WO2001003467A2 - Dispositif acoustique - Google Patents

Dispositif acoustique Download PDF

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Publication number
WO2001003467A2
WO2001003467A2 PCT/GB2000/002353 GB0002353W WO0103467A2 WO 2001003467 A2 WO2001003467 A2 WO 2001003467A2 GB 0002353 W GB0002353 W GB 0002353W WO 0103467 A2 WO0103467 A2 WO 0103467A2
Authority
WO
WIPO (PCT)
Prior art keywords
panel
mass
acoustic device
whole
frequency
Prior art date
Application number
PCT/GB2000/002353
Other languages
English (en)
Other versions
WO2001003467A3 (fr
Inventor
Christien Ellis
Original Assignee
New Transducers Limited
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 New Transducers Limited filed Critical New Transducers Limited
Priority to JP2001508196A priority Critical patent/JP2003503990A/ja
Priority to AU55475/00A priority patent/AU5547500A/en
Priority to NZ515327A priority patent/NZ515327A/en
Priority to EP00940555A priority patent/EP1192839A2/fr
Publication of WO2001003467A2 publication Critical patent/WO2001003467A2/fr
Publication of WO2001003467A3 publication Critical patent/WO2001003467A3/fr
Priority to HK02102795.1A priority patent/HK1041400A1/zh

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/26—Damping by means acting directly on free portion of diaphragm or cone
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
    • H04R7/04—Plane diaphragms
    • H04R7/045—Plane diaphragms using the distributed mode principle, i.e. whereby the acoustic radiation is emanated from uniformly distributed free bending wave vibration induced in a stiff panel and not from pistonic motion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
    • H04R7/04—Plane diaphragms
    • H04R7/06—Plane diaphragms comprising a plurality of sections or layers

Definitions

  • This invention relates to an acoustic device, in particular to an acoustic device using distributed resonant bending wave modes in a plate.
  • a bending wave transducer excites resonant modes distributed in a plate, and creates sound thereby.
  • Such loudspeakers can suffer adverse effects from whole body modes, which are lower frequency vibrations of the plate moving as a whole.
  • An example of such a mode can occur when a panel is placed in a shallow enclosure. If the outer edge of the panel is held in place, the centre of the panel can vibrate backwards and forwards; the frequency of this vibration will be affected by on the cushion of air trapped by the enclosure and can occur at frequencies around lOOOHz, which are relatively critical for sound production.
  • Another example of a whole body mode may be the vibration mode associated with the panel vibrating on its resilient suspension.
  • the discrete resonance caused by whole body modes may cause peaks in the frequency response. This is disadvantageous, so distributed mode devices would be normally designed so that they operate outside the frequency range of such modes. However, this is not always possible and so there is a need to reduce the effect of such modes on the performance of a distributed mode acoustic device.
  • an acoustic device comprising a panel capable of supporting bending waves, and having a whole-body resonance at a whole-body resonance frequency, a transducer for exciting distributed bending waves modes in the panel to cause the panel to emit sound, and a mass fixed to the panel at a location spaced from the transducer to control the whole-body resonance.
  • the mass is fixed to the panel by a coupling which decouples the mass from the panel at higher frequencies.
  • the coupling may be a compliant coupling, such as a spring or compliant metal sheet to substantially decouple the mass from resonant bending waves m the panel at frequencies much higher than the whole-body resonance frequency.
  • the compliance may also result from the elasticity of the skin and core of the panel.
  • compliant adhesive may form the compliant coupling fixing the mass to the panel. At frequencies much higher than the resonance frequency of the mass on the compliant coupling the mass may be substantially decoupled from the panel.
  • the compliance of the compliant coupling may be selected so that the resonance frequency of the mass on the compliant coupling is suitable for desired acoustic results; the resonance frequency of mass and compliant coupling may be above the whole body mode frequency.
  • the area of the panel, B the bending stiffness, and ⁇ the areal density m Kg/m 2 .
  • this fundamental frequency is arranged to be suitably low, so that the panel has sufficiently distributed modes m the operating frequency range.
  • the panel may need to be stiffer than may be optimal, i.e. the panel may need to be "over-stiff", with a value of bending stiffness B higher than would normally be chosen to reduce the fundamental frequency. In such cases reduction of the effects of the whole body mode may be particularly useful.
  • the mass fixed to the panel may be m proportion to the effective moving mass of the panel, i.e. between 10% or 20% of the effective moving mass and 200% or 300% of that mass.
  • Lightweight multimedia speakers may have, for example, an effective moving panel mass of say 8 gram; for such an application a mass between 1 and 10 gram may need to be fixed to the panel.
  • the mass must be varied depending on a number of parameters, such as the mass of the system, the relevant spring constants and indeed the whole mechanical circuit of the assembly.
  • the mass is preferably fixed to the panel m a near- central location. This choice is not to do with modal drive but takes into account the consideration that the mass should be located relatively near to the centre of mass of the panel so that the added mass can control whole body modes.
  • the preferred location may be one which couples more weakly to the lower resonant modes other than the whole body mode. The location may be found by systematic experiment or computed analysis of the mechanical circuit of the panel.
  • An enclosure may be provided behind the panel; the enclosure may be open or closed, m particular the enclosure may conveniently be shallow.
  • the enclosure may act as a baffle.
  • the invention also relates to a method of making an acoustic device, following the steps of providing a panel capable of supporting bending waves, and a transducer on the panel, exciting distributed bending waves modes in the panel using the transducer to cause the panel to emit sound, determining the frequency response of the panel, identifying a whole-body resonance at a whole-body resonance frequency, and applying a mass to the panel at a particular location to control the whole-body resonance.
  • the frequency response of the panel may be determined by using systematic analysis or mathematical calculation.
  • one acoustic device may simply be replicated by using a like panel, with a like transducer and a like mass mounted thereupon in a like manner, without needing to determine the whole-body resonance frequency for every unit made.
  • the step of fixing the mass to the panel may be carried out using a compliant coupling.
  • Figure 2 shows a view of a loudspeaker according to the invention
  • Figure 3 shows the frequency response of the loudspeaker without the additional mass
  • Figure 4 shows the frequency response of the loudspeaker with the additional mass.
  • a panel 11 is mounted on a frame 13.
  • the panel 11 has a thickness of 0.35mm, a length of 206.5mm, a width of 147mm, a mechanical impedance of 6.22Nm, a fundamental frequency of 203Hz and a coincidence frequency of 7.8kHz.
  • the frame 13 is a rear structure that defines and encloses a shallow enclosure 15 of volume 0.6 litre.
  • An optimised panel of the same material might have thickness 0.35mm, mechanical impedance of 6.22 Nm, length 333mm, width 284mm, fundamental frequency 78Hz and coincidence frequency of 7.8KHz.
  • the fundamental frequency of the panel according to the invention is much higher, 203Hz against 78Hz.
  • the panel 11 is resiliently supported on the frame 13 by 4mm thick double sided foam tape 17 adhered around the perimeter of the panel 11, to provide a relatively compliant support.
  • Other edge supports such as a clamped support or a simply supported support may be provided if useful .
  • two exciters 19 are mounted in positions taught to be advantageous by WO97/09842.
  • the exciters are 25mm exciters wired m series to give a d.c. resistance of 9 ⁇ ; a parallel connection may also be possible .
  • Figure 3 shows the measurement of the sound pressure level of the panel measured at lm as a function of frequency. A substantial peak around 500Hz-lKHz is believed to show the effect of the whole body mode caused by the panel 11 vibrating on a cushion of air m the enclosure 15, the whole body mode being controlled by the compliance of air m the enclosure.
  • the mass was fixed with a piece of thin compliant plastic 23 with adhesive on each side, similar to conventional sticky tape.
  • the mass was 3.1g.
  • the peak is substantially controlled without causing significant change at higher frequencies .
  • the mass 21 selectively controls the output, sufficiently reduces the sensitivity and lowers the resonant frequency substantially at the whole body mode frequency.
  • the mass 21 becomes increasingly decoupled from the panel 11 at higher frequencies as the panel becomes more densely modal .
  • the position of the mass clearly is important for fine-tuning the control.
  • the position, mass and compliance of the mounting of the mass on the panel may be adjusted to control the response of the system, for example to provide a more even acoustic response as a function of frequency.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
  • Details Of Audible-Bandwidth Transducers (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)

Abstract

Un dispositif acoustique comprend un panneau (11) qui est capable de supporter des modes d'ondes de flexion à résonance et des transducteurs (19) montés sur ledit panneau. Parfois la réponse acoustique du panneau et des transducteurs peut comporter un pic de résonance du corps tout entier à une fréquence particulière. Pour réguler ce phénomène, une masse (21) peut être ajoutée au panneau telle que par exemple un couplage souple (23).
PCT/GB2000/002353 1999-07-02 2000-06-30 Dispositif acoustique WO2001003467A2 (fr)

Priority Applications (5)

Application Number Priority Date Filing Date Title
JP2001508196A JP2003503990A (ja) 1999-07-02 2000-06-30 音響装置
AU55475/00A AU5547500A (en) 1999-07-02 2000-06-30 Acoustic device
NZ515327A NZ515327A (en) 1999-07-02 2000-06-30 Acoustic device with a panel having a mass fixed thereto to control whole-body resonance
EP00940555A EP1192839A2 (fr) 1999-07-02 2000-06-30 Dispositif acoustique
HK02102795.1A HK1041400A1 (zh) 1999-07-02 2002-04-12 彎曲波聲學裝置

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9915361.1A GB9915361D0 (en) 1999-07-02 1999-07-02 Acoustic device
GB9915361.1 1999-07-02

Publications (2)

Publication Number Publication Date
WO2001003467A2 true WO2001003467A2 (fr) 2001-01-11
WO2001003467A3 WO2001003467A3 (fr) 2001-03-22

Family

ID=10856397

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2000/002353 WO2001003467A2 (fr) 1999-07-02 2000-06-30 Dispositif acoustique

Country Status (9)

Country Link
EP (1) EP1192839A2 (fr)
JP (1) JP2003503990A (fr)
CN (1) CN1351813A (fr)
AU (1) AU5547500A (fr)
GB (1) GB9915361D0 (fr)
HK (1) HK1041400A1 (fr)
NZ (1) NZ515327A (fr)
TW (1) TW488183B (fr)
WO (1) WO2001003467A2 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005101899A2 (fr) * 2004-04-16 2005-10-27 New Transducers Limited Dispositif acoustique et procede de fabrication de celui-ci
US6988339B2 (en) 2002-02-06 2006-01-24 Andersen Corporation Specialty media window
US7426804B2 (en) 2002-02-06 2008-09-23 Andersen Corporation Specialty display window
GB2489700A (en) * 2011-04-04 2012-10-10 Canon Kk Controlling the vibration modes of a vibrating support
GB2551723B (en) * 2016-06-27 2018-11-28 Amina Tech Limited Speaker Panel
GB2564061A (en) * 2016-06-27 2019-01-02 Amina Tech Limited Speaker panel
GB2568282A (en) * 2017-11-10 2019-05-15 Amina Tech Limited Flat panel loudspeaker

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4654554A (en) * 1984-09-05 1987-03-31 Sawafuji Dynameca Co., Ltd. Piezoelectric vibrating elements and piezoelectric electroacoustic transducers
US5376853A (en) * 1991-09-28 1994-12-27 Star Micronics Co., Ltd. Electroacoustic transducer
WO1997009842A2 (fr) * 1995-09-02 1997-03-13 New Transducers Limited Dispositif acoustique
WO1998052381A2 (fr) * 1997-05-15 1998-11-19 New Transducers Limited Haut-parleur a panneaux
EP0881856A1 (fr) * 1996-10-24 1998-12-02 Shinsei Corporation Vibrateur acoustique piezo-electrique et haut-parleur utilisant ledit vibrateur acoustique piezo-electrique correspondant

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4654554A (en) * 1984-09-05 1987-03-31 Sawafuji Dynameca Co., Ltd. Piezoelectric vibrating elements and piezoelectric electroacoustic transducers
US5376853A (en) * 1991-09-28 1994-12-27 Star Micronics Co., Ltd. Electroacoustic transducer
WO1997009842A2 (fr) * 1995-09-02 1997-03-13 New Transducers Limited Dispositif acoustique
EP0881856A1 (fr) * 1996-10-24 1998-12-02 Shinsei Corporation Vibrateur acoustique piezo-electrique et haut-parleur utilisant ledit vibrateur acoustique piezo-electrique correspondant
WO1998052381A2 (fr) * 1997-05-15 1998-11-19 New Transducers Limited Haut-parleur a panneaux

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6988339B2 (en) 2002-02-06 2006-01-24 Andersen Corporation Specialty media window
US7426804B2 (en) 2002-02-06 2008-09-23 Andersen Corporation Specialty display window
WO2005101899A2 (fr) * 2004-04-16 2005-10-27 New Transducers Limited Dispositif acoustique et procede de fabrication de celui-ci
WO2005101899A3 (fr) * 2004-04-16 2006-04-06 New Transducers Ltd Dispositif acoustique et procede de fabrication de celui-ci
US7916878B2 (en) 2004-04-16 2011-03-29 New Transducers Limited Acoustic device and method of making acoustic device
GB2489700B (en) * 2011-04-04 2013-09-18 Canon Kk Method and device for controlling the vibration modes of a vibrating support
GB2489700A (en) * 2011-04-04 2012-10-10 Canon Kk Controlling the vibration modes of a vibrating support
GB2551723B (en) * 2016-06-27 2018-11-28 Amina Tech Limited Speaker Panel
GB2564061A (en) * 2016-06-27 2019-01-02 Amina Tech Limited Speaker panel
GB2564061B (en) * 2016-06-27 2020-12-16 Amina Tech Limited Speaker panel
US10893344B2 (en) 2016-06-27 2021-01-12 Amina Technologies Limited Speaker panel
US11582540B2 (en) 2016-06-27 2023-02-14 Amina Technologies Limited Speaker panel
GB2568282A (en) * 2017-11-10 2019-05-15 Amina Tech Limited Flat panel loudspeaker
GB2568282B (en) * 2017-11-10 2020-11-25 Amina Tech Limited Flat panel loudspeaker
US11388518B2 (en) 2017-11-10 2022-07-12 Amina Technologies Limited Flat panel loudspeaker

Also Published As

Publication number Publication date
HK1041400A1 (zh) 2002-07-05
CN1351813A (zh) 2002-05-29
TW488183B (en) 2002-05-21
WO2001003467A3 (fr) 2001-03-22
EP1192839A2 (fr) 2002-04-03
GB9915361D0 (en) 1999-09-01
JP2003503990A (ja) 2003-01-28
NZ515327A (en) 2002-05-31
AU5547500A (en) 2001-01-22

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