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DESCRIPTION JP2013165329

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DESCRIPTION JP2013165329
Abstract: In a parametric speaker, an area where an audible sound is demodulated is finely
controlled. A speaker array 10 has a configuration in which a plurality of transducers 100 are
arranged in an array (two-dimensional). However, the plurality of transducers 100 may be
arranged in a one-dimensional manner. The control unit 20 inputs an oscillation signal to each of
the plurality of transducers 100, and causes each of the plurality of transducers 100 to output a
sound wave. The oscillation signal is either a modulation signal for a parametric speaker or a
carrier signal having the same frequency as the modulation signal. Then, the control unit 20
switches which of the modulation signal and the carrier signal is input to the at least one vibrator
100 or whether any signal is not input. [Selected figure] Figure 1
Oscillator apparatus and oscillation method
[0001]
The present invention relates to an oscillation device and an oscillation method that function as
parametric speakers.
[0002]
One of the speakers is a parametric speaker.
A parametric speaker modulates an audio signal into a modulation signal of an ultrasonic band as
described in, for example, Patent Document 1, and demodulates the modulation signal in the
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atmosphere to an audible sound.
[0003]
Unexamined-Japanese-Patent No. 4-123699
[0004]
The characteristic of the parametric speaker is to have high directivity.
However, it has been difficult to finely control the area where the audible sound is demodulated.
[0005]
An object of the present invention is to provide an oscillation device and an oscillation method
which function as a parametric speaker and can finely control an area where an audible sound is
demodulated.
[0006]
According to the present invention, there are provided a plurality of transducers arranged side by
side, and a control means for inputting an oscillation signal to the plurality of transducers and
causing them to oscillate, and the control means comprises: Either a modulation signal for a
speaker or a carrier signal having the same frequency as the modulation signal is input as the
oscillation signal, and either the modulation signal or the carrier signal is input to at least one of
the vibrators. An oscillator is provided which switches whether or not any signal is input.
[0007]
According to the present invention, any one of a modulation signal for a parametric speaker or a
carrier signal having the same frequency as the modulation signal is input to a plurality of
transducers arranged in a row, and at least one of the transducers is On the other hand, there is
provided an oscillation method for controlling an area where an audible sound is generated by
switching which of the modulation signal and the carrier signal is input or not.
[0008]
According to the present invention, it is possible to finely control an area where an audible sound
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is demodulated in a parametric speaker.
[0009]
It is a figure showing composition of an oscillation device concerning a 1st embodiment.
It is a figure for demonstrating that the oscillation apparatus shown in FIG. 1 can control an
audible sound generation area.
It is a figure for demonstrating that the oscillation apparatus shown in FIG. 1 can control an
audible sound generation area.
It is a figure for demonstrating that the oscillation apparatus shown in FIG. 1 can control an
audible sound generation area.
It is a figure for demonstrating that the oscillation apparatus shown in FIG. 1 can control an
audible sound generation area. It is a figure for demonstrating that the oscillation apparatus
shown in FIG. 1 can control an audible sound generation area. It is a figure for demonstrating
that the oscillation apparatus shown in FIG. 1 can control an audible sound generation area. It is
a sectional view showing an example of composition of a vibrator concerning a 2nd embodiment.
It is a figure which shows an example of a structure of the control part which concerns on 2nd
Embodiment. It is a figure showing composition of an oscillation device concerning a 3rd
embodiment.
[0010]
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.
[0011]
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First Embodiment FIG. 1 is a diagram showing a configuration of an oscillation device according
to a first embodiment. This oscillator is used as a parametric speaker. Specifically, this oscillation
device is used, for example, as a sound source of an electronic device (for example, a mobile
phone, a laptop personal computer, a small game machine, etc.).
[0012]
The oscillation device includes a speaker array 10 and a control unit 20. The speaker array 10
has a configuration in which a plurality of transducers 100 are arranged in an array (twodimensional). However, the plurality of transducers 100 may be arranged in a one-dimensional
manner. The control unit 20 inputs an oscillation signal to each of the plurality of transducers
100, and causes each of the plurality of transducers 100 to output a sound wave. The oscillation
signal is either a modulation signal for a parametric speaker or a carrier signal having the same
frequency as the modulation signal. Then, the control unit 20 switches which of the modulation
signal and the carrier signal is input to the at least one vibrator 100 or whether any signal is not
input. Thereby, as described in detail later, it is possible to finely control an area where the
audible sound is demodulated (the audible sound generation area 30 described later).
[0013]
The control unit 20 modulates an audio signal of an audible sound input from the outside to
generate a modulation signal for a parametric speaker. The modulation signal is generated, for
example, by amplitude modulation (AM) modulation, double side band (DSB) modulation, single
side band (SSB) modulation, or frequency modulation (FM) modulation. The control unit 20 also
generates a transport signal.
[0014]
FIGS. 2 to 7 are diagrams for explaining that the oscillation device shown in FIG. 1 can control a
region where audible sound is demodulated. The parametric speaker utilizes the fact that, when
sound waves of two frequencies propagate in the air, the difference frequency of the two
frequencies is newly generated due to the non-linearity of the particle velocity of the sound wave
in the air. Therefore, when the oscillation device shown in FIG. 1 is made to function as a
parametric speaker, a modulation signal is input to one of the vibrators 100 to oscillate a
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modulation wave, and a carrier signal is input from another vibrator 100. It is necessary to
oscillate the carrier wave. These modulated waves and carriers all have directivity because they
have an ultrasonic frequency (for example, 20 kHz or more, preferably 40 kHz or more). Then, an
audible sound appears in a region where the distance from the oscillation device is at a constant
distance (described as a demodulatable area in the drawing) in the region where the modulated
wave and the carrier wave overlap.
[0015]
In the present embodiment, the control unit 20 can switch which one of all modulation signals
and carrier signals is input to any of the transducers 100 or whether any signal is not input.
[0016]
For example, in the example illustrated in FIG. 2, the control unit 20 causes three of the leftmost
three of the nine arranged transducers 100 to function as the carrier oscillation device 104 and
the three on the right as the modulation signal oscillation device 102. It functions as
The control unit 20 inputs the carrier signal of the same output to any of the carrier oscillation
devices 104 and also inputs the modulation signal of the same output to any of the modulation
signal oscillation devices 102. An area where the carrier wave output from the carrier oscillation
element 104 and the modulation wave output from the modulation signal oscillation element
102 overlap is the audible sound generation area 30.
[0017]
On the other hand, in the example shown in FIG. 3, the control unit 20 causes four of the left end
of the nine arranged transducers 100 to function as the carrier oscillation device 104 and the
four on the right side for modulation signals. It functions as the oscillation element 102. In this
case, as compared to the example shown in FIG. 2, the sound pressure of the modulation wave
and the carrier wave is higher, so the width of the area through which the carrier wave travels (ie
directivity angle) and the width of the area ) Is narrower than the example shown in FIG. For this
reason, the audible sound generation area 30 tends to narrow in the direction parallel to the
speaker array 10 as compared with the example shown in FIG. On the other hand, the audible
sound generation area 30 becomes wider in the distance direction from the speaker array 10 as
compared with the example shown in FIG.
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[0018]
Further, in the example shown in FIG. 4, the control unit 20 reduces the number of carrier
oscillation elements 104 by one as compared with FIG. 2. In this case, the audible sound
generation area 30 is narrowed both in the distance from the speaker array 10 and in the
direction parallel to the speaker array 10 as compared with the example shown in FIG.
[0019]
Further, in the example shown in FIG. 5, the control unit 20 shifts the vibrator 100 functioning as
the modulation signal oscillation element 102 to the left by one compared to FIG. Close to). In
this case, the audible sound generation area 30 is wider in the distance from the speaker array
10 and in the direction parallel to the speaker array 10 as compared with the example shown in
FIG.
[0020]
Further, the control unit 20 can control the width of the demodulation possible area by
controlling the amplitudes of the modulation signal and the carrier signal (that is, controlling the
amplification factor of the signal).
[0021]
For example, in the example shown in FIG. 6, the case where the amplitudes of the modulation
signal and the carrier signal are reduced as compared with the example shown in FIG. 3 is shown.
In this case, the demodulation possible area is narrowed in the direction approaching and away
from the speaker array 10, respectively.
[0022]
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The example shown in FIG. 7 shows the case where the amplitudes of the modulation signal and
the carrier signal are increased as compared with the example shown in FIG. In this case, the
demodulation possible area expands in the direction approaching and away from the speaker
array 10, respectively.
[0023]
As described above, according to the present embodiment, the control unit 20 can switch which
of the modulation signal and the carrier signal is input to at least one vibrator 100 or whether
any signal is not input. It is possible to finely control the generation area of the hearing.
[0024]
Further, the control unit 20 can finely control the generation area of the audible sound by
controlling the position and the number of the transducers 100 to which the modulation signal is
input, and the position and the number of the transducers 100 to which the carrier signal is
input. .
[0025]
Second Embodiment The present embodiment is an embodiment in which the configurations of
the vibrator 100 and the control unit 20 are more specific than those of the first embodiment.
[0026]
FIG. 8 is a cross-sectional view showing an example of the configuration of the vibrator 100. As
shown in FIG.
The vibrator 100 according to the present embodiment has a piezoelectric element 150.
The control unit 20 causes the vibrator 100 to oscillate a sound wave by bending and vibrating
the piezoelectric element 150.
[0027]
In detail, the first vibration member 140, the piezoelectric element 150, the second vibration
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member 130, the elastic member 120, and the support portion 110 are provided.
[0028]
The first vibrating member 140 is in the form of a sheet, and vibrates due to the vibration
generated from the piezoelectric element 150.
The first vibrating member 140 also adjusts the fundamental resonant frequency of the
piezoelectric element 150.
The thickness of the first vibrating member 140 is preferably 5 μm or more and 500 μm or
less. Moreover, as for the 1st vibration member 140, 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 first vibrating member 140 is too low or too high, there is a
possibility that the characteristics and the reliability of the mechanical vibrator may be impaired.
The material constituting the first vibrating member 140 is not particularly limited as long as it is
a material having a high elastic modulus with respect to the piezoelectric element 150 which is a
brittle material such as metal or resin, but from the viewpoint of processability and cost Bronze
or stainless steel is preferable.
[0029]
The piezoelectric element 150 is formed of, for example, a piezoelectric ceramic such as PZT.
However, the piezoelectric element 150 may be formed of another piezoelectric material. The
planar shape of the piezoelectric element 150 is smaller than the planar shape of the first
vibrating member 140.
[0030]
The second vibrating member 130 is in the form of a sheet, and is formed of a material whose
rigidity is lower than that of the first vibrating member 140. When the first vibrating member
140 is formed of metal, the second vibrating member 130 is formed of resin. The planar shape of
the second vibrating member 130 is larger than the planar shape of the first vibrating member
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140. The edge of the second vibrating member 130 protrudes from the first vibrating member
140 over the entire circumference.
[0031]
The stacked body of the piezoelectric element 150, the first vibrating member 140, and the
second vibrating member 130 is supported by the support portion 110 via the elastic member
120. The support portion 110 is a frame-shaped member, and holds a laminate of the
piezoelectric element 150, the first vibrating member 140, and the second vibrating member
130 inside in a plan view. Specifically, a recess is formed over the entire circumference of the
inner peripheral surface of the support portion 110, and the elastic material 120 is embedded in
the recess. The elastic material 120 is, for example, a resin. The edge of the second vibrating
member 130 is embedded in the elastic material 120. The stacked body of the piezoelectric
element 150, the first vibrating member 140, and the second vibrating member 130 is disposed
such that the piezoelectric element 150 faces the upper surface side of the support portion 110.
That is, the vibrator 100 oscillates a sound wave on the upper surface side of the support portion
110.
[0032]
The bottom surface of the support portion 110 is closed, so that a closed space is formed by the
second vibrating member 130 and the support portion 110. The closed space is connected to the
outside through a through hole 112 formed in the bottom surface of the support portion 110.
[0033]
In addition, terminals 172 and 174 are provided on the bottom surface of the support portion
110. The terminal 172 is connected to the back electrode of the piezoelectric element 150
through a wire. In the example shown in the figure, the first vibrating member 140 also serves as
the back electrode of the piezoelectric element 150. The terminal 174 is connected to the surface
electrode of the piezoelectric element 150 through a wire. The terminals 172 and 174 are
connected to the control unit 20.
[0034]
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A cone 160 is fixed to the upper surface of the piezoelectric element 150 via an adhesive layer
162. The cone 160 is made of, for example, metal, and is provided to increase the sound wave
output from the vibrator 100.
[0035]
FIG. 9 is a diagram showing a functional configuration of the control unit 20. As shown in FIG.
The control unit 20 includes a modulation signal generation unit 22, a carrier signal generation
unit 24, a plurality of switches 26, and a switching control unit 28.
[0036]
The modulation signal generation unit 22 generates a modulation signal based on an audio signal
input from the outside. The carrier signal generation unit 24 generates a carrier signal. The
modulation signal and the carrier wave preferably have a resonance frequency of a vibrator
including the piezoelectric element 150, the first vibrating member 140, and the second
vibrating member 130, for example, a fundamental resonance frequency.
[0037]
The plurality of switches 26 are connected to different vibrators 100, respectively. Then, when
the switch 26 is switched, it is switched whether the carrier signal is input to the vibrator 100,
the modulation signal is input, or nothing is input. The switching control unit 28 controls the
switch 26. The switch 26 may be a mechanical switch or a transistor.
[0038]
Also according to this embodiment, the same effect as that of the first embodiment can be
obtained. Further, a piezoelectric element 150 is provided as a vibration source of the vibrator
100. Since the piezoelectric element 150 has a high mechanical quality factor Q, it is possible to
output the modulation signal and the carrier wave with high efficiency.
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[0039]
Third Embodiment FIG. 10 is a diagram showing a configuration of an oscillation device
according to a third embodiment. The example shown in this figure is the first or the first except
that the vibrator 100 serving as the modulation signal oscillating element 102 and the vibrator
100 serving as the carrier oscillation element 104 are separate speaker arrays. The configuration
is the same as that of the oscillator shown in the second embodiment. Also according to this
embodiment, the same effect as that of the first or second embodiment can be obtained.
[0040]
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.
[0041]
DESCRIPTION OF SYMBOLS 10 Speaker array 20 Control part 30 Audible sound generation area
22 Modulation signal generation part 24 Carrier signal generation part 26 Switch 28 Switching
control part 100 Vibrator 102 Oscillator for modulation signal 104 Oscillator for carrier
oscillation 110 Support part 112 Through hole 120 Elasticity Material 130 Second vibrating
member 140 First vibrating member 150 Piezoelectric element 160 Cone 162 Adhesive layer
172 terminal 174 terminal
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