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JP2009290355

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DESCRIPTION JP2009290355
A speaker system which reproduces sound by applying vibration to an acoustic diaphragm by an
actuator so that a sound image can be expanded to the periphery and the outside of the acoustic
diaphragm. SOLUTION: Four actuators 1, 2, 3, 4 are brought into contact with a lower end
surface of a cylindrical acoustic diaphragm 10 to apply vibration to the acoustic diaphragm 10.
In the normal mode, the same left audio signal Lo is supplied to the actuators 1 and 3, and the
same right audio signal Ro is supplied to the actuators 2 and 4. Thus, the sound image Ai is
formed at the inner central portion of the acoustic diaphragm 10. In the wide mode, left voice
signals Lo and Lx in opposite phase to each other are supplied to the actuators 1 and 3, and right
voice signals Ro and Rx in reverse phase to each other are supplied to the actuators 2 and 4. By
this, the sound image Ai is formed on the outside of the acoustic diaphragm 10. [Selected figure]
Figure 20
Speaker driving method and speaker system
[0001]
The present invention relates to a speaker system that reproduces sound by applying vibration to
an acoustic diaphragm by an actuator such as a magnetostrictive actuator or a piezoelectric
actuator, and a method of driving an actuator of the speaker system by an audio signal.
[0002]
As a speaker system, one that applies vibration to an acoustic diaphragm by an actuator such as
a magnetostrictive actuator or a piezoelectric actuator to reproduce sound is considered.
11-05-2019
1
[0003]
Specifically, in Patent Document 1 (Japanese Patent Laid-Open No. 2007-166027) and Patent
Document 2 (Japanese Patent Laid-Open No. 2007-228557), a speaker system as shown in FIG.
27 is proposed.
[0004]
In this speaker system, a cylindrical acoustic diaphragm 10 made of acrylic or the like is
vertically supported on a disk-shaped base housing 20, and the magnetostrictive actuators 30 are
disposed at four equiangularly spaced positions of the base housing 20. Deploy.
[0005]
The driving rod 35 of each magnetostrictive actuator 30 is brought into contact with the lower
end face 12 of the acoustic diaphragm 10, and the magnetostrictive actuator 30 is driven by the
audio signal to make the lower end face 12 of the acoustic diaphragm 10 a plate surface
perpendicular thereto. Add a directional vibration.
[0006]
The lower end face 12 is excited by the longitudinal wave, but the vibration elastic wave
propagates in the direction of the plate surface of the acoustic diaphragm 10 to become a wave
in which the longitudinal wave and the transverse wave are mixed, and is perpendicular to the
plate surface of the acoustic diaphragm 10 Sound waves are emitted in any direction, and a
uniform sound image is formed over the entire height direction of the acoustic diaphragm 10.
[0007]
Furthermore, although omitted in FIG. 27, Patent Literatures 1 and 2 show that a normal speaker
unit is attached to the central opening of the base housing 20.
[0008]
In this case, the acoustic diaphragm 10 and the magnetostrictive actuator 30 function as a
tweeter for receiving the middle high frequency band of the audio frequency band, and function
a normal speaker unit as a woofer for receiving the low frequency side of the audio frequency
band.
[0009]
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2
In FIG. 7 of Patent Documents 1 and 2, a drive system as shown in FIG. 28 is shown as a drive
system of this speaker system.
In FIG. 28, actuators 1, 2, 3 and 4 are the four magnetostrictive actuators shown in FIG.
[0010]
In the drive system of FIG. 28, the left audio signal L and the right audio signal R that constitute a
stereo audio signal are synthesized by the addition circuit 121.
[0011]
The synthesized speech signal Ahl is supplied to the high pass filter 122 and the low pass filter
125, and from the high pass filter 122, the speech signal Ah of the middle to high frequency
component is obtained, and from the low pass filter 125, the speech signal Al on the low
frequency component Is obtained.
[0012]
The audio signal Ah of the mid-high frequency component from the high-pass filter 122 has its
frequency characteristic corrected by the equalizer 123, and is further amplified by the
amplifiers 124-1, 124-2, 124-3, 124-4, and the actuators 1, 2, It is supplied to 3,4.
[0013]
The low-pass component audio signal Al from the low-pass filter 125 is corrected for frequency
characteristics by the equalizer 126, delayed for several milliseconds by the delay circuit 127,
amplified by the amplifier 128, and supplied to the speaker unit 50 described above. Be done.
[0014]
Further, FIG. 16 of Patent Documents 1 and 2 shows a drive system as shown in FIG. 29 as a
drive system of the above speaker system.
In FIG. 29, actuators 1, 2, 3 and 4 are the four magnetostrictive actuators shown in FIG.
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[0015]
The left audio signal L and the right audio signal R are synthesized by the adder circuit 121, the
high-pass filter 122 obtains an audio signal Ah of the middle high frequency component, and the
low pass filter 125 obtains an audio signal Al of low frequency component It is the same as the
drive system of FIG.
[0016]
In the drive system of FIG. 29, the audio signal Ah of the mid-high frequency component from
the high-pass filter 122 has a level or the like at the signal processing units 129-1, 129-2, 129-3,
129-4 such as DSP (Digital Signal Processor). Delay time etc. are adjusted.
[0017]
The adjusted audio signals are amplified by the amplifiers 124-1, 124-2, 124-3, 124-4 and
supplied to the actuators 1, 2, 3, 4.
[0018]
The audio signal Al of the low-pass component from the low-pass filter 125 is subjected to
processing equivalent to the equalizer 126 and the delay circuit 127 of FIG. It is supplied to the
unit 50.
[0019]
Further, FIG. 17 of Patent Document 2 shows a drive system as shown in FIG. 30 as a drive
system of the above speaker system.
In FIG. 30, actuators 1, 2, 3 and 4 are the four magnetostrictive actuators shown in FIG.
[0020]
In the drive system of FIG. 30, the left audio signal L and the right audio signal R are attenuated
by the attenuator 210 for each channel of the actuator, and the signal processing unit 211
adjusts the level, delay time, and the like.
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The signal processing unit 211 further mixes the adjusted left audio signal and the right audio
signal.
[0021]
The mixed audio signal is supplied to the high pass filter 212 for each channel of the actuator,
and from the high pass filter 212, the middle and high frequency components of the mixed audio
signal are obtained for each channel of the actuator.
The voice signals of the middle and high frequency components are amplified by the amplifier
202 and supplied to the actuators 1, 2, 3 and 4.
[0022]
On the other hand, the left audio signal L and the right audio signal R are attenuated by the
attenuator 220 for the speaker unit 50, and the signal processing unit 221 adjusts the level,
delay time, and the like.
The signal processing unit 221 further mixes the adjusted left audio signal and the right audio
signal.
[0023]
The mixed voice signal is supplied to the low pass filter 222, and the low pass filter 222 obtains
the low frequency component of the mixed voice signal.
The audio signal of the low frequency component is amplified by the amplifier 203 and supplied
to the speaker unit 50.
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5
[0024]
The magnetostrictive actuator is an actuator using a magnetostrictive element whose shape
changes when an external magnetic field is applied.
Recently, as magnetostrictive elements, giant magnetostrictive elements whose shape change
amount is nearly 1000 times that of the conventional one have appeared.
[0025]
In addition, since the magnetostrictive element generates a large stress when the shape changes,
even a small magnetostrictive actuator can make the acoustic diaphragm ring at a relatively large
volume, and even a hard acoustic diaphragm such as an iron plate can ring. be able to.
[0026]
Furthermore, the magnetostrictive actuator is also excellent in response speed, and the response
speed of the single magnetostrictive element is on the order of nanoseconds.
[0027]
However, not only the magnetostrictive actuator but also a piezoelectric actuator can be used as
an actuator for driving the acoustic diaphragm.
[0028]
In addition, the thing of the correlation coefficient between two audio | voice signals (acoustic
signal) is described in the following nonpatent literature 1. FIG.
Further, Non-Patent Document 1 shows a pseudo stereo system in which an input audio signal is
used as it is as a left audio signal, and a signal obtained by supplying the same input audio signal
to a Schrader circuit as a right audio signal. .
[0029]
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6
The prior art documents mentioned above are as follows.
JP, 2007-166027, A JP, 2007-228, 557 NHK Giken monthly report, December, 1984, pages 1823 "Control method of sense of spread and sense of distance in sound image in stereo
reproduction"
[0030]
However, when the plurality of actuators vibrate the acoustic diaphragm to reproduce the sound
as described above, if the actuators are driven by the same audio signal as described above, the
spread of the sound image is reduced.
[0031]
Specifically, when the speaker system of the example of FIG. 27 is driven by the method shown in
FIG. 28, FIG. 29 or FIG. 30, the sound image Ai is of the acoustic diaphragm 10 as shown in FIGS.
In the plane orthogonal to the central axis, the acoustic diaphragm 10 is formed at the inner
central portion thereof and has no sense of expansion.
A signal (L + R) h in FIG. 31A is a middle high frequency component of a synthesized signal of the
left audio signal L and the right audio signal R described above.
[0032]
Therefore, in the present invention, the sound image can be expanded to the periphery and the
outside of the acoustic diaphragm.
[0033]
According to the speaker driving method of the present invention, the control unit of the speaker
system which applies vibration to the acoustic diaphragm by the plurality of actuators to
reproduce the sound drives the plurality of actuators. To generate first and second speech signals
decorrelated such that the correlation coefficient between each other is smaller than one, and
driving the first actuator by the first speech signal; The second actuator is driven by the audio
signal.
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7
[0034]
In the above speaker driving method, since the first and second audio signals are signals having a
correlation coefficient between each other which is less than 1, less correlated with each other,
or uncorrelated with each other, A sound image by the second sound signal is spread and formed
on the periphery and the outside of the acoustic diaphragm.
[0035]
As described above, according to the present invention, the sound image can be expanded to the
peripheral portion or the outside of the acoustic diaphragm.
[0036]
[1.
Example of Speaker System: FIGS. 1 to 4] As an example of a speaker system, a case where
vibration in a plate surface direction perpendicular to the end face is applied to the end face of a
cylindrical acoustic diaphragm by a plurality of actuators is shown.
[0037]
(1−1.
Configuration of Entire System: FIGS. 1 to 3) FIGS. 1, 2 and 3 show a speaker system of this
example.
FIG. 1 is a view of the speaker system as viewed from above, FIG. 2 is a side view of the base
housing taken along line AA in FIG. 1, and FIG. 3 is a line BB in FIG. It is sectional drawing of a
part.
[0038]
The acoustic diaphragm 10 is formed, for example, of an acrylic or the like in a cylindrical shape
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8
with both ends opened, and has a thickness of 2 mm, a diameter of 10 cm, and a length (height)
of 100 cm.
[0039]
The base housing 20 is formed of, for example, aluminum or the like in a disk shape having a
certain height (thickness), which is larger than the outer diameter of the acoustic diaphragm 10.
[0040]
The acoustic diaphragm 10 has an end face on one end side as the upper end face 11 and an end
face on the other end as the lower end face 12 so that its axial direction is vertical and its central
axis is aligned with the central axis of the base housing 20 , Mounted on the upper surface 21 of
the base housing 20.
[0041]
Specifically, one end of the L-shaped angle 41 is made to interpose the damping material 42
made of silicon rubber between it and the base casing 20 at four positions of the equiangular
interval of the upper surface 21 of the base casing 20, respectively. And attach to the base
housing 20 with the screws 43.
[0042]
Furthermore, damping materials 44 and 45 made of silicone rubber are respectively interposed
inside and outside of the acoustic diaphragm 10, and the other end of the L-shaped angle 41 is
attached to the lower end of the acoustic diaphragm 10 by the screw 46 and the nut 47. Attach.
[0043]
By attaching the acoustic diaphragm 10 to the base casing 20 via the damping members 44, 45
and 42 in this manner, the vibration of the acoustic diaphragm 10 is transmitted to the base
casing 20 and a sound image is formed on the base casing 20 side. It is possible to prevent
localization.
[0044]
Furthermore, in the base housing 20, a storage portion which is a hole vertically penetrating
from the upper surface 21 to the lower surface 22 at four positions at equal angular intervals
between the attachment positions of the L-shaped angle 41. Form 23.
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9
[0045]
The magnetostrictive actuators 30 are inserted into the respective housing portions 23 of the
base housing 20 from the lower side with the respective drive rods 35 directed upward.
[0046]
Furthermore, coil springs (coil springs) 24 and screws 25 are respectively inserted below the
magnetostrictive actuators 30 in the respective storage portions 23.
The screw 25 is inserted into the housing 23 until the tip of the drive rod 35 abuts on the lower
end surface 12 of the acoustic diaphragm 10 and the coil spring 24 is compressed by a
predetermined amount.
[0047]
Legs 27 are formed on the lower surface 22 of the base housing 20 at three positions at equal
angular intervals.
Between the lower end surface 12 of the acoustic diaphragm 10 and the upper surface 21 of the
base housing 20, a damping material 28 made of silicon rubber or the like is disposed at a
position excluding the position of the drive rod 35 of the magnetostrictive actuator 30, as
necessary. To intervene.
Thereby, the degree of sealing between the acoustic diaphragm 10 and the base housing 20 can
be increased.
[0048]
With the above configuration, when the magnetostrictive actuator 30 is driven by an audio
signal, the magnetostrictive element described later of the magnetostrictive actuator 30 expands
and contracts in the axial direction according to the audio signal, and the drive rod 35 is
displaced in the same direction. Longitudinal wave vibration is applied to the lower end surface
12 of the acoustic diaphragm 10.
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10
[0049]
This longitudinal wave propagates along the plate surface of the acoustic diaphragm 10 to the
upper end surface 11, but in the process of propagation, it becomes a wave in which the
longitudinal wave and the transverse wave are mixed, and is perpendicular to the plate surface of
the acoustic diaphragm 10. Sound waves are emitted in the direction.
[0050]
Furthermore, in this example, as shown in FIG. 1 and FIG. 3, with the central portion of the base
housing 20 as the opening 29, the speaker unit 50 is directed to the opening 29, for example,
with the front of the speaker facing downward Attach the back side upwards.
For the speaker unit 50, the acoustic diaphragm 10 functions as a cabinet.
[0051]
In this case, for example, the acoustic diaphragm 10 and the magnetostrictive actuator 30 are
functioned as tweeters for receiving the middle high frequency range of the audio frequency
band, and the speaker unit 50 is functioned as a woofer for receiving the lower frequency side
audio frequency band.
[0052]
(1−2.
Example of Magnetostrictive Actuator: FIG. 4) FIG. 4 shows an example of the magnetostrictive
actuator 30.
In this example, the magnetostrictive element is preloaded.
[0053]
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11
As an actuator body, a solenoid coil 32 is disposed around a bar-shaped magnetostrictive
element 31, and a magnet 33 and a yoke 34 are disposed around the solenoid coil 32.
Further, the drive rod 35 is connected to one end of the magnetostrictive element 31, and the
fixed board 36 is attached to the other end of the magnetostrictive element 31.
[0054]
The actuator main body is loaded in an outer casing case 39 made of, for example, aluminum so
that the tip end of the drive rod 35 protrudes to the outside of the outer casing case 39.
[0055]
Furthermore, a damping material 37 made of silicon rubber or the like is loaded on the drive rod
35, and a screw 38 is inserted behind the fixed plate 36 to apply a preload to the
magnetostrictive element 31.
[0056]
[2.
Speaker Driving Method: FIGS. 5 to 22] (2-1.
Correlation coefficient r: FIGS. 5 to 7) As shown in the above non-patent document 1 etc., the
correlation coefficient r can be considered as one of the indicators showing the degree of
similarity between two audio signals. ing.
[0057]
As shown in FIG. 5, the correlation coefficient r takes values from +1 to -1.
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12
If the two audio signals are identical, the correlation coefficient r is 1 (+1).
If the two audio signals are independent or unrelated, the correlation coefficient r is zero.
If the two audio signals are out of phase with each other, the correlation coefficient r is -1.
[0058]
According to the speaker system of the example shown in FIGS. 1 to 3, as shown in FIG. 6, a plate
surface direction perpendicular to the lower end surface of the cylindrical acoustic diaphragm 10
by the two actuators 1 and 2 Consider the case of adding vibration.
[0059]
An audio signal for driving the actuator 1 (supplied to the actuator 1) is A1, and an audio signal
for driving the actuator 2 (supplied to the actuator 2) is A2, and the phase relationship between
the audio signal A1 and the audio signal A2 Let the number be r12.
[0060]
Considering the relationship between the correlation coefficient r12 and the sound image, in the
case of r12 = 1, as shown in FIG. 7A, the sound image Ai is acoustic in a plane orthogonal to the
central axis of the acoustic diaphragm 10. It is formed at the inner central portion of the
diaphragm 10 and has no sense of spreading.
[0061]
In the case of r12 = 0, as shown in FIG. 7B, the entire sound image is formed with circular
portions Ai10 and Ai20 on the inner side of the actuators 1 and 2 in the plane orthogonal to the
central axis of the acoustic diaphragm 10. , And the part Ai30 between the two.
[0062]
In the case of r12 = -1, as shown in FIG. 7C, the entire sound image is a semi-annular sound
image Ai1 outside the actuators 1 and 2 in a plane perpendicular to the central axis of the
acoustic diaphragm 10. It consists of Ai2, and a sound image with a sense of expansion is
obtained.
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13
[0063]
In the case of r12 = 1 as shown in FIG. 7A, for example, similarly to the case shown in FIG. 31,
the signal of the sum of the left audio signal and the right audio signal of the stereo audio signal
is each audio signal A1, A1. This is the case of A2.
[0064]
When r12 = 0 as shown in FIG. 7B, for example, the audio signal A1 is a left audio signal in a
stereo audio signal, and the audio signal A2 is a right audio signal in a stereo audio signal.
[0065]
In the case of r12 = -1 as shown in FIG. 7C, for example, a signal of the sum of the left audio
signal and the right audio signal of the stereo audio signal is defined as the audio signal A1, and
the audio signal A1 is in reverse phase This is the case where the signal is an audio signal A2.
[0066]
Therefore, in the present invention, the two actuators are driven by the two audio signals that are
decorrelated so that the correlation coefficient between them is smaller than one.
The decorrelation in this case is performed by phase shifting, delaying or calculating
(synthesizing) the speech signal.
[0067]
As described above, it is an example of decorrelation that setting the signal of a phase of the sum
of the left audio signal and the right audio signal as the audio signal A1 and the signal of the
opposite phase to this as the audio signal A2. is there.
[0068]
(2−2.
Driving Method and Sound Image State: FIG. 8 and FIG. 9 FIG. 8 shows the case of driving the
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14
speaker system of the example shown in FIGS.
The actuators 1, 2, 3 and 4 are the four magnetostrictive actuators shown in FIG.
[0069]
An audio signal (supplied to the actuator 1) that drives the actuator 1 A1, an audio signal that
drives the actuator 2 (supplied to the actuator 2) A2, an audio that drives the actuator 3
(supplied to the actuator 3) A signal is A3, and an audio signal for driving the actuator 4
(supplied to the actuator 4) is A4.
[0070]
As the correlation coefficient r, (a) r12: correlation coefficient between audio signals A1 and A2,
(b) r13: correlation coefficient between audio signals A1 and A3, (c) r14: between audio signals
A1 and A4 (D) r23: correlation coefficient between audio signals A2 and A3, (e) r24: correlation
coefficient between audio signals A2 and A4, (f) r34: phase between audio signals A3 and A4
There are six relation numbers, which can be considered.
[0071]
In the driving method of the following example, all six correlation coefficients r12, r13, r14, r23,
r24 and r34 are sufficiently smaller than 1, that is, close to -1 or 0, The speech signal is
decorrelated.
[0072]
As a result, as shown as sound image Ai in FIGS. 9A and 9B as a whole, the sound image by the
sound signals A1, A2, A3 and A4 is a sound in a plane perpendicular to the central axis of the
acoustic diaphragm 10. The ring 10 is annularly formed on the outside of the diaphragm 10 to
obtain a sound image with a sense of spread.
[0073]
Hereinafter, a specific driving method will be described for monaural reproduction, stereo
reproduction, and surround reproduction.
[0074]
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15
(2−3.
Driving method in the case of performing monaural reproduction: FIG. 10) FIG. 10 shows an
example of a driving method in the case of performing monaural reproduction.
[0075]
In this example, the original monaural audio signal Mo is supplied as it is to the actuator 1, and
the phase of the monaural audio signal Mo is delayed (or advanced) by 90 ° phase shift circuit
79a to produce monaural audio signal M1. The actuator 2 is supplied as
[0076]
Further, the phase of the monaural audio signal M1 is delayed (or advanced) by 90 ° by the 90
° phase shift circuit 79b and supplied to the actuator 3 as the monaural audio signal M2 and is
supplied to the actuator 3 by the 90 ° phase shift circuit 79c. The phase is delayed by 90 ° (or
advanced) and supplied to the actuator 4 as a monaural audio signal M3.
[0077]
In this example, the six correlation coefficients r12, r13, r14, r23, r24 and r34 shown in FIG. 8
are all decorrelated to form a sound image outside the acoustic diaphragm 10 as shown in FIG.
And a sound image with a sense of spread is obtained.
[0078]
(2−4.
Driving method in the case of performing stereo reproduction: FIGS. 11 to 16 <First example: FIG.
11> FIG. 11 shows a first example of a driving method in the case of performing stereo
reproduction.
In this example, decorrelation is achieved by inverting the phase.
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16
[0079]
That is, the original left audio signal Lo is directly supplied to the actuator 1 as one left audio
signal La, and the phase inversion circuit 61 inverts the phase of the left audio signal Lo to
produce the other left audio signal Lb. A signal whose phase is inverted with respect to one left
audio signal La is obtained and supplied to the actuator 3.
[0080]
Similarly, the original right audio signal Ro is directly supplied to the actuator 2 as one right
audio signal Ra, and the phase inversion circuit 62 inverts the phase of the right audio signal Ro,
and the other right audio signal Rb As a signal obtained by inverting the phase of one right audio
signal Ra, the signal is supplied to the actuator 4.
[0081]
Therefore, in this example, the correlation coefficient r13 between the left audio signal La and
the left audio signal Lb is -1, and the correlation coefficient r24 between the right audio signal Ra
and the right audio signal Rb is also -1. .
[0082]
In this example, a sound image is formed on the outside of the acoustic diaphragm 10, and a
sound image with a sense of spreading is obtained.
[0083]
Furthermore, in this example, even if the listener listens from the direction indicated by the
arrow 9a or from the direction indicated by the arrow 9b, the left audio signal is localized to the
left as viewed from the listener, and the right audio as viewed from the listener to the right You
can listen to music as the signal is localized.
[0084]
However, when the listener's listening direction is fixed, etc., the left audio signals La, Lb are
supplied to the adjacent actuators 1, 2, and the right audio signals Ra, Rb are supplied to the
adjacent actuators 3, 4. You may
[0085]
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17
Second Example: FIG. 12 FIG. 12 shows a second example of the driving method in the case of
performing stereo reproduction.
In this example, decorrelation is achieved by shifting the phase by 90 °.
[0086]
That is, the original left audio signal Lo is directly supplied to the actuator 1 as one left audio
signal La, and the phase of the left audio signal Lo is shifted by 90 ° by the 90 ° phase shift
circuit 63, and the other left audio is generated. As the signal Lc, a signal whose phase is shifted
by 90 ° with respect to one left audio signal La is obtained and supplied to the actuator 3.
[0087]
Similarly, the original right audio signal Ro is directly supplied to the actuator 2 as one right
audio signal Ra, and the phase of the right audio signal Ro is shifted 90 ° by the 90 ° phase
shift circuit 64, and the other right As the audio signal Rc, a signal whose phase is shifted by 90
° with respect to one right audio signal Ra is obtained and supplied to the actuator 4.
[0088]
Also in this example, the left audio signal Lc is decorrelated to the left audio signal La, the right
audio signal Rc is decorrelated to the right audio signal Ra, and a sound image is formed on the
outside of the acoustic diaphragm 10. A sound image with a sense of spread is obtained.
[0089]
Furthermore, also in this example, the listener localizes the left audio signal to the left as viewed
from the listener, and the right audio as viewed from the listener to the right as viewed from the
listener, regardless of whether the listener listens from the direction indicated by the arrow 9a
You can listen to music as the signal is localized.
[0090]
However, also in this example, the left audio signals La and Lc may be supplied to the adjacent
actuators 1 and 2, and the right audio signals Ra and Rc may be supplied to the adjacent
actuators 3 and 4.
[0091]
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Third Example: FIG. 13 FIG. 13 shows a third example of the driving method in the case of
performing stereo reproduction.
[0092]
In this example, the original left audio signal Lo is supplied to the actuator 1 as it is as one left
audio signal La, and the phase of the original right audio signal Ro is delayed by 90 ° by the 90
° phase shift circuit 89c. The output is supplied to the actuator 2 as one right audio signal Ra.
[0093]
In addition, the phase of the left audio signal Lo is delayed by 90 ° (or advanced) by the 90 °
phase shift circuit 89a, and the phase of the output of the 90 ° phase shift circuit 89a is delayed
by 90 ° by the 90 ° phase shift circuit 89b (or The output of the 90 ° phase shift circuit 89b
is supplied to the actuator 3 as the other left audio signal Lg.
[0094]
Further, the phase of the right audio signal Ra is delayed by 90 ° by the 90 ° phase shift circuit
89d (or advanced), and the phase of the output of the 90 ° phase shift circuit 89d is delayed by
90 ° by the 90 ° phase shift circuit 89e (or The output of the 90 ° phase shift circuit 89e is
supplied to the actuator 4 as the other right audio signal Rg.
[0095]
In this example, the sound image spreading effect can be obtained in any direction of the arrows
9a, 9b, 9c, 9d.
[0096]
Also in this example, the left audio signals La and Lg may be supplied to the adjacent actuators 1
and 2, and the right audio signals Ra and Rg may be supplied to the adjacent actuators 3 and 4.
[0097]
<Fourth Example: FIG. 14> FIG. 14 shows a fourth example of the driving method in the case of
performing stereo reproduction.
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In this example, decorrelation is performed by delaying for a certain time.
[0098]
That is, the original left audio signal Lo is supplied to the actuator 1 as it is as one left audio
signal La, and the delay circuit 65 delays the left audio signal Lo for several milliseconds, and the
other left audio signal Ld is obtained. A signal delayed by several milliseconds with respect to one
left audio signal La is obtained and supplied to the actuator 3.
[0099]
Similarly, the original right audio signal Ro is directly supplied to the actuator 2 as one right
audio signal Ra, and the delay circuit 66 delays the right audio signal Ro for several milliseconds,
and the other right audio signal Rd A signal delayed by several milliseconds with respect to one
right audio signal Ra is obtained and supplied to the actuator 4.
[0100]
Also in this example, the left audio signal Ld is decorrelated to the left audio signal La, the right
audio signal Rd is decorrelated to the right audio signal Ra, and a sound image is formed on the
outside of the acoustic diaphragm 10. A sound image with a sense of spread is obtained.
[0101]
Also in this example, the left audio signals La and Ld may be supplied to the adjacent actuators 1
and 2, and the right audio signals Ra and Rd may be supplied to the adjacent actuators 3 and 4.
[0102]
<Fifth Example: FIG. 15> FIG. 15 shows a fifth example of the driving method in the case of
performing stereo reproduction.
In this example, decorrelation is performed by two comb filters having frequency characteristics
complementary to each other.
[0103]
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20
That is, the delay circuit 67 delays the original left audio signal Lo by about 2 to 4 milliseconds.
The left audio signal of the output of the delay circuit 67 is added to the left audio signal Lo by
the arithmetic circuit 68 to obtain one left audio signal La, and the left of the output of the delay
circuit 67 from the left audio signal Lo is obtained by the arithmetic circuit 69. The audio signal
is subtracted to obtain the other left audio signal Le.
The left audio signal La is supplied to the actuator 1 and the left audio signal Le is supplied to the
actuator 3.
[0104]
Similarly, the delay circuit 71 delays the original right audio signal Ro for about 2 to 4
milliseconds.
The arithmetic circuit 72 adds the right audio signal of the output of the delay circuit 71 to the
right audio signal Ro to obtain one right audio signal Ra, and the arithmetic circuit 73 obtains the
right of the output of the delay circuit 71 from the right audio signal Ro. The audio signal is
subtracted to obtain the other right audio signal Re.
The right audio signal Ra is supplied to the actuator 2 and the right audio signal Re is supplied to
the actuator 4.
[0105]
Also in this example, the left audio signal Le is decorrelated to the left audio signal La, the right
audio signal Re is decorrelated to the right audio signal Ra, and a sound image is formed on the
outside of the acoustic diaphragm 10. A sound image with a sense of spread is obtained.
[0106]
Also in this example, the left audio signals La and Le may be supplied to the adjacent actuators 1
and 2, and the right audio signals Ra and Re may be supplied to the adjacent actuators 3 and 4.
11-05-2019
21
[0107]
<Sixth Example: FIG. 16> FIG. 16 shows a sixth example of the driving method in the case of
performing stereo reproduction.
In this example, the Schroeder circuit decorrelation.
[0108]
That is, the original left audio signal Lo is directly supplied to the actuator 1 as one left audio
signal La, and the other left audio signal Lf is obtained by the Schrader circuit 75 from the
original left audio signal Lo. To supply the actuator 3.
[0109]
Similarly, the original right audio signal Ro is supplied as it is to the actuator 2 as it is as one
right audio signal Ra, and from the original right audio signal Ro by the Schrader circuit 76, the
other right audio signal Rf is And supply it to the actuator 4.
[0110]
In the Schrader circuits 75 and 76, the input voice signal is divided into signal components of 2N
frequency bands by 2N band pass filters shown as BPF1... BPF2N, respectively.
Furthermore, the signal components of one other frequency band advance the phase by 90 °,
and the signal components of the other alternate frequency band are delayed by 90 °, and the
signal components are added and output.
[0111]
Also in this example, the left audio signal Lf is decorrelated to the left audio signal La, the right
audio signal Rf is decorrelated to the right audio signal Ra, and a sound image is formed on the
outside of the acoustic diaphragm 10. A sound image with a sense of spread is obtained.
11-05-2019
22
[0112]
Also in this example, the left audio signals La and Lf may be supplied to the adjacent actuators 1
and 2, and the right audio signals Ra and Rf may be supplied to the adjacent actuators 3 and 4.
[0113]
In the pseudo stereo method disclosed in the above non-patent document 1, an input audio signal
is used as it is as a left audio signal, and a signal obtained by supplying the same input audio
signal to a Schrader circuit as a right audio signal. Therefore, it is completely different from the
stereo reproduction method of the example of FIG.
[0114]
(2−5.
Driving method in the case of performing surround reproduction: FIGS. 17 and 18) FIG. 17 shows
an example of a driving method in the case of performing surround reproduction.
[0115]
In this example, the original left audio signal Lo is supplied to the actuator 1 as the left audio
signal L as it is, and the original right audio signal Ro is supplied to the actuator 4 as the right
audio signal R as it is.
[0116]
At the same time, the right audio signal Ro is subtracted from the left audio signal Lo in the
arithmetic circuit 77, and a signal (Lo-Ro) decorrelated for each of the left audio signal L (Lo) and
the right audio signal R (Ro) , And supplies this signal (Lo-Ro) to the actuator 2 as a surround left
audio signal SL.
[0117]
Similarly, the left audio signal Lo is subtracted from the right audio signal Ro in the arithmetic
circuit 78, and a signal (Ro--decorrelated) is generated for each of the left audio signal L (Lo) and
the right audio signal R (Ro). Lo), and this signal (Ro-Lo) is supplied to the actuator 3 as a
surround right audio signal SR.
11-05-2019
23
[0118]
The surround right audio signal SR is also uncorrelated with the surround left audio signal SL,
that is, the surround left audio signal SL and the surround right audio signal SR are mutually
uncorrelated.
[0119]
The listener listens to the sound to be reproduced, for example, from the direction indicated by
the arrow 9c.
[0120]
In this example, as shown in FIG. 18, the front sound image Af is formed between the actuator 1
and the actuator 4 inside the acoustic diaphragm 10, and the rear sound image Ar is an actuator
outside the acoustic diaphragm 10. It is formed from the vicinity of 2 to the vicinity of the
actuator 3 to obtain a multi-directional sound image as a whole.
[0121]
(2−5.
Control of Switching of Drive Mode and Degree of Decorrelation: FIGS. 19 to 22) The abovedescribed drive method is a case where each actuator is driven in the wide mode by the
decorrelation, but the above-described wide mode The speaker system can also be configured to
be switched to the normal mode in which the special decorrelation processing is not performed.
[0122]
In this case, the drive mode may be switched by the user's operation, but may be automatically
switched without the user's operation.
[0123]
In the latter case, as one method, when the reproduction target is music, the music data is
analyzed by 12-sound analysis or the like in the speaker system, and the drive mode is switched
according to the analysis result.
11-05-2019
24
[0124]
As another method, when information such as metadata is attached to music data and a driving
mode suitable for the music is instructed by the information, the driving mode is switched in the
speaker system according to the instruction.
[0125]
Also, instead of switching the drive mode between the normal mode and the wide mode in a
binary manner, the drive mode can be controlled stepwise or continuously between the normal
mode and the wide mode.
[0126]
Some specific examples are shown below.
[0127]
First Example: FIGS. 19 and 20 FIG. 19 shows a first example.
[0128]
In this example, the drive mode is switched according to the analysis result of music data, and
stereo reproduction is performed.
[0129]
In this example, music data Sa obtained by a DVD player or a music reproduction apparatus is
supplied to the audio processing unit 81 to obtain a left audio signal Lo and a right audio signal
Ro.
[0130]
The left audio signal Lo and the right audio signal Ro are decorrelated by the decorrelating
processor 82 to obtain the left audio signal Lx and the right audio signal Rx.
[0131]
As the decorrelation processing in this case, for example, as shown in FIG. 11, the phase is
11-05-2019
25
reversed.
By inverting the phase, the correlation coefficient between the left audio signal Lo and the left
audio signal Lx and the correlation coefficient between the right audio signal Ro and the right
audio signal Rx become −1, respectively.
[0132]
The left audio signal Lo is supplied to the actuator 1 and the right audio signal Ro is supplied to
the actuator 2.
Also, the left audio signals Lo and Lx and the right audio signals Ro and Rx are supplied to the
switching circuit 84.
[0133]
Then, the 12 sound analysis unit 83 analyzes the 12 sounds of the music data Sa, determines the
genre of the music related to the music data Sa, and determines a drive mode suitable for the
music.
[0134]
In the 12 sound analysis, C (do), C #, D (re), D #, E (mi), F (fa), F #, G (so), G #, A (la), A #, By
analyzing the 12 tones of B (T), the strength of the beat of the music can be detected, and the
genre of the music can be determined.
[0135]
In the relation between the genre of music and the spread of sound images, for example, in the
case of classical music, it is preferable that the spread of sound images is large, but in the case of
rock, it is preferable that the spread of sound images is rather small.
[0136]
Therefore, when the 12 sound analysis unit 83 determines that the music is locked, the left audio
signal Lo and the right audio signal Ro are extracted from the switching circuit 84, and the 12
sound analysis unit 83 determines that the music is classical. Occasionally, the left audio signal
11-05-2019
26
Lx and the right audio signal Rx are extracted from the switching circuit 84.
[0137]
The left audio signal extracted from the switching circuit 84 is supplied to the actuator 3, and the
right audio signal extracted from the switching circuit 84 is supplied to the actuator 4.
[0138]
Therefore, when the music is in lock, the left audio signal Lo is supplied to the actuators 1 and 3,
and the right audio signal Ro is supplied to the actuators 2 and 4, as shown in FIG. A sound
image Ai is formed at the inner center of the acoustic diaphragm 10.
[0139]
When the music is classical, the left audio signal Lo is supplied to the actuator 1, the left audio
signal Lx to the actuator 3, the right audio signal Ro to the actuator 2, and the right audio signal
Rx to the actuator 4, respectively. A sound image Ai is formed on the outside of the acoustic
diaphragm 10, as shown in 20 (B) as the wide mode.
[0140]
Even when the music is another genre, the normal mode or the wide mode is selected according
to the genre.
[0141]
<Second Example: FIG. 21> FIG. 21 shows a second example.
[0142]
In this example, when the decorrelation processing unit 82 and the 12 sound analysis unit 83 are
provided as shown in the example of FIG. 19, in accordance with the analysis result of the 12
sound analysis unit 83 Change control of the degree of correlation continuously.
[0143]
Specifically, for example, the 12-tone analysis unit 83 detects the strength of the beat of the
music, and the decorrelation processing unit 82 continuously changes the phase shift amount in
the range from 0 to 180 °. It is assumed that it has a phase shift circuit for an audio signal and a
right audio signal.
11-05-2019
27
[0144]
The phase shift amounts of the two phase shift circuits are continuously changed and controlled
so that the stronger the beat of the music is, the closer to 0, and the weaker the beat of the
music, the closer to 180 °.
[0145]
Then, in this example, the left audio signal Lo is supplied to the actuator 1, the right audio signal
Ro is supplied to the actuator 2, and the left audio signal Lv output from the decorrelation
processing unit 82 is supplied to the actuator 3, The right audio signal Rv of the output of the
quantization processing unit 82 is supplied to the actuator 4.
[0146]
Therefore, in this example, the drive mode is continuously changed between the normal mode
and the wide mode described above, and the sound image becomes wider as the beat of the
music is weaker.
[0147]
<Third Example: FIG. 22> FIG. 22 shows a third example.
[0148]
This example is a case where the drive mode is switched according to an instruction in metadata
attached to music data, and is a case where surround reproduction is performed.
[0149]
However, this example is different from the example of FIG. 17 and is a case where surround
reproduction is performed by five actuators 1 to 5 instead of four actuators 1 to 4.
The actuator 5 is a magnetostrictive actuator that contacts the acoustic diaphragm 10 at a
position between the actuator 1 and the actuator 4.
11-05-2019
28
[0150]
In this example, the music data Sa is supplied to the audio processing unit 85 to obtain a center
audio signal Co, a left audio signal Lo, a right audio signal Ro, a surround left audio signal SLo,
and a surround right audio signal SRo.
[0151]
These original audio signals are supplied to the decorrelation processing unit 86 so that they are
decorrelated compared to the original audio signals, that is, centers whose correlation
coefficients r between each other are smaller than 1 An audio signal Cx, a left audio signal Lx, a
right audio signal Rx, a surround left audio signal SLx and a surround right audio signal SRx are
obtained.
[0152]
The audio signals Co, Lo, Ro, SLo, SRo from the audio processing unit 85 and the audio signals
Cx, Lx, Rx, SLx, SRx from the decorrelation processing unit 86 are supplied to the switching
circuit 88. .
[0153]
Then, the metadata analysis unit 87 reads the metadata Dm attached to the music data Sa,
determines the drive mode, and switches the switching circuit 88.
[0154]
That is, when the normal mode is set by the metadata Dm, the switching circuit 88 is switched to
the audio processing unit 85 side to set the audio signals Co, Lo, Ro, SLo, SRo to the actuators 5,
1, 4, 2, 3. , Supply each.
[0155]
Therefore, at this time, as in FIG. 20A, a sound image is formed at the inner central portion of the
acoustic diaphragm 10.
[0156]
When the wide mode is set by the metadata Dm, the switching circuit 88 is switched to the
decorrelation processing unit 86 side to set the audio signals Cx, Lx, Rx, SLx, SRx to the actuators
5, 1, 4, 2, 3. , Supply each.
11-05-2019
29
[0157]
Therefore, at this time, a sound image is formed on the outside of the acoustic diaphragm 10 as
in FIG. 20 (B).
[0158]
[3.
Another Example of Speaker System and Driving Method: FIGS. 23 to 26] In addition to the
examples shown in FIGS. 1 to 3, the speaker system can be configured, for example, as follows.
[0159]
(3−1.
Another example in the case of making an acoustic diaphragm into a cylindrical shape: FIG. 23)
An example shown in FIGS. 1 to 3 is a case where the upper end side of the acoustic diaphragm
10 is also an opening, as shown in FIG. The upper end side of the acoustic diaphragm 10 may be
the upper surface bottom plate portion 13 with a bottom.
[0160]
Since FIG. 23 is a cross-sectional view corresponding to FIG. 3, the magnetostrictive actuator is
not shown in FIG.
[0161]
(3−2.
First example in the case where the acoustic diaphragm has a flat plate shape: FIGS. 24 and 25)
FIG. 24 shows an example of the case where the acoustic diaphragm has a flat plate shape.
11-05-2019
30
FIG. 24A is a view of the speaker system as viewed from above, and FIG. 24B is a front view of a
portion of a line CC in FIG. 24A of the base housing.
[0162]
In this example, the flat acoustic diaphragm 100 is attached to the upper surface 21 of the diskshaped base casing 20 by an L-shaped angle 41 or the like shown in FIGS. 1 to 3.
[0163]
The base housing 20 is a hole which vertically penetrates from the upper surface 21 to the lower
surface 22 at two positions opposite to each other across the center on the center side of the Lshaped angle 41 attachment position. The portion 23 is formed.
[0164]
Similar to the example shown in FIGS. 1 to 3, the magnetostrictive actuators 30 are inserted into
the respective housing portions 23 of the base housing 20 from the lower side with the
respective drive rods 35 directed upward.
[0165]
Furthermore, coil springs (coil springs) 24 and screws 25 are respectively inserted below the
magnetostrictive actuators 30 in the respective storage portions 23.
The screw 25 is inserted into the housing 23 until the tip of the drive rod 35 abuts on the lower
end surface 105 of the acoustic diaphragm 100 and the coil spring 24 is compressed by a
predetermined amount.
[0166]
Legs 27 are formed on the lower surface 22 of the base housing 20 at three positions at equal
angular intervals.
[0167]
11-05-2019
31
Also in this example, when the magnetostrictive actuator 30 is driven by an audio signal,
longitudinal wave vibration is applied to the lower end surface 105 of the acoustic diaphragm
100, and sound waves are emitted in a direction perpendicular to the plate surface of the
acoustic diaphragm 100.
[0168]
Furthermore, also in this example, with the central portion of the base housing 20 as the opening
29, the speaker unit 50 may be attached to the opening 29 with the front of the speaker facing
downward and the rear of the speaker facing upward, for example. it can.
[0169]
Also in this case, for example, the acoustic diaphragm 100 and the magnetostrictive actuator 30
can function as a tweeter that receives the middle high range of the audio frequency band, and
the speaker unit 50 can function as a woofer that receives the low frequency side of the audio
frequency band. .
[0170]
FIG. 25 shows an example of a method of driving the speaker system of the example of FIG.
The actuators 1 and 2 are two magnetostrictive actuators shown in FIG.
[0171]
In this example, the left audio signal Lo and the right audio signal Ro are added by the arithmetic
circuit 91 to obtain the monaural audio signal Mo, and the phase inverting circuit 92 inverts the
phase of the monaural audio signal Mo.
[0172]
Then, the monaural sound signal Mo is supplied to one of the actuators 1, and a monaural sound
signal −Mo whose phase is inverted with respect to the monaural sound signal Mo is supplied to
the other actuator 2.
[0173]
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32
According to this, since the correlation coefficient r between the audio signals Mo and Mo is -1, a
sound image spreading to the outside of the actuators 1 and 2 is formed.
[0174]
(3−3.
Second example in the case where the acoustic diaphragm has a flat plate shape: FIG. 26) FIG. 26
shows another example in the case where the acoustic diaphragm has a flat plate shape.
[0175]
In this example, two square holes 101 and 102 are formed in the flat acoustic diaphragm 100,
and the laminated piezoelectric actuators 111 and 112 are respectively formed in the square
holes 101 and 102 at one end and the other end in the respective displacement directions. Are
mounted in the plane of the acoustic diaphragm 100.
[0176]
The laminated piezoelectric actuators 111 and 112 are actuators that respectively laminate
piezoelectric ceramic substrates and displace the respective substrates in the thickness direction
according to an applied voltage.
[0177]
In this example, when the laminated piezoelectric actuators 111 and 112 are driven by the audio
signal, longitudinal wave vibration is applied to the end faces of the acoustic diaphragm 100
facing the square holes 101 and 102, and a direction perpendicular to the plate surface of the
acoustic diaphragm 100. Sound waves are emitted.
[0178]
Also in this example, the monaural audio signal Mo is supplied to the laminated piezoelectric
actuator 111 by the arithmetic circuit 91 and the phase inverting circuit 92, for example, as in
the example of FIG. An audio signal -Mo is supplied to the laminated piezoelectric actuator 112.
[0179]
11-05-2019
33
According to this, since the correlation coefficient r between the audio signals Mo and Mo is −1,
a sound image spreading to the outside of the laminated piezoelectric actuators 111 and 112 is
formed.
[0180]
It is the figure which looked at an example of the speaker system of this invention from upper
direction.
It is the side view which made the cross section the part of line AA of the speaker system of FIG.
It is sectional drawing of the part of line BB of the speaker system of FIG.
It is a figure showing an example of a magnetostrictive actuator.
It is a figure where it uses for description of a correlation coefficient.
It is a figure showing the case where there are two actuators.
It is a figure which shows a mode that a sound image changes according to the correlation
coefficient between two audio | voice signals.
It is a figure showing the case where four actuators are.
It is a figure which shows an example of the sound image state at the time of according to the
drive method of this invention.
It is a figure which shows an example of the drive method in the case of performing monaural
reproduction | regeneration.
11-05-2019
34
It is a figure which shows the 1st example of the drive method in the case of performing stereo
reproduction | regeneration.
It is a figure which shows the 2nd example of the drive method in the case of performing stereo
reproduction | regeneration.
It is a figure which shows the 3rd example of the drive method in the case of performing stereo
reproduction | regeneration.
It is a figure which shows the 4th example of the drive method in the case of performing stereo
reproduction | regeneration.
It is a figure which shows the 5th example of the drive method in the case of performing stereo
reproduction | regeneration.
It is a figure which shows the 6th example of the drive method in the case of performing stereo
reproduction | regeneration.
It is a figure which shows an example of the drive method in the case of performing surround
reproduction | regeneration.
FIG. 18 is a diagram showing a sound image state in the case of the driving method of FIG. 17;
It is a figure which shows an example in the case of switching drive mode.
It is a figure which shows the sound image state at the time of according to the drive method of
FIG.
It is a figure which shows an example in the case of carrying out change control of the grade of
decorrelation continuously.
11-05-2019
35
It is a figure which shows the other example in the case of switching drive mode.
It is a figure which shows the other example of the speaker system of this invention.
It is a figure which shows the other example of the speaker system of this invention.
It is a figure which shows an example of the drive method of the speaker system of FIG.
It is a figure which shows the other example of the speaker system of this invention.
It is a figure showing a speaker system indicated in patent documents 1 and 2.
It is a figure showing the speaker drive circuit indicated in patent documents 1 and 2.
It is a figure showing the speaker drive circuit indicated in patent documents 1 and 2.
It is a figure which shows the speaker drive circuit described in patent document 2. FIG.
It is a figure which shows the sound image state in the case of the speaker drive method
described in patent document 1, 2 in the case.
Explanation of sign
[0181]
The main part is described in the figure, so it is omitted here.
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36
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