JP2013172416A - Speaker and suppression method of standing-wave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a speaker which can suppress standing-wave excellently without a microphone.SOLUTION: A speaker 1 includes a cylindrical body 3, a first exciter 4 secured to a first surface of the cylindrical body 3, a second exciter 5 secured to a second surface of the cylindrical body 3 facing the first surface, and a control unit 6 for controlling the first and second exciters 4, 5. The control unit 6 controls the first exciter 4 on the basis of an acoustic signal, and controls the second exciter 5 based on a signal obtained by inverting the phase of frequency component of a standing-wave generated by the first and second exciters 4, 5 facing each other, for the acoustic signal.

Description

  The present invention relates to a speaker and a standing wave suppressing method, and more particularly to a speaker and a standing wave suppressing method in which substantially the same sound is reproduced from a facing surface.

  In a speaker configured to reproduce substantially the same sound from the opposing surfaces, standing waves are generated between the opposing surfaces. For example, as shown in FIG. 6A, a speaker 100 in which exciters 102 and 103 are fixed on opposite surfaces of a cylinder 101 is configured, and the phases, amplitudes, and frequencies of acoustic signals that drive the exciters 102 and 103 are made equal. Is assumed.

  Here, the acoustic characteristics on the surface 104 at the height position of the exciters 102 and 103 in FIG. 6A are shown by acoustic intensity in FIG. 6B, and the acoustic characteristics on the surface 105 at the height position of the top plate of the cylinder 101. Is shown by acoustic intensity in FIG. 6C.

  On the surface 104, as shown in FIG. 6B, sound interferes with each other in the hollow portion of the cylinder 101, and the waveform is doubled because the phases are the same. On the surface 105, as shown in FIG. 6C, the vibrations of the exciters 102 and 103 are transmitted to the top plate of the cylindrical body 101, and the vibrations are in phase so that the vibrations increase.

  In this way, the level increases at a specific frequency, and the speaker configured to reproduce substantially the same sound from the opposite surface has a problem that it is difficult to make the frequency characteristics constant.

  By the way, in the audio system of patent document 1, the frequency which a standing wave produces with a microphone is detected, and only the sound which reversed the phase of the said frequency component in an acoustic signal from a predetermined speaker is output, and a standing wave is output. Suppressed.

JP 2000-115883 A

  The audio system of Patent Document 1 is a technology that can suppress standing waves. However, when the technology is applied to a speaker having an exciter fixed to opposite surfaces of a cylindrical body, a microphone is provided in the hollow portion of the cylindrical body. It is necessary to arrange, and it is difficult to make the cylinder hollow.

  An object of the present invention is to solve such problems, and provides a speaker and a standing wave suppressing method that can satisfactorily suppress standing waves while omitting a microphone. It is.

A speaker according to an aspect of the present invention is fixed to a cylindrical body, a first exciter fixed to the first surface of the cylindrical body, and a second surface of the cylindrical body facing the first surface. A second exciter, and a control unit that controls the first and second exciters, the control unit controlling the first exciter based on an acoustic signal, and the second exciter. Is controlled based on a signal obtained by inverting the phase of the frequency component of the standing wave generated by the first and second exciters facing each other with respect to the acoustic signal.
In the speaker, the control unit includes a band-pass filter that passes a frequency component of the standing wave in the acoustic signal, an inverter that inverts an output signal of the band-pass filter, and the standing signal from the acoustic signal. A band elimination filter that removes a frequency component of the wave, an adder that adds the output signal of the inverter and the output signal of the band elimination filter, and outputs the resultant signal to the second exciter. preferable.
In the speaker, it is preferable that the frequency component in which the standing wave is generated is calculated based on a distance between the first surface and the second surface of the cylindrical body.
In the speaker, it is preferable that one channel signal of stereo signals is input to the first exciter and the control unit.
In the speaker, it is preferable that a first monaural signal is input to the first exciter, and a second monaural signal is input to the control unit.
A standing wave suppressing method according to an aspect of the present invention includes a cylindrical body, a first exciter fixed to the first surface of the cylindrical body, and a first surface facing the first surface of the cylindrical body. A second exciter fixed to the second surface, and a control unit that controls the first and second exciters, wherein the first and second exciters operate to generate substantially equal sounds. A method for suppressing standing waves in a speaker, wherein the first exciter is controlled based on an acoustic signal, and the second exciter is opposed to the acoustic signal. Control is performed based on a signal obtained by inverting the phase of the frequency component of the standing wave generated by the exciter.

  As described above, according to the present invention, there is provided a speaker and a standing wave suppressing method that can satisfactorily suppress standing waves while omitting a microphone.

It is a block diagram which shows the speaker unit using the speaker which concerns on Embodiment 1 of this invention. It is a perspective view which shows the exciter used for the speaker which concerns on Embodiment 1 of this invention. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. It is a figure for demonstrating the suppression effect of the standing wave in the speaker which concerns on Embodiment 1 of this invention. It is a figure for demonstrating the suppression effect of the standing wave in the speaker which concerns on Embodiment 1 of this invention. It is a figure for demonstrating the suppression effect of the standing wave in the speaker which concerns on Embodiment 1 of this invention. It is a block diagram which shows the speaker which concerns on Embodiment 2 of this invention. It is a figure for demonstrating generation | occurrence | production of the standing wave in the conventional speaker. It is a figure for demonstrating generation | occurrence | production of the standing wave in the conventional speaker. It is a figure for demonstrating generation | occurrence | production of the standing wave in the conventional speaker.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

<Embodiment 1>
Two speakers according to the present embodiment are prepared as shown in FIG. 1, and form a speaker unit for stereo reproduction.

  First, the configuration of the speaker unit will be described. The speaker unit of this embodiment includes a first speaker 1 and a second speaker 2.

  In order to realize stereo reproduction, a first acoustic signal (R side channel signal) is input to the first speaker 1 from, for example, an amplifier. The first speaker 1 includes a cylindrical body 3, a first exciter 4, a second exciter 5, and a control unit 6. The cylinder 3 is formed in a substantially prismatic shape including four plate bodies 7. The plate body 7 has a substantially square shape and is connected so as to be orthogonal to other adjacent plate bodies 7.

  That is, the cylindrical body 3 has openings on two opposing surfaces, and a cavity is formed inside so as to include the openings. Incidentally, the cylinder 3 of the present embodiment is made of wood, but is not particularly limited as long as it is a material capable of outputting sound by vibration.

  As shown in FIG. 1, the first exciter 4 is fixed to one opposing plate 7 in the cylinder 3. As the first exciter 4, a general exciter can be used.

  As shown in FIG. 2, the first exciter 4 of the present embodiment has a substantially disk shape. As shown in FIG. 3, the first exciter 4 includes a bobbin side vibration member 9 including a bobbin portion 8 and a magnetic circuit side vibration member 10. An electric coil L is wound around the bobbin portion 8.

  The magnetic circuit side vibration member 10 includes a magnetic circuit portion F including a yoke 11 and a ring-shaped permanent magnet 12. The magnetic circuit part F forms a magnetic gap into which the electric coil L provided on the bobbin part 8 is inserted.

  The bobbin side vibration member 9 and the magnetic circuit side vibration member 10 are elastically connected by a damper 13. With the above configuration, when a signal is input to the electric coil L, the distance d between the bobbin-side vibrating member 9 and the magnetic circuit-side vibrating member 10 changes according to the signal.

  As shown in FIG. 1, the second exciter 5 is fixed to a plate body 7 facing the plate body 7 to which the first exciter 4 in the cylindrical body 3 is fixed. The second exciter 5 has the same configuration as that of the first exciter 4, and therefore a duplicate description is omitted.

  The control unit 6 controls the first exciter 4 based on the first acoustic signal from the amplifier and the like, and the second exciter 5 generates a standing wave with respect to the first acoustic signal from the amplifier and the like. Control is performed based on a signal obtained by inverting the phase of the frequency component. Specifically, as shown in FIG. 1, the control unit 6 includes a band pass filter 14, an inverter 15, a band elimination filter 16, and an adder 17.

  The band pass filter 14 is a general Band Pass Filter. The first acoustic signal is input to the band pass filter 14 from an amplifier or the like. The band pass filter 14 outputs only a frequency component in which a standing wave in the input first acoustic signal is generated to the inverter 15. That is, the band pass filter 14 extracts only the frequency component in which a standing wave is generated from the first acoustic signal. In other words, the band pass filter 14 removes frequency components other than the frequency component in which a standing wave is generated from the input first acoustic signal.

  Here, the frequency at which the standing wave is generated is the distance T (see FIG. 1) between the plate 7 to which the first exciter 4 is fixed and the plate 7 to which the second exciter 5 is fixed. Since it is fixed, it can be calculated based on the interval T. For example, the frequency T of the standing wave can be calculated by <Equation 1> under the condition that the interval T is 34 cm and the room temperature is normal.

<Formula 1>
f = v _s / T = 340/34/100 = 1000 [Hz] = 1 [kHz]
Here, v _s is the speed of sound under normal temperature conditions.

  Therefore, the band-pass filter 14 has a standing wave calculated based on the interval T between the plate 7 to which the first exciter 4 is fixed and the plate 7 to which the second exciter 5 is fixed. The generated frequency component is set to be extracted from the first acoustic signal. That is, the band pass filter 14 of the present embodiment is set so as to extract a frequency component of 1 kHz from the first acoustic signal.

  The inverter 15 receives a frequency component signal from which a standing wave in the first acoustic signal is generated from the bandpass filter 14. The inverter 15 inverts the signal and outputs it to the adder 17.

  The band elimination filter 16 is a general Band Eliminate Filter. The first acoustic signal is also input to the band elimination filter 16 from an amplifier or the like. That is, the acoustic signal input to the band elimination filter 16 is equal to the acoustic signal input to the band pass filter 14. The band elimination filter 16 removes only the frequency component in which the standing wave in the input first acoustic signal is generated, and outputs it to the adder 17. In other words, the band elimination filter 16 extracts frequency components other than the frequency component in which a standing wave is generated from the first acoustic signal.

  The band elimination filter 16 generates a standing wave calculated based on the interval T between the plate 7 to which the first exciter 4 is fixed and the plate 7 to which the second exciter 5 is fixed. The frequency component is set to be removed from the first acoustic signal. That is, the band elimination filter 16 of the present embodiment is set so as to remove the 1 kHz frequency component from the first acoustic signal.

  The adder 17 adds the output signal of the inverter 15 and the output signal of the band elimination filter 16 and outputs the result to the second exciter 5. Accordingly, the second exciter 5 vibrates based on a signal obtained by inverting only the phase of the frequency component in which the standing wave is generated with respect to the first acoustic signal input from the amplifier or the like. On the other hand, the first exciter 4 to which the first acoustic signal such as an amplifier is input from the control unit 6 vibrates based on the first acoustic signal input from the amplifier or the like.

  Such a first speaker 1 functions as one speaker for stereo reproduction because the first exciter 4 and the second exciter 5 vibrate so that the plate body 7 forming the cylindrical body 3 vibrates. .

  At this time, the first exciter 4 vibrates based on the first acoustic signal input from the amplifier or the like, and the second exciter 5 is stationary with respect to the first acoustic signal input from the amplifier or the like. Since only the phase of the frequency component in which the wave is generated vibrates based on the inverted signal, substantially the same sound is reproduced with the hollow portion of the cylindrical body 3 interposed therebetween.

  The second speaker 2 has the same configuration except that the second acoustic signal (L-side channel signal) is input to the first speaker 1 from an amplifier or the like. Is omitted, but includes a cylinder 18, a first exciter 19, a second exciter 20, and a control unit 21. And the control part 21 is equipped with the band pass filter 22, the inverter 23, the band removal filter 24, and the adder 25, and controls the 1st exciter 19 based on the 2nd acoustic signal from amplifier etc., The second exciter 20 is controlled based on a signal obtained by inverting the phase of a frequency component in which a standing wave is generated with respect to a second acoustic signal from an amplifier or the like. Thereby, the 1st exciter 19 vibrates based on the 2nd acoustic signal input from amplifier etc. FIG. The second exciter 20 vibrates based on a signal obtained by inverting only the phase of a frequency component in which a standing wave is generated with respect to a second acoustic signal input from an amplifier or the like.

  In such a second speaker 2, the first exciter 19 and the second exciter 20 vibrate, so that the plate 7 constituting the cylindrical body 18 vibrates and functions as the other speaker for stereo reproduction. .

  At this time, the first exciter 19 vibrates based on the second acoustic signal input from the amplifier or the like, and the second exciter 20 is stationary with respect to the second acoustic signal input from the amplifier or the like. Since only the phase of the frequency component in which the wave is generated vibrates based on the inverted signal, substantially the same sound is reproduced with the hollow portion of the cylindrical body 3 interposed therebetween.

  Therefore, with the first speaker 1 and the second speaker 2, the speaker unit of the present embodiment can realize stereo reproduction.

  Next, suppression of standing waves in the first speaker 1 and the second speaker 2 of the present embodiment will be described. In the following description, since the first speaker 1 and the second speaker 2 have the same configuration except for an input acoustic signal, the suppression of the standing wave on the first speaker 1 side is performed. The explanation will be omitted, and the explanation about the suppression of the standing wave on the second speaker 2 side will be omitted.

  When the first exciter 4 and the second exciter 5 are vibrated and the sound is reproduced from the first speaker 1, at a frequency at which a standing wave is generated, the sound wave based on the vibration of the first exciter 4 is applied. Since the sound waves based on the vibrations of the second exciter 5 have opposite phases, they cancel each other.

  Here, the effect of suppressing the standing wave in the first speaker 1 of the present embodiment will be confirmed with reference to FIG. The acoustic characteristics of the first exciter 4 and the second exciter 5 at the height position surface 26 in FIG. 4A are shown in FIG. 4B as acoustic intensity, and the top surface height surface 27 of the cylinder 3 is shown. The acoustic characteristics are shown in FIG. 4C as acoustic intensity.

  On the surface 26, as shown in FIG. 4B, the sound wave based on the vibration of the first exciter 4 and the sound wave based on the vibration of the second exciter 5 cancel each other in the hollow portion of the cylindrical body 3, and the sound level is reduced. You can see that it is getting smaller. Further, on the surface 27, as shown in FIG. 4C, the vibration of the first exciter 4 and the vibration of the second exciter 5 transmitted to the top plate of the cylindrical body 3 cancel each other, and the vibration is attenuated. I understand.

  As described above, the first speaker 1 of the present embodiment can satisfactorily suppress the standing waves generated by the first and second exciters 4 and 5 facing each other, and makes the frequency characteristics substantially constant. be able to. Therefore, a speaker having excellent sound reproducibility can be realized.

  At this time, in the present embodiment, the frequency at which a standing wave is generated based on the interval T between the plate 7 to which the first exciter 4 is fixed and the plate 7 to which the second exciter 5 is fixed. Since the standing wave can be suppressed based on the calculated frequency, the standing wave can be satisfactorily suppressed while omitting the conventionally used microphone.

  Therefore, the inside of the cylinder 3 can be made hollow, and the design of the speaker can be improved.

  In addition, when a microphone is arranged in the hollow portion of the cylinder 3 and the frequency at which a standing wave is generated is detected, it is difficult to accurately detect the frequency at which the standing wave is generated due to sound interference with the microphone. In the embodiment, the frequency at which the standing wave is generated is calculated based on the interval T between the plate body 7 to which the first exciter is fixed and the plate body 7 to which the second exciter is fixed. The frequency at which the standing wave is generated can be accurately derived, and the standing wave can be suppressed with high accuracy.

  In addition, since the microphone can be omitted, it is possible to contribute to downsizing and cost reduction of the speaker.

  Incidentally, as shown in FIG. 4B and FIG. 4C, at a frequency at which a standing wave is generated, between the plate body 7 to which the first exciter 4 is fixed and the plate body 7 to which the second exciter 5 is fixed. Since the sound is reduced, the speaker according to the present embodiment is configured to have directivity toward the outside of the plate body 7.

<Other embodiments>
In Embodiment 1, the speaker is used for stereo reproduction, but may be used for monaural reproduction.

  That is, as shown in FIG. 5, the speaker 28 of the present embodiment has a configuration substantially the same as that of the first speaker 1 or the second speaker 2 of the first embodiment. The exciter 30, the second exciter 31, and the controller 32 are provided. The control unit 32 includes a band pass filter 33, an inverter 34, a band removal filter 35, and an adder 36.

  The speaker 28 of the present embodiment inputs a first acoustic signal (first monaural signal) from an amplifier or the like to the first exciter 30. Then, a second acoustic signal (second monaural signal) is input from an amplifier or the like to the control unit 32 that controls the second exciter 31. Here, the first monaural signal and the second monaural signal are equal signals. Therefore, as a result, the second exciter 31 is controlled based on a signal obtained by inverting the phase of the frequency component in which the standing wave is generated with respect to the first monaural signal.

  Therefore, even in the speaker 28 having such a configuration, the first and second exciters 30 and 31 facing each other are omitted while omitting the microphone, as in the first speaker 1 or the second speaker 2 of the first embodiment. It is possible to satisfactorily suppress the standing wave generated by.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 1st speaker 2 2nd speaker 3 Cylindrical body 4 1st exciter 5 2nd exciter 6 Control part 7 Plate body 8 Bobbin part 9 Bobbin side vibration member 10 Magnetic circuit side vibration member 11 Yoke 12 Permanent magnet 13 Damper 14 Band-pass filter 15 Inverter 16 Band-rejection filter 17 Adder 18 Tube 19 First exciter 20 Second exciter 21 Control unit 22 Band-pass filter 23 Inverter 24 Band-rejection filter 25 Adders 26 and 27 Surface 28 Speaker 29 Cylindrical body 30 1st exciter 31 2nd exciter 32 Control part 33 Band pass filter 34 Inverter 35 Band elimination filter 36 Adder 100 Speaker 101 Cylindrical body 102 Exciters 104 and 105 Surface F Magnetic circuit part f Frequency L Electric coil T interval

Claims (6)

A cylinder,
A first exciter fixed to the first surface of the cylinder;
A second exciter fixed to a second surface opposite to the first surface of the cylindrical body;
A controller for controlling the first and second exciters,
The controller is
Controlling the first exciter based on an acoustic signal;
A speaker that controls the second exciter based on a signal obtained by inverting the phase of a frequency component of a standing wave generated by the first and second exciters facing each other with respect to the acoustic signal. The controller is
A bandpass filter that passes the frequency component of the standing wave in the acoustic signal;
An inverter for inverting the output signal of the bandpass filter;
A band elimination filter for removing the frequency component of the standing wave from the acoustic signal;
An adder that adds the output signal of the inverter and the output signal of the band elimination filter and outputs the resultant signal to the second exciter;
A speaker according to claim 1.   The speaker according to claim 1 or 2, wherein the frequency component of the standing wave is calculated based on a distance between a first surface and a second surface of the cylindrical body.   The speaker according to any one of claims 1 to 3, wherein one channel signal of stereo signals is input to the first exciter and the control unit. A first monaural signal is input to the first exciter,
The speaker according to claim 1, wherein a second monaural signal is input to the control unit. A cylinder,
A first exciter fixed to the first surface of the cylinder;
A second exciter fixed to a second surface opposite to the first surface of the cylindrical body;
A controller for controlling the first and second exciters, wherein the first and second exciters operate to generate substantially equal sounds, and the method of suppressing standing waves in a speaker,
Controlling the first exciter based on an acoustic signal;
Standing wave suppression for controlling the second exciter based on a signal obtained by inverting the phase of the frequency component of the standing wave generated by the first and second exciters facing each other with respect to the acoustic signal. Method.

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