EP1169143A1 - Impulse sound transducer with an elementary block made of piezoelectric material - Google Patents

Impulse sound transducer with an elementary block made of piezoelectric material

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Publication number
EP1169143A1
EP1169143A1 EP00929375A EP00929375A EP1169143A1 EP 1169143 A1 EP1169143 A1 EP 1169143A1 EP 00929375 A EP00929375 A EP 00929375A EP 00929375 A EP00929375 A EP 00929375A EP 1169143 A1 EP1169143 A1 EP 1169143A1
Authority
EP
European Patent Office
Prior art keywords
block
sound transducer
piezoelectric material
impulse sound
collar
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.)
Granted
Application number
EP00929375A
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German (de)
French (fr)
Other versions
EP1169143B1 (en
Inventor
Bicz Wieslaw
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.)
Sonident Anstalt
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Sonident Anstalt
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Publication of EP1169143A1 publication Critical patent/EP1169143A1/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0644—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element

Definitions

  • the invention relates to a pulse transducer in the ultrasonic range. Such converters are needed in many areas of technology where short pulses are necessary. Defectoscopy comes first, followed by sonography in the medical field.
  • the classic design of such a transducer consists of a plane-parallel plate made of piezoelectric material, which has electrodes on the two flat upper and lower sides, the plate being polarized perpendicular to the sides covered with electrodes.
  • This plate is glued to a block that dampens the ultrasonic wave and has acoustic impedance that is matched to the piezo plate.
  • So-called adaptation layers are provided on the outlet side, which allow reflection-free sound transmission and very short pulses to be achieved in pulse mode. Converters of this type are well known State of the art, and a good discussion of it and the problems that arise, can be found, for example, in the book by MG Silk, Ultrasonic Transducers for Nondestructive Testing, Adam Hüger 1984.
  • Converters of the well-known type require a complex and therefore expensive technology if they are to generate really good impulses. Furthermore, the known transducers are relatively thick (at least 5 mm) and it is virtually impossible to manufacture them for frequencies that are greater than 30 MHz. Also, with pulse excitation, only relatively long pulses are generated, which have a negative effect on the measurements. Another disadvantage is that they are not suitable for automatic mass production and their parameters cannot be kept within a narrow tolerance range.
  • Transducers with lens-shaped elementary blocks have relatively good pulse shapes and also good repeatability, but they only produce weak signals and are considerably less sensitive compared to classic converters. The same disadvantages have also been found in transducers which are able to deliver relatively short signals due to the special electrode design or inhomogeneous polarization of the piezo element.
  • the object on which the invention is based is to create a sound transducer for the ultrasound range which emits strong and short pulses, has a high sensitivity and ensures repeatability of the parameters in series production.
  • the object is achieved according to the invention by the features of the pulse sound transducer contained in the characterizing part of claim 1.
  • the block which is T-shaped in longitudinal section and which may have a column, cone or pyramid shape with a round, oval or polygonal cross section is dimensioned in such a way that that there is damping of the shaft which moves inside the column to prevent it from reflecting on the free column wall and emerging as a ringing which deteriorates the pulse quality. It is therefore possible to dispense with further damping means. In addition, the production as a mass article is made considerably easier by the omission of additional damping means and adhesive connections. It is essential for the invention to form a collar on the block to form the unit cell. This shape, the selected proportions and the arrangement of the electrodes, which are arranged on the exit surface and around the block above the collar, are decisive for the basic vibration, which is designed in three dimensions.
  • the basic polarization direction of the piezo material should run perpendicular to the base surface, that is to say the exit surface of the pulse of the T-shaped unit cell.
  • Fig. 3 shows the electric field within the elementary cell.
  • Figure 1 shows the unit cell 1 in a perspective view. This consists of block 2 and the collar 3 molded onto it. The collar protrudes over the block.
  • the unit cell 1 is triangular in section, but it can also have any other shape. It can be round, oval and polygonal, and taper to the top as a cone or pyramid.
  • One electrode 4 is arranged on the straight exit surface of the pulse, while the other electrode 5 extends laterally along the block 2. It is not necessary for the electrode 5 to run around the entire block, nor for the lower electrode to cover the entire lower surface.
  • the thickness of the covenant is marked with a, the height of the block with b, the width of the block with c and the total height of unit cell 1 with h.
  • the active area of the unit cell is located in the lower part of the block and within the federal government.
  • the proportions of the unit cell are essential. It has been shown that the thickness of the collar in relation to the height of the block of piezoelectric material to the total height, So keep a / b / h in the ratio 1/4 - 6/10 in order to produce optimal results. Optimal results means that strong and short impulses are emitted and the converter has a high sensitivity. 2 shows the pulse curve achieved with the sound transducer according to the invention.
  • the T-shape of the elementary cell 1 according to the invention is of very great importance since it enables the electric field between the electrodes within the elementary cell to be closed.
  • 3 shows the image of the electric field in the unit cell. As can be seen from this, this only runs within the unit cell of the converter. This shape also enables volume oscillation and all upwards s.
  • Fig. 1 directed waves, that is, against the impulse exit surface propagating waves so attenuated that they can no longer be reflected at the upper end of the unit cell.
  • the proportions of the unit cell are of great importance.
  • the ratio of the individual parts of the unit cell has already been specified.
  • the height of cell h should be at least 10 times greater than the height of collar a.
  • Such a converter produces pulses that are 20 ns long and has a bandwidth of 4 - 35 MHz as a receiver.
  • the ultrasonic wave that goes up in the drawing is totally damped.
  • the complete transducer does not have to be thicker than 2 mm. It is even possible to make it significantly thinner if the unit cell is constructed in such a way that it forms a peak at the top, which prematurely dampens the wave going in this direction.
  • the component of the electric field that is parallel to the foot of the unit cell 1, that is to say the transverse bars of the T, is comparable to the component perpendicular to it.
  • the properties of the transducer according to the invention are only determined by the properties of the selected piezoelectric material and the precision of the shape of the unit cell, i. H. in other words, the converter according to the invention can be produced with very good repeatability.
  • Transducers of this type can contain one or more unit cells that can be connected to one another.
  • the converter according to the invention is able to produce very short and very strong pulses that cannot be achieved with other converter designs.
  • the amplitude of the pulses produced is at least twice greater than that of the classic converters. Its sensitivity is comparable to that of classic designs.
  • the converter according to the invention can, however, be manufactured at considerably lower costs and used wherever classic converter types can also be used.
  • the converter according to the invention can achieve a significant increase in effectiveness in comparison to other non-classical constructions, since no losses of the electric field occur to the outside and all undesired sound waves are subjected to an almost complete damping without this large ceramic thickness or other damping bodies would have to be used.
  • the pulse length is shorter and the amplitude larger. None of the known designs is easier to manufacture.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Surgical Instruments (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)

Abstract

The invention relates to an impulse sound traducer for the ultrasonic range. Transducers in prior art require complicated and expensive technology in order to really generate good impulses. The invention aims at providing a sound transducer for the ultrasonic range, which transmits strong and short impulses, has high senstivity and ensures repeatability of parameters. This is achieved by a sound transducer for the ultrasonic range that is used both as a transmitter and as a receiver and is comprised of an elementary block made of piezoelectric material, wherein the height of the elementary blocks consisting of piezoelectric material is bigger than its width and the block on the output end of the impulse has a formed edge so that the elementary block has a T-shape in the longitudinal section, wherein one electrode is provided on the outlet surface while the other electrode extends above the edge on the block.

Description

IMPULS-ULTRASCHALLWANDLER MIT EINEM ELEMENTARBLOCK AUS PIEZOELEKTRISCHEM MATE¬ RIALPULSE ULTRASOUND CONVERTER WITH AN ELEMENTARY BLOCK FROM PIEZOELECTRIC MATE RIAL ¬
Die Erfindung bezieht sich auf einen Impulsschallwandler im Ultraschallbereich. Solche Wandler werden auf vielen Gebieten der Technik benötigt, wo kurze Impulse notwendig sind. An erster Stelle steht dabei die Defektoskopie, woran sich die Sonographie im medizinischen Bereich anschließt.The invention relates to a pulse transducer in the ultrasonic range. Such converters are needed in many areas of technology where short pulses are necessary. Defectoscopy comes first, followed by sonography in the medical field.
Die klassische Konstruktion eines solchen Wandlers besteht aus einer planparallelen Platte aus piezoelektrischem Material, die an den beiden flachen Ober- und Unterseiten Elektroden aufweist, wobei die Platte senkrecht zu den mit Elektroden belegten Seiten polarisiert ist. Diese Platte ist auf einen Block aufgeklebt, der die Ultraschallwelle dämpft und akustische Impedanz hat, die an die Piezoplatte angepaßt ist. An der Austrittsseite sind sogenannte Anpassungsschichten vorgesehen, die eine reflexionsfreie Schallübertragung und im Impulsbetrieb sehr kurze Impulse erzielen lassen. Wandler dieser Art gehören zum bekannten Stand der Technik, und eine gute Erörterung darüber und der dabei auftretenden Probleme findet sich z.B. in dem Buch von M. G. Silk, Ultrasonic Transducers for Nondestructive Testing, Adam Hüger 1984.The classic design of such a transducer consists of a plane-parallel plate made of piezoelectric material, which has electrodes on the two flat upper and lower sides, the plate being polarized perpendicular to the sides covered with electrodes. This plate is glued to a block that dampens the ultrasonic wave and has acoustic impedance that is matched to the piezo plate. So-called adaptation layers are provided on the outlet side, which allow reflection-free sound transmission and very short pulses to be achieved in pulse mode. Converters of this type are well known State of the art, and a good discussion of it and the problems that arise, can be found, for example, in the book by MG Silk, Ultrasonic Transducers for Nondestructive Testing, Adam Hüger 1984.
Wandler der bekannten Bauart verlangen, eine aufwendige und damit kostspielige Technologie, falls sie wirklich gute Impulse generieren sollen. Ferner sind die bekannten Wandler relativ dick (mindestens 5 mm) und es ist so gut wie unmöglich, sie für Frequenzen zu fertigen, die größer als 30 MHz sind. Auch werden bei Impulsanregung nur relativ lange Pulse erzeugt, die sich nachteilig auf die Messungen auswirken. Ein weiterer Nachteil besteht darin, daß sie sich nicht für automatische Massenanfertigung eignen und auch ihre Parameter nicht in einem engen Toleranzbereich gehalten werden können.Converters of the well-known type require a complex and therefore expensive technology if they are to generate really good impulses. Furthermore, the known transducers are relatively thick (at least 5 mm) and it is virtually impossible to manufacture them for frequencies that are greater than 30 MHz. Also, with pulse excitation, only relatively long pulses are generated, which have a negative effect on the measurements. Another disadvantage is that they are not suitable for automatic mass production and their parameters cannot be kept within a narrow tolerance range.
Relativ gute Impulsformen und auch gute Wiederholbarkeit besitzen Wandler mit linsenförmigen Elementarblöcken, jedoch produzieren sie nur schwache Signale und sind im Vergleich zu den klassischen Wandlern erheblich weniger empfindlich. Die gleichen Nachteile wurden auch an Wandlern festgestellt, die durch spezielle Elektrodengestaltung oder inhomogene Polarisation des Piezoelementes in der Lage sind, relativ kurze Signale zu liefern.Transducers with lens-shaped elementary blocks have relatively good pulse shapes and also good repeatability, but they only produce weak signals and are considerably less sensitive compared to classic converters. The same disadvantages have also been found in transducers which are able to deliver relatively short signals due to the special electrode design or inhomogeneous polarization of the piezo element.
Die der Erfindung zugrunde liegende Aufgabe besteht darin, einen Schallwandler für den Ultraschallbereich zu schaffen, der starke und kurze Impulse aussendet, eine große Empfindlichkeit aufweist und eine Wiederholbarkeit der Parameter bei der Serienherstellung gerantiert. Die gestellte Aufgabe wird erfindungsgemäß durch die im kennzeichnenden Teil des Anspruches 1 enthaltenen Merkmale des Impulsschallwandlers gelöst.The object on which the invention is based is to create a sound transducer for the ultrasound range which emits strong and short pulses, has a high sensitivity and ensures repeatability of the parameters in series production. The object is achieved according to the invention by the features of the pulse sound transducer contained in the characterizing part of claim 1.
Der im Längsschnitt T-förmige Block, der Säulen-, Kegel- oder Pyramidenform mit rundem, ovalem oder mehreckigem Querschnitt haben kann, ist so bemessen, daß eine Dämpfung der Welle erfolgt, die sich ins Innere der Säule bewegt um zu verhindern, daß sie an der freien Säulenwand reflektiert und als eine Nachschwingung nach außen tritt, die die Impulsqualität verschlechtert. Es kann somit auf weitere Dämpfungsmittel verzichtet werden, Außerdem wird die Herstellung als Massenartikel durch den Wegfall von zusätzlichen Dämpfungsmitteln und Klebeverbindungen wesentlich erleichtert. Essentiell für die Erfindung ist die Anformung eines Bundes an den Block zur Bildung der Elementarzelle. Diese Formgebung, die gewählten Proportionen sowie die Anordnung der Elektroden, die an der Austrittsfläche und um den Block herum oberhalb des Bundes angeordent sind, sind ausschlaggebend für die Grundschwingung, die dadurch dreidimensional gestaltet ist. Es ist auch wichtig, daß infolge der erfindungsgemäßen Konstruktion der Elementarzelle sich das elektrische Feld innerhalb der Elementarzelle schließt und somit ein starker Impuls nach außen gesendet werden kann. Die Grundpolarisationsrichtung des Piezomaterials soll senkrecht zu der Fußfläche, also der Austrittsfläche des Impulses der T-förmigen Elementarzelle verlaufen.The block which is T-shaped in longitudinal section and which may have a column, cone or pyramid shape with a round, oval or polygonal cross section is dimensioned in such a way that that there is damping of the shaft which moves inside the column to prevent it from reflecting on the free column wall and emerging as a ringing which deteriorates the pulse quality. It is therefore possible to dispense with further damping means. In addition, the production as a mass article is made considerably easier by the omission of additional damping means and adhesive connections. It is essential for the invention to form a collar on the block to form the unit cell. This shape, the selected proportions and the arrangement of the electrodes, which are arranged on the exit surface and around the block above the collar, are decisive for the basic vibration, which is designed in three dimensions. It is also important that, due to the construction of the unit cell according to the invention, the electric field within the unit cell closes and a strong pulse can thus be sent outwards. The basic polarization direction of the piezo material should run perpendicular to the base surface, that is to say the exit surface of the pulse of the T-shaped unit cell.
Es wurde festgestellt, daß es besonders vorteilhaft ist, wenn die folgenden Abmessungsverhältnisse eingehalten werden, nämlich a/ b/ h = 1 / 4-6/ 10, wobei a die Dicke des Bundes, b der Durchmesser des Blocks bzw. dessen Breite und h die Höhe der Elementarzelle ist. Die Größenverhältnisse der schallerzeugenden Elementen, hier der Elementarzelle, sind bei allen schallwellenerzeugenden Konstruktionen von ganz besonderer Bedeutung, wie Beispiele aus der Musikwelt zeigen. So erzeugen die Violine, die Bratsche, das Cello und der Kontrabaß aufgrund ihrer unterschiedlichen Größenverhältnisse unterschiedliche Tonhöhen und -tiefen. Es hat sich ebenfalls gezeigt, daß eine zusätzliche radiale Polarisierung durch Anlegen einer hohen Spannung die Stärke des Impulses verbessert. Höchstwahrscheinlich wirkt sich diese Polarisierung durch die Ausnutzung der zusätzlichen Piezoef- fekte vorteilhaft aus.It has been found that it is particularly advantageous if the following dimensional ratios are observed, namely a / b / h = 1 / 4-6 / 10, where a is the thickness of the collar, b the diameter of the block or its width and h is the height of the unit cell. The proportions of the sound generating elements, here the unit cell, are of particular importance in all sound wave generating constructions, as examples from the music world show. The violin, viola, cello and double bass produce different pitches and depths due to their different proportions. It has also been shown that additional radial polarization by applying a high voltage improves the strength of the pulse. Most likely, this polarization has an advantageous effect by utilizing the additional piezo effects.
Weitere Einzelheiten der Erfindung werden anhand der beigefügten Zeichnungen erläutert. Dabei zeigen:Further details of the invention will be explained with reference to the accompanying drawings. Show:
Fig. 1 eine perspektivische Darstellung der Elementarzelle,1 is a perspective view of the unit cell,
Fig. 2 den Verlauf des Impulses,2 shows the course of the pulse,
Fig. 3 das elektrische Feld innerhalb der Elementarrzelle.Fig. 3 shows the electric field within the elementary cell.
Figur 1 zeigt die Elementarzelle 1 in perspektivischer Darstellung. Diese besteht aus dem Block 2 und dem daran angeformten Bund 3. Der Bund ragt über den Block heraus. In der gezeigten Darstellung ist die Elementarzelle 1 im Schnitt dreieckförmig gehalten, sie kann aber auch jede andere Form besitzen. Sie kann rund, oval und mehreckig sein, sowie nach obenhin spitz als Kegel oder Pyramide zulaufen. Die eine Elektrode 4 ist an der geraden Austrittsfläche des Impulses angeordnet, während die andere Elektrode 5 sich seitlich entlang dem Block 2 erstreckt. Es ist nicht erforderlich, daß die Elektrode 5 um den ganzen Block herumläuft und auch nicht, daß die untere Elektrode die gesamte untere Fläche bedeckt.Figure 1 shows the unit cell 1 in a perspective view. This consists of block 2 and the collar 3 molded onto it. The collar protrudes over the block. In the illustration shown, the unit cell 1 is triangular in section, but it can also have any other shape. It can be round, oval and polygonal, and taper to the top as a cone or pyramid. One electrode 4 is arranged on the straight exit surface of the pulse, while the other electrode 5 extends laterally along the block 2. It is not necessary for the electrode 5 to run around the entire block, nor for the lower electrode to cover the entire lower surface.
Die Dicke des Bundes ist mit a, die Höhe des Blocks mit b, die Breite des Blocks mit c und die Gesamthöhe der Elementarzelle 1 mit h gekennzeichnet. Der aktive Bereich der Elementarzelle befindet sich im unteren Teil des Blocks und innerhalb des Bundes. Wie schon erwähnt, sind die Proportionen der Elementarzelle von essentieller Bedeutung. Es hat sich dabei gezeigt, daß die Dicke des Bundes im Verhältnis zu der Höhe des Blocks aus piezoelektrischem Material zu der Gesamthöhe, also a/b/h im Verhältnis 1 / 4 - 6 / 10 zu halten ist, um optimale Ergebnisse zu erzeugen. Optimale Ergebnisse heißt, daß starke und kurze Impulse ausgesendet werden, und der Wandler eine große Empfindlichkeit aufweist. In Fig. 2 ist die mit dem erfindungsgemäßen Schallwandler erreichte Impulskurve dargestellt.The thickness of the covenant is marked with a, the height of the block with b, the width of the block with c and the total height of unit cell 1 with h. The active area of the unit cell is located in the lower part of the block and within the federal government. As already mentioned, the proportions of the unit cell are essential. It has been shown that the thickness of the collar in relation to the height of the block of piezoelectric material to the total height, So keep a / b / h in the ratio 1/4 - 6/10 in order to produce optimal results. Optimal results means that strong and short impulses are emitted and the converter has a high sensitivity. 2 shows the pulse curve achieved with the sound transducer according to the invention.
Die erfindungsgemäße T-Form der Elementarzelle 1 ist von sehr großer Bedeutung, da sie ermöglicht, daß das elektrische Feld zwischen den Elektroden innerhalb der Elementarzelle geschlossen wird. In Fig. 3 ist das Bild des elektrischen Feldes in der Elementarzelle wiedergegeben. Wie daraus ersichtlich, verläuft dieses nur innerhalb der Elementarzelle des Wandlers. Diese Form ermöglicht außerdem eine Volumenschwingung und dazu noch alle nach oben s. Fig. 1 gerichteten Wellen, also entgegen der Impulsaustrittsfläche sich fortpflanzenden Wellen so dämpft, daß sie nicht mehr an dem oberen Ende der Elementarzelle reflektiert werden können.The T-shape of the elementary cell 1 according to the invention is of very great importance since it enables the electric field between the electrodes within the elementary cell to be closed. 3 shows the image of the electric field in the unit cell. As can be seen from this, this only runs within the unit cell of the converter. This shape also enables volume oscillation and all upwards s. Fig. 1 directed waves, that is, against the impulse exit surface propagating waves so attenuated that they can no longer be reflected at the upper end of the unit cell.
Von großer Bedeutung sind - wie schon ausgeführt - die Proportionen der Elementarzelle. Das Verhältnis der einzelnen Teile der Elementarzelle ist bereits angegeben worden. Die Höhe der Zelle h soll mindestens 10 mal größer als die der Höhe des Bundes a sein. Die tatsächlichen Abmessungen können beispielsweise folgende Werte haben: a = 0,2 mm, b = 1 mm und h = 2 mm. Ein solcher Wandler produziert Impulse, die 20 ns lang sind und hat als Empfänger eine Bandbreite von 4 - 35 MHz.As already stated, the proportions of the unit cell are of great importance. The ratio of the individual parts of the unit cell has already been specified. The height of cell h should be at least 10 times greater than the height of collar a. The actual dimensions can have the following values, for example: a = 0.2 mm, b = 1 mm and h = 2 mm. Such a converter produces pulses that are 20 ns long and has a bandwidth of 4 - 35 MHz as a receiver.
Bei dem erfindungsgemäßen Wandler mit den genannten Proportionen wird die Ultraschallwelle, die in der Zeichnung nach oben geht, total gedämpft. Der komplette Wandler muß nicht dicker als 2 mm sein. Es ist sogar möglich, ihn bedeutend dünner zu machen, wenn die Elementarzelle so konstruiert ist, daß sie nach oben eine Spitze bildet, die die in diese Richtung gehen-de Welle vorzeitig ausreichend dämpft.In the transducer according to the invention with the proportions mentioned, the ultrasonic wave that goes up in the drawing is totally damped. The complete transducer does not have to be thicker than 2 mm. It is even possible to make it significantly thinner if the unit cell is constructed in such a way that it forms a peak at the top, which prematurely dampens the wave going in this direction.
Von Bedeutung ist es auch, daß bei den gewählten Größenverhältnissen die Komponente des elektrischen Feldes, die zu dem Fuß der Elementarzelle 1 , also den Querbalken des T parallel ist, vergleichbar mit der dazu senkrechten Komponente ist.It is also important that, with the selected size ratios, the component of the electric field that is parallel to the foot of the unit cell 1, that is to say the transverse bars of the T, is comparable to the component perpendicular to it.
Infolge dieser Tatsache spielen alle Piezokoeffizienten des Piezomaterials eine im wesentlichen gleichbedeutende Rolle. Es kommt zu einer Volumenschwingung des aktiven Bereichs der Elementarzelle, die durch ihre Form und gezielte Anbringung der Elektroden sowie nachträgliche Polarisierung in der radialen Richtung gestaltbar ist. Die nachträgliche Polarisierung erfolgt nach Fertigstellung des Wandlers bzw. der Elementarzelle durch Anlegen einer relativ hohen Spannung an seine Elektroden. Diese Schwingungsart ermöglicht offensichtlich eine bessere Nutzung des Piezoeffektes und beeinflußt auch die Dämpfung der nach hinten gehenden Welle.As a result of this fact, all the piezocoefficients of the piezomaterial play an essentially equivalent role. There is a volume oscillation of the active area of the unit cell, which can be designed in the radial direction by its shape and targeted attachment of the electrodes as well as subsequent polarization. The subsequent polarization takes place after completion of the converter or the unit cell by applying a relatively high voltage to its electrodes. This type of vibration obviously enables better use of the piezo effect and also influences the damping of the shaft going backwards.
Die Eigenschaften des erfindungsgemäßen Wandlers werden dabei nur durch die Eigenschaften des gewählten piezoelektrischen Materials und die Präzision der Formgebung der Elementarzelle bestimmt, d. h. mit anderen Worten, der erfindungsgemäße Wandler läßt sich mit sehr guter Wiederholbarkeit herstellen. Wandler diesen Typs können eine oder mehrere Elementarzellen enthalten, die miteinander verbunden werden können.The properties of the transducer according to the invention are only determined by the properties of the selected piezoelectric material and the precision of the shape of the unit cell, i. H. in other words, the converter according to the invention can be produced with very good repeatability. Transducers of this type can contain one or more unit cells that can be connected to one another.
Der erfindungsgemäße Wandler ist in der Lage sehr kurze und sehr starke Impulse zu produzieren, die mit anderen Wandlerkonstruktionen nicht erreichbar sind. Die Amplitude der produzierten Impulse ist mindestens zweimal größer als bei den klassischen Wandlern. Seine Empfindlichkeit ist mit den klassischen Konstruktionen vergleichbar. Der erfindungsgemäße Wandler läßt sich aber mit erheblich niedrigeren Kosten herstellen und überall dort einsetzen, wo auch klassische Wandlertypen verwendet werden können.The converter according to the invention is able to produce very short and very strong pulses that cannot be achieved with other converter designs. The amplitude of the pulses produced is at least twice greater than that of the classic converters. Its sensitivity is comparable to that of classic designs. The converter according to the invention can, however, be manufactured at considerably lower costs and used wherever classic converter types can also be used.
Zusammenfassend läßt sich sagen, daß mit dem erfindungsgemäßen Wandler im Vergleich zu anderen nicht klassischen Konstruktionen eine erhebliche Steigerung der Effektivität erreicht werden kann, da keine Verluste des elektrischen Feldes nach außenhin auftreten und alle unerwünschten Schallwellen einer fast vollständigen Dämpfung unterworfen werden, ohne daß dazu eine große Keramikdicke oder andere Dämpfungskörper benutzt werden müßten. Im Vergleich zu den klassischen Konstruktionen ist die Impulslänge kürzer und die Amplitude größer. Keine der bekannten Konstruktionen ist leichter zu fertigen. In summary, it can be said that the converter according to the invention can achieve a significant increase in effectiveness in comparison to other non-classical constructions, since no losses of the electric field occur to the outside and all undesired sound waves are subjected to an almost complete damping without this large ceramic thickness or other damping bodies would have to be used. Compared to classic designs, the pulse length is shorter and the amplitude larger. None of the known designs is easier to manufacture.

Claims

Patentansprüche claims
1.) Impulsschallwandler für den Ultraschallbereich zum Einsatz sowohl als Sender wie auch als Empfänger mit einem Elementarblock aus piezoelektrischem Material, dadurch gekennzeichnet, daß die Höhe des aus piezoelektrischem Material bestehenden Elementarblocks des Wandlers größer ist als dessen Breite und der Block am Austrittsende der Impulse einen angeformten Bund derart aufweist, daß eine glatte Austrittsfläche für die Schallwelle gebildet ist und im Längsschnitt eine T-Form entsteht, wobei die Grundpolarisation senkrecht zur Austrittsfläche verläuft und die eine Elektrode auf der Austrittsfläche vorgesehen ist, während die andere oberhalb des Bundes an dem Block verläuft.1.) Impulse sound transducer for the ultrasonic range for use both as a transmitter and as a receiver with an elementary block made of piezoelectric material, characterized in that the height of the elementary block made of piezoelectric material of the transducer is greater than its width and the block at the exit end of the pulses integrally formed collar so that a smooth exit surface for the sound wave is formed and a T-shape is formed in longitudinal section, the basic polarization is perpendicular to the exit surface and one electrode is provided on the exit surface, while the other runs above the collar on the block .
2.) Impulsschallwandler nach Anspruch 1, dadurch gekennzeichnet, daß der Block als runde oder mehreckige Säule, Kegel oder Pyramide ausgebildet und der Bund entsprechend angepaßt ist.2.) Impulse sound transducer according to claim 1, characterized in that the block is designed as a round or polygonal column, cone or pyramid and the collar is adapted accordingly.
3.) Impulsschallwandler nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Proportion der Elementarzelle wie folgt gewählt ist: a/b/h = 1 / 4-6/10, wobei a die Dicke des Bundes ist, b der Durchmesser oder die Breite des Blocks und h die Höhe der gesamten Zelle. 3.) Impulse sound transducer according to claim 1 or 2, characterized in that the proportion of the unit cell is selected as follows: a / b / h = 1 / 4-6 / 10, where a is the thickness of the collar, b is the diameter or Width of the block and h the height of the entire cell.
4.) Impulsschallwandler nach einem oder mehreren der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Elementarzelle nach der Formgebung einer zusätzlichen radialen Polarisierung durch Anlegen einer hohen Spannung ausgesetzt wird.4.) Impulse sound transducer according to one or more of the preceding claims, characterized in that the unit cell is exposed to an additional radial polarization by applying a high voltage after the shaping.
5.) Impulsschallwandler nach einem oder mehreren der Ansprüche 1-4, dadurch gekennzeichnet, daß der Wandler aus mehreren Elementarzellen zusammengesetzt ist, wobei den Zellen um die Säulen oder dgl. längliche Gebilde Elektroden zugeordnet sind, jedoch die Gesamtheit der Zellen eine Elektrode an der Gesamtaustrittsfläche der Pulse aufweist. 5.) Impulse sound transducer according to one or more of claims 1-4, characterized in that the transducer is composed of several unit cells, the cells around the columns or the like. Elongated structures are associated with electrodes, but the totality of the cells is an electrode on the Total exit area of the pulses.
EP00929375A 1999-04-19 2000-04-18 Impulse sound transducer with an elementary block made of piezoelectric material Expired - Lifetime EP1169143B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19917429A DE19917429A1 (en) 1999-04-19 1999-04-19 Impulse sound transducer, for operating in ultrasonic range, utilizes an elementary cell consisting of a piezoceramic block and a collar shaped to it and protruding beyond it.
DE19917429 1999-04-19
PCT/EP2000/003489 WO2000062946A1 (en) 1999-04-19 2000-04-18 Impulse sound transducer with an elementary block made of piezoelectric material

Publications (2)

Publication Number Publication Date
EP1169143A1 true EP1169143A1 (en) 2002-01-09
EP1169143B1 EP1169143B1 (en) 2004-12-22

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EP00929375A Expired - Lifetime EP1169143B1 (en) 1999-04-19 2000-04-18 Impulse sound transducer with an elementary block made of piezoelectric material

Country Status (7)

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US (1) US6720715B1 (en)
EP (1) EP1169143B1 (en)
AT (1) ATE285302T1 (en)
CA (1) CA2366956A1 (en)
DE (2) DE19917429A1 (en)
PL (1) PL351622A1 (en)
WO (1) WO2000062946A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100472832C (en) 2001-11-02 2009-03-25 产品系统公司 Radial power megasonic transducer
US6984922B1 (en) * 2002-07-22 2006-01-10 Matsushita Electric Industrial Co., Ltd. Composite piezoelectric transducer and method of fabricating the same
JP4473532B2 (en) * 2002-10-10 2010-06-02 日本碍子株式会社 Piezoelectric / electrostrictive device and manufacturing method

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US3271704A (en) * 1963-03-25 1966-09-06 Bell Telephone Labor Inc Ultrasonic delay device
DE2314420C3 (en) * 1973-03-22 1978-03-30 Siemens Ag, 1000 Berlin Und 8000 Muenchen Piezoelectric button
US3891869A (en) * 1973-09-04 1975-06-24 Scarpa Lab Inc Piezoelectrically driven ultrasonic generator
SE455538B (en) * 1985-12-06 1988-07-18 Tekniska Roentgencentralen Ab Ultrasonic probe for testing a slotted or semi-finished piece of material
GB2225426B (en) * 1988-09-29 1993-05-26 Michael John Gill A transducer
WO1997016260A1 (en) * 1995-11-02 1997-05-09 Sonident Anstalt Piezoelectric ultrasonic transducer
US5606297A (en) * 1996-01-16 1997-02-25 Novax Industries Corporation Conical ultrasound waveguide
US6777856B2 (en) * 2001-08-02 2004-08-17 Kistler Holding Ag Crystal element for piezo sensors

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Title
See references of WO0062946A1 *

Also Published As

Publication number Publication date
PL351622A1 (en) 2003-05-19
EP1169143B1 (en) 2004-12-22
US6720715B1 (en) 2004-04-13
WO2000062946A1 (en) 2000-10-26
DE19917429A1 (en) 2000-10-26
CA2366956A1 (en) 2000-10-26
DE50009032D1 (en) 2005-01-27
ATE285302T1 (en) 2005-01-15

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