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EP0390959A2 - Transducteur ultrasonique - Google Patents

Transducteur ultrasonique Download PDF

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Publication number
EP0390959A2
EP0390959A2 EP89106914A EP89106914A EP0390959A2 EP 0390959 A2 EP0390959 A2 EP 0390959A2 EP 89106914 A EP89106914 A EP 89106914A EP 89106914 A EP89106914 A EP 89106914A EP 0390959 A2 EP0390959 A2 EP 0390959A2
Authority
EP
European Patent Office
Prior art keywords
transducer
ultrasonic transducer
transducer element
adaptation
amplitude
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.)
Withdrawn
Application number
EP89106914A
Other languages
German (de)
English (en)
Other versions
EP0390959A3 (fr
Inventor
Neil Dr. Craigie
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.)
CRAIGIE, NEIL, STUART
Original Assignee
CRAIGIE Neil S Dr
Pepperl and Fuchs SE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE19893911047 external-priority patent/DE3911047A1/de
Priority claimed from DE8904225U external-priority patent/DE8904225U1/de
Application filed by CRAIGIE Neil S Dr, Pepperl and Fuchs SE filed Critical CRAIGIE Neil S Dr
Publication of EP0390959A2 publication Critical patent/EP0390959A2/fr
Publication of EP0390959A3 publication Critical patent/EP0390959A3/fr
Withdrawn legal-status Critical Current

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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
    • B06B1/0662—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 with an electrode on the sensitive surface
    • B06B1/0681—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 with an electrode on the sensitive surface and a damping structure
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators

Definitions

  • the invention relates to an ultrasonic transducer according to the preamble of claim 1.
  • Such an ultrasonic transducer is known for example from DE-PS 25 41 492 or DE-PS 34 01 979.
  • the aforementioned known ultrasonic transducers have already shown solutions to the fundamental problem existing in the design of ultrasonic transducers, namely to achieve the highest possible sound pressure and a large sound amplitude with the same energy.
  • the impedance matching problem that exists between the piezo-ceramic transducer element excited to vibrate and the air has been solved relatively satisfactorily by applying a ⁇ / 4 matching body to the piezoceramic transducer element.
  • the acoustic impedance of the matching body was chosen between the impedance of the piezoceramic and that of the air.
  • the original concept of an ultrasonic transducer with a platelet-shaped, piezoceramic transducer element and a ⁇ / 4 adaptation layer bonded thereon is a step in the right direction the main radiation, this ⁇ / 4 adaptation layer is exactly adapted to the piezoceramic transducer element and has, for example, a circular cylindrical shape, a very wide central main lobe in the sound lobe profile with a large number of relatively equally strong side lobes.
  • the solution of the ultrasonic transducer proposed in DE-PS 25 41 492 does provide a ⁇ / 4 layer as the adaptation body.
  • the adaptation body itself has a much larger surface area with the area protruding beyond the edge of the piezoceramic transducer element.
  • a weighting ring spaced from it is bonded to the underside of this protruding area, so to speak at the level of the piezoceramic transducer element.
  • the resulting sound lobe profile shows a relatively narrow central main lobe, which, however, is accompanied by two extremely strong, closely adjacent first side lobes.
  • the solution alternative proposed in DE-PS 34 01 979 provides in a quite comparable manner a ⁇ / 4 adaptation body which is substantially larger in area and which is designed as a ⁇ / 2 oscillator in the area which projects radially beyond the piezoceramic transducer, so to speak.
  • the resulting sound lobe profile is characterized by a relatively strong, central main lobe and several, weaker side lobes.
  • the object of the invention is therefore to design an ultrasonic transducer of the generic type with small dimensions with good radiation characteristics and also to enable simple adaptation options to changed parameters, in particular the frequency.
  • the object is achieved by the features of the characterizing part of claim 1.
  • a fundamental idea of the invention can therefore be seen in the fact that it was not based on an oversizing of the adaptation body on the piezoceramic transducer element, but rather a reorientation towards an ⁇ / 4 adaptation body which was almost identical in diameter as the piezoceramic transducer element.
  • the effective main radiation area or end face of the ⁇ / 4 adaptation body deviates slightly from the main area of the piezoceramic transducer element.
  • the effective radiation area is to be understood as the area up to which there is node in the amplitude diagram of the vertical or thickness vibration of the ⁇ / 4 adaptation body or a phase inversion of the amplitude does not occur.
  • the knowledge that the main surface of the ⁇ / 4 adaptation body facing away from the piezoceramic transducer element is slightly larger or smaller than that bonded onto the piezoceramic transducer element and usually matching surface of the adaptation body.
  • the invention therefore makes use of the knowledge that the actually desired thickness vibration or vertical vibration perpendicular to the main surface of the ultrasonic transducer is superimposed by radial vibrations. These radial vibrations are present above all if the thickness of the ⁇ / 4 adapter body is relatively small in relation to the diameter of the adapter body. This superposition of vertical vibration and radial vibration modes can result in node points or node rings, which result in a smaller effective radiation area.
  • the invention has recognized that the radial vibration modes in the adapter body are very sensitive to the reflection boundary conditions on the lateral peripheral edge of the adapter body. This has the corresponding effect that the vibrations of the ultrasonic transducer can be significantly influenced by small changes in the diameter of the main surface of the adapter body, based on the diameter of the piezoceramic transducer element, and small changes in shape of the peripheral wall of the adapter body. Frequency, modulus of elasticity and Poisson transverse number therefore influence the precise shape of the lateral peripheral wall, the configuration being such that knots form in the Amplitude diagram of the vertical vibration can be avoided.
  • the side line of the peripheral surface of the adapter body is a straight line that diverges or converges, so that the diameter of the main surface of the adapter body deviates slightly from the main surface of the piezoceramic transducer element.
  • the diameter of the main surface of the adapter body facing away from the transducer element can be 32 mm.
  • slightly positive or slightly negative curved side lines are also advantageous in order to achieve a relatively centered high sound pressure.
  • the change in the diameter of the main surface of the adapter body compared to the transducer surface is suitably in the range from 4% to 15%, especially around 6% to 10%.
  • the main surface of the adapter body facing away from it may also have a different contour, especially if the diameter is larger than that of the transducer element.
  • Another possible variation is to make the diameter of the surface of the adapter body bonded to the transducer surface slightly smaller or larger than the piezoceramic transducer surface. For certain frequencies and transducer diameters, this, in combination with the above-mentioned shaping, has a favorable influence on the sound beam profile.
  • the ring transducer consists of a ring-like, piezoceramic transducer element with an inner diameter slightly larger than the largest diameter of the inner adapter body.
  • the ring converter is on the converter element a ring-cylindrical ⁇ / 4 adapter body is bonded, which is usually strictly cylindrical.
  • an ultrasound transducer combined with a ring transducer in comparison to the main area of a single truncated cone-shaped ultrasound transducer, can have a very specific influence on the side lobes by means of a different phase and magnitude ratio between the two transducers. This makes it possible to push back the problematic side lobes even more than is possible with pure truncated cone-shaped transducers and with the known solutions mentioned above.
  • even embodiments open up, e.g. on one side of the sound lobe profile wanted to reach a wide sound field with intense side lobes, while on the other side the side lobes are almost non-existent.
  • the ultrasound transducer shown schematically in axial section in FIG. 1 has a circular cylindrical, plate-shaped piezoceramic transducer element 2, on which a ⁇ / 4 adaptation body 3 is applied.
  • the main radiation direction of this transducer 1 is perpendicular to the upper main surface of the adaptation body.
  • the adapter body 3 is precisely adapted to the transducer element 2 in diameter.
  • Fig. 2a this is at a certain frequency and excitation energy and a certain diameter of the transducer 1 of e.g. 30mm obtained sound beam profile shown in the horizontal plane.
  • This sound lobe profile has a relatively wide, central main lobe 5, which is accompanied on both sides by several strong side lobes 6.
  • FIG. 2 b shows the amplitude diagram of the transducer 1 according to FIG. 1, the amplitude A being plotted on the ordinate as a function of the radius R of the transducer 1.
  • Amplitude A is understood to mean the vertical or thickness vibration of the transducer 1.
  • This problem consists in that there is a phase inversion of the amplitude with the node towards the outer radius R, so that after the point of intersection with the abscissa R there is a negative amplitude up to the maximum radius.
  • This phase reversal of the amplitude which occurs in terms of area as a node ring in the transducer 1, therefore does not produce any sound radiation in the direction of the main radiation direction, but rather represents a loss of energy which can be avoided in any case.
  • FIG. 3a A further ultrasonic transducer 8 according to the prior art is shown in Fig. 3a.
  • This transducer 8 constructed in accordance with DE-PS 25 51 492, has a ⁇ / 4 adapter body 9, which projects significantly beyond the diameter of the piezoelectric transducer element 2.
  • a weighting ring 10 is present on the underside of the adaptation body 9.
  • the amplitude profile of the transducer 8 according to FIG. 3a is shown in FIG. 3c.
  • the maximum, standardized amplitude A can be found in a direction perpendicular to the center of the transducer 8.
  • the sound lobe profile according to FIG. 3b is characterized by a relatively narrow central lobe and two pronounced side lobes.
  • FIG. 4a also shows schematically in axial section the further ultrasonic transducer according to DE-PS 34 01 979.
  • This transducer 12 also comprises a ⁇ / 4 adapter body 13, which acts as a ⁇ / 2 oscillator in the region 14 projecting radially beyond the transducer element 2 is trained.
  • the sound lobe profile according to FIG. 4b shows a main lobe filling the 10 ° range and several, but smaller, side lobes, the difference from FIG. 3b being due to the amplitude distribution (FIG. 4c).
  • the amplitude diagram of the transducer 12 according to FIG. 4a shown in FIG. 4c has, in addition to the main maximum, a further secondary maximum in the region of two thirds of the maximum radius. Between these maximas there is a minimum with almost no amplitude oscillation. In the edge area, however, a phase reversal, albeit slight, has also been found here.
  • an ultrasonic transducer 20 according to the invention is shown in basic section in axial section.
  • a ⁇ / 4 adaptation body 22 is bonded onto the piezoceramic transducer element 21, which is circular, for example.
  • the surface 23 of the transducer element 21 corresponds to the lower surface 24 of the adapter body.
  • the lateral peripheral surface is designed to diverge. This way he there is a horn-like or frustoconical shape for the adaptation body, the main surface 25 facing away from the transducer element 21 has a somewhat larger diameter than the transducer element 21.
  • the side line 26 is therefore a straight line which, for. B. connects a main surface 25 with a diameter of about 32 mm with the main surface 24 of about 30 mm.
  • an amplitude diagram for the thickness or vertical vibration is obtained, taking into account possible superimpositions by the radial vibration, as shown in FIG. 5c.
  • the ordinate A shows the amplitude, based on the maximum amplitude 1.0, as a function of the radius R.
  • the right discontinuity value on the abscissa R therefore characterizes the amplitude at the outer edge of the front main surface 25 of the adaptation body 22 lying in the radiation direction.
  • the maximum of the vertical amplitude lies somewhat radially spaced from the axis of the transducer or the main radiation direction, but avoiding a node or a phase reversal of the amplitude due to the configuration of the lateral peripheral surface in coordination with the diameter of the front main surface becomes.
  • the amplitude distribution therefore approaches that of a rigid piston vibration.
  • this configuration of the ⁇ / 4 adaptation body 22 according to FIG. 5a achieves a central lobe 28 in the region of a 10 ° radiation angle from the main radiation direction 0 with two smaller, but nevertheless noticeable side lobes 29.
  • the advantage of the transducer according to the invention can therefore be seen above all in comparison with the transducer according to the prior art according to FIG. 1 and from the comparison of the corresponding sound diagrams.
  • the minimally changed design configuration of the transducer 20 according to FIG. 5a which, however, largely excludes the formation of a node for the vertical oscillation, results in a much more intensive, more concentrated main lobe 28 in comparison with the central main lobe 5 according to FIG. 2 of the prior art.
  • FIG. 6 shows another ultrasound transducer 40 according to the invention.
  • This transducer 40 is characterized by a piezoceramic transducer element 21, on which a ⁇ / 4 adapter body is applied, which has a convex side line of the peripheral surface in axial section.
  • the same thickness in the radiation direction for the transducer and adapter body and also the same resonance frequency as assumed in the example according to FIG. 5a, this positively curved, convex profile of the side surface is expedient if the transducer element has a smaller diameter, for example, of about 20 mm instead of 30 mm Has.
  • the course of the vertical amplitude is shown in Fig. 6a. Here the amplitude maximum moves further to the edge. However, an amplitude reversal is also avoided here.
  • the combination of a converter according to FIG. 5a with a ring converter 52 shown in FIG. 7a has proven.
  • the entire converter 50 therefore exists from an inner compact transducer 51 with transducer element 21 and ⁇ / 4 adapter body 22.
  • this transducer 51 is surrounded by a ring transducer 52.
  • This ring transducer 52 itself has an annular, piezoelectric transducer element 54, on which a ⁇ / 4 adapter body, for example in the form of a ring cylinder, is applied with the same thickness.
  • these two transducers 51 and 52 can be controlled equally in terms of phase and amount, but can also be controlled differently, this opens up possibilities for influencing the sound beam profile in an excellent manner.
  • One form of this influence is shown in the sound lobe profile shown in FIG. 7c, in which, for example, the side lobes 29, which are still relatively noticeable in FIG. 5b, are pushed back into the now very small side lobes 59.
  • FIG. 7d shows the amplitude diagram of the vertical vibration of the transducer combination 50 according to FIG. 7a.
  • the maximum therefore shifts somewhat closer to the ordinate.
  • This example according to FIG. 7d shows that in the combination of a compact transducer 51 with a ring transducer 52 according to FIG. 7a, a broad spectrum of desired amplitude profiles for the vertical vibration and thus also for the sound beam profile can be set.
  • the invention therefore opens up a new way of being able to achieve extremely effective power or range with partially controllable side lobes even with very small ultrasonic transducers.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Ultra Sonic Daignosis Equipment (AREA)
  • Transducers For Ultrasonic Waves (AREA)
EP19890106914 1989-04-05 1989-04-18 Transducteur ultrasonique Withdrawn EP0390959A3 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE19893911047 DE3911047A1 (de) 1989-04-05 1989-04-05 Ultraschallwandler
DE8904225U DE8904225U1 (de) 1989-04-05 1989-04-05 Ultraschallwandler
DE3911047 1989-04-05
DE8904225U 1989-04-05

Publications (2)

Publication Number Publication Date
EP0390959A2 true EP0390959A2 (fr) 1990-10-10
EP0390959A3 EP0390959A3 (fr) 1991-10-09

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ID=25879561

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890106914 Withdrawn EP0390959A3 (fr) 1989-04-05 1989-04-18 Transducteur ultrasonique

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EP (1) EP0390959A3 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994005004A1 (fr) * 1992-08-13 1994-03-03 Siemens Aktiengesellschaft Transducteur ultrasonore
WO1997047403A1 (fr) * 1996-06-10 1997-12-18 Siemens Aktiengesellschaft Transducteur ultrasonique

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2956184A (en) * 1954-11-01 1960-10-11 Honeywell Regulator Co Transducer
US3915018A (en) * 1974-11-21 1975-10-28 Us Energy Transition section for acoustic waveguides
DE2541492C3 (de) * 1975-09-17 1980-10-09 Siemens Ag, 1000 Berlin Und 8000 Muenchen Ultraschallwandler
US4333028A (en) * 1980-04-21 1982-06-01 Milltronics Ltd. Damped acoustic transducers with piezoelectric drivers
US4735096A (en) * 1986-08-27 1988-04-05 Xecutek Corporation Ultrasonic transducer

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994005004A1 (fr) * 1992-08-13 1994-03-03 Siemens Aktiengesellschaft Transducteur ultrasonore
US5659220A (en) * 1992-08-13 1997-08-19 Siemens Aktiengesellschaft Ultrasonic transducer
WO1997047403A1 (fr) * 1996-06-10 1997-12-18 Siemens Aktiengesellschaft Transducteur ultrasonique
US6122970A (en) * 1996-06-10 2000-09-26 Siemens Ag Ultrasonic transducer

Also Published As

Publication number Publication date
EP0390959A3 (fr) 1991-10-09

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