JP3603704B2 - Low frequency reproduction speaker device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a low-frequency sound reproduction speaker device for obtaining a high low-frequency reproduction capability despite being a small cabinet.
[0002]
[Prior art]
In general, regarding the low-frequency reproduction of a speaker, there is an inverse relationship between the volume V in the cabinet, the low-frequency reproduction limit frequency fc, and the efficiency μ, and it is a principle that a small cabinet reproduces to a low frequency without lowering the efficiency. Is known to be very difficult.
[0003]
Further, if negative stiffness is used to reduce the stiffness of the air inside the cabinet to increase the volume V inside the cabinet equivalently, the concept itself that it is possible to escape from this restriction and improve the low-frequency reproduction capability is also old. From. However, the reality is that there was no good way to implement this.
[0004]
Here, conventional technologies that have been proposed in the past to realize this concept will be described. The prior art U.S. Patent 2810021 (LOW FREQUENCY LOUDSPEAKER, Patented Oct.15,1957), and U.S. Patent 4607382 (ELECTROACOUSTIC TRANSDUCER UNIT WITH REDUCED RESONANT FREQUENCY AND MECHANICAL SPRING WITH NEGATIVE SPRING STIFFNESS, PREFERABLY USED IN SUCH A TRANSDUCER UNIT, Patented Aug 19, 1986). Both have the same basic concept, but the latter has a more advanced configuration than the former.
[0005]
8 and 9 show the configuration of this conventional bass reproduction speaker device. 8 and 9, reference numeral 51 denotes an electrodynamic 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 an outer peripheral portion of the diaphragm 51f. Reference numeral 54 denotes a pair of springs in which upper and lower two bow-shaped leaf springs are opposed to each other, and both ends thereof are fixed to the movable side support member 51g on the reinforcing ring 51i and the frame 51b while being compressed. It is attached to the fixed side support member 52a at the location. In this conventional example, about three sets of the springs 54 are provided symmetrically with respect to the center axis in the vibration direction of the diaphragm 51f.
[0007]
The fixed-side support members 52a are arranged on both sides of the movable-side support member 51g. If only one side is used, an axial rotational force is generated in the reinforcing ring 51i, that is, the diaphragm 51f, and stress is applied to the support system of the speaker unit 51. Is added, leading to breakage.
[0008]
Reference numeral 58 denotes a means for detecting a deviation of the diaphragm 51f from the center of vibration. The specification of US Pat. No. 4,607,382 includes a capacitance detection method, an inductance detection method, a light amount detection method, and a cabinet air pressure detection method. Mention the scheme.
[0009]
Reference numeral 59 denotes a control device for correcting a deviation of the vibration plate 51f from the vibration center position, and is operated by an 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. In FIG. 9, the control device 59 is a high-output power amplifier provided separately from a normal power amplifier that amplifies a source signal, and is connected to the speaker unit 51.
[0010]
The operation of the conventional bass reproduction speaker device configured as described above will be described with reference to FIGS. FIGS. 10 and 11 show the action of the negative stiffness by the spring 54. FIG. In FIG. 10, 52a is a fixed-side support member, 51g is a movable-side support member, and 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 side support member 51g is exactly at the center of the vibration displacement direction x, that is, at x = 0, the direction of the repulsive force of the spring 54 acting between the movable side support member 51g and the fixed side support member 52a is the x direction. Since it is a right angle and the force vector component in the x direction becomes zero, no force in the x direction is generated.
[0012]
However, when the position of the movable-side support member 51g deviates from the center, that is, when the position of the movable-side support member 51g is, for example, the position of Δx in FIG. 10, the repulsion of the spring 54 acting between the movable-side support member 51g and the fixed-side support member 52a. Since the direction of the force is not perpendicular to the x direction, a force vector component in the x direction is generated, and a force for pushing the movable-side support member 51g in the Δx direction is generated.
[0013]
When the movable-side support member 51g is displaced by Δx, in addition to the support system of the speaker unit 51 such as the edge 51e, the force given by the sealed air in the cabinet 52 to the vibration system of the speaker unit 51 is F1, Needless to say, the polarity of the stiffness of the force of F1 is positive because the movable side support member 51g is to be pulled 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-side support member 51g in the direction of displacement, and the polarity of the stiffness of the force of F2. Is negative.
[0015]
Therefore, a negative stiffness force is generated by the spring 54. FIG. 11 shows the effect of this negative stiffness. In FIG. 11, the broken line indicates the relationship between the positive stiffness of the speaker unit support system and the cabinet internal air applied to the vibration system, that is, the movable-side support member 51 g, and the displacement in the x direction. Similarly, the dashed line indicates the negative stiffness of the spring 54. The solid line indicates the relationship between the force applied to the movable-side support member 51g and the x-direction displacement, and the solid line indicates the relationship between the force applied to the movable-side support member 51g and the x-direction displacement given by the sum of these forces.
[0016]
The positive stiffness is F1 / △ x, which corresponds to the slope of the broken line. The negative stiffness is F2 / △ x, which corresponds to the dashed line gradient. The total stiffness is Ft / △ x, that is, (F1−F2) / △ x, which corresponds to the gradient of the solid line. This slope is smaller than the dashed slope, which will reduce the total stiffness. In this way, the stiffness finally applied to the movable-side support member 51g is reduced by the action of the negative stiffness, so that an effect equivalent to a reduction in the stiffness of the air inside the cabinet is obtained. Accordingly, since the stiffness of the air inside the cabinet is inversely proportional to the volume inside the cabinet, the effect of increasing the inside volume of the cabinet 52 equivalently is obtained.
[0017]
In order to obtain this effect sufficiently, the negative stiffness of the spring 54 must be increased. However, in this case, 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 outside the displacement center position x = 0, so that normal operation cannot be performed. .
[0018]
The sum of the stiffness of the air inside the cabinet 52 and the stiffness of the support system of the speaker unit 51 is larger than the negative stiffness, but a small amount of air leaks 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 cannot stop at the displacement center position.
[0019]
The detection means 58, the control device 59, and the intake / exhaust pump 60 in FIGS. 8 and 9 are provided to prevent and correct this. For example, in the configuration of FIG. 8, if the average vibration displacement center of the vibration system of the speaker unit 51 is shifted forward from the original center position (the position of x = 0 in FIG. 10), the deviation of the displacement will be described. Is detected by the detecting means 58 to generate a signal and send an output signal to the control device 59. Then, the control device 59 causes the intake / exhaust pump 60 to perform an exhaust operation to exhaust the air in the cabinet 52, and returns the diaphragm 51f of the speaker unit 51 to the original displacement center position.
[0020]
Conversely, when the vibration system is biased backward, the intake / exhaust pump 60 performs a suction operation to draw air into the cabinet 52, and pushes the vibration system of the speaker unit 51 back to the original displacement center position.
[0021]
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 control device 59 supplies a current in the opposite direction to the voice coil 51c of the speaker unit 51 to push the vibration system back to the original displacement center position.
[0022]
Note that 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 an original voice coil for reproducing the source signal.
[0023]
Therefore, with the bass reproduction speaker device having the conventional configuration as described above, the internal volume of the cabinet is equivalently increased by negative stiffness while correcting the bias in the displacement direction of the vibration system of the speaker unit 51, and the low-frequency reproduction capability is improved. Can be improved. A more detailed description of the principle of equivalently increasing the internal volume of the cabinet by negative stiffness and improving the low-frequency reproduction capability will be given in the embodiments of the present invention.
[0024]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, the device requires a power amplifier different from the intake / exhaust pump and the power amplifier for reproducing the source signal in order to correct the bias in the displacement direction of the vibration system of the speaker unit 51. There was a problem that it was complicated, large-scale, and expensive. In addition, there is also a problem that reliability is poor because mechanical fatigue easily occurs in the spring 54.
[0025]
In other words, although there was a concept of improving the bass reproduction capability by equivalently increasing the internal volume of the cabinet, it was not practical with the bass reproduction speaker device according to the prior art.
[0026]
SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and has a simple structure, low cost and high reliability. It is an object to provide a speaker device.
[0027]
[Means for Solving the Problems]
In order to achieve this object, a bass reproduction speaker device according to the present invention includes a speaker unit, means for providing a negative stiffness to a vibration system of the speaker unit, and a cabinet accommodating the speaker unit. , A detecting means for generating an electric signal according to a displacement of a vibration system of the speaker unit, and a feedback circuit for feeding back the electric signal from the detecting means to a power amplifier for reproducing a source signal for driving the speaker unit. The power amplifier, in addition to the source signal power, supplies to the speaker unit electric power for correcting the bias in the displacement direction of the vibration system of the speaker unit.AloneSupplyMeans for holding the vibration system of the speaker unit near the center position in the displacement direction when the bass reproduction speaker device is not operating.Things.
[0028]
Further, a movable magnet that moves together with the vibration system of the speaker unit and a Hall element that detects the magnetism of the movable magnet are used as the detection means.
[0029]
Further, a means for giving a negative stiffness to the vibration system of the speaker unit is compressed and attached to a plurality of locations substantially symmetric about the central axis between the center of the vibration system of the speaker unit and the vicinity of the outer periphery of the speaker unit. This is a plate-shaped spring. Alternatively, the means for providing 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.The fixed magnet and the movable magnet are arranged at the same vertical center position.It is something.
[0030]
ADVANTAGE OF THE INVENTION According to this invention, the low-pitched sound reproduction | regeneration speaker apparatus which has a simple structure, is low-cost, has high reliability, and has excellent low-frequency reproduction capability can be realized.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
The invention according to claim 1 of the present invention is directed to a low-frequency sound reproduction speaker device including a speaker unit, a unit for providing a negative stiffness to a vibration system of the speaker unit, and a cabinet for housing the speaker unit. A power amplifier for generating an electric signal corresponding to a displacement of a vibration system of the unit, and a feedback circuit for feeding back the electric signal from the detecting means to a power amplifier for reproducing a source signal for driving the speaker unit; Is,In addition to the source signal power, the power for correcting the bias in the displacement direction of the vibration system of the speaker unit isAloneSupplyAnd when the bass reproduction speaker device is not operating,YouEquipped with means to hold the knit vibration system near the center position in the displacement directionIt is low cost, simple in configuration, and has excellent practical low-frequency reproduction capability.And long life with little change over timeA bass reproduction speaker device can be realized.
[0033]
Claims of the invention2The invention described in the above, means for giving a negative stiffness to the vibration system of the speaker unit, a plurality of substantially central axis object between the center of the vibration system of the speaker unit and the vicinity of the outer periphery of the speaker unit, Compressed and attached leaf springClaim 1And a highly reliable bass reproduction speaker device can be realized.
[0034]
Claims of the invention3In the invention described in (1), means for giving a negative stiffness to the vibration system of the speaker unit includes a movable magnet that moves together with the vibration system of the speaker unit, and a force in the vibration displacement direction of the speaker unit applied to the movable magnet. As a fixed magnetThe fixed magnet and the movable magnet are arranged at the same vertical center position.Claims1, And a particularly reliable bass reproduction speaker device can be realized.
[0036]
Claims of the present invention4The invention described in,A self-holding solenoid is used as means for holding a vibration system of the speaker unit near a center position in a displacement direction.1The low-frequency sound reproduction speaker device described in (1) above can be realized.
[0037]
Claims of the present invention5In the invention described in (1), the operating current of the self-holding solenoid is supplied via a capacitor, and the return current of the self-holding solenoid is supplied by discharging the capacitor.4And a low-frequency sound reproduction speaker device with high safety can be realized.
[0040]
Hereinafter, a bass reproduction speaker device of the present invention will be described based on specific embodiments.
[0041]
(Embodiment 1)
FIG. 1 shows the structure of the bass reproduction speaker device of the first embodiment. In FIG. 1, a speaker unit 1 including a field part 1a, a frame 1b, a voice coil 1c, a damper 1d, an edge 1e, a diaphragm 1f, and a movable support member 1g serving also as a dust cap is mounted on a closed cabinet 2. ing. The movable magnet 3 is attached to the bobbin of the voice coil 1c, and moves together with the vibration system of the speaker unit 1 such as the voice coil 1c and the diaphragm 1f.
[0042]
A movable-side support member 1g is attached to the tip of the long and extended bobbin of the voice coil 1c. On the outer peripheral side of the frame 1b of the cabinet 2, fixed-side support members 2a are fixed at four positions symmetric with respect to the central axis. A pair of springs 4 having bow springs facing each other is mounted between the fixed-side support member 2a and each movable-side support member 1g so as to be compressed from both ends. That is, the spring 4 applies a repulsive force to the movable-side support member 1g and the fixed-side support member 2a, and is applied to the movable-side support member 1g, that is, to the vibration system of the speaker unit 1 according to the same principle as the above-described conventional example. Gives negative stiffness.
[0043]
Since all four springs 4 are the same and are mounted at symmetrical positions, the repulsive force is balanced in the horizontal direction, and the movable-side support member 1g is kept at the center in the horizontal direction. .
[0044]
In the vicinity of the movable magnet 3, a Hall element 5 is disposed as detection means for generating an electric signal according to the displacement of the vibration system. The speaker unit 1 is driven by a power amplifier 6 for reproducing a source signal. The output electric signal of the Hall element 5 is fed back to the power amplifier 6 by the feedback circuit 5a, and the power for correcting the bias in the displacement direction of the vibration system of the speaker unit 1 is added to the source signal power. Supplied.
[0045]
Hereinafter, the material, dimensions, performance, circuit configuration, and the like of the components of the bass reproduction speaker device will be specifically described.
[0046]
The diameter 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 has a diameter of 18 cm and is made of an iron plate. The diameter (nominal diameter) of the voice coil 1c is 25 mm. The material of the edge 1e is urethane foam and has a down-roll shape. The diaphragm 1f is a cone made of paper. The material of the movable side support member 1g is a resin.
[0047]
The cabinet 2 is of a closed type and has a small internal volume of 10 liters. The material of the fixed-side support member 2a is a resin. The bow-shaped leaf spring 4 has a length of 10 cm in a mounted state. The width of the spring 4 is 1 cm, and the material is a phosphor bronze plate.
[0048]
Here, the principle of equivalently increasing the internal volume of the cabinet by negative stiffness and improving the low-frequency reproduction capability will be described in more detail. Assuming that the effective vibration mass of the speaker unit is M and the lowest resonance frequency in a single free air state is f0, the stiffness Ks of the support system (damper and edge) of the speaker unit is Ks = M × (2πf0) 2 (1) It is. Assuming that the effective vibration radius of the speaker unit is a, the air sound velocity is c, the air density is ρ, and the volume of the cabinet is V, the stiffness Kc given by the air in the cabinet to the speaker unit vibration system is Kc = ρc2 (πa) 2 / V Expression (2). When the speaker unit is attached to the cabinet, a stiffness of Ks + Kc acts on the speaker unit vibration system. Assuming that the lowest resonance frequency at this time is f1, f1 = (Ks + Kc) 1/2 / 2πM1 / 2 (3).
[0049]
Here, the magnitude of the negative stiffness is assumed to be Kn. Then, the stiffness acting on the vibration system of the speaker unit becomes Ks + Kc-Kn, which corresponds to the stiffness of the 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 (2), this is equivalent to an increase in the internal volume of the cabinet from 1 / Kc to 1 / (Kc-Kn).
[0050]
Due to the negative stiffness, the lowest resonance frequency of the speaker unit attached to the cabinet becomes f1 = (Ks + Kc-Kn) 1/2 / 2πM1 / 2 (4), so that the lowest resonance frequency is Δ (Ks + Kc). −Kn) / (Ks + Kc)｝ 1/2, that is, the low-frequency reproduction limit frequency is extended correspondingly, and the low-frequency reproduction capability is improved.
[0051]
If the technique of the negative stiffness is not used, in order to lower the lowest resonance frequency, the effective vibration mass must be increased or the effective vibration area must be reduced, so that the efficiency is reduced. On the other hand, if negative stiffness is used, the lowest resonance frequency can be reduced without doing so, so that the low range can be extended without lowering the efficiency.
[0052]
In accordance with the principle described above, the effect of equivalently increasing the internal volume of the cabinet and improving the low-frequency reproduction capability according to the present embodiment will be described. In the present embodiment, the minimum resonance frequency of the speaker unit 1 when the compression of the spring 4 is relaxed and no negative stiffness is generated is 60 Hz, and the effective vibration mass is 15 g. The effective vibration radius is 70 mm. That is, the stiffness Ks of the support system of the speaker unit is Ks = 2130 (N / m) according to the equation (1). The stiffness Kc given by the air in the cabinet 2 is Kc = 3290 (N / m) according to the equation (2). That is, Ks + Kc = 5420 (N / m). Then, the lowest resonance frequency f1 of the speaker unit 1 in a state where the speaker unit 1 is attached to the cabinet 2 is calculated from Expression (3) as f1 = 96 Hz, and the actual measurement value is also the same.
[0053]
The negative stiffness Kn obtained when the spring 4 was compressed and attached was 2800 (N / m), which exceeded the stiffness Ks of the support system of the speaker unit 1 = 2130 (N / m). The total stiffness is Ks + Kc-Kn = 5420-2800 = 2620 (N / m). In the first embodiment, the lowest resonance frequency, that is, the low-frequency reproduction limit frequency can be significantly extended from 96 Hz to 67 Hz. did it.
[0054]
This is equivalent to increasing the volume in the cabinet from 1/3290 to 1 / (3290-2800) = 1/490. That is, the effect of increasing the internal volume of the cabinet 2 several times equivalently is obtained.
[0055]
Next, a configuration for correcting a bias in the displacement direction of the vibration system of the speaker unit 1 will be described in detail.
[0056]
The dimensions of the movable magnet 3 are 5 mm in length and width, 3 mm in thickness, and the material is ferrite. The movable magnet 3 is magnetized in the vertical direction, that is, in the vertical height direction in FIG. 1, and the upper side is the N pole and the lower side is the S pole. The Hall element 5 is arranged in the vertical and vertical directions near the center of the movable magnet 3 in the vertical direction. The distance between them is about 3 mm.
[0057]
The Hall element 5 generates an output signal according to a magnetic flux vector generated by the movable magnet 3 in the horizontal direction. At the center position of the movable magnet 3 in the vertical direction, the magnetic flux passes from the north pole to the south pole in the vertical direction immediately below, so that the horizontal magnetic flux vector becomes zero. Therefore, when the vertical center position of the movable magnet 3 matches the vertical center position of the Hall element 5, 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 up or down, the magnetic flux distribution becomes asymmetric at the position of the Hall element 5 and, in short, either the N pole side or the S pole side of the movable magnet 3 approaches, so the horizontal direction 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 electric signal when the N pole approaches, for example, the direction of the horizontal magnetic flux vector is reversed when the S pole approaches, so that a negative electric signal is generated. That is, with this configuration, an electric signal corresponding to the displacement of the vibration system 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, when there is no deviation in the displacement direction, the Hall element 5 is generated when low-frequency AC power is applied to the speaker unit 1. The electric signal is symmetrical on the plus side and the minus side with respect to the zero level, and when this is integrated, the electric signal becomes zero. However, when the displacement of the vibration system is deviated in the displacement direction, the level on either the plus side or the minus side becomes large (that is, a bias is generated), so that an electric signal is generated even after integration.
[0060]
In the present embodiment, for example, when the vibration system of the speaker unit 1 starts to be biased to one side, a current in a direction to return the vibration system in the opposite direction, that is, to return to the original displacement center position, is supplied from the power amplifier 6 to the speaker unit 1. 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 at which detection voltages are generated. OP1 is an operational amplifier in a buffer amplifying section, and OP2 is an operational amplifier in an integrating circuit section. P-AMP is a general audio IC power amplifier, and its output is 30W.
[0062]
C3 is an integrating capacitor, and the amplification gain of OP2 attenuates as the frequency increases. As a result, feedback is applied only to the very low frequency component signal corresponding to the biased movement of the vibration system of the speaker unit 1. In other words, no feedback is applied to the movement of the vibration system of the audio source such as music at a low frequency of several tens of Hz or more, so that there is no adverse effect on the low frequency. VR is a volume for offset adjustment, and can adjust the output voltage of the feedback circuit to zero when the vibration system of the speaker unit 1 is at the original center position.
[0063]
The feedback circuit 5a is connected to the feedback circuit 5a so that a current corresponding to the ultra-low frequency component signal fed back to the + terminal of the P-AMP from the feedback circuit 5a, that is, power for correcting the bias of the vibration system in the displacement direction can be supplied to the speaker 1. The connected P-AMP portion has a DC amplifier configuration.
[0064]
However, a DC cut capacitor C1 is inserted between the terminal IN receiving the source signal and the P-AMP, and the power amplifier 6 as a whole operates in the same manner as a normal audio power amplifier. I mean,OnePower amplifier 6AloneThus, both the power of the audio source signal and the power of correcting the bias in the displacement direction of the vibration system can be supplied to the speaker unit 1.
[0065]
With this configuration, the speaker unit 1 is provided with a servo that always corrects a slight deviation in the displacement direction of the vibration system and maintains the original position in the center of the displacement direction. Even if the negative stiffness is large, the average of the vibration system is increased. An extremely stable operation in which the displacement center position was maintained at the original center position was obtained.
[0066]
That is, in the present embodiment, it is not necessary to separately provide an intake / exhaust pump and a control power amplifier as in the related art in order to correct the bias in the displacement direction of the vibration system. Further, needless to say, the voice coil 1c of the speaker unit 1 does not need to be a double voice coil. Further, the configurations of the detecting means 5 and the feedback circuit 5a are simple, and all of the components used are inexpensive.
[0067]
In the conventional configuration described with reference to FIG. 8, when the speaker unit 51 has the same 18 cm diameter, the length of the spring 54 attached between the movable support member 51g and the fixed support member 52a is only about 5 cm. In the first embodiment, the spring 4 is attached between the center of the vibration system of the speaker unit 1 and the outer periphery of the frame 1b, which means that the movable support member 1g and the fixed support member 2a The mechanical fatigue of the spring 4 is very small because the length of the spring 4 attached between them can be increased to 10 cm.
[0068]
Therefore, as described above, according to the present embodiment, a low-frequency sound reproduction speaker device having a simple configuration, low cost, high reliability, and practical and excellent low-frequency reproduction capability can be realized.
[0069]
In the present embodiment, the movable magnet 3 is attached to the voice coil 1c. However, the movable magnet 3 may be attached to other parts of the vibration system 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 a low frequency range. However, it is better not to bring the Hall element 5 too close to the field portion 1a. This is because the magnetic flux leaking from the field portion 1a has an effect.
[0070]
Further, in the present embodiment, the speaker unit 1 is a normal electrodynamic type, but the present invention can be applied to other electroacoustic conversion type speaker units such as a motor drive type and an electromagnetic type.
[0071]
In the present embodiment, the means for providing negative stiffness is a mechanical means using a spring, but it is needless to say that magnetic means may be used as described in the second embodiment. In addition, electrostatic means using a repulsive force between charges of the same polarity may be used.
[0072]
Further, in this embodiment, four springs 4 are arranged symmetrically with respect to the central axis, but may be three or other numbers. If the negative stiffness generated by the spring 4 is not so large, it is possible to use two springs.
[0073]
In the present embodiment, the spring 4 is a bow spring made of phosphor bronze, but other materials and shapes are also possible. For example, if the material is a shape memory alloy, metal fatigue is reduced and reliability is improved.
[0074]
Further, in the present embodiment, the fixed-side support member 2a is fixed to the cabinet 2, but the length of the spring 4 can be sufficiently ensured even when the fixed-side support member 2a is attached to the outer peripheral portion of the frame 1b of the speaker unit 1.
[0075]
Further, in the present embodiment, the cabinet 2 is a closed type, but a cabinet type other than the closed type, such as a Kelton type, can be applied as long as the rear of the speaker unit is closed.
[0076]
Further, in the present embodiment, the Hall element 5 is used as the detecting means, but it goes without saying that other methods, for example, the following types of detecting means are also possible. That is, an optical system that detects a change in the amount of light with a CDS, a photodiode, a phototransistor, or the like, an electrostatic system that detects a capacitance between a movable electrode and a fixed electrode attached to a vibration system of a speaker unit, a speaker unit And an induction method in which a change in coil inductance is detected by an iron plate attached to the vibration system and a coil arranged near the iron plate.
[0077]
However, when a Hall element is used as the detection means, the simplest configuration can be obtained. This is because, in the optical system, the electrostatic system, and the induction system, it is necessary to arrange two upper and lower detection elements in order to determine whether the speaker unit 1 is vertically moved from the center position of the displacement of the vibration system. In the first embodiment, since the movable magnet 3 has two polarities of the N pole and the S pole, the Hall element 5 generates a plus or minus electric signal according to the vertical displacement of the vibration system of the speaker unit 1. That is, it is possible to determine whether the displacement of the vibration system of the speaker unit 1 is up or down with one detection element.
[0078]
In the present embodiment, the Hall element 5 is used as the detecting means. However, if a Hall IC is used instead, the feedback circuit can be simplified.
[0079]
Further, in the first embodiment, the signal feedback from the feedback circuit 5a to the power amplifier 6 is performed purely electrically, but may be performed via a photocoupler.
[0080]
In the present embodiment, the portion of the power amplifier 6 that receives the feedback signal has a DC amplifier configuration. However, if a problem arises when DC amplification is performed, a non-DC amplifier configuration may be used. 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 an extremely low frequency can be performed without performing complete DC amplification.
[0081]
In addition, it goes without saying that the present invention is not limited to the examples described above.
[0082]
(Embodiment 2)
The configuration of the low-frequency sound reproduction speaker device according to the second embodiment of the present invention will be described with reference to FIG. 3, but the field portion 11a, frame 11b, damper 11d, edge 11e, diaphragm 11f, cabinet 12, detection means 15, power amplifier 16 is exactly the same as that of the first embodiment described with reference to FIG. 1, and a 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. Then, a dust cap 11g is attached to the diaphragm 11f.
[0084]
A major difference between the present embodiment and the present embodiment is that a means for giving a negative stiffness to the vibration system of the speaker unit 11 includes a movable magnet 13 that moves together with the vibration system of the speaker unit 11, That is, the fixed magnet 14 gives a repulsive force in the vibration displacement direction.
[0085]
The movable magnet 13 has a ring shape, is attached to the voice coil 11c, and moves together with the vibration system of the speaker unit 11. A fixed magnet 14 is attached to the inner peripheral side of the same vertical center position as the movable magnet 13 by a resin support member 11h. 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, and is made of neodymium having a magnetic energy product of 32 M · G · Oe (Mega Gauss Oersted). The fixed magnet 14 has a cylindrical shape with dimensions of 22 mm in diameter and 10 mm in thickness, and is made of the same material as the movable magnet 13.
[0086]
Both the movable magnet 13 and the fixed magnet 14 are magnetized with the N pole on the upper side and the S pole on the lower side, 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 is generated in the vertical direction, that is, in the displacement direction of the vibration system of the speaker unit 11.
[0087]
However, when the movable magnet 13 is displaced, a vertical vector is generated in the direction of the repulsive force, so that the movable magnet 13 generates a force that is further pushed out in the displacement direction, that is, a negative stiffness. The negative stiffness obtained in the case of the second embodiment is also substantially the same as that obtained in the first embodiment.
[0088]
Similarly to 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]
As in the first embodiment, the Hall element 15 serving as a detecting means is arranged in the vertical and vertical directions near the center of the movable magnet 13 in the vertical direction. 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 in the first embodiment, the detection voltage level of the Hall element 15 is higher than that in 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, and specifically, the value of the resistor R8 in FIG. 2 is smaller than that of the first embodiment. This is because if the feedback loop gain is too high, there is a risk that oscillation will occur.
[0091]
The bass reproducing apparatus according to the second embodiment configured as described above has the same effect as that described in the first embodiment. In other words, the lowest resonance frequency, that is, the low-frequency reproduction limit frequency can be significantly extended from 96 Hz to slightly lower than 70 Hz by negative stiffness while correcting the bias in the displacement direction of the vibration system of the speaker unit 11.
[0092]
Further, in the present embodiment, since the generation of negative stiffness is not a mechanical means, there is no generation 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-frequency sound reproduction speaker device having a simple configuration, low cost, particularly high reliability, practical, and excellent low-frequency reproduction capability. Can be.
[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 periphery of the movable magnet 13 (in this case, the Hall element 15 may be arranged on the inner periphery of the movable magnet 13), or the fixed magnet 4 or the movable magnet 3 may be provided with an iron plate. Or a yoke or the like may be attached.
[0095]
In the present embodiment, the magnetizing direction of the movable magnet 13 and the fixed magnet 14 is set to the vertical direction, that is, the thickness direction of the magnet. However, the magnetizing may be performed in the radial direction so that they repel each other.
[0096]
In this embodiment, the Hall element 15 detects the magnetic flux of the movable magnet 13 that generates negative stiffness. However, a small magnet is attached to the vibration system separately from the movable magnet to detect the magnetic flux. May be.
[0097]
In addition, it goes without saying that the present invention is not limited to the examples described above.
[0098]
(Embodiment 3)
The configuration of the low-frequency sound reproduction speaker device according to the third embodiment of the present invention will be described with reference to FIG. 4, but a field part 21a, a frame 21b, a voice coil 21c, a damper 21d, an edge 21e, a diaphragm 21f, a cabinet 22, a fixed side. Since the supporting member 22a, the movable magnet 23, the spring 24, the detecting means 25, the feedback circuit 25a, and the power amplifier 26 are completely the same as those in the first embodiment described with reference to FIG. 1, a specific description thereof will be given here. Omitted.
[0099]
The present embodiment is different from the first embodiment in that means 27a, 27b, and 21g for holding the vibration system of the speaker unit 21 near the center position in the displacement direction when the low-frequency sound reproduction speaker device is not operating are provided.
[0100]
Reference numeral 27a denotes a small geared motor, and a rotary shaft 27b projects from the center. The distal end of the shaft 27b is bent in a U-shape so that the movable-side support member 21g can be sandwiched between the upper and lower sides with slight clearance. Reference numeral 21g denotes a movable support member to which a spring 24 also serving as a dust cap is attached, and a small relief hole having a size slightly larger than the front peripheral dimension of the bent end portion of the rotary shaft 27b is provided at the center.
[0101]
During operation of the bass reproduction speaker device, the direction of the bent end of the rotary shaft 27b matches the clearance hole of the movable-side support member 21g. Thus, during 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 of the rotary shaft 27b.
[0102]
When the low-frequency sound reproduction speaker device is not operating, for example, when the power of the low-frequency sound reproduction speaker device is turned off, the geared motor 27a rotates the rotary shaft 27b by several tens of degrees. Then, as shown in FIG. 4, the direction of the bent portion of the end of the rotary shaft 27 b is disengaged from the relief hole of the movable-side support member 21 g, and the movable-side support member 21 g is sandwiched from both upper and lower sides with a slight clearance, and the vibration system of the speaker unit 21 is moved. 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 power of the low-pitched sound reproduction speaker device is turned 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 rotating 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]
In order to cope with the case where the power of the bass reproduction speaker device is turned off, a relay that 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 cut off, and immediately after that, the geared motor 27a is operated to hold the vibration system of the speaker unit 21 near the center position in the displacement direction. Then, after the geared motor 27a stops, the entire power supply such as the power amplifier 26 and the feedback circuit 25 may be shut off by the relay.
[0105]
The bass reproducing apparatus of the present embodiment configured as described above can not only obtain the same effect as that described in the first embodiment, but also can reduce the vibration system of the speaker unit 21 when the bass reproducing speaker apparatus is not operating. Since it is held in the vicinity of the center position in the displacement direction, there is no long time skew to one side. For this reason, the stress due to the support system of the speaker unit 21, that is, the tension of the damper 21d and the edge 21e can be eliminated, so that the change with time and deterioration of the support system are reduced.
[0106]
In addition, since the spring 24 is also held at the equilibrium position, there is no concern that the negative stiffness of the spring 24 becomes vertically asymmetrical, which tends to occur when the spring 24 remains deformed for a long time.
[0107]
Therefore, as described above, according to the present embodiment, it is possible to realize a long-life low-frequency sound reproduction speaker device with little change over time.
[0108]
In the present embodiment, a slight air leak occurs from the escape hole of the movable-side support member 21g. It is more desirable to provide a hermetic cover on the movable side support member 21g because this 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 distal end portion of the movable-side support member 21g, but it goes without saying that other members or parts may be used.
[0110]
Further, in the present embodiment, 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, but this may be used as a rotary solenoid or other means.
[0111]
In addition, it goes without saying that the present invention is not limited to the examples described above.
[0112]
(Embodiment 4)
The configuration of the low-frequency sound reproduction speaker device according to the fourth embodiment of the present invention will be described with reference to FIG. 5, but a field part 31a, a frame 31b, a voice coil 31c, a damper 31d, an edge 31e, a diaphragm 31f, a 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 completely the same as those in the first embodiment described with reference to FIG. Is omitted.
[0113]
This embodiment also has a means for holding the vibration system of the speaker unit 31 in the vicinity of the center position in the displacement direction when the bass reproduction speaker device is not operating, similarly to the third embodiment, but uses a self-holding solenoid 37a. Is different. A plunger 37b that moves in the direction of the center axis projects from the center of the self-holding solenoid 37a, and the tip of the plunger 37b fits into a resin holding fitting member 37c attached to the bobbin of the voice coil 31c. Have been. A return spring 37d is mounted on the plunger 37b.
[0114]
During operation of the bass reproduction speaker device, as soon as the self-holding solenoid 37a is energized, the plunger 37b is instantaneously sucked, and the plunger 37b immediately comes off the holding fitting member 37c. When the bass reproduction speaker device is operated, the vibration system of the speaker unit 31 can move without the holding fitting member 37c contacting the tip of the plunger 37b.
[0115]
Since the solenoid 37a is a self-holding solenoid, the plunger 37b is kept in the suction state, so that the power can be released immediately after the suction. That is, energization is only required for a moment.
[0116]
When the bass reproduction speaker device is not operating, for example, when the power of the bass reproduction speaker device is turned off, the self-holding solenoid 37a is energized in the reverse direction. A so-called return current flows. Then, the plunger 37b is released from the suction state, and returns to the position of the holding fitting 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.
[0117]
FIG. 6 shows an example of a circuit diagram for controlling the operation of the self-holding solenoid 37a.
Yes. ACD is an AC primary side current detection circuit of the bass reproduction speaker device. The coil of the self-holding solenoid 37a is energized by using a large-capacity capacitor C2. The operation of this control circuit is as follows.
[0118]
When the power switch of the low-pitched sound reproduction speaker device is turned on, the AC primary current detection circuit ACD generates a detection electric signal, and a current starts flowing to the base of the transistor Q. A capacitor C1 and a resistor R are connected to the transistor Q, and the relay RR connected to the emitter of the transistor Q operates about one second after the power switch is turned on due to the time constant. The reason why the operation is performed 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, the terminal 1 and the terminal 2 are connected, and a current instantaneously flows from the power supply side to 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 for the capacitor C2, but only for a moment, so that it is not necessary to continuously supply unnecessary current to the self-holding solenoid 37a.
[0120]
When the power switch of the bass reproduction speaker device is turned off, the detected electric signal from the AC primary current detection circuit ACD disappears, so that the transistor Q is turned off and the relay RR is turned off. Then, the terminal 1 and the terminal 3 of the relay RR are connected, and the capacitor C1 discharges the self-holding solenoid 37a. The direction of the current at this time is opposite to that when the power switch of the bass reproduction speaker device is turned on. . In this way, a reverse current flows through the self-holding solenoid 37a, so that the plunger 37b can be returned. The terminals 4 and 6 of the relay RR are for discharging the time constant capacitor C1.
[0121]
The bass reproducing apparatus according to the present embodiment having the above-described configuration not only provides the same effects as those described in the third embodiment, but also operates the self-holding solenoid 37a instantaneously. As in the geared motor used in No. 3, the operation state can be quickly entered without taking much time.
[0122]
If there is no means for holding the vibration system of the speaker unit near the center position in the displacement direction, it is difficult to quickly turn on the bass reproduction speaker device after turning on the power. The reason is that when the bass reproduction speaker device is not operated, the vibration system is pushed away from the center position in the displacement direction by the force of the spring, and it takes some time to return to the center position in the displacement direction. is there.
[0123]
In this embodiment, the operating current of the self-holding solenoid 37a is supplied via 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, even if the power is suddenly cut off during the operation of the bass reproduction speaker device, for example, in the case of a power failure or accidental disconnection of the power outlet, the self-holding solenoid 37a is used by utilizing the charge stored in the capacitor C2. Since the return operation is performed, it is possible to hold the vicinity of the center position in the displacement direction 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 low-frequency sound reproduction speaker device which can not only change with time but has a long life but also can quickly enter an operation state and has high safety.
[0125]
In the present embodiment, the plunger 37b of the self-holding solenoid 37a is in the return state when the low-frequency sound reproduction speaker device is not operating, but the reverse design is also possible.
[0126]
Further, in the present embodiment, the self-holding type solenoid 37a is used, but it can be designed as a normal solenoid or another type of solenoid. However, when a self-holding solenoid is used, power can be saved only by momentarily flowing an operating current.
[0127]
In addition, it goes without saying that the present invention is not limited to the examples described above.
[0128]
(Embodiment 5)
The configuration of the low-frequency sound reproduction speaker device according to the fifth embodiment of the present invention will be described with reference to FIG. 7, but a field portion 41a, a frame 41b, a voice coil 41c, a damper 41d, an edge 41e, a diaphragm 41f, and a 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 completely the same as those in the first embodiment described with reference to FIG. Omitted.
[0129]
A characteristic feature of the present embodiment is that a movable rod 42b is provided in a fixed-side support member 42a for fixedly supporting, so that the negative stiffness of a spring 44 can be changed.
[0130]
More specifically, the four fixed-side support members 42a and the movable rod 42b in FIG. 7 have a built-in 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 that the movable rod 42b works as a stationary fixed end.
[0131]
When the low-frequency sound reproduction speaker device is not operated, the movable rod 42b is retracted to loosen the spring 44. During the operation of the bass reproduction speaker device, the movable rod 42b is advanced to apply a predetermined compressive force to the spring 44. Alternatively, by adjusting the rest position of the movable rod 42b, the compression force applied to the spring 44 can be adjusted, so that the generated negative stiffness can be varied.
[0132]
The bass reproducing apparatus of the present embodiment having the above-described configuration not only provides the same effects as those described in the first embodiment, but also can reduce the negative stiffness of the spring 44 when not operating. In addition, 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 deterioration of the support system are reduced.
[0133]
Also, since the negative stiffness generated by the spring 44 can be adjusted, the lowest resonance frequency of the low-frequency sound reproduction speaker device can be adjusted, and the low-frequency characteristics can be varied.
[0134]
Therefore, as described above, according to the present embodiment, it is possible to realize a low-frequency sound reproduction speaker device that not only has a small change over time but has a long service life, but also has a variable low-frequency characteristic.
[0135]
In the fifth embodiment, the means for providing the negative stiffness is a mechanical means, that is, the spring 44, but it may be a magnetic means as described in the second embodiment. In this case, for example, by using a fixed magnet as an electromagnet and adjusting the current supplied thereto, the generated negative stiffness can be varied.
[0136]
In addition, it goes without saying that the present invention is not limited to the examples described above.
[0137]
【The invention's effect】
As described above, according to the bass reproduction speaker device of the present invention, a bass reproduction speaker device including a speaker unit, means for providing a negative stiffness to a vibration system of the speaker unit, and a cabinet for accommodating the speaker unit. , A detecting means for generating an electric signal according to a displacement of a vibration system of the speaker unit, and a feedback circuit for feeding back the electric signal from the detecting means to a power amplifier for reproducing a source signal for driving the speaker unit. The power amplifier,In addition to the source signal power, the power for correcting the bias in the displacement direction of the vibration system of the speaker unit is,To the speaker unitAloneSupplyMeans for holding the vibration system of the speaker unit near the center position in the displacement direction when the bass reproduction speaker device is not operating.By
The speaker unit is provided with a servo that always corrects a slight bias in the displacement direction of the vibration system and maintains the original position in the center position in the displacement direction. Even if the negative stiffness is large, the average displacement center position of the vibration system is Not only is it possible to obtain an extremely stable operation held at the center position of the above, but also it is not necessary to separately provide an intake / exhaust pump or a control power amplifier as in the past in order to correct the bias in the displacement direction of the vibration system. Accordingly, it is possible to realize a low-frequency sound reproduction speaker device having a simple configuration, low cost and practical, and excellent low-frequency reproduction capability.Furthermore, when the low-frequency sound reproduction speaker device is not operated, the vibration system of the speaker unit is not biased to one side in the displacement direction and does not elapse for a long time, and a long-time stress is not applied to the support system and the spring of the speaker unit. Therefore, a long-life low-frequency sound reproduction speaker device with little change over time can be realized.
[0139]
Claims of the invention2According to the bass speaker device described above, the means for giving negative stiffness to the vibration system of the speaker unit is provided between the center of the vibration system of the speaker unit and the vicinity of the outer periphery of the speaker unit. Since the spring is attached by being compressed at a plurality of locations, the length of the spring can be increased, and the mechanical fatigue can be reduced. Therefore, a highly reliable bass reproduction speaker device can be realized.
[0140]
Claims of the invention3According to the bass reproduction speaker device described above, means for providing a negative stiffness to the vibration system of the speaker unit includes a movable magnet that moves together with the vibration system of the speaker unit, and a vibration displacement direction of the speaker unit with respect to the movable magnet. With a fixed magnet that gives the power ofThe fixed magnet and the movable magnet are arranged at the same vertical center position.As a result, since the generation of negative stiffness is not a mechanical means, there is no generation of mechanical fatigue. Therefore, a particularly reliable bass reproduction speaker device can be realized.
[0142]
Claims of the invention4According to the bass reproduction speaker device described,,By using a self-holding solenoid as means for holding the vibration system of the speaker unit near the center position in the displacement direction, it is instantaneous to hold or release the vibration system of the speaker unit near the center position in the displacement direction. I can do it. Therefore, it is possible to realize a low-frequency sound reproduction speaker device that can be quickly put into an operating state.
[0143]
Claims of the invention5According to the bass reproduction speaker device described above, the operating current of the self-holding solenoid is supplied via a capacitor, and the return current of the self-holding solenoid is supplied by discharging the capacitor. Even if the power is suddenly cut off during the operation of the speaker unit, the vicinity of the center position in the displacement direction of the vibration system of the speaker unit can be held. Accordingly, a low-pitched sound reproduction speaker device with high security can be realized.
[0146]
As described above, the present invention has an extremely large practical value.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view and a front view showing a configuration of a low-frequency sound reproduction speaker device according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a feedback circuit according to the first embodiment of the present invention;
FIG. 3 is a cross-sectional view and a front view showing a configuration of a low-frequency sound reproduction speaker device according to a second embodiment of the present invention.
FIG. 4 is a cross-sectional view and a front view showing a configuration of a low-frequency sound reproduction speaker device according to a third embodiment of the present invention.
FIGS. 5A and 5B are a cross-sectional view and a front view showing a configuration of a bass reproduction speaker device having another configuration according to Embodiment 3 of the present invention. FIGS.
FIG. 6 is a diagram illustrating an example of a control circuit that controls the operation of the solenoid according to the embodiment;
FIG. 7 is a cross-sectional view and a front view showing a configuration of a low-frequency sound reproduction speaker device according to a fourth embodiment of the present invention.
FIG. 8 is a cross-sectional view and a front view showing the configuration of a conventional bass reproduction speaker device.
FIG. 9 is a cross-sectional view and a front view showing the configuration of a conventional bass reproduction speaker device.
FIG. 10 is an explanatory diagram showing the operation of a spring that provides negative stiffness.
FIG. 11 is a graph showing displacement to force characteristics of stiffness.
[Explanation of symbols]
1,11,21,31,41 Speaker unit
1a, 11a, 21a, 31a, 41a Field part
1b, 11b, 21b, 31b, 41b frames
1c, 11c, 21c, 31c, 41c Voice coil
1d, 11d, 21d, 31d, 41d Damper
1e, 11e, 21e, 31e, 41e Edge
1f, 11f, 21f, 31f, 41f diaphragm
1g, 21g, 31g, 41g Movable support member
11g dust cap
11h Support member
2,12,22,32,42 cabinet
2a, 22a, 32a, 42a Fixed-side support member
42b Movable rod
3,13,23,33,43 Movable magnet
4,24,34,44 Spring
14 Fixed magnet
5,15,25,35,45 Hall element
5a, 15a, 25a, 35a, 45a Feedback circuit
6,16,26,36,46 Power amplifier
27a Gear motor
37a Self-holding solenoid
27b Rotary shaft
37b plunger
37c Holding fitting member
37d return spring

Claims (5)

In a low-frequency sound reproduction speaker device including a speaker unit, means for providing a negative stiffness to a vibration system of the speaker unit, and a cabinet accommodating the speaker unit, an electric signal corresponding to a displacement of the vibration system of the speaker unit is provided. Detecting means for generating, and a feedback circuit for feeding back an electric signal from the detecting means to a power amplifier for reproducing a source signal for driving the speaker unit, wherein the power amplifier includes the power of the speaker unit in addition to the source signal power. power for correcting the displacement direction of the deviation of the vibration system, supplied solely to said speaker unit, also the time to the non-operation of the bass reproduction speaker apparatus, means for holding the vibration system of the speaker unit in the vicinity of the displacement direction center position A low-frequency sound reproduction speaker device comprising: Means for imparting negative stiffness to the vibration system of the speaker unit are compressed and attached to a plurality of locations substantially on the center axis between the center of the vibration system of the speaker unit and the vicinity of the outer periphery of the speaker unit. The low-frequency sound reproduction speaker device according to claim 1 , wherein the speaker is a spring. Means for giving a negative stiffness to the vibration system of the speaker unit, 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 ; The low-frequency sound reproduction speaker device according to claim 1 , wherein the fixed magnet and the movable magnet are arranged at the same vertical center position . During non-operation, as a means for holding the vibration system of the speaker unit in the vicinity of the displacement direction central position, characterized by using a self-hold solenoid, bass reproduction speaker apparatus according to claim 1. The bass reproduction speaker device according to claim 4 , wherein the operating current of the self-holding solenoid is supplied via a capacitor, and the return current of the self-holding solenoid is supplied by discharging the capacitor.

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