EP0614704B1 - Dispositif de génération d'impulsions sonores pour des applications médicales - Google Patents

Dispositif de génération d'impulsions sonores pour des applications médicales Download PDF

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Publication number
EP0614704B1
EP0614704B1 EP94101427A EP94101427A EP0614704B1 EP 0614704 B1 EP0614704 B1 EP 0614704B1 EP 94101427 A EP94101427 A EP 94101427A EP 94101427 A EP94101427 A EP 94101427A EP 0614704 B1 EP0614704 B1 EP 0614704B1
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EP
European Patent Office
Prior art keywords
voltage
transducer elements
pulses
bias
pulse
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
EP94101427A
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German (de)
English (en)
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EP0614704A2 (fr
EP0614704A3 (fr
Inventor
Werner Krauss
Jan Dipl.-Ing. Zwingenberger
Peter Jaggy
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Richard Wolf GmbH
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Richard Wolf GmbH
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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
    • B06B1/0207—Driving circuits
    • B06B1/0215—Driving circuits for generating pulses, e.g. bursts of oscillations, envelopes
    • 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
    • B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
    • B06B2201/20—Application to multi-element transducer
    • 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
    • B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
    • B06B2201/50—Application to a particular transducer type
    • B06B2201/55—Piezoelectric transducer
    • 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
    • B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
    • B06B2201/70—Specific application
    • B06B2201/76—Medical, dental
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H04R17/04—Gramophone pick-ups using a stylus; Recorders using a stylus
    • H04R17/08—Gramophone pick-ups using a stylus; Recorders using a stylus signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously

Definitions

  • the invention is based on a device for generating sound pulses for medical applications, in particular for generating shock waves for sounding objects inside the body, with piezoceramic transducer elements as electroacoustic transducers which can be controlled from a high-voltage source with high-voltage pulses in order to depend on the predetermined polarization the transducer elements and the polarity of the high-voltage pulses to generate the sound pulses by directional changes in length of the transducer elements.
  • Increases in performance can be achieved by using new improved piezoceramics or also by means of optimal acoustic adjustments, but this is generally associated with a relatively high outlay.
  • the performance of the devices can also be increased by increasing the high-voltage pulses driving the converter elements.
  • this is only at the expense of the service life of the converter elements and places the highest demands on the insulation strength, since the contacts or electrodes of the converter elements can otherwise no longer be reliably electrically insulated from one another. Otherwise, the device output can only be increased to a limited extent in this way, since otherwise the electric field strength between the contacts of the transducer elements becomes too high, the deflection and change in length of the transducer elements no longer increases in proportion to the voltage applied, and the ceramic could ultimately be destroyed.
  • the invention is intended to show a simple and inexpensive way of increasing the acoustic performance of the devices in question.
  • This object is achieved according to the invention in a device of the type mentioned at the outset in such a way that the converter elements can be subjected to a bias voltage before the arrival of a high-voltage pulse, the polarity of which is opposite to the polarity of the high-voltage pulse.
  • the transducer elements are initially biased negatively with the bias, so that a negatively directed electric field is built up in them and the length of the transducer elements, starting from a neutral output configuration , is reduced.
  • the reciprocal piezoelectric effect is also used in connection with such a bias, so that the transducer elements are biased not only by the correspondingly directed electric field, but also mechanically negatively and the position of the radiation surface is changed by a negative offset.
  • the transducer elements After negative pretensioning of the transducer elements, these are driven with the short transient and positive high-voltage pulse and deformed in the opposite direction in the radiation direction with the delivery of a positive pressure pulse from the arbitrarily induced deformation. The reverse would have to be done if negative pressure pulses or train pulses are to be generated.
  • the transducer elements are biased positively, so that their length in relation to the neutral output configuration is initially increased by a positive offset, while the transducer elements are subsequently subjected to negative high-voltage pulses and their length is suddenly reduced with the result of a negative acoustic pulse.
  • the solution according to the invention can achieve the maximum voltage applied to the transducer elements can be reduced by the amount of the bias and thus the risk of voltage flashovers between the electrodes of the transducer elements.
  • the performance of the device is also increased in that, due to the pretensioning of the transducer elements, a short rise time in their deformation and deflection is achieved as soon as the respective high-voltage pulse arrives. This is due to the endeavor of the ceramic material to want to return from the prestressed state to the neutral state, as a result of which the acceleration of the deformation is higher than if, as before, the transducer elements are driven in a charge-neutral state.
  • the bias voltage can be a permanent DC voltage, which is superimposed on the high voltage pulses which are higher in their absolute voltage value.
  • the bias voltage can also have a pulse shape and can be switched off essentially at the same time as the start or arrival of a high-voltage pulse. Because the converter elements look like RC elements with a time constant ⁇ ⁇ R x C should behave when applying bias pulses, their time length ⁇ t and the time constant ⁇ the relationship ⁇ t ⁇ 5 ⁇ meet so that the converter elements can be biased to the required value in good time before the high-voltage pulses occur.
  • a second high-voltage source for generating the bias voltage for the converter elements is provided in the control of the device, the first high-voltage source being connectable to the converter elements via a triggerable switch.
  • the transducer elements can be arranged upright and in a mosaic-like arrangement on a carrier 2 such that, due to the spherical shape of the carrier, the axes of the transducer elements meet at one point, namely in the focus of the transducer. It is therefore a self-focusing version.
  • the transducer elements have contacts at the top on the radiation side, via which they are connected to one another with wires 3 connected to ground.
  • the opposite ends of the transducer elements are connected to the carrier 2 made of electrically conductive material.
  • the carrier is connected to the high voltage sources described later for generating the high voltage pulses and the bias voltage.
  • the transducer elements 1 are located on the underside of the carrier 2, which is connected to ground, so that in this case the opposite carrier side forms the radiation surface.
  • the electrical contacts and connections of the transducer elements to the wires 3 are designed as in the transducer shown in FIG. 7 and connected to the outputs of the high-voltage sources.
  • the transducer elements 1 are fastened on a flat carrier 2, so that the sound pulses emitted by them on parallel axes, if their focusing is necessary, must be focused with an acoustic lens 4.
  • a metallic focusing lens 5 is used in accordance with FIG. 10, separate connecting wires can be omitted, since their function can be taken over by the lens that electrically connects the upper ends of the transducer elements.
  • the other ends of the transducer elements are then connected via the metallic carrier 2, so that here, as in the three previously described transducer types, all transducer elements are electrically connected in parallel.
  • the polarity of the voltages with which the transducer elements are controlled and the polarity of the connections of the transducer elements depend on how they are polarized and whether they are should generate positive pressure impulses or negative train impulses. This is known and therefore need not be explained in more detail.
  • the converter elements 1 can be biased negatively and then controlled with positive high-voltage pulses.
  • the high-voltage source 6 switched negatively with respect to the polarization of the converter elements, the converter elements 1 are biased via the resistor 7 against their polarization direction, the capacitor 8 acting as a separating capacitor for the bias voltage, which in this case should be a permanent DC voltage.
  • the charging capacitor 10 is charged via the further high-voltage source 9.
  • a quick and e.g. Switch 11, designed as a spark gap, is connected at its input 12 to a conventional trigger circuit (not shown). By triggering the switch 11, it is briefly closed, so that the converter elements are driven in the polarization direction with the high voltage present at the charging capacitor 10 in the form of a positive high voltage pulse. Via the resistor 7 and the diode 13, the converter elements are then returned to the state of charge, which is determined by the permanent bias.
  • This circuit works in a corresponding manner if the transducer elements are to be biased positively and negative high-voltage pulses are to be applied in order to be able to generate correspondingly negatively directed acoustic pulses or shock waves. Then only the two high-voltage sources 6 and 9 and the diode 8 with reverse polarity are to be installed in the circuit according to FIG.
  • the bias voltage 14 provided by the high-voltage source 6 is a negative DC voltage.
  • the trigger pulses 15 control the switch 11, so that, as described above, the positive high-voltage pulses 16 are generated, which in this case overdrive the bias voltage 14, so that the curve of the voltage 17 will result on the converter elements, essentially with the curve the deformation and length change 18 of the transducer elements will match when working in the linear range.
  • the negative bias due to the negative bias, a negative offset 18a of the transducer elements and, when a high-voltage pulse 16 arrives, the course 18b of the change in length of the transducer elements occurs.
  • the voltage curves according to FIG. 3 result from a pulse-like form of the negative bias, the bias pulses 19 being terminated essentially simultaneously with the occurrence of the high-voltage pulses 16. This makes additional triggering of the high-voltage source 6 via a switch necessary, in such a way that the bias voltage or bias pulses 19 are generated in time and in relation to the high-voltage pulses 16 as shown in FIG. Then, the curve of the voltage 20 results on the converter elements, which in this case too will at least substantially match the curve of the change in length of the converter elements in and opposite to the radiation direction.
  • the bias 21 is positive.
  • the corresponding high-voltage source is briefly connected to the converter elements via a switch, negative high-voltage pulses 22 being generated which are superimposed on voltage 21. This will result in the curve of the voltage 23 on the converter elements, so that, starting from a positive offset, their length will be suddenly reduced and generate negative or tensile impulses.
  • the positive bias voltage 24 is represented by pulses with which the transducer elements are biased and brought into a positive offset with respect to their neutral initial shape.
  • the trigger pulses 15 can switch off the bias voltage source essentially simultaneously and switch on the high voltage source to emit the negative high voltage pulses 25, so that the course of the voltage 26 will occur on the converter elements.
  • the high voltage source for the high voltage pulses 25 is triggered such that the required bias is applied to the transducer elements before the arrival of the high voltage pulses, which will be the case if the relationship ⁇ t ⁇ 5 ⁇ is satisfied, where ⁇ is the time constant caused by the converter elements connected in parallel and behaving like RC elements.
  • the transducer element Due to the negative bias and the polarization of the transducer element, the transducer element is shortened in length, starting from the contour shown in solid lines, with the formation of a laterally directed bulge 1a, so that a negative offset is produced. As soon as the positive high-voltage pulse arrives, the transducer element expands abruptly with the formation of a lateral constriction 1b and then assumes its initial configuration again. Understandably, this depends on whether a permanent or a pulse-shaped preload is used.
  • the amplitude of the high-voltage pulses will generally be greater than that of the bias voltage, especially if a DC voltage is applied to the converter elements as a bias voltage. Furthermore, certain limits will be imposed on the level of the prestress by the depolarization voltage of the piezoceramic not to be exceeded.
  • all converters are simultaneously subjected to the bias voltage and then to a high-voltage pulse.
  • Piezoelectric ceramics are primarily considered as material for the transducer elements. However, the use of electrostrictive materials is also possible. Finally, the transducer elements can also be designed as a so-called plate stack consist of several stacked piezoceramic plates.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Surgical Instruments (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)

Claims (5)

  1. Appareil pour produire des impulsions acoustiques pour le domaine d'application médical, notamment pour produire des ondes de choc pour irradier des objets situés à l'intérieur d'un corps, et comportant des éléments transducteurs piézocéramiques (1) en tant que transducteurs électroacoustiques, qui peuvent être commandés à partir d'une source de haute tension (9) au moyen d'impulsions à haute tension (16,22,25), de manière à produire, en fonction de la polarisation pré-établie des éléments transducteurs (1) et de la polarité des impulsions de haute tension, des impulsions acoustiques sous l'effet de variations dirigées de longueur des éléments transducteurs (1), caractérisé en ce que, avant l'arrivée d'une impulsion à haute tension (16,22,25), les éléments transducteurs (1) peuvent être excités par une tension de polarisation (14,19,21,24), dont la polarité est opposée à la polarité de l'impulsion à haute tension.
  2. Appareil selon la revendication 1, caractérisé en ce que la tension de polarisation (14,21) est une tension continue permanente, à laquelle sont superposées les impulsions à haute tension (16,22), dont la valeur absolue de tension est plus élevée.
  3. Appareil selon la revendication 1, caractérisé en ce que la tension de polarisation (19,24) est en forme d'impulsions et peut être interrompue chaque fois en même temps, sensiblement, que débute ou arrive une impulsion à haute tension (16,25).
  4. Appareil selon la revendication 3, dans lequel les éléments transducteurs (1) se comportent comme des circuits RC possédant une constante de temps τ ≈ R x C
    Figure imgb0008
    , caractérisé en ce que la durée Δt des impulsions de tension de polarisation (19,24) et la constante de temps τ satisfont la relation Δt ≧ 5τ
    Figure imgb0009
    .
  5. Appareil selon l'une des revendications 1 à 4, caractérisé en ce qu'en dehors de la première source de haute tension mentionnée (9), il est prévu une seconde source de haute tension (6) servant à produire la tension de polarisation (14,19,21,24) et en ce que la première source de haute tension (9) peut être raccordée aux éléments transducteurs (1) par l'intermédiaire d'un interrupteur déclenchable (12).
EP94101427A 1993-03-11 1994-02-01 Dispositif de génération d'impulsions sonores pour des applications médicales Expired - Lifetime EP0614704B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4307669 1993-03-11
DE4307669A DE4307669C2 (de) 1993-03-11 1993-03-11 Gerät zur Erzeugung von Schallimpulsen für den medizinischen Anwendungsbereich

Publications (3)

Publication Number Publication Date
EP0614704A2 EP0614704A2 (fr) 1994-09-14
EP0614704A3 EP0614704A3 (fr) 1994-10-19
EP0614704B1 true EP0614704B1 (fr) 1996-01-24

Family

ID=6482490

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94101427A Expired - Lifetime EP0614704B1 (fr) 1993-03-11 1994-02-01 Dispositif de génération d'impulsions sonores pour des applications médicales

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US (1) US5549110A (fr)
EP (1) EP0614704B1 (fr)
JP (1) JPH06292679A (fr)
DE (2) DE4307669C2 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4433224C1 (de) * 1994-09-17 1996-03-28 Wolf Gmbh Richard Ansteuerschaltung für eine Impulsschallquelle
US5585546A (en) * 1994-10-31 1996-12-17 Hewlett-Packard Company Apparatus and methods for controlling sensitivity of transducers
US5900690A (en) * 1996-06-26 1999-05-04 Gipson; Lamar Heath Apparatus and method for controlling an ultrasonic transducer
DE19733233C1 (de) 1997-08-01 1998-09-17 Wolf Gmbh Richard Elektroakustischer Wandler
FR2830468B1 (fr) * 2001-10-04 2004-02-20 Inst Nat Sante Rech Med Dispositif et procede de production d'impulsions ultrasonores de forte pression
US20230128152A1 (en) * 2021-10-27 2023-04-27 Curative Sound, LLC Handheld focused extracorporeal shock wave therapy device, kit, and method

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1094026B (de) * 1954-03-08 1960-12-01 Raytheon Mfg Co Verfahren und Vorrichtung zur Erzeugung eines kurzen abklingenden Schwingungszuges fuer die Echolotung
JPH0759235B2 (ja) * 1988-01-20 1995-06-28 株式会社東芝 超音波結石破砕用駆動回路
DE8815090U1 (de) * 1988-12-03 1990-02-15 Dornier Medizintechnik GmbH, 8000 München Piezokeramische Stoßwellenquelle
DE3932959C1 (fr) * 1989-10-03 1991-04-11 Richard Wolf Gmbh, 7134 Knittlingen, De
DE4000362C2 (de) * 1990-01-09 1993-11-11 Wolf Gmbh Richard Ultraschallwandler mit piezoelektrischen Wandlerelementen
US5410205A (en) * 1993-02-11 1995-04-25 Hewlett-Packard Company Ultrasonic transducer having two or more resonance frequencies

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Publication number Publication date
EP0614704A2 (fr) 1994-09-14
DE4307669A1 (de) 1994-09-15
JPH06292679A (ja) 1994-10-21
DE4307669C2 (de) 1995-06-29
EP0614704A3 (fr) 1994-10-19
US5549110A (en) 1996-08-27
DE59400093D1 (de) 1996-03-07

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