EP1665879B1 - Transducteur de force electromecanique - Google Patents

Transducteur de force electromecanique Download PDF

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Publication number
EP1665879B1
EP1665879B1 EP04768390A EP04768390A EP1665879B1 EP 1665879 B1 EP1665879 B1 EP 1665879B1 EP 04768390 A EP04768390 A EP 04768390A EP 04768390 A EP04768390 A EP 04768390A EP 1665879 B1 EP1665879 B1 EP 1665879B1
Authority
EP
European Patent Office
Prior art keywords
transducer
transducer according
resonant elements
stub
damping layer
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 - Fee Related
Application number
EP04768390A
Other languages
German (de)
English (en)
Other versions
EP1665879A1 (fr
Inventor
Mark William Cygnet House Kingfisher Way STARNES
James John Cygnet House Kingfisher Way EAST
Neil Simon Cygnet House Kingfisher Way OWEN
Steven Mark Cygnet House Kingfisher Way HOYLE
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.)
NVF Tech Ltd
Original Assignee
New Transducers 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 New Transducers Ltd filed Critical New Transducers Ltd
Publication of EP1665879A1 publication Critical patent/EP1665879A1/fr
Application granted granted Critical
Publication of EP1665879B1 publication Critical patent/EP1665879B1/fr
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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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
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • 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
    • 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
    • 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

Definitions

  • the invention relates to electromechanical force transducers, actuators, exciters and the like devices and more particularly but not exclusively, to such devices for use in acoustic apparatus, e.g. loudspeakers and microphones.
  • the invention relates particularly, but not exclusively, to electromechanical force transducers of the kind described in International patent application WO01/54450 to the present applicants, and comprising one or more resonant elements or beams having a frequency distribution of modes in the operative frequency range of the transducer.
  • Such transducers are known as "distributed mode actuators" or DMA for short.
  • Another object of the invention is to reduce the first resonant mode frequency of an actuator or transducer, e.g. a DMA transducer.
  • the invention is a transducer of the kind described wherein a low stiffness layer is inserted between, and bonded to the adjacent faces of a plurality of resonant elements.
  • a damping layer to one face of a resonant element or beam gives poor damping performance as the layer stretches with the element as the element face changes dimensions.
  • a flexible reference layer with a high resistance to dimensional change, such as a foil on the other side of the damping layer results in an improvement in damping as the damping layer now shears between the changing element face dimension and the non-stretching foil. If the reference layer can be made to change dimension in opposition to the damped face, the damping effect will be doubled. This is the effect gained by adhering the damping layer between adjacent element faces.
  • FIG. 1 shows a double beam transducer of the kind generally described in WO01/54450.
  • the transducer (1) comprises a first piezoelectric beam (2) on the back of which is mounted a second piezoelectric beam (3) by connecting means in the form of a rigid stub (4) located near to the centre of both beams.
  • Each beam is a bimorph.
  • the measured resistance, R is approx 8 x 10 5 Ns/m3. These figures are the measured 'real' part of the mechanical resistance when in compression, not shear. Shear figures are not available.
  • the density (in isolation from E and R) is expected to be irrelevant, and could vary by a factor of 100 and have little effect.
  • E is important but the shearing that is occurring makes the importance of E difficult to identify.
  • a reduction of E would have little effect as it appears the system stiffness is not being affected too much by the addition of the foam.
  • the R figure is important. Reducing R is expected to effect damping in a linear fashion. We suggest that it is not reduced by more than a factor of say 4. Increasing R is good but cannot be achieved without affecting the other parameters.
  • Figure 2 shows the effect of bonding to one face or to both faces of multibeam transducer.
  • Figure 2a shows the case where the damping layer (7) is only bonded to one beam (2).
  • the damping layer is bonded to both beams, and so is forced into shear by the relative movement of beam (3) in relation to beam (2). It is this shearing which applies damping.
  • Figure 4 shows the simulated effect on acoustic pressure of adding a damping between the faces of a 36mm/34mm beam length DMA transducer. Output at the transducer fundamental is slightly reduced, but a broad increase in output occurs in 3-4kHz region. This is the region of internal cancellation in the transducer. The acoustic pressure response is also smoother.
  • Drop test failure rates are expected to be reduced. At impact most of the energy will be present in the exciter at its fundamental resonance. Since the damping reduces the Q of this resonance, the instantaneous maximum displacement will be reduced, resulting in reduced stress in the beam. This stress reduction is expected to improve drop test reliability. In addition, the build height of the transducer can be reduced by the present invention.
  • the stub used to couple a transducer of the kind described above to its load is stiff in all 3 cartesian axes and rotational stiffness is usually ignored, and is assumed to be high.
  • 0 rotation occurs at the stub for the beam fundamental resonance. If this 0 rotation boundary condition is replicated at the end of a half length beam the fundamental will occur at the same frequency as the full length beam, with half the force.
  • This is the cantilever condition, see Figure 5.
  • Figure 5 is a diagram showing fundamental mode shape of a cantilever beam (that is an extreme offset stub). The displaced shape shows pure bending motion.
  • FIG. 6 is a diagram of a modeshape of a beam coupled to a panel with a soft stub allowing rotation of the beam, the modeshape showing some bending in the beam and some rotational translations.
  • the mode drops to 0 Hz and is a rigid body mode.
  • Reference (9) represents a trapped air layer behind the panel (5), which in the simulation couples to the panel and affects the modal set of resonances in the panel
  • reference (10) represents the body of a cell phone containing a loudspeaker formed by the panel (5) and transducer (1). It will be noted that the deflection of the beam (2) is greatly exaggerated so that it is visible.
  • a solid stub will have the same stiffness in the 3 translational and rotational axes.
  • different stiffnesses in the 6 different axes can be generated. The result is that modes in the different axes occur at different frequencies. If the load impedance is asymmetric, modes involving movement in directions other than normal to the beam surface can couple into the panel, providing increased modal density, see Figure 8.
  • Figure 8a is a graph of simulated effect on acoustic pressure generated by changing stub stiffness.
  • Figure 8b is a perspective view of a panel-form loudspeaker having a panel(5) with an attached transducer mounted on a soft stub (6) of I-beam section and showing the DMA moving in-plane.
  • this mode is not present if the rotational stiffness around the axis (8) normal to the plane of the panel is ignored.
  • the first mode is partly due to rotational stiffness around the axis along the short edge of the beam
  • the second mode is due to the stiffness around the axis normal to the beam.
  • the last rotational axis, around the axis moving along the length of the beam will also generate a mode.
  • the fundamental resonance By changing the fundamental resonance from a purely bending motion in the beam to a partly translatory motion, the stress in the beam is reduced at the fundamental. Since the fundamental resonance will receive the most energy during impact, the beam is more likely to survive without damage as most of the deformation will occur in the stub.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)

Claims (12)

  1. Transducteur à force électromécanique comprenant une pluralité d'éléments résonants, une couche d'amortissement couplée entre les faces contiguës d'au moins deux éléments résonants contigus, et un élément de tronçon sur lequel les éléments résonants sont supportés et pour coupler le transducteur à un site sur lequel est appliquée une force, caractérisé en ce que la couche d'amortissement est choisie de telle sorte que la sortie est augmentée dans la région de fréquence d'annulation interne du transducteur.
  2. Transducteur selon la revendication 1, dans lequel la couche d'amortissement est en plastique alvéolaire.
  3. Transducteur selon la revendication 2, dans lequel le plastique alvéolaire présente des caractéristiques de faible rebond.
  4. Transducteur selon l'une quelconque des revendications 1 à 3, dans lequel la couche d'amortissement se présente sous la forme d'une couche collée sur l'ensemble ou sur une partie substantielle des faces contiguës des éléments résonants.
  5. Transducteur selon l'une quelconque des revendications précédentes, dans lequel les éléments résonants sont en forme de poutre.
  6. Transducteur selon l'une quelconque des revendications précédentes, dans lequel le tronçon présente une rigidité de rotation faible, de telle sorte que la résonance fondamentale du transducteur devient moins dépendante du mouvement de flexion du transducteur et plus rigide dans l'ensemble.
  7. Transducteur selon la revendication 6, dans lequel le tronçon présente des rigidités différentes dans les axes de translation et de rotation, de telle sorte que les modes dans les différents axes se produisent à des fréquences différentes.
  8. Transducteur selon l'une quelconque des revendications précédentes, dans lequel les paramètres de l'élément résonant sont choisis pour accroître la répartition des modes dans l'élément, dans la plage de fréquences opérantes, avec les paramètres qui sont choisis à partir du groupe consistant en rapport d'aspect, isotropie de rigidité de flexion, isotropie d'épaisseur et géométrie.
  9. Transducteur selon l'une quelconque des revendications précédentes, dans lequel au moins l'un des éléments résonants est actif, par exemple en piézomatière.
  10. Transducteur selon l'une quelconque des revendications précédentes, dans lequel l'élément à faible rigidité est couplé entre sensiblement l'ensemble des faces contiguës.
  11. Transducteur de force électromécanique selon l'une quelconque des revendications précédentes, dans lequel les éléments résonants ont une répartition de fréquence des modes dans la plage de fréquences opérantes du transducteur.
  12. Haut-parleur comprenant un transducteur selon l'une quelconque des revendications précédentes, et un élément de radiation acoustique en forme de panneau à ondes fléchissantes sur lequel est couplé le transducteur.
EP04768390A 2003-09-11 2004-09-09 Transducteur de force electromecanique Expired - Fee Related EP1665879B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB0321292.5A GB0321292D0 (en) 2003-09-11 2003-09-11 Transducer
PCT/GB2004/003843 WO2005027571A1 (fr) 2003-09-11 2004-09-09 Trasnducteur de force electromecanique

Publications (2)

Publication Number Publication Date
EP1665879A1 EP1665879A1 (fr) 2006-06-07
EP1665879B1 true EP1665879B1 (fr) 2007-02-28

Family

ID=29226902

Family Applications (1)

Application Number Title Priority Date Filing Date
EP04768390A Expired - Fee Related EP1665879B1 (fr) 2003-09-11 2004-09-09 Transducteur de force electromecanique

Country Status (9)

Country Link
EP (1) EP1665879B1 (fr)
JP (1) JP5128127B2 (fr)
KR (1) KR101176671B1 (fr)
CN (1) CN1839659B (fr)
DE (1) DE602004005060T2 (fr)
GB (1) GB0321292D0 (fr)
HK (1) HK1094748A1 (fr)
TW (1) TWI343755B (fr)
WO (1) WO2005027571A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11297416B2 (en) 2020-01-17 2022-04-05 Shenzhen Shokz Co., Ltd. Microphone and electronic device having the same
US11843923B2 (en) 2020-01-17 2023-12-12 Shenzhen Shokz Co., Ltd. Microphone and electronic device having the same

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB0414652D0 (en) * 2004-06-30 2004-08-04 New Transducers Ltd Transducer or actuator
JP6304168B2 (ja) * 2015-08-06 2018-04-04 Tdk株式会社 圧電モジュール
US10356523B2 (en) * 2017-12-13 2019-07-16 Nvf Tech Ltd Distributed mode loudspeaker actuator including patterned electrodes
US10681471B2 (en) 2017-12-22 2020-06-09 Google Llc Two-dimensional distributed mode actuator
US10631072B2 (en) 2018-06-25 2020-04-21 Google Llc Actuator for distributed mode loudspeaker with extended damper and systems including the same
JP7148481B2 (ja) 2019-12-04 2022-10-05 エルジー ディスプレイ カンパニー リミテッド 表示装置
WO2021142913A1 (fr) * 2020-01-17 2021-07-22 Shenzhen Voxtech Co., Ltd. Microphone et dispositif électronique le comprenant

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3440363A (en) * 1965-11-26 1969-04-22 Bell Telephone Labor Inc Shock-resistant microphone
JPS63110900A (ja) * 1986-10-28 1988-05-16 Murata Mfg Co Ltd 振動アラ−ム装置
US4969197A (en) * 1988-06-10 1990-11-06 Murata Manufacturing Piezoelectric speaker
US5805726A (en) * 1995-08-11 1998-09-08 Industrial Technology Research Institute Piezoelectric full-range loudspeaker
JP2000201398A (ja) 1998-06-30 2000-07-18 Shinsei Kk スピ―カ
IL140038A0 (en) * 1998-07-03 2002-02-10 New Tranducers Ltd Resonant panel-form loudspeaker
TW511391B (en) * 2000-01-24 2002-11-21 New Transducers Ltd Transducer
US7151837B2 (en) * 2000-01-27 2006-12-19 New Transducers Limited Loudspeaker
JP2004087662A (ja) * 2002-08-26 2004-03-18 Fdk Corp 圧電素子

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11297416B2 (en) 2020-01-17 2022-04-05 Shenzhen Shokz Co., Ltd. Microphone and electronic device having the same
US11671746B2 (en) 2020-01-17 2023-06-06 Shenzhen Shokz Co., Ltd. Microphone and electronic device having the same
US11843923B2 (en) 2020-01-17 2023-12-12 Shenzhen Shokz Co., Ltd. Microphone and electronic device having the same

Also Published As

Publication number Publication date
EP1665879A1 (fr) 2006-06-07
HK1094748A1 (en) 2007-04-04
KR101176671B1 (ko) 2012-08-23
TWI343755B (en) 2011-06-11
WO2005027571A1 (fr) 2005-03-24
JP2007505539A (ja) 2007-03-08
CN1839659B (zh) 2011-05-04
DE602004005060D1 (de) 2007-04-12
KR20060119972A (ko) 2006-11-24
GB0321292D0 (en) 2003-10-15
DE602004005060T2 (de) 2007-11-22
TW200522760A (en) 2005-07-01
JP5128127B2 (ja) 2013-01-23
CN1839659A (zh) 2006-09-27

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