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JP2012019334

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DESCRIPTION JP2012019334
An object of the present invention is to increase the amount of hardware of a signal processing
system and an amplifier even if the number of speakers in an acoustic system is increased.
SOLUTION: Amplifiers 1a to 8a are connected to two positive and negative terminals of each of a
plurality of main speakers 1m to 8m constituting an array speaker, and they are respectively
bridge-driven. The auxiliary speakers 1s to 7s for interpolating the main speakers 1m to 8m are
respectively disposed between the main speakers 1m to 8m, and the positive and negative
electrodes of the auxiliary speakers 1s to 7s are the same poles of two adjacent main speakers
1m to 8m Connect to the terminal of One sub-speaker receives an average value of signals given
to two adjacent main speakers, and the one sub-speaker interpolates wavefronts emitted from the
two adjacent main speakers. [Selected figure] Figure 4
Sound system
[0001]
The present invention relates to acoustic systems.
[0002]
Humans grasp the acoustic space by the difference in the size of the sound input to the two ears
and the time difference.
A method of expressing a sound space with two speakers on the left and right sides by utilizing
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1
this, that is, stereo recording is generally used. In this acoustic system, a method is used in which
the sound pressure of the sound radiated from the left and right speakers is differentiated to
make it appear as if the sound is coming from the position between the speakers, that is,
panning. In addition, a method is also used to obtain the same effect by using the time difference
to reach the microphones placed at intervals.
[0003]
However, the sound emitted from the left and right speakers is attenuated according to the
distance, and a difference occurs in the propagation time of those sounds, so that the sound from
the left and right speakers is sounded according to the position of the listener. There are
pressure differences and time differences. Therefore, the position where the intended panning
effect can be obtained is only on the central line equidistant from the two left and right speakers
installed, and the listener who is listening to the sound at other positions is closer to the listener
It sounds as if sound is emitted from the speaker in position.
[0004]
As a method for solving this problem, for example, Non-Patent Document 1 describes an acoustic
system that synthesizes the wave front of sound using an array speaker by the WFS (Wave Field
Synthesis) technology. The WFS technology uses an array speaker in which a plurality of
speakers are arranged in a row, and synthesizes the wave front of the sound by superimposing
the sounds radiated from the individual speakers and makes the sound source position
perceivable at the center point of the wave front It is a technology. Since the WFS technology is a
technology for reproducing the wave front of sound itself, the sound source can be perceived in a
wide range of intended positions. Here, the central point of the wave front of the sound
generated from the array speaker is called a virtual sound source.
[0005]
The plurality of speakers constituting the array speaker can reproduce the wave front of high
frequency sound as the installation interval is narrower, while the wider the installation width of
the array speaker, the wider the space in which the wave front of sound can be reproduced. The
aperture diameter of the speakers included in the array speaker is physically equal to or less than
the installation interval of the speakers, so in order to realize an acoustic system that reproduces
09-05-2019
2
the wave front of high frequency sound, the aperture diameter of each speaker must be reduced.
Do not get. On the other hand, the aperture of the speaker is often restricted due to the
installation conditions. In particular, in the case of incorporating a speaker into a television, in
order to make the presence of the speaker inconspicuous, the area is reduced by shortening the
height or width of the speaker, and using a small-aperture speaker corresponding to the short
side Is often taken. As another reason, in order to reduce the cost of the entire sound system
including the signal processing unit, the installation intervals of the speakers may be wide and a
speaker with a relatively small aperture may be selected.
[0006]
However, in the case of a small-aperture speaker, there is a limit to the sound pressure obtained
with a finite diaphragm amplitude because the diaphragm area is small. Therefore, generally
speaking, a speaker with a small aperture can not generate high sound pressure, and the
reproduction frequency band also has problems in acoustic characteristics such as insufficient
bass. In addition, the size of the diaphragm amplitude itself is also smaller than the vibration
amplitude width itself of the speaker having a large aperture due to its structure. Although it is
effective to increase the diaphragm area to obtain high sound pressure, if there is any restriction
that the aperture of the speaker can not be increased, connect multiple speakers in parallel or in
series to obtain sufficient sound pressure. A method is taken to drive a plurality of speakers with
the same signal and to equivalently increase the diaphragm area. However, when a plurality of
speakers are driven by the same signal, the radiation waves from the speakers interfere with
each other to increase the directivity of the sound wave. Since the array loudspeakers synthesize
the wave front of sound by superimposing the sound radiated from the individual loudspeakers,
it is appropriate to make the radiation characteristic of each loudspeaker omnidirectional.
Therefore, driving a plurality of speakers with the same signal causes disturbance of the wave
front of sound, which hinders achieving the original function of the array speaker. On the other
hand, in order to expand the reproduction frequency band on the low-pitched side, it is effective
to increase the aperture of the speaker, but the same problem arises and it is often not realistic.
[0007]
Further, in the case of an array speaker, there is a problem that a listener approaching an array
speaker perceives the sound source at the position of the speaker near him if the distance
between a plurality of speakers constituting the array speaker is wide. This is because the
curvature of the actually emitted wavefront is smaller than the wavefront to be reproduced. In
WFS, wavefronts are reproduced by superposing wavefronts emitted from individual speakers,
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but wavefronts can not be reproduced smoothly without a sufficient speaker density to
superpose wavefronts. In other words, in order to reproduce the wavefront smoothly, it is
necessary to narrow the speaker spacing to secure a sufficient speaker density. To this end, it is
conceivable to add a speaker that complements the wavefront emitted from the speaker.
[0008]
To summarize the above, in order to reproduce higher frequency sound in a wider range as an
acoustic system using array speakers, it is necessary to install small diameter speakers as close
as possible and as many as possible, and to control those speakers is there. However, in order to
obtain high sound pressure for low frequency sounds, it is necessary to incorporate as many
loudspeakers as possible as possible in the acoustic system as possible. As a method for solving
the problem caused by the relationship between the size of the aperture of the speaker and the
wide and narrow frequency bands, for example, Patent Document 1 discloses an array speaker by
combining a plurality of speakers having different apertures for each frequency band. A device
has been described which has been configured and the frequency of the sound has been
broadened.
[0009]
JP, 2006-67301, A
[0010]
Berghout, De Bries, D. de Vries, and P. Vogel, "Acoustic control by wave field synthesis"
(Netherlands), 93 (5) edition, Journal Of the Acoustical Society of America (J. Acoust.
Soc), May 1993, p. 2764-2778.
[0011]
However, in the device described in Patent Document 1, signal processing devices corresponding
to a plurality of speakers constituting an array speaker and amplifiers for driving the speakers
are required as many as the number of speakers, and the hardware of the signal processing
devices and amplifiers The volume increases and the cost of building the acoustic system
increases.
09-05-2019
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[0012]
Moreover, when using a small diameter speaker by a certain restriction in constructing an
acoustic system, the diaphragm area can be equivalently enlarged by narrowing the installation
interval of those speakers, and thereby the output sound pressure of the speaker can be
increased. .
However, in order to increase the diaphragm area, it is necessary to increase the number of small
diameter speakers, and accordingly, the number of signal processing system devices and
amplifiers increases, the amount of hardware of the acoustic system increases, and the cost of
constructing the acoustic system Increases.
[0013]
Therefore, the present invention has been made in view of such circumstances, and the purpose
thereof is that, even if the number of loudspeakers is increased in order to interpolate the
wavefront radiated from the loudspeaker in the acoustic system, An object of the present
invention is to provide an acoustic system which does not bring about an increase in the amount
of hardware of signal processing system equipment and amplifiers involved.
[0014]
An audio system according to the present invention is an audio system provided with an array
speaker including at least three speakers, the two input terminals for inputting signals
corresponding to one first speaker and two second speakers adjacent to each other, And a
driving device for driving the two second speakers based on signals input from two input
terminals, wherein positive terminals of the two second speakers are two corresponding to the
two second speakers. The negative terminal of each of the two second speakers is connected to
the positive terminal of the drive unit, and the negative terminal of each of the two second
speakers is connected to the negative terminals of two drive units corresponding to the two
second speakers. The positive electrode terminal and the negative electrode terminal included in
each of the two second speakers adjacent to the one first speaker include the positive electrode
terminal and the other second speaker of any one of the second speakers. Ca, characterized in
that it is the connection to the negative terminal with the.
[0015]
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5
In the present invention, with respect to a speaker group connected to one signal processing
system and one amplifier system, another speaker group is provided at a position to interpolate
between the systems, and the speaker group larger than the number of input signals is provided.
From the speakers connected to one system by applying the average value between the systems
to the other speaker group without increasing the hardware amount of the signal processing
system and the amplifier even when driving the The emitted wavefront can be interpolated.
[0016]
An audio system according to the present invention is an audio system provided with an array
speaker including at least three speakers, the two input terminals for inputting signals
corresponding to one first speaker and two second speakers adjacent to each other, Between a
drive device for driving the array speaker based on a signal input from an input terminal, and
any one terminal of either one of the two second speakers and an input terminal corresponding
to the terminal; Or a circuit interposed between the other terminal of the other second speaker
and the input terminal corresponding to the terminal, and inverting the phase of one of the
signals input to the two input terminals. The positive terminal and the negative terminal of the
one first speaker have one second speaker of the two second speakers adjacent to the one first
speaker. Wherein the positive terminal and the other second speakers are each connected to the
negative terminal with the.
[0017]
In the present invention, with respect to a speaker group connected to one signal processing
system and one amplifier system, another speaker group is provided at a position to interpolate
between the systems, and the speaker group larger than the number of input signals is provided.
From the speakers connected in one system by applying the addition value between the systems
to the other speaker group without increasing the hardware amount of the signal processing
system and the amplifier even when driving the The emitted wavefront can be interpolated.
[0018]
In the sound system of the present invention, the one first speaker is equidistant from two
second speakers adjacent to the one first speaker.
[0019]
In the present invention, it is possible to reduce the error of the wave front radiated from the
speaker of another system by installing one speaker of another system at the same distance from
two speaker groups included in one system. it can.
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[0020]
The acoustic system according to the present invention is characterized in that the one first
speaker has an impedance four times that of the two second speakers adjacent to the one first
speaker.
[0021]
In the present invention, when the same signal is input to each input terminal, by setting the
impedance of one speaker to four times the impedance of two speakers adjacent to the one
speaker, Power supplied to each of the one connected speaker and the two speakers adjacent to
the one speaker can be aligned.
[0022]
An acoustic system according to the present invention is an acoustic system provided with an
array speaker including at least three speakers, wherein a plurality of second speakers arranged
in a row and a row different from the plurality of second speakers are provided. Of two or more
first speakers smaller than the number of the plurality of second speakers, and two
corresponding second speakers adjacent to one first speaker. A terminal, and a driving device for
driving the two second speakers based on signals input from the two input terminals, wherein
positive terminals of the two second speakers are the two second speakers. The negative terminal
of each of the two second speakers is connected to the positive terminal of the corresponding
two drive units, and the negative terminal of each of the two second speakers is connected to the
negative terminals of the two drive units corresponding to the two second speakers. The positive
terminal and the negative terminal of the one first speaker are the positive terminal and the other
of the second speaker of either one of the two second speakers adjacent to the one first speaker.
It is characterized in that each is connected to the negative electrode terminal which it has.
[0023]
In the present invention, with respect to a single speaker group connected to one signal
processing system and one amplifier system, another speaker group is separated from the one
speaker group at a position to interpolate between the systems. Even when the speaker group is
provided in the column of and drives more speaker groups than the number of input signals, the
average value between the systems is calculated without using the hardware amount of the
signal processing system and the amplifier. The wave front emitted from the speaker group of
one system can be interpolated by applying the voltage to.
[0024]
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7
An acoustic system according to the present invention is an acoustic system provided with an
array speaker including at least three speakers, wherein a plurality of second speakers arranged
in a row and a row different from the plurality of second speakers are provided. And one or more
first speakers smaller than the number of the plurality of second speakers, and input signals
corresponding to one first speaker and two adjacent second speakers, respectively. Two input
terminals, a drive device for driving the array speaker based on a signal input from the input
terminal, and a positive electrode terminal included in one of the two second speakers or the
other second speaker And a circuit interposed between any one of the negative terminals and
inverting the phase of the signal input to the two input terminals, wherein the positive terminal
of the one first speaker is included. And the negative electrode terminal is connected to the
positive electrode terminal of one of the two second speakers adjacent to the one first speaker
and the negative electrode terminal of the other second speaker. Do.
[0025]
In the present invention, with respect to a single speaker group connected to one signal
processing system and one amplifier system, another speaker group is separated from the one
speaker group at a position to interpolate between the systems. Even when the number of
speaker groups provided in the column of and driving more speaker groups than the number of
input signals is increased, the addition value between the systems is not increased in the other
column without increasing the hardware amount of the signal processing system and the
amplifier. By applying the voltage to the speaker group, it is possible to interpolate the wavefront
emitted from the one speaker group.
[0026]
In the sound system of the present invention, the two second speakers connected to the first
speaker and adjacent to the first speaker are characterized by being equidistant from the first
speaker.
[0027]
In the present invention, a speaker group arranged in two rows is provided by installing another
speaker in another line at the same distance from one row of two speaker groups included in one
system. It is possible to reduce the error of the wavefront radiated from the speaker of the
different system.
[0028]
According to the present invention, for example, an audio system can be realized with a signal
processing system for eight channels and an amplifier for eight channels for 15 speakers, and
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the amount of hardware of the signal processing system etc. and the amplifier can be increased.
Even if it does not, the effect that the speaker which interpolates a waveform can be added is
acquired.
[0029]
It is an explanatory view showing an example of appearance of an array speaker.
It is explanatory drawing which shows a virtual sound source position and the position of an
array speaker typically.
It is a block diagram showing the example of whole composition of an acoustic system.
FIG. 2 is a block diagram showing an example of an entire configuration of an array speaker and
an array speaker driving unit according to Embodiment 1.
It is explanatory drawing which shows an example of the positional relationship of an array
speaker and a virtual sound source.
It is explanatory drawing which shows various waveforms when it assumes radiating ¦ emitting a
100-Hz sine wave from a virtual sound source.
It is explanatory drawing which shows the example of an external appearance of another array
speaker.
It is explanatory drawing which shows an example of the positional relationship of an array
speaker and a virtual sound source.
It is a block diagram showing an example of the whole composition of the array speaker at the
time of carrying out band restriction to the frequency of the signal given to an auxiliary speaker,
and an array speaker drive part.
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9
FIG. 7 is a block diagram showing an example of the overall configuration of an array speaker
and an array speaker driving unit according to a second embodiment.
It is a block diagram showing an example of the whole composition of the array speaker at the
time of carrying out band restriction to the frequency of the signal given to an auxiliary speaker,
and an array speaker drive part.
[0030]
Embodiments will be specifically described below with reference to the drawings.
First Embodiment FIG. 1 is an explanatory view showing an example of the appearance of an
array speaker.
In FIG. 1, the array speaker 1 includes main speakers (first speakers) 1 m to 8 m and sub
speakers (second speakers) 1 s to 7 s.
The main speakers 1m to 8m and the sub-speakers 2s to 7s are alternately installed on the baffle
plate 1b on the front of the array speaker 1.
That is, the array speaker 1 is arranged in the order of 1 m, 1 s, 2 s, 2 m, 2 s, 3 m, 3 s, 4 m, 4 m,
5 m, 5 s, 6 m, 6 s, 7 m, 7 s, 8 m from the left with respect to the front of the housing Each
speaker is arranged.
[0031]
The main speakers 1m to 8m are driven by the input signal, and the sub speakers 1s to 7s are
driven by the interpolation signal.
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Details of the input signal and the interpolation signal will be described later.
[0032]
FIG. 2 is an explanatory view schematically showing the virtual sound source position and the
position of the array speaker.
In FIG. 2, a stage and a listening seat are provided on both sides of the array speaker 1, a virtual
sound source A1 is installed on the stage, and listeners B1 to B3 are installed on the listening
seat. AL1 indicates the position of the virtual sound source A1. According to the WFS, the
listeners B1 to B3 are as if the sound source is at the position of the virtual sound source A1 by
reproducing the wave front of the sound that the speakers 1m to 8m and 1s to 7s constituting
the array speaker 1 spread from the virtual sound source A1. It can be perceived as if it exists.
[0033]
FIG. 3 is a block diagram showing an example of the overall configuration of the acoustic system.
In summary, the acoustic system includes k microphones 11 to 1 k, a wavefront synthesis signal
processing unit 9, an amplification unit 4, and an array speaker 1. The wavefront synthesis signal
processing unit 9 includes a level adjustment unit 5, a control unit 6, a position information
holding unit 7, an operation unit 8, and a signal processing unit 3. Moreover, the array speaker 1
is comprised from 15 speaker 1 m-8 m and 1 s-7 s. Here, k is an integer of 1 or more.
[0034]
The level adjustment unit 5 includes k level adjustment modules 51 to 5k. The signal processing
unit 3 includes k × 8 delay units, variable gain amplifiers 311 to 3k8, and eight adders 711 to
718. The level adjustment module 51 amplifies the audio signal input from the microphone 11
and then supplies the amplified signal to the eight delay units and variable gain amplifiers 311 to
318 as a first-system signal. The level adjustment module 52 amplifies the audio signal input
from the microphone 12 and then supplies the amplified signal as a second system signal to
eight delayers and variable gain amplifiers 321 to 328. The level adjustment module 5k amplifies
the audio signal input from the microphone 1k and then supplies it to the eight delayers and
variable gain amplifiers 3k1 to 3k8 as a k-th system signal. The delayer and variable gain
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amplifiers 311 to 318 delay the signal of the first system and perform variable gain
amplification. Also, the delayer and variable gain amplifiers 321 to 328 delay the signal of the
second system and perform variable gain amplification. The delayer and variable gain amplifiers
3k1 to 3k8 delay the signal of the k-th system and perform variable gain amplification. Thus, the
delay unit and variable gain amplifiers 311 to 318, 321 to 328,..., 3k1 to 3k8 respectively delay
the signals of the first system to the k system and perform variable gain amplification, but the
delay amount thereof The amplification factor is calculated by the control unit 6 described later.
The delay unit and variable gain amplifiers 311 to 318, 321 to 328,..., 3k1 to 3k8 individually
delay the signals of the first system to the k system according to the delay amount and
amplification factor calculated by the control unit 6. , Variable gain amplification.
[0035]
Thus, the signals of the first to k-th systems corresponding to the microphones 11 to 1 k are
delayed by the delay units and variable gain amplifiers 311 to 318, 321 to 328, ..., 3k1 to 3k8,
Variable gain amplification. The delay and variable gain amplifiers 311 to 318, 321 to 328,...,
3k1 to 3k8 The signals delayed and variable gain amplified are added by the adders 711 to 712,
and the first to eighth channels of It is separated into signals. Then, the separated first to eighth
channel signals are applied to the amplification unit 4.
[0036]
The adders 711 to 712 will be described in more detail. The adder 711 adds the output signals
of the delay unit and the variable gain amplifiers 311 to 3k1 and supplies the result to the
amplification unit 4 as a signal of the first channel. The adder 712 adds the output signals of the
delay and variable gain amplifiers 312 to 3k2 and supplies the result to the amplification unit 4
as a signal of the second channel. The adder 718 adds the output signals of the delay and
variable gain amplifiers 318 to 3k8 and supplies the result to the amplifier 4 as a signal of the
eighth channel. Thus, the signal processing unit 3 supplies the signals of the first to eighth
channels to the amplification unit 4.
[0037]
The amplification unit 4 has an array speaker drive unit (drive device) described later. The array
speaker driving unit amplifies the input first to eighth channel signals, and applies the amplified
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signals to the corresponding main speakers 1m to 8m and the auxiliary speakers 1s to 7s. Then,
the main speakers 1m to 8m and the sub-speakers 1s to 8s emit a wave front of sound based on
the signal given from the array speaker driving unit.
[0038]
The operation unit 8 is an operation device for the operator to operate the sound system, and
includes a position information input unit 81 and a volume adjustment unit 82. The position
information input unit 81 inputs position information including virtual sound source positions
inputted by the operator and positions of the speakers 1m to 8m and 1s to 7s constituting the
array speaker 1. The position information holding unit 7 gives the position information received
from the operation unit 8 to the control unit 6. The volume adjuster 82 gives amplification
factors to each of the level adjustment modules 51 to 5k according to the operation by the
operator so that each audio signal is loudened to the listening seat with an appropriate volume
and volume balance. .
[0039]
The control unit 6 calculates the delay amount and amplification factor according to the distance,
and the delay units in the signal processing unit 3 provided corresponding to the speakers 1m to
8m and 1s to 7s constituting the array speaker 1 and The delay amount td and the amplification
factor G obtained by calculation are set in the variable gain amplifiers 311 to 312, 321 to 328, ...,
3k1 to 3k8. Assuming that the distance between the virtual sound source A1 and each of the
speakers 1m to 8m and 1s to 7s is d, the delay amount td set in the delay unit and the
amplification factor G set in the variable gain amplifier are calculated according to the following
equation . Delay amount td = d / cc is the speed of sound amplification factor G = d <r> r is the
distance attenuation constant (0> r> -2) As described above, the signal processing unit 3
corresponds to, for example, the virtual sound source A1. The input audio signal 11 is subjected
to processing based on the delay amount and amplification factor, and the signal subjected to the
processing is applied to the amplification unit 4.
[0040]
FIG. 4 is a block diagram showing an example of the entire configuration of the array speaker
and the array speaker driving unit according to the first embodiment. The array speaker driving
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unit 4v is a device included in the amplification unit 4 illustrated in FIG. 3 and has a function of
supplying power to the speakers 1m to 8m and 1s to 7s. The array speaker driving unit 4 v has
eight input terminals 1 n to 8 n and eight amplifiers 1 a to 8 a. The input terminals 1n to 8n are
respectively connected to the amplifiers 1a to 8a, and the amplifiers 1a to 8a are respectively
connected to the corresponding main speakers 1m to 8m and the corresponding sub speakers 1s
to 7s.
[0041]
The connection relationship between the amplifiers 1a to 8a, the main speakers 1m to 8m, and
the auxiliary speakers 1s to 7s will be described more specifically below. The positive terminals
(+) of the amplifiers 1a-8a are connected to the main speakers 1m-8m and the positive terminals
(+) of the sub-speakers 1s-7s, respectively. On the other hand, the negative terminal (-) of the
amplifier 1a is connected to the negative terminal (-) of the main speaker 1m, and the negative
terminals (-) of the amplifiers 2a-8a are the negative terminals of the main speakers 2m-8m and
the auxiliary speakers 1s-7s. Each is connected to (-).
[0042]
The input terminals 1 n to 8 n receive eight signals processed by the signal processing unit 3
shown in FIG. 3 and send the eight input signals to the corresponding amplifiers 1 a to 8 a. The
amplifiers 1a to 8a amplify the input signals received from the input terminals 1n to 8n and send
the amplified signals to the main speakers 1m to 8m and the auxiliary speakers 1s to 7s. Here,
the amplifiers 1a to 8a balance amplify the input signals received from the input terminals 1n to
8n. That is, the amplifiers 1a to 8a have the same signal amplitude, and a signal amplified in the
same phase as the input signal with respect to the reference voltage and a signal amplified in the
opposite phase to the input signal with respect to the reference voltage It sends to the main
speakers 1m to 8m and the sub speakers 1s to 7s.
[0043]
The signals balanced and amplified by the respective amplifiers 1a to 8a are applied to the
positive terminal (+) and the negative terminal (-) of the main speakers 1m to 8m. For example, to
the positive terminal (+) and the negative terminal (-) of the main speakers 1m to 8m, two signals
that change in opposite phases with equal amplitude with respect to the balance drive, that is, the
09-05-2019
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reference voltage are sent. On the other hand, the positive terminals (+) and the negative
terminals (-) of the auxiliary speakers 1s to 7s are connected to the terminals of the same polarity
of the amplifiers 1a to 8a adjacent to each other, and the positive terminals (+) and the negative
terminals of the auxiliary speakers 1s to 7s Signals from the amplifiers 1a to 8a corresponding to
different inputs are given to the terminals (-). For example, the positive terminal (+) of the sub
speaker 1 s is connected to the positive terminal (+) of the main speaker 1 m, and the negative
terminal (−) of the sub speaker 1 s is connected to the negative terminal (−) of the main
speaker 2 m. Therefore, the signal from the positive electrode terminal (+) of the amplifier 1a is
given to the positive electrode terminal (+) of the sub speaker 1s, and the negative electrode
terminal (-) of the sub speaker 1s is the negative electrode of the amplifier 2a adjacent to the
amplifier 1a. A signal from the terminal (-) is sent.
[0044]
Since the main speakers 1m and 2m are respectively driven in balance, a voltage of 1/2 of the
drive voltage applied to the main speaker 1m with respect to the reference voltage is applied to
the positive terminal (+) of the main speaker 1m. ing. Similarly, to the negative electrode terminal
(-) of the main speaker 2m, a half of the drive voltage applied to the main speaker 2m with
respect to the reference voltage is applied in reverse phase. Therefore, for the sub-speaker 1s
connected to the positive terminal (+) of the main speaker 1m and the negative terminal (-) of the
main speaker 2m, a voltage half the drive voltage of the main speaker 1m and a drive voltage of
the main speaker 2m A half voltage of is applied. This is equivalent to the fact that the average
value of the drive voltages of the main speakers 1m and 2m is applied to the sub speaker 1s.
[0045]
As described above, the array speaker driving unit 4v amplifies the input signals 1n to 8n using
the amplifiers 1a to 8a, and applies the amplified signals to the corresponding main speakers 1m
to 8m and the corresponding sub speakers 1s to 7s. Then, the speakers 1m to 8m and 1s to 8s
emit a wave front of sound based on the signals sent from the amplifiers 1a to 8a.
[0046]
The array speaker 1 has a function of synthesizing wavefronts by superimposing sound waves
radiated from a plurality of main speakers 1m to 8m and sub-speakers 1s to 7s constituting the
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array speaker 1. Therefore, the signals given to the main speakers 1m to 8m and the auxiliary
speakers 1s to 7s constituting the array speaker 1 have a strong correlation with each other. For
example, in WFS, the signal processing unit 3 shown in FIG. 3 shows the delay and distance
attenuation when a sound wave propagates from the virtual sound source position to the
positions of the main speakers 1m to 8m and the auxiliary speakers 1s to 7s constituting the
array speaker 1 By reproducing using the delay and variable gain amplifiers 311 to 318, 321 to
328,..., 3k1 to 3k8, a wavefront centered on the virtual sound source position is emitted from the
array speaker 1.
[0047]
As described above, the input signals applied to the amplifiers 1a-8a in the array speaker driver
4v depend on the relative difference in the distances between the virtual sound sources and the
main speakers 1m-8m and the auxiliary speakers 1s-7s constituting the array speaker 1. The
time difference is determined, and the amplitude is determined depending on the distance
between the virtual sound source and the speakers 1m to 8m and 1s to 7s. Therefore, when the
distance between the main speakers 1m to 8m and the auxiliary speakers 1s to 7s constituting
the array speaker 1 is shorter than the wavelength, or when the distance between the array
speaker 1 and the virtual sound source is large, The phase difference of the input signal sent is
reduced. On the other hand, when the width of the array speaker 1 is shorter than the
wavelength, or when the angle between the array speaker 1 and the virtual sound source is close
to a right angle, the maximum value of the phase difference of the input signal sent to each
amplifier 1a to 8a is It becomes smaller.
[0048]
In addition, when the virtual sound source position and the positions of the speakers 1m to 8m
and 1s to 7s are apart and the curvature of the wave front in the vicinity of the speakers 1m to
8m and 1s to 7s is large, signals generated by interpolation, that is, average values; The error
from the true value of the signal corresponding to the position of the target secondary speakers
1s to 7s is reduced.
[0049]
FIG. 5 is an explanatory view showing an example of the positional relationship between the
array speaker and the virtual sound source.
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FIG. 6 is an explanatory view showing various waveforms when it is assumed that a 100 Hz sine
wave is radiated from a virtual sound source. According to FIG. 5, in the array speaker 1, the
main speakers 1m to 4m and the auxiliary speakers 1s to 4s are alternately arranged at intervals
of 20 cm. The virtual sound source A1 is disposed at a distance of 50 cm from the front of the
array speaker 1 to the back of the speaker and at a distance of 75 cm from the main speaker 1m
to the speaker 4s. Further, in FIG. 6, in the array speaker 1 having the positional relationship
shown in FIG. 5, when it is assumed that a sine wave of 100 Hz is radiated from the virtual sound
source A1, signals (1n given from the main speakers 1m and 2m and the sub speaker 1s The
waveform of the error signal between the interpolation true value signal necessary to reproduce
the wavefront corresponding to the position of the signal and the 2 n signal) and the sub speaker
1s, and the interpolation signal and the interpolation true value signal input to the sub speaker 1
s is shown. . In FIG. 6, the horizontal axis direction of the waveform indicates time, and the
vertical axis direction indicates the amplitude of the waveform. As described above, for example,
the average value of the drive voltages of the main speakers 1m and 2m is applied to the sub
speaker 1s, but the difference in distance between each main speaker and the virtual sound
source position is 40 cm at maximum, 100 Hz The wave length is short compared to about 3.4 m
(normal temperature) of the sound wave wavelength, and no large phase difference occurs.
Further, as shown in FIG. 6, no large error occurs in the interpolation signal and the interpolation
true value signal corresponding to the position of the sub-speaker 1s.
[0050]
In this way, up to seven sub-speakers 1s to 7s are added to eight mains speakers 1m to 8m, and
for each sub-speaker 1s to 7s, the main speakers 1m to 8m (adjacent to each other) For example,
by applying the average value of the driving voltage to the main speakers 1m and 2m), the subspeakers 1s to 7s can be installed in the form of interpolating the wavefront generated by the
main speakers 1m to 8m. Since this is an interpolation signal, it is possible to synthesize a
wavefront close to the target wavefront as compared with parallel drive or series drive for the
main speakers 1m to 8m.
[0051]
As a result, an audio system can be realized by the signal processing unit 3 for eight channels
and the amplifiers 1a to 8a for eight channels with respect to the main speakers 1m to 8m and
the auxiliary speakers 1s to 7s of 15 systems. The effect is obtained that the amount of hardware
of the signal processing unit 3 and the amplification unit 4 does not need to be increased even if
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[0052]
Here, the sub-speakers 1s to 7s may be installed anywhere as long as they are adjacent to the
two main speakers, but by installing the sub-speakers at the same distance from the two main
speakers, regardless of the virtual sound source position. It does not break the wave front that
emits it.
Furthermore, if the main speakers 1m to 8m and the sub-speakers 1s to 7s are the same speaker,
it is possible to reduce the error of the wavefront emitted by the sub-speaker with respect to the
wavefront from the virtual sound source position.
[0053]
In the present embodiment, seven sub-speakers 1s to 7s are connected to the signal processing
unit 3 for eight channels and the amplifiers 1a to 8a, but it is not necessary to connect all seven
sub-speakers.
[0054]
FIG. 7 is an explanatory view showing an appearance example of another array speaker.
In the case of the array speaker 10, the eight main speakers 1m-8m are arranged in a row, and
the four sub-speakers 1s, 3s, 5s and 7s are in a row different from the row of the main speakers
1m-8m. Are arranged to make That is, the eight main speakers 1m to 8m and the four subspeakers 1s, 3s, 5s, and 7s are arranged in two rows. Here, the main speakers are arranged in the
order of 1 m, 2 m, 3 m, 4 m, 5 m, 6 m, 7 m, 8 m toward the front of the array speaker 10, while
the sub speakers are similarly 1s, 3s, They are arranged in the order of 5s and 7s. In the case of
this example, the number of speakers 1m to 8m is eight, and the number of auxiliary speakers 1s,
2s, 5s, and 7s is four, but the number of auxiliary speakers is any number of 1 to 4 It may be.
[0055]
In addition, as described above, in WFS, the delay time is set according to the distance between
the virtual sound source and the main speakers 1m to 8m and the sub speakers 1s to 7s. It is
determined by the angle, the speaker spacing and the wavelength.
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[0056]
FIG. 8 is an explanatory view showing an example of the positional relationship between the
array speaker and the virtual sound source.
Referring to FIG. 8, assuming that the distance from virtual sound source A1 to main speaker 1m
is d1 and the distance from virtual sound source A1 to speaker 2m is d2, the phase difference
between the signals applied to main speakers 1m and 2m θ is expressed by the following
equation. θ = 2π × Δd / λ = 2π × ¦ d1−d2 ¦ / (c / f) It is assumed that the velocity of sound
is c and the frequency is f.
[0057]
On the other hand, since the average value of the drive voltage to the adjacent main speakers 1m
to 8m is applied to the sub speakers 1s to 7s, when the phases of the signals applied to the two
adjacent main speakers are opposite to each other No signal is applied to the sub-speaker. From
this, the upper frequency limit fH of the signal that can be interpolated is fH = c / (2Δd) = c / ¦
2d1-2d2 ¦. Therefore, the condition for reproducing the wavefront traveling parallel to the array
speaker 1 is the lowest as the upper limit of the frequency that can reproduce the wavefront, and
the frequency fz at this time is fz = c / where d is the speaker pitch and c is the sound velocity. It
will be 2d.
[0058]
FIG. 9 is a block diagram showing an example of the overall configuration of the array speaker
and the array speaker driving unit when band limiting is applied to the frequency of the signal
supplied to the sub-speaker. According to FIG. 9, the array speaker driving unit 4v is a device
included in the amplification unit 4 shown in FIG. Band limitation is performed by inserting low
pass filters 1L, 3L, 5L and 7L between the sub-speakers 1s, 3s, 5s and 7s and the amplifiers 1a to
8a. That is, by limiting the frequency of the signal sent to the auxiliary speakers 1s, 3s, 5s, 7s to
the frequency fz or less, that is, by attenuating the frequency higher than the frequency fz, the
sound wave having high frequency components that disturbs the wave front of the sound It is
possible to prevent the speakers 1s, 3s, 5s and 7s from being emitted. In particular, when lowrange speakers having characteristics different from those of the main speakers 1m to 8m are
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used as the secondary speakers 1s, 3s, 5s, and 7s, band limitation is effective to avoid both the
problem of the speaker spacing and the problem of the reproduction band. It becomes.
[0059]
Second Embodiment FIG. 10 is a block diagram showing an example of an entire configuration of
an array speaker and an array speaker driving unit according to a second embodiment. The array
speaker driving unit 4 w is a device included in the amplification unit 4 illustrated in FIG. 3 and
has a function of supplying power to the main speakers 1 m to 8 m and the sub speakers 1 s to 7
s. The array speaker driver 4 w has eight input terminals 1 n to 8 n, four phase inverters 2 r, 4 r,
6 r and 8 r, and eight amplifiers 1 a to 8 a. The input terminals 1n, 3n, 5n and 7n are
respectively connected to the amplifiers 1a, 3a, 5a and 7a, and the amplifiers 1a, 3a, 5a and 7a
are respectively connected to the corresponding main speakers 1m-8m and auxiliary speakers
1s-7s There is. On the other hand, input terminals 2n, 4n, 6n and 8n are connected to amplifiers
2a, 4a, 6a and 8a via phase inverters 2r, 4r, 6r and 8r, respectively. The amplifiers 1a to 8a are
connected to the corresponding main speakers 1m to 8m and the auxiliary speakers 1s to 7s,
respectively. The negative terminals of the main speakers 1m to 7m and the positive terminal of
the main speaker 8m are grounded.
[0060]
More specifically, the connection between the amplifiers 1a to 8a and the speakers 1m to 8m
and 1s to 7s is described. The output signals of the amplifiers 1a, 3a, 5a and 7a are supplied to
the positive terminals (+) of the main speaker 1m and the sub speaker 1s. The output signals of
the amplifiers 2a, 4a, 6a and 8a are connected to the negative terminals (-) of the main speakers
2m, 4m, 6m and 8m and to the negative terminals (-) of the auxiliary speakers 1s to 7s,
respectively.
[0061]
The input terminals 1 n to 8 n receive eight input signals processed by the signal processing unit
3 described above, and the received eight input signals are respectively corresponding to the
amplifiers 1 a to 8 a or the phase inverters 2 r, 4 r, Give to 6r and 8r.
The phase inverters 2r, 4r, 6r and 8r invert the phase of the input signals supplied from the input
terminals 2n, 4n, 6n and 8n.
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[0062]
The amplifiers 1a, 3a, 5a and 7a amplify the input signals received from the input terminals 1n,
3n, 5n and 7n and apply them to the main speakers 1m to 8m and the auxiliary speakers 1s to
7s. On the other hand, amplifiers 2a, 4a, 6a and 8a amplify the signals applied from phase
inverters 2r, 4r, 6r and 8r and apply the amplified signals to main speakers 1m-8m and auxiliary
speakers 1s-7s. Then, the main speakers 1m to 8m and the auxiliary speakers 1s to 7s emit
sound waves according to the given signals.
[0063]
In FIG. 10, phase inverters 2r, 4r, 6r and 8r corresponding to input terminals 2n, 4n, 6n and 8n
are provided. The amplifiers 1a, 3a, 5a and 7a output signals amplified with the same phase as
the phase of the input signal with respect to the reference voltage, and the amplifiers 2a, 4a, 6a
and 8a reverse the phase of the input signal with respect to the reference voltage. A signal
obtained by amplifying the signal converted to the phase of is output. That is, the amplifiers 1a,
3a, 5a and 7a are connected to the positive terminals (+) of the main speakers 1m, 3m, 5m and
7m, and apply signals of the same phase to the main speakers 1m, 3m, 5m and 7m. On the other
hand, amplifiers 2a, 4a, 6a and 8a are connected to the negative terminals (-) of main speakers
2m, 4m, 6m and 8m and are opposite to the phases of the signals applied to main speakers 1m,
3m, 5m and 7m. Give a signal of phase. Thus, when signals of the same phase are input to the
input terminals 1n to 8n, the main speakers 1m to 8m emit a wave front of sound based on the
signals of the same phase.
[0064]
That is, the amplifier 1a amplifies the input signal from the input terminal 1n and sends it to the
positive terminal (+) of the main speaker 1m. On the other hand, the amplifier 2a amplifies the
phase-inverted input signal by the phase inverter 2r and sends it to the negative terminal (-) of
the main speaker 2m, so the main speaker 2m has the same phase as the signal sent to the main
speaker 1m. Operates in phase. Also, the amplifiers 2a, 4a, 6a and 8a send phase-inverted signals
to the secondary speakers 1s and 2s, 3s and 4s, 5s and 6s, and 7s negative terminal (-). That is,
the positive terminals (+) and the negative terminals (-) of the sub-speakers 1s to 7s are driven by
different signals.
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[0065]
Since the positive terminal (+) of the main speaker 1m and the negative terminal (−) of 2m are
driven in opposite phases to each other, the drive voltage of the main speaker 1m and the drive
voltage of the main speaker 2m are applied to the sub speaker 1s. This is equivalent to the
addition value of the main speakers 1m and 2m being applied.
[0066]
As described above, seven sub-speakers 1s to 7s are added at maximum to the eight main
speakers 1m to 8m, and for each sub-speaker 1s to 7s, driving is performed on the adjacent main
speakers 1m to 8m By applying the addition value of the voltage, the sub-speakers 1s to 7s can
be installed in the form of interpolating the wavefronts generated by the main speakers 1m to
8m.
Since this is an interpolation signal, it is possible to synthesize a wavefront close to the target
wavefront as compared with parallel drive or series drive for the main speakers 1m to 8m.
[0067]
By this, as in the first embodiment, an acoustic system can be realized by the signal processing
unit 3 for eight channels and the amplifiers 1a to 8a for eight channels with respect to fifteen
speakers 1m to 8m and 1s to 7s, Even if the number of speakers is increased, an increase in the
amount of hardware of the signal processing unit 3 and the amplification unit 4 can be
prevented. Furthermore, amplifiers 1a to 8a that are not driven in balance can be used, and the
number of wires connecting the speakers 1m to 8m and 1s to 7s can be at least nine. As a result,
the construction cost of the acoustic system can be reduced. . Since the phase inverting circuit
can be configured at very low cost, the addition of the phase inverting circuit hardly affects the
cost.
[0068]
Here, since the signals for two systems of the main speakers 1m to 8m are given to the sub-
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speakers 1s to 7s, a voltage approximately twice that of the main speakers 1m to 8m can be
applied. Thereby, even if the impedances of the speakers 1m to 8m and 1s to 7s are the same,
power larger than that of the main speakers 1m to 8m can be supplied to the auxiliary speakers
1s to 7s. When low-range speakers are used as the sub-speakers 1s to 7s, the efficiency of the
low-range speakers is generally low, and it is necessary to increase the power supplied to the
low-range speakers. By making it high, a speaker with high impedance can be used, and the
current capacity of the amplifier can be reduced.
[0069]
In addition, in the case where the sub-speaker is connected in parallel to a specific main speaker,
the current capacity of the amplifier needs to be increased, and in the case where the
configuration and the configuration in which the sub-speaker is not connected in parallel to the
main speaker are mixed, A bias occurs in the current for each main speaker circuit. Therefore, in
the case where the array speakers are driven by the same type of amplifier, the current capacity
of the amplifier is wasteful when the auxiliary speakers are not connected in parallel to the main
speakers. However, according to the present embodiment, it is possible to reduce the current
capacity bias and to reduce the cost of the amplifier.
[0070]
Further, since the addition signals for two systems of the main speakers 1m to 8m are applied to
the auxiliary speakers 1s to 7s, the impedance of the auxiliary speakers 1s to 7s is set to four
times that of the main speakers 1m to 8m. When the same signal is input to the terminals 1n to
8n, the powers supplied to the connected main speakers 1m to 7m and the auxiliary speakers 1s
to 8s can be aligned. If the characteristics and specifications other than the impedances of the
main speakers 1m to 8m and the sub-speakers 1s to 7s are aligned, the apparent efficiency of the
main speakers 1m to 8m and the sub-speakers 1s to 7s can be equalized, and the wavefronts are
interpolated It is effective in At this time, the current supplied to the auxiliary speakers 1s to 7s
is about half of the current supplied to the main speakers 1m to 8m, and it is not necessary to
significantly increase the current capacity of the amplifier.
[0071]
FIG. 11 is a block diagram showing an example of the overall configuration of the array speaker
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and the array speaker driving unit when the frequency of the signal supplied to the sub-speaker
is band-limited. According to FIG. 11, the array speaker drive unit 4w is a device included in the
amplification unit 4 shown in FIG. As in the first embodiment, band limitation is performed by
inserting low pass filters 1L, 3L, 5L and 7L between the sub-speakers 1s, 3s, 5s and 7s and the
amplifiers 1a to 8a. The negative terminals of the main speakers 1m to 7m and the positive
terminal of the main speaker 8m are grounded.
[0072]
As in the first embodiment, the second embodiment can be applied even to the configuration of
the array speaker shown in FIG. That is, the main speaker and the sub-speaker may be arranged
in two rows.
[0073]
Modifications The present invention is not limited to the above-described first and second
embodiments, and can be implemented in other aspects. Several aspects are shown as a
modification below. In the first and second embodiments, the case of outputting wavefronts to
eight input signal systems is exemplified, but the number of input signal systems can be set to an
arbitrary number. In the first and second embodiments, eight main speakers 1 m to 8 m and
seven sub speakers 1 s to 7 s are connected to eight input signal systems, but the number of
speakers to be connected is n If so, it is possible to connect any number of lines up to n for the
main speaker and n-1 for the sub-speaker. In the first and second embodiments, one main
speaker is connected to one main speaker, but a plurality of speakers may be connected. At that
time, the types of speakers to be connected may be the same or different. In the first and second
embodiments, WFS is given as an example of the wavefront synthesis method, but a method
other than WFS may be used. In the first and second embodiments, the speaker is installed in a
straight line, but the speaker may not be installed in a straight line, and may be installed twodimensionally. In that case, the terminals of the sub-speaker are likewise connected to the
terminals of the two last different main speakers.
[0074]
1 array speaker 1m to 8m main speaker 1s to 7s auxiliary speaker 1n to 8n input terminal 1a to
8a amplifier 2r, 4r, 6r, 8r phase inverter 1L, 3L, 5L, 7L low pass filter 3 signal processing unit 4
amplification unit 5 level Adjustment unit 6 Control unit 7 Position information holding unit 8
Operation unit 9 Wavefront synthesis signal processing unit A1 Virtual sound source B1 to B3
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Listener
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