DESCRIPTION JP2006245730

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DESCRIPTION JP2006245730
An object of the present invention is to provide a superdirective acoustic device that maintains
good sound pressure and sound quality regardless of the type of sound source and the change in
acoustic signal. An integrated value of acoustic information distribution indicating a relationship
between acoustic information based on an acoustic signal from a sound source and a frequency
is within a predetermined unit time in a superdirective acoustic device that emits ultrasonic
waves having directivity. And a frequency band dividing means for dividing the frequency band
of the acoustic signal into a predetermined number based on the frequency value, and an
ultrasonic signal oscillating means for outputting an ultrasonic signal. And modulating the
ultrasonic signal with the divided acoustic signal for each frequency band to obtain a modulated
ultrasonic signal in each frequency band, and a diaphragm based on a predetermined number of
modulated ultrasonic signals. It is configured to have an ultrasonic vibration oscillating means
that oscillates and emits modulated ultrasonic vibration having directivity. [Selected figure]
Figure 1
Superdirectional sound device
[0001]
The present invention relates to a superdirective acoustic device configured to radiate modulated
ultrasonic vibration from a predetermined number of ultrasonic vibration oscillating means, and
more specifically, improve a driving method for the purpose of improving sound pressure and
sound quality. The present invention relates to a superdirective acoustic device.
[0002]
In recent years, the functions of acoustic devices have been diversified, and among them,
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superdirective acoustic devices that can prevent sound leakage to others by forming an audible
sound field in a specific region are beginning to attract attention There is.
[0003]
However, this superdirective acoustic device is an acoustic device in which the sound pressure
and the sound quality of the acoustic vibration to be reproduced are normal, on the principle that
the modulated ultrasonic vibration is demodulated on the transport path to form an audible
sound field. There is a problem that it is extremely low compared to the above, and unnecessary
noise vibration other than acoustic vibration is easily generated.
In particular, this problem is noticeable when an acoustic signal having a large amount of
acoustic information integral value is reproduced as acoustic vibration on the transport path of
one modulated ultrasonic vibration.
[0004]
A superdirective acoustic device 22 shown in FIG. 3 has been proposed as a means for solving
such problems and improving the sound quality and sound pressure of the acoustic vibration to
be reproduced (see, for example, Patent Document 1).
The device configuration and driving method of this superdirective acoustic device 22 will be
described below.
[0005]
The superdirective acoustic device 22 comprises a sound source 1e, an ultrasonic wave signal
generating means 2e, a frequency band dividing means 15e for dividing an acoustic signal 6e
from the sound source 1e into a predetermined number (three in the drawing) frequency bands,
Further, it comprises an ultrasonic vibration oscillation means drive system 9e consisting of a
predetermined number of modulation means 3e to 3g, and ultrasonic vibration oscillation means
4e to 4g connected to the respective modulation means 3e to 3g.
[0006]
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Here, the carrier ultrasonic wave signal 5e generated by the ultrasonic wave signal generating
means 2e is modulated in the modulation means 3e to 3g by the divided acoustic signals 7e to 7g
divided into each frequency band by the frequency band dividing means 15e. Ru.
Then, the modulated modulated ultrasonic signals 8e to 8g are input to the predetermined
number of prepared ultrasonic oscillation means 4e to 4g, and have a driving principle that they
are radiated to the air as modulated ultrasonic vibrations. ing.
[0007]
Also, as shown in FIG. 4, the superdirective acoustic device 22 is radiated from the ultrasonic
vibration oscillating means 4e to 4g based on the modulated ultrasonic signals 8e to 8g obtained
from the ultrasonic vibration oscillating means driving system 9e. The radiation directions and
shapes of the respective ultrasonic vibration oscillation means 4e to 4g are adjusted such that
the transport paths 10e to 10g of the predetermined number of modulated ultrasonic vibrations
overlap in one focusing region 11e.
[0008]
In this superdirective acoustic device 22, by having the above-described device configuration and
driving principle, for example, it is an acoustic signal 6e having many frequency components and
a large amount of acoustic information as shown in FIG. 5 (a). Also, as shown in FIG. 5 (b), this
acoustic signal 6e is used as the divided acoustic signals 7e to 7g of the appropriate acoustic
information integral value, and each modulated ultrasonic signal is divided by the divided
acoustic signals 7e to 7g. After 8e to 8g, they can be distributed and input to the respective
ultrasonic vibration oscillating means 4e to 4g.
[0009]
Then, it is possible to radiate modulated ultrasonic vibration carrying an acoustic signal of an
appropriate acoustic information integral value into the air from each of the ultrasonic vibration
oscillating means 4e to 4g.
[0010]
If the acoustic information integral value of the divided acoustic signals 7e to 7g obtained in this
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manner is the modulated ultrasound vibration appropriately limited, an acoustic signal having a
large amount of acoustic information integral values as described above When 6e is reproduced
as acoustic vibration on the transport path of one modulated ultrasonic vibration, it is possible to
suppress the decrease in sound pressure and sound quality and the generation of unnecessary
noise vibration.
Therefore, it is possible to maintain good sound pressure and sound quality of the acoustic
vibration reproduced in the superdirective sound field region.
[0011]
Then, as shown in FIG. 4, the sound field area formed by the transfer paths 10e to 10g of the
predetermined number of transfer ultrasonic vibrations is integrated into one focusing area 11e,
thereby making the audibility in the focusing area 11e. It is possible to reproduce the acoustic
vibration with the sound quality and the sound pressure maintained well over the entire
frequency band of the area.
[0012]
JP-A-2002-354575 (page 5, FIG. 1)
[0013]
However, in the superdirective acoustic device 22 as described above, although the acoustic
signal 6e having acoustic information over the entire frequency band of the audible area can
always be realized, its function can be sufficiently expressed. In the case of an acoustic signal in
which acoustic information is concentrated in a specific frequency band, or in the case of an
acoustic signal in which the distribution of acoustic information components in the frequency
band significantly changes over time, its function is sufficient. Can not be expressed.
[0014]
For example, as shown in FIG. 6A, assuming that the acoustic signal 6e ′ from the sound source
has acoustic information concentrated on a specific narrow frequency band, the frequency band
division means 15e (see FIG. Even if it has 3), the acoustic information integrated value
distributed to each of the divided acoustic signals 7e 'to 7g' is a divided acoustic signal including
the frequency band as shown in FIG. 6 (b). It becomes extremely many at 7f '.
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On the other hand, it can be seen that the divided acoustic signals 7e 'and 7g' in the frequency
bands other than the divided acoustic signal 7f 'become extremely small.
[0015]
Under such circumstances, among the predetermined number of modulation means 3e to 3g and
the ultrasonic wave oscillation means 4e to 4g constituting the superdirective acoustic device 22,
modulation of a portion to which the divided acoustic signal of the frequency band is assigned
Only the means 3f is driven, and the other modulation means are not driven.
[0016]
That is, this means that these modulation means 3e and 3g are in a state of reproducing nearsilence acoustic vibration that hardly contains acoustic information, and the overall function of
the superdirective acoustic device 22 is improved. It means that it does not play.
[0017]
In this case, only a part of the modulation means 3f to which the divided acoustic signal 7f 'of the
frequency band is allocated is driven, and an ultrasonic sound oscillation field of superdirectivity
is formed only from the ultrasonic vibration oscillation means 4f belonging to the series. In
addition, the total sound pressure of the acoustic vibration to be reproduced is extremely low
compared to a superdirective acoustic device having almost the same size of the entire device
and not using the frequency band dividing means 15e. is there.
[0018]
Further, in the case of modulated ultrasonic vibration on which the divided acoustic signal 7f 'of
the frequency band is placed, the divided acoustic signal 7f' having this large amount of acoustic
information integral value is used as the conveyance path 10f of one conveyance ultrasonic
vibration. 4) Since the signal is to be demodulated simultaneously, even if the range of the
frequency band of the acoustic vibration is narrow, it induces the generation of the noise
pressure and the sound quality as described above and the generation of unnecessary noise
vibration It will be done.
[0019]
Furthermore, even if the frequency band dividing means 15e sets in advance to finely divide in a
specific frequency band, the distribution of acoustic information components in a general
acoustic signal changes with the passage of time. It can not be avoided that time-varying events
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occur such as acoustic information moving to another frequency band and concentrated, or
across the entire audible range.
[0020]
Therefore, it is obvious that such a situation can not be coped with by the frequency band
division means 15e (see FIG. 3) of the conventional superdirective acoustic device 22.
[0021]
Therefore, the present invention aims to solve the above-mentioned drawbacks and to provide a
superdirective acoustic device capable of improving sound pressure and sound quality with
respect to various acoustic signals.
[0022]
In order to achieve the above object, the superdirective acoustic device of the present invention
basically adopts the following configuration.
[0023]
The superdirective acoustic device according to the present invention is a superdirective acoustic
device that emits ultrasonic waves with directivity, and the integral value of the acoustic
information distribution indicating the relationship between the acoustic information based on
the acoustic signal from the sound source and the frequency is A division frequency control
means for calculating frequency values that are substantially equal within a predetermined unit
time; a frequency band division means for dividing a frequency band of an acoustic signal into a
predetermined number based on the frequency values; and outputting an ultrasonic signal
Ultrasonic wave signal oscillating means for modulating, ultrasonic wave signal modulated by the
acoustic signal of each divided frequency band respectively to obtain modulated ultrasonic wave
signal in each frequency band, and a predetermined number of modulated ultrasonic wave
signals And vibration means for vibrating the vibration plate based on the above to oscillate the
modulated ultrasonic vibration having directivity.
[0024]
Further, in the superdirective acoustic device according to the present invention, the number of
the modulation means and the ultrasonic vibration oscillation means described above is the same
as the predetermined number for which the frequency band is divided, It is characterized in that
modulated ultrasonic vibrations carrying acoustic signals in a frequency band are separately
oscillated at sound pressures substantially equal to each other.
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[0025]
According to the present invention, even if the distribution of the acoustic information in the
acoustic signal is biased to an arbitrary frequency band, or even if the distribution fluctuates with
the passage of time, the subject of the appropriate integral of the acoustic information is always
obtained. It has the advantage that the split acoustic signal can be distributed to various means
sequences.
[0026]
Therefore, a divided acoustic signal having an appropriate acoustic information integral value is
distributed and carried as it is to a predetermined number of modulated ultrasonic vibrations,
and is reproduced as acoustic vibration by receiving a demodulation action on the conveyance
path. It becomes.
[0027]
Therefore, the problems such as the sound pressure and the deterioration of the sound quality as
described above and the generation of unnecessary noise and vibration are eliminated, and the
sound pressure and the sound quality are always good even if the acoustic information
distribution of the acoustic signal has bias or fluctuation. It is possible to realize super-directional
audible sound field reproduction with maintaining.
[0028]
First, the device configuration and driving method of the superdirective acoustic device in the
embodiment of the present invention will be described.
FIG. 1 shows a configuration example of a superdirective acoustic device 21 according to the
present invention.
The same components as the background art in the configuration of the present invention will be
described using the same reference numerals.
[0029]
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As shown in the schematic diagram of FIG. 1, the superdirective acoustic device 21 according to
the present invention has a predetermined number of acoustic signals 6a from the sound source
1a and the sound source 1a in a frequency band as in the conventional superdirective acoustic
device. To frequency band dividing means 15a for division, ultrasonic signal generation means
2a, and predetermined number of modulation means 3a to 3c for inputting divided acoustic
signals 7a to 7c together with the carrier ultrasonic signal 5a, and to each modulation means It
has ultrasonic vibration oscillation means 4a-4c connected.
[0030]
Further, the superdirective acoustic device 21 of the present invention divides information
integral values of the acoustic characteristic distribution indicating the relationship between the
acoustic information of the acoustic signal 6a and the frequency so as to be approximately equal
within a predetermined unit time. A division frequency control means 16a for calculating
frequency values is provided, and based on the division control signal 17a outputted by this
division frequency control means, the frequency band division means 15a generates a
predetermined number of acoustic signals 6a (three in the drawing). Have the function of
dividing into
[0031]
Furthermore, the superdirective acoustic device 21 of the present invention inputs the to-bedivided acoustic signals 7a to 7c to the modulation means 3a to 3c prepared in a predetermined
number, and the modulated ultrasonic waves output from the modulation means 3a to 3c. Signals
8a-8c can be input to ultrasonic vibration oscillating means 4a-4c, and modulated ultrasonic
vibrations based on modulated ultrasonic signals 8a-8c with substantially equal sound pressure
can be output from ultrasonic vibration oscillating means 4a-4c. It is supposed to be.
[0032]
In the present embodiment, the configuration of the predetermined number of ultrasonic
vibration oscillation means 4a to 4c is shown in the case where the same number of ultrasonic
transducers of the same type are arranged in the same form.
[0033]
Furthermore, in the superdirective acoustic device 21 according to the present invention, as in
the conventional device, the ultrasonic radiation directions of the ultrasonic vibration oscillating
means 4a to 4c are focused so as to form one overlapping region. It is made to become.
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[0034]
Next, the functions and effects of the superdirective acoustic device 21 of the present invention
will be described.
[0035]
As described above, superdirective acoustic device 21 has division frequency control means 16a
for controlling the frequency band for dividing acoustic signal 6a, unlike superdirective acoustic
device 22 in the background art of FIG. ing.
[0036]
The division frequency control means 16a detects temporal variation in acoustic information
distribution characteristics of the frequency and acoustic information in the acoustic signal 6a
output from the sound source 1a every predetermined unit time, and based on the detection
result, predetermined It has a function of repeatedly calculating the frequency value to be
divided for each unit time so that the acoustic information integral values in the plurality of
divided acoustic signals 7a to 7c become substantially equal to each other.
[0037]
Furthermore, the division frequency control means 16a has a function of repeatedly controlling
the frequency band division processing performed by the frequency band division means 15a for
each unit time by the division control signal 17a carrying information of the calculated division
frequency value. have.
[0038]
By having such a function, the acoustic information distribution characteristic in the acoustic
signal 6a has acoustic information concentrated on a specific narrow frequency band, as in the
case of the acoustic signal 6e 'in FIG. 6 (a). Even if there is a division frequency value (arrows in
FIG. 2) for equally dividing the total amount of the acoustic information integral value into a
predetermined number is sequentially calculated for each unit time, and division based on this
division frequency value The processing is performed via the frequency band dividing means
15a, and it becomes possible to generate divided acoustic signals 7a 'to 7c' having integral values
of acoustic information substantially equal to each other.
[0039]
In this manner, as shown in FIG. 2, the divided acoustic signals 7a 'to 7c' having acoustic
information integral values that are always appropriately limited by being approximately equal to
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each other and thus dispersed into a predetermined number , Modulation means 3a to 3c can be
put on modulated ultrasonic signals 8a 'to 8c'.
[0040]
In the superdirective acoustic device 21 according to the present invention, the predetermined
number of modulated ultrasonic vibrations are emitted from the predetermined number of
ultrasonic vibration oscillating means 4a to 4c with substantially the same sound pressure. The
modulated ultrasonic vibrations emitted from the vibration oscillating means 4a to 4c are
radiated into the air while carrying the divided acoustic signals 7a 'to 7c' of the acoustic
information integral values which are substantially equal and appropriately limited to each other
as described above. It will be done.
[0041]
Here, since the acoustic information integral value included in each of the divided acoustic
signals 7a 'to 7c' is appropriately limited, the divided acoustic signals 7a to 7c 'are those of the
modulated ultrasonic vibration. In the process of receiving the demodulation action on the
conveyance path and generating the corresponding acoustic vibration, the conveyance path of
one modulated ultrasonic vibration of the acoustic signal having a large amount of acoustic
information integral value as described above. It is possible to avoid the situation of
demodulation above.
[0042]
In general, the principle of the superdirective acoustic device that the acoustic signal on the
modulated ultrasonic vibration is demodulated to become an acoustic vibration and an audible
sound field is formed is a complex physics called nonlinear wave effect in the propagation
medium of ultrasonic waves. It is largely due to the nature of nature.
[0043]
Therefore, when the acoustic information having a large amount of acoustic information integral
values is directly demodulated on the transport path of one modulated ultrasonic vibration, an
unforeseen interaction depending on this property appears remarkably, and the demodulation
efficiency is It has to cause a marked decline.
[0044]
Then, due to the influence of the reduction in the demodulation efficiency, the sound pressure
and the sound quality of the generated acoustic vibration and the noise vibration are generated.
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[0045]
However, in the superdirective acoustic device 21 according to the present invention, it is
possible to demodulate an acoustic signal having a large amount of acoustic information integral
values on the transport path of one modulated ultrasonic vibration by the function of the division
frequency control means 16a. Even if the acoustic information is concentrated in a specific
narrow frequency band, as in the case of the acoustic signal 6e 'in FIG. Can be prevented.
[0046]
In this way, it is possible to suppress the decrease in sound pressure and sound quality of the
acoustic vibration to be reproduced and unnecessary noise vibration.
Therefore, it is possible to maintain good sound pressure and sound quality as a superdirective
acoustic device.
[0047]
Also, as in the conventional superdirective sound device 22, the superdirective sound device 21
according to the present invention combines the sound field area formed by the predetermined
number of transfer ultrasonic vibration transfer paths into one focusing area. Because of this, in
the focusing area, it becomes possible to reproduce the acoustic vibration with the sound quality
and the sound pressure being well maintained over the entire frequency band of the audible area.
[0048]
Further, in addition to this, in the superdirective acoustic device 21 according to the present
invention, since it is driven by the modulated ultrasonic signals 8a to 8c modulated by the
divided acoustic signals 7a to 7c of appropriate acoustic information integral values. The
frequency-related vibration load applied to one of the ultrasonic vibration oscillating means 4a to
4c is reduced.
[0049]
Therefore, it is possible to suppress split resonance which is likely to occur due to overload of
frequency-like vibration, and to make it difficult to induce unnecessary noise and vibration
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caused by the split resonance.
[0050]
Furthermore, in the superdirective acoustic device 21 according to the present invention, in view
of the function of calculating the division frequency value sequentially every unit time, if this unit
time is set short, the acoustic signal 6a fluctuates remarkably with time. Even in the case of
having such acoustic information, it is possible to radiate modulated ultrasonic vibration carrying
an acoustic signal of almost the same amount of acoustic information into the air.
[0051]
Therefore, regardless of the type of the sound source 1a and the variety of the acoustic signal 6a
from there, it is possible to form a superdirective sound field area while maintaining stable sound
pressure and sound quality at all times.
[0052]
It is the schematic which shows the structure of the super-directional sound apparatus of this
invention.
It is a figure which shows an example of the acoustic information distribution characteristic
which the to-be-divided acoustic signal in the superdirective acoustic apparatus of this invention
has.
It is the schematic which shows the structural example of the conventional super-directional
sound apparatus.
FIG. 8 is a schematic view showing the arrangement and function of ultrasonic vibration
radiation means in a conventional superdirective acoustic device.
It is a figure which shows an example of the acoustic information distribution characteristic
which the acoustic signal in the conventional superdirective acoustic apparatus has, and the
acoustic information distribution characteristic which a to-be-divided acoustic signal has.
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It is a figure which shows the acoustic information distribution characteristic which the acoustic
signal in the conventional superdirective acoustic apparatus has, and the other example of the
acoustic information distribution characteristic which a to-be-divided acoustic signal has.
Explanation of sign
[0053]
1a, 1e Sound source 2a, 2e Ultrasonic signal generating means 3a to 3c, 3e to 3g Modulating
means 4a to 4c, 4e to 4g Ultrasonic vibration oscillating means 5a, 5e Conveyed ultrasonic signal
6a, 6e, 6e 'Acoustic signal 7a to 7c, 7e to 7g, 7a 'to 7c', 7e 'to 7g' acoustic signals to be divided
8a to 8c, 8e to 8g, 8a 'to 8c' modulated ultrasonic signals 9a, 9e ultrasonic vibration means
driving system 10e 10g Carrier Path 11e Focusing Region 15a, 15e Frequency Band Division
Means 16a Division Frequency Control Means 17a Division Control Signal 21, 22 Superdirective
Acoustic Device
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