JPH06161476

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DESCRIPTION JPH06161476
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
superdirective sound wave output device, and in particular, a superdirective superdirectivity
which functions as an interface of a signal system for outputting a sound wave, between human
and information equipment. The present invention relates to a sound wave output device.
[0002]
2. Description of the Related Art Conventionally, sound wave output devices such as speakers
and earphones, which are means for outputting sound and sound, as one of the interfaces for
signal exchange between human beings and information equipment, together with other types of
interfaces. It has been used in the form of being equipped with information equipment. Such a
sound wave output device is configured to convert energy from an electrical system to an
acoustic system to emit sound, and has different directivity coefficients depending on the
application and type.
[0003]
However, simply installing such a speaker on an information device as in the prior art gives the
operator of the information device the convenience of providing sound as a signal, but the
information device For those other than the operator who is doing other work in the vicinity, the
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voice is rather received as offensive noise or noise, which is both annoying and undesirable. In
addition, when the operator of the information device uses a device such as an earphone that is
directly attached to the ear, another sound may not be heard by the operator.
[0004]
Therefore, in order to solve such problems, it is conceivable to equip the information device with
a parametric speaker according to the conventional idea as a superdirective speaker, but if such a
separate parametric speaker is simply equipped in the information device However, it has not
been shown that the practical realization of how to incorporate and use it even if it is
incorporated into an information device.
[0005]
The object of the present invention is to focus on such conventional problems, and in order to
solve the problems, it is possible to integrate with the information device without increasing the
size of the information device, and the superdirectivity of the parametric speaker It is an object of
the present invention to provide a superdirective sound wave output device that can be
embodied.
[0006]
SUMMARY OF THE INVENTION In order to achieve the above object, according to the present
invention, two sound waves of different frequencies emitted as a fundamental wave from a sound
source are guided into a medium to induce nonlinear interaction, and a beat frequency is
provided. A sound wave output device capable of outputting a secondary sound wave
corresponding to a flat sound source unit that generates at least two or more of the fundamental
waves, and the non-linear interaction by the fundamental waves guided from the sound source
unit It is characterized in that it is made to be transparent by laminating in three layers by a
propagation part consisting of a medium that induces L and an absorption part that can absorb a
fundamental wave element other than the secondary sound wave formed through the
propagation part. It is a thing.
[0007]
According to the present invention, it is possible to absorb a fundamental wave element other
than a secondary acoustic wave, and a propagation part comprising a flat plate-like sound source
unit for generating a fundamental wave, a medium for inducing nonlinear interaction with two
fundamental waves, and Since all the absorption parts are formed by laminating three layers in a
transparent body, the generated secondary sound wave can be regulated in the direction
orthogonal to the flat sound source part, and in particular, it overlaps with the display part of the
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information device. It is possible to provide a sound wave output device having superdirectivity
that is suitable to be configured together.
[0008]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of the
present invention will be described in detail and in detail with reference to the drawings. Prior to
that, the principle of construction of a parametric speaker applied to the present invention will be
described with reference to FIG.
[0009]
Now, as shown in this figure, if two sound waves SW1 and SW2 having different frequencies f1
and f2 respectively from the sound source 10 are emitted toward a specific propagation medium,
these two sound waves SW1 and SW2 interfere with each other. The so-called beats 21 in which
the vibration changes periodically in a strong and weak manner occur due to the interaction.
The frequency of the combined carrier wave in this case is (f1 + f2) / 2, and the frequency of the
amplitude modulation wave 22 corresponding to the beat is represented by (f1-f2) / 2 (where f1>
f2).
Therefore, if the component waveforms in this case are both large-amplitude sound waves that
are sufficiently large, they are gradually distorted as shown in FIG. 2 in the secondary wave
source region 20 as a synthetic secondary waveform and the final result is (f1 -f2). While
generating a sound wave 23 of a corresponding frequency (hereinafter referred to as a difference
sound), it disappears.
[0010]
Such a phenomenon is induced by the nonlinear material of the medium 20A while the sound
waves SW1 and SW2 having two large amplitudes emitted from the sound source 10 are
propagated in the medium 20A constituting the secondary wave source area 20. This is a virtual
sound source of the difference tone 23 of the frequency corresponding to the difference between
the frequencies f1 and f2.
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Now, assuming that the sound waves SW1 and SW2 are called primary waves and the difference
sound 23 is a secondary wave, as long as the influence of the above-mentioned non-linear
interaction between the primary waves SW1 and SW2 continues, the primary waves SW1 and
SW2 The secondary wave sound source area 20 functions as a virtual sound source of the
difference sound 23 until the amplitude of SW2 attenuates to an infinitesimally small amplitude
linear wave.
That is, since a virtual sound source with a very long propagation distance, in other words, a
waveform train with a very long propagation direction is formed in the medium 20A, the
frequency of the difference sound 23 is very sharp even if it may be low. It will have directivity.
[0011]
FIG. 1 shows an embodiment of the present invention to which the above principle is applied.
Here, 1 is a flat plate-shaped sound source unit that generates sound waves of a plurality of
different frequencies, and 2 is a second order for inducing the above-mentioned nonlinear
interaction with the sound wave emitted from the sound source unit 1 An area corresponding to
the sound source area 20 (hereinafter referred to as a propagation section), and 3 are sound
absorbing sections capable of absorbing primary waves not involved in secondary wave
generation among sound waves radiated from the sound source section.
[0012]
Here, the sound source unit 1 is formed of a transparent and piezoelectric material such as a
vinylidene fluoride resin PVDF (polyvinylidene fluoride) copolymer known as an organic polymer
piezoelectric material. In addition, it is preferable that the propagation unit 2 has a property of
inducing a non-linear interaction with sound waves and that it is transparent, for example, silicon
gel or the like as a medium. Furthermore, the sound absorbing unit 3 can be formed of, for
example, an acrylic resin or the like, which has characteristics capable of sufficiently absorbing
the primary wave and is transparent.
[0013]
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Therefore, in the sound wave output unit as shown in FIG. 1, when emitting the sound wave of
the primary wave corresponding to the frequencies f1 and f2 from the sound source unit 1, the
difference (f1-f2) of these frequencies is in the audible range Set to For example, if f1 is 50 KHz
and f2 is 45 KHz, the secondary wave of (f1-f2) is 5 KHz. Now, when the sound wave of the
primary wave is emitted from the sound source unit 1, such primary wave is basically propagated
in the propagation unit 2 with a spread of an angle of 360 °, but at that time the secondary
wave of the difference sound The primary wave remaining in the propagation unit 2 as it is
without contributing to the generation is absorbed by the sound absorbing unit 3. Therefore, no
extra sound is transmitted from the sound absorbing unit 3 to the outside.
[0014]
FIG. 3 shows a circuit configuration according to the present invention, where 100 is a sound
wave output unit with superdirectivity consisting of three layers of the sound source unit 1, the
propagation unit 2 and the sound absorption unit 3 shown in FIG. Reference numeral 110
denotes a drive circuit for driving the sound wave output unit 100, 120 denotes a power supply
unit for supplying drive power to the drive circuit 110, and 130 denotes an oscillator for
generating a sound wave.
[0015]
(A) and (B) of FIG. 4 respectively show the example of a structure of the sound wave output part
by the other Example of this invention. In these (A) and (B), 12 is a propagation part, and the
propagation part 12 is formed in convex lens shape in any case. That is, by making the sound
absorption part side central part of the propagation part 12 into a convex lens shape which is
made to project smoothly, the sound wave which propagates the inside of the propagation part
12 is radiated so that it may concentrate on the central part efficiently, The effect of enhancing
can be obtained. The sound absorbing portion 13 may cover the propagating portion 12 with a
uniform thickness as shown in FIG. 4A, or the outer surface as shown in FIG. 4B. It may be flat.
[0016]
FIG. 5 shows the configuration of a sound source unit according to still another embodiment of
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the present invention. In this embodiment, for example, plus and minus electrodes or earth
electrodes are formed in a zigzag form on one side and the other side of the sound source unit 11
formed of a PVDF polymer or the like which is entirely transparent and has a piezoelectric
property. In the case of this example, two types of sound waves of different frequencies can be
generated between the facing electrodes. Here, 21A and 21B are two plus electrodes 31A and
31B arranged in a staggered arrangement so as to keep a predetermined distance from each
other on one side of the sound source unit 11, for example, the propagation unit side, the other
There are also two negative electrodes arranged in a staggered manner in the same way on the
surface.
[0017]
FIG. 6 shows an example of an information apparatus to which the sound wave output apparatus
of the present invention is applied. Here, 100 is a sound wave output unit, 140 is a display unit
such as a CRT or liquid crystal integrated with the sound wave output unit 100, and 150 is an
information processing unit that performs data processing and data manipulation. An audio
signal processing apparatus 160 sends an audible signal (audio signal) to the sound wave output
unit 100 according to the processing signal from the information processing unit 150, and 170
displays on the display unit 140 according to the processing signal from the information
processing unit 150. Video signal processing apparatus for supplying an image signal.
[0018]
Thus, the ultrasonic wave output unit 100 outputs a superdirectional sound wave with very
limited direction toward the operator occupying the position facing the display unit 140, and
occupies a position different from the operator. The sound and voice from the sound wave output
unit 100 hardly reach other people, and there is no inconvenience, and an interface of sound that
can be exchanged only between the operator and the information device can be provided.
Although the volume and the like can be adjusted with the volume and the like as in the prior art,
it is desirable that the reach distance of the sound be adjusted to a clear vision distance or
approximately twice that distance.
[0019]
Further, in the embodiment described above, the case where two sound waves having different
frequencies are generated from the sound source unit has been described, but the number of
fundamental frequencies is not limited to two, and two or more fundamental frequencies may be
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used. Similarly, it is needless to say that it is possible to generate a secondary wave sound source
by non-linear interaction and to output a superdirective sound wave to the space.
[0020]
As described above, according to the present invention, two sound waves of different frequencies
emitted as a fundamental wave from a sound source are introduced into a medium to induce
nonlinear interaction and correspond to a beat frequency. A sound wave output device capable of
outputting a secondary sound wave, wherein the non-linear interaction is induced by a flat platelike sound source unit generating at least two or more of the fundamental waves, and the
fundamental wave guided from the sound source unit. Since it is made three layers by the
propagation part which consists of media, and the absorption part which can absorb fundamental
wave elements other than the above-mentioned secondary sound wave formed via the
propagation part and made it transparent, it is easy to use information equipment, for example It
becomes possible to incorporate it into the display unit and use it, and the user of the output
voice, for example, in the case of an information device, operates as a sound that is useless to
persons other than the operator without obstructing the operation. Among people It is possible
to provide an interface reaches capable of sound.
In addition, there is no bother of attaching and detaching as in the conventional earphone, and
there is no hindrance to the input of other voices.
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