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JP2014127974

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DESCRIPTION JP2014127974
Abstract: To provide an acoustic generator, an acoustic generator, and an electronic device that
have high durability and little variation in sound quality. A first frame (10), a vibrating body (20)
stretched on the first frame (10), and an exciter (30) provided on the vibrating body (20). The
second frame 50 is further provided on the outer peripheral portion of the second frame 50 to
suppress the deformation of the first frame 10 which receives large stress due to the vibration of
the vibrating body 20, thereby suppressing the exciter 30, the vibrating body 20 and the first
frame. It is possible to reduce the deformation and deterioration of the entire composite vibrator
consisting of ten. Therefore, even if it is used for a long time, the sound generator 1 with little
fluctuation of the sound quality provided with the vibrating body 20 with little deformation such
as deflection can be obtained. [Selected figure] Figure 1
Acoustic generator, acoustic generator and electronic device
[0001]
The present invention relates to a sound generator, a sound generator and an electronic device.
[0002]
Conventionally, an acoustic generator represented by a piezoelectric speaker is known as a smallsized, low-current-driven acoustic device using a piezoelectric body as an electroacoustic
transducer, and, for example, a small electronic device such as a mobile computing device It is
used as a built-in sound generator.
[0003]
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1
In general, an acoustic generator using a piezoelectric body as an electroacoustic transducer has
a structure in which a piezoelectric vibrating element as an exciter having an electrode made of a
silver thin film or the like formed on a metal diaphragm.
The sound generation mechanism of an acoustic generator using a piezoelectric body as an
electroacoustic transducer generates a shape distortion in the piezoelectric vibration element by
applying an alternating voltage to both surfaces of the piezoelectric vibration element, and makes
the shape distortion of the piezoelectric vibration element metal The sound is generated by
transmitting the vibration to the diaphragm of (1) (for example, see Patent Document 1).
[0004]
Moreover, the sound generator which applied the resin film as a diaphragm instead of the metal
diaphragm is known.
In this acoustic generator, a bimorph-type laminated piezoelectric vibrating element is
sandwiched by a pair of resin films in the thickness direction, and the resin films are fixed to a
frame member in a tensioned state. Thereby, the sound conversion efficiency is improved, and
generation of high sound pressure is enabled (see, for example, Patent Document 2).
[0005]
[Patent Document 1] Japanese Patent Application Publication No. 2001-285994 Japanese Patent
Application Publication No. 2004-023436
[0006]
However, since the above-described conventional sound generator actively utilizes the resonance
of the diaphragm to generate a high sound pressure, a peak (a portion where the sound pressure
is higher than that of the surroundings) and a dip There is a problem that the sound pressure is
apt to be generated at a portion where the sound pressure is lower than the surroundings, the
load on the frame member fixed in a tensioned state is high, and the sound quality fluctuates due
to the deformation or deterioration of the frame member.
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For this reason, the improvement of the endurance of a frame member is called for.
[0007]
The present invention is made in view of the above, and an object of the present invention is to
provide an acoustic generator, an acoustic generator, and an electronic device having high
durability and little fluctuation in sound quality.
[0008]
A sound generator according to the present invention comprises a first frame, a vibrator
stretched on the first frame, and an exciter provided on the vibrator, the first frame A second
frame is further provided on the outer periphery of the body.
[0009]
The sound generator of the present invention is characterized by including the above-described
sound generator and a housing for housing the sound generator.
[0010]
An electronic apparatus according to the present invention includes the above-described sound
generator, an electronic circuit connected to the sound generator, and a case for housing the
electronic circuit and the sound generator, and the sound generator is provided with the sound. It
is characterized by having a function to generate.
[0011]
According to the present invention, it is possible to provide an acoustic generator, an acoustic
generator and an electronic device that are highly durable and have less variation in sound
quality.
[0012]
They are an explanatory view by (a) plane view of a sound generator concerning a 1st
embodiment, and an A-A 'line sectional view of (b) and (a).
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It is sectional drawing which shows another example of 1st Embodiment.
(A) A block diagram of a sound generation device, and (b) It is a block diagram of an electronic
device.
They are an explanatory view by (a) plane view of a sound generator concerning a 2nd
embodiment, and a B-B 'line sectional view of (b) and (a).
It is a (a) typical perspective view for demonstrating each part of a frame, and the C-C 'line
sectional view of (b) (a).
It is sectional drawing of the sound generator which concerns on 3rd Embodiment. It is sectional
drawing which shows another example of 3rd Embodiment. It is explanatory drawing by (a)
planar view of the sound generator which concerns on 4th Embodiment, and the D-D 'sectional
view taken on the line of (b) and (a). It is sectional drawing of the sound generator which
concerns on 5th Embodiment.
[0013]
Hereinafter, with reference to the accompanying drawings, embodiments of the sound generator,
the sound generator and the electronic device disclosed in the present application will be
described. Note that the present invention is not limited by the embodiments described below.
[0014]
First Embodiment A configuration of a sound generator according to a first embodiment will be
described with reference to FIGS. 1 (a) and 1 (b).
[0015]
1 (a) is an explanatory view in plan view of the sound generator 1 according to the first
embodiment as viewed from a direction perpendicular to the main surface of the vibrating body
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20, and FIG. 1 (b) is a view It is an AA 'line sectional view of 1 (a).
In order to make the description easy to understand, FIGS. 1A and 1B illustrate a threedimensional orthogonal coordinate system including the Z axis perpendicular to the main surface
of the vibrating body 20. Such an orthogonal coordinate system may also be shown in other
drawings used in the following description. Moreover, in FIG.1 (b), in order to make an
understanding easy, the sound generator 1 is greatly exaggerated and shown to Z-axis direction.
[0016]
As shown in FIG. 1A, the sound generator 1 includes a first frame 10, a vibrating body 20, a
piezoelectric vibrating element 30, a second frame 50, and lead wires (not shown). And
[0017]
The vibrating body 20 can be formed using various materials such as resin, metal, and paper.
For example, the thin plate-like vibrating body 20 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 20 with a resin film, the vibrating body 20 is bent and
vibrated with a large amplitude to obtain sound pressure The width and height of the resonance
peak in the frequency characteristic can be increased to reduce the difference between the
resonance peak and the dip. In addition, there is also an advantage that it is easy to adjust the
tension applied when the vibrating body 20 is fixed to the first frame 10. A composite of metal
and resin may be used as the vibrator 20.
[0018]
The piezoelectric vibrating element 30 includes the laminate 33, the surface electrode layers 34
and 35 formed on the upper and lower surfaces of the laminate 33, and the outside formed on
the side surface where the end face of the internal electrode layer 32 of the laminate 33 is
exposed. Electrodes 36 and 37 are provided. Then, lead wires (not shown) are connected to the
external electrodes 36 and 37. The main surface of the piezoelectric vibration element 30 is
bonded to the main surface of the vibrating body 20 by an adhesive such as an epoxy resin.
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[0019]
The laminate 33 is formed by alternately laminating four piezoelectric layers 31a, 31b, 31c, and
31d made of ceramics and three internal electrode layers 32. In the piezoelectric vibrating
element 30, the main surfaces on the upper surface side and the lower surface side are
rectangular, and the piezoelectric layers 31a and 31b and the piezoelectric layers 31c and 31d
are polarized in different directions in the thickness direction, The piezoelectric layers 31b and
31c are polarized in the same direction.
[0020]
Therefore, when a voltage is applied to the piezoelectric vibrating element 30 through the lead
wire, for example, the lower surface side of the piezoelectric vibrating element 30, ie, the
piezoelectric layers 31c and 31d on the vibrating body 20 side shrinks, while the piezoelectric on
the top side The body layers 31a, 31b deform so as to extend. Therefore, by applying an
alternating current signal to the piezoelectric vibrating element 30, the piezoelectric vibrating
element 30 can be bent and vibrated, and the bending vibration can be applied to the vibrating
body 20. As described above, the piezoelectric layers 31a and 31b on the upper surface side of
the piezoelectric vibrating element 30 and the piezoelectric layers 31c and 31d on the lower
surface exhibit opposite stretching behavior, and as a result, the piezoelectric vibrating element
30 has a bimorph-type bending. By vibrating, the vibrating body 20 can be given a constant
vibration to generate a sound.
[0021]
As described above, since the piezoelectric vibration element 30 is a bimorph-type laminated
piezoelectric vibration element and the piezoelectric vibration element 30 itself bends and
vibrates alone, it is, for example, a soft vibration body 20 regardless of the material of the
vibration body 20. However, strong vibration can be generated, and a sufficient sound pressure
can be obtained by the small number of piezoelectric vibrating elements 30.
[0022]
Here, as materials for forming the piezoelectric layers 31a, 31b, 31c, and 31d, conventionally,
lead-free piezoelectric materials such as lead zirconate titanate (PZT), Bi layer compounds, and
tungsten bronze structure compounds are used. The piezoelectric ceramic used can be used.
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[0023]
Further, the material of the internal electrode layer 32 contains metal, for example, silver and
palladium as main components.
The internal electrode layer 32 may contain ceramic components constituting the piezoelectric
layers 31a, 31b, 31c, 31d, whereby the piezoelectric layers 31a, 31b, 31c, 31d and the internal
electrode layers 32, 32 can be obtained. , 32 can reduce the stress due to the thermal expansion
difference.
[0024]
In addition, the surface electrode layers 34 and 35 and the external electrodes 36 and 37 contain
a metal, such as silver, as a main component.
Moreover, you may contain a glass component. By containing the glass component, strong
adhesion can be obtained between the piezoelectric layers 31a, 31b, 31c, 31d or the internal
electrode layer 32 and the surface electrode layers 34, 35 or the external electrodes 36, 37. . The
content of the glass component may be, for example, 20% by volume or less.
[0025]
The lead wire is an example of a wiring member, and one end of the lead wire is connected to the
piezoelectric vibrating element 30, and an electrical signal is input to the piezoelectric vibrating
element 30. Such a lead can be formed using various metal materials. For example, when the lead
wire is configured using a flexible wiring in which a metal foil such as copper or aluminum is
sandwiched by resin films, the height of the acoustic generator 1 can be reduced.
[0026]
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The first frame 10 has a role of holding the vibrating body 20 to form a fixed end of vibration.
For example, as shown in FIG. 1 (b), the upper frame member 11 and the lower frame member
12 both having a rectangular shape are joined to the upper and lower sides to constitute a first
frame 10. And the outer peripheral part of the vibrating body 20 which consists of resin films is
pinched ¦ interposed between the upper frame member 11 and the lower frame member 12, and
it is fixing in the state to which predetermined ¦ prescribed tension ¦ tensile̲strength was
provided. Therefore, when the vibrating body 20 vibrates to generate a high sound pressure, a
large stress is applied to the first frame 10 for fixing it, and the first frame 10 is deformed or the
vibrating body 20 There is a concern that the quality of the sound may change due to
deterioration of the joint and change in tension applied to the vibrating body 20.
[0027]
The second frame 50 is provided on an outer peripheral portion of the first frame 10 including
the upper frame member 11 and the lower frame member 12, and supports the first frame 10.
By supporting the first frame 10 with the second frame 50, deformation of the first frame 10
which receives large stress due to the vibration of the vibrating body 20 is suppressed, and the
piezoelectric vibrating element 30, the vibrating body 20 and the It is possible to reduce the
deformation and deterioration of the entire composite vibrator consisting of one frame 10.
Therefore, it becomes the sound generator 1 provided with the vibrating body 20 with few
deformations, such as bending, even if used for a long time.
[0028]
The thickness and material of the first frame 10 and the second frame 50 are not particularly
limited, but in the first embodiment, for example, because they are excellent in mechanical
strength and corrosion resistance, for example, A stainless steel material with a thickness of 100
to 1000 μm is used.
[0029]
1A shows the first frame 10 and the second frame 50 in which the shape of the inner region is
substantially rectangular, but the parallelogram, the trapezoid, and the regular n-gon are
illustrated. It may be a polygon such as
In this embodiment, as shown to Fig.1 (a), suppose that it is a substantially rectangular shape.
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[0030]
In the above description, the first frame 10 is formed of two frame members, and the two frame
members sandwich and support the peripheral portion of the diaphragm 20 as an example. It is
not limited to For example, as shown in FIG. 2, the first frame 10 may be formed of a single
frame member, and the peripheral portion of the diaphragm 20 may be adhered and fixed to the
first frame 10 and supported. . In FIG. 2, details of the laminated structure and the like of the
piezoelectric vibrating element 30 are omitted, and are simplified and shown as a simple
rectangular shape. Hereinafter, the description of the piezoelectric vibration element 30 in the
cross-sectional view is similarly simplified and shown.
[0031]
Further, as shown in FIG. 1 (b), the sound generator 1 according to the first embodiment is a
resin-made coating filled in the first frame 10 so as to embed the piezoelectric vibration element
30. The layer 40 is provided. As described above, by embedding the piezoelectric vibration
element 30 with the covering layer 40 made of resin, it is possible to induce an appropriate
damping effect, to suppress the resonance phenomenon and to further reduce the difference
between the resonance peak and the dip. be able to. Furthermore, the piezoelectric vibration
element 30 can also be protected from the external environment.
[0032]
In the first embodiment, the entire surface of the vibrating body 20 is covered by the covering
layer 40, but it is not necessary to cover the entire surface. That is, in the sound generator 1, the
piezoelectric vibrating element 30 and at least a part of the surface of the vibrating body 20 on
the side where the piezoelectric vibrating element 30 is disposed may be covered by the covering
layer 40.
[0033]
Further, FIG. 1B shows a state in which the resin layer 40 and the first frame 10 and the second
frame 50 are formed to have the same height in the Z-axis direction. The resin layer 40 only
needs to have the piezoelectric vibrating element 30 embedded therein. For example, the resin
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layer 40 may be formed to be higher than the height of the first frame 10.
[0034]
In FIG. 1B, a bimorph-type laminated piezoelectric vibration element is described as an example
of the piezoelectric vibration element 30. However, the present invention is not limited to this. It
may be a unimorph type pasted to.
[0035]
Next, a sound generating device equipped with the sound generator 1 according to the first
embodiment will be described with reference to FIG. 3 (a).
FIG. 3A is a block diagram of the sound generator.
[0036]
As shown to Fig.3 (a), the sound generator 4 can be comprised by accommodating the sound
generator 1 of the structure mentioned above in the resonance box 400. As shown in FIG.
The resonance box 400 is a housing that houses the sound generator 1, 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 4 can be used alone as a speaker, or can be suitably
incorporated into, for example, various electronic devices 2.
[0037]
As described above, 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, as well as having high durability and little variation in sound quality. The
sound generator 1 according to the embodiment can be suitably incorporated into an electronic
device 2 such as a mobile phone, a flat-screen television, or a tablet terminal.
[0038]
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The electronic device 2 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.
[0039]
Here, the electronic device 2 provided with the above-described sound generator 1 will be briefly
described with reference to FIG. 3 (b).
FIG. 3B is a block diagram of the electronic device 2.
The electronic device 2 includes the sound generator 1 described above, an electronic circuit
connected to the sound generator 1, and a housing 200 for housing the sound generator 1 and
the electronic circuit.
[0040]
Specifically, as shown in FIG. 3B, the electronic device 2 includes an electronic circuit including
the sound generator 1, the control circuit 21, the signal processing circuit 22, and the wireless
circuit 23 as an input device, and the antenna 24. And a housing 200 for housing them. Although
the wireless input device is illustrated in FIG. 3 (b), it can naturally be provided as a signal input
by normal electrical wiring.
[0041]
In addition, description is abbreviate ¦ omitted about the other electronic member (For example,
devices and circuits, such as a display, a microphone, a speaker, etc.) with which the electronic
device 2 is equipped, here. Moreover, although one sound generator 1 was illustrated in FIG.3
(b), two or more sound generators 1 and another oscillator can also be provided.
[0042]
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The control circuit 21 controls the entire electronic device 2 including the wireless circuit 23
through the signal processing circuit 22. An output signal to the sound generator 1 is input from
the signal processing circuit 22. Then, the control circuit 21 controls the signal processing circuit
22 to generate an audio signal S by controlling the signal processing circuit 22, and outputs the
audio signal S to the sound generator 1.
[0043]
Thus, the electronic device 2 shown in FIG. 3 (b) suppresses the frequency fluctuation as much as
possible by reducing the difference between the resonance peak and the dip while incorporating
the small and thin acoustic generator 1. Thus, it is possible to improve the sound quality as a
whole even in the low sound region including the low frequency sound region and to reduce the
fluctuation of the sound quality.
[0044]
Although FIG. 3B exemplifies the electronic apparatus 2 on which the sound generator 1 is
directly mounted as the sound output device, an example of the sound output device is, for
example, a sound generating device in which the sound generator 1 is housed in a housing 4 may
be mounted.
[0045]
Second Embodiment The configuration of a sound generator according to a second embodiment
will be described with reference to FIGS. 4 (a) and 4 (b).
[0046]
Here, from the viewpoint of making the following description easy to understand, the names of
the respective portions of the first frame 10 and the second frame 50 in the present embodiment
will be described with reference to FIGS. 5 (a) and 5 (b). To say.
Fig.5 (a) is a typical perspective view for demonstrating each part of the 1st frame 10, FIG.5 (b) is
a CC 'sectional view taken on the line of Fig.5 (a). is there.
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In FIG. 5 (a), only one of two frame members constituting the frame 10 is shown.
[0047]
As shown to Fig.5 (a), in this embodiment, the end surface in alignment with XY plane is
expressed as an "edge surface" among the end surfaces which the 1st frame 10 has.
Similarly, among the end surfaces of the first frame 10, the end surface along the Z-axis is
referred to as the "side surface", and the "side surface" located inside the first frame is generally
referred to as the "inner circumferential surface". The side surface located outside the frame
body 10 is generally expressed as the peripheral surface . Then, as shown in FIG. 5B, the
distance between the inner peripheral surface and the outer peripheral surface in the cross
section parallel to the XY plane is referred to as width of edge surface w, thickness of the
first frame 10 in the Z axis direction Express t as t. In the present invention, the edge surface
and the side surface may be parallel to the XY plane and the Z axis, respectively, or may
form an angle smaller than 45 °. Also, the "edge surface" and the "side surface" may be flat or
curved.
[0048]
Further, as shown in FIG. 5B, in the present embodiment, a portion close to the edge surface
in the side surface is expressed as an end of the first frame in the Z-axis direction.
[0049]
Further, as shown in FIG. 5A, in the present embodiment, the area inside the first frame 10 is
within the frame of the first frame, and the area outside the first frame is out of the
frame . Express each one.
In addition, these names use the same expression also in the case of the second frame 50.
[0050]
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In the second embodiment, the width w2 of the edge surface of the second frame 50 in the
direction parallel to the main surface of the vibrator 20, that is, the XY direction is the edge
surface of the first frame 10 adjacent thereto. Be larger than the width w1 of By making w2
larger than w1, the deformation of the first frame 10 is further suppressed, and the deformation
and deterioration of the entire composite vibrator including the piezoelectric vibration element
30, the vibrator 20 and the first frame 10 are achieved. It can be further reduced.
[0051]
Third Embodiment FIG. 6 is a cross-sectional view showing a configuration of a sound generator
according to a third embodiment in a YZ cross section. In the third embodiment, the edge surface
of the first frame 10 is closer to the vibrating member 20 than the edge surface of the second
frame 50 on the side on which the piezoelectric vibrating element 30 is provided, that is, the
positive of the Z axis. It projects in the direction of.
[0052]
As described above, the first frame 10 is a support that supports the vibrating body 20 while
applying tension uniformly, but it can also be regarded as a component of the composite
vibrating body, and the vibrating body 20 When vibrating, the first frame body 10 itself is also
vibrated by being induced to the resonance of the vibrating body 20, and a reflected wave is
returned to the vibrating body 20.
[0053]
Since the edge surface of the first frame 10 protrudes from the edge surface of the second frame
50, the first frame 10 holds the vibrating body 20 to form a fixed end of vibration and It has an
area supported by the second frame 50 and an area not supporting the vibrating body 20 and
not supported by the second frame 50.
That is, since the symmetry of the first frame 10 in the Z-axis direction is reduced, the resonant
frequency of the first frame 10 is dispersed, and the reflected wave returned from the first frame
10 to the vibrating body 20 is disturbed. Be done. As a result, the difference between the
resonance peak and the dip in the frequency characteristic of the sound pressure of the entire
complex vibration body consisting of the piezoelectric vibration element 30, the vibration body
20 and the first frame 10 is reduced, and the frequency fluctuation of the sound pressure is as
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great as possible The sound quality can be improved by suppressing the
[0054]
In FIG. 6, the edge surface of the first frame 10 protrudes in the positive direction of the Z axis
more than the edge surface of the second frame 50, and the second frame 50 in the negative
direction of the Z axis. Of the second frame 50 is made smaller than the thickness t1 of the first
frame 10, although an example is shown in which the edge face of the second frame 50
protrudes more than the edge face of the first frame 10. , And the edge surface of the second
frame 50 and the edge surface of the first frame 10 may be at the same height in the negative
direction of the Z axis, as shown in FIG. The edge surface of the first frame 10 may be arranged
to project in the positive and negative directions of the Z axis more than the edge surface of the
second frame 50.
[0055]
Fourth Embodiment A configuration of a sound generator according to a fourth embodiment will
be described with reference to FIGS. 8 (a) and 8 (b).
In the fourth embodiment, the intervening layer 60 is provided between the outer peripheral
surface of the first frame 10 and the inner peripheral surface of the second frame 50 facing each
other. The intervening layer 60 is, for example, an adhesive and a member having a lower
Young's modulus than the first frame 10 and the second frame 50. Thus, in the fourth
embodiment, the first frame 10 and the second frame 50 have the intervening layer 60 having a
Young's modulus lower than that of the first frame 10 and the second frame 50. It is fixed
through.
[0056]
The first frame 10 vibrates the first frame 10 itself as one of the components of the composite
vibrating body and returns a reflected wave to the vibrating body 20, but the outer periphery of
the first frame 10 The second frame 50 provided on the support and supporting the first frame
10 is also induced by the vibration of the first frame 10, and the second frame 50 itself also
vibrates and the first frame The reflected wave is returned to the frame 10, and can be regarded
as one of the components of the composite vibrator.
[0057]
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Since a material having a low Young's modulus usually has a small mechanical Q value, ie, a large
mechanical loss, the vibration of the first frame 10 is absorbed by the intervening layer 60 by
providing such an intervening layer 60, The vibration transmitted to the second frame 50 can be
attenuated.
Also, the reflected wave returned by the second frame 50 to the first frame 10 can be similarly
attenuated, thereby minimizing the influence of the second frame 50 on the sound quality of the
composite vibrator. Can.
[0058]
Therefore, in the fourth embodiment, the deformation and deterioration of the first frame 10 and
the entire composite vibrator can be reduced to provide a highly durable acoustic generator 1,
and the acoustic generator 1 It is possible to minimize the influence of the second frame 50 on
the sound quality of the.
[0059]
The intervening layer 60 may have a void.
In the case of having a void, the energy of vibration is further absorbed by the void and it
becomes difficult to transmit each other's vibration between the first frame 10 and the second
frame 50. The influence of the second frame 50 can be further reduced.
[0060]
Fifth Embodiment FIG. 9 is a cross-sectional view showing a configuration of a sound generator
according to a fifth embodiment in a YZ cross section. In the fifth embodiment, the intervening
layer 60 is provided between the outer peripheral surface of the first frame 10 and the inner
peripheral surface of the second frame 50 facing each other, and the first frame 10 Between the
end of the outer peripheral surface in the Z-axis direction and the end of the inner peripheral
surface of the second frame 50 in the Z-axis direction, there is a gap 70 in which the intervening
layer 60 does not exist. Thus, by providing the gap 70 at least in part between the outer
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peripheral surface of the first frame 10 and the inner peripheral surface of the second frame 50,
the first frame 10 and the second frame The energy of vibration due to the body 50 is absorbed
and damped by the gap 70, and it becomes difficult for the vibration of each other to be
transmitted between the first frame 10 and the second frame 50.
[0061]
In the fifth embodiment, the intermediate layer 60 is provided between the outer peripheral
surface of the first frame 10 and the inner peripheral surface of the second frame 50. However,
the fifth embodiment has the intermediate layer 60. Similarly, in the case where the first frame
10 and the second frame 50 are formed by providing the gap 70 between the outer peripheral
surface of the first frame 10 and the inner peripheral surface of the second frame 50, as well.
Damping effect of vibration between In this case, since the damping effect of the vibration by the
intervening layer 60 does not exist, the damping effect of the vibration by the gap 70 becomes
more remarkable.
[0062]
Further, in the fifth embodiment, the portion where the gap 70 is provided is an end portion of
the outer peripheral surface of the first frame 10 in the Z-axis direction and an end portion of the
inner peripheral surface of the second frame 50 in the Z-axis direction. However, the present
invention is not limited to this, and when the gap 70 is provided on either the positive side or the
negative side of the end in the Z-axis direction, Even in the case of having at least a part between
the outer peripheral surface of the frame 10 and the inner peripheral surface of the second
frame 50, the above-mentioned effect can be obtained.
[0063]
Between the outer peripheral surface of the first frame 10 and the inner peripheral surface of the
second frame 50, a gap 70 is provided on either the positive side or the negative side of the end
portion in the Z-axis direction. In this case, the symmetry of the first frame 10 in the Z-axis
direction is reduced, the resonance frequency of the first frame 10 is dispersed, and the reflected
wave returning from the first frame 10 to the vibrating body 20 is An effect is also obtained that
the difference between the resonance peak and the dip in the frequency characteristic of the
sound pressure of the entire composite vibrator is reduced.
[0064]
In addition, although the case where a vibrating body is comprised by thin films, such as a resin
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film, was mentioned as the example in embodiment mentioned above, it is not restricted to this,
For example, it is good also as comprising a plate-shaped member.
[0065]
Moreover, although the thing which arrange ¦ positioned one piezoelectric vibration element on
the vibrating body was illustrated in the sound generator mentioned above, you may arrange two
or more piezoelectric vibration elements on a vibrating body.
[0066]
Furthermore, in each embodiment mentioned above, although the case where a piezoelectric
vibration element was used was mentioned as an example and explained as an example of an
exciter, an exciter is not limited to a piezoelectric vibration element, An electric signal is input
and What is necessary is just to have a function to vibrate.
For example, an electrodynamic exciter, an electrostatic exciter, or an electromagnetic exciter
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.
[0067]
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.
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[0068]
DESCRIPTION OF SYMBOLS 1 sound generator 2 electronic device 4 sound generator 10 1st
frame 20 vibrator 30 piezoelectric vibration element 40 coating layer 50 2nd frame 60
intervening layer 70 gap
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