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DESCRIPTION JP2012217037

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DESCRIPTION JP2012217037
An object of the present invention is to reduce the power consumption of an electronic device
having an oscillation device. An electronic device 200 includes a plurality of oscillation devices
100 arranged in an array. The oscillation device 100 includes a piezoelectric vibrator 10, a
vibrating member 20 that holds the piezoelectric vibrator 10 on one side, and a support member
30 that holds the vibrating member 20. The two adjacent oscillators 100 have mutually different
resonant frequencies by the fact that the piezoelectric vibrators 10 that they have are made of
different materials. Thus, power consumption of the electronic device having the oscillation
device can be reduced. [Selected figure] Figure 1
Electronics
[0001]
The present invention relates to an electronic device having an oscillation device.
[0002]
As an electroacoustic transducer mounted on an electronic device, there is a piezoelectric
electroacoustic transducer.
The piezoelectric-type electroacoustic transducer generates an oscillation amplitude by using an
expansion and contraction motion generated by applying an electric field to the piezoelectric
vibrator. The piezoelectric electroacoustic transducer does not require a large number of
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members to generate vibration amplitude, and is advantageous for thinning. As a technique
regarding a piezoelectric type electroacoustic transducer, what is described, for example in
patent documents 1-3 is mentioned.
[0003]
The technology described in Patent Document 1 relates to a wide band transducer having a
plurality of electroacoustic transducers, in which the lengths of matching layers of the respective
electroacoustic transducers are made different. The technique described in Patent Document 2 is
to offset the carrier frequency from the resonant frequency to increase the parametric output.
The technique described in Patent Document 3 relates to an acoustic transducer including a layer
having different ratios of piezoelectric material and non-piezoelectric material etc. across the
aperture. Moreover, as a technique regarding a piezoelectric element, there exists a thing of
patent document 4, for example. The technology described in Patent Document 4 is to make the
cross-sectional area of the piezoelectric element different along the ultrasonic wave radiation
direction in a composite piezoelectric body consisting of a piezoelectric element and a dielectric
portion.
[0004]
JP, 2002-44787, A JP, 2003-513576, A JP, 3-113,999, JP, 2004-72755, A
[0005]
In an electronic device having a plurality of oscillating devices arranged in an array, sound waves
output from adjacent oscillating devices may interfere with one another.
In this case, energy loss due to cancellation of sound waves occurs.
[0006]
An object of the present invention is to reduce the power consumption of an electronic device
having an oscillation device.
[0007]
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According to the present invention, the oscillation device includes a plurality of oscillation
devices arranged in an array, wherein the oscillation device includes: a piezoelectric vibrator; a
vibrating member that holds the piezoelectric vibrator on one surface; and a support member
that holds the vibrating member The two adjacent oscillation devices are made of materials
different from each other in the respective piezoelectric vibrators, whereby electronic devices
having different resonance frequencies are provided.
[0008]
According to the present invention, the oscillation device includes a plurality of oscillation
devices arranged in an array, wherein the oscillation device includes: a piezoelectric vibrator; a
vibrating member that holds the piezoelectric vibrator on one surface; and a support member
that holds the vibrating member The two adjacent oscillators have different shapes from each
other in the respective piezoelectric vibrators, so that electronic devices having different
resonance frequencies are provided.
[0009]
According to the present invention, the oscillation device includes a plurality of oscillation
devices arranged in an array, wherein the oscillation device includes: a piezoelectric vibrator; a
vibrating member that holds the piezoelectric vibrator on one surface; and a support member
that holds the vibrating member The two adjacent oscillators have different film thicknesses of
the vibrating members respectively, so that electronic devices having different resonant
frequencies are provided.
[0010]
According to the present invention, power consumption of an electronic device having an
oscillation device can be reduced.
[0011]
FIG. 2 is a cross-sectional view showing the electronic device according to the first embodiment.
It is a top view which shows the electronic device shown in FIG.
It is a sectional view showing an electronic device concerning a 2nd embodiment which is a
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sectional view showing a piezoelectric vibrator shown in FIG.
It is a top view which shows the electronic device shown in FIG.
It is sectional drawing which shows the modification of the electronic device shown in FIG.
It is sectional drawing which shows the electronic device which concerns on 3rd Embodiment.
[0012]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings. In all the drawings, the same components are denoted by the same reference numerals,
and the description thereof will be appropriately omitted.
[0013]
FIG. 1 is a cross-sectional view showing an electronic device 200 according to the first
embodiment. FIG. 2 is a plan view showing the electronic device 200 shown in FIG. 1 and 2 show
a part of the electronic device 200. FIG. An electronic device 200 according to the present
embodiment includes a plurality of oscillation devices 100 arranged in an array. The electronic
device 200 is, for example, a mobile communication terminal such as a mobile phone.
[0014]
The plurality of oscillation devices 100 each include the piezoelectric vibrator 10, the vibration
member 20, and the support member 30. The vibrating member 20 restrains the piezoelectric
vibrator 10 on one side. The support member 30 holds the vibrating member 20. The two
adjacent oscillators 100 have mutually different resonant frequencies by the fact that the
piezoelectric vibrators 10 that they have are made of different materials. Hereinafter, the
configuration of the electronic device 200 will be described in detail.
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[0015]
As shown in FIG. 1, the vibrating member 20 has, for example, a flat plate shape. The vibrating
member 20 is made of a material such as metal or resin having a high elastic modulus with
respect to a ceramic which is a brittle material, and is made of a general-purpose material such as
phosphor bronze or stainless steel. The thickness of the vibrating member 20 is preferably 5 to
500 μm. Moreover, it is preferable that the longitudinal elasticity coefficient of the vibration
member 20 is 1-500 GPa. If the longitudinal elastic modulus of the vibrating member 20 is
excessively low or high, the vibration characteristics and reliability of the oscillator may be
impaired.
[0016]
As shown in FIG. 1, the oscillation device 100 includes an elastic member 22. The elastic member
22 is provided on the other surface opposite to the one surface of the vibrating member 20.
Further, as shown in FIG. 2, the edge of the elastic member 22 is located outside the edge of the
vibrating member 20 in a plan view. The elastic member 22 is made of, for example, a resin
material such as urethane, PET, or polyethylene. The support member 30 supports the vibrating
member 20 via the elastic member 22. The elastic member 22 may be provided, for example,
only on the outer peripheral portion of the vibrating member 20 (not shown).
[0017]
FIG. 3 is a cross-sectional view showing the piezoelectric vibrator 10 shown in FIG. As shown in
FIG. 3, the piezoelectric vibrator 10 has a piezoelectric body 70, an upper electrode 72 and a
lower electrode 74. The piezoelectric body 70 is sandwiched between the upper electrode 72 and
the lower electrode 74. The piezoelectric body 70 is polarized in the thickness direction (vertical
direction in FIG. 3). The piezoelectric vibrator 10 has, for example, a circular shape or an
elliptical shape in a plane direction parallel to one surface of the vibrating member 20. Further,
as shown in FIG. 2, the piezoelectric vibrator 10 can be formed concentrically with the vibrating
member 20 and the elastic member 22.
[0018]
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The piezoelectric body 70 is made of a material having a piezoelectric effect, and is made of, for
example, lead zirconate titanate (PZT) or barium titanate (BaTiO 3) as a material having high
electromechanical conversion efficiency. Two adjacent oscillation devices 100 in the present
embodiment have mutually different resonance frequencies by the fact that the piezoelectric
bodies 70 of the piezoelectric vibrators 10 included in each are made of different materials. In
the present embodiment, for example, the piezoelectric body 70 of the piezoelectric vibrator 10
included in one of the two adjacent oscillating devices 100 is made of PZT, and the piezoelectric
vibrator 10 included in the other oscillating device 100 is The piezoelectric body 70 can be made
of BaTiO 3. As a result, two adjacent oscillators 100 have different resonant frequencies.
[0019]
The thickness of the piezoelectric body 70 is preferably 10 μm to 1 mm. When the thickness is
less than 10 μm, since the piezoelectric body 70 is made of a brittle material, breakage or the
like is likely to occur during handling. On the other hand, when the thickness exceeds 1 mm, the
electric field strength of the piezoelectric body 70 is reduced. This leads to a decrease in energy
conversion efficiency.
[0020]
The upper electrode 72 and the lower electrode 74 are made of a material having electrical
conductivity, such as silver or silver / palladium alloy. Silver is a general purpose material with
low resistance, and is advantageous in terms of manufacturing cost and manufacturing process.
In addition, a silver / palladium alloy is a low resistance material excellent in oxidation resistance
and excellent in reliability. The thickness of the upper electrode 72 and the lower electrode 74 is
preferably 1 to 50 μm. If the thickness is less than 1 μm, uniform molding becomes difficult.
On the other hand, if it exceeds 50 μm, the upper electrode 72 or the lower electrode 74
becomes a constraining surface with respect to the piezoelectric body 70, resulting in a decrease
in energy conversion efficiency.
[0021]
The oscillation device 100 includes a control unit 90 and a signal generation unit 92. The signal
generation unit 92 is connected to the piezoelectric vibrator 10 and generates an electric signal
to be input to the piezoelectric vibrator 10. The control unit 90 is connected to the signal
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generation unit 92, and controls the generation of the signal by the signal generation unit 92.
The control unit 90 controls the generation of the signal of the signal generation unit 92 based
on the information input from the outside, whereby the output of the oscillation device 100 can
be controlled. In the present embodiment, as shown in FIG. 1, the signal generation unit 92 is
connected to each piezoelectric vibrator 10. Then, the control unit 90 can individually control the
outputs of the plurality of oscillation devices 100 via the signal generation unit 92.
[0022]
In the present embodiment, the oscillation device 100 is used as a parametric speaker. When
using the oscillation device 100 as a parametric speaker, the control unit 90 inputs a modulation
signal as a parametric speaker via the signal generation unit 92. In this case, the piezoelectric
vibrator 10 uses a sound wave of 20 kHz or more, for example, 100 kHz as the transport wave of
the signal.
[0023]
The control unit 90 can control the output of the oscillation device 100 so that, for example,
sound waves output from two adjacent oscillation devices 100 have different frequencies. In this
case, since the two adjacent oscillation devices 100 have different resonance frequencies, it is
possible to select the resonance frequency of each oscillation device 100 as the frequency of the
transport wave.
[0024]
Also, the control unit 90 can adjust the output of each oscillation device 100 in consideration of
the frequency of the audible sound to be reproduced and the directivity of the sound wave to be
output.
[0025]
The oscillation device 100 can also be used as a normal speaker or a sound wave sensor.
When the oscillation device 100 is used as a normal speaker, the control unit 90 directly inputs
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an audio signal to the piezoelectric vibrator 10 via the signal generation unit 92. Moreover, when
using the oscillation apparatus 100 as a sound wave sensor, the signal input into the control part
90 is a command signal to the effect of oscillating a sound wave. In this case, the signal
generation unit 92 causes the piezoelectric vibrator 10 to generate a sound wave of the
resonance frequency of the piezoelectric vibrator 10.
[0026]
Next, the effects of the present embodiment will be described. According to the present
embodiment, two adjacent oscillators 100 have mutually different resonant frequencies. That is,
adjustment can be made so that two adjacent oscillation devices 100 output sound waves having
different frequencies from each other, and interference of sound waves output from the two
adjacent oscillation devices 100 can be suppressed. In addition, a sufficient sound pressure level
can be secured by outputting sound waves having frequencies near the respective resonance
frequencies from the oscillation devices 100 having resonance frequencies different from each
other. Thus, according to the electronic device according to the present embodiment, it is
possible to secure a sufficient sound pressure level while suppressing the interference of sound
waves. Therefore, the power consumption of the electronic device can be reduced.
[0027]
Further, according to the present embodiment, two adjacent oscillation devices 100 have
mutually different resonant frequencies by being formed of different materials of the
piezoelectric vibrators 10 respectively. Therefore, the above effect can be obtained without
changing the shape or the like of the piezoelectric vibrator 10. Therefore, it is possible to provide
an electronic device which can be easily manufactured without affecting the design of the
electronic device and can realize low power consumption.
[0028]
The impedance of the piezoelectric vibrator is increased by shifting the frequency of the sound
wave to be output to a high frequency. And in connection with this, the power consumption of an
electronic device increases. On the other hand, the directivity of the sound wave to be output also
becomes high by shifting the frequency to a high frequency. Thus, the reduction of the power
consumption of the electronic device and the improvement of the directivity of the sound wave
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are in a trade-off relationship with each other. According to the present embodiment, the
electronic device 200 includes the oscillation devices 100 having different resonance
frequencies. This enables the output of sound waves in a wide frequency band. For this reason,
the oscillating frequency can be changed in consideration of the directivity matched to the scene
to be used. Therefore, it is possible to realize the power consumption of the electronic device and
the directivity of sound waves in a well-balanced manner.
[0029]
Moreover, according to the present embodiment, the electronic device 200 includes the
oscillation devices 100 having different resonance frequencies. For this reason, it is possible to
reproduce a demodulated sound having a high sound pressure level in a wide band.
[0030]
FIG. 4 is a cross-sectional view showing the electronic device 202 according to the second
embodiment, and corresponds to FIG. 1 in the first embodiment. 5 is a plan view showing the
electronic device 202 shown in FIG. 4 and corresponds to FIG. 2 in the first embodiment. In the
electronic device 202 according to the present embodiment, two adjacent oscillators 100 have
mutually different resonant frequencies because the piezoelectric vibrators 10 respectively have
different shapes. Except for this point, the electronic device 202 according to the present
embodiment has the same configuration as the electronic device 200 according to the first
embodiment.
[0031]
In the present embodiment, as shown in FIG. 4 and FIG. 5, the areas of the piezoelectric vibrators
10 each having two adjacent oscillators 100 are different from each other in a plane horizontal
to one surface of the vibrating member 20. Can be configured. As a result, the piezoelectric
vibrators 10 of the two adjacent oscillation devices 100 have different shapes. Therefore, two
adjacent oscillators 100 have different resonance frequencies. Moreover, each piezoelectric
vibrator 10 can be comprised with the same material.
[0032]
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FIG. 6 is a cross-sectional view showing a modification of the electronic device 202 shown in FIG.
In this modification, as shown in FIG. 6, two adjacent oscillation devices 100 are configured such
that the heights of the piezoelectric vibrators 10 respectively provided in the directions
perpendicular to one surface of the vibrating member 20 are different from each other. Can. As a
result, the piezoelectric vibrators 10 of the two adjacent oscillation devices 100 have different
shapes. Therefore, two adjacent oscillators 100 have different resonance frequencies. In this
case, the area of each of the piezoelectric vibrators 10 in a plane parallel to one surface of the
vibrating member 20 can be the same.
[0033]
Also in the present embodiment, as in the first embodiment, low power consumption of the
electronic device can be realized. Also in the present embodiment, the electronic device 202
includes the oscillation devices 100 having different resonance frequencies. Therefore, the power
consumption of the electronic device and the directivity of the sound wave can be realized in a
well-balanced manner. In addition, it is also possible to reproduce a demodulated sound having a
high sound pressure level in a wide band.
[0034]
FIG. 7 is a cross-sectional view showing the electronic device 204 according to the third
embodiment, and corresponds to FIG. 1 in the first embodiment. In the electronic device 204
according to the present embodiment, two adjacent oscillation devices 100 have mutually
different resonant frequencies due to the vibration members 20 respectively having different film
thicknesses. Except for this point, the electronic device 204 according to the present embodiment
has the same configuration as the electronic device 200 according to the first embodiment.
[0035]
In the present embodiment, as shown in FIG. 7, the piezoelectric vibrators 10 can be configured
to have the same shape. Moreover, each piezoelectric vibrator 10 can be comprised with the
mutually same material.
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[0036]
Also in the present embodiment, as in the first embodiment, low power consumption of the
electronic device can be realized. Also in the present embodiment, the electronic device 204 is
provided with the oscillation devices 100 having different resonance frequencies. Therefore, the
power consumption of the electronic device and the directivity of the sound wave can be realized
in a well-balanced manner. In addition, it is also possible to reproduce a demodulated sound
having a high sound pressure level in a wide band.
[0037]
Although the embodiments of the present invention have been described above with reference to
the drawings, these are merely examples of the present invention, and various configurations
other than the above can also be adopted.
[0038]
DESCRIPTION OF SYMBOLS 10 piezoelectric vibrator 20 vibration member 22 elastic member
30 support member 70 piezoelectric body 72 upper electrode 74 lower electrode 90 control part
92 signal generation part 100 oscillation device 200 electronic device 202 electronic device 204
electronic device
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