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JP2004186895

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DESCRIPTION JP2004186895
The present invention provides a speaker apparatus using an array speaker which can relatively
easily localize sound images of respective channels even in sound reproduction by multi-channel
audio signals such as multi-channel surround reproduction. SOLUTION: First and second array
speakers 10L and 10R are arranged in the vicinity of two intersecting lines of mutually facing
wall surfaces of a listening room and a ceiling. The directions of the principal axes of directivity
of the first and second beam-like sound waves BM1 and BM2 emitted from the first and second
array speakers are the first and second directions in which the sound image by the input sound
signal is to be localized To generate signals to drive the first and second array speakers. The
signals for driving the first and second array speakers are simultaneously at positions where the
first and second beam sound waves BM1 and BM2 should localize the sound image of the input
sound signal for the same sound component of the input sound signal. The delay time is adjusted
to reach. [Selected figure] Figure 3
Speaker device
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker apparatus using an array speaker composed of a plurality of speaker units. [0002] A
plurality of speaker units are arranged, for example, one-dimensionally or two-dimensionally, and
an array speaker configured in a panel type is arranged, for example, in front of and in front of a
listening position. There has been proposed a speaker system which reproduces sound of two or
more channels only with a speaker (see, for example, WO 01/23104 A3 (Patent Document 1)
and JP-A-6-205496 (Patent Document 2)). In this system, sound waves emitted from an array
speaker are reflected as a beam-like directivity on the side wall, rear wall, ceiling, etc. of the
listener to reach the listener, and as if sound waves were finally It is perceived that the sound
source is in the direction of the reflected wall, and sound image localization in any direction is
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possible with only one panel of array speakers arranged in front of the listener. Patent Document
1: International Publication No. WO 01/23104 A3. [Patent Document 2] Japanese Patent
Application Laid-Open No. 6-205496. In the speaker apparatus using the above-mentioned array
speaker, when performing multi-channel surround reproduction, the speaker is disposed at the
center in the width direction on the front (front) side of the listener. It is realized by emitting
multi-channel sound waves each having a beam-like directivity from one array speaker. However,
in the case of the conventional speaker device, it is difficult to localize the sound images of all the
channels to the desired positions. In particular, with regard to the sound of the rear (rear)
channel that must be made to reach the listener after being reflected many times on the wall or
ceiling, the sound is localized in the sound image localization direction assumed corresponding to
the rear (rear) channel. It is difficult to That is, it is almost impossible to narrow down the
directivity narrowly like a light beam by the size of the array speaker and the wavelength of the
sound wave, and it is reflected on the wall many times to reach the listener. In this case, the path
length of the sound wave becomes very long, and the distance attenuation of the sound wave
becomes large. Furthermore, since the wall usually does not reflect the sound wave completely
but partially absorbs the sound, the attenuation of the sound wave becomes intense according to
the number of reflections.
Therefore, as in the case of the above-mentioned rear channel, in the case where the sound wave
emitted from the array speaker is reflected many times on the wall surface to reach the listener,
it is assumed for each rear channel. Localizing in the sound image localization direction is
considered to be extremely difficult in practice. In view of the above points, the present invention
makes it relatively easy to localize the sound image of each channel to an initial position even in
sound reproduction by multi-channel sound signals such as multi-channel surround
reproduction. It is an object of the present invention to provide a speaker device that SUMMARY
OF THE INVENTION In order to solve the above-mentioned problems, a speaker device according
to the present invention comprises: a first plurality of speaker units; and a first wall and a ceiling
of a listening room The intersection of a second wall and a ceiling which is composed of a first
array speaker arranged in the vicinity of the intersection and a plurality of second speaker units
and which is different from the first wall of the listening room A second array speaker disposed
in the vicinity of the second array speaker, and generating a plurality of first unit drive signals
for receiving the input audio signal and supplying the first plurality of speaker units of the first
array speaker A finger of an acoustic wave emitted from the first array speaker by the first
plurality of unit drive signals being supplied to the first plurality of speaker units. First directivity
forming signal generating means for generating the first plurality of unit drive signals such that
the direction of the main axis of the sound is the first direction to localize the sound image by the
input audio signal; Generating a second plurality of unit drive signals to be supplied to the
second plurality of speaker units of the second array speaker in response to the input audio
signal, the second plurality of units comprising: The direction of the principal axis of the
directivity of the sound wave emitted from the second array speaker by supplying a drive signal
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to the second plurality of speaker units is the second of the sound images by the input sound
signal to be localized A second directivity forming signal generating unit that generates the
second plurality of unit drive signals, and a main axis of directivity from the first array speaker to
the first direction. The time for the sound wave emitted as the direction to reach the position
where the sound image by the input sound signal should be localized, and the sound wave
emitted from the second array speaker with the second direction as the direction of the main axis
of directivity And delay means for adjusting the difference between the time to reach the position
where the sound image by the input audio signal is to be localized.
According to this invention of the above-described configuration, the first and second array
speakers are respectively disposed in the vicinity of the intersection of the wall and the ceiling on
the left and right sides of the listening room, for example, as viewed from the listener. Ru. Then,
first and second unit drive signals for driving each of the first and second array speakers are
generated from the audio signal of each channel. Then, from the first and second array speakers,
sound waves of first and second beams are respectively emitted in the sound image localization
direction assumed for the sound signal of the channel. In this case, with respect to the first and
second unit drive signals, the delay time difference between both unit drive signals is adjusted by
the delay means, and the first and second beam-like acoustic waves The sound image localization
positions assumed for audio signals are simultaneously reached. Therefore, since the first and
second beam-shaped sound waves based on the audio signal of the channel simultaneously reach
the sound image localization position assumed for the audio signal of the channel, both sound
waves are synthesized in the same phase. And become mutually reinforcing and reach the
maximum level. That is, by combining the first and second beam-shaped sound waves with the
audio signal of the channel, a sound image focused at a sound image localization position
assumed for the audio signal of the channel is formed. Therefore, the listener can listen to the
sound image localization position so that the sound image of the channel is localized. Also for the
audio signal of each channel in the case of multi-channel surround reproduction, focusing to the
assumed sound image localization position by synthesizing beam-like sound waves from the first
and second array speakers in exactly the same manner. Can easily form a sound image. Also for
the sound of the rear channel, it is possible to easily localize the sound image to a desired
position without performing many wall reflections. BEST MODE FOR CARRYING OUT THE
INVENTION Hereinafter, embodiments of a speaker device and a sound reproduction method
according to the present invention will be described with reference to the drawings. FIGS. 1, 2
and 3 illustrate a speaker device according to the present invention for monitoring the image
projected on the screen of the video reproduction device and playing back the sound associated
with the sound. 7 shows an example of a system configuration in the case of using as a part of a
viewing system to be used.
In this example, the viewing environment (listening room) is assumed to be a room like a normal
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rectangular parallelepiped, and right and left wall surfaces 4 L and 4 R are on the sides of the
listener 2. There are wall surfaces 4F and 4B, and above the listener 2, there is a ceiling 4C, and
the listener is seated in a chair placed on the floor 4G. In this example, a projection screen 1 for
displaying an image projected by the video projector 3 (see FIG. 2) is installed on the side of the
wall 4 F in front of the room as viewed from the listener 2. In this example, the listener 2 is
seated so as to look at the projection screen 1 in front. In the speaker device of this embodiment,
a plurality of speaker units 11 are arrayed in this example: first and second array speakers 10 L
and 10 R arranged one-dimensionally or two-dimensionally. And an audio signal generation
circuit for a speaker. The first and second array speakers 10 L and 10 R are, in this example, at
the intersection of the first and second wall surfaces facing each other across the floor surface
and ceiling of the listening room, and the ceiling. It is attached and provided. That is, as shown in
FIGS. 1 to 3, in this example, the first array speaker 10L is disposed in the vicinity of the
intersection line 5 between the left side wall 4L and the ceiling surface 4C with reference to the
listener 2. The second array speaker 10R is disposed in the vicinity of the intersection 5 between
the right side wall 4R and the ceiling surface 4C. Although not shown in FIGS. 1 to 3, the audio
signal generation circuit for an array speaker is provided in a circuit box provided with an input
terminal for audio signals for one or a plurality of channels and provided with an adjustment
operation unit. . This circuit box is provided at an appropriate position that can be operated by
the user. The circuit box and the first and second array speakers 10L and 10R may be connected
by a cable or may be connected wirelessly. When wirelessly connecting, a plurality of unit drive
signals supplied from the circuit box to the plurality of speaker units 11 are multiplexed and sent
to the first and second array speakers 10L and 10R, and each of the array speakers 10L and 10R
, Decomposes a plurality of multiplexed unit drive signals and supplies corresponding ones to the
respective speaker units 11. Also, the array speaker audio signal generation circuit configures
the first and second array speakers 10 L and 10 R respectively from the audio signals of the
respective channels such as the audio signal of the left channel and the audio signal of the right
channel. The first and second plurality of unit drive signals supplied to each of the plurality of
speaker units 11 are formed.
The first and second plurality of unit drive signals are emitted from the array speakers 10 L and
10 R when the plurality of unit drive signals are supplied to the corresponding plurality of
speaker units 11. The main axes of the directivity of the sound waves BM1 and BM2 (see FIG. 3)
are generated as described later so as to be desired directions. That is, based on the first and
second plurality of unit drive signals, the directions of the sound waves BM1 and BM2 emitted in
the form of beams are determined from the array speakers 10L and 10R. [Configuration Example
of First and Second Array Speakers] The first and second array speakers 10L and 10R in this
embodiment have the same configuration. As shown in FIG. 4, the array speakers 10L and 10R of
this embodiment are configured such that a plurality of speaker units 11 are attached to a
prismatic cabinet 12 whose cross-sectional shape is substantially a right triangle. And FIG. 4
showed three examples by the difference in the method of arrangement | positioning of the
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several speaker unit 11. In FIG. 4 (A) and 4 (B) are the first example, FIGS. 4 (C) and 4 (D) are the
second example, and FIGS. 4 (E) and 4 (F) are the second example. Three examples are shown
respectively. 4 (A), 4 (C) and 4 (E) show the surface 15S of the cabinet 12 to which the plurality
of speaker units 11 are attached, and FIG. 4 (B) FIGS. 4 (D) and 4 (F) show cross sections of the
cabinet 12, respectively. As shown in FIG. 4 (B), FIG. 4 (D) and FIG. 4 (F), the cabinet 12 of the
array speakers 10L and 10R of this embodiment has tops of which the shape of the cross section
is substantially perpendicular. The plurality of speaker units 11 are attached to the cabinet 12 so
as to emit a sound wave from the surface 15S including the oblique side 15, which is a right
triangle including the sandwiching side 13 and the side 14 and the oblique side 15. <First
Arrangement Example of Speaker Unit> In this first arrangement example, as shown in FIG. 4A,
the diaphragms 11 v of the plurality of speaker units 11 are the surface 15 S of the cabinet 12.
Are arranged in a one-dimensional array. In this example, a plurality of speaker units 11 having
the same size and the same characteristic are arranged. Here, arranging the plurality of speaker
units 11 means arranging the plurality of speaker units 11 side by side so that the respective
diaphragms face the outside from the surface 15 S where the sound wave emitting surface is to
be formed. It means that.
In the example of FIG. 4, the speaker unit 11 is provided with a circular diaphragm 11v, and all
the principal axes in the vibration direction of the diaphragm 11v are in a direction orthogonal to
the surface 15S. In this example, as the speaker unit 11, for example, a small full-range speaker
unit with a diameter of about 8 cm is used. Although this speaker unit 11 has a minimum
reproduction frequency of approximately 200 Hz, it is possible to reproduce an audio signal
although the reproduction sound pressure level is lowered even in a frequency band below that.
The speaker units 11 are arranged in a row in close proximity to each other at a constant interval
D. Here, the arrangement interval D is an interval between the centers (unit centers) of the
diaphragms 11 v of the adjacent speaker units 11, and in this example, for example, D is 10 cm.
The number of loudspeaker units 11 affects the sharpness of the directional beam, the low side
lobes, or the frequency range where sharp directivity can be obtained. In consideration of the
installation space and the like, it is about 8 to 16 for example. <Second Arrangement Example of
Loudspeaker Units> In the first arrangement example of FIG. 4A, the plurality of speaker units 11
are linearly arranged, but in the second arrangement example, FIG. As shown in), a plurality of
speaker units 11 are two-dimensionally arranged in a so-called staggered arrangement. By
arranging the plurality of speaker units 11 in a staggered manner as described above, as shown
in FIG. 4C, the arrangement interval of the speaker units 11 can be D / 2, and a large number of
speakers can be arranged in a narrow space. The units can be arranged, and the high frequency
limit frequency that can control the directivity can be further increased. <Third Arrangement
Example of Speaker Unit> In the above-described two arrangement examples, full-range speaker
units having the same diameter and the same characteristics are used as the plurality of speaker
units 11, but a plurality of speakers As a unit, speaker units having different diameters and
characteristics may be mixed and used. The third arrangement example is an example in that
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case, and in the example of FIG. 4E, a full range speaker unit is used as a plurality of speaker
units, and a high sound range unit (tweeter with a small aperture) is used. ) 16 is used. Then, in
this example, the high range unit (tweeter) is disposed in the gap between the full range speaker
units as shown in FIG. 4 (E).
According to the array speaker of the third arrangement example, it is possible to improve the
directivity in the high frequency range. In addition, not only the high range unit (tweeter) but
also a combination of a medium range unit and a full range unit, or a combination of three types
of a full range unit, a high range unit, and a medium range unit You may do so. The array
speaker configuration method is not limited to the above-described example, and various
configuration methods are possible. [Attachment Position of Array Speakers 10 L and 10 R] The
array speaker 10 L is in contact with the ceiling 4 C, or a surface including one side 13 which
sandwiches the top of the triangle in the triangular cross section shown in FIG. Close to and
parallel to the ceiling 4C, the plane including the other side 14 sandwiching the top of the right
angle contacts the left wall 4L or close to the wall 4L and parallel to the wall 4L It is made to be
and attached. In the array speaker 10R, the surface including the side 13 is in contact with the
ceiling 4C or close to the ceiling 4C so as to be parallel to the ceiling 4C and the surface
including the side 14 is on the right It is attached so as to be in contact with the wall surface 4R
or close to the wall surface 4R so as to be parallel to the wall surface 4R. The plurality of speaker
units 11 constituting the array speakers 10 L and 10 R have cabinets as viewed from the surface
15 S including the oblique side 15 of the triangular cross section shown in FIG. As it is attached
to 12, the direction of the main axis of the plurality of speaker units 11 is in the state of facing
obliquely downward. FIG. 5 is a cross-sectional view showing a state in which the array speaker
10R is disposed at the intersection between the ceiling 4C and the right side wall 4R. As
described above, in this example, the cross section of the cabinet 12 of the array speaker 10R is
substantially in the shape of a right triangle, and the right angle portion of the cabinet 12 faces
the intersection line between the ceiling 4C surface and the right side wall 4R. Will be installed.
The ceiling 4 C surface and the right side wall 4 R acoustically act as a boundary surface.
Although the sound wave is not completely reflected, in general, the sound absorption coefficient
in these surfaces is not so high, so it is necessary to consider an acoustic phenomenon close to a
mirror image phenomenon. For the sake of simplicity, the loudspeaker unit 11 is considered to
be omnidirectional and radiate at equal sound pressure levels in any direction.
The acoustic center of the speaker unit 11 (perhaps considered to be the joint between the voice
coil and the diaphragm) is separated from the ceiling surface 4 C and the right side wall 4 R by
several cm to 10 cm, respectively. In this case, in the speaker unit 11 (SP0), a mirror image SPm1
with respect to the ceiling surface 4C is formed, a mirror image SPm3 with respect to the right
side wall surface 4F is formed, and a mirror image SPm2 with respect to both surfaces is formed.
When the array speaker is designed on the premise of operation in a free sound field space such
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as an anechoic chamber, the gain and delay time given to each speaker unit can be derived
relatively simply. However, it is very difficult to design in consideration of the presence of
reflective walls and the like in the listening environment of the speaker. However, in the
loudspeaker apparatus of this embodiment, since the mirror images SPm1, SPm2 and SPm3 of
the array loudspeakers are in the vicinity of the real sound source SP0, the interference due to
them is extremely reduced, and the simple design method is used. Beam-like directivity
characteristics are obtained. Rather, since the reflected waves from the respective wall surfaces
(equivalent to the sound waves propagated from the respective mirror images) and the direct
waves from the real sound source SP0 travel without interference, an effect of increasing the
sound pressure also occurs. Also in FIG. 5, since the acoustic center of the speaker unit 11 is
slightly separated from the ceiling surface 4 C and the right side wall 4 R, it is expected that the
interference phenomenon by the mirror image will occur in the high sound area. Since the
directivity characteristic of the unit 11 is not completely omnidirectional and there is not a
problem that the shift to the front direction is particularly remarkable in the high range and the
radiation in the lateral direction and the rear direction is hardly emitted. It does not happen.
[Audio Signal Generating Circuit for Array Speaker] For each of the plurality of speaker units 11
of the first and second array speakers 10 L and 10 R configured by arranging the plurality of
speaker units 11 as described above The first and second plurality of unit drive signals are
supplied from the array speaker audio signal generation circuit. The array speaker audio signal
generation circuit supplies, from the audio signal of each channel, first and second plurality of
unit drive signals supplied to each of the plurality of speaker units 21 of the first and second
array speakers 10L and 10R. Generate An example of the array speaker audio signal generation
circuit 70 for one channel of the input audio signal will be described below with reference to FIG.
In practice, the circuits 70 of FIG. 6 are provided for the number of channels. However, the
control circuit 75 described later can be provided commonly to the multiple channels. In the case
of the audio signal generation circuit for an array speaker of this example, as shown in FIG. 6, a
first directivity formation signal generation circuit 71 and a second directivity formation signal
generation circuit 72 , Delay adjustment circuits 73 and 74, control circuit 75, first and second
adjustment operation units 76 and 77, output amplifiers 781, 782, 783, ..., 78n (n is the number
of speaker units 11) And output amplifiers 791, 792, 793,..., 79n. The delay adjustment circuit
73 is provided in the front stage of the first directivity forming signal generation circuit 71, and
the delay adjustment circuit 74 is provided in the front stage of the first directivity forming
signal generation circuit 72. The audio input signal of the channel is supplied to the delay
adjustment circuits 73 and 74 through the audio input terminal Sin. The first directivity forming
signal generation circuits 711 and 721 generate the first directivity signal from the input audio
signal of the channel input through the audio input terminal Sin, based on the control signals
CT11 and CT21 from the control circuit 75. And generates a plurality of first and second unit
drive signals U1 and U2 to be supplied to the plurality of speaker units 11 constituting each of
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the second array speakers 10L and 10R. The first and second plurality of unit drive signals U1
and U2 are generated from the control circuit 75 in the direction of the principal axis of the
directivity of the acoustic wave radiated in beam form from the first and second array speakers
10L and 10R. It is generated so as to have a direction determined by control signals CT11 and
CT21. The delay adjustment circuits 73 and 74 are a sound wave (hereinafter referred to as a
first beam sound wave BM1) radiated in a beam shape from the array speaker 10L in the first
direction and a second sound wave from the array speaker 10R. Adjust the difference in time for
sound waves emitted in the form of beams in the direction (hereinafter referred to as the second
beam sound waves BM2) to reach the position assumed as the sound image localization position
of the channel (for example, position FR in FIG. 3) It is to do. The delay times adjusted by the
delay adjusting circuits 73 and 74 are adjusted, for example, on the assumption that the beamlike sound waves BM1 and BM2 are emitted from the longitudinal center points of the array
speakers 10L and 10R. It is
The delay time adjustment among the plurality of speaker units constituting each of the array
speakers 10L and 10R is performed in the first and second directivity forming signal generation
circuits 71 and 72 as described later. Delay times of these delay adjustment circuits 73 and 74
are controlled by control signals CT10 and CT20 from control circuit 75. The control circuit 75 is
supplied with the adjustment operation signal from the first adjustment operation unit 76 and
the adjustment operation signal from the second adjustment operation unit 77. In the first
adjustment operation unit 76, a knob 91 for adjusting the direction of the main axis of directivity
of the first beam sound wave BM1, a knob 92 for adjusting the amplitude of the first beam sound
wave BM1, and the first beam shape A delay time adjustment knob 93 is provided to adjust the
time taken to reach the position assumed to be the sound image localization position of the
sound wave BM1. In the second adjustment operation unit 77, a knob 94 for adjusting the
direction of the main axis of directivity of the second beam sound wave BM2, a knob 95 for
adjusting the amplitude of the second beam sound wave BM1, and the second beam shape A
delay time adjustment knob 96 is provided to adjust the time taken to reach the position
assumed to be the sound image localization position of the sound wave BM1. Then, the direction
adjustment knob 91 is adjusted to adjust a portion related to delay amount control in the control
signal CT11, and the control signal CT11 generates a signal from the first directivity generation
signal generation circuit 71. The direction (first direction) of the main axis of directivity of the
first beam sound wave BM1 determined by the first unit drive signal U1 is adjusted. Further, by
adjusting the amplitude adjusting knob 92, a portion related to amplitude control in the control
signal CT11 is adjusted, and the first beam sound wave BM1 determined by the first unit drive
signal U1 by the control signal CT11. The amplitude (level) is adjusted. Further, by adjusting the
delay amount adjustment knob 93, the control signal CT10 is adjusted, and the delay time in the
first delay adjustment circuit 73 is adjusted by the control signal CT10. Further, by adjusting the
direction adjusting knob 94, the part related to delay amount control in the control signal CT21
is adjusted, and the control signal CT21 generates a signal from the second directivity forming
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signal generation circuit 72. The direction (second direction) of the main axis of directivity of the
second beam-like sound wave BM2 determined by the second unit drive signal U2 is adjusted.
Further, by adjusting the amplitude adjusting knob 95, the portion related to amplitude control in
the control signal CT21 is adjusted, and the second beam sound wave BM2 determined by the
second unit drive signal U2 by the control signal CT21. The amplitude (level) is adjusted. Further,
by adjusting the delay amount adjusting knob 96, the control signal CT20 is adjusted, and the
delay time of the second delay adjusting circuit 74 is adjusted by the control signal CT20. The
first directivity forming signal generation circuit 71 and the second directivity forming signal
generation circuit 72 have exactly the same configuration, and are each composed of the same
number of filter circuits as the number of speaker units 11. That is, the first directivity forming
signal generation circuit 71 includes filter circuits 711, 712, 713,..., 71n in the same number as
the number of speaker units 11 of the first array speaker 10L. The directivity generation signal
generation circuit 72 includes filter circuits 721, 722, 723,..., 72 n of the same number as the
speaker units 11 of the second array speaker 10 </ b> R. Then, as shown in FIG. 6, the control
signal CT11 from the control circuit 75 is individually assigned to each of the filter circuits 711,
712, 713,..., 71n of the first directivity forming signal generation circuit 71. The control signal
CT21 from the control circuit 75 is a bundle of filter circuits 721, 722, 723... 72n of the second
directivity forming signal generation circuit 72. It is a bundle of a plurality of control signals
individually supplied to each. The filter circuits 711, 712, 713, ..., 71n and the filter circuits 721,
722, 723, ..., 72n are each configured by, for example, an analog filter or a digital filter. In the
case of a digital filter, the input audio signal from the audio input terminal Sin is a digital audio
signal, or at the input stage of the first and second directivity forming signal generation circuits
71 and 72, It needs to be converted to a digital audio signal. When each of the filter circuits 711,
712, 713, ..., 71n and the filter circuits 721, 722, 723, ..., 72n is formed of an analog filter, for
example, the capacitance value of the variable capacitance element or The delay time and the
amplitude are adjusted by adjusting the resistance value of the variable resistor by the control
signals CT11 and CT21.
Further, in the case of a digital filter, the control signals CT11 and CT21 are a bundle of sets of
filter coefficients to be supplied to the respective filter circuits, and the delay time is controlled
by changing the filter coefficient values of these sets. And the amplitude is adjusted. As described
above, the first unit drive signal U1 generated by the first directivity formation signal generation
circuit 71 is not limited to the output amplifiers 781, 782, 783,. The number of units 11) is
supplied to each of the corresponding speaker units 11 of the array speaker 10L. Similarly, the
second unit drive signal U2 generated by the second directivity formation signal generation
circuit 72 is output amplifiers 791, 792, 793,..., 79n (n is a speaker unit). 11) are respectively
supplied to the corresponding speaker units 11 of the array speaker 10R. [Description of Sound
Image Forming Method for Each Channel] Next, using the array speaker audio signal generation
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circuit configured as described above and the array speakers 10 L and 10 R, a sound image by
the audio signal of the right channel is generated. The case where it forms in a desired position,
for example, FR is demonstrated. In the example described below, all of the delay adjustment
circuits 73 and 74, the first directivity formation signal generation circuit 71, and the second
directivity formation signal generation circuit 72 are configured as digital circuits. Ru. Therefore,
in this example, each of filter circuits 71 1 -71 n and 721-72 n is formed of a digital filter, and
control signals CT11 and CT21 are respectively applied to filter circuits 711-71 n and 721-72 n.
It is a set of a plurality of supplied filter coefficients. Then, the values of the filter coefficients of
each set are changed by the adjustment of the adjustment knobs 91 to 93 and 94 to 96. The
delay adjustment circuits 413 and 423 are also digital filter configurations, and the control
signals CT10 and CT20 are a bundle of sets of filter coefficients. In this case, for example, the
control circuit 75 is configured by mounting a microcomputer, and the control circuit 75 is a
filter for sequentially changing the direction of the main axis of the directivity of the beam sound
wave. A set of filter coefficients for the circuits 71 1 -71 n and 72 1 -72 n are stored, for
example, in a non-volatile memory, and the set of filter coefficients read from the memory is for
adjusting the adjustment knobs 91, 92 and 94, 95. By changing accordingly, the directions of the
principal axes of directivity of the first and second beam sound waves BM1 and BM2 and the
amplitudes of the first and second beam sound waves BM1 and BM2 are changed.
Similarly, in the control circuit 75, a set of filter coefficients for adjusting the delay time of the
delay adjusting circuits 73 and 74 is stored, for example, in a non-volatile memory, and the filter
coefficients are read out from the memory. The set is changed according to the adjustment of the
adjustment knobs 93 and 96 so that the difference in delay time between the first and second
beam sound waves BM1 and BM2 is adjusted. First, in FIG. 6, in this example, the digital audio
signal of the right channel is supplied through the audio input terminal Sin. Then, in this
embodiment, in the first directivity forming signal generation circuit 71, as shown by the solid
arrow 101 in FIG. 3, from the digital audio signal of the right channel through the audio input
terminal Sin, The position where the sound image by the sound signal of the right channel is to
be localized, in the example of FIG. 3, a first beam sound wave BM1 directed to the right position
FR of the front wall is emitted from the first array speaker 10L To generate a first unit drive
signal U1. As described above, the direction of the main axis of directivity of the first beamshaped acoustic wave BM 1 is adjusted by the direction adjustment knob 91. Further, the
amplitude of the beam sound wave BM1 is adjusted by the amplitude adjustment knob 92. In the
second directivity formation signal generation circuit 72, the digital audio signal of the right
channel through the audio input terminal Sin is directed to the position FR as shown by the solid
arrow 102 in FIG. A second unit drive signal U2 is generated which causes the second beam
sound wave BM2 to be emitted from the second array speaker 10R. As described above, the
direction of the main axis of directivity of the second beam-like acoustic wave BM 2 is adjusted
by the direction adjustment knob 94. Further, the amplitude of the second beam sound wave
BM2 is adjusted by the amplitude adjustment knob 95. Then, the delay adjustment circuits 73
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and 74 are adjusted by the delay amount adjustment knobs 93 and 96, whereby the first beam
sound wave BM1 and the second beam sound wave BM2 of the right channel are adjusted. The
same audio signal component is adjusted to arrive simultaneously (in phase, at the same level) at
the position FR assumed as the sound image localization position. In this way, the first beam
sound wave BM1 and the second beam sound wave BM2 strengthen each other at the position
FR.
Therefore, the listener 2 can listen to the reproduction sound of the right channel as if the sound
image of the right channel is localized at the position FR. Here, the first and second directivity
forming signal generation circuits 71 in the case of reproducing the audio signal of the right
channel by focusing the first and second beam sound waves at the position FR. The delay /
amplitude adjustment of the filter circuits 71 1 to 71 n and 72 1 to 72 n will be further
described with reference to FIG. For example, in order to focus on a point P shown in FIG. 7
corresponding to the position FR and reproduce an audio signal of the right channel, a plurality
of speaker units of the first and second array speakers 10L and 10R It is necessary to adjust the
delay and amplitude according to the distance between point 11 and point P. That is, the delay
for the time required for the sound wave radiated from the point P to reach each of the plurality
of speaker units 11 of the first and second array speakers 10L and 10R and the distance thereof
are inversely proportional to each other. The delay / amplitude adjustment may be performed to
adjust the sound pressure level relatively. However, since the sound image is reproduced at the
point P by the sound waves radiated from the respective speaker units 11, an operation such as
"reverse rotation" of time is performed. For example, in the case of the second array speaker 10R
on the right side of FIG. 7, it is assumed that the array speaker 10R is composed of eight speaker
units 11R1, 11R2, 11R3,. If you explain, it becomes as follows. First, among the plurality of
speaker units constituting the array speaker 10R, the sound wave from the point P reaches the
speaker unit 11R1 closest to the point P earlier than the other speaker units 11R2, 11R3,. . In
addition, the sound wave is received at a sound pressure level higher than that of the other
speaker units 11R2, 11R3, ... 11R8. Conversely, among the plurality of speaker units constituting
the array speaker 10R, the speaker unit 11R8 farthest to the point P is the sound wave from the
point P rather than the other speaker units 11R1, 11R2, 11R3. To arrive late. Moreover, the
sound wave is received at a sound pressure level lower than that of the other speaker units 11R1,
11R2, 11R3,. That is, each of the speaker units 11R1, 11R2, 11R3,... 11R8 receives the sound
wave from the point P with the delay time and the sound pressure level according to the distance
to the point P.
Therefore, when the "reverse rotation" operation is performed, the amplitude of the unit drive
signal input to the speaker unit 11R1 is higher than that of the unit drive signals input to the
other speaker units 11R2, 11R3, ... 11R8. Is reduced and the amount of delay is increased. The
amplitude of the unit drive signal input to the speaker unit 11R8 is larger than that of the unit
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drive signals input to the other speaker units 11R1, 11R2, 11R3, ... 11R7, and the delay amount
is smaller. . Then, regarding unit drive signals supplied to the other intermediate speakers 11R2,
11R3,... 11R7, the amplitude level and the delay amount are determined according to the
distance from the point P. To summarize the above, the amplitude level Ai of the unit drive signal
of the ith speaker unit 11Ri can be determined as being proportional to the distance Li to the
point P. That is, it is determined by Ai = αi · Li (αi is a constant). The delay amount DLi of the
unit drive signal of the i-th speaker unit 11Ri can be determined as a constant value minus a
portion proportional to the distance Li to the point P. That is, it is determined by DLi = K-βi · Li
(K, βi is a constant). Therefore, in the array speaker 10R, a unit drive signal is first input to the
speaker unit 11R8 at a relatively large level, and then sequentially to the speaker unit 11R7, the
speaker units 11R6, 11R5,..., 11R2 The level is gradually lowered, and finally, each unit drive
signal is input to the speaker unit 11R1. Thus, the sound waves emitted from the second speaker
units 11R1, 11R2, 11R3... 11R8 on the right side of FIG. 7 are synthesized at the point P with
their wave fronts having the same amplitude and the same phase, Maximize each other. The unit
drive signal of each speaker unit 11 of the first array speaker 10L on the left side is similarly
generated, and the wave fronts of the sound waves radiated from each speaker unit at point P are
synthesized with the same amplitude and the same phase. Strengthen each other. Therefore, the
sound waves from the two array speakers 10L and 10R strengthen each other at the point P, that
is, at the position FR where the sound image of the right channel is to be localized, and the sound
image by the sound signal of the right channel is localized at the position FR. become.
The design method of each of the filter circuits 711 to 71 n and 721 to 72 n described above is
an example, and as a simpler method, the sound waves radiated from each speaker unit from
each speaker by adjusting only each delay time The wavefronts of may be synthesized in the
same phase. In this embodiment, since the plurality of speaker units 11 of the array speakers
10L and 10R are arranged in a straight line, the directivity characteristics of the array speakers
10L and 10R are also rotationally symmetrical around the arrangement axis. . Of course, as
described above, in each actual speaker unit, almost no sound wave is emitted in the back
direction, so the directivity characteristics on the right side of FIG. 7 need not be considered. This
state will be described with reference to FIG. Focused on the point P (FR) on the front wall 4F
side by the first beam-like sound wave BM1 emitted from the first array speaker 10L disposed in
the vicinity of the intersection line between the ceiling surface 4C and the left side wall 4L
Assuming that a sound image is formed, the sound image is similarly formed at a position as
indicated by a thick dotted line 81 in the figure that is rotationally symmetrical. Of course,
considering that each speaker unit 11 has a preference, strictly speaking, the sound pressure
level is the highest in the front direction of each speaker unit 11. The ability to produce such an
arc-like sound image is undesirable in order to obtain a clear sense of sound and presence.
Therefore, in this embodiment, the second array speaker 10R disposed in the vicinity of the line
of intersection between the ceiling surface 4C and the right side wall 4R is used in combination.
A sound image focused at the point P (FR) is formed by the same method as described above by
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the second beam sound wave BM2 emitted from the second array speaker 10R. In this case, a
sound image is formed at a position as indicated by a thick line 82 in the figure. Then, when it is
synthesized with the sound image by the beam-like sound wave BM1 radiated from the array
speaker 10L disposed near the left intersection line, a sound image is formed only at the point P
(FR). The sound images formed in the arc shape except the point P, as viewed from the other
array speakers of each other, are a collection of points that are not completely in phase, so they
do not reinforce each other, but rather weaken. It no longer works. The above description has
described the method of forming a sound image for the audio signal of the right channel.
However, by providing the array speaker audio signal generation circuits for one channel of FIG.
A sound image of the audio signal of the channel can be formed.
FIG. 9 is a diagram for explaining an example of a sound image formed by using the speaker
device of the embodiment for multi-channel audio signals. In FIG. 9, in the case of the audio
signal of the front left channel, at the position FL on the left side of the front wall 4F, the first
beam sound wave BM1 (solid line 21) from the first array speaker 10L The second beam sound
wave BM2 (solid line 22) from the second array speaker 10R is constructively emitted as
described above to form a sound image. The listener 2 listens so that the sound image of the
front left channel is localized at the position FL in the direction of the dotted line 23. In the case
of the audio signal of the front right channel, as described above, with the first beam sound wave
BM1 (solid line 31) from the first array speaker 10L at the position FR on the right side of the
front wall 4F. The second beam sound wave BM2 (solid line 32) from the second array speaker
10R is constructively emitted as described above to form a sound image. The listener 2 listens so
that the sound image of the front right channel is localized at the position FR in the direction of
the dotted line 33. In the case of the sound signal of the front center channel, at the center
position FC of the front wall surface 4F, the first beam sound wave BM1 (solid line 41) from the
first array speaker 10L and the second array The second beam sound wave BM2 (solid line 42)
from the speaker 10R is constructively emitted as described above to form a sound image. The
listener 2 listens so that the sound image of the front center channel is localized at the position
FC in the direction of the dotted line 43. In the case of the rear left channel, at the position RL on
the left side of the rear wall 4B, the first beam sound wave BM1 (solid line 51) from the first
array speaker 10L and the second array speaker 10R The second beam-like acoustic wave BM2
(solid line 52) is emitted in a constructive manner as described above to form a sound image. The
listener 2 listens to the position RL in the direction of the dotted line 53 so that the sound image
of the rear left channel is localized. In the case of the rear right channel, from the first array
sound wave BM1 (solid line 61) from the first array speaker 10L and the second array speaker
10R at the right position RR of the rear wall surface 4B. The second beam-like acoustic wave
BM2 (solid line 62) is emitted in a constructive manner as described above to form a sound
image.
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The listener 2 listens to the position RR in the direction of the dotted line 63 such that the sound
image of the rear right channel is localized. Note that although not shown in FIG. 9, caution is
required when it is desired to localize on the wall surface just beside the listener 2. For example,
in the case where a sound image is localized on the left side wall 4L just beside the listener 2,
when the above-described beam-like acoustic wave BM2 is emitted from the array speaker 10R
disposed near the right crossing line, the acoustic wave BM2 becomes the listener 2 Crosses the
overhead of the head, so that part of the sound waves reaches the listener 2, and part of the
sound waves are beam-like sound waves emitted to the left side wall 4L by the array speaker 10L
disposed near the left crossing line Since it arrives earlier than BM1, a sense of stereotactic to the
right is generated. In order to avoid this, only in this case, the delay with respect to the unit drive
signal supplied to the speaker unit of the array speaker 10 L disposed in the vicinity of the left
intersection is an array disposed in the vicinity of the right intersection. The unit drive signal
supplied to the speaker unit of the array speaker 10R disposed near the right crossing line rather
than larger than the unit driving signal supplied to the speaker unit of the speaker 10R is
disposed near the left crossing line. It is necessary to give a larger delay to the unit drive signal
supplied to the speaker unit of the array speaker 10L provided. Alternatively, sound waves may
be controlled not to be emitted from the array speaker 10R disposed near the right intersection
line. As described above, according to the above-described embodiment, the first and second
array speakers are provided, and the beam sound waves from the first and second array speakers
are generated as sound images of the input sound signal. The sound image by the audio signal of
each channel can be easily localized to the desired sound image localization position by
combining in a constructive manner at the position where it is desired to localize the sound, and
a good sound reproduction space can be obtained. You can get it. This embodiment differs from
the conventional case where the beam-like sound wave is reflected a plurality of times so that the
sound wave reaches the listener as in the conventional speaker apparatus using an array speaker
disposed on the front of the front, According to this, it is possible to form a good sound image
relatively easily even for the rear channel. [Other Modifications] In the above embodiment, the
first and second array speakers are arranged in the vicinity of the intersection line between the
left and right side wall surfaces 4L and 4R and the ceiling 4C. The first and second array
speakers may be disposed in the vicinity of the line of intersection between the ceiling 4C and
the front wall 4F and the line of intersection of the ceiling 4C and the rear wall 4B.
Further, array speakers are disposed all around the intersection line between the ceiling and the
four wall surfaces 4 L, 4 R, 4 F, 4 B, and the front and rear array speakers are used as the first
and second array speakers, The left and right array speakers can also be used as the first and
second array speakers. In this case, for example, the left and right first and second array
speakers perform the sound image formation as shown in FIG. 9, and the front and rear first and
second array speakers generate the sound image just beside the listener. Can be done. In
addition, the first and second array speakers may be arranged not on the intersecting line
between the facing wall surface and the ceiling but on the intersecting line of the adjacent wall
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surface and the ceiling. Also, instead of two intersections between the ceiling and the two wall
surfaces, three array speakers are provided at three intersections between the ceiling and the
three wall surfaces, and among these three array speakers, for each channel, Alternatively, a set
of two array speakers to be used may be defined to form a sound image of the channel. In the
above embodiment, the position assumed as the sound image localization position is on or near
the wall surface, but it is also possible to assume the sound image localization position in a space
apart from the wall surface it can. Further, the sound image localization position may be assumed
on the rear side of the wall surface. Also, in the case of multi-channel surround reproduction, the
sound image forming method may be applied by combining and strengthening two sound waves
with respect to the sound signals of all the channels as in the above embodiment The method of
combining two sound waves to form a sound image as in the above-described embodiment may
be applied only to the audio signals of some channels such as the left and right channels and the
center channel. In the above embodiment, the array speaker cabinet has a triangular cross
section, but may have a polygonal shape. In addition, the surface 15S including the oblique side
15 in the above-described example may be a curved surface. Furthermore, the shape of the
cabinet may not be parallel to either or both of the ceiling or the wall. In the above example, the
video projector is used as the video reproduction device, so the projection screen is arranged
above the array speaker. However, a television monitor using a CRT (Cathode Ray Tube) as the
video reproduction device A flat display device using a device, an LCD (Liquid Crystal Display), a
PDP (Plasma Display Panel), or the like may be used.
Further, although the delay adjustment circuits 73 and 74 are provided on the input side of the
first and second directivity forming signal generation circuits 71 and 72 in the above example,
they are provided on the output side. You may However, when provided on the output side, a
delay adjustment circuit needs to be provided for each speaker unit 11, and furthermore, the
delay amount and the amplitude for all the speaker units 11 constituting the array speakers 10L
and 10R. The plurality of unit drive signals to be supplied need to be controlled in conjunction so
as to have similar values. The delay adjustment circuits 73 and 74 also have an amplitude
adjustment function, and as the configuration of the delay / amplitude adjustment circuit, the
levels of the first and second beam-shaped acoustic waves are also detected It may be configured
to be adjustable. As described above, according to the present invention, a sound wave emitted
from an array speaker with directivity in a beam shape is made to reach a listener after being
reflected by a wall. Also in this case, sound image localization can be performed in the sound
image localization direction appropriate for the listener. BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view for explaining an example of a system configuration including an embodiment of
a speaker device according to the present invention. FIG. 2 is a diagram for describing an
example of a system configuration including an embodiment of a speaker device according to the
present invention. FIG. 3 is a view for explaining a sound image forming method by the speaker
device according to the present invention; FIG. 4 is a view for explaining an example of an array
speaker used in the embodiment of the speaker device according to the present invention. FIG. 5
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is a view for explaining an arrangement state of an array speaker used in the embodiment of the
speaker device according to the present invention. FIG. 6 is a block diagram of an example of an
audio signal generation circuit for an array speaker used in an embodiment of a speaker device
according to the present invention. FIG. 7 is a view for explaining a sound image forming method
by the speaker device according to the present invention; FIG. 8 is a view for explaining a sound
image forming method by the speaker device according to the present invention; FIG. 9 is a view
for explaining an example of a sound reproduction method using the embodiment of the speaker
device according to the present invention; [Description of the code] 10L: first array speaker, 10R:
second array speaker, 11: speaker unit, 12: cabinet, 71: first directivity forming signal generation
circuit, 72: second directivity Signal formation circuit for formation, 73, 74 ... delay adjustment
circuit, 75 ... control circuit
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