11b, 11c, and 11d, and by arranging the
first internal electrode layer and the second internal electrode layer in the stacking order, the
surface electrode 11f, A driving voltage is applied to the piezoelectric layers 11a, 11b, 11c, and
11d sandwiched between 11g and the internal electrode layer 11e. Various metal materials can
be used as a material for forming the internal electrode layer 11 e. For example, a conductor
containing silver or silver-palladium as a main component suitable for low-temperature firing, or
a conductor containing copper, platinum or the like can be used, but these may contain a ceramic
component or a glass component. When the internal electrode layer 11e is formed of a material
containing a metal component of silver and palladium and a ceramic component of the
piezoelectric layers 11a, 11b, 11c and 11d, the piezoelectric layers 11a, 11b and 11c are formed.
Since the stress due to the firing shrinkage difference between 11 d and the internal electrode
layer 11 e can be reduced, it is possible to obtain the piezoelectric element 11 without a stacking
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fault.
[0019]
As the exciter, for example, a piezoelectric element 11 is preferably made of a plate-like body
whose main surface on the upper surface side and the lower surface side has a polygonal shape
such as a rectangular shape or a square shape, or a circular shape or an elliptical shape. The
sound generator 1 can be made thin by using the piezoelectric element 11 and the diaphragm 12
and frame 13 described later.
[0020]
Furthermore, it is preferable to make the piezoelectric element 11 into a bimorph structure.
That is, it is preferable that the polarization direction with respect to the direction of the electric
field applied at a certain moment be polarized so as to be reversed on one side and the other side
in the thickness direction. Since the diaphragm 12 can be efficiently vibrated with a small
amount of energy while contributing to thinning, the sound generator 1 of high volume can be
obtained. In addition, although the bimorph-type laminated-type piezoelectric element was
mentioned as the example as the piezoelectric element 11, it may be a unimorph-type
piezoelectric element (multilayer-type piezoelectric element to expand-contract).
[0021]
The diaphragm 12 which comprises the sound generator 1 can be formed using various
materials, such as resin and a metal. For example, the diaphragm 12 can be made of a resin film
of polyethylene, polyimide or the like having a thickness of 10 to 200 μm.
[0022]
A piezoelectric element 11 as an exciter is attached to the diaphragm 12. Specifically, the main
surface of the piezoelectric element 11 is bonded to the main surface of the diaphragm 12 with
an adhesive such as epoxy resin.
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[0023]
The vibration plate 12 vibrates together with the piezoelectric element 11 by the vibration of the
piezoelectric element 11. For example, in the case where the piezoelectric element 11 is a
piezoelectric element having a bimorph structure, the wiring member 15 is connected to the
external electrode, and an electric signal is applied to the piezoelectric element 11 through the
wiring member 15 (voltage is applied And at a certain moment, the piezoelectric layer on the side
(lower surface side of the piezoelectric element 11) bonded to the diaphragm 12 shrinks in the
in-plane direction perpendicular to the stacking direction, and the piezoelectric layer on the
upper surface side of the piezoelectric element 11 It is deformed so as to extend in the in-plane
direction perpendicular to the stacking direction, and is bent toward the diaphragm 12 side.
Therefore, by applying an alternating current signal to the piezoelectric element 11, the
piezoelectric element 11 can be bent and vibrated, and can be bent and vibrated to the
diaphragm 12. As the wiring member 15, a flexible substrate (FPC), a metal plate or the like in
which a lead wire, for example, a metal foil such as copper or aluminum is sandwiched between
resin films is used. It is advantageous for thinning and shortening.
[0024]
A frame 13 is provided to support the outer peripheral portion of the diaphragm 12. As the
frame 13, for example, a frame member whose inner peripheral shape and outer peripheral
shape are rectangular can be used. In the example shown in FIG. 1, the frame 13 is composed of
a frame member 131 provided only on the one main surface side of the diaphragm 12, and the
outer periphery of the diaphragm 12 is attached to this to configure the sound generator 1. ing.
On the other hand, in the example shown in FIG. 2, the frame 13 is composed of the one main
surface side frame member 131 provided on the one main surface side and the other main
surface side frame member 132 provided on the other main surface side. The diaphragm 3 is
supported by sandwiching the outer peripheral portion 12. The outer peripheral portion of the
diaphragm 12 is sandwiched and fixed between the one main surface side frame member 131
and the other main surface side frame member 132 which constitute the frame 13. Thus, the
diaphragm 12 is supported by the frame 13 in a stretched state within the frame of the frame 13.
A portion of the diaphragm 12 in FIG. 1 located inside the frame 13, and one of the main surface
side frame member 131 and the other main surface side frame member 132 of the frame 12 in
the diaphragm 12 of FIG. 2. The parts that are not sandwiched by are able to vibrate freely.
[0025]
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The thickness, the material, and the like of the one main surface side frame member 131 and the
other main surface side frame member 132 which constitute the frame 13 are not particularly
limited. As thickness of one side principal surface side frame member 131 which constitutes
frame 13, and the other side principal surface side frame member 132, a 100-5000 micrometers
thing is employable, for example. Moreover, as a material of the one main surface side frame
member 131 which comprises the frame 13, and the other main surface side frame member 132,
various materials, such as glass, a metal, and resin, can be used, for example. In the case of glass,
since there is mechanical strength, deformation of the one main surface side frame member 131
and the other main surface side frame member 132 is small, and the sound quality is stabilized.
In the case of metal, the rigidity is smaller than that of glass, and the difference between the
resonance peak and the dip is further dispersed, and the frequency characteristics can be
flattened. Therefore, the sound quality can be improved by flattening the sound pressure.
Further, in the case of resin, the rigidity is smaller than that of metal, and the difference between
the resonance peak and the dip is dispersed, and the frequency characteristics can be flattened.
Therefore, the sound quality can be improved by flattening the sound pressure.
[0026]
In addition, although the frame 13 is a rectangular shape and the example of the shape of the
area ¦ region of the inner side is a rectangular shape is shown in FIG. 1 and FIG. 2, dispersion ¦
distribution of resonance by the aspect ratio being larger than 1 is shown. Contribute to the peak
/ dip flattening. However, it may be a polygon such as a square, a parallelogram, a trapezoid and
a regular n-gon, or may be a circle or an ellipse.
[0027]
Moreover, although the case where the number of piezoelectric elements 11 is one is illustrated
in the figure, the number of piezoelectric elements 11 is not limited. Although the figure shows
the case where the piezoelectric element 11 is provided on one main surface of the diaphragm
12, the piezoelectric element 11 may be provided on both sides of the diaphragm 12.
[0028]
The frame 13 (one main surface side frame member 131 and the other main surface side frame
member 132) may be a plurality of frame members in the circumferential direction, and these
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may be joined to each other.
[0029]
The sound generator 1 further includes a covering layer 14 provided on the inside of the frame
13.
The covering layer 14 includes a resin 141 and a plurality of fillers 142 made of a material
different from the resin 141, and the plurality of fillers 142 is contained in the resin 141. Note
that among the plurality of fillers 142 shown in the figure, those shown by broken lines show a
state in which they are seen through.
[0030]
Examples of the resin 141 constituting the covering layer 14 include acrylic resins, epoxy resins,
radical polymerization resins, cationic polymerization resins, and phenol resins.
[0031]
The plurality of fillers 142 contained in the resin 141 may be resin, metal or the like as long as
the material has a difference in Young's modulus or density in relation to the resin 141, but the
Young's modulus with the resin 141 may be used. In view of the difference in density and the
insulating property, for example, ceramics such as zirconia and alumina, glass fibers and the like
can be mentioned.
[0032]
As a shape of the filler 142, as shown in FIG. 4, (a) spherical shape, (b) flake shape (flat shape),
(c) needle shape, (d) random shape etc. are mentioned, for example.
If the filler 142 is in the form of flakes as shown in FIG. 4B, the adjacent fillers 142 are disposed
parallel to the diaphragm 12 and overlap each other to easily follow the diaphragm 12 and
vibrate as a damper. The effect of
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Thereby, specific peak dips can be suppressed. In addition, if the filler 142 has a needle shape as
shown in FIG. 4C, the filler 142 crosses in three dimensions, so deformation of the covering layer
14 is reduced.
[0033]
As a size of the filler 142, for example, when the filler 142 is spherical, a filler having a diameter
of 0.5 to 70 μm is employed. Moreover, the thing of the same magnitude ¦ size is employable
also in shapes other than spherical shape.
[0034]
Here, the plurality of fillers 142 may not be collected at one place, but may be disposed in a
dispersed manner, and this state is, for example, directly polishing or measuring the sample to be
measured with abrasive paper. The sample can be embedded in an acrylic resin or the like,
polished in cross section, and observed by a scanning electron microscope (SEM).
[0035]
Moreover, as a ratio in which the filler 142 is contained, when the coating layer 14 is cut ¦
disconnected by arbitrary cross sections and the said cross section is seen, it is contained in the
grade which the filler 142 occupies 1 to 50% of area, The lowest resonance frequency f0 of the
sound generator 1 may be lowered to flatten the sound pressure.
[0036]
Since the covering layer 14 contains a plurality of fillers 142 made of a material different from
that of the resin 141, the propagating vibration is changed by the fillers 142.
Specifically, the vibration propagating from the piezoelectric element 11 and the vibration plate
12 is dispersed by the filler 142, and the resonance peak is damped and becomes smaller.
Further, the spurious vibration due to the reflected wave from the one main surface side frame
member 131 is also dispersed by the filler 142, and the resonance peak of the spurious vibration
is also damped and becomes smaller. Thereby, the peak / dip in the frequency-sound pressure
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characteristic is suppressed, this characteristic can be made flat, and the sound quality can be
improved.
[0037]
When the filler 142 has a thermal conductivity higher than that of the resin 141, for example, a
ceramic or metal, the heat dissipation effect is enhanced by the inclusion of the plurality of fillers
142 in the covering layer 14, and the temperature of the diaphragm 12 is increased. It is possible
to suppress the reduction in tension and reduce the strain rate. Therefore, the sound quality is
further improved.
[0038]
Furthermore, when the filler 142 has a Young's modulus higher than that of the resin 141, for
example, a ceramic or a metal, the covering layer 14 contains a plurality of fillers 142, so that
deformation of the covering layer 14 is reduced. The deformation of the element 11 is also
reduced and the durability is also improved.
[0039]
The covering layer 14 may not necessarily be provided to cover the surface of the piezoelectric
element 11 as long as the covering layer 14 is provided to cover the diaphragm 12, but is
provided before covering the surface of the piezoelectric element 11, By embedding the
piezoelectric element 11 in the covering layer 14, an appropriate damping effect can be induced.
In the figure, the covering layer 14 is shown to be formed to have the same height as the frame
13, but the covering layer 14 may be formed to be higher than the height of the frame 132.
[0040]
Moreover, it is preferable that the Young's modulus of the coating layer 14 is lower than the
Young's modulus of the piezoelectric element 11 which is an exciter. Since the Young's modulus
of the covering layer 14 is lower than the Young's modulus of the piezoelectric element 11, it is
difficult to inhibit the vibration, and the sound pressure in the low range can be increased. The
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Young's modulus can be compared by preparing a sample piece of the piezoelectric element 11
and the coating layer 14 having the same size as that of the piezoelectric element 11 and
performing a tensile test so as to be pulled in the longitudinal direction. .
[0041]
For example, the coating layer 14 contains 0.5% to 10% of a zirconia resin as a filler in an area
ratio as viewed from an arbitrary cross section in a phenol resin, and the piezoelectric element
11 is made of lead zirconate titanate. In the case of an element provided with a piezoelectric
layer, the Young's modulus of the covering layer 14 can be made lower than the Young's
modulus of the piezoelectric element 11.
[0042]
Here, a graph of the difference in the frequency characteristics of the sound pressure between
the acoustic generator provided with the covering layer not containing the filler and the acoustic
generator provided with the covering layer 14 containing the filler 142 is shown in FIG.
In the graph shown in FIG. 5, the horizontal axis represents frequency and the vertical axis
represents sound pressure.
[0043]
The sound generator compared has the same configuration except for the presence or absence of
the filler 142, that is, the respective members, their dimensions and materials.
[0044]
In FIG. 5, the peaks and dips respectively located in the frequency band of 1 kHz to 2 kHz and in
the frequency band of 10 kHz to 20 kHz are provided with the covering layer 14 including the
filler 142 against the acoustic generator provided with the covering layer not including the filler.
The sound generator is smaller.
Further, the sound pressure of the sound generator provided with the covering layer 14
containing the filler 142 is higher than that of the sound generator provided with the covering
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layer not containing the filler in the low frequency band of 500 Hz or less. Thus, when the filler
142 is contained in the resin 141, the peak and dip become smaller and the flatness of the sound
pressure is improved and the frequency characteristic of the sound pressure is improved as
compared with the case where the filler is not contained. Be done.
[0045]
Here, it is preferable that at least a part of the plurality of fillers 142 be in contact with the
portion where the Young's modulus changes. As a portion where Young's modulus changes, the
boundary between the piezoelectric element 11 and the covering layer 14, the boundary between
the frame 13 (one main surface side frame member 131) and the covering layer 14, the
boundary between the diaphragm 12 and the covering layer 14 Etc. By being at these
boundaries, the vibrations propagated at the boundaries are disturbed and the effect of being
dispersed is enhanced.
[0046]
Further, as shown in FIG. 4D, it is preferable that the sizes or the shapes of the plurality of fillers
142 contained in the covering layer 14 be nonuniform. In other words, non-uniform size or
shape of the plurality of fillers 142 means that the fillers 142 having different sizes or different
shapes are included beyond the uniform range.
[0047]
If the size of the plurality of fillers 142 is uniform, for example, prepare an image including, for
example, 100 fillers 142 photographed at an arbitrary magnification with an optical microscope
or an electron microscope, and the respective fillers 142 in this image are prepared. The particle
diameter of the filler is determined, and the filler 142 having the largest particle diameter and
the filler 142 having the smallest particle diameter are within the range of plus or minus 10% of
the average particle diameter. Here, the particle diameter of the filler 142 draws a plurality of
parallel line segments from one direction with respect to the image. At this time, the line segment
is drawn to be in contact with one end and the other end of one filler 142, and the distance
between them is taken as the particle diameter. This is done similarly for each filler 142 in the
image. Moreover, an average particle diameter calculates ¦ requires the particle diameter of the
said 100 pieces of fillers 142, for example, and calculates an average value. And when the filler
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142 which remove ¦ deviates from the range of the magnitude ¦ size of +/- 10% of average
particle diameter exists, suppose that the magnitude ¦ sizes of the some filler 142 are nonuniform ¦ heterogenous.
[0048]
On the other hand, when the shapes of the plurality of fillers 142 are nonuniform, for example,
when the fillers 142 are observed with an optical microscope or an electron microscope, a
plurality of fillers 142 having different shapes such as spheres, plates or needles are included. It
is meant to include a plurality of fillers 142 which are not identical or similar.
[0049]
Also, for example, the size of a plurality (for example, 500 pieces) of fillers 142 is determined
from an image or photograph taken with an optical microscope or an electron microscope at an
arbitrary magnification, and a test of normality is regarded as a significance level 0.05 from this
measurement result. It can also be judged that the shape is nonuniform when the normality is
rejected.
[0050]
When the size or shape of the plurality of fillers 142 is nonuniform, differences in elastic
modulus and density partially occur in the planar direction or thickness direction of the covering
layer 14, and resonance can be divided.
In addition, since differences occur in the average particle size and particle size distribution of
the filler 142, and dispersion and scattering of waves propagating in a wider frequency band can
be induced, the peak dip can be further suppressed and the frequency characteristics (especially
high frequency characteristics) ) Can be flattened, and the sound quality is further improved.
[0051]
For example, in the case where the filler 142 is spherical, an example in which the filler 142
having a diameter of at most 70 μm to the filler 142 having a diameter of at least 0.5 μm is
included.
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Moreover, as a shape of the filler 142, the example etc. which are contained, for example from a
spherical thing to flake shape (flat shape) and a needle-like thing etc. are mentioned. This state
can be confirmed, for example, by directly polishing the sample to be measured with abrasive
paper or embedding the sample to be measured in an acrylic resin or the like to cross-section
polish and observing with a scanning electron microscope (SEM).
[0052]
Note that a plurality of fillers 142 of different types of materials may be randomly dispersed,
which also achieves the above-described effect of improving the sound quality.
[0053]
In addition, it is preferable that the packing density of the filler 142 contained in the covering
layer 14 be nonuniform when viewed over the entire covering layer 14.
The non-uniform packing density of the filler 142 means that the packing density of the filler
142 has a region higher or lower than other regions.
[0054]
This state can be confirmed, for example, by directly polishing the sample to be measured with
abrasive paper or embedding the sample to be measured in an acrylic resin or the like to crosssection polish and observing with a scanning electron microscope (SEM).
[0055]
Here, that the packing density is uniform means, for example, dividing (for example, dividing into
six) each of the cross sections in any two planar directions parallel to the main surface of the
diaphragm 12 into substantially the same area, and dividing each Seeing the images taken at the
same magnification of about 50 to 500 times for any one place (for example, 12 places in total)
of the area, the area occupied by the filler 142 in each image is determined and the average
value is calculated. It means that the maximum value and the minimum value of the area
occupied by the filler 142 of each divided area with respect to the value are within the range of
plus or minus 10%.
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[0056]
Further, for example, the cross section cut in the plane direction may be prepared at the upper
surface side and the lower surface side of the covering layer 14 in the thickness direction, and
the above measurement may be performed.
Also, the top surface of the covering layer 14 may be measured instead of one cross section.
[0057]
And, the non-uniform packing density means that the area occupied by the filler 142 in the
above measurement is outside the range of plus or minus 10%.
[0058]
This state can be confirmed, for example, by directly polishing the sample to be measured with
abrasive paper or embedding the sample to be measured in an acrylic resin or the like to crosssection polish and observing with a scanning electron microscope (SEM).
[0059]
Due to the non-uniform packing density of the filler 142, the density of the filler 142 can be
changed in the planar direction or thickness direction of the coating layer 14.
As a result, the vibration is dispersed, and the frequency-sound pressure characteristic is
flattened. Therefore, the peak dip can be further suppressed to flatten the frequency
characteristic (particularly, the high-frequency characteristic), and the sound quality is further
improved. .
[0060]
In addition, in order to change the packing density of the filler 142, for example, after preparing
two or more types of resin 141 which varied the density ¦ concentration of the filler 142 and
filling each with a dispenser, another one from these several dispensers simultaneously The resin
141 is filled in the dispenser, and the resin 141 is filled and cured in the frame without stirring
and mixing, or two or more types of resins 141 having different concentrations of the filler 142
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are prepared, and After filling, the resin 141 is simultaneously discharged from the plurality of
dispensers into the frame to be cured, or, for example, the resin adjusted to the first
concentration is filled to 1/10 of the coating layer and then adjusted to the second concentration.
The resin 141 is dropped to a plurality of places, and then the resin 141 adjusted to the first
concentration is filled with 1/10 of the coating layer. Method of filling the resin 141 with
specified amount and then curing, Method of filling resin with different filler 142 on resin 141
containing cured filler 142, about 30 minutes before curing resin 141 A technique of leaving it
to settle and settling the filler 142 is used.
[0061]
Next, an example of the embodiment of the sound generator of the present invention will be
described.
[0062]
The sound generation device 20 is a sound generation device such as a so-called speaker, and as
shown in FIG. 6, for example, includes a sound generator 1 and a housing 30 for housing the
sound generator 1.
The housing 30 resonates the sound emitted by the sound generator 1 internally, and radiates
the sound to the outside from an opening (not shown) formed in the housing 30.
The housing 30 can be formed using, for example, various materials such as metals such as
aluminum and magnesium alloy, resins such as polycarbonate, and wood.
By including such a housing 30, sound pressure in, for example, a low frequency band can be
increased.
[0063]
The sound generation device 20 can be used alone as a speaker, and can be suitably incorporated
into a portable terminal, a flat-screen television, a tablet terminal, or the like as described later.
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In addition, it can be incorporated into home appliances such as refrigerators, microwave ovens,
vacuum cleaners, washing machines, etc., for which sound quality has not been emphasized
conventionally.
[0064]
Next, an electronic device mounted with a sound generator will be described using FIG. FIG. 7 is a
view showing the configuration of the electronic device 50 according to the embodiment. In the
drawings, only components necessary for the description are shown, and description of general
components is omitted.
[0065]
As shown in FIG. 7, the electronic device 50 of the present example includes an acoustic
generator 1, an electronic circuit 60 connected to the acoustic generator 1, and a case 40 that
accommodates the electronic circuit 60 and the acoustic generator 1. Prepare. In the example
shown in FIG. 7, it is assumed that the electronic device 50 is a portable terminal device such as a
mobile phone or a tablet terminal.
[0066]
As shown in FIG. 7, the electronic device 50 includes an electronic circuit 60. The electronic
circuit 60 includes, for example, a controller 50a, a transmitting / receiving unit 50b, a key input
unit 50c, and a microphone input unit 50d. The electronic circuit 60 is connected to the sound
generator 1 and has a function of outputting an audio signal to the sound generator 1. The sound
generator 1 generates a sound based on the sound signal input from the electronic circuit 60.
[0067]
In addition, the electronic device 50 includes the display unit 50e, the antenna 50f, and the
sound generator 1, and includes the housing 40 that accommodates these devices. Although FIG.
7 shows a state in which all the devices including the controller 50a are housed in one housing
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40, the housing form of each device is not limited. In the present embodiment, at least the
electronic circuit 60 and the sound generator 1 may be accommodated in one housing 40.
[0068]
Here, the sound generator 1 is accommodated in the housing 40 by being joined to the inner wall
of the housing 40, for example. At this time, the bonding member for bonding the sound
generator 1 is a bonding member including a visco-elastic body at least in part. The joining
member may be a single body consisting only of a visco-elastic body or a composite body
consisting of several members including a visco-elastic body. As such a joining member, for
example, a double-sided tape or the like in which an adhesive is attached to both sides of a base
material layer made of non-woven fabric or the like can be suitably used. The thickness of the
bonding member is set to, for example, 0.1 mm to 0.6 mm.
[0069]
As the electronic circuit 60, for example, a circuit that processes image information to be
displayed on a display or audio information transmitted by a mobile terminal, a communication
circuit, and the like can be exemplified. At least one of these circuits may be included, or all of the
circuits may be included. Alternatively, a circuit having another function may be used.
Furthermore, a plurality of electronic circuits may be included. The electronic circuit 60 and the
sound generator 1 are connected by connection wiring.
[0070]
The controller 50 a is a control unit of the electronic device 50. The transmitting and receiving
unit 50b transmits and receives data via the antenna 50f based on the control of the controller
50a. The key input unit 50c is an input device of the electronic device 50, and receives a key
input operation by the operator. The microphone input unit 50d is also an input device of the
electronic device 50, and receives a voice input operation and the like by the operator. The
display unit 50 e is a display output device of the electronic device 50, and outputs display
information based on the control of the controller 50 a. For example, known displays such as
liquid crystal displays and organic EL displays can be suitably used. The display may have an
input device such as a touch panel. Here, a part of the housing 40 may be a display, or a part of
the housing 40 may be a cover of the display and the display may be disposed inside the cover.
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[0071]
The sound generator 1 then operates as a sound output device in the electronic device 50. The
sound generator 1 is connected to the controller 50a of the electronic circuit 60, and emits a
sound in response to the application of a voltage controlled by the controller 50a.
[0072]
In FIG. 7, a portable terminal having a communication unit (communication unit) that transmits
and receives data via an antenna or the like as the electronic device 50 has been described, but
the type of the electronic device 50 is not questioned. The present invention may be applied to
various consumer devices having a function of emitting sound. For example, flat-screen TVs and
car audio devices may be used for various products such as vacuum cleaners, washing machines,
refrigerators, microwave ovens and the like, as a matter of course, products having a function of
emitting sound, for example.
[0073]
According to the electronic device 50 of this example, since the electronic device 50 is
configured using the sound generator 1 with improved sound quality, it is possible to obtain an
electronic device with high sound quality.
[0074]
DESCRIPTION OF SYMBOLS 1 sound generator 11 piezoelectric element 11a, 11b, 11c, 11d
piezoelectric material layer 11e internal electrode layer 11f, 11g surface electrode layer 11h, 11i
external electrode 12 diaphragm 13 frame 131 one main surface side frame member 132 other
main surface side Frame member 14 Covering layer 141 Resin 142 Filler 15 Wiring member 20
Sound generator 30, 40 Case 50 Electronic device 50a Controller 50b Transmitter and receiver
50c Key input unit 50d Microphone input unit 50e Display unit 50f Antenna 60 Electronic
circuit
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