EP0118837B1 - Ultrasonic transducer - Google Patents

Ultrasonic transducer Download PDF

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Publication number
EP0118837B1
EP0118837B1 EP84102147A EP84102147A EP0118837B1 EP 0118837 B1 EP0118837 B1 EP 0118837B1 EP 84102147 A EP84102147 A EP 84102147A EP 84102147 A EP84102147 A EP 84102147A EP 0118837 B1 EP0118837 B1 EP 0118837B1
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European Patent Office
Prior art keywords
layer
ultrasonic transducer
receiving layer
plastics material
transducer according
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German (de)
French (fr)
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EP0118837A2 (en
EP0118837A3 (en
Inventor
Reinhard Dr. Lerch
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Siemens AG
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Siemens AG
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    • GPHYSICS
    • G10MUSICAL INSTRUMENTS; ACOUSTICS
    • G10KSOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00Methods 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
    • G10K11/02Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators

Definitions

  • the invention relates to an ultrasonic transducer with a support body, a transmission layer made of a material with a relatively high dielectric constant and a first X / 4 adaptation layer, which faces the transmission layer, and a second ⁇ / 4 adaptation layer, which faces a load .
  • Ultrasonic broadband converters are used in medical ultrasound diagnostics and non-destructive material testing.
  • the medical application where a coupling between tissue and sound transducer must be carried out with the lowest possible losses, requires an improvement in the electromechanical and acoustic properties of these transducer systems.
  • An ultrasonic transducer is known, the keymetric transducer of which is adapted to a load medium, tissue or water, by means of two X / 4 adaptation layers.
  • This transducer system contains an epoxy resin backing with an acoustic impedance of 3 x 10 6 Pas / m, a ceramic transducer, a first ⁇ / 4 matching layer made of glass with an acoustic impedance of 10 x 10 6 Pas / m and a second X / 4 Matching layer made of polyacrylic or epoxy resin with an acoustic impedance of 3 x 10 6 Pas / m.
  • the ceramic converter is arranged on a backing.
  • the glass plate as the first adaptation layer is made with an adhesive adhesive of very low viscosity, so that adhesive layers are in the range of approximately 2 ⁇ m.
  • the epoxy resin as a second adaptation layer is poured directly onto the first adaptation layer (experimental studies on the construction of ultrasound broadband transducers, biomedical engineering, volume 27, issues 7 to 8, 1982, pages 182 to 185).
  • This double ⁇ / 4 adaptation only improves the sensitivity and the bandwidth of the ceramic transmission layer.
  • the bandwidth of this ultrasonic transducer is approximately 60 to 70% of the center frequency.
  • an ultrasonic transducer which has a transmission layer made of a material with a relatively high dielectric constant and high sound impedance and a reception layer made of a material with a relatively low dielectric constant and low sound impedance, which are connected flatly in hybrid technology.
  • the transmission layer consists, for example, of lead zirconate titanate PZT or lead metanobate Pb (N0 3 ).
  • the receiving layer consists of a piezoelectric plastic film with an acoustic impedance of approximately 3 x 10 6 Pas / m, for example polyvinylidene fluoride PVDF or polycarbonate or polyvinyl chloride PVC.
  • the receiving layer should also be an adaptation layer for the transmission case (German patent specification 2914 031).
  • the formation of the receiving layer as an adaptation layer for adaptation to body tissue can, however, only be designed as a simple X / 4 layer.
  • the adaptation layer for the transmission case is not a simple X / 4 adaptation.
  • the theory results in an adaptation layer with an acoustic impedance of approximately 7 x 10 6 Pas / m.
  • the invention is based on the object of specifying an ultrasonic transducer with an effective broadband transmitter and a sensitive and broadband receiver.
  • the ceramic vibrating material of the transmission layer is to be broadband adapted to tissue or water.
  • the receiving layer consists of a stack of thin piezoelectric plastic films that are electrically connected in series. This design of the receiving layer makes it easier to polarize the individual piezoelectric plastic films due to the small thickness.
  • the receiving layer consists of an active and a passive piezoelectric plastic film, the active piezoelectric plastic film being arranged on the first matching layer and the passive piezoelectric plastic film facing the load.
  • the thickness of the passive piezoelectric plastic film is a multiple of the thickness of the active piezoelectric plastic film.
  • an ultrasound transducer contains a support body 2, a transmission layer 4 and two X / 4 adaptation layers, the second X / 4 adaptation layer being simultaneously provided as a reception layer 6.
  • the first ⁇ / 4 adaptation layer 8 faces the transmission layer 4 and at the same time is provided as backing for the reception layer 6. All layers can preferably be connected to one another over a large area in hybrid technology.
  • the thicknesses of the matching layers are each a quarter wavelength at a predetermined resonance frequency. With a resonance frequency of approximately 10 MHz, the thickness of the matching layers is, for example, 55 ⁇ m and with a resonance frequency of approximately 2 MHz for example 275 ⁇ m.
  • a material with a relatively high dielectric constant and high sound impedance for example a piezoceramic material, serves as the transmission layer 4.
  • the two matching layers have the task of matching different acoustic impedances to each other with little reflection.
  • the transmitting layer made of lead-zirconate-titanate PZT with an acoustic impedance of approximately 30 x 10 6 Pas / m to a load, for example tissue or water with an acoustic impedance of 1.5x10 8 Pas / m.
  • multi-stage transformation with two X / 4 adjustment layers is known from the theory, in which a permissible input reflection factor is approximated according to the Chebyshev curve.
  • the material for the first adaptation layer 8 can be, for example, porcelain, preferably quartz glass, in particular a glass-like material (Macor), and for the second adaptation layer one can use, for example, polyvinyl chloride PVC, in particular polyvinylidene fluoride PVDF.
  • the polyvinylidene fluoride PVDF layer must be polarized and provided with electrical connections which, like the electrical connections of the transmission layer, are not shown in FIG. 1.
  • This design provides a broadband and sensitive ultrasound transducer, which is used in medicine in particular because of its almost low-reflection coupling between tissue and ultrasound transducer.
  • the receiving layer 6 consists of a stack of thin piezoelectric plastic films 10 which are electrically connected in series. These piezoelectric plastic films 10 are each polarized in the same direction, and the thickness of the stack is a quarter wavelength at a predetermined resonance frequency. Up to a frequency of, for example, 4 MHz, the stack can expediently consist of, for example, 25 ⁇ m thick plastic films 10, while for higher frequencies the stack can be constructed of, for example, 9 ⁇ m thick plastic films 10.
  • polyvinyl chloride PVC in particular polyvinylidene fluoride PVDF, can be used as the material for the piezoelectric plastic films of the receiving layer 6.
  • This configuration of the receiving layer 6 allows the thin, for example 9 ⁇ m to 25 ⁇ m thick, piezoelectric plastic films to be polarized very well.
  • the receiving layer 6 consists of an active piezoelectric plastic film 12 and a thicker, passive piezoelectric plastic film 14.
  • the thickness of the passive piezoelectric plastic film 14 of the receiving layer 6 is a multiple, for example 2 to 15 times, the thickness of the active one piezoelectric plastic film 12 of the receiving layer 6.
  • the active piezoelectric plastic film 12, which is for example 25 ⁇ m thick, is arranged on the first X / 4 matching layer 8, and the passive piezoelectric plastic film 14 faces the load.
  • the material used for the piezoelectric plastic films of the receiving layer 6 is, for example, polyvinyl chloride PVC, in particular polyvinylidene fluoride PVDF. Both the active and the passive piezoelectric plastic film 12 or 14 consist of the same material, the active piezoelectric plastic film 12 being polarized.
  • This configuration of the receiving layer 6 results in a broadband and sensitive ultrasound transducer with a relatively large capacitance and a correspondingly low internal impedance with relatively small spatial dimensions.

Abstract

1. An ultrasonic transducer having a supporting body (2), a transmitting layer (4) of a material with a relatively high dielectric constant and high acoustic impedance and a first lambda/4 coupling layer (8) that faces the transmitting layer (4), and a second lambda/4 coupling layer that faces a load, characterised in that the second lambda/4 coupling layer also serves as a receiving layer (6) and that the first lambda/4 coupling layer (8) also serves as backing for the receiving layer (6).

Description

Die Erfindung bezieht sich auf einen Ultraschallwandler mit einem Tragkörper, einer Sendeschicht aus einem Material mit verhältnismäßig hoher dielektrischer Konstante und einer ersten X/4-Anpassungsschicht, die der Sendeschicht zugewandt ist, sowie einer zweiten λ/4-Anpassungsschicht, die einer Last zugewandt ist.The invention relates to an ultrasonic transducer with a support body, a transmission layer made of a material with a relatively high dielectric constant and a first X / 4 adaptation layer, which faces the transmission layer, and a second λ / 4 adaptation layer, which faces a load .

In der medizinischen Ultraschalldiagnostik und der zerstörungsfreien Werkstoffprüfung werden Ultraschallbreitbandwandler eingesetzt. Insbesondere die medizinische Anwendung, wo mit möglichst geringen Verlusten eine Kopplung zwischen Gewebe und Schallwandler vorgenommen werden muß, erfordert eine Verbesserung der elektromechanischen und akustischen Eigenschaften dieser Wandlersysteme.Ultrasonic broadband converters are used in medical ultrasound diagnostics and non-destructive material testing. In particular, the medical application, where a coupling between tissue and sound transducer must be carried out with the lowest possible losses, requires an improvement in the electromechanical and acoustic properties of these transducer systems.

Es ist ein Ultraschallwandler bekannt, dessen Ke- .ramikwandler durch zwei X/4-Anpassungsschichten an ein Lastmedium Gewebe oder Wasser angepaßt wird. Dieses Wandlersystem enthält ein Backing aus Epoxidharz mit einer akustischen Impedanz von 3 x 106 Pas/m, einen Keramikwandler, eine erste λ/ 4-Anpassungsschicht aus Glas mit einer akustischen Impedanz von 10 x 106 Pas/m und eine zweite X/4-Anpassungsschicht aus Polyacryl oder aus Epoxidharz mit einer akustischen Impedanz von 3 x 106 Pas/m. Der Keramikwandler ist auf einem Backing angeordnet. Die Glasplatte als erste Anpassungsschicht ist mit einem Adhäsionskleber sehr niedriger Viskosität vorgenommen, so daß Klebeschichten im Bereich von etwa 2 µm vorliegen. Das Epoxidharz als zweite Anpassungsschicht ist direkt auf die erste Anpassungsschicht aufgegossen (Experimentelle Untersuchungen zum Aufbau von Ultraschallbreitbandwandlern, Biomedizinische Technik, Band 27, Heft 7 bis 8, 1982, Seiten 182 bis 185). Durch diese doppelte λ/4-Anpassung erreicht man nur eine Verbesserung der Empfindlichkeit und der Bandbreite der Keramiksendeschicht. Die Bandbreite dieses Ultraschallwandlers beträgt etwa 60 bis 70% der Mittenfrequenz.An ultrasonic transducer is known, the keymetric transducer of which is adapted to a load medium, tissue or water, by means of two X / 4 adaptation layers. This transducer system contains an epoxy resin backing with an acoustic impedance of 3 x 10 6 Pas / m, a ceramic transducer, a first λ / 4 matching layer made of glass with an acoustic impedance of 10 x 10 6 Pas / m and a second X / 4 Matching layer made of polyacrylic or epoxy resin with an acoustic impedance of 3 x 10 6 Pas / m. The ceramic converter is arranged on a backing. The glass plate as the first adaptation layer is made with an adhesive adhesive of very low viscosity, so that adhesive layers are in the range of approximately 2 μm. The epoxy resin as a second adaptation layer is poured directly onto the first adaptation layer (experimental studies on the construction of ultrasound broadband transducers, biomedical engineering, volume 27, issues 7 to 8, 1982, pages 182 to 185). This double λ / 4 adaptation only improves the sensitivity and the bandwidth of the ceramic transmission layer. The bandwidth of this ultrasonic transducer is approximately 60 to 70% of the center frequency.

Außerdem ist ein Ultraschallwandler bekannt, der eine Sendeschicht aus einem Material mit verhältnismäßig hoher dielektrischer Konstante und hoher Schallimpedanz und einer Empfangsschicht aus einem Material mit verhältnismäßig niedriger dielektrischer Konstante und niedriger Schallimpedanz, die in Hybridtechnik flächig aufeinanderliegend verbunden sind. Die Sendeschicht besteht beispielsweise aus Blei-Zirkonat-Titanat PZT oder Bleimetaniobat Pb(N03). Die Empfangsschicht besteht demgegenüber aus einer piezoelektrischen Kunststoffolie mit einer akustischen Impedanz von etwa 3 x 106 Pas/m beispielsweise Polyvinyliden-Fluorid PVDF oder Polycarbonat oder Polyvinylchlorid PVC. Die Empfangsschicht soll zugleich Anpassungsschicht für den Sendefall sein (deutsche Patentschrift 2914 031). Die Ausbildung der Empfangsschicht als Anpassungsschicht zur Anpassung an Köpergewebe kann aber nur als einfache X/4-Schicht ausgebildet sein. Die Anpassungsschicht für den Sendefall ist jedoch hier keine einfache X/4-Anpassung. Bei einfacher X/4-Anpassung ergibt sich aus der Theorie eine Anpassungsschicht mit einer akustischen Impedanz von etwa 7 x 106 Pas/m.In addition, an ultrasonic transducer is known which has a transmission layer made of a material with a relatively high dielectric constant and high sound impedance and a reception layer made of a material with a relatively low dielectric constant and low sound impedance, which are connected flatly in hybrid technology. The transmission layer consists, for example, of lead zirconate titanate PZT or lead metanobate Pb (N0 3 ). In contrast, the receiving layer consists of a piezoelectric plastic film with an acoustic impedance of approximately 3 x 10 6 Pas / m, for example polyvinylidene fluoride PVDF or polycarbonate or polyvinyl chloride PVC. The receiving layer should also be an adaptation layer for the transmission case (German patent specification 2914 031). The formation of the receiving layer as an adaptation layer for adaptation to body tissue can, however, only be designed as a simple X / 4 layer. However, the adaptation layer for the transmission case is not a simple X / 4 adaptation. With a simple X / 4 adaptation, the theory results in an adaptation layer with an acoustic impedance of approximately 7 x 10 6 Pas / m.

Der Erfindung liegt nun die Aufgabe zugrunde, einen Ultraschallwandler mit einem effektiven breitbandigen Sender und einem empfindlichen und breitbandigen Empfänger anzugeben. Außerdem soll das keramische Schwingermaterial der Sendeschicht breitbandig an Gewebe oder Wasser angepaßt werden.The invention is based on the object of specifying an ultrasonic transducer with an effective broadband transmitter and a sensitive and broadband receiver. In addition, the ceramic vibrating material of the transmission layer is to be broadband adapted to tissue or water.

Diese Aufgabe wird erfindungsgemäß gelöst mit den kennzeichnenden Merkmalen des Anspruchs 1. Dadurch, daß die zweite X/4-Anpassungsschicht zugleich als Empfangsschicht und die erste λ/4-Anpassungsschicht zugleich als Backing für die Empfangsschicht vorgesehen ist, erhält man einen Ultraschallwandler, dessen Sendeschicht reflexionsarm an eine Last angepaßt ist und dessen Empfangsschicht außergewöhnlich empfindlich und breitbandig ist.This object is achieved according to the invention with the characterizing features of claim 1. Because the second X / 4 adaptation layer is simultaneously provided as a receiving layer and the first λ / 4 adaptation layer is also provided as a backing for the receiving layer, an ultrasound transducer whose transmission layer is obtained is adapted to a load with little reflection and its receiving layer is exceptionally sensitive and broadband.

Bei einer besonders vorteilhaften Ausführungsform des Ultraschallwandlers besteht die Empfangsschicht aus einem Stapel dünner elektrisch in Serie geschalteter piezoelektrischer Kunststoffolien. Durch diese Gestaltung der Empfangsschicht kann man die einzelnen piezoelektrischen Kunststoffolien aufgrund der geringen Dicke einfacher polarisieren.In a particularly advantageous embodiment of the ultrasound transducer, the receiving layer consists of a stack of thin piezoelectric plastic films that are electrically connected in series. This design of the receiving layer makes it easier to polarize the individual piezoelectric plastic films due to the small thickness.

In einer weiteren vorteilhaften Ausführungsform des Ultraschallwandlers besteht die Empfangsschicht aus einer aktiven und einer passiven piezoelektrischen Kunststoffolie, wobei die aktive piezoelektrische Kunststoffolie auf der ersten Anpassungsschicht angeordnet ist und die passive piezoelektrische Kunststoffolie der Last zugewandt ist. Die Dicke der passiven piezoelektrischen Kunststoffolie beträgt ein Vielfaches der Dicke der aktiven piezoelektrischen Kunststoffolie. Durch die Gestaltung der Empfangsschicht erhält man einen breitbandigen, empfindlichen Ultraschallwandler mit verhältnismäßig großer Kapazität und entsprechend geringer Innenimpedanz.In a further advantageous embodiment of the ultrasonic transducer, the receiving layer consists of an active and a passive piezoelectric plastic film, the active piezoelectric plastic film being arranged on the first matching layer and the passive piezoelectric plastic film facing the load. The thickness of the passive piezoelectric plastic film is a multiple of the thickness of the active piezoelectric plastic film. The design of the receiving layer gives a broadband, sensitive ultrasonic transducer with a relatively large capacity and a correspondingly low internal impedance.

Zur weiteren Erläuterung wird auf die Zeichnung Bezug genommen, in der ein Ausführungsbeispiel eines Ultraschallwandlers nach der Erfindung schematisch veranschaulicht ist.

  • Fig. 1 zeigt einen Ultraschallwandler gemäß der Erfindung, und in
  • Fig. 2 ist eine vorteilhafte Ausführungsform der Erfindung dargestellt.
  • Fig. 3 veranschaulicht eine weitere Ausführungsform der Erfindung.
For further explanation, reference is made to the drawing, in which an embodiment of an ultrasonic transducer according to the invention is schematically illustrated.
  • Fig. 1 shows an ultrasonic transducer according to the invention, and in
  • 2 shows an advantageous embodiment of the invention.
  • Figure 3 illustrates another embodiment of the invention.

In der Ausführungsform nach Fig. 1 enthält ein Ultraschallwandler einen Tragkörper 2, eine Sendeschicht 4 und zwei X/4-Anpassungsschichten, wobei die zweite X/4-Anpassungsschicht zugleich als Empfangsschicht 6 vorgesehen ist. Die erste λ/4-Anpassungsschicht 8 ist der Sendeschicht 4 zugewandt und zugleich als Backing für die Empfangsschicht 6 vorgesehen. Sämtliche Schichten können vorzugsweise großflächig in Hybridtechnik miteinander verbunden sein. Die Dicken der Anpassungsschichten betragen jeweils bei einer vorbestimmten Resonanzfrequenz eine Viertelwellenlänge. Bei einer Resonanzfrequenz von etwa 10 MHz beträgt die Dicke der Anpassungsschichten beispielsweise 55 µm und bei einer Resonanzfrequenz von etwa 2 MHz beispielsweise 275 µm. Als Sendeschicht 4 dient ein Material mit relativ hoher dielektrischer Konstante und hoher Schallimpedanz, beispielsweise ein Piezokeramik-Material. Zu bevorzugen ist hierbei eine Sendeschicht 4 aus Blei-Zirkonat-Titanat PZT oder Bleimetaniobat Pb(NO3).In the embodiment according to FIG. 1, an ultrasound transducer contains a support body 2, a transmission layer 4 and two X / 4 adaptation layers, the second X / 4 adaptation layer being simultaneously provided as a reception layer 6. The first λ / 4 adaptation layer 8 faces the transmission layer 4 and at the same time is provided as backing for the reception layer 6. All layers can preferably be connected to one another over a large area in hybrid technology. The thicknesses of the matching layers are each a quarter wavelength at a predetermined resonance frequency. With a resonance frequency of approximately 10 MHz, the thickness of the matching layers is, for example, 55 μm and with a resonance frequency of approximately 2 MHz for example 275 µm. A material with a relatively high dielectric constant and high sound impedance, for example a piezoceramic material, serves as the transmission layer 4. A transmission layer 4 made of lead zirconate titanate PZT or lead metaniobate Pb (NO 3 ) is preferred.

Die beiden Anpassungsschichten haben die Aufgabe, unterschiedliche akustische Impedanzen reflexionsarm aneinander anzupassen. Hier muß man die Sendeschicht aus Blei-Zirkonat-Titanat PZT mit einer akustischen Impedanz von ungefähr 30 x 106 Pas/m einer Last, beispielsweise Gewebe oder Wasser mit einer akustischen Impedanz von 1,5x108 Pas/m, anpassen. Um eine optimale reflektionsarme Anpassung zu erreichen, ist aus der Theorie die mehrstufige Transformation mit zwei X/4-Anpassungsschichten bekannt, bei der ein zulässiger Eingangsreflexionsfaktor nach dem Tschebyscheff-Verlauf approximiert wird. Hieraus ergibt sich für die erste X/4-Anpassungsschicht 8 eine akustische Impedanz von etwa 14 x 10° Pas/m und für die zweite λ/4-Anpassungsschicht eine akustische Impedanz von etwa 4x 106 Pas/m. Als Material für die erste Anpassungsschicht 8 kann man beispielsweise Porzellan, vorzugsweise Quarzglas, insbesondere einen glasartigen Stoff (Macor), und für die zweite Anpassungsschicht kann man beispielweise Polyvinylchlorid PVC, insbesondere Polyvinyliden-Fluorid PVDF, verwenden.The two matching layers have the task of matching different acoustic impedances to each other with little reflection. Here you have to adapt the transmitting layer made of lead-zirconate-titanate PZT with an acoustic impedance of approximately 30 x 10 6 Pas / m to a load, for example tissue or water with an acoustic impedance of 1.5x10 8 Pas / m. In order to achieve an optimal low-reflection adjustment, multi-stage transformation with two X / 4 adjustment layers is known from the theory, in which a permissible input reflection factor is approximated according to the Chebyshev curve. This results in an acoustic impedance of approximately 14 × 10 ° Pas / m for the first X / 4 matching layer 8 and an acoustic impedance of approximately 4x 106 Pas / m for the second λ / 4 matching layer. The material for the first adaptation layer 8 can be, for example, porcelain, preferably quartz glass, in particular a glass-like material (Macor), and for the second adaptation layer one can use, for example, polyvinyl chloride PVC, in particular polyvinylidene fluoride PVDF.

Damit die zweite Anpassungsschicht zugleich als Empfangsschicht 6 dient, muß man die Polyvinyliden-Fluorid PVDF-Schicht polarisieren und mit elektrischen Anschlüssen versehen, die wie die elektrischen Anschlüsse der Sendeschicht in der Fig. 1 nicht dargestellt sind.So that the second adaptation layer also serves as the receiving layer 6, the polyvinylidene fluoride PVDF layer must be polarized and provided with electrical connections which, like the electrical connections of the transmission layer, are not shown in FIG. 1.

Durch diese Gestaltung erhält man einen breitbandigen und empfindlichen Ultraschallwandler, der insbesondere wegen seiner annähernd reflexionsarmen Kopplung zwischen Gewebe und Ultraschallwandler in der Medizin Anwendung findet.This design provides a broadband and sensitive ultrasound transducer, which is used in medicine in particular because of its almost low-reflection coupling between tissue and ultrasound transducer.

In einer besonders vorteilhaften Ausführungsform nach Fig. 2 besteht die Empfangsschicht 6 aus einem Stapel dünner, elektrisch in Serie geschalteter piezoelektrischer Kunststoffolien 10. Diese piezoelektrischen Kunststoffolien 10 sind jeweils in derselben Richtung polarisiert, und die Dicke des Stapels beträgt eine Viertelwellenlänge bei einer vorbestimmten Resonanzfrequenz. Bis zu einer Frequenz von beispielsweise 4 MHz kann der Stapel zweckmäßig aus beispielsweise 25 µm dicken Kunststoffolien 10 bestehen, während für höhere Frequenzen der Stapel aus beispielsweise 9 µm dikken Kunststoffolien 10 aufgebaut sein kann. Als Material für die piezoelektrischen Kunststoffolien der Empfangsschicht 6 kann man beispielsweise Polyvinylchlorid PVC, insbesondere Polyvinyliden-Fluorid PVDF, verwenden.In a particularly advantageous embodiment according to FIG. 2, the receiving layer 6 consists of a stack of thin piezoelectric plastic films 10 which are electrically connected in series. These piezoelectric plastic films 10 are each polarized in the same direction, and the thickness of the stack is a quarter wavelength at a predetermined resonance frequency. Up to a frequency of, for example, 4 MHz, the stack can expediently consist of, for example, 25 μm thick plastic films 10, while for higher frequencies the stack can be constructed of, for example, 9 μm thick plastic films 10. For example, polyvinyl chloride PVC, in particular polyvinylidene fluoride PVDF, can be used as the material for the piezoelectric plastic films of the receiving layer 6.

Durch diese Gestaltung der Empfangsschicht 6 kann man die dünnen, beispielsweise 9 µm bis 25 µm dicken, piezoelektrischen Kunststoffolien sehr gut polarisieren.This configuration of the receiving layer 6 allows the thin, for example 9 μm to 25 μm thick, piezoelectric plastic films to be polarized very well.

In einerweiteren Ausführungsform nach Fig. 3 besteht die Empfangsschicht 6 aus einer aktiven piezoelektrischen Kunststoffolie 12 und einer dickeren, passiven piezoelektrischen Kunststoffolie 14. Die Dicke der passiven piezoelektrischen Kunststoffolie 14 der Empfangsschicht 6 beträgt ein Vielfaches, beispielsweise 2- bis 15fache, der Dicke der aktiven piezoelektrischen Kunststoffolie 12 der Empfangsschicht 6. Die aktive piezoelektrische Kunststoffolie 12, die beispielsweise 25 µm dick ist, ist auf die erste X/4-Anpassungsschicht 8 angeordnet, und die passive piezoelektrische Kunststoffolie 14 ist der Last zugewandt. Auch in dieser Ausführungsform verwendet man als Material für die piezoelektrischen Kunststoffolien der Empfangsschicht 6 beispielsweise Polyvinylchlorid PVC, insbesondere Polyvinyliden-Fluorid PVDF. Sowohl die aktive als auch die passive piezoelektrische Kunststoffolie 12 bzw. 14 bestehen aus demselben Material, wobei die aktive piezoelektrische Kunststoffolie 12 polarisiert ist.In a further embodiment according to FIG. 3, the receiving layer 6 consists of an active piezoelectric plastic film 12 and a thicker, passive piezoelectric plastic film 14. The thickness of the passive piezoelectric plastic film 14 of the receiving layer 6 is a multiple, for example 2 to 15 times, the thickness of the active one piezoelectric plastic film 12 of the receiving layer 6. The active piezoelectric plastic film 12, which is for example 25 μm thick, is arranged on the first X / 4 matching layer 8, and the passive piezoelectric plastic film 14 faces the load. In this embodiment too, the material used for the piezoelectric plastic films of the receiving layer 6 is, for example, polyvinyl chloride PVC, in particular polyvinylidene fluoride PVDF. Both the active and the passive piezoelectric plastic film 12 or 14 consist of the same material, the active piezoelectric plastic film 12 being polarized.

Durch diese Gestaltung der Empfangsschicht 6 erhält man einen breitbandigen und empfindlichen Ultraschallwandler mit verhältnismäßig großer Kapazität und entsprechend geringer Innenimpedanz bei verhältnimäßig kleinen räumlichen Abmessungen.This configuration of the receiving layer 6 results in a broadband and sensitive ultrasound transducer with a relatively large capacitance and a correspondingly low internal impedance with relatively small spatial dimensions.

Claims (10)

1. An ultrasonic transducer having a supporting body (2), a transmitting layer (4) of a material with a relatively high dielectric constant and high acoustic impedance and a first λ/4 coupling layer (8) that faces the transmitting layer (4), and a second X/4 coupling layer that faces a load, characterised in that the second λ/4 coupling layer also serves as a receiving layer (6) and that the first λ/4 coupling layer (8) also serves as backing for the receiving layer (6).
2. An ultrasonic transducer according to claim 1, characterised in that the receiving layer (6) consists of a stack of thin foils (10) of piezoelectric plastics material electrically connected in series.
3. An ultrasonic transducer according to claim 1, characterised in that the receiving layer (6) consists of an active piezoelectric plastics material foil (12) and a passive piezoelectric plastics material foil (14).
4. An ultrasonic transducer according to claim 3, characterised in that the active piezoelectric plastics material foil (12) of the receiving layer is arranged on the hard backing and the passive piezoelectric plastics material foil (14) faces the receiving layer (6) of the load.
5. An ultrasonic transducer according to claim 3, characterised in that the thickness of the passive piezoelectric plastics material foil (14) of the receiving layer (6) is a multiple of the thickness of the active piezoelectric plastics material foil (12) of the receiving layer (6).
6. An ultrasonic transducer according to claim 1, characterised in that the transmitting layer (4) consists of lead zirconate titanate PZT or lead meta- niobate Pb(N03).
7. An ultrasonic transducer according to claim 1 and claim 6, characterised in that the second A/4 coupling layer has an acoustic impedance of about 4 x 106 Pas/m and the first X/4 coupling layer (8) has an acoustic impedance of about 14 x 106 Pas/m.
8. An ultrasonic transducer according to any one of claims 1 to 3, characterised in that the receiving layer (6) consists of piezoelectric plastics material foils (10, 12, 14).
9. An ultrasonic transducer according to claim 8, characterised in that the piezoelectric plastics material foils (10, 12, 14) of the receiving layer (6) consist of polyvinylidene fluoride PVDF or polyvinyl chloride PVC.
10. An ultrasonic transducer according to claim 1, characterised in that the first λ/4 coupling layer consists of quartz glass or a vitreous substance or porcelain.
EP84102147A 1983-03-15 1984-02-29 Ultrasonic transducer Expired EP0118837B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84102147T ATE35338T1 (en) 1983-03-15 1984-02-29 ULTRASONIC TRANSDUCER.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19833309236 DE3309236A1 (en) 1983-03-15 1983-03-15 ULTRASONIC CONVERTER
DE3309236 1983-03-15

Publications (3)

Publication Number Publication Date
EP0118837A2 EP0118837A2 (en) 1984-09-19
EP0118837A3 EP0118837A3 (en) 1985-05-15
EP0118837B1 true EP0118837B1 (en) 1988-06-22

Family

ID=6193523

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84102147A Expired EP0118837B1 (en) 1983-03-15 1984-02-29 Ultrasonic transducer

Country Status (5)

Country Link
EP (1) EP0118837B1 (en)
JP (1) JPS59161800U (en)
AT (1) ATE35338T1 (en)
CA (1) CA1252558A (en)
DE (2) DE3309236A1 (en)

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DE102007027277A1 (en) * 2007-06-11 2008-12-18 Endress + Hauser Flowtec Ag ultrasonic sensor

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DE3422115A1 (en) * 1984-06-14 1985-12-19 Siemens AG, 1000 Berlin und 8000 München ULTRASONIC TRANSDUCER SYSTEM
DE3430186A1 (en) * 1984-08-16 1986-02-27 Siemens AG, 1000 Berlin und 8000 München METHOD FOR PRODUCING A POROUS PIEZOELECTRIC MATERIAL AND MATERIAL PRODUCED BY THIS METHOD
DE3501808A1 (en) * 1985-01-21 1986-07-24 Siemens AG, 1000 Berlin und 8000 München ULTRASONIC CONVERTER
US4718421A (en) * 1985-08-09 1988-01-12 Siemens Aktiengesellschaft Ultrasound generator
DE3839057A1 (en) * 1988-11-18 1990-05-23 Fraunhofer Ges Forschung Array-type probe
DE3932959C1 (en) * 1989-10-03 1991-04-11 Richard Wolf Gmbh, 7134 Knittlingen, De
US5263004A (en) * 1990-04-11 1993-11-16 Hewlett-Packard Company Acoustic image acquisition using an acoustic receiving array with variable time delay
EP0451517B1 (en) * 1990-04-11 1996-05-01 Hewlett-Packard Company Acoustic image acquisition
DE19714606A1 (en) * 1997-04-09 1998-10-15 Itt Mfg Enterprises Inc Ultra sound transmitter and receiver for motor vehicle distance warning system
EP1042653A1 (en) * 1997-12-23 2000-10-11 Simmonds Precision Products Inc. Ultrasonic liquid gauging system
US20100256497A1 (en) * 2007-11-21 2010-10-07 Kenji Ohnuma Oscillator for ultrasonic wave reception, its manufacturing method, ultrasonic wave probe and ultrasonic wave medical diagnostic imaging system
EP2444166A1 (en) * 2009-09-15 2012-04-25 Fujifilm Corporation Ultrasonic transducer, ultrasonic probe and producing method
US11806749B2 (en) * 2021-10-28 2023-11-07 Baker Hughes, A Ge Company, Llc Ultrasonic transducer for flow measurement

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Biomedizinische Technik, Bd. 27 Heft 7 Seiten 183-184 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007027277A1 (en) * 2007-06-11 2008-12-18 Endress + Hauser Flowtec Ag ultrasonic sensor

Also Published As

Publication number Publication date
EP0118837A2 (en) 1984-09-19
JPS59161800U (en) 1984-10-30
JPH0453117Y2 (en) 1992-12-14
ATE35338T1 (en) 1988-07-15
CA1252558A (en) 1989-04-11
EP0118837A3 (en) 1985-05-15
DE3309236A1 (en) 1984-09-20
DE3472318D1 (en) 1988-07-28

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