EP0142178B1 - Ultrasonic transducer - Google Patents

Ultrasonic transducer Download PDF

Info

Publication number
EP0142178B1
EP0142178B1 EP84201200A EP84201200A EP0142178B1 EP 0142178 B1 EP0142178 B1 EP 0142178B1 EP 84201200 A EP84201200 A EP 84201200A EP 84201200 A EP84201200 A EP 84201200A EP 0142178 B1 EP0142178 B1 EP 0142178B1
Authority
EP
European Patent Office
Prior art keywords
piezoelectric material
layer
medium
acoustic impedance
layers
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
EP84201200A
Other languages
German (de)
French (fr)
Other versions
EP0142178A1 (en
EP0142178B2 (en
Inventor
Claude Robert Mequio
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.)
Laboratoires dElectronique Philips SAS
Koninklijke Philips NV
Original Assignee
Laboratoires dElectronique Philips SAS
Laboratoires dElectronique et de Physique Appliquee
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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 Laboratoires dElectronique Philips SAS, Laboratoires dElectronique et de Physique Appliquee, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Laboratoires dElectronique Philips SAS
Publication of EP0142178A1 publication Critical patent/EP0142178A1/en
Publication of EP0142178B1 publication Critical patent/EP0142178B1/en
Application granted granted Critical
Publication of EP0142178B2 publication Critical patent/EP0142178B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators

Definitions

  • the present invention relates to an ultrasonic transducer comprising a substrate constituting a rear medium, a layer of piezoelectric material and one or more matching layers whose acoustic impedance has a value between that of the piezoelectric material and that of a medium before spread.
  • a second embodiment of the ultrasonic transducer according to the invention is presented as an ultrasonic transducer comprising a substrate constituting a rear medium, a layer of piezoelectric material and one or more adaptation layers, the values of the impedances of the layer of piezoelectric material, adaptation layers of acoustic impedance and of the medium before propagation forming, considered in this order, a decreasing sequence, characterized in that the adaptation layers are placed in identical number on either side of the piezoelectric material, the layers located symmetrically two by two having the same acoustic impedance value and the same thickness, in that the rear medium has an acoustic impedance value substantially equal to that of the medium before propagation, and in that the thickness of the layer of piezoelectric material is equal to half the wavelength associated with the f resonance frequency of the transducer, so that the structure is symmetrical with respect to the median plane of the layer of piezoelectric material.
  • the essential characteristic of the structure with total symmetry is very good damping.
  • the advantages of the structure with virtual symmetry are the following: gain of 6 dB (maximum) on the sensitivity index of the structure with total symmetry, thanks to the effect of "acoustic mirror of the rigid rear center which reflects all the acoustic energy towards the front, maintaining the same damping as that, very satisfactory, of the structure with total symmetry, thickness of the piezoelectric material twice less, for a given working frequency, than with conventional transducers with a piezoelectric layer in ⁇ / 2 (this last characteristic is important for piezoelectric polymers such as the polyvinylidene fluoride mentioned above, which are difficult to obtain in high thicknesses).

Description

La présente invention concerne un transducteur ultrasonore comprenant un substrat constituant un milieu arrière, une couche de matériau piézoélectrique et une ou plusieurs couches d'adaptation dont l'impédance acoustique a une valeur comprise entre celle du matériau piézoélectrique et celle d'un milieu avant de propagation.The present invention relates to an ultrasonic transducer comprising a substrate constituting a rear medium, a layer of piezoelectric material and one or more matching layers whose acoustic impedance has a value between that of the piezoelectric material and that of a medium before spread.

Un transducteur ultrasonore est constitué essentiellement, de façon classique, d'un substrat constituant un milieu arrière d'absorption ou de réflexion, d'une couche de matériau piézoélectrique équipée d'électrodes sur ses faces avant et arrière et d'au moins une couche d'adaptation d'impédance acoustique, placée devant le matériau piézoélectrique, entre celui-ci et le milieu de propagation. Des transducteurs de ce type sont notamment décrits dans l'article « The effects of backing and matching on the performance of piezoelectric ceramic transducers de G. Kossoff, paru dans la revue IEEE Transactions on sonics and uitrasonics, volume SU-13, mars 1966, pages 20 à 30. La mise en place d'une ou de plusieurs de ces couches d'adaptation a pour effet principal d'améliorer la sensibilité des transducteurs et contribue également à augmenter leur largeur de bande.An ultrasonic transducer essentially consists, in a conventional manner, of a substrate constituting a rear absorption or reflection medium, a layer of piezoelectric material equipped with electrodes on its front and rear faces and at least one layer acoustic impedance matching, placed in front of the piezoelectric material, between it and the propagation medium. Transducers of this type are notably described in the article “The effects of backing and matching on the performance of piezoelectric ceramic transducers by G. Kossoff, published in the journal IEEE Transactions on sonics and uitrasonics, volume SU-13, March 1966, pages 20 to 30. The implementation of one or more of these adaptation layers has the main effect of improving the sensitivity of the transducers and also contributes to increasing their bandwidth.

On rappellera ici que les transducteurs ultrasonores utilisés en échographie doivent réunir deux qualités principales au niveau de la transduction : non seulement une bonne sensibilité (car l'augmentation du rapport signal-sur-bruit facilite le traitement des signaux reçus) mais aussi un amortissement suffisant (car la brièveté de la réponse impulsionnelle conditionne la résolution axiale).It will be recalled here that the ultrasonic transducers used in ultrasound must combine two main qualities at the level of transduction: not only good sensitivity (because the increase in the signal-to-noise ratio facilitates the processing of the signals received) but also sufficient damping (because the brevity of the impulse response conditions the axial resolution).

Le but de l'invention est de proposer un transducteur ultrasonore conciliant de façon simple les exigences de sensibilité et d'amortissement.The object of the invention is to propose an ultrasonic transducer which easily reconciles the requirements of sensitivity and damping.

A cet effet une première réalisation du transducteur ultrasonore conforme à l'invention se présente comme un transducteur ultrasonore comprenant un substrat constituant un milieu arrière, une couche de matériau piézoélectrique et une ou plusieurs couches d'adaptation placées entre le matériau piézoélectrique et le milieu avant de propagation, les valeurs des impédances de la couche de matériau piézoélectrique, des couches d'adaptation d'impédance acoustique et du milieu avant de propagation formant, considérées dans cet ordre, une suite décroissante, caractérisé en ce que le milieu arrière a une valeur d'impédance acoustique suffisamment élevée par rapport à celle du matériau piézoélectrique pour pouvoir être considéré comme rigide, et en ce que l'épaisseur de la couche de matériau piézoélectrique est égale au quart de la longueur d'onde associée à la fréquence de résonance du transducteur.To this end, a first embodiment of the ultrasonic transducer according to the invention is presented as an ultrasonic transducer comprising a substrate constituting a rear medium, a layer of piezoelectric material and one or more adaptation layers placed between the piezoelectric material and the front medium. propagation, the values of the impedances of the layer of piezoelectric material, of the acoustic impedance adaptation layers and of the medium before propagation forming, considered in this order, a decreasing sequence, characterized in that the rear medium has a value of sufficiently high acoustic impedance compared to that of the piezoelectric material to be considered rigid, and in that the thickness of the layer of piezoelectric material is equal to a quarter of the wavelength associated with the resonant frequency of the transducer.

Une deuxième réalisation du transducteur ultrasonore conforme à l'invention se présente comme un transducteur ultrasonore comprenant un substrat constituant un milieu arrière, une couche de matériau piézoélectrique et une ou plusieurs couches d'adaptation, les valeurs des impédances de la couche de matériau piézoélectrique, des couches d'adaptation d'impédance acoustique et du milieu avant de propagation formant, considérées dans cet ordre, une suite décroissante, caractérisé en ce que les couches d'adaptation sont placées en nombre identique de part et d'autre du matériau piézoélectrique, les couches situées symétriquement deux à deux ayant la même valeur d'impédance acoustique et la même épaisseur, en ce que le milieu arrière a une valeur d'impédance acoustique sensiblement égale à celle du milieu avant de propagation, et en ce que l'épaisseur de la couche de matériau piézoélectrique est égale à la moitié de la longueur d'onde associée à la fréquence de résonance du transducteur, de façon que la structure soit symétrique par rapport au plan médian de la couche de matériau piézoélectrique.A second embodiment of the ultrasonic transducer according to the invention is presented as an ultrasonic transducer comprising a substrate constituting a rear medium, a layer of piezoelectric material and one or more adaptation layers, the values of the impedances of the layer of piezoelectric material, adaptation layers of acoustic impedance and of the medium before propagation forming, considered in this order, a decreasing sequence, characterized in that the adaptation layers are placed in identical number on either side of the piezoelectric material, the layers located symmetrically two by two having the same acoustic impedance value and the same thickness, in that the rear medium has an acoustic impedance value substantially equal to that of the medium before propagation, and in that the thickness of the layer of piezoelectric material is equal to half the wavelength associated with the f resonance frequency of the transducer, so that the structure is symmetrical with respect to the median plane of the layer of piezoelectric material.

La demande de brevet européen publiée N' EP-A-0015886 décrit diverses réalisations de transducteurs ultrasonores qui, toutes, comprennent d'une part une couche de matériau piézoélectrique et d'autre part une ou plusieurs couches dites additionnelles, placées juste en avant et/ou arrière dudit matériau piézoélectrique et qui ont une impédance acoustique égale à ou très voisine de celle de ce matériau. La modélisation dite de Cook-Redwood, exposée pour la première fois par E. G. Cook, en 1956, dans la communication « Transient and steady-state response of ultrasonic piezoelectric transducers ", IRE Conv. Record, 4, 1956, page 61-69, et généralisée par M. Redwood, permet cependant d'effectuer l'analyse mathématique des structures proposées dans ce document cité et de montrer que ces couches additionnelles jouent un rôle piézoélectrique. Cette analyse montre en effet que le régime des vibrations ultrasonores s'établit non pas dans le seul matériau piézoélectrique, mais dans la cavité globale constituée par ce matériau et la ou les couches additionnelles. Ces couches augmentent artificiellement l'épaisseur du matériau piézoélectrique, et abaissent donc la fréquence de travail de celui-ci, pour rendre cette fréquence compatible avec la gamme des fréquences dans laquelle se situent les applications médicales. Elles jouent donc un rôle sans rapport avec le rôle d'amortissement tenu par les couches d'adaptation d'impédance acoustique prévues dans la présente demande.The published European patent application No. EP-A-0015886 describes various embodiments of ultrasonic transducers which all comprise on the one hand a layer of piezoelectric material and on the other hand one or more so-called additional layers, placed just in front and / or rear of said piezoelectric material and which have an acoustic impedance equal to or very close to that of this material. The so-called Cook-Redwood modeling, exposed for the first time by EG Cook, in 1956, in the communication "Transient and steady-state response of ultrasonic piezoelectric transducers " , IRE Conv. Record, 4, 1956, page 61-69, and generalized by M. Redwood, allows however to carry out the mathematical analysis of the structures proposed in this cited document and to show that these additional layers play a piezoelectric role. This analysis shows indeed that the regime of ultrasonic vibrations is established not not in the piezoelectric material alone, but in the overall cavity formed by this material and the additional layer or layers. These layers artificially increase the thickness of the piezoelectric material, and therefore lower the working frequency of the latter, to make this frequency compatible with the range of frequencies in which medical applications are located. They therefore play a role unrelated to the role damping held by the acoustic impedance adaptation layers provided for in this application.

Les particularités et avantages de l'invention vont être maintenant décrits ci-dessous plus en détail en se référant aux figures 1 et 2, données à titre d'exemples non limitatifs et qui montrent deux réalisation de transducteurs conformes à l'invention.The features and advantages of the invention will now be described below in more detail with reference to Figures 1 and 2, given by way of non-limiting examples and which show two embodiments of transducers according to the invention.

La première réalisation, représentée sur la figure 1, consiste en un transducteur ultrasonore à vibration en mode d'épaisseur, composé d'un substrat 10 constituant le milieu arrière de transducteur, d'une couche 20 de matériau piézoélectrique recouverte sur ses faces avant et arrière de feuilles métalliques 21 et 22 constituant des première et deuxième électrodes (reliées de façon connue à un circuit de polarisation non représenté qui fournit le potentiel d'excitation), et, entre cette couche 20 et le milieu avant de propagation 50, de deux couches 30 et 40 d'adaptation d'impédance acoustique (dites couches interférentielles quart d'onde).The first embodiment, represented in FIG. 1, consists of an ultrasonic transducer with vibration in thickness mode, composed of a substrate 10 constituting the rear middle of the transducer, a layer 20 of piezoelectric material covered on its front faces and rear of metal sheets 21 and 22 constituting first and second electrodes (connected in a known manner to a polarization circuit not shown which provides the excitation potential), and, between this layer 20 and the medium before propagation 50, of two layers 30 and 40 of acoustic impedance matching (called quarter wave interference layers) .

Dans cette première structure selon l'invention, le substrat 10 présente par rapport à la couche 20 de matériau piézoélectrique une valeur d'impédance acoustique très nettement supérieure, et suffisamment élevée en tout cas pour que ce substrat puisse être considéré comme rigide relativement au matériau piézoélectrique, c'est-à-dire comme un milieu arrière à déformation nulle. En outre, l'épaisseur de la couche 20 est égale au quart de la longueur d'onde associée à la fréquence de. résonance du transducteur. Enfin, si l'on veut optimiser le transfert d'énergie de la couche 20 de matériau piézoélectrique vers le milieu avant de propagation 50, les valeurs des impédances de cette couche 20, des couches d'adaptation 30 et 40 et du milieu de propagation forment, considérées dans cet ordre, une suite décroissante, par exemple et de façon non limitative une suite arithmétique ou géométrique.In this first structure according to the invention, the substrate 10 has, with respect to the layer 20 of piezoelectric material, a value of acoustic impedance very much higher, and sufficiently high in any case so that this substrate can be considered as rigid relative to the material piezoelectric, that is to say as a rear medium with zero deformation. In addition, the thickness of the layer 20 is equal to a quarter of the wavelength associated with the frequency of. transducer resonance. Finally, if we want to optimize the energy transfer from the layer 20 of piezoelectric material to the medium before propagation 50, the values of the impedances of this layer 20, of the adaptation layers 30 and 40 and of the propagation medium form, considered in this order, a decreasing sequence, for example and without limitation an arithmetic or geometric sequence.

Pour comprendre maintenant comment la première structure ainsi décrite présente à la fois une bonne sensibilité et un excellent amortissement, on imagine (voir la figure 2) un deuxième transducteur ultrasonore, totalement symétrique, comprenant un substrat 10 servant de milieu arrière, une couche 20 de matériau piézoélectrique d'épaisseur égale à la moitié de la longueur d'onde associée à la fréquence de résonance du transducteur, et deux couches 30, 40 d'adaptation d'impédance acoustique d'une part entre le milieu arrière et le matériau piézoélectrique et d'autre part entre ce matériau et le milieu avant de propagation 50. Dans cette deuxième structure, les valeurs des impédances acoustiques forment de même une suite décroissante à partir de celle du matériau piézoéiectrique et ces valeurs ainsi que les épaisseurs des couches 30, 40 d'adaptation sont symétriques de part et d'autre de ce matériau. Les tests et simulations effectués avec une structure ainsi constituée montrent que le spectre (ou module de la transformée de Fourier) de la réponse électrique en mode échographique à une excitation électrique de type impulsionnel et de durée effective égale au temps de vol dans le matériau piézoélectrique (le temps de vol est la durée du parcours des ondes ultrasonores d'une face à l'autre du matériau piézoélectrique) vibrant suivant son épaisseur égale à la moitié de la longueur d'onde ultrasonore à la fréquence d'émission du transducteur est de forme gaussienne ; par suite, l'enveloppe de la réponse électrique est également gaussienne et cette réponse s'amortit rapidement Par ailleurs, de la symétrie de la structure, il résulte que les déformations sur les deux faces du matériau piézoélectrique sont identiques (puisque ces deux faces sont, acoustiquement, chargées de façon identique) et que, par suite, la déformation est nulle dans le plan médian de ce matériau. La partie de la deuxième structure qui se trouve située d'un seul côté de ce plan médian est donc équivalente à un milieu arrière infiniment rigide, c'est-à-dire à déformation nulle. Un tel milieu est assez facilement réalisable si le matériau piézoélectrique choisi ne possède pas une impédance acoustique trop élevée: d'où la proposition de la première structure, dite à symétrie virtuelle et comprenant donc un milieu arrière rigide, une couche piézoélectrique ayant une épaisseur égale à un quart de ladite longueur d'onde, et les couches d'adaptation d'impédance acoustique, cette structure présentant les mêmes caractéristiques d'amortissement que la deuxième structure totalement symétrique mais une sensibilité améliorée.To understand now how the first structure thus described has both good sensitivity and excellent damping, we imagine (see Figure 2) a second ultrasonic transducer, completely symmetrical, comprising a substrate 10 serving as rear medium, a layer 20 of piezoelectric material with a thickness equal to half the wavelength associated with the resonant frequency of the transducer, and two acoustic impedance matching layers 30, 40 on the one hand between the rear medium and the piezoelectric material and on the other hand between this material and the medium before propagation 50. In this second structure, the values of the acoustic impedances likewise form a decreasing sequence from that of the piezoelectric material and these values as well as the thicknesses of the layers 30, 40 are symmetrical on both sides of this material. The tests and simulations carried out with a structure thus constituted show that the spectrum (or module of the Fourier transform) of the electrical response in ultrasound mode to an electrical excitation of impulse type and of effective duration equal to the time of flight in the piezoelectric material (the flight time is the duration of the path of the ultrasonic waves from one face to the other of the piezoelectric material) vibrating according to its thickness equal to half of the ultrasonic wavelength at the emission frequency of the transducer is Gaussian form; as a result, the envelope of the electrical response is also Gaussian and this response is rapidly amortized. Furthermore, from the symmetry of the structure, it follows that the deformations on the two faces of the piezoelectric material are identical (since these two faces are , acoustically loaded identically) and that, consequently, the deformation is zero in the median plane of this material. The part of the second structure which is located on only one side of this median plane is therefore equivalent to an infinitely rigid rear medium, that is to say with zero deformation. Such a medium is fairly easily achievable if the chosen piezoelectric material does not have too high an acoustic impedance: hence the proposal of the first structure, called virtual symmetry and therefore comprising a rigid rear medium, a piezoelectric layer having an equal thickness at a quarter of said wavelength, and the acoustic impedance matching layers, this structure having the same damping characteristics as the second completely symmetrical structure but improved sensitivity.

Les essais et simulations réalisés (dans d'égales conditions électriques d'émission et de réception) ont montré la possibilité d'obtenir effectivement diverses structures répondant aux objectifs de l'invention (sensibilité et amortissement simultanément satisfaisants). Dans le cas où le matériau piézoélectrique est une céramique ferroélectrique de type PZT-5 (matériau piézoélectrique à base de zirconate titanate de plomb : voir l'ouvrage « Physical Acoustics, Principles and Methods », de Warren P. Mason, Vol. 1, partie A, page 202), on peut citer les exemples suivants (exemples à deux couches d'adaptation d'impédance acoustique) :

  • (1) première structure (à symétrie virtuelle) :
    • (a) impédances (en kglcm2.sec x 106) :
      • - milieu arrière : 1 000 (simulation)
      • - matériau piézoélectrique : 30
      • - première couche d'adaptation : 4
      • - deuxième couche d'adaptation : 1,8
      • - milieu avant de propagation : 1,5
    • (b) résultats obtenus :
      • - indice de sensibilité =―10,03 dB
      • - largeur de bande relative à - 6 dB = 55 %
      • - durée de réponse à - 20 dB = 7,6 τ
      • - durée de réponse à - 40 dB = 8,9 τ
The tests and simulations carried out (under equal electrical conditions of emission and reception) have shown the possibility of effectively obtaining various structures meeting the objectives of the invention (sensitivity and damping simultaneously satisfactory). In the case where the piezoelectric material is a ferroelectric ceramic of the PZT-5 type (piezoelectric material based on lead zirconate titanate: see the work "Physical Acoustics, Principles and Methods", by Warren P. Mason, Vol. 1, part A, page 202), the following examples can be cited (examples with two layers of acoustic impedance adaptation):
  • (1) first structure (with virtual symmetry):
    • (a) impedances (in kglcm 2 .sec x 106):
      • - rear midpoint: 1,000 (simulation)
      • - piezoelectric material: 30
      • - first adaptation layer: 4
      • - second adaptation layer: 1.8
      • - medium before propagation: 1.5
    • (b) results obtained:
      • - sensitivity index = ―10.03 dB
      • - relative bandwidth at - 6 dB = 5 5%
      • - response time at - 20 dB = 7.6 τ
      • - response time at - 40 dB = 8.9 τ

(On rappellera ici que la sensibilité est caractérisée par un indice de sensibilité dont l'expression en dB est du type 20 log VS/VREF où VREF est pour un générateur d'impédance interne adaptée à sa charge la tension permettant l'émission d'une impulsion résonnante rectangulaire et où Vs est la tension crête-à- crête de la réponse, et que l'amortissement est généralement caractérisé par la largeur de bande relative à - 6 dB dF/F du spectre fondamental, exprimée en % et dans laquelle dF est l'écart entre les points où l'amplitude électrique est à - 6 dB sous le maximum et F la fréquence centrale correspondant audit maximum. Cependant, cette dernière information est insuffisante pour caractériser complètement l'amortissement puisqu'elle ne tient compte ni de la forme, qui peut être irrégulière, du spectre fondamental ni de la présence d'harmoniques supérieurs qui perturbent la fin des échos, et elle est complétée par deux autres indicateurs temporels qui sont les durées de la réponse électrique à - 20 dB et à - 40 dB (ces points à - 20 et - 40 dB étant définis par les instants auxquels l'amplitude crête-à- crête est devenue inférieure respectivement au dixième et au centième de sa valeur initiale) à une impulsion résonnante rectangulaire de durée T, ces durées étant normées (c'est-à-dire exprimées par référence audit temps de vol τ).(It will be recalled here that the sensitivity is characterized by a sensitivity index whose expression in dB is of the type 20 log V S / V REF where V REF is for an internal impedance generator adapted to its load the voltage allowing the emission of a rectangular resonant pulse and where V s is the peak-to-peak voltage of the response, and that the damping is generally characterized by the relative bandwidth at - 6 dB dF / F of the fundamental spectrum, expressed in % and in which dF is the difference between the points where the electrical amplitude is at - 6 dB below the maximum and F the central frequency corresponding to said maximum. However, this latter information is insufficient to fully characterize the damping since it takes into account neither the shape, which can be irregular, the fundamental spectrum nor the presence of higher harmonics which disturb the end of the echoes, and it is supplemented by two other time indicators which are the durations of the electrical response at - 20 dB and - 40 dB (these points at - 20 and - 40 dB being defined by the instants at which the peak-to-peak amplitude has become less respectively to the tenth and to the hundredth of its initial value) to a rectangular resonant pulse of duration T , these durations being normalized (that is to say expressed by reference to said flight time τ).

  • (2) deuxième structure, à symétrie totale, duale de la précédente :
    • (a) impédances :
      • - milieu arrière : 1,5
      • - couches d'adaptation : 1,8 et 4
      • - matériau piézoélectrique : 30
      • - couche d'adaptation : 4 et 1,8
      • - milieu avant de propagation : 1,5
    • (b) résultats obtenus :
      • - indice de sensibilité : ―13 dB
      • - largeur de bande relative à - 6 dB = 53 %
      • - durée de réponse à ―20 dB = 7,79 τ
      • - durée de réponse à - 40 dB = 9,8 τ
    (2) second structure, with total symmetry, dual from the previous one:
    • (a) impedances:
      • - rear center: 1.5
      • - adaptation layers: 1.8 and 4
      • - piezoelectric material: 30
      • - adaptation layer: 4 and 1.8
      • - medium before propagation: 1.5
    • (b) results obtained:
      • - sensitivity index: ―13 dB
      • - relative bandwidth at - 6 dB = 53%
      • - response time at ―20 dB = 7.79 τ
      • - response time at - 40 dB = 9.8 τ

Dans le cas où le matériau piézoélectrique est du polyfluorure de vinylidène, on peut citer de même les exemples suivants (exemples à une couche d'adaptation d'impédance acoustique) :In the case where the piezoelectric material is polyvinylidene fluoride, the following examples can also be cited (examples with an acoustic impedance matching layer):

  • (3) première structure (à symétrie virtuelle) :
    • (a) impédances :
      • - milieu arrière : 46
      • - matériau piézoélectrique: 4,6
      • - couche d'adaptation : 1,8
      • - milieu avant de propagation : 1,5
    • (b) résultats obtenus :
      • - indice de sensibilité = ―19,66 dB
      • - largeur de bande relative à - 6 dB = 82 %
      • - durée de réponse à - 20 dB = 5,4 τ
      • - durée de réponse à - 40 dB = 7,8 τ
    (3) first structure (with virtual symmetry):
    • (a) impedances:
      • - rear center: 46
      • - piezoelectric material: 4.6
      • - adaptation layer: 1.8
      • - medium before propagation: 1.5
    • (b) results obtained:
      • - sensitivity index = ―19.66 dB
      • - relative bandwidth at - 6 dB = 82%
      • - response time at - 20 dB = 5.4 τ
      • - response time at - 40 dB = 7.8 τ
  • (4) deuxième structure, à symétrie totale, duale de la précédente :
    • (a) impédances :
      • - milieux arrière et avant : 1,5
      • - couches d'adaptation arrière et avant : 1,8
      • - matériau piézoélectrique : 4,6
    • (b) résultats obtenus :
      • - indice de sensibilité = ― 23,8 dB
      • - largeur de bande relative à - 6 dB = 75 %
      • - durée de réponse à - 20 dB = 5,63 τ
      • - durée de réponse à -40 dB = 8 τ
    (4) second structure, with total symmetry, dual from the previous one:
    • (a) impedances:
      • - rear and front midpoints: 1.5
      • - rear and front adaptation layers: 1.8
      • - piezoelectric material: 4.6
    • (b) results obtained:
      • - sensitivity index = - 23.8 dB
      • - relative bandwidth at - 6 dB = 75%
      • - response time at - 20 dB = 5.63 τ
      • - response time at -40 dB = 8 τ

La caractéristique essentielle de la structure à symétrie totale (figure 2) est un très bon amortissement. Les avantages de la structure à symétrie virtuelle (figure 1) sont, eux, les suivants : gain de 6 dB (au maximum) sur l'indice de sensibilité de la structure à symétrie totale, grâce à l'effet de « miroir acoustique du milieu arrière rigide qui réfléchit toute l'énergie acoustique vers l'avant, maintien du même amortissement que celui, très satisfaisant, de la structure à symétrie totale, épaisseur du matériau piézoélectrique deux fois plus faible, pour une fréquence de travail donnée, qu'avec les transducteurs classiques à couche piézoélectrique en λ/2 (cette dernière caractéristique est importante pour des polymères piézoélectriques tels que le polyfluorure de vinylidène cité plus haut, qui sont difficiles à obtenir en fortes épaisseurs).The essential characteristic of the structure with total symmetry (Figure 2) is very good damping. The advantages of the structure with virtual symmetry (figure 1) are the following: gain of 6 dB (maximum) on the sensitivity index of the structure with total symmetry, thanks to the effect of "acoustic mirror of the rigid rear center which reflects all the acoustic energy towards the front, maintaining the same damping as that, very satisfactory, of the structure with total symmetry, thickness of the piezoelectric material twice less, for a given working frequency, than with conventional transducers with a piezoelectric layer in λ / 2 (this last characteristic is important for piezoelectric polymers such as the polyvinylidene fluoride mentioned above, which are difficult to obtain in high thicknesses).

Bien entendu la présente invention n'est pas limitée aux exemples de réalisation décrits et représentés, à partir desquels des variantes peuvent être proposées sans pour cela sortir du cadre de l'invention, en particulier celles dans lesquelles on aurait choisi un nombre différent de couches d'adaptation d'impédance acoustique entre le matériau piézoélectrique et les milieux extrêmes.Of course the present invention is not limited to the embodiments described and shown, from which variants can be proposed without departing from the scope of the invention, in particular those in which a different number of layers would have been chosen. adaptation of acoustic impedance between the piezoelectric material and extreme environments.

Claims (2)

1. An ultrasonic transducer comprising a substrate (10) which constitutes a backing medium, a layer (20) of piezoelectric material, and one or more matching layers (30, 40) which are provided between the piezoelectric material and the propagation medium (50) in front, the impedance values of the layer of piezoelectric material, of the acoustic impedance matching layers, and of the propagation medium (50) in front forming a descending progression in this order, characterized in that the backing medium (10) has an acoustic impedance value which is sufficiently high with respect to that of the piezoelectric material (20) for the backing medium to be considered to be rigid, and in that the thickness of the layer (20) of piezoelectric material is equal to one quarter of the wavelength associated with the resonant frequency of the transducer.
2. An ultrasonic transducer comprising a substrate (10) which constitutes a backing medium, a layer (20) of piezoelectric material, and one or more matching layers (30, 40), the impedance values of the layer (20) of piezoelectric material, of the acoustic impedance matching layers, and of the propagation medium (50) in front forming a descending progression in this order, characterized in that an equal number of matching layers (30, 40) is provided on both sides of the piezoelectric material (20), the pair-wise symmetrically situated layers having the same acoustic impedance value and the same thickness, in that the backing medium (10) has an acoustic impedance value which is substantially equal to that of the propagation medium (50) in front, and in that the thickness of the layer (20) of piezoelectric material is equal to one half of the wavelength associated with the resonant frequency of the transducer, so that the structure is symmetrical with respect to the central plane of the layer of piezoelectric material.
EP84201200A 1983-08-31 1984-08-20 Ultrasonic transducer Expired - Lifetime EP0142178B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8313986A FR2551611B1 (en) 1983-08-31 1983-08-31 NOVEL ULTRASONIC TRANSDUCER STRUCTURE AND ULTRASONIC ECHOGRAPHY MEDIA EXAMINATION APPARATUS COMPRISING SUCH A STRUCTURE
FR8313986 1983-08-31

Publications (3)

Publication Number Publication Date
EP0142178A1 EP0142178A1 (en) 1985-05-22
EP0142178B1 true EP0142178B1 (en) 1990-01-03
EP0142178B2 EP0142178B2 (en) 1994-01-12

Family

ID=9291921

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84201200A Expired - Lifetime EP0142178B2 (en) 1983-08-31 1984-08-20 Ultrasonic transducer

Country Status (7)

Country Link
US (1) US4771205A (en)
EP (1) EP0142178B2 (en)
JP (1) JPH0640676B2 (en)
CA (1) CA1260603A (en)
DE (1) DE3480968D1 (en)
FR (1) FR2551611B1 (en)
IL (1) IL72791A (en)

Families Citing this family (115)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60100950A (en) * 1983-11-09 1985-06-04 松下電器産業株式会社 Ultrasonic probe
NL8501908A (en) * 1985-07-03 1987-02-02 Tno PROBE SENSOR.
US5119840A (en) * 1986-04-07 1992-06-09 Kaijo Kenki Co., Ltd. Ultrasonic oscillating device and ultrasonic washing apparatus using the same
EP0369127A3 (en) * 1988-09-29 1991-11-06 Siemens Aktiengesellschaft Compound ultrasonar sonar transducer
US5212671A (en) * 1989-06-22 1993-05-18 Terumo Kabushiki Kaisha Ultrasonic probe having backing material layer of uneven thickness
DE3920663A1 (en) * 1989-06-23 1991-01-10 Siemens Ag WIDE-RADIATION ULTRASONIC transducer
DE59010738D1 (en) * 1990-04-09 1997-08-21 Siemens Ag Frequency-selective ultrasound layer converter
US5187403A (en) * 1990-05-08 1993-02-16 Hewlett-Packard Company Acoustic image signal receiver providing for selectively activatable amounts of electrical signal delay
US5268610A (en) * 1991-12-30 1993-12-07 Xerox Corporation Acoustic ink printer
US5355048A (en) * 1993-07-21 1994-10-11 Fsi International, Inc. Megasonic transducer for cleaning substrate surfaces
US5777230A (en) * 1995-02-23 1998-07-07 Defelsko Corporation Delay line for an ultrasonic probe and method of using same
ES2183757T5 (en) † 1995-06-19 2009-07-06 Denso Corporation ELECTROMAGNETIC COIL.
US5706564A (en) * 1995-07-27 1998-01-13 General Electric Company Method for designing ultrasonic transducers using constraints on feasibility and transitional Butterworth-Thompson spectrum
US5648941A (en) * 1995-09-29 1997-07-15 Hewlett-Packard Company Transducer backing material
US6087198A (en) * 1998-02-12 2000-07-11 Texas Instruments Incorporated Low cost packaging for thin-film resonators and thin-film resonator-based filters
US6049159A (en) * 1997-10-06 2000-04-11 Albatros Technologies, Inc. Wideband acoustic transducer
US6050943A (en) 1997-10-14 2000-04-18 Guided Therapy Systems, Inc. Imaging, therapy, and temperature monitoring ultrasonic system
US5936150A (en) * 1998-04-13 1999-08-10 Rockwell Science Center, Llc Thin film resonant chemical sensor with resonant acoustic isolator
US6051913A (en) * 1998-10-28 2000-04-18 Hewlett-Packard Company Electroacoustic transducer and acoustic isolator for use therein
US6307302B1 (en) * 1999-07-23 2001-10-23 Measurement Specialities, Inc. Ultrasonic transducer having impedance matching layer
US6452310B1 (en) * 2000-01-18 2002-09-17 Texas Instruments Incorporated Thin film resonator and method
US6717335B2 (en) * 2000-11-27 2004-04-06 Murata Manufacturing Co., Ltd. Composite vibration device
US7914453B2 (en) 2000-12-28 2011-03-29 Ardent Sound, Inc. Visual imaging system for ultrasonic probe
US6936009B2 (en) * 2001-02-27 2005-08-30 General Electric Company Matching layer having gradient in impedance for ultrasound transducers
DE10124349A1 (en) * 2001-05-18 2002-12-05 Infineon Technologies Ag Piezoelectric resonator device with detuning layer sequence
DE10321701B4 (en) * 2002-05-24 2009-06-10 Murata Manufacturing Co., Ltd., Nagaokakyo Longitudinally coupled multi-mode piezoelectric bulk wave filter device, longitudinally coupled piezoelectric multi-mode bulk wave filter and electronic component
GB2391625A (en) 2002-08-09 2004-02-11 Diagnostic Ultrasound Europ B Instantaneous ultrasonic echo measurement of bladder urine volume with a limited number of ultrasound beams
US8221321B2 (en) 2002-06-07 2012-07-17 Verathon Inc. Systems and methods for quantification and classification of fluids in human cavities in ultrasound images
US20060006765A1 (en) * 2004-07-09 2006-01-12 Jongtae Yuk Apparatus and method to transmit and receive acoustic wave energy
US8221322B2 (en) 2002-06-07 2012-07-17 Verathon Inc. Systems and methods to improve clarity in ultrasound images
US7520857B2 (en) * 2002-06-07 2009-04-21 Verathon Inc. 3D ultrasound-based instrument for non-invasive measurement of amniotic fluid volume
US7819806B2 (en) 2002-06-07 2010-10-26 Verathon Inc. System and method to identify and measure organ wall boundaries
WO2004091812A2 (en) * 2003-04-15 2004-10-28 Koninklijke Philips Electronics N.V. Two-dimensional (2d) array capable of harmonic generation for ultrasound imaging
US7393325B2 (en) 2004-09-16 2008-07-01 Guided Therapy Systems, L.L.C. Method and system for ultrasound treatment with a multi-directional transducer
US7824348B2 (en) 2004-09-16 2010-11-02 Guided Therapy Systems, L.L.C. System and method for variable depth ultrasound treatment
US9011336B2 (en) * 2004-09-16 2015-04-21 Guided Therapy Systems, Llc Method and system for combined energy therapy profile
US8535228B2 (en) 2004-10-06 2013-09-17 Guided Therapy Systems, Llc Method and system for noninvasive face lifts and deep tissue tightening
US7530958B2 (en) * 2004-09-24 2009-05-12 Guided Therapy Systems, Inc. Method and system for combined ultrasound treatment
US10864385B2 (en) 2004-09-24 2020-12-15 Guided Therapy Systems, Llc Rejuvenating skin by heating tissue for cosmetic treatment of the face and body
US8444562B2 (en) 2004-10-06 2013-05-21 Guided Therapy Systems, Llc System and method for treating muscle, tendon, ligament and cartilage tissue
US8133180B2 (en) 2004-10-06 2012-03-13 Guided Therapy Systems, L.L.C. Method and system for treating cellulite
US11883688B2 (en) 2004-10-06 2024-01-30 Guided Therapy Systems, Llc Energy based fat reduction
US20060111744A1 (en) 2004-10-13 2006-05-25 Guided Therapy Systems, L.L.C. Method and system for treatment of sweat glands
US7530356B2 (en) * 2004-10-06 2009-05-12 Guided Therapy Systems, Inc. Method and system for noninvasive mastopexy
US8690778B2 (en) 2004-10-06 2014-04-08 Guided Therapy Systems, Llc Energy-based tissue tightening
US9694212B2 (en) 2004-10-06 2017-07-04 Guided Therapy Systems, Llc Method and system for ultrasound treatment of skin
DK1855759T3 (en) 2004-10-06 2017-06-06 Guided Therapy Systems Llc Tissue Ultrasound Treatment System
US11235179B2 (en) 2004-10-06 2022-02-01 Guided Therapy Systems, Llc Energy based skin gland treatment
US7758524B2 (en) 2004-10-06 2010-07-20 Guided Therapy Systems, L.L.C. Method and system for ultra-high frequency ultrasound treatment
US9827449B2 (en) 2004-10-06 2017-11-28 Guided Therapy Systems, L.L.C. Systems for treating skin laxity
CA2583600A1 (en) 2004-10-06 2006-04-20 Guided Therapy Systems, L.L.C. Method and system for noninvasive cosmetic enhancement
US11207548B2 (en) 2004-10-07 2021-12-28 Guided Therapy Systems, L.L.C. Ultrasound probe for treating skin laxity
US11724133B2 (en) 2004-10-07 2023-08-15 Guided Therapy Systems, Llc Ultrasound probe for treatment of skin
EP1875327A2 (en) 2005-04-25 2008-01-09 Guided Therapy Systems, L.L.C. Method and system for enhancing computer peripheral saftey
US9566454B2 (en) * 2006-09-18 2017-02-14 Guided Therapy Systems, Llc Method and sysem for non-ablative acne treatment and prevention
TWI526233B (en) 2007-05-07 2016-03-21 指導治療系統股份有限公司 Methods and systems for modulating medicants using acoustic energy
US20150174388A1 (en) 2007-05-07 2015-06-25 Guided Therapy Systems, Llc Methods and Systems for Ultrasound Assisted Delivery of a Medicant to Tissue
US8167803B2 (en) 2007-05-16 2012-05-01 Verathon Inc. System and method for bladder detection using harmonic imaging
US7804742B2 (en) * 2008-01-29 2010-09-28 Hyde Park Electronics Llc Ultrasonic transducer for a proximity sensor
US8456957B2 (en) * 2008-01-29 2013-06-04 Schneider Electric USA, Inc. Ultrasonic transducer for a proximity sensor
US8129886B2 (en) * 2008-02-29 2012-03-06 General Electric Company Apparatus and method for increasing sensitivity of ultrasound transducers
CN104545998B (en) 2008-06-06 2020-07-14 奥赛拉公司 System and method for cosmetic treatment and imaging
JP5658151B2 (en) 2008-08-07 2015-01-21 ベラソン インコーポレイテッドＶｅｒａｔｈｏｎ Ｉｎｃ． Apparatus, system and method for measuring the diameter of an abdominal aortic aneurysm
KR20110101204A (en) 2008-12-24 2011-09-15 가이디드 테라피 시스템스, 엘.엘.씨. Methods and systems for fat reduction and/or cellulite treatment
US9068775B2 (en) 2009-02-09 2015-06-30 Heat Technologies, Inc. Ultrasonic drying system and method
US8264126B2 (en) 2009-09-01 2012-09-11 Measurement Specialties, Inc. Multilayer acoustic impedance converter for ultrasonic transducers
US8715186B2 (en) 2009-11-24 2014-05-06 Guided Therapy Systems, Llc Methods and systems for generating thermal bubbles for improved ultrasound imaging and therapy
KR101173277B1 (en) * 2010-03-15 2012-08-13 주식회사 휴먼스캔 Ultrasound probe using rear acoustic matching layer
US9504446B2 (en) 2010-08-02 2016-11-29 Guided Therapy Systems, Llc Systems and methods for coupling an ultrasound source to tissue
US10183182B2 (en) 2010-08-02 2019-01-22 Guided Therapy Systems, Llc Methods and systems for treating plantar fascia
US8857438B2 (en) 2010-11-08 2014-10-14 Ulthera, Inc. Devices and methods for acoustic shielding
US8858471B2 (en) 2011-07-10 2014-10-14 Guided Therapy Systems, Llc Methods and systems for ultrasound treatment
KR20190080967A (en) 2011-07-11 2019-07-08 가이디드 테라피 시스템스, 엘.엘.씨. Systems and methods for coupling an ultrasound source to tissue
US9263663B2 (en) 2012-04-13 2016-02-16 Ardent Sound, Inc. Method of making thick film transducer arrays
US9510802B2 (en) 2012-09-21 2016-12-06 Guided Therapy Systems, Llc Reflective ultrasound technology for dermatological treatments
EP2775730A1 (en) 2013-03-05 2014-09-10 British Telecommunications public limited company Video data provision
EP2775731A1 (en) 2013-03-05 2014-09-10 British Telecommunications public limited company Provision of video data
CN204637350U (en) 2013-03-08 2015-09-16 奥赛拉公司 Aesthstic imaging and processing system, multifocal processing system and perform the system of aesthetic procedure
US10561862B2 (en) 2013-03-15 2020-02-18 Guided Therapy Systems, Llc Ultrasound treatment device and methods of use
GB2513884B (en) 2013-05-08 2015-06-17 Univ Bristol Method and apparatus for producing an acoustic field
EP2819418A1 (en) 2013-06-27 2014-12-31 British Telecommunications public limited company Provision of video data
US9612658B2 (en) 2014-01-07 2017-04-04 Ultrahaptics Ip Ltd Method and apparatus for providing tactile sensations
SG11201608691YA (en) 2014-04-18 2016-11-29 Ulthera Inc Band transducer ultrasound therapy
GB2530036A (en) 2014-09-09 2016-03-16 Ultrahaptics Ltd Method and apparatus for modulating haptic feedback
JP2016086956A (en) * 2014-10-31 2016-05-23 セイコーエプソン株式会社 Ultrasonic probe, electronic apparatus, and ultrasonogram device
ES2908299T3 (en) 2015-02-20 2022-04-28 Ultrahaptics Ip Ltd Algorithm improvements in a haptic system
AU2016221500B2 (en) 2015-02-20 2021-06-10 Ultrahaptics Ip Limited Perceptions in a haptic system
WO2016138622A1 (en) * 2015-03-02 2016-09-09 深圳市理邦精密仪器股份有限公司 Ultrasonic transducer and manufacturing method thereof
WO2016183243A1 (en) 2015-05-11 2016-11-17 Measurement Specialties, Inc. Impedance matching layer for ultrasonic transducers with metallic protection structure
US10818162B2 (en) 2015-07-16 2020-10-27 Ultrahaptics Ip Ltd Calibration techniques in haptic systems
US11189140B2 (en) 2016-01-05 2021-11-30 Ultrahaptics Ip Ltd Calibration and detection techniques in haptic systems
AU2017208980B2 (en) 2016-01-18 2022-03-31 Ulthera, Inc. Compact ultrasound device having annular ultrasound array peripherally electrically connected to flexible printed circuit board and method of assembly thereof
US10531212B2 (en) 2016-06-17 2020-01-07 Ultrahaptics Ip Ltd. Acoustic transducers in haptic systems
US10268275B2 (en) 2016-08-03 2019-04-23 Ultrahaptics Ip Ltd Three-dimensional perceptions in haptic systems
US10755538B2 (en) 2016-08-09 2020-08-25 Ultrahaptics ilP LTD Metamaterials and acoustic lenses in haptic systems
KR102593310B1 (en) 2016-08-16 2023-10-25 얼테라, 인크 Ultrasound imaging system configured to reduce imaging misalignment, ultrasound imaging module, and method for reducing imaging misalignment
US10943578B2 (en) 2016-12-13 2021-03-09 Ultrahaptics Ip Ltd Driving techniques for phased-array systems
US10497358B2 (en) 2016-12-23 2019-12-03 Ultrahaptics Ip Ltd Transducer driver
EP3384849B1 (en) 2017-04-07 2022-06-08 Esaote S.p.A. Ultrasound probe with acoustic amplifier
US11531395B2 (en) 2017-11-26 2022-12-20 Ultrahaptics Ip Ltd Haptic effects from focused acoustic fields
JP7029588B2 (en) * 2017-12-06 2022-03-04 パナソニックＩｐマネジメント株式会社 Ultrasonic sensor
EP3729417A1 (en) 2017-12-22 2020-10-28 Ultrahaptics Ip Ltd Tracking in haptic systems
JP2021508423A (en) 2017-12-22 2021-03-04 ウルトラハプティクス アイピー リミテッドＵｌｔｒａｈａｐｔｉｃｓ Ｉｐ Ｌｔｄ Minimize unwanted responses in haptic systems
US11944849B2 (en) 2018-02-20 2024-04-02 Ulthera, Inc. Systems and methods for combined cosmetic treatment of cellulite with ultrasound
JP7354146B2 (en) 2018-05-02 2023-10-02 ウルトラハプティクス アイピー リミテッド Barrier plate structure for improved sound transmission efficiency
US11098951B2 (en) 2018-09-09 2021-08-24 Ultrahaptics Ip Ltd Ultrasonic-assisted liquid manipulation
US11378997B2 (en) 2018-10-12 2022-07-05 Ultrahaptics Ip Ltd Variable phase and frequency pulse-width modulation technique
US11550395B2 (en) 2019-01-04 2023-01-10 Ultrahaptics Ip Ltd Mid-air haptic textures
US11842517B2 (en) 2019-04-12 2023-12-12 Ultrahaptics Ip Ltd Using iterative 3D-model fitting for domain adaptation of a hand-pose-estimation neural network
US11374586B2 (en) 2019-10-13 2022-06-28 Ultraleap Limited Reducing harmonic distortion by dithering
CA3154040A1 (en) 2019-10-13 2021-04-22 Benjamin John Oliver LONG Dynamic capping with virtual microphones
WO2021090028A1 (en) 2019-11-08 2021-05-14 Ultraleap Limited Tracking techniques in haptics systems
US11715453B2 (en) 2019-12-25 2023-08-01 Ultraleap Limited Acoustic transducer structures
US11816267B2 (en) 2020-06-23 2023-11-14 Ultraleap Limited Features of airborne ultrasonic fields
WO2022058738A1 (en) 2020-09-17 2022-03-24 Ultraleap Limited Ultrahapticons

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2427348A (en) * 1941-08-19 1947-09-16 Bell Telephone Labor Inc Piezoelectric vibrator
US3946149A (en) * 1974-10-24 1976-03-23 Cbs Inc. Apparatus for embossing information on a disc
AT353506B (en) * 1976-10-19 1979-11-26 List Hans PIEZOELECTRIC RESONATOR
US4096756A (en) * 1977-07-05 1978-06-27 Rca Corporation Variable acoustic wave energy transfer-characteristic control device
JPS54131380A (en) * 1978-03-31 1979-10-12 Hitachi Medical Corp Dumbbell type ultrasonic wave detecting contacting piece
US4211948A (en) * 1978-11-08 1980-07-08 General Electric Company Front surface matched piezoelectric ultrasonic transducer array with wide field of view
EP0015886A1 (en) * 1979-03-13 1980-09-17 Toray Industries, Inc. An improved electro-acoustic transducer element
US4383194A (en) * 1979-05-01 1983-05-10 Toray Industries, Inc. Electro-acoustic transducer element
US4297607A (en) * 1980-04-25 1981-10-27 Panametrics, Inc. Sealed, matched piezoelectric transducer
US4434384A (en) * 1980-12-08 1984-02-28 Raytheon Company Ultrasonic transducer and its method of manufacture
JPS57170708U (en) * 1981-04-20 1982-10-27
JPS5817358A (en) * 1981-07-23 1983-02-01 Toshiba Corp Ultrasonic probe
US4507582A (en) * 1982-09-29 1985-03-26 New York Institute Of Technology Matching region for damped piezoelectric ultrasonic apparatus
JPS59166139A (en) * 1983-03-10 1984-09-19 富士通株式会社 Ultrasonic transducer

Also Published As

Publication number Publication date
US4771205A (en) 1988-09-13
FR2551611A1 (en) 1985-03-08
IL72791A (en) 1988-08-31
CA1260603A (en) 1989-09-26
IL72791A0 (en) 1984-11-30
FR2551611B1 (en) 1986-10-24
EP0142178A1 (en) 1985-05-22
JPH0640676B2 (en) 1994-05-25
EP0142178B2 (en) 1994-01-12
JPS6084099A (en) 1985-05-13
DE3480968D1 (en) 1990-02-08

Similar Documents

Publication Publication Date Title
EP0142178B1 (en) Ultrasonic transducer
EP0769988B1 (en) Wide-band multifrequency acoustic transducer
FR2484735A1 (en) SURFACE ACOUSTIC WAVE RESONATOR
EP1053593B1 (en) Filter with surface acoustic wave resonators
EP0513085B2 (en) Surface acoustic wave filter
FR2635247A1 (en) PIEZOELECTRIC TRANSDUCER FOR GENERATING VOLUME WAVES
FR2601824A1 (en) SURFACE ELASTIC WAVE FILTER
EP0998037A1 (en) Low loss surface acoustic wave filter on a cut-optimised substrate
WO2005071375A1 (en) Remotely testable temperature sensor
FR2811828A1 (en) SOUND WAVE DEVICE COMPRISING ALTERNATE POLARIZATION AREAS
WO2023047042A1 (en) Surface-acoustic-wave filter employing resonant cavities
EP0162515A1 (en) Ultrasonic transducer devices using an array of piezoelectric transducer elements
EP0660981B1 (en) Unidirectional wave transducer
EP0040559A1 (en) Piezoelectric convolution device using elastic waves
EP0375570B1 (en) Vibration absorption device comprising a piezoelectric element
CA2748383A1 (en) Acoustic wave transducer and sonar antenna with improved directivity
EP0982859B1 (en) Acoustic filter with two different channels and rejection compensation
EP3034183B1 (en) Acoustic device for galvanic isolation
EP0424240B1 (en) Unidirectional surface wave transducer
FR2998420A1 (en) ELASTIC SURFACE WAVE TRANSDUCER SPRAYING ON LITHIUM NIOBATE SUBSTRATE OR LITHIUM TANTALATE.
FR2546703A1 (en) Novel ultrasound transducer structure
WO2023222282A1 (en) Surface acoustic wave device incorporating a thin layer of metal material
FR2479608A1 (en) SURFACE ACOUSTIC WAVE DEVICE AND PRODUCTION METHOD
WO2023247639A1 (en) Ultrasonic transducer for high-temperature application
FR2818051A1 (en) OPTIMIZED SYMMETRY SURFACE ACOUSTIC WAVE FLITERS

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): DE FR GB SE

17P Request for examination filed

Effective date: 19851121

17Q First examination report despatched

Effective date: 19870305

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB SE

RAP2 Party data changed (patent owner data changed or rights of a patent transferred)

Owner name: N.V. PHILIPS' GLOEILAMPENFABRIEKEN

Owner name: LABORATOIRES D'ELECTRONIQUE PHILIPS

REF Corresponds to:

Ref document number: 3480968

Country of ref document: DE

Date of ref document: 19900208

GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)
PLBI Opposition filed

Free format text: ORIGINAL CODE: 0009260

26 Opposition filed

Opponent name: SIEMENS AKTIENGESELLSCHAFT, BERLIN UND MUENCHEN

Effective date: 19901002

PUAH Patent maintained in amended form

Free format text: ORIGINAL CODE: 0009272

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: PATENT MAINTAINED AS AMENDED

27A Patent maintained in amended form

Effective date: 19940112

AK Designated contracting states

Kind code of ref document: B2

Designated state(s): DE FR GB SE

GBTA Gb: translation of amended ep patent filed (gb section 77(6)(b)/1977)

Effective date: 19940323

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19940728

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19940825

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19940826

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19941026

Year of fee payment: 11

EAL Se: european patent in force in sweden

Ref document number: 84201200.7

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19950820

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19950821

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19950820

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Effective date: 19960430

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19960501

EUG Se: european patent has lapsed

Ref document number: 84201200.7

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST