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JPH06245287

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DESCRIPTION JPH06245287
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
loudspeaker apparatus, and more particularly to a loudspeaker apparatus capable of preventing a
vibration of a magnetic circuit or the like due to a reaction force of a diaphragm to obtain a good
acoustic output.
[0002]
2. Description of the Related Art A speaker generally comprises a magnetic circuit comprising a
magnet, a pole, a plate and a yoke, a voice coil disposed in a magnetic gap formed between the
pole and the plate of the magnetic circuit, and a top of the voice coil. And a frame supporting the
periphery of the opening of the diaphragm and mechanically supporting the magnetic circuit,
and allowing the voice current from the voice signal source to flow through the power amplifier
to the voice coil Thus, the diaphragm is vibrated to output sound. Moreover, such a speaker is
used in the state which fixed the flame | frame to the baffle plate of a speaker box.
[0003]
By the way, in the speaker having the above-described configuration, when the diaphragm
vibrates in the axial direction of the voice coil, the magnetic circuit is excited by the reaction
force. As a result, the vibration of the magnetic circuit is transmitted to the baffle plate through
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the frame, and the baffle and the magnetic circuit vibrate, so that the vibration of the baffle
adversely affects the acoustic output taken out by the piston movement of the diaphragm.
Significantly lower the
[0004]
As described above, as a method of suppressing the vibration of the baffle plate by the speaker
reaction force to improve the sound quality, the weight of the magnetic circuit or the like is
sufficiently increased in proportion to the weight of the diaphragm and the voice coil
conventionally. There is known a method of suppressing the vibration of a magnetic circuit or the
like or the vibration of a baffle plate by making a structure in which a speaker reaction force
generated by the vibration of a diaphragm hardly acts on a magnetic circuit or the like. However,
in this method, since the weight of the entire speaker is heavy, it is not easy to carry it, or the
rigidity of the installation place must be increased, which causes various problems in practical
use and is not preferable as a general speaker structure .
[0005]
Therefore, as a speaker for suppressing the vibration of the magnetic circuit and the like due to
the speaker reaction force without increasing the weight of the magnetic circuit and the like, for
example, a speaker having a structure shown in FIG. 10 has been proposed (Japanese Patent
Publication No. 60-6157). In FIG. 10, the speaker 1 includes a first drive means 3 for vibrating
the cone-shaped diaphragm 2, a second drive means 5 for vibrating the weight 4 for canceling
the reaction force of the diaphragm 2, and a frame 6. . The first drive means 3 comprises a
magnetic circuit 3A comprising a magnet 3a, a pole 3b and a yoke 3c, and a voice coil 3d
disposed in the magnetic gap 3B formed in the magnetic circuit 3A and fixed to the top of the
diaphragm 2. The diaphragm 2 and the magnetic circuit 3A are held by the frame 6, and the
frame 6 is attached to the baffle plate 8 of the cabinet 7.
[0006]
The second drive means 5 is integrally fixed to the back of the yoke 3a of the first drive means 3
and comprises a magnetic circuit 5A comprising a magnet 5a, a pole 5b and a yoke 5c, and a
magnetic circuit 5A. The movable coil 5d disposed in the magnetic gap 5B formed in and fixed to
the weight body 4, the supporting member 5C projectingly provided on the yoke 5c, and the
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movable coil 5d and the weight body 4 are pivotable to the support member 5C. It comprises the
damper 5D to support. Further, an audio current is supplied from the audio signal source 9 to the
voice coil 3d of the first driving means 3 through the power amplifier 10, thereby vibrating the
diaphragm 2 to output sound. Further, in the movable coil 5d of the second drive means 5, the
voice signal from the signal source 9 is made to be in reverse phase by the reverse phase circuit
11, and the level of the output signal from this reverse phase circuit 11 is adjusted by the level
adjustment circuit 12. The generated excitation current is supplied through the power amplifier
13 to vibrate the weight 4 so that the reaction force from the diaphragm 2 is offset.
[0007]
However, in the conventional speaker apparatus in which the weight body 4 is vibrated such that
the reaction force from the diaphragm 2 is offset as described above, the vibration of the entire
speaker can be at all frequencies. Vibrations in the frequency band that can not be completely
canceled out in the band and remain uncancelled are transmitted to the baffle plate through the
frame. As a result, although the baffle plate slightly vibrates, it adversely affects the sound output
from the diaphragm and causes the sound quality to deteriorate. The present invention has been
made in view of such circumstances, and it is an object of the present invention to provide a
speaker device capable of preventing a vibration of a magnetic circuit or the like due to a
reaction force of a diaphragm to obtain a good acoustic output. I assume.
[0008]
SUMMARY OF THE INVENTION In order to achieve the above object, the invention according to
claim 1 comprises first and second drives in which a coil is disposed in a magnetic gap formed in
a magnetic circuit. Means, a diaphragm driven by the first drive means, a weight driven by the
second drive means in a direction opposite to the vibration direction of the diaphragm, the
magnetic circuit and the diaphragm A speaker device comprising a frame attached to the cabinet,
wherein the reaction force by the diaphragm is offset by the reaction force by the drive of the
weight body, and a plurality of the speaker devices including the center of gravity of the speaker
A support means is provided for attaching the portion to the cabinet.
[0009]
The invention according to claim 2 comprises first and second drive means having a coil
disposed in a magnetic gap formed in a magnetic circuit, and a diaphragm driven by the first
drive means. A speaker driven with a weight driven by the second drive means in a direction
opposite to the vibration direction of the diaphragm and a reaction by the vibration of the
diaphragm by a reaction by the drive of the weight A signal system for supplying a drive signal
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for canceling a reaction force to the second drive means is provided with an equalizer for
controlling the amplitude and phase of the drive force of the second drive means.
[0010]
The invention according to claim 3 comprises first and second drive means having a coil
disposed in a magnetic gap formed in a magnetic circuit, and a diaphragm driven by the first
drive means. A speaker driven with a weight driven by the second drive means in a direction
opposite to the vibration direction of the diaphragm and a reaction by the vibration of the
diaphragm by a reaction by the drive of the weight Motional feedback such that the vibration of
the magnetic circuit becomes smaller than a reference level in a target frequency range in a
signal system for supplying a drive signal for counteracting the reaction to the second drive
means. A feedback circuit is provided.
[0011]
The invention according to claim 4 comprises first and second drive means having a coil
disposed in a magnetic gap formed in a magnetic circuit, and a diaphragm driven by the first
drive means. A speaker driven with a weight driven by the second drive means in a direction
opposite to the vibration direction of the diaphragm and a reaction by the vibration of the
diaphragm by a reaction by the drive of the weight And an adaptive digital filter having a transfer
function that minimizes the vibration of the magnetic circuit in a predetermined frequency range
in a signal system for supplying a drive signal for counteracting the reaction to the second drive
means. is there.
[0012]
According to the construction described in the first aspect, the support means fixes the plurality
of parts including the center of gravity of the speaker to the cabinet, so that the vibration
transmission to the cabinet is dispersed and the vibration transmission to the baffle plate is
effective. Stop it.
Therefore, the vibration of the baffle plate is reduced, and a speaker excellent in sound quality
can be obtained.
[0013]
According to the configuration of the second aspect, the equalizer adjusts the amplitude and
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phase of the signal applied to the second drive means so that it is canceled with respect to the
vibration of the first drive means due to the reaction force of the diaphragm. Thus, the vibration
of the speaker is reduced, and a speaker excellent in sound quality can be obtained.
[0014]
According to the configuration of the third aspect, the feedback circuit applies motional feedback
to the second drive means so that the vibration of the magnetic circuit is below the reference
level, so that the vibration occurring in the first drive means is generated. It can be canceled
accurately, and a speaker with excellent sound quality can be obtained.
[0015]
According to the configuration of the fourth aspect, since the coefficient of the adaptive digital
filter is corrected such that the vibration of the magnetic circuit is minimized in a predetermined
frequency range, the frequency of the magnetic circuit can be obtained by using this adaptive
digital filter. The characteristics can be made flat.
Therefore, in terms of sound quality, a better speaker can be provided.
[0016]
First Embodiment The first embodiment of the present invention will be described below with
reference to FIG.
In FIG. 1, the same parts as those in FIG. 10 are given the same reference numerals, and the
explanation of the configuration is omitted.
That is, the characteristic part of the present embodiment is that between the coupling surface of
the yoke 3c of the magnetic circuit 3A constituting the first drive means 3 and the yoke 5c of the
magnetic circuit 5A constituting the second drive means 5, The disk-shaped support member 20
is concentrically interposed and fixed, and the peripheral edge portion of the support member 20
is fixed to a support portion 21 extended in the cabinet 7 by a tapping screw or the like.
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In such a first embodiment, the vibrational force to the baffle plate 8 is defined by the moment
by (the vibration component left at the center of gravity position) × (the distance from the
center of gravity position to the mounting position). By supporting the speaker 1 including the
first and second driving means 3 and 5 and the frame 6 and the like to the cabinet 7 via the
support member 20 at a portion near the center of gravity position of the speaker 1 other than
the frame 6, a diaphragm Transmission of the vibration generated by the reaction force of 2 to
the baffle plate 8 can be most effectively suppressed.
As a result, the vibration of the baffle plate 8 is reduced, and a speaker device excellent in sound
quality can be obtained.
[0017]
FIGS. 2A and 2B show a modification of the first embodiment. In FIG. 2A, the upper end portion
of a stand-shaped support member 20A having a substantially reverse T-shaped cross section is
held between the coupling surfaces of the yokes 3c and 5c of the first and second magnetic
circuits 3A and 5A. The lower end portion of the support member 20A is fixed to the cabinet 7 so
that the portion near the center of gravity of the speaker 1 is supported by the cabinet 7. Also in
this modification, the same effect as that of the first embodiment can be obtained.
[0018]
Further, FIG. 2B shows that the yokes 3c and 5c of the first and second magnetic circuits 3A and
5A are supported by the cabinet 7 via separate stand-type support members 20A and 20B. In
such a modification, since the speaker 1 is attached to the cabinet 7 at a plurality of portions
close to its center of gravity, vibration transmission from the speaker 1 to the cabinet 7 (the
baffle plate 8) is dispersed, and the vibration of the baffle plate 8 is generated. As a result, the
influence on the sound quality can be reduced and the rigidity of the cabinet 7 can also be
increased. Further, since the entire weight of the speaker 1 is supported by the support
mechanism provided at the position including the center of gravity, the attachment portion of the
frame 6 to the baffle plate 8 only needs to maintain the degree of sealing. May be closed with a
viscoelastic body such as rubber so as not to transmit vibration. The number of support points of
the speaker in the present invention and the support structure thereof are not limited to those
shown in the above-mentioned embodiment and modification.
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[0019]
Second Embodiment The second embodiment of the present invention will be described with
reference to FIGS. FIG. 3 shows the entire configuration of the speaker apparatus according to
this embodiment. The same reference numerals as in FIG. 10 denote the same parts as in FIG. 10,
and a description thereof will be omitted. Emphasize part. That is, the feature of this embodiment
is that the voice signal from the signal source 9 is reverse phase to the signal supply path for
excitation connecting the movable coil 5 d of the second drive means 5 and the signal source 9.
The circuit 11, a level control circuit 12 for adjusting the level of the signal output from the
reverse phase circuit 11, and a power amplifier 13 for excitation are connected in cascade, and in
addition to these, between the level control circuit 12 and the power amplifier 13 The equalizer
30 is newly connected to control the amplitude and phase of the vibration force of the second
drive unit 5 based on the signal output from the level adjustment circuit 12.
[0020]
In the speaker apparatus having the above-described configuration, the vibration of the first
drive means 3 caused by the reaction force of the diaphragm 2 is controlled by the equalizer 30
in the target frequency range, from the signal source 9 to the second drive means 5. The
amplitude and the phase of the signal applied to the movable coil 5d are adjusted to an ideal
state (the amplitude is equal and the phase is opposite), so the vibration generated by the
reaction force of the diaphragm in the first drive means 3 can be in a wide frequency range Can
be canceled out efficiently, and the remaining of vibration can be reduced.
[0021]
FIG. 4 is a characteristic diagram showing the relationship between frequency and vibration level
in the present embodiment and in the prior art.
In FIG. 4, the curve is the vibration characteristic of the speaker having only the first drive means
3, and the curve is the vibration characteristic of the speaker having the second drive means 5 in
addition to the first drive means 3, Is the vibration characteristic of the speaker using the
equalizer 30 of this embodiment. As apparent from FIG. 4, since the curve uses the second
driving means, the reaction force of the diaphragm can be canceled to some extent compared to
the curve, but the amplitude and phase are perfect over the entire target frequency range.
Because the vibration level in the non-coincident frequency band is large, the residual of the
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vibration due to the reaction force occurs. On the other hand, in the present embodiment, the
amplitude and the phase of the signal applied to the movable coil 5d with respect to the vibration
of the first drive means 3 can be adjusted by the equalizer 30, so the vibration level significantly
decreases as shown by the curve. It is possible to reduce the elimination of vibration due to the
reaction force.
[0022]
FIG. 5 shows a specific configuration example of the equalizer 30. The equalizer 30 includes an
input buffer 30a, a time constant circuit 30b including a resistor, a capacitor, a coil, and the like,
and an output buffer 30c. The equalizer in the present invention is not limited to the one shown
in FIG.
[0023]
Therefore, in the second embodiment, the vibration of the speaker 1 can be reduced over a wide
frequency range, and a speaker device excellent in sound quality can be obtained, and the power
applied to the second drive means 5 is Since each frequency is accurately given, unnecessary
power is not consumed. Further, since the optimum equalizer 30 can be designed in accordance
with the characteristics of the second drive means 5, the design of the second drive means 5 is
simplified.
[0024]
Third Embodiment The third embodiment of the present invention will be described with
reference to FIG. FIG. 6 shows the entire configuration of the speaker apparatus according to this
embodiment. The same reference numerals as in FIG. 10 denote the same parts as in FIG. 10, and
a description thereof will be omitted. Emphasize part. That is, the feature of this embodiment is
that the voice signal from the signal source 9 is reverse phase to the signal supply path for
excitation connecting the movable coil 5 d of the second drive means 5 and the signal source 9.
The circuit 11 and the power amplifier 13 for excitation are connected in cascade, and in
addition to these, a variable for controlling the amplitude of the signal output from the negative
phase circuit 11 to the power amplifier 13 between the negative phase circuit 11 and the power
amplifier 13 By providing the gain amplifier 40 and feeding back an error signal between the
vibration of the speaker 1 and the reference value to the variable gain amplifier 40, control is
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performed so that the vibration of the speaker 1 becomes smaller than the reference value in the
target frequency range. The feedback circuit 41 is provided.
[0025]
The feedback circuit 41 comprises a pickup 41a for detecting the vibration of the speaker 1, a
preamplifier 41b for amplifying the pickup signal, a detector 41c for converting the amplified
output into a direct current, and comparing the direct current output with the reference voltage
Vref. And the comparator 41 d that outputs the error signal to the variable gain amplifier 40.
[0026]
In the third embodiment, the gain of the variable gain amplifier 40 is automatically adjusted by
the error signal output from the feedback circuit 41, and the vibration level of the speaker 1
detected by the pickup 41a is higher than the reference level. Since the motional feedback is
made so as to always be small, the adjustment of the level adjustment circuit 12 and the
equalizer 30 as shown in the second embodiment becomes unnecessary, and the problem of the
unerased oscillation due to the adjustment deviation is eliminated.
As a result, the vibration level of the speaker 1 can be further reduced than the characteristic of
the curve shown in FIG. 4, and a speaker device excellent in sound quality can be obtained.
Further, since the power to be applied to the second driving means 5 is accurately given for each
frequency, unnecessary power is not consumed, and an optimum equalizer is designed according
to the characteristics of the second driving means 5 Since there is no need, the design of the
second drive means 5 is simplified.
[0027]
(Fourth Embodiment) A fourth embodiment of the present invention will be described with
reference to FIGS. FIG. 7 shows the entire configuration of the loudspeaker apparatus in this
embodiment. The same reference numerals are given to the same parts as in FIG. 10 to omit the
description of the configuration, and the features of this embodiment different from FIG.
Emphasize part. That is, the characteristic part of the present embodiment is that the audio signal
from the signal source 9 is provided between the signal source 9 and the power amplifier 13 for
supplying power for excitation to the movable coil 5d of the second drive means A / D converter
50 for converting into a digital signal, and an inverse characteristic to the vibration cancellation
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system including the second driving means 5 so that the vibration of the speaker 1 due to the
reaction force of the diaphragm 2 becomes minimum in a predetermined frequency range
Adaptive digital filter 51 having a coefficient (transfer function) obtained from the impulse
response of the D / A converter 52, and a D / A converter 52 which converts the digital signal
output from the adaptive digital filter 51 into an analog signal and outputs it to the power
amplifier 13. And are connected in cascade.
[0028]
FIG. 8 is a block diagram for determining the coefficient of the adaptive digital filter 51. As
shown in FIG. In FIG. 8, the noise signal output from the M-sequence noise source 61 is supplied
to a voice coil (not shown) via the D / A converter 62 and the power amplifier 10 to drive the
speaker 1. On the other hand, the noise signal from the M-sequence noise source 61 is applied to
the FIR filter 63, and the filter output is applied to the addition unit 64. The vibration of the
speaker 1 due to the reaction force of the diaphragm 2 is detected by the pickup 65, amplified by
the preamplifier 66, converted into a digital quantity by the A / D converter 67, and added to the
adder 64. In this addition unit 64, the error signal (error) obtained from this is input to the filter
coefficient adjustment unit 68, so that the coefficient of the FIR filter 63 is re-set so that the
mean square error of the filter output and the pick-up detection output is minimized. adjust.
Therefore, by using the adaptive digital filter 51 having the coefficients thus obtained, it is
possible to obtain a highly accurate and highly accurate correction system. Once the coefficients
of the FIR filter 63 have been readjusted to an optimal value, the pickup means becomes
unnecessary. Therefore, the pickup means is used only at the time of coefficient adjustment.
[0029]
FIG. 9 is a characteristic diagram showing the relationship between frequency and vibration level
in the fourth embodiment and in the prior art. In FIG. 9, the curve shows the vibration
characteristic according to the present embodiment, and as is apparent from this, flat frequency
characteristics can be obtained over a wide frequency range. The curves in FIG. 9 indicate
conventional vibration characteristics.
[0030]
Therefore, in the fourth embodiment, the coefficients of the FIR filter 63 of the adaptive digital
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filter 51 are readjusted so that the mean square error of the filter output of the adaptive digital
filter 51 and the pickup output is minimized. Because the vibration generated by the first drive
means 3 is canceled by the adaptive digital filter 51 in the state having the above, the vibration
of the speaker 1 can be accurately reduced over a wide frequency range, and the sound quality is
further enhanced. An excellent speaker device is obtained. In addition, accurate equalizers
suitable for the first and second drive means 3 and 5 can be easily obtained, and the adjustment
thereof is also unnecessary. Furthermore, since the power to be applied to the second drive
means 5 is given extremely accurately for each frequency, unnecessary power is not consumed,
and an optimum equalizer is designed according to the characteristics of the second drive means
5 Since it is not necessary to do so, the design of the second drive means 5 is simplified.
[0031]
Although the magnetic circuits of the first and second drive means 3 and 5 are separately
provided in each of the above embodiments, the present invention is not limited to this. For
example, as shown in Japanese Patent Publication No. S60-6157, the magnetic circuit of the first
and second drive means is shared, and the magnetic circuit of each drive means is formed into an
inner magnet type or an outer magnet type. The coil forming the second driving means may be
fixed, and a part of the magnetic circuit may be movable as a weight.
[0032]
As described above, according to the first aspect of the present invention, since a plurality of
points including the center of gravity of the speaker are attached to the cabinet by the support
means, vibration force transmission to the baffle plate can be achieved. While being able to
suppress most effectively, the rigidity of the cabinet is increased and the vibration transmission
to the cabinet (baffle plate) is dispersed, so that the vibration of the speaker is reduced, and a
speaker device excellent in sound quality can be obtained. it can.
[0033]
According to the second aspect of the present invention, an equalizer is provided in the signal
system for supplying the drive signal for canceling the reaction force to the second drive means,
and the amplitude of the drive force of the second drive means and the equalizer Since the phase
is controlled, the vibration of the speaker can be reduced over a wide frequency range, and a
speaker device excellent in sound quality can be obtained, and the power to be applied to the
second driving means is for each frequency. As it is accurately provided, it does not consume
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unnecessary power.
In addition, since the optimum equalizer can be designed in accordance with the characteristics
of the second drive means, the design of the second drive means is simplified.
[0034]
According to the third aspect of the present invention, in the signal system for supplying the
drive signal for canceling the reaction force to the second drive means, the vibration of the
magnetic circuit becomes smaller than the reference level in the target frequency range. Since
the feedback circuit for motional feedback is provided, the vibration of the speaker can be
reduced over a wide frequency range, and a speaker device excellent in sound quality can be
obtained. In addition, since the power applied to the second drive means is accurately provided
for each frequency, unnecessary power is not consumed, and it is necessary to design an
optimum equalizer according to the characteristics of the second drive means. Because it is not,
the design of the second drive means is simplified.
[0035]
According to the invention as set forth in claim 4, the coefficient (transfer function) of the
adaptive digital filter is corrected such that the vibration of the speaker due to the reaction force
of the diaphragm is minimized in the predetermined frequency range, and the adaptive digital
having this coefficient Since the second drive means is controlled through the filter, the vibration
of the speaker can be accurately reduced over a wide frequency range, and a speaker device with
even better sound quality can be obtained. In addition, it is possible to easily obtain an accurate
equalizer suitable for the first and second drive means, and to make adjustment thereof
unnecessary.
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