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DESCRIPTION JPWO2016067667

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DESCRIPTION JPWO2016067667
Abstract: To provide an acoustic generator, an acoustic generator and an electronic apparatus
having a long-term reliability in which a sufficient sound pressure is obtained by application of a
high voltage and mechanical degradation is suppressed even by long-term driving. SOLUTION: A
sound generator of the present invention includes a piezoelectric element 11, a diaphragm 12
vibrated by the vibration of the piezoelectric element 11, and a frame 13 supporting an outer
peripheral portion of the main surface of the diaphragm 12 The ridge portion 130 located on the
inner peripheral side of the body 13 and on the side facing the diaphragm 12 is formed as an
inclined surface or a curved surface. [Selected figure] Figure 1
Acoustic generator, acoustic generator and electronic device
[0001]
The present invention relates to an acoustic generator, an acoustic generator and an electronic
device using a piezoelectric element.
[0002]
Conventionally, an acoustic generator using a piezoelectric element is known (see, for example,
Patent Document 1).
Such a sound generator vibrates the vibration plate by applying a voltage to the piezoelectric
element attached to the vibration plate to vibrate the vibration plate, and outputs the sound by
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actively utilizing the resonance of the vibration.
[0003]
JP 2001-16692 A
[0004]
Since the sound pressure and the sound quality tend to deteriorate due to the miniaturization of
the sound generator, driving with a high voltage is required.
[0005]
However, in the above-mentioned sound generator, the ridge portion located on the inner
peripheral side of the frame serving as the support portion of the diaphragm and facing the
diaphragm has a sharp shape with a substantially right angle when viewed in cross section.
[0006]
Therefore, in the bending vibration of the diaphragm, the diaphragm is fixed at the ridge portion
located on the inner peripheral side of the frame and on the side facing the diaphragm, so a large
amplitude can not be obtained even when a high voltage is applied. There was a possibility that
sound pressure could not be improved sufficiently.
In addition, when driven with a high voltage, the cross-sectional shape of the ridge located on the
inner peripheral side of the frame and facing the diaphragm has a right-angled cross section.
During period driving, a crack due to mechanical deterioration occurs, which may damage the
diaphragm.
[0007]
In view of the above circumstances, it is possible to provide an acoustic generator, an acoustic
generator, and an electronic device having long-term reliability in which sufficient sound
pressure is obtained by application of high voltage and mechanical degradation is suppressed
even by long-term driving. With the goal.
[0008]
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The sound generator of this embodiment includes a piezoelectric element, a diaphragm that
vibrates due to the vibration of the piezoelectric element, and a frame that supports the outer
peripheral portion of the main surface of the diaphragm, and the inner peripheral side of the
frame And the ridge part located in the side which faced the said diaphragm is made into an
inclined surface or a curved surface, It is characterized by the above-mentioned.
[0009]
The sound generator of the present embodiment is characterized by including the sound
generator of the above configuration and a case for housing the sound generator.
[0010]
Further, the electronic device of the present embodiment includes the sound generator of the
above configuration, an electronic circuit connected to the sound generator, and a case for
housing the electronic circuit and the sound generator, the sound generator It has a function to
generate sound from
[0011]
According to the acoustic generator of the present embodiment, a sufficient sound pressure can
be obtained by applying a high voltage to the piezoelectric element, and the acoustic generator
has long-term reliability in which mechanical deterioration of the diaphragm is suppressed even
by long-term driving. A generator can be realized.
Further, according to the sound generation device and the electronic device of the present
embodiment, it is possible to realize a sound generation device and an electronic device having
high sound pressure, high sound quality, and excellent sound performance having high
reliability.
[0012]
(A) is a schematic plan view which shows an example of the sound generator of this embodiment,
(b) is a schematic sectional drawing cut | disconnected by the AA shown to (a).
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(A) is a schematic plan view which shows the other example of the sound generator of this
embodiment, (b) is the schematic sectional drawing cut | disconnected by the AA shown to (a).
(A) is a schematic plan view showing another example of the sound generator of the present
embodiment, (b) is a schematic cross-sectional view cut along the line AA shown in (a), (c) is
shown in (a) It is the schematic sectional drawing cut | disconnected by the BB line.
(A) is a schematic plan view showing another example of the sound generator of the present
embodiment, (b) is a schematic cross-sectional view of an example cut along line A-A shown in
(a), (c) is (a) It is a schematic sectional drawing of the other example cut | disconnected by the AA
shown to these.
It is a graph which shows the frequency characteristic of the sound pressure of the sound
generator of this embodiment.
(A) is a schematic plan view which shows the other example of the sound generator of this
embodiment, (b) is the schematic sectional drawing cut | disconnected by the AA shown to (a). (A)
is a schematic plan view which shows the other example of the sound generator of this
embodiment, (b) is the schematic sectional drawing cut | disconnected by the AA shown to (a). (A)
is a schematic plan view which shows the other example of the sound generator of this
embodiment, (b) is the schematic sectional drawing cut | disconnected by the AA shown to (a). (A)
is a schematic plan view which shows the other example of the sound generator of this
embodiment, (b) is the schematic sectional drawing cut | disconnected by the AA shown to (a). It
is a block diagram showing an example of a sound generation device of this embodiment. It is a
block diagram which shows an example of the electronic device of this embodiment.
[0013]
Hereinafter, an example of the sound generator of the present embodiment will be described
with reference to the drawings.
[0014]
Fig.1 (a) is a schematic plan view which shows an example of the sound generator of this
embodiment, FIG.1 (b) is the schematic sectional drawing cut | disconnected by the AA shown to
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Fig.1 (a).
The sound generator 1 of the example shown in FIG. 1 includes a piezoelectric element 11, a
diaphragm 12 that vibrates due to the vibration of the piezoelectric element 11, and a frame 13
that supports the outer peripheral portion of the main surface of the diaphragm 12 The ridge
portion 130 located on the inner peripheral side of the body 13 and on the side facing the
diaphragm 12 is formed as an inclined surface or a curved surface.
[0015]
The structure of the piezoelectric element 11 constituting the sound generator 1 is not shown,
but, for example, it comprises a laminate formed by laminating a piezoelectric layer and an
internal electrode layer into a plate shape, and this laminate A form is adopted in which an
external electrode provided on the side from which the internal electrode layer is drawn and a
surface electrode connected to the external electrode and provided on the main surface of the
laminate are provided. The piezoelectric element 11 is attached to the main surface of the
diaphragm 12 or the like by being attached or the like, and excites the diaphragm 12 by
vibrating upon receiving an applied voltage.
[0016]
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 the piezoelectric layer is set to, for example, 0.04 to 1.0 mm. Further, in order to obtain a large
flexural vibration, it is preferable to have a piezoelectric constant d31 of 200 pm / V or more.
[0017]
Further, the internal electrode layer constituting the piezoelectric element 11 is formed by cofiring with the ceramic forming the piezoelectric layer, and is composed of the first internal
electrode layer and the second internal electrode layer. The piezoelectric layers are alternately
stacked with the piezoelectric layers, sandwiching the piezoelectric layers from above and below.
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Various metal materials can be used as a material for forming the internal electrode layer. For
example, a conductor containing silver or silver-palladium as a main component which can be
fired at a low temperature, 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 is made of a material containing a metal component of silver and palladium and a ceramic
component of the piezoelectric layer, the stress due to the thermal expansion difference between
the piezoelectric layer and the internal electrode layer is reduced. As a result, it is possible to
obtain a piezoelectric element 11 free from stacking faults.
[0018]
The piezoelectric element 11 is preferably formed of a plate-like body whose main surfaces on
the upper surface side and the lower surface side have a polygonal shape such as a rectangular
shape or a square shape, or a circular shape or an elliptical shape, for example. By using the
piezoelectric element 11 and the diaphragm 12 and the frame 13 described later, the sound
generator can be made thin.
[0019]
The piezoelectric element 11 may have, for example, a monomorph structure having a single
piezoelectric layer, but preferably has a bimorph structure having two or more piezoelectric
layers.
Thus, the diaphragm 12 can be vibrated efficiently with a small amount of energy, as well as
contributing to thinning. In addition, in a bimorph structure in which the direction of
displacement due to an electric field applied at a certain moment is reversed such that the
direction of displacement in one side and the other side in the thickness direction is reversed, the
piezoelectric element 11 itself is bent and vibrated to form a diaphragm Since the mechanical
loss in the joint surface with 12 can be reduced, it can contribute to the improvement of sound
pressure.
[0020]
The diaphragm 12 constituting the sound generator 1 can be formed using various materials
such as resin and 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.
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[0021]
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.
[0022]
The vibrating plate 12 vibrates due to the vibration of the piezoelectric element 11. For example,
a wiring member (not shown) is connected to the surface electrode of the piezoelectric element
11, and an electrical signal is input to the piezoelectric element 11 through the wiring member,
and the piezoelectric element 11 is in the in-plane direction (principal surface of diaphragm 12
When the diaphragm 12 is expanded in the parallel direction, the diaphragm 12 itself is not
displaced by the electric signal, so that the diaphragm 12 is bent so as to be convex toward the
piezoelectric element 11 side. Next, in this state, if the positive and negative electrodes of the
electric signal are reversed, the piezoelectric element 11 contracts and the diaphragm 12 itself
does not displace by the electric signal, and consequently the diaphragm 12 is concave toward
the piezoelectric element 11 To flex. That is, by applying an alternating current signal to the
piezoelectric element 11, the piezoelectric element 11 can be expanded and contracted to give
bending vibration to the diaphragm 12.
[0023]
In addition, a frame 13 is provided to support the outer peripheral portion of the main surface 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 provided on one main surface side of the diaphragm 12.
[0024]
The thickness of the frame 13 may be, for example, 100 to 5000 μm. Moreover, as a material of
the frame 13, various materials, such as glass, a metal, and resin, can be used, for example. In the
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case of glass or metal, the rigidity is high, so the deformation is small and the sound quality is
stable. Further, in the case of resin, since rigidity is smaller than glass or metal and deformation
due to vibration of the diaphragm 12 is easily caused, spurious vibration is easily induced to the
resonance of the diaphragm 12. Therefore, in the sound pressure characteristic, the resonance
peak is dispersed, the peak and dip can be reduced, and the frequency characteristic can be
flattened. Therefore, the sound quality can be improved by flattening the sound pressure.
[0025]
The frame 13 may be assembled by arranging a plurality of members in the circumferential
direction, and these may be joined to each other.
[0026]
Further, FIG. 1 shows an example in which the outer peripheral shape of the frame 13 is a
rectangular shape and the inner peripheral shape is also a rectangular shape. It contributes to
the dispersion of resonance and can contribute to the reduction of peaks and dips.
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 FIG. 1, the number of piezoelectric elements 11 is not limited. Further, although FIG. 1 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 surfaces of the diaphragm 12,
respectively.
[0028]
Although not shown, a resin layer may be provided in the frame of the frame 3 so as to cover the
piezoelectric element 11.
[0029]
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And in the sound generator 1 of this embodiment, the collar part 130 located in the inner
peripheral side of the frame 13 and the side facing the diaphragm 12 is made into an inclined
surface or a curved surface.
In addition, an inclined surface or a curved surface is a surface inclined or bent to the frame 13
side.
[0030]
With such a configuration, the holding of the diaphragm 12 in the vicinity of the flange portion
130 of the frame 13 can be reduced while maintaining the rigidity of the frame 13, so that the
voltage applied to the piezoelectric element 11 can be reduced. By making it high, the amplitude
of the diaphragm 12 can be increased, and the sound pressure can be sufficiently improved.
Further, even if the piezoelectric element 11 is driven at high voltage, repetitive stress applied to
the diaphragm 12 can be alleviated in the vicinity of the flange portion 130 of the frame 13, so
that mechanical deterioration of the diaphragm 12 is suppressed even in long-term driving.
Sound generator with long-term reliability.
[0031]
In the case where the flange 130 is an inclined surface, in a cross-sectional view in which the
frame 13 is cut in a direction perpendicular to the main surface of the diaphragm 12, the frame
13 on the side opposite to the side facing the diaphragm 12 When the width is, for example, 0.5
to 3.5 mm, a ridge line and a frame between the surface facing the diaphragm 12 of the frame 13
and the inclined surface from a virtual corner (a corner when there is no inclined surface) Each
distance from the inner surface of 13 to the ridgeline of the inclined surface is, for example, 0.03
to 0.2 mm. Further, when the collar portion 130 is a curved surface, the width of the frame 13 on
the side opposite to the side facing the diaphragm 12 in a cross-sectional view in which the
frame 13 is cut in a direction perpendicular to the main surface of the diaphragm 12 Is 0.5 to 3.5
mm, for example, from the virtual corner (corner when there is no curved surface), the ridge line
of the surface of the frame 13 facing the diaphragm 12 with the curved surface and the inner
surface of the frame 13 The distance between each of the edges and the curved line is, for
example, 0.03 to 0.2 mm, and the radius of curvature of the curved surface (curve) is, for
example, 0.03 to 0.2 mm.
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[0032]
Here, as shown in FIG. 2, the frame 13 is made up of the first frame member 131 and the second
frame member 132, and the diaphragm 12 is made of the first frame member 131 and the
second frame member 132. The flanges 1310 and 1320, which are sandwiched and supported
and positioned on the inner peripheral side of the first frame member 131 and the second frame
member 132 and facing the diaphragm 12, are inclined surfaces or curved surfaces. It is also
good. Thereby, the outer peripheral portion of the main surface of the diaphragm 12 is firmly
fixed, and the leakage of the vibration energy of the diaphragm 12 is suppressed, and the abovementioned effect is obtained, so that the sound pressure can be further improved. . Further, even
if the piezoelectric element 11 is driven at high voltage for a long period of time, the problem
that the diaphragm 12 is peeled off from the frame 13 can be suppressed, so the fulcrum of the
diaphragm 12 does not fluctuate and the sound pressure and sound quality are longer. It can be
stable for a period.
[0033]
Further, as shown in FIG. 3, when the ridge 1310 of the first frame member 131 and the ridge
1320 of the second frame member 132 are viewed over the entire circumference, the shape of
the inclined surface or the curved surface is uneven. It may be What has shown in FIG. 3 is a
shape in which the curvature radius of each curved surface differs in a different cross section
(the cross section cut | disconnected by the AA line and the cross section cut by the BB line). In
addition, the area | region shown with the broken line in FIG.3 (b) and FIG.3 (c) expands a
principal part. As described above, when different cross sections are used, it is assumed that the
shapes of the ridges 1310 and 1320 (the shape of the inclined surface or the shape of the curved
surface) are different from each other as the shapes referred to here are nonuniform. Thereby,
the distance between the supporting points of the diaphragm 12 and the displacement of the
outer peripheral portion of the diaphragm 12 can be partially changed. Therefore, in addition to
the main vibration, a plurality of spurious vibrations can be induced, and dispersion of the
resonance frequency and damping of the vibrations become possible, so that differences in peak
and dip can be reduced in the frequency-sound pressure characteristics, and sound quality can
be improved.
[0034]
Further, as shown in FIG. 4, when cut in a direction perpendicular to the main surface of the
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diaphragm 12, the inclined surface or the inclined surface of the flange 1310 of the first frame
member 131 and the flange 1320 of the second frame member 132 It may have a cross section
in which the shape of the curved surface is different.
[0035]
In FIG. 4B, the collar 1310 of the first frame member 131 is a curved surface, and the collar
1320 of the second frame member 132 is an inclined surface.
Further, in FIG. 4C, both the ridge 1310 of the first frame member 131 and the ridge 1320 of the
second frame member 132 are curved, and in the direction perpendicular to the main surface of
the diaphragm 12. The radius of curvature of each of the curved surfaces when cut is different.
For example, each of the first frame member 131 and the second frame member 132 on the side
opposite to the side facing the diaphragm 12 when the frame 13 is cut in the direction
perpendicular to the main surface of the diaphragm 12 When the width is 0.5 to 3.5 mm, the
difference in the radius of curvature of the curved surfaces (curves) of the ridges 1310 and 1320
is, for example, 0.01 to 0.15 mm. In addition, the area | region shown with the broken line in
FIG.4 (b) and FIG.4 (c) expands a principal part.
[0036]
With such a configuration, the distance between supporting points of the diaphragm 12 and the
displacement of the outer peripheral portion of the diaphragm 12 can be partially changed also
in the displacement on the one main surface side and the other main surface side. Therefore, in
addition to the main vibration, a plurality of spurious vibrations can be induced, and dispersion
of the resonance frequency and damping of the vibration become possible, thereby reducing the
difference between the peak and dip in the frequency-sound pressure characteristics and
improving sound quality. .
[0037]
FIG. 5 is a graph showing the frequency characteristic obtained by the configuration shown in
FIG. 4C, the solid line shows the frequency characteristic of the sound pressure of the sound
generator of this embodiment, and the dotted line shows the comparative example Sound
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pressure frequency of the sound generator when the ridges 1310 and 1320 located on the inner
peripheral side of the first frame member 131 and the second frame member 132 facing the
diaphragm 12 are substantially perpendicular in cross section It shows the characteristics.
According to the graph shown in FIG. 5, it can be seen that the dip in the high frequency region is
reduced by the configuration of FIG. 4 (c).
[0038]
Furthermore, as shown in FIG. 6, when cut in a direction perpendicular to the main surface of the
diaphragm 12, the width and the second frame of the first frame member 131 on the side
opposite to the side facing the diaphragm 12. It may have a cross section which is different from
the width of the member 132.
[0039]
Further, as shown in FIG. 7, the frame 13 supports the diaphragm 12 via the adhesive 14, and
the adhesive 14 is interposed between the flange 130 of the frame 13 and the diaphragm 12.
May be
Furthermore, as shown in FIG. 8, the adhesive 14 may be extended to the diaphragm 12 beyond
the ridge 130 extending to the inside of the frame 13 from between the ridge 130 and the
diaphragm 12. . With these configurations, the damping effect by the adhesive 14 works when
the diaphragm 12 is bent, dispersion of resonance frequency and damping of vibration are
promoted, and the difference between peak and dip in frequency-sound pressure characteristics
is further reduced. , Can improve the sound quality.
[0040]
Further, as shown in FIG. 9, when cut in the direction perpendicular to the main surface of the
diaphragm 12, the frame 13 faces the diaphragm 12 from the side opposite to the side facing the
diaphragm 12. The width may be narrowed as it approaches. Thereby, the squeezing of the
diaphragm 12 in the vicinity of the flange portion 130 of the frame 13 can be reduced, the sound
pressure can be improved, and the vibration wave propagated from the diaphragm 12 to the
frame 13 is Since the change in width causes the resonance to be reflected in a dispersed state,
distortion due to the resonance of the frame 13 is suppressed, and the sound quality can be
improved.
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[0041]
7 to 9 show a structure in which the frame 13 is formed of the first frame member 131, but the
present invention is not limited to this structure, and the second frame member 132 is also
provided, and the diaphragm 12 is It may have a structure in which the frame member 131 and
the second frame member 132 hold the same.
[0042]
Next, a method of manufacturing the sound generator of the present embodiment will be
described.
[0043]
First, a ceramic molded body to be a piezoelectric layer is manufactured.
Specifically, a ceramic slurry is prepared by mixing a calcined powder of a piezoelectric ceramic,
a binder made of an organic polymer such as acrylic and butyral, and a plasticizer.
Then, a ceramic green sheet is produced using this ceramic slurry by using a tape forming
method such as a doctor blade method or a calender roll method. Any piezoelectric ceramic may
be used as long as it has piezoelectric characteristics, and, for example, a perovskite oxide made
of lead zirconate titanate (PbZrO 3 -PbTiO 3) can be used. Further, as a plasticizer, dibutyl
phthalate (DBP), dioctyl phthalate (DOP) or the like can be used.
[0044]
In addition, as a manufacturing method of a ceramic molded object, other suitable manufacturing
methods, such as press molding and extrusion molding, can be used.
[0045]
In the case of a laminate, a conductive paste to be an internal electrode layer is produced.
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Specifically, a conductive paste is prepared by adding and mixing a binder and a plasticizer to
silver-palladium metal powder. The conductive paste may be applied on the above-mentioned
ceramic green sheet in a desired pattern of internal electrodes by screen printing, and a plurality
of ceramic green sheets on which the conductive paste is printed may be laminated.
[0046]
Then, the ceramic molded body obtained above is debinded at a predetermined temperature,
fired at a temperature of 900 ° C. to 1200 ° C., and ground to a predetermined shape using a
surface grinder or the like. By processing, a laminate including a single-layer piezoelectric
material or alternately stacked internal electrode layers and a piezoelectric material layer is
produced.
[0047]
In addition, as long as a single-layered piezoelectric body or a laminated body formed by
laminating a plurality of internal electrode layers and piezoelectric layers can be manufactured,
any manufacturing method may be used.
[0048]
Thereafter, a silver glass-containing conductive paste prepared by adding a binder, a plasticizer
and a solvent to a mixture of conductive particles containing silver as a main component and
glass is screen-printed on the main surface of a piezoelectric body or a laminate. Print by law etc.
and dry.
[0049]
Next, similarly, a silver glass-containing conductive paste prepared by adding a binder, a
plasticizer and a solvent to a mixture of conductive particles containing silver as a main
component and glass is specified on the side surface of a piezoelectric body or a laminate. After
printing and drying by a screen printing method or the like according to the pattern of (1),
baking processing is performed at a temperature of 600 ° C. to 800 ° C. to form surface
electrodes and external electrodes.
[0050]
Thereafter, the piezoelectric body or the laminate is subjected to polarization treatment to impart
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piezoelectric activity.
For polarization processing, using a DC power supply device, for example, the first surface
electrode provided on the surface of the piezoelectric element is connected to the negative
electrode, and the second surface electrode is connected to the positive electrode, for example 2
kV / mm to 3 kV / mm The potential difference may be applied at an ambient temperature of 15
° C. to 35 ° C. for several seconds as an application time.
The voltage, the ambient temperature, and the application time are suitably selected depending
on the properties of the piezoelectric material.
[0051]
Although the desired piezoelectric element 11 can be obtained as described above, when a wiring
member is required, it may be connected to the piezoelectric element 11 by the following
method.
For example, when connecting and fixing (joining) the flexible wiring substrate to the
piezoelectric element 11 using a conductive adhesive, a conductive adhesive paste is applied and
formed on a predetermined position of the piezoelectric element using a method such as screen
printing. .
Then, the flexible wiring board is connected and fixed to the piezoelectric element by curing the
conductive adhesive paste while the flexible wiring board is in contact. The conductive adhesive
paste may be applied and formed on the flexible wiring substrate side.
[0052]
In addition, a lead wire which carried out insulation covering may be used as a wiring member,
solder may be used as a joining member, and a member which has the same function can be
chosen suitably.
[0053]
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Next, the diaphragm 12 is bonded and fixed to the other main surface of the piezoelectric
element 11 using a bonding material.
When, for example, an anaerobic resin adhesive is used as the bonding material, the anaerobic
adhesive paste is applied and formed on a predetermined position on the one main surface side
of the diaphragm using a method such as screen printing.
[0054]
Thereafter, pressure is applied in a state in which the piezoelectric element 11 is in contact to
cure the paste for anaerobic adhesive, thereby bonding and fixing the piezoelectric element 11 to
the diaphragm 12. The anaerobic adhesive paste may be applied and formed on the piezoelectric
element 11 side. As another bonding material, for example, the diaphragm 12 is bonded and
fixed to a predetermined main surface of the frame 13 processed into a desired shape using the
adhesive 14. When, for example, an anaerobic resin adhesive is used as the adhesive 14, an
anaerobic adhesive paste is applied and formed at a predetermined position on the main surface
side of the diaphragm 12 using a method such as screen printing, and then a frame is formed.
With the body 13 in contact, pressure is applied to harden the anaerobic adhesive paste, and the
frame 13 is bonded and fixed to the diaphragm 12. The anaerobic adhesive paste may be applied
and formed on the frame 13 side. As the other adhesive 14, for example, an adhesive such as a
heat-curing epoxy-based adhesive can be used.
[0055]
Next, the frame 13 is produced. The frame 13 is made of, for example, a metal such as stainless
steel by press punching or etching, and thereafter, a predetermined ridge portion of the frame 13
is processed by grinding or etching to form an inclined surface or a curved surface. . When using
resin materials such as acrylic resin, polycarbonate resin, polybutylene terephthalate resin, etc., it
is manufactured by injection molding using a mold manufactured so that a predetermined ridge
portion of the frame 13 has an inclined surface or a curved surface. Ru.
[0056]
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Next, the diaphragm 12 is bonded and fixed to the predetermined main surface of the frame 13
processed into the desired shape by the above method using the adhesive 14. When, for example,
an anaerobic resin adhesive is used as the adhesive 14, an anaerobic adhesive paste is applied
and formed at a predetermined position on the main surface side of the diaphragm 12 using a
method such as screen printing, and then a frame is formed. With the body 13 in contact,
pressure is applied to harden the anaerobic adhesive paste, and the frame 13 is bonded and fixed
to the diaphragm 12. The anaerobic adhesive paste may be applied and formed on the frame 13
side. As the other adhesive 14, for example, an adhesive such as a heat-curing epoxy-based
adhesive can be used.
[0057]
The acoustic generator of this embodiment is obtained by the above manufacturing method.
[0058]
Next, an example of the embodiment of the sound generator of the present embodiment will be
described.
[0059]
The sound generation device is a so-called speaker-like sound generation device, and as shown in
FIG. 10, the sound generation device 20 of this example includes a sound generator 1 and a
housing 30 for housing the sound generator 1.
Note that a part of the housing 30 may be the diaphragm 20 constituting the sound generator 1,
and that the housing 30 accommodates the sound generator 10 is a part of the sound generator
1 (piezoelectric element 11 ) Is meant to be included.
[0060]
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.
By including such a housing 30, sound pressure in, for example, a low frequency band can be
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increased.
[0061]
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. 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.
[0062]
The sound generation device 20 of the present embodiment described above can improve the
sound pressure by obtaining an amplitude corresponding to a voltage rise even if a high voltage
is applied, and mechanical degradation even when driven with a high voltage for a long time
Because it is configured using an acoustic generator that can be suppressed and has long-term
reliability, it has excellent sound performance with high sound pressure, high sound quality, and
high reliability.
[0063]
Next, an example of the electronic device of the present embodiment will be described.
[0064]
As shown in FIG. 11, 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. It has a function to
generate sound from the sound generator 1.
[0065]
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.
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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.
[0066]
In addition, the electronic device 50 includes the display unit 50e, the antenna 50f, and the
sound generator 1, and includes the housing 70 that accommodates these devices. Although FIG.
11 shows a state in which all the devices including the controller 50a are housed in one housing
40, the housing form of the devices 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.
[0067]
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.
[0068]
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.
[0069]
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Although the electronic device 50 has been described as a portable terminal device in FIG. 11, it
does not ask the type of the electronic device 50, and 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.
[0070]
The electronic device of the present invention described above can improve the sound pressure
by obtaining an amplitude corresponding to a voltage rise even when applying a high voltage,
and can suppress mechanical deterioration even when driven at a high voltage for a long time.
Since it is configured using a sound generator having long-term reliability, it has high sound
pressure, high sound quality, and excellent sound performance having high reliability.
[0071]
An embodiment of the sound generator will be described.
Specifically, a sound generator was produced as shown below.
[0072]
The piezoelectric element was a piezoelectric body having a length of 32 mm, a width of 14 mm,
and a thickness of 0.2 mm. The piezoelectric body was formed of lead zirconate titanate. The
surface electrode and the external electrode were made of silver glass.
[0073]
For the diaphragm, a resin film of polyethylene terephthalate having a thickness of 0.025 mm
was used.
[0074]
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20
The frame was made of stainless steel as the material, and was prepared to have an outer
dimension of 60 mm in length, 34 mm in width, 1.0 mm in thickness and 2.0 mm in frame width.
Here, as in Example 1, a 0.1 mm inclined surface (C surface with a chamfering distance of 0.1
mm) is formed on the ridge portion in contact with the diaphragm on the inner side of the frame
(Curve of the shape shown in FIG. A modified shape was produced. Moreover, what formed the
curved surface (R surface of curvature radius 0.1 mm) of 0.1 mm as Example 2 (shape shown in
FIG. 1) was produced. On the other hand, as a comparative example, assuming that the material,
external dimensions and frame width of the piezoelectric element, diaphragm, and frame are the
same as above, the ridge portion in contact with the diaphragm inside the frame is substantially
perpendicular to the other ridges The shape was made.
[0075]
When voltages of 100 Vp-p / mm and 150 Vp-p / mm were applied to the respective sound
generators described above, and the sound pressure at 1 kHz was measured at a distance of 10
cm, Example 1 was 100 Vp-p / mm. 87 dB, 91 V at 150 Vp-p / mm, Example 2 87 dB at 100 V pp / mm, 91 dB at 150 V p-p / mm, Comparative Example 85 dB at 100 V p-p / mm, 86 dB at 150
V p-p / mm It became.
[0076]
Thus, it has been confirmed that in the sound generator of this example, an improvement in the
sound pressure corresponding to the increase in the applied voltage can be seen as compared to
the sound generator of the comparative example.
[0077]
In addition, a voltage of 150 Vp-p / mm was applied for 100 hours at room temperature, and the
sound pressure at 1 kHz was measured at a distance of 10 cm before and after that, and the
amount of change in sound pressure was measured. In the second embodiment, the change
amount is 0 dB, and in the comparative example, the change amount is -2 dB.
[0078]
Thus, it has been confirmed that the sound generator of this example can suppress the change in
sound pressure as compared to the sound generator of the comparative example.
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[0079]
DESCRIPTION OF SYMBOLS 1 ... Sound generator 11 ... Piezoelectric element 12 ... Diaphragm 13
... Frame body 130 ... Collar part 131 ... 1st frame member 1310 ... Collar part 132 ... Second
frame member 1320 ... collar portion 14 ... adhesive 20 ... sound generator 30, 40 ... housing 50
... electronic device 60 ... electronic circuit
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