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JP2001157290

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2001157290
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
bass reproduction speaker apparatus for obtaining high bass reproduction capability while being
a small cabinet.
[0002]
2. Description of the Related Art Generally, with regard to low frequency reproduction of a
speaker, there is an inverse relationship between the cabinet volume V, the low frequency
reproduction limit frequency fc and the efficiency .mu. It is known that regeneration is in
principle very difficult.
[0003]
Also, if the stiffness of air in the cabinet can be reduced by using negative stiffness to increase
the volume V in the cabinet equivalently, the concept of being able to escape from this limitation
and improve the low-range regeneration ability is also old. It was from.
But the reality is that there was no good way to embody this.
[0004]
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1
Here, the prior art proposed in the past to embody this concept will be described. This prior art is
disclosed in U.S. Pat. No. 281 0021 (LOW FREQUENCY LOUDSPEAKER, Patented Oct. 15, 1957)
and U.S. Pat. 19, 1986). The basic principle concept is the same in both cases, but the latter is
more advanced than the former, so this will be explained.
[0005]
8 and 9 show the configuration of this conventional bass reproduction speaker device. In FIG. 8
and FIG. 9, reference numeral 51 denotes a dynamic type speaker unit, which includes a field
part 51a, a frame 51b, a voice coil 51c, a damper 51d, an edge 51e and a diaphragm 51f.
Reference numeral 52 denotes a closed cabinet, to which a speaker unit 51 is attached.
[0006]
Reference numeral 51i denotes a reinforcing ring for reinforcing the diaphragm 51f, which is
attached to the outer peripheral portion of the diaphragm 51f. Reference numeral 54 denotes a
pair of springs in which two upper and lower bowed plate springs are opposed, and both ends
thereof are fixed to the movable side supporting member 51g on the reinforcing ring 51i and the
frame 51b while being compressed. It is attached to the fixed side support member 52a of the
part. Further, in the conventional example, three sets of the springs 54 are provided
symmetrically about the central axis of the vibration direction of the diaphragm 51 f.
[0007]
If fixed side support member 52a is arranged on both sides of movable side support member
51g, if it is only one side, axial direction rotational force is generated in reinforcing ring 51i, that
is, diaphragm 51f, and stress in the support system of speaker unit 51 Because it leads to
damage.
[0008]
58 is a means for detecting the displacement of the diaphragm 51f from the vibration center
position, and in the specification of this US Pat. No. 4,607,382, as a detection method, a
capacitance detection method, an inductance detection method, a light amount detection method,
a cabinet internal air pressure detection It mentions the method.
01-05-2019
2
[0009]
Reference numeral 59 denotes a control device for correcting the displacement of the diaphragm
51f from the vibration center position, and operates in accordance with the output signal from
the detection means 58.
In FIG. 8, reference numeral 60 denotes an intake / exhaust pump, which operates according to
an output signal of the control device 59.
Further, in FIG. 9, the control device 59 is a high-power power amplifier provided separately
from the normal power amplifier for amplifying the source signal, and is connected to the
speaker unit 51.
[0010]
The operation of the conventional bass reproduction speaker apparatus configured as described
above will be described with reference to FIGS. 10 and 11 as well. 10 and 11 show the action of
negative stiffness by the spring 54. FIG. In FIG. 10, 52a is a fixed side support member, 51g is a
movable side support member, 54 is a pair of springs compressed and attached by both. That is,
one unit of the spring 54 shown in FIGS. 8 and 9 is shown.
[0011]
When the position of the movable support member 51g is at the exact center of the vibration
displacement direction x, that is, x = 0, the direction of the repulsive force of the spring 54 acting
between the movable support member 51g and the fixed support member 52a is the x direction.
Since the force vector component in the x direction is at right angles and in the x direction, no
force in the x direction is generated.
[0012]
However, when the position of the movable support member 51g deviates from the center, that
is, when it comes to the position of Δx in FIG. 10, for example, the repulsion of the spring 54
acting between the movable support member 51g and the fixed support member 52a. Since the
01-05-2019
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direction of the force is not perpendicular to the x direction, a force vector component in the x
direction is generated, and a force is generated to push the movable support member 51g in the
Δx direction.
[0013]
Assuming that, in addition to the support system of the speaker unit 51 such as the edge 51e, the
force that the sealed air in the cabinet 52 gives to the vibration system of the speaker unit 51 is
F1 when the movable side support member 51g is displaced by Δx. Needless to say, the polarity
of the stiffness of the force of F1 is positive because it tries to pull the movable side support
member 51g back to the center of x = 0.
[0014]
On the other hand, assuming that the force generated when the spring 54 is displaced by Δx is
F2, the direction of F2 is opposite to that of F1 because it tries to push the movable support
member 51g in the displacement direction, and the polarity of the stiffness of the force of F2 Is
negative.
[0015]
Thus, the spring 54 generates negative stiffness.
The effect of this negative stiffness is shown in FIG.
In FIG. 11, the broken line indicates the relationship between the force that the positive stiffness
of the speaker unit support system and the air inside the cabinet gives to the vibration system,
that is, the movable side support member 51g, and the displacement in the x direction. The solid
line indicates the relationship between the force applied to the movable support member 51g
and the displacement in the x direction. The solid line indicates the relationship between the
force applied to the movable support member 51g and the displacement in the x direction.
[0016]
The positive stiffness is F1 / Δx, which corresponds to the slope of the dashed line.
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The negative stiffness is F2 / Δx, which corresponds to the slope of the dashed dotted line.
The total stiffness is Ft / Δx, that is, (F1-F2) / Δx, which corresponds to the slope of the solid
line. This slope is smaller than that of the dashed line and the total stiffness will be reduced.
Thus, since the stiffness finally applied to the movable side support member 51g is reduced by
the function of the negative stiffness, an effect equivalent to the reduction of the stiffness of the
air inside the cabinet can be obtained. Therefore, since the stiffness of the air inside the cabinet is
inversely proportional to the volume inside the cabinet, an effect that the internal volume of the
cabinet 52 is equivalently increased can be obtained.
[0017]
In order to obtain this effect sufficiently, the negative stiffness of the spring 54 must be
increased. However, if this is done, the support system of the speaker unit 51 loses this negative
stiffness force, and the vibration system of the speaker unit 51 is biased to a position deviated
from the displacement center position x = 0, so normal operation can not be performed. .
[0018]
Although the sum of the stiffness of the internal air of the cabinet 52 and the stiffness of the
support system of the speaker unit 51 is larger than the negative stiffness, a slight amount of air
leakage always occurs from the cabinet 52 and the diaphragm 51f. Therefore, if the negative
stiffness exceeds the stiffness of the support system of the speaker unit 51, the vibration system
can not stop at the displacement center position.
[0019]
The detection means 58, the control device 59, and the intake and exhaust pump 60 shown in
FIGS. 8 and 9 are provided to prevent and correct this. For example, in the configuration of FIG.
8, when the average vibration displacement center of the vibration system of the speaker unit 51
is biased forward than the original center position (position of x = 0 in FIG. 10), this displacement
is biased. Is detected and a signal is generated to send an output signal to the control device 59.
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Then, the control device 59 discharges the air suction and discharge pump 60 to discharge the
air in the cabinet 52, and pulls the diaphragm 51f of the speaker unit 51 back to the original
displacement center position.
[0020]
Conversely, when the vibration system is biased backward, the intake and exhaust pump 60
performs suction operation to suck air into the cabinet 52 and push the vibration system of the
speaker unit 51 back to the original displacement center position.
[0021]
Further, in the configuration of FIG. 9, when the vibration system of the speaker unit 51 is biased
forward, the control device 59, that is, the power amplifier supplies a current to the voice coil
51c of the speaker unit 51 to move the vibration system to the original displacement center
position. Pull back to.
Conversely, when the vibration system is biased backward, the controller 59 supplies a current in
the reverse direction to the voice coil 51c of the speaker unit 51 to push the vibration system
back to the original displacement center position.
[0022]
The voice coil 51c needs to have a double voice coil configuration, that is, a voice coil for flowing
the current of the control device 59 and a voice coil for reproducing the source signal.
[0023]
Therefore, while correcting the deviation of the displacement direction of the vibration system of
the speaker unit 51 by the bass reproduction speaker device of the conventional configuration as
described above, the internal volume of the cabinet is equivalently increased by negative
stiffness, and low-pass reproduction ability Can be improved.
A more detailed description of the equivalent increase of the volume inside the cabinet by the
negative stiffness and the principle of the improvement of the low range reproduction capability
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will be given in the embodiment of the present invention.
[0024]
However, in the above-described conventional configuration, a power amplifier different from the
suction and exhaust pump and the power amplifier for reproducing the source signal is used to
correct the deviation in the displacement direction of the vibration system of the speaker unit 51.
The system is complicated and large-scaled, and the cost is high. In addition, mechanical fatigue
is likely to occur in the spring 54, so that there is also a problem that the reliability is poor.
[0025]
That is, although there was a concept of equivalently increasing the volume in the cabinet to
improve the low frequency reproduction capability, it was not practical in the conventional bass
reproduction speaker device according to the prior art.
[0026]
The present invention solves the above-mentioned conventional problems, and is a low-cost,
high-reliability, simple structure, and a bass reproduction with excellent low-pass reproduction
ability by equivalently increasing the volume inside the cabinet. It aims at providing a speaker
apparatus.
[0027]
SUMMARY OF THE INVENTION In order to achieve the above object, a bass reproduction
speaker apparatus according to the present invention comprises a speaker unit, means for giving
negative stiffness to a vibration system of the speaker unit, and the speaker unit. In a low-sound
reproduction speaker device provided with a cabinet, detection means for generating an
electrical signal according to the displacement of the vibration system of the speaker unit, and a
power amplifier for reproducing a source signal for driving the speaker unit The power amplifier
includes a feedback circuit for feeding back an electric signal, and the power amplifier supplies
power to the speaker unit to correct deviation of the displacement direction of the vibration
system of the speaker unit in addition to source signal power.
[0028]
A movable magnet that moves with the vibration system of the speaker unit and a Hall element
that detects the magnetism of the movable magnet are the detection means.
01-05-2019
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[0029]
Furthermore, the means for giving negative stiffness to the vibration system of the speaker unit
is compressed and attached to a plurality of substantially central axis symmetrical plural points
between the central portion of the vibration system of the speaker unit and the outer periphery
of the speaker unit. It is used as a plate-shaped spring.
Alternatively, the means for giving negative stiffness to the vibration system of the speaker unit
is a movable magnet that moves together with the vibration system of the speaker unit, and a
fixed magnet that applies a force in the vibration displacement direction of the speaker unit to
the movable magnet. It is a thing.
[0030]
According to the present invention, it is possible to realize a low-cost, high-reliability practical,
low-frequency bass reproduction speaker device having excellent low-pass reproduction
capability according to the present invention.
[0031]
The invention according to claim 1 of the present invention is a bass unit comprising a speaker
unit, means for giving negative stiffness to a vibration system of the speaker unit, and a cabinet
for housing the speaker unit. In the reproduction speaker device, a detection means for
generating an electric signal according to a displacement of a vibration system of the speaker
unit, and a feedback for returning the electric signal from the detection means to a power
amplifier for reproducing a source signal for driving the speaker unit. A circuit is provided, and
the power amplifier is configured to supply power to the speaker unit to correct deviation of the
displacement direction of the vibration system of the speaker unit in addition to source signal
power, and the configuration is simple and low cost. Thus, it is possible to realize a bass
reproduction speaker device having a practical low frequency reproduction capability.
[0032]
The invention according to claim 2 of the present invention is the bass reproducing apparatus
according to claim 1, wherein the detection means is a movable magnet that moves with the
vibration system of the speaker unit, and a Hall element that detects the magnetism of the
movable magnet. Thus, it is possible to realize a bass reproduction speaker device in which the
01-05-2019
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configuration of the detection means is simplified.
[0033]
The invention according to claim 3 of the present invention is characterized in that the means for
giving negative stiffness to the vibration system of the speaker unit is a substantially center
between the central portion of the vibration system of the speaker unit and the periphery of the
speaker unit. It is set as the bass reproduction | regeneration speaker apparatus of Claim 1 or 2
which was made into the plate-like spring compressed and attached to a plurality of axiallysymmetrical places, and a highly reliable bass reproduction | regeneration speaker apparatus is
realizable.
[0034]
The invention according to claim 4 of the present invention is characterized in that the means for
giving negative stiffness to the vibration system of the speaker unit is a movable magnet moving
with the vibration system of the speaker unit, and vibration of the speaker unit with respect to
the movable magnet. The bass reproduction speaker apparatus according to claim 1 or 2,
wherein the fixed magnet applies a force in the direction of displacement. A bass reproduction
speaker apparatus having high reliability can be realized.
[0035]
The invention as set forth in claim 5 of the present invention is the bass sound reproduction
speaker device according to any one of claims 1 to 4, further comprising means for holding the
vibration system of the speaker unit near the center position in the displacement direction when
not operating. Thus, it is possible to realize a long-life bass reproduction speaker device with less
change over time.
[0036]
The invention according to claim 6 of the present invention uses a self-holding type solenoid as a
means for holding the vibration system of the speaker unit in the vicinity of the center position in
the displacement direction when not operating. Thus, it is possible to realize a bass reproduction
speaker device that can be put into operation quickly.
[0037]
The invention according to claim 7 of the present invention is the one according to claim 6,
wherein the operating current of the self holding solenoid is supplied through a capacitor, and
the return current of the self holding solenoid is supplied by discharging the capacitor. As a bass
01-05-2019
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reproduction speaker apparatus of the present invention, a highly safe bass reproduction speaker
apparatus can be realized.
[0038]
The invention according to claim 8 of the present invention is provided with means for reducing
the negative stiffness of the means for giving negative stiffness to the vibration system of the
speaker unit when not operating. A bass reproduction speaker apparatus can be realized, and a
long life bass reproduction speaker apparatus with less change over time can be realized.
[0039]
The invention as set forth in claim 9 of the present invention is characterized in that it comprises
means for changing the stiffness of the means for giving negative stiffness to the vibration
system of the speaker unit, and the bass reproduction speaker device according to any one of
claims 1 to 8. Thus, it is possible to realize a bass reproduction speaker device capable of
changing low frequency characteristics.
[0040]
Hereinafter, the bass reproduction speaker device of the present invention will be described
based on a specific embodiment.
[0041]
(First Embodiment) The structure of a bass reproduction speaker apparatus according to the first
embodiment is shown in FIG.
In FIG. 1, a speaker unit 1 including a field portion 1a, a frame 1b, a voice coil 1c, a damper 1d,
an edge 1e, a diaphragm 1f, and a movable supporting member 1g which also serves as a dust
cap is attached to a closed cabinet 2. ing.
The movable magnet 3 is attached to the bobbin of the voice coil 1c, and moves with the
vibration system of the speaker unit 1 such as the voice coil 1c and the diaphragm 1f.
[0042]
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10
The movable side support member 1g is attached to the tip of the long-extended bobbin of the
voice coil 1c.
The fixed side support members 2a are fixed at four positions symmetrical with respect to the
central axis on the outer peripheral side of the frame 1b of the cabinet 2.
Between the stationary support member 2a and each movable support member 1g, a pair of
springs 4 having bowed flat springs facing each other is attached so as to be compressed from
both ends thereof.
That is, the spring 4 applies a repulsive force to the movable support member 1g and the fixed
support member 2a, and the movable support member 1g, that is, the vibration system of the
speaker unit 1 according to the same principle as the prior art described above. It gives negative
stiffness.
[0043]
The four springs 4 are all the same and are mounted at symmetrical positions, so the repulsive
force is balanced in the horizontal direction, and the movable side support member 1g is held at
the horizontal center. .
[0044]
In the vicinity of the movable magnet 3, a Hall element 5 is disposed as a detection unit that
generates an electric signal according to the displacement of the vibration system.
The speaker unit 1 is driven by a power amplifier 6 for source signal reproduction.
The electric signal output from the hall element 5 is fed back to the power amplifier 6 by the
feedback circuit 5a, and the power for correcting the deviation in the displacement direction of
the vibration system of the speaker unit 1 is added to the source signal power. Supplied.
01-05-2019
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[0045]
Hereinafter, the materials, dimensions, performance, circuit configuration and the like of the
components of the bass reproduction speaker device will be specifically described.
[0046]
The aperture of the speaker unit 1 is 18 cm.
The field portion 1a uses a ferrite magnet having a diameter of 70 mm.
The frame 1b is 18 cm in diameter and made of iron plate.
The diameter (nominal diameter) of the voice coil 1c is 25 mm.
The material of the edge 1e is urethane foam and is in the shape of a down roll.
The diaphragm 1f is a cone made of paper.
The material of the movable side support member 1g is resin.
[0047]
The cabinet 2 is a closed type and has a small internal volume of 10 liters.
The material of the fixed side support member 2a is resin.
The bowed leaf spring 4 has a length of 10 cm in the attached state.
01-05-2019
12
The width of the spring 4 is 1 cm and the material is a phosphor bronze plate.
[0048]
Here, the equivalent increase of the volume in the cabinet by the negative stiffness and the
principle of the improvement of the low-range regeneration capacity will be described in more
detail. Assuming that the speaker unit effective vibration mass is M, and the lowest resonance
frequency in the single-piece free air state is f0, the stiffness Ks of the support system (damper or
edge) of the speaker unit is Ks = M × (2πf0) 2. Further, assuming that the effective vibration
radius of the speaker unit is a, the sound velocity of air is c, the air density is ρ, and the volume
in the cabinet is V, the stiffness Kc given to the speaker unit vibration system by the air in the
cabinet is Kc = ρc2 (πa) It is a 2 / V ... type. And, in the state of being attached to the cabinet,
the stiffness of Ks + Kc works on the speaker unit vibration system. Assuming that the lowest
resonance frequency at this time is f1, f1 = (Ks + Kc) 1/2 / 2πM1 / 2.
[0049]
Here, the magnitude of negative stiffness is Kn. Then, the stiffness acting on the vibration system
of the speaker unit is Ks + Kc-Kn, which corresponds to the stiffness of air in the cabinet
changing from Kc to Kc-Kn. Since the stiffness of the air in the cabinet is inversely proportional
to the internal volume according to the equation, this is equivalent to an increase in the volume
in the cabinet from 1 / Kc to 1 / (Kc-Kn).
[0050]
The lowest resonance frequency of the speaker unit attached to the cabinet becomes f1 = (Ks +
Kc−Kn) 1/2 / 2πM1 / 2 by the negative stiffness working, the lowest resonance frequency is
{(Ks + Kc−Kn) / (Ks + Kc)} 1/2 times lower, that is, the lower reproduction limit frequency is
expanded accordingly, and the lower reproduction capability is improved.
[0051]
In the case where the negative stiffness technique is not used, in order to lower the lowest
resonance frequency, the effective vibration mass must be increased or the effective vibration
01-05-2019
13
area must be decreased, which leads to a decrease in efficiency.
On the other hand, if the negative stiffness is used, the lowest resonance frequency can be
lowered without such a thing, so that the low band can be expanded without lowering the
efficiency.
[0052]
In accordance with the principle described above, the effects of equivalent increase of the volume
inside the cabinet and improvement of the low-range regeneration ability of this embodiment will
be described. In the present embodiment, the minimum resonance frequency of the speaker unit
1 is 60 Hz and the effective vibrating mass is 15 g when the compression of the spring 4 is
released to generate no negative stiffness. The effective radius of vibration is 70 mm. That is, the
support system stiffness Ks of the speaker unit is Ks = 2130 (N / m) according to the equation.
According to the equation, the stiffness Kc given by the air in the cabinet 2 is Kc = 3290 (N / m).
That is, Ks + Kc = 5420 (N / m). And the lowest resonance frequency f1 of the speaker unit 1 in
the state attached to the cabinet 2 is calculated with f1 = 96 Hz from Formula, and an actual
value is also this.
[0053]
The negative stiffness Kn obtained when the spring 4 is compressed and attached is 2800 (N /
m), which exceeds the stiffness Ks = 2130 (N / m) of the support system of the speaker unit 1.
The total stiffness is Ks + Kc-Kn = 5420-2800 = 2620 (N / m), and in the first embodiment, the
lowest resonance frequency, that is, the lower frequency reproduction limit frequency can be
greatly expanded from 96 Hz to 67 Hz. did it.
[0054]
This is equivalent to an increase of the internal volume of the cabinet from 1/3290 to 1 / (32902800) = 1/490. That is, the internal volume of the cabinet 2 is equivalently increased several
times.
01-05-2019
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[0055]
Next, the configuration for correcting the deviation of the displacement direction of the vibration
system of the speaker unit 1 will be described in detail.
[0056]
The dimension of the movable magnet 3 is 5 mm in length and width, 3 mm in thickness, and the
material is ferrite.
The movable magnet 3 is magnetized in the longitudinal direction, that is, in the vertical height
direction in FIG. 1, and the upper side is an N pole and the lower side is an S pole. The Hall
element 5 is disposed in the vertical direction near the longitudinal center of the movable magnet
3. The distance between the two is about 3 mm.
[0057]
The Hall element 5 generates an output signal in accordance with the magnetic flux vector
generated in the horizontal direction by the movable magnet 3. At the longitudinal center
position of the movable magnet 3, since the magnetic flux passes vertically from the N pole to the
S pole directly below, the horizontal magnetic flux vector becomes zero. Therefore, when the
longitudinal center position of the movable magnet 3 and the longitudinal center position of the
Hall element 5 coincide with each other, no signal is output because the magnetic flux passing
horizontally through the Hall element 5 is zero.
[0058]
When the movable magnet 3 is displaced either up or down, the magnetic flux distribution
becomes asymmetric at the position of the Hall element 5, and simply speaking, either the N pole
side or the S pole side of the movable magnet 3 approaches, so the horizontal direction Magnetic
flux vector is generated. At this time, an electric signal is generated from the Hall element 5.
Needless to say, if the Hall element 3 generates a positive electrical signal when, for example, the
N pole side approaches, when the S pole side approaches, the direction of the magnetic flux
vector in the horizontal direction is reversed, and a negative electrical signal is generated. That is,
with this configuration, an electrical signal according to the displacement of the vibration system
01-05-2019
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of the speaker unit 1 can be obtained.
[0059]
When the average vibration displacement center of the vibration system of the speaker unit 1 is
at the original center position, that is, there is no deviation in the displacement direction, the Hall
element 5 is generated when AC power of low frequency is applied to the speaker unit 1 The
electrical signal becomes symmetrical with respect to the zero level on the plus side and the
minus side, and integrating this makes the electrical signal zero. However, when a deviation in
the displacement direction occurs in the vibration system, either the plus side or the minus side
increases (that is, a bias occurs), so that an electrical signal is generated even when integrated.
[0060]
Then, in the present embodiment, for example, when the vibration system of the speaker unit 1
starts to be biased to one side, the current in the direction of returning it back to the reverse
direction, that is, the original displacement center position is supplied to the speaker unit 1 from
the power amplifier 6 Thus, the Hall element 5 and the feedback circuit 5a are configured.
[0061]
FIG. 2 shows an example of a circuit diagram of the feedback circuit 5a including the detection
means 5, the feedback circuit 5a and the power amplifier 6 according to the present
embodiment.
In FIG. 2, terminals 1 and 3 of the Hall element 5 are driving current supply terminals. Reference
numerals 2 and 4 denote output terminals, and a detection voltage is generated at both ends.
OP1 is a buffer amplifier op amp, and OP2 is an integration circuit op amp. P-AMP is a general
audio IC power amplifier, and its output is 30 W.
[0062]
C3 is an integrating capacitor, and the amplification gain of OP2 attenuates as the frequency
becomes higher. As a result, feedback is applied only to the very low frequency component signal
01-05-2019
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corresponding to the biased movement of the vibration system of the speaker unit 1. In other
words, since the feedback is not applied to the movement of the vibration system with a bass of
several tens Hz or more of an audio source such as music, the bass is not adversely affected. VR
is a volume for offset adjustment, and when the vibration system of the speaker unit 1 is at the
original center position, the output voltage of the feedback circuit can be adjusted to zero or the
like.
[0063]
The feedback circuit 5a and the feedback circuit 5a are supplied so that the current
corresponding to the very low frequency component signal fed back to the + terminal of P-AMP
from the feedback circuit 5a, that is, the power for correcting the deviation in the displacement
direction of the vibration system can be supplied to the speaker 1. The connected P-AMP portion
is in a DC amplifier configuration.
[0064]
However, a DC cut capacitor C1 is inserted between the terminal IN receiving the source signal
and P-AMP, and the power amplifier 6 as a whole operates in the same manner as an ordinary
audio power amplifier.
That is, with only one power amplifier 6, both of the source signal power of audio and the power
for correcting the deviation of the displacement direction of the vibration system can be supplied
to the speaker unit 1.
[0065]
With such a configuration, the speaker unit 1 always receives a slight deviation in the
displacement direction of the vibration system, and servo is held at the center position in the
original displacement direction. Even if the negative stiffness is large, the average of the vibration
system is averaged. An extremely stable motion was obtained with the displacement center
position held at the original center position.
[0066]
That is, in the present embodiment, it is not necessary to separately provide a conventional
01-05-2019
17
intake and exhaust pump and a control power amplifier in order to correct the deviation in the
displacement direction of the vibration system.
Of course, the voice coil 1c of the speaker unit 1 need not be a double voice coil. Further, the
configurations of the detection means 5 and the feedback circuit 5a are simple, and all the used
parts are inexpensive.
[0067]
In the conventional configuration described in FIG. 8, when the speaker unit 51 has the same 18
cm diameter, the length of the spring 54 attached between the movable side support member
51g and the fixed side support member 52a is only about 5 cm. Although this can not be
obtained, in the first embodiment, the spring 4 is attached between the central portion of the
vibration system of the speaker unit 1 and the outer peripheral portion of the frame 1b, that is,
the movable side support member 1g and the fixed side support member 2a. The mechanical
fatigue of the spring 4 is very small because the length of the spring 4 attached between the two
can be as long as 10 cm.
[0068]
Therefore, as described above, according to the present embodiment, it is possible to realize a
low-cost, high-reliability, practical low-frequency bass reproduction speaker device having
excellent low-pass reproduction capability with a simple configuration.
[0069]
Although the movable magnet 3 is attached to the voice coil 1c in the present embodiment, it
may be attached to the other vibration system part of the speaker unit 1.
Further, an elastic body or the like may be interposed between the movable magnet 3 and the
vibration system of the speaker unit 1, and the movable magnet 3 and the vibration system may
move together in the low frequency range.
However, it is better not to bring the Hall element 5 too close to the field part 1a. This is because
the magnetic flux leaking from the field portion 1a affects the magnetic field.
01-05-2019
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[0070]
Further, although the speaker unit 1 is a normal electrodynamic type in the present embodiment,
it can be applied to a speaker unit of other electroacoustic conversion type such as a motor drive
type or an electromagnetic type.
[0071]
Further, although the means for giving negative stiffness is a mechanical means using a spring in
this embodiment, it is needless to say that a magnetic means may be used as described in the
second embodiment.
In addition, electrostatic means utilizing the repulsive force of charges of the same polarity may
be considered.
[0072]
Further, in the present embodiment, four springs 4 are disposed symmetrically about the central
axis, but may be three or other numbers. If the negative stiffness generated by the spring 4 is not
very large, it may be two.
[0073]
In the embodiment, the spring 4 is a bow-shaped plate spring made of phosphor bronze, but
other materials and shapes are also possible. For example, when the material is a shape memory
alloy, metal fatigue is reduced and the reliability is improved.
[0074]
Further, although the fixed side support member 2a is fixed to the cabinet 2 in the present
embodiment, the length of the spring 4 can be sufficiently secured even when attached to the
outer peripheral portion of the frame 1b of the speaker unit 1.
01-05-2019
19
[0075]
Further, in the present embodiment, the cabinet 2 is of the closed type, but if the rear of the
speaker unit is closed, the cabinet 2 can be applied to a cabinet type other than the closed type,
such as the Kelton type.
[0076]
Further, although the Hall element 5 is used as the detection means in the present embodiment,
it goes without saying that other methods, for example, detection means of the following method
are also possible.
That is, an optical method that detects a change in light amount with a CDS, a photodiode, a
phototransistor, etc., an electrostatic method that detects an electrostatic capacitance between a
movable side electrode and a fixed side electrode attached to a vibration system of a speaker
unit, a speaker unit In the induction system or the like, a change in inductance of a coil is
detected by an iron plate attached to the vibration system of the above item and a coil disposed
in the vicinity thereof.
[0077]
However, when a Hall element is used as the detection means, the simplest structure can be
obtained.
This is because in the optical method, electrostatic method, and induction method, in order to
determine the upper and lower positions from the center position of the displacement of the
vibration system of the speaker unit 1, it is necessary to arrange two upper and lower detection
elements. In the first embodiment, since the movable magnet 3 has two polarities of N pole and S
pole, the Hall element 5 generates a plus or minus electric signal according to the displacement
of the vibration system of the speaker unit 1. That is, the upper and lower portions of the
displacement of the vibration system of the speaker unit 1 can be determined by one detection
element.
[0078]
Further, although the Hall element 5 is used as the detection means in the present embodiment,
01-05-2019
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the feedback circuit can be simplified by using a Hall IC instead.
[0079]
In the first embodiment, signal feedback from the feedback circuit 5a to the power amplifier 6 is
performed purely electrically, but may be performed via a photocoupler.
[0080]
Further, in the present embodiment, the portion receiving the feedback signal of the power
amplifier 6 is configured as a DC amplifier, but it may be configured as a non-DC amplifier if
there is a problem when performing DC amplification.
For example, a large capacity capacitor may be inserted between the resistor R1 and the ground
in the circuit diagram of FIG. 2 so that amplification at a very low frequency can be performed
without performing full direct current amplification.
[0081]
Needless to say, the present invention is not limited to the examples described above.
[0082]
Second Embodiment The configuration of a bass reproduction speaker device according to a
second embodiment of the present invention will be described with reference to FIG. 3. The field
unit 11a, frame 11b, damper 11d, edge 11e, diaphragm 11f, cabinet 12, The detection means 15
and the power amplifier 16 are exactly the same as those of the first embodiment described in
FIG. 1, and thus the detailed description thereof will be omitted here.
[0083]
In the present embodiment, the voice coil 11c has a diameter of 25 mm as in the first
embodiment, but the bobbin is not extended as in the first embodiment and has a normal length.
The dust cap 11g is attached to the diaphragm 11f.
01-05-2019
21
[0084]
A significant difference between the present embodiment and the present embodiment is that the
means for giving negative stiffness to the vibration system of the speaker unit 11 is a movable
magnet 13 that moves with the vibration system of the speaker unit 11 and the speaker unit 11
relative to the movable magnet 13. The fixed magnet 14 provides a repulsive force in the
vibration displacement direction.
[0085]
The movable magnet 13 has a ring shape, is attached to the voice coil 11 c and moves with the
vibration system of the speaker unit 11.
The fixed magnet 14 is disposed on the inner peripheral side of the same vertical center position
as the movable magnet 13 by a support member 11 h made of resin.
The movable magnet 13 has dimensions of an outer diameter of 30 mm, an inner diameter of
about 25 mm, and a thickness of 3 mm. The material is neodymium with a magnetic energy
product of 32 M · G · Oe (Mega Gauss Oersted).
The fixed magnet 14 has a cylindrical shape with a diameter of 22 mm and a thickness of 10
mm, and is made of the same material as the movable magnet 13.
[0086]
The movable magnet 13 and the fixed magnet 14 are both magnetized to the N pole at the top
and the S pole at the bottom, and repel each other. When the vertical center positions of the
movable magnet 13 and the fixed magnet 14 exactly coincide with each other, no force in the
vertical direction, that is, the displacement direction of the vibration system of the speaker unit
11 is generated.
[0087]
01-05-2019
22
However, when the movable magnet 13 is displaced, a longitudinal vector is generated in the
direction of the repulsive force, so that the movable magnet 13 generates a force to be further
pushed out in the displacement direction, that is, negative stiffness. The negative stiffness
obtained in the case of the second embodiment is also substantially the same value as obtained in
the first embodiment.
[0088]
Further, as in the first embodiment, when the fixed magnet 14 is removed and there is no
negative stiffness, the minimum resonance frequency of the speaker unit 11 is 60 Hz, the
effective vibration mass is about 15 g, and the effective vibration radius is 70 mm.
[0089]
The Hall element 15, which is a detecting means, is arranged in the vertical direction near the
center of the movable magnet 13 in the vertical direction as in the first embodiment.
That is, the movable magnet 13 which is a negative stiffness generating means is shared for
detection.
[0090]
In the present embodiment, since the movable magnet 13 is stronger than the first embodiment,
the detection voltage level of the Hall element 15 is higher than that of the first embodiment.
Therefore, the gain of the feedback circuit 15a is smaller than that of the first embodiment
described with reference to FIG. 2. Specifically, the value of the resistor R8 in FIG. 2 is smaller
than that of the first embodiment. If the feedback loop gain is too high, there is a risk that
oscillation will occur.
[0091]
The low-pitched sound reproduction apparatus of the second embodiment configured in this way
01-05-2019
23
also obtained the same effects as those described in the first embodiment. That is, while
correcting the deviation of the displacement direction of the vibration system of the speaker unit
11, the lowest resonance frequency, that is, the low frequency reproduction limit frequency can
be greatly expanded from 96 Hz to less than 70 Hz due to the negative stiffness.
[0092]
Furthermore, in the present embodiment, since the occurrence of negative stiffness is not a
mechanical means, there is no occurrence of mechanical fatigue, and the reliability is very high.
[0093]
Therefore, as described above, according to the present embodiment, it is possible to realize a
low-cost, low-cost, particularly high-reliability bass reproduction speaker device having excellent
low-pass reproduction ability, which is particularly high in reliability. Can.
[0094]
In the present embodiment, the movable magnet 13 and the fixed magnet 14 are configured as
described above, but various other configurations are possible.
For example, the fixed magnet 14 may be arranged in a ring shape on the outer peripheral side
of the movable magnet 13 (in this case, the Hall element 15 may be arranged on the inner
peripheral side of the movable magnet 13). You may attach a yoke or the like.
[0095]
Further, in the present embodiment, the magnetizing direction of the movable magnet 13 and the
fixed magnet 14 is the longitudinal direction, that is, the thickness direction of the magnet, but it
is also possible to radially magnetize such that both repel each other.
[0096]
Further, in the present embodiment, the Hall element 15 detects the magnetic flux of the
movable magnet 13 that generates negative stiffness, but a small magnet is attached to the
vibration system separately from the movable magnet, and the magnetic flux is detected, etc. You
may
01-05-2019
24
[0097]
Needless to say, the present invention is not limited to the examples described above.
[0098]
(Third Embodiment) The configuration of a bass reproduction speaker device according to a third
embodiment of the present invention will be described with reference to FIG. 4. However, field
unit 21a, frame 21b, voice coil 21c, damper 21d, edge 21e, diaphragm 21f The cabinet 22, the
fixed side support member 22a, the movable magnet 23, the spring 24, the detection means 25,
the feedback circuit 25a, and the power amplifier 26 are the same as in the first embodiment
described with reference to FIG. The specific description of is omitted.
[0099]
A different point of the present embodiment is that means 27a, 27b, 21g for holding the
vibration system of the speaker unit 21 near the center position in the displacement direction is
provided when the bass reproduction speaker device is not operating.
[0100]
A small geared motor 27a has a rotary shaft 27b projecting from the center.
The front end of the shaft 27b is bent in a U-shape so that the movable side support member 21g
can be held with a slight clearance from both the upper and lower sides.
Reference numeral 21g denotes a movable side supporting member to which the spring 24 also
serving as a dust cap is attached, but a small relief hole having a size slightly larger than the
front peripheral dimension of the tip bent portion of the rotating shaft 27b is provided at the
center.
[0101]
At the time of operation of the low-frequency reproduction speaker device, the direction of the
tip end bent portion of the rotary shaft 27b coincides with the relief hole of the movable side
01-05-2019
25
support member 21g.
Thus, at the time of operation of the bass reproduction speaker device, the vibration system of
the speaker unit 21 can move without the movable side support member 21g coming into
contact with the bent end portion of the rotary shaft 27b.
[0102]
When the bass reproduction speaker device is not in operation, for example, when turning off the
bass reproduction speaker device, the geared motor 27a rotates the rotation shaft 27b by several
tens of degrees.
Then, as shown in FIG. 4, the direction of the tip bent portion of the rotary shaft 27b deviates
from the relief hole of the movable support 21g, and the movable support 21g is sandwiched
from both upper and lower sides with a slight clearance, and the vibration system of the speaker
unit 21 Is held near the center position in the displacement direction.
[0103]
The operation control of the geared motor 27a may be performed as follows.
When the bass reproduction speaker device is powered on, the vibration system of the speaker
unit 21 is moved from the biased position to the center position in the displacement direction,
and then the rotary shaft 27b is rotated to release the holding of the vibration system.
The source input signal of the power amplifier is muted for several seconds until the rotating
shaft 27b moves to a predetermined position and stops. This series of operations can be easily
realized by a simple delay circuit or the like.
[0104]
01-05-2019
26
Further, in order to cope with the case where the power of the bass reproduction speaker device
is turned off, a relay which operates about 1 to 2 seconds later than the main body power switch
touched by the user may be provided inside the device. That is, at the moment when the user
turns off the main body power, only the source input to the power amplifier 26 is turned off, and
the geared motor 27a is operated immediately after this to hold the vibration system of the
speaker unit 21 near the center position in the displacement direction. Then, after the geared
motor 27a is stopped, the entire power supply such as the power amplifier 26 and the feedback
circuit 25 may be cut off by the relay.
[0105]
The low-pitched sound reproduction apparatus of this embodiment configured as described
above can not only obtain the same effects as those described in the first embodiment, but also
the vibration system of the speaker unit 21 when the low-pitched reproduction speaker
apparatus is not operating. Since it is held near the center position in the displacement direction,
it does not pass over one side for a long time. As a result, it is possible to eliminate the stress due
to the support system of the speaker unit 21, that is, the support of the damper 21d and the edge
21e, so that the temporal change and deterioration of the support system are reduced.
[0106]
In addition, since the spring 24 is also held in the equilibrium position, there is no concern that
the negative stiffness of the spring 24 tends to be asymmetry, which tends to occur by remaining
deformed for a long time.
[0107]
Therefore, as described above, according to the present embodiment, it is possible to realize a
long-life bass reproduction speaker apparatus with less change over time.
[0108]
In the present embodiment, air leaks slightly from the relief hole of the movable side support
member 21g.
Providing a sealing cover on the movable side support member 21g is more desirable because it
01-05-2019
27
is eliminated.
[0109]
Further, in the present embodiment, the vibration system of the speaker unit 21 is held near the
center position in the displacement direction by using the tip portion of the movable side support
member 21g, but it goes without saying that other members or portions may be used.
[0110]
Although the geared motor 27a is used as means for holding the vibration system of the speaker
unit 21 near the center position in the displacement direction in the present embodiment, it may
be used as a rotating solenoid or other means.
[0111]
Needless to say, the present invention is not limited to the examples described above.
[0112]
(Fourth Embodiment) The configuration of a bass reproduction speaker apparatus according to a
fourth embodiment of the present invention will be described with reference to FIG. 5. However,
field unit 31a, frame 31b, voice coil 31c, damper 31d, edge 31e, diaphragm 31f The movable
side support member 31g, the cabinet 32, the fixed side support member 32a, the movable
magnet 33, the spring 34, the detection means 35, the feedback circuit 35a, and the power
amplifier 36 are exactly the same as the first embodiment described in FIG. Therefore, the
specific explanation about these is omitted here.
[0113]
Like the third embodiment, the present embodiment also includes means for holding the
vibration system of the speaker unit 31 near the center position in the displacement direction
when the bass reproduction speaker device is not operating. However, the self holding solenoid
37a is used. The point is different.
A plunger 37b moving in the central axis direction protrudes from the central portion of the selfholding type solenoid 37a, and a tip end thereof is engaged with a resin holding fitting member
37c attached to the bobbin of the voice coil 31c. It is done.
01-05-2019
28
A return spring 37d is attached to the plunger 37b.
[0114]
At the time of operation of the low-pitched sound reproducing speaker device, the plunger 37b is
immediately sucked as soon as the self-holding solenoid 37a is energized, and the plunger 37b is
immediately removed from the holding engagement member 37c.
The vibration system of the speaker unit 31 can be moved without the holding and fitting
member 37c coming into contact with the tip of the plunger 37b when the bass reproduction
speaker device is in operation.
[0115]
Since 37a is a self holding solenoid, the plunger 37b is kept in a suction state, so that it is
possible to release the energization immediately after suction.
In other words, energization may be performed only for a moment.
[0116]
When the bass reproduction speaker device is not operating, for example, when the bass
reproduction speaker device is turned off, the self-holding solenoid 37a is energized in the
reverse direction.
So-called return current flows. Then, the plunger 37b is released from the suction state, and
returns to the position of the holding engagement member 37c by the force of the return spring
37d. Thus, the vibration system of the speaker unit 31 is held near the center position in the
displacement direction.
01-05-2019
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[0117]
An example of a circuit diagram for controlling the operation of the self-holding solenoid 37a is
shown in FIG. ACD is an AC primary side current detection circuit of the bass reproduction
speaker device. Energization of the coil of the self-holding solenoid 37a is performed using a
large capacity capacitor C2. The operation of this control circuit is as follows.
[0118]
When the power supply switch of the bass reproduction speaker device is turned on, the AC
primary side current detection circuit ACD generates a detection electric signal, and current
starts to flow to the base of the transistor Q. The capacitor C1 and the resistor R are connected to
the transistor Q, and the relay RR connected to the emitter of the transistor Q with this time
constant operates about one second after the power switch is turned on. The reason for
operating about one second later is to wait for the vibration system of the speaker unit 31 to
move from the biased position to the center position in the displacement direction.
[0119]
Then, the relay RR is turned on to connect the terminal 1 and the terminal 2, current from the
power supply side instantaneously flows into the self-holding solenoid 37a through the capacitor
C2, and the self-holding solenoid 37a operates to be in a suction state. This current is a charging
current of the capacitor C2, but it is only for a moment, and it is not necessary to keep the
unnecessary current flowing to the self-holding solenoid 37a.
[0120]
When the power supply switch of the bass reproduction speaker device is turned off, the
detected electric signal from the AC primary side current detection circuit ACD disappears, so the
transistor Q is cut off and the relay RR is turned off. Then, terminals 1 and 3 of relay RR are
connected, and capacitor C1 discharges to self-holding type solenoid 37a, but the direction of the
current at this time is reverse to that when the power switch of the bass reproduction speaker
device is turned on. . Thus, the reverse current flows in the self-holding solenoid 37a, so that the
01-05-2019
30
plunger 37b can be returned. The terminals 4 and 6 of the relay RR are for discharging the time
constant capacitor C1.
[0121]
The low-pitched sound reproduction apparatus according to the present embodiment configured
as described above not only can obtain the same effects as those described in the third
embodiment, but the self-holding type solenoid 37a operates instantaneously. As in the geared
motor used in 3, it can be put into operation quickly without taking time.
[0122]
When the speaker system is not provided with means for holding the vibration system of the
speaker unit in the vicinity of the center position in the displacement direction, it is difficult to
quickly turn on the bass reproduction speaker device after turning on the power.
Because the vibration system is pushed far away from the center position in the displacement
direction by the force of the spring when the bass reproduction speaker device is not operating,
it takes some time for this to return to the center position in the displacement direction. is there.
[0123]
Further, in the present embodiment, the operating current of the self-holding solenoid 37a is
supplied through the capacitor C2, and the same capacitor is discharged to supply the return
current of the self-holding solenoid 37a. There is no need to have a separate power supply. As a
result, if the power is cut off suddenly during operation of the bass reproduction speaker device,
for example, even if a power failure or a power outlet is accidentally disconnected, the selfholding type solenoid 37a is utilized using the charge stored in the capacitor C2. Since the return
operation is performed, it is possible to hold the vicinity of the displacement direction center
position of the vibration system of the speaker unit 31.
[0124]
Therefore, as described above, according to the present embodiment, it is possible to realize a
highly safe bass reproduction speaker device that can not only change with time and have a long
life, but also can quickly enter an operating state.
01-05-2019
31
[0125]
In this embodiment, the plunger 37b of the self-holding solenoid 37a is in the return state when
the low-sound reproduction speaker device is not in operation, but the reverse design is also
possible.
[0126]
Although the self-holding solenoid 37a is used in the present embodiment, it may be designed as
a normal solenoid or another type of solenoid.
However, if a self-holding type solenoid is used, it is possible to save power by simply flowing an
operating current.
[0127]
Needless to say, the present invention is not limited to the examples described above.
[0128]
(Fifth Embodiment) The configuration of a bass reproduction speaker apparatus according to a
fifth embodiment of the present invention will be described with reference to FIG. 7. However,
field unit 41a, frame 41b, voice coil 41c, damper 41d, edge 41e, diaphragm 41f The movable
side support member 41g, the cabinet 42, the movable magnet 43, the spring 44, the detection
means 45, the feedback circuit 45a, and the power amplifier 46 are exactly the same as in the
first embodiment described in FIG. The specific description of is omitted.
[0129]
A characteristic point of this embodiment is that a movable rod 42b is provided in the fixed
support member 42a that supports and supports, so that the negative stiffness of the spring 44
can be varied.
[0130]
01-05-2019
32
Specifically, the four fixed support members 42a and the movable rods 42b in FIG. 7 incorporate
an axial propulsion movable mechanism including a motor, a worm gear, and a rack gear.
When the rotation of the motor stops, the worm gear and the rack gear do not move even if a
compressive force is applied to the movable rod 42b, so the movable rod 42b acts as a stationary
fixed end.
[0131]
When the bass reproduction speaker device is not in operation, the movable rod 42b is retracted
to loosen the spring 44.
During operation of the bass reproduction speaker device, the movable rod 42b is advanced to
apply a predetermined compression force to the spring 44.
Alternatively, by adjusting the stationary position of the movable rod 42b, the compression force
to be applied to the spring 44 can be adjusted, so that the generated negative stiffness can be
varied.
[0132]
The low-pitched sound reproducing apparatus according to the present embodiment configured
as described above can not only obtain the same effects as those described in the first
embodiment but also reduce the negative stiffness of the spring 44 when not operating. The
support system of the speaker unit 41, that is, the damper 41d and the edge 41e are not
stretched, and the change with time and the deterioration of the support system are reduced.
[0133]
Further, since the negative stiffness generated by the spring 44 can be adjusted, the lowest
resonance frequency of the bass reproduction speaker device can be adjusted, and the low
frequency characteristic can be varied.
[0134]
Therefore, as described above, according to the present embodiment, it is possible to realize a
01-05-2019
33
low frequency reproduction speaker device that is not only small in change with time, has a long
life, and can change low frequency characteristics.
[0135]
In the fifth embodiment, the means for giving negative stiffness is a mechanical means, that is,
the spring 44, but a magnetic means as described in the second embodiment may be used.
In this case, for example, by adjusting the current supplied to the fixed magnet as an
electromagnet, the generated negative stiffness can be varied.
[0136]
Needless to say, the present invention is not limited to the examples described above.
[0137]
As described above, according to the bass reproduction speaker device of the present invention,
the speaker unit, the means for giving negative stiffness to the vibration system of the speaker
unit, and the cabinet for housing the speaker unit are provided. In the bass reproduction speaker
device, the electric signal from the detection means is fed back to the detection means for
generating an electric signal according to the displacement of the vibration system of the speaker
unit and a power amplifier for reproducing the source signal for driving the speaker unit. The
speaker unit is provided with a feedback circuit, and the power amplifier supplies power to the
speaker unit to correct deviation of the displacement direction of the vibration system of the
speaker unit in addition to source signal power. A slight deviation in the displacement direction is
always corrected and held at the center position in the original displacement direction. Not only
is extremely stable movement where the average displacement center position of the vibration
system is held at the original center position, but also correction of deviation in the displacement
direction of the vibration system, even if negative stiffness is large. There is no need to separately
provide a conventional intake and exhaust pump and a control power amplifier.
Therefore, it is possible to realize a low-cost and practical low-frequency bass reproduction
speaker device having excellent low-pass reproduction capability with a simple configuration.
01-05-2019
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[0138]
According to the low-pitched sound reproduction speaker device according to claim 2 of the
present invention, the movable magnet moving with the vibration system of the speaker unit and
the Hall element for detecting the magnetism of the movable magnet are the detection means.
The upper and lower of the displacement of the vibration system of the speaker unit can be
determined by
Therefore, it is possible to realize a bass reproduction speaker device in which the configuration
of the detection means is simplified.
[0139]
According to the bass reproduction speaker device according to the third aspect of the present
invention, the means for giving negative stiffness to the vibration system of the speaker unit
comprises: a central portion of the vibration system of the speaker unit and a vicinity of an outer
peripheral portion of the speaker unit In the meantime, since the spring is compressed and
attached to a plurality of substantially central axis symmetric plural points, the length of the
spring can be increased and the mechanical fatigue is reduced.
Therefore, a highly reliable bass reproduction speaker device can be realized.
[0140]
According to the bass reproduction speaker device of the present invention, the means for giving
negative stiffness to the vibration system of the speaker unit is a movable magnet which moves
together with the vibration system of the speaker unit, and the movable magnet with respect to
the movable magnet. By using a fixed magnet that applies a force in the direction of vibration
displacement of the speaker unit, no mechanical fatigue occurs because negative stiffness is not a
mechanical means.
Therefore, a particularly reliable bass reproduction speaker device can be realized.
01-05-2019
35
[0141]
According to the bass reproduction speaker apparatus according to the fifth aspect of the present
invention, by including means for holding the vibration system of the speaker unit in the vicinity
of the center position in the displacement direction when not in operation, The vibration system
of the speaker unit is not biased to one side in the displacement direction and does not pass for a
long time, so long-term stress is not applied to the support system or the spring of the speaker
unit. Therefore, it is possible to realize a long-life bass reproduction speaker device with less
change over time.
[0142]
According to the low-pitched sound reproduction speaker device according to claim 6 of the
present invention, by using a self-holding type solenoid as a means for holding the vibration
system of the speaker unit near the center position in the displacement direction when not
operating It is possible to instantly hold or release the vibration system of the above in the
vicinity of the center position in the displacement direction. Therefore, it is possible to realize a
bass reproduction speaker device which can be put into operation quickly.
[0143]
According to the bass regeneration speaker device of the present invention, the operating current
of the self holding solenoid is supplied through the capacitor, and the return current of the self
holding solenoid is supplied by the discharge of the capacitor. Thus, even when power is
suddenly shut off during operation of the bass reproduction speaker device, it is possible to
maintain the vicinity of the displacement direction center position of the vibration system of the
speaker unit. Therefore, a highly safe bass reproduction speaker device can be realized.
[0144]
According to the bass reproduction speaker device according to the eighth aspect of the present
invention, the speaker unit is supported by the means for reducing the negative stiffness of the
01-05-2019
36
means for giving negative stiffness to the vibration system of the speaker unit when not
operating. The system gets stuck. Therefore, it is possible to realize a long-life bass reproduction
speaker device with less change over time.
[0145]
According to the bass reproduction speaker device of the present invention, the negative stiffness
can be adjusted by providing the means for varying the stiffness of the means for giving the
negative stiffness to the vibration system of the speaker unit. The lowest resonance frequency of
the bass reproduction speaker device can be adjusted. Therefore, it is possible to realize a bass
reproduction speaker device capable of changing the low frequency characteristics.
[0146]
As described above, the present invention has extremely great practical value.
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