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JP2014127767

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DESCRIPTION JP2014127767
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. The vibrator is formed so that at least one side of the substantially
rectangular shape is different in length from the side opposite to the one side based on the
substantially rectangular shape which is a virtual basic shape in plan view. It has a shape.
[Selected figure] Figure 3
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.
[0005]
JP 2004-023436
[0006]
However, since the above-mentioned conventional sound generator actively utilizes the
resonance of the uniformly tensioned diaphragm, a peak (a portion where the sound pressure is
higher than that of the surroundings) and a dip in the frequency characteristic of the sound
pressure There is a problem that (the part where the sound pressure is lower than the
surrounding area) is 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.
The exciter vibrates when an electrical signal is input.
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The vibrator is attached with the exciter, and vibrates with the exciter due to the vibration of the
exciter.
The vibrator is formed so that at least one side of the substantially rectangular shape is different
in length from the side opposite to the one side based on the substantially rectangular shape
which is a virtual basic shape in plan view. It has a shape.
[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. 3 is a schematic plan view showing an example of the configuration of the sound generator
according to the embodiment. FIG. 4A is a schematic plan view showing a virtual basic shape of a
vibrating body. FIG. 4: B is a schematic diagram (the 1) which shows an example of formation of
a side. FIG. 4C is a schematic view (part 2) showing an example of forming a side. FIG. 4D is a
schematic view (No. 3) showing an example of forming a side. FIG. 5A is a schematic plan view
(part 1) showing a modified example of the shape of the vibrator. FIG. 5B is a schematic plan
view (No. 2) showing a modified example of the shape of the vibrator. FIG. 5C is a schematic plan
view (No. 3) showing a modified example of the shape of the vibrator. FIG. 5D is a schematic plan
view (No. 4) showing a modified example of the shape of the vibrator. FIG. 5E is a schematic plan
view (No. 5) showing a modified example of the shape of the vibrator. 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]
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Hereinafter, embodiments of a sound generator, a sound generator and an electronic device
disclosed in the present application will be described in detail with reference to the attached
drawings. Note that the present invention is not limited by the embodiments described below.
[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.
[0014]
Further, in the following, with respect to the constituent element composed of a plurality of parts,
a part of the plurality of parts may be given a reference numeral, and the rest may be omitted. In
such a case, it is assumed that the part given the reference numeral and the other part have the
same configuration.
[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).
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[0016]
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]
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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
2 because of its excellent mechanical strength and corrosion resistance.
[0021]
In the above description, the frame 2 is formed of two frame members, and the two frame
members sandwich and support the peripheral portion of the diaphragm 3 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.
[0022]
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.
[0023]
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.
[0024]
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.
The piezoelectric layers 5a, 5b, 5c and 5d are polarized as shown by arrows in FIG. 1B. That is,
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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.
[0025]
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.
[0026]
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.
[0027]
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.
[0028]
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.
[0029]
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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.
[0030]
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.
[0031]
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 damper 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.
[0032]
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.
[0033]
As described above, the vibrating body 3a, the piezoelectric element 5 and the resin layer 7 are
integrated, and constitute a so-called composite vibrating body that vibrates integrally.
[0034]
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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. It does not matter.
[0035]
By the way, as shown to FIG. 1A and FIG. 1B, the vibrating body 3a is supported substantially
flatly in the state which was tensioned uniformly in the frame of the frame 2. As shown in FIG.
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.
[0036]
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 vibrating body 3a is substantially flatly
supported in the frame 2 with tension applied uniformly.
[0037]
However, in such a case, since the peaks are concentrated at a specific frequency and degenerate
due to the resonance of the vibrator 3a, as shown in FIG.
[0038]
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
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difficult to obtain good sound quality.
[0039]
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.
[0040]
Here, attention is paid to the shape of the vibrating body 3a.
The vibrating body 3a has a substantially rectangular shape in the frame of the frame 2 as
described above, and has symmetry in the shape. Therefore, because of such symmetry, it is easy
to generate a specific standing wave, which makes it difficult to flatten the frequency
characteristic of sound pressure.
[0041]
Therefore, in the present embodiment, at least one side of the substantially rectangular side of
the vibrating body 3a is different in length from the side opposite to the one side.
[0042]
That is, the symmetry of the shape of the vibrating body 3a and hence the entire composite
vibrating body described above is intentionally reduced to make it difficult to generate a standing
wave of a specific frequency and wavelength.
At the same time, the reflected wave returning from the frame 2 to the vibrating body 3a is
disturbed, and the symmetry of the reflected wave is also lowered.
[0043]
Then, as a result, the resonance frequencies are partially made uneven, thereby degenerating and
dispersing the resonance mode, thereby reducing the height of the peak P and widening the peak
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width.
[0044]
Hereinafter, the sound generator 1 which concerns on embodiment is concretely demonstrated in
order using FIGS. 3-5E.
First, FIG. 3 is a schematic plan view showing an example of the configuration of the sound
generator 1 according to the embodiment.
[0045]
In addition, although a schematic plan view may be shown below including FIG. 3 in any case,
illustration of the resin layer 7 is abbreviate | omitted similarly to FIG. 1A.
[0046]
As shown in FIG. 3, in the sound generator 1, compared with the sound generator 1 ′ of FIGS.
1A and 1B, the vibrating body 3 a has a substantially rectangular shape having a virtual basic
shape in plan view (see FIG. The point of difference is that at least one side of the substantially
rectangular shape has a shape formed to be different in length from the side opposite to the one
side based on the two-dot chain line in FIG.
[0047]
Here, in order to make the following description easy to understand, in this embodiment, the
vibrating body 3a is formed such that “at least one side of the substantially rectangular shape
has a length different from the side opposite to the one side”. , FIG. 4A to FIG. 4D will be
described in detail.
[0048]
FIG. 4A is a schematic plan view showing a virtual basic shape of the vibrating body 3a.
Moreover, FIG. 4B-FIG. 4D are the schematic diagrams (the 1)-(the 3) which show an example of
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formation of a side.
[0049]
As shown in FIG. 4A, in the present embodiment, the virtual basic shape of the vibrating body 3a
is substantially rectangular.
Needless to say, such a substantially rectangular shape has four sides and four vertices which are
end points of such sides.
As shown in FIG. 4A, in the present embodiment, the description will proceed with the symbols
“S1” to “S4” attached to each side and the symbols “a1” to “a4” attached to each
vertex.
[0050]
Here, the side S1 and the side S3 are "opposing sides". Similarly, the side S2 and the side S4 are
also "opposing sides".
[0051]
And the sound generator 1 of this embodiment has the vibrating body 3a of the shape formed
such that "at least one side is different from the side opposite to this one side" in the side S1 to
the side S4. For example, as shown in FIG. 4B, the vibration body 3a has a shape in which the
apex a4 is shifted from the substantially rectangular basic position (see the basic line BL in the
drawing) to the end a of the side S1. It is done by forming.
[0052]
Also, for example, as shown in FIG. 4C, this may be performed without shifting the vertex a1 and
the vertex a4 from the substantially rectangular basic position (see the basic line BL in the
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figure). Specifically, as shown in FIG. 4C, for example, the side S1 is formed so as to be non-linear
on the entire side S1 by including the line segment S11 and the line segment S12 passing
through the bending point cp. It is also good.
[0053]
Also, for example, as shown in FIG. 4D, this may be performed by continuously changing the line
connecting the vertex a1 and the vertex a4. Specifically, as shown in FIG. 4D, for example, the
side S1 may be formed in a curved line connecting the vertex a1 and the vertex a4.
[0054]
In addition, the effect by an example of formation of the edge | side shown to FIG. 4B-FIG. 4D is
mentioned later separately, respectively. It returns to the explanation of FIG. Here, the shape of
the vibrator 3a shown in FIG. 3 is an example of the formation of the side in FIG. 4B described
above.
[0055]
That is, the length of the side S1 is made different from the length of the side S3 opposite to the
side S1 by setting the apex a4 'obtained by shifting the apex a4 as the end point of the linear side
S1. In addition, the length of the side S4 is made different from the length of the side S2 opposed
to the side S4.
[0056]
By setting the vibrating body 3a in such a shape that the opposing sides have different lengths, it
is possible to make the wavelength and the frequency of the standing wave determined by the
shape of the vibrating body 3a not coincide with each other.
[0057]
In other words, it is possible to reduce the symmetry of the vibrating body 3a, and hence the
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shape of the entire composite vibrating body described above, to make it difficult to generate a
standing wave of a specific frequency and wavelength.
At the same time, the reflected wave returning from the frame 2 to the vibrating body 3a can be
disturbed, and the symmetry of the reflected wave can also be lowered.
[0058]
Then, as a result, the resonance frequency can be partially made uneven, so that the peak P of
the sound pressure at the resonance point can be dispersed, and the frequency characteristic of
the sound pressure can be flattened. That is, good sound pressure frequency characteristics can
be obtained.
[0059]
The shape of the vibrating body 3a is not limited to the example shown in FIG. Therefore, on the
premise of an example of the formation of the side already described with reference to FIGS. 4B
to 4D, modifications of the shape of the vibrating body 3a will be described with reference to
FIGS. 5A to 5E.
[0060]
5A to 5E are schematic plan views (No. 1) to (No. 5) showing modified examples of the shape of
the vibrator 3a.
[0061]
As shown in FIG. 5A, the vibrator 3a may have, for example, a shape such that at least a side S1
connecting at least the vertex a1 and the vertex a4 is non-linear as a whole.
In addition, this is an example of formation of the edge of FIG. 4C mentioned above.
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[0062]
Moreover, although the example shown to FIG. 5A is a case where the edge | side is bent in one
point (that is, one bending point is one), the number of objects of a bending point is not limited.
In the example shown in FIG. 5A, only one of the opposing sides is non-linear, but it is assumed
that the opposing sides are non-linear and have different lengths. It is also good.
[0063]
Specifically, as shown in FIG. 5B, for example, the side S1 may be bent at a plurality of (four in
the drawing) bending points so as to form a so-called notch in the vibrating body 3a. Also,
together with this, the side S1 and the side S3 have a length different from each other by bending
the opposing side S3 at a plurality of (eight in the figure) bending points so as to form two
notches. May be different.
[0064]
As shown in FIGS. 5A and 5B, the shape of the vibrating body 3a is formed such that at least one
side of the substantially rectangular shape is non-linear, and the length is different from the side
opposite to the one side. The following effects can be obtained by being done.
[0065]
That is, the symmetry of the shape of the vibrating body 3a and hence the entire composite
vibrating body described above can be reduced to make it difficult to generate a standing wave of
a specific frequency and wavelength.
At the same time, the reflected wave returning from the frame 2 to the vibrating body 3a can be
disturbed, and the symmetry of the reflected wave can also be lowered.
[0066]
Then, as a result, the resonance frequency can be partially made uneven, so that the peak P of
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the sound pressure at the resonance point can be dispersed, and the frequency characteristic of
the sound pressure can be flattened. That is, good sound pressure frequency characteristics can
be obtained.
[0067]
Further, as in the example shown in FIG. 5B, in particular, by bending the side at a plurality of
bending points so as to form a notch in the vibrating body 3a, for example, vibration waves are
effectively transmitted around the notch. It can be disturbed.
[0068]
That is, since the resonance frequencies can be effectively made partially unequal, the peak P of
the sound pressure at the resonance point can be dispersed to flatten the frequency
characteristics of the sound pressure.
Therefore, good sound pressure frequency characteristics can be obtained.
[0069]
Moreover, although the case where it formed so that it might become non-linear form which
combined the several line segment in FIG. 5A and 5B was illustrated, it may be a curve form
which changes continuously. In addition, this is an example of formation of the edge of FIG. 4D
mentioned above.
[0070]
Specifically, as shown in FIG. 5C, the vibrator 3a may have, for example, a shape in which at least
the side S1 has a curved shape.
[0071]
Moreover, although the example shown to FIG. 5C is a case where side S1 is the curve shape
which bulges toward the outer peripheral side of the frame 2, it does not limit the expansion
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direction of a curve.
The example shown in FIG. 5C is a case where only one of the opposing sides is curved, but the
opposing sides may be curvilinear and have different lengths. .
[0072]
Specifically, as shown in FIG. 5D, in addition to the example of FIG. 5C, for example, the side S3
may be formed into a so-called curvilinear curve so that the length is different at least from the
opposing side S1.
[0073]
As shown in FIGS. 5C and 5D, the shape of the vibrating body 3a is formed such that at least one
side of the substantially rectangular shape is curved, and the length is different from the side
opposite to the one side. The following effects can be obtained by
[0074]
That is, since the length of the vibrating body 3a which determines the wavelength of the
standing wave is continuously changed, it is possible to make it difficult to generate the standing
wave of the specific frequency and wavelength.
As a result, the resonance frequency can not be partially aligned, and the sound pressure peak P
at the resonance point can be dispersed to flatten the frequency characteristic of the sound
pressure.
That is, good sound pressure frequency characteristics can be obtained.
[0075]
In addition, since the symmetry of the shape of the vibrating body 3a and hence of the entire
composite vibrating body described above is lowered, it is also possible to make it difficult to
generate a standing wave of a specific frequency and wavelength. At the same time, the reflected
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wave returning from the frame 2 to the vibrating body 3a can be disturbed, and the symmetry of
the reflected wave can also be lowered.
[0076]
Then, as a result, the resonance frequency can be partially made uneven, so that the peak P of
the sound pressure at the resonance point can be dispersed, and the frequency characteristic of
the sound pressure can be flattened. That is, good sound pressure frequency characteristics can
be obtained.
[0077]
Of course, the examples shown in FIGS. 5A to 5D may be combined. For example, as shown in
FIG. 5E, the vertex a1 and the vertex a2 may be shifted from the virtual substantially rectangular
shape to be the vertex a1 ′ and the vertex a2 ′, and the side S1 connecting the vertex a1 ′
and the vertex a4 may be curved. . Further, the side S3 connecting the vertex a2 'and the vertex
a3 may be linear.
[0078]
As shown in FIG. 5E, even in the case of combining the examples shown in FIGS. 5A to 5D, the
lengths of the opposing sides are made different, and the vibrating body 3a, and thus the abovementioned composite vibrating body It is essential that the whole be configured to reduce the
symmetry of its shape.
[0079]
As a result, since the resonance frequencies can be partially unequalized, the peak P of the sound
pressure at the resonance point can be dispersed to flatten the frequency characteristic of the
sound pressure.
That is, the sound generator 1 which has the frequency characteristic of a favorable sound
pressure can be obtained.
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18
[0080]
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.
[0081]
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.
[0082]
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.
[0083]
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.
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[0084]
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.
[0085]
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.
[0086]
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.
[0087]
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.
[0088]
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.
[0089]
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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.
[0090]
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. .
[0091]
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. The vibrator is formed so that at least one side of the substantially rectangular shape is
different in length from the side opposite to the one side based on the substantially rectangular
shape which is a virtual basic shape in plan view. It has a shape.
[0092]
Therefore, according to the sound generator which concerns on embodiment, the frequency
characteristic of a favorable sound pressure can be obtained.
[0093]
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.
[0094]
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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.
[0095]
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.
[0096]
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.
[0097]
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.
[0098]
For example, an electrodynamic exciter, an electrostatic exciter, or an electromagnetic exciter
well known as an exciter for vibrating a speaker may be used.
[0099]
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.
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[0100]
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.
[0101]
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
device 50a Controller 50b Transmitter and receiver 50c Key input unit 50d Microphone input
unit 50e Display unit 50f Antenna 60 Electronic circuit BL Basic line P Peak S Peak S1 Side S11,
S12 Line segment S2 to S4 Edge a1 to a4 vertex cp inflection point
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