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JP2012029080

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DESCRIPTION JP2012029080
An oscillation device which functions as a parametric speaker and whose structure can be
simplified. An oscillation device includes a plurality of oscillation units. Each of the oscillators has
a vibrator and is arranged in a matrix. The outputs of the plurality of oscillating units are
controlled by the control unit 50. The control unit 50 is housed inside the housing 102, and
causes the oscillation device 110 to function as a parametric speaker by inputting ultrasonic
oscillation data obtained by modulating audio data in the audible range into the oscillation unit.
The acoustic lens 30 bends the ultrasonic waves oscillated from each of the plurality of
oscillators in a direction to focus them at one point. [Selected figure] Figure 1
Oscillator and electronic device
[0001]
The present invention relates to an oscillator and an electronic device.
[0002]
In recent years, demand for portable terminals such as mobile phones and laptop computers has
been expanding.
In particular, development of thin portable terminals that make audio functions such as
videophone calls, video reproduction, hands-free telephone functions, etc. have a commercial
value has been promoted. Among these developments, the demand for a compact and high-power
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1
electroacoustic transducer is increasing. BACKGROUND ART Conventionally, electrodynamic
electroacoustic transducers are used as electroacoustic transducers in electronic devices such as
mobile phones. This electrodynamic electroacoustic transducer is composed of a permanent
magnet, a voice coil and a vibrating membrane. However, the electrodynamic electroacoustic
transducer has a limit in thinning due to its operation principle and structure. Therefore, it is
expected to use the piezoelectric vibrator as a parametric speaker that is an electroacoustic
transducer.
[0003]
Moreover, although it is not the application as a parametric speaker, attaching an acoustic lens to
the transmission source of an ultrasonic wave is described in patent documents 1-3 when using
an ultrasonic wave as a probe. Among these, the techniques described in Patent Documents 1
and 3 use an acoustic lens to diffuse ultrasonic waves. Further, the technology described in
Patent Document 2 focuses ultrasonic waves linearly by focusing ultrasonic waves oscillated
respectively from a plurality of linearly arranged transmission sources.
[0004]
JP-A-2004-023781 JP-A-2006-334074 JP-B-59-120976
[0005]
One of the demodulation methods of parametric speakers is to demodulate audible sound by
superposing and interfering ultrasonic waves oscillated from sources arranged in a matrix.
If this method is adopted, it is necessary to individually change the oscillation directions of a
plurality of sources, resulting in a complicated structure.
[0006]
An object of the present invention is to provide an oscillator and an electronic device that
function as a parametric speaker and can simplify the structure.
[0007]
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2
According to the present invention, ultrasonic oscillation data in which audio data in the audible
range is modulated is provided to a plurality of oscillating units each having a transducer and
arranged in a matrix, and the plurality of oscillating units. By inputting, a control unit that causes
the plurality of oscillation units to function as a parametric speaker; and a control unit that is
provided opposite to the plurality of oscillation units, and bends in a direction to focus ultrasonic
waves oscillated from each of the plurality of oscillation units. And an acoustic lens system.
[0008]
According to the present invention, it comprises: a housing; and an oscillating device housed
inside the housing, wherein the oscillating device comprises a plurality of oscillations each
having a vibrator and arranged in a matrix. A control unit that causes the plurality of oscillation
units to function as a parametric speaker by inputting ultrasonic oscillation data obtained by
modulating audio data in the audible range to the plurality of oscillation units; and the plurality
of oscillation units An electronic apparatus comprising: an acoustic lens system disposed
opposite to, and bent in a direction to focus ultrasonic waves oscillated from each of the plurality
of oscillators.
[0009]
According to the present invention, it is possible to provide an oscillator and an electronic device
that function as a parametric speaker and can simplify the structure.
[0010]
It is a sectional view showing the composition of the electronic equipment concerning a 1st
embodiment.
It is a top view of an electronic device.
It is sectional drawing which shows the structure of the thickness direction of a piezoelectric
vibrator.
It is a perspective exploded view which shows the structure of the piezoelectric vibrator of the
electronic device which concerns on 2nd Embodiment.
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It is sectional drawing of the electronic device which concerns on 3rd Embodiment.
[0011]
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.
[0012]
First Embodiment FIG. 1 is a cross-sectional view showing a configuration of an electronic device
100 according to a first embodiment. FIG. 2 is a plan view of the electronic device 100. FIG. The
electronic device 100 is, for example, a mobile communication terminal, and includes a housing
102, an oscillation device 110, and a control unit 50. However, the electronic device 100 may be
a laptop personal computer, a small game machine, or the like. The oscillation device 110 is
housed inside the housing 102. The oscillation device 110 includes a plurality of oscillation units.
Each of the oscillators has a vibrator and is arranged in a matrix. The outputs of the plurality of
oscillating units are controlled by the control unit 50. The control unit 50 is housed inside the
housing 102, and causes the oscillation device 110 to function as a parametric speaker by
inputting ultrasonic oscillation data obtained by modulating audio data in the audible range into
the oscillation unit. The housing 102 is provided with a speaker hole 104. The speaker hole 104
faces the oscillation surface of the oscillation device 110 and is closed by the acoustic lens 30 of
the oscillation device 110. The acoustic lens 30 bends the ultrasonic waves oscillated from each
of the plurality of oscillators in a direction to focus them at one point. The details will be
described below.
[0013]
The oscillation device 110 includes a plurality of vibration members 10, a plurality of
piezoelectric vibrators 20, and a support 40. The vibrating member 10 has a sheet shape. The
above-described oscillation unit is configured by a pair of the vibrating member 10 and the
piezoelectric vibrator 20. A main portion of the oscillation device 110 is configured by arranging
the sets of the vibration member 10 and the piezoelectric vibrators 20 in a matrix. The support
40 is a frame-like member, and the inner surface supports the edge of the vibrating member 10.
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The plurality of vibration members 10 are arranged to constitute the same plane.
[0014]
The vibrating member 10 vibrates by the vibration generated from the piezoelectric vibrator 20.
The vibrating member 10 also adjusts the fundamental resonant frequency of the piezoelectric
vibrator 20. The fundamental resonance frequency of the mechanical oscillator depends on the
load weight and the compliance. Since the compliance is mechanical rigidity of the vibrator, by
controlling the rigidity of the vibrating member 10, the fundamental resonant frequency of the
piezoelectric vibrator 20 can be controlled. The thickness of the vibrating member 10 is
preferably 5 μm or more and 500 μm or less. Moreover, as for the vibration member 10, it is
preferable that the longitudinal elasticity coefficient which is a parameter ¦ index which shows
rigidity is 1 Gpa or more and 500 GPa or less. If the rigidity of the vibrating member 10 is too
low or too high, there is a possibility that the characteristics and reliability of the mechanical
vibrator will be impaired. The material constituting the vibration member 10 is not particularly
limited as long as the material has a high elastic modulus with respect to the piezoelectric
vibrator 20 which is a brittle material such as metal or resin, but from the viewpoint of
processability and cost And stainless steel are preferable.
[0015]
In the present embodiment, the piezoelectric vibrator 20 is rectangular, for example, square. The
outer edge of the piezoelectric vibrator 20 is located inside the portion of the vibrating member
10 supported by the support 40. However, the shape of the piezoelectric vibrator 20 is not
limited to a rectangle.
[0016]
The oscillation device further includes a control unit 50 and a signal generation unit 54 as an
oscillation circuit. The signal generation unit 54 generates an electrical signal to be input to the
piezoelectric vibrator 20. The control unit 50 modulates voice data input from the outside to
generate data for ultrasonic oscillation, and inputs the data to the piezoelectric vibrator 20 via
the signal generation unit 54.
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[0017]
The acoustic lens 30 bends the ultrasonic wave, for example, a sound wave having a frequency of
20 kHz or more in nine directions in a focusing direction. In the present embodiment, the
acoustic lens 30 corresponds to the plurality of matrix-shaped oscillating portions described
above with one acoustic lens 30. The acoustic lens 30 is supported at its peripheral portion by
the support 40. In the acoustic lens 30, for example, the surface facing the vibrating member 10
is concave. Preferably, the surface of the acoustic lens 30 facing the outside is flat.
[0018]
FIG. 3 is a cross-sectional view showing the configuration of the piezoelectric vibrator 20 in the
thickness direction. The piezoelectric vibrator 20 has a piezoelectric body 22, an upper surface
electrode 24, and a lower surface electrode 26. The piezoelectric body 22 is polarized in the
thickness direction. The material constituting the piezoelectric body 22 may be either an
inorganic material or an organic material as long as it has a piezoelectric effect. However, a
material having high electromechanical conversion efficiency, such as zirconate titanate (PZT) or
barium titanate (BaTiO3) is preferable. The thickness h of the piezoelectric body 22 is, for
example, 10 μm or more and 1 mm or less. If the thickness h1 is less than 10 μm, there is a
possibility that the piezoelectric vibrator 20 may be broken at the time of manufacturing the
oscillation device. When the thickness h1 is more than 1 mm, the electromechanical conversion
efficiency is too low. Vibration of sufficient magnitude can not be obtained. The reason is that
when the thickness of the piezoelectric vibrator 20 increases, the electric field strength in the
piezoelectric vibrator decreases in inverse proportion. Further, the thicknesses of the
piezoelectric members 22 may be equal to or different from each other.
[0019]
Although the material which comprises the upper surface electrode 24 and the lower surface
electrode 26 is not specifically limited, For example, silver and silver / palladium can be used.
Silver is used as a low-resistance general-purpose electrode material, so it has advantages in
manufacturing process and cost. Since silver / palladium is a low resistance material excellent in
oxidation resistance, it is advantageous from the viewpoint of reliability. Further, the thickness
h2 of the upper surface electrode 24 and the lower surface electrode 26 is not particularly
limited, but it is preferable that the thickness h2 is 1 μm to 50 μm. If the thickness h2 is less
than 1 μm, it is difficult to form the upper surface electrode 24 and the lower surface electrode
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26 uniformly, and as a result, the electromechanical conversion efficiency may be reduced. When
the film thickness of the upper surface electrode 24 and the lower surface electrode 26 exceeds
100 μm, the upper surface electrode 24 and the lower surface electrode 26 become a
constraining surface with respect to the piezoelectric body 22 and there is a possibility that the
energy conversion efficiency is reduced. come.
[0020]
Next, the operation and effects of the present embodiment will be described. In the present
embodiment, an acoustic lens 30 is provided in a portion facing the plurality of oscillating
portions. The acoustic lens 30 bends the ultrasonic waves oscillated from each of the plurality of
oscillators arranged in a matrix in a direction to focus the ultrasonic waves on one point. For this
reason, even if the plurality of vibration members 10 are arranged to constitute the same plane,
the ultrasonic waves oscillated from the plurality of oscillation portions can be interfered with
each other to be demodulated into audible sound. Therefore, the structure of the parametric
speaker can be simplified to reduce the manufacturing cost. In addition, since it is not necessary
to change the directions of the plurality of vibration members 10, the oscillation device 110 can
be thinned.
[0021]
Second Embodiment FIG. 4 is an exploded perspective view showing a configuration of a
piezoelectric vibrator 20 of an electronic device 100 according to a second embodiment. The
electronic device 100 according to the present embodiment has the oscillation according to the
first embodiment except that the piezoelectric vibrator 20 has a structure in which a plurality of
piezoelectric members 22 and electrodes 24 are alternately stacked. It has the same
configuration as the device. The polarization directions of the piezoelectric members 22 are
switched from one layer to another and are staggered.
[0022]
Also in this embodiment, the same effect as that of the first embodiment can be obtained.
Further, since the piezoelectric vibrator 20 has a structure in which the plurality of piezoelectric
bodies 22 and the electrodes 24 are alternately stacked, the amount of expansion and
contraction of the piezoelectric vibrator 20 becomes large. Therefore, the output of the oscillator
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can be increased.
[0023]
Third Embodiment FIG. 5 is a cross-sectional view of an electronic device 100 according to a
third embodiment. The electronic device 100 according to the present embodiment has the same
configuration as the electronic device 100 according to the first embodiment except that the
acoustic lens 30 of the oscillation device 110 is provided with the anti-reflection layer 32.
[0024]
The anti-reflection layer 32 is provided on the surface of the acoustic lens 30 facing the vibrating
member 10, and suppresses the reflection of the ultrasonic wave propagating through the air
when it is incident on the acoustic lens 30. The antireflective layer 32 is made of a material
whose acoustic impedance is between the air and the main body of the acoustic lens 30. In
addition, the acoustic impedance of the material which comprises the acoustic lens 30 is higher
than the acoustic impedance of air.
[0025]
Also according to this embodiment, the same effect as that of the first embodiment can be
obtained. In addition, since the acoustic lens 30 has the anti-reflection layer 32, it is possible to
suppress the reflection of the ultrasound when the ultrasound enters the acoustic lens 30 from
the air.
[0026]
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.
[0027]
DESCRIPTION OF REFERENCE NUMERALS 10 vibration member 20 piezoelectric vibrator 22
piezoelectric body 24 upper surface electrode 26 lower surface electrode 30 acoustic lens 32
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anti-reflection layer 40 support 50 control unit 54 signal generation unit 100 electronic device
102 housing 104 speaker hole 110 oscillation device
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