EP1221824B1 - Dispositif a haut-parleur - Google Patents

Dispositif a haut-parleur Download PDF

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Publication number
EP1221824B1
EP1221824B1 EP00950015A EP00950015A EP1221824B1 EP 1221824 B1 EP1221824 B1 EP 1221824B1 EP 00950015 A EP00950015 A EP 00950015A EP 00950015 A EP00950015 A EP 00950015A EP 1221824 B1 EP1221824 B1 EP 1221824B1
Authority
EP
European Patent Office
Prior art keywords
microphone
speaker unit
subtracter
output signal
pass filter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP00950015A
Other languages
German (de)
English (en)
Other versions
EP1221824A4 (fr
EP1221824A1 (fr
Inventor
Hidekazu Tanaka
Fumiyasu Konno
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Publication of EP1221824A1 publication Critical patent/EP1221824A1/fr
Publication of EP1221824A4 publication Critical patent/EP1221824A4/fr
Application granted granted Critical
Publication of EP1221824B1 publication Critical patent/EP1221824B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/002—Damping circuit arrangements for transducers, e.g. motional feedback circuits

Definitions

  • the present invention relates to a loudspeaker (speaker) device for use in various acoustic apparatus and television receivers; more specifically, a speaker unit coupled with an acoustic pipe disposed in front of the speaker, wherein the acoustic pipe has a microphone for detecting sounds reproduced by the speaker unit, and sounds from the speaker unit are corrected in accordance with the signals detected by the microphone.
  • FIG. 7 is a block diagram
  • FIG. 8 (A) shows microphone output signals
  • FIG. 8 (B) shows sound output characteristics of the conventional speaker device, where, curve "a” shows a sound pressure characteristic, "b” a phase characteristic.
  • curve "a” shows a sound pressure characteristic
  • "b” a phase characteristic.
  • JP 07 162 990 A JP 07 162 990 A.
  • a speaker unit 1 generates sound waves, and the speaker unit 1 is coupled with an acoustic pipe 2. At both sides of the acoustic pipe 2 are sound absorbing material (not shown) provided for suppressing resonance. Inside the acoustic pipe 2, a microphone 4 is provided close to the speaker unit 1 for detecting sound output signals.
  • the speaker unit 1 radiates acoustic output, which is radiated from the opening through the acoustic pipe 2.
  • the standing wave due to a length of the acoustic pipe 2 and the one generated within the acoustic pipe 2 cause a speaker device to reproduce sounds having steep peaks and dips in the sound pressure frequency characteristic.
  • a sound absorbing material is employed to suppress the standing waves.
  • the sound absorbing material is not effective enough to suppress the standing waves completely. So, a microphone 4 detects the remaining standing wave and feeds it back to the subtracter 6 via a microphone amplifier 5.
  • the standing wave in acoustic pipe 2 is suppressed, and the reproduced sounds with a flat sound pressure frequency characteristic were obtained.
  • f ( n + 1 ) C / 4 L
  • f pipe resonance frequency
  • n the n-th resonance
  • C sound velocity
  • L length of the pipe
  • V out / V in A / ( 1 + A ⁇ T ( S ) )
  • V out output voltage
  • V in input voltage
  • A total amplification by amplifiers
  • T (S) transfer function
  • the T (S) becomes minus 1 as a result of phase shift caused by the speaker unit 1 and the second, or the third, pipe resonance of acoustic pipe 2.
  • the denominator becomes 0 to be ready for making oscillation. This makes it difficult to apply too many feedbacks taking an oscillation margin into consideration, and to effectively control a low frequency region and a pipe resonance.
  • the present invention addresses the above problems and aims to provide a speaker device that has stable characteristics.
  • a speaker device of the present invention comprises a power amplifier which receives input signal via subtracter, a speaker unit for reproducing output signal of the power amplifier, an acoustic pipe coupled to the speaker unit in the front for guiding sound waves generated by the speaker unit, a microphone for detecting acoustic outputs radiated from the speaker unit, and a microphone amplifier for amplifying acoustic output signals detected by the microphone.
  • output signals of the microphone amplifier are delivered to the subtracter, and, at the same time, output signals of the above microphone amplifier are delivered via a high-pass filter also to the substacter to form a negative feedback circuit in order to suppress peaks and dips in the sound pressure frequency characteristics.
  • the speaker device is provided with stable characteristics.
  • FIG. 1 shows a block diagram of an acoustic circuit in accordance with a first exemplary embodiment of the present invention.
  • FIG. 2 is a sound output characteristic chart; where, curve "a” shows the sound pressure characteristic, while “b” shows the phase characteristic. In the first place, overall structure of the speaker device is described referring to FIG. 1.
  • an acoustic pipe 2 is coupled to the speaker unit 1, and a microphone 4 is mounted within the acoustic pipe 2. Sound wave radiated from the speaker unit 1 are detected by the microphone 4 within the acoustic pipe 2. The detected signals are delivered to a subtracter 6 via a high-pass filter 7, and at the same time, the signals detected by the microphone 4 are input directly to the subtracter 6 to be mixed with input signals coming from outside for correcting the input signals. The corrected signals are amplified at a power amplifier 13 and delivered to the speaker unit 1.
  • the acoustic pipe 2 is disposed in front of a speaker box (not shown) in which the speaker unit 1 is mounted, and sound waves are guided by the acoustic pipe 2 to be radiated from a narrow slit opening of a rectangular shape.
  • the microphone 4 detects resonance in the acoustic pipe 2, and feeds an acoustic output signals thus detected back to the subtracter 6 via a secondary high-pass (-12dB/oct) filter 7. At the same time, the acoustic output signals are fed back directly to the subtracter 6.
  • FIG. 2 shows a sound output characteristic.
  • FIG. 8 (B) which shows the conventional counterpart, the peak due to a shift of resonance component caused by phase shift is not seen in FIG. 2.
  • Frequency characteristics of a speaker device in the present embodiment have been flattened, without having a shift of the resonance component.
  • the resonance in the acoustic pipe 2 is detected by microphone 4, and the acoustic output signals thus detected are delivered via the secondary high-pass filter 7 (-12dB/oct) to the subtracter 6 as the feedback.
  • the signals detected by the microphone 4 are also delivered directly to the subtracter 6.
  • a cutoff frequency of secondary high-pass filter 7 (-12dB/oct) are set to match with the resonance frequency of the pipe.
  • FIG. 3 shows a block diagram of a sound circuit in accordance with a second exemplary embodiment of the present invention.
  • FIG. 4 (A) shows a microphone output signal characteristic
  • FIG. 4 (B) shows an acoustic output characteristics, where, curve "a” shows a sound pressure characteristic, while “b” shows a phase characteristic.
  • a difference with the first embodiment is that a negative feedback circuit in the present embodiment is formed by delivering the acoustic output signals detected by microphone 4 to the subtracter 6 via a couple of high-pass filters 7 and 8 connected in parallel.
  • the filter 7 is the secondary high-pass filter (-12dB/oct), while the filter 8 is the primary high-pass filter (6dB/oct).
  • FIG. 8 (A) which shows the frequency characteristic of the microphone signal of the conventional device
  • the feedback is preformed covering even the low frequency region components, which means the low frequency region components are enhanced.
  • the level of low frequency region components is lowered as shown in the characteristic chart, as is shown in FIG. 4 (A). This means that the low frequency region components are not enhanced in the present embodiment.
  • the negative feedback circuit in the present embodiment is provided with a couple of primary and secondary high-pass filters 8 and 7 connected in parallel, and output signals of the microphone amplifier 5 are connected thereto to be delivered to the subtracter 6.
  • the circuit can feed back those microphone output signals only in the vicinity of the resonance frequency component, so, the enhancement of the low frequency region components is suppressed.
  • the output frequency characteristics can be flattened and corrected, and a speaker device of superior sound characteristics is provided.
  • FIG. 5 shows a block diagram of a sound circuit in accordance with a third exemplary embodiment of the present invention.
  • FIG. 6 (A) shows the microphone output signal characteristics
  • FIG. 6 (B) shows the sound output characteristics; where, curve "a” shows the sound pressure characteristic, while “b” shows the phase characteristic.
  • a difference with the first embodiment is that a negative feedback circuit in the present embodiment is formed of a couple of filters 7 and 9.
  • a secondary high-pass filter 7 for processing the output signal detected by the microphone 4 and delivering to the subtracter 6, and a low-pass filter 9 of -12dB/oct, or -6dB/oct, for processing the output signal detected by the microphone 4 and delivering to the subtracter 6.
  • the low-pass filter 9 can take out only the low frequency region components for phase correction. Thus the output sound characteristic can be corrected for the low frequency region components alone.
  • the secondary high-pass filter 7 can correct the acoustic pipe resonance independently and arbitrary. In this way, the output frequency characteristics can be flattened and corrected easily and arbitrary, and a speaker device of superior sound characteristics is provided in accordance with the present embodiment.
  • n-th resonance (n being a positive integer) of the pipe can of course be controlled in accordance with the present invention.
  • the present invention can be applied also to those speaker devices whose back cover for coupling with the acoustic pipe is a bass reflective type, or having no back cover at all.
  • the speaker devices of the present invention comprise a power amplifier which receives input signal via a subtracter, a speaker unit for reproducing output signal of the power amplifier, an acoustic pipe coupled in a front of the speaker unit for guiding sound waves from the speaker unit, a microphone for detecting acoustic outputs radiated from the speaker unit, and a microphone amplifier for amplifying the sound output signals detected by the microphone.
  • the speaker device having a negative feedback circuit formed by direct connection of the output signal of microphone amplifier to the subtracter and by connection of the above output signal of microphone amplifier via a high-pass filter to the subtracter, makes the phase correction and suppresses the peak due to a shift of resonance frequency component, the shift being caused by a phase change.
  • the direct feedback of microphone output signal enables to enhance the low frequency region components. The output frequency characteristics are thus flattened and the low frequency sound reproduction is improved to provide a speaker device of superior sound characteristics.
  • a speaker device comprising a power amplifier which receives input signal via a subtracter, a speaker unit for reproducing output signal from the power amplifier, an acoustic pipe coupled to a front of the speaker unit for guiding sound waves, a microphone for detecting acoustic outputs radiated from the speaker unit, and a microphone amplifier for amplifying acoustic output signals detected by the microphone, and a negative feedback circuit formed of a couple of primary and secondary high-pass filters disposed in parallel for connecting the output signals from microphone amplifier to the subtracter, the microphone output signals can be fed back only in the vicinity of the resonance frequency component. As a result, an enhancement in the low frequency region components can be suppressed. Thus the output frequency characteristics can be easily flattened and corrected for providing a speaker device of superior sound characteristics.
  • a speaker device comprising a power amplifier which receives input signal via subtracter, a speaker unit for reproducing output signal of the power amplifier, an acoustic pipe coupled in a front of the speaker unit for guiding sound waves, a microphone for detecting sound outputs radiated from the speaker unit, and a microphone amplifier for amplifying the sound output signals detected by the microphone, and a negative feedback circuit formed of a secondary high-pass filter and a primary, or a secondary, low-pass filter disposed in parallel to be connected to the subtracter, the output signals of microphone amplifier can be fed back only in the low frequency component and that at the vicinity of resonance frequency component.
  • the low-pass filter can perform a phase correction for the low frequency region component and a control of low frequency region component.
  • any desired frequency components can be controlled independently, and the resonance frequency component can be controlled while enhancing or suppressing reproduction of the low frequency region. In this way, the output frequency characteristics can be flattened and corrected easily, and a speaker device of superior sound characteristics can be provided.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Circuit For Audible Band Transducer (AREA)

Claims (4)

  1. Dispositif d'enceinte comprenant :
    un soustracteur (6),
    un amplificateur de puissance (13) destiné à recevoir un signal d'entrée par l'intermédiaire du soustracteur (6),
    une unité de haut-parleur (1) destinée à reproduire le signal de sortie de l'amplificateur de puissance,
    un conduit acoustique (2) couplé sur l'avant de l'unité de haut-parleur, destiné à guider des ondes sonores reproduites par l'unité de haut-parleur,
    un microphone (4) destiné à détecter les sorties acoustiques émises à partir de l'unité de haut-parleur,
    un amplificateur de microphone (5) destiné à amplifier le signal de sortie du microphone, et
    un circuit à contre-réaction,
    dans lequel le circuit à contre-réaction est formé en reliant le signal de sortie de l'amplificateur de microphone au soustracteur et en même temps en reliant le signal de sortie de l'amplificateur de microphone au soustracteur par l'intermédiaire d'un filtre passe-haut (7).
  2. Dispositif d'enceinte selon la revendication 1, dans lequel le filtre passe-haut (7) est utilisé en tant que filtre passe-haut secondaire et la fréquence de coupure correspond à la fréquence de résonance du conduit acoustique.
  3. Dispositif d'enceinte comprenant :
    un soustracteur (6),
    un amplificateur de puissance (13) destiné à recevoir un signal d'entrée par l'intermédiaire du soustracteur,
    une unité de haut-parleur (1) destinée à reproduire le signal de sortie de l'amplificateur de puissance,
    un conduit acoustique (2) couplé sur l'avant de l'unité de haut-parleur, destiné à guider les ondes sonores reproduites par l'unité de haut-parleur,
    un microphone (4) destiné à détecter les sorties acoustiques émises à partir de l'unité de haut-parleur,
    un amplificateur de microphone (5) destiné à amplifier le signal de sortie du microphone, et
    un circuit à contre-réaction,
    dans lequel un circuit à contre-réaction est formé en reliant le signal de sortie de l'amplificateur de microphone au soustracteur par l'intermédiaire de filtres passe-haut primaire et secondaire (7, 8), reliés en parallèle.
  4. Dispositif d'enceinte comprenant :
    un soustracteur (6),
    un amplificateur de puissance (13) destiné à recevoir un signal d'entrée par l'intermédiaire du soustracteur,
    une unité de haut-parleur (1) destinée à reproduire le signal de sortie de l'amplificateur de puissance,
    un conduit acoustique (2) couplé sur l'avant de l'unité de haut-parleur, destiné à guider les ondes sonores,
    un microphone (4) destiné à détecter les sorties acoustiques émises à partir de l'unité de haut-parleur,
    un amplificateur de microphone (5) destiné à amplifier le signal de sortie du microphone, et
    un circuit à contre-réaction,
    dans lequel le circuit à contre-réaction est formé en reliant le signal de sortie de l'amplificateur de microphone au soustracteur par l'intermédiaire d'un filtre passe-haut secondaire relié en parallèle à l'un d'un filtre passe-bas primaire et d'un filtre passe-bas secondaire (7, 9).
EP00950015A 2000-08-07 2000-08-07 Dispositif a haut-parleur Expired - Lifetime EP1221824B1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2000/005271 WO2002013573A1 (fr) 1999-05-19 2000-08-07 Dispositif a haut-parleur

Publications (3)

Publication Number Publication Date
EP1221824A1 EP1221824A1 (fr) 2002-07-10
EP1221824A4 EP1221824A4 (fr) 2005-12-07
EP1221824B1 true EP1221824B1 (fr) 2006-10-25

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ID=11736331

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00950015A Expired - Lifetime EP1221824B1 (fr) 2000-08-07 2000-08-07 Dispositif a haut-parleur

Country Status (6)

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EP (1) EP1221824B1 (fr)
CN (1) CN1186965C (fr)
CZ (1) CZ299745B6 (fr)
DE (1) DE60031558T2 (fr)
HK (1) HK1049940B (fr)
WO (1) WO2002013573A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003264888A (ja) * 2002-03-07 2003-09-19 Pioneer Electronic Corp スピーカ制御装置及びスピーカシステム
CN100566140C (zh) * 2003-10-14 2009-12-02 音频专用集成电路公司 麦克风前置放大器
US8243939B2 (en) * 2008-12-30 2012-08-14 Gn Resound A/S Hearing instrument with improved initialisation of parameters of digital feedback suppression circuitry
CN102384821B (zh) * 2011-08-10 2015-07-29 歌尔声学股份有限公司 扬声器模组气密性测试方法、测试工装以及测试系统

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3798374A (en) * 1972-04-03 1974-03-19 Rene Oliveras Sound reproducing system utilizing motional feedback
JPS5990491A (ja) * 1982-11-15 1984-05-24 Matsushita Electric Ind Co Ltd オ−デイオ装置
DE4021787A1 (de) * 1990-07-09 1992-01-16 Telefunken Electronic Gmbh Elektro-akustisches system
JP3132270B2 (ja) * 1993-12-09 2001-02-05 松下電器産業株式会社 音響再生装置
JP3521626B2 (ja) * 1996-07-16 2004-04-19 松下電器産業株式会社 音響再生装置
JP3893730B2 (ja) * 1998-04-15 2007-03-14 松下電器産業株式会社 音響再生装置
CZ292683B6 (cs) * 1998-12-01 2003-11-12 Matsushita Electric Industrial Co., Ltd. Reproduktor

Also Published As

Publication number Publication date
EP1221824A4 (fr) 2005-12-07
CN1186965C (zh) 2005-01-26
CN1377566A (zh) 2002-10-30
DE60031558T2 (de) 2007-06-06
EP1221824A1 (fr) 2002-07-10
WO2002013573A1 (fr) 2002-02-14
DE60031558D1 (de) 2006-12-07
HK1049940A1 (en) 2003-05-30
CZ299745B6 (cs) 2008-11-12
CZ20021168A3 (cs) 2003-02-12
HK1049940B (zh) 2005-06-10

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