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DESCRIPTION JP2014003571

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DESCRIPTION JP2014003571
Abstract: A means for reproducing (oscillating) high-quality sound with high drop impact
resistance is desired. SOLUTION: A ceiling portion 10A and a floor portion 10C overlapping with
the ceiling portion 10A in a plan view and being separated from the ceiling portion 10A, a ceiling
portion 10A and a floor portion 10C are connected, and elasticity is provided. The first vibrating
member 10 having the first beam portion 10B, the piezoelectric element 20 held by the ceiling
10A of the first vibrating member 10, and the first surface facing the floor 10C 1. An oscillation
device comprising a support member 30 for supporting a first vibration member 10, and an
elastic member 40 located between a first surface and a floor 10C. [Selected figure] Figure 1
Oscillator and electronic device
[0001]
The present invention relates to an oscillator and an electronic device.
[0002]
In mobile terminals such as mobile phones, development of thin and stylish mobile phones that
use audio functions such as music reproduction and hands-free as a commercial value has been
activated.
Among them, there is a high demand for an electro-acoustic transducer (oscillator) to be compact
and thin and to have high sound quality.
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[0003]
In ordinary mobile phones, dynamic speakers are used as the speakers. However, since the sound
pressure level of an electrodynamic speaker using a magnetic circuit depends on the volume
exclusion amount, the sound pressure level is limited in principle. For this reason, although it is
necessary to increase the amount of vibration amplitude for making the high sound pressure,
when the driving force of the magnetic circuit is taken into consideration, the magnetic flux is a
factor, and there is a problem of being traded off with the volume of the magnet. Further, in
thinning as well as thinning of the magnet, thinning of the voice coil is necessary, but in a
magnetic circuit through which a large current flows, there are problems such as burnout.
[0004]
Therefore, there is a piezoelectric oscillation device as a thin oscillation device replacing the
electrodynamic type. This is to generate a vibration amplitude by utilizing the piezoelectric
electrostrictive effect.
[0005]
In Patent Document 1, a pedestal is formed of a piezoelectric element and a stretchable member,
and a pedestal to which the main surface of the piezoelectric element is attached, and a plurality
of beams connected to the outer peripheral portion of the pedestal and the other end connected
to the support member A piezoelectric actuator is disclosed having a member. The pedestal of the
piezoelectric actuator vibrates in the thickness direction of the piezoelectric element in
accordance with the expansion and contraction movement of the piezoelectric element. Each
beam member has an extension portion extending from the outer peripheral portion of the
pedestal toward the device side, and a rising portion continuous with the extension portion and
extending in a direction intersecting the extension portion.
[0006]
International Publication No. 2007/026736
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[0007]
The piezoelectric oscillation device is advantageous in thinning because the piezoelectric element
itself is a vibration source.
However, as a problem of the piezoelectric oscillation device, there is a high machine quality
factor Q (hereinafter, “machine Q”) and drop stability.
[0008]
Since the piezoelectric oscillator has a high mechanical Q, a large sound pressure level can be
obtained near the resonance frequency, but the sound pressure level is attenuated in the other
bands. That is, peaks and valleys occur in the sound pressure frequency characteristic, and the
flat sound pressure frequency characteristic, which is an essential factor for high sound quality,
is deteriorated.
[0009]
Moreover, since the piezoelectric ceramic that can be used for the piezoelectric element is a
brittle material, when stress is concentrated on a specific location, breakage such as cracking or
chipping occurs. The portable terminal is required to have high impact resistance to fall, and thus
there is a problem from the viewpoint of practicality.
[0010]
In addition, since piezoelectric ceramics have high rigidity, a large shape is required to obtain a
low resonance frequency. There has been a practical problem in portable terminals that are
required to be miniaturized.
[0011]
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For this reason, in the piezoelectric oscillation device, means for reproducing (oscillating) highquality sound with high impact resistance to fall is desired. In addition, although the subject of
the oscillation apparatus was demonstrated taking the example of a portable terminal here, the
same subject exists in the oscillation apparatus used with another electronic device.
[0012]
According to the present invention, a ceiling portion overlaps with the ceiling portion in plan
view, and a floor portion separated from the ceiling portion is connected to the ceiling portion
and the floor portion, and has elasticity. A first vibrating member having a beam portion; a
piezoelectric element held by the ceiling portion of the first vibrating member; and a first surface
in a state in which a first surface faces the floor portion. And a resilient member positioned
between the first surface and the floor portion.
[0013]
Further, according to the present invention, an electronic device having the above-described
oscillation device is realized.
[0014]
According to the present invention, means for reproducing (oscillating) high-quality sound with
high impact resistance to falling is desired.
[0015]
It is an example of the cross-sectional schematic diagram of the oscillation apparatus of this
embodiment.
It is an example of the perspective schematic diagram of the oscillation apparatus of this
embodiment.
It is another example of the cross-sectional schematic diagram of the oscillation apparatus of this
embodiment.
It is a graph which shows the relationship between frequency and a sound pressure level. FIG. 6
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is a diagram showing an oscillation device of Comparative Example 1;
[0016]
Hereinafter, embodiments of the electronic device and the oscillation device of the present
invention will be described using the drawings. The drawings are merely schematics for
explaining the configuration of the invention, and the sizes, shapes, numbers, ratios of sizes
between different members, and the like of the respective members are not limited to those
illustrated unless otherwise stated.
[0017]
FIG. 1 shows an example of a schematic cross-sectional view of the oscillation device of the
present embodiment. As illustrated, the oscillation device of the present embodiment includes a
first vibrating member 10, a piezoelectric element 20, a support member 30, and an elastic
member 40. FIG. 2 shows a schematic perspective view of the oscillation device shown in FIG.
The side wall 30B of the support member 30 shown in FIG. 1 is omitted. Each member will be
described below.
[0018]
The first vibrating member 10 has a ceiling 10A, a floor 10C, and a first beam 10B. The ceiling
portion 10A, the floor portion 10C, and the first beam portion 10B can be made of a metal
material such as phosphor bronze or stainless steel. For example, the ceiling portion 10A, the
floor portion 10C, and the first beam portion 10B may be formed by processing a plate-like metal
material having a thickness of 10 μm to 200 μm. The ceiling 10A, the floor 10C, and the first
beam 10B may be made of the same metal material, or may be made of different metal materials.
Further, the thicknesses of the ceiling portion 10A, the floor portion 10C, and the first beam
portion 10B may be the same or may be different from each other.
[0019]
The ceiling portion 10A and the floor portion 10C overlap in plan view. Further, the ceiling
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portion 10A and the floor portion 10C are located apart from each other. The first beam portion
10B is connected to both the ceiling portion 10A and the floor portion 10C and connects them to
each other. The illustrated first beam portion 10B is connected to each other near the outer edge
of each of the ceiling portion 10A and the floor portion 10C. The support of the first beam
portion 10B realizes a state in which the ceiling portion 10A and the floor portion 10C are
separated from each other.
[0020]
The ceiling portion 10A and the first beam portion 10B, and the floor portion 10C and the first
beam portion 10B may be joined by means such as welding. Alternatively, any combination of the
ceiling portion 10A and the first beam portion 10B and the floor portion 10C and the first beam
portion 10B may be integrally formed of a metal plate of a predetermined shape. . That is, even if
the ceiling portion 10A and the first beam portion 10B or the floor portion 10C and the first
beam portion 10B connected to each other are formed by bending a predetermined portion of a
block of metal plate having a predetermined shape. Good.
[0021]
In the illustrated example, the planar shape of the ceiling portion 10A is a circle, but is not
limited to this, and may be another shape such as a polygon or an oval. Although the size of the
planar shape of the ceiling portion 10A is a matter of design, the piezoelectric element 20
described below is attached to the ceiling portion 10A. Therefore, the size of the planar shape of
the ceiling portion 10A is preferably larger than the planar shape of the piezoelectric element 20.
[0022]
The first beam portion 10B is configured to have elasticity. Specifically, when a voltage is applied
to the piezoelectric element 20 attached to the ceiling portion 10A and an electric field is applied,
the piezoelectric element 20 performs a stretching movement. And the force resulting from the
expansion-contraction movement of the said piezoelectric element 20 will be added to 1st beam
part 10B. The first beam portion 10B is configured to elastically deform when receiving the
force. Specifically, the distance between the connection point (boundary point) between the first
beam portion 10B and the ceiling portion 10A and the connection point (boundary point)
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between the first beam portion 10B and the floor portion 10C becomes smaller (larger And then
elastically deform back to its original state. Due to the elastic deformation of the first beam
portion 10B, the first vibrating member 10 achieves a smaller (possibly larger) distance between
the ceiling portion 10A and the floor portion 10C, and thereafter realizes an oscillating motion
returning to the original state. can do.
[0023]
The means for realizing the above-mentioned elasticity of the first beam portion 10B is realized,
for example, by configuring the first beam portion 10B to have a curved portion (curved surface),
as shown in FIGS. It is also good. That is, the first beam portion 10B may constitute a spring. And
the ceiling part 10A may be located in the one end side of a curved part, and the floor part 10C
may be located in the other end side. The above-mentioned elasticity of the first beam portion
10B may be realized by other means. The number, planar area, thickness, etc. of the first beam
portions 10B are designed to realize the elasticity as described above. In addition, as shown in
FIG. 2, when providing the some 1st beam part 10B mutually isolate | separated, these some 1st
beam part 10B may be arrange | positioned so that it may become equal intervals.
[0024]
The planar shape and size of the floor portion 10C are not particularly limited, but for example,
an opening can be provided as shown in FIG. By the floor portion 10C being provided with the
opening, the rigidity of the entire first vibrating member 10 can be reduced. As a result, the
amplitude expansion of the vibration operation and the reduction of the fundamental resonance
frequency are realized.
[0025]
For example, as shown in FIG. 2, the floor portion 10C connects the central island portion 12C,
an outer peripheral portion 11C surrounding the central island portion 12C with a
predetermined gap therebetween, and a plurality connecting the central island portion 12C and
the outer peripheral portion 11C. And the second beam portion 13C.
[0026]
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The plane shape of the floor portion 10C may be point-symmetrical.
In the case of the example shown in FIG. 2, the planar shape of the central island portion 12C is
circular, and the planar shape of the outer peripheral portion 11C is circular. And, the center of
the circle of the central island 12C and the center of the circle drawn by the outer peripheral
portion 11C coincide with each other. There are four second beam portions 13C, each extending
from the center of the circle of the central island portion 12C toward the outer peripheral
portion 11C. The four second beam portions 13C divide the gap existing between the central
island portion 12C and the outer peripheral portion 11C into four equal parts. In addition, FIG. 2
is an example to the last, and the floor part 10C can be made into another structure. For example,
the planar shape of the central island 12C may be another shape, or the planar shape of the
outer peripheral portion 11C may be another shape, and the number and shape of the second
beam portions 13C may be other It is good also as composition. The planar shape of the second
beam portion 13C may be linear or curved or zigzag.
[0027]
As described above, even in the case where the floor portion 10C is provided with an opening, by
providing a region (central island portion 12C) of a predetermined size in the central portion of
the floor portion 10C, the entire first vibrating member 10 can be obtained. Balance can be kept
good. As a result, it is possible to suppress the inconvenience that the unnecessary sound such as
the divided vibration is generated to deteriorate the sound quality. Moreover, the same effect can
be implement | achieved by making the planar shape of the floor part 10C into a pointsymmetrical shape.
[0028]
The piezoelectric element 20 is formed of, for example, a piezoelectric ceramic such as PZT. The
piezoelectric element 20 is held by the ceiling 10 A of the first vibrating member 10. As shown in
FIGS. 1 and 2, the piezoelectric element 20 may be held by the surface of the ceiling 10A facing
the floor 10C, or the opposite surface, ie, the floor of the ceiling 10A. It may be held by a surface
that does not face 10C. The means for attaching the piezoelectric elements 20 to the ceiling
portion 10A is not particularly limited, but may be attached to each other with a conductive
adhesive, for example. The oscillation device of the present embodiment is configured to be able
to apply a voltage to the piezoelectric element 20, and when an electric field is applied, the
piezoelectric element 20 performs stretching movement.
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[0029]
The support member 30 supports the first vibrating member 10. The first vibrating member 10
holds the piezoelectric element 20. The support member 30 has a flat portion 30A. The support
member 30 supports the first vibrating member 10 in a state where the first surface (the upper
surface in FIG. 1) of the flat portion 30A and the floor portion 10C of the first vibrating member
10 face each other. Do. The planar shape of the flat portion 30A is not limited to the illustrated
circle, and may be another shape such as a polygon or an oval.
[0030]
The support member 30 may further include a side wall portion 30B extending from the first
surface of the flat portion 30A to the side where the first vibrating member 10 is positioned. The
side wall 30B can be configured to surround the periphery of the first vibrating member 10 in a
plan view. In the example shown in FIG. 2, the side wall 30B is omitted. In addition, the support
member 30 can also be set as the structure which does not have the side wall part 30B.
[0031]
The support member 30 can be formed of, for example, a material such as brass or stainless
steel.
[0032]
The elastic member 40 is located between the support member 30 and the first vibrating
member 10.
Specifically, the elastic member 40 is located between the first surface (upper surface in FIG. 1)
of the flat portion 30A of the support member 30 and the floor portion 10C of the first vibrating
member 10. That is, the elastic member 40 is connected not only to the flat portion 30A but also
to the floor portion 10C.
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[0033]
The elastic member 40 is made of, for example, a resin material, a carbon fiber, or the like. The
thickness of the elastic member 40 (the thickness in the direction connecting the support
member 30 and the first vibrating member 10) is, for example, 200 μm or less.
[0034]
The elastic member 40 is configured to be elastically deformed. Specifically, when a voltage is
applied to the piezoelectric element 20 attached to the first vibrating member 10 and an electric
field is applied, the piezoelectric element 20 performs a stretching movement. And the force
resulting from the expansion-contraction movement of the said piezoelectric element 20 will be
added to 1st beam part 10B. The first beam portion 10B elastically deforms when receiving the
force. Due to the elastic deformation of the first beam portion 10B, the first vibrating member 10
decreases (or may increase) the distance between the ceiling portion 10A and the floor portion
10C, and then returns to its original vibration operation (hereinafter referred to as , “First
vibration operation”). The elastic member 40 elastically deforms when it receives a force
resulting from such vibration of the first vibrating member 10. Specifically, the distance between
the contact point of the elastic member 40 and the flat portion 30A and the contact point of the
elastic member 40 and the floor portion 10C becomes small (or may become large), and then
elastically deformed to return to the original state. Due to the elastic deformation of the elastic
member 40, the first vibrating member 10 vibrates in such a manner that the floor portion 10C
approaches (belongs to) the flat portion 30A of the support member 30, and then returns to its
original state (hereinafter referred to as “second To realize the vibration operation ").
[0035]
The vibration direction of the first vibration operation substantially matches the vibration
direction of the second vibration operation. That is, regardless of any vibration operation, the
ceiling portion 10A of the first vibrating member 10 approaches the flat portion 30A of the
support member 30 and moves away from it (vibration in the vertical direction in FIG. 1). It will
be done. Therefore, by adding the first vibration operation and the second vibration operation,
the vibration of the first vibrating member 10, specifically, the vibration of the ceiling portion
10A can be enlarged.
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[0036]
The floor portion 10C of the first vibrating member 10 has a central island portion 12C, an outer
peripheral portion 11C, and a plurality of second beam portions 13C, as shown in FIG. When
configured, the elastic member 40 may be located between the outer peripheral portion 11C and
the first surface of the flat portion 30A, and between the central island 12C and the first surface
of the flat portion 30A. Good. In such a case, the elastic member 40 may not be located between
the second beam portion 13C and the first surface of the flat portion 30A. By arranging the
elastic member 40 in such a part where the stress is concentrated, the effects (described below)
that can be realized by the elastic member 40 can be made remarkable.
[0037]
The connection between the elastic member 40 and the first vibrating member 10 can be
realized using, for example, a conductive adhesive. Also, the connection between the elastic
member 40 and the support member 30 can be realized similarly using, for example, a
conductive adhesive.
[0038]
Here, FIG. 3 shows an example of a schematic cross-sectional view of a modification of the
oscillation device of the present embodiment. Hereinafter, differences from the above-described
oscillation device described with reference to FIGS. 1 and 2 will be described. In addition, the
description about the part which can be considered as the same structure is abbreviate | omitted.
[0039]
In the example described with reference to FIGS. 1 and 2, the support member 30 may or may
not have the side wall 30B. However, the support member 30 of the modified example has a side
wall portion 30B extending from the first surface (upper surface in the drawing) of the flat
portion 30A to the side on which the first vibrating member 10 is located. The side wall portion
30B surrounds the periphery of the first vibrating member 10 in a plan view.
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[0040]
Further, in the example described with reference to FIGS. 1 and 2, the piezoelectric element 20
may be held on the surface facing the floor portion 10C of the ceiling portion 10A, or the
opposite surface, ie, the ceiling portion 10A. It may be held on the side not facing the floor
portion 10C. However, the piezoelectric element 20 of the modification is held on the surface of
the ceiling portion 10A facing the floor portion 10C.
[0041]
Then, the oscillator of the modified example has the second vibrating member 50. The second
vibrating member 50 is a plate-like vibrating film. The second vibrating member 50 can be made
of, for example, a PET film or a polyethylene film. The second vibrating member 50 is held by the
side wall 30 B and is connected to the ceiling 10 A of the first vibrating member 10. Specifically,
the second vibrating member 50 is joined to the surface of the ceiling 10A that does not face the
floor 10C. Therefore, when the ceiling portion 10A vibrates, the second vibrating member 50
vibrates due to the vibration.
[0042]
The means by which the side wall portion 30B holds the second vibrating member 50 is not
particularly limited, and can be realized using an adhesive such as an epoxy adhesive.
[0043]
Further, the means for connecting the second vibration member 50 and the ceiling portion 10A
is not particularly limited, and can be realized using an adhesive such as an epoxy adhesive.
[0044]
The oscillation device of the present embodiment described above can be used, for example, as
an electroacoustic transducer, and can be used, for example, in various electronic devices such as
a mobile phone.
[0045]
Next, the operation and effect of the present embodiment will be described.
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[0046]
The oscillation device of the present embodiment is configured to include the piezoelectric
element 20, the first vibration member 10, the elastic member 40, and the support member 30.
As shown in FIGS. 1 and 2, the first vibrating member 10 has a first beam portion 10B that bends
in the thickness direction (vertical direction in FIG. 1) of the oscillator, and the floor portion 10C
is an elastic member 40. Directly to the support member 30 via
[0047]
Then, a voltage is applied to the piezoelectric element 20 to apply an electric field, and when the
piezoelectric element 20 stretches and contracts, the first beam portion 10B elastically deforms
due to this.
Due to the elastic deformation of the first beam portion 10B, in the first vibrating member 10,
the ceiling portion 10A and the floor portion 10C move closer to each other (sometimes move
away from each other), and then return to their original vibration operation (first Vibration
operation).
Further, due to the expansion and contraction movement of the piezoelectric element 20, the
elastic member 40 is elastically deformed.
By the elastic deformation of the elastic member 40, the first vibrating member 10 approaches
(may move away from) the flat portion 30A of the support member 30, and then performs a
vibrating operation (second vibrating operation) to return to the original state.
[0048]
The vibration direction of the first vibration operation substantially matches the vibration
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direction of the second vibration operation. That is, regardless of any vibration operation, the
ceiling portion 10A of the first vibrating member 10 approaches the flat portion 30A of the
support member 30 and moves away from it (vibration in the vertical direction in FIG. 1). It will
be done. Therefore, by adding the first vibration operation and the second vibration operation,
the vibration of the first vibrating member 10, specifically, the vibration of the ceiling portion
10A can be enlarged. By expanding the stroke in the thickness direction (vertical direction in FIG.
1) of the oscillator, it is possible to expand the vibration propagation from the piezoelectric
element, and the sound pressure level is improved.
[0049]
Further, the elastic member 40 can be made of a resin material. In such a case, the elastic
member 40 functions as a damping material that reduces the mechanical Q of the piezoelectric
element. Further, as described above, by utilizing the sensitivity and the restoring force of the
elastic member 40, the elastic member 40 plays a role of a vibration expanding mechanism.
[0050]
That is, according to the oscillation device of the present embodiment, amplification of vibration
and reduction of the machine Q can be realized. As a result, high sound pressure level and flat
frequency sound pressure characteristics can be realized.
[0051]
It will be described in more detail.
When a voltage is applied to the piezoelectric element 20, the piezoelectric element 20 performs
a stretching movement. The vibration from the piezoelectric element 20 is transmitted to the
floor portion 10C through the ceiling portion 10A of the first vibrating member 10 to
concentrate stress on the floor portion 10C. Here, since the floor portion 10C is connected to the
support member 30 via the elastic member 40 having a large internal loss, the machine Q of the
oscillation device is reduced, and the flattening of the sound pressure frequency characteristics is
realized.
[0052]
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Further, the impact at the time of dropping can be absorbed by the first beam portion 10B of the
first vibrating member 10 and the elastic member 40, and the reliability is also improved.
[0053]
For this reason, when the oscillation device of the present embodiment is used as an
electroacoustic transducer, a high sound pressure level and flat frequency characteristics can be
realized as compared with a conventional piezoelectric transducer.
Moreover, since the oscillation device of the present embodiment is excellent in shock stability
and has high reliability, its industrial value is large.
[0054]
In addition, the oscillation frequency of the oscillation apparatus of this embodiment is not
specifically limited, For example, an ultrasonic wave 20 kHz or more can be oscillated. That is, it
can be used as a drive source of a parametric speaker.
[0055]
Here, FIG. 4 is a graph showing the relationship between frequency and sound pressure level.
Example 1 is an oscillating device of the structure of FIG. 3, and Comparative Example 1 is an
oscillating device of the structure of FIG.
[0056]
The comparative example 1 is a general piezoelectric actuator, and includes the support member
3, the vibration member 5 and the piezoelectric element 2. The support member 3 has the same
configuration as the support member 30 of the first embodiment, and has a flat portion 3A and a
side wall portion 3B. The vibrating member 5 has the same configuration as the second vibrating
member 50 of the first embodiment. The piezoelectric element 2 has the same configuration as
the piezoelectric element 20 of the first embodiment, but is directly joined to the second
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vibrating member 50.
[0057]
It can be seen from FIG. 4 that Example 1 achieves a high sound pressure level and also realizes
flat sound pressure frequency characteristics, as compared to Comparative Example 1.
[0058]
DESCRIPTION OF SYMBOLS 10 1st vibration member 10A ceiling part 10B 1st beam part 10C
floor part 11C outer peripheral part 12C center island part 13C 2nd beam part 20 piezoelectric
element 30 support member 30A flat part 30B side wall part 40 elastic member 50 2nd
Vibrating member
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