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JP2006238155

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DESCRIPTION JP2006238155
PROBLEM TO BE SOLVED: To generate a high quality surround sound field. SOLUTION: A signal
of each channel of RL, FL, C, FR, RR is divided into a high frequency signal and a low frequency
signal by HPF and LPF, respectively. The low band signals of the RL, FL and C channels are
superimposed and output from the woofer 21-1 on the left side, and the low band signals of the
RR, FR and C channels are superimposed and output from the woofer 21-2 on the right side . The
high-frequency signals of the respective channels are given predetermined directivity in their
respective directivity control units 17-1 to 17-5, and are outputted from the respective speaker
units 20-1 to 20-n of the array speaker, and Generate a virtual sound source by reflection. A high
quality surround sound field is generated by making the rear channel narrow beam by making
the crossover frequency f2 of the rear channel (RL, RR) higher than the crossover frequency f1 of
the front channel (FL, FR) . [Selected figure] Figure 1
Array speaker device
[0001]
The present invention relates to an array speaker apparatus configured to output multi-channel
sound beams, generate virtual sound sources by wall reflection, and perform surround
reproduction.
[0002]
The delay array type speaker system outputs a slightly different delay time so that the same
acoustic signal can simultaneously reach a certain point (focus) in space from a large number of
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linear or surface arranged speaker units. By doing this, the acoustic energy around the focal
point is intensified by in-phase addition, and as a result, a strong directivity in the focal direction,
that is, a sound beam is produced.
Then, the above-mentioned delay processing is applied to each of the multi-channels, and by
adding all the channels before output to the speaker unit, the speaker unit and the space are
substantially linear systems, so the output multi-channel signal is Each channel has a sound beam
with different directivity. As a result, by emphasizing the directivity in a specific direction, a large
volume can be provided only to the deaf person (Patent Document 1), or two people can
simultaneously give different content by giving different directivity to voices of two different
contents. It is possible to generate a surround sound field by generating a virtual sound source
by viewing and listening (Patent Document 2) or partially reflecting a multi-channel including
surround to a wall (Patent Document 3).
[0003]
FIG. 3 is a diagram showing how several beams are directed to any wall of a room and reflected
to create a virtual sound source in the direction of the wall to generate a multi-channel surround
sound field. In this figure, 31 is a listening room, 32 is a video apparatus such as a television, 33
is an array speaker, 34 is a listener (listener), 35 is a wall on the left of the listener, 36 is a wall
on the right of the listener, 37 is a listener It is a wall behind. Here, assuming that five channels
are reproduced, an acoustic signal is generated forward from the array speaker 33 for the center
(C) channel signal, and for the front left (FL) channel signal, the listener's left side Control the
beam to hit the wall 35 to generate a virtual FL channel sound source 38 and for the front light
(FR) channel signal, control the beam to hit the right wall 36 to control the virtual FR channel
sound source 39 Generate Also, for the rear left (RL) channel signal, the beam is controlled to be
directed from the left wall 35 to the rear wall 37 to generate a virtual RL channel sound source
40, and for the rear right (RR) channel signal, The beam is controlled from the right wall 36 to
the rear wall 37 to generate a virtual RR channel sound source 41. In this way, the signals of
each channel of FL (front left), FR (front light), RL (rear left), and RR (rear light) are given strong
directivity to be beamed, and this is reflected on the wall and the wall direction By perceiving a
sound source, it is possible to generate a surround sound field by a virtual sound source with
only one array speaker installed in front.
[0004]
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The frequency band whose directivity can be controlled by the array speaker is physically
determined by the shape of the array. That is, a wavelength (low frequency) longer than the full
width of the array or a wavelength (high frequency) shorter than the pitch between the speaker
units can not be controlled. Therefore, in reality, a small wide-range speaker is used as a speaker
unit, and control to a certain high frequency is enabled. Since the low band can not be coped with
unless the entire width of the array is increased, a large number of speaker units are required.
Therefore, a method of separately outputting the low band without forming a beam has been
proposed (Patent Document 3).
[0005]
FIG. 4 is a block diagram showing the configuration of the array speaker apparatus in which the
low band is not beamed. In this figure, reference numeral 33 denotes the above-mentioned array
speaker, which comprises a plurality of (n) speaker units 33-1 to 33-n. As shown in this figure,
the signals of the center (C), front left (FL), front light (FR), rear left (RL) and rear light (RR)
channels are respectively provided in the corresponding bands. Input to split filter. Each band
division filter is configured by a combination of a high pass filter (HPF) and a low pass filter
(LPF), and the signal of each channel has a band division frequency (crossover frequency)
passing through HPFs 51-1 to 51-5. Also, it is divided into a high frequency signal (high
frequency component) and a signal (low frequency component) having a frequency lower than
the crossover frequency passing through the LPFs 52-1 to 52-5. The low frequency components
of the signals of the respective channels passed through the LPFs 52-1 to 52-5 are superimposed
by the adder 53, and then from the gain control unit 54-6, the frequency characteristic
correction unit 55-6, and the delay circuit 56-6. The signal adjustment unit (ADJ unit) is
corrected to have the level and the frequency characteristics corrected and subjected to a
predetermined time delay.
[0006]
Further, the high frequency components of the signals of the respective channels that have
passed through the HPFs 51 to 51 to 51 are the gain control units 54-1 to 54-5 and the
frequency characteristic correction unit (EQ) 55 provided corresponding to the respective
channels. The signal adjustment unit comprising the delay circuits 56-1 to 55-5 and the delay
circuits 56-1 to 56-5 is corrected for level and frequency characteristics, and subjected to a
predetermined time delay. Then, it is inputted to directivity control units (DirC) 57-1 to 57-5
provided corresponding to each channel, and the speaker units 33-1 to 33-1 of the array speaker
33 so as to have directivity shown in FIG. A signal of each channel to be output to 33-n is
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generated. Each directivity control unit 57-1 to 57-5 is provided with a delay circuit and a gain
setting unit corresponding to each speaker unit 33-1 to 33-n, and directs the beam in the
direction set for that channel The setting of the delay amount for the purpose and the
multiplication of the window coefficient for reducing the side lobe are performed, and the signal
to be output to each of the speaker units 33-1 to 33-n is generated.
[0007]
An output signal corresponding to each speaker unit having a frequency higher than the
crossover frequency of each channel output from each directivity control unit 57-1 to 57-5, and
a cross of all channels output from the delay circuit 55-6 Signals having frequencies lower than
the over frequency are input to adders 58-1 to 58-n provided corresponding to the respective
speaker units and added. The signals output from the respective adders 58-1 to 58-n are
amplified by power amplifiers 59-1 to 59-n provided corresponding to the respective speaker
units 33-1 to 33-n, and the corresponding speaker units 33 are produced. -1 to 33-n. In this way,
signals at frequencies lower than the crossover frequency are output without being beamed for
all channels, and signals at frequencies higher than the crossover frequency are beamed as
shown in FIG. 3 and output. Be done. JP-A-11-136788 JP-A-11-27604 JP-A-2003-510924
[0008]
The directivity shape when directivity is controlled by the delay array method is determined by
the relationship between the full width of the array and the wavelength, and the high frequency
becomes a narrow shape of the main lobe and the low frequency a wide shape of the main lobe.
FIG. 5 is a view showing an example of the directivity shape of the array speaker. As shown in
this figure, the higher the frequency, the narrower the main lobe. That is, there is a characteristic
that directivity is weak in the low band.
[0009]
In the above-described conventional array speaker apparatus, the beam generation of the front
channel (FL, FR) and the beam generation of the rear channel (RL, RR) are performed in the same
system, which causes a problem in surround quality. That is, there is a problem that the
frequency band localized on the wall in the front channel (FL, FR) can be directly heard from the
array speaker in the rear channel (RL, RR). This is because the rear channel has a longer beam
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path than the front channel as shown in FIG. 3 described above, so the beam that hits the main
lobe is attenuated by distance (6 dB every 2 times), and the low frequency of weak directivity In
the band, the sound from the virtual sound source is lost to the acoustic energy from the front
direction which is the offset of the main lobe. Furthermore, if the distance is long, a time delay
also occurs, which is disadvantageous in the hearth effect. Further, as shown in FIG. 3, the beam
of the rear channel has a smaller angle with the front direction than the beam of the front
channel, and the angle difference between the main lobe and the listener is small. In other words,
the beam travels nearby and is susceptible to fog. As a result, there is a problem that rear
positioning of the rear channel is difficult. A further problem is the rear channel time alignment.
Since the rear channel has a long beam path distance, the beam must be output earlier so as to
be in time with the low-pass component output from the front without being beamed. However, if
the low frequency component of the beam is heard from the front for the above-mentioned
reason, it will be heard at different timings depending on the frequency band.
[0010]
Therefore, the present invention is to improve the quality of the surround sound field generated
in an array speaker apparatus that outputs multi-channel sound beams from an array speaker
and generates a virtual sound source by wall reflection to generate a surround sound field. The
purpose is.
[0011]
In order to achieve the above object, the array speaker apparatus of the present invention uses
an array speaker that generates a plurality of sound beams having different directivity, and
utilizes a wall reflection to surround sound field having a front channel and a rear channel. An
array speaker device for generating a signal and dividing the signal of each channel into a signal
of a frequency band higher than a band division frequency and a signal of a low frequency band,
and sounding a signal of a frequency band higher than the band division frequency Means for
beaming and outputting; and means for outputting a signal in a frequency band lower than the
band division frequency without sound beaming, and the band division frequency for the rear
channel signal is the front channel The frequency is set to be higher than the band division
frequency for the signal.
Further, a signal of a frequency band lower than the band division frequency is outputted from a
low frequency reproduction speaker provided separately from the array speaker.
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[0012]
According to such an array speaker apparatus of the present invention, the quality of the rear
channel can be particularly improved by making the front channel and the rear channel
respectively optimum beam designs. That is, since the front channel is beamed over a wide band,
a sound image with a good sense of localization is generated, and the rear channel is limited to a
narrow band of high frequency and the beam is narrowed, so the localization problem And the
problem of time alignment can be alleviated. Further, when a 2-way system in which a low
frequency band signal is output from a low frequency range reproduction speaker is adopted, the
low frequency range reproduction capability is improved, and music can be reproduced in a wide
band with good balance.
[0013]
FIG. 1 is a block diagram showing the configuration of an embodiment of the array speaker
device of the present invention. The array speaker apparatus according to the present invention
is a two-way system in which the frequency band is divided into at least two, and the high band is
beamed and output using the array speaker 20 including a plurality (n) of speaker units 20-1 to
20-n. The low frequency band is output from the low frequency reproduction speakers (woofers)
21-1 and 21-2 without forming a beam. FIG. 2 is a view showing an appearance of a speaker in
an embodiment of the array speaker device of the present invention. As shown in this figure, an
array speaker 20 having n speaker units is disposed at the center of the speaker housing 22. The
woofer 21-1 is on the left side and the woofer 21 on the right side. 2 is provided. This two-way
arrangement can be expected to play well-balanced music over a wide bandwidth.
[0014]
In FIG. 1, the signals of the channels RL (rear left), FL (front left), C (center), FR (front light), and
RR (rear light) are respectively provided high-pass filters (HPF). 11-1 to 11-5 and a low-pass
filter (LPF) 12-1 to 12-5 and is divided into a high-pass component higher than the crossover
frequency and a low-pass component lower than the crossover frequency. Ru. Here, in the
present invention, the band division filter has at least two types of crossover frequencies. That is,
the front channels (FL, FR) are required to make a stable localization on the wall side, so in order
to beam as wide a band as possible, the HPF 11 for the front channels (FL, FR) is inevitably The
crossover frequency f1 of -2, LPF12-2, HPF11-4 and LPF12-4 is a lower frequency. For example,
if the total array width is 1 m, directivity can be provided up to about 300 Hz, which is an
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equivalent wavelength, and this vicinity is a measure of the crossover frequency f1. Also, since
the rear channel (RL, RR) must pass sideways of the listener in a more directional state as a beam
narrower than the front channel, it is necessary to beam only wavelengths that are sufficiently
short compared to the full width of the array. good. Therefore, the crossover frequency f2 of the
HPF 11-1 for the rear channel (RL, RR), the LPF 12-1, the HPF 11-5 and the LPF 12-5 is set
higher than the crossover frequency f1 of the front channel (f2> f1). Further, the crossover
frequency f0 of the HPF 11-3 for the center channel (C) and the LPF 12-3 is the crossover
frequency (about the same as the front channel (FL, FR) due to the sound quality balance with the
front channels (FL, FR) It may be set as f0 = f1). Alternatively, it may be determined with
reference to the reproduction characteristics of the array speaker unit and the woofer.
[0015]
The low frequency component of the signal of the RL channel which has passed through the LPF
12-1 (the signal of a frequency lower than the frequency f2), the low frequency component of the
signal of the FL channel which has passed through the LPF 12-2 (the signal of the frequency
lower than the frequency f1) The low frequency components (signals of frequencies lower than
frequency f0) of the C-channel signal that has passed through the LPF 12-3 are added by the
adder 13-1. At this time, it is possible to add an arbitrarily set weight to the signal of each
channel. For example, the weights of the RL channel and the FL channel are respectively set to 1,
and the weights of the C channel are added as α (0 <α <1). Gain control unit 14-6 sets the lowpass component signals of the RL channel, FL channel and C channel output from adder 13-1 to
a predetermined gain, and the frequency characteristic correction unit 15-6 sets a predetermined
frequency. After the characteristic is corrected and a predetermined time delay is given by the
delay circuit 16-6, the signal is outputted from the woofer 21-1 on the left side through the
power amplifier 19-6. Similarly, the low frequency component of the RR channel signal (signal
having a frequency lower than the frequency f2) passing through the LPF 12-5 and the low
frequency component of the FR channel signal passing through the LPF 12-4 (lower than the
frequency f1) The low frequency component (the signal of the frequency) and the low frequency
component (the signal of the frequency lower than the frequency f0) of the signal of the C
channel which has passed through the LPF are added by the adder 13-2 with a predetermined
weight as described above. Then, the low frequency component signals of the RR channel, the FR
channel and the C channel output from the adder 13-2 are the same as those described above in
the gain control unit 14-7, the frequency characteristic correction unit 15-7, and the delay circuit
16 After being subjected to predetermined processing at -7, the signal is amplified by the power
amplifier 19-7 and output from the woofer 21-2 on the right side. Thus, the low-frequency
components of the left channel (RL, FL) and the center channel signal (1: 1: α) are output from
the left woofer 21-1 and the right channel (RR and FR) and the center The low-pass component
(1: 1: α) of the channel signal is output from the woofer 21-2 on the right. The contents of
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processing in the gain control units 14-6 and 14-7, the frequency characteristic correction units
15-6 and 15-7, and the delay circuits 16-6 and 16-7 will be described later.
[0016]
On the other hand, the high frequency components of the signals of the channels FL, FR, RL and
RR are respectively beamed to generate the virtual sound sources 38, 39, 40 and 41 shown in
FIG. That is, the high frequency component (signal of a frequency higher than the frequency f2)
of the signal of the RL channel that has passed through the HPF 11-1 is set to a predetermined
gain by the gain control unit 14-1, and the frequency characteristic correction unit 15-1. The
frequency characteristic is corrected corresponding to the characteristics of the beam path, and
time delay for compensating for the difference in propagation delay time due to the beam path is
performed in the delay circuit 16-1 and input to the directivity control unit 17-1. Ru. The
directivity control unit 17-1 is provided with a delay circuit and a level control circuit
corresponding to each of the n speaker units constituting the array speaker 20. Then, in each
delay circuit, the delay amount for the signal output from each of the speaker units 20-1 to 20-n
is set so that the high frequency signal of this RL channel reaches the listener along the path
shown in FIG. Also, each level control circuit is multiplied by a window coefficient for reducing
the side lobe of the signal output from the array speaker 20, and an output signal corresponding
to each speaker unit is output. Thereby, the high frequency signal of the RL channel is reflected
by the left wall 35 and the rear wall 37 shown in FIG. 3 to generate a virtual sound source 40.
Similarly, high frequency components (signals of a frequency higher than the frequency f1) of
the signal of the FL channel which has passed through the HPF 11-2 have a gain control unit 142, a frequency characteristic correction unit 15-2, and a delay circuit 16-2. Are input to the
directivity control unit 17-2 for the signal of the FL channel. Then, a signal to be output to each
of the speaker units 20-1 to 20-n is generated such that the high frequency signal of the FL
channel is reflected by the left wall 35 to form a beam for generating the virtual sound source
38. Ru.
[0017]
Further, the high frequency component (signal of a frequency higher than the frequency f1) of
the signal of the FR channel which has passed through the HPF 11-4 passes through the gain
control unit 14-4, the frequency characteristic correction unit 15-4 and the delay circuit 16-4.
Are input to the directivity control unit 17-4 for the FR channel signal, and the high frequency
signal of the FR channel is reflected by the right wall 36 to form a beam that generates the
virtual sound source 39. Signals to be output to the speaker units 20-1 to 20-n are generated.
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Furthermore, the high-frequency component (signal of a frequency higher than the frequency f2)
of the signal of the RR channel that has passed through the HPF 11-5 passes through the gain
control unit 14-5, the frequency characteristic correction unit 15-5, and the delay circuit 16-5. Of
the high frequency of the RR channel is reflected by the right wall 36 and the rear wall 37 to
generate a virtual sound source 41. As a result, signals to be output to the speaker units 20-1 to
20-n are generated. The high frequency component (signal of a frequency higher than the
frequency f0) of the C channel signal that has passed through the HPF 11-3 passes through the
gain control unit 14-3, the frequency characteristic correction unit 15-3, and the delay circuit
16-3. And the signal is output to each of the speaker units 20-1 to 20-n so as to be input to the
directivity control unit 17-3 for the C channel signal and to output a signal having directivity to
the front. Ru.
[0018]
The signals output from the directivity control units 17-1 to 17-5 to correspond to the speaker
units 20-1 to 20-n are generated by adders 18-1 to 18-n provided to correspond to the speaker
units. The addition is performed to generate an output signal for each of the speaker units 20-1
to 20-n, which is amplified by the power amplifiers 19-1 to 19-n provided corresponding to each
of the corresponding speaker units to obtain the corresponding speaker unit 20-. It is output
from 1 to 20-n. Since the system after the above adders 18-1 to 18-n is a substantially linear
system including space, each channel has an independent directivity as if the array speakers are
for the number of channels (beams). The virtual sound source is generated as shown in FIG. 3
and multi-channel reproduction is performed.
[0019]
The set values in the gain control units 14-1 to 14-7, the frequency characteristic correction
units 15-1 to 15-7, and the delay circuits 16-1 to 16-7 will be described. The gain control units
14-1 to 14-7 set gains according to the beam path distances of the respective channels so as to
compensate for the distance attenuation until the beams of the respective channels reach the
listener. That is, in the rear channel (RL, RR), the distance from the array speaker 20 to the
listener is long and the distance attenuation is large. Therefore, in order to compensate for this,
the gain control units 14-1 and 14-5 have gain (volume) Set the larger. Then, the gain control
units 14-2 and 14-4 for the FL channel and the FR channel set the gain to a medium level, and
for the C channel, set the gain to "x1". Further, the gain control units 14-6 and 14-7 for low band
signals set the gains to compensate for the differences in the efficiency and number of the array
speakers 20 and the woofer 21. The frequency characteristic correction units 15-1 to 15-7
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correct the frequency characteristic to compensate for the difference in the characteristic (wall
reflection characteristic etc.) of the path through which each beam passes. For example, in the
frequency characteristic correction units 15-1, 15-2, 15-4 and 15-5, the frequency characteristic
is controlled so as to compensate for the wall reflection characteristic. The delay circuits 16-1 to
16-7 correct the difference in arrival time due to the difference in the path length of each beam.
That is, no delay time is set (delay time = 0) in the delay circuits 16-1 and 16-5 of the rear
channel (RL, RR) having the longest path to the listener, and the delay of the front channel (FL,
FR) In circuits 16-2 and 16-4, a first delay time d1 corresponding to the difference in path
distance from the rear channel is set, and delay circuits 16-3 and 16- for the center channel (C)
and the low band signal are set. In 6 and 16-7, a second delay time d2 (d2> d1) corresponding to
the difference in path distance with the rear channel is set. This allows the listener to reach all
the signals simultaneously.
[0020]
Thus, according to the array speaker device of the present invention, the frequency band is
divided into two, and the high band signal is beamed to generate a virtual sound source, and the
low band signal is output without being beamed. The crossover frequency is set to be different
for the front channel (FL. FR) and the rear channel (RL, RR), and the rear channel is configured to
beam a signal in a higher frequency band than the front channel. As a result, the front channels
(FL, FR) are beamed over a wide frequency band, so that a sound image with a good sense of
localization is reproduced, and the rear channels are beamed narrowly. The problem is reduced.
[0021]
In the above, two woofers are used to reproduce the low band signals of each of the left and right
channels, but a single woofer is used to transmit low band signals of all channels to the single
woofers. It may be used to reproduce. Moreover, in the above, although the case where 2 way
system was employ | adopted was demonstrated, it is not restricted to this. The present invention
can also be applied to the case where the two-way system is not adopted as shown in FIG. 4 or
the case of the three-way system. Furthermore, although the case of 5 channels has been
described above as an example, the present invention can be applied to other multi-channel
systems such as 7.1 channels as well.
[0022]
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It is a block diagram which shows the structure of one Embodiment of the array speaker
apparatus of this invention. It is a figure which shows the external appearance of the speaker
part in one embodiment of the array speaker apparatus of this invention. It is a figure which
shows a mode that a multi-channel surround sound field is produced | generated by an array
speaker. It is a figure which shows the structure of the array speaker apparatus which was made
not to beam-form low-pass. It is a figure which shows an example of the directivity shape of an
array speaker.
Explanation of sign
[0023]
11-1 to 11-5: high pass filter, 12-1 to 12-5: low pass filter, 13-1, 13-2: adder, 14-1 to 14-7: gain
control unit, 15-1 to 15 -7: frequency characteristic correction unit, 16-1 to 16-7: delay circuit,
17-1 to 17-5: directivity control unit, 18-1 to 18-n: adder, 19-1 to 19-n , 19-6, 19-7: power
amplifier, 20: array speaker, 20-1 to 20-n: speaker unit, 21-1, 21-2: low frequency reproduction
speaker
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