WO2000057496A1 - Transducteur electroacoustique a bande large - Google Patents

Transducteur electroacoustique a bande large Download PDF

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Publication number
WO2000057496A1
WO2000057496A1 PCT/US2000/007663 US0007663W WO0057496A1 WO 2000057496 A1 WO2000057496 A1 WO 2000057496A1 US 0007663 W US0007663 W US 0007663W WO 0057496 A1 WO0057496 A1 WO 0057496A1
Authority
WO
WIPO (PCT)
Prior art keywords
active element
electro
acoustic transducer
substrate
recited
Prior art date
Application number
PCT/US2000/007663
Other languages
English (en)
Inventor
Richard E. Pearce
Original Assignee
Sercel, Inc.
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 Sercel, Inc. filed Critical Sercel, Inc.
Priority to AU40214/00A priority Critical patent/AU4021400A/en
Publication of WO2000057496A1 publication Critical patent/WO2000057496A1/fr

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
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers

Definitions

  • the present invention relates to a piezoelectric electro-acoustic transducer employing a diaphragm made of a piezoelectric film.
  • PVDF polyvinylidene fluoride
  • the recent art has arranged the film in a primitive shell configuration, such as a cylinder or a portion of a cylinder, to transform between (1) strain in the film along the uniaxial direction (which corresponds to the largest piezoelectric effect) and tangent to the film surface, and (2) the motion normal to the film surface necessary if direct electroacoustic transduction and the accompanying low mass/area ratio are to be achieved.
  • a primitive shell configuration such as a cylinder or a portion of a cylinder
  • an acoustic pressure difference between the surfaces of the piezoelectric film is supported by the arch of the cylindrical form and is transformed in part into stress and strain tangential to the film and in the uniaxial direction.
  • the piezoelectric effect gives rise to a variation in the length (or area) of the piezoelectric film.
  • This length variation is substantially linear with the applied voltage.
  • the conversion of this length in a direction perpendicular (normal) to the surface of the piezoelectric film, appears to be non-linear, the resultant deformation being dependent on the geometry of the piezoelectric film surface and the amplitude of the length variation (or area variation) of the piezoelectric film.
  • the geometry of the piezoelectric film is responsible for distortions occurring during conversion of electrical signals into acoustic signals and vice versa.
  • the present invention provides an electro-acoustic transducer including a substrate and an active element placed on the substrate.
  • the active element forms a catenary curve or a hyperbolic curve to define a sealed chamber between the active element and the substrate.
  • the active element includes a piezoelectric material, such as a polyvinylidene fluoride material.
  • the substrate further comprises at least one cavity wherein the active element is placed over the at least one cavity to form the sealed chamber.
  • the at least one cavity is, for example, of a substantially concave shape and the catenary curve is formed by the active element at each cavity.
  • a diaphragm is for example bonded to the piezoelectric material.
  • a diaphragm having a standoff ledge is used to provide the cavity and the active element is placed over the diaphragm.
  • At least two active elements are placed on the substrate to provide for discrete multiple transducers.
  • Each of the active elements form catenary curves or hyperbolic curves to define a sealed chamber between the first active element and the substrate and between the second active element and the first active element.
  • Figure 1 is a side view showing an embodiment of the transducer according to the present invention.
  • Figures 2A-2C are cross sectional views of Figure 1 taken along line A- A, wherein Figure 2B is an exploded cross sectional view;
  • Figure 3 is a top view showing another embodiment of the transducer according to the present invention.
  • Figure 4 is a cross sectional view of Figure 3 taken along line B-B;
  • Figure 5 is a bottom view of still another embodiment of the transducer according to the present invention.
  • Figure 6 is a cross sectional view of Figure 5 taken along line C-C;
  • Figures 7A-7B are cross sectional views of an embodiment of the transducer according to the present invention wherein multiple discrete active elements are stacked.
  • the electro-acoustic transducer of the present invention when excited with an electrical signal of any form or placed in a dynamic pressure field, correspondingly transmits acoustic energy or, conversely, when excited with a form of acoustic energy transfers the acoustic energy into electrical energy, accurately reproducing the waveform in domain.
  • the electro-acoustic transducer 90 is illustrated including a substrate 100 having at least one active element 104 including a thin sheet or film of a pre-formed, flexible, bi-polar piezoelectric material 114, such as, preferably, a polyvinylidene fluoride ("PVDF").
  • PVDF polyvinylidene fluoride
  • the thickness of the PVDF material is preferably in the order of 28 microns, although other thicknesses may be used.
  • the substrate 100 includes at least one cavity 106 of a desired shape and depth and is bounded by shoulders 108.
  • the active element 104 forms a catenary curve across the at least one cavity 106 to define a sealed chamber 110 between the active element 104 and the surface 102 of the substrate 100.
  • the substrate 100 is, for example, made of an aluminum material, a carbon fiber material, or other suitable stiff material.
  • the substrate 100 can include any of a variety of shapes, such as, for example, a cylindrical shape ( Figures 1 and 2A-2C), or a flat shape ( Figures 3 and 4).
  • a plurality of cavities 106 of a substantially concave shape and bounded by shoulders 108 are included on a surface 102 of the substrate 100.
  • the active element 104 forms a catenary curve across the plurality of cavities 106 to define a plurality of sealed chambers 110 between the active element 104 and the surface 102 of the substrate 100.
  • the cavities 106 are positioned relative to each other and the active element 104 is, for example, hermetically sealed at the shoulders 108 by a suitable means such as an adhesive or a clamp, placed around the entire periphery of each cavity 106 to form an enclosed or sealed chamber 110 between the active element 104 and the surface 102 of the substrate 100.
  • the transducer 90 includes, for example, unpressurized air in the sealed chamber 110.
  • the plurality of cavities 106 are formed on the surface 102 of the substrate 100.
  • a compliant diaphragm 112 having a standoff ledge for forming the shoulders 108 also forms the plurality of cavities 106 and is bonded to the piezoelectric material 114.
  • a protective layer over the piezoelectric material 114 can be used to protect the active element 104.
  • the size of the active element 104 is sufficient to cover the entire surface 102 of the substrate 100.
  • the active element 104 is placed on the substrate 100 over the cavities 106 and is hermetically sealed at the shoulders 108 by a suitable means, such as an adhesive or a clamp, placed around the entire periphery of the shoulders 108 to form the sealed chamber 110 between the active element 104 and the substrate 100.
  • Electrical connectors 116 and 118 are coupled to the piezoelectric material 114 using, for example, a piezoelectric film tab 120.
  • the electrical connectors 116 and 118 receive or transmit electrical signals from or to the piezoelectric material 114.
  • the application of an electrical signal across the electrical connectors 116 and 118 results in a change in length in the piezoelectric material 114 or film as well as a change in the thickness of the piezoelectric material 114.
  • the change in length of the piezoelectric material 114 when suspended across a fixed length results in a change in volume in the medium in which the transducer 90 operates.
  • FIGS 5 and 6 illustrate another embodiment of a transducer 130 according to the present invention wherein the active element 104, including the piezoelectric material 114, forms a hyperbolic curve to define the sealed chamber 110 between the active element 104 and the substrate 100.
  • the substrate 100 has a substantially hyperbolic curved shape and the active element 104 is placed over an inner surface 126 of the substrate 100 to form the sealed chamber 110.
  • the electrical connectors 116 and 118 are coupled to the piezoelectric material 114 using, for example, a piezoelectric film tab 120.
  • the electrical connectors 116 and 118 receive or transmit electrical signals from or to the piezoelectric material 114.
  • the medium in which the transducer 130 operates is allowed to flood both sides of the active element 104.
  • the shape of the piezoelectric material 114 across the sealed chamber 110 is important in the performance of the transducer 90 of the present invention.
  • the piezoelectric material 114 is shaped substantially in the form of a catenary curve or a hyperbolic curve.
  • the apex 124 of the catenary curve or hyperbolic curve of the piezoelectric material 114 provides for a focused direction for the change in length and thickness or strain of the piezoelectric material 114.
  • the smaller the angle of the apex 124 of the catenary curve shape or the hyperbolic curve shape of the piezoelectric material 114 the more directionally focused the change of the piezoelectric material 114 becomes, providing for less distortions in converting acoustic signals into electrical signals and vise versa.
  • the catenary curve and the hyperbolic curve shaped active elements of the present invention provide for greater signal reliability than the typical cylinder shaped active element transducer since, for a given surface area, the volume displaced by the catenary curve and the hyperbolic curve shaped active elements is greater than that of the cylinder shaped active element.
  • the use of the active element formed into a catenary curve or a hyperbolic curve can also be used to provide for multiple discrete transducers on a substrate as illustrated in Figures 7A and 7B by stacking the active elements.
  • a first active element 132 and a second active element 134 are placed on the substrate 100.
  • Each of the first and second active elements 132 and 134 respectively, form a catenary curve or a hyperbolic curve (not shown) to define a first sealed chamber 136 between the first active element 132 and the substrate 100, and a second sealed chamber 138 between the first active element 132 and the second active element 134.
  • Electrical connectors are coupled to the first and second active elements 132 and 134, respectively, to provide for multi-channel data acquisition.
  • the output response from the first active element 132 is combined with the output response from the second active element 134 to provide for a combined output response having a reduced distortion.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)

Abstract

L'invention concerne un transducteur électroacoustique (90) comprenant un substrat (100) et un élément actif (104) placé sur le substrat (100). L'élément actif forme une courbe caténaire ou hyperbolique de manière à délimiter une chambre étanche entre l'élément actif (104) et le substrat (100). L'élément actif (104) comprend un matériau piézo-électrique (114) tel qu'un matériau à base de fluorure de polyvinylidène. Dans un mode de réalisation, le substrat (100) comprend aussi au moins une cavité (106), l'élément actif (104) étant placé par-dessus cette cavité (106) de manière à former la chambre étanche. La cavité (106) peut avoir, par exemple, une forme sensiblement concave, et la courbe caténaire est formée par l'élément actif (104) dans chacune de ces cavités (106). On utilise un diaphragme possédant un rebord situé à l'écart pour créer la cavité (106) puis on place l'élément actif (104) par-dessus le diaphragme. Dans un autre mode de réalisation, au moins deux éléments actifs, y compris un premier élément actif et un deuxième élément actif, sont placés sur un substrat pour former plusieurs transducteurs discrets. Chacun des éléments actifs forme des courbes caténaires ou hyperboliques de manière à définir une chambre étanche entre le premier élément actif et le substrat et entre le deuxième élément actif et le premier élément actif.
PCT/US2000/007663 1999-03-22 2000-03-22 Transducteur electroacoustique a bande large WO2000057496A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU40214/00A AU4021400A (en) 1999-03-22 2000-03-22 Broadband elecro-acoustic transducer

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US27409099A 1999-03-22 1999-03-22
US09/274,090 1999-03-22

Publications (1)

Publication Number Publication Date
WO2000057496A1 true WO2000057496A1 (fr) 2000-09-28

Family

ID=23046727

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2000/007663 WO2000057496A1 (fr) 1999-03-22 2000-03-22 Transducteur electroacoustique a bande large

Country Status (2)

Country Link
AU (1) AU4021400A (fr)
WO (1) WO2000057496A1 (fr)

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3924974A (en) * 1973-05-21 1975-12-09 Rca Corp Fluid ejection or control device
US3953828A (en) * 1968-11-08 1976-04-27 The United States Of America As Represented By The Secretary Of The Navy High power-wide frequency band electroacoustic transducer
US3985201A (en) * 1974-10-24 1976-10-12 Kloster Glenn R Infinite sound reproduction chamber
US4284921A (en) * 1977-11-17 1981-08-18 Thomson-Csf Polymeric piezoelectric transducer with thermoformed protuberances
US4437033A (en) * 1980-06-06 1984-03-13 Siemens Aktiengesellschaft Ultrasonic transducer matrix having filler material with different acoustical impedance
US4445380A (en) * 1982-07-21 1984-05-01 Technicare Corporation Selectable focus sphericone transducer and imaging apparatus
US4558249A (en) * 1980-03-10 1985-12-10 Reinhard Lerch Stretched piezopolymer transducer with unsupported areas
US4641530A (en) * 1984-09-12 1987-02-10 Centre National De La Recherche Scientifique Acoustic microscope for analyzing an object in depth having aspherical lenses
US4996713A (en) * 1989-09-25 1991-02-26 S. Eletro-Acustica S.A. Electroacoustic piezoelectric transducer having a broad operating range
US5027659A (en) * 1988-03-11 1991-07-02 General Electric Cbr Sa Ultrasonic imaging device in which electroacoustic transducers are disposed on a convex probe
US5373483A (en) * 1991-03-29 1994-12-13 The Charles Stark Draper Laboratory, Inc. Curvilinear wideband, projected derivative-matched, continuous aperture acoustic transducer
US5434830A (en) * 1990-04-27 1995-07-18 Commonwealth Scientific And Industrial Research Organization Ultrasonic transducer
US5437195A (en) * 1991-12-17 1995-08-01 Thomson-Csf Mechanical sensor produced from a polymer film

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3953828A (en) * 1968-11-08 1976-04-27 The United States Of America As Represented By The Secretary Of The Navy High power-wide frequency band electroacoustic transducer
US3924974A (en) * 1973-05-21 1975-12-09 Rca Corp Fluid ejection or control device
US3985201A (en) * 1974-10-24 1976-10-12 Kloster Glenn R Infinite sound reproduction chamber
US4284921A (en) * 1977-11-17 1981-08-18 Thomson-Csf Polymeric piezoelectric transducer with thermoformed protuberances
US4558249A (en) * 1980-03-10 1985-12-10 Reinhard Lerch Stretched piezopolymer transducer with unsupported areas
US4437033A (en) * 1980-06-06 1984-03-13 Siemens Aktiengesellschaft Ultrasonic transducer matrix having filler material with different acoustical impedance
US4564980A (en) * 1980-06-06 1986-01-21 Siemens Aktiengesellschaft Ultrasonic transducer system and manufacturing method
US4445380A (en) * 1982-07-21 1984-05-01 Technicare Corporation Selectable focus sphericone transducer and imaging apparatus
US4641530A (en) * 1984-09-12 1987-02-10 Centre National De La Recherche Scientifique Acoustic microscope for analyzing an object in depth having aspherical lenses
US5027659A (en) * 1988-03-11 1991-07-02 General Electric Cbr Sa Ultrasonic imaging device in which electroacoustic transducers are disposed on a convex probe
US4996713A (en) * 1989-09-25 1991-02-26 S. Eletro-Acustica S.A. Electroacoustic piezoelectric transducer having a broad operating range
US5434830A (en) * 1990-04-27 1995-07-18 Commonwealth Scientific And Industrial Research Organization Ultrasonic transducer
US5373483A (en) * 1991-03-29 1994-12-13 The Charles Stark Draper Laboratory, Inc. Curvilinear wideband, projected derivative-matched, continuous aperture acoustic transducer
US5437195A (en) * 1991-12-17 1995-08-01 Thomson-Csf Mechanical sensor produced from a polymer film

Also Published As

Publication number Publication date
AU4021400A (en) 2000-10-09

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