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JP2014060478

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DESCRIPTION JP2014060478
Abstract: To obtain good sound pressure frequency characteristics. A sound generator according
to an embodiment includes an exciter and a flat vibrator. The exciter vibrates when an electrical
signal is input. The vibrator is attached with the exciter and vibrates with the exciter due to the
vibration of the exciter. Moreover, the said exciter is formed so that thickness may become nonuniform | heterogenous. [Selected figure] Figure 3B.
Acoustic generator, acoustic generator and electronic device
[0001]
Embodiments of the disclosure relate to a sound generator, a sound generator and an electronic
device.
[0002]
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
actively utilizing the resonance of the vibration.
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1
[0003]
Moreover, since such a sound generator can use thin films, such as a resin film, for a diaphragm,
it can be comprised thinly and lightweight compared with a general electromagnetic speaker etc.
[0004]
In the case where a thin film is used as the diaphragm, the thin film is supported in a uniformly
tensioned state by being sandwiched from a thickness direction, for example, by a pair of frame
members so as to obtain excellent acoustic conversion efficiency. Is required.
Also, the piezoelectric element is formed so that its thickness is uniform.
[0005]
JP 2004-023436
[0006]
However, since the above-described conventional sound generator resonates the diaphragm
tensioned uniformly by the piezoelectric element having a uniform thickness, the peak in the
frequency characteristic of the sound pressure (a portion where the sound pressure is higher
than the surrounding area) And dips (where the sound pressure is lower than that of the
surroundings) are likely to occur, and it is difficult to obtain good sound quality.
[0007]
One aspect of the embodiments is made in view of the above, and it is an object of the present
invention to provide an acoustic generator, an acoustic generator and an electronic device
capable of obtaining good frequency characteristics of sound pressure.
[0008]
The sound generator according to one aspect of the embodiment includes an exciter and a flat
vibrator.
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The exciter vibrates when an electrical signal is input.
The vibrator is attached with the exciter, and vibrates with the exciter due to the vibration of the
exciter.
Moreover, the said exciter is formed so that thickness may become non-uniform | heterogenous.
[0009]
According to one aspect of the embodiment, good sound pressure frequency characteristics can
be obtained.
[0010]
FIG. 1A is a schematic plan view showing a schematic configuration of a basic sound generator.
FIG. 1B is a cross-sectional view taken along line A-A 'of FIG. 1A. FIG. 2 is a diagram showing an
example of the frequency characteristic of sound pressure. FIG. 3A is a schematic plan view
showing the configuration of the sound generator according to the embodiment. FIG. 3B is a
cross-sectional view taken along line B-B 'of FIG. 3A. FIG. 3C is a cross-sectional view taken along
line C-C 'of FIG. 3A. FIG. 4A is a schematic explanatory view (No. 1) in the case of forming a thick
central portion of a piezoelectric element. FIG. 4B is a schematic explanatory view (No. 2) in the
case of forming the central portion of the piezoelectric element thick. FIG. 5A is an explanatory
diagram (No. 1) in the case of forming a portion corresponding to the surface electrode layer
thick. FIG. 5B is an explanatory view (No. 2) in the case where a portion corresponding to the
surface electrode layer is formed thick. FIG. 5C is an explanatory view (No. 3) in the case of
forming a portion corresponding to the surface electrode layer thick. FIG. 6A is a diagram
showing the configuration of the sound generation device according to the embodiment. FIG. 6B
is a view showing the configuration of the electronic device according to the embodiment.
[0011]
Hereinafter, embodiments of a sound generator, a sound generator and an electronic device
disclosed in the present application will be described in detail with reference to the attached
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drawings. Note that the present invention is not limited by the embodiments described below.
[0012]
First, prior to the description of the sound generator 1 according to the embodiment, a schematic
configuration of a basic sound generator 1 'will be described using FIGS. 1A and 1B. FIG. 1A is a
schematic plan view showing a schematic configuration of the sound generator 1 ′, and FIG. 1B
is a cross-sectional view taken along the line A-A ′ of FIG. 1A.
[0013]
In order to make the description easy to understand, FIGS. 1A and 1B illustrate a threedimensional orthogonal coordinate system including a Z axis in which the vertically upward
direction is a positive direction and the vertically downward direction is a negative direction.
Such an orthogonal coordinate system may also be shown in other drawings used in the
following description. Further, in the present embodiment, the positive direction of the X axis in
the orthogonal coordinate system is defined as the front direction.
[0014]
Further, in the following, with respect to the constituent element composed of a plurality of parts,
the sign may be attached to only one of the plural parts, and the addition of the sign may be
omitted for the other parts. In such a case, it is assumed that parts denoted by reference
numerals have the same configuration as the other parts.
[0015]
Further, in FIG. 1A, illustration of the resin layer 7 (described later) is omitted. Further, in order
to make the description easy to understand, FIG. 1B shows the sound generator 1 ′ in a greatly
exaggerated manner in the thickness direction (Z-axis direction).
[0016]
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As shown in FIG. 1A, the sound generator 1 ′ includes a frame 2, a diaphragm 3 and a
piezoelectric element 5. As shown in FIG. 1A, the following description exemplifies the case
where one piezoelectric element 5 is provided, but the number of piezoelectric elements 5 is not
limited.
[0017]
The frame 2 is constituted by two frame members having a rectangular frame shape and the
same shape, and functions as a support for supporting the diaphragm 3 by sandwiching the
peripheral portion of the diaphragm 3. The diaphragm 3 has a plate-like or film-like shape, and
the peripheral edge portion thereof is sandwiched and fixed to the frame 2 and is substantially
flat in a state where tension is uniformly applied within the frame 2 Supported by
[0018]
A portion of the diaphragm 3 inside the inner periphery of the frame 2, that is, a portion of the
diaphragm 3 which is not sandwiched by the frame 2 and can freely vibrate is referred to as a
vibrator 3a. That is, the vibrating body 3 a is a portion having a substantially rectangular shape
in the frame of the frame 2.
[0019]
Moreover, the diaphragm 3 can be formed using various materials, such as resin and a metal. For
example, the diaphragm 3 can be made of a resin film of polyethylene, polyimide or the like
having a thickness of about 10 to 200 μm.
[0020]
Also, the thickness, material, and the like of the frame 2 are not particularly limited, and the
frame 2 can be formed using various materials such as metal and resin. For example, a stainless
steel or the like having a thickness of about 100 to 1000 μm can be suitably used as the frame
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2 because of its excellent mechanical strength and corrosion resistance.
[0021]
Although FIG. 1A shows the frame 2 in which the shape of the inner region is substantially
rectangular, it may be a polygon such as a parallelogram, a trapezoid, and a regular n-gon. In the
present embodiment, as shown in FIG. 1A, it is assumed to be substantially rectangular.
[0022]
In the above description, the frame 2 is constituted by two frame members, and the peripheral
portion of the diaphragm 3 is sandwiched and supported by the two frame members as an
example, but the present invention is limited thereto. It is not a thing. For example, the frame 2
may be formed of a single frame member, and the peripheral portion of the diaphragm 3 may be
adhered and fixed to the frame 2 and supported.
[0023]
The piezoelectric element 5 is provided by being attached to the surface of the vibrating body 3a
or the like, and is an exciter that excites the vibrating body 3a by vibrating upon receiving an
applied voltage.
[0024]
As shown in FIG. 1B, the piezoelectric element 5 is, for example, a laminated body in which
piezoelectric layers 5a, 5b, 5c, and 5d made of four layers of ceramics and three layers of
internal electrode layers 5e are alternately stacked; The laminate includes surface electrode
layers 5f and 5g formed on the upper and lower surfaces of the laminate, and external electrodes
5h and 5j formed on the exposed side surfaces of the internal electrode layer 5e.
Further, lead terminals 6a and 6b are connected to the external electrodes 5h and 5j.
[0025]
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The piezoelectric element 5 has a plate shape, and the 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.
In addition, the piezoelectric element 5 is often formed so that its thickness is uniform.
[0026]
The piezoelectric layers 5a, 5b, 5c and 5d are polarized as shown by arrows in FIG. 1B. That is,
the direction of polarization with respect to the direction of the electric field applied at a certain
moment is polarized such that one side and the other side in the thickness direction (Z-axis
direction in the drawing) are reversed.
[0027]
Then, when a voltage is applied to the piezoelectric element 5 through the lead terminals 6a, 6b,
for example, at a certain moment, the piezoelectric layers 5c, 5d on the side adhered to the
vibrating body 3a shrink and the upper surface of the piezoelectric element 5 The piezoelectric
layers 5a and 5b on the side deform so as to extend. Therefore, by applying an alternating
current signal to the piezoelectric element 5, the piezoelectric element 5 can be bent and
vibrated, and the bending vibration can be applied to the vibrating body 3 a.
[0028]
Further, the main surface of the piezoelectric element 5 is bonded to the main surface of the
vibrating body 3a by an adhesive such as an epoxy resin.
[0029]
As materials constituting the piezoelectric layers 5a, 5b, 5c and 5d, lead-free piezoelectric
materials such as lead zirconate titanate (PZT), Bi layer compounds, tungsten bronze structure
compounds, etc. are conventionally used. Piezoelectric ceramics can be used.
[0030]
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Moreover, various metal materials can be used as a material of the internal electrode layer 5e.
For example, in the case of containing a metal component composed of silver and palladium, and
a ceramic component forming piezoelectric layers 5a, 5b, 5c, 5d, between piezoelectric layers 5a,
5b, 5c, 5d and internal electrode layer 5e. Since the stress due to the thermal expansion
difference can be reduced, it is possible to obtain the piezoelectric element 5 having no stacking
fault.
[0031]
Also, the lead terminals 6a, 6b can be formed using various metal materials.
For example, when the lead terminals 6a and 6b are formed using a flexible wiring in which a
metal foil such as copper or aluminum is sandwiched by resin films, the height of the
piezoelectric element 5 can be reduced.
[0032]
Further, as shown in FIG. 1B, the acoustic generator 1 ′ is disposed so as to cover the surfaces
of the piezoelectric element 5 and the vibrating body 3a in the frame of the frame 2, and is
integrated with the vibrating body 3a and the piezoelectric element 5. The resin layer 7 is further
provided.
[0033]
The resin layer 7 is preferably formed, for example, using an acrylic resin so that the Young's
modulus is in the range of about 1 MPa to 1 GPa.
In addition, since the appropriate damping effect can be induced by embedding the piezoelectric
element 5 in the resin layer 7, it is possible to suppress the resonance phenomenon and to
suppress the peak and the dip in the frequency characteristic of the sound pressure.
[0034]
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Further, FIG. 1B shows a state in which the resin layer 7 is formed to have the same height as the
frame 2, but it is sufficient if the piezoelectric element 5 is embedded, for example, the resin
layer 7 is a frame It may be formed to be higher than the height of the body 2.
[0035]
Further, in FIG. 1B, a bimorph-type laminated piezoelectric element is described as an example of
the piezoelectric element 5. However, the present invention is not limited to this. For example, a
unimorph type in which the expanding and contracting piezoelectric element 5 is attached to the
vibrator 3a It does not matter.
[0036]
By the way, as shown in FIG. 1A and FIG. 1B, the vibrating body 3a is supported flatly in a state in
which tension is uniformly applied within the frame of the frame 2, and the vibration of the
piezoelectric element 5 having uniform thickness is received. It vibrates together with the
piezoelectric element 5.
In such a case, since the peak dip and distortion caused by the resonance induced by the
vibration of the piezoelectric element 5 occur, the sound pressure changes rapidly at a specific
frequency, and the frequency characteristic of the sound pressure is difficult to flatten.
[0037]
This point is illustrated in FIG.
FIG. 2 is a diagram showing an example of the frequency characteristic of sound pressure. As
already described in the description of FIG. 1A, the vibrator 3a is flatly supported in the frame 2
with tension applied uniformly. Therefore, it can be said that the vibrating body 3a has a uniform
Young's modulus as a whole.
[0038]
However, in such a case, since the peaks are concentrated at a specific frequency and degenerate
due to the resonance of the vibrating body 3a, as shown in FIG. 2, sharp peaks and dips are likely
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to be scattered and generated over the entire frequency range.
[0039]
As an example, attention is focused on a portion enclosed by a dashed closed curve PD in FIG.
When such a peak occurs, the sound pressure varies depending on the frequency, so that it is
difficult to obtain good sound quality.
[0040]
In such a case, as shown in FIG. 2, the height of peak P is lowered (see arrow 201 in the figure)
and the peak width is broadened (see arrow 202 in the figure), and peak P or dip (not shown) is
It is effective to take measures to make it smaller.
[0041]
Therefore, in the present embodiment, the height of the peak P is lowered by forming the
piezoelectric element 5 so as to have a large thickness and become nonuniform.
That is, by shifting the resonance point for each thickness of the piezoelectric element 5, the
resonance frequencies propagating to the vibrating body 3a are not aligned. Then, as a result, the
degeneracy of the resonance mode is solved and dispersed, the height of the peak P is lowered,
and the peak width is broadened.
[0042]
Hereinafter, the sound generator 1 which concerns on embodiment is sequentially demonstrated
concretely using FIG. 3A-FIG. 5C. First, FIG. 3A is a schematic plan view showing the
configuration of the sound generator 1 according to the embodiment, FIG. 3B is a cross-sectional
view taken along the line BB 'of FIG. 3A, and FIG. 3C is FIG. It is CC 'line sectional drawing. In FIG.
3A, the resin layer 7 is not shown.
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[0043]
As shown to FIG. 3A-FIG. 3C, the sound generator 1 is provided with the piezoelectric element 5
formed so that the thickness might become uneven. Specifically, the point that “the thickness is
not uniform” of the piezoelectric element 5 will be described.
[0044]
As shown in FIGS. 3B and 3C, for example, the piezoelectric element 5 is formed such that the
thickness h of the central portion thereof is larger than the thickness of the other portions.
[0045]
Here, although the resonance frequency is defined by the thickness h of the central portion of the
piezoelectric element 5, the peak P can be obtained by making the thickness of the other portion
smaller than the thickness h of the central portion. The more you move away from the middle
part of the
[0046]
That is, the peak P of the sound pressure at the resonance point can be dispersed across the
composite vibrator including the piezoelectric element 5, the vibrator 3a and the resin layer 7,
and the frequency characteristic of the sound pressure can be flattened.
Therefore, good sound pressure frequency characteristics can be obtained.
[0047]
Although FIG. 3B and FIG. 3C show the piezoelectric element 5 having a shape in which each side
of the substantially rectangular parallelepiped is chamfered, this is merely an example, and the
present invention is not limited to such a shape.
[0048]
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Moreover, the formation method which makes the thickness of the piezoelectric element 5
uneven is not limited, either.
For example, in anticipation of shrinkage of the piezoelectric element 5 in the firing step, it may
be omitted to finally adjust the shape to a substantially rectangular parallelepiped, or chamfering,
polishing, etc. are performed after firing of the piezoelectric element 5 You may do it.
[0049]
Here, the point in which the central portion of the piezoelectric element 5 is formed thick will be
described in more detail.
FIGS. 4A and 4B are schematic explanatory views in the case of forming the central portion of the
piezoelectric element 5 thick. 4A shows the piezoelectric element 5 having a uniform thickness
shown in FIG. 1B, and FIG. 4B shows the thick piezoelectric element in the central portion shown
in FIG. 3B. 5 is illustrated.
[0050]
Although already described with reference to FIG. 1B, as shown in FIG. 4A, the piezoelectric
element 5 is a laminate in which the piezoelectric layers 5a, 5b, 5c, 5d and the internal electrode
layer 5e are alternately stacked. . And as shown to FIG. 4A, the part which all the internal
electrode layers 5e overlap is an active region which expands-contracts when a voltage is applied
to the piezoelectric element 5. As shown in FIG. The other part is an inactive region.
[0051]
That is, in the portion corresponding to the active region, since all the internal electrode layers
5e overlap, the stacking density is larger than that in the inactive region. Therefore, for example,
if the piezoelectric element 5 is subjected to shrinkage deformation when firing, as shown in FIG.
4B, the thickness of the portion corresponding to the active region is obviously left thicker than
the thickness of the portion corresponding to the inactive region. Can.
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[0052]
When chamfering, polishing, or the like is performed after firing of the piezoelectric element 5,
as shown in FIG. 4B, processing may be performed with a portion corresponding to the inactive
region of the piezoelectric element 5 as a guide.
[0053]
As described above, by increasing the thickness of the active region in which all the internal
electrode layers 5e overlap, the phase shift with the inactive region at the resonance point can be
increased, so the peak of the sound pressure at the resonance point By varying P, it is possible to
flatten the frequency characteristic of sound pressure.
Therefore, good sound pressure frequency characteristics can be obtained.
[0054]
By the way, although the case where the thickness of the portion corresponding to the active
region in the piezoelectric element 5 has been increased has been described as an example, the
thickness may be increased in the portion where the surface electrode layer 5f (see FIG. 1B) is
formed. Good. Next, such a case will be described with reference to FIGS. 5A to 5C.
[0055]
5A to 5C are explanatory views in the case of forming a portion corresponding to the surface
electrode layer 5f thick. 5B is a further enlarged view of a cross section taken along the line D-D
'shown in FIG. 5A. 5A to 5C, illustration of components (for example, the external electrodes 5h
and 5j, etc.) other than the components required for the description is omitted. Here, the
description is mainly made by taking the surface electrode layer 5f as an example, but the same
may be considered for the surface electrode layer 5g shown in FIG. 1B.
[0056]
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As shown in FIG. 5A, the piezoelectric element 5 may be formed to have a non-uniform thickness
by dispersing and forming a plurality of surface electrode layers 5f on the surface thereof. For
example, FIG. 5A shows an example in which two front surface electrode layers 5 f and one front
surface electrode layer 5 f ′ are formed in parallel in three rows.
[0057]
In such a case, as shown in FIG. 5B, at least the thickness α for the surface electrode layer 5f and
the thickness α ′ for the surface electrode layer 5f ′ are considered, so the thickness of the
piezoelectric element 5 as a whole is determined. It can be uneven.
[0058]
In order to make the thicknesses of the surface electrode layer 5f and the surface electrode layer
5f 'different from each other, for example, the surface electrode layer 5f' may be printed in
multiple layers, for example.
Moreover, it is not necessary to make all the surface electrode layer 5 f and the surface electrode
layer 5 f ′ electrically conductive. That is, it may include the surface electrode layer 5f or the
surface electrode layer 5f 'which becomes a dummy.
[0059]
As described above, by thickening the portion where the front surface electrode layer 5 f or the
front surface electrode layer 5 f ′ having different Young's modulus is formed, the resonance
frequency can be deviated. That is, the peak P of the sound pressure at the resonance point can
be varied to flatten the frequency characteristic of the sound pressure. Therefore, good sound
pressure frequency characteristics can be obtained.
[0060]
In addition, when the piezoelectric element 5 is co-fired with the surface electrode layer 5f or the
surface electrode layer 5f ', the portion in contact with the surface electrode layer 5f or the
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surface electrode layer 5f' of the piezoelectric layer 5a is as shown in FIG. The particle diameter
of the piezoelectric particles is larger than that of the portion not in contact with the surface
electrode layer 5 f or the surface electrode layer 5 f ′. This is because the portion covered with
the surface electrode during firing can not be in contact with the surrounding air as compared
with the other portions, resulting in sintering in an oxygen-deficient state. In the oxygen deficient
state, oxygen defects which promote sintering are generated in excess in the crystal particles of
the piezoelectric raw material as compared to other portions, thereby promoting the growth of
the piezoelectric particles.
[0061]
Since the difference in size of the piezoelectric particles makes the piezoelectric characteristics of
the piezoelectric body different, a plurality of regions with different resonance frequencies can be
present inside the piezoelectric element 5. That is, since the sound pressure peak P at the
resonance point can be dispersed to flatten the sound pressure frequency characteristics, it is
possible to obtain good sound pressure frequency characteristics.
[0062]
5A and 5B show an example in which the front surface electrode layer 5f and the front surface
electrode layer 5f 'are formed in parallel in three rows, but in this case, the entire piezoelectric
element 5 has at least symmetry. It has a different shape.
[0063]
Therefore, as shown in FIG. 5C, the surface electrode layer 5f may be scattered on the surface of
the piezoelectric element 5 in the form of islands to reduce the symmetry of the entire
piezoelectric element 5.
In this case, the resonance frequency of the piezoelectric element 5 itself varies due to a decrease
in the symmetry of the entire piezoelectric element 5, so that the peak P of the sound pressure at
the resonance point is dispersed, and the frequency characteristic of the sound pressure Can be
flattened. Therefore, good sound pressure frequency characteristics can be obtained.
[0064]
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Next, a sound generating device and an electronic device equipped with the sound generator 1
according to the embodiment described above will be described with reference to FIGS. 6A and
6B. FIG. 6A is a view showing the configuration of the sound generation device 20 according to
the embodiment, and FIG. 6B is a view showing the configuration of the electronic device 50
according to the embodiment. In both figures, only the components necessary for the description
are shown, and the description of general components is omitted.
[0065]
The sound generation device 20 is a sound generation device such as a so-called speaker, and as
shown in FIG. 6A, for example, includes a sound generator 1 and a housing 30 that houses 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. By including such a housing 30, sound pressure in, for example, a low frequency
band can be increased.
[0066]
Also, the sound generator 1 can be mounted on various electronic devices 50. For example, in
FIG. 6B shown below, it is assumed that the electronic device 50 is a mobile terminal device such
as a mobile phone or a tablet terminal.
[0067]
As shown in FIG. 6B, the electronic device 50 includes the 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.
[0068]
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The electronic device 50 further includes a display unit 50 e, an antenna 50 f, and the sound
generator 1. In addition, the electronic device 50 includes a housing 40 that accommodates each
of these devices.
[0069]
Although FIG. 6B shows a state in which all the devices including the controller 50a are housed
in one housing 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.
[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.
[0071]
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.
[0072]
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.
[0073]
The sound generator 1 then operates as a sound output device in the electronic device 50.
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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.
[0074]
By the way, although the electronic device 50 was described as what is a portable terminal device
in FIG. 6B, 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, etc. .
[0075]
As described above, the sound generator according to the embodiment includes an exciter
(piezoelectric element) and a flat vibrator. The exciter vibrates when an electrical signal is input.
The vibrator is attached with the exciter and vibrates with the exciter due to the vibration of the
exciter. Moreover, the said exciter is formed so that thickness may become non-uniform |
heterogenous.
[0076]
Therefore, according to the sound generator which concerns on embodiment, the frequency
characteristic of a favorable sound pressure can be obtained.
[0077]
In the embodiment described above, the description has been made mainly by exemplifying the
case where the piezoelectric element is provided on one main surface of the vibrating body, but
the invention is not limited to this, and the piezoelectric element is provided on both sides of the
vibrating body. It may be provided.
[0078]
Further, in the above-described embodiment, the case where the shape of the region inside the
frame is substantially rectangular is taken as an example, and it may be any polygon as long as it
is a polygon, but it is not limited thereto. It may be in the form of
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[0079]
Moreover, in the embodiment described above, the case where the resin layer is formed to cover
the piezoelectric element and the vibrator within the frame of the frame is described as an
example, but such a resin layer may not necessarily be formed.
[0080]
Further, in the embodiment described above, the diaphragm is made of a thin film such as a resin
film. However, the present invention is not limited to this. For example, the diaphragm may be
made of a plate-like member.
[0081]
Further, in the above-described embodiment, the case where the support for supporting the
vibrator is the frame and the peripheral edge of the vibrator is supported is described as an
example, but the present invention is not limited thereto.
For example, only both ends in the longitudinal direction or the latitudinal direction of the
vibrator may be supported.
[0082]
In the above-described embodiment, although the case where the exciter is a piezoelectric
element has been described as an example, the exciter is not limited to a piezoelectric element,
and a function of vibrating by receiving an electric signal is described. What is possessed is good.
[0083]
For example, an electrodynamic exciter, an electrostatic exciter, or an electromagnetic exciter
well known as an exciter for vibrating a speaker may be used.
[0084]
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
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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.
[0085]
Further effects and modifications can be easily derived by those skilled in the art.
Thus, the broader aspects of the invention are not limited to the specific details and
representative embodiments represented and described above.
Accordingly, various modifications may be made without departing from the spirit or scope of
the general inventive concept as defined by the appended claims and their equivalents.
[0086]
1, 1 'Sound generator 2 Frame 3 Vibrator 3a Vibrator 5 Piezoelectric element 5a, 5b, 5c, 5d
Piezoelectric layer 5e Internal electrode layer 5f, 5g Surface electrode layer 5h, 5j External
electrode 6a, 6b Lead terminal 7 Resin layer 20 Sound generator 30, 40 Case 50 Electronic
equipment 50a Controller 50b Transmitter and receiver 50c Key input unit 50d Microphone
input unit 50e Display unit 50f Antenna 60 Electronic circuit P Peak
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