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DESCRIPTION JP2012100042

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DESCRIPTION JP2012100042
An oscillation device capable of reproducing a small volume with a large volume is provided.
Since the piezoelectric element 10 is fixed by a first resin member 41 which is an elastic member,
the movable range at the time of vibration is large, and the amplitude is expanded. Further, since
the second resin member 42 having lower rigidity than the first resin member 41 is interposed
between the first resin member 41 and the support 45, impedance matching of rigidity can be
achieved. For this reason, an audible sound can be reproduced by oscillating an ultrasonic wave
limited to a specific frequency using the high mechanical quality factor Q which is a feature of
the piezoelectric element 10, and a large volume can be reproduced. [Selected figure] Figure 1
Oscillator and electronic device
[0001]
The present invention relates to an oscillation device including a piezoelectric element, and an
electronic device including the oscillation device.
[0002]
In recent years, the demand for portable electronic devices such as mobile phones and notebook
computers has been expanding.
With regard to such electronic devices, development of thin portable terminals in which sound
functions such as videophone calls, video reproduction, hands-free telephones and the like have
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1
commercial value has been promoted. Among such developments, there is an increasing demand
for high-quality, compact, and thin oscillator devices (speaker devices) that are acoustic
components.
[0003]
2. Description of the Related Art Conventionally, an electrodynamic oscillation device has been
used as an oscillation device in electronic devices such as mobile phones. This electrodynamic
oscillator is composed of a permanent magnet, a voice coil and a vibrating membrane. However,
the electrodynamic oscillator has a limit in thinning due to its operation principle and structure.
On the other hand, Patent Documents 1 and 2 disclose that a piezoelectric element is used as an
oscillation device.
[0004]
Further, as another example of an oscillation device using a piezoelectric element, in addition to a
speaker device, an acoustic wave sensor that detects a distance to an object or the like using a
sound wave oscillated from a piezoelectric element (see Patent Document 3), etc. Various
oscillators and electronic devices are known. For example, there is a proposal to realize a
bimorph oscillation device by laminating two piezoelectric elements of the same shape and the
same material on an elastic member in two stages (Patent Document 4). There is also a proposal
to realize a bimorph oscillation device by arranging two piezoelectric elements having different
planar shapes one by one on both sides of the elastic member (Patent Document 5).
[0005]
Japanese Patent Application Publication No. 2007-026736 Japanese Patent Application
Publication No. 2007- 083497 Japanese Patent Application Laid-Open No. 03-270282 Japanese
Patent Application Laid-Open No. 2002-121391 Japanese Patent Application Laid-Open No.
2008-28593
[0006]
An oscillation apparatus using a piezoelectric element generates a vibration amplitude by an
electrostrictive action by an input of an electric signal by utilizing the piezoelectric effect of a
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2
piezoelectric layer.
And while an electrodynamic oscillation device generates vibration by piston type back and forth
movement, an oscillation device using a piezoelectric element has a smaller amplitude because it
takes a bending vibration mode. Therefore, the present invention is superior to the abovedescribed dynamic type oscillation device in thinning.
[0007]
However, since the ceramic material is a brittle material and the mechanical loss is small, the
mechanical quality factor Q tends to be higher than that of the electrodynamic electroacoustic
transducer which generates the amplitude from the organic film. For example, for the
electrodynamic type, the mechanical quality factor Q is about 3 to 5 and for the piezoelectric
type, it is about 50. Since the mechanical quality factor Q indicates sharpness at resonance, in
summary, in the piezoelectric electroacoustic transducer, the sound pressure is high near the
fundamental resonance frequency, and the sound pressure is attenuated in the other bands.
[0008]
That is, in the sound pressure level frequency characteristics, peaks and valleys of the acoustic
characteristics occur, and a sound of a specific frequency is emphasized or lost, and there is a
problem that sufficient sound quality can not be obtained for music reproduction and the like. In
addition, there are problems with the radiation area as well as the acoustic characteristics. Also in
the piezoelectric type electroacoustic transducer, the sound pressure level depends on the
volume exclusion amount (the product of the radiation area and the amplitude) as in the
electromagnetic transducer, so the radiation can be made even if thinning is possible. There is a
limit to the reduction of the area, and it does not fulfill sufficient functions as an electroacoustic
transducer for a mobile phone. For this reason, there has been a demand for an innovative
technology that produces high-quality, compact electro-acoustic transducers.
[0009]
The present invention has been made in view of the problems as described above, and provides
an oscillation device capable of reproducing a large volume even with a small size, and an
electronic apparatus using the oscillation device.
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[0010]
The oscillation device according to the present invention supports at least a piezoelectric element
in a flat plate-like piezoelectric element that moves in an expanding and contracting manner by
application of an electric field, a flat plate-like elastic member that restrains one of the two main
surfaces of the piezoelectric element. It has a first resin member, a second resin member
supporting the first resin member and having a smaller modulus of longitudinal elasticity than
the first resin member, and a frame-shaped support supporting at least the second resin member.
.
[0011]
A first electronic device of the present invention includes the oscillation device of the present
invention and an oscillation drive unit that causes the oscillation device to output sound waves in
an audible range.
[0012]
The second electronic device of the present invention includes the oscillation device of the
present invention, an ultrasonic detection unit that detects an ultrasonic wave emitted from the
oscillation device and reflected by the measurement object, and from the detected ultrasonic
wave to the measurement object And a distance measuring unit for calculating the distance of
[0013]
In the oscillation device of the present invention, since the piezoelectric element is fixed by the
first resin member which is an elastic member, the movable range at the time of vibration is large
and the amplitude is expanded.
Further, since the second resin member having lower rigidity than the first resin member is
interposed between the first resin member and the support, impedance matching of rigidity can
be achieved.
For this reason, an audible sound can be reproduced by oscillating an ultrasonic wave limited to a
specific frequency using the high mechanical quality factor Q which is a feature of the
piezoelectric element, and a large volume can be reproduced.
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[0014]
FIG. 1 is a schematic vertical front view showing a structure of an oscillation device according to
a first embodiment of the present invention.
It is a schematic plan view which shows the external appearance of an oscillation apparatus.
It is a typical longitudinal front view showing the structure of a piezoelectric element. It is a
schematic plan view which shows the structure of the oscillation apparatus of one modification.
It is a schematic diagram which shows operation | movement of the principal part of an
oscillation apparatus. It is a schematic diagram which shows operation | movement of an
oscillation apparatus. It is a schematic diagram which shows operation | movement of the
principal part of an oscillation apparatus. FIG. 6 is a schematic vertical front view showing a
structure of an oscillation device according to a second embodiment of the present invention. It is
a schematic diagram which shows operation | movement of a bimorph type piezoelectric
element. It is a disassembled perspective view which shows the assembly structure of the
piezoelectric element of the oscillation apparatus of the 3rd form of implementation of this
invention. It is a schematic plan view which shows the structure of the 4th form of
implementation of this invention. It is a schematic plan view which shows the structure of the
oscillation apparatus of the 5th form of implementation of this invention. It is a longitudinal front
view which shows the structure of the oscillation apparatus of one prior art example. It is a
typical front view which shows the external appearance of the mobile telephone which is an
electronic device.
[0015]
First Embodiment The embodiment of the present invention will be described with reference to
FIGS. 1 and 2. FIG. FIG. 1 is a schematic cross-sectional view showing the electro-acoustic
transducer of the present embodiment, and FIG. 2 is a schematic top view. As shown in FIG. 1, the
oscillation device 50, which is an electrodynamic electroacoustic transducer according to the
present embodiment, has one of two main surfaces of a flat plate-like piezoelectric element 10
that stretches and moves by application of an electric field. Supporting at least the first resin
member 41 having a longitudinal elastic modulus smaller than that of the first resin member 41
and the first resin member 41 supporting at least the piezoelectric element 10; And a frame-like
support 45 supporting at least the second resin member 42.
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[0016]
More specifically, the lower main surface of the piezoelectric element 10 is restrained by the
elastic member 20 to form a vibrator, and both ends thereof are supported by the first resin
member 41. A second resin member 42 is interposed between the lower surface of the first resin
member 41 and the bottom surface of the support 45. The piezoelectric element 10 and the
elastic member 20 are joined via two first resin members 41 and a second resin member 42
having different elastic moduli. Further, the lead wire 46 is joined to the end of the piezoelectric
element 10 and the elastic member 20 and is fixed in the first resin member 41 and the second
resin member 42. Is connected to the terminal 47 of the
[0017]
The piezoelectric element 10 of the present invention is configured as shown in FIG. 3. The upper
and lower main surfaces of the piezoelectric material 3-b are constrained by the electrode
materials 3-a and 3-c. The piezoelectric material 3-b is not particularly limited as to both the
inorganic material and the organic material as long as it has a piezoelectric effect, but a material
having high electromechanical conversion efficiency, such as lead zirconate titanate (PZT) or
barium titanate Materials such as (BaTiO3) can be used. The thickness is not particularly limited,
but preferably 10 μm to 1 mm.
[0018]
When a thin film having a thickness of less than 10 μm is used as a ceramic material which is a
brittle material, chipping and breakage occur due to weak mechanical strength during handling,
making handling difficult. In addition, when a ceramic having a thickness of more than 1 mm is
used, the conversion efficiency for converting electrical energy into mechanical energy is
significantly reduced, and sufficient performance as the oscillation device 50 can not be
obtained. Generally, in a piezoelectric ceramic that produces an electrostrictive effect by the
input of an electrical signal, its conversion efficiency depends on the electric field strength. Since
this electric field strength is expressed by thickness / input voltage with respect to the
polarization direction, an increase in thickness inevitably causes a decrease in conversion
efficiency.
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[0019]
In the piezoelectric element 10 of the present invention, an electrode layer is formed on the main
surface in order to generate an electric field. The material is not particularly limited, but it is
possible to use, for example, silver or silver / palladium. Silver is used as a low-resistance
general-purpose electrode material and has advantages in manufacturing processes and costs,
and silver / palladium is a low-resistance material excellent in oxidation resistance, so it has
advantages in terms of reliability. is there.
[0020]
Moreover, the thickness of the electrode material is not particularly limited, but the thickness is
preferably 1 to 50 μm. If the thickness is less than 1 μm, since the film thickness is thin, it can
not be formed uniformly on the electrode, and the conversion efficiency may be reduced. When
the film thickness of the electrode exceeds 100 μm, there is no particular problem in
manufacture, but there is a problem that the electrode layer becomes a constraining surface with
respect to the piezoelectric ceramic material and the energy conversion efficiency is lowered.
[0021]
The main surface of one side of the piezoelectric element 10 of the present invention is
restrained by the elastic member 20. The elastic member 20 has a function of propagating the
vibration generated from the piezoelectric element 10 to the support 45. At the same time, the
elastic member 20 has a function of adjusting the fundamental resonance frequency of the
piezoelectric element 10. The fundamental resonant frequency of the mechanical oscillator
depends on the load weight and the compliance as shown by the following equation. In other
words, since the compliance is mechanical rigidity of the vibrator, this means that controlling the
rigidity of the piezoelectric element 10 can control the fundamental resonance frequency.
[0022]
[Equation 1] f = 1 / (2πL√ (mC)) where “m” is mass and “C” is compliance.
[0023]
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By selecting a material having a high elastic modulus or reducing the thickness of the elastic
member 20, the fundamental resonance frequency can be shifted to a lower range.
The elastic member 20 is not particularly limited as long as it is a material having a high elastic
modulus to ceramic which is a brittle material such as metal or resin, but a general-purpose
material such as phosphor bronze or stainless steel is used from the viewpoint of processability
and cost. Ru. The thickness is preferably 5 to 1000 μm. If the thickness is less than 5 μm, the
mechanical strength is weak, and there is a problem that the mechanical vibration characteristics
of the vibrator may vary among manufacturing lots due to the loss of the function as a
constraining member or the reduction due to the processing accuracy.
[0024]
In addition, when the thickness exceeds 1000 μm, there is a problem that the restraint on the
piezoelectric element 10 due to the increase in rigidity is intensified, and the vibration
displacement amount is attenuated. Moreover, as for the elastic member 20 of this embodiment,
it is preferable that the longitudinal elastic modulus which is a parameter | index which shows
the rigidity of material is 1-500 GPa. As described above, when the rigidity of the elastic member
20 is excessively low or excessively high, there is a problem that the characteristics and
reliability of the mechanical oscillator are impaired.
[0025]
In the oscillation device 50 of the present invention, the end portions of the piezoelectric element
10 and the elastic member 20 are bonded to the support 45 through the two types of first resin
members 41 and second resin members 42. The first resin member 41 is joined to the
piezoelectric material or the elastic member 20, and functions as a mechanism for expanding the
vibration. In the conventional piezoelectric oscillation device 50, the elastic member 20 for
restraining the piezoelectric element 10 is directly bonded to the support 45. However, in
bending vibration, as shown in FIG. 5, since stress is concentrated on the support 45 and the
elastic member 20, in this configuration, the function of the fixed end is performed, so the lower
rigidity is displaced from the theory of bending deformation. It is superior from the viewpoint of
expansion.
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[0026]
Further, in the present invention, the second resin member 42 is interposed between the first
resin member 41 and the bottom of the support 45. The second resin member 42 is a material
with low rigidity compared to the first resin member 41, and is characterized by having a low
elastic modulus, and has a function of expanding vibration displacement and a function of
improving the drop impact stability. Have. The elastic modulus of the second resin member 42 is
preferably 1/10 or less of the elastic modulus of the first resin member 41.
[0027]
Further, the second resin member 42 and the first resin member 41 are bonded by an adhesive,
and an epoxy-based adhesive or the like can be used for the adhesion. It is preferable that both
the second resin member 42 and the first resin member 41 be a material having high bonding
strength with respect to epoxy bonding. Furthermore, in order to reduce the vibration energy
loss at the joint, the thickness of the adhesive is preferably 20 μm or less. As shown in FIG. 6,
flexural vibration of the piezoelectric element 10 is converted in the thickness direction of the
piezoelectric element 10. That is, an amplitude movement in the thickness direction of the
oscillation device 50 occurs, and as shown in FIG. 7, the driving force and the inertia from the
piezoelectric element 10 act on the thickness direction.
[0028]
Therefore, it is a feature of the present invention to expand the amount of deformation using the
restoring force of the second resin member 42 having a high elastic deformation rate. In
addition, the second resin member 42 also absorbs the energy at the time of impact with respect
to the impact stability at the time of drop, so the reliability is improved. The first resin member
41 and the second resin member 42 are not particularly limited as long as the modulus of
longitudinal elasticity is a polymer material of 100 GPa or less, but from the viewpoint of
versatility, polyethylene terephthalate, polyethylene, urethane, The use of silicone rubber, natural
rubber, synthetic rubber, etc. is possible.
[0029]
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The method of manufacturing the oscillation device 50 of the present invention will be described
below. First, the piezoelectric element 10 is a piezoelectric plate having an outer diameter of 5 ×
3 mm and a thickness of 200 μm (0.2 mm), and an upper electrode material 3-a and a lower
electrode material 3 each having a thickness of 8 μm on both sides thereof. -B is formed. The
elastic member 20 is phosphor bronze having an outer diameter of 7 × 3 mm and a thickness of
300 μm (0.3 mm). The support 45 is made of SUS 304 and is directly bonded to the elastic
member 20. The support 45 is a bathtub-like case of an outer diameter = 10 × 5 mm and an
inner diameter = 8 × 3.5 mm, and is formed of SUS304.
[0030]
The piezoelectric material and the elastic member 20 were arranged concentrically at the center.
In addition, a lead zirconate titanate ceramic was used as the piezoelectric material, and a silver /
palladium alloy (70% by weight ratio: 30%) was used for the electrode layer. The piezoelectric
ceramic was produced by a green sheet method, and was fired in the atmosphere at 1100 ° C.
for 2 hours, and then the piezoelectric material layer was subjected to polarization treatment. An
epoxy-based adhesive was used to bond the piezoelectric element 10 and the elastic member 20.
Further, polyethylene was used for the first resin member 41, and natural rubber was used for
the second resin member 42.
[0031]
The operation principle of the oscillation device 50 of the present invention will be described
below. The oscillation device 50 of the present invention generates a sound wave traveling
toward the radiation surface from a plurality of transducers arranged in parallel. The frequency
is not particularly limited, but since the ultrasonic wave oscillated here is used as a carrier of the
modulation wave, it is preferable to be outside the audible band, for example, 100 KHz or the like
is suitable. Further, a sound reproducing method by the oscillation device 50 of the present
invention will be described.
[0032]
In this configuration, the operation principle of a parametric speaker, which is an acoustic
regenerator using ultrasonic waves as a carrier of modulated waves, is used. Here, ultrasonic
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waves with AM (Amplitude Modulation) modulation, DSB (Double Side Band amplitude
modulation) modulation, SSB (Single-Sideband Modulation) modulation, and FM (Frequency
Modulation) modulation are emitted into the air, and the ultrasonic waves Sound is reproduced
on the principle that an audible sound appears due to the non-linear characteristic when
propagating in the air.
[0033]
The non-linearity includes a phenomenon in which the transition from laminar flow to turbulent
flow occurs when the Reynolds number represented by the ratio of the flow inertia action to the
viscous action increases. That is, since the sound wave is finely disturbed in the fluid, the sound
wave is non-linearly propagating. However, although the amplitude of the sound wave in the low
frequency band is non-linear, the amplitude difference is very small, and is usually treated as a
phenomenon of linear theory.
[0034]
On the other hand, in the case of ultrasonic waves, non-linearity can be easily observed, and
when radiated into the air, harmonics with non-linearity are significantly generated. Roughly
speaking, in the air, sound waves are in a dense / dense state in which molecular groups are
mixed with concentration, and when time is required for air molecules to recover more than
compression, air that can not be recovered after compression continuously propagates. It is a
principle that collides with a molecule and a shock wave is generated to generate an audible
sound.
[0035]
As described above, the oscillation device 50 according to the present invention is highly reliable,
small in size, and capable of reproducing a large volume. In addition, since ultrasonic waves are
used, the directivity is narrow, and the industrial value is great in terms of user privacy
protection and the like.
[0036]
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Summarizing the above, the oscillation device 50 of the present invention can also be used as a
sound source of an electronic device (for example, a mobile phone, a laptop personal computer, a
small game machine, etc.). Since the entire oscillation device 50 does not increase in size and the
acoustic characteristics are improved, it can be suitably used for a portable electronic device.
[0037]
In the above embodiment, the rectangular oscillation device 50 is exemplified in which the
piezoelectric element 10, the elastic member 20, and the support 45 have a planar shape.
However, as shown in FIG. 4, it is also possible to implement an oscillating device in which the
piezoelectric element 10, the elastic member 20, and the support 45 are circular.
[0038]
Second Embodiment of the Embodiment A second embodiment of the present invention will be
described with reference to FIG. The present embodiment is characterized in that the elastic
member 20 is restrained by two piezoelectric elements 10 a and 10 b with respect to the first
embodiment. That is, it has a bimorph structure using two piezoelectric elements 10a and 10b.
As shown in FIG. 9, in the bimorph piezoelectric elements 10a and 10b, two piezoelectric
ceramics whose polarization directions are opposite to each other are bonded, one is stretched in
the longitudinal direction, and the other is bent to be bent. It is possible to obtain a larger
displacement as compared with the unimorph structure composed of one piezoelectric element
10a, 10b of the first form. The same piezoelectric material as that in the first embodiment can be
used for the two piezoelectric elements 10a and 10b. Further, the two piezoelectric elements 10a
and 10b may have the same shape or may have different shapes.
[0039]
As described above, the oscillation device according to the present embodiment can also be used
as a sound source of an electronic device (for example, a mobile phone, a laptop personal
computer, a small game machine, etc.). Since the entire oscillation device does not increase in size
and the acoustic characteristics are improved, it can be suitably used for portable electronic
devices.
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[0040]
Third Embodiment of the Invention A third embodiment of the present invention will be
described with reference to FIG. In the present embodiment, it is composed of a laminated
piezoelectric element. As shown in FIG. 10, the piezoelectric element 12 has a multilayer
structure in which five piezoelectric plates 13a to 13e made of a piezoelectric material are
stacked. Electrode layers (conductor layers) 14 a to 14 d are formed one by one between the
piezoelectric plates. The polarization direction of each of the piezoelectric plates 13a to 13e is
reversed in each layer, and the direction of the electric field is alternately reversed. According to
the piezoelectric element 12 having such a laminated structure, since the electric field strength
generated between the electrode layers 14a to 14d is high, the driving force of the piezoelectric
element as a whole is improved by an amount corresponding to the number of laminated layers
Do.
[0041]
As described above, the oscillation device according to the present embodiment can also be used
as a sound source of an electronic device (for example, a mobile phone, a laptop personal
computer, a small game machine, etc.). Since the entire oscillation device does not increase in size
and the acoustic characteristics are improved, it can be suitably used for portable electronic
devices.
[0042]
Fourth Embodiment of the Invention A fourth embodiment of the present invention will be
described with reference to FIG. In the present embodiment, the shape of the piezoelectric
element 10 is changed with respect to the first embodiment. By changing the shape of the
piezoelectric element 10 in this manner, any material for which a mass production process has
been established can be used, and the degree of freedom in design is improved. With regard to
the shape, materials of any shape such as rectangular, oval and circular can be used.
[0043]
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As described above, the oscillation device according to the present embodiment can also be used
as a sound source of an electronic device (for example, a mobile phone, a laptop personal
computer, a small game machine, etc.). Since the entire oscillation device does not increase in size
and the acoustic characteristics are improved, it can be suitably used for portable electronic
devices.
[0044]
Fifth Embodiment of the Invention A fifth embodiment of the present invention will be described
with reference to FIG. In the present embodiment, the shape and the number of the piezoelectric
elements 10 are changed with respect to the first embodiment. In this configuration, two small
piezoelectric elements 10 are used. By changing the number and shape of the piezoelectric
elements 10 in this manner, as in the fourth embodiment, any material for which a mass
production process has been established can be used, and design freedom is improved.
[0045]
As described above, the oscillation device according to the present embodiment can also be used
as a sound source of an electronic device (for example, a mobile phone, a laptop personal
computer, a small game machine, etc.). Since the entire oscillation device does not increase in size
and the acoustic characteristics are improved, it can be suitably used for portable electronic
devices.
[0046]
[Another Example of the Invention] The characteristic evaluation of the oscillation device of the
present invention was performed on the evaluation items of Evaluation 1 to Evaluation 2 below.
[0047]
(Evaluation 1) Measurement of sound pressure level frequency characteristics: The sound
pressure level when an AC voltage of 1 V was input was measured by a microphone placed at a
predetermined distance from the piezoelectric element.
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The predetermined distance is 10 cm unless otherwise specified, and the frequency measurement
range is 10 Hz to 10 kHz.
[0048]
(Evaluation 2) Drop Impact Test: A drop impact stability test was conducted by causing a mobile
phone equipped with an oscillation device to drop spontaneously five times from 50 cm directly
above. Specifically, breakage such as cracks after the drop impact test was visually confirmed,
and the sound pressure characteristics after the test were measured. As a result, the sound
pressure level difference (referring to the difference between the sound pressure level before the
test and the sound pressure level after the test) was 3 dB or less within 3 dB, and 3 dB or more
was x.
[0049]
Example 1 The characteristics of the oscillator described in the first embodiment of the present
invention were evaluated. Comparative Example 1 As a comparative example 1, the conventional
electrodynamic oscillation device of FIG. 13 was manufactured. Example 2 As Example 2, an
oscillation device of a second embodiment was produced. Example 3 As Example 3, an oscillation
device of the third embodiment was prepared. Example 4 As Example 4, an oscillator of the
fourth embodiment was produced. Example 5 As Example 5, an oscillation device of the fifth
form of implementation was created.
[0050]
As is clear from the above results, according to the oscillation devices of Examples 1 to 5, the
sound pressure level frequency characteristic is flat with a small size and high sound pressure
level.
[0051]
Example 6 As Example 6, a mobile phone as shown in FIG. 14 was prepared, and the oscillation
device of Example 1 was mounted in the housing.
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Specifically, the oscillation device is attached to the inner surface of the casing of the mobile
phone. Example 7 As Example 7, a mobile phone as shown in FIG. 14 was prepared, and the
oscillation device of Example 2 was mounted in the housing. Specifically, the oscillation device is
attached to the inner surface of the casing of the mobile phone. Example 8 As Example 8, a
mobile phone as shown in FIG. 14 was prepared, and the oscillation device of Example 3 was
mounted in the case. Specifically, the oscillation device is attached to the inner surface of the
casing of the mobile phone. Example 9 As Example 9, a mobile phone as shown in FIG. 14 was
prepared, and the oscillation device of Example 4 was mounted in the housing. Specifically, the
oscillation device is attached to the inner surface of the casing of the mobile phone. Example 10
As Example 10, a mobile phone as shown in FIG. 14 was prepared, and the oscillation device of
Example 5 was mounted in the housing. Specifically, the oscillation device is attached to the inner
surface of the casing of the mobile phone.
[0052]
As is clear from the above results, according to the oscillation devices of Examples 6 to 10, it was
confirmed that they were compact and had high sound pressure levels.
[0053]
The present invention is not limited to the present embodiment, and various modifications are
allowed without departing from the scope of the present invention.
For example, in the above embodiment, the use of the oscillation device 50 as a sound generation
device of a portable telephone has been exemplified. However, the oscillation device 50, an
ultrasonic detection unit that detects an ultrasonic wave emitted from the oscillation device 50
and reflected by the measurement object, and a distance measurement unit that calculates the
distance from the detected ultrasonic wave to the measurement object An electronic device (not
shown) or the like is also feasible.
[0054]
3-a electrode material 3-b piezoelectric material 3-c elastic material 10 piezoelectric element 12
piezoelectric element 20 elastic member 41 first resin member 42 second resin member 45
support 46 lead wire 47 terminal 50 oscillator
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