EP0035426B1 - Transducteur électromécanique à suspension active, et son procédé de fabrication - Google Patents

Transducteur électromécanique à suspension active, et son procédé de fabrication Download PDF

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Publication number
EP0035426B1
EP0035426B1 EP81400241A EP81400241A EP0035426B1 EP 0035426 B1 EP0035426 B1 EP 0035426B1 EP 81400241 A EP81400241 A EP 81400241A EP 81400241 A EP81400241 A EP 81400241A EP 0035426 B1 EP0035426 B1 EP 0035426B1
Authority
EP
European Patent Office
Prior art keywords
active
film
active suspension
transducer according
spherical
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
Application number
EP81400241A
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German (de)
English (en)
French (fr)
Other versions
EP0035426A1 (fr
Inventor
Pierre Ravinet
François Micheron
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.)
Thales SA
Original Assignee
Thomson CSF SA
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 Thomson CSF SA filed Critical Thomson CSF SA
Priority to AT81400241T priority Critical patent/ATE6015T1/de
Publication of EP0035426A1 publication Critical patent/EP0035426A1/fr
Application granted granted Critical
Publication of EP0035426B1 publication Critical patent/EP0035426B1/fr
Expired 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
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H04R17/005—Piezoelectric transducers; Electrostrictive transducers using a piezoelectric polymer

Definitions

  • the present invention relates to electromechanical transducers comprising a polymer element in which an electrical anisotropy has been induced in the form of an excess of electrical charge or of a dipolar orientation of the macromolecular chains.
  • the invention relates more particularly to transducers such as loudspeaker, microphone, hydrophone, ultrasound probe, etc., in which the active structure consists of at least one polymer film having undergone shaping of the non-developable type.
  • the active structure consists of at least one polymer film having undergone shaping of the non-developable type.
  • Such a structure is self-supporting and requires no other support than a peripheral attachment.
  • two modes of deformation are encountered depending on whether the lamellar structure is homogeneous or heterogeneous. The simplest example is that of a single film carrying metallizations on its two flat faces.
  • the other deformations depend on the stretch that the film underwent during forming.
  • the stretch is unidirectional, the deformations are greater according to the direction of stretch.
  • the deformations are also isotropic.
  • the subject of the invention is an electromagnetic transducer with a self-supporting radiating structure comprising at least one active element consisting of at least one film of polymer material, the faces of which include electrodes, this radiating structure being fixed at its periphery to a support means, this radiating structure comprising at least one active suspension extending between said support means and a central element of this radiating structure constituted by a film conforming to the shape of a spherical surface portion, characterized in that said active suspension substantially matches the shape of a trunk of a pyramid or of a cone, said shape having as its director the periphery of said spherical surface portion and for generating lines parallel to the marginal radii of said spherical surface portion, said active suspension being made of a film surrounded by electrodes.
  • the invention also relates to the method of manufacturing the electromechanical transducer mentioned above.
  • the subject of the invention is also an electromechanical transducer with a self-supporting radiating structure comprising at least one active element constituted by at least one film of polymer material, the faces of which include electrodes, this radiating structure being fixed at its periphery to a support means.
  • this radiating structure comprising at least one active suspension extending between said support means and a central element of this radiating structure constituted by a film conforming to the shape of a spherical surface portion, characterized in that said active suspension matches substantially the shape of a trunk of a pyramid or cone, said shape having for its director the periphery of said spherical surface portion and for generating lines perpendicular to the marginal radii of said spherical surface portion, said active suspension being made of a bimorph structure surrounded by electrodes.
  • the electromechanical transducers considered are electrically excited via a system of electrodes and emit via a radiating surface coupled to media propagating longitudinal vibrational waves.
  • these linear transducers also work in reverse.
  • the transducer effects induced in polar polymer films are piezoelectric effects.
  • the deformation of an active element can essentially produce an isotropic or anisotropic surface variation with corresponding change in curvature if necessary (case of the homogeneous structure) or, on the contrary, produce a cumulative sag accompanied by transverse displacement (case of the bimorph structure).
  • the polymeric materials which can be used are polar homopolymers such as PVF z (polyvinylidene fluoride) and PVF (polyvinyl fluoride) or else polar copolymers such as PVF z / PTFE.
  • Non-polar polymeric materials can also be used with an excess of electric charge obtained by implantation, by thermal electrification or by corona discharge.
  • Many synthetic organic dielectrics can be used, such as polyurethane (PU) and polyethylene tetrafluoride (PTFE).
  • This transducer comprises an annular support 2 of axis of revolution XX to which is fixed a polymer film 1, the shaping of which has been such that it appears in the center in the form of a spherical cap with a half angle of opening a having its center C on the axis XX.
  • this film has a frustoconical shape with rectilinear generatrices according to the marginal radii of the spherical cap.
  • the frustoconical part of the radiating structure of FIG. 1 constitutes an active suspension. To this end, it is coated on its two faces with electrodes 3 and 4.
  • the radiating structure of FIG. 1 can be produced by thermoforming a thin film of polyvinylidene fluoride having a thickness of the order of 25 l im.
  • the electrodes 3 and 4 are obtained by thermal evaporation under aluminum vacuum up to a thickness of 1500 ⁇ .
  • the part of the film 1 forming the cap was stretched biaxially while the frustoconical part was stretched unidirectionally according to the rays shown in dotted lines.
  • an electric polarization treatment creating between the electrodes 3 and 4 a transverse electric field of high intensity (1 MV / cm)
  • the peripheral suspension of the central dome is activated.
  • the active peripheral suspension behaves like a piezoelectric transducer.
  • the alternating elongations and contractions of the conical wall of the active peripheral suspension are oriented by construction as shown by the double arrow 8.
  • the passive spherical cap is stressed along its marginal radii, which causes it to move parallel to the axis XX.
  • the dotted line 6 represents the low position of the radiating structure and the dashed line 7 represents the high position.
  • the spherical cap sweeps a relatively large volume, because the transducer effect is concentrated in the conical suspension with maximum sensitivity for deformations along the meridians.
  • each protuberance 11 seals the radiating structure, in order to counteract the acoustic short-circuiting between the radiating faces of the vibrating piston.
  • it offers no circumferential stiffness capable of preventing the active sectors 12 from following the translational movement of the central dome.
  • the central dome plays a passive role and it can undergo a curvature, it can be made in a material other than the active frustoconical suspension or with another wall thickness.
  • the active peripheral suspension is here of the bimorph type. This results in a different mounting, since the peripheral suspension is embedded in the support 2 while, in FIG. 1, it could pivot around the support thanks to a hinge effect on the outside fold. Another difference lies in the fact that the connection between the spherical cap and the active frustoconical suspension does not include the 90 ° bend which is visible in FIG. 1.
  • the active suspension in fig. 2 is provided with a film 10 of frustoconical shape which adheres perfectly to the frustoconical part of the film 1.
  • a film 10 of frustoconical shape which adheres perfectly to the frustoconical part of the film 1.
  • the surface deformations of the film 1 differ from that of the film 10
  • Along the line connecting with the spherical cap there is a displacement oriented along the marginal radii thereof. This movement is illustrated by the curved double arrow 9 and, if we refer to FIG. 1, it can be seen that it differs little from the displacement symbolized by the double arrow 8.
  • the two types of active suspensions are quite comparable. It can be noted that the mechanical compliance of the active suspension in fig. 1 is greater than that of the suspension in FIG. 2; it follows that the edge of the spherical cap of FIG. 2 moves more specifies according to the marginal radii shown in dotted lines.
  • Figs. 1 and 2 have less directional radiation patterns than those of an active cap resting directly on the fixing ring 2.
  • Fig. 5 represents a spherical surface 13 with, at point H, a system of axes 1,2,3.
  • Axis 3 is oriented along a radius, axis 1 is tangent to a parallel and axis 2 is tangent to a meridian.
  • Fig. 6 is a view in meridian section of a spherical transducer having omnidirectional radiation by spherical waves of center of phase C; such a transducer is disclosed in DE-A 2417962.
  • the polymer film 16 has a wall thickness e and carries on its outer and inner faces of the metallizations 14 and 15. An orifice is required for the handshake on metallization 15.
  • Such a transducer is very delicate to manufacture and has the drawback of enclosing a small volume of air which greatly increases the rigidity of the radiating structure.
  • a vibrating piston constituted by a spherical surface portion could emit waves of center of phase C.
  • Such a piston is shown in fig. 7. It is a spherical cap 13 with radius R and half-opening angle a.
  • the ideal deformed state is an expanded cap 17 of radius R + AR; all the points have undergone a radial displacement AR.
  • Fig. 8 shows that the fixing of this spherical cap in an annular rigid support 18, as described in the document D E-A No. 2417962, does not at all reproduce the purely radial displacement of FIG. 7.
  • the center of curvature goes from C to C 'and the radius of curvature goes from the value R to the value R'.
  • the invention provides for its connection by means of an active peripheral suspension which reproduces the boundary conditions of the pulsating sphere from which it is extracted and which ensures the immobility of center C.
  • the active suspension vibrates without radiating for its own account.
  • the radiation pattern is only determined by the operation of the central dome in a pulsating cap.
  • FIG. 10 is a plan view of the metallizations 3 and 18 carried by the upper face of the polymer film 1. These metallizations 18 and 3 are independent of one another to allow the electrical polarizations of the spherical cap and of the active suspension be made in a sign such that the application of the excitation voltages is facilitated. After polarization, the electrodes 18 and 3 can be interconnected if the same excitation voltage is applied to the spherical cap and to the peripheral suspension.
  • the electrodes 19 and 4 are arranged in the same way as the electrodes 18 and 3. It is possible, without drawback, to completely metallize one of the faces of the film 1.
  • the use of an active spherical cap in the configuration of FIG. 2 is also possible. However, it should be noted that the active suspension in fig. 2 provides part of the overall radiation.
  • the complex ratio of excitation voltages of the active spherical cap and the active peripheral suspension may not be constant. These two elements can be excited with voltages whose amplitudes and phases no longer ensure the neutrality of the deformations on either side of the connection line except for the high frequencies of the acoustic spectrum. Indeed, at low frequencies, a piston not having the characteristics of a portion of a pulsating sphere can radiate in a non-directive manner. It is therefore possible to vary the ratio of the excitation voltages with the frequency for the sole purpose of obtaining an optimized frequency response curve in a predetermined radiation angle.
  • the manufacture of a structure as shown in FIG. 9 can be done by making the spherical cap and the frustoconical suspension separately.
  • Figs. 11 to 13 illustrate a manufacturing process making it possible to obtain these two active elements from a flat film of polyvinylidene fluoride.
  • the PVF 2 film 24 is pinched in two peripheral jaws 20 and 23; it is also pinched between two jaws 21 and 22, as shown in fig. 11.
  • the invention is in no way limited to a portion of passive or active spherical surface in the form of a spherical cap.
  • the main radiating element of which consists of a spherical zone connected to two active and frustoconical peripheral suspensions.
  • the transducer comprises a rigid support 2 on which the two frustoconical peripheral suspensions are supported.
  • the lower suspension is provided with electrodes 27 and 28, while the upper suspension has received electrodes 29 and 30.
  • the radiating spherical zone is provided with electrodes 18 and 19. All the electrodes are connected to an excitation generator 5 which fulfills the operating condition in a pulsating sphere.
  • the spherical zone can be purely passive and it is possible to add to it a passive or active upper spherical cap of the same curvature which is connected to the upper active suspension surrounded by the electrodes 29 and 30.
  • the manufacturing of a spherical zone can be done by blowing in a mold in two parts of a tube of polymeric material.
  • the frusto-conical suspensions can be added or produced by another stretching operation of the tube of polymer material.
  • the active frustoconical suspension can be flared towards the support or, on the contrary, converges towards the support. This duality of form also applies to figs. 1 and 9.
  • the active suspensions in fig. 14 can be replaced by bimorphic suspensions, as illustrated in fig. 2. The latter participate in the overall radiation of the radiating structure.
  • One of the suspensions can also be made from bimorph film and the other from single film.
  • spherical surface portion of material of greater compliance than the active suspensions.
  • polyurethane will be used as a passive element and polyvinylidene fluoride as an active suspension element.
  • active suspensions described are produced from polymeric films, active suspensions which use electrodynamic or magnetic forces should not be excluded. Nor should we dismiss active suspension structures with undulations which can reduce the size of bimorph structures while cumulating the effects of deflection over an effective length greater than their folded length.
  • the invention is in no way limited to radiating surfaces having the symmetry of revolution.
  • the active suspension can take the form of a truncated cone or pyramid with a non-circular director connecting with a portion of spherical surface.
  • the active suspension must reproduce the movements of a pulsating sphere, it is advantageous to make the top of the truncated cone or pyramid coincide with the center of this sphere.
  • the invention is also not limited to the spherical surface portions used in the piston. It also includes, as an alternative embodiment, pistons of generally spherical shape, but having a relief of small amplitude intended to increase mechanical compliance.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Primary Cells (AREA)
  • Cell Separators (AREA)
EP81400241A 1980-03-04 1981-02-17 Transducteur électromécanique à suspension active, et son procédé de fabrication Expired EP0035426B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81400241T ATE6015T1 (de) 1980-03-04 1981-02-17 Elektromechanischer wandler mit aktiver aufhaengung und verfahren zu seiner herstellung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8004838 1980-03-04
FR8004838A FR2477822A1 (fr) 1980-03-04 1980-03-04 Transducteur electromecanique a suspension active et son procede de fabrication

Publications (2)

Publication Number Publication Date
EP0035426A1 EP0035426A1 (fr) 1981-09-09
EP0035426B1 true EP0035426B1 (fr) 1984-01-25

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Family Applications (1)

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EP81400241A Expired EP0035426B1 (fr) 1980-03-04 1981-02-17 Transducteur électromécanique à suspension active, et son procédé de fabrication

Country Status (8)

Country Link
US (2) US4401911A (enrdf_load_stackoverflow)
EP (1) EP0035426B1 (enrdf_load_stackoverflow)
JP (1) JPS56136098A (enrdf_load_stackoverflow)
AT (1) ATE6015T1 (enrdf_load_stackoverflow)
CA (1) CA1173553A (enrdf_load_stackoverflow)
DE (1) DE3161995D1 (enrdf_load_stackoverflow)
FR (1) FR2477822A1 (enrdf_load_stackoverflow)
GB (1) GB2070891B (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3818931A1 (de) * 1988-06-03 1989-12-14 Electronic Werke Deutschland Lautsprecherbox

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JP5479659B2 (ja) * 2000-02-23 2014-04-23 エスアールアイ インターナショナル 生体によって動力を供給される電気活性ポリマジェネレータ
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WO2003079409A2 (en) * 2002-03-15 2003-09-25 United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Electro-active device using radial electric field piezo-diaphragm for control of fluid movement
US6919669B2 (en) * 2002-03-15 2005-07-19 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Electro-active device using radial electric field piezo-diaphragm for sonic applications
DK1512215T3 (da) * 2002-03-18 2011-12-05 Stanford Res Inst Int Elektroaktive polymeranordning til bevægelse af fluid
DK1751843T3 (da) * 2003-08-29 2012-12-17 Stanford Res Inst Int Forbelastning af elektroaktive polymer
KR100781329B1 (ko) * 2005-07-08 2007-11-30 드림 소닉 테크놀러지 리미티드 필름 스피커
US7952261B2 (en) 2007-06-29 2011-05-31 Bayer Materialscience Ag Electroactive polymer transducers for sensory feedback applications
EP2239793A1 (de) 2009-04-11 2010-10-13 Bayer MaterialScience AG Elektrisch schaltbarer Polymerfilmaufbau und dessen Verwendung
US8712559B2 (en) * 2010-02-10 2014-04-29 The Board Of Trustees Of The University Of Illionois Adaptive control for uncertain nonlinear multi-input multi-output systems
EP2681748B1 (en) 2011-03-01 2016-06-08 Parker-Hannifin Corp Automated manufacturing processes for producing deformable polymer devices and films
KR20140019801A (ko) 2011-03-22 2014-02-17 바이엘 인텔렉쳐 프로퍼티 게엠베하 전기활성 중합체 작동기 렌티큘라 시스템
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FR2303436A1 (fr) * 1975-03-03 1976-10-01 Philips Nv Dispositif pour convertir des oscillations electriques en vibrations acoustiques et inversement, muni d'une membrane comportant au moins une couche formee par un polymere piezo-electrique
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3818931A1 (de) * 1988-06-03 1989-12-14 Electronic Werke Deutschland Lautsprecherbox

Also Published As

Publication number Publication date
CA1173553A (en) 1984-08-28
US4401911A (en) 1983-08-30
JPS56136098A (en) 1981-10-23
ATE6015T1 (de) 1984-02-15
US4518555A (en) 1985-05-21
DE3161995D1 (en) 1984-03-01
GB2070891A (en) 1981-09-09
FR2477822A1 (fr) 1981-09-11
GB2070891B (en) 1984-06-20
EP0035426A1 (fr) 1981-09-09
FR2477822B1 (enrdf_load_stackoverflow) 1982-10-01

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